National Library of Energy BETA

Sample records for microbiol mol biol

  1. Riddhi Siddhi Gluco Biols Ltd RSGBL | Open Energy Information

    OpenEI (Open Energy Information) [EERE & EIA]

    Place: 591307, Karnataka, India Sector: Biomass Product: Karnataka-based starch and glucose manufacturer and biomass project developers. References: Riddhi Siddhi Gluco Biols...

  2. MOL.19980331.0174 PARTICULATE MATTEX AMBIENT A I R QUALITY

    National Nuclear Security Administration (NNSA)

    MOL.19980331.0174 PARTICULATE MATTEX AMBIENT A I R QUALITY DATA REPORT FOR 1989 AND 1990 ... Applications International Corporation Technical & Management Support Services Las Vegas, ...

  3. Phase transformation and wear studies of plasma sprayed yttria stabilized zirconia coatings containing various mol% of yttria

    SciTech Connect

    Aruna, S.T. Balaji, N.; Rajam, K.S.

    2011-07-15

    Plasma sprayable grade zirconia powders doped with various mol% of yttria (0, 2, 3, 4, 6, 8 and 12 mol%) were synthesized by a chemical co-precipitation route. The coprecipitation conditions were adjusted such that the powders possessed good flowability in the as calcined condition and thus avoiding the agglomeration step like spray drying. Identical plasma spray parameters were used for plasma spraying all the powders on stainless steel plates. The powders and plasma sprayed coatings were characterized by X-ray diffractometry, Scanning Electron Microscopy and Raman spectroscopy. Zirconia powders are susceptible to phase transformations when subjected to very high temperatures during plasma spraying and XRD is insensitive to the presence of some non crystalline phases and hence Raman spectroscopy was used as an important tool. The microstructure of the plasma sprayed coatings showed a bimodal distribution containing fully melted and unmelted zones. The microhardness and wear resistance of the plasma sprayed coatings were determined. Among the plasma sprayed coatings, 3 mol% yttria stabilized zirconia coating containing pure tetragonal zirconia showed the highest wear resistance. - Research Highlights: {yields} Preparation plasma sprayable YSZ powders without any agglomeration process and plasma spraying {yields} Phase transformation studies of plasma sprayed YSZ coatings by XRD and Raman spectroscopy {yields} Microstructure of the plasma sprayed coatings exhibited bimodal distribution {yields} Plasma sprayed 3 mol% YSZ coating exhibited the highest wear resistance {yields} Higher wear resistance is due to the higher fracture toughness of tetragonal 3 mol% YSZ phase.

  4. mol2.3.dvi

    Office of Scientific and Technical Information (OSTI)

    These well-defined systems provide a new way to study the Kondo effect on the nanoscale, ... These results not only provide a new arena for studying the Kondo effect on the nanoscale, ...

  5. mol2.3.dvi

    Office of Scientific and Technical Information (OSTI)

    Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 2 Department of Chemistry, University of California, Berkeley, California 94720, USA (Dated: Phys. Rev. ...

  6. Structure and optical homogeneity of LiNbO{sub 3}:Zn (0.03–4.5 mol.%) crystals

    SciTech Connect

    Sidorov, Nikolay E-mail: tepl-na@chemy.kolasc.net.ru E-mail: Jovial1985@yandex.ru Tepljakova, Natalja E-mail: tepl-na@chemy.kolasc.net.ru E-mail: Jovial1985@yandex.ru Gabain, Aleksei E-mail: tepl-na@chemy.kolasc.net.ru E-mail: Jovial1985@yandex.ru Yanichev, Aleksander E-mail: tepl-na@chemy.kolasc.net.ru E-mail: Jovial1985@yandex.ru Palatnikov, Mikhail E-mail: tepl-na@chemy.kolasc.net.ru E-mail: Jovial1985@yandex.ru

    2014-11-14

    Structure and optical homogeneity of LiNbO{sub 3}:Zn (0.03–4.5 mol.%) crystals were searched by photoinduced light scattering and by Raman spectroscopy. The photorefractive effect depends on Zn{sup 2+} concentration nonmonotonically. Decrease of photorefractive effect is explained by decrease of structure defects with localized electrons. The Zn{sup 2+} cations replace structure defects Nb{sub Li} and Li{sub Nb}, trapping levels appear near the bottom of the conduction band and photo electrons recombine with emission under laser radiation. By the Raman spectra the area of the high structure order is found. In this area the own alternation, the alternation of impurity cations and the vacancies along the polar axis is almost perfect.

  7. Microsoft Word - MolJACSrev28.doc

    Office of Scientific and Technical Information (OSTI)

    ... were stirred overnight. The green-yellow solution was then taken to dryness ... an unfocused, uncollimated beam with energy resolution (< 0.7 eV) far narrower than ...

  8. Microsoft Word - MolJACSrev28.doc

    Office of Scientific and Technical Information (OSTI)

    Lawrence Berkeley National Laboratory, Berkeley, California 94720, Department of Chemistry, University of California, Berkeley, California 94720, Nuclear Sciences Division, ...

  9. Disruption of Wnt/[beta]-Catenin Signaling and Telomeric Shortening...

    Office of Scientific and Technical Information (OSTI)

    Disruption of Wntbeta-Catenin Signaling and Telomeric Shortening Are Inextricable ... Resource Type: Journal Article Resource Relation: Journal Name: Mol. Cell Biol.; Journal ...

  10. Final Technical Report

    Office of Scientific and Technical Information (OSTI)

    ... Biophys. Mol. Biol. 89:292-329. Pereira, LA., A. R. Ramos, F. Grein, M.C. Marques, S.M. da Silva, and S.S. Venceslau. (2011) A comparative genomic analysis of energy metabolism in ...

  11. Crystal Structure and Functional Analysis Identify Evolutionary...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... M. Guo, X. L. Yang, and P. Schimmel, "New Functions of Aminoacyl-tRNA Synthetases Beyond Translation", Nat. Rev. Mol. Cell Biol. 11, 668 (2010) A. Amsterdam, R. M. Nissen, Z. Sun, ...

  12. Broad Temperature Pinning Study of 15 mol.% Zr-Added (Gd, Y)-Ba-Cu-O MOCVD Coated Conductors

    SciTech Connect

    Xu, AX; Khatri, N; Liu, YH; Majkic, G; Galstyan, E; Selvamanickam, V; Chen, YM; Lei, CH; Abraimov, D; Hu, XB; Jaroszynski, J; Larbalestier, D

    2015-06-01

    BaZrO3 (BZO) nanocolumns have long been shown to be very effective for raising the pinning force F-p of REBa2Cu3Ox (REBCO, where RE = rare earth) films at high temperatures and recently at low temperatures too. We have successfully incorporated a high density of BZO nanorods into metal organic chemical vapor deposited (MOCVD) REBCO coated conductors via Zr addition. We found that, compared to the 7.5% Zr-added coated conductor, dense BZO nanorod arrays in the 15% Zr-added conductor are effective over the whole temperature range from 77 K down to 4.2 K. We attribute the substantially enhanced J(c) at 30 K to the weak uncorrelated pinning as well as the strong correlated pinning. Meanwhile, by tripling the REBCO layer thickness to similar to 2.8 mu m, the engineering critical current density J(e) at 30 K exceeds J(e) of optimized Nb-Ti wires at 4.2 K.

  13. Threshold Photoelectron Photoion Coincidence (TPEPICO) Studies: The Road to ? 0.1 kJ/mol Thermochemistry

    SciTech Connect

    Baer, Tomas

    2013-10-14

    The threshold photoelectron photoion coincidence (TPEPICO) technique is utilized to investigate the dissociation dynamics and thermochemistry of energy selected medium to large organic molecular ions. The reactions include parallel and consecutive steps that are modeled with the statistical theory in order to extract dissociation onsets for multiple dissociation paths. These studies are carried out with the aid of molecular orbital calculations of both ions and the transition states connecting the ion structure to their products. The results of these investigations yield accurate heats of formation of ions, free radicals, and stable molecules. In addition, they provide information about the potential energy surface that governs the dissociation process. Isomerization reactions prior to dissociation are readily inferred from the TPEPICO data.

  14. pH- and mol-ratio dependent formation of zinc(II) coordination polymers with iminodiacetic acid: Synthesis, spectroscopic, crystal structure and thermal studies

    SciTech Connect

    Ni Lubin; Zhang Ronghua; Liu Qiongxin; Xia Wensheng; Wang Hongxin; Zhou Zhaohui

    2009-10-15

    Three novel zinc coordination polymers (NH{sub 4}){sub n}[Zn(Hida)Cl{sub 2}]{sub n} (1), [Zn(ida)(H{sub 2}O){sub 2}]{sub n} (2), [Zn(Hida){sub 2}]{sub n}.4nH{sub 2}O (3) (H{sub 2}ida=iminodiacetic acid) and a monomeric complex [Zn(ida)(phen)(H{sub 2}O)].2H{sub 2}O (4) (phen=1,10-phenanthroline) have been synthesized and characterized by X-ray diffraction methods. 1 and 2 form one-dimensional (1-D) chain structures, whereas 3 exhibits a three-dimensional (3-D) diamondoid framework with an open channel. The mononuclear complex 4 is extended into a 3-D supramolecular architecture through hydrogen bonds and pi-pi stacking. Interestingly, cyclic nonplanar tetrameric water clusters are observed that encapsulated in the 3-D lattice of 4. Based on {sup 1}H and {sup 13}C NMR observations, there is obvious coordination of complex 2 in solution, while 1 and 3 decompose into free iminodiacetate ligand. Monomer [Zn(ida)(H{sub 2}O){sub 3}] (5) is considered as a possible discrete species from 2. These coordination polymers can serve as good molecular precursors for zinc oxide. - Text3: Reaction of zinc salt with iminodiacetic acid afforded three new coordination polymers 1-3 and a monomer 4, which is dependent on pH value and molar ratio of the reactants.

  15. High quality permanent draft genome sequence of Phaseolibacter flectens ATCC 12775T, a plant pathogen of French bean pods

    DOE PAGES [OSTI]

    Aizenberg-Gershtein, Yana; Izhaki, Ido; Lapidus, Alla; Copeland, Alex; Reddy, TBK; Huntemann, Marcel; Pillay, Manoj; Markowitz, Victor; Göker, Markus; Woyke, Tanja; et al

    2016-01-13

    We report that the Phaseolibacter flectens strain ATCC 12775T (Halpern et al., Int J Syst Evol Microbiol 63:268–273, 2013) is a Gram-negative, rod shaped, motile, aerobic, chemoorganotroph bacterium. Ph. flectens is as a plant-pathogenic bacterium on pods of French bean and was first identified by Johnson (1956) as Pseudomonas flectens. After its phylogenetic position was reexamined, Pseudomonas flectens was transferred to the family Enterobacteriaceae as Phaseolibacter flectens gen. nov., comb. nov. Here we describe the features of this organism, together with the draft genome sequence and annotation. The DNA GC content is 44.34 mol%. The chromosome length is 2,748,442 bp.more » It encodes 2,437 proteins and 89 RNA genes. Ph. flectens genome is part of the Genomic Encyclopedia of Type Strains, Phase I: the one thousand microbial genomes study.« less

  16. Microsoft Word - MnO_Reduction bh

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... References 1. B. M. Tebo, H. A. Johnson, J. K. McCarthy and A. S. Templeton, "Geomicrobiology of Manganese(II) Oxidation", Trends Microbiol. 13, 9 (2005). 2. C. R. Myers, and K. H. ...

  17. Measuring Real-time Biological and Abiotic Manganese Oxide Reduction...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... B. M. Tebo, H. A. Johnson, J. K. McCarthy and A. S. Templeton, "Geomicrobiology of Manganese(II) Oxidation", Trends Microbiol. 13, 9 (2005). C. R. Myers, and K. H. Nealson, ...

  18. Microbes as Engines of Ecosystem Function: When Does Community...

    Office of Scientific and Technical Information (OSTI)

    ... Primers for overlooked nirK, qnorB, and nosZ genes of thermophilic Gram-positive denitrifiers. FEMS Microbiol. Ecol. 89, 162-180. doi: 10.11111574-6941.12346 Wagg, C., Bender, S. ...

  19. Microsoft Word - Maeder et al.doc

    Office of Scientific and Technical Information (OSTI)

    ... molecular nitrogen (Bomar and Knoll 1985; Lobo and Zinder 1988). 73 They also adapt to ... Syst. Appl. Microbiol. 7: 293-299. 494 Lobo, A.L. and S.H. Zinder. 1988. Diazotrophy and ...

  20. RESEARCH ARTICLE

    Office of Scientific and Technical Information (OSTI)

    ... Both vectors have a lacUV5 promoter and kanamycin resistance marker, but the replication ... Microbiol. 76: 1935-1945. http:dx.doi.org10.1128AEM.02323-09. 15. Zingaro KA, Terry ...

  1. Insights into Methyltransferase Specificity and Bioactivity of...

    Office of Scientific and Technical Information (OSTI)

    OSTI Identifier: 1182773 Resource Type: Journal Article Resource Relation: Journal Name: ACS Chem. Biol.; Journal Volume: 10; Journal Issue: (5) ; 05, 2015 Research Org: Advanced ...

  2. Memo Is Homologous to Nonheme Iron Dioxygenases and Binds an...

    Office of Scientific and Technical Information (OSTI)

    Affiliations (JHU-MED) ( Publication Date: 2008-04-02 OSTI Identifier: 1006524 Resource Type: Journal Article Resource Relation: Journal Name: J. Biol. Chem.; Journal Volume: ...

  3. Native Chemical Ligation in Covalent Caspase Inhibition by p35...

    Office of Scientific and Technical Information (OSTI)

    Weill-Med Publication Date: 2015-10-15 OSTI Identifier: 1223965 Resource Type: Journal Article Resource Relation: Journal Name: Chem. Biol.; Journal Volume: 13; Journal Issue: 2 ...

  4. Structural and Biochemical Analysis of DNA Helix Invasion by...

    Office of Scientific and Technical Information (OSTI)

    (Harvard-Med) ( Publication Date: 2013-07-26 OSTI Identifier: 1087764 Resource Type: Journal Article Resource Relation: Journal Name: J. Biol. Chem.; Journal Volume: ...

  5. Structure-Function Analyses of the Interactions between Rab11...

    Office of Scientific and Technical Information (OSTI)

    OSTI Identifier: 1208687 Resource Type: Journal Article Resource Relation: Journal Name: J. Biol. Chem.; Journal Volume: 290; Journal Issue: (30) ; 07, 2015 Research Org: Advanced ...

  6. J.B. (comp.) 63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT...

    Office of Scientific and Technical Information (OSTI)

    AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; 62 RADIOLOGY AND NUCLEAR MEDICINE; 99 GENERAL AND MISCELLANEOUSMATHEMATICS, COMPUTING, AND INFORMATION...

  7. Genome Wide Evaluation of Normal Human Tissue in Response to...

    Office of Scientific and Technical Information (OSTI)

    Subject: 63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; 61 RADIATION PROTECTION AND DOSIMETRY Low-dose radiation; gene expression Word ...

  8. Alterations of intermolecular disulfides in the insulin receptor...

    Office of Scientific and Technical Information (OSTI)

    Biol.; (United States); Journal Volume: 45:6; Conference: 76. annual meeting of the Federation of American Society for ... ANTIMITOTIC DRUGS; CHEMICAL REACTIONS; DRUGS; ...

  9. Possible bias in tree-ring time series due to mortality (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: 54 ENVIRONMENTAL SCIENCES; 63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; TREE RINGS; TIME-SERIES ANALYSIS; AIR POLLUTION; ...

  10. Helix Dipole Movement and Conformational Variability Contribute to Allosteric GDP Release in G[alpha] Subunits

    SciTech Connect

    Preininger, Anita M.; Funk, Michael A.; Oldham, William M.; Meier, Scott M.; Johnston, Christopher A.; Adhikary, Suraj; Kimple, Adam J.; Siderovski, David P.; Hamm, Heidi E.; Iverson, Tina M.

    2009-06-01

    Heterotrimeric G proteins (Galphabetagamma) transmit signals from activated G protein-coupled receptors (GPCRs) to downstream effectors through a guanine nucleotide signaling cycle. Numerous studies indicate that the carboxy-terminal alpha5 helix of Galpha subunits participates in Galpha-receptor binding, and previous EPR studies suggest this receptor-mediated interaction induces a rotation and translation of the alpha5 helix of the Galpha subunit [Oldham, W. M., et al. (2006) Nat. Struct. Mol. Biol. 13, 772-777]. On the basis of this result, an engineered disulfide bond was designed to constrain the alpha5 helix of Galpha(i1) into its EPR-measured receptor-associated conformation through the introduction of cysteines at position 56 in the alpha1 helix and position 333 in the alpha5 helix (I56C/Q333C Galpha(i1)). A functional mimetic of the EPR-measured alpha5 helix dipole movement upon receptor association was additionally created by introduction of a positive charge at the amino terminus of this helix, D328R Galpha(i1). Both proteins exhibit a dramatically elevated level of basal nucleotide exchange. The 2.9 A resolution crystal structure of I56C/Q333C Galpha(i1) in complex with GDP-AlF(4)(-) reveals the shift of the alpha5 helix toward the guanine nucleotide binding site that is anticipated by EPR measurements. The structure of the I56C/Q333C Galpha(i1) subunit further revealed altered positions for the switch regions and throughout the Galpha(i1) subunit, accompanied by significantly elevated crystallographic temperature factors. Combined with previous evidence in the literature, the structural analysis supports the critical role of electrostatics of the alpha5 helix dipole and overall conformational variability during nucleotide release.

  11. Title:

    Office of Scientific and Technical Information (OSTI)

    ... Phys Med Biol 1984; 29: 1537-1554. 8 . ' 21. Mijnheer BJ, Wootton P, Williams JR, Eenma J, Pamell, CJ. Uniformity in dosimetry protocols for therapeutic applications of fast ...

  12. November 11, 1997

    Office of Scientific and Technical Information (OSTI)

    ... J. Oncology Biol. Phys. 21 37- 58 (1991). 3 K. Ayyangar, J. R. Palta, J. W. Sweet, and N. Suntharalingam,Med. Phys. 21 (2) 325-329 (1993). 4 C. Hurkmans, T. Kns, R. Nilsson, G. ...

  13. 2010 Publications | Stanford Synchrotron Radiation Lightsource

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... Lesley and I. A. Wilson, "Conformational Changes Associated with the Binding of Zinc ... of Amyloid b-related Behavioral Deficits in a Mouse Model of Alzheimer Disease", J. Biol. ...

  14. The Gut Microbiota of Rural Papua New Guineans: Composition,...

    Office of Scientific and Technical Information (OSTI)

    ... from stochastic processes across scales. Philos. Trans. R. Soc. Lond. B Biol. Sci. 366, 2351-2363. Chase, J.M., Kraft, N.J.B., Smith, K.G., Vellend, M., and Inouye, B.D. (2011). ...

  15. DOE_/10630--29 DE92

    National Nuclear Security Administration (NNSA)

    ... Bull., Biol., Ser. 6(3):1-81. I Jorgensen, C. D., H. D. Smith and J. R. Garcia. 1980. ... Nevada 89193-8521 (1) O Gayle Smith P. O. Box 26569 Las Vegas, Nevada 89126 (I) Dr'. ...

  16. ULTRAVIOLET PHOTOPRODUCTS IN ORDERED STRUCTURES OF POLY U AND...

    Office of Scientific and Technical Information (OSTI)

    Biol., 27: 131-44(July 14, 1967).; Other Information: Orig. Receipt Date: 31-DEC-68; Bib. Info. Source: DIX (Henry Dix) Research Org: Univ. of Toronto Sponsoring Org: USDOE Country ...

  17. Low-melting point heat transfer fluid

    DOEpatents

    Cordaro, Joseph Gabriel; Bradshaw, Robert W.

    2010-11-09

    A low-melting point, heat transfer fluid made of a mixture of five inorganic salts including about 29.1-33.5 mol % LiNO.sub.3, 0-3.9 mol % NaNO.sub.3, 2.4-8.2 mol % KNO.sub.3, 18.6-19.9 mol % NaNO.sub.2, and 40-45.6 mol % KNO.sub.2. These compositions can have liquidus temperatures below 80.degree. C. for some compositions.

  18. Analysis of Metabolic Pathways and Fluxes in a Newly Discovered...

    Office of Scientific and Technical Information (OSTI)

    a maximum ethanol yield of 0.38+-0.07 mol mol-1 more glucose. In silico flux balance modeling demonstrates that lactate and acetate production from G. thermoglucosidasius...

  19. Forensic analysis of the microbiome of phones and shoes

    Office of Scientific and Technical Information (OSTI)

    Georgia Barguil Colares4, Daniel Smith1,5, Jonathan A Eisen6,7,8 and Jack A ... Genome Biol. 2013, 14. doi:10.1186gb-2013-14-2-202. 2. Lax S, Smith DP, Hampton-Marcell ...

  20. Hungary petroleum privatization limited by economic concerns

    SciTech Connect

    Not Available

    1994-07-04

    Once the leading economic hope of eastern Europe, a newly doubt-filled, postelection Hungary is deciding on limited oil privatization amid strategic worries and falling production. Those worries contrast with the bright promise seen in Hungary after the collapse of communism. The paper discusses energy supplies; profile of the former petroleum monopoly, Magyar Olaj es Gaz (MOL); the state owned Mineralimpex; strategic supplies; MOL privatization; post-election politics; and MOL's subsidiaries.

  1. 2014 Publications | Stanford Synchrotron Radiation Lightsource

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... Speciation, Collective Behavior, Nanoscale Heterogeneity, ... "Enhanced Photovoltaic Performance of Indacenodithiophene-Q... "Structural and Functional Analysis of Human SIRT1", J. Mol. ...

  2. ORGANIC SPECIES IN GEOTHERMAL WATERS IN LIGHT OF FLUID INCLUSION...

    OpenEI (Open Energy Information) [EERE & EIA]

    that indicate H2 concentrations > 0.001 mol % typically have ethane > ethylene, propane > propylene, and butane > butylene. There are three end member fluid compositions:...

  3. Fluid Inclusion Analysis At Coso Geothermal Area (2003) | Open...

    OpenEI (Open Energy Information) [EERE & EIA]

    that indicate H2 concentrations > 0.001 mol % typically have ethane > ethylene, propane > propylene, and butane > butylene. There are three end member fluid compositions...

  4. Li corrosion resistant glasses for headers in ambient temperature Li batteries

    DOEpatents

    Hellstrom, E.E.; Watkins, R.D.

    1985-10-11

    Glass compositions containing 10 to 50 mol% CaO, 10 to 50 mol% Al/sub 2/O/sub 3/, 30 to 60 mol% B/sub 2/O/sub 3/, and 0 to 30 mol% MgO are provided. These compositions are capable of forming a stable glass-to-metal seal possessing electrical insulating properties for use in a lithium battery. Also provided are lithium cells containing a stainless steel body and molybdenum center pin electrically insulated by means of a seal produced according to the invention.

  5. Promoting uranium immobilization by the activities of microbial phophatases

    SciTech Connect

    Sobecky, Patricia A.

    2005-06-01

    The first objective of this project is to determine the relationship of phosphatase activity to metal resistance in subsurface strains and the role of lateral gene transfer (LGT) in dissemination of nonspecific acid phosphatase genes. Nonspecific acid phosphohydrolases are a broad group of secreted microbial phosphatases that function in acidic-to-neutral pH ranges and utilize a wide range of organophosphate substrates. We have previously shown that PO43- accumulation during growth on a model organophosphorus compound was attributable to the overproduction of alkaline phosphatase by genetically modified subsurface pseudomonads [Powers et al. (2002) FEMS Microbiol. Ecol. 41:115-123]. During this report period, we have extended these results to include indigenous metal resistant subsurface microorganisms cultivated from the Field Research Center (FRC), in Oak Ridge Tennessee.

  6. Anaerobic Biotransformation and Mobility of Pu and PuEDTA

    SciTech Connect

    Xun, Luying

    2005-06-01

    Although our goal is to isolate anaerobic EDTA degraders, we initiated the experiments to include nitrilotriacetate (NTA), which is a structure homologue of EDTA. All the aerobic EDTA degraders can degrade NTA, but the isolated NTA degraders cannot degrade EDTA. Since NTA is a simpler structure homologue, it is likely that EDTA-degrading ability is evolved from NTA degradation. This hypothesis is further supported from our characterization of EDTA and NTA-degrading enzymes and genes (J. Bact. 179:1112-1116; and Appl. Environ. Microbiol. 67:688-695). The EDTA monooxygenase and NTA monooxygenase are highly homologous. EDTA monooxygenase can use both EDTA and NTA as substrates, but NTA monooxygenase can only use NTA as a substrate. Thus, we put our effort to isolate both NTA and EDTA degraders. In case, an anaerobic EDTA degrader is not immediately enriched, we will try to evolve the NTA degraders to use EDTA. Both aerobic and anaerobic enrichment cultures were set.

  7. Native Chemical Ligation in Covalent Caspase Inhibition by p35 (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Native Chemical Ligation in Covalent Caspase Inhibition by p35 Citation Details In-Document Search Title: Native Chemical Ligation in Covalent Caspase Inhibition by p35 Authors: Lu, Miao ; Min, Tongpil ; Eliezer, David ; Wu, Hao [1] + Show Author Affiliations Weill-Med Publication Date: 2015-10-15 OSTI Identifier: 1223965 Resource Type: Journal Article Resource Relation: Journal Name: Chem. Biol.; Journal Volume: 13; Journal Issue: 2 Research Org: Advanced Photon

  8. Metal-air cell comprising an electrolyte with a room temperature ionic liquid and hygroscopic additive

    DOEpatents

    Friesen, Cody A.; Krishnan, Ramkumar; Tang, Toni; Wolfe, Derek

    2014-08-19

    An electrochemical cell comprising an electrolyte comprising water and a hydrophobic ionic liquid comprising positive ions and negative ions. The electrochemical cell also includes an air electrode configured to absorb and reduce oxygen. A hydrophilic or hygroscopic additive modulates the hydrophobicity of the ionic liquid to maintain a concentration of the water in the electrolyte is between 0.001 mol % and 25 mol %.

  9. Silicon nitride ceramic having high fatigue life and high toughness

    DOEpatents

    Yeckley, Russell L.

    1996-01-01

    A sintered silicon nitride ceramic comprising between about 0.6 mol % and about 3.2 mol % rare earth as rare earth oxide, and between about 85 w/o and about 95 w/o beta silicon nitride grains, wherein at least about 20% of the beta silicon nitride grains have a thickness of greater than about 1 micron.

  10. Homoacetogenic fermentation of cellulose by a coculture of Clostridium thermocellum and Acetogenium kivui

    SciTech Connect

    Le Ruyet, P.; Dubourguier, H.C.; Albagnac, G.

    1984-10-01

    Interrelationships between methanogens and fermentative or hydrolytic bacteria are well documented; however, such cocultures do not allow a complete fermentation shift to a peculiar metabolite. A new stable association between Clostridium thermocellum and Acetogenium kivui is described which converts 1 mol of cellulose (anhydroglucose equivalent) into a 2.7 mol of acetate.

  11. Low-melting point heat transfer fluid

    DOEpatents

    Cordaro, Joseph G.; Bradshaw, Robert W.

    2011-04-12

    A low-melting point, heat transfer fluid comprising a mixture of LiNO.sub.3, NaNO.sub.3, KNO.sub.3, NaNO.sub.2 and KNO.sub.2 salts where the Li, Na and K cations are present in amounts of about 20-33.5 mol % Li, about 18.6-40 mol % Na, and about 40-50.3 mol % K and where the nitrate and nitrite anions are present in amounts of about 36-50 mol % NO.sub.3, and about 50-62.5 mol % NO.sub.2. These compositions can have liquidus temperatures between 70.degree. C. and 80.degree. C. for some compositions.

  12. Solubility Measurements of Crystalline NiO in Aqueous Solution as a Function of Temperature and pH

    SciTech Connect

    Palmer, Donald; Benezeth, Pascale; Xiao, Caibin {nmn}; Wesolowski, David J; Anovitz, Lawrence {Larry} M

    2011-01-01

    Abstract Results of solubility experiments involving crystalline nickel oxide (bunsenite) in aqueous solutions are reported as functions of temperature (0 to 350 C) and pH at pressures slightly exceeding (with one exception) saturation vapor pressure. These experiments were carried out in either flow-through reactors or a hydrogen-electrode concentration cell for mildly acidic to near neutral pH solutions. The results were treated successfully with a thermodynamic model incorporating only the unhydrolyzed aqueous nickel species (viz., Ni2+ ) and the neutrally charged hydrolyzed species (viz., Ni(OH)02 ). The thermodynamic quantities obtained at 25 C and infinite dilution are, with 2 uncertainties: log10Ko s0 = (12.40 0.29), rGo m = (70.8 1.7) kJ mol 1; rHo m = (105.6 1.3) kJ mol 1; rSo m = (116.6 3.2) J K 1 mol 1; rCo p,m = (0 13) J K 1 mol 1; and log10Ko s2 = (8.76 0.15); rGo m = (50.0 1.7) kJ mol 1; rHo m = (17.7 1.7) kJ mol 1; rSo m = (108 7) J K 1 mol 1; rCo p,m = (108 3) J K 1 mol 1. These results are internally consistent, but the latter set differs from those gleaned from previous studies recorded in the literature. The corresponding thermodynamic quantities for the formation of Ni2+ and Ni(OH)02 are also estimated. Moreover, the Ni(OH) 3 anion was never observed, even in relatively strong basic solutions (mOH = 0.1 mol kg 1), contrary to the conclusions drawn from all but one previous study.

  13. LPG--a direct source of C/sub 3/-C/sub 4/ olefins

    SciTech Connect

    Pujado, P.R.; Berg, R.C.; Vora, B.V.

    1983-03-28

    This article describes the selective production of olefins by the catalytic dehydrogenation of the corresponding paraffins by means of UOP's Oleflex process. In this process, propylene can be obtained at about 85 mol % selectivity by the catalytic dehydrogenation of propane. Isobutylene can be obtained at selectivities in excess of 90 mol % from isobutane, and n-butenes (1-butene plus 2-butene) at about 80 mol % from n-butane. The availability of this technology, coupled with an abundant supply of LPG (C/sub 3/ and C/sub 4/ paraffins), opens new avenues for the selective production of propylene and butylenes.

  14. Info Capabilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    MOL PCR A nucleic acid based assay chemistry that uses microsphere arrays and flow/image cytometry for the detection of human and pathogen biomarkers. LAUR: 16-22527 Benefits/Features Multiple Markers per Sample- (MOL-PCR) has the ability to simultaneously ask more than one question about a sample at the same time, and the ability to conduct more than one test on a sample in the same reaction. Broad Array of Applications- (MOL-PCR) provides genotyping for genetic susceptibility to disease and

  15. Crystal Structure of Cascade | Stanford Synchrotron Radiation...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    486 (2011). Y. Savir and T. Tlusty, "RecA-Mediated Homology Search as a Nearly Optimal Signal Detection System", Mol Cell 40, 388 (2010). Z. Chen, H. Yang, N. P. Pavletich,...

  16. Effect of co-doped SnO{sub 2} nanoparticles on photoluminescence of cu-doped potassium lithium borate glass

    SciTech Connect

    Namma, Haydar Aboud; Wagiran, H.; Hussin, R.; Ariwahjoedi, B.

    2012-09-26

    The SnO{sub 2} co-doped lithium potassium borate glasses doped with 0.05, 0.10, 0.25 and 0.50 mol% of Cu were synthesized by the melt quenching technique. The SnO{sub 2} co-dope was added to the compounds in the amounts of 0.05, 0.10, and 0.20 mol%. The photoluminescent spectrum for different concentrations of copper was studied. It was observed that the intensity of blue emission (450, 490 nm) varies with concentration mol%. In addition, with different concentration of SnO{sub 2} to 0.10 mol% Cu, the influence of the luminescence has been observed to enhance intensity and shifted to blue and red (490, 535 nm) emissions.

  17. RussiaSNL2-web.indd

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... with angle 81,78680, Plane (111) and planar 7. a b c d Modifi ed for the Web Visualizers Futures MolDraw ACDStructure Drawing Applet MW3D Crystal Lab Crystal Studio ...

  18. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Office of Science (SC) (United States) USDOE Office of Worker ... Hsub 2 production rate of 46.6 mol hsup -1 in ... breathing rate increases were not accompanied by death. ...

  19. TITLE AUTHORS SUBJECT SUBJECT RELATED DESCRIPTION PUBLISHER AVAILABILI...

    Office of Scientific and Technical Information (OSTI)

    with an exchangeable proton is eventually formed We have determined the bond dissociation free energy and pKa of the new O H bond in to be kcal mol and respectively in CH CN...

  20. Mechanistic Insight into the Formation of Cationic Naked Nanocrystals

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Generated Under Equilibrium Control - Joint Center for Energy Storage Research October 24, 2014, Research Highlights Mechanistic Insight into the Formation of Cationic Naked Nanocrystals Generated Under Equilibrium Control Pre-JCESR stripping chemistries (for cationic NC): NOBF4 (strong oxidant, not suitable for many compositions, ~$600/mol) Et3OBF4 (mild, but still causes adatom desorption for some sensitive compositions, ~$800/mol) New ligand-stripping chemistry developed within JCESR:

  1. Spectroscopic properties of erbium-doped yttria-stabilised zirconia crystals

    SciTech Connect

    Ryabochkina, P A; Sidorova, N V; Ushakov, S N; Lomonova, E E

    2014-02-28

    Yttria-stabilised zirconia crystals ZrO{sub 2} Y{sub 2}O{sub 3} (6 mol %) Er{sub 2}O{sub 3} (5.85 mol %) are grown by directional crystallisation in a cold container using direct RF melting. The spectral and luminescent properties of these crystals are studied in order to use them as active media of solid state lasers emitting in the wavelength range 1.5 1.7 ?m. (active media)

  2. SREL Reprint #3225

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    5 A new set of microsatellite loci for Laptonycteris yerbabuenae and cross species amplification with other glossophagines Jose Antonio Romero-Meza1, Stacey L. Lance2, and Jorge Ortega1 1Laboratorio de Ictiología y Limnología, Posgrado en Ciencias Quimicobiológicas, Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Sto. Tomas, 11340 Mexico, DF, Mexico 2Savannah River Ecology Laboratory,

  3. SREL Reprint #3233

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    3 Development of 24 microsatellite markers for the white nosed coati (Nasua narica) using 454 sequencing Eduardo Sánchez Garibay1, Adrian Silva-Caballero1, Melina Del Real-Monroy1, Stacey L. Lance2, David Valenzuela-Galván3, and Jorge Ortega1 1Laboratorio de Ictiología y Limnología, Posgrado en Ciencias Quimicobiológicas, Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Sto. Tomas, 11340

  4. SREL Reprint #3272

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    2 Development of microsatellite loci for the Honduran white-bat (Ectophylla alba) by using Illumina paired-end sequences Alberto Morales-Leyva1, Rodrigo A. Medellín2, Stacey L. Lance3, Bernal Rodríguez-Herrera4, Melina Del Real-Monroy1, and Jorge Ortega1 1Laboratorio de Bioconservación y Manejo, Posgrado en Ciencias Quimicobiológicas, Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n, Col. Sto.

  5. SREL Reprint #3374

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    4 Ecosystem Services Provided by Avian Scavengers Travis L. DeVault1, James C. Beasley2, Zachary H. Olson3, Marcos Moleón4, Martina Carrete5, Antoni Margalida6, and José Antonio Sánchez-Zapata7 1National Wildlife Research Center, United States Department of Agriculture 2Savannah River Ecology Laboratory, University of Georgia 3University of New England 4Department of Conservation Biology, Estación Biológica de Doñana 5Department of Physical, Chemical and Natural Systems, Universidad Pablo

  6. Untitled

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    and Terry M. Bricker Bellamy, Jost S. Goettert, Patrick A. Limbach Laurie K. Frankel, Larry Sallans, Henry PHOTOSYSTEM WATER CHANNELS WITHIN THE IDENTIFICATION OF PUTATIVE Plants: EXPERIMENTAL Surfaces in Photosystem II of Higher Radiolytic Mapping of Solvent-Contact Bioenergetics: doi: 10.1074/jbc.M113.487033 originally published online June 28, 2013 2013, 288:23565-23572. J. Biol. Chem. 10.1074/jbc.M113.487033 Access the most updated version of this article at doi: . JBC Affinity Sites Find

  7. Evaluation of the effect of impregnated platinum on PFSA degradation for PEM fuel cells.

    SciTech Connect

    Rodgers, Marianne; Pearman, Benjamin P; Bonville, Leonard J.; Cullen, David A; Mohajeri, Nahid; Slattery, Darlene

    2013-01-01

    One of the main sources of membrane degradation in fuel cells is attack by radicals formed wherever Pt, H2, and O2 are present. The effect of Pt precipitated in the membrane is under debate. Although Pt can provide another site for radical formation, it can also scavenge hydrogen peroxide and radicals in the membrane and improve durability. In this work, the effects of Pt particles within the membrane are evaluated and related to membrane degradation. Membranes were ex situ impregnated with 0, 10, 30, and 50 mol% Pt and then tested for 100 h in a fuel cell, at 90 C/100% relative humidity. The highest degradation was observed with the membranes containing 10 mol% Pt, with fluoride emissions of the same magnitude as those of catalyst coated membranes containing Pt/C. Membranes containing 0, 30, and 50 mol% Pt resulted in very low fluoride emission. The high degradation in the 10 mol% membrane was attributed to the low density of platinum particles, which allows generated radicals to attack the membrane before being deactivated. In the 30 mol% and 50 mol% membranes, where the platinum particles were denser, the generated radicals became deactivated on neighboring particles before they attacked the membrane.

  8. An accurate and efficient computational protocol for obtaining the complete basis set limits of the binding energies of water clusters at the MP2 and CCSD(T) levels of theory: Application to (H?O)m, m=2-6, 8, 11, 16 and 17

    SciTech Connect

    Miliordos, Evangelos; Xantheas, Sotiris S.

    2015-06-21

    We report MP2 and CCSD(T) binding energies with basis sets up to pentuple zeta quality for the m = 2-6, 8 clusters. Or best CCSD(T)/CBS estimates are -4.99 kcal/mol (dimer), -15.77 kcal/mol (trimer), -27.39 kcal/mol (tetramer), -35.9 0.3 kcal/mol (pentamer), -46.2 0.3 kcal/mol (prism hexamer), -45.9 0.3 kcal/mol (cage hexamer), -45.4 0.3 kcal/mol (book hexamer), -44.3 0.3 kcal/mol (ring hexamer), -73.0 0.5 kcal/mol (D2d octamer) and -72.9 0.5 kcal/mol (S4 octamer). We have found that the percentage of both the uncorrected (dimer) and BSSE-corrected (dimerCPe) binding energies recovered with respect to the CBS limit falls into a narrow range for each basis set for all clusters and in addition this range was found to decrease upon increasing the basis set. Relatively accurate estimates (within < 0.5%) of the CBS limits can be obtained when using the 2/3, 1/3 (for the AVDZ set) or the , (for the AVTZ, AVQZ and AV5Z sets) mixing ratio between dimere and dimerCPe. Based on those findings we propose an accurate and efficient computational protocol that can be used to estimate accurate binding energies of clusters at the MP2 (for up to 100 molecules) and CCSD(T) (for up to 30 molecules) levels of theory. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multi program national laboratory operated for DOE by Battelle. This research also used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. AC02-05CH11231.

  9. High quality draft genome sequence of Leucobacter chironomi strain MM2LBT (DSM 19883T) isolated from a Chironomus sp. egg mass

    SciTech Connect

    Laviad, Sivan; Lapidus, Alla; Copeland, Alex; Reddy, T. B. K.; Huntemann, Marcel; Pati, Amrita; Ivanova, Natalia N.; Markowitz, Victor M.; Pukall, Rüdiger; Klenk, Hans-Peter; Woyke, Tanja; Kyrpides, Nikos C.; Halpern, Malka

    2015-05-08

    Leucobacter chironomi strain MM2LBT (Halpern et al., Int J Syst Evol Microbiol 59:665-70 2009) is a Gram-positive, rod shaped, non-motile, aerobic, chemoorganotroph bacterium. L. chironomi belongs to the family Microbacteriaceae, a family within the class Actinobacteria. Strain MM2LBT was isolated from a chironomid (Diptera; Chironomidae) egg mass that was sampled from a waste stabilization pond in northern Israel. In a phylogenetic tree based on 16S rRNA gene sequences, strain MM2LBT formed a distinct branch within the radiation encompassing the genus Leucobacter. Here we describe the features of this organism, together with the complete genome sequence and annotation. We find that the DNA GC content is 69.90%. The chromosome length is 2,964,712 bp. It encodes 2,690 proteins and 61 RNA genes. L. chironomi genome is part of the Genomic Encyclopedia of Type Strains, Phase I: the one thousand microbial genomes (KMG) project.

  10. Greengenes: 16S rRNA Database and Workbench Compatible with ARB

    DOE Data Explorer

    DeSantis, T. Z.; Hugenholtz, P.; Larsen, N.; Rojas, M.; Brodie, E. L.; Keller, K.; Huber, T.; Dalevi, D. Hu, P. Andersen, G. L.

    Greengenes was developed, as the abstract of an AEM reprint states, to "addresse limitations of public repositories by providing chimera screening, standard alignment, and taxonomic classification using multiple published taxonomies. It was found that there is incongruent taxonomic nomenclature among curators even at the phylum level. Putative chimeras were identified in 3% of environmental sequences and in 0.2% of records derived from isolates. Environmental sequences were classified into 100 phylum-level lineages in the Archaea and Bacteria....Greengenes is also a functional workbench to assist in analysis of user-generated 16S rRNA gene sequences. Batches of sequencing reads can be uploaded for quality-based trimming and creation of multiple-sequence alignments (9). Three types of non-MSA similarity searches are also available, seed extension by BLAST (1), similarity based on shared 7-mers by a tool called Simrank, and a direct degenerative pattern match for probe/primer evaluation. Results are displayed using user-preferred taxonomic nomenclature and can be saved between sessions. [Taken from DeSantis, T. Z., P. Hugenholtz, N. Larsen, M. Rojas, E. L. Brodie, K. Keller, T. Huber, D. Dalevi, P. Hu, and G. L. Andersen. 2006. Greengenes, a Chimera-Checked 16S rRNA Gene Database and Workbench Compatible with ARB. Appl Environ Microbiol 72:5069-72, pages 1 and 3] (Specialized Interface)

  11. The Characterization of Psychrophilic Microorganisms and their potentially useful Cold-Active Glycosidases Final Progress Report

    SciTech Connect

    Brenchly, Jean E.

    2008-06-30

    Our studies of novel, cold-loving microorganisms have focused on two distinct extreme environments. The first is an ice core sample from a 120,000 year old Greenland glacier. The results of this study are particularly exciting and have been highlighted with press releases and additional coverage. The first press release in 2004 was based on our presentation at the General Meeting of the American Society for Microbiology and was augmented by coverage of our publication (Appl. Environ. Microbiol. 2005. Vol. 71:7806) in the Current Topics section of the ASM news journal, “Microbe.” Of special interest for this report was the isolation of numerous, phylogenetically distinct and potentially novel ultrasmall microorganisms. The detection and isolation of members of the ultrasmall population is significant because these cells pass through 0.2 micron pore filters that are generally used to trap microorganisms from environmental samples. Thus, analyses by other investigators that examined only cells captured on the filters would have missed a significant portion of this population. Only a few ultrasmall isolates had been obtained prior to our examination of the ice core samples. Our development of a filtration enrichment and subsequent cultivation of these organisms has added extensively to the collection of, and knowledge about, this important population in the microbial world.

  12. High quality draft genome sequence of Leucobacter chironomi strain MM2LBT (DSM 19883T) isolated from a Chironomus sp. egg mass

    DOE PAGES [OSTI]

    Laviad, Sivan; Lapidus, Alla; Copeland, Alex; Reddy, T. B. K.; Huntemann, Marcel; Pati, Amrita; Ivanova, Natalia N.; Markowitz, Victor M.; Pukall, Rüdiger; Klenk, Hans-Peter; et al

    2015-05-08

    Leucobacter chironomi strain MM2LBT (Halpern et al., Int J Syst Evol Microbiol 59:665-70 2009) is a Gram-positive, rod shaped, non-motile, aerobic, chemoorganotroph bacterium. L. chironomi belongs to the family Microbacteriaceae, a family within the class Actinobacteria. Strain MM2LBT was isolated from a chironomid (Diptera; Chironomidae) egg mass that was sampled from a waste stabilization pond in northern Israel. In a phylogenetic tree based on 16S rRNA gene sequences, strain MM2LBT formed a distinct branch within the radiation encompassing the genus Leucobacter. Here we describe the features of this organism, together with the complete genome sequence and annotation. We find thatmore » the DNA GC content is 69.90%. The chromosome length is 2,964,712 bp. It encodes 2,690 proteins and 61 RNA genes. L. chironomi genome is part of the Genomic Encyclopedia of Type Strains, Phase I: the one thousand microbial genomes (KMG) project.« less

  13. Anaerobic Biotransformation and Mobility of Pu and PuEDTA

    SciTech Connect

    Xun, Luying

    2005-06-01

    The objective of this report is to isolate anaerobic EDTA-degrading bacteria. Although our goal is to isolate anaerobic EDTA degraders, we initiated the experiments to include nitrilotriacetate (NTA), which is a structure homologue of EDTA. All the aerobic EDTA degraders can degrade NTA, but the isolated NTA degraders cannot degrade EDTA. Since NTA is a simpler structure homologue, it is likely that EDTA-degrading ability is evolved from NTA degradation. This hypothesis is further supported from our characterization of EDTA and NTA-degrading enzymes and genes (J. Bact. 179:1112-1116; and Appl. Environ. Microbiol. 67:688-695). The EDTA monooxygenase and NTA monooxygenase are highly homologous. EDTA monooxygenase can use both EDTA and NTA as substrates, but NTA monooxygenase can only use NTA as a substrate. Thus, we put our effort to isolate both NTA and EDTA degraders. In case, an anaerobic EDTA degrader is not immediately enriched, we will try to evolve the NTA degraders to use EDTA. Both aerobic and anaerobic enrichment cultures were set.

  14. Assessment of G3(MP2)//B3 theory including a pseudopotential for molecules containing first-, second-, and third-row representative elements

    SciTech Connect

    Rocha, Carlos Murilo Romero; Morgon, Nelson Henrique; Custodio, Rogrio; Pereira, Douglas Henrique; Departamento de Cincias Exatas e Biotecnolgicas, Universidade Federal do Tocantins, Campus de Gurupi, 77410-530 Gurupi, Tocantins

    2013-11-14

    G3(MP2)//B3 theory was modified to incorporate compact effective potential (CEP) pseudopotentials, providing a theoretical alternative referred to as G3(MP2)//B3-CEP for calculations involving first-, second-, and third-row representative elements. The G3/05 test set was used as a standard to evaluate the accuracy of the calculated properties. G3(MP2)//B3-CEP theory was applied to the study of 247 standard enthalpies of formation, 104 ionization energies, 63 electron affinities, 10 proton affinities, and 22 atomization energies, comprising 446 experimental energies. The mean absolute deviations compared with the experimental data for all thermochemical results presented an accuracy of 1.4 kcal mol{sup ?1} for G3(MP2)//B3 and 1.6 kcal mol{sup ?1} for G3(MP2)//B3-CEP. Approximately 75% and 70% of the calculated properties are found with accuracy between 2 kcal mol{sup ?1} for G3(MP2)//B3 and G3(MP2)//B3-CEP, respectively. Considering a confidence interval of 95%, the results may oscillate between 4.2 kcal mol{sup ?1} and 4.6 kcal mol{sup ?1}, respectively. The overall statistical behavior indicates that the calculations using pseudopotential present similar behavior with the all-electron theory. Of equal importance to the accuracy is the CPU time, which was reduced by between 10% and 40%.

  15. Free energies and mechanisms of water exchange around Uranyl from first principles molecular dynamics

    SciTech Connect

    Atta-Fynn, Raymond; Bylaska, Eric J.; De Jong, Wibe A.

    2012-02-01

    From density functional theory (DFT) based ab initio (Car-Parrinello) metadynamics, we compute the activation energies and mechanisms of water exchange between the first and second hydration shells of aqueous Uranyl (UO{sub 2}{sup 2+}) using the primary hydration number of U as the reaction coordinate. The free energy and activation barrier of the water dissociation reaction [UO{sub 2}(OH{sub 2}){sub 5}]{sup 2+}(aq) {yields} [UO{sub 2}(OH{sub 2})4]{sup 2+}(aq) + H{sub 2}O are 0.7 kcal and 4.7 kcal/mol respectively. The free energy is in good agreement with previous theoretical (-2.7 to +1.2 kcal/mol) and experimental (0.5 to 2.2 kcal/mol) data. The associative reaction [UO{sub 2}(OH{sub 2}){sub 5}]{sup 2+}(aq) + H{sub 2}O {yields} [UO{sub 2}(OH{sub 2})6]{sup 2+}(aq) is short-lived with a free energy and activation barrier of +7.9 kcal/mol and +8.9 kca/mol respectively; it is therefore classified as associative-interchange. On the basis of the free energy differences and activation barriers, we predict that the dominant exchange mechanism between [UO{sub 2}(OH{sub 2}){sub 5}]{sup 2+}(aq) and bulk water is dissociative.

  16. Improving the ethanol gas-sensing properties of porous ZnO microspheres by Co doping

    SciTech Connect

    Xiao, Qi Wang, Tao

    2013-08-01

    Graphical abstract: - Highlights: • Co-doped porous ZnO microspheres were synthesized. • 3 mol% Co-doped ZnO sensor showed the highest response to ethanol. • 3 mol% Co-doped ZnO sensor exhibited fast recovery property. • 3 mol% Co-doped ZnO sensor exhibited good selectivity and long-term stability. - Abstract: Porous Co-doped ZnO microspheres were prepared by a simple hydrothermal method combined with post-annealing. Co species existed as a form of divalent state in the sample and substituted Zn{sup 2+} sites in ZnO crystal lattice, which was affirmed by X-ray diffraction, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The gas-sensing measurements demonstrated that the 3 mol% Co-doped ZnO sample showed the highest response value to 100 ppm ethanol at 350 °C, which were 5 folds higher than that of the pure ZnO sample. In addition, the 3 mol% Co-doped ZnO sensor exhibited fast recovery property, good quantitative determination, good selectivity and long-term stability. The superior sensing properties were contributed to high specific surface area combined with the large amount of oxygen vacancies originating from Co doping.

  17. Supercritical Fluid Extraction of Plutonium and Americium from Soil using Thenoyltrifluoroacetone and Tributylphosphate Complexation

    SciTech Connect

    Mincher, Bruce Jay; Fox, Robert Vincent; Holmes, R.; Robbins, R; Boardman, C.

    2001-10-01

    Samples of clean soil from the source used to backfill pits at the Idaho National Engineering and Environmental Laboratory's Radioactive Waste Management Complex were spiked with Pu-239 and Am-241 to evaluate ligand-assistedsupercritical fluid extraction as a decontamination method. The actual soil in the pits has been subject to approximately three decades of weatheringsince it was originally contaminated. No surrogate soil can perfectly simulate the real event, but actual contaminated soil was not available for research purposes. However, fractionation of Am and Pu in the surrogate soil was found to be similar to that previously measured in the real soil using asequential aqueous extraction procedure. This suggests that Pu and Am behavior are similar in the two soils. The surrogate was subjected to supercritical carbon dioxide extraction, in the presence of the fluorinated beta diketone thenoyltrifluoroacetone (TTA), and tributylphosphate (TBP). As much as 69% of the Pu and 88% of the Am were removed from the soil using 3.2mol% TTA and 2.7 mol % TBP, in a single 45 minute extraction. Extraction conditions employing a 5 mol % ethanol modifier with 0.33 mol % TTA and 0.27 mol %TBP resulted in 66% Pu and 68% Am extracted. To our knowledge, this is thefirst report of the use of supercritical fluid extraction (SFE) for the removal of actinides from soil.

  18. Hybrid Quantum Mechanics/Molecular Mechanics-Based Molecular Dynamics Simulation of Acid-Catalyzed Dehydration of Polyols in Liquid Water

    SciTech Connect

    Caratzoulas, Stavros; Courtney, Timothy; Vlachos, Dionisios G.

    2011-01-01

    We use the conversion of protonated glycerol to acrolein for a case study of the mechanism of acid-catalyzed dehydration of polyols in aqueous environments. We employ hybrid Quamtum Mechanics/Molecular Mechanics Molecular Dynamics (QM/MM MD) simulations with biased sampling and perform free energy calculations for the elementary steps of the reaction. We investigate the effects of solvent dynamics and in particular the role of quantum mechanical water in the dehydration mechanism. We present results supporting a mechanism that proceeds via water-mediated proton transfers and thus through an enol intermediate. We find that the first dehydration may take place by two, low-energy pathways requiring, respectively, 20.9 and 18.8 kcal/mol of activation free energy. The second dehydration requires 19.9 kcal/mol of activation free energy while for the overall reaction we compute a free energy change of -8 kcal/mol.

  19. Diffusion of CO{sub 2} on Rutile TiO{sub 2}(110) Surface

    SciTech Connect

    Lee, Junseok; Sorescu, Dan C.; Deng, Xingyi; Jordan, Kenneth D.

    2011-12-15

    The diffusion of CO{sub 2} molecules on a reduced rutile TiO{sub 2}(110)-(11) surface has been investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The STM feature associated with a CO{sub 2} molecule at an oxygen vacancy (V{sub O}) becomes increasingly streaky with increasing temperature, indicating thermally activated CO{sub 2} diffusion from the V{sub O} site. From temperature-dependent tunneling current measurements, the barrier for diffusion of CO{sub 2} from the V{sub O} site is estimated to be 3.31 0.23 kcal/mol. The corresponding value from the DFT calculations is 3.80 kcal/mol. In addition, the DFT calculations give a barrier for diffusion of CO{sub 2} along Ti rows of only 1.33 kcal/mol.

  20. Effect of nickelous and other metal ions on the inhibition of rumen bacterial metabolism by 3-(3'-isocyanocyclopent-2-enylidene)propionic acid and related isocyanides. [Phleum pratense

    SciTech Connect

    Brewer, D.; Calder, F.W.; Jones, G.A.; Tanguay, D.; Taylor, A.

    1986-01-01

    3-(3'-isocyanocyclopent-2-enylidene) propionic acid at a concentration of 2 to 5 ..mu..g ml/sup -1/ inhibited cellulose digestion by a mixed culture of rumen microorganisms and in other experiments inhibited the degradation of timothy had (Phleum pratense) in a digestibility test. At isocyanide concentrations of 12 ..mu..g ml/sup -1/ the fermentation activity of rumen fluid, measured by its dehydrogenase activity, was inhibited but not abolished. All of these isocyanide effects were reversed by the incorporation of nickelous ion into the solutions of the systems under study. The activity of 1 mol of isocyanide is reversed by about 1 mol of Ni/sup 2 +/ and, in the case of the cellulose digestion test, by about 1 mol of Co/sup 2 +/. Of some 15 other ions tested only Pd/sup 2 +/ and possibly chromium reversed the effect of the isocyanide.

  1. Influences of ureaglycerol mixtures as mixed mesopore-controlling agents on tailoring physicochemical properties and photocatalytic H{sub 2} production activity of solgel-derived mesoporous-assembled TiO{sub 2} nanocrystals

    SciTech Connect

    Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2013-01-15

    Graphical abstract: Display Omitted Highlights: ? Mesoporous-assembled TiO{sub 2} nanocrystals were synthesized by modified solgel process. ? Ureaglycerol mixtures were applied as mixed mesopore-controlling agents. ? Urea and glycerol contents affected physicochemical properties of synthesized TiO{sub 2}. ? Photocatalytic H{sub 2} production activity also depended on urea and glycerol contents. ? 75 mol% urea and 25 mol% glycerol yielded the most photocatalytically active TiO{sub 2}. -- Abstract: In this work, the mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts were successfully synthesized by a solgel process with the aid of ureaglycerol mixtures used as mixed mesopore-controlling agents. The photocatalytic activity of the synthesized mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts was investigated for hydrogen production from the water splitting reaction using methanol as a hole scavenger under UV light irradiation. The synthesized TiO{sub 2} nanocrystal photocatalysts were systematically characterized by TGDTA, N{sub 2} adsorptiondesorption, SEM, high resolution TEM, and XRD analyses. The characterization results showed that the well-controlled contents of urea and glycerol in a ureaglycerol mixture at 75 mol% urea and 25 mol% glycerol resulted in not only the most highly porous network (i.e. the highest specific surface area and total pore volume, and the smallest mean mesopore diameter), but also the smallest crystallite size of the synthesized TiO{sub 2} nanocrystal photocatalyst. The photocatalytic reaction results, hence, revealed a much superior photocatalytic hydrogen production activity of the mesoporous-assembled TiO{sub 2} nanocrystal synthesized with 75 mol% urea and 25 mol% glycerol to the other synthesized TiO{sub 2} nanocrystals, also being much higher than those of the commercially available P-25 TiO{sub 2} and ST-01 TiO{sub 2} powders.

  2. Organic Rankine-Cycle Power Systems Working Fluids Study: Topical report No. 3, 2-methylpyridine/water

    SciTech Connect

    Cole, R.L.; Demirgian, J.C.; Allen, J.W.

    1987-09-01

    A mixture of 35 mole percent (mol %) 2-methylpyridine and 65 mol % water was tested at 575, 625, and 675/degree/F in a dynamic loop. Samples of the degraded fluid were chemically analyzed to determine the identities of major degradation products and the quantity of degradation. Computed degradation rates were found to be higher than those for Fluorinol 85 or toluene. For this reason (and other reasons, related to fluid handling), other fluids are recommended as the first choice for service in organic Rankine-cycle systems in preference to 2-methylpyridine/water. 7 refs., 39 figs., 39 tabs.

  3. Visible absorption spectra of crystal violet in supercritical ethane - methanol solution.

    SciTech Connect

    Dimitrijevic, N. M.; Takahashi, K.; Jonah, C. D.; Chemistry

    2002-11-01

    The effects of concentration and mole fraction of methanol in supercritical ethane on the absorption spectra of crystal violet (CV) were examined. Keeping the concentration of CV in the cell constant at 50 {mu}mol l{sup -1}, both the methanol concentration (from 0.4 to 1.2 mol l{sup -1}) and pressure of ethane (from 60 to 150 bar) were varied. The degree of solvation of CV depends both on the mole fraction and concentration of cosolvent. The dimerization of CV was found to decrease with pressure, and with the ratio between methanol and CV concentrations.

  4. Terpolymerization of ethylene, sulfur dioxide and carbon monoxide

    DOEpatents

    Johnson, Richard; Steinberg, Meyer

    1981-01-01

    This invention relates to a high molecular weight terpolymer of ethylene, sulfur dioxide and carbon monoxide stable to 280.degree. C. and containing as little as 36 mol % ethylene and about 41-51 mol % sulfur dioxide; and to the method of producing said terpolymer by irradiation of a liquid and gaseous mixture of ethylene, sulfur dioxide and carbon monoxide by means of Co-60 gamma rays or an electron beam, at a temperature of about 10.degree.-50.degree. C., and at a pressure of about 140 to 680 atmospheres, to initiate polymerization.

  5. Phase diagram of EuI{sub 2}-KI binary system

    SciTech Connect

    Sun, Y. |; Wang, S.; Wang, M.; Qiao, Z.

    1998-02-15

    The phase diagram of the EuI{sub 2}-KI binary system was studied by differential thermal analysis (DTA) and X-ray powder diffraction (XRD). The phase diagram of the EuI{sub 2}-KI system shows the existence of one congruently melting compound, KEu{sub 2}I{sub 5}, and one incongruently melting compound, K{sub 4}EuI{sub 6}. There are two eutectic points located at 465 C, 20 mol% KI and 439 C, 60 mol% KI, respectively.

  6. Preconversion catalytic deoxygenation of phenolic functional groups. Quarterly technical progress report, January 1, 1992--March 31, 1992

    SciTech Connect

    Kubiak, C.P.

    1992-08-01

    The deoxygenation of phenols is a conceptually simple, but unusually difficult chemical transformation to achieve. The phenolic C-O bond energy of 103 kcal/mol is as strong as a benzene C-H bond and over a 10 kcal/mol stronger than the C-O bonds of methanol and ethanol. The consequence of this is that the hydrogenation/deoxygenation methods in current use require severe conditions and give low selectivities. The ongoing research described herein is based on the unprecedented, but thermodynamically promising, use of carbon monoxide as the oxygen atom acceptor for the catalytic deoxygenation of phenols.

  7. Genomic Sequencing of Single Microbial Cells from Environmental Samples

    SciTech Connect

    Ishoey, Thomas; Woyke, Tanja; Stepanauskas, Ramunas; Novotny, Mark; Lasken, Roger S.

    2008-02-01

    Recently developed techniques allow genomic DNA sequencing from single microbial cells [Lasken RS: Single-cell genomic sequencing using multiple displacement amplification, Curr Opin Microbiol 2007, 10:510-516]. Here, we focus on research strategies for putting these methods into practice in the laboratory setting. An immediate consequence of single-cell sequencing is that it provides an alternative to culturing organisms as a prerequisite for genomic sequencing. The microgram amounts of DNA required as template are amplified from a single bacterium by a method called multiple displacement amplification (MDA) avoiding the need to grow cells. The ability to sequence DNA from individual cells will likely have an immense impact on microbiology considering the vast numbers of novel organisms, which have been inaccessible unless culture-independent methods could be used. However, special approaches have been necessary to work with amplified DNA. MDA may not recover the entire genome from the single copy present in most bacteria. Also, some sequence rearrangements can occur during the DNA amplification reaction. Over the past two years many research groups have begun to use MDA, and some practical approaches to single-cell sequencing have been developed. We review the consensus that is emerging on optimum methods, reliability of amplified template, and the proper interpretation of 'composite' genomes which result from the necessity of combining data from several single-cell MDA reactions in order to complete the assembly. Preferred laboratory methods are considered on the basis of experience at several large sequencing centers where >70% of genomes are now often recovered from single cells. Methods are reviewed for preparation of bacterial fractions from environmental samples, single-cell isolation, DNA amplification by MDA, and DNA sequencing.

  8. Oxidation kinetics of calcium-doped palladium powders

    SciTech Connect

    Jain, S.; Kodas, T.T.; Hampden-Smith, M. [Univ. of New Mexico, Albuquerque, NM (United States)

    1997-04-01

    The oxidation kinetics of submicron Ca-containing Pd powders produced by spray pyrolysis were studied in the temperature range 600 to 675 C using thermogravimetric analysis. The oxidation of pure Pd powder had an activation energy of {approximately}230 kJ/mol in the region 27% < oxidation < 70% and 65 kJ/mol for oxidation > 70%. The activation energies for Pd particles containing 0.01 weight percent (w/o) and 0.4 w/o Ca in the region 27% < oxidation < 70% were {approximately}230 kJ/mol and {approximately}50 kJ/mol, respectively. Transmission electron microscopy suggested that the conversion of Pd to Pd{sup II}O (stoichiometric PdO) proceeds from the particle surface into the interior and not homogeneously throughout the particle. The predictions of a variety of models and rate laws (shrinking core, parabolic, cubic, logarithmic, and inverse logarithmic) were compared with the data. The comparison suggested a mechanism in which oxidation of pure Pd proceeds by chemisorption and diffusion of oxygen to form a substoichiometric oxide, followed by the conversion of substoichiometric PdO to Pd{sup II}O. Oxidation of pure Pd is then probably limited by the diffusion of oxygen through the substoichiometric PdO and/or Pd{sup II}O. The addition of Ca increased the oxidation resistance of Pd most likely by inhibiting oxygen diffusion through the metal oxide layers surrounding the Pd.

  9. A study of radiolytic stability of 25,27-bis(2-propyloxy) calix[4]-26,28-crown-6 (iPR-C[4]C-6)

    SciTech Connect

    Jianchen, Wang; Chongli, Song

    2008-07-01

    The radiolytic stability of 25,27-bis(2-propyloxy)calix[4] arene -26,28-crown-6 (iPr-C[4]C-6) was studied. {sup 60}co was used as a radiation source. Its dose rate was 437 Gy/min., and the total absorbed dose of the iPr-C[4]C-6 was from 10{sup 4} to 10{sup 6} Gy. The iPr-C[4]C-6 solid and 0.025 mol/L iPr-C[4]C-6/n-octanol which were pre-equilibrated with 0.01 mol/L and 3 mol/L nitric acid, respectively, were given different doses, and their extraction performance was researched. Their degradation mechanism was investigated by mass spectrometry (MS) and infrared spectroscopy (IR). The results show that radiolytic stability of the iPr-C[4]C-6 solid and 0.025 mol/L iPr-C[4]C-6/n-octanol are good when their absorbed dose is less than 10{sup 6} Gy. The extracting system of iPr-C[4]C-6/n-octanol is promising for separating cesium from high-level liquid waste(HLLW)

  10. Thermodynamic properties of a geothermal working fluid; 90% isobutane-10% isopentane: Final report

    SciTech Connect

    Gallagher, J.S.; Linsky, D.; Morrison, G.; Levelt Sengers, J.M.H.

    1987-04-01

    We present tables of thermodynamic properties, and dew and bubble properties, of a mixture of 90 mol % isobutane and 10 mol % isopentane, a working fluid in a binary geothermal power cycle. The tables are generated by a formulation of the Helmholtz free energy, in which the mixture properties are mapped onto the known properties of pure isobutane by means of the principle of generalized corresponding states. The data base for the Helmholtz free energy formulation is new. We report data obtained in three different apparatus: critical-line and isopentane vapor pressure data obtained in a visual cell; vapor-liquid equilibria data obtained in a mercury-operated variable-volume cell; and pressure-volume-temperature data for the 90 mol %-10 mol % mixture obtained in a semi-automated Burnett-isochoric apparatus. The principles of the methods, and estimates of the reliability, are discussed and all experimental data are compared with the surface. The results are tables of specific volume, enthalpy, entropy, specific heat and density and temperature derivatives of the pressure at 10 K temperature increments from 240 to 600 K along isobars from 0.01 to 20 MPa. Separate tables are prepared from the dew and bubble properties of the 90-10 mixture. Estimates of the effects of isomeric impurity of isobutane are given in graphical form.

  11. Annealing of paramagnetic centres in electron- and ion-irradiated yttria-stabilized zirconia: effect of yttria content

    SciTech Connect

    Costantini, Jean-Marc; Beuneu, Francois; Weber, William J

    2014-01-01

    We have studied the effect of the yttria content on the recovery of paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+). Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. Paramagnetic centre thermal annealing was studied by X-band EPR spectroscopy. Hole-centres are found to be annealed more quickly, or at a lower temperature, for 18 mol% than for 9.5 mol% Y2O3. At long annealing times, a non-zero asymptotic behaviour is observed in the isothermal annealing curves of hole-centres and F+-type centres between 300 and 500 K. The normalized asymptotic concentration of both defects has a maximum value of about 0.5 for annealing temperatures near 375 K, below the onset of the (isochronal) recovery stage, regardless of the yttria content. Such an uncommon behaviour is analyzed on the basis of either kinetic rate equations of charge transfer or equilibria between point defects with different charge states.

  12. Vibrationally resolved transitions in ion-molecule and atom-molecular ion slow collisions

    DOE Data Explorer

    The data tables and interactive graphs made available here contain theoretical integral cross sections for vibrational excitation and vibrationally resolved charge transfer from vibrationally excited states of H2 and H2+ with protons and hydrogen atoms, respectively. [From http://www-cfadc.phy.ornl.gov/h2mol/home.html] (Specialized Interface)

  13. Thermal decomposition of 1,3,3-trinitroazetidine (TNAZ): A density functional theory and ab initio study

    SciTech Connect

    Veals, Jeffrey D.; Thompson, Donald L.

    2014-04-21

    Density functional theory and ab initio methods are employed to investigate decomposition pathways of 1,3,3-trinitroazetidine initiated by unimolecular loss of NO{sub 2} or HONO. Geometry optimizations are performed using M06/cc-pVTZ and coupled-cluster (CC) theory with single, double, and perturbative triple excitations, CCSD(T), is used to calculate accurate single-point energies for those geometries. The CCSD(T)/cc-pVTZ energies for NO{sub 2} elimination by NN and CN bond fission are, including zero-point energy (ZPE) corrections, 43.21 kcal/mol and 50.46 kcal/mol, respectively. The decomposition initiated by trans-HONO elimination can occur by a concerted H-atom and nitramine NO{sub 2} group elimination or by a concerted H-atom and nitroalkyl NO{sub 2} group elimination via barriers (at the CCSD(T)/cc-pVTZ level with ZPE corrections) of 47.00 kcal/mol and 48.27 kcal/mol, respectively. Thus, at the CCSD(T)/cc-pVTZ level, the ordering of these four decomposition steps from energetically most favored to least favored is: NO{sub 2} elimination by NN bond fission, HONO elimination involving the nitramine NO{sub 2} group, HONO elimination involving a nitroalkyl NO{sub 2} group, and finally NO{sub 2} elimination by CN bond fission.

  14. Urinary 1-hydroxypyrene concentrations in Chinese coke oven workers relative to job category, respirator usage, and cigarette smoking

    SciTech Connect

    Bo Chen; Yunping Hu; Lixing Zheng; Qiangyi Wang; Yuanfen Zhou; Taiyi Jin

    2007-09-15

    1-Hydroxypyrene (1-OHP) is a biomarker of recent exposure to polycyclic aromatic hydrocarbons (PAHs). We investigated whether urinary 1-OHP concentrations in Chinese coke oven workers (COWs) are modulated by job category, respirator usage, and cigarette smoking. The present cross-sectional study measured urinary 1-OHP concentrations in 197 COWs from Coking plant I and 250 COWs from Coking plant II, as well as 220 unexposed referents from Control plant I and 56 referents from Control plant II. Urinary 1-OHP concentrations (geometric mean, {mu}mol/mol creatinine) were 5.18 and 4.21 in workers from Coking plants I and II, respectively. The highest 1-OHP levels in urine were found among topside workers including lidmen, tar chasers, and whistlers. Benchmen had higher 1-OHP levels than other workers at the sideoven. Above 75% of the COWs exceeded the recommended occupational exposure limit of 2.3 {mu}mol/mol creatinine. Respirator usage and increased body mass index (BMI) slightly reduced 1-OHP levels in COWs. Cigarette smoking significantly increased urinary 1-OHP levels in unexposed referents but had no effect in COWs. Chinese COWs, especially topside workers and benchmen, are exposed to high levels of PAHs. Urinary 1-OHP concentrations appear to be modulated by respirator usage and BMI in COWs, as well as by smoking in unexposed referents.

  15. Enthalpy of formation of gallium nitride

    SciTech Connect

    Ranade, M.R.; Tessier, F.; Navrotsky, A.; Leppert, V.J.; Risbud, S.H.; DiSalvo, F.J.; Balkas, C.M.

    2000-05-04

    A major discrepancy in the literature concerning the enthalpy of formation of GaN has been resolved using oxidative oxide melt solution calorimetry. Four samples of differing nitrogen contents were measured by dropping them into molten 3Na{sub 2}O{center_dot}4MoO{sub 3} in a calorimeter at 975 K with oxygen gas bubbling through the solvent. The samples were characterized by X-ray diffraction, chemical analysis, transmission electron microscopy, particle size analysis, and BET measurements. The enthalpy of drop solution (kJ/g) varied approximately linearly with nitrogen content. Extrapolated to stoichiometric GaN, the data yield a value of {minus}156.8 {+-} 16.0 kJ/mol for the standard enthalpy of formation from the elements at 298 K. The relatively large error reflects the deviation of individual points from the straight line rather than uncertainties in each set of data for a given sample. This new directly measured enthalpy of formation is in excellent agreement with that obtained from the temperature dependence of the equilibrium pressure of nitrogen over GaN, {minus}157.7 kJ/mol, measured by Madar et al. and Karpinski and Porowski. This value of {minus}156.8 kJ/mol should replace the commonly tabulated value of {minus}110 kJ/mol determined by Hahn and Juza using combustion calorimetry on an uncharacterized sample over 50 years ago.

  16. Supercritical Fluid Extraction of Plutonium and Americium from Soil

    SciTech Connect

    Fox, R.V.; Mincher, B.J.

    2002-05-23

    Supercritical fluid extraction (SFE) of plutonium and americium from soil was successfully demonstrated using supercritical fluid carbon dioxide solvent augmented with organophosphorus and beta-diketone complexants. Spiked Idaho soils were chemically and radiologically characterized, then extracted with supercritical fluid carbon dioxide at 2,900 psi and 65 C containing varying concentrations of tributyl phosphate (TBP) and thenoyltrifluoroacetone (TTA). A single 45 minute SFE with 2.7 mol% TBP and 3.2 mol% TTA provided as much as 88% {+-} 6.0 extraction of americium and 69% {+-} 5.0 extraction of plutonium. Use of 5.3 mol% TBP with 6.8 mol% of the more acidic beta-diketone hexafluoroacetylacetone (HFA) provided 95% {+-} 3.0 extraction of americium and 83% {+-} 5.0 extraction of plutonium in a single 45 minute SFE at 3,750 psi and 95 C. Sequential chemical extraction techniques were used to chemically characterize soil partitioning of plutonium and americium in pre-SFE soil samples. Sequential chemical extraction techniques demonstrated that spiked plutonium resides primarily (76.6%) in the sesquioxide fraction with minor amounts being absorbed by the oxidizable fraction (10.6%) and residual fractions (12.8%). Post-SFE soils subjected to sequential chemical extraction characterization demonstrated that 97% of the oxidizable, 78% of the sesquioxide and 80% of the residual plutonium could be removed using SFE. These preliminary results show that SFE may be an effective solvent extraction technique for removal of actinide contaminants from soil.

  17. Heterogeneity and dynamics in villin headpiece crystal structures

    SciTech Connect

    Meng, Jianmin; McKnight, Christopher James, E-mail: cjmck@bu.edu [Boston University School of Medicine (United States)

    2009-05-01

    New crystal structures of the well studied protein-folding model system villin headpiece in a new space group provide insights into the conformations available in the folded state. The villin headpiece domain (HP67) is the C-terminal F-actin-binding motif that confers F-actin-bundling activity to villin, a component of the actin bundles that support the brush-border microvilli. It has been investigated extensively by both experimental and theoretical measurements. Our laboratory, for example, has determined both its NMR and its crystal structures. This study presents the structures of HP67 and its pH-stabilized mutant (H41Y) in a different crystal form and space group. For both constructs, two molecules are found in each asymmetric unit in the new space group P6{sub 1}. While one of the two structures (Mol A) is structurally similar to our previously determined structure (Mol X), the other (Mol B) has significant deviations, especially in the N-terminal subdomain, where lattice contacts do not appear to contribute to the difference. In addition, the structurally most different crystal structure, Mol B, is actually closer to the averaged NMR structure. Harmonic motions, as suggested by the B-factor profiles, differ between these crystal structures; crystal structures from the same space group share a similar pattern. Thus, heterogeneity and dynamics are observed in different crystal structures of the same protein even for a protein as small as villin headpiece.

  18. SREL Reprint #3027

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    similarity) as its closest relative. The G+C content of the genomic DNA was 30.8 mol% (HPLC). Cells were straight to curved rods, 0.5-1.0 m in diameter and 3.0-9.0 m in...

  19. Roaming radical pathways for the decomposition of alkanes.

    SciTech Connect

    Harding, L. B.; Klippenstein, S. J.

    2010-01-01

    CASPT2 calculations predict the existence of roaming radical pathways for the decomposition of propane, n-butane, isobutane and neopentane. The roaming radical paths lead to the formation of an alkane and an alkene instead of the expected radical products. The predicted barriers for the roaming radical paths lie {approx}1 kcal/mol below the corresponding radical asymptotes.

  20. CX-014248: Categorical Exclusion Determination

    Energy.gov [DOE]

    Enabling 10 mol/kg Swing Capacity via Heat Integrated Sub-Ambient Pressure Swing CX(s) Applied: A9, B3.6Date: 09/09/2015 Location(s): GeorgiaOffices(s): National Energy Technology Laboratory

  1. Determination of rate constants for the reaction between 2-(2-amino-ethoxy) ethanol and carbonyl sulfide

    SciTech Connect

    Singh, M.; Bullin, J.A. (Texas A and M Univ., College Station, TX (US))

    1988-01-01

    The kinetics of the reaction between carbonyl sulfide (COS) and aqueous 2-(2-amino-ethoxy) ethanol (Diglycolamine or DGA) in aqueous solutions were investigated over a temperature range of 307 K to 322 K and pressure range of 345-414 kPa. The experimental data were correlated by assuming the reaction to be kinetically controlled. The observed reaction rates were significantly larger than those for the COS/H/sub 2/O system. Therefore, it was concluded that DGA had a catalytic effect on the COS hydrolysis reaction. The analysis indicated that the reaction followed a second order rate equation: first order in COS and first order in DGA. Justification for assuming kinetic control of the absorption was demonstrated by doubling and tripling the stirring speed which produced no significant change in the absorption rate (mol/s). Another series of tests were carried out which showed that the absorption rate (mol/s) was proportional to the reactor volume. In addition, the activation energy was out of the range of ordinary mass transfer control.

  2. Analysis of emission spectra of Ho{sup 3+}:LFBCd glasses

    SciTech Connect

    Naresh, V. Buddhudu, S.

    2014-04-24

    In the present paper, we report on the absorption and emission properties of (0.1-1.5 mol %) Ho{sup 3+} doped LFBCd (Li{sub 2}O{sub ?}LiF{sub ?}B{sub 2}O{sub 3?}CdO) glasses prepared via melt quenching method. On exciting these glasses at (?{sub exci}) = 452 nm, two emissions at 556 nm ({sup 5}S{sub 2}?{sup 5}I{sub 8}; Green), 655 nm ({sup 5}F{sub 5}?{sup 5}I{sub 8}; Red) have been obtained. Upon exciting these glasses with a 980 nm diode laser, NIR emissions at 1195 nm ({sup 5}I{sub 6}?{sup 5}I{sub 8}), 1951 nm ({sup 5}I{sub 7}?{sup 5}I{sub 8}) have been measured for 1 mol % Ho{sup 3+}:LFBCd glass. For higher concentration beyond 1.0 mol %, emission quenching of Ho{sup 3+} glass has been noticed and which has successfully been explained in terms of an energy level diagram. From absorption cross-section data, stimulated emission cross-section has been evaluated by applying McCumber's theory and further cross-sectional gain has also been computed for the emissions at 1195 nm (?1.20 ?m) and 1951 nm (?2.0 ?m) of 1 mol % Ho{sup 3+}:LFBCd glass.

  3. Kinetics of wet oxidation of propionic and 3-hydroxypropionic acids

    SciTech Connect

    Shende, R.V.; Levec, J.

    1999-07-01

    Oxidation of aqueous solutions of 3-hydroxypropionic (3-HPA) and propionic acids (PA) was studied in a titanium high-pressure reactor at 280--310 C using oxygen partial pressures between 10 and 45 bar. Oxidation of both acids was found to obey first-order kinetic with respect to their concentrations as well as to their lumped TOC concentrations. Oxidation rate revealed a half order dependence with respect to oxygen for oxidation of both acids. In the case of 3-HPA oxidation, the activation energy was found to be 135 kJ/mol, and it was 140 kJ/mol when lumped concentration TOC was used. The activation energy for PA oxidation is 150 kJ/mol, and it is slightly higher, 158 kJ/mol, for TOC reduction. Almost complete conversion of 3-HPA was achieved at 300 C after 1 h, whereas 95% conversion of PA acid was obtained at 310 C after 3 h. During oxidation of 3-HPA, 3-oxopropionic and acetic acids were identified as intermediate products. Oxidation of PA yielded acetic and formic acids as intermediates; at oxygen partial pressures above 25 bar and 310 C, the formation of acetic acid was appreciably reduced. In both cases, however, direct oxidation to carbon dioxide and water was found to be the main reaction route.

  4. Diquat induces renal proximal tubule injury in glutathione reductase-deficient mice

    SciTech Connect

    Rogers, Lynette K. . E-mail: rogersl@ccri.net; Bates, Carlton M.; Welty, Stephen E.; Smith, Charles V.

    2006-12-15

    Reactive oxygen species (ROS) have been associated with many human diseases, and glutathione (GSH)-dependent processes are pivotal in limiting tissue damage. To test the hypothesis that Gr1{sup a1Neu} (Neu) mice, which do not express glutathione reductase (GR), would be more susceptible than are wild-type mice to ROS-mediated injury, we studied the effects of diquat, a redox cycling toxicant. Neu mice exhibited modest, dose- and time-dependent elevations in plasma alanine aminotransferase (ALT) activities, 126 {+-} 36 U/l at 2 h after 5 {mu}mol/kg of diquat, but no ALT elevations were observed in diquat-treated C3H/HeN mice for up to 6 h after 50 {mu}mol/kg of diquat. Histology indicated little or no hepatic necrosis in diquat-treated mice of either strain, but substantial renal injury was observed in diquat-treated Neu mice, characterized by brush border sloughing in the proximal tubules by 1 h and tubular necrosis by 2 h after doses of 7.5 {mu}mol/kg. Decreases in renal GSH levels were observed in the Neu mice by 2 h post dose (3.4 {+-} 0.4 vs 0.2 {+-} 0.0 {mu}mol/g tissue at 0 and 50 {mu}mol/kg, respectively), and increases in renal GSSG levels were observed in the Neu mice as early as 0.5 h after 7.5 {mu}mol/kg (105.5 {+-} 44.1 vs 27.9 {+-} 4.8 nmol/g tissue). Blood urea nitrogen levels were elevated by 2 h in Neu mice after doses of 7.5 {mu}mol/kg (Neu vs C3H, 32.8 {+-} 4.1 vs 17.9 {+-} 0.3 mg/dl). Diquat-induced renal injury in the GR-deficient Neu mice offers a useful model for studies of ROS-induced renal necrosis and of the contributions of GR in defense against oxidant-mediated injuries in vivo.

  5. Maximizing photosynthetic productivity and solar conversion efficiency in microalgae by minimizing the light-harvesting chlorophyll antenna size of the photosystems

    SciTech Connect

    Melis, A.; Neidhardt, J.; Benemann, J.R.

    1998-08-01

    The solar conversion efficiency and productivity of photosynthesis in light-acclimated Dunaliella salina (green algae) were analyzed. Cells were grown under continuous low-light (LL; 100 {micro}mol photons/m{sup 2} s) or high-light (HL; 2,000 {micro}mol photons/m{sup 2} s) conditions. HL-grown cells exhibited signs of chronic photoinhibition, i.e., a lower pigment content, a highly truncated chlorophyll (Chl) antenna size for the photosystems, and accumulation of photodamaged photosystem-II (PSII) reaction centers in the chloroplast thylakoids. In spite of these deficiencies, high-light-grown cells showed photosynthetic productivity (300 mmol O{sub 2}/(mol Chl) s) that was {approximately} 3 times greater than that of the normally pigmented LL-grown cells ({approximately} 100 mmol O{sub 2}/(mol Chl) s). Recovery from photoinhibition in the HL-grown cells, induced in the absence of a light-harvesting Chl antenna size enlargement, increased photosynthetic productivity further to {approximately} 650 mmol O{sub 2}/(mol Chl) s. It is shown that, under moderate to high light conditions, D. salina with a highly truncated Chl antenna size will display superior photosynthetic productivity, solar conversion efficiency and H{sub 2} production when compared to the normally pigmented control cells. Estimates of H{sub 2} production in mass culture suggest an average of 200 L H{sub 2}/m{sup 2} d for the cells with the truncated Chl antenna, and less than 50 L H{sub 2}/m{sup 2} d for the normally pigmented cells.

  6. Energy Landscape of Water and Ethanol on Silica Surfaces

    SciTech Connect

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-06-26

    Fundamental understanding of small moleculesilica surface interactions at their interfaces is essential for the scientific, technological, and medical communities. We report direct enthalpy of adsorption (?hads) measurements for ethanol and water vapor on porous silica glass (CPG-10), in both hydroxylated and dehydroxylated (hydrophobic) forms. Results suggest a spectrum of energetics as a function of coverage, stepwise for ethanol but continuous for water. The zero-coverage enthalpy of adsorption for hydroxylated silica shows the most exothermic enthalpies for both water (-72.7 3.1 kJ/mol water) and ethanol (-78.0 1.9 kJ/mol ethanol). The water adsorption enthalpy becomes less exothermic gradually until reaching its only plateau (-20.7 2.2 kJ/mol water) reflecting water clustering on a largely hydrophobic surface, while the enthalpy of ethanol adsorption profile presents two well separated plateaus, corresponding to strong chemisorption of ethanol on adsorbate-free silica surface (-66.4 4.8 kJ/mol ethanol), and weak physisorption of ethanol on ethanol covered silica (-4.0 1.6 kJ/mol ethanol). On the other hand, dehydroxylation leads to missing watersilica interactions, whereas the number of ethanol binding sites is not impacted. The isotherms and partial molar properties of adsorption suggest that water may only bind strongly onto the silanols (which are a minor species on silica glass), whereas ethanol can interact strongly with both silanols and the hydrophobic areas of the silica surface.

  7. Energy Landscape of Water and Ethanol on Silica Surfaces

    SciTech Connect

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-06-26

    Fundamental understanding of small molecule–silica surface interactions at their interfaces is essential for the scientific, technological, and medical communities. We report direct enthalpy of adsorption (Δhads) measurements for ethanol and water vapor on porous silica glass (CPG-10), in both hydroxylated and dehydroxylated (hydrophobic) forms. Results suggest a spectrum of energetics as a function of coverage, stepwise for ethanol but continuous for water. The zero-coverage enthalpy of adsorption for hydroxylated silica shows the most exothermic enthalpies for both water (-72.7 ± 3.1 kJ/mol water) and ethanol (-78.0 ± 1.9 kJ/mol ethanol). The water adsorption enthalpy becomes less exothermic gradually until reaching its only plateau (-20.7 ± 2.2 kJ/mol water) reflecting water clustering on a largely hydrophobic surface, while the enthalpy of ethanol adsorption profile presents two well separated plateaus, corresponding to strong chemisorption of ethanol on adsorbate-free silica surface (-66.4 ± 4.8 kJ/mol ethanol), and weak physisorption of ethanol on ethanol covered silica (-4.0 ± 1.6 kJ/mol ethanol). On the other hand, dehydroxylation leads to missing water–silica interactions, whereas the number of ethanol binding sites is not impacted. The isotherms and partial molar properties of adsorption suggest that water may only bind strongly onto the silanols (which are a minor species on silica glass), whereas ethanol can interact strongly with both silanols and the hydrophobic areas of the silica surface.

  8. Carbonic anhydrase-facilitated CO2 absorption with polyacrylamide buffering bead capture

    SciTech Connect

    Dilmore, Robert; Griffith, Craid; Liu, Zhu; Soong, Yee; Hedges, Sheila W.; Koepsel, Richard; Ataai, M [Ataai, Mohammad

    2009-07-01

    A novel CO2 separation concept is described wherein the enzyme carbonic anhydrase (CA) is used to increase the overall rate Of CO2 absorption after which hydrated CO2 reacts with regenerable amine-bearing polyacrylamide buffering beads (PABB). Following saturation of the material's immobilized tertiary amines, CA-bearing carrier water is separated and recycled to the absorption stage while CO2-loaded material is thermally regenerated. Process application of this concept would involve operation of two or more columns in parallel with thermal regeneration with low-pressure steam taking place after the capacity of a column of amine-bearing polymeric material was exceeded. PABB CO2- bearing capacity was evaluated by thermogravimetric analysis (TGA) for beads of three acrylamido buffering monomer ingredient concentrations: 0 mol/kg bead, 0.857 mol/kg bead, and 2 mol/kg bead. TGA results demonstrate that CO2- bearing capacity increases with increasing PABB buffering concentration and that up to 78% of the theoretical CO2- bearing capacity was realized in prepared PABB samples (0.857 mol/kg recipe). The highest observed CO2-bearing capacity of PABB was 1.37 mol of CO2 per kg dry bead. TGA was also used to assess the regenerability Of CO2-loaded PABB. Preliminary results suggest that CO2 is partially driven from PABB samples at temperatures as low as 55 degrees C, with complete regeneration occurring at 100 degrees C. Other physical characteristics of PABB are discussed. In addition, the effectiveness of bovine carbonic anhydrase for the catalysis Of CO2 dissolution is evaluated. Potential benefits and drawbacks of the proposed process are discussed. Published by Elsevier Ltd.

  9. Energy Landscape of Water and Ethanol on Silica Surfaces

    DOE PAGES [OSTI]

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-06-26

    Fundamental understanding of small molecule–silica surface interactions at their interfaces is essential for the scientific, technological, and medical communities. We report direct enthalpy of adsorption (Δhads) measurements for ethanol and water vapor on porous silica glass (CPG-10), in both hydroxylated and dehydroxylated (hydrophobic) forms. Results suggest a spectrum of energetics as a function of coverage, stepwise for ethanol but continuous for water. The zero-coverage enthalpy of adsorption for hydroxylated silica shows the most exothermic enthalpies for both water (-72.7 ± 3.1 kJ/mol water) and ethanol (-78.0 ± 1.9 kJ/mol ethanol). The water adsorption enthalpy becomes less exothermic gradually until reachingmore » its only plateau (-20.7 ± 2.2 kJ/mol water) reflecting water clustering on a largely hydrophobic surface, while the enthalpy of ethanol adsorption profile presents two well separated plateaus, corresponding to strong chemisorption of ethanol on adsorbate-free silica surface (-66.4 ± 4.8 kJ/mol ethanol), and weak physisorption of ethanol on ethanol covered silica (-4.0 ± 1.6 kJ/mol ethanol). On the other hand, dehydroxylation leads to missing water–silica interactions, whereas the number of ethanol binding sites is not impacted. The isotherms and partial molar properties of adsorption suggest that water may only bind strongly onto the silanols (which are a minor species on silica glass), whereas ethanol can interact strongly with both silanols and the hydrophobic areas of the silica surface.« less

  10. Adsorption and diffusion of carbon dioxide on metal-organic framework (MOF-5)

    SciTech Connect

    Zhao, Z.X.; Li, Z.; Lin, Y.S.

    2009-11-15

    Adsorption equilibrium and diffusion of CO{sub 2} on microporous metal-organic frameworks (MOF-5, or IRMOF-1) crystals were experimentally studied by the gravimetric method in the pressure range up to 1 atm. The MOF-5 crystal cubes of about 40-60 {mu} m in sizes were synthesized by the solvothermal method. Freundlich adsorption isotherm equation can fit well CO{sub 2} adsorption isotherms on MOF-5, with isosteric heat of adsorption of about 34 kJ/mol. Diffusion coefficient of CO{sub 2} in the MOF-5 is in the range of 8.1-11.5 x 10{sup -9} cm{sup 2}/s in 295-331K with activation energy of 7.61 kJ/mol. MOF-5 offers attractive adsorption properties as an adsorbent for separation of CO{sub 2} from flue gas.

  11. Kinetics of Methane Hydrate Decomposition Studied via in Situ Low Temperature X-ray Powder Diffraction

    SciTech Connect

    Everett, Susan M; Rawn, Claudia J; Keffer, David J.; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy Joe

    2013-01-01

    Gas hydrates are known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice termed self-preservation or anomalous preservation. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Two regions of slowed decomposition for methane hydrate, 180 200 K and 230 260 K, were observed, and the kinetics were studied by in situ low temperature x-ray powder diffraction. The kinetic constants for ice formation from methane hydrate were determined by the Avrami model within each region and activation energies, Ea, were determined by the Arrhenius plot. Ea determined from the data for 180 200 K was 42 kJ/mol and for 230 260 K was 22 kJ/mol. The higher Ea in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  12. Porous Vycor membranes modified by chemical vapor deposition of boron nitride for gas separation

    SciTech Connect

    Levy, R.A.; Ravindranath, C.; Krasnoperov, L.N.; Opyrchal, J.; Ramos, E.S.

    1997-01-01

    This study focuses on the characterization of porous Vycor membranes modified by chemical vapor deposition of boron nitride (B-N-C-H) for gas separation. The B-N-C-H films were deposited on mesoporous Vycor tubes using triethylamine borane complex and ammonia as precursors. The effects of deposition temperature and reactant flow geometry on permselectivity of membranes with respect to various permeant gases were investigated. High selectivities (up to 50,000) were achieved between small molecules (He, H{sub 2}) and large molecules (N{sub 2}, Ar, C{sub 6}H{sub 5}CH{sub 3}). The measured activation energies for the He and H{sub 2} permeability are 9.5 kcal/mol and 12 kcal/mol, respectively. The membranes synthesized at lower temperatures and lower ammonia flow rates showed good mechanical and chemical stability.

  13. Effects of Ti-Based Additives on the Hydrogen Storage Properties of aLiBH4/CaH2Destabilized System

    DOE PAGES [OSTI]

    Yang, Hongwei; Ibikunle, Adeola; Goudy, Andrew J.

    2010-01-01

    The hydrogen storage properties of a destabilizedLiBH4/CaH2system ball-milled withTiCl3,TiF3, andTiO2additives have been investigated. It is found that the system withTiCl3additive has a lower dehydrogenation temperature than the ones with other additives. Further study shows that a higher amount ofTiCl3is more effective in reducing the desorption temperature of theLiBH4/CaH2system, since it leads to a lower activation energy of dehydrogenation. The activations energies for mixtures containing 4, 10, and 25?mol% ofTiCl3are 141, 126, and 110?kJ/mol, respectively. However, the benefits of higher amounts ofTiCl3are offset by a larger reduction in hydrogen capacity of the mixtures.

  14. EVALUATION OF CARBON DIOXIDE CAPTURE FROM EXISTING COAL FIRED PLANTS BY HYBRID SORPTION USING SOLID SORBENTS

    SciTech Connect

    Benson, Steven; Palo, Daniel; Srinivasachar, Srivats; Laudal, Daniel

    2014-12-01

    Under contract DE-FE0007603, the University of North Dakota conducted the project Evaluation of Carbon Dioxide Capture from Existing Coal Fired Plants by Hybrid Sorption Using Solid Sorbents. As an important element of this effort, an Environmental Health and Safety (EH&S) Assessment was conducted by Barr Engineering Co. (Barr) in association with the University of North Dakota. The assessment addressed air and particulate emissions as well as solid and liquid waste streams. The magnitude of the emissions and waste streams was estimated for evaluation purposes. EH&S characteristics of materials used in the system are also described. This document contains data based on the mass balances from both the 40 kJ/mol CO2 and 80 kJ/mol CO2 desorption energy cases evaluated in the Final Technical and Economic Feasibility study also conducted by Barr Engineering.

  15. Carbonyl sulphide (COS) in geothermal fluids; An example from the Larderello field (Italy)

    SciTech Connect

    Chiodini, G. ); Cioni, R.; Raco, B. ); Scandiffio, G. )

    1991-01-01

    This paper reports that the carbonyl sulphide (COS) content in the fluids of 12 wells in the Larderello geothermal field ranges from 0.005 to 0.1 {mu}m mol/mol. Measured data are comparable with the theoretical concentrations, considering a homogeneous gas phase at the temperature and pressure conditions of the reservoir. However, the low temperature dependence of equilibrium constants of reactions involving COS prevents us from using them as geothermometers. On the contrary, P{sub CO{sub 2}} estimates in the gas equilibration zone can be inferred from the H{sub 2}S/COS ratio. The calculated CO{sub 2} partial pressures are comparable with those estimated by means of the H{sub 2}/CO ratio.

  16. Comparative Calculations of Solubility Equilibria

    SciTech Connect

    Beahm, E.C.

    2000-07-25

    The uncertainties in calculated solubilities in the Na-F-PO{sub 4}-HPO{sub 4}-OH system. at 25 C for NaOH concentrations up to 5 mol/kg were assessed. These uncertainties were based on an evaluation of the range of values for the Gibbs energies of the solids. Comparative calculations using the Environmental Simulation Program (ESP) and SOLGASMIX indicated that the variation in activity coefficients with NaOH concentration is much greater in the ESP code than in SOLGASMIX. This resulted in ESP calculating a higher solubility in water and a lower solubility in NaOH concentrations above 1 mol/kg: There was a marked discrepancy in the solubilities of the pure components sodium fluoride and trisodium phosphate predicted by ESP and SOLGASMIX. In addition, different solubilities for these components were obtained using different options in ESP. Because of these observations, a Best Practices Guide for ESP will be assembled.

  17. Vapor pressure osmometry studies on buckminsterfullerene

    SciTech Connect

    Honeychuck, R.V.; Cruger, T.W.; Milliken, J.

    1993-12-31

    Vapor pressure osmometry has been employed in studies of solutions of buckminsterfullerene (C{sub 60}. Two aromatic solvents were selected in order to obtain solutions which would be as concentrated as possible. The number-average molecular weights M{sub n} of C{sub 60} determined by analysis of the data are 930 {+-} 5 g mol{sup {minus}1} in chlorobenzene and 700 {+-} 10 g mol{sup {minus}1} in toluene), so the M{sub n} obtained in chlorobenzene is unexpected. Both determinations were performed with the same batch of C{sub 60}, which was processed to yield material of very high purity. The amount of interstitial N{sub 2} was determined using an appropriate method. The role if interstitial molecules, solvents in the crystal lattice, solvent-fullerene complexes, C{sub 70}, and C{sub 60} dimers in these measurements will be discussed.

  18. Tuned sensitivity towards H{sub 2}S and NH{sub 3} with Cu doped barium strontium titanate materials

    SciTech Connect

    Simion, C. E. Teodorescu, V. S.; Stănoiu, A.; Sackmann, A.; Ruşti, C. F.; Piticescu, R. M.

    2014-11-05

    The different amount of Cu-doped Barium Strontium Titanate (BST) thick film materials have been tested for their gas-sensing performances towards NH{sub 3} and H{sub 2}S under dry and 50% relative humidity (RH) background conditions. The optimum NH{sub 3} sensitivity was attained with 0.1mol% Cu-doped BST whereas the selective detection of H{sub 2}S was highlighted using 5mol% Cu-doped BST material. No cross-sensitivity effects to CO, NO{sub 2}, CH{sub 4} and SO{sub 2} were observed for all tested materials operated at their optimum temperature (200°C) under humid conditions (50% RH). The presence of humidity clearly enhances the gas sensitivity to NH{sub 3} and H{sub 2}S detection.

  19. Kinetics of sorption of Cu(II)-ethylenediaminetetraacetic acid chelated anions on cross-linked, polyaminated chitosan beads

    SciTech Connect

    Juang, R.S.; Ju, C.Y.

    1998-08-01

    Rates of sorption of Cu(II)-ethylenediaminetetraacetic acid (EDTA) chelated anions from aqueous solutions on cross-linked, poly(ethylenimine) (PEI)-modified chitosan beads were measured in a batch stirred vessel. All experiments were carried out in an equimolar solution of Cu(II) and EDTA (0.47--3.15 mol/m{sup 3}). It was shown that the rates of sorption increased with an increase in the initial concentration of Cu(II), pH, and temperature but decreased with an increase in the molecular weight of PEI introduced in the beads. The widely used homogeneous diffusion model based on Fick`s law and the shrinking core model cannot describe the sorption process. On the contrary, the kinetic data were well fit by the Elovich equation. The apparent activation energies evaluated (3.5--8.4 kcal/mol at pH 3) indicated the combined film and particle diffusion mechanism.

  20. Effects of Ti-Based Additives on the Hydrogen Storage Properties of a L i B H 4 / C a H 2 Destabilized System

    DOE PAGES [OSTI]

    Yang, Hongwei; Ibikunle, Adeola; Goudy, Andrew J.

    2010-01-01

    Tmore » he hydrogen storage properties of a destabilized LiBH 4 / CaH 2 system ball-milled with TiCl 3 , TiF 3 , and TiO 2 additives have been investigated. It is found that the system with TiCl 3 additive has a lower dehydrogenation temperature than the ones with other additives. Further study shows that a higher amount of TiCl 3 is more effective in reducing the desorption temperature of the LiBH 4 / CaH 2 system, since it leads to a lower activation energy of dehydrogenation.he activations energies for mixtures containing 4, 10, and 25 mol% of TiCl 3 are 141, 126, and 110 kJ/mol, respectively. However, the benefits of higher amounts of TiCl 3 are offset by a larger reduction in hydrogen capacity of the mixtures.« less

  1. Erbium hydride decomposition kinetics.

    SciTech Connect

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  2. Synthesis and stability of liquid molecular DT

    SciTech Connect

    Souers, P.C.; Fearon, E.M.; Garza, R.G.; Griffith, C.M.; Mayhugh, S.R.; Mapoles, E.R.; Tsurgawa, R.T.; Sater, J.D.; Collins, G.W.; Gaines, J.R.

    1988-01-01

    Regular equimolar deuterium-tritium is a mixture of 25 mol% T/sub 2/-50% DT-25% D/sub 2/. We have synthesized molecular DT of greater purity by the reaction LiT + CH/sub 3/OD ..-->.. DT + LiOCH/sub 3/, run at 243/degree/K. With both the alcohol and reactor-to-cryostat transfer lines at room temperature, we obtain 88 mol% DT purity. By cooling the alcohol and holding the transfer lines at 80/degree/K, the yield rose to 95% DT. The DT disproportionated to D/sub 2/ and T/sub 2/ with a le-time constant of about 100 hours in the liquid at 20.5/degree/K. Nuclear magnetic resonance data showed that the eventual T/sub 2/-DT-D/sub 2/ equilibrium is probably a /open quotes/hot-atom/close quotes/ one.

  3. Synthesis and stability of liquid molecular DT

    SciTech Connect

    Souers, P.C.; Fearon, E.M.; Garza, R.G.; Friffith, C.M.; Mayhugh, S.R.; Mapoles, E.R.; Tsugawa, R.T.; Sater, J.D.; Collins, G.W.; Gaines, J.R.

    1988-05-01

    Regular equimolar deuterium-tritium is a mixture of 25 mol% T/sub 2/-50% DT-25% D/sub 2/. We have synthesized molecular DT of greater purity by the reaction LiT + CH/sub 3/OD ..-->.. DT + LiOCH/sub 3/, run at 243/degree/K. With both the alcohol and reactor-to-cryostat transfer lines at room temperature, we obtain 88 mol% DT purity. By cooling the alcohol and holding the transfer lines at 80/degree/K, the yield rose to 95% DT. The DT disproportionated to D/sub 2/ and T/sub 2/ with a 1e time constant of about 100 h in the liquid at 20.5/degree/K. Nuclear magnetic resonance data showed that the eventual T/sub 2/-DT-D/sub 2/ equilibrium is probably a /open quotes/hot-atom/close quotes/ one. 15 refs., 4 figs., 1 tab.

  4. Synthesis and stability of liquid molecular DT

    SciTech Connect

    Pearon, E.M.; Garza, R.G.; Griffith, C.M.; Mayhugh, S.R.; Mapoles, E.R.; Sater, J.D.; Souers, P.C.; Tsugawa, R.T.; Gaines, J.R.; Collins, G.W.

    1988-09-01

    Regular equimolar deuterium-tritium is a mixture of 25 mol% T/sub 2/-50% DT-25% D/sub 2/. The authors have synthesized molecular DT of greater purity by the reaction LiT + CH/sub 3/OD /yields/ DT + LiOCH/sub 3/, run at 243 K. With both the alcohol and reactor-to-cryostat transfer lines at room temperature, they obtain the 88 mol% DT purity. By cooling the alcohol and holding the transfer lines at 80 K, the yield rose to 95% DT. The DT disproportionated to D/sub 2/ and T/sub 2/ with a 1/e time constant of about 100 hr in the liquid at 20.5 K. Nuclear magnetic resonance data showed that the eventual T/sub 2/-DT-D/sub 2/ equilibrium is probably a hot-atom one.

  5. Activation energy and enthalpy of decomposition for the Fe{sub 17}Sm{sub 2} nitride

    SciTech Connect

    Cabral, F.A.; Gama, S.; Ribeiro, C.A.

    1997-04-01

    Decomposition studies of the Fe{sub 17}Sm{sub 2}N{sub 3} compound were done using a Calvet-type microcalorimeter and a simultaneous gravimetric and differential thermal analyzer (DTA). The results show that the decomposition has onset temperature of 570{degree}C and proceeds up to 900{degree}C, and presents only one well determined exothermic thermal event. The calorimetric measurement shows that the enthalpy associated with the decomposition is 69 kJ/mol. The activation energy of the process was also determined using the Kissinger method applied to the DTA signal. It was observed that there was only one activation energy for the decomposition process, with a value of 339 kJ/mol. {copyright} {ital 1997 American Institute of Physics.}

  6. Improved spectrophotometric analysis of barium styphnate

    SciTech Connect

    Brown, N E; Blasi, J A

    1983-01-01

    A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.

  7. Ternary ceramic alloys of Zr-Ce-Hf oxides

    DOEpatents

    Becher, P.F.; Funkenbusch, E.F.

    1990-11-20

    A ternary ceramic alloy is described which produces toughening of zirconia and zirconia composites through the stress transformation from tetragonal phase to monoclinic phase. This alloy, having the general formula Ce[sub x]Hf[sub y]Zr[sub 1[minus]x[minus]y]O[sub 2], is produced through the addition of appropriate amounts of ceria and hafnia to the zirconia. Typically, improved toughness is achieved with about 5 to about 15 mol % ceria and up to about 40 mol % hafnia. The preparation of alloys of these compositions are given together with data as to the densities, tetragonal phase content, hardness and fracture toughness. The alloys are useful in preparing zirconia bodies as well as reinforcing ceramic composites. 1 fig.

  8. Ternary ceramic alloys of ZR-CE-HF oxides

    DOEpatents

    Becher, Paul F.; Funkenbusch, Eric F.

    1990-01-01

    A ternary ceramic alloy which produces toughening of zirconia and zirconia composites through the stress transformation from tetragonal phase to monoclinic phase. This alloy, having the general formula Ce.sub.x Hf.sub.y Zn.sub.1-x-y O.sub.2, is produced through the addition of appropriate amounts of ceria and hafnia to the zirconia. Typically, improved toughness is achieved with about 5 to about 15 mol % ceria and up to about 40 mol % hafnia. The preparation of alloys of these compositions are given together with data as to the densities, tetragonal phase content, hardness and fracture toughness. The alloys are useful in preparing zirconia bodies as well as reinforcing ceramic composites.

  9. Fundamental aspects of recoupled pair bonds. II. Recoupled pair bond dyads in carbon and sulfur difluoride

    SciTech Connect

    Dunning, Thom H. Takeshita, Tyler Y.; Xu, Lu T.

    2015-01-21

    Formation of a bond between a second ligand and a molecule with a recoupled pair bond results in a recoupled pair bond dyad. We examine the recoupled pair bond dyads in the a{sup 3}B{sub 1} states of CF{sub 2} and SF{sub 2}, which are formed by the addition of a fluorine atom to the a{sup 4}Σ{sup −} states of CF and SF, both of which possess recoupled pair bonds. The two dyads are very different. In SF{sub 2}, the second FS–F bond is very strong (D{sub e} = 106.3 kcal/mol), the bond length is much shorter than that in the SF(a{sup 4}Σ{sup −}) state (1.666 Å versus 1.882 Å), and the three atoms are nearly collinear (θ{sub e} = 162.7°) with only a small barrier to linearity (0.4 kcal/mol). In CF{sub 2}, the second FC–F bond is also very strong (D{sub e} = 149.5 kcal/mol), but the bond is only slightly shorter than that in the CF(a{sup 4}Σ{sup −}) state (1.314 Å versus 1.327 Å), and the molecule is strongly bent (θ{sub e} = 119.0°) with an 80.5 kcal/mol barrier to linearity. The a{sup 3}B{sub 1} states of CF{sub 2} and SF{sub 2} illustrate the fundamental differences between recoupled pair bond dyads formed from 2s and 3p lone pairs.

  10. ENERGY EFFICIENCY LIMITS FOR A RECUPERATIVE BAYONET SULFURIC ACID DECOMPOSITION REACTOR FOR SULFUR CYCLE THERMOCHEMICAL HYDROGEN PRODUCTION

    SciTech Connect

    Gorensek, M.; Edwards, T.

    2009-06-11

    A recuperative bayonet reactor design for the high-temperature sulfuric acid decomposition step in sulfur-based thermochemical hydrogen cycles was evaluated using pinch analysis in conjunction with statistical methods. The objective was to establish the minimum energy requirement. Taking hydrogen production via alkaline electrolysis with nuclear power as the benchmark, the acid decomposition step can consume no more than 450 kJ/mol SO{sub 2} for sulfur cycles to be competitive. The lowest value of the minimum heating target, 320.9 kJ/mol SO{sub 2}, was found at the highest pressure (90 bar) and peak process temperature (900 C) considered, and at a feed concentration of 42.5 mol% H{sub 2}SO{sub 4}. This should be low enough for a practical water-splitting process, even including the additional energy required to concentrate the acid feed. Lower temperatures consistently gave higher minimum heating targets. The lowest peak process temperature that could meet the 450-kJ/mol SO{sub 2} benchmark was 750 C. If the decomposition reactor were to be heated indirectly by an advanced gas-cooled reactor heat source (50 C temperature difference between primary and secondary coolants, 25 C minimum temperature difference between the secondary coolant and the process), then sulfur cycles using this concept could be competitive with alkaline electrolysis provided the primary heat source temperature is at least 825 C. The bayonet design will not be practical if the (primary heat source) reactor outlet temperature is below 825 C.

  11. Water and Carbon Dioxide Adsorption at Olivine Surfaces

    SciTech Connect

    Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

    2013-11-14

    Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

  12. Thermodynamic study of orthorhombic T{sup x} and tetragonal T? lanthanum cuprate, La{sub 2}CuO{sub 4}

    SciTech Connect

    Lilova, K.I.; Hord, R.; Alff, L.; Albert, B.; Navrotsky, A.

    2013-08-15

    The enthalpies of transition among the T{sup x}, T?, and TLa{sub 2}CuO{sub 4} phases are obtained from a combination of differential scanning calorimetry, high temperature oxide melt solution calorimetry, and transposed temperature drop calorimetry. The enthalpy of transformation of T{sup x} to T is 2.320.07 kJ/mol and the corresponding entropy of transition is 4.380.13 J/(mol K). The T? modification, with an average of 1.40 kJ/mol, is less stable in enthalpy than T{sup x} but at 0.96 kJ/mol, more stable in enthalpy than T. Although we cannot rule out a small stability field at temperatures near the T{sup x}T transition at 530 K, T? is most likely metastable at all temperatures. - Graphical abstract: Crystal structure of T{sup x} (orthorhombic), T? and T (tetragonal) modifications of La{sub 2}CuO{sub 4} (left to right). The space group for orthorhombic T{sup x} is Cmce and I4/mmm for both T? and T structures; copper cations are presented as small purple, lanthanum as large blue and oxygen as large green circles. Highlights: The enthalpies of transition among the T{sup x} , T?, and T-La{sub 2}CuO{sub 4} phases are obtained. The T{sup x} phase is the lowest in energy, the T? higher and the T highest. T? phase is metastable at all temperatures.

  13. THE ABUNDANCE OF MOLECULAR HYDROGEN AND ITS CORRELATION WITH MIDPLANE PRESSURE IN GALAXIES: NON-EQUILIBRIUM, TURBULENT, CHEMICAL MODELS

    SciTech Connect

    Mac Low, Mordecai-Mark; Glover, Simon C. O. E-mail: glover@uni-heidelberg.de

    2012-02-20

    Observations of spiral galaxies show a strong linear correlation between the ratio of molecular to atomic hydrogen surface density R{sub mol} and midplane pressure. To explain this, we simulate three-dimensional, magnetized turbulence, including simplified treatments of non-equilibrium chemistry and the propagation of dissociating radiation, to follow the formation of H{sub 2} from cold atomic gas. The formation timescale for H{sub 2} is sufficiently long that equilibrium is not reached within the 20-30 Myr lifetimes of molecular clouds. The equilibrium balance between radiative dissociation and H{sub 2} formation on dust grains fails to predict the time-dependent molecular fractions we find. A simple, time-dependent model of H{sub 2} formation can reproduce the gross behavior, although turbulent density perturbations increase molecular fractions by a factor of few above it. In contradiction to equilibrium models, radiative dissociation of molecules plays little role in our model for diffuse radiation fields with strengths less than 10 times that of the solar neighborhood, because of the effective self-shielding of H{sub 2}. The observed correlation of R{sub mol} with pressure corresponds to a correlation with local gas density if the effective temperature in the cold neutral medium of galactic disks is roughly constant. We indeed find such a correlation of R{sub mol} with density. If we examine the value of R{sub mol} in our local models after a free-fall time at their average density, as expected for models of molecular cloud formation by large-scale gravitational instability, our models reproduce the observed correlation over more than an order-of-magnitude range in density.

  14. Biographical sketch - Kevin Redding | Center for Bio-Inspired Solar Fuel

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Production Kevin Redding a. Professional Preparation Rice University Biochemistry B. S., 1987 Stanford University Biochemistry Ph. D., 1993 University of Geneva Mol. Biology Postdoctoral studies, 1994 - 1998 b. Area of Specialization: Structure/function analysis of biological electron transfer c. Appointments Arizona State University, Associate Professor of Chemistry (1/1/08 - present) Chercheur associé (CNRS), Institut de Biologie Physico-Chimique, Paris (8/15/07-7/20/08) and Fulbright

  15. Biological Applications

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Biological Applications Biological Applications Bioscience technologies for biosecurity, infectious disease, and other threats. Bioscience Capabilities-for Collaboration View our capability sheets: get details of what we do. Atomic Magnetometer Micro Imaging MOL PCR Raman LIBS Waveguide Biosensor How we deploy innovation bioscience-foundational-science Cell biology hasn't been the same since Los Alamos pioneered flow cytometry in mid-1960s when a Lab scientist invented a cell separator that

  16. Toxicity to embryo and adult zebrafish of copper complexes with two malonic acids as models for dissolved organic matter

    SciTech Connect

    Palmer, F.B.; Evans, C.W.; Butler, C.A.; Timperley, M.H.

    1998-08-01

    The toxicity to embryo and adult zebrafish (Danio rerio) of Cu complexes with two substituted malonic acids, benzyl- and n-hexadecyl-, chosen as models for low-molecular-weight natural dissolved organic matter, were investigated. Toxicity test solutions at pH 6.5 {+-} 0.1 with the required Cu ion-specific electrode. In the absence of malonic acids, concentrations of Cu{sup 2+} up to 1.13 {mu}mol/L increased the embryo hatching time from approx. 2 d in control solutions (no Cu or malonic acid) and solutions containing malonic acids without Cu to approx. 8 d. The Cu-benzylmalonic acid complex in the presence of inorganic Cu species did not delay hatching beyond that attributable to Cu{sup 2+}. In contrast, 0.60 {mu}mol/L Cu-n-hexadecylmalonic complexes delayed hatching by 5.5 d in excess of that attributable to 1.13 {mu}mol/L Cu{sup 2+}, assuming that the hatching delays caused by the different Cu species were additive, possibly because of Cu entry into the embryo as the lipophilic Cu-n-hexadecylmalonic complex. None of the Cu-malonic acid complexes was acutely toxic to adult zebrafish at concentrations up to 1.4 {mu}mol/L, possibly because Cu was removed from the Cu-malonic acid complexes by stronger chelating groups at the gill surface. Substituted malonic acids with similar proton and Cu association constants can be readily prepared with a variety of simple substituents, radiolabeled if required. Their results show that these acids could be useful ligands for investigating intracellular transport and metabolism of metal-organic complexes.

  17. Reversible Electrocatalytic Production and Oxidation of Hydrogen at Low Overpotentials by a Functional Hydrogenase Mimic

    SciTech Connect

    Smith, Stuart E.; Yang, Jenny Y.; DuBois, Daniel L.; Bullock, Morris

    2012-03-26

    A new bis(diphosphine) nickel(II) complex, [Ni(PPh2NR2)2](BF4)2, 1, (R = CH2CH2OCH3) is described. A {Delta}G{sup o} of 0.84 kcal/mol{sup -1} for hydrogen addition for this complex was calculated from the experimentally determined equilibrium constant. This complex displays reversible electrocatalytic activity for hydrogen production and oxidation at low overpotentials, a characteristic most commonly associated with hydrogenase enzymes.

  18. Role of associated defects in oxygen ion conduction and surface exchange reaction for epitaxial samaria-doped ceria thin films as catalytic coatings

    DOE PAGES [OSTI]

    Yang, Nan; Shi, Yanuo; Schweiger, Sebastian; Strelcov, Evgheni; Foglietti, Vittorio; Orgiani, Pasquale; Balestrino, Giuseppe; Kalinin, Sergei V.; Jennifer L. M. Rupp; Aruta, Carmela; et al

    2016-05-18

    Samaria-doped ceria (SDC) thin films are particularly important for energy and electronic applications such as micro-solid oxide fuel cells, electrolysers, sensors and memristors. In this paper we report a comparative study investigating ionic conductivity and surface reactions for well-grown epitaxial SDC films varying the samaria doping concentration. With increasing doping above 20 mol% of samaria, an enhancement in the defect association was observed by Raman spectroscopy. The role of such defect associates on the films` oxygen ion transport and exchange was investigated by electrochemical impedance spectroscopy and electrochemical strain microscopy (ESM). The measurements reveal that the ionic transport has amore » sharp maximum in ionic conductivity and drop in its activation energy down to 0.6 eV for 20 mol% doping. Increasing the doping concentration further up to 40 mol%, raises the activation energy substantially by a factor of two. We ascribe the sluggish transport kinetics to the "bulk" ionic-near ordering in case of the heavily doped epitaxial films. Analysis of the ESM first order reversal curve measurements indicate that these associated defects may have a beneficial role by lowering the activation of the oxygen exchange "surface" reaction for heavily doped 40 mol% of samaria. We reveal in a model experiment through a solid solution series of samaria doped ceria epitaxial films that the occurrence of associate defects in the bulk affects the surface charging state of the films to increase the exchange rates. Lastly, the implication of these findings are the design of coatings with tuned oxygen surface exchange by control of bulk associate clusters for future electro-catalytic applications.« less

  19. Aqueous Binary Lanthanide(III) Nitrate Ln(NO3)3 Electrolytes Revisited: Extended Pitzer and Bromley Treatments

    SciTech Connect

    Chatterjee, Sayandev; Campbell, Emily L.; Neiner, Doinita; Pence, Natasha; Robinson, Troy; Levitskaia, Tatiana G.

    2015-09-11

    To date, only limited thermodynamic models describing activity coefficients of the aqueous solutions of lanthanide ions are available. This work expands the existing experimental osmotic coefficient data obtained by classical isopiestic technique for the aqueous binary trivalent lanthanide nitrate Ln(NO3)3 solutions using a combination of water activity and vapor pressure osmometry measurements. The combined osmotic coefficient database for each aqueous lanthanide nitrate at 25°C, consisting of literature available data as well as data obtained in this work, was used to test the validity of Pitzer and Bromley thermodynamic models for the accurate prediction of mean molal activity coefficients of the Ln(NO3)3 solutions in wide concentration ranges. The new and improved Pitzer and Bromley parameters were calculated. It was established that the Ln(NO3)3 activity coefficients in the solutions with ionic strength up to 12 mol kg-1 can be estimated by both Pitzer and single-parameter Bromley models, even though the latter provides for more accurate prediction, particularly in the lower ionic strength regime (up to 6 mol kg-1). On the other hand for the concentrated solutions, the extended three-parameter Bromley model can be employed to predict the Ln(NO3)3 activity coefficients with remarkable accuracy. The accuracy of the extended Bromley model in predicting the activity coefficients was greater than ~95% and ~90% for all solutions with the ionic strength up to 12 mol kg-1 and and 20 mol kg-1, respectively. This is the first time that the activity coefficients for concentrated lanthanide solutions have been predicted with such a remarkable accuracy.

  20. Quantum effects and anharmonicity in the H{sub 2}-Li{sup +}-benzene complex: A model for hydrogen storage materials

    SciTech Connect

    Kolmann, Stephen J.; D'Arcy, Jordan H.; Jordan, Meredith J. T.

    2013-12-21

    Quantum and anharmonic effects are investigated in H{sub 2}-Li{sup +}-benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials. Three- and 8-dimensional quantum diffusion Monte Carlo (QDMC) and rigid-body diffusion Monte Carlo (RBDMC) simulations are performed on potential energy surfaces interpolated from electronic structure calculations at the M05-2X/6-31+G(d,p) and M05-2X/6-311+G(2df,p) levels of theory using a three-dimensional spline or a modified Shepard interpolation. These calculations investigate the intermolecular interactions in this system, with three- and 8-dimensional 0 K H{sub 2} binding enthalpy estimates, ?H{sub bind} (0 K), being 16.5 kJmol{sup ?1} and 12.4 kJmol{sup ?1}, respectively: 0.1 and 0.6 kJmol{sup ?1} higher than harmonic values. Zero-point energy effects are 35%of the value of ?H{sub bind} (0 K) at M05-2X/6-311+G(2df,p) and cannot be neglected; uncorrected electronic binding energies overestimate ?H{sub bind} (0 K) by at least 6 kJmol{sup ?1}. Harmonic intermolecular binding enthalpies can be corrected by treating the H{sub 2} helicopter and ferris wheel rotations as free and hindered rotations, respectively. These simple corrections yield results within 2% of the 8-dimensional anharmonic calculations. Nuclear ground state probability density histograms obtained from the QDMC and RBDMC simulations indicate the H{sub 2} molecule is delocalized above the Li{sup +}-benzene system at 0 K.

  1. Negative Ion Photoelectron Spectroscopy Confirms the Prediction that (CO)5 and (CO)6 Each Has a Singlet Ground State

    SciTech Connect

    Bao, Xiaoguang; Hrovat, David; Borden, Weston; Wang, Xue B.

    2013-03-20

    Cyclobutane-1,2,3,4-tetraone has been both predicted and found to have a triplet ground state, in which a b2g MO and an a2u MO is each singly occupied. In contrast, (CO)5 and (CO)6 have each been predicted to have a singlet ground state. This prediction has been tested by generating the (CO)5 - and (CO)6 - anions in the gas-phase by electrospray vaporization of solutions of, respectively, the croconate (CO)52- and rhodizonate (CO)62- dianions. The negative ion photoelectron (NIPE) spectra of the (CO)5•- radical anion give electron affinity (EA) = 3.830 eV and a singlet ground state for (CO)5, with the triplet higher in energy by 0.850 eV (19.6 kcal/mol). The NIPE spectra of the (CO)6•- radical anion give EA = 3.785 eV and a singlet ground state for (CO)6, with the triplet higher in energy by 0.915 eV (21.1 kcal/mol). (RO)CCSD(T)/aug-cc-pVTZ//(U)B3LYP/6-311+G(2df) calculations give EA values that are only ca. 1 kcal/mol lower than those measured and EST values that are only 2 - 3 kcal/mol higher than those obtained from the NIPE spectra. Thus, the calculations support the interpretations of the NIPE spectra and the finding, based on the spectra, that (CO)5 and (CO)6 both have a singlet ground state.

  2. Supercritical Fluid Extraction of Plutonium and Americium from Soil

    SciTech Connect

    Fox, Robert Vincent; Mincher, Bruce Jay

    2002-08-01

    Supercritical fluid extraction (SFE) of plutonium and americium from soil was successfully demonstrated using supercritical fluid carbon dioxide solvent augmented with organophosphorus and beta-diketone complexants. Spiked Idaho soils were chemically and radiologically characterized, then extracted with supercritical fluid carbon dioxide at 2,900 psi and 65°C containing varying concentrations of tributyl phosphate (TBP) and thenoyltrifluoroacetone (TTA). A single 45 minute SFE with 2.7 mol% TBP and 3.2 mol% TTA provided as much as 88% ± 6.0 extraction of americium and 69% ± 5.0 extraction of plutonium. Use of 5.3 mol% TBP with 6.8 mol% of the more acidic beta-diketone hexafluoroacetylacetone (HFA) provided 95% ± 3.0 extraction of americium and 83% ± 5.0 extraction of plutonium in a single 45 minute SFE at 3,750 psi and 95°C. Sequential chemical extraction techniques were used to chemically characterize soil partitioning of plutonium and americium in pre-SFE soil samples. Sequential chemical extraction techniques demonstrated that spiked plutonium resides primarily (76.6%) in the sesquioxide fraction with minor amounts being absorbed by the oxidizable fraction (10.6%) and residual fractions (12.8%). Post-SFE soils subjected to sequential chemical extraction characterization demonstrated that 97% of the oxidizable, 78% of the sesquioxide and 80% of the residual plutonium could be removed using SFE. These preliminary results show that SFE may be an effective solvent extraction technique for removal of actinide contaminants from soil.

  3. Blocking effect of crystalglass interface in lanthanum doped barium strontium titanate glassceramics

    SciTech Connect

    Wang, Xiangrong; Zhang, Yong; Baturin, Ivan; Liang, Tongxiang

    2013-10-15

    Graphical abstract: The blocking effect of the crystalglass interface on the carrier transport behavior in the lanthanum doped barium strontium titanate glassceramics: preparation and characterization. - Highlights: La{sub 2}O{sub 3} addition promotes the crystallization of the major crystalline phase. The Z? and M? peaks exist a significant mismatch for 0.5 mol% La{sub 2}O{sub 3} addition. The Z? and M? peaks separate obviously for 1.0 mol% La{sub 2}O{sub 3} addition. Crystallite impedance decreases while crystalglass interface impedance increases. La{sub 2}O{sub 3} addition increases blocking factor of the crystalglass interface. - Abstract: The microstructures and dielectric properties in La{sub 2}O{sub 3}-doped barium strontium titanate glassceramics have been investigated by scanning electron microscopy (SEM) and impedance spectroscopy. SEM analysis indicated that La{sub 2}O{sub 3} additive decreases the average crystallite size. Impedance spectroscopy revealed that the positions of Z? and M? peaks are close for undoped samples. When La{sub 2}O{sub 3} concentration is 0.5 mol%, the Z? and M? peaks show a significant mismatch. Furthermore, these peaks separate obviously for 1.0 mol% La{sub 2}O{sub 3} addition. With increasing La{sub 2}O{sub 3} concentration, the contribution of the crystallite impedance becomes smaller, while the contribution of the crystalglass interface impedance becomes larger. More interestingly, it was found that La{sub 2}O{sub 3} additive increases blocking factor of the crystalglass interface in the temperature range of 250450 C. This may be attributed to a decrease of activation energy of the crystallite and an increase of the crystalglass interface area.

  4. Low-temperature aqueous-phase reforming of ethanol on bimetallic PdZn catalysts

    SciTech Connect

    Xiong, Haifeng; DelaRiva, Andrew; Wang, Yong; Dayte, Abhaya

    2015-01-01

    Bimetallic PdZn catalysts supported on carbon black (CB) and carbon nanotubes (CNTs) were found to be selective for CO-free H-2 production from ethanol at low temperature (250 degrees C). On Pd, the H-2 yield was low (similar to 0.3 mol H-2/mol ethanol reacted) and the CH4/CO2 ratio was high (similar to 1.7). Addition of Zn to Pd formed the intermetallic PdZn beta phase (atomic ratio of Zn to Pd is 1) with increased H-2 yield (similar to 1.9 mol H-2/mol ethanol reacted) and CH4/CO2 ratio of <1. The higher H-2 yield and low CH4 formation was related to the improved dehydrogenation activity of the L1(0) PdZn beta phase. The TOF increased with particle size and the CNTs provided the most active and selective catalysts, which may be ascribed to pore-confinement effects. Furthermore, no significant changes in either the supports or the PdZn beta particles was found after aqueous-phase reforming (APR) indicating that the metal nanoparticles and the carbon support are hydrothermally stable in the aqueous phase at elevated temperatures and pressures (>200 degrees C, 65 bar). No CO was detected for all the catalysts performed in aqueous-phase reaction, indicating that both monometallic Pd and bimetallic PdZn catalysts have high water-gas shift activity during APR. However, the yield of H-2 is considerably lower than the theoretical value of 6 H-2 per mole ethanol which is due to the presence of oxygenated products and methane on the PdZn catalysts.

  5. Routine production of copper-64 using 11.7MeV protons

    SciTech Connect

    Jeffery, C. M.; Smith, S. V.; Asad, A. H.; Chan, S.; Price, R. I.

    2012-12-19

    Reliable production of copper-64 ({sup 64}Cu) was achieved by irradiating enriched nickel-64 ({sup 64}Ni, >94.8%) in an IBA 18/9 cyclotron. Nickel-64 (19.1 {+-} 3.0 mg) was electroplated onto an Au disc (125{mu}m Multiplication-Sign 15mm). Targets were irradiated with 11.7 MeV protons for 2 hours at 40{mu}A. Copper isotopes ({sup 60,61,62,64}Cu) were separated from target nickel and cobalt isotopes ({sup 55,57,61}Co) using a single ion exchange column, eluted with varying concentration of low HCl alcohol solutions. The {sup 64}Ni target material was recovered and reused. The {sup 64}Cu production rate was 1.46{+-}0.3MBq/{mu}A.hr/mg{sup 64}Ni(n = 10) (with a maximum of 2.6GBq of {sup 64}Cu isolated after 2hr irradiation at 40uA. Radionuclidic purity of the {sup 64}Cu was 98.7 {+-} 1.6 % at end of separation. Cu content was < 6mg/L (n = 21). The specific activity of {sup 64}Cu was determined by ICP-MS and by titration with Diamsar to be 28.9{+-}13.0GBq/{mu}mol[0.70{+-}0.35Ci/{mu}mol]/({mu}A.hr/mg{sup 64}Ni)(n = 10) and 13.1{+-}12.0GBq/{mu}mol[0.35{+-}0.32Ci/{mu}mol]/({mu}A.hr/mg{sup 64}Ni)(n 9), respectively; which are in agreement, however, further work is required.

  6. Enhancing the Performance of a Redox Active Polymer via Specific

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Electrolyte Interactions - Joint Center for Energy Storage Research March 30, 2016, Research Highlights Enhancing the Performance of a Redox Active Polymer via Specific Electrolyte Interactions Poly (para-nitrostyrene) (PNS) is an attractive candidate for use as an anolyte material in size exclusion non-aqueous redox flow batteries because of its low reduction potential and its equivalent weight of only 149 g/mol. This polymer has highly reversible electrochemistry in TBA+ salts, but is

  7. Dielectric behavior of samarium-doped BaZr{sub 0.2}Ti{sub 0.8}O{sub 3} ceramics

    SciTech Connect

    Li, Yuanliang; Wang, Ranran; Ma, Xuegang; Li, Zhongqiu; Sang, Rongli; Qu, Yuanfang

    2014-01-01

    Graphical abstract: - Highlights: • We investigate dielectric properties and phase transition of Sm{sup 3+}-doped BaZr{sub 0.2}Ti{sub 0.8}O{sub 3} ceramics. • The additive amount of Sm{sub 2}O{sub 3} can greatly affect the dielectric properties. • The materials undergo a diffuse type ferroelectric phase transition. • There is an alternation of substitution preference of Sm{sup 3+} ion for the host cations in perovskite lattice. - Abstract: The dielectric properties and phase transition of Sm{sup 3+}-doped BaZr{sub 0.2}Ti{sub 0.8}O{sub 3} (BZT20) ceramics were investigated. Room temperature X-ray diffraction study suggested that the compositions had single-phase cubic symmetry. Microstructure studies showed that the grain size decreased and that the Sm{sub 2}O{sub 3} amount markedly affected the dielectric properties of BZT20. A dielectric constant of 5700 at 0.2 mol% Sm{sub 2}O{sub 3} and a dissipation factor of only 0.0011 at 2 mol% Sm{sub 2}O{sub 3} were observed, indicating that BZT20 had significant potential applications. Moreover, the dielectric constant, dissipation factor, phase-transition temperature, and maximum dielectric constant increased with increased Sm{sub 2}O{sub 3} amount at ≤0.2 mol% Sm{sub 2}O{sub 3} but decreased with increased Sm{sub 2}O{sub 3} amount at >0.2 mol% Sm{sub 2}O{sub 3}.

  8. Crack growth rates and metallographic examinations of Alloy 600 and Alloy 82/182 from field components and laboratory materials tested in PWR environments.

    SciTech Connect

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.

    2008-05-05

    In light water reactors, components made of nickel-base alloys are susceptible to environmentally assisted cracking. This report summarizes the crack growth rate results and related metallography for field and laboratory-procured Alloy 600 and its weld alloys tested in pressurized water reactor (PWR) environments. The report also presents crack growth rate (CGR) results for a shielded-metal-arc weld of Alloy 182 in a simulated PWR environment as a function of temperature between 290 C and 350 C. These data were used to determine the activation energy for crack growth in Alloy 182 welds. The tests were performed by measuring the changes in the stress corrosion CGR as the temperatures were varied during the test. The difference in electrochemical potential between the specimen and the Ni/NiO line was maintained constant at each temperature by adjusting the hydrogen overpressure on the water supply tank. The CGR data as a function of temperature yielded activation energies of 252 kJ/mol for a double-J weld and 189 kJ/mol for a deep-groove weld. These values are in good agreement with the data reported in the literature. The data reported here and those in the literature suggest that the average activation energy for Alloy 182 welds is on the order of 220-230 kJ/mol, higher than the 130 kJ/mol commonly used for Alloy 600. The consequences of using a larger value of activation energy for SCC CGR data analysis are discussed.

  9. Engineering Database of Liquid Salt Thermophysical and Thermochemical Properties

    SciTech Connect

    Manohar S. Sohal; Matthias A. Ebner; Piyush Sabharwall; Phil Sharpe

    2010-03-01

    The purpose of this report is to provide a review of thermodynamic and thermophysical properties of candidate molten salt coolants, which may be used as a primary coolant within a nuclear reactor or heat transport medium from the Next Generation Nuclear Plant (NGNP) to a processing plant, for example, a hydrogen-production plant. Thermodynamic properties of four types of molten salts, including LiF-BeF2 (67 and 33 mol%, respectively; also known as FLiBe), LiF-NaF-KF (46.5, 11.5, and 52 mol%, also known as FLiNaK), and KCl-MgCl2 (67 and 33 mol%), and sodium nitrate-sodium nitrite-potassium nitrate (NaNO3–NaNO2–KNO3, (7-49-44 or 7-40-53 mol%) have been investigated. Limitations of existing correlations to predict density, viscosity, specific heat capacity, surface tension, and thermal conductivity, were identified. The impact of thermodynamic properties on the heat transfer, especially Nusselt number was also discussed. Stability of the molten salts with structural alloys and their compatibility with the structural alloys was studied. Nickel and alloys with dense Ni coatings are effectively inert to corrosion in fluorides but not so in chlorides. Of the chromium containing alloys, Hastelloy N appears to have the best corrosion resistance in fluorides, while Haynes 230 was most resistant in chloride. In general, alloys with increasing carbon and chromium content are increasingly subject to corrosion by the fluoride salts FLiBe and FLiNaK, due to attack and dissolution of the intergranular chromium carbide. Future research to obtain needed information was identified.

  10. Relationship between substrate concentration and fermentation product ratios in Clostridium thermocellum cultures

    SciTech Connect

    Brener, D.; Johnson, B.F.

    1984-05-01

    Growth of Clostridium thermocellum in batch cultures was studied over a broad range of cellobiose concentrations. Cultures displayed important differences in their substrate metabolism as determined by the end product yields. Bacterial growth was severly limited when the initial cellobiose concentration was 0.2 (wt/vol), was maximal at substrate concentrations between 0.5 and 2.0%, and did not occur at 5.0% cellobiose. Ethanol accumulated maximally (38.3% ..mu..mol/10/sup 9/ cells) in cultures with an initial cellobiose concentration of 0.8%, whereas cultures in 2.0% cellobiose accumulated on 17.3 ..mu..mol, and substrate-limited cultures (0.2% cellobiose) accumulated little, if any, ethanol beyond that initially detected (8.3 ..mu..mol/10/sup 9/ cells). In a medium with 0.8% cellobiose, ethanol was produced at a constant rate of approximately 1.1 ..mu..mol/10/sup 9/ cells per h from late-logarithmic phase (16 h) of growth well into stationary phase (44 h). When ethanol was added exogenously at levels more than twice the maximum produced by the cultures themselves (0.5% vol/vol), neither the extent of growth (maximum Klett units, 150) nor the amounts of ethanol produced (approximately 0.17%) by the culture was affected. The ratio of ethanol to acetate was highest (2.8) when cells were grown in 0.8% cellobiose and lowest (1.2) when cells were grown in 0.2% cellobiose. 18 references.

  11. A vapor-pressure study of the systems formed by polonium with palladium and iridium

    SciTech Connect

    Abakumou, A.S.; Khokhlou, A.D.; Malysheu, M.L.; Reznikova, N.F.

    1985-11-01

    Direct thermal vacuum synthesis shows that polonium vapor does not react with iridium when they are heated together to 1000/sup 0/C. Polonium vapor begins to be absorbed appreciably by palladium at 340-350/sup 0/C. The radiotensimetric method has been used in examining the thermal stabilities of polonium-palladium comounds, which has shown that there are three intermetallides PdPo, Pd/sub 2/Po, and Pd/sub 3/Po, which dissociate to release elemental polonium. The dissociation temperature increases as the polonium content of the compound decreases and is in the range 390-700/sup 0/C. The temperature dependence of the polonium vapor pressure in the dissociation is described by the following: PdPo log P /SUB Pa/ = (7.31 + or - 0.08) -- (4520 + or -40)/T, and at 460580/sup 0/C, ..delta..H = 86.3 + or - 0.7 kJ/mol; Pd/sub 2/Po log P /SUB Pa/ = (7.42 + or - 0.01) -- (6080 + or 10)/T at 725900/sup 0/C, ..delta..H = 116 + or - 0.2 kJ/mol; Pd/sub 3/Po log P /SUB Pa/ = (9.18 + or - 0.01) -- (8620 + or 1000/sup 0/C, ..delta..H = 164 + or - 1 kJ/mol. The properties of these compounds are compared with those of the corresponding tellurides and of the polonium-nickel and poloniumplatinum systems.

  12. Direct measurement of the enthalpy of fusion of diopside

    SciTech Connect

    Ziegler, D.; Navrotsky, A.

    1986-11-01

    Crystalline diopside, CaMgSi/sub 2/O/sub 6/, was dropped directly into a Setaram HT1500 calorimeter operating at high temperature. At 1575 < T < 1624 K, the heat content of the crystals was in excellent agreement with previously published results. Above 1634 K, a rise in the enthalpy was seen, supporting the incongruent melting reported by Kushiro. The total enthalpy of fusion at 1665 K, the nominal melting point, is 138.5 kJ/mol, in excellent agreement with measurements which used a cycle that involves dropping the liquid to form a glass and measuring heats of solution of glass and crystals. The heat content of a glassy diopside starting material was also measured. Because the calorimetric experiment lasts only about 8 minutes, these measurements could be extended into the supercooled liquid range (to 1170 K) before the onset of rapid crystallization. A change in slope in the measured heat contents gives a glass transition temperature of 9333 K, about 70 K lower than that reported by other methods. A linear fit of all the data above T/sub g/ (supercooled liquid at 970 to 1170 K, stable liquid at 1668 to 1766 K) gives an average heat capacity for the liquid of 332.8 J/mol/ x K, comparable to the value of 334.6 J/mol x K reported by Richet and Bottinga.

  13. Phase Stability of Chromium(III) Oxide Hydroxide in Alkaline Sodium Phosphate Solutions

    SciTech Connect

    S.E. Ziemniak; E.P. Opalka

    2003-07-08

    Grimaldiite ({alpha}-CrOOH) is shown to transform to a sodium-chromium(III)-hydroxyphosphate compound (SCHP) in alkaline sodium phosphate solutions at elevated temperatures via CrOOH(s) + 4Na{sup +} + 2HPO{sub 4}{sup 2-} = Na{sub 4}Cr(OH)(PO{sub 4}){sub 2}(s) + H{sub 2}O. X-ray diffraction analyses indicate that SCHP possesses an orthorhombic lattice having the same space group symmetry (Ibam, No.72) as sodium ferric hydroxyphosphate. A structurally-consistent designation for SCHP is Na{sub 3}Cr(PO{sub 4}){sub 2} {center_dot} NaOH; the molar volume of SCHP is estimated to be 1552 cm{sup 3}. The thermodynamic equilibrium for the above reaction was defined in the system Na{sub 2}O-P{sub 2}O{sub 5}-Cr{sub 2}O{sub 3}-H{sub 2}O for Na/P molar ratios between 2.0 and 2.4. On the basis of observed reaction threshold values for sodium phosphate concentration and temperature, the standard molar entropy (S{sup o}), heat capacity (C{sub p}{sup o}) and free energy of formation ({Delta}G{sub f}{sup o}) for SCHP were calculated to be 690 J/(mol-K), 622 J/(mol-K) and -3509.97 kJ/mol, respectively.

  14. Microcalorimetric measurement of reaction enthalpies in solutions of uranium and neptunium compounds

    SciTech Connect

    Schreiner, F.; Friedman, A.M.; Richards, R.R.; Sullivan, J.C.

    1984-01-01

    The formation of complexes of uranyl and neptunyl(VI) ions with carbonate and hydrogen carbonate has been studied by titration microcalorimetry. The measurements were carried out with a computer-controlled microcalorimeter which is described in detail. Sample volumes are typically in the range of 1.5 to 2.5 ccm, containing about 0.05 millimole of the ionic species to be studied. The small volume renders the calorimeter useful for the measurement of uncommon and strongly radioactive substances. Enthalpies of reaction were obtained for the formation of the dicarbonato and the tricarbonato uranyl ions in a sulfate medium of ionic strength 1.6. The enthalpies are ..delta..H/sub 2/ = -39.6 +- 1 kJ/mol and -57.5 +- 1.5 kJ/mol, respectively. The titration data for the neptunyl(VI) - carbonate system yield a value of -50 +- 2 kJ/mol for the tricarbonato-neptunyl ion when interpreted in analogy to the uranyl system.

  15. Linear rheology and structure of molecular bottlebrushes with short side chains

    SciTech Connect

    López-Barrón, Carlos R. Brant, Patrick; Crowther, Donna J.; Eberle, Aaron P. R.

    2015-05-15

    We investigate the microstructure and linear viscoelasticity of model molecular bottlebrushes (BBs) using rheological and small-angle X-ray and neutron scattering measurements. Our polymers have short atactic polypropylene (aPP) side chains of molecular weight ranging from 119 g/mol to 259 g/mol and narrow molecular weight distribution (M{sub w}/M{sub n} 1.02–1.05). The side chain molecular weights are a small fraction of the entanglement molecular weight of the corresponding linear polymer (M{sub e,aPP}= 7.05 kg/mol), and as such, they are unentangled. The morphology of the aPP BBs is characterized as semiflexible thick chains with small side chain interdigitation. Their dynamic master curves, obtained by time-temperature superposition, reveal two sequential relaxation processes corresponding to the segmental relaxation and the relaxation of the BB backbone. Due to the short length of the side chains, their fast relaxation could not be distinguished from the glassy relaxation. The fractional free volume is an increasing function of the side chain length (N{sub SC}). Therefore, the glassy behavior of these polymers as well as their molecular friction and dynamic properties are influenced by their N{sub SC} values. The apparent flow activation energies are a decreasing function of N{sub SC}, and their values explain the differences in zero-shear viscosity measured at different temperatures.

  16. The effect of Au and Ni doping on the heavy fermion state of the Kondo lattice antiferromagnet CePtZn

    SciTech Connect

    Dhar, S. K.; Aoki, Y.; Suemitsu, B.; Miyazaki, R.; Provino, A.; Manfrinetti, P.

    2014-05-07

    We have probed the effect of doping CePtZn with Au and Ni and also investigated in detail the magnetic behavior of the iso-structural CeAuZn. A magnetic ground state is observed in both CePt{sub 0.9}Au{sub 0.1}Zn and CePt{sub 0.9}Ni{sub 0.1}Zn with T{sub N}?=?2.1 and 1.1?K and the coefficient of the linear term of electronic heat capacity ??=?0.34 and 0.9?J/mol K{sup 2}, respectively. The corresponding values for CePtZn are 1.7?K and 0.6?J/mol K{sup 2}. The altered values of T{sub N} and ? show that the electronic correlations in CePtZn are affected by doping with Au and Ni. CeAuZn orders magnetically near 1.7?K and its electrical resistivity shows a normal metallic behavior. Together with a ? of 0.022?J/mol K{sup 2} the data indicate a weak 4f-conduction electron hybridization in CeAuZn characteristic of normal trivalent cerium based systems.

  17. Hydrogen isotope trapping in Al-Cu binary alloys

    SciTech Connect

    Chao, Paul; Karnesky, Richard A.

    2016-01-01

    In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol–1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high; for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15×10–7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.

  18. TRANSITION STATE FOR THE GAS-PHASE REACTION OF URANIUM HEXAFLUORIDE WITH WATER

    SciTech Connect

    Garrison, S; James Becnel, J

    2008-03-18

    Density Functional Theory and small-core, relativistic pseudopotentials were used to look for symmetric and asymmetric transitions states of the gas-phase hydrolysis reaction of uranium hexafluoride, UF{sub 6}, with water. At the B3LYP/6-31G(d,p)/SDD level, an asymmetric transition state leading to the formation of a uranium hydroxyl fluoride, U(OH)F{sub 5}, and hydrogen fluoride was found with an energy barrier of +77.3 kJ/mol and an enthalpy of reaction of +63.0 kJ/mol (both including zero-point energy corrections). Addition of diffuse functions to all atoms except uranium led to only minor changes in the structure and relative energies of the reacting complex and transition state. However, a significant change in the product complex structure was found, significantly reducing the enthalpy of reaction to +31.9 kJ/mol. Similar structures and values were found for PBE0 and MP2 calculations with this larger basis set, supporting the B3LYP results. No symmetric transition state leading to the direct formation of uranium oxide tetrafluoride, UOF{sub 4}, was found, indicating that the reaction under ambient conditions likely includes several more steps than the mechanisms commonly mentioned. The transition state presented here appears to be the first published transition state for the important gas-phase reaction of UF{sub 6} with water.

  19. Conceptual Design of a CERMET NTR Fission Core Using Multiphysics Modeling Techniques

    SciTech Connect

    Jonathan A. Webb; Brian J. Gross; William T. Taitano

    2011-08-01

    An initial pre-conceptual CERMET Nuclear Thermal Propulsion reactor system is investigated within this paper. Reactor configurations are investigated where the fuel consists of 60 vol.% UO2 and 40 vol.% W where the UO2 consists of Gd2O3 concentrations of 5 and 10 mol.%.Gd2O3. The fuel configuration consisting of 5 mol.% UO2 was found to have a total mass of 2761 kg and a thrust to weight ratio of 4.10 and required a coolant channel surface area to fueled volume ratio of approximately 15.0 in order to keep the centerline temperature below 3000 K. The configuration consisting of 10 mol.% Gd2O3 required a surface area to volume ratio of approximately 12.2 to cool the reactor to a peak temperature of 3000 K and had a total mass of 3200 kg and a thrust to weight ratio of 3.54. It is not known yet what concentration of Gd2O3 is required to maintain fuel stability at 3000 K; however, both reactors offer the potential for operations at 25,000 lb, and at a specific impulse which may range from 900 to 950 seconds.

  20. Thermodynamic analysis of hydration in human serum heme-albumin

    SciTech Connect

    Baroni, Simona; Pariani, Giorgio; Fanali, Gabriella; Longo, Dario; Ascenzi, Paolo; Aime, Silvio; Fasano, Mauro

    2009-07-31

    Ferric human serum heme-albumin (heme-HSA) shows a peculiar nuclear magnetic relaxation dispersion (NMRD) behavior that allows to investigate structural and functional properties. Here, we report a thermodynamic analysis of NMRD profiles of heme-HSA between 20 and 60 {sup o}C to characterize its hydration. NMRD profiles, all showing two Lorentzian dispersions at 0.3 and 60 MHz, were analyzed in terms of modulation of the zero field splitting tensor for the S = {sup 5}/{sub 2} manifold. Values of correlation times for tensor fluctuation ({tau}{sub v}) and chemical exchange of water molecules ({tau}{sub M}) show the expected temperature dependence, with activation enthalpies of -1.94 and -2.46 {+-} 0.2 kJ mol{sup -1}, respectively. The cluster of water molecules located in the close proximity of the heme is progressively reduced in size by increasing the temperature, with {Delta}H = 68 {+-} 28 kJ mol{sup -1} and {Delta}S = 200 {+-} 80 J mol{sup -1} K{sup -1}. These results highlight the role of the water solvent in heme-HSA structure-function relationships.

  1. Structural investigation of phosphate - bismuth glasses with vanadium

    SciTech Connect

    Stănescu, R.; Vedeanu, N.; Cozar, I. B.; Măgdaş, A.

    2013-11-13

    The xV{sub 2}O{sub 5}(1−dx)[0.5P{sub 2}O{sub 5}⋅0.5Bi{sub 2}O{sub 3}] glass system with 0 ≤ x ≤ 50 mol% is investigated by IR and Raman spectroscopy. Both P{sub 2}O{sub 5} and Bi{sub 2}O{sub 3} oxides are known as network formers, but Bi{sub 2}O{sub 3} is an unconventional one. At low content of vanadium oxide (x ≤ 5 mol%), both IR and Raman spectra are dominated by vibration bands characteristics to structural groups of phosphate and bismuthate lattices. Due to the network modifier role, vanadium oxide acts mainly on the Bi{sub 2}O{sub 3} network allowing the phosphate groups to impose their characteristics absorption bands in spectra. These bands are strongly reduced for x ≥ 20 mol% due to the phosphate network depolymerization and the appearance of new vibrations characteristic to P-O-V, Bi-O-V and V-O-V groups showing the network former role of V{sub 2}O{sub 5}.

  2. Nanoscale Strontium Titanate Photocatalysts for Overall Water Splitting

    SciTech Connect

    Townsend, Troy K.; Browning, Nigel D.; Osterloh, Frank

    2012-08-28

    SrTiO3 (STO) is a large band gap (3.2 eV) semiconductor that catalyzes the overall water splitting reaction under UV light irradiation in the presence of a NiO cocatalyst. As we show here, the reactivity persists in nanoscale particles of the material, although the process is less effective at the nanoscale. To reach these conclusions, Bulk STO, 30 5 nm STO, and 6.5 1 nm STO were synthesized by three different methods, their crystal structures verified with XRD and their morphology observed with HRTEM before and after NiO deposition. In connection with NiO, all samples split water into stoichiometric mixtures of H2 and O2, but the activity is decreasing from 28 ?mol H2 g1 h1 (bulk STO), to 19.4 ?mol H2 g1 h1 (30 nm STO), and 3.0 ?mol H2 g1 h1 (6.5 nm STO). The reasons for this decrease are an increase of the water oxidation overpotential for the smaller particles and reduced light absorption due to a quantum size effect. Overall, these findings establish the first nanoscale titanate photocatalyst for overall water splitting.

  3. Development of high strength hydroxyapatite for bone tissue regeneration using nanobioactive glass composites

    SciTech Connect

    Shrivastava, Pragya; Dalai, Sridhar; Vijayalakshmi, S.; Sudera, Prerna; Sivam, Santosh Param; Sharma, Pratibha

    2013-02-05

    With an increasing demand of biocompatible bone substitutes for the treatment of bone diseases and bone tissue regeneration, bioactive glass composites are being tested to improvise the osteoconductive as well as osteoinductive properties. Nanobioactive glass (nBG) composites, having composition of SiO{sub 2} 70 mol%, CaO 26 mol % and P{sub 2}O{sub 5} 4 mol% were prepared by Freeze drying method using PEG-PPG-PEG co-polymer. Polymer addition improves the mechanical strength and porosity of the scaffold of nBG. Nano Bioactive glass composites upon implantation undergo specific reactions leading to the formation of crystalline hydroxyapatite (HA). This is tested in vitro using Simulated Body Fluid (SBF). This high strength hydroxyapatite (HA) layer acts as osteoconductive in cellular environment, by acting as mineral base of bones, onto which new bone cells proliferate leading to new bone formation. Strength of the nBG composites as well as HA is in the range of cortical and cancellous bone, thus proving significant for bone tissue regeneration substitutes.

  4. New sulfur adsorbents derived from layered double hydroxides: II. DRIFTS study of COS and H2S adsorption

    SciTech Connect

    Toops, Todd J [ORNL; Crocker, Mark [University of Kentucky

    2008-01-01

    H2S and COS adsorption were studied on two calcined layered double hydroxides (LDHs), Mg0.75Al0.25(OH)2(CO3)0.125 and Mg0.65Al0.35(OH)2(CO3)0.175, using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and a chemisorption apparatus. Both demonstrated the ability to irreversibly adsorb H2S, corresponding to uptakes of 1.54 and 1.76 mol/m2 respectively, but Mg0.75Al0.25 had a significantly larger capacity for COS, 1.62 mol/m2 compared to 0.80 mol/m2 for Mg0.65Al0.35. Analysis of the DRIFT spectra suggests the adsorption of H2S proceeds via the substitution of lattice oxygen with sulfur, resulting in the formation of H2O on the surface. COS adsorption is more complicated, although it appears that a similar substitution of lattice oxygen with sulfur occurs. This results in the formation of CO2 and subsequently bicarbonates and carbonates. The formation of hydrogen thiocarbonate is also involved, although this form is generally only observed in the later stages of adsorption and appears to form at the expense of bicarbonate. The Mg0.75Al0.25 LDH retained its ability to adsorb COS in the presence of propene.

  5. A thiocyanate hydrolase of Thiobacillus thioparus. A novel enzyme catalyzing the formation of carbonyl sulfide from thiocyanate

    SciTech Connect

    Katayama, Y.; Narahara, Y.; Inoue, Y.; Amano, F.; Kanagawa, T.; Kuraishi, H. (Faculty of Agriculture, Tokyo University of Agriculture and Technology, (Japan))

    1992-05-05

    A thiocyanate hydrolase that catalyzes the first step in thiocyanate degradation was purified to homogeneity from Thiobacillus thioparus, an obligate chemolithotrophic eubacterium metabolizing thiocyanate to sulfate as an energy source. The thiocyanate hydrolase was purified 52-fold by steps involving ammonium sulfate precipitation, DEAE-Sephacel column chromatography, and hydroxylapatite column chromatography. The enzyme hydrolyzed 1 mol of thiocyanate to form 1 mol of carbonyl sulfide and 1 mol of ammonia as follows: SCN- + 2H2O----COS + NH3 + OH-. This is the first report describing the hydrolysis of thiocyanate to carbonyl sulfide by an enzyme. The enzyme had a molecular mass of 126 kDa and was composed of three different subunits: alpha (19 kDa), beta (23 kDa), and gamma (32 kDa). The enzyme exhibited optimal activities at pH 7.5-8.0 and at temperatures ranging from 30 to 40 degrees C. The Km value for thiocyanate was approximately 11 mM. Immunoblot analysis with polyclonal antibodies against the purified enzyme suggested that it was induced in T. thioparus cells when the cells were grown with thiocyanate.

  6. Inherent room temperature ferromagnetism and dopant dependent Raman studies of PbSe, Pb{sub 1−x}Cu{sub x}Se, and Pb{sub 1−x}Ni{sub x}Se

    SciTech Connect

    Gayner, Chhatrasal; Kar, Kamal K.

    2015-03-14

    Polycrystalline lead selenide (PbSe) doped with copper (Cu) and nickel (Ni) was prepared to understand its magnetic behaviour and Raman activity. The processing conditions, influence of dopants (magnetically active and non-active) and their respective compositions on the magnetic properties and Raman active mode were studied. A surprising/anomalous room temperature ferromagnetism (hysteresis loop) is noticed in bulk diamagnetic PbSe, which is found to be natural or inherent characteristic of material, and depends on the crystallite size, dopant, and developed strain due to dopant/defects. The magnetic susceptibility (−1.71 × 10{sup −4} emu/mol Oe) and saturated magnetic susceptibility (−2.74 × 10{sup −4} emu/mol Oe) are found to be higher than the earlier reported value (diamagnetic: −1.0 × 10{sup −4} emu/mol Oe) in bulk PbSe. With increase of Cu concentration (2% to 10%) in PbSe, the saturated magnetic susceptibility decreases from −1.22 × 10{sup −4} to −0.85 × 10{sup −4} emu/mol Oe. Whereas for Ni dopant, the saturated magnetic susceptibility increases to −2.96 × 10{sup −4} emu/mol Oe at 2% Ni doped PbSe. But it further decreases with dopant concentration. In these doped PbSe, the shifting of longitudinal (LO) phonon mode was also studied by the Raman spectroscopy. The shifting of LO mode is found to be dopant dependent, and the frequency shift of LO mode is associated with the induced strain that created by the dopants and vacancies. This asymmetry in LO phonon mode (peak shift and shape) may be due to the intraband electronic transition of dopants. The variation in magnetic susceptibility and Raman shifts are sensitive to crystallite size, nature of dopant, concentration of dopants, and induced strain due to dopants.

  7. Effect of Antimicrobial Peptide on Dynamics of Phosphocholine Membrane. Role of Cholesterol and Physical State of Bilayer

    DOE PAGES [OSTI]

    Sharma, Veerendra K; Mamontov, Eugene; Anunciado, Divina B; O'Neill, Hugh Michael; Urban, Volker S

    2015-06-24

    Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fallmore » in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence

  8. Effect of Antimicrobial Peptide on Dynamics of Phosphocholine Membrane. Role of Cholesterol and Physical State of Bilayer

    SciTech Connect

    Sharma, Veerendra K; Mamontov, Eugene; Anunciado, Divina B; O'Neill, Hugh Michael; Urban, Volker S

    2015-06-24

    Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fall in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol

  9. Molecular and Dissociative Adsorption of Water on (TiO 2 ) n Clusters, n = 1–4

    DOE PAGES [OSTI]

    Chen, Mingyang; Straatsma, Tjerk P.; Dixon, David A.

    2015-10-20

    In the low energy structures of the (TiO2)n(H2O)m (n ≤ 4, m ≤ 2n) and (TiO2)8(H2O)m (m = 3, 7, 8) clusters were predicted using a global geometry optimization approach, with a number of new lowest energy isomers being found. Water can molecularly or dissociatively adsorb on pure and hydrated TiO2 clusters. Dissociative adsorption is the dominant reaction for the first two H2O adsorption reactions for n = 1, 2, and 4, for the first three H2O adsorption reactions for n = 3, and for the first four H2O adsorption reactions for n = 8. As more H2O’s are addedmore » to the hydrated (TiO2)n cluster, dissociative adsorption becomes less exothermic as all the Ti centers become 4-coordinate. Furthermore two types of bonds can be formed between the molecularly adsorbed water and TiO2 clusters: a Lewis acid–base Ti–O(H2) bond or an O···H hydrogen bond. The coupled cluster CCSD(T) results show that at 0 K the H2O adsorption energy at a 4-coordinate Ti center is ~15 kcal/mol for the Lewis acid–base molecular adsorption and ~7 kcal/mol for the H-bond molecular adsorption, in comparison to that of 8–10 kcal/mol for the dissociative adsorption. The cluster size and geometry independent dehydration reaction energy, ED, for the general reaction 2(-TiOH) → -TiOTi– + H2O at 4-coordinate Ti centers was estimated from the aggregation reaction of nTi(OH)4 to form the monocyclic ring cluster (TiO3H2)n + nH2O. ED is estimated to be -8 kcal/mol, showing that intramolecular and intermolecular dehydration reactions are intrinsically thermodynamically allowed for the hydrated (TiO2)n clusters with all of the Ti centers 4-coordinate, which can be hindered by cluster geometry changes caused by such processes. Finally by bending force constants for the TiOTi and OTiO bonds are determined to be 7.4 and 56.0 kcal/(mol·rad2). Infrared vibrational spectra were calculated using density functional theory, and the new bands appearing upon water adsorption were assigned.« less

  10. Structures and Energetics of (MgCO3 )n Clusters ( n ≤ 16)

    DOE PAGES [OSTI]

    Chen, Mingyang; Jackson, Virgil E.; Felmy, Andrew R.; Dixon, David A.

    2015-03-13

    There is significant interest in the role of carbonate minerals for the storage of CO2 and the role of prenucleation dusters in their formation. Global minima for (MgCO3)n (n ≤ 16) structures were optimized using a tree growth-hybrid genetic algorithm in conjunction with MNDO/MNDO/d semiempirical molecular orbital calculations followed by density functional theory geometry optimizations with the B3LYP functional. The most stable isomers for (MgCO3)n (n < 5) are approximately 2-dimensional. Mg can be bonded to one or two 0 atoms of a CO32-, and the 1-O bonding scheme is more favored as the cluster becomes larger. The average C-Mgmore » coordination number increases as the cluster size increases, and at n = 16, the average C-Mg coordination number was calculated to be 5.2. The normalized dissociation energy to form monomers increases as n increases. At n = 16, the normalized dissociation energy is calculated to be 116.2 kcal/mol, as compared to the bulk value of 153.9 kcal/mol. The adiabatic reaction energies for the recombination reactions of (MgO)nclusters and CO2 to form (MgCO3)n were calculated. The exothermicity of the normalized recombination energy < RE >(CO2) decreases as n increases and converged to the experimental bulk limit rapidly. The normalized recombination energy < RE >(CO2) was calculated to be -52.2 kcal/mol for the monomer and -30.7 kcal/mol for n = 16, as compared to the experimental value of -27.9 kcal/mol for the solid phase reaction. Infrared spectra for the lowest energy isomers were calculated, and absorption bands in the previous experimental infrared studies were assigned with our density functional theory predictions. The 13C, 17O, and 25Mg NMR chemical shifts for the clusters were predicted. We found that the results provide insights into the structural and energetic transitions from nanoclusters of (MgCO3)n to the bulk and the spectroscopic properties of clusters for their experimental identification.« less

  11. Structures and Energetics of (MgCO3 )n Clusters ( n ≤ 16)

    SciTech Connect

    Chen, Mingyang; Jackson, Virgil E.; Felmy, Andrew R.; Dixon, David A.

    2015-03-13

    There is significant interest in the role of carbonate minerals for the storage of CO2 and the role of prenucleation dusters in their formation. Global minima for (MgCO3)n (n ≤ 16) structures were optimized using a tree growth-hybrid genetic algorithm in conjunction with MNDO/MNDO/d semiempirical molecular orbital calculations followed by density functional theory geometry optimizations with the B3LYP functional. The most stable isomers for (MgCO3)n (n < 5) are approximately 2-dimensional. Mg can be bonded to one or two 0 atoms of a CO32-, and the 1-O bonding scheme is more favored as the cluster becomes larger. The average C-Mg coordination number increases as the cluster size increases, and at n = 16, the average C-Mg coordination number was calculated to be 5.2. The normalized dissociation energy to form monomers increases as n increases. At n = 16, the normalized dissociation energy is calculated to be 116.2 kcal/mol, as compared to the bulk value of 153.9 kcal/mol. The adiabatic reaction energies for the recombination reactions of (MgO)nclusters and CO2 to form (MgCO3)n were calculated. The exothermicity of the normalized recombination energy < RE >(CO2) decreases as n increases and converged to the experimental bulk limit rapidly. The normalized recombination energy < RE >(CO2) was calculated to be -52.2 kcal/mol for the monomer and -30.7 kcal/mol for n = 16, as compared to the experimental value of -27.9 kcal/mol for the solid phase reaction. Infrared spectra for the lowest energy isomers were calculated, and absorption bands in the previous experimental infrared studies were assigned with our density functional theory predictions. The 13C, 17O, and 25Mg NMR chemical shifts for the clusters were predicted. We found that the results provide insights into the structural and energetic

  12. Efficient photocatalytic hydrogen generation by silica supported and platinum promoted titanium dioxide

    SciTech Connect

    Joshi, Meenal M.; Labhsetwar, Nitin K.; Parwate, D.V.; Rayalu, Sadhana S.

    2013-09-01

    Graphical abstract: Titanium dioxide was supported on mesoporous silica and promoted with Pt and Ru. The supported photocatalysts show high surface area and better photocatalytic activity in visible light as compared to the benchmark Degussa P25. These photocatalysts were characterized using XRD, BET-SA, and UV-DRS techniques. The surface area of supported photocatalyst was 140.6 m{sup 2}/g which is higher than Degussa P-25. Supported photocatalyst was evaluated for hydrogen evolution via water splitting reaction using ethanol as a sacrificial donor. Hydrogen yield observed is 4791.43 ?mol/h/g of TiO{sub 2} and that for P-25 is 161 ?mol/h/g of TiO{sub 2} under visible light irradiation. The value is 30 times higher than benchmark material Degussa P-25. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. - Highlights: Semiconductor titanium dioxide has been supported on silica gel and promoted with Pt by simple wet impregnation route. This synthesized photocatalyst is showing high surface area of 140.6 m{sup 2}/g with crystallite size in the range of 15.44 ?. This photocatalyst is showing enhanced hydrogen yield of about 4791.43 ?mol/h/g of TiO{sub 2}. This photocatalyst is also found stable up to 24 h without replenishing with sacrificial donor ethanol. The effect of various operating parameters on supported photocatalyst also has been studied. - Abstract: Titanium dioxide was supported on mesoporous silica and promoted with Pt and Ru. The supported photocatalysts show high surface area and better photocatalytic activity in visible light as compared to the benchmark Degussa P25. These photocatalysts were characterized using XRD, BET-SA, and UV-DRS techniques. The surface area of supported photocatalyst was 140.6 m{sup 2}/g which is higher than Degussa P-25. Supported photocatalyst was evaluated for hydrogen evolution via water splitting reaction using ethanol as a sacrificial donor. Hydrogen yield

  13. Effect of Antimicrobial Peptide on Dynamics of Phosphocholine Membrane: Role of Cholesterol and Physical State of Bilayer

    SciTech Connect

    Sharma, Veerendra K [ORNL; Mamontov, Eugene [ORNL; Anunciado, Divina B [ORNL; O'Neill, Hugh Michael [ORNL; Urban, Volker S [ORNL

    2015-01-01

    Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fall in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol

  14. TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER

    SciTech Connect

    Westbrook, M.; Becnel, J.; Garrison, S.

    2010-02-25

    The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction mechanism is

  15. Engineering Ascorbate Peroxidase Activity Into Cytochrome C Peroxidase

    SciTech Connect

    Meharenna, Y.T.; Oertel, P.; Bhaskar, B.; Poulos, T.L.

    2009-05-26

    Cytochrome c peroxidase (CCP) and ascorbate peroxidase (APX) have very similar structures, and yet neither CCP nor APX exhibits each others activities with respect to reducing substrates. APX has a unique substrate binding site near the heme propionates where ascorbate H-bonds with a surface Arg and one heme propionate (Sharp et al. (2003) Nat. Struct. Biol. 10, 303--307). The corresponding region in CCP has a much longer surface loop, and the critical Arg residue that is required for ascorbate binding in APX is Asn in CCP. In order to convert CCP into an APX, the ascorbate-binding loop and critical arginine were engineered into CCP to give the CCP2APX mutant. The mutant crystal structure shows that the engineered site is nearly identical to that found in APX. While wild-type CCP shows no APX activity, CCP2APX catalyzes the peroxidation of ascorbate at a rate of {approx}12 min{sup -1}, indicating that the engineered ascorbate-binding loop can bind ascorbate.

  16. Radiotherapy margin design with particular consideration of high curvature CTVs

    SciTech Connect

    Herschtal, Alan; Kron, Tomas; Fox, Chris [Peter MacCallum Cancer Centre, St. Andrews Place, E. Melbourne, Victoria 3002 (Australia)

    2009-03-15

    In applying 3D conformal radiation therapy to a tumor clinical target volume (CTV), a margin is added around the CTV to account for any sources of error in the application of treatment which may result in misalignment between the CTV and the dose distribution actually delivered. The volume enclosed within the CTV plus the margin is known as the PTV, or planning target volume. The larger the errors are anticipated to be, the wider the margin will need to be to accommodate those errors. Based on the approach of van Herk et al. [''The probability of correct target dosage: Dose-population histograms for deriving treatment margins in radiotherapy,'' Int. J. Radiat. Oncol. Biol., Phys. 47(4), 1121-1135 (2000)] this paper develops the mathematical theory behind the calculation of the margin width required to ensure that the entire CTV receives sufficiently high dose with sufficiently high probability. The margin recipe developed not only considers the magnitude of the errors but also includes a term to adjust for curved CTV surfaces. In doing so, the accuracy of the margin recipe is enhanced yet remains mathematically concise enough to be readily implemented in the clinical setting. The results are particularly relevant for clinical situations in which the uncertainties in treatment are large relative to the size of the CTV.

  17. Going beyond 2D: following membrane diffusion and topography in the IgE-Fc[epsilon]RI system using 3-dimensional tracking microscopy

    SciTech Connect

    Wells, Nathan P; Lessard, Guillaume A; Phipps, Marry E; Goodwin, Peter M; Werner, James H; Lidke, Diane S; Wilson, Bridget S

    2008-01-01

    The ability to follow and observe single molecules as they function in live cells would represent a major milestone for molecular-cellular biology. Here we present a tracking microscope that is able to track quantum dots in 3 dimensions and simultaneously record time-resolved emission statistics from a single dot. This innovative microscopy approach is based on four spatial filters and closed loop feedback to constantly keep a single quantum dot in the focal spot. Using this microscope, we demonstrate the ability to follow quantum dot-labeled IgE antibodies bound to Fc{epsilon}Rl membrane receptors in live RBL-2H3 cells. The results are consistent with prior studies of 2 dimensional membrane diffusion (Andrews et al., Nat. Cell Biol., 10, 955, 2008). In addition, the microscope captures motion in the axial (Z) direction, which permits tracking of diffusing receptors relative the 'hills and valley' of the dynamically changing membrane landscape. Our novel approach is uniquely capable of following single-molecule dynamics on live cells with 3 dimensional spatial resolution.

  18. NHE10, a novel osteoclast-specific member of the Na{sup +}/H{sup +} exchanger family, regulates osteoclast differentiation and survival

    SciTech Connect

    Lee, Seoung Hoon; Kim, Taesoo; Park, Eui-Soon; Yang, Sujeong; Jeong, Daewon; Choi, Yongwon; Rho, Jaerang

    2008-05-02

    Bone homeostasis is tightly regulated by the balanced actions of osteoblasts (OBs) and osteoclasts (OCs). We previously analyzed the gene expression profile of OC differentiation using a cDNA microarray, and identified a novel osteoclastogenic gene candidate, clone OCL-1-E7 [J. Rho, C.R. Altmann, N.D. Socci, L. Merkov, N. Kim, H. So, O. Lee, M. Takami, A.H. Brivanlou, Y. Choi, Gene expression profiling of osteoclast differentiation by combined suppression subtractive hybridization (SSH) and cDNA microarray analysis, DNA Cell Biol. 21 (2002) 541-549]. In this study, we have isolated full-length cDNAs corresponding to this clone from mice and humans to determine the functional roles of this gene in osteoclastogenesis. The full-length cDNA of OCL-1-E7 encodes 12 membrane-spanning domains that are typical of isoforms of the Na{sup +}/H{sup +} exchangers (NHEs), indicating that this clone is a novel member of the NHE family (hereafter referred to as NHE10). Here, we show that NHE10 is highly expressed in OCs in response to receptor activator of nuclear factor-{kappa}B ligand signaling and is required for OC differentiation and survival.

  19. Crystallographic Studies of the Binding of Ligands to theDicarboxylate Site of Complex II, and the Identity of the Ligand in the'Oxaloacetate-Inhibited' State

    SciTech Connect

    Huang, Li-Shar; Shen, John T.; Wang, Andy C.; Berry, Edward A.

    2006-07-01

    Mitochondrial Complex II (succinate:ubiquinoneoxidoreductase) is purified in a partially innactivated state, which canbe activated by removal of tightly bound oxaloacetate (Kearney, E.B. etal. Biochem Biophys Res Commun 49, 1115-1121). We crystallized Complex IIin the presence of oxaloacetate or with the endogenous inhibitor bound.The structure showed a ligand essentially identical to the "malate-likeintermediate" found in Shewanella Flavocytochrome c crystallized withfumarate (Taylor, P., et al. Nat Struct Biol 6, 1108-1112.)Crystallization of Complex II in the presence of excess fumarate alsogave the malate-like intermediate or a mixture of that and fumarate atthe active site. In order to more conveniently monitor the occupationstate of the dicarboxylate site, we are developing a library of UV/Visspectral effects induced by binding different ligands to the site.Treatment with fumarate results in rapid development of the fumaratedifference spectrum and then a very slow conversion into a speciesspectrally similar to the OAA liganded complex. Complex II is known to becapable of oxidizing malate to the enol form of oxaloacetate (Belikova,Y.O., et al. Biochim Biophys Acta 936, 1-9). The observations abovesuggest it may also be capable of interconverting fumarate and malate. Itmay be useful for understanding the mechanism and regulation of theenzyme to identify the malate-like intermediate and its pathway offormation from oxaloacetate or fumarate.

  20. INTEGRATED GENOME-BASED STUDIES OF SHEWANELLA ECOPHYSIOLOGY

    SciTech Connect

    NEALSON, KENNETH H.

    2013-10-15

    three undergraduate researchers in the lab, each working on an aspect of this work, and each involved with an undergraduate honors research project. Publications produced as a result of this funding. 1. Waters, M.S., M.Y. El-Naggar, L. Hsu, C.A. Sturm, A. Luttge, F.E. Udwadia, D.G. Cvitkovitch, S.D. Goodman, and K.H. Nealson. 2009. Simultaneous interferometric measurement of corrosive or demineralizing bacteria and their mineral interfaces. Appl. Environ. Microbiol. 75:1445-1449. 2. Gao, H., Z.K. Yang, S. Barua, S. B. Reed, M.F. Romine, K.H. Nealson, J.K. Fredrickson, J.M. Tiedje, and J. Zhou. 2009. Reduction of nitrate in Shewanella oneidensis depends on atypical NAP and NRF systems with NapB as a preferred electron transport protein from CymA to NapA. The ISME J. 3:966-976. 3. Salas, E.C., W.M. Berelson, D.E. Hammond, A.R. Kampf and K. H. Nealson. 2009. The impact of bacterial strain on the products of dissimilatory iron reduction. Geochim. Cosmochim. Acta. (in press: doi: 10.1016/j.gca.2009.10.039) 4. Salas, E.C., W.M. Berelson, D.E. Hammond, A.R. Kampf, and K. H. Nealson. 2009. The influence of carbon source on the products of dissimilatory iron reduction. Geomicrobiol. J. 26:451-462 [7,18]. 5. Waters, M.S., E.C. Salas, S.D. Goodman, F.E. Udwadia, and K.H. Nealson. 2009. Early detection of oxidized surfaces using Shewanella oneidensis MR-1 as a tool. Biofouling. 25:163-172. 6. Konstantinidis, K., et al. 2009. Comparative systems biology across an evolutionary gradient within the Shewanella genus. Proc. Nat. Acad. Sci. USA 106: 15909-15914. 7. Harris, H.W., M.Y. El-Naggar, O. Bretschger, M.J. Ward, M. F. Romine, A.Y. Obraztsova, and K.H. Nealson. 2010. Electrokinesis is a microbial behavior that requires extracellular electron transport. Proc. Nat. Acad. Sci. 107:326-331 8. Nealson, K.H. 2010. Sediment reactions defy dogma. Nature 463:1033-1034. 9. Salas, E.C., W.M. Berelson, D.E. Hammond, A.R. Kampf, and K.H. Nealson. 2010. The impact of bacterial strain on the

  1. Benchmark Theoretical Study of the π–π Binding Energy in the Benzene Dimer

    SciTech Connect

    Miliordos, Evangelos; Aprà, Edoardo; Xantheas, Sotiris S.

    2014-09-04

    We establish a new estimate for the binding energy between two benzene molecules in the parallel-displaced (PD) conformation by systematically converging (i) the intra- and intermolecular geometry at the minimum, (ii) the expansion of the orbital basis set, and (iii) the level of electron correlation. The calculations were performed at the second-order Møller–Plesset perturbation (MP2) and the coupled cluster including singles, doubles, and a perturbative estimate of triples replacement [CCSD(T)] levels of electronic structure theory. At both levels of theory, by including results corrected for basis set superposition error (BSSE), we have estimated the complete basis set (CBS) limit by employing the family of Dunning’s correlation-consistent polarized valence basis sets. The largest MP2 calculation was performed with the cc-pV6Z basis set (2772 basis functions), whereas the largest CCSD(T) calculation was with the cc-pV5Z basis set (1752 basis functions). The cluster geometries were optimized with basis sets up to quadruple-ζ quality, observing that both its intra- and intermolecular parts have practically converged with the triple-ζ quality sets. The use of converged geometries was found to play an important role for obtaining accurate estimates for the CBS limits. Our results demonstrate that the binding energies with the families of the plain (cc-pVnZ) and augmented (aug-cc-pVnZ) sets converge [within <0.01 kcal/mol for MP2 and <0.15 kcal/mol for CCSD(T)] to the same CBS limit. In addition, the average of the uncorrected and BSSE-corrected binding energies was found to converge to the same CBS limit much faster than either of the two constituents (uncorrected or BSSE-corrected binding energies). Due to the fact that the family of augmented basis sets (especially for the larger sets) causes serious linear dependency problems, the plain basis sets (for which no linear dependencies were found) are deemed as a more efficient and straightforward path for

  2. Calorimetric, spectroscopic and structural investigations of phase polymorphism in [Ru(NH{sub 3}){sub 6}](BF{sub 4}){sub 3}. Part I

    SciTech Connect

    Dolega, Diana; Mikuli, Edward; Inaba, Akira; Gorska, Natalia; Holderna-Natkaniec, Krystyna; Nitek, Wojciech

    2013-01-15

    Four crystalline phases of the coordination compound [Ru(NH{sub 3}){sub 6}](BF{sub 4}){sub 3} are identified by adiabatic calorimetry. Three phase transitions, one at T{sub C3}(IV{yields}III)=30.7 K, the second at T{sub C2}(III{yields}II)=91.7 K (both accompanied by comparable entropy changes 3.0 and 3.1 J K{sup -1} mol{sup -1}, respectively) and the third at T{sub C1}(II{yields}I)=241.6 K (accompanied by an entropy change of 8.1 J K{sup -1} mol{sup -1}) were discovered. X-ray single crystal diffraction (at 293 K) demonstrates that phase I is a highly dynamic disordered cubic phase (Fm3{sup Macron }m, No. 225) with two types of BF{sub 4}{sup -} anions differing in a degree of disorder. In phase II (at 170 K) the structure remains cubic (Ia3{sup Macron }, No. 206), with two different types of cations and four different types of anions. Splitting of certain IR bands connected with NH{sub 3} ligands at the observed phase transitions suggests a lowering of the symmetry of the [Ru(NH{sub 3}){sub 6}]{sup 3+} complex cation. Both NH{sub 3} ligands and BF{sub 4}{sup -} anions perform fast reorientations ({tau}{sub R} Almost-Equal-To 10{sup -12} s), which are significantly slowed down below the phase transition at T{sub C3}. {sup 1}H NMR studies led to estimate the values of the activation energy of NH{sub 3} ligands reorientation in the phases II and I as equal to {approx}8 kJ mol{sup -1}. In phase I the whole hexammineruthenium(III) cations reorientation as a tumbling process can be noticed. The activation energy value of this motion is {approx}24 kJ mol{sup -1}. {sup 19}F NMR studies give the values of the activation energy of BF{sub 4}{sup -} anions reorientation as {approx}6 kJ mol{sup -1}. Above the phase transition temperature half of BF{sub 4}{sup -} anions perform a tumbling motion with E{sub a} Almost-Equal-To 8 kJ mol{sup -1}. - Graphical abstract: A series of complementary methods, such as Adiabatic Calorimetry, Differential Scanning Calorimetry, Fourier

  3. Luminescent nanocrystals in the rare-earth niobatezirconia system formed via hydrothermal method

    SciTech Connect

    Hirano, Masanori Dozono, Hayato

    2013-08-15

    Luminescent nanocrystals based on the rare-earth niobates (Ln{sub 3}NbO{sub 7}, Ln=Y, Eu) and zirconia (ZrO{sub 2}) that were composed of 50 mol% Ln{sub 3}NbO{sub 7} and 50 mol% ZrO{sub 2}, were hydrothermally formed as cubic phase under weakly basic conditions at 240 C. The lattice parameter of the as-prepared nanoparticles corresponding to the composition of Y{sub 3?x}Eu{sub x}NbO{sub 7}4ZrO{sub 2} that was estimated as a single phase of cubic gradually increased as the content of europium x increased. The existence of small absorbance peaks at 395 and 466 nm corresponding to the Eu{sup 3+7}F{sub 0}?{sup 5}L{sub 6}, and {sup 7}F{sub 0}?{sup 5}D{sub 2} excitation transition, respectively, was clearly observed in the diffuse reflectance spectra of the as-prepared samples containing europium. The optical band gap of the as-prepared samples was in the range from 3.5 to 3.7 eV. The photoluminescence spectra of the as-prepared nanocrystals containing europium showed orange and red luminescences with main peaks at 590 and 610 nm, corresponding to {sup 5}D{sub 0}?{sup 7}F{sub 1} and {sup 5}D{sub 0}?{sup 7}F{sub 2} transitions of Eu{sup 3+}, respectively, under excitation at 395 nm Xe lamp. The emission intensity corresponding to {sup 5}D{sub 0}?{sup 7}F{sub 2} transition increased as heat-treatment temperature rose from 800 to 1200 C. - Graphical abstract: This graphical abstract shows the excitation and emission spectra and a transmission electron microscopy image of nanocrystals (with composition based on the rare-earth niobates (Ln{sub 3}NbO{sub 7}, Ln=Y, Eu) and zirconia (ZrO{sub 2}) that were composed of 50 mol% Ln{sub 3}NbO{sub 7} and 50 mol% ZrO{sub 2}) formed via hydrothermal route. Display Omitted - Highlights: Nanocrystals composed of 50 mol% Y{sub 3?x}Eu{sub x}NbO{sub 7} and 50 mol% ZrO{sub 2} was directly formed. The nanocrystals were hydrothermally formed under weakly basic conditions at 240 C. The Y{sub 3}NbO{sub 7} showed an UV-blue and broad

  4. Relativistic effects for the reaction Sg + 6 CO → Sg(CO){sub 6}: Prediction of the mean bond energy, atomization energy, and existence of the first organometallic transactinide superheavy hexacarbonyl Sg(CO){sub 6}

    SciTech Connect

    Malli, Gulzari L.

    2015-02-14

    Our ab initio all-electron fully relativistic Dirac–Fock (DF) and nonrelativistic (NR) Hartree-Fock calculations predict the DF relativistic and NR energies for the reaction: Sg + 6 CO → Sg(CO){sub 6} as −7.39 and −6.96 eV, respectively, i.e., our calculated ground state total DF relativistic and NR energies for the reaction product Sg(CO){sub 6} are lower by 7.39 and 6.96 eV than the total DF and NR ground state energies of the reactants, viz., one Sg atom plus six CO molecules, respectively. Our calculated DF relativistic and NR atomization energies (Ae) are 65.23 and 64.82 eV, respectively, and so the contribution of relativistic effects to the Ae of ∼0.40 eV is marginal. The Sg–C and C–O optimized bond distances for the octahedral geometry as calculated in our DF (NR) calculations are 2.151 (2.318 Å) and 1.119 (1.114 Å), respectively. The BSSE correction calculated using the DIRAC code ∼14 kcal/mol. The relativistic DF and NR mean energies predicted by us are 118.8 and 111.9 kJ/mol, respectively, and the contribution of ∼7 kJ/mol due to relativistic effects to the mean energy of Sg(CO){sub 6} is negligible. Ours are the first calculations of the relativistic effects for the atomization energy, mean bond energy, and energy of the reaction for possible formation of Sg(CO){sub 6}, and both our relativistic DF and the NR treatments clearly predict for the first time the existence of hexacarbonyl of the transactinide superheavy element seaborgium Sg. In conclusion, relativistic effects are not significant for Sg(CO){sub 6}.

  5. Development of palladium composite membranes for hydrogen separation

    SciTech Connect

    Paglieri, S. N. (Stephen N.); Birdsell, S. A. (Stephen A.); Snow, R. C. (Ronny C.); Smith, F. M. (Frank M.); Tewell, C. R. (Craig R.)

    2004-01-01

    Two types of palladium composite membrane were investigated for hydrogen separation. A palladium alloy membrane was prepared by electroless plating a layer of palladium ({approx}20 {micro}m) and then copper onto a commercially available porous (nominal 0.2 {micro}m pores) {alpha}-alumina substrate. The resulting multilayer metal film was annealed at 355 C for several days to promote metallic interdiffusion and alloy formation. During the heat treatment, a maximum hydrogen flux of 0.15 mol (STP)/m{sup 2} {center_dot} s was observed at 355 C and a pressure drop ({Delta}P) across the membrane of 6.8 atm. The H{sub 2}/Ar ideal separation factor was 68 at these conditions, however, the separation factor decreased upon thermal cycling. The other type of membrane fabricated was a palladium coated vanadium-copper alloy foil where the main advantage is the reduction in palladium film coating thickness to 100 nm per side. New methods are being developed for welding the thin foil into modules for testing. The hydrogen flux through a pinhole-free, 75 {micro}m thick Pd/VCu{sub 1.1}/Pd (atomic %) composite membrane was 0.66 mol (STP)/m{sup 2} {center_dot} at 350 C and {Delta}P = 3.5 atm compared to 0.44 mol (STP)/m{sup 2} {center_dot} s for a 71 {micro}m thick Pd/VCu{sub 10}/Pd membrane. Vanadium alloy composition was checked using Auger electron spectroscopy (AES).

  6. Manganese-Based Molecular Electrocatalysts for Oxidation of Hydrogen

    SciTech Connect

    Hulley, Elliott; Kumar, Neeraj; Raugei, Simone; Bullock, R. Morris

    2015-10-05

    Oxidation of H2 (1 atm) is catalyzed by the manganese electrocatalysts [(P2N2)MnI(CO)(bppm)]+ and [(PNP)MnI(CO)(bppm)]+ (P2N2= 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane; PNP = (Ph2PCH2)2NMe); bppm = (PArF2)2CH2, and ArF = 3,5-(CF3)2C6H3). In fluorobenzene solvent using 2,6-lutidine as the exogeneous base, the turnover frequency for [(P2N2)MnI(CO)(bppm)]+ is 3.5 s-1 with an estimated overpotential of 590 mV. For [(PNP)MnI(CO)(bppm)], in fluorobenzene solvent using N-methylpyrrolidine as the exogeneous base, the turnover frequency is 1.4 s-1 with an estimated overpotential of 700 mV. Density functional theory calculations suggest that the slow step in the catalytic cycle is proton transfer from the oxidized 17-electron manganese hydride, e.g., [(P2N2)MnIIH(CO)(bppm)]+ to the pendant amine. The computed activation barrier for intramolecular proton transfer from the metal to the pendant amine is 20.4 kcal/mol in [(P2N2)MnIIH(CO)(bppm)]+ and 21.3 kcal/mol in [(PNP)MnI(CO)(bppm)]. The high barrier appears to result from both the unfavorability of metal-to-nitrogen proton transfer (thermodynamically uphill by 6.6 pKa units, 9 kcal/mol), as well as the relatively long manganese-nitrogen separation in the MnIIH complexes.

  7. Detection of Specific Solvent Rearrangement Regions of an Enzyme: NMR and ITC Studies with Aminoglycoside Phosphotransferase(3??)-IIIa

    SciTech Connect

    Ozen, C.; Norris, Adrianne; Land, Miriam L; Tjioe, Elina; Serpersu, Engin H

    2008-01-01

    This work describes differential effects of solvent in complexes of the aminoglycoside phosphotransferase(3¢)-IIIa (APH) with different aminoglycosides and the detection of change in solvent structure at specific sites away from substrates. Binding of kanamycins to APH occurs with a larger negative ¢H in H2O relative to D2O (¢¢H(H2O-D2O) < 0), while the reverse is true for neomycins. Unusually large negative ¢Cp values were observed for binding of aminoglycosides to APH. ¢Cp for the APHneomycin complex was -1.6 kcalâmol-1âdeg-1. A break at 30 C was observed in the APH-kanamycin complex yielding ¢Cp values of -0.7 kcalâmol-1âdeg-1 and -3.8 kcalâmol-1âdeg-1 below and above 30 C, respectively. Neither the change in accessible surface area (¢ASA) nor contributions from heats of ionization were sufficient to explain the large negative ¢Cp values. Most significantly, 15N-1H HSQC experiments showed that temperature-dependent shifts of the backbone amide protons of Leu 88, Ser 91, Cys 98, and Leu143 revealed a break at 30 C only in the APH-kanamycin complex in spectra collected between 21 C and 38 C. These amino acids represent solVent reorganization sites that experience a change in solvent structure in their immediate environment as structurally different ligands bind to the enzyme. These residues were away from the substrate binding site and distributed in three hydrophobic patches in APH. Overall, our results show that a large number of factors affect ¢Cp and binding of structurally different ligand groups cause different solvent structure in the active site as well as differentially affecting specific sites away from the ligand binding site.

  8. Transjugular Insertion of Bare-Metal Biliary Stent for the Treatment of Distal Malignant Obstructive Jaundice Complicated by Coagulopathy

    SciTech Connect

    Tsauo Jiaywei Li Xiao Li Hongcui Wei Bo Luo Xuefeng Zhang Chunle Tang Chengwei; Wang Weiping

    2013-04-15

    This study was designed to investigate retrospectively the feasibility of transjugular insertion of biliary stent (TIBS) for the treatment of distal malignant obstructive jaundice complicated by coagulopathy. Between April 2005 and May 2010, six patients with distal malignant obstructive jaundice associated with coagulopathy that was unable to be corrected underwent TIBS at our institution for the palliation of jaundice. Patients' medical record and imaging results were reviewed to obtain information about demographics, procedure details, complications, and clinical outcomes. The intrahepatic biliary tract was successfully accessed in all six patients via transjugular approach. The procedure was technically successfully in five of six patients, with a bare-metal stent implanted after traversing the biliary strictures. One procedure failed, because the guidewire could not traverse the biliary occlusion. One week after TIBS, the mean serum bilirubin in the five successful cases had decreased from 313 {mu}mol/L (range 203.4-369.3) to 146.2 {mu}mol/L (range 95.8-223.3) and had further decreased to 103.6 {mu}mol/L (range 29.5-240.9) at 1 month after the procedure. No bleeding, sepsis, or other major complications were observed after the procedure. The mean survival of these five patients was 4.5 months (range 1.9-5.8). On imaging follow-up, there was no evidence of stent stenosis or migration, with 100 % primary patency. When the risks of hemorrhage from percutaneous transhepatic cholangiodrainage are high, TIBS may be an effective alternative for the treatment of distal malignant obstructive jaundice.

  9. Impact of solvent for individual steps of phenol hydrodeoxygenation with Pd/C and HZSM-5 as catalysts

    SciTech Connect

    He, Jiayue; Zhao, Chen; Lercher, Johannes A.

    2014-01-01

    Impacts of water, methanol, and hexadecane solvents on the individual steps of phenol hydrodeoxygenation are investigated over Pd/C and HZSM-5 catalyst components at 473 Kin presence of H-2. Hydrodeoxygenation of phenol to cyclohexane includes four individual steps of phenol hydrogenation to cyclohexanone on Pd/C, cyclohexanone hydrogenation to cyclohexanol on Pd/C, cyclohexanol dehydration to cyclohexene on HZSM-5, and cyclohexene hydrogenation to cyclohexane on Pd/C. Individual phenol and cyclohexanone hydrogenation rates are much lower in methanol and hexadecane than in water, while rates of cyclohexanol dehydration and cyclohexene hydrogenation are similar in three solvents. The slow rate in methanol is due to the strong solvation of reactants and the adsorption of methanol on Pd, as well as to the reaction between methanol and the cyclohexanone intermediate. The low solubility of phenol and strong interaction of hexadecane with Pd lead to the slow rate in hexadecane. The apparent activation energies for hydrogenation follow the order E-a phenol > E-a cyclonexanone > E-a cyclohexene, and the sequences of individual reaction rates are reverse in three solvents. The dehydration rates (1.1-1.8 x 10(3) mol mol(BAS)(-1) h(-1))and apparent activation energies (115-124 kJ mol(-1)) are comparable in three solvents. In situ liquid-phase IR spectroscopy shows the rates consistent with kinetics derived from chromatographic evidence in the aqueous phase and verifies that hydrogenation of phenol and cyclohexanone follows reaction orders of 1.0 and 0.55 over Pd/C, respectively. Conversion of cyclohexanol with HZSM-5 shows first-order dependence in approaching the dehydration-hydration equilibrium in the aqueous phase.

  10. Mechanisms of nickel sorption by a bacteriogenic birnessite

    SciTech Connect

    Pena, J.; Kwon, K.D.; Refson, K.; Bargar, J.R.; Sposito, G.

    2010-04-01

    A synergistic experimental-computational approach was used to study the molecular-scale mechanisms of Ni sorption at varying loadings and at pH 6-8 on the biogenic hexagonal birnessite produced by Pseudomonas putida GB-1. We found that Ni is scavenged effectively by bacterial biomass-birnessite assemblages. At surface excess values below 0.18 mol Ni kg{sup -1} sorbent (0.13 mol Ni mol{sup -1} Mn), the biomass component of the sorbent did not interfere with Ni sorption on mineral sites. Extended X-ray absorption fine structure (EXAFS) spectra showed two dominant coordination environments: Ni bound as a triple-corner-sharing (Ni-TCS) complex at vacancy sites and Ni incorporated (Ni-inc) into the MnO{sub 2} sheet, with the latter form of Ni favored at high sorptive concentrations and decreased proton activity. In parallel to our spectral analysis, first-principles geometry optimizations based on density functional theory (DFT) were performed to investigate the structure of Ni surface complexes at vacancy sites. Excellent agreement was achieved between EXAFS- and DFT-derived structural parameters for Ni-TCS and Ni-inc. Reaction-path calculations revealed a pH-dependent energy barrier associated with the transition from Ni-TCS to Ni-inc. Our results are consistent with the rate-limited incorporation of Ni at vacancy sites in our sorption samples, but near-equilibrium state of Ni in birnessite phases found in nodule samples. This study thus provides direct and quantitative evidence of the factors governing the occurrence of Ni adsorption versus Ni incorporation in biogenic hexagonal birnessite, a key mineral in the terrestrial manganese cycle.

  11. Thermodynamic studies of CaLaFe??O??(s)

    SciTech Connect

    Rakshit, S.K.; Parida, S.C.; Lilova, Kristina; Navrotsky, Alexandra

    2013-05-01

    Thermodynamic studies on CaLaFe??O??(s) were carried out using Knudsen effusion mass spectrometry and calorimetry, viz. differential scanning calorimetry and high temperature oxide melt solution calorimetry. Standard molar Gibbs free energy of formation (?{sub f}G?{sub m}), enthalpy of formation and heat capacity (C?{sub ?,m}) of the compound were calculated as a function of temperature for the first time. C?{sub ?,m}(CaLaFe??O??) was determined and used for second law analysis, from which enthalpy and entropy of formation of the compound were calculated and the respective values are: ?{sub f}H?{sub m}(298.15 K)/kJ mol?=-6057(8) and S?{sub m}(298.15 K)/J K? mol?=427(5). ?{sub f}H?{sub m}(298.15 K)/kJ mol?: -6055(6) was also calculated using oxide melt solution calorimetry, which is in close agreement with the second law value. A heat capacity anomaly was also observed at T=684 K. A table of thermodynamic data from 298.15 K to 1000 K for CaLaFe??O??(s) was also constructed to represent an optimized set of data. - graphical abstract: Variation of standard molar heat capacities of CaLaF??O??(s) and MFe??O??(s) (M=Sr, Ba and Pb) as a function of temperature. Highlights: Thermodynamic studies on CaLaFe??O??(s) were performed using KEQMS and solution calorimetry. It was synthesized using gel combustion route and characterized by XRD technique. The compound is magnetic in nature and shows a heat capacity anomaly at 684 K. Thermodynamic table was constructed from 298 K to 1000 K.

  12. Kinetic studies of the [NpO? (CO?)?]?? ion at alkaline conditions using C NMR

    SciTech Connect

    Panasci, Adele F.; Harley, Stephen J.; Zavarin, Mavrik; Casey, William H.

    2014-04-21

    Carbonate ligand-exchange rates on the [NpO? (CO?)?]?? ion were determined using a saturation-transfer C nuclear magnetic resonance (NMR) pulse sequence in the pH range of 8.1 ? pH ? 10.5. Over the pH range 9.3 ? pH ? 10.5, which compares most directly with previous work of Stout et al.,1 we find an average rate, activation energy, enthalpy, and entropy of k298ex = 40.6(4.3) s?, Ea =45.1(3.8) kJ mol?, ?H = 42.6(3.8) kJ mol?, and ?S = -72(13) J mol? K?, respectively. These activation parameters are similar to the Stout et al. results at pH 9.4. However, their room-temperature rate at pH 9.4, k298ex = 143(1.0) s?, is ~3 times faster than what we experimentally determined at pH 9.3: k298ex = 45.4(5.3) s?. Our rates for [NpO? (CO?)?]?? are also faster by a factor of ~3 relative to the isoelectronic [UO?(CO?)?]?? as reported by Brucher et al.2 of k298ex = 13(3) s?. Consistent with results for the [UO?(CO?)?]?? ion, we find evidence for a proton-enhanced pathway for carbonate exchange for the [NpO?(CO?)?]?? ion at pH < 9.0.

  13. Microbial Metabolism Shifts Towards an Adverse Profile with Supplementary Iron in the TIM-2 In vitro Model of the Human Colon

    DOE PAGES [OSTI]

    Kortman, Guus A. M.; Dutilh, Bas E.; Maathuis, Annet J. H.; Engelke, Udo F.; Boekhorst, Jos; Keegan, Kevin P.; Nielsen, Fiona G. G.; Betley, Jason; Weir, Jacqueline C.; Kingsbury, Zoya; et al

    2016-01-06

    Oral iron administration in African children can increase the risk for infections. However, it remains unclear to what extent supplementary iron affects the intestinal microbiome. We here explored the impact of iron preparations on microbial growth and metabolism in the well-controlled TNO's in vitro model of the large intestine (TIM-2). The model was inoculated with a human microbiota, without supplementary iron, or with 50 or 250 μmol/L ferrous sulfate, 50 or 250 μmol/L ferric citrate, or 50 μmol/L hemin. High resolution responses of the microbiota were examined by 16S rDNA pyrosequencing, microarray analysis, and metagenomic sequencing. The metabolome was assessedmore » by fatty acid quantification, gas chromatography-mass spectrometry (GC-MS), and 1H-NMR spectroscopy. Cultured intestinal epithelial Caco-2 cells were used to assess fecal water toxicity. Microbiome analysis showed, among others, that supplementary iron induced decreased levels of Bifidobacteriaceae and Lactobacillaceae, while it caused higher levels of Roseburia and Prevotella. Metagenomic analyses showed an enrichment of microbial motility-chemotaxis systems, while the metabolome markedly changed from a saccharolytic to a proteolytic profile in response to iron. Branched chain fatty acids and ammonia levels increased significantly, in particular with ferrous sulfate. Importantly, the metabolite-containing effluent from iron-rich conditions showed increased cytotoxicity to Caco-2 cells. In conclusion, our explorations indicate that in the absence of host influences, iron induces a more hostile environment characterized by a reduction of microbes that are generally beneficial, and increased levels of bacterial metabolites that can impair the barrier function of a cultured intestinal epithelial monolayer.« less

  14. Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers

    DOE PAGES [OSTI]

    Coffin, Robert C.; MacNeill, Christopher M.; Peterson, Eric D.; Ward, Jeremy W.; Owen, Jack W.; McLellan, Claire A.; Smith, Gregory M.; Noftle, Ronald E.; Jurchescu, Oana D.; Carroll, David L.

    2011-01-01

    Tmore » hrough manipulation of the solubilizing side chains, we were able to dramatically improve the molecular weight ( M w ) of 4,8-dialkoxybenzo[1,2- b :4,5- b ′ ]dithiophene (BDT)/2,1,3-benzothiadiazole (BT) copolymers. When dodecyl side chains ( P1 ) are employed at the 4- and 8-positions of the BDT unit, we obtain a chloroform-soluble copolymer fraction with M w of 6.3 kg/mol. Surprisingly, by moving to the commonly employed 2-ethylhexyl branch ( P2 ), M w decreases to 3.4 kg/mol.his is despite numerous reports that this side chain increases solubility and M w . By moving the ethyl branch in one position relative to the polymer backbone (1-ethylhexyl, P3 ), M w is dramatically increased to 68.8 kg/mol. As a result of this M w increase, the shape of the absorption profile is dramatically altered, with λ max = 637 nm compared with 598 nm for P1 and 579 nm for P2 .he hole mobility as determined by thin film transistor (TFT) measurements is improved from ~ 1 × 10 − 6  cm 2 /Vs for P1 and P2 to 7 × 10 − 4  cm 2 /Vs for P3 , while solar cell power conversion efficiency in increased to 2.91 % for P3 relative to 0.31 % and 0.19 % for P1 and P2 , respectively.« less

  15. Monte Carlo simulations of coupled diffusion and surface reactions during the aqueous corrosion of borosilicate glasses

    DOE PAGES [OSTI]

    Kerisit, Sebastien; Pierce, Eric M.; Ryan, Joseph V.

    2014-09-19

    Borosilicate nuclear waste glasses develop complex altered layers as a result of coupled processes such as hydrolysis of network species, condensation of Si species, and diffusion. However, diffusion has often been overlooked in Monte Carlo models of the aqueous corrosion of borosilicate glasses. Therefore, in this paper three different models for dissolved Si diffusion in the altered layer were implemented in a Monte Carlo model and evaluated for glasses in the compositional range (75 - x) mol% SiO2 (12.5 + x/2) mol% B2O3 and (12.5 + x/2) mol% Na2O, where 0 ≤ x ≤ 20%, and corroded in static conditionsmore » at a surface-area-to-volume ratio of 1000 m-1. The three models considered instantaneous homogenization (M1), linear concentration gradients (M2), and concentration profiles determined by solving Fick's 2nd law using a finite difference method (M3). Model M3 revealed that concentration profiles in the altered layer are not linear and show changes in shape and magnitude as corrosion progresses, unlike those assumed in model M2. Furthermore, model M3 showed that, for borosilicate glasses with a high forward dissolution rate compared to the diffusion rate, the gradual polymerization and densification of the altered layer is significantly delayed compared to models M1 and M2. Finally, models M1 and M2 were found to be appropriate models only for glasses with high release rates such as simple borosilicate glasses with low ZrO2 content.« less

  16. Photo-oxidation of gaseous ethanol on photocatalyst prepared by acid leaching of titanium oxide/hydroxyapatite composite

    SciTech Connect

    Ono, Y.; Rachi, T.; Yokouchi, M.; Kamimoto, Y.; Nakajima, A.; Okada, K.

    2013-06-01

    Highlights: ► Photocatalyst powder was prepared by acid leaching of TiO{sub 2}/apatite composite. ► The photocatalytic activity was evaluated from in situ FT-IR study using ethanol. ► Apatite in the composite had positive effect for the photo-oxidation of ethanol. ► The enhanced oxidation rate was explained by the difference in deactivation rate. - Abstract: Highly active photocatalysts were synthesized by leaching of heat-treated titanium dioxide (TiO{sub 2})/hydroxyapatite (HAp) powder with hydrochloric acid at 0.25, 0.50, 0.75 mol/l, and their photocatalytic activities were evaluated from in situ Fourier transform infrared (FT-IR) study of photo-oxidation of gaseous ethanol. By changing the acid concentration, the TiO{sub 2}/HAp composite had different atomic ratios of Ca/Ti (0.0–2.8) and P/Ti (0.3–2.1). It was found that phosphate group remained on the surface of TiO{sub 2} particle even in the sample treated with concentrated acid (0.75 mol/l). These acid-treated samples showed higher rates for ethanol photo-oxidation than the commercial TiO{sub 2} powder, Degussa P25. The highest rate was obtained in the TiO{sub 2}/HAp composite treated with the dilute (0.25 mol/l) acid in spite of its low content of TiO{sub 2} photocatalyst. This enhanced photocatalytic activity was attributed to the result that the deactivation with repeated injections of ethanol gas was suppressed in the TiO{sub 2}/HAp composites compared with the TiO{sub 2} powders.

  17. {sup 55}Co separation from proton irradiated metallic nickel

    SciTech Connect

    Valdovinos, H. F. Graves, S. Barnhart, T. Nickles, R. J.

    2014-11-07

    {sup 55}Co with > 97% radionuclidic purity 24 hours after end of bombardment (EoB) was produced from the {sup 58}Ni(p,α) reaction using proton irradiations of 16 MeV on natural nickel. Two-hour irradiations with 25 μA on a 254 μm thick nickel foil generate 0.18 ± 0.01 GBq (n = 3) 24 hours after EoB. The separation of cobalt from the target material and other metallic contaminants present at trace levels is accomplished in HCl medium by two rounds of anion exchange chromatography (AG1-X8) using an automated module driven by a peristaltic pump. 80 ± 5 % (n = 3) of the activity generated at EoB is ready for labeling in 0.1 M HCl one hour after the start of separation. Using 99.999% pure Ni, the reactivity (decay corrected to EoB) with the bifunctional chelator (BFC) DOTA was 8.5 GBq/μmol; enough for radiolabeling BFC conjugated biomolecules at a nmol scale with > 90% yield. Using 99.9% pure Ni the reactivity with DOTA and NOTA was 0.19 +/− 0.09 GBq/μmol and 2.9 +/− 1.7 GBq/μmol (n = 2), respectively. Both cobalt complexes showed 100% in vitro stability in PBS and mouse serum over 41 hours at room temperature. MicroPET images of a miniature Derenzo phantom show excellent resolution where rods of 1.5 mm were separated by two times their diameter.

  18. Controlling Interfacial Dynamics: Covalent Bonding versus Physical Adsorption in Polymer Nanocomposites

    DOE PAGES [OSTI]

    Holt, Adam P.; Bocharova, Vera; Cheng, Shiwang; Kisliuk, Alexander M.; White, B. Tyler; Saito, Tomonori; Uhrig, David; Mahalik, J. P.; Kumar, Rajeev; Imel, Adam E.; et al

    2016-06-23

    It is generally believed that the strength of the polymer nanoparticle interaction controls the modification of near-interface segmental mobility in polymer nanocomposites (PNCs). However, little is known about the effect of covalent bonding on the segmental dynamics and glass transition of matrix-free polymer-grafted nanoparticles (PGNs), especially when compared to PNCs. In this article, we directly compare the static and dynamic properties of poly(2-vinylpyridine)/silica-based nanocomposites with polymer chains either physically adsorbed (PNCs) or covalently bonded (PGNs) to identical silica nanoparticles (RNP = 12.5 nm) for three different molecular weight (MW) systems. Interestingly, when the MW of the matrix is as lowmore » as 6 kg/mol (RNP/Rg = 5.4) or as high as 140 kg/mol (RNP/Rg= 1.13), both small-angle X-ray scattering and broadband dielectric spectroscopy show similar static and dynamic properties for PNCs and PGNs. However, for the intermediate MW of 18 kg/mol (RNP/Rg = 3.16), the difference between physical adsorption and covalent bonding can be clearly identified in the static and dynamic properties of the interfacial layer. We ascribe the differences in the interfacial properties of PNCs and PGNs to changes in chain stretching, as quantified by self-consistent field theory calculations. These results demonstrate that the dynamic suppression at the interface is affected by the chain stretching; that is, it depends on the anisotropy of the segmental conformations, more so than the strength of the interaction, which suggests that the interfacial dynamics can be effectively tuned by the degree of stretching a parameter accessible from the MW or grafting density.« less

  19. Photocatalytic pure water splitting activities for ZnGa{sub 2}O{sub 4} synthesized by various methods

    SciTech Connect

    Zeng, Chunmei; Hu, Tao; Hou, Nianjun; Liu, Siyao; Gao, Wenliang; Cong, Rihong; Yang, Tao

    2015-01-15

    Highlights: High temperature solid state reaction, hydrothermal, sol-gel methods were applied. All ZnGa{sub 2}O{sub 4} samples show UV-light catalytic activities on pure water splitting. Bulk ZnGa{sub 2}O{sub 4} has a good photocatalytic activity per specific surface area. Sol-gel is a superior method to prepare nanosized ZnGa{sub 2}O{sub 4} with a high activity. The AQY for SG-ZnGa{sub 2}O{sub 4} is 2.6% for pure water splitting under 313 nm irradiation. - Abstract: We studied and compared the photocatalytic water splitting performances for ZnGa{sub 2}O{sub 4} prepared by high temperature solid state reaction (HTSSR), hydrothermal (HY) and sol-gel (SG) methods. HTSSR-ZnGa{sub 2}O{sub 4} has a relative large photocatalytic activity per surface area (1.6 ?mol/h/m{sup 2}) in pure water by UV irradiation due to its high crystallinity. The HY- and SG-samples both have small particle sizes (20?30 nm) and therefore high surface area (20 and 29 m{sup 2}/g, respectively), which leads to superior photocatalytic H{sub 2} evolution rates per unit mass (11.5 and 28.5 ?mol/h/g). The apparent quantum yield of SG-ZnGa{sub 2}O{sub 4} for pure water splitting under 313 nm irradiation is 2.6%. The existence of substantial surface defects is the major problem for HY- and SG-ZnGa{sub 2}O{sub 4}. Consequently, the usage of sacrificial agents could greatly enhance the activities and indeed the H{sub 2} evolution rates in 20 Vol. % methanol aqueous solution increase to 100 and 142 ?mol/h/g for HY- and SG-ZnGa{sub 2}O{sub 4}, respectively.

  20. Hydrolysis of COS and CS{sub 2} over alumina catalysts at lower temperature

    SciTech Connect

    Shangguan Ju; Li Chunhu; Guo Hanxian [Taiyuan Univ. of Technology, Shanxi (China). Research Inst. of Chemical Engineering for Coal

    1997-12-31

    Carbonyl sulfide (COS) and carbon disulfide (CS{sub 2}) widely exist in chemical processing gases from natural gas, coal, Claus tail gas, and petroleum. Those sulfur compound are a major factor of deactivation of synthesis catalysts. Since it is difficult to remove COS and CS{sub 2} completely by the conventional desulfurization, a hydrolysis process has been developed in recent years. The activity of COS and CS{sub 2} hydrolysis was measured in a fixed bed reactor and the surface basicity was studied by CO{sub 2}-TPD. The results showed that the apparent reaction activation energies of COS over three catalysts are 57.80, 52.50 and 44.71 kJ/mol at lower temperature, and those of CS{sub 2}, 55.53, 38.70 and 35.30 kJ/mol, respectively. The apparent activation energies of desorption for weak type basic center over three catalysts were 25.97, 27.92 and 29.77kJ/mol respectively. The surface basicity on catalysts played an important role in the hydrolysis of COS and CS{sub 2}.The weak basic center was the catalytic active center of COS hydrolysis, while the weak and the weaker basic centers took part in catalytic reaction of CS{sub 2} hydrolysis. The K{sub 2}O and Pt loaded on active {gamma}-Al{sub 2}O{sub 3} could greatly change the distribution of surface basicity over catalysts and increase organic sulfide catalytic hydrolysis.

  1. Sub-5 nm Domains in Ordered Poly(cyclohexylethylene)-block-poly(methyl methacrylate) Block Polymers for Lithography.

    SciTech Connect

    Kennemur, Justin; Yao, Li; Bates, Frank Stephen; Hillmyer, Marc

    2014-01-01

    A series of poly(cyclohexylethylene)-block-poly- (methyl methacrylate) (PCHE PMMA) diblock copolymers with varying molar mass (4.9 kg/mol Mn 30.6 kg/mol) and narrow molar mass distribution were synthesized through a combination of anionic and atom transfer radical polymerization (ATRP) techniques. Heterogeneous catalytic hydrogenation of -(hydroxy)polystyrene (PS-OH) yielded -(hydroxy)poly(cyclohexylethylene) (PCHEOH) with little loss of hydroxyl functionality. PCHE-OH was reacted with -bromoisobutyryl bromide (BiBB) to produce an ATRP macroinitiator used for the polymerization of methyl methacrylate. PCHE PMMA is a glassy, thermally stable material with a large effective segment segment interaction parameter, eff = (144.4 6.2)/T (0.162 0.013), determined by meanfield analysis of order-to-disorder transition temperatures (TODT) measured by dynamic mechanical analysis and differential scanning calorimetry. Ordered lamellar domain pitches (9 D 33 nm) were identified by small-angle X-ray scattering from neat BCPs containing 43 52 vol % PCHE ( f PCHE). Atomic force microscopy was used to show 7.5 nm lamellar features (D = 14.8 nm) which are some of the smallest observed to date. The lowest molar mass sample (Mn = 4.9 kg/mol, f PCHE = 0.46) is characterized by TODT = 173 3 C and sub-5 nm nanodomains, which together with the sacrificial properties of PMMA and the high overall thermal stability place this material at the forefront of high- systems for advanced nanopatterning applications.

  2. Hydrogenation of CO2 to methanol on CeOx/Cu(111) and ZnO/Cu(111) catalysts: Role of the metal-oxide interface and importance of Ce3+ sites

    DOE PAGES [OSTI]

    Sanjaya D. Senanayake; Ramirez, Pedro J.; Waluyo, Iradwikanari; Kundu, Shankhamala; Mudiyanselage, Kumudu; Liu, Zongyuan; Liu, Zhi; Axnanda, Stephanus; Stacchiola, Dario J.; Evans, Jaime; et al

    2016-01-06

    The role of the interface between a metal and oxide (CeOx–Cu and ZnO–Cu) is critical to the production of methanol through the hydrogenation of CO2 (CO2 + 3H2 → CH3OH + H2O). The deposition of nanoparticles of CeOx or ZnO on Cu(111), θoxi < 0.3 monolayer, produces highly active catalysts for methanol synthesis. The catalytic activity of these systems increases in the sequence: Cu(111) < ZnO/Cu(111) < CeOx/Cu(111). The apparent activation energy for the CO2 → CH3OH conversion decreases from 25 kcal/mol on Cu(111) to 16 kcal/mol on ZnO/Cu(111) and 13 kcal/mol on CeOx/Cu(111). The surface chemistry of the highlymore » active CeOx–Cu(111) interface was investigated using ambient pressure X-ray photoemission spectroscopy (AP-XPS) and infrared reflection absorption spectroscopy (AP-IRRAS). Both techniques point to the formation of formates (HCOO–) and carboxylates (CO2δ–) during the reaction. Our results show an active state of the catalyst rich in Ce3+ sites which stabilize a CO2δ– species that is an essential intermediate for the production of methanol. Furthermore, the inverse oxide/metal configuration favors strong metal–oxide interactions and makes possible reaction channels not seen in conventional metal/oxide catalysts.« less

  3. Nanoscale characterization of β-phase H{sub x}Li{sub 1−x}NbO{sub 3} layers by piezoresponse force microscopy

    SciTech Connect

    Manzo, Michele; Gallo, Katia; Denning, Denise; Rodriguez, Brian J.

    2014-08-14

    We investigate a non-destructive approach for the characterization of proton exchanged layers in LiNbO{sub 3} with sub-micrometric resolution by means of piezoresponse force microscopy (PFM). Through systematic analyses, we identify a clear correlation between optical measurements on the extraordinary refractive index and PFM measurements on the piezoelectric d{sub 33} coefficient. Furthermore, we quantify the reduction of the latter induced by proton exchange as 83 ± 2% and 68 ± 3% of the LiNbO{sub 3} value, for undoped and 5 mol. % MgO-doped substrates, respectively.

  4. Orthorhombic-tetragonal phase coexistence and enhanced piezo-response at room temperature in Zr, Sn, and Hf modified BaTiO{sub 3}

    SciTech Connect

    Kalyani, Ajay Kumar; Brajesh, Kumar; Ranjan, Rajeev; Senyshyn, Anatoliy

    2014-06-23

    The effect of Zr, Hf, and Sn in BaTiO{sub 3} has been investigated at close composition intervals in the dilute concentration limit. Detailed structural analysis by x-ray and neutron powder diffraction revealed that merely 2 mol. % of Zr, Sn, and Hf stabilizes a coexistence of orthorhombic (Amm2) and tetragonal (P4mm) phases at room temperature. As a consequence, all the three systems show substantial enhancement in the longitudinal piezoelectric coefficient (d{sub 33}), with Sn modification exhibiting the highest value ∼425 pC/N.

  5. Hydroxide Degradation Pathways for Substituted Benzyltrimethyl Ammonium: A DFT Study

    DOE PAGES [OSTI]

    Long, Hai; Pivovar, Bryan S.

    2014-11-01

    The stability of cations used in the alkaline exchange membranes has been a major challenge. In this paper, degradation energy barriers were investigated by density functional theory for substituted benzyltrimethyl ammonium (BTMA+) cations. Findings show that electron-donating substituent groups at meta-position(s) of the benzyl ring could result in increased degradation barriers. However, after investigating more than thirty substituted BTMA+ cations, the largest improvement in degradation barrier found was only 6.7 kJ/mol. This suggests a modest (8×) improvement in stability for this type of approach may be possible, but for anything greater other approaches will need to be pursued.

  6. Analysis of fixed bed data for the extraction of a rate mechanism for the reaction of hematite with methane

    SciTech Connect

    Breault, Ronald W.; Monazam, Esmail R.

    2015-04-01

    In this study, chemical looping combustion is a promising technology for the capture of CO2 involving redox materials as oxygen carriers. The effects of reduction conditions, namely, temperature and fuel partial pressure on the conversion products are investigated. The experiments were conducted in a laboratory fixed-bed reactor that was operated cyclically with alternating reduction and oxidation periods. Reactions are assumed to occur in the shell surrounding the particle grains with diffusion of oxygen to the surface from the grain core. Activation energies for the shell and core reactions range from 9 to 209 kJ/mol depending on the reaction step.

  7. Electrical conductivity of polycrystalline AI/sub 2/O/sub 3/ doped with silicon

    SciTech Connect

    Lee, C.H.; Kroger, F.A.

    1985-02-01

    Direct current conductivity was measured for polycrystalline AI/sub 2/O/sub 3/ doped with silicon, which is found to act as a single donor, the donor level lying approx. = 165 kJ/mol (approx. =1.7 eV) below the conduction band. Silicon in excess of the solubility limit (approx. =220 ppm at 1500/sup 0/C, 300 ppm at 1600/sup 0/C) is present as a glassy aluminosilicate second phase. Silicon dissolved in AI/sub 2/O/sub 3/ tends to segregate at grain boundaries.

  8. Unconventional hydrogen bonding to organic ions in the gas phase: Stepwise association of hydrogen cyanide with the pyridine and pyrimidine radical cations and protonated pyridine

    SciTech Connect

    Hamid, Ahmed M.; El-Shall, M. Samy; Hilal, Rifaat; Elroby, Shaaban; Aziz, Saadullah G.

    2014-08-07

    Equilibrium thermochemical measurements using the ion mobility drift cell technique have been utilized to investigate the binding energies and entropy changes for the stepwise association of HCN molecules with the pyridine and pyrimidine radical cations forming the C{sub 5}H{sub 5}N{sup +·}(HCN){sub n} and C{sub 4}H{sub 4}N{sub 2}{sup +·}(HCN){sub n} clusters, respectively, with n = 1–4. For comparison, the binding of 1–4 HCN molecules to the protonated pyridine C{sub 5}H{sub 5}NH{sup +}(HCN){sub n} has also been investigated. The binding energies of HCN to the pyridine and pyrimidine radical cations are nearly equal (11.4 and 12.0 kcal/mol, respectively) but weaker than the HCN binding to the protonated pyridine (14.0 kcal/mol). The pyridine and pyrimidine radical cations form unconventional carbon-based ionic hydrogen bonds with HCN (CH{sup δ+}⋯NCH). Protonated pyridine forms a stronger ionic hydrogen bond with HCN (NH{sup +}⋯NCH) which can be extended to a linear chain with the clustering of additional HCN molecules (NH{sup +}⋯NCH··NCH⋯NCH) leading to a rapid decrease in the bond strength as the length of the chain increases. The lowest energy structures of the pyridine and pyrimidine radical cation clusters containing 3-4 HCN molecules show a strong tendency for the internal solvation of the radical cation by the HCN molecules where bifurcated structures involving multiple hydrogen bonding sites with the ring hydrogen atoms are formed. The unconventional H-bonds (CH{sup δ+}⋯NCH) formed between the pyridine or the pyrimidine radical cations and HCN molecules (11–12 kcal/mol) are stronger than the similar (CH{sup δ+}⋯NCH) bonds formed between the benzene radical cation and HCN molecules (9 kcal/mol) indicating that the CH{sup δ+} centers in the pyridine and pyrimidine radical cations have more effective charges than in the benzene radical cation.

  9. Pyrolysis kinetics for the Bakken shale

    SciTech Connect

    Burnham, A.K.

    1992-01-01

    Pyrolysis kinetics are reported and compared for rapid open pyrolysis experiments: Py-TG-FTIR, Py-FID, and Py-MS. Where the type of information obtained overlapped, the results were very similar. The principal activation energy for total hydrocarbon generation using a parallel reaction model is 52 kcal/mol. As with most petroleum source rocks, carbon dioxide generation tends to lead oil formation while ethene and methane generation tend to lag oil generation. The midpoint of oil generation for a geological heating rate of 3 {degrees}C/m.y. is predicted to be between 130 and 140{degrees}C. 5 refs., 4 figs., 1 tab.

  10. Acceleration of Amide Bond Rotation by Encapsulation in the Hydrophobic Interior of a Water-Soluble Supramolecular Assembly

    SciTech Connect

    Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

    2008-04-08

    The hydrophobic interior cavity of a self-assembled supramolecular assembly exploits the hydrophobic effect for the encapsulation of tertiary amides. Variable temperature 1H NMR experiments reveal that the free energy barrier for rotation around the C-N amide bond is lowered by up to 3.6 kcal/mol upon encapsulation. The hydrophobic cavity of the assembly is able to stabilize the less polar transition state of the amide rotation process. Carbon-13 labeling studies showed that the {sup 13}C NMR carbonyl resonance increases with temperature for the encapsulated amides which suggests that the assembly is able to favor a twisted for of the amide.

  11. In-core and ex-core calculations of the VENUS simulated PWR benchmark experiment

    SciTech Connect

    Williams, M.L.; Chowdhury, P.; Landesman, M.; Kam, F.B.K.

    1985-01-01

    The VENUS PWR engineering mockup experiment was established to simulate a beginning-of-life, generic PWR configuration at the zero-power VENUS critical facility located at CEN/SCK, Mol, Belgium. The experimental measurement program consists of (1) gamma scans to determine the core power distribution, (2) in-core and ex-core foil activations, (3) neutron spectrometer measurements, and (4) gamma heating measurements with TLD's. Analysis of the VENUS benchmark has been performed with two-dimensional discrete ordinates transport theory, using the DOT-IV code.

  12. Lignin-derived thermoplastic co-polymers and methods of preparation

    DOEpatents

    Naskar, Amit K.; Saito, Tomonori; Pickel, Joseph M.; Baker, Frederick S.; Eberle, Claude Clifford; Norris, Robert E.; Mielenz, Jonathan Richard

    2014-06-10

    The present invention relates to a crosslinked lignin comprising a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100.degree. C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. Thermoplastic copolymers containing the crosslinked lignin are also described. Methods for producing the crosslinked lignin and thermoplastic copolymers are also described.

  13. In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental Study

    SciTech Connect

    Xie, Xianjun; Wang, Yanxin; Pi, Kunfu; Liu, Chongxuan; Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu

    2015-09-15

    In situ arsenic removal from groundwater by an iron coating method has great potential to be a cost effective and simple groundwater remediation technique, especially in rural and remote areas where groundwater is used as the main source of drinking water. The in situ arsenic removal technique was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions., Its effectiveness was then evaluated in an actual high-arsenic groundwater environment. The mechanism of arsenic removal by the iron coating was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, an electron microprobe, and Fourier transformation infrared spectroscopy. A 4-step alternative cycle aquifer iron coating method was developed. A continuous injection of 5 mmol/L FeSO4 and 2.5 mmol/L NaClO for 96 hours can create a uniform coating of crystalline goethite on the surface of quartz sand in the columns without causing clogging. At a flow rate of 0.45 cm/min of the injection reagents (vi), the time for arsenic (as Na2HAsO4) to pass through the iron-coated quartz sand column was approximately 35 hours, which was much longer than that for tracer fluorescein sodium (approximately 2 hours). The retardation factor of arsenic was 23, and its adsorption capacity was 0.11 mol As per mol Fe, leading to an excellent arsenic removal. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As (V) and Fe (II) reagents. When the arsenic content in the groundwater was 233 ?g/L, the aqueous phase arsenic was completely removed with an arsenic adsorption of 0.05 mol As per mol Fe. Arsenic fixation resulted from a process of adsorption/co-precipitation, in which arsenic and iron likely formed the arsenic-bearing iron mineral phases with poor crystallinity by way of bidentate binuclear complexes. Thus, the high arsenic removal efficiency of the technique likely resulted from the

  14. Analysis of fixed bed data for the extraction of a rate mechanism for the reaction of hematite with methane

    DOE PAGES [OSTI]

    Breault, Ronald W.; Monazam, Esmail R.

    2015-04-01

    In this study, chemical looping combustion is a promising technology for the capture of CO2 involving redox materials as oxygen carriers. The effects of reduction conditions, namely, temperature and fuel partial pressure on the conversion products are investigated. The experiments were conducted in a laboratory fixed-bed reactor that was operated cyclically with alternating reduction and oxidation periods. Reactions are assumed to occur in the shell surrounding the particle grains with diffusion of oxygen to the surface from the grain core. Activation energies for the shell and core reactions range from 9 to 209 kJ/mol depending on the reaction step.

  15. Thermal behavior of the amorphous precursors of the ZrO{sub 2}-SnO{sub 2} system

    SciTech Connect

    Stefanic, Goran Music, Svetozar; Ivanda, Mile

    2008-11-03

    Thermal behavior of the amorphous precursors of the ZrO{sub 2}-SnO{sub 2} system on the ZrO{sub 2}-rich side of the concentration range, prepared by co-precipitation from aqueous solutions of the corresponding salts, was monitored using differential thermal analysis, X-ray powder diffraction, Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectrometry (EDS). The crystallization temperature of the amorphous precursors increased with an increase in the SnO{sub 2} content, from 405 deg. C (0 mol% SnO{sub 2}) to 500 deg. C (40 mol% SnO{sub 2}). Maximum solubility of Sn{sup 4+} ions in the ZrO{sub 2} lattice ({approx}25 mol%) occurred in the metastable products obtained upon crystallization of the amorphous precursors. A precise determination of unit-cell parameters, using both Rietveld and Le Bail refinements of the powder diffraction patterns, shows that the incorporation of Sn{sup 4+} ions causes an asymmetric distortion of the monoclinic ZrO{sub 2} lattice. The results of phase analysis indicate that the incorporation of Sn{sup 4+} ions has no influence on the stabilization of cubic ZrO{sub 2} and negligible influence on the stabilization of tetragonal ZrO{sub 2}. Partial stabilization of tetragonal ZrO{sub 2} in products having a tin content above its solid-solubility limit was attributed to the influence of ZrO{sub 2}-SnO{sub 2} surface interactions. In addition to phases closely structurally related to cassiterite, monoclinic ZrO{sub 2} and tetragonal ZrO{sub 2}, a small amount of metastable ZrSnO{sub 4} phase appeared in the crystallization products of samples with 40 and 50 mol% of SnO{sub 2} calcined at 1000 deg. C. Further temperature treatments caused a decrease in and disappearance of metastable phases. The results of the micro-structural analysis show that the sinterability of the crystallization products significantly decreases with an increase in the SnO{sub 2} content.

  16. Effect of cold work and processing orientation on stress corrosion cracking behavior of alloy 600

    SciTech Connect

    Moshier, W.C.; Brown, C.M.

    2000-03-01

    Cold work accelerates stress corrosion cracking (SCC) growth rates in Alloy 600 (UNS N06600). However, the variation in crack growth rates generated from cold-worked material has been significant, and the effect has been difficult to quantify. A study was performed in hydrogenated water adjusted to pH 10.2 to evaluate systematically the effect of cold work on Alloy 600 as a function of temperature, amount of cold work, stress intensity factor, and processing orientation. Cold work was introduced into the material by tensile prestraining or cold-rolling plate product. Crack growth rates were determined between 252 C and 360 C, stress intensity factors between 21 MPa{radical}m and 55 MPa{radical}m, and yield strengths between 201 MPa and 827 MPa. The material with the highest yield strength was cold-rolled and tested in the longitudinal-transverse (LT) and short-transverse (ST) orientations. Crack growth rates increased with increasing temperature, stress intensity factor, and yield strength. Furthermore, crack growth rates were a strong function of the processing orientation in the cold-rolled plate, with growth rates approximately an order of magnitude greater in the ST orientation compared to the LT orientation. Crack growth rates in the LT orientation were measured between 0.003 x 10{sup {minus}9} m/s and 1.95 x 10{sup {minus}9} m/s and between 0.066 x 10{sup {minus}9} m/s and 6.3 x 10{sup {minus}9} m/s in the ST orientation. Activation energies were slightly greater in the ST orientation, ranging from 154 kcal/mol to 191 kcal/mol, compared to activation energies between 126 kJ/mol and 157 kJ/mol in the LT orientation. Results of this study demonstrated that, although cold work can be used to accelerate SCC, the orientation of crack growth significantly can affect the results and must be taken into account when analyzing data from cold-worked material.

  17. Accurate Thermochemical Properties for Energetic Materials Applications. II. Heats of Formation of Imidazolium-, 1,2,4-Triazolium-, and Tetrazolium-Based Energetic Salts fromIsodesmic and Lattice Energy Calculations.

    SciTech Connect

    Gutowski, Keith E; Rogers, Robin D; Dixon, David A

    2007-03-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. A computational approach to the prediction of the heats of formation (ΔHf°’s) of solid-state energetic salts from electronic structure and volume-based thermodynamics (VBT) calculations is described. The method uses as its starting point reliable ΔHf°’s for energetic precursor molecules and ions. The ΔHf°’s of more complex energetics species such as substituted imidazole, 1,2,4-triazole, and tetrazole molecules and ions containing amino, azido, and nitro (including methyl) substituents are calculated using an isodesmic approach at the MP2/complete basis set level. On the basis of comparisons to experimental data for neutral analogues, this isodesmic approach is accurate to <3 kcal/mol for the predicted cation and anion ΔHf°’s. The ΔHf°’s of the energetic salts in the solid state are derived from lattice energy (UL) calculations using a VBT approach. Improved values for the ∝ and β parameters of 19.9 (kcal nm)/mol and 37.6 kcal/mol for the UL equation were obtained on the basis of comparisons to experimental UL’s for a series of 23 salts containing ammonium, alkylammonium, and hydrazinium cations. The total volumes are adjusted to account for differences between predicted and experimental total volumes due to different shapes of the ions (flat vs spherical). The predicted ΔHf°’s of the energetic salts are estimated to have error bars of 6-7 kcal/mol, on the basis of comparisons to established experimental ΔHf°’s of a subset of the salts studied. Energetic salts with the highest positive ΔHf°’s are predicted for azido-containing cations, coupled with heterocyclic anions containing nitro substituents. The substitution of functional groups on

  18. The reaction of cobaloximes with hydrogen: Products and thermodynamics

    DOE PAGES [OSTI]

    Estes, Deven P.; Grills, David C.; Norton, Jack R.

    2014-11-26

    In this study, a cobalt hydride has been proposed as an intermediate in many reactions of the Co(dmgBF₂)₂L₂ system, but its observation has proven difficult. We have observed the UV–vis spectra of Co(dmgBF₂)₂L₂ (1) in CH₃CN under hydrogen pressures up to 70 atm. A Co(I) compound (6), with an exchangeable proton, is eventually formed. We have determined the bond dissociation free energy and pKa of the new O–H bond in 6 to be 50.5 kcal/mol and 13.4, respectively, in CH₃CN, matching previous reports.

  19. Hydrocracking with molten zinc chloride catalyst containing 2-12% ferrous chloride

    DOEpatents

    Zielke, Clyde W.; Bagshaw, Gary H.

    1981-01-01

    In a process for hydrocracking heavy aromatic polynuclear carbonaceous feedstocks to produce hydrocarbon fuels boiling below about 475.degree. C. by contacting the feedstocks with hydrogen in the presence of a molten zinc chloride catalyst and thereafter separating at least a major portion of the hydrocarbon fuels from the spent molten zinc chloride catalyst, an improvement comprising: adjusting the FeCl.sub.2 content of the molten zinc chloride to from about 2 to about 12 mol percent based on the mixture of ferrous chloride and molten zinc chloride.

  20. The reaction of cobaloximes with hydrogen: Products and thermodynamics

    SciTech Connect

    Estes, Deven P.; Grills, David C.; Norton, Jack R.

    2014-11-26

    In this study, a cobalt hydride has been proposed as an intermediate in many reactions of the Co(dmgBF?)?L? system, but its observation has proven difficult. We have observed the UVvis spectra of Co(dmgBF?)?L? (1) in CH?CN under hydrogen pressures up to 70 atm. A Co(I) compound (6), with an exchangeable proton, is eventually formed. We have determined the bond dissociation free energy and pKa of the new OH bond in 6 to be 50.5 kcal/mol and 13.4, respectively, in CH?CN, matching previous reports.

  1. Deducing the Energetic Cost of Protein Folding in Zinc Finger Proteins Using Designed Metallopeptides

    SciTech Connect

    Reddi,A.; Guzman, T.; Breece, r.; Tierney, D.; Gibney, B.

    2007-01-01

    Zinc finger transcription factors represent the largest single class of metalloproteins in the human genome. Binding of Zn(II) to their canonical Cys4, Cys3His1, or Cys2His2 sites results in metal-induced protein folding events required to achieve their proper structure for biological activity. The thermodynamic contribution of Zn(II) in each of these coordination spheres toward protein folding is poorly understood because of the coupled nature of the metal-ligand and protein-protein interactions. Using an unstructured peptide scaffold, GGG, we have employed fluorimetry, potentiometry, and calorimetry to determine the thermodynamics of Zn(II) binding to the Cys4, Cys3His1, and Cys2His2 ligand sets with minimal interference from protein folding effects. The data show that Zn(II) complexation is entropy driven and modulated by proton release. The formation constants for Zn(II)-GGG with a Cys4, Cys3His1, or Cys2His2 site are 5.6 x 1016, 1.5 x 1015, or 2.5 x 1013 M-1, respectively. Thus, the Zn(II)-Cys4, Zn(II)-Cys3His1, and Zn(II)-Cys2His2 interactions can provide up to 22.8, 20.7, and 18.3 kcal/mol, respectively, in driving force for protein stabilization, folding, and/or assembly at pH values above the ligand pKa values. While the contributions from the three coordination motifs differ by 4.5 kcal/mol in Zn(II) affinity at pH 9.0, they are equivalent at physiological pH, ?G = -16.8 kcal/mol or a Ka = 2.0 x 1012 M-1. Calorimetric data show that this is due to proton-based enthalpy-entropy compensation between the favorable entropic term from proton release and the unfavorable enthalpic term due to thiol deprotonation. Since protein folding effects have been minimized in the GGG scaffold, these peptides possess nearly the tightest Zn(II) affinities possible for their coordination motifs. The Zn(II) affinities in each coordination motif are compared between the GGG scaffold and natural zinc finger proteins to determine the free energy required to fold the latter

  2. Ab initio investigation on hydrogen adsorption capability in Zn and Cu-based metal organic frameworks

    SciTech Connect

    Tanuwijaya, V. V.; Hidayat, N. N. Agusta, M. K. Dipojono, H. K.

    2015-09-30

    One of the biggest challenge in material technology for hydrogen storage application is to increase hydrogen uptake in room temperature and pressure. As a class of highly porous material, Metal-Organic Frameworks (MOF) holds great potential with its tunable structure. However, little is known about the effect of metal cluster to its hydrogen storage capability. Investigation on this matter has been carried out carefully on small cluster of Zn and Cu-based MOF using first principles method. The calculation of two distinct building units of MOFs, namely octahedral and paddle-wheel models, have been done with B3LYP density functional method using 6-31G(d,p) and LANL2DZ basis sets. From geometry optimization of Zn-based MOF linked by benzene-dicarboxylate (MOF-5), it is found that hydrogen tends to keep distance from metal cluster group and stays above benzene ring. In the other hand, hydrogen molecule prefers to stay atop of the exposed Cu atom in Cu-based MOF system linked by the same linker group (Cu-bdc). Calculated hydrogen binding enthalpies for Zn and Cu octahedral cages at ZnO{sub 3} sites are 1.64kJ/mol and 2.73kJ/mol respectively, while hydrogen binding enthalpies for Zn and Cu paddle-wheel cages calculated on top of metal atoms are found to be at 6.05kJ/mol and 6.10kJ/mol respectively. Major difference between Zn-MOF-5 and Cu-bdc hydrogen uptake performance might be caused by unsaturated metal sites present in Cu-bdc system and the influence of their geometric structures, although a small difference on binding energy in the type of transition metal used is also observed. The comparison between Zn and Cu-based MOF may contribute to a comprehensive understanding of metal clusters and the importance of selecting best transition metal for design and synthesis of metal-organic frameworks.

  3. PHOTOSYNTHESIS AND RESOURCE ALLOCATION OF THREE MOJAVE DESERT GRASSES IN RESPONSE TO ELEVATED ATMOSPHERIC CO2

    SciTech Connect

    L. A. DEFALCO; C. K. IVANS; P. VIVIN; J. R. SEEMANN; R. S. NOWAK

    2004-01-01

    Gas exchange, biomass and N allocation were compared among three Mojave Desert grasses representing different functional types to determine if photosynthetic responses and the associated allocation of resources within the plant changed after prolonged exposure to elevated CO{sub 2}. Leaf gas exchange characteristics were measured for Bromus madritensis ssp. rubens (C{sub 3} invasive annual), Achnatherum hymenoides (C{sub 3} native perennial) and Pleuraphis rigida (C{sub 4} native perennial) exposed to 360 {micro}mol mol{sup -1} (ambient) and 1000 {micro}mol mol{sup -1} (elevated) CO{sub 2} concentrations in a glasshouse experiment, and tissue biomass and total N pools were quantified from three harvests during development. The maximum rate of carboxylation by the N-rich enzyme Rubisco (Vc{sub max}), which was inferred from the relationship between net CO{sub 2} assimilation (A{sub net}) and intracellular CO{sub 2} concentration (c{sub i}), declined in the C{sub 3} species Bromus and Achnatherum across all sampling dates, but did not change at elevated CO{sub 2} for the C{sub 4} Pleuraphis. Whole plant N remained the same between CO{sub 2} treatments for all species, but patterns of allocation differed for the short- and long-lived C{sub 3} species. For Bromus, leaf N used for photosynthesis was reallocated to reproduction at elevated CO{sub 2} as inferred from the combination of lower Vc{sub max} and N per leaf area (NLA) at elevated CO{sub 2}, but similar specific leaf area (SLA, cm{sup 2} g{sup -1}), and of greater reproductive effort (RE) for the elevated CO{sub 2} treatment. Vc{sub max}, leaf N concentration and NLA declined for the perennial Achnatherum at elevated CO{sub 2} potentially due to accumulation of carbohydrates or changes in leaf morphology inferred from lower SLA and greater total biomass at elevated CO{sub 2}. In contrast, Vc{sub max} for the C{sub 4} perennial Pleuraphis did not change at elevated CO{sub 2}, and tissue biomass and total N were

  4. Do Practical Standard Coupled Cluster Calculations Agree Better than Kohn–Sham Calculations with Currently Available Functionals When Compared to the Best Available Experimental Data for Dissociation Energies of Bonds to 3d Transition Metals?

    SciTech Connect

    Xu, Xuefei; Zhang, Wenjing; Tang, Mingsheng; Truhlar, Donald G.

    2015-05-12

    Coupled-cluster (CC) methods have been extensively used as the high-level approach in quantum electronic structure theory to predict various properties of molecules when experimental results are unavailable. It is often assumed that CC methods, if they include at least up to connected-triple-excitation quasiperturbative corrections to a full treatment of single and double excitations (in particular, CCSD(T)), and a very large basis set, are more accurate than Kohn–Sham (KS) density functional theory (DFT). In the present work, we tested and compared the performance of standard CC and KS methods on bond energy calculations of 20 3d transition metal-containing diatomic molecules against the most reliable experimental data available, as collected in a database called 3dMLBE20. It is found that, although the CCSD(T) and higher levels CC methods have mean unsigned deviations from experiment that are smaller than most exchange-correlation functionals for metal–ligand bond energies of transition metals, the improvement is less than one standard deviation of the mean unsigned deviation. Furthermore, on average, almost half of the 42 exchange-correlation functionals that we tested are closer to experiment than CCSD(T) with the same extended basis set for the same molecule. The results show that, when both relativistic and core–valence correlation effects are considered, even the very high-level (expensive) CC method with single, double, triple, and perturbative quadruple cluster operators, namely, CCSDT(2)Q, averaged over 20 bond energies, gives a mean unsigned deviation (MUD(20) = 4.7 kcal/mol when one correlates only valence, 3p, and 3s electrons of transition metals and only valence electrons of ligands, or 4.6 kcal/mol when one correlates all core electrons except for 1s shells of transition metals, S, and Cl); and that is similar to some good xc functionals (e.g., B97-1 (MUD(20) = 4.5 kcal/mol) and PW6B95 (MUD(20) = 4.9 kcal/mol)) when the same basis set is used

  5. Evolution of structure in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} single crystals with BaTiO{sub 3}

    SciTech Connect

    Ge, Wenwei Luo, Chengtao; Li, Jiefang; Viehland, D.; Zhang, Qinhui; Luo, Haosu; Ren, Yang

    2014-10-20

    The structural, dielectric, and piezoelectric properties of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-x mol. %BaTiO{sub 3} (NBT-x%BT) crystals have been investigated. The dielectric and piezoelectric properties of NBT-x%BT were enhanced near x = 5–7. High resolution synchrotron x-ray powder diffraction studies revealed the presence of a phase boundary between monoclinic (Cc) and tetragonal (P4bm) phases near x = 5–7, where the dielectric and piezoelectric properties were enhanced.

  6. Synthesis and characterization of zinc doped nano TiO{sub 2} for efficient photocatalytic degradation of Eriochrome Black T

    SciTech Connect

    Singla, Pooja; Singh, Kulvir; Pandey, O. P.; Sharma, Manoj

    2013-06-03

    Sol-gel method was used to synthesize undoped and zinc doped TiO{sub 2} with varied dopant concentrations using titanium tetraisopropoxide and zinc acetate as precursors. The synthesized catalyst samples were characterized by various techniques such as X-ray powder diffraction (XRD), UV-vis diffuse reflectance (DRS). The photocatalytic activity was determined by means of degradation of azo dye Eriochrome Black T. The results revealed that Zn doped TiO{sub 2} nanoparticles exhibited better results as compared to undoped TiO{sub 2} nanoparticles. Zn doped TiO{sub 2} (0.7mol %) nanoparticles exhibited the highest photocatalytic activity.

  7. High Capacity Hydrogen Storage Nanocomposite - Energy Innovation Portal

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Hydrogen and Fuel Cell Hydrogen and Fuel Cell Energy Storage Energy Storage Advanced Materials Advanced Materials Find More Like This Return to Search High Capacity Hydrogen Storage Nanocomposite Processes to add metal hydrideds to nanocarbon structures to yield high capacity hydrogen storage materials Savannah River National Laboratory Contact SRNL About This Technology Plot of Number of hydrogen atoms per lithium atom vs the Mol ratio of C<sub>60</sub>:Li.&nbsp; An ratio of 1:6

  8. Polarization reversal and domain kinetics in magnesium doped stoichiometric lithium tantalate

    SciTech Connect

    Shur, V. Ya., E-mail: vladimir.shur@urfu.ru; Akhmatkhanov, A. R.; Baturin, I. S. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation); Labfer Ltd., 620014 Ekaterinburg (Russian Federation); Chuvakova, M. A. [Institute of Natural Sciences, Ural Federal University, 620000 Ekaterinburg (Russian Federation)

    2014-10-13

    The polarization reversal process has been studied in 1?mol.?% MgO doped stoichiometric lithium tantalate (LT) single crystal. The revealed stages of domain structure evolution represent (1) continuous nucleation and growth of isolated hexagonal domains with walls oriented along Y directions and (2) continuous motion of the plane domain walls stimulated by merging with isolated domains. The activation field dependence of the switching time has been revealed. The coercive field for quasi-static switching is about 150?V/mm. The bulk screening process has been analyzed. The main parameters of the switching process have been compared with other representatives of LT family.

  9. Respiration-Correlated Image Guidance Is the Most Important Radiotherapy Motion Management Strategy for Most Lung Cancer Patients

    SciTech Connect

    Korreman, Stine, E-mail: korreman@ruc.dk [Department of Science, Systems and Models, Roskilde University, Roskilde (Denmark); Department of Radiation Oncology, The Finsen Centre, Rigshospitalet, Copenhagen (Denmark); Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark); Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison (United States); Persson, Gitte; Nygaard, Ditte [Department of Radiation Oncology, The Finsen Centre, Rigshospitalet, Copenhagen (Denmark); Brink, Carsten [Laboratory of Radiation Physics, Odense University Hospital, Odense (Denmark); Faculty of Health Sciences, University of Southern Denmark, Odense (Denmark); Juhler-Nottrup, Trine [Department of Oncology, Herlev Hospital, Copenhagen (Denmark)

    2012-07-15

    Purpose: The purpose of this study was to quantify the effects of four-dimensional computed tomography (4DCT), 4D image guidance (4D-IG), and beam gating on calculated treatment field margins in a lung cancer patient population. Materials and Methods: Images were acquired from 46 lung cancer patients participating in four separate protocols at three institutions in Europe and the United States. Seven patients were imaged using fluoroscopy, and 39 patients were imaged using 4DCT. The magnitude of respiratory tumor motion was measured. The required treatment field margins were calculated using a statistical recipe (van Herk M, et al. Int J Radiat Oncol Biol Phys 2000;474:1121-1135), with magnitudes of all uncertainties, except respiratory peak-to-peak displacement, the same for all patients, taken from literature. Required margins for respiratory motion management were calculated using the residual respiratory tumor motion for each patient for various motion management strategies. Margin reductions for respiration management were calculated using 4DCT, 4D-IG, and gated beam delivery. Results: The median tumor motion magnitude was 4.4 mm for the 46 patients (range 0-29.3 mm). This value corresponded to required treatment field margins of 13.7 to 36.3 mm (median 14.4 mm). The use of 4DCT, 4D-IG, and beam gating required margins that were reduced by 0 to 13.9 mm (median 0.5 mm), 3 to 5.2 mm (median 5.1 mm), and 0 to 7 mm (median 0.2 mm), respectively, to a total of 8.5 to 12.4 mm (median 8.6 mm). Conclusion: A respiratory management strategy for lung cancer radiotherapy including planning on 4DCT scans and daily image guidance provides a potential reduction of 37% to 47% in treatment field margins. The 4D image guidance strategy was the most effective strategy for >85% of the patients.

  10. Radioprotectors and Tumors: Molecular Studies in Mice

    SciTech Connect

    Gayle Woloschak, David Grdina

    2010-03-10

    This proposal investigated effects of radiation using a set of archival tissues. Main interests of this proposal were to investigate effects of irradiation alone or in the presence or radioprotectors; to investigate these effects on different tissues; and to use/develop molecular biology techniques that would be suitable for work with archived tissues. This work resulted in several manuscripts published or in preparation. Approach for evaluation of gene copy numbers by quantitative real time PCR has been developed and we are striving to establish methods to utilize Q-RT-PCR data to evaluate genomic instability caused by irradiation(s) and accompanying treatments. References: 1. Paunesku D, Paunesku T, Wahl A, Kataoka Y, Murley J, Grdina DJ, Woloschak GE. Incidence of tissue toxicities in gamma ray and fission neutron-exposed mice treated with Amifostine. Int J Radiat Biol. 2008, 84(8):623-34. PMID: 18661379, http://informahealthcare.com/doi/full/10.1080/09553000802241762?cookieSet=1 2. Wang Q, Paunesku T and Woloschak GE. Tissue and data archives from irradiation experiments conducted at Argonne National Laboratory over a period of four decades, in press in Radiation and Environmental Biophysics. 3. Alcantara M, Paunesku D, Rademaker A, Paunesku T and Woloschak GE. A RETROSPECTIVE ANALYSIS OF TISSUE TOXICITIES IN B6CF1 MICE IRRADIATED WITH FISSION NEUTRONS OR COBALT 60 GAMMA RAYS: Gender modulates accumulation of tissue toxicities caused by low dose rate fractionated irradiation; in preparation; this document has been uploaded as STI product 4. Wang Q, Paunesku T Wanzer B and Woloschak GE. Mitochondrial gene copy number differences in different tissues of irradiated and control mice with lymphoid cancers; in preparation 5. Wang Q, Raha, S, Paunesku T and Woloschak GE. Evaluation of gene copy number differences in different tissues of irradiated and control mice; in preparation

  11. Thermal analysis and temperature dependent dielectric responses of Co doped anatase TiO{sub 2} nanoparticles

    SciTech Connect

    Alamgir; Khan, Wasi; Ahammed, Nashiruddin; Naqvi, A. H.; Ahmad, Shabbir

    2015-05-15

    Nanoparticles (NPs) of pure and 5?mol % cobalt doped TiO{sub 2} synthesized through acid modified sol-gel method were characterized to understand their thermal, structural, morphological, and temperature dependent dielectric properties. Thermogravimetric analysis (TGA) has been used for thermal studies and indicates the weight loss in two steps due to the removal of residual organics. X-ray diffraction study was employed to confirm the formation of single anatase phase with tetragonal symmetry for both pure and 5?mol % Co doped TiO{sub 2} NPs. The average crystallite size of both samples was calculated from the Scherrers formula and was found in the range from 9-11?nm. TEM micrographs of these NPs reflect their shape and distribution. The dielectric constant (??), dielectric loss (tan?) and ac conductivity (?{sub ac}) were also studied as a function of temperature at different frequencies. Electrical responses of the synthesized NPs have been analyzed carefully in the framework of relevant models. It is also noticed that the dielectric constant (??) of the samples found to decrease with increasing frequency but increases with increasing temperature up to a particular value and then sharply decreases. Temperature variation of dielectric constant exhibits step like escalation and shows relaxation behavior. Study of dielectric properties shows dominant dependence on the grain size as well as Co ion incorporation in TiO{sub 2}.

  12. Electrochemical Investigation of Li–Al Anodes in Oligo(ethylene glycol) Dimethyl Ether/LiPF6

    SciTech Connect

    Zhou, Y.N.; Yang, X.; Wang, X.J.; Lee, H.S.; Nam, K.W.; Haas, O.

    2010-11-01

    1 M LiPF{sub 6} dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight 500 g mol{sup -1} was investigated as a new electrolyte (OEGDME500, 1 M LiPF{sub 6}) for metal deposition and battery applications. At 25 C a conductivity of 0.48 x 10{sup -3} S cm{sup -1} was obtained and at 85 C, 3.78 x 10{sup -3} S cm{sup -1}. The apparent activation barrier for ionic transport was evaluated to be 30.7 kJ mol{sup -1}. OEGDME500, 1 M LiPF{sub 6} allows operating temperature above 100 C with very attractive conductivity. The electrolyte shows excellent performance at negative and positive potentials. With this investigation, we report experimental results obtained with aluminum electrodes using this electrolyte. At low current densities lithium ion reduction and re-oxidation can be achieved on aluminum electrodes at potentials about 280 mV more positive than on lithium electrodes. In situ X-ray diffraction measurements collected during electrochemical lithium deposition on aluminum electrodes show that the shift to positive potentials is due to the negative Gibbs free energy change of the Li-Al alloy formation reaction.

  13. Electrochemical Investigation of Li-Al Anodes in Oligo (ethylene glycol) Dimethyl ether/LiPF6

    SciTech Connect

    Y Zhou; X Wang; H Lee; K Nam; X Yang; O Haas

    2011-12-31

    LiPF{sub 6} dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight 5 g mol{sup -1} was investigated as a new electrolyte (OEGDME5, 1 M LiPF{sub 6}) for metal deposition and battery applications. At 25 C a conductivity of .48 x 1{sup -3} S cm{sup -1} was obtained and at 85 C, 3.78 x 1{sup -3} S cm{sup -1}. The apparent activation barrier for ionic transport was evaluated to be 3.7 kJ mol{sup -1}. OEGDME5, 1 M LiPF{sub 6} allows operating temperature above 1 C with very attractive conductivity. The electrolyte shows excellent performance at negative and positive potentials. With this investigation, we report experimental results obtained with aluminum electrodes using this electrolyte. At low current densities lithium ion reduction and re-oxidation can be achieved on aluminum electrodes at potentials about 28 mV more positive than on lithium electrodes. In situ X-ray diffraction measurements collected during electrochemical lithium deposition on aluminum electrodes show that the shift to positive potentials is due to the negative Gibbs free energy change of the Li-Al alloy formation reaction.

  14. Pressure effect on ionic conductivity in yttrium-oxide-doped single-crystal zirconium oxide

    SciTech Connect

    Park, E.T.; Park, J.H.

    1998-06-01

    In this study, the authors investigated the effect of pressure on the ionic conductivity of a 9.5 mol% yttria-stabilized zirconia (YSZ) single crystal. The experiment was conducted in the elastic region, and the oxygen ion transport number was unity (t{sub ion} > 0.99999). A conventional four-probe DC method was used to measure the ionic conductivity of the rectangular-shaped sample under uniaxial pressures up to 600 atm at 750 C in air. Measured ionic conductivity decreased as applied pressure increased. Based on henry Eyring`s absolute reaction rate theory, which states that the calculated activation volume has a positive value ({Delta}V{sup 2} = 2.08 cm{sup 3}/mol of O{sup {minus}2}) for oxygen ion transport in the fluoride cubic lattice, they concluded that the results they obtained could be explained by an oxygen ion transport mechanism. This mechanism can explain the fact that the interionic distance increases during oxygen ion transport from one unit cell to neighboring unit cells.

  15. Activation of small alkanes in Ga-exchanged zeolites: A quantum chemical study of ethane dehydrogenation

    SciTech Connect

    Frash, M.V.; Santen, R.A. van

    2000-03-23

    Quantum chemical calculations on the mechanism of ethane dehydrogenation catalyzed by Ga-exchanged zeolites have been undertaken. Two forms of gallium, adsorbed dihydride gallium ion GaH{sub 2}+Z{sup {minus}} and adsorbed gallyl ion [Ga=O]{sup +}Z{sup {minus}}, were considered. It was found that GaH{sub 2}{sup +}Z{sup {minus}} is the likely active catalyst. On the contrary, [Ga=O]{sup +}Z{sup {minus}} cannot be a working catalyst in nonoxidative conditions, because regeneration of this form is very difficult. Activation of ethane by GaH{sub 2}{sup +}Z{sup {minus}} occurs via an alkyl mechanism and the gallium atom acts as an acceptor of the ethyl group. The carbenium activation of ethane, with gallium abstracting a hydride ion, is much (ca. 51 kcal/mol) more difficult. The catalytic cycle for the alkyl activation consists of three elementary steps: (1) rupture of the ethane C-H bond; (2) formation of dihydrogen from the Bronsted proton and hydrogen bound to Ga; and (3) formation of ethene from the ethyl group bound to Ga. The best estimates (MP2/6--311++G(2df,p)//B3LYP/6--31G*) for the activation energies of these three steps are 36.9, ca. 0, and 57.9 kcal/mol, respectively.

  16. Lithium ion conducting electrolytes

    DOEpatents

    Angell, C. Austen; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte having exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH.sub.3 CN) succinnonitrile (CH.sub.2 CN).sub.2, and tetraglyme (CH.sub.3 --O--CH.sub.2 --CH.sub.2 --O--).sub.2 (or like solvents) solvated to a Mg.sup.+2 cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100.degree. C. conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone.

  17. Lithium ion conducting electrolytes

    DOEpatents

    Angell, C.A.; Liu, C.

    1996-04-09

    A liquid, predominantly lithium-conducting, ionic electrolyte is described having exceptionally high conductivity at temperatures of 100 C or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH{sub 3}CN), succinnonitrile (CH{sub 2}CN){sub 2}, and tetraglyme (CH{sub 3}--O--CH{sub 2}--CH{sub 2}--O--){sub 2} (or like solvents) solvated to a Mg{sup +2} cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100 C conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone. 2 figs.

  18. Efficient photoluminescence of Dy{sup 3+} at low concentrations in nanocrystalline ZrO{sub 2}

    SciTech Connect

    Diaz-Torres, L.A.; Rosa, E. de la Salas, P.; Romero, V.H.; Angeles-Chavez, C.

    2008-01-15

    Nanocrystalline ZrO{sub 2}:Dy{sup 3+} were prepared by sol-gel and the structural and photoluminescence properties characterized. The crystallite size ranges from 20 to 50 nm and the crystalline phase is a mixture of tetragonal and monoclinic structure controlled by dopant concentration. Strong white light produced by the host emission band centered at {approx}460 nm and two strong Dy{sup 3+} emission bands, blue (488 nm) and yellow (580 nm), under direct excitation at 350 nm were observed. The highest efficiency was obtained for 0.5 mol% of Dy{sup 3+}. Emission is explained in terms of high asymmetry of the host suggesting that Dy{sup 3+} are substituted mainly into Zr{sup 4+} lattice sites at the crystallite surface. Luminescence quenching is explained in terms of cross-relaxation of intermediate Dy{sup 3+} levels. - Graphical abstract: White light emission from {approx}70 nm ZrO{sub 2}:Dy{sup 3+} nanocrystals. The highest efficiency was obtained for 0.5 mol% of dopant and the dominant crystalline structure was monoclinic.

  19. Magnetic order and heavy fermion behavior in CePd{sub 1+x}Al{sub 6-x}: Synthesis, structure, and physical properties

    SciTech Connect

    Tobash, Paul H., E-mail: ptobash@lanl.go [Materials Physics and Application Division, MPA-10, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States); Ronning, Filip; Thompson, J.D. [Materials Physics and Application Division, MPA-10, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bobev, Svilen [Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States); Bauer, Eric D. [Materials Physics and Application Division, MPA-10, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2010-03-15

    The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of single crystals are reported for the compound CePd{sub 1+x}Al{sub 6-x} (x=0.5) which crystallizes in the tetragonal SrAu{sub 2}Ga{sub 5}-type structure (space group P4/mmm). The compound was grown from an excess of molten Al flux from the respective elements and the crystal structure was established from single-crystal X-ray diffraction. Anomalies in the low temperature specific heat C{sub p}(T) and electrical resistivity rho(T) show that the compound undergoes ferromagnetic order at T{sub C}=2.8 K. In the ordered state, CePd{sub 1.5}Al{sub 5.5} displays heavy fermion behavior with a Sommerfeld coefficient of ca. 500 mJ/mol-K{sup 2}. - Graphical abstract: The compound CePd{sub 1+x}Al{sub 6-x} (x=0.5) has been synthesized and structurally characterized by single-crystal X-ray diffraction. The measured physical properties of temperature and field dependent magnetic susceptibility, specific heat, and electrical resistivity suggests that the compound undergoes ferromagnetic order at ca. 2.8 K and further exhibits relatively heavy fermion behavior with a Sommerfeld coefficient of 500 mJ/mol-K2.

  20. Molecular basis of endosomal-membrane association for the dengue virus envelope protein

    DOE PAGES [OSTI]

    Rogers, David M.; Kent, Michael S.; Rempe, Susan B.

    2015-01-02

    Dengue virus is coated by an icosahedral shell of 90 envelope protein dimers that convert to trimers at low pH and promote fusion of its membrane with the membrane of the host endosome. We provide the first estimates for the free energy barrier and minimum for two key steps in this process: host membrane bending and protein–membrane binding. Both are studied using complementary membrane elastic, continuum electrostatics and all-atom molecular dynamics simulations. The predicted host membrane bending required to form an initial fusion stalk presents a 22–30 kcal/mol free energy barrier according to a constrained membrane elastic model. Combined continuummore »and molecular dynamics results predict a 15 kcal/mol free energy decrease on binding of each trimer of dengue envelope protein to a membrane with 30% anionic phosphatidylglycerol lipid. The bending cost depends on the preferred curvature of the lipids composing the host membrane leaflets, while the free energy gained for protein binding depends on the surface charge density of the host membrane. The fusion loop of the envelope protein inserts exactly at the level of the interface between the membrane's hydrophobic and head-group regions. As a result, the methods used in this work provide a means for further characterization of the structures and free energies of protein-assisted membrane fusion.« less

  1. Thermodynamics of formation of coffinite, USiO₄

    DOE PAGES [OSTI]

    Guo, Xiaofeng; Szenknect, Stéphanie; Mesbah, Adel; Labs, Sabrina; Clavier, Nicolas; Poinssot, Christophe; Ushakov, Sergey V.; Curtius, Hildegard; Bosbach, Dirk; Ewing, Rodney C.; et al

    2015-05-26

    Coffinite, USiO₄, is an important U(IV) mineral, but its thermodynamic properties are not well-constrained. In this work, two different coffinite samples were synthesized under hydrothermal conditions and purified from a mixture of products. The enthalpy of formation was obtained by high temperature oxide melt solution calorimetry. Coffinite is energetically metastable with respect to a mixture of UO₂ (uraninite) and SiO₂ (quartz) by 25.6 ± 3.9 kJ/mol. Its standard enthalpy of formation from the elements at 25 °C is -1,970.0 ± 4.2 kJ/mol. Decomposition of the two samples was characterized by X-ray diffraction and by thermogravimetry and differential scanning calorimetry coupledmore » with mass spectrometric analysis of evolved gases. Coffinite slowly decomposes to U₃O₈ and SiO₂ starting around 450 °C in air and thus has poor thermal stability in the ambient environment. The energetic metastability explains why coffinite cannot be synthesized directly from uraninite and quartz but can be made by low temperature precipitation in aqueous and hydrothermal environments. These thermochemical constraints are in accord with observations of the occurrence of coffinite in nature and are relevant to spent nuclear fuel corrosion.« less

  2. The hydrogenation of acetylene catalyzed by palladium: Hydrogen pressure dependence

    SciTech Connect

    Molero, H.; Bartlett, B.F.; Tysoe, W.T.

    1999-01-01

    The kinetics of acetylene hydrogenation catalyzed by a clean palladium foil at high pressures are measured and yield an activation energy of 9.6 {+-} 0.1 kcal/mol when using hydrogen. The rate exhibits a deuterium isotope effect such that the reaction activation energy is 9.0 {+-} 0.2 kcal/mol for reaction with deuterium. The hydrogen pressure reaction order is 1.04 {+-} 0.02 at 300 K with an acetylene pressure of 100 Torr and the acetylene order is {minus}0.66 at 300 K and with a hydrogen pressure of 100 Torr. These reaction kinetics closely mimic those of supported model catalysts. In addition, it is found that the rate of benzene formation is accelerated by the addition of hydrogen to the reaction mixture. This is rationalized by proposing that hydrogen enhances the coverage of acetylene under catalytic conditions. This notion can be used to successfully calculate the hydrogen pressure dependence for acetylene hydrogenation as a function of temperature, a value which varies between {approximately}1.05 and 1.3 as the temperature changes from 300 to 380 K. Possible origins for this effect are discussed.

  3. Reversible Redox-Based Optical Sensing of Parts per Million Levels of Nitrosyl Cation in Organic Solvents by Osmium Chromophore-Based Monolayers

    SciTech Connect

    Gupta,T.; Cohen, R.; Evmenenko, G.; Dutta, P.; van der Boom, M.

    2007-01-01

    Exposure of an osmium(II)-based monolayer on glass to organic solvents containing 0.36-116 ppm of NOBF{sub 4} results in one-electron transfer from the covalently immobilized complexes to the inorganic analyte with concurrent optical changes. The NO{sup +} induced oxidation of the monolayer can be detected optically with an off-the-self-UV/vis spectrophotometer (260-800 nm). The redox-based NO{sup +} detection and quantification system can be reset with water within {approx}20 s for at least 40 times. The reaction of the monolayer with a THF solution containing 5 ppm of NOBF{sub 4} follows pseudo first-order kinetics in the monolayer with {Delta}G{sup {double_dagger}}{sub 298K} = 21.5 {+-} 0.7 kcal/mol, {Delta}H{sup {double_dagger}} = 9.5 {+-} 0.3 kcal/mol, and {Delta}S{sup {double_dagger}} = -40.6 {+-} 1.1 eu. The monolayer structure and properties have been resolved by electrochemical measurements and synchrotron X-ray reflectivity measurements in combination with density functional theory calculations (B3LYP/SDD level of theory).

  4. Iron (III) Matrix Effects on Mineralization and Immobilization of Actinides

    SciTech Connect

    Cynthia-May S. Gong; Tyler A. Sullens; Kenneth R. Czerwinski

    2006-01-01

    Abstract - A number of models for the Yucca Mountain Project nuclear waste repository use studies of actinide sorption onto well-defined iron hydroxide materials. In the case of a waste containment leak, however, a complex interaction between dissolved waste forms and failed containment vessel components can lead to immediate precipitation of migratory iron and uranyl in the silicate rich near-field environment. Use of the Fe(III) and UO22+ complexing agent acetohydroxamic acid (AHA) as a colorimetric agent for visible spectrophotometry is well-known. Using the second derivative of these spectra a distinct shift in iron complexation in the presence of silicate is seen that is not seen with uranyl or alone. Silica also decreases the ability of uranyl and ferric solutions to absorb hydroxide, hastening precipitation. These ferric silicate precipitates are highly amorphous and soluble. Precipitates formed in the presence of uranyl below ~1 mol% exhibit lower solubility than precipitates from up to 50 mol % and of uranyl silicates alone.

  5. Optical properties of lanthanide-doped RbTiOAsO{sub 4} and transition metal-doped KTiOPO{sub 4}

    SciTech Connect

    Phillips, M.L.F.; Anderson, M.T.; Sinclair, M.B.

    1993-12-31

    We have synthesized derivatives of potassium titanyl phosphate (KTP) and rubidium titanyl (RTA) where Ti has been replaced by transition metal or lanthanide ions, and K, Ti, P or O has laced by aliovalent counterions. Up to 5 mol % lanthanide ion can be substituted onto the Ti and 100 mol % substitution of other transition metals onto the Ti sites in KTP can be made. The visible spectra of these doped KTP phases are characteristic of the dopant ions, with sharp, narrow transitions resulting from lanthanide substitution and broader absorptions from transition-metal dopants. Powder second harmonic generation (SHG) intensities diminish with increased dopant concentration. Decreases in SHG intensities parallel those seen in previously studied systems. The choice of counterion substantially impacts some dopant solubilities, but generally affects SHG intensity and visible spectrum to a lesser degree. Single crystals doped with Er{sup 3+}, Fe{sup 3+} and Co{sup 2+} have linear absorption coefficients in the range of 1 to 5 cm{sup {minus}1}. Changes in noncritical phase matching wavelength due to anomalous dispersion are calculated to be less than 1 nm at the dopant levels tested.

  6. Activation energy of tantalum-tungsten oxide thermite reactions

    SciTech Connect

    Cervantes, Octavio G.; Munir, Zuhair A.; Kuntz, Joshua D.; Gash, Alexander E.

    2011-01-15

    The activation energy of a sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the high-pressure spark plasma sintering (HPSPS) technique at 300 and 400 C. The ignition temperatures were investigated under high heating rates (500-2000 C min{sup -1}). Such heating rates were required in order to ignite the thermite composite. Samples consolidated at 300 C exhibit an abrupt change in temperature response prior to the main ignition temperature. This change in temperature response is attributed to the crystallization of the amorphous WO{sub 3} in the SG derived Ta-WO{sub 3} thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO{sub 3} thermite ranged from approximately 465 to 670 C. The activation energies of the SG derived Ta-WO{sub 3} thermite composite consolidated at 300 and 400 C were determined to be 38{+-} 2 kJ mol{sup -1} and 57 {+-} 2 kJ mol{sup -1}, respectively. (author)

  7. Activation Energy of Tantalum-Tungsten Oxide Thermite Reaction

    SciTech Connect

    Cervantes, O; Kuntz, J; Gash, A; Munir, Z

    2010-02-25

    The activation energy of a high melting temperature sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the High Pressure Spark Plasma Sintering (HPSPS) technique to 300 and 400 C to produce pellets with dimensions of 5 mm diameter by 1.5 mm height. A custom built ignition setup was developed to measure ignition temperatures at high heating rates (500-2000 C {center_dot} min{sup -1}). Such heating rates were required in order to ignite the thermite composite. Unlike the 400 C samples, results show that the samples consolidated to 300 C undergo an abrupt change in temperature response prior to ignition. This change in temperature response has been attributed to the crystallization of the amorphous WO{sub 3} in the SG derived Ta-WO{sub 3} thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO{sub 3} thermite ranged from approximately 465-670 C. The activation energy of the SG derived Ta-WO{sup 3} thermite composite consolidated to 300 and 400 C were determined to be 37.787 {+-} 1.58 kJ {center_dot} mol{sup -1} and 57.381 {+-} 2.26 kJ {center_dot} mol{sup -1}, respectively.

  8. Catalytic glycerol steam reforming for hydrogen production

    SciTech Connect

    Dan, Monica Mihet, Maria Lazar, Mihaela D.

    2015-12-23

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H{sub 2}. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al{sub 2}O{sub 3}. The catalyst was prepared by wet impregnation method and characterized through different methods: N{sub 2} adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H{sub 2}, CH{sub 4}, CO, CO{sub 2}. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H{sub 2}O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.

  9. Inhibitive formation of nanocavities by introduction of Si atoms in Ge nanocrystals produced by ion implantation

    SciTech Connect

    Cai, R. S.; Shang, L.; Liu, X. H.; Zhang, Y. J.; Wang, Y. Q. E-mail: barba@emt.inrs.ca; Ross, G. G.; Barba, D. E-mail: barba@emt.inrs.ca

    2014-05-28

    Germanium nanocrystals (Ge-nc) were successfully synthesized by co-implantation of Si and Ge ions into a SiO{sub 2} film thermally grown on (100) Si substrate and fused silica (pure SiO{sub 2}), respectively, followed by subsequent annealing at 1150 °C for 1 h. Transmission electron microscopy (TEM) examinations show that nanocavities only exist in the fused silica sample but not in the SiO{sub 2} film on a Si substrate. From the analysis of the high-resolution TEM images and electron energy-loss spectroscopy spectra, it is revealed that the absence of nanocavities in the SiO{sub 2} film/Si substrate is attributed to the presence of Si atoms inside the formed Ge-nc. Because the energy of Si-Ge bonds (301 kJ·mol{sup −1}) are greater than that of Ge-Ge bonds (264 kJ·mol{sup −1}), the introduction of the Si-Ge bonds inside the Ge-nc can inhibit the diffusion of Ge from the Ge-nc during the annealing process. However, for the fused silica sample, no crystalline Si-Ge bonds are detected within the Ge-nc, where strong Ge outdiffusion effects produce a great number of nanocavities. Our results can shed light on the formation mechanism of nanocavities and provide a good way to avoid nanocavities during the process of ion implantation.

  10. Molecular dynamics simulations of the electrical double layer on smectite surfaces contacting concentrated mixed electrolyte (NaCl-CaCl?) solutions

    SciTech Connect

    Bourg, Ian C.; Sposito, Garrison

    2011-01-01

    We report new molecular dynamics results elucidating the structure of the electrical double layer (EDL) on smectite surfaces contacting mixed NaClCaCl2 electrolyte solutions in the range of concentrations relevant to pore waters in geologic repositories for CO2 or high-level radioactive waste (0.341.83 molc dm-3). Our results confirm the existence of three distinct ion adsorption planes (0-, ?-, and d-planes), often assumed in EDL models, but with two important qualifications: (1) the location of the ?- and d-planes are independent of ionic strength or ion type and (2) indifferent electrolyte ions can occupy all three planes. Charge inversion occurred in the diffuse ion swarm because of the affinity of the clay surface for CaCl+ ion pairs. Therefore, at concentrations {>=0.34 molc dm-3}, properties arising from long-range electrostatics at interfaces (electrophoresis, electro-osmosis, co-ion exclusion, colloidal aggregation) will not be correctly predicted by most EDL models. Co-ion exclusion, typically neglected by surface speciation models, balanced a large part of the clay mineral structural charge in the more concentrated solutions. Water molecules and ions diffused relatively rapidly even in the first statistical water monolayer, contradicting reports of rigid ice-like structures for water on clay mineral surfaces.

  11. Computational Study of Bond Dissociation Enthalpies for Substituted $\\beta$-O-4 Lignin Model Compounds

    SciTech Connect

    Younker, Jarod M; Beste, Ariana; Buchanan III, A C

    2011-01-01

    The biopolymer lignin is a potential source of valuable chemicals. Phenethyl phenyl ether (PPE) is representative of the dominant $\\beta$-O-4 ether linkage. Density functional theory (DFT) is used to calculate the Boltzmann-weighted carbon-oxygen and carbon-carbon bond dissociation enthalpies (BDEs) of substituted PPE. These values are important in order to understand lignin decomposition. Exclusion of all conformers that have distributions of less than 5\\% at 298 K impacts the BDE by less than 1 kcal mol$^{-1}$. We find that aliphatic hydroxyl/methylhydroxyl substituents introduce only small changes to the BDEs (0-3 kcal mol$^{-1}$). Substitution on the phenyl ring at the $ortho$ position substantially lowers the C-O BDE, except in combination with the hydroxyl/methylhydroxyl substituents, where the effect of methoxy substitution is reduced by hydrogen bonding. Hydrogen bonding between the aliphatic substituents and the ether oxygen in the PPE derivatives has a significant influence on the BDE. CCSD(T)-calculated BDEs and hydrogen bond strengths of $ortho$-substituted anisoles when compared with M06-2X values confirm that the latter method is sufficient to describe the molecules studied and provide an important benchmark for lignin model compounds.

  12. Plasmon-enhanced reverse water gas shift reaction over oxide supported Au catalysts

    SciTech Connect

    Upadhye, AA; Ro, I; Zeng, X; Kim, HJ; Tejedor, I; Anderson, MA; Dumesic, JA; Huber, GW

    2015-01-01

    We show that localized surface plasmon resonance (LSPR) can enhance the catalytic activities of different oxide-supported Au catalysts for the reverse water gas shift (RWGS) reaction. Oxide-supported Au catalysts showed 30 to 1300% higher activity for RWGS under visible light compared to dark conditions. Au/TiO2 catalyst prepared by the deposition-precipitation (DP) method with 3.5 nm average Au particle size showed the highest activity for the RWGS reaction. Visible light is converted into chemical energy for this reaction with up to a 5% overall efficiency. A shift in the apparent activation energy (from 47 kJ mol(-1) in dark to 35 kJ mol(-1) in light) and apparent reaction order with respect to CO2 (from 0.5 in dark to 1.0 in light) occurs due to the LSPR. Our kinetic results indicate that the LSPR increases the rate of either the hydroxyl hydrogenation or carboxyl decomposition more than any other steps in the reaction network.

  13. Room-temperature ionic liquid-amine solutions: tunable solvents for efficient and reversible capture of CO{sub 2}

    SciTech Connect

    Dean Camper; Jason E. Bara; Douglas L. Gin; Richard D. Noble

    2008-11-05

    Solutions of room-temperature ionic liquids (RTILs) and commercially available amines were found to be effective for the capture of CO{sub 2} as carbamate salts. RTIL solutions containing 50 mol % (16% v/v) monoethanolamine (MEA) are capable of rapid and reversible capture of 1 mol of CO{sub 2} per 2 moles MEA to give an insoluble MEA-carbamate precipitate that helps to drive the capture reaction (as opposed to aqueous amine systems). Diethanolamine (DEA) can also be used in the same manner for CO{sub 2} capture in RTILs containing a pendant hydroxyl group. The captured CO{sub 2} in the resulting RTIL-carbamate salt mixtures can be readily released by either heating and/or subjecting them to reduced pressure. Using this unprecedented and industrially attractive mixing approach, the desirable properties of RTILs (i.e., nonvolatility, enhancedCO{sub 2} solubility, lower heat capacities) can be combined with the performance of amines for CO{sub 2} capture without the use of specially designed, functionalized 'task-specific' ionic liquids. By mixing RTILs with commercial amines, reactive solvents with a wide range of amine loading levels can be tailored to capture CO{sub 2} in a variety of conditions and processes. These RTIL-amine solutions behave similarly to their water-based counterparts but may offer many advantages, including increased energy efficiency, compared to current aqueous amine technologies.

  14. Catalytic Ionic Hydrogenation of Ketones by {[Cp*Ru(CO)2]2(-H)}+

    SciTech Connect

    Bullock, R.M.; Fagan, P.J.; Voges, M.H.

    2010-02-22

    {l_brace}[Cp*Ru(CO){sub 2}]{sub 2}({mu}-H){r_brace}{sup +}OTf{sup -} functions as a homogeneous catalyst precursor for hydrogenation of ketones to alcohols, with hydrogenations at 1 mol % catalyst loading at 90 C under H{sub 2} (820 psi) proceeding to completion and providing >90% yields. Hydrogenation of methyl levulinate generates {gamma}-valerolactone, presumably by ring-closing of the initially formed alcohol with the methyl ester. Experiments in neat Et{sub 2}C=O show that the catalyst loading can be <0.1 mol % and that at least 1200 turnovers of the catalyst can be obtained. These reactions are proposed to proceed by an ionic hydrogenation pathway, with the highly acidic dihydrogen complex [Cp*Ru(CO){sub 2}({eta}{sup 2}-H{sub 2})]{sup +}OTf{sup -} being formed under the reaction conditions from reaction of H2 with {l_brace}[Cp*Ru(CO){sub 2}]{sub 2}({mu}-H){r_brace}{sup +}OTf{sup -}.

  15. Do TFSA anions slither? Pressure exposes the role of TFSA conformational exchange in self-diffusion

    SciTech Connect

    Suarez, Sophia N.; Wishart, James F.; Rua, Armando; Cuffari, David; Pilar, Kartik; Hatcher, Jasmine L.; Ramati, Sharon

    2015-10-28

    Multi-nuclear (1H, 2H, and 19F) magnetic resonance spectroscopy techniques as functions of temperature and pressure were applied to the study of selectively deuterated 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMIM TFSA) ionic liquid isotopologues and related ionic liquids. For EMIM TFSA, temperature-dependent 2H T1 data indicate stronger electric field gradients in the alkyl chain region compared to the imidazolium ring. Most significantly, the pressure dependences of the EMIM and TFSA self-diffusion coefficients revealed that the displacements of the cations and anions are independent, with diffusion of the TFSA anions being slowed much more by increasing pressure than for the EMIM cations, as shown by their respective activation volumes (28.8 ± 2.5 cm³/mol for TFSA vs. 14.6 ± 1.3 cm³/mol for EMIM). Increasing pressure may lower the mobility of the TFSA anion by hindering its interconversion between trans and cis conformers, a process that is coupled to diffusion according to published molecular dynamics simulations. Measured activation volumes (ΔV) for ion self-diffusion in EMIM bis(fluoromethylsulfonyl)amide and EMIM tetrafluoroborate support this hypothesis.

  16. Do TFSA anions slither? Pressure exposes the role of TFSA conformational exchange in self-diffusion

    DOE PAGES [OSTI]

    Suarez, Sophia N.; Wishart, James F.; Rua, Armando; Cuffari, David; Pilar, Kartik; Hatcher, Jasmine L.; Ramati, Sharon

    2015-10-28

    Multi-nuclear (1H, 2H, and 19F) magnetic resonance spectroscopy techniques as functions of temperature and pressure were applied to the study of selectively deuterated 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMIM TFSA) ionic liquid isotopologues and related ionic liquids. For EMIM TFSA, temperature-dependent 2H T1 data indicate stronger electric field gradients in the alkyl chain region compared to the imidazolium ring. Most significantly, the pressure dependences of the EMIM and TFSA self-diffusion coefficients revealed that the displacements of the cations and anions are independent, with diffusion of the TFSA anions being slowed much more by increasing pressure than for the EMIM cations, as shown bymore » their respective activation volumes (28.8 ± 2.5 cm³/mol for TFSA vs. 14.6 ± 1.3 cm³/mol for EMIM). Increasing pressure may lower the mobility of the TFSA anion by hindering its interconversion between trans and cis conformers, a process that is coupled to diffusion according to published molecular dynamics simulations. Measured activation volumes (ΔV‡) for ion self-diffusion in EMIM bis(fluoromethylsulfonyl)amide and EMIM tetrafluoroborate support this hypothesis.« less

  17. The solubility of hydrogen in plutonium in the temperature range 475 to 825 degrees centigrade

    SciTech Connect

    Allen, T.H.

    1991-01-01

    The solubility of hydrogen (H) in plutonium metal (Pu) was measured in the temperature range of 475 to 825{degree}C for unalloyed Pu (UA) and in the temperature range of 475 to 625{degree}C for Pu containing two-weight-percent gallium (TWP). For TWP metal, in the temperature range 475 to 600{degree}C, the saturated solution has a maximum hydrogen to plutonium ration (H/Pu) of 0.00998 and the standard enthalpy of formation ({Delta}H{degree}{sub f(s)}) is (-0.128 {plus minus} 0.0123) kcal/mol. The phase boundary of the solid solution in equilibrium with plutonium dihydride (PuH{sub 2}) is temperature independent. In the temperature range 475 to 625{degree}C, UA metal has a maximum solubility at H/Pu = 0.011. The phase boundary between the solid solution region and the metal+PuH{sub 2} two-phase region is temperature dependent. The solubility of hydrogen in UA metal was also measured in the temperature range 650 to 825{degree}C with {Delta}H{degree}{sub f(s)} = (-0.104 {plus minus} 0.0143) kcal/mol and {Delta}S{degree}{sub f(s)} = 0. The phase boundary is temperature dependent and the maximum hydrogen solubility has H/Pu = 0.0674 at 825{degree}C. 52 refs., 28 figs., 9 tabs.

  18. Kinetics of Hydrogen Isotope Exchange in ?-phase Pd-H-D

    SciTech Connect

    Luo, Weifang; Cowgill, Donald F.

    2015-07-22

    Hydrogen isotope gas exchange within palladium powders is examined using a batch-type reactor coupled to a residual gas analyzer (RGA). Furthermore, the exchange rates in both directions (H2 + PdD and D2 + PdH) are measured in the temperature range 178323 K for the samples with different particle sizes. The results show this batch-type exchange is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An exchange rate constant of 1.40 0.24 ?mol H2/atm cm2 s is found for H2 + PdD at 298 K, 1.4 times higher than that for D2 + PdH, with an activation energy of 25.0 3.2 kJ/mol H for both exchange directions. Finally, a comparison of exchange measurement techniques shows these coefficients, and the fundamental exchange probabilities are in good agreement with those obtained by NMR and flow techniques.

  19. High precision quantum-chemical treatment of adsorption: Benchmarking physisorption of molecular hydrogen on graphane

    SciTech Connect

    Usvyat, Denis

    2015-09-14

    A multilevel hierarchical ab initio protocol for calculating adsorption on non-conducting surfaces is presented. It employs fully periodic treatment, which reaches local Møller-Plesset perturbation theory of second order (MP2) with correction for the basis set incompleteness via the local F12 technique. Post-MP2 corrections are calculated using finite clusters. That includes the coupled cluster treatment in the local and canonical frameworks (up to perturbative quadruples) and correlated core (with MP2). Using this protocol, the potential surface of hydrogen molecules adsorbed on graphane was computed. According to the calculations, hydrogen molecules are adsorbed on graphane in a perpendicular to the surface orientation with the minimum of the potential surface of around −3.6 kJ/mol located at the distance of 3.85 Å between the bond center of the hydrogen molecule and the mid-plane of graphane. The adsorption sites along the path from the downward-pointing carbon to the ring center of the graphane are energetically virtually equally preferable, which can enable nearly free translations of hydrogen molecules along these paths. Consequently, the hydrogen molecules on graphane most likely form a non-commensurate monolayer. The analysis of the remaining errors reveals a very high accuracy of the computed potential surface with an error bar of a few tenths of a kJ/mol. The obtained results are a high-precision benchmark for further theoretical and experimental studies of hydrogen molecules interacting with graphane.

  20. Thermodynamics of formation of coffinite, USiO?

    SciTech Connect

    Guo, Xiaofeng; Szenknect, Stphanie; Mesbah, Adel; Labs, Sabrina; Clavier, Nicolas; Poinssot, Christophe; Curtius, Hildegard; Bosbach, Dirk; Ewing, Rodney C.; Burns, Peter C.; Dacheux, Nicolas; Navrotsky, Alexandra

    2015-05-26

    Coffinite, USiO?, is an important U(IV) mineral, but its thermodynamic properties are not well-constrained. In this work, two different coffinite samples were synthesized under hydrothermal conditions and purified from a mixture of products. The enthalpy of formation was obtained by high temperature oxide melt solution calorimetry. Coffinite is energetically metastable with respect to a mixture of UO? (uraninite) and SiO? (quartz) by 25.6 3.9 kJ/mol. Its standard enthalpy of formation from the elements at 25 C is -1,970.0 4.2 kJ/mol. Decomposition of the two samples was characterized by X-ray diffraction and by thermogravimetry and differential scanning calorimetry coupled with mass spectrometric analysis of evolved gases. Coffinite slowly decomposes to U?O? and SiO? starting around 450 C in air and thus has poor thermal stability in the ambient environment. The energetic metastability explains why coffinite cannot be synthesized directly from uraninite and quartz but can be made by low temperature precipitation in aqueous and hydrothermal environments. These thermochemical constraints are in accord with observations of the occurrence of coffinite in nature and are relevant to spent nuclear fuel corrosion.

  1. Thermodynamics of formation of coffinite, USiO₄

    SciTech Connect

    Guo, Xiaofeng; Szenknect, Stéphanie; Mesbah, Adel; Labs, Sabrina; Clavier, Nicolas; Poinssot, Christophe; Curtius, Hildegard; Bosbach, Dirk; Ewing, Rodney C.; Burns, Peter C.; Dacheux, Nicolas; Navrotsky, Alexandra

    2015-05-26

    Coffinite, USiO₄, is an important U(IV) mineral, but its thermodynamic properties are not well-constrained. In this work, two different coffinite samples were synthesized under hydrothermal conditions and purified from a mixture of products. The enthalpy of formation was obtained by high temperature oxide melt solution calorimetry. Coffinite is energetically metastable with respect to a mixture of UO₂ (uraninite) and SiO₂ (quartz) by 25.6 ± 3.9 kJ/mol. Its standard enthalpy of formation from the elements at 25 °C is -1,970.0 ± 4.2 kJ/mol. Decomposition of the two samples was characterized by X-ray diffraction and by thermogravimetry and differential scanning calorimetry coupled with mass spectrometric analysis of evolved gases. Coffinite slowly decomposes to U₃O₈ and SiO₂ starting around 450 °C in air and thus has poor thermal stability in the ambient environment. The energetic metastability explains why coffinite cannot be synthesized directly from uraninite and quartz but can be made by low temperature precipitation in aqueous and hydrothermal environments. These thermochemical constraints are in accord with observations of the occurrence of coffinite in nature and are relevant to spent nuclear fuel corrosion.

  2. Ab initio metadynamics simulations of oxygen/ligand interactions in organoaluminum clusters

    SciTech Connect

    Alnemrat, Sufian; Hooper, Joseph P.

    2014-10-14

    Car-Parrinello molecular dynamics combined with a metadynamics algorithm is used to study the initial interaction of O{sub 2} with the low-valence organoaluminum clusters Al{sub 4}Cp{sub 4} (Cp=C{sub 5}H{sub 5}) and Al{sub 4}Cp{sub 4}{sup *} (Cp{sup *}=C{sub 5}[CH{sub 3}]{sub 5}). Prior to reaction with the aluminum core, simulations suggest that the oxygen undergoes a hindered crossing of the steric barrier presented by the outer ligand monolayer. A combination of two collective variables based on aluminum/oxygen distance and lateral oxygen displacement was found to produce distinct reactant, product, and transition states for this process. In the methylated cluster with Cp{sup *} ligands, a broad transition state of 45 kJ/mol was observed due to direct steric interactions with the ligand groups and considerable oxygen reorientation. In the non-methylated cluster the ligands distort away from the oxidizer, resulting in a barrier of roughly 34 kJ/mol with minimal O{sub 2} reorientation. A study of the oxygen/cluster system fixed in a triplet multiplicity suggests that the spin state does not affect the initial steric interaction with the ligands. The metadynamics approach appears to be a promising means of analyzing the initial steps of such oxidation reactions for ligand-protected clusters.

  3. Energetics of alkali and alkaline earth ion-exchanged zeolite A

    DOE PAGES [OSTI]

    Sun, Hui; Wu, Di; Liu, Kefeng; Guo, Xiaofeng; Navrotsky, Alexandra

    2016-06-30

    Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential (Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO2 (Mg-A). The formation enthalpies from oxides (25 °C) range from –93.71 ± 1.77 (K-A) to –48.02more » ± 1.85 kJ/mol per TO2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from –47.99 ± 1.20 (Ba-A) to –26.41 ± 1.71 kJ/mol per TO2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. As a result, the formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.« less

  4. THE THICKNESS DEPENDENCE OF OXYGEN PERMEABILITY IN SOL-GEL DERIVED CGO-COFE2O4 THIN FILMS ON POROUS CERAMIC SUBSTRATES: A SPUTTERED BLOCKING LAYER FOR THICKNESS CONTROL

    SciTech Connect

    Brinkman, K

    2009-01-08

    Mixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membrane is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce{sub 0.8}Gd{sub 0.2}O{sub 2-{delta}} (CGO)-CoFe{sub 2}O{sub 4} (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ {approx} 50 nm sputtered CeO{sub 2} layers on the surface of porous CGO ceramic substrates which serve as solution 'blocking' layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of {approx} 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03 {micro}mol/cm{sup 2} s) at 800 C as compared to 1mm thick bulk ceramic membranes (0.003 {micro}mol/cm{sup 2}).

  5. Fundamental studies in production of C{sub 2}-C{sub 4} hydrocarbons from coal. Final report, 1 September 1988--31 August 1992

    SciTech Connect

    Wiser, W.H.; Oblad, A.G.

    1993-03-01

    The following conclusions can be drawn from the result obtained in this kinetic study of single stage coal gasification to hydrocarbon (HC) gases high in C{sub 2}-C{sub 4} hydrocarbons. It was observed that the direct conversion of coal to HC gases involves two steps. The first step is thermal cleavage of the coal structure to produce liquids with small amounts of gases and coke. The second step is conversion of liquids to gases. Coal to liquids occurs very rapidly and was completed within 10 minutes. Liquids to gases is the rate-determining step of the overall process. The conversion of liquids to gases was observed to follow first order kinetics. The first order kinetics treatment of the data by isothermal approximation gave an apparent activation energy of approximately 23 kcal/mol. The first order kinetics treatment of the data by a more rigorous non-isothermal method gave an activation energy of 26 kcal/mol. The quantity of HC gases produced directly from coal reached a constant value of about l0% of the dmmf coal at a reaction time of 10 miutes. Most of the HC gases were produced from the liquids. The study of model compounds shows that conversion of liquids to HC gases.proceeds through a carbonium ion mechanism, and this accounts for the production of C{sub 2}-C{sub 4} gases. Liquid to gases occurs by a catalytic hydrocracking reaction.

  6. Fundamental studies in production of C[sub 2]-C[sub 4] hydrocarbons from coal

    SciTech Connect

    Wiser, W.H.; Oblad, A.G.

    1993-03-01

    The following conclusions can be drawn from the result obtained in this kinetic study of single stage coal gasification to hydrocarbon (HC) gases high in C[sub 2]-C[sub 4] hydrocarbons. It was observed that the direct conversion of coal to HC gases involves two steps. The first step is thermal cleavage of the coal structure to produce liquids with small amounts of gases and coke. The second step is conversion of liquids to gases. Coal to liquids occurs very rapidly and was completed within 10 minutes. Liquids to gases is the rate-determining step of the overall process. The conversion of liquids to gases was observed to follow first order kinetics. The first order kinetics treatment of the data by isothermal approximation gave an apparent activation energy of approximately 23 kcal/mol. The first order kinetics treatment of the data by a more rigorous non-isothermal method gave an activation energy of 26 kcal/mol. The quantity of HC gases produced directly from coal reached a constant value of about l0% of the dmmf coal at a reaction time of 10 miutes. Most of the HC gases were produced from the liquids. The study of model compounds shows that conversion of liquids to HC gases.proceeds through a carbonium ion mechanism, and this accounts for the production of C[sub 2]-C[sub 4] gases. Liquid to gases occurs by a catalytic hydrocracking reaction.

  7. On the competition between hydrogen abstraction versus C-O bond fission in initiating dimethyl ether combustion

    SciTech Connect

    Francisco, J.

    1999-07-01

    There has been a growing interest in the potential use of dimethyl ether (DME) as a diesel fuel in compression ignition engines. There are two initiation steps involved in the combustion of DME, one involving C-O bond fission and the other involving hydrogen abstraction by molecular oxygen. The kinetics and thermodynamics of C-O bond fission were explored computationally in a previous paper. The present paper addresses the competing process--hydrogen abstraction by molecular oxygen. Ab initio molecular orbital calculations are used to study the structures and energetics of the reactants, products, and the transition state for the CH{sub 3}OCH{sub 3} + O{sub 2} reaction. The calculations predict a barrier for hydrogen abstraction from CH{sub 3}OCH{sub 3} by O{sub 2} of 47.4 kcal/mol. This is lower than the barrier height for C-O bond fission previously calculated to be 81.1 kcal/mol. The results support values used in current models for the combustion of DME. Moreover, an examination of rates for C-O bond fission versus hydrogen abstraction by O{sub 2} suggests that the bimolecular process is the dominant pathway.

  8. Permeability of hydrogen isotopes through nickel-based alloys

    SciTech Connect

    Edge, E.M.; Mitchell, D.J.

    1983-04-01

    Permeabilities and diffusivities of deuterium in several nickel-based alloys were measured in this investigation. Measurements were made by the gas-phase breakthrough technique in the temperature range 200 to 450/sup 0/C with applied pressures ranging from 1 to 100 kPa. The results were extrapolated to predict the permeabilities (K) of the alloys at room temperature. The alloy with the smallest deuterium permeability is Carpenter 49, for which K = 4.3 x 10/sup -18/ mol s/sup -1/ m/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The permeability of deuterium in Kovar or Ceramvar is about 80% greater than that for Carpenter 49. Premeabilities of Inconel 625, Inconel 718, Inconel 750 and Monel K-500 are all equal to about 5 x 10/sup -17/ mol m/sup -1/ s/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The validity (from a statistical standpoint) of the extrapolation of the permeabilities to room temperature is considered in detail. Published permeabilities of stainless steels and nickel-iron alloys are also reviewed. The greatest differences in permeabilities among the nickel-based alloys appear to be associated with the tendency for some alloys to form protective oxide layers. Permeabilities of deuterium through laminates containing copper are smaller than for any of the iron-nickel alloys.

  9. Hydrogen ingress into copper-nickel alloys

    SciTech Connect

    Pound, B.G. . Materials Research Center)

    1994-04-01

    Hydrogen (H) ingress into two copper (Cu)-nickel (Ni) alloys -- a commercial 77% Cu-15% Ni alloy (aged) and alloy K-500 (UNS N05500, aged and unaged) --- was studied using a technique referred to as hydrogen ingress analysis by potentiostatic pulsing (HIAPP). Anodic current transients obtained for these alloys in an acetate buffer (1 mol/L acetic acid + 1 mol/L sodium acetate [NaAc]) were analyzed using a diffusion-trapping model to determine trapping constants and H entry fluxes. A small increase was observed in the irreversible trapping constant for alloy K-500 with aging. Trapping constants of the aged alloys were similar within the limits of uncertainty, but H entry flux for the 77% Cu alloy was lower than that for aged or unaged alloy K-500. The lower flux may have accounted at least partly, for the Cu alloy's higher resistance to H embrittlement. Trap densities were consistent qualitatively with levels of sulfur (S) and phosphorus (P) in the two alloys. This finding supported an assumption that S and P provided the primary irreversible traps.

  10. Theoretical Study of Trimethylacetic Acid Adsorption on CeO 2 (111) Surface

    DOE PAGES [OSTI]

    Wang, Weina; Thevuthasan, S.; Wang, Wenliang; Yang, Ping

    2016-01-11

    We investigated trimethylacetic acid (TMAA) adsorption on stoichiometric and oxygen-deficient CeO2(111) surfaces using density functional theory that accounts for the on-site Coulomb interaction via a Hubbard term (DFT+U) and long-range dispersion correction. Both the molecular state and dissociative state (TMAA → TMA– + H+) were identified on stoichiometric and oxygen-deficient CeO2(111) surfaces. For the stoichiometric surface, two thermodynamically favorable configurations with adsorption energies of the order of -30 kcal/mol are identified; one is a molecule adsorption state, and the other one is a dissociative state. For the oxygen-deficient surface, dissociative states are more favorable than molecular states. Moreover, the mostmore » favorable configuration is the dissociative adsorption of TMAA with the adsorption energy of the order of -77 kcal/mol. The dissociated TMA moiety takes the position of oxygen vacancy, forming three Ce–O bonds. The signature vibrational frequencies for these thermodynamically stable structures are reported as well as their electronic structures. The effects of long-range dispersion interactions are found to be negligible for geometries but important for adsorption energies.« less

  11. Effects of Amines on the Surface Charge Poperties of Iron Oxides.

    SciTech Connect

    Benezeth, Pascale; Wesolowski, David J; Palmer, Donald; Machesky, Michael L.

    2009-07-01

    Specific studies detailing the effects of amines, used as pH control agents for corrosion inhibition in power plants, on the surface charge of iron oxides provide data to assess the mechanism of how these amines impact deposition rate. The current study was undertaken in order to determine accurately the dissociation constants of the relevant amines at Pressurized Water Reactor (PWR) operating conditions and to investigate the effect of sorption of two of these amines (morpholine and dimethylamine) by magnetite. The acid-dissociation equilibria of morpholine (MOR), dimethylamine (DMA) and ethanolamine (ETA) were measured potentiometrically with a hydrogen-electrode concentration cell (HECC) from 0 to 290 C in sodium trifluoromethanesulfonate (NaTr) solutions at ionic strengths up to 1 mol {center_dot} kg{sup -1}. Magnetite surface titrations were performed at an ionic strength of 0.03 mol {center_dot} kg{sup -1} (NaTr medium) in the presence or absence of morpholine and dimethylamine buffers over a wide range of pH and total amine concentrations at 150-250 C.

  12. The solubility of zinc oxide in 0.03 m NaTr as a function of temperature, with in situ pH measurement

    SciTech Connect

    Benezeth, P.; Palmer, D.A.; Wesolowski, D.J.

    1999-05-01

    The solubility of zincite (ZnO) has been measured in noncomplexing solutions over a wide range of pH{sub m} (4--11), and temperature (75--200 C) at 0.03 mol/kg ionic strength in NaTr media (sodium trifluoromethanesulfonate, a noncomplexing 1:1 electrolyte), in a hydrogen electrode concentration cell (HECC), which provided continuous in situ measurement of hydrogen ion molality. Total zinc content was analyzed by atomic absorption using graphite furnace, flame, and inductively coupled plasma (ICP) spectrometers. The direction of approach to the equilibrium saturation state was varied to demonstrate that the system was reversible thermodynamically. Separate experiments were performed in alkaline solutions (0.03 mol/kg NaOH) at 25 and 50 C in polypropylene syringes, and between 50 and 290 C in a Teflon-lined pressure vessel. The aim of these experiments was to reach higher pH{sub m} (>8 depending on the temperature) to determine the thermodynamic properties of the negatively charged species, Zn(OH){sub 3}{sup {minus}}. A least-squares regression of the results obtained at this ionic strength was used to determine the molal solubility products (Q{sub sn}) of zincite. The solubility products (Q{sub sn}) were extrapolated to infinite dilution (K{sub sn}), permitting calculation of the thermodynamic properties of aqueous species of zinc for comparison with previous work.

  13. Kinetic and Thermodynamic Investigation of Hydrogen Release from Ethane 1,2-di-amineborane

    SciTech Connect

    Neiner, Doinita; Karkamkar, Abhijeet J.; Bowden, Mark; Choi, Young Joon; Luedtke, Avery T.; Holladay, Jamelyn D.; Fisher, Allison M.; Szymczak, Nathaniel; Autrey, Thomas

    2011-07-18

    The thermodynamics and kinetics of hydrogen (H2) release from ethane 1,2-di-amineborane (EDAB, BH3NH2CH2CH2NH2BH3) were measured using Calvet and differential scanning calorimetry (DSC), pressure-composition isotherms, and volumetric gas-burette experiments. The results presented here indicate that EDAB releases ~ 9 wt.% H2 at temperatures ranging from 100 C to 200 C in two moderately exothermic steps, approximately -101 kJ/mol H2 and -3.81 kJ/mol H2. Isothermal kinetic analysis shows that EDAB is more stable than ammonia borane (AB) at temperatures lower than 100C; however, the rates of hydrogen release are faster for EDAB than for AB at temperatures higher than 120C. In addition, no volatile impurities in the H2 released by EDAB were detected by mass spectrometry upon heating with 1C/min to 200C in a calorimeter.

  14. Commercial-scale demonstration of the Liquid Phase Methanol (LPMEOH{trademark}) Process. Peroxide formation of dimethyl ether in methanol mixtures

    SciTech Connect

    Waller, F.J.

    1997-11-01

    Organic peroxides could form when dimethyl ether in methanol is stored for three to six months at a time. The objective of this work was to determine the level of peroxide formation from dimethyl ether in reagent grade methanol and raw methanol at room temperature under 3 atmospheres (45 psig) of air. Raw methanol is methanol made from syngas by the LPMEOH Process without distillation. Aliphatic ethers tend to react slowly with oxygen from the air to form unstable peroxides. However, there are no reports on peroxide formation from dimethyl ether. After 172 days of testing, dimethyl ether in either reagent methanol or raw methanol at room temperature and under 60--70 psig pressure of air does not form detectable peroxides. Lack of detectable peroxides suggests that dimethyl ether or dimethyl ether and methanol may be stored at ambient conditions. Since the compositions of {approximately} 1.3 mol% or {approximately} 4.5 mol% dimethyl ether in methanol do not form peroxides, these compositions can be considered for diesel fuel or an atmospheric turbine fuel, respectively.

  15. Assessment of reduction behavior of hematite iron ore pellets in coal fines for application in sponge ironmaking

    SciTech Connect

    Kumar, M.; Patel, S.K.

    2009-07-01

    Studies on isothermal reduction kinetics (with F grade coal) in fired pellets of hematite iron ores, procured from four different mines of Orissa, were carried out in the temperature range of 850-1000C to provide information for the Indian sponge iron plants. The rate of reduction in all the fired iron ore pellets increased markedly with a rise of temperature up to 950C, and thereafter it decreased at 1000C. The rate was more intense in the first 30 minutes. All iron ores exhibited almost complete reduction in their pellets at temperatures of 900 and 950C in 2 hours' heating time duration, and the final product morphologies consisted of prominent cracks. The kinetic model equation 1-(1-a){sup 1/3}=kt was found to fit best to the experimental data, and the values of apparent activation energy were evaluated. Reductions of D. R. Pattnaik and M. G. Mohanty iron ore pellets were characterized by higher activation energies (183 and 150 kJ mol{sup -1}), indicating carbon gasification reaction to be the rate-controlling step. The results established lower values of activation energy (83 and 84 kJ mol{sup -1}) for the reduction of G. M. OMC Ltd. and Sakaruddin iron ore pellets, proposing their overall rates to be controlled by indirect reduction reactions.

  16. Fast crystallization of amorphous Gd{sub 2}Zr{sub 2}O{sub 7} induced by thermally activated electron-beam irradiation

    SciTech Connect

    Huang, Zhangyi; Qi, Jianqi Zhou, Li; Feng, Zhao; Yu, Xiaohe; Gong, Yichao; Yang, Mao; Wei, Nian; Shi, Qiwu; Lu, Tiecheng

    2015-12-07

    We investigate the ionization and displacement effects of an electron-beam (e-beam) on amorphous Gd{sub 2}Zr{sub 2}O{sub 7} synthesized by the co-precipitation and calcination methods. The as-received amorphous specimens were irradiated under electron beams at different energies (80 keV, 120 keV, and 2 MeV) and then characterized by X-ray diffraction and transmission electron microscopy. A metastable fluorite phase was observed in nanocrystalline Gd{sub 2}Zr{sub 2}O{sub 7} and is proposed to arise from the relatively lower surface and interface energy compared with the pyrochlore phase. Fast crystallization could be induced by 120 keV e-beam irradiation (beam current = 0.47 mA/cm{sup 2}). The crystallization occurred on the nanoscale upon ionization irradiation at 400 °C after a dose of less than 10{sup 17} electrons/cm{sup 2}. Under e-beam irradiation, the activation energy for the grain growth process was approximately 10 kJ/mol, but the activation energy was 135 kJ/mol by calcination in a furnace. The thermally activated ionization process was considered the fast crystallization mechanism.

  17. Kinetics of hydrogen isotope exchange in β-phase Pd-H-D

    SciTech Connect

    Luo, Weifang; Cowgill, Donald F.

    2015-07-22

    Hydrogen isotope gas exchange within palladium powders is examined using a batch-type reactor coupled to a residual gas analyzer (RGA). Furthermore, the exchange rates in both directions (H2 + PdD and D2 + PdH) are measured in the temperature range 178–323 K for the samples with different particle sizes. The results show this batch-type exchange is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An exchange rate constant of 1.40 ± 0.24 μmol H2/atm cm2 s is found for H2 + PdD at 298 K, 1.4 times higher than that for D2 + PdH, with an activation energy of 25.0 ± 3.2 kJ/mol H for both exchange directions. Finally, a comparison of exchange measurement techniques shows these coefficients, and the fundamental exchange probabilities are in good agreement with those obtained by NMR and flow techniques.

  18. Synthesis, characterization and optical properties of hybrid PVAZnO nanocomposite: A composition dependent study

    SciTech Connect

    Hemalatha, K.S. [Department of Physics, Bangalore University, Bangalore 560 056, Karnataka (India); Department of Physics, Maharani's Science College for Women, Palace Road, Bangalore 560 001, Karnataka (India); Rukmani, K., E-mail: rukmani9909@yahoo.co.in [Department of Physics, Bangalore University, Bangalore 560 056, Karnataka (India); Suriyamurthy, N. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, Karnataka (India)

    2014-03-01

    Graphical abstract: - Highlights: ZnO nanoparticles were prepared by solution combustion method. PVAZnO nanocomposites were synthesized by solution casting method. Doped and undoped films were characterized using different techniques. Red shift in optical band gap was observed in Nanocomposite films with respect to nano ZnO. Photoluminescence intensity was found to be optimum for PVA10 mol% ZnO nanocomposite film. - Abstract: Nanocomposites of poly vinyl alcohol (PVA) and ZnO have been synthesized using the solution casting technique for different concentrations of nano ZnO powder prepared by low temperature solution combustion method. The formation of polymer nanocomposite and changes in the structural and micro structural properties of the materials were investigated by X-ray diffraction, Energy dispersive X ray spectroscopy and optical microscopy techniques (FTIR and UVVisible). The surface morphology of PVAZnO nanocomposite films were elucidated using Scanning Electron Microscopy. The optical absorption spectrum of nano ZnO shows blue shift in the optical band gap energy with respect to characteristic bulk ZnO at room temperature, whereas PVAZnO hybrid films show red shift with respect to nano ZnO. The photoluminescence studies show that the intensity of the blue emission (470 nm) varies with change in concentration of ZnO with an optimum intensity observed at 10 mol% of ZnO.

  19. Ultra-low-temperature reactions of C({sup 3}P{sub 0}) atoms with benzene molecules in helium droplets

    SciTech Connect

    Krasnokutski, Serge A. Huisken, Friedrich

    2014-12-07

    The reaction of carbon atoms with benzene has been investigated in liquid helium droplets at T = 0.37 K. We found an addition of the carbon atom to form an initial intermediate complex followed by a ring opening and the formation of a seven-membered ring. In contrast to a previous gas phase study, the reaction is frozen after these steps and the loss of hydrogen does not occur. A calorimetric technique was applied to monitor the energy balance of the reaction. It was found that more than 267 kJ mol{sup ?1} were released in this reaction. This estimation is in line with quantum chemical calculations of the formation energy of a seven-membered carbon ring. It is suggested that reactions of this kind could be responsible for the low abundance of small polycyclic aromatic hydrocarbon molecules in the interstellar medium. We also found the formation of weakly bonded water-carbon adducts, in which the carbon atom is linked to the oxygen atom of the water molecule with a binding energy of about 33.4 kJ mol{sup ?1}.

  20. Density functional and neutron diffraction studies of lithium polymer electrolytes.

    SciTech Connect

    Baboul, A. G.

    1998-06-26

    The structure of PEO doped with lithium perchlorate has been determined using neutron diffraction on protonated and deuterated samples. The experiments were done in the liquid state. Preliminary analysis indicates the Li-O distance is about 2.0 {angstrom}. The geometries of a series of gas phase lithium salts [LiCF{sub 3}SO{sub 3}, Li(CF{sub 3}SO{sub 2}){sub 2}N, Li(CF{sub 3}SO{sub 2}){sub 2}CH, LiClO{sub 4}, LiPF{sub 6}, LiAsF{sub 6}] used in polymer electrolytes have been optimized at B3LYP/6-31G(d) density functional level of theory. All local minima have been identified. For the triflate, imide, methanide, and perchlorate anions, the lithium cation is coordinated to two oxygens and have binding energies of ca 141 kcal/mol at the B3LYP/6-311+G(3df,2p)/B3LYP/6-31G* level of theory. For the hexafluoroarsenate and hexafluorophosphate the lithium cation is coordinated to three oxygens and have binding energies of ca. 136 kcal/mol.

  1. Optimizing white light luminescence in Dy{sup 3+}-doped Lu{sub 3}Ga{sub 5}O{sub 12} nano-garnets

    SciTech Connect

    Haritha, P.; Linganna, K.; Venkatramu, V.; Martn, I. R.; Monteseguro, V.; Rodrguez-Mendoza, U. R.; Babu, P.; Len-Luis, S. F.; Jayasankar, C. K.; Lavn, V.

    2014-11-07

    Trivalent dysprosium-doped Lu{sub 3}Ga{sub 5}O{sub 12} nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457?nm laser excitation, the white luminescence properties of Lu{sub 3}Ga{sub 5}O{sub 12} nano-garnets have been studied as a function of the optically active Dy{sup 3+} ion concentration and at low temperature. Decay curves for the {sup 4}F{sub 9/2} level of Dy{sup 3+} ion exhibit non-exponential nature for all the Dy{sup 3+} concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy{sup 3+} ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8?mol% Dy{sup 3+} ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy{sup 3+} concentrations. These results indicate that 2.0?mol% Dy{sup 3+} ions doped nano-garnet could be useful for white light emitting device applications.

  2. Growth of Ammonium Bisulfate Clusters by Adsorption of Oxygenated Organic Molecules

    DOE PAGES [OSTI]

    DePalma, Joseph W.; Wang, Jian; Wexler, Anthony S.; Johnston, Murray V.

    2015-10-21

    Quantum chemical calculations were employed to model the interactions of the [(NH4+)4(HSO4-)4] ammonium bisulfate cluster with one or more molecular products of monoterpene oxidation. A strong interaction was found between the bisulfate ion of the cluster and a carboxylic acid, aldehyde or ketone functionality of the organic molecule. Free energies of adsorption for carboxylic acids were in the -70 to -73 kJ/mol range, while those for aldehydes and ketones were in the -46 to -50 kJ/mol range. These values suggest that a small ambient ammonium bisulfate cluster, such as the [(NH4+)4(SO4-)4] cluster, is able to adsorb an oxygenated organic molecule.more » Although adsorption of the first molecule is highly favorable, adsorption of subsequent molecules is not, suggesting that sustained uptake of organic molecules does not occur, and thus is not a pathway for continuing growth of the cluster. This result is consistent with ambient measurements showing that particles below ~1 nm grow slowly, while those above 1 nm grow at an increasing rate presumably due to a lower surface energy barrier enabling the uptake of organic molecules. This work provides insight into the molecular level interactions which affect sustained cluster growth by uptake of organic molecules.« less

  3. Equations of state of ice VI and ice VII at high pressure and high temperature

    SciTech Connect

    Bezacier, Lucile; Hanfland, Michael; Journaux, Baptiste; Perrillat, Jean-Philippe; Cardon, Herv; Daniel, Isabelle

    2014-09-14

    High-pressure H{sub 2}O polymorphs among which ice VI and ice VII are abundant in the interiors of large icy satellites and exo-planets. Knowledge of the elastic properties of these pure H{sub 2}O ices at high-temperature and high-pressure is thus crucial to decipher the internal structure of icy bodies. In this study we assess for the first time the pressure-volume-temperature (PVT) relations of both polycrystalline pure ice VI and ice VII at high pressures and temperatures from 1 to 9 GPa and 300 to 450 K, respectively, by using in situ synchrotron X-ray diffraction. The PVT data are adjusted to a second-order Birch-Murnaghan equation of state and give V{sub 0} = 14.17(2) cm{sup 3}?mol{sup ?1}, K{sub 0} = 14.05(23) GPa, and ?{sub 0} = 14.6(14) 10{sup ?5} K{sup ?1} for ice VI and V{sub 0} = 12.49(1) cm{sup 3}?mol{sup ?1}, K{sub 0} = 20.15(16) GPa, and ?{sub 0} = 11.6(5) 10{sup ?5} K{sup ?1} for ice VII.

  4. Effects of relativity for atomization and isomerization energies of seaborgium carbonyl SgCO and seaborgium isocarbonyl SgOC: Relativity predicts SgOC to be more stable than SgCO

    SciTech Connect

    Malli, Gulzari L.

    2015-12-15

    Our ab initio all-electron fully relativistic Dirac-Fock (DF) and nonrelativistic Hartree-Fock (NR) calculations for seaborgium isocarbonyl SgOC predict atomization energy (AE) of 13.04 and 11.05 eV, respectively. However, the corresponding DF and NR atomization energies for the seaborgium carbonyl SgCO are predicted as 12.75 and 12.45 eV, respectively. This is the first such result in Chemistry where an isocarbonyl (and especially for a system of superheavy element Sg) is predicted to be more stable at the DF level of theory than the corresponding carbonyl. The predicted energy for the formation of the carbonyl SgCO at the relativistic DF and NR levels of theory is -54.90 and -50.95 kJ /mol, whereas the corresponding energy of formation of the isocarbonyl SgOC is -64.44 and -18.64 kJ/mol, respectively. Ours are the first results of relativistic effects for isomerization and atomization energies of the superheavy seaborgium isocarbonyl SgOC and its isomer SgCO.The formation of isocarbonyl SgOC, should be favored over the carbonyl isomer SgCO in the first step of the reaction Sg+CO →SgOC.

  5. Development and field testing of a rapid and ultra-stable atmospheric carbon dioxide spectrometer

    DOE PAGES [OSTI]

    Xiang, B.; Nelson, D. D.; McManus, J. B.; Zahniser, M. S.; Wehr, R. A.; Wofsy, S. C.

    2014-12-15

    We present field test results for a new spectroscopic instrument to measure atmospheric carbon dioxide (CO2) with high precision (0.02 μmol mol-1, or ppm at 1 Hz) and demonstrate high stability (within 0.1 ppm over more than 8 months), without the need for hourly, daily, or even monthly calibration against high-pressure gas cylinders. The technical novelty of this instrument (ABsolute Carbon dioxide, ABC) is the spectral null method using an internal quartz reference cell with known CO2 column density. Compared to a previously described prototype, the field instrument has better stability and benefits from more precise thermal control of themore » optics and more accurate pressure measurements in the sample cell (at the mTorr level). The instrument has been deployed at a long-term ecological research site (the Harvard Forest, USA), where it has measured for 8 months without on-site calibration and with minimal maintenance, showing drift bounds of less than 0.1 ppm. Field measurements agree well with those of a commercially available cavity ring-down CO2 instrument (Picarro G2301) run with a standard calibration protocol. This field test demonstrates that ABC is capable of performing high-accuracy, unattended, continuous field measurements with minimal use of reference gas cylinders.« less

  6. Formation of Aqueous MgUO2(CO3)32- Complex and Uranium Anion Exchange Mechanism onto an Exchange Resin

    SciTech Connect

    Dong, Wenming; Brooks, Scott C

    2008-01-01

    The formation of and stability constants for aqueous Mg-UO2-CO3 complexes were determined using an anion exchange method. Magnesium concentration was varied (up to 20 mmol/L) at constant ionic strength (I = 0.101, 0.202, 0.304, 0.406, and 0.509 mol/kg NaNO3), pH = 8.1, total [U(VI)] = 10.4 mol/L under equilibrium with atmospheric CO2. The results indicate that only the MgUO2(CO3)32- complex is formed. The cumulative formation constant extrapolated to zero ionic strength is similar regardless of the activity correction convention used: log = 25.8 b 0.5 using Davies equation and = 25.02 b 0.08 using specific ion interaction theory (SIT). Uranium sorption onto the exchange resin decreased in the presence of Mg putatively due to the formation of MgUO2(CO3)32- that had a lower affinity for the resin than UO2(CO3)34-. Uranium sorption results are consistent with an equivalent anion exchange reaction between NO3- and UO2(CO3)34- species to retain charge neutrality regardless of Mg concentration. No Mg was associated with the anion exchange resin indicating that the MgUO2(CO3)32- complex did not sorb.

  7. Ethylenediamine salt of 5-nitrotetrazole and preparation

    DOEpatents

    Lee, Kien-yin; Coburn, Michael D.

    1985-01-01

    Ethylenediamine salt of 5-nitrotetrazole and preparation. This salt has been found to be useful as an explosive alone and in eutectic mixtures with ammonium nitrate and/or other explosive compounds. Its eutectic with ammonium nitrate has been demonstrated to behave in a similar manner to a monomolecular explosive such as TNT, and is less sensitive than the pure salt. Moreover, this eutectic mixture, which contains 87.8 mol % of ammonium nitrate, is close to the CO.sub.2 -balanced composition of 90 mol %, and has a relatively low melting point of 110.5 C. making it readily castable. The ternary eutectic system containing the ethylenediamine salt of 5-nitrotetrazole, ammonium nitrate and ethylenediamine dinitrate has a eutectic temperature of 89.5 C. and gives a measured detonation pressure of 24.8 GPa, which is 97.6% of the calculated value. Both the pure ethylenediamine salt and its known eutectic compounds behave in substantially ideal manner. Methods for the preparation of the salt are described.

  8. Evaluation of Synroc-C as a second-generation waste form

    SciTech Connect

    Shade, J.W.

    1986-08-01

    The durability of a crystalline titanate waste form, Synroc-C, was evaluated as a second-generation waste form by leach testing. Tests using both monolith and high surface area powdered samples were used with silicate water and brines at 90/sup 0/C and 150/sup 0/C for up to 90 days. In addition, low surface area-to-volume ratio, 1-day leach tests were conducted between 90/sup 0/C and 250/sup 0/C to determine forward-direction leach rates and activation energies. Dissolution rates of Cs, Mo, Ba, and U indicated that Synroc-C generally performed about an order of magntidue better than uranium-doped 76-68 glass. The release of Cs and Mo from Synroc-C, at least initially, may be primarily from intergranular regions of the material. The activation energy for the release of these elements from glass was about 9 kcal/mol but less than 3 kcal/mol for Synroc-C. In long-term tests, uranium dissolution may be controlled more by the formation of uranium alteration products than by release from the waste form.

  9. Interplay of confinement and surface energetics in the interaction of water with a metal–organic framework

    DOE PAGES [OSTI]

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2016-03-24

    Here, the enthalpy of water adsorption (Δh) on the metal–organic framework (MOF) HKUST-1 has been determined directly by calorimetry. The most exothermic value of Δh [–119.4 ± 0.5 kJ/(mol of water)] occurs at zero coverage and perhaps represents water confinement in the smallest (4-Å) cages. An intermediate Δh value of –50.2 ± 1.8 kJ/(mol of water) at higher loading probably corresponds to the binding of water on the available Cu nodes and subsequent filling of the largest (11-Å) pores. The weakest interactions take place in the medium (10-Å) cages, showing weak inclusion of water clusters in a limited hydrophobic environment.more » By combining ethanol adsorption calorimetry, mathematical analysis of the slope of the water adsorption isotherm, and the differential enthalpy of water adsorption curve, we are able not only to develop an approach to separate energetically multistage guest–host interactions in complex MOF architectures but also to distinguish a sequence of interactions with very similar energetic effects.« less

  10. Modifications under irradiation of a self-assembled monolayer grafted on a nano-porous silica glass: a solid-state NMR characterization

    SciTech Connect

    Le Caer, S.; Chatelain, C.; Renault, J.Ph.; Brunet, F.; Charpentier, T.; Durand, D.; Dauvois, V.

    2012-02-15

    Controlled pore glasses with a pore size of 8 nm are grafted with chlorodimethylsilane (ClSi(CH{sub 3}){sub 2}H). The surface of the glass is carefully characterized before and after irradiation with 10 MeV electrons by solid-state NMR measurements. {sup 1}H MAS NMR experiments in one and two dimensions (2D double quantum and 2D exchange) have been used to reveal the grafting of the chlorodimethylsilane at the silica surface and evidence the formation of a homogeneous layer on the surface. Irradiation leads to a high H{sub 2} yield (3.3 * 10{sup -7} mol/J) due to the efficient cleavage of the Si H bond. Methane is detected in smaller quantities (5.5 * 10{sup -8} mol/J), indicating that the Si-H bond is preferentially cleaved over the Si-C bond. The H{sub 2} production arising from OH groups on the surface is very minor in comparison to the S- H and Si-C radiolysis. (authors)

  11. Molecular basis of endosomal-membrane association for the dengue virus envelope protein

    SciTech Connect

    Rogers, David M.; Kent, Michael S.; Rempe, Susan B.

    2015-01-02

    Dengue virus is coated by an icosahedral shell of 90 envelope protein dimers that convert to trimers at low pH and promote fusion of its membrane with the membrane of the host endosome. We provide the first estimates for the free energy barrier and minimum for two key steps in this process: host membrane bending and protein–membrane binding. Both are studied using complementary membrane elastic, continuum electrostatics and all-atom molecular dynamics simulations. The predicted host membrane bending required to form an initial fusion stalk presents a 22–30 kcal/mol free energy barrier according to a constrained membrane elastic model. Combined continuum and molecular dynamics results predict a 15 kcal/mol free energy decrease on binding of each trimer of dengue envelope protein to a membrane with 30% anionic phosphatidylglycerol lipid. The bending cost depends on the preferred curvature of the lipids composing the host membrane leaflets, while the free energy gained for protein binding depends on the surface charge density of the host membrane. The fusion loop of the envelope protein inserts exactly at the level of the interface between the membrane's hydrophobic and head-group regions. As a result, the methods used in this work provide a means for further characterization of the structures and free energies of protein-assisted membrane fusion.

  12. Theoretical analysis of co-solvent effect on the proton transfer reaction of glycine in a water–acetonitrile mixture

    SciTech Connect

    Kasai, Yukako; Yoshida, Norio Nakano, Haruyuki

    2015-05-28

    The co-solvent effect on the proton transfer reaction of glycine in a water–acetonitrile mixture was examined using the reference interaction-site model self-consistent field theory. The free energy profiles of the proton transfer reaction of glycine between the carboxyl oxygen and amino nitrogen were computed in a water–acetonitrile mixture solvent at various molar fractions. Two types of reactions, the intramolecular proton transfer and water-mediated proton transfer, were considered. In both types of the reactions, a similar tendency was observed. In the pure water solvent, the zwitterionic form, where the carboxyl oxygen is deprotonated while the amino nitrogen is protonated, is more stable than the neutral form. The reaction free energy is −10.6 kcal mol{sup −1}. On the other hand, in the pure acetonitrile solvent, glycine takes only the neutral form. The reaction free energy from the neutral to zwitterionic form gradually increases with increasing acetonitrile concentration, and in an equally mixed solvent, the zwitterionic and neutral forms are almost isoenergetic, with a difference of only 0.3 kcal mol{sup −1}. The free energy component analysis based on the thermodynamic cycle of the reaction also revealed that the free energy change of the neutral form is insensitive to the change of solvent environment but the zwitterionic form shows drastic changes. In particular, the excess chemical potential, one of the components of the solvation free energy, is dominant and contributes to the stabilization of the zwitterionic form.

  13. Incorporation of chromium into TiO{sub 2} nanopowders

    SciTech Connect

    Kollbek, Kamila; Sikora, Marcin; Kapusta, Czesław; Szlachetko, Jakub; Radecka, Marta; Lyson-Sypien, Barbara; Zakrzewska, Katarzyna

    2015-04-15

    Highlights: • Nanopowders of TiO{sub 2}:Cr with different amount of Cr dopant were obtained by flame spray synthesis, FSS. • Increase in the optical absorption and a shift of the absorption edge were observed upon Cr doping. • HERFD-XANES measurements indicated that the average valence state of titanium ions was preserved. • Increasing magnetic susceptibility of a paramagnetic character was observed upon Cr doping. - Abstract: The paper reports on the results of a study of optical, electronic and magnetic properties of TiO{sub 2} nanopowders doped with Cr ions. Diffused reflectance spectra reveal an increase in the optical absorption and a shift of the absorption edge towards lower energies upon Cr doping. Direct information on the Ti electronic state and the symmetry of its nearest environment is obtained from XANES Ti K-edge spectra. Magnetic behaviour is probed by means of the temperature dependence of DC magnetic susceptibility. Increasing magnetic susceptibility of a paramagnetic character is observed upon increasing chromium doping. The Curie constant of TiO{sub 2}:10 at.% Cr sample (0.12 emu K/mol Oe) is lower than that expected for Cr{sup 3+} (0.1875 emu K/mol Oe) possibly due to the appearance of Cr{sup 4+} or the presence of the orbital contribution to the magnetic moment.

  14. Ab Initio Study of the Wolff Rearrangement of C6H40 Intermediate in the Gas Phase

    SciTech Connect

    Borisov, Yurii A.; Garrett, Bruce C.; Feller, David F.

    1999-09-30

    Ab initio calculations of the geometry and reactivity of 1,2-ketocarbene C6H4O as an intermediate in organic reactions were performed using the second-order Møller-Plesset (MP2) perturbation theory in the 6-311G* basis set. Only the singlet state of the intermediate was considered. An oxirene-like structure (6) with a six-membered ring and a ketene-like structure (5) with a five-membered ring were localized on the potential energy surface. Attempts to locate a quinone type structure characteristic of aliphatic ketocarbenes failed. The energy of structure5 is -70 kcal mol-1 lower than that of structure 6. Harmonic frequencies and intensities of normal vibrations in the IR spectra of6 and5 were calculated. The activation energy of the Wolff rearrangement 6→5 was estimated at 12.5 kcal mol-1. The geometry of the transition state of this reaction resembles the quinone-like structure.

  15. Formation of the diphenyl molecule in the crossed beam reaction of phenyl radicals with benzene

    SciTech Connect

    Zhang Fangtong; Gu Xibin; Kaiser, Ralf I.

    2008-02-28

    The chemical dynamics to form the D5-diphenyl molecule, C{sub 6}H{sub 5}C{sub 6}D{sub 5}, via the neutral-neutral reaction of phenyl radicals (C{sub 6}H{sub 5}) with D6-benzene (C{sub 6}D{sub 6}), was investigated in a crossed molecular beams experiment at a collision energy of 185 kJ mol{sup -1}. The laboratory angular distribution and time-of-flight spectra of the C{sub 6}H{sub 5}C{sub 6}D{sub 5} product were recorded at mass to charge m/z of 159. Forward-convolution fitting of our data reveals that the reaction dynamics are governed by an initial addition of the phenyl radical to the {pi} electron density of the D6-benzene molecule yielding a short-lived C{sub 6}H{sub 5}C{sub 6}D{sub 6} collision complex. The latter undergoes atomic deuterium elimination via a tight exit transition state located about 30 kJ mol{sup -1} above the separated reactants; the overall reaction to form D5-diphenyl from phenyl and D6-benzene was found to be weakly exoergic. The explicit identification of the D5-biphenyl molecules suggests that in high temperature combustion flames, a diphenyl molecule can be formed via a single collision event between a phenyl radical and a benzene molecule.

  16. PROTON-CONDUCTING DENSE CERAMIC MEMBRANES FOR HYDROGEN SEPARATION

    SciTech Connect

    Jerry Y. S. Lin; Scott Cheng; Vineet Gupta

    2003-12-01

    Dense perovskite-type structured ceramic membranes, SrCe{sub 0.95}Tm{sub 0.05}O{sub 3} (SCTm), of different thickness, were prepared by the dry-press method. Membrane thickness was varied from 3 mm to 150 {micro}m. The hydrogen permeation flux was found to be inversely proportional to the thickness of the dense films, indicating that the bulk diffusion rather than the surface reaction played a dominant role in the H{sub 2} transport through these dense membranes within the studied thickness range. Hydrogen permeation flux increases with increasing upstream hydrogen partial pressure and decreasing downstream hydrogen partial pressure. The activation energy for hydrogen permeation through the SCTm membrane is about 116 kJ/mol in 600-700 C and 16 kJ/mol in 750-950 C. This indicates a change in the electrical and protonic conduction mechanism at around 700 C. Pd-Cu thin films were synthesized with elemental palladium and copper targets by the sequential R.F. sputter deposition on porous substrates. Pd-Cu alloy films could be formed after proper annealing. The deposited Pd-Cu films were gas-tight. This result demonstrated the feasibility of obtaining an ultrathin SCTm film by the sequential sputter deposition of Sr, Ce and Tm metals followed by proper annealing and oxidation. Such ultrathin SCTm membranes will offer sufficiently high hydrogen permeance for practical applications.

  17. Interaction of alkanes with unsaturated metal centers. 2. Complexes of alkanes and fluoroalkanes with W(CO) sub 5 in the gas phase

    SciTech Connect

    Brown, C.E.; Ishikawa, Yoichi; Hackett, P.A.; Rayner, D.M. )

    1990-03-28

    Time-resolved infrared spectroscopy has been used to study the interaction of a range of open-chain, cyclic, and fluorine-substituted alkanes with the 16-electron species W(CO){sub 5}. W(CO){sub 5} forms reversible complexes with all the unsubstituted alkanes studied except CH{sub 4}. The equilibrium constant K{sub p} = (W(CO){sub 5}L)/((W(CO){sub 5})p(L)), at 300 K, increases with carbon number from 610 {plus minus} 100 atm{sup {minus}1} in cyclohexane. binding energies have also been obtained through temperature studies. They are in the range 7-11 kcal mol{sup {minus}1}, again increasing with the size of the alkanes. In the case of CH{sub 4}, a binding energy K5 kcal mol{sup {minus}1} is implied by their inability to observe a complex. Correlation of the binding energies with C-H {sigma} MO stabilization energies is consistent with a simple molecular orbital picture involving formation of a 2-electron, 3-center C-H-M bond through {sigma} {yields} M electron donation.

  18. The Stress Corrosion Crack Growth Rate of Alloy 600 Heat Affected Zones Exposed to High Purity Water

    SciTech Connect

    George A. Young; Nathan Lewis

    2003-04-05

    Grain boundary chromium carbides improve the resistance of nickel based alloys to primary water stress corrosion cracking (PWSCC). However, in weld heat affected zones (HAZ's), thermal cycles from fusion welding can solutionize beneficial grain boundary carbides, produce locally high residual stresses and strains, and promote PWSCC. The present research investigates the crack growth rate of an A600 HAZ as a function of test temperature. The A600 HAZ was fabricated by building up a gas-tungsten-arc-weld deposit of EN82H filler metal onto a mill-annealed A600 plate. Fracture mechanics based, stress corrosion crack growth rate testing was performed in high purity water between 600 F and 680 F at an initial stress intensity factor of 40 ksi {radical}in and at a constant electrochemical potential. The HAZ samples exhibited significant SCC, entirely within the HAZ at all temperatures tested. While the HAZ samples showed the same temperature dependence for SCC as the base material (HAZ: 29.8 {+-} 11.2{sub 95%} kcal/mol vs A600 Base: 35.3 {+-} 2.58{sub 95%} kcal/mol), the crack growth rates were {approx} 30X faster than the A600 base material tested at the same conditions. The increased crack growth rates of the HAZ is attributed to fewer intergranular chromium rich carbides and to increased plastic strain in the HAZ as compared to the unaffected base material.

  19. Ethylenediamine salt of 5-nitrotetrazole and preparation

    DOEpatents

    Lee, K.; Coburn, M.D.

    1984-05-17

    The ethylenediamine salt of 5-nitrotetrazole has been found to be useful as an explosive alone and in eutectic mixtures with ammonium nitrate and/or other explosive compounds. Its eutectic with ammonium nitrate has been demonstrated to behave in a similar manner to a monomolecular explosive such as TNT, and is less sensitive than the pure salt. Moreover, this eutectic mixture, which contains 87.8 mol% of ammonium nitrate, is close to the CO/sub 2/-balanced composition of 90 mol%, and has a relatively low melting point of 110.5 C making it readily castable. The ternary eutectic system containing the ethylenediamine salt of 5-nitrotetrazole, ammonium nitrate and ethylenediamine dinitrate has a eutectic temperature of 89.5 C and gives a measured detonation pressure of 24.8 GPa, which is 97.6% of the calculated value. Both the pure ethylenediamine salt and its known eutectic compounds behave in substantially ideal manner. Methods for the preparation of the salt are described.

  20. Spontaneous combustion prediction of coal by C80 and ARC techniques

    SciTech Connect

    Qingsong Wang; Song Guo; Jinhua Sun

    2009-09-15

    Many coal fires were caused by spontaneous combustion in coal mines or coal storehouses, which resulted in a great loss and energy wastage. To identify and evaluate the hazardous degree of coal stockpile, a C80 microcalorimeter and accelerating rate calorimeter (ARC) were employed in this work. The coal samples undergo an exothermal process start at 80 {sup o}C with heat generation of -75.1 J g{sup -1} (mean value) detected by C80 experiment. The activation energies of the first exothermal process were calculated for the three experiments, and the mean value is 80.76 kJ mol{sup -1}, which is lower than that of obtained from the ARC result, 127.0 kJ mol{sup -1}. For a 300 tons coal stockpile, the self-heating oxidation temperatures (SHOT) were calculated as 164, 60, 90, and 68{sup o}C based on the ARC experiment and three C80 experiments, respectively. Further research on the mass effect on SHOT shows that if the coal mass is less than 12 tons, the danger of thermal spontaneous combustion is less. However, if the mass amount is more than 12000 tons, the danger of thermal spontaneous combustion is difficult to avoid even at ambient temperature if no special measures are taken. 38 refs., 9 figs.

  1. Characterization of tungsten films and their hydrogen permeability

    SciTech Connect

    Nemani?, Vincenc Kova?, Janez; Lungu, Cristian; Porosnicu, Corneliu; Zajec, Bojan

    2014-11-01

    Prediction of tritium migration and its retention within fusion reactors is uncertain due to a significant role of the structural disorder that is formed on the surface layer after plasma exposure. Tungsten films deposited by any of the suitable methods are always disordered and contain a high density of hydrogen traps. Experiments on such films with hydrogen isotopes present a suitable complementary method, which improves the picture of the hydrogen interaction with fusion relevant materials. The authors report on the morphology, composition, and structure of tungsten films deposited by the thermionic vacuum arc method on highly permeable Eurofer substrates. Subsequently, hydrogen permeation studies through these films were carried out in a wide pressure range from 20 to 1000 mbars at 400?C. The final value of the permeation coefficient for four samples after 24?h at 400?C was between P?=?3.2??10{sup ?14}?mol?H{sub 2}/(m?s?Pa{sup 0.5}) and P?=?1.1??10{sup ?15}?mol H{sub 2}/(m s Pa{sup 0.5}). From the time evolution of the permeation flux, it was shown that diffusivity was responsible for the difference in the steady fluxes, as solubility was roughly the same. This is confirmed by XRD data taken on these samples.

  2. Kinetics of hydrogen isotope exchange in β-phase Pd-H-D

    DOE PAGES [OSTI]

    Luo, Weifang; Cowgill, Donald F.

    2015-07-22

    Hydrogen isotope gas exchange within palladium powders is examined using a batch-type reactor coupled to a residual gas analyzer (RGA). Furthermore, the exchange rates in both directions (H2 + PdD and D2 + PdH) are measured in the temperature range 178–323 K for the samples with different particle sizes. The results show this batch-type exchange is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An exchange rate constant of 1.40 ± 0.24 μmol H2/atm cm2 s is found for H2 + PdD at 298 K, 1.4 times highermore » than that for D2 + PdH, with an activation energy of 25.0 ± 3.2 kJ/mol H for both exchange directions. Finally, a comparison of exchange measurement techniques shows these coefficients, and the fundamental exchange probabilities are in good agreement with those obtained by NMR and flow techniques.« less

  3. Hydrogen isotope trapping in Al-Cu binary alloys

    DOE PAGES [OSTI]

    Chao, Paul; Karnesky, Richard A.

    2016-01-01

    In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol–1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high;more » for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15×10–7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.« less

  4. Free radical hydrogen atom abstraction from saturated hydrocarbons: A crossed-molecular-beams study of the reaction Cl + C{sub 3}H{sub 8} {yields} HCl + C{sub 3}H{sub 7}

    SciTech Connect

    Blank, D.A.; Hemmi, N.; Suits, A.G.; Lee, Y.T.

    1997-04-01

    The abstraction of hydrogen atoms from saturated hydrocarbons are reactions of fundamental importance in combustion as well as often being the rate limiting step in free radical substitution reactions. The authors have begun studying these reactions under single collision conditions using the crossed molecular beam technique on beamline 9.0.2.1, utilizing VUV undulator radiation to selectively ionize the scattered hydrocarbon free radical products (C{sub x}H{sub 2x+1}). The crossed molecular beam technique involves two reactant molecular beams fixed at 90{degrees}. The molecular beam sources are rotatable in the plane defined by the two beams. The scattered neutral products travel 12.0 cm where they are photoionized using the VUV undulator radiation, mass selected, and counted as a function of time. In the authors initial investigations they are using halogen atoms as protypical free radicals to abstract hydrogen atoms from small alkanes. Their first study has been looking at the reaction of Cl + propane {r_arrow} HCl + propyl radical. In their preliminary efforts the authors have measured the laboratory scattering angular distribution and time of flight spectra for the propyl radical products at collision energies of 9.6 kcal/mol and 14.9 kcal/mol.

  5. Effects of Compaction and Temperature on Sorption and Diffusion of Cs and HTO in Compacted Bentonite Saturated with Saline Water

    SciTech Connect

    Satoru Suzuki; Masashi Haginuma; Kazunori Suzuki

    2007-07-01

    The sorption and diffusion of Cs and tritiated water (HTO) in compacted bentonite was investigated at temperatures from 30 to 60 deg. C. The apparent (D{sub a}) and effective (D{sub e}) diffusion coefficients were determined by in-diffusion and through-diffusion experiments with a constant boundary concentration maintained. The temperature dependence of De and Da obeyed an Arrhenius-type equation, allowing determination of the activation energy for diffusion of Cs and HTO. The D{sub e} value of Cs was three times the D{sub e} of HTO, which is considered to be a result of surface-excess diffusion. Cs may be concentrated near the surface of the negatively charged clay, thus giving a large diffusive flux. The activation energies for Cs diffusion were 21.4{+-}2.8 kJ/mol and 37.3{+-}1.5 kJ/mol as determined based on D{sub e} and D{sub a}, respectively. This difference was due to the temperature dependence of the distribution coefficient K{sub d} of Cs. (authors)

  6. Molecular metal-Oxo catalysts for generating hydrogen from water

    DOEpatents

    Long, Jeffrey R; Chang, Christopher J; Karunadasa, Hemamala I

    2015-02-24

    A composition of matter suitable for the generation of hydrogen from water is described, the positively charged cation of the composition having the general formula [(PY5W.sub.2)MO].sup.2+, wherein PY5W.sub.2 is (NC.sub.5XYZ)(NC.sub.5H.sub.4).sub.4C.sub.2W.sub.2, M is a transition metal, and W, X, Y, and Z can be H, R, a halide, CF.sub.3, or SiR.sub.3, where R can be an alkyl or aryl group. The two accompanying counter anions, in one embodiment, can be selected from the following Cl.sup.-, I.sup.-, PF.sub.6.sup.-, and CF.sub.3SO.sub.3.sup.-. In embodiments of the invention, water, such as tap water containing electrolyte or straight sea water can be subject to an electric potential of between 1.0 V and 1.4 V relative to the standard hydrogen electrode, which at pH 7 corresponds to an overpotential of 0.6 to 1.0 V, with the result being, among other things, the generation of hydrogen with an optimal turnover frequency of ca. 1.5 million mol H.sub.2/mol catalyst per h.

  7. Synthesis and fluxional behavior of [Bis(trialkylphosphine)nickelio]anthracene (Alkyl = Et, Bu)

    SciTech Connect

    Stanger, A.; Vollhardt, K.P.C. |

    1992-01-01

    The title compounds were prepared from the respective (R{sub 3}P){sub 2}NiCl{sub 2} complexes and magnesium-anthracene-(THF){sub 3} (or anthracene in the presence of Mg or C{sub 8}K). The assignment of the anthracene proton NMR signals using NOE in conjunction with magnetization-transfer techniques is described. The complexes undergo haptotropic rearrangements in which the (R{sub 3}P){sub 2}Ni moiety migrates between the two terminal rings of the coordinated anthracene. The rates of these processes are concentration independent and unaffected by the presence of free anthracene and tris(trialkylphosphine)nickel. Kinetic studies in the temperature range-60 to +70 {degrees}C using line shape analysis and spin saturation transfer techniques were carried out. It was found that {Delta}H{sup {double_dagger}} = 13.6 kcal mol{sup {minus}1} and {Delta}S{sup {double_dagger}} = 4.3 eu for the haptotropic rearrangement in 2, and similar values were found for 1. Possible mechanisms are discussed. According to {sup 1}H, {sup 13}C, and {sup 31}P NMR data, the coordination number between the anthracene and the (R{sub 3}P){sub 2}Ni moiety is 4. However, an equilibrium between two {eta}{sup 2} structures with {Delta}G{sup {double_dagger}} {le} 4 kcal mol{sup {minus}1} cannot be ruled out. 19 refs., 4 figs.

  8. Synthesis of Aza-m-Xylylene diradicals with large singlet-triplet energy gap and statistical analyses of their EPR spectra

    SciTech Connect

    Olankitwanit, Arnon; Pink, Maren; Rajca, Suchada; Rajca, Andrzej

    2014-10-08

    We describe synthesis and characterization of a derivative of aza-m-xylylene, diradical 2, that is persistent in solution at room temperature with the half-life measured in minutes (~80250 s) and in which the triplet ground state is below the lowest singlet state by >10 kcal mol?. The triplet ground states and ?EST of 2 in glassy solvent matrix are determined by a new approach based on statistical analyses of their EPR spectra. Characterization and analysis of the analogous diradical 1 are carried out for comparison. Statistical analyses of their EPR spectra reliably provide improved lower bounds for ?EST (from >0.4 to >0.6 kcal mol?) and are compatible with a wide range of relative contents of diradical vs monoradical, including samples in which the diradical and monoradical are minor and major components, respectively. This demonstrates a new powerful method for the determination of the triplet ground states and ?EST applicable to moderately pure diradicals in matrices.

  9. Aluminum doped zirconia nanopowders: Wet-chemical synthesis and structural analysis by Rietveld refinement

    SciTech Connect

    Srdic, Vladimir V. Rakic, Srdan; Cvejic, Zeljka

    2008-10-02

    Alumina/zirconia nanopowders, with up to 20 mol% Al{sub 2}O{sub 3}, were prepared by wet-chemical synthesis technique, using controlled hydrolysis of alkoxides. The as-synthesized powders are amorphous, have very high specific surface area and the corresponding particle size smaller than 4 nm. Amorphous powders with 0, 10 and 20 mol% Al{sub 2}O{sub 3} crystallize at 460, 692 and 749 deg. C, respectively, as a single-phase tetragonal zirconia, without any traces of alumina phases. Rietvled refinement of X-ray diffraction data, used for the detailed structural analysis of annealed nanopowders, showed that the high-temperature zirconia phase is stabilized due to the formation of ZrO{sub 2}/Al{sub 2}O{sub 3} solid solutions. High solubility of alumina in the tetragonal zirconia (up to 28.6 at% Al{sup 3+}) and stabilization of tetragonal zirconia solid solution up to high temperature (as high as 1150 deg. C) were also confirmed.

  10. Effect of Yttria Content on the Zirconia Unit Cell Parameters

    SciTech Connect

    Krogstad, Jessica A.; Lepple, Maren; Gao, Yan; Lipkin, Don M.; Levi, Carlos G.

    2012-02-06

    The relationship between yttria concentration and the unit cell parameters in partially and fully stabilized zirconia has been reassessed, motivated by the need to improve the accuracy of phase analysis upon decomposition of t{prime}-based thermal barrier coatings. Compositions ranging from 6 to 18 mol% YO{sub 1.5} were synthesized and examined by means of high-resolution X-ray diffraction. Lattice parameters were determined using the Rietveld refinement method, a whole-pattern fitting procedure. The revised empirical relationships fall within the range of those published previously. However, efforts to achieve superior homogeneity of the materials, as well as accuracy of the composition and lattice parameters, provide increased confidence in the reliability of these correlations for use in future studies. Additional insight into the potential sources for scatter previously reported for the transition region ({approx}12-14 mol% YO{sub 1.5}), where tetragonal and cubic phases have been observed to coexist, is also provided. Implications on the current understanding of stabilization mechanisms in zirconia are discussed.

  11. Adsorption of metal ions on polyaminated highly porous chitosan chelating resin

    SciTech Connect

    Kawamura, Yoshihide; Mitsuhashi, Masaki; Tanibe, Hiroaki ); Yoshida, Hiroyuki )

    1993-02-01

    Highly porous chelating resin was fabricated from the natural polysaccharide chitosan. The adsorption capacity was increased by polyamination with poly(ethylene imine) (MW = 10,000). The capacity was about 1-2 times larger than that of commercial chelate resins. The selectivity for adsorption of metal ions on the resin, which was determined for a single solute at pH [approx equal] 7, was Hg(II) > UO[sub 2](II) > Cd(II) > Zn(II) > Cu(II) > Ni(II). Mg(II), Ca(II), Ga(III), As(III), and Sr(II) were not adsorbed on the resin at all. The selectivity depended on the pH of each metal solution. The equilibrium isotherms for adsorption of HgCl[sub 2] were correlated by the Langmuir equation. The saturation capacities were close to the concentration of amino group fixed on the resin. When HCl or NaCl coexisted in HgCl[sub 2] solution and their concentrations were lower than 100 mol/m[sup 3], the saturation capacity of HgCl[sub 2] was little affected by them. When 500 mol/m[sup 3] H[sub 2]SO[sub 4] coexisted in HgCl[sub 2] solution, extremely low pH inhibited the adsorption of Hg(II) at all.

  12. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    SciTech Connect

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-25

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  13. Effects of Light and Temperature on Fatty Acid Production in Nannochloropsis Salina

    SciTech Connect

    Van Wagenen, Jonathan M.; Miller, Tyler W.; Hobbs, Samuel J.; Hook, Paul W.; Crowe, Braden J.; Huesemann, Michael H.

    2012-03-12

    Accurate prediction of algal biofuel yield will require empirical determination of physiological responses to the climate, particularly light and temperature. One strain of interest, Nannochloropsis salina, was subjected to ranges of light intensity (5-850 {mu}mol m{sup -2} s{sup -1}) and temperature (13-40 C); exponential growth rate, total fatty acids (TFA) and fatty acid composition were measured. The maximum acclimated growth rate was 1.3 day{sup -1} at 23 C and 250 {mu}mol m{sup -2} s{sup -1}. Fatty acids were detected by gas chromatography with flame ionization detection (GC-FID) after transesterification to corresponding fatty acid methyl esters (FAME). A sharp increase in TFA containing elevated palmitic acid (C16:0) and palmitoleic acid (C16:1) during exponential growth at high light was observed, indicating likely triacylglycerol accumulation due to photo-oxidative stress. Lower light resulted in increases in the relative abundance of unsaturated fatty acids; in thin cultures, increases were observed in palmitoleic and eicosapentaenoeic acids (C20:5{omega}3). As cultures aged and the effective light intensity per cell converged to very low levels, fatty acid profiles became more similar and there was a notable increase of oleic acid (C18:1{omega}9). The amount of unsaturated fatty acids was inversely proportional to temperature, demonstrating physiological adaptations to increase membrane fluidity. This data will improve prediction of fatty acid characteristics and yields relevant to biofuel production.

  14. The structural and magnetic properties of Pr{sub 1−x}Er{sub x}Al{sub 2}

    SciTech Connect

    Pathak, Arjun K.; Gschneidner, K. A.; Pecharsky, V. K.

    2015-05-07

    We report on the effect of Er addition to PrAl{sub 2} on the lattice parameters, magnetic behavior, heat capacity, and magnetocaloric effect by using x-ray diffraction, magnetization, and heat capacity measurements. Unlike Pr{sub 0.6}Er{sub 0.4}Al{sub 2}, other alloys we studied in the pseudobinary (Pr{sub 1−x}Er{sub x})Al{sub 2} system do not exhibit a sharp peak in heat capacity with the application of magnetic field. Both the cubic lattice parameter and the Curie temperature decrease with increasing Er concentration. The nuclear specific heat coefficient decreases from 660 mJ K mol{sup −1} for x = 0.05 to a nearly negligible value for x = 0.95. The magnetic entropy and adiabatic temperature change varies from 2 to 4 J mol{sup −1} K{sup −1} and 2.5 to 5 K at ΔH = 20 kOe for x = 0.05 to 0.95, respectively. These values of the magnetocaloric effect are comparable to those of the other rare-earth dialuminides systems.

  15. Thermodynamic characterization of new palladium alloy tritides

    SciTech Connect

    Hoelder, J.S.; Wermer, J.R.

    1994-08-09

    The decay of tritium in a metal tritide generates {sup 3}He in the lattice which tends to degrade the performance of the material over time. It is desired to develop a material which minimizes the tritium aging effects and may be tailored to a particular tritium processing application. Pd alloys with Ni and Co have been investigated, as Pd tritide is known to be resistant to tritium aging effects and alloying provides a means for adjusting the plateau pressure of the metal tritide. Sets of tritium desorption isotherms were acquired at temperatures between 273 and 338 K over the pressure range of 1 to 900 kPa. The thermodynamic parameters of {Delta}H and {Delta}S for the {beta}-{alpha} phase transition of the metal tritides were determined across the plateau regions of the P-C-T curves. The average values of {Delta}H (kJ/mol{center_dot}T) and {Delta}S (J/K/mol{center_dot}T) were found to be 15.8 and 50.1 for Pd(2.8 wt. %)Ni, 13.7 and 50.3 for Pd(5.2 wt. %)Ni, 15.9 and 51.3 for Pd(2.8 wt. %)Co, and 13.6 and 51.8 for Pd(5.2 wt. %)Co, respectively.

  16. Preparation, characterization of the Ta-doped ZnO nanoparticles and their photocatalytic activity under visible-light illumination

    SciTech Connect

    Kong Jizhou; Li Aidong; Zhai Haifa; Gong Youpin; Li Hui; Wu Di

    2009-08-15

    This paper describes a novel catalyst of the Ta-doped ZnO nanocrystals prepared by a modified polymerizable complex method using the water-soluble tantalum precursor as the sources of Ta. The catalysts were characterized by means of various analytical techniques as a function of Ta content (x=0-4 mol%) systematically. A remarkable advantage of the results was confirmed that dopant Ta enhanced the visible-light absorption of ZnO and the low-solubility tantalum doping could restrain the growth of crystal and minish the particle size. The relationship between the physicochemical property and the photocatalytic performance was discussed, and it was found that the photocatalytic activity in the photochemical degradation of methylene blue under visible-light irradiation (lambda>=420 nm) was dependent on the contents of the dopant, which could affect the particle size, concentration of surface hydroxyl groups and active hydrogen-related defect sites, and the visible-light absorption. The highest photocatalytic activity was obtained for the 1.0 mol% Ta-doped ZnO sample. - Graphical abstract: The addition of the tantalum into ZnO prepared by a modified polymerizable complex method not only restrains the growth of crystal, minish the particle size, but also changes the nanocrystal morphology.

  17. Are the Radical Centers in Peptide Radical Cations Mobile? The Generation, Tautomerism, and Dissociation of Isomeric α-Carbon-Centered Triglycine Radical Cations in the Gas Phase

    SciTech Connect

    Chu, Ivan K.; Zhao, Junfang; Xu, Minjie; Siu, Shiu On; Hopkinson, Alan C.; Siu , K W Michael

    2008-05-31

    The mobility of the radical center in three isomeric triglycine radical cationss[G•GG]+, [GG•G]+, and [GGG•]+shas been investigated theoretically via density functional theory (DFT) and experimentally via tandem mass spectrometry. These radical cations were generated by collision-induced dissociations (CIDs) of Cu(II)-containing ternary complexes that contain the tripeptides YGG, GYG, and GGY, respectively (G and Y are the glycine and tyrosine residues, respectively). Dissociative electron transfer within the complexes led to observation of [Y•GG]+, [GY•G]+, and [GGY•]+; CID resulted in cleavage of the tyrosine side chain as p-quinomethide, yielding [G•GG]+, [GG•G]+, and [GGG•]+, respectively. Interconversions between these isomeric triglycine radical cations have relatively high barriers (g44.7 kcal/mol), in support of the thesis that isomerically pure [G•GG]+, [GG•G]+, and [GGG•]+ can be experimentally produced. This is to be contrasted with barriers < 17 kcal/mol that were encountered in the tautomerism of protonated triglycine [Rodriquez C. F. et al. J. Am. Chem. Soc. 2001, 123, 3006-3012]. The CID spectra of [G•GG]+, [GG•G]+, and [GGG•]+ were substantially different, providing experimental proof that initially these ions have distinct structures. DFT calculations showed that direct dissociations are competitive with interconversions followed by dissociation.

  18. The role of hydrogen bonds in protein folding and protein association

    SciTech Connect

    Ben-Naim, A. (National Inst. of Health, Bethesda, MD (USA))

    1991-02-07

    The contribution of a pair of functional groups that can form either intermolecular or intramolecular hydrogen bonds to the total standard free energy of the process of protein folding or protein association is examined. It is found that this contribution can be quite large, either positive or negative, depending on the particular process and on the solvent density. This is in contrast to the common belief that the hydrogen-bond energies tend to be compensated in these processes. For the binding process, in which the two functional groups are completely removed from the aqueous environment, the contribution of such a pair of functional groups to {Delta}G can be as high as +6.4 kcal/mol. This is the main reason why hydrophobic rather than hydrophilic surfaces tend to attach to each other. In contrast, when the two functional groups are only partially removed from the aqueous environment, as in the case of the formation of {alpha}-helix, their contribution to {Delta}G can be negative and of the order of about 1 kcal/mol.

  19. Mechanism and kinetics of peptide partitioning into membranes

    SciTech Connect

    Ulmschneider, Martin [University of Oxford; Killian, J Antoinette [University of Utrecht; Doux, Jacques P. F. [University of Utrecht; Smith, Jeremy C [ORNL; Ulmschneider, Jakob [University of Heidelberg

    2010-02-01

    Partitioning properties of transmembrane (TM) polypeptide segments directly determine membrane protein folding, stability, and function, and their understanding is vital for rational design of membrane active peptides. However, direct determination of water-to-bilayer transfer of TM peptides has proved difficult. Experimentally, sufficiently hydrophobic peptides tend to aggregate, while atomistic computer simulations at physiological temperatures cannot yet reach the long time scales required to capture partitioning. Elevating temperatures to accelerate the dynamics has been avoided, as this was thought to lead to rapid denaturing. However, we show here that model TM peptides (WALP) are exceptionally thermostable. Circular dichroism experiments reveal that the peptides remain inserted into the lipid bilayer and are fully helical, even at 90 C. At these temperatures, sampling is 50 500 times faster, sufficient to directly simulate spontaneous partitioning at atomic resolution. A folded insertion pathway is observed, consistent with three-stage partitioning theory. Elevated temperature simulation ensembles further allow the direct calculation of the insertion kinetics, which is found to be first-order for all systems. Insertion barriers are Hin = 15 kcal/mol for a general hydrophobic peptide and 23 kcal/mol for the tryptophan-flanked WALP peptides. The corresponding insertion times at room temperature range from 8.5 s to 163 ms. High-temperature simulations of experimentally validated thermostable systems suggest a new avenue for systematic exploration of peptide partitioning properties.

  20. Glass-ceramic joint and method of joining

    DOEpatents

    Meinhardt, Kerry D [Richland, WA; Vienna, John D [West Richland, WA; Armstrong, Timothy R [Clinton, TN; Pederson, Larry R [Kennewick, WA

    2003-03-18

    The present invention is a glass-ceramic material and method of making useful for joining a solid ceramic component and at least one other solid component. The material is a blend of M1-M2-M3, wherein M1 is BaO, SrO, CaO, MgO, or combinations thereof, M2 is Al.sub.2 O.sub.3, present in the blend in an amount from 2 to 15 mol %, M3 is SiO.sub.2 with up to 50 mol % B.sub.2 O.sub.3 that substantially matches a coefficient of thermal expansion of the solid electrolyte. According to the present invention, a series of glass ceramics in the M1-Al.sub.2 O.sub.3 -M3 system can be used to join or seal both tubular and planar solid oxide fuel cells, oxygen electrolyzers, and membrane reactors for the production of syngas, commodity chemicals and other products.

  1. Computational screening of large molecule adsorption by metal-organic frameworks.

    SciTech Connect

    Allendorf, Mark D.; Greathouse, Jeffery A.

    2010-04-01

    Grand canonical Monte Carlo simulations were performed to investigate trends in low-pressure adsorption of a broad range of organic molecules by a set of metal-organic frameworks (MOFs). The organic analytes considered here are relevant to applications in chemical detection: small aromatics (o-, m-, and p-xylene), polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene), explosives (TNT and RDX), and chemical warfare agents (GA and VM). The framework materials included several Zn-MOFs (IRMOFs 1-3, 7, 8), a Cr-MOF (CrMIL-53lp), and a Cu-MOF (HKUST-1). Many of the larger organics were significantly adsorbed by the target MOFs at low pressure, which is consistent with the exceptionally high isosteric heats of adsorption (25 kcal/mol - 60 kcal/mol) for this range of analyte. At a higher loading pressure of 101 kPa, the Zn-MOFs show a much higher volumetric uptake than either CrMIL-53-lp or HKUST-1 for all types of analyte. Within the Zn-MOF series, analyte loading is proportional to free volume, and loading decreases with increasing analyte size due to molecular packing effects. CrMIL-53lp showed the highest adsorption energy for all analytes, suggesting that this material may be suitable for low-level detection of organics.

  2. A novel plug-flow digester for biogasification of conventional and hazardous organics

    SciTech Connect

    Ghosh, S.; Kato, Y.; Liu, T.; Fukushi, K.

    1996-12-31

    A novel plug-flow digestion system of simple construction was designed, fabricated and operated for several years with a synthetic mixture of solid and liquid wastes simulating conditions south of the US-Mexican border and other developing countries. Benzene, toluene, and o-xylene (BTX) were mixed with the synthetic feed in several phases of this research to simulate field conditions where these solvents are discharged to public sewers and mixed with non-hazardous pollutants. The mesophilic plug-flow digester exhibited a high gas yield of 0.46 SCM /kg VS added, a methane content of 77 mol%, and a VS reduction of 75% at an HRT of 13 days with a 96% biodegradation of the feed toluene. At a feed concentration of 50 mg/l, toluene did not inhibit anaerobic fermentation. Gas and methane yields, and VS and COD conversion efficiencies were about the same with or without toluene present in the feed. At a reduced HRT of 8 days, a high feed COD concentration of 50,000 mg/l, and a loading rate of 0.48 kg VS/m{sup 3}-day, the digester afforded a gas yield of 3.1 SCM /kg VS added, and a methane content of 67 mol%. Benzene, toluene, and o-xylene were biodegraded at efficiencies of 94%, 90%, and 88%, respectively. The degradation kinetics of the xenobiotic compound could be described by a model based on cometabolic degradation of these secondary substrates.

  3. Determination of hydrogen diffusion coefficients in F82H by hydrogen depth profiling with a tritium imaging plate technique

    SciTech Connect

    Higaki, M.; Otsuka, T.; Hashizume, K.; Tokunaga, K.; Ezato, K.; Suzuki, S.; Enoeda, M.; Akiba, M.

    2015-03-15

    Hydrogen diffusion coefficients in a reduced activation ferritic/martensitic steel (F82H) and an oxide dispersion strengthened F82H (ODS-F82H) have been determined from depth profiles of plasma-loaded hydrogen with a tritium imaging plate technique (TIPT) in the temperature range from 298 K to 523 K. Data on hydrogen diffusion coefficients, D, in F82H, are summarized as D [m{sup 2}*s{sup -1}] =1.1*10{sup -7}exp(-16[kJ mol{sup -1}]/RT). The present data indicate almost no trapping effect on hydrogen diffusion due to an excess entry of energetic hydrogen by the plasma loading, which results in saturation of the trapping sites at the surface and even in the bulk. In the case of ODS-F82H, data of hydrogen diffusion coefficients are summarized as D [m{sup 2}*s{sup -1}] =2.2*10{sup -7}exp(-30[kJ mol{sup -1}]/RT) indicating a remarkable trapping effect on hydrogen diffusion caused by tiny oxide particles (Y{sub 2}O{sub 3}) in the bulk of F82H. Such oxide particles introduced in the bulk may play an effective role not only on enhancement of mechanical strength but also on suppression of hydrogen penetration by plasma loading.

  4. State-to-state reaction dynamics of {sup 18}O+{sup 32}O{sub 2} studied by a time-dependent quantum wavepacket method

    SciTech Connect

    Xie, Wenbo; Liu, Lan; Sun, Zhigang; Guo, Hua; Dawes, Richard

    2015-02-14

    The title isotope exchange reaction was studied by converged time-dependent wave packet calculations, where an efficient 4th order split operator was applied to propagate the initial wave packet. State-to-state differential and integral cross sections up to the collision energy of 0.35 eV were obtained with {sup 32}O{sub 2} in the hypothetical j{sub 0} = 0 state. It is discovered that the differential cross sections are largely forward biased in the studied collision energy range, due to the fact that there is a considerable part of the reaction occurring with large impact parameter and short lifetime relative to the rotational period of the intermediate complex. The oscillations of the forward scattering amplitude as a function of collision energy, which result from coherent contribution of adjacent resonances, may be a sensitive probe for examining the quality of the underlying potential energy surface. A good agreement between the theoretical and recent experimental integral and differential cross sections at collision energy of 7.3 kcal/mol is obtained. However, the theoretical results predict slightly too much forward scattering and colder rotational distributions than the experimental observations at collision energy of 5.7 kcal/mol.

  5. Concentration effect of Er{sup 3+} ions on structural and spectroscopic properties of CdNb{sub 2}O{sub 6} phosphors

    SciTech Connect

    Ghafouri, Sanaz Aian; Erdem, Murat; Ekmeki, M. Kaan; Mergen, Ayhan; zen, Gnl

    2014-12-15

    Excitation and emission spectra of a visible room-temperature Er{sup 3+} ions luminescence from powders. - Highlights: This is the first report on spectroscopic properties of CdNb{sub 2}O{sub 6}:Er{sup 3+}. The crystalline sizes are affected as the concentration of Er{sup 3+} ions increased. Quenching of the luminescence was observed to be above 1.0 mol% Er{sup 3+}. - Abstract: This study is focused on the synthesis and characterization of CdNb{sub 2}O{sub 6} compounds doped with of Er{sup 3+} ions. Powders were synthesized by using the molten salt method and annealed at 900 C for 4 h. The synthesized particles were structurally characterized by using X-ray diffraction, scanning electron microscopy. A single phase of the CdNb{sub 2}O{sub 6} was determined and the size of the particles was found to be affected by the presence and the concentration of Er{sup 3+} ions. Luminescence properties of each sample were investigated by measuring accurately the emission and excitation spectra at room temperature in the wavelength range of 2001700 nm by exciting the Er{sup 3+} ions at 379 nm and 805 nm. Quenching of the luminescence in both visible and near infrared spectral regions was observed to be above 1.0 mol% Er{sup 3+} concentration.

  6. Reaction layer characterization of the braze joint of silicon nitride to stainless steel

    SciTech Connect

    Xu, R.; Indacochea, J.E. . Civil and Materials Engineering Dept.)

    1994-10-01

    This investigation studies the role of titanium in the development of the reaction layer in braze joining silicon nitride to stainless steel using titanium-active copper-silver filler metals. This reaction layer formed as a result of titanium diffusing to the filler metal/silicon nitride interface and reacting with the silicon nitride to form the intermetallics, titanium nitride (TiN) and titanium silicide (Ti[sub 5]Si[sub 3]). This reaction layer, as recognized in the literature, allows wetting of the ceramic substrate by the molten filler metal. The reaction layer thickness increases with temperature and time. Its growth rate obeys the parabolic relationship. Activation energies of 220.1 and 210.9 kJ/mol were calculated for growth of the reaction layer for the two filler metals used. These values are close to the activation energy of nitrogen in TiN (217.6 kJ/mol). Two filler metals were used in this study, Ticusil (68.8 wt% Ag, 26.7 wt% Cu, 4.5 wt% Ti) and CB4 (70.5 wt% Ag, 26.5 wt% Cu, 3.0 wt% Ti). The joints were processed in vacuum at temperatures of 840 to 900 C at various times. Bonding strength is affected by reaction layer thickness in the absence of Ti-Cu intermetallics in the filler metal matrix.

  7. Growth of Ammonium Bisulfate Clusters by Adsorption of Oxygenated Organic Molecules

    SciTech Connect

    DePalma, Joseph W.; Wang, Jian; Wexler, Anthony S.; Johnston, Murray V.

    2015-10-21

    Quantum chemical calculations were employed to model the interactions of the [(NH4+)4(HSO4-)4] ammonium bisulfate cluster with one or more molecular products of monoterpene oxidation. A strong interaction was found between the bisulfate ion of the cluster and a carboxylic acid, aldehyde or ketone functionality of the organic molecule. Free energies of adsorption for carboxylic acids were in the -70 to -73 kJ/mol range, while those for aldehydes and ketones were in the -46 to -50 kJ/mol range. These values suggest that a small ambient ammonium bisulfate cluster, such as the [(NH4+)4(SO4-)4] cluster, is able to adsorb an oxygenated organic molecule. Although adsorption of the first molecule is highly favorable, adsorption of subsequent molecules is not, suggesting that sustained uptake of organic molecules does not occur, and thus is not a pathway for continuing growth of the cluster. This result is consistent with ambient measurements showing that particles below ~1 nm grow slowly, while those above 1 nm grow at an increasing rate presumably due to a lower surface energy barrier enabling the uptake of organic molecules. This work provides insight into the molecular level interactions which affect sustained cluster growth by uptake of organic molecules.

  8. Multiphoton photoluminescence contrast in switched Mg:LiNbO{sub 3} and Mg:LiTaO{sub 3} single crystals

    SciTech Connect

    Reichenbach, P., E-mail: philipp.reichenbach@iapp.de; Kmpfe, T.; Thiessen, A.; Haumann, A.; Eng, L. M. [Institut fr Angewandte Photophysik, Technische Universitt Dresden, George-Bhr-Str. 1, 01069 Dresden (Germany); Woike, T. [Institut fr Strukturphysik, Technische Universitt Dresden, Zellescher Weg 16, 01069 Dresden (Germany)

    2014-09-22

    We observed a multiphoton luminescence contrast between virgin and single-switched domains in Mg-doped LiNbO{sub 3} (LNO) and LiTaO{sub 3} (LTO) single crystals with different doping levels of 07?mol. % and 08?mol. %, respectively. A luminescence contrast in the range of 3% was measured between as-grown and electrically inverted domain areas in Mg:LNO samples, while the contrast reaches values of up to 30% for the Mg:LTO case. Under annealing, an exponential decay of the domain contrast was observed. The activation energy of about 1?eV being determined for the decay allowed a comparison with reported activation energies of associated defects, clearly illustrating a strong connection between thermal contrast decay and the H{sup +} and Li{sup +}-ion mobility. Finally, performing similar experiments on oxidized samples undoubtedly demonstrated that the origin of the reported luminescence contrast is strongly connected with lithium ions.

  9. Lasing characteristics of ZrO{sub 2}Y{sub 2}O{sub 3}Ho{sub 2}O{sub 3} crystal

    SciTech Connect

    Borik, M A; Lomonova, E E; Kulebyakin, A V; Ushakov, S N; Lyapin, A A; Ryabochkina, P A; Chabushkin, A N

    2013-09-30

    The spectral dependences of the gain cross section of the {sup 5}I{sub 8} ? {sup 5}I{sub 7}, {sup 5}I{sub 7} ? {sup 5}I{sub 8} transition of Ho{sup 3+} ions in the ZrO{sub 2} 13.6 mol % Y{sub 2}O{sub 3} 0.4 mol % Ho{sub 2}O{sub 3} crystal are calculated at different relative population inversions using the absorption and luminescence spectra of the {sup 5}I{sub 8} ? {sup 5}I{sub 7} and {sup 5}I{sub 7} ? {sup 5}I{sub 8} transitions of Ho{sup 3+} ions at T=''300'' K. Lasing of these crystals at the {sup 5}I{sub 7} ? {sup 5}I{sub 8} transition is obtained for the first time under pumping by a Tm : YLiF{sub 4} laser (?{sub p} = 1.905 ?m). The lasing wavelength is 2.17 ?m. (lasers)

  10. Effect of Gaseous Impurities on Long-Term Thermal Cycling and Aging Properties of Complex Hydrides for Hydrogen Storage

    SciTech Connect

    Chandra, Dhanesh; Lamb, Joshua; Chien, Wen-Ming; Talekar, Anjali; and Pal, Narendra.

    2011-03-28

    This program was dedicated to understanding the effect of impurities on Long-Term Thermal Cycling and aging properties of Complex Hydrides for Hydrogen Storage. At the start of the program we found reversibility between Li2NH+LiH  LiH+LiNH2 (yielding ~5.8 wt.%H capacity). Then we tested the effect of impurity in H2 gas by pressure cycling at 255oC; first with industrial gas containing ppm levels of O2 and H2O as major impurities. Both these impurities had a significant impact on the reversibility and decreased the capacity by 2.65 wt.%H. Further increase in number of cycles from 500 to 1100 showed only a 0.2 wt%H more weight loss, showing some capacity is still maintained after a significant number of cycles. The loss of capacity is attributed to the formation of ~55 wt% LiH and ~30% Li2O, as major contaminant phases, along with the hydride Li2NH phase; suggesting loss of nitrogen during cycling. The effect of 100 ppm H2O in H2 also showed a decrease of ~2.5 wt.%H (after 560 cycles), and 100ppm O2 in H2; a loss of ~4.1 wt.%. Methane impurity (100 ppm, 100cycles), showed a very small capacity loss of 0.9 wt.%H under similar conditions. However, when Li3N was pressure cycled with 100ppmN2-H2 there were beneficial effects were observed (255oC); the reversible capacity increased to 8.4wt.%H after 853 cycles. Furthermore, with 20 mol.%N2-H2 capacity increased to ~10 wt.%H after 516 cycles. We attribute this enhancement to the reaction of nitrogen with liquid lithium during cycling as the Gibbs free energy of formation of Li3N (Go = -98.7 kJ/mol) is more negative than that of LiH (Go = -50.3 kJ/mol). We propose that the mitigation of hydrogen capacity losses is due to the destabilization of the LiH phase that tends to accumulate during cycling. Also more Li2NH phase was found in the cycled product. Mixed Alanates (3LiNH2:Li3AlH6) showed that 7 wt% hydrogen desorbed under dynamic vacuum. Equilibrium experiments (maximum 12 bar H2) showed up to 4wt% hydrogen

  11. Molecular and Dissociative Adsorption of Water on (TiO 2 ) n Clusters, n = 1–4

    SciTech Connect

    Chen, Mingyang; Straatsma, Tjerk P.; Dixon, David A.

    2015-10-20

    In the low energy structures of the (TiO2)n(H2O)m (n ≤ 4, m ≤ 2n) and (TiO2)8(H2O)m (m = 3, 7, 8) clusters were predicted using a global geometry optimization approach, with a number of new lowest energy isomers being found. Water can molecularly or dissociatively adsorb on pure and hydrated TiO2 clusters. Dissociative adsorption is the dominant reaction for the first two H2O adsorption reactions for n = 1, 2, and 4, for the first three H2O adsorption reactions for n = 3, and for the first four H2O adsorption reactions for n = 8. As more H2O’s are added to the hydrated (TiO2)n cluster, dissociative adsorption becomes less exothermic as all the Ti centers become 4-coordinate. Furthermore two types of bonds can be formed between the molecularly adsorbed water and TiO2 clusters: a Lewis acid–base Ti–O(H2) bond or an O···H hydrogen bond. The coupled cluster CCSD(T) results show that at 0 K the H2O adsorption energy at a 4-coordinate Ti center is ~15 kcal/mol for the Lewis acid–base molecular adsorption and ~7 kcal/mol for the H-bond molecular adsorption, in comparison to that of 8–10 kcal/mol for the dissociative adsorption. The cluster size and geometry independent dehydration reaction energy, ED, for the general reaction 2(-TiOH) → -TiOTi– + H2O at 4-coordinate Ti centers was estimated from the aggregation reaction of nTi(OH)4 to form the monocyclic ring cluster (TiO3H2)n + nH2O. ED is estimated to be -8 kcal/mol, showing that intramolecular and intermolecular dehydration reactions are intrinsically thermodynamically allowed for the hydrated (TiO2)n clusters with all of the Ti centers 4-coordinate, which can be hindered by cluster geometry changes caused by such

  12. Mechanisms of Selective Cleavage of C-O Bonds in Di-aryl Ethers in Aqueous Phase

    SciTech Connect

    He, Jiayue; Zhao, Chen; Mei, Donghai; Lercher, Johannes A.

    2014-01-02

    A novel route for cleaving the C-O aryl ether bonds of p-substituted H-, CH3-, and OH- diphenyl ethers has been explored over Ni/SiO2 catalysts at very mild conditions. The C-O bond of diphenyl ether is cleaved by parallel hydrogenolysis and hydrolysis (hydrogenolysis combined with HO* addition) on Ni. The rates as a function of H2 pressure from 0 to 10 MPa indicate that the rate-determining step is the C-O bond cleavage on Ni. H* atoms compete with the organic reactant for adsorption leading to a maximum in the rate with increasing H2 pressure. In contrast to diphenyl ether, hydrogenolysis is the exclusive route for cleaving an ether C-O bond of di-p-tolyl ether to form p-cresol and toluene. 4,4'-dihydroxydiphenyl ether undergoes sequential surface hydrogenolysis, first to phenol and HOC6H4O* (adsorbed), which is then cleaved to phenol (C6H5O* with added H*) and H2O (O* with two added H*) in a second step. Density function theory supports the operation of this pathway. Notably, addition of H* to HOC6H4O* is less favorable than a further hydrogenolytic C-O bond cleavage. The TOFs of three aryl ethers with Ni/SiO2 in water followed the order 4,4'-dihydroxydiphenyl ether (69 h-1) > diphenyl ether (26 h-1) > di-p-tolyl ether (1.3 h-1), in line with the increasing apparent activation energies, ranging from 93 kJ∙mol-1 (4,4'-dihydroxydiphenyl ether) < diphenyl ether (98 kJ∙mol-1) to di-p-tolyl ether (105 kJ∙mol-1). D.M. thanks the support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R

  13. Theoretical study of the rhodium dimer interaction with the hydrogen molecule

    SciTech Connect

    Castillo, S.; Cruz, A.; Cuan, A.

    1995-12-31

    The C{sub 2v} potential energy surfaces for the end-on and side-on approaches of H{sub 2} to the rhodium dimer were studied through self-consistent-field (SCF) and multiconfigurational SCF calculations, followed by extensive variational plus second-order multireference Moller-Plesset perturbational configuration interaction (CIPSI) calculations. Relativistic effective core potentials were used to replace the core electrons of the rhodium atoms. Together with the Rh{sub 2}-H{sub 2} interaction, the spectroscopic constants for the {sup 5}{summation}{sub g}{sup +}, {sup 1}{summation}{sub g}{sup +}, {sup 3}II{sub {mu}}, and {sup 1}II{sub {mu}} states of Rh{sub 2} are reported. It was found that the potential energy curves of the parallel and the perpendicular Rh{sub 2}({sup 5}{summation}{sub g}) interaction with H{sub 2} show that the rhodium dimer has the ability to capture and break the H{sub 2} molecule. The parallel interaction presents a soft potential barrier of 7.8 kcal/mol, energy necessary to surmount before the capture and breaking of the H-H bond. In the perpendicular interaction, Rh{sub 2} captures and breaks spontaneously H{sub 2}. The potential energy curve of the parallel Rh{sub 2}({sup 1}{summation}{sub g}) + H{sub 2} interaction shows that Rh{sub 2} also captures and breaks spontaneously the H{sub 2}, with a very deep well of 92.7 kcal/mol, while in the perpendicular approach, Rh{sub 2} has to surmount again a soft barrier of 5.2 kcal/mol to capture and break the H{sub 2} molecule. Finally, the energy curves of the parallel Rh{sub 2}({sup 1,3}II{sub {mu}}) + H{sub 2} interactions present capture and breaking with very small barriers. The perpendicular interactions capture and scisse the hydrogen molecule spontaneously. 35 refs., 6 tabs.

  14. Dielectric, ferroelectric and piezoelectric properties of Nb{sup 5+} doped BCZT ceramics

    SciTech Connect

    Parjansri, Piewpan; Intatha, Uraiwan; Eitssayeam, Sukum

    2015-05-15

    Highlights: • Average grain size of BCZT ceramic decreased with the increasing Nb{sup 5+} doping. • Dielectric constant value is enhanced with Nb{sup 5+} doping. • Dielectric loss of BCZT − x Nb{sup 5+} ceramics was less than 0.03 at room temperature (1 kHz). • Piezoelectric coefficient decreased with the increasing Nb{sup 5+} doping. • The relaxation behavior is enhanced with the doping of Nb{sup 5+}. - Abstract: This work investigated the electrical properties of Nb{sup 5+} (0.0–1.0 mol%) doped with Ba{sub 0.90}Ca{sub 0.10}Zr{sub 0.10}Ti{sub 0.90}O{sub 3} while adding 1 mol% of Ba{sub 0.90}Ca{sub 0.10}Zr{sub 0.10}Ti{sub 0.90}O{sub 3} seeds. The mixed powder was ball milled for 24 h, calcined and sintered at 1200 °C for 2 h and 1450 °C for 4 h, respectively. The XRD patterns of the ceramic samples were investigated by X-ray diffraction. The electrical properties of ceramics were measured and the results indicated that all samples show a pure perovskite phase with no secondary phase. Density and average grain size values were in the range of 5.60–5.71 g/cm{sup 3} and 12.62–1.86 μm, respectively. The highest dielectric constant, ϵ{sub r} at room temperature (1 kHz) was 4636 found at 1.0 mol% Nb. The dielectric loss, tan δ was less than 0.03 for all samples at room temperature (1 kHz). Other electrical properties, P{sub r}, d{sub 33} and k{sub p} values were decreased with Nb doped relates to the decreasing grain size in BCZT ceramics. Moreover, the degrees of phase transition diffuseness and relaxation behavior were observed in the higher Nb doping.

  15. Orbital-optimized MP2.5 and its analytic gradients: Approaching CCSD(T) quality for noncovalent interactions

    SciTech Connect

    Bozkaya, Uğur; Sherrill, C. David

    2014-11-28

    Orbital-optimized MP2.5 [or simply “optimized MP2.5,” OMP2.5, for short] and its analytic energy gradients are presented. The cost of the presented method is as much as that of coupled-cluster singles and doubles (CCSD) [O(N{sup 6}) scaling] for energy computations. However, for analytic gradient computations the OMP2.5 method is only half as expensive as CCSD because there is no need to solve λ{sub 2}-amplitude equations for OMP2.5. The performance of the OMP2.5 method is compared with that of the standard second-order Møller–Plesset perturbation theory (MP2), MP2.5, CCSD, and coupled-cluster singles and doubles with perturbative triples (CCSD(T)) methods for equilibrium geometries, hydrogen transfer reactions between radicals, and noncovalent interactions. For bond lengths of both closed and open-shell molecules, the OMP2.5 method improves upon MP2.5 and CCSD by 38%–43% and 31%–28%, respectively, with Dunning's cc-pCVQZ basis set. For complete basis set (CBS) predictions of hydrogen transfer reaction energies, the OMP2.5 method exhibits a substantially better performance than MP2.5, providing a mean absolute error of 1.1 kcal mol{sup −1}, which is more than 10 times lower than that of MP2.5 (11.8 kcal mol{sup −1}), and comparing to MP2 (14.6 kcal mol{sup −1}) there is a more than 12-fold reduction in errors. For noncovalent interaction energies (at CBS limits), the OMP2.5 method maintains the very good performance of MP2.5 for closed-shell systems, and for open-shell systems it significantly outperforms MP2.5 and CCSD, and approaches CCSD(T) quality. The MP2.5 errors decrease by a factor of 5 when the optimized orbitals are used for open-shell noncovalent interactions, and comparing to CCSD there is a more than 3-fold reduction in errors. Overall, the present application results indicate that the OMP2.5 method is very promising for open-shell noncovalent interactions and other chemical systems with difficult electronic structures.

  16. An Integral Effects Test in a zion-like geometry to investigate the effects of pre-existing hydrogen on direct containment heating in the Surtsey Test Facility. The IET-6 experiment

    SciTech Connect

    Allen, M.D.; Blanchat, T.K.; Pilch, M.; Nichols, R.T.

    1993-01-01

    The sixth experiment of the Integral Effects Test (IET-6) series was conducted to investigate the effects of high pressure melt ejection on direct containment heating. Scale models of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories. The RPV was modeled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a hemispherical bottom head containing a graphite limitor plate with a 4-cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by ejection of an instrument guide tube in a severe nuclear power plant accident. The cavity contained 3.48 kg of water, which corresponds to condensate levels in the Zion plant, and the containment basement floor was dry. A 43-kg initial charge of iron oxide/aluminum/chromium thermite was used to simulate corium debris on the bottom head of the RPV. Molten thermite was ejected by steam at an initial pressure of 6.3 MPa into the reactor cavity. The Surtsey vessel atmosphere contained pre-existing hydrogen to represent partial oxidation of the zirconium in the Zion core. The initial composition of the vessel atmosphere was 87.1 mol.% N{sub 2}, 9.79 mol.% O{sub 2}, and 2.59 mol.% H{sub 2}, and the initial absolute pressure was 198 kPa. A partial hydrogen burn occurred in the Surtsey vessel. The peak vessel pressure increase was 279 kPa in IET-6, compared to 246 kPa in the IET-3 test. The total debris mass ejected into the Surtsey vessel in IET-6 was 42.5 kg. The gas grab sample analysis indicated that there were 180 g{center_dot} moles of pre-existing hydrogen, and that 308{center_dot}moles of hydrogen were produced by steam/metal reactions. About 335 g{center_dot}moles of hydrogen burned, and 153 g{center_dot}moles remained unreacted.

  17. An Integral Effects Test in a zion-like geometry to investigate the effects of pre-existing hydrogen on direct containment heating in the Surtsey Test Facility

    SciTech Connect

    Allen, M.D.; Blanchat, T.K.; Pilch, M. ); Nichols, R.T. )

    1993-01-01

    The sixth experiment of the Integral Effects Test (IET-6) series was conducted to investigate the effects of high pressure melt ejection on direct containment heating. Scale models of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories. The RPV was modeled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a hemispherical bottom head containing a graphite limitor plate with a 4-cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by ejection of an instrument guide tube in a severe nuclear power plant accident. The cavity contained 3.48 kg of water, which corresponds to condensate levels in the Zion plant, and the containment basement floor was dry. A 43-kg initial charge of iron oxide/aluminum/chromium thermite was used to simulate corium debris on the bottom head of the RPV. Molten thermite was ejected by steam at an initial pressure of 6.3 MPa into the reactor cavity. The Surtsey vessel atmosphere contained pre-existing hydrogen to represent partial oxidation of the zirconium in the Zion core. The initial composition of the vessel atmosphere was 87.1 mol.% N[sub 2], 9.79 mol.% O[sub 2], and 2.59 mol.% H[sub 2], and the initial absolute pressure was 198 kPa. A partial hydrogen burn occurred in the Surtsey vessel. The peak vessel pressure increase was 279 kPa in IET-6, compared to 246 kPa in the IET-3 test. The total debris mass ejected into the Surtsey vessel in IET-6 was 42.5 kg. The gas grab sample analysis indicated that there were 180 g[center dot] moles of pre-existing hydrogen, and that 308[center dot]moles of hydrogen were produced by steam/metal reactions. About 335 g[center dot]moles of hydrogen burned, and 153 g[center dot]moles remained unreacted.

  18. Ultraviolet photodissociation dynamics of the n-propyl and i-propyl radicals

    SciTech Connect

    Song, Yu; Zheng, Xianfeng; Zhou, Weidong; Lucas, Michael; Zhang, Jingsong

    2015-06-14

    Ultraviolet (UV) photodissociation dynamics of jet-cooled n-propyl (n-C{sub 3}H{sub 7}) radical via the 3s Rydberg state and i-propyl (i-C{sub 3}H{sub 7}) radical via the 3p Rydberg states are studied in the photolysis wavelength region of 230260 nm using high-n Rydberg atom time-of-flight and resonance enhanced multiphoton ionization techniques. The H-atom photofragment yield spectra of the n-propyl and i-propyl radicals are broad and in good agreement with the UV absorption spectra. The H + propene product translational energy distributions, P(E{sub T})s, of both n-propyl and i-propyl are bimodal, with a slow component peaking around 5-6 kcal/mol and a fast one peaking at ?50 kcal/mol (n-propyl) and ?45 kcal/mol (i-propyl). The fraction of the average translational energy in the total excess energy, ?f{sub T}?, is 0.3 for n-propyl and 0.2 for i-propyl, respectively. The H-atom product angular distributions of the slow components of n-propyl and i-propyl are isotropic, while that of the fast component of n-propyl is anisotropic (with an anisotropy parameter ?0.8) and that of i-propyl is nearly isotropic. Site-selective loss of the ? hydrogen atom is confirmed using the partially deuterated CH{sub 3}CH{sub 2}CD{sub 2} and CH{sub 3}CDCH{sub 3} radicals. The bimodal translational energy and angular distributions indicate two dissociation pathways to the H + propene products in the n-propyl and i-propyl radicals: (i) a unimolecular dissociation pathway from the hot ground-state propyl after internal conversion from the 3s and 3p Rydberg states and (ii) a direct, prompt dissociation pathway coupling the Rydberg excited states to a repulsive part of the ground-state surface, presumably via a conical intersection.

  19. Scalable Computational Chemistry: New Developments and Applications

    SciTech Connect

    Yuri Alexeev

    2002-12-31

    The computational part of the thesis is the investigation of titanium chloride (II) as a potential catalyst for the bis-silylation reaction of ethylene with hexaclorodisilane at different levels of theory. Bis-silylation is an important reaction for producing bis(silyl) compounds and new C-Si bonds, which can serve as monomers for silicon containing polymers and silicon carbides. Ab initio calculations on the steps involved in a proposed mechanism are presented. This choice of reactants allows them to study this reaction at reliable levels of theory without compromising accuracy. The calculations indicate that this is a highly exothermic barrierless reaction. The TiCl{sub 2} catalyst removes a 50 kcal/mol activation energy barrier required for the reaction without the catalyst. The first step is interaction of TiCl{sub 2} with ethylene to form an intermediate that is 60 kcal/mol below the energy of the reactants. This is the driving force for the entire reaction. Dynamic correlation plays a significant role because RHF calculations indicate that the net barrier for the catalyzed reaction is 50 kcal/mol. They conclude that divalent Ti has the potential to become an important industrial catalyst for silylation reactions. In the programming part of the thesis, parallelization of different quantum chemistry methods is presented. The parallelization of code is becoming important aspects of quantum chemistry code development. Two trends contribute to it: the overall desire to study large chemical systems and the desire to employ highly correlated methods which are usually computationally and memory expensive. In the presented distributed data algorithms computation is parallelized and the largest arrays are evenly distributed among CPUs. First, the parallelization of the Hartree-Fock self-consistent field (SCF) method is considered. SCF method is the most common starting point for more accurate calculations. The Fock build (sub step of SCF) from AO integrals is also

  20. Concept Feasibility Report for Electroplating Zirconium onto Uranium Foil - Year 2

    SciTech Connect

    Coffey, Greg W.; Meinhardt, Kerry D.; Joshi, Vineet V.; Pederson, Larry R.; Lavender, Curt A.; Burkes, Douglas

    2015-03-01

    The Fuel Fabrication Capability within the U.S. High Performance Research Reactor Conversion Program is funded through the National Nuclear Security Administration (NNSA) NA-26 (Office of Material Management and Minimization). An investigation was commissioned to determine the feasibility of using electroplating techniques to apply a coating of zirconium onto depleted uranium/molybdenum alloy (U-10Mo). Electroplating would provide an alternative method to the existing process of hot roll-bonding zirconium foil onto the U-10Mo fuel foil during the fabrication of fuel elements for high-performance research reactors. The objective of this research was to develop a reproducible and scalable plating process that will produce a uniform, 25 μm thick zirconium metal coating on U-10Mo foil. In previous work, Pacific Northwest National Laboratory (PNNL) established a molten salt electroplating apparatus and protocol to plate zirconium metal onto molybdenum foil (Coffey 2015). During this second year of the research, PNNL furthered this work by moving to the U-10Mo alloy system (90 percent uranium:10 percent molybdenum). The original plating apparatus was disassembled and re-assembled in a laboratory capable of handling low-level radioactive materials. Initially, the work followed the previous year’s approach, and the salt bath composition was targeted at the eutectic composition (LiF:NaF:ZrF4 = 26:37:37 mol%). Early results indicated that the formation of uranium fluoride compounds would be problematic. Other salt bath compositions were investigated in order to eliminate the uranium fluoride production (LiF:NaF = 61:39 mol% and LiF:NaF:KF = 46.5:11.5:42 mol% ). Zirconium metal was used as the crucible for the molten salt. Three plating methods were used—isopotential, galvano static, and pulsed plating. The molten salt method for zirconium metal application provided high-quality plating on molybdenum in PNNL’s previous work. A key advantage of this approach is that

  1. Technique for measuring air flow and carbon dioxide flux in large, open-top chambers

    SciTech Connect

    Ham, J.M.; Owensby, C.E.; Coyne, P.I.

    1993-10-01

    Open-Top Chambers (OTCs) are commonly used to evaluate the effect of CO{sub 2},O{sub 3}, and other trace gases on vegetation. This study developed and tested a new technique for measuring forced air flow and net CO{sub 2} flux from OTCs. Experiments were performed with a 4.5-m diam. OTC with a sealed floor and a specialized air delivery system. Air flow through the chamber was computed with the Bernoulli equation using measurements of the pressure differential between the air delivery ducts and the chamber interior. An independent measurement of air flow was made simultaneously to calibrate and verify the accuracy of the Bernoulli relationship. The CO{sub 2} flux density was calculated as the product of chamber air flow and the difference in CO{sub 2} concentration between the air entering and exhausting from the OTC (C{sub in}-C{sub out}). Accuracy was evaluated by releasing CO{sub 2} within the OTC at known rates. Data were collected with OTCs at ambient and elevated CO{sub 2} ({approx}700 {mu}mol{sup -1}). Results showed the Bernoulli equation, with a flow coefficient of 0.7, accurately measured air flow in the OTC within {+-}5% regardless of flow rate and air duct geometry. Experiments in ambient OTCs showed CO{sub 2} flux density ({mu}mol m{sup -2} s{sup -1}), computed from 2-min averages of air flow and C{sub in} - C{sub out,} was typically within {+-} 10% of actual flux, provided that the exit air velocity at the top of the OTC was greater than 0.6 m s{sup -1}. Obtaining the same accuracy in CO{sub 2}-enriched OTCs required a critical exit velocity near 1.2 m s{sup -1} to minimize the incursion of ambient air and prevent contamination of exit gas sample. When flux data were integrated over time to estimate daily CO{sub 2} flux ({mu}mol m{sup -2} d{sup -1}), actual and measured values agreed to within {+-}2% for both ambient and CO{sub 2}-enriched chambers, suggesting that accurate measurements of daily net C exchange are possible with this technique.

  2. Complexation of Gluconate with Uranium(VI) in Acidic Solutions: Thermodynamic Study with Structural Analysis

    SciTech Connect

    Zhang, Zhicheng; Helms, G.; Clark, S. B.; Tian, Guoxin; Zanonato, PierLuigi; Rao, Linfeng

    2009-01-05

    Within the pC{sub H} range of 2.5 to 4.2, gluconate forms three uranyl complexes UO{sub 2}(GH{sub 4}){sup +}, UO{sub 2}(GH{sub 3})(aq), and UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -}, through the following reactions: (1) UO{sub 2}{sup 2+} + GH{sub 4}{sup -} = UO{sub 2}(GH{sub 4}){sup +}, (2) UO{sub 2}{sup 2+} + GH{sub 4}{sup -} = UO{sub 2}(GH{sub 3})(aq) + H{sup +}, and (3) UO{sub 2}{sup 2+} + 2GH{sub 4}{sup -} = UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -} + H{sup +}. Complexes were inferred from potentiometric, calorimetric, NMR, and EXAFS studies. Correspondingly, the stability constants and enthalpies were determined to be log {Beta}{sub 1} = 2.2 {+-} 0.3 and {Delta}H{sub 1} = 7.5 {+-} 1.3 kJ mol{sup -1} for reaction (1), log {Beta}{sub 2} = -(0.38 {+-} 0.05) and {Delta}H{sub 2} = 15.4 {+-} 0.3 kJ mol{sup -1} for reaction (2), and log {Beta}{sub 3} = 1.3 {+-} 0.2 and {Delta}H{sub 3} = 14.6 {+-} 0.3 kJ mol{sup -1} for reaction (3), at I = 1.0 M NaClO{sub 4} and t = 25 C. The UO{sub 2}(GH{sub 4}){sup +} complex forms through the bidentate carboxylate binding to U(VI). In the UO{sub 2}(GH{sub 3})(aq) complex, hydroxyl-deprotonated gluconate (GH{sub 3}{sup 2-}) coordinates to U(VI) through the five-membered ring chelation. For the UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -} complex, multiple coordination modes are suggested. These results are discussed in the context of trivalent and pentavalent actinide complexation by gluconate.

  3. Progress Report on FY15 Crystalline Experiments M4FT-15LL0807052

    SciTech Connect

    Zavarin, M.; Zhao, P.; Joseph, C.; Begg, J.; Dai, Z.; Kersting, A. B.

    2015-08-13

    Colloid-facilitated plutonium transport is expected to be the dominant mechanism in its migration through the environment. The forms of Pu colloids (intrinsic versus pseudo-colloid) and their stabilities control temporal and spatial scales of Pu transport in the environment. In the present study, we examine the stability of Pu intrinsic colloids freshly prepared in alkaline solution relative to Pu-montmorillonite pseudo-colloids using a dialysis device and modeling approaches. Intrinsic colloids prepared under alkaline conditions were found to be unstable over a timescale of months. The kinetics of multiple processes, including hydrolysis/precipitation of Pu(IV), dissolution of intrinsic colloids in the absence and presence of the clay colloids, transport of dissolved Pu species across the dialysis membrane, and formation of pseudo-colloids were examined. The dissolution of intrinsic colloids was the rate-limiting process in most cases. The apparent intrinsic colloid dissolution rate constants range from 6×10-7 to 1×10- 6 mol·m-2·day-1 and 4×10-6 to 8×10-6 mol·m-2·day-1 at 25 and 80°C, respectively, while the apparent diffusion rate constants for Pu ions crossing the dialysis membrane are >200 times higher. Elevated temperatures enhance dissolution of Pu colloids and the activation energy for the process is estimated to be 28 kJ mol-1. The sorption of Pu to montmorillonite appears to be endothermic as the affinity of Pu for the clay increases with increasing temperature. Our results provide an in-depth understanding of how intrinsic and pseudo-colloids interact with each other kinetically. Although the fact that intrinsic colloids tend to dissolve in the presence of montmorillonite and transform into pseudo-colloids may limit the migration of intrinsic colloids, the thermodynamically more stable pseudo-colloids may play an important role in Pu transport in

  4. Development of a Conceptual Process for Selective CO 2 Capture from Fuel Gas Streams Using [hmim][Tf 2 N] Ionic Liquid as a Physical Solvent

    SciTech Connect

    Basha, Omar M.; Keller, Murphy J.; Luebke, David R.; Resnik, Kevin P.; Morsi, Badie I.

    2013-06-04

    The Ionic Liquid (IL) [hmim][Tf2N] was used as a physical solvent in an Aspen Plus simulation, employing the Peng-Robinson Equation of State (P-R EOS) with Boston-Mathias (BM) alpha function and standard mixing rules, to develop a conceptual process for CO2 capture from a shifted warm fuel gas stream produced from Pittsburgh # 8 coal for a 400 MWe power plant. The physical properties of the IL, including density, viscosity, surface tension, vapor pressure and heat capacity were obtained from literature and modeled as a function of temperature. Also, available experimental solubility values for CO2, H2, H2S, CO, and CH4 in this IL were compiled and their binary interaction parameters (Δij and lij) were optimized and correlated as functions of temperature. The Span-Wager Equation-of-State EOS was also employed to generate CO2 solubilities in [hmim][Tf2N] at high pressures (up to 10 MPa) and temperatures (up to 510 K). The conceptual process developed consisted of 4 adiabatic absorbers (2.4 m ID, 30 m high) arranged in parallel and packed with Plastic Pall Rings of 0.025 m for CO2 capture; 3 flash drums arranged in series for solvent (IL) regeneration with the pressure-swing option; and a pressure-intercooling system for separating and pumping CO2 up to 153 bar to the sequestration sites. The compositions of all process streams, CO2 capture efficiency, and net power were calculated using Aspen Plus simulator. The results showed that, based on the composition of the inlet gas stream to the absorbers, 95.67 mol% of CO2 was captured and sent to sequestration sites; 99.5 mol% of H2 was separated and sent to turbines; the solvent exhibited a minimum loss of 0.31 mol%; and the net power balance of the entire system was 30.81 MW. These results indicated that [hmim][Tf2N] IL could be used as a physical

  5. Structure and dynamics of complexes of the uranyl ion with nonamethylimidodiphosphoramide (NIPA). 2. NMR studies of complexes (UO/sub 2/(NIPA)/sub 2/X)(CIO/sub 4/)/sub 2/ with X = H/sub 2/O, MeOH, EtOH, or Me/sub 2/CO

    SciTech Connect

    Rodehueser, L.; Rubini, P.R.; Bokolo, K.; Delpuech, J.J.

    1982-03-01

    The /sup 31/P and /sup 1/H spectra at -90/sup 0/C of the title uranyl complex ions (prepared as solutions of the solid perchlorates in inert anhydrous organic solvents (CH/sub 3/NO/sub 2/, CH/sub 2/Cl/sub 2/)) reveal a pentacoordinated arrangement of two symmetrically doubly bonded NIPA molecules and one solvent molecule about the uranyl group. In the case of (UO/sub 2/(NIPA)/sub 2/(EtOH))(ClO/sub 4/)/sub 2/, an intermolecular exchange between bound and free ethanol molecules is observed above -75/sup 0/C upon addition of ethanol to a solution of the complex. The observed rate law, k/sub inter/ = kK(EtOH)/(1 + K(EtOH) is accounted for by the existence of an outer-sphere complex (UO/sub 2//sup 2 +/(NIPA)/sub 2/(EtOH))EtOH in fast equilibrium (K) with the initial complex and free ethanol. The rate-determining step (k) consists of an outer-sphere to inner-sphere interchange of ethanol molecules. The thermodynamic and kinetic parameters are K(25/sup 0/C) = 15.8 dm/sup 3/ mol/sup -1/, k(25/sup 0/C) = 1.0 x 10/sup 4/s/sup -1/, ..delta..H and ..delta..H/sub inter//sup + +/ = -4.8 and 7.6 kcal mol/sup -1/, and ..delta..S and ..delta..S/sub inter//sup + +/ = 10.7 and -14.7 eu. A second exchange takes place at higher temperatures (above -30/sup 0/C) yielding full dynamic equivalence of the phosphorus nuclei of the coordinated NIPA molecules. The observed rate law k/sub intra/ = k/sub ex/(1 + K(EtOH)) reveals that the internal rearrangement of NIPA molecules occurs on the complex ion (UO/sub 2/(NIPA)/sub 2/(EtOH))/sup 2 +/ but not on the outer-sphere complex: k/sub ex/(25/sup 0/C) = 0.91 x 10/sup 3/s/sup -1/, ..delta..H/sub intra//sup + +/ = 10.6 kcal mol/sup -1/ and ..delta..S/sub intra//sup + +/ = -9.4 eu. Possible mechanisms for this exchange are discussed. 5 figures, 2 tables.

  6. Synthesis, structure, and dynamic properties of the lanthanum(III) complex of 1,4,7,10-tetrakis(2-carbamoylethyl)-1,4,7,10-tetraazacyclododecane

    SciTech Connect

    Morrow, J.R.; Amin, S.; Lake, C.H.; Churchill, M.R. )

    1993-10-13

    The synthesis, structure and dynamic properties of the lanthanum(III) complex of macrocycle 1 (1=1,4,7,10-tetrakis(2-carbamoylethyl)-1,4,7,10-tetraazacyclododecane) are reported. The eight-coordinate La[sup 3+] cation is encapsulated by the macrocyclic ligand and has a distorted square antiprismatic coordination geometry. The macrocyclic ligand coordinates strongly with the four oxygen atoms of the amide groups (average distance = 2.423 [+-] 0.032 [angstrom]) and weakly with the four nitrogen atoms within the macrocyclic ring (average distance = 2.718 [+-] 0.009 [angstrom]). The hydrogen atoms of the amide groups form a hydrogen-bonded system with the triflate counteranions. In acetonitrile or methanol solutions, [sup 13]C NMR resonances for the amide C(O) carbons in the complex are shifted by greater than 2 ppm from those of 1, suggesting that the amide groups are coordinated in these solvents. At low temperatures (O[degrees]C) the ethylenic groups of the 12-membered tetraazamacrocyclic are rigid on the NMR time scale. Variable-temperature [sup 13]C NMR studies suggest that rigidity of the macrocyclic is lost at higher temperatures. A dynamic process involving conformational changes about the cyclen ethylenic groups is consistent with [sup 13]C NMR data, and an activation barrier of 58.9 [+-] 0.3 kJ mol[sup [minus]1] is calculated for this process. A second dynamic process that averages protons on the amide nitrogens may involve free rotation about the amide C-N bond. An activation barrier of 69.8 [+-] 0.5 kJ mol[sup [minus]1] is calculated for this process for the lanthanum complex in dimethyl-d[sub 6] sulfoxide. The activation barrier calculated for the free ligand 1 is 70.5 [+-] 0.5 kJ mol[sup [minus]1]. The close correspondence of these values in conjunction with [sup 13]C NMR data for the amide C(O) resonance suggests that, in dimethyl sulfoxide solution, the amide groups of the complex are not bound.

  7. Synthesis and peferentially loading of nickel nanoparticle on CdS surface and its photocatalytic performance for hydrogen evolution under visible light

    SciTech Connect

    Li, Xiying; Wang, Hui; Chu, Tingting; Li, Danzhen; Mao, Liqun

    2014-09-15

    Graphical abstract: Ni nanoparticles were prepared via chemical reduction of aqueous NiCl{sub 2} by borohydride reducing agent in the presence of polyvinlylpyrolidone as a modifier to prevent fast growth of Ni crystals and their aggregation, and then preferentially deposited on (1 0 0), (0 0 2), and (1 0 1) crystal planes of CdS by photo-induced electrons while water splitting reaction occurred simultaneously. Resultant nickel nanoparticles have a size of about 3 nm, and contributes to decreasing the photoluminescence peak intensity of CdS, which means that nickel functions as the trapper of photo-generated electrons thereby quenching the photoluminescence of CdS. Therefore, nano-Ni/CdS photocatalyst with a Ni loading of 2.5% possesses the best visible-light catalytic activity for water splitting-hydrogen evolution and provides a hydrogen production rate of up to 9050 ?mol h{sup ?1} g{sup ?1}, while it exhibits stabilized activity towards H{sub 2} evolution as well. - Highlights: Ni nanoparticles are prepared by chemical reduction and then loaded on CdS surface by photo-reduction. Non-noble metal Ni nanoparticles (size: about 3 nm) act as co-catalyst for photocatalytic H{sub 2} evolution. Nano-Ni/CdS exhibits high activity (9050 ?mol h{sup ?1} g{sup ?1}) and perfect stability. - Abstract: Ni nanoparticles were prepared via chemical reduction of NiCl{sub 2} by NaBH{sub 4} in the presence of polyvinlylpyrolidone (PVP), and loaded on the surface of CdS by photo-induced electrons while water splitting reaction occurred simultaneously. Resultant Ni/CdS was characterized by high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultravioletvisible light diffuse reflectance spectrometry, and photoluminescence spectrometry. It was found that as-prepared Ni nanoparticles are about 3 nm, and preferentially deposited on (1 0 0), (0 0 2), and (1 0 1) crystal planes of CdS. Meanwhile, loading nickel decreases the

  8. Preparation, photoluminescent properties and luminescent dynamics of BaAlF{sub 5}:Eu{sup 2+} nanophosphors

    SciTech Connect

    Zhang, Wei; Hua, Ruinian; Liu, Tianqing; Zhao, Jun; Na, Liyan; Chen, Baojiu

    2014-12-15

    Graphical abstract: Rice-shaped BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF{sub 5}:Eu{sup 2+} are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu{sup 2+} was observed. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The strong ultraviolet emission of Eu{sup 2+} ions in BaAlF{sub 5}:Eu{sup 2+} nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via a mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu{sup 2+}-doped BaAlF{sub 5} nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF{sub 5}:Eu{sup 2+} nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF{sub 5}:Eu{sup 2+} nanophosphors exhibit the sharp line emissions of Eu{sup 2+} at room temperature. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu{sup 2+} can be deduced to be a dominant for quenching fluorescence in BaAlF{sub 5}:Eu{sup 2+} nanophosphors. The strong ultraviolet emission of Eu{sup 2+} in BaAlF{sub 5}:Eu{sup 2+} nanophosphors suggests that

  9. Molten Salt Fuel Version of Laser Inertial Fusion Fission Energy (LIFE)

    SciTech Connect

    Moir, R W; Shaw, H F; Caro, A; Kaufman, L; Latkowski, J F; Powers, J; Turchi, P A

    2008-10-24

    Molten salt with dissolved uranium is being considered for the Laser Inertial Confinement Fusion Fission Energy (LIFE) fission blanket as a backup in case a solid-fuel version cannot meet the performance objectives, for example because of radiation damage of the solid materials. Molten salt is not damaged by radiation and therefore could likely achieve the desired high burnup (>99%) of heavy atoms of {sup 238}U. A perceived disadvantage is the possibility that the circulating molten salt could lend itself to misuse (proliferation) by making separation of fissile material easier than for the solid-fuel case. The molten salt composition being considered is the eutectic mixture of 73 mol% LiF and 27 mol% UF{sub 4}, whose melting point is 490 C. The use of {sup 232}Th as a fuel is also being studied. ({sup 232}Th does not produce Pu under neutron irradiation.) The temperature of the molten salt would be {approx}550 C at the inlet (60 C above the solidus temperature) and {approx}650 C at the outlet. Mixtures of U and Th are being considered. To minimize corrosion of structural materials, the molten salt would also contain a small amount ({approx}1 mol%) of UF{sub 3}. The same beryllium neutron multiplier could be used as in the solid fuel case; alternatively, a liquid lithium or liquid lead multiplier could be used. Insuring that the solubility of Pu{sup 3+} in the melt is not exceeded is a design criterion. To mitigate corrosion of the steel, a refractory coating such as tungsten similar to the first wall facing the fusion source is suggested in the high-neutron-flux regions; and in low-neutron-flux regions, including the piping and heat exchangers, a nickel alloy, Hastelloy, would be used. These material choices parallel those made for the Molten Salt Reactor Experiment (MSRE) at ORNL. The nuclear performance is better than the solid fuel case. At the beginning of life, the tritium breeding ratio is unity and the plutonium plus {sup 233}U production rate is {approx}0

  10. Toxicological significance of renal Bcrp: Another potential transporter in the elimination of mercuric ions from proximal tubular cells

    SciTech Connect

    Bridges, Christy C. Zalups, Rudolfs K.; Joshee, Lucy

    2015-06-01

    Secretion of inorganic mercury (Hg{sup 2+}) from proximal tubular cells into the tubular lumen has been shown to involve the multidrug resistance-associated protein 2 (Mrp2). Considering similarities in localization and substrate specificity between Mrp2 and the breast cancer resistance protein (Bcrp), we hypothesize that Bcrp may also play a role in the proximal tubular secretion of mercuric species. In order to test this hypothesis, the uptake of Hg{sup 2+} was examined initially using inside-out membrane vesicles containing Bcrp. The results of these studies suggest that Bcrp may be capable of transporting certain conjugates of Hg{sup 2+}. To further characterize the role of Bcrp in the handling of mercuric ions and in the induction of Hg{sup 2+}-induced nephropathy, Sprague–Dawley and Bcrp knockout (bcrp{sup −/−}) rats were exposed intravenously to a non-nephrotoxic (0.5 μmol·kg{sup −1}), a moderately nephrotoxic (1.5 μmol·kg{sup −1}) or a significantly nephrotoxic (2.0 μmol·kg{sup −1}) dose of HgCl{sub 2}. In general, the accumulation of Hg{sup 2+} was greater in organs of bcrp{sup −/−} rats than in Sprague–Dawley rats, suggesting that Bcrp may play a role in the export of Hg{sup 2+} from target cells. Within the kidney, cellular injury and necrosis was more severe in bcrp{sup −/−} rats than in controls. The pattern of necrosis, which was localized in the inner cortex and the outer stripe of the outer medulla, was significantly different from that observed in Mrp2-deficient animals. These findings suggest that Bcrp may be involved in the cellular export of select mercuric species and that its role in this export may differ from that of Mrp2. - Highlights: • Bcrp may mediate transport of mercury out of proximal tubular cells. • Hg-induced nephropathy was more severe in Bcrp knockout rats. • Bcrp and Mrp2 may differ in their ability to transport Hg.

  11. Modeling Solute Thermokinetics in LiCI-KCI Molten Salt for Nuclear Waste Separation

    SciTech Connect

    Morgan, Dane; Eapen, Jacob

    2013-10-01

    Recovery of actinides is an integral part of a closed nuclear fuel cycle. Pyrometallurgical nuclear fuel recycling processes have been developed in the past for recovering actinides from spent metallic and nitride fuels. The process is essentially to dissolve the spent fuel in a molten salt and then extract just the actinides for reuse in a reactor. Extraction is typically done through electrorefining, which involves electrochemical reduction of the dissolved actinides and plating onto a cathode. Knowledge of a number of basic thermokinetic properties of salts and salt-fuel mixtures is necessary for optimizing present and developing new approaches for pyrometallurgical waste processing. The properties of salt-fuel mixtures are presently being studied, but there are so many solutes and varying concentrations that direct experimental investigation is prohibitively time consuming and expensive (particularly for radioactive elements like Pu). Therefore, there is a need to reduce the number of required experiments through modeling of salt and salt-fuel mixture properties. This project will develop first-principles-based molecular modeling and simulation approaches to predict fundamental thermokinetic properties of dissolved actinides and fission products in molten salts. The focus of the proposed work is on property changes with higher concentrations (up to 5 mol%) of dissolved fuel components, where there is still very limited experimental data. The properties predicted with the modeling will be density, which is used to assess the amount of dissolved material in the salt; diffusion coefficients, which can control rates of material transport during separation; and solute activity, which determines total solubility and reduction potentials used during electrorefining. The work will focus on La, Sr, and U, which are chosen to include the important distinct categories of lanthanides, alkali earths, and actinides, respectively. Studies will be performed using LiCl-KCl salt

  12. Effect of La{sub 2}O{sub 3}-treatment on textural and solid-solid interactions in ferric/cobaltic oxides system

    SciTech Connect

    Fagal, Gehan A.; Badawy, Abdelrahman A.; Hassan, Neven A.; El-Shobaky, Gamil A.

    2012-10-15

    Pure and La{sub 2}O{sub 3}-containing (0.75-3.0 mol%) Fe{sub 2}O{sub 3}/Co{sub 3}O{sub 4} solids were prepared by thermal treatment of their carbonates at 500-700 Degree-Sign C. The produced solids were characterized using XRD, HRTEM, EDX and nitrogen adsorption at -196 Degree-Sign C. The results revealed that pure solids calcined at 600 and 700 Degree-Sign C consisted of nanosized CoFe{sub 2}O{sub 4} phase, while pure mixed solids calcined at 500 Degree-Sign C consisted of trace amount of CoFe{sub 2}O{sub 4} and unreacted Fe{sub 2}O{sub 3}, Co{sub 3}O{sub 4} phases. The presence of 0.75 mol% La{sub 2}O{sub 3} enhanced solid-solid interaction between Fe{sub 2}O{sub 3} and Co{sub 3}O{sub 4} at 500 Degree-Sign C yielding CoFe{sub 2}O{sub 4}. The ferrite phase existed also in all mixed oxides upon treated with La{sub 2}O{sub 3} besides LaCoO{sub 3} phase. LaCoO{sub 3} existed as a major phase in all mixed oxides treated with 3 mol% La{sub 2}O{sub 3}. La{sub 2}O{sub 3}-treatment modified the crystallite size of all phases present to an extent dependent on calcination temperature and amount of La{sub 2}O{sub 3} content. This treatment decreased effectively the S{sub BET} of all mixed solids. - Graphical Abstract: TEM photographs of pure mixed oxides calcined at 500 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Cobalt ferrite exhibit chemical stability, low electric loss and high coercivity. Black-Right-Pointing-Pointer Cobalt ferrite is used in microwave devices, computer memories and magnetic storage. Black-Right-Pointing-Pointer Solid-solid interactions in ferric/cobaltic oxides system were investigated. Black-Right-Pointing-Pointer La{sub 2}O{sub 3}-treatment modified surface compositions of the system investigated. Black-Right-Pointing-Pointer All phases present in various solids existed as nanosized solids.

  13. Effects of O{sub 2} and SO{sub 2} on the Capture Capacity of a Primary-Amine Based Polymeric CO{sub 2} Sorbent

    SciTech Connect

    Hallenbeck, Alexander P; Kitchin, John R

    2013-08-01

    Post combustion CO{sub 2} capture is most commonly carried out using an amine solution that results in a high parasitic energy cost in the stripper unit due to the need to heat the water which comprises a majority of the amine solution. It is also well known that amine solvents suffer from stability issues due to amine leaching and poisoning by flue gas impurities. Solid sorbents provide an alternative to solvent systems that would potentially reduce the energy penalty of carbon capture. However, the cost of using a particular sorbent is greatly affected by the usable lifetime of the sorbent. This work investigated the stability of a primary amine-functionalized ion exchange resin in the presence of O{sub 2} and SO{sub 2}, both of which are constituents of flue gas that have been shown to cause degradation of various amines in solvent processes. The CO{sub 2} capture capacity was measured over multiple capture cycles under continuous exposure to two simulated flue gas streams, one containing 12 vol% CO{sub 2}, 4% O{sub 2}, 84% N{sub 2}, and the other containing 12.5 vol% CO{sub 2}, 4% O{sub 2}, 431 ppm SO{sub 2}, balance N{sub 2} using a custom-built packed bed reactor. The resin maintained its CO{sub 2} capture capacity of 1.31 mol/kg over 17 capture cycles in the presence of O{sub 2} without SO{sub 2}. However, the CO{sub 2} capture capacity of the resin decreased rapidly under exposure to SO{sub 2} by an amount of 1.3 mol/kg over 9 capture cycles. Elemental analysis revealed the resin adsorbed 1.0 mol/kg of SO{sub 2}. Thermal regeneration was determined to not be possible. The poisoned resin was, however, partially regenerated with exposure to 1.5M NaOH for 3 days resulting in a 43% removal of sulfur, determined through elemental analysis, and a 35% recovery of CO{sub 2} capture capacity. Evidence was also found for amine loss upon prolonged (7 days) continuous exposure to high temperatures (120 C) in air. It is concluded that desulfurization of the flue gas

  14. The adsorption and reaction of vinyl acetate on Au/Pd(100) alloy surfaces

    SciTech Connect

    Li, Zhenjun [Pacific Northwest National Laboratory (PNNL); Calaza, Florencia C [ORNL; Tysoe, Wilfred [University of Wisconsin, Milwaukee

    2012-01-01

    The surface chemistry of vinyl acetate monomer (VAM) is studied on Au/Pd(100) alloys as a function of alloy composition using temperature-programmed desorption and reflection adsorption infrared spectroscopy. VAM adsorbs weakly on isolated palladium sites on the alloy with a heat of adsorption of ~55 kJ/mol, with the plane of the VAM adsorbed close to parallel to the surface. The majority of the VAM adsorbed on isolated sites desorbs molecularly with only a small portion decomposing. At lower gold coverages (below ~0.5 ML of gold), where palladium palladium bridge sites are present, VAM binds to the surface in a distorted geometry via a rehybridized vinyl group. A larger proportion of this VAM decomposes and this reaction is initiated by C\\O bond scission in the VAM to form adsorbed acetate and vinyl species. The implication of this surface chemistry for VAM synthesis on Au/Pd(100) alloys is discussed.

  15. The Chemical Kinetics of Alkaline Extraction of Tellurium from Lead-Bismuth Eutectic

    SciTech Connect

    Laurence E. Auman; Eric P. Loewen; Thomas F. Gesell; Shuji Ohno

    2005-07-01

    Polonium-210 is an important radioactive product of neutron activation of molten lead-bismuth eutectic, a promising candidate coolant for advanced fast nuclear reactors. The radiological hazard potential associated with polonium can be significantly reduced by continuous online removal of polonium from the coolant. The removal method under investigation in this research is alkaline extraction. Chemical kinetic measurements were made to determine first and second order rate constants, activation energy, and heat of reaction at various temperatures using tellurium as a surrogate. First and second order alkaline extraction rate constants were measured to be: k1 = 10.05 e –52,274/RT and k2 = 167 e –97,224/RT. Alkaline extraction is dependent on temperature and was found to follow the Arrhenius rate law. The activation energy (Ea) ranged between 52,274 – 97,224 J mol-1. With a strong foundation of surrogate work completed, this work should be validated using polonium-210.

  16. High temperature creep of SiC densified using a transient liquid phase

    SciTech Connect

    Jou, Z.C.; Virkar, A.V. ); Cutler, R.A. )

    1991-09-01

    Silicon carbide-based ceramics can be rapidly densified above approximately 1850 {degree}C due to a transient liquid phase resulting from the reaction between alumina and aluminum oxycarbides. The resulting ceramics are fine-grained, dense, and exhibit high strength at room temperature. SiC hot pressed at 1875 {degree}C for 10 min in Ar was subjected to creep deformation in bending at elevated temperatures between 1500 and 1650 {degree}C in Ar. Creep was thermally activated with an activation energy of 743 kJ/mol. Creep rates at 1575 {degree}C were between 10{sup {minus}9}/s and 10{sup {minus}7}/s at an applied stress between 38 and 200 MPa, respectively, resulting in a stress exponent of {approx}1.7.

  17. Modeling of NOx Destruction Options for INEEL Sodium-Bearing Waste Vitrification

    SciTech Connect

    Wood, Richard Arthur

    2001-09-01

    Off-gas NOx concentrations in the range of 1-5 mol% are expected as a result of the proposed vitrification of sodium-bearing waste at the Idaho National Engineering and Environmental Laboratory. An existing kinetic model for staged combustion (originally developed for NOx abatement from the calcination process) was updated for application to vitrification offgas. In addition, two new kinetic models were developed to assess the feasibility of using selective non-catalytic reduction (SNCR) or high-temperature alone for NOx abatement. Each of the models was developed using the Chemkin code. Results indicate that SNCR is a viable option, reducing NOx levels to below 1000 ppmv. In addition, SNCR may be capable of simultaneously reducing CO emissions to below 100 ppmv. Results for using high-temperature alone were not as promising, indicating that a minimum NOx concentration of 3950 ppmv is achievable at 3344F.

  18. Radiation-Induced Decomposition of PETN and TATB under Extreme Conditions

    SciTech Connect

    Giefers, Hubertus; Pravica, Michael

    2008-11-03

    We conducted a series of experiments investigating decomposition of secondary explosives PETN and TATB at varying static pressures and temperatures using synchrotron radiation. As seen in our earlier work, the decomposition rate of TATB at ambient temperature slows systematically with increasing pressure up to at least 26 GPa but varies little with pressure in PETN at ambient temperature up to 15.7 GPa, yielding important information pertaining to the activation complex volume in both cases. We also investigated the radiation-induced decomposition rate as a function of temperature at ambient pressure and 26 GPa for TATB up to 403 K, observing that the decomposition rate increases with increasing temperature as expected. The activation energy for the TATB reaction at ambient temperature was experimentally determined to be 16 {+-} 3 kJ/mol.

  19. Thin-layer drying behavior of vegetable wastes from wholesale market

    SciTech Connect

    Lopez, A.; Iguaz, A.; Esnoz, A.; Virseda, P.

    2000-05-01

    The thin-layer drying behavior of vegetable wastes (as a mix of lettuce and cauliflower leaves) from wholesale market for a temperature range of 50--150 C was determined. Drying of this material was found to take part only in the falling-rate period. The experimental data were fitted to the simple exponential model and the Page model. Both models have good prediction capability. Effective diffusion coefficient varied from 6.03 x 10{sup {minus}9} to 3.15 x 10{sup {minus}8} m{sup 2}/s with an activation energy of diffusion of 19.82 kJ/mol. The temperature dependence of the effective diffusion coefficient was expressed by an Arrhenius-type relationship.

  20. Partial substitution of Mo{sup 6+} by S{sup 6+} in the fast oxide ion conductor La{sub 2}Mo{sub 2}O{sub 9}: Synthesis, structure and sulfur depletion

    SciTech Connect

    Mhadhbi, Noureddine; Corbel, Gwenaeel; Lacorre, Philippe; Bulou, Alain

    2012-06-15

    Powder-solid state reaction route using La{sub 2}(SO{sub 4}){sub 3} as sulfur source was used to prepare compositions of the solid solution La{sub 2}Mo{sub 2-y}S{sub y}O{sub 9}. Single phases were only obtained in the substitution range extending up to y=0.8 (40 mol% S) at the annealing temperature of 850 Degree-Sign C with regard to the limit of stability of the lanthanum sulphate reactant. Within the synthesis conditions, a stabilization of the high temperature {beta}-form is observed from and above y=0.1 (5 mol% S). Temperature-controlled X-ray diffraction and thermogravimetric analyses have shown that La{sub 2}Mo{sub 2-y}S{sub y}O{sub 9} raw powders undergo thermal decompositions in two steps. Heating above 900 Degree-Sign C, a sulfur depletion to the benefit of molybdenum in La{sub 2}Mo{sub 2-y}S{sub y}O{sub 9} raw powders leads to the formation of La{sub 2}SO{sub 6}. At higher temperature, the exsolved La{sub 2}SO{sub 6} phase then decomposes into La{sub 2}O{sub 3}, which in turn reacts with the sulfur-depleted La{sub 2}Mo{sub 2}O{sub 9} phase to form La{sub 2}MoO{sub 6}. The present study also reveals that depending on the substitution rate y, the sulfur depletion can be induced by ball-milling of raw powders. Along the La{sub 2}Mo{sub 2-y}S{sub y}O{sub 9} series, the isovalent substitution of molybdenum by sulfur tends to restrict in magnitude, or even to suppress above 400 Degree-Sign C, the distortive thermal expansion of the cubic {beta}-type structure, thus strongly decreasing the conductance at high temperature. - Graphical abstract: La{sub 2}O{sub 3}-MoO{sub 3}-'SO{sub 3}' ternary phase diagram showing the exsolution path at low temperature (white arrows) and the total decomposition path at high temperature (black arrows) of {beta}-La{sub 2}Mo{sub 2-y}S{sub y}O{sub 9} raw powders. Highlights: Black-Right-Pointing-Pointer Isovalent substitution of molybdenum by sulfur in La{sub 2}Mo{sub 2}O{sub 9} up to 40 mol%. Black

  1. Fluorohydrogenate Cluster Ions in the Gas Phase: Electrospray Ionization Mass Spectrometry of the [1-Ethyl-3-methylimidazolium+][F(HF)2.3] Ionic Liquid

    SciTech Connect

    Gary S. Groenewold; James E. Delmore; Michael T. Benson; Tetsuya Tsuda; Rika Hagiwara

    2013-12-01

    Electrospray ionization of the fluorohydrogenate ionic liquid [1-ethyl-3-methylimidazolium][F(HF)2.3] ionic liquid was conducted to understand the nature of the anionic species as they exist in the gas phase. Abundant fluorohydrogenate clusters were produced; however, the dominant anion in the clusters was [FHF-], and not the fluoride-bound HF dimers or trimers that are seen in solution. Density functional theory (DFT) calculations suggest that HF molecules are bound to the clusters by about 30 kcal/mol. The DFT-calculated structures of the [FHF-]-bearing clusters show that the favored interactions of the anions are with the methynic and acetylenic hydrogen atoms on the imidazolium cation, forming planar structures similar to those observed in the solid state. A second series of abundant negative ions was also formed that contained [SiF5-] together with the imidazolium cation and the fluorohydrogenate anions that originate from reaction of the spray solution with silicate surfaces.

  2. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    SciTech Connect

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; Zeng, Xiao Cheng; Gong, Bing

    2015-01-01

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of Kdimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. The persistent tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.

  3. Structural basis for thermostability revealed through the identification and characterization of a highly thermostable phosphotriesterase-like lactonase from Geobacillus stearothermophilus

    SciTech Connect

    Hawwa, Renda; Aikens, John; Turner, Robert J.; Santarsiero, Bernard D.; Mescar, Andrew D.

    2009-08-31

    A new enzyme homologous to phosphotriesterase was identified from the bacterium Geobacillus stearothermophilus (GsP). This enzyme belongs to the amidohydrolase family and possesses the ability to hydrolyze both lactone and organophosphate (OP) compounds, making it a phosphotriesterase-like lactonase (PLL). GsP possesses higher OP-degrading activity than recently characterized PLLs, and it is extremely thermostable. GsP is active up to 100 C with an energy of activation of 8.0 kcal/mol towards ethyl paraoxon, and it can withstand an incubation temperature of 60 C for two days. In an attempt to understand the thermostability of PLLs, the X-ray structure of GsP was determined and compared to those of existing PLLs. Based upon a comparative analysis, a new thermal advantage score and plot was developed and reveals that a number of different factors contribute to the thermostability of PLLs.

  4. Chemical solution deposition of ferroelectric yttrium-doped hafnium oxide films on platinum electrodes

    SciTech Connect

    Starschich, S.; Griesche, D.; Schneller, T.; Böttger, U.; Waser, R.

    2014-05-19

    Ferroelectric hafnium oxide films were fabricated by chemical solution deposition with a remnant polarization of >13 μC/cm{sup 2}. The samples were prepared with 5.2 mol. % yttrium-doping and the thickness varied from 18 nm to 70 nm. The hafnium oxide layer was integrated into a metal-insulator-metal capacitor using platinum electrodes. Due to the processing procedure, no thickness dependence of the ferroelectric properties was observed. To confirm the ferroelectric nature of the deposited samples, polarization, capacitance, and piezoelectric displacement measurements were performed. However, no evidence of the orthorhombic phase was found which has been proposed to be the non-centrosymmetric, ferroelectric phase in HfO{sub 2}.

  5. Palladium-coated zirconium membranes for oxidative extraction of hydrogen

    SciTech Connect

    Hsu, C.; Buxbaum, R.E.

    1987-01-01

    Palladium-coated metal membranes are attractive choices for low pressure, high temperature hydrogen and hydrogen isotope extractions, e.g. from fusion blanket fluids. The authors present experimental data on hydrogen transport through palladium-coated zirconium membranes at 600 - 700/sup 0/K. The upstream hydrogen pressure range is 10/sup -4/ to 10/sup -6/ torr and an oxygen-containing gas flows over the downstream side of the membrane. Thus, the irreversible oxidation reaction drives the flux. Deuterium permeabilities in zirconium are 2.00x10/sup -6/exp(59/T)+-20% g-mol/m.s.Pa/sup 1/2/, similar to the values obtained from diffusivity and solubility measurements. Extrapolated deuterium absorptive sticking coefficients on palladium are about .05.

  6. Size and charge effects of dopant M on the unit-cell parameters of monoclinic zirconia solid solutions Zr{sub 0.98}M{sub 0.02}O{sub 2{minus}{delta}} (M = Ce, La, Nd, Sm, Y, Er, Yb, Sc, Mg, Ca)

    SciTech Connect

    Yashima, Masatomo; Kakihana, Masato; Yoshimura, Masahiro; Hirose, Teruo; Suzuki, Yasuo

    1997-01-01

    The crystal structure of monoclinic phase [P2{sub 1}/c, Z = 4] has been refined by the Rietveld analysis of X-ray powder diffraction data to study the size and charge effects of dopant M{sup n+} on the unit-cell parameters of monoclinic ZrO{sub 2}-2 mol% MO{sub n/2} solid solutions (n = 4 for M = Ce; n = 3 for M = La, Nd, Sm, Y, Er, Yb, Sc; and n = 2 for M = Mg and Ca). For trivalent dopant (n = 3), the unit-cell parameters a{sub m}, b{sub m}, c{sub m} and unit-cell volume increase and {beta}{sub m} decreases with an increase of dopant size. Unit-cell volume increases with increasing of dopant charge n.

  7. Hydration of Kr(aq) in dilute and concentrated solutions

    DOE PAGES [OSTI]

    Chaudhari, Mangesh I.; Sabo, Dubravko; Pratt, Lawrence R.; Rempe, Susan B.

    2014-10-13

    Molecular dynamics simulations of water with both multi-Kr and single Kr atomic solutes are carried out to implement quasi-chemical theory evaluation of the hydration free energy of Kr(aq). This approach obtains free energy differences reflecting Kr–Kr interactions at higher concentrations. Those differences are negative changes in hydration free energies with increasing concentrations at constant pressure. The changes are due to a slight reduction of packing contributions in the higher concentration case. The observed Kr–Kr distributions, analyzed with the extrapolation procedure of Krüger et al., yield a modestly attractive osmotic second virial coefficient, B2 ≈ -60 cm3/mol. Moreover, the thermodynamic analysismore » interconnecting these two approaches shows that they are closely consistent with each other, providing support for both approaches.« less

  8. Dynamics of CN+alkane reactions by crossed-beam dc slice imaging

    SciTech Connect

    Huang Cunshun; Li Wen; Estillore, Armando D.; Suits, Arthur G.

    2008-08-21

    The hydrogen atom abstraction reactions of CN (X {sup 2}{sigma}{sup +}) with alkanes have been studied using the crossed molecular beam technique with dc slice ion imaging at collision energies of 7.5 and 10.8 kcal/mol. The product alkyl radical images were obtained via single photon ionization at 157 nm for the reactions of CN (X {sup 2}{sigma}{sup +}) with n-butane, n-pentane, n-hexane, and cyclohexane. From analysis of the images, we obtained the center-of-mass frame product angular distributions and translational energy distributions directly. The results indicate that the products are largely backscattered and that most of the available energy ({approx}80%-85%) goes to the internal energy of the products. The reaction dynamics is discussed in light of recent kinetics data, theoretical calculations, and results for related halogen and oxygen atom reactions.

  9. Viscosity correlations for binary supercritical fluids

    SciTech Connect

    Tilly, K.D.; Foster, N.R.; Macnaughton, S.J.; Tomasko, D.L. . School of Chemical Engineering and Industrial Chemistry)

    1994-03-01

    The viscosities and densities of supercritical mixtures of methanol, ethanol, n-propanol, isopropanol, n-pentane, n-hexane, n-heptane, and acetone in carbon dioxide, at concentrations between 1 and 5 mol %, were determined using a falling weight viscometer at pressures up to 240 bar and at temperatures between 313 and 328 K. The effects of pressure, temperature, cosolvent concentration, and the physical properties of the cosolvents on the mixture viscosity and density were examined. The viscosities and the densities of the mixtures were found to increase with the size, polarity, and concentration of the cosolvent molecule. The mixture viscosity was correlated with several empirical dense gas viscosity correlations. The best correlation was the Ely and Hanley technique modified with a density-dependent noncorrespondence factor. The Peng-Robinson equation of state was used to correlate the mixture densities.

  10. Catalytic Ionic Hydrogenation of Ketones by {[Cp*Ru(CO)2]2(? H)}+

    SciTech Connect

    Fagan, Paul J.; Voges, Mark H.; Bullock, R. Morris

    2010-02-22

    {[Cp*Ru(CO)2]2(? H)}+OTf functions as a homogeneous catalyst precursor for hydrogenation of ketones to alcohols, with hydrogenations at 1 mol % catalyst loading at 90 C under H2 (820 psi) proceeding to completion and providing >90% yields. Hydrogenation of methyl levulinate generates ?-valerolactone, presumably by ring-closing of the initially formed alcohol with the methyl ester. Experiments in neat Et2C=O show that the catalyst loading can be <0.1 mole %, and that at least 1200 turnovers of the catalyst can be obtained. These reactions are proposed to proceed by an ionic hydrogenation pathway, with the highly acidic dihydrogen complex [Cp*Ru(CO)2(?2-H2)]+OTf- being formed under the reaction conditions from reaction of H2 with {[Cp*Ru(CO)2]2(? H)}+OTf .

  11. Amorphization and crystallization processes of the ball-milled Al-Y-Fe-TM alloys (TM=Ni, Co, Cu, and Fe) (Prop. 2003-037)

    SciTech Connect

    Wilson, Timothy W.; Choo, Hahn; Porter, Wallace D; Speakman, Scott A; Fan, Chang; Liaw, Peter K

    2006-01-01

    High-energy ball milling was used to synthesize aluminum-based alloys containing amorphous and nanocrystalline phases to investigate the compositional effects of transition metals (TM) on the amorphization and crystallization processes of the ball-milled Al{sub 85}Y{sub 7}Fe{sub 5}TM{sub 3} alloys (TM = Ni, Co, Cu, and Fe) were investigated. The crystallization kinetics of the ball-milled Al-Y-Fe-TM nanocomposite powders were studied using differential scanning calorimetry (DSC). The DSC results of Al{sub 83}Y{sub 7}Fe{sub 5}Ni{sub 5} show that the crystallization temperature and the activation energy of crystallization are 668 K and 310 kJ/mol, respectively. In-situ high-temperature X-ray diffraction showed that the crystallization was a complex process involving growth of the nanocrystalline phase along with crystallization of the amorphous matrix phase.

  12. Phonon anharmonicity of monoclinic zirconia and yttrium-stabilized zirconia

    DOE PAGES [OSTI]

    Li, Chen W.; Smith, Hillary L.; Lan, Tian; Niedziela, Jennifer L.; Munoz, Jorge A.; Keith, J. Brian; Mauger, L.; Abernathy, Douglas L; Fultz, B.

    2015-04-13

    Inelastic neutron scattering measurements on monoclinic zirconia (ZrO2) and 8 mol% yttrium-stabilized zirconia were performed at temperatures from 300 to 1373 ωK. We reported temperature-dependent phonon densities of states (DOS) and Raman spectra obtained at elevated temperatures. First-principles lattice dynamics calculations with density functional theory gave total and partial phonon DOS curves and mode Grüneisen parameters. These mode Grüneisen parameters were used to predict the experimental temperature dependence of the phonon DOS with partial success. However, substantial anharmonicity was found at elevated temperatures, especially for phonon modes dominated by the motions of oxygen atoms. Yttrium-stabilized zirconia (YSZ) was somewhat moremore » anharmonic and had a broader phonon spectrum at low temperatures, owing in part to defects in its structure. YSZ also has a larger vibrational entropy than monoclinic zirconia.« less

  13. Phonon anharmonicity of monoclinic zirconia and yttrium-stabilized zirconia

    SciTech Connect

    Li, Chen W.; Smith, Hillary L.; Lan, Tian; Niedziela, Jennifer L.; Munoz, Jorge A.; Keith, J. Brian; Mauger, L.; Abernathy, Douglas L; Fultz, B.

    2015-04-13

    Inelastic neutron scattering measurements on monoclinic zirconia (ZrO2) and 8 mol% yttrium-stabilized zirconia were performed at temperatures from 300 to 1373 ωK. We reported temperature-dependent phonon densities of states (DOS) and Raman spectra obtained at elevated temperatures. First-principles lattice dynamics calculations with density functional theory gave total and partial phonon DOS curves and mode Grüneisen parameters. These mode Grüneisen parameters were used to predict the experimental temperature dependence of the phonon DOS with partial success. However, substantial anharmonicity was found at elevated temperatures, especially for phonon modes dominated by the motions of oxygen atoms. Yttrium-stabilized zirconia (YSZ) was somewhat more anharmonic and had a broader phonon spectrum at low temperatures, owing in part to defects in its structure. YSZ also has a larger vibrational entropy than monoclinic zirconia.

  14. Application of electron stimulated desorption techniques to measure the isotherm and the mean residence time of hydrogen physisorbed on a metal surface

    SciTech Connect

    Arakawa, Ichiro Shimizu, Hideyuki; Kawarabuki, Taku; Yamakawa, Koichiro; Miura, Takashi

    2015-03-15

    Electron stimulated desorption techniques were applied to probe the density of H{sub 2} physisorbed on a cold surface. The adsorption isotherm of H{sub 2} on a copper surface was measured in the equilibrium pressure range between 10{sup ?9} and 10{sup ?4} Pa at surface temperatures of 6.5 and 4.2?K. The mean residence times of H{sub 2} on copper were obtained from the observation of the time development of the surface density in a transitional state approaching equilibrium, and are 50500?s for the coverage between 1 and 0.18 at 4.2?K of the substrate temperature. The adsorption energies of 1.181.27?kJ/mol, and the condensation coefficient of 0.0740.018 were also deduced.

  15. Accessing siloxane functionalized polynorbornenes via vinyl-addition polymerization for CO2 separation membranes

    DOE PAGES [OSTI]

    Mahurin, Shannon Mark; Sokolov, Alexei P.; Saito, Tomonori; Long, Brian K.; Gmernicki, Kevin R.; Hong, Eunice; Maroon, Christopher R.

    2016-07-06

    Here, the vinyl addition polymerization of norbornylbased monomers bearing polar functional groups is often problematic, leading to low molecular weight polymers in poor yield. Herein, we provide proof-of-principle evidence that addition-type homopolymers of siloxane substituted norbornyl-based monomers may be readily synthesized using the catalyst trans-[Ni(C6F5)2(SbPh3)2]. Polymerizations using this catalyst reached moderate to high conversion in just 5 min of polymerization and produced siloxanesubstituted polymers with molecular weights exceeding 100 kg/mol. These polymers showed excellent thermal stability (Td ≥ 362 °C) and were cast into membranes that displayed high CO2 permeability and enhanced CO2/N2 selectivity as compared to related materials.

  16. Effect of CaF{sub 2} addition on optical properties of barium phosphate glasses

    SciTech Connect

    Kumar, N. Manoj Rao, G. Venkateswara Akhila, B. E. Shashikala, H. D.

    2014-04-24

    Ternary barium phosphate glasses, (50−X)BaO−XCaF{sub 2}−50P{sub 2}O{sub 5} have been prepared by adding 0-10 mol% of CaF{sub 2} to binary barium phosphate glasses. The amorphous nature of the prepared glasses was confirmed by X-ray diffraction technique. The UV-Visible absorption spectra have been recorded, optical band gap energy Eopt and Urbach energy Etail were determined. Shift in Eopt and Etail with increase in concentration of CaF{sub 2} is noted. FTIR analysis was carried out to investigate the short and intermediate-range orders in glasses. Shift of (P-O-P) band to higher wave number with the substitution of BaO with CaF{sub 2} shows the shortening of the phosphate chains. Hardness and density of glass samples were measured and correlated with the composition of glasses.

  17. Spectroscopic studies of silver boro tellurite glasses

    SciTech Connect

    Kumar, E. Ramesh Kumari, K. Rajani Rao, B. Appa Bhikshamaiah, G.

    2014-04-24

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI−Ag{sub 2}O−[(1−x)B{sub 2}O{sub 3}−xTeO{sub 2}] (x=0 to 1 mol% in steps of 0.2) glasses. The glassy nature of the compounds has been confirmed by X-ray diffraction. FTIR and Raman spectra were recorded for all samples at room temperature. FTIR spectra which provides the information about the change in bond structure of the glasses. Raman spectra provide the effect of TeO{sub 2} on SBT glass system is that as increasing the concentration of TeO{sub 2} the band intensity at 707 cm{sup −1} increase.

  18. Synthesis, characterization and hydrogen storage studies on porous carbon

    SciTech Connect

    Ruz, Priyanka Banerjee, Seemita; Sudarsan, V.; Pandey, M.

    2015-06-24

    Porous carbon sample has been prepared, using zeolite-Y as template followed by annealing at 800°C, with view to estimate the extent of hydrogen storage by the sample. Based on XRD, {sup 13}C MAS NMR and Raman spectroscopic studies it is confirmed that the porous Carbon sample contains only sp{sup 2} hybridized carbon. The hydrogen sorption isotherms have been recorded for the sample at 273, 223K and 123K and the maximum hydrogen absorption capacity is found to be 1.47wt% at 123K. The interaction energy of hydrogen with the carbon framework was determined to be ∼ 10 kJ mol{sup −1}at lower hydrogen uptake and gradually decreases with increase in hydrogen loading.

  19. Intermolecular interactions involving C-H bonds, 3, Structure and energetics of the interaction between CH{sub 4} and CN{sup {minus}}

    SciTech Connect

    Novoa, J.J.; Whangbo, Myung-Hwan; Williams, J.M.

    1991-12-31

    On the basis of SCF and single reference MP2 calculations, the full potential energy surface of the interaction between CH{sub 4} and CN{sup {minus}} was studied using extended basis sets of up to near Hartree-Fock limit quality. Colinear arrangements C-N{sup {minus}}{hor_ellipsis}H-CH{sub 3} and N-C{sup {minus}}{hor_ellipsis}H-CH{sub 3} are found to be the only two energy minima. The binding energies of these two structures are calculated to be 2.5 and 2.1 kcal/mol, respectively, at the MP2 level. The full vibrational analyses of two structures show a red shift of about 30 cm{sup {minus}1} for the v{sub s} C-H stretching.

  20. Stabilization of lead lithium iron tungstate with adding barium titanate

    SciTech Connect

    Lu, C.; Fang, B.

    1997-01-01

    The kinetics of formation, phase stabilities, and dielectric constants of Pb(Li{sub 1/4}Fe{sub 1/4}W{sub 1/2})O{sub 3} and BaTiO{sub 3}-added Pb(Li{sub 1/4}Fe{sub 1/4}W{sub 1/2})O{sub 3} have been compared. The addition of 2 mol{percent} BaTiO{sub 3} in Pb(Li{sub 1/4}Fe{sub 1/4}W{sub 1/2})O{sub 3} was confirmed to promote the complete formation of the perovskite phase at 700{degree}C. Also the thermal stability of the perovskite phase was significantly enhanced, which results in an increase of the dielectric permittivity. {copyright} {ital 1997 Materials Research Society.}

  1. Segregation of mass at the periphery of N -isopropylacrylamide-co-acrylic-acid microgels at high temperatures

    DOE PAGES [OSTI]

    Hyatt, John S.; Do, Changwoo; Hu, Xiaobo; Choi, Hong Sung; Kim, Jin Woong; Lyon, L. Andrew; Fernandez-Nieves, Alberto

    2015-09-29

    Here, we investigate poly(N-isopropylacrylamide) (pNIPAM) microgels randomly copolymerized with large mol % of protonated acrylic acid (AAc), finding that above the lower critical solution temperature the presence of the acid strongly disrupts pNIPAM's collapse, leading to unexpected new behavior at high temperatures. We see a dramatic increase in the ratio between the radius of gyration and the hydrodynamic radius above the theoretical value for homogeneous spheres, and a corresponding increase of the network length scale, which we attribute to the presence of a heterogeneous polymer distribution that forms due to frustration of pNIPAM's coil-to-globule transition by the AAc. Finally, wemore » analyze this phenomenon using a Debye-Bueche-like scattering contribution as opposed to the Lorentzian term often used, interpreting the results in terms of mass segregation at the particle periphery.« less

  2. Segregation of mass at the periphery of N -isopropylacrylamide-co-acrylic-acid microgels at high temperatures

    SciTech Connect

    Hyatt, John S.; Do, Changwoo; Hu, Xiaobo; Choi, Hong Sung; Kim, Jin Woong; Lyon, L. Andrew; Fernandez-Nieves, Alberto

    2015-09-29

    Here, we investigate poly(N-isopropylacrylamide) (pNIPAM) microgels randomly copolymerized with large mol % of protonated acrylic acid (AAc), finding that above the lower critical solution temperature the presence of the acid strongly disrupts pNIPAM's collapse, leading to unexpected new behavior at high temperatures. We see a dramatic increase in the ratio between the radius of gyration and the hydrodynamic radius above the theoretical value for homogeneous spheres, and a corresponding increase of the network length scale, which we attribute to the presence of a heterogeneous polymer distribution that forms due to frustration of pNIPAM's coil-to-globule transition by the AAc. Finally, we analyze this phenomenon using a Debye-Bueche-like scattering contribution as opposed to the Lorentzian term often used, interpreting the results in terms of mass segregation at the particle periphery.

  3. Effect of seawater temperature on uranium recovery from seawater using amidoxime adsorbents

    SciTech Connect

    Sekiguchi, Koji; Saito, Kyoichi; Konishi, Satoshi; Furusaki, Shintaro . Dept. of Chemical Engineering); Sugo, Takanobu . Takasaki Radiation Chemistry Research Establishment); Nobukawa, Hisashi . Dept. of Naval Architecture and Ocean Engineering)

    1994-03-01

    Porous amidoxime hollow fibers, which were prepared by radiation-induced graft polymerization of acrylonitrile onto porous polyethylene hollow fibers and subsequent amidoximation, were used as packing materials of the adsorption bed for uranium recovery from seawater. Seawater was forced to flow through the bed charged with the amidoxime hollow fibers either by pumping or by ocean current. Uranium concentration decay through the bed could be well correlated with residence time based on the adsorption rate expressed in terms of the overall mass-transfer coefficient. The resultant activation energy of 20 kcal/mol for uranium adsorption was indicative of the chelate formation of the amidoxime group with uranyl species as a rate-determining step.

  4. Thermodynamics of methane adsorption on copper HKUST-1 at low pressure

    SciTech Connect

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-06-11

    Metalorganic frameworks (MOFs) can be engineered as natural gas storage materials by tuning the pore structures and surface properties. Here we report the direct measurement of CH? adsorption enthalpy on a paddlewheel MOF (Cu HKUST-1) using gas adsorption calorimetry at 25 C at low pressures (below 1 bar). In this pressure region, the CH?CH? intermolecular interactions are minimized and the energetics solely reflects the CH?MOF interactions. Our results suggest moderately exothermic physisorption with an enthalpy of -21.1 1.1 kJ/mol CH? independent of coverage. The calorimetric investigation complements previous computational and crystallographic studies by providing zero coverage enthalpies of CH? adsorption. The analysis of the new and literature data suggests that in initial stages of adsorption the CH?HKUST-1 interaction tends to be more sensitive to the pore dimension than to the guest polarizability, suggesting a less specific chemical binding role for the open Cu site.

  5. Determination of enthalpies of formation of energetic molecules with composite quantum chemical methods

    DOE PAGES [OSTI]

    Manaa, M. Riad; Fried, Laurence E.; Kuo, I-Feng W.

    2016-02-01

    We report gas-phase enthalpies of formation for the set of energetic molecules NTO, DADE, LLM-105, TNT, RDX, TATB, HMX, and PETN using the G2, G3, G4, and ccCA-PS3 quantum composite methods. Calculations for HMX and PETN hitherto represent the largest molecules attempted with these methods. G3 and G4 calculations are typically close to one another, with a larger difference found between these methods and ccCA-PS3. Furthermore there is significant uncertainty in experimental values, the mean absolute deviation between the average experimental value and calculations are 12, 6, 7, and 3 kcal/mol for G2, G3, G4, and ccCA-PS3, respectively.

  6. THE OXYGEN PERMEATION PROPERTIES OF NANO CRYSTALLINE CEO2 THIN FILMS

    SciTech Connect

    Brinkman, K.

    2010-09-27

    The measurement of oxygen flux across nanocrystalline CeO{sub 2} cerium oxide thin films at intermediate temperature (650 to 800 C) is presented. Porous ceria support substrates were fabricated by sintering with carbon additions. The final dense film was deposited from an optimized sol-gel solution resulting in a mean grain size of 50 nm which displayed oxygen flux values of up to 0.014 {micro}mol/cm{sup 2}s over the oxygen partial pressure range from air to helium gas used in the measurement at 800 C. The oxygen flux characteristics confirm mixed ionic and electronic conductivity in nanocrystalline ceria films and demonstrate the role of size dependent materials properties as a design parameter in functional membranes for oxygen separation.

  7. The Acid Hydrolysis Mechanism of Acetals Catalyzed by a Supramolecular Assembly in Basic Solution

    SciTech Connect

    Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

    2008-09-24

    A self-assembled supramolecular host catalyzes the hydrolysis of acetals in basic aqueous solution. The mechanism of hydrolysis is consistent with the Michaelis-Menten kinetic model. Further investigation of the rate limiting step of the reaction revealed a negative entropy of activation ({Delta}S{double_dagger} = -9 cal mol{sup -1}K{sup -1}) and an inverse solvent isotope effect (k(H{sub 2}O)/k(D{sub 2}O) = 0.62). These data suggest that the mechanism of hydrolysis that takes place inside the assembly proceeds through an A-2 mechanism, in contrast to the A-1 mechanism operating in the uncatalyzed reaction. Comparison of the rates of acetal hydrolysis in the assembly with the rate of the reaction of unencapsulated substrates reveals rate accelerations of up to 980 over the background reaction for the substrate diethoxymethane.

  8. In situ characterization of strontium surface segregation in epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films as a function of oxygen partial pressure

    SciTech Connect

    Fister, Tim T.; Fong, Dillon D.; Eastman, Jeffrey A.; Baldo, Peter M.; Highland, Matthew J.; Fuoss, Paul H.; Balasubramaniam, Kavaipatti R.; Meador, Joanna C.; Salvador, Paul A.

    2008-10-13

    Using in situ synchrotron measurements of total reflection x-ray fluorescence, we find evidence of strontium surface segregation in (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films over a wide range of temperatures (25-900 deg. C) and oxygen partial pressures (pO{sub 2}=0.15-150 Torr). The strontium surface concentration is observed to increase with decreasing pO{sub 2}, suggesting that the surface oxygen vacancy concentration plays a significant role in controlling the degree of segregation. Interestingly, the enthalpy of segregation becomes less exothermic with increasing pO{sub 2}, varying from -9.5 to -2.0 kJ/mol. In contrast, the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} film thickness and epitaxial strain state have little impact on segregation behavior.

  9. Broadband sensitization of downconversion phosphor YPO{sub 4} by optimizing TiO{sub 2} substitution in host lattice co-doped with Pr{sup 3+}-Yb{sup 3+} ion-couple

    SciTech Connect

    Li, Kai-Yu; Liu, Li-Ying; Wang, Ru-Zhi Yan, Hui; Xiao, Si-Guo; Zhou, Hua

    2014-03-28

    This study demonstrates a feasible and efficient route to alleviate the absorption problem of the terrestrial solar spectrum and enhance broadband luminescence from a promising down conversion powder phosphor YPO{sub 4} co-doped with Pr{sup 3+}-Yb{sup 3+} lanthanide ion-couple: incorporating a third sensitizing transition metal ion, e.g., Ti{sup 4+}. The x-ray powder diffraction results confirm the lattice substitution by the solid-state reaction doping rather than the formation of any secondary phase. The emission spectral results and the luminescence decay curve analysis show that the downconversion luminescence can be enhanced by 200%300% and the quantum efficiency enhanced by more than 20% at the wavelength of around 980?nm, the best response spectrum for Si-based solar cells, by optimizing TiO{sub 2} doping concentration at 7?mol. %.

  10. Study on the electrochemical extraction of rare earth elements from FLINAK

    SciTech Connect

    Long, Dewu; Huang, Wei; Jiang, Feng; Tian, Lifang; Li, Qingnuan

    2013-07-01

    Electrochemical behaviors of rare earth elements, such as NdF{sub 3}, GdF{sub 3}, SmF{sub 3}, YF{sub 3}, and EuF{sub 3}, were investigated in a LiF-NaF-KF (46.5-11.5-42.0 mol %, FLINAK, m. p. 454 Celsius degrees) solvent. The results indicated that it is possible to extract Nd, Gd and Y directly by electrochemical deposition since the reductions of those cations to metal are located in the electrochemical window of the FLINAK eutectic, while the reductions of Sm and Eu metal are out of the range of the medium. Subsequently electro-deposition of Nd was carried out with two kinds of cathodic materials, namely, an inert cathode, Pt, and a reactive electrode, Cu. The collected products were characterized by various techniques revealing that a Nd-rich product was obtained. (authors)

  11. 100 MeV swift Si{sup 7+} ion induced thermoluminescence studies of nanocrystalline erbium doped ZrO{sub 2}

    SciTech Connect

    Lokesha, H. S.; Nagabhushana, K. R.; Singh, Fouran

    2015-06-24

    Pure and erbium (1mol%) doped nanocrystalline ZrO{sub 2} is synthesized by combustion technique. Thermoluminescence (TL) properties ZrO{sub 2}pellets annealed at 873 K and irradiated by 100 MeV swift Si{sup 7+} ion for various fluence are recorded. The evolution crystalline structure and crystallite size are done using by XRD data. Two TL glow curves, a well resolved one peak at ∼420 K and an unresolved with peak at ∼598 K are observed. TL intensity increases up to 3×10{sup 12} ions cm{sup −2} beyond which the TL intensity decreases. The glow peak shape method is used to calculate the TL trap parameter and discussed in this paper.

  12. Impact of Biodiesel on the Oxidation Kinetics and Morphology of Diesel Particulate

    SciTech Connect

    Strzelec, Andrea; Toops, Todd J; Daw, C Stuart

    2011-01-01

    We compare the oxidation characteristics of four different diesel particulates generated with a modern light-duty engine. The four particulates represent engine fueling with conventional ultra-low sulfur diesel (ULSD), biodiesel, and two intermediate blends of these fuels. The comparisons discussed here are based on complementary measurements implemented in a laboratory micro-reactor, including temperature programmed desorption and oxidation, pulsed isothermal oxidation, and BET surface area. From these measurements we have derived models that are consistent with the observed oxidation reactivity differences. When accessible surface area effects are properly accounted for, the oxidation kinetics of the fixed carbon components were found to consistently exhibit an Arrhenius activation energy of 113 6 kJ/mol. Release of volatile carbon from the as-collected particulate appears to follow a temperaturedependent rate law.

  13. Intermolecular triple proton and deuteron transfer in crystalline 3,5-dimethylpyrazole studied by NMR, NQR, and x-ray methods

    SciTech Connect

    Wehrle, B.; Aguilar-Parrilla, F.; Limbach, H.H. ); de la Concepcion Foces-Foces, M.; Cano, F.H. ); Elguero, J. ); Baldy, A.; Pierrot, M. ); Khurshid, M.M.T.; Larcombe-McDouall, J.B.; Smith, J.A.S. )

    1989-09-13

    A combination of {sup 13}C, {sup 15}N magnetic resonance, {sup 14}N quadrupole double resonance, and x-ray studies of solid 3,5-dimethylpyrazole between 270 and 350 K has shown that the NH...N hydrogen bond units present in the crystal are dynamically disordered, so that each nitrogen atom is on average attached to half a hydrogen atom. The molecules form discrete hydrogen-bonded cyclic trimers, in which the hydrogen atoms move in a double minimum potential energy surface which is symmetrical, to within experimental error. The experimental evidence in this temperature range is consistent with disorder by means of correlated triple hydrogen jumps with an activation energy of 45 kJ mol{sup {minus}1}. There is a large kinetic hydrogen (HHH)/deuterium (DDD) isotope effort of >20 at 299 K and equal to 8 at 347 K.

  14. Speciation of uranium in La{sub 2}Zr{sub 2}O{sub 7} pyrochlore by TRPLS

    SciTech Connect

    Mohapatra, M.; Rajeswari, B.; Hon, N. S.; Kadam, R. M. Natarajan, V.

    2015-06-24

    We discuss the speciation of uranium in lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7} =LZO) pyrochlore ceramic prepared via a gel-combustion route. Uranium concentration in the pyrochlore was optimized to 2 mol%. XRD and SEM experiments were carried out to assess the phase and homogeneity of the prepared samples. Time resolved photoluminescence (TRPLS) investigations were carried out for understanding the species stabilized in the pyrochlore host. It was observed that, uranium exists as uranate ion (UO{sub 6}{sup 6−}) in the zirconate host where it replaces the ‘Zr’ ions at its regular site with surrounding defect centers created for charge compensation.

  15. Multireference configuration interaction calculations of the first six ionization potentials of the uranium atom

    SciTech Connect

    Bross, David H.; Parmar, Payal; Peterson, Kirk A.

    2015-11-14

    The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set limit using new all-electron correlation consistent basis sets. The latter was carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons has been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. The final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV) and thus more reliable than the current experimental values of IP{sub 3} through IP{sub 6}.

  16. Infrared and Raman spectra, DFT-calculations and spectral assignments of germacyclohexane

    SciTech Connect

    Aleksa, V. Ozerenskis, D.; Pucetaite, M.; Sablinskas, V.; Cotter, C.; Guirgis, G. A.

    2015-03-30

    Raman spectra of germacyclohexane in liquid and solid states were recorded and depolarization data obtained. Infrared absorption spectra of the vapor and liquid have been studied. The wavenumbers of the vibrational modes were derived in the harmonic and anharmonic approximation in B3LYP/ccpVTZ calculations. According to the calculations, germacyclohexane exists in the stable chair conformation, whereas a possible twist form should have more than 15 kJ·mol{sup -1} higher enthalpy of formation what makes this conformer experimentally not observable. The 27 A' and 21 A'' fundamentals were assigned on the basis of the calculations and infrared and Raman band intensities, contours of gas phase infrared spectral bands and Raman depolarization measurements. An average discrepancy of ca. 0.77 % was found between the observed and the calculated anharmonic wavenumbers for the 48 modes. Substitution of carbon atom with Ge atom in the cyclohexane ring is reasoning flattening of the ring.

  17. Organotin piezo- and pyroelectric polymer films. [Synthesis, glass transition, and piezo- and pyroelectric activity

    SciTech Connect

    Liepins, R.; Timmons, M.L.; Morosoff, N.; Surles, J.

    1983-01-01

    The synthesis of a new class of piezo- and pyroelectrically active materials of various co- and terpolymers of tributylin methacrylate (TBTM) and trimethyltin methacrylate (TMTM) is described. A description of sample preparation, poling techniques, and measurement system is given in some detail. Films of the various polymer compositions were evaluated for tin current, glass transition temperature (Tg), crystallinity or ordering of the amorphous phase and piezo- and pytoelectric activity. Experimental results on 25 to 30 mol% TBTM/methyl methacrylate copolymers, which possessed good piezoelectric activity, antifouling properties and paint-formulation characteristics, are discussed in detail. Solvent-induced orientation effects that lead to piezoelectric activity in amorphous, unpoled, polymers are also described.

  18. Hydrogenated 5-carbon compound and method of making

    DOEpatents

    Elliott, D.C.; Frye, J.G.

    1999-03-16

    The present invention is based upon the surprising discovery that a 5-carbon compound selected from the group of 4-oxopentanoic acid, at least one lactone of 4-oxopentanoic acid, and combinations thereof, may be hydrogenated with a bimetallic catalyst of a noble metal in combination with a second metal and preserve the pendant methyl group. It was further unexpectedly discovered that the same conditions of bimetallic catalyst in the presence of hydrogen are useful for catalyzing the different intermediate reactions, for example, angelicalactone to gamma-valerolactone and gamma-valerolactone to 1,4-pentanediol. Finally, it was surprising that levulinic acid could be converted to 2-methyltetrahydrofuran with heating in the presence of the bimetallic catalyst and hydrogen in a single process vessel. The method of the present invention unexpectedly produced a fuel or fuel component having 2-methyltetrahydrofuran either in a yield greater than 4.5 mol % or in combination with alcohols. 8 figs.

  19. Hydrogenated 5-carbon compound and method of making

    DOEpatents

    Elliott, Douglas C.; Frye, John G.

    1999-01-01

    The present invention is based upon the surprising discovery that a 5-carbon compound selected from the group of 4-oxopentanoic acid, at least one lactone of 4-oxopentanoic acid, and combinations thereof, may be hydrogenated with a bimetallic catalyst of a noble metal in combination with a second metal and preserve the pendant methyl group. It was further unexpectedly discovered that the same conditions of bimetallic catalyst in the presence of hydrogen are useful for catalyzing the different intermediate reactions for example angelicalactone to gamma-valerolactone and gamma-valerolactone to 1,4-pentanediol. Finally, it was surprising that levulinic acid could be converted to 2-methyltetrahydrofuran with heating in the presence of the bimetallic catalyst and hydrogen in a single process vessel. The method of the present invention unexpectedly produced a fuel or fuel component having 2-methyltetrahydrofuran either in a yield greater than 4.5 mol % or in combination with alcohols.

  20. Non-covalent interactions of nitrous oxide with aromatic compounds: Spectroscopic and computational evidence for the formation of 1:1 complexes

    SciTech Connect

    Cao, Qian; School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 ; Gor, Gennady Y.; Krogh-Jespersen, Karsten; Khriachtchev, Leonid

    2014-04-14

    We present the first study of intermolecular interactions between nitrous oxide (N{sub 2}O) and three representative aromatic compounds (ACs): phenol, cresol, and toluene. The infrared spectroscopic experiments were performed in a Ne matrix and were supported by high-level quantum chemical calculations. Comparisons of the calculated and experimental vibrational spectra provide direct identification and characterization of the 1:1 N{sub 2}O-AC complexes. Our results show that N{sub 2}O is capable of forming non-covalently bonded complexes with ACs. Complex formation is dominated by dispersion forces, and the interaction energies are relatively low (about ?3 kcal mol{sup ?1}); however, the complexes are clearly detected by frequency shifts of the characteristic bands. These results suggest that N{sub 2}O can be bound to the amino-acid residues tyrosine or phenylalanine in the form of ? complexes.

  1. The oxidation-reduction kinetics of palladium powder

    SciTech Connect

    Munir, Z.A.; Coombs, P.G.

    1983-03-01

    The cyclic oxidation-reduction of submicrometer sized palladium powder was investigated over the temperature range 848 to 923 K. The total oxygen uptake decreased with increasing number of cycles as a consequence of sintering. Sintering was restricted to the reduction steps in these cycles. The relationships for the rate constants of the oxidation and reduction processes are, respectively, (1.04)10/sup 6/ exp(-(74.1)10/sup 3//RT), and (7.63)10/sup 12/ exp(-(207.9)10/sup 3//RT). The activation energies for the oxidation of palladium powder and the reduction of palladium oxide are 74.1 and 207.9 kJ mol/sup -1/, respectively.

  2. Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C

    DOE PAGES [OSTI]

    Wang, J.; Du, A.; Yang, Di; Raj, R.; Conrad, H.

    2013-01-01

    Tmore » he grain size dependence of the bulk resistivity of 3 mol% yttria-stabilized zirconia at 1400°C was determined from the effect of a dc electric field E a = 18.1  V/cm on grain growth and the corresponding electric current during isothermal annealing tests. Employing the brick layer model, the present annealing test results were in accordance with extrapolations of the values obtained at lower temperature employing impedance spectroscopy and 4-point-probe dc.he combined values give that the magnitude of the grain boundary resistivity ρ b = 133  ohm-cm.he electric field across the grain boundary width was 28–43 times the applied field for the grain size and current ranges in the present annealing test.« less

  3. Spin-torsion effects in the hyperfine structure of methanol

    SciTech Connect

    Coudert, L. H. Gutlé, C.; Huet, T. R.; Grabow, J.-U.; Levshakov, S. A.

    2015-07-28

    The magnetic hyperfine structure of the non-rigid methanol molecule is investigated experimentally and theoretically. 12 hyperfine patterns are recorded using molecular beam microwave spectrometers. These patterns, along with previously recorded ones, are analyzed in an attempt to evidence the effects of the magnetic spin-torsion coupling due to the large amplitude internal rotation of the methyl group [J. E. M. Heuvel and A. Dymanus, J. Mol. Spectrosc. 47, 363 (1973)]. The theoretical approach setup to analyze the observed data accounts for this spin-torsion in addition to the familiar magnetic spin-rotation and spin-spin interactions. The theoretical approach relies on symmetry considerations to build a hyperfine coupling Hamiltonian and spin-rotation-torsion wavefunctions compatible with the Pauli exclusion principle. Although all experimental hyperfine patterns are not fully resolved, the line position analysis yields values for several parameters including one describing the spin-torsion coupling.

  4. Structural investigation of MO⋅P{sub 2}O{sub 5}⋅Li{sub 2}O (MO = Fe{sub 2}O{sub 3} or V{sub 2}O{sub 5}) glass systems by FTIR spectroscopy

    SciTech Connect

    Andronache, Constantin I. Racolta, Dania

    2014-11-24

    Glasses from the systems xMO⋅(100−x)[P{sub 2}O{sub 5}⋅Li{sub 2}O] (MO = Fe{sub 2}O{sub 3} or V{sub 2}O{sub 5}) with 0 ≤ x ≤ mol % were prepared in the same conditions and characterized by IR spectroscopy. It was established the mode in which both Fe{sub 2}O{sub 3} and V{sub 2}O{sub 5} influences the local structure of these glasses. The iron ions generally modify in a different way the local structure of these glasses then vanadium ions. The results shown that phosphate units are the main structural units of glass system and the iron and vanadium ions are located in the network.

  5. Magnetic behavior of erbium-zinc-borate glasses and glass ceramics

    SciTech Connect

    Borodi, G.; Pascuta, P.; Bosca, M.; Pop, V.; Stefan, R.; Tetean, R.; Radulescu, D.

    2013-11-13

    Glasses of the system (Er{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} (3 ≤ x ≤ 15 mol%) were prepared by conventional melt quenching and subsequently converted to glass ceramics by heat treatment of glass samples at 860 °C for 2 h. The magnetic behaviour of the studied glasses and glass ceramics were investigated using a vibrating sample magnetometer (VSM) and a Faraday-type magnetic balance. Magnetic data show that erbium ions are involved in negative superexchange interactions in all the investigated samples, being antiferromagnetically coupled. For all studied samples the experimental values obtained for the effective magnetic moments are lower than the value corresponding to free Er{sup 3+} ions and decrease with the increasing of Er{sub 2}O{sub 3} content. The decrease is more pronounced in heat treated samples than untreated ones.

  6. Electrolyte optimization for cathodic growth of zinc oxide films

    SciTech Connect

    Izaki, Masanobu; Omi, Takashi

    1996-03-01

    Zinc oxide is of considerable interest to the optical and electronic industries, because of its electrical, optical, and acoustic characteristics. ZnO films can be prepared by several techniques, such as radio frequency (RF) magnetron sputtering, chemical vapor deposition, and molecular beam epitaxy. Preparation of oxide films by electrodeposition from aqueous solutions has several potential advantages over the other techniques. However, the formation of oxide films through electrochemical reactions have been demonstrated only on thallic oxide by Switzer and zirconium oxide by Gal-Or. In this work, the authors have prepared transparent ZnO films with optical bandgap energy of 3.3 eV by electrodeposition from an aqueous, 0.1 mol/liter zinc nitrate electrolyte. The deposition technology is still being developed. This paper reports the effects of the electrolyte concentration on the electrodeposition and properties of the ZnO films.

  7. Comparison of methods for leaching heavy metals from composts

    SciTech Connect

    Ciba, Jerzy; Zolotajkin, Maria; Kluczka, Joanna; Loska, Krzysztof; Cebula, Jan

    2003-07-01

    This paper presents the determination of total iron, copper, zinc, chromium, nickel, lead, cadmium and mercury contents in the compost obtained from sorted municipal organic solid waste applying the following methods of sample mineralization: 40% hydrofluoric acid with preliminary incineration of a sample, a mixture of concentrated nitric(V) and chloric(VII) acids with preliminary incineration of organic matter and a mixture of nitric(V) and chloric(VII) acids without sample incineration. The speciation analysis of Tessier was used to estimate the bioavailability of the metals. Elution degrees of the mobile forms of the metals from the compost with 10% nitric(V) acid and 1 mol/dm{sup 3} hydrochloric acid were compared. The contents of the elements in the eluates were determined applying atomic absorption spectrometry.

  8. Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

    SciTech Connect

    Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

    2011-06-20

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

  9. Catalytic hydroprocessing of chloropyridinols

    SciTech Connect

    Kim, D.I.; Allen, D.T. . Dept. of Chemical Engineering)

    1994-12-01

    The hydrodechlorination and hydrodeoxygenation of 2-chloro-3-pyridinol, 5-chloro-3-pyridinol, and 6-chloro-2-pyridinol were examined using a packed bed microreactor operating at 1,500 psi and at temperatures between 275 and 325 C. A commercial NiMo catalyst was used. Dechlorination to pyridinols was the dominant pathway with some subsequent deoxygenation. The overall rates and activation energies (18--35 kcal/mol) of dechlorination were comparable to the dechlorination rate parameters observed for chlorinated benzenes and chlorinated phenols, indicating that the pyridinic nitrogen has only a minor effect on dechlorination rates. Differences in dechlorination rates between the chloropyridinols were qualitatively explained based on the electron donating properties of the hydroxyl group and steric effects. Such studies are critical for evaluating the utility of catalytic hydroprocessing in waste management since waste streams are likely to contain a variety of contaminants and some chlorinated organics are multifunctional (e.g., chlorophenol).

  10. Spectroscopic properties of (PVA+ZnO):Mn{sup 2+} polymer films

    SciTech Connect

    Rani, Ch.; Raju, D. Siva; Bindu, S. Hima; Krishna, J. Suresh; Raju, Ch. Linga

    2015-05-15

    Electron Paramagnetic Resonance (EPR), optical absorption and infrared spectral studies have been carried out on Mn{sup 2+} ions doped in poly(vinyl alcohol) complexed with zinc oxide polymer films prepared by solution cast technique. The EPR spectra of 1 mol% Mn{sup 2+} ions doped polymer complex (PVA+ZnO) at room temperature exhibit sextet hyperfine structure (hfs), centered at 2.01. The spin-Hamiltonian parameter values indicate that the ground state of Mn{sup 2+} ion in d{sup 5} and the site symmetry around Mn{sup 2+} ions in tetragonally distorted octa hedral site. The optical absorption spectra exhibits two bands centered at 275nm at 437nm. The FTIR spectrum exhibits bands characteristic of stretching and banding vibrations of O-H, C-H and C=C groups.

  11. The reaction of acetylene with hydroxyl radicals.

    SciTech Connect

    Klippenstein, Stephen J.; Senosiain, Juan P.; Miller, James A.

    2005-02-01

    The potential energy surface for the reaction between OH and acetylene has been calculated using the RQCISD(T) method and extrapolated to the complete basis-set limit. Rate coefficients were determined for a wide range of temperatures and pressures, based on this surface and the solution of the one-dimensional and two-dimensional master equations. With a small adjustment to the association energy barrier (1.1 kcal/mol), agreement with experiments is good, considering the discrepancies in such data. The rate coefficient for direct hydrogen abstraction is significantly smaller than that commonly used in combustion models. Also in contrast to previous models, ketene + H is found to be the main product at normal combustion conditions. At low temperatures and high pressures, stabilization of the C{sub 2}H{sub 2}OH adduct is the dominant process. Rate coefficient expressions for use in modeling are provided.

  12. Effect of filler metal composition on the strength of yttria stabilized zirconia joints brazed with Pd-Ag-CuOx

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2008-09-08

    The Ag-CuOx system is of interest to be used to be used as an air braze filler metal for joining high temperature electrochemical devices. Previous work has shown that the melting temperatures can be increased by adding palladium to Ag-CuOx and it is expected that this may aid high temperature stability. This work compares the room temperature bend strength of joints made between yttria-stabilized zirconia (YSZ) air brazed using Ag-CuOx without palladium and with 5 and 15mol% palladium additions. It has been found that in general palladium decreases joint strength, especially in low copper oxide compositions filler metals. At high copper oxide contents, brittle fracture through both copper oxide rich phases and the YSZ limits joint strength.

  13. X-ray diffraction and electron microscope studies of yttria stabilized zirconia (YSZ) ceramic coatings exposed to vanadia. Master's thesis

    SciTech Connect

    Kondos, K.G.

    1992-09-01

    The U.S. Navy sometimes has the requirement to use low cost fuels containing significant amounts of vanadium and sulfur in gas turbine engines. Unfortunately the yttria stabilized zirconia (YSZ) witch is used as a thermal barrier coating on gas turbine blades can be severely attacked by vanadia. Powders of YSZ containing 8-mol% Y203 and pure zirconia containing various and mounts Of V205 were annealed at 900 deg. C. These were then examined by X-ray diffraction and electron microscopy, as well as single crystals of pure Zro2 and YSZ ( 20% Wt Y203 ) exposed to V205 Melts, to study how the vanadia degrades the YSZ by reacting with the stabilizer to form YVO4 and how the vanadium transforms the cubic and tetragonal YSZ crystal structures to monoclinic which degrades rapidly as a gas turbine blade coating.

  14. Transport properties of lithium- lead-vanadium-telluride glass and glass ceramics

    SciTech Connect

    Sathish, M.; Eraiah, B.

    2014-04-24

    Glasses with the chemical composition 35Li{sub 2}O-(45-x)V{sub 2}O{sub 5?}20PbO-xTeO{sub 2} (where x = 2.5, 5, 7.5, 10, 15 mol %) have prepared by conventional melt quenching method. The electrical conductivity of Li{sup +} ion conducting lead vanadium telluride glass samples has been carried out both as a function of temperature and frequency in the temperature range 503K-563K and over frequencies 40 Hz to 10 MHz. The electronic conduction has been observed in the present systems. When these samples annealed around 400C for 2hour become the glass ceramic, which also shows increase tendency of conductivity. SEM confines glass and glass ceramic nature of the prepared samples.

  15. Purification of 1-aminocyclopropane-1-carboxylate synthase from apple fruits using s-adenosyl (3,4 sup 14 C)-methionine (SAM) as a probe

    SciTech Connect

    Yip, Wingkip; Dong, Jianguo,; Yang, Shang Fa )

    1989-04-01

    Tomato ACC synthase is inactivated by its substrate SAM, with the moiety of aminobutyrate being covalently linked to ACC synthase during the catalytic reactions. A partial purified ACC synthase (the catalytic activity 100 {mu}mol/h{center dot}mg protein) from pellets of apple extract was incubated with (3,4{sup 14}C) SAM. Only one radioactive peak was revealed in a C-4 reverse phase HPLC and one radioactive band on SDS-PAGE with an M.W. of 48 kDa. Apple ACC synthase in native form is resistant to V8, {alpha}-chromtrypsin and carboxylpeptidase A digestion, but effectively inactivated by trypsin and ficin, as demonstrated by both the activity assay and SAM labeling. The radioactive protein cut from the SDS-PAGE was injected to three mice, two of the mice showed responses to the protein in western blot analysis. The antibodies from mice is currently under characterization.

  16. Poly(lactide)-block-poly([epsilon]-caprolactone-co-[epsilon]-decalactone)-block-poly(lactide) copolymer elastomers

    SciTech Connect

    Schneiderman, Deborah K.; Hill, Erin M.; Martello, Mark T.; Hillmyer, Marc A.

    2015-08-28

    Batch ring opening transesterification copolymerization of ?-caprolactone and ?-decalactone was used to generate statistical copolymers over a wide range of compositions and molar masses. Reactivity ratios determined for this monomer pair, rCL = 5.9 and rDL = 0.03, reveal ?-caprolactone is added preferentially regardless of the propagating chain end. Relative to poly(?-caprolactone) the crystallinity and melting point of these statistical copolymers were depressed by the addition of ?-decalactone; copolymers containing greater than 31 mol% (46 wt%) ?-decalactone were amorphous. Poly(lactide)-block-poly(?-caprolactone-co-?-decalactone)-block-poly(lactide) triblock polymers were also prepared and used to explore the influence of midblock composition on the temperature dependent Flory-Huggins interaction parameter (?). In addition, uniaxial extension tests were used to determine the effects of midblock composition, poly(lactide) content, and molar mass on the mechanical properties of these new elastomeric triblocks.

  17. Experiments of one-point cold fusion

    SciTech Connect

    Matsumoto, Takaaki )

    1993-11-01

    Experiments of one-point cold fusion have been performed by electrical discharging in ordinary and heavy water mixed with 0.6 mol/l potassium carbonate. A platinum pin anode was located perpendicular to a copper plate cathode. After discharge, the surfaces of the copper plates were examined by an optical microscope. Many ring spots caused by gravity decay of single and di-neutrons were separately distributed on the plates. Furthermore, several kinds of traces that might be produced by itonic hydrogen clusters and by tiny black and white holes were observed. The mechanisms of cold fusion by electrical discharge are also discussed in terms of the Nattoh model. 13 refs., 12 figs.

  18. Crystal structure and short-range oxygen defects in La- and Nd-modified ZrO{sub 2}

    SciTech Connect

    Loong, C.K.; Richardson, J.W. Jr.; Ozawa, M.; Kimura, M.

    1993-09-01

    The crystal structure of rare-earth modified zirconia and the associated oxygen defects were studied by neutron diffraction. A Rietveld analysis of the neutron powder patterns of heat treated samples of La- and Nd- 10mol%-ZrO{sub 2} revealed the composition of a major tetragonal phase (space group P4{sub 2}/nmc) and a minor cubic phase (space group Fm3m). The sort-range oxygen defects structure was examined by a Fourier-filtering technique. A real-space correlation function, obtained from a Fourier transform of the filtered residual diffuse scattering, showed evidence of static, oxygen-vacancy induced atomic displacements along the <111> and other directions of the pseudocubic cell.

  19. Microsoft Word - CR.doc

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    March 2004 Table 1. Estimated composition of REDOX HLW released from Tank 108 to the vadose zone in 1969 (from Jones et al., 2000). Temperature (° C) 100 H 2 O mole fraction 0.539 H 2 O weight fraction 0.304 Solution density (g/cm 3 ) 2.09 Ionic strength 18.02 Primary Chemical Species (mol/L) Al(OH) 4 - 3.36 K + 7.39 x 10 -2 Na + 19.6 OH - 5.25 NO 3 - 5.46 NO 2 - 4.42 Cl - 0.34 CO 3 2- 3.25 x 10 -2 SO 4 2- 2.77 x 10 -2 CrO 4 2- 4.13 x 10 -1 137 Cs + 6.51 x 10 -5 Table 1. Estimated composition

  20. Near-ambient X-ray photoemission spectroscopy and kinetic approach to the mechanism of carbon monoxide oxidation over lanthanum substituted cobaltites

    SciTech Connect

    Hueso, J. L.; Martinez-Martinez, D.; Cabalerro, Alfonso; Gonzalez-Elipe, Agustin Rodriguez; Mun, Bongjin Simon; Salmeron, Miquel

    2009-07-31

    We have studied the oxidation of carbon monoxide over a lanthanum substituted perovskite (La0.5Sr0.5CoO3-d) catalyst prepared by spray pyrolysis. Under the assumption of a first-order kinetics mechanism for CO, it has been found that the activation energy barrier of the reaction changes from 80 to 40 kJ mol-1 at a threshold temperature of ca. 320 oC. In situ XPS near-ambient pressure ( 0.2 torr) shows that the gas phase oxygen concentration over the sample decreases sharply at ca. 300 oC. These two observations suggest that the oxidation of CO undergoes a change of mechanism at temperatures higher than 300 oC.

  1. Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes

    SciTech Connect

    Shi, Yuanyuan; Kamasah, Alexander; Joalland, Baptiste; Suits, Arthur G.

    2015-05-14

    We report the reaction dynamics of F atom with selected alkanes studied by crossed beam scattering with DC slice ion imaging. The target alkanes are propane, n-butane, and n-pentane. The product alkyl radicals are probed by 157 nm single photon ionization following reaction at a collision energy of ∼10 kcal mol{sup −1}. The analyzed data are compared with the corresponding theoretical studies. Reduced translational energy distributions for each system show similar trends with little of the reaction exoergicity appearing in translation. However, the pentane reaction shows a somewhat smaller fraction of available energy in translation than the other two, suggesting greater energy channeled into pentyl internal degrees of freedom. The center-of-mass angular distributions all show backscattering as well as sharp forward scattering that decreases in relative intensity with the size of the molecule. Possible reasons for these trends are discussed.

  2. Photoluminescence, enhanced ferroelectric, and dielectric properties of Pr{sup 3+}-doped SrBi{sub 2}Nb{sub 2}O{sub 9} multifunctional ceramics

    SciTech Connect

    Zou, Hua; Yu, Yao; Li, Jun; Cao, Qiufeng; Wang, Xusheng; Hou, Junwei

    2015-09-15

    Pr{sup 3+}-doped SrBi{sub 2}Nb{sub 2}O{sub 9} (SBN) multifunctional ceramics were synthesized by the conventional solid state method. The photoluminescence (PL) excitation and emission spectra, enhanced ferroelectric and dielectric properties were investigated. The X-ray diffraction (XRD) and FESEM analyses indicated that the samples were simple phase and uniform flake-structure. Under the 250–350 nm ultraviolet (UV) excitations, the red emission was obtained and the optimal emission intensity was investigated when Pr doping level was 0.005 mol. With the increasing of the Pr{sup 3+} ion contents, the ferroelectric properties were enhanced obviously. As a new multifunctional material, the Pr{sup 3+}-doped SBN ceramics could be used for a wide range of application, such as integrated electro-optical devices.

  3. Catalytic Mechanism of Cellulose Degradation by a Cellobiohydrolase, CelS

    SciTech Connect

    Saharay, Moumita; Guo, Hong; Smith, Jeremy C

    2010-08-01

    The hydrolysis of cellulose is the bottleneck in cellulosic ethanol production. The cellobiohydrolase CelS from Clostridium thermocellum catalyzes the hydrolysis of cello-oligosaccharides via inversion of the anomeric carbon. Here, to examine key features of the CelS-catalyzed reaction, QM/MM (SCCDFTB/MM) simulations are performed. The calculated free energy profile for the reaction possesses a 19 kcal/mol barrier. The results confirm the role of active site residue Glu87 as the general acid catalyst in the cleavage reaction and show that Asp255 may act as the general base. A feasible position in the reactant state of the water molecule responsible for nucleophilic attack is identified. Sugar ring distortion as the reaction progresses is quantified. The results provide a computational approach that may complement the experimental design of more efficient enzymes for biofuel production.

  4. The glass transition temperature of glassy polymers using dynamic mechanical analysis

    SciTech Connect

    Rodriguez, E.L.

    1994-09-01

    Dynamic Mechanical Analysis (DMA) is presented for four glassy polymers. Poly(vinyl acetate), poly(vinyl chloride), poly(styrene), and poly(carbonate) were studied as a function of the heating rate using ramp and step heating programs and a constant frequency of 1 Hz. The effect of frequency on the dynamic mechanical parameters was also examined from 0.01 Hz to 10 Hz. The dynamic elastic storage modulus (E{double_prime}), the dynamic elastic loss modulus (E{double_prime}) and the tan{delta} (E{double_prime}/E{prime}) were affected by both the heating rate and the frequency. Apparent activation energies for the glass transition were also determined for the four polymers which were in the range from 98 of 194 kcal/mol.

  5. SOLICITATION, OFFER AND AWARD

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    SOLICITATION, OFFER AND AWARD !, TI11S COllT!<'}.l~f l8 AW.TEO ORDER Vr;OER O?>.$ (IS CfR TCO) fiATJtiG I 3 ~-DATE 1SSli[O ] Ii. RE,QU:siilO!i'f'lJRCl-'ASE !llcl/BC.R 15F:M002922 EMCHC U.S. Dep:1rl".!n0.nt of Energy EM Consoliciat.ed Businnss CeriLer 250 E:. Sth Str~at, S11ite 500 Cincinnnl.i Ofl 4S20~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - ---------- NOTE: fft1U]*4 b!d Ut(j!1\lo~1 *0Ntf"3od ''1lff£10('mol'1"bj.j*and._'"""'~"c'°~* - - -

  6. Communication: Towards the binding energy and vibrational red shift of the simplest organic hydrogen bond: Harmonic constraints for methanol dimer

    SciTech Connect

    Heger, Matthias; Suhm, Martin A.; Mata, Ricardo A.

    2014-09-14

    The discrepancy between experimental and harmonically predicted shifts of the OH stretching fundamental of methanol upon hydrogen bonding to a second methanol unit is too large to be blamed mostly on diagonal and off-diagonal anharmonicity corrections. It is shown that a decisive contribution comes from post-MP2 electron correlation effects, which appear not to be captured by any of the popular density functionals. We also identify that the major deficiency is in the description of the donor OH bond. Together with estimates for the electronic and harmonically zero-point corrected dimer binding energies, this work provides essential constraints for a quantitative description of this simple hydrogen bond. The spectroscopic dissociation energy is predicted to be larger than 18 kJ/mol and the harmonic OH-stretching fundamental shifts by about ?121 cm{sup ?1} upon dimerization, somewhat more than in the anharmonic experiment (?111 cm{sup ?1})

  7. Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

    SciTech Connect

    Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin; Othman, Norinsan Kamil

    2014-09-03

    Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm. Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.

  8. Computational Modeling of Degradation of Substituted Benzyltrimethyl Ammonium: Preprint

    SciTech Connect

    Long, H.; Pivovar, B. S.

    2014-09-01

    The degradation of cations on the alkaline exchange membranes is the major challenge for alkaline membrane fuel cells. In this paper, we investigated the degradation barriers by density functional theory for substituted benzyltrimethyl ammonium (BTMA+) cations, which is one of the most commonly used cations for alkaline exchange membranes. We found that substituted cations with electron-releasing substituent groups at meta-position of the benzyl ring could result in improved degradation barriers. However, after investigating more than thirty substituted BTMA+ cations with ten different substituent groups, the largest improvement of degradation barriers is only 1.6 kcal/mol. This implies that the lifetime of alkaline membrane fuel cells could increase from a few months to a few years by using substituted BTMA+ cations, an encouraging but still limited improvement for real-world applications.

  9. Complexation of Lanthanides with Nitrate at Variable Temperatures: Thermodynamics and Coordination Modes

    SciTech Connect

    Rao, Linfeng; Tian, Guoxin

    2008-12-10

    Complexation of neodymium(III) with nitrate was studied at variable temperatures (25, 40, 55 and 70 C) by spectrophotometry and microcalorimetry. The NdNO{sub 3}{sup 2+} complex is weak and becomes slightly stronger as the temperature is increased. The enthalpy of complexation at 25 C was determined by microcalorimetry to be small and positive, (1.5 {+-} 0.2) kJ {center_dot} mol{sup -1}, in good agreement with the trend of the stability constant at variable temperatures. Luminescence emission spectra and lifetime of Eu(III) in nitrate solutions suggest that inner-sphere and bidentate complexes form between trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) and nitrate in aqueous solutions. Specific Ion Interaction approach (SIT) was used to obtain the stability constants of NdNO{sub 3}{sup 2+} at infinite dilution and variable temperatures.

  10. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGES [OSTI]

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; et al

    2014-09-16

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of K-dimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. Furthermore, themore » persistent tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.« less

  11. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGES [OSTI]

    Kline, Mark A.; Wei, Xiaoxi; Horner, Ian J.; Liu, Rui; Chen, Shuang; Chen, Si; Yung, Ka Yi; Yamato, Kazuhiro; Cai, Zhonghou; Bright, Frank V.; et al

    2015-01-01

    As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of Kdimer > 1013 M-1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (-49.77 kcal mol-1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results in well-aligned tubular stacks. The persistentmore » tubular assemblies of 3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for 3.« less

  12. One-photon band gap engineering of borate glass doped with ZnO for photonics applications

    SciTech Connect

    Abdel-Baki, Manal; Abdel-Wahab, Fathy A.; El-Diasty, Fouad

    2012-04-01

    Lithium tungsten borate glass of the composition (0.56-x)B{sub 2}O{sub 3}-0.4Li{sub 2}O-xZnO-0.04WO{sub 3} (0 {<=}x{<=} 0.1 mol. %) is prepared for photonics applications. The glass is doped with ZnO to tune the glass absorption characteristics in a wide spectrum range (200-2500 nm). Chemical bond approach, including chemical structure, electronegativity, bond ionicity, nearest-neighbor coordination, and other chemical bonding aspect, is used to analyze and to explain the obtained glass properties such as: transmittance, absorption, electronic structure parameters (bandgap, Fermi level, and Urbach exciton-phonon coupling), Wannier free excitons excitation (applying Elliott's model), and two-photon absorption coefficient as a result of replacement of B{sub 2}O{sub 3} by ZnO.

  13. Design, installation, and operation of a remote hazard-warning system in west Texas; A case study

    SciTech Connect

    Seanard, K.C. ); McClurkin, C.C. )

    1992-04-01

    A major problem facing operators in the Permian Basin is the hydrogen sulfide (H{sub 2}S) associated with oil and gas production in populated areas. Population growth in the area has led to the encroachment of the once-small towns into the producing fields. This situation is potentially hazardous in areas of west Texas where the concentration of H{sub 2}S can range from 5 to 10 mol% of the produced gas. To protect the population living around these wells, it has become necessary, and in some circumstances mandatory, to install early warning systems to inform company personnel of problems on producing leases. This paper describes the process of designing, installing, and operating an early hazard-warning system to monitor the leases operated by Fina Oil and Chemical Co. in the Foster field in Ector County, TX.

  14. Selectivity Principles in Anion Separation by Crystallization of Hydrogen-Bonding Capsules

    SciTech Connect

    Custelcean, Radu; Bock, Aurelien; Moyer, Bruce A

    2010-01-01

    The fundamental factors controlling anion selectivity in the crystallization of hydrogen-bonding capsules [Mg(H2O)6][X L2] (X = SO42-, 1a; SeO42-, 1b; SO32-, 1c; CO32-, 1d; L = tris[2-(3-pyridylurea)ethyl]-amine) from water have been investigated by solution and solid-state thermodynamic measurements, anion competition experiments, and X-ray structural analysis. The crystal structures of 1a-d are isomorphous, thereby simplifying the interpretation of the observed selectivities based on differences in anion coordination geometries. The solubilities of 1a-d in water follow the order: 1a < 1b < 1c < 1d, which is consistent with the selectivity for the tetrahedral sulfate and selenate anions observed in competitive crystallization experiments. Crystallization of the capsules is highly exothermic, with the most favorable {Delta}H{sub cryst}{sup o} of -99.1 and -108.5 kJ/mol corresponding to SO42- and SeO42-, respectively, in agreement with the X-ray structural data showing shape complementarity between these tetrahedral anions and the urea-lined cavities of the capsules. Sulfite, on the other hand, has a significantly less negative {Delta}H{sub cryst}{sup o} of -64.6 kJ/mol, which may be attributed to its poor fit inside the capsules, involving repulsive interactions. The more favorable entropy of crystallization for this anion, however, partly offsets the enthalpic disadvantage, resulting in a solubility product very similar to that of the selenate complex. Because of their very similar shape and size, SO42- and SeO42- have a propensity to form solid solutions, which limits the selectivity between these two anions in competitive crystallizations. In the end, a comprehensive picture of contributing factors to anion selectivity in crystalline hydrogen-bonding capsules emerges.

  15. Supercritical water oxidation of landfill leachate

    SciTech Connect

    Wang Shuzhong; Guo Yang; Chen Chongming; Zhang Jie; Gong Yanmeng; Wang Yuzhen

    2011-09-15

    Highlights: > Thermal analysis of NH{sub 3} in supercritical water oxidation reaction. > Research on the catalytic reaction of landfill leachate by using response surface method. > Kinetic research of supercritical water oxidation of NH{sub 3} with and without MnO{sub 2} catalyst. - Abstract: In this paper, ammonia as an important ingredient in landfill leachate was mainly studied. Based on Peng-Robinson formulations and Gibbs free energy minimization method, the estimation of equilibrium composition and thermodynamic analysis for supercritical water oxidation of ammonia (SCWO) was made. As equilibrium is reached, ammonia could be totally oxidized in SCW. N{sub 2} is the main product, and the formation of NO{sub 2} and NO could be neglected. The investigation on SCWO of landfill leachate was conducted in a batch reactor at temperature of 380-500 deg. C, reaction time of 50-300 s and pressure of 25 MPa. The effect of reaction parameters such as oxidant equivalent ratio, reaction time and temperature were investigated. The results showed that COD and NH{sub 3} conversion improved as temperature, reaction time and oxygen excess increased. Compared to organics, NH{sub 3} is a refractory compound in supercritical water. The conversion of COD and NH{sub 3} were higher in the presence of MnO{sub 2} than that without catalyst. The interaction between reaction temperature and time was analyzed by using response surface method (RSM) and the results showed that its influence on the NH{sub 3} conversion was relatively insignificant in the case without catalyst. A global power-law rate expression was regressed from experimental data to estimate the reaction rate of NH{sub 3}. The activation energy with and without catalyst for NH{sub 3} oxidation were 107.07 {+-} 8.57 kJ/mol and 83.22 {+-} 15.62 kJ/mol, respectively.

  16. Leaching behavior of copper from waste printed circuit boards with Brnsted acidic ionic liquid

    SciTech Connect

    Huang, Jinxiu; Chen, Mengjun Chen, Haiyan; Chen, Shu; Sun, Quan

    2014-02-15

    Highlights: A Brnsted acidic ILs was used to leach Cu from WPCBs for the first time. The particle size of WPCBs has significant influence on Cu leaching rate. Cu leaching rate was higher than 99% under the optimum leaching conditions. The leaching process can be modeled with shrinking core model, and the E{sub a} was 25.36 kJ/mol. - Abstract: In this work, a Brnsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO{sub 4}), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1 g WPCBs powder was leached under the optimum conditions: particle size of 0.10.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70 C and 2 h. Copper leaching by [bmim]HSO{sub 4} can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol.

  17. A magnesium-carboxylate framework showing luminescent sensing for CS{sub 2} and nitroaromatic compounds

    SciTech Connect

    Wu, Zhao-Feng; Tan, Bin; Feng, Mei-Ling; Du, Cheng-Feng; Huang, Xiao-Ying

    2015-03-15

    A magnesium metal-organic framework compound, namely [NH{sub 2}(CH{sub 3}){sub 2}][Mg{sub 3}(NDC){sub 2.5}(HCO{sub 2}){sub 2}(DMF){sub 0.75}(H{sub 2}O){sub 0.25}]·1.25DMF·0.75H{sub 2}O (1) (H{sub 2}NDC=1,4-naphthalene dicarboxylic acid, DMF=N,N′-dimethylformamide), has been synthesized in solvothermal conditions and structurally characterized. It features a three-dimensionally anionic framework with aligned channels parallel to the b-axis. Luminescent studies indicated that it showed significant luminescence quenching for carbon disulfide (CS{sub 2}) and nitrobenzene after being activated, at a content of only 3.0 and 0.1 vol% in DMF, respectively. In addition, the activated sample showed sensitive luminescence quenching for 1,3,5-trinitrophenol with a low concentration of 5×10{sup −5} mol/L. - Graphical abstract: Presented is a microporous 3D Mg-MOF, namely, [NH{sub 2}(CH{sub 3}){sub 2}][Mg{sub 3}(NDC){sub 2.5}(HCO{sub 2}){sub 2}(DMF){sub 0.75}(H{sub 2}O){sub 0.25}]·1.25DMF·0.75H{sub 2}O (1) (H{sub 2}NDC=1,4-naphthalene dicarboxylic acid) showing significant luminescence quenching for carbon disulfide and nitrobenzene. - Highlights: • A microporous 3D metal-organic framework based on Mg. • The compound shows significant luminescence quenching for CS{sub 2} and nitrobenzene after activated. • The compound shows sensitive luminescence quenching for 1,3,5-trinitrophenol with a low concentration of 5×10{sup −5} mol/L.

  18. Metal-Organic Frameworks as Adsorbents for Hydrogen Purification and Precombustion Carbon Dioxide Capture

    SciTech Connect

    Herm, Zoey R; Swisher, Joe A; Smit, Berend; Krishna, Rajamani; Long, Jeffrey R

    2011-04-20

    Selected metal–organic frameworks exhibiting representative properties—high surface area, structural flexibility, or the presence of open metal cation sites—were tested for utility in the separation of CO₂ from H₂ via pressure swing adsorption. Single-component CO₂ and H₂ adsorption isotherms were measured at 313 K and pressures up to 40 bar for Zn₄O(BTB)₂ (MOF-177, BTB3- = 1,3,5-benzenetribenzoate), Be12(OH)12(BTB)₄ (Be-BTB), Co(BDP) (BDP2- = 1,4-benzenedipyrazolate), H₃[(Cu₄Cl)₃(BTTri)₈] (Cu-BTTri, BTTri3- = 1,3,5-benzenetristriazolate), and Mg₂(dobdc) (dobdc4- = 1,4-dioxido-2,5-benzenedicarboxylate). Ideal adsorbed solution theory was used to estimate realistic isotherms for the 80:20 and 60:40 H₂/CO₂ gas mixtures relevant to H₂ purification and precombustion CO₂ capture, respectively. In the former case, the results afford CO₂/H₂ selectivities between 2 and 860 and mixed-gas working capacities, assuming a 1 bar purge pressure, as high as 8.6 mol/kg and 7.4 mol/L. In particular, metal–organic frameworks with a high concentration of exposed metal cation sites, Mg₂(dobdc) and Cu-BTTri, offer significant improvements over commonly used adsorbents, indicating the promise of such materials for applications in CO₂}/H₂ separations.

  19. Tensile and compressive creep behavior of extruded Mg–10Gd–3Y–0.5Zr (wt.%) alloy

    SciTech Connect

    Wang, H.; Wang, Q.D.; Boehlert, C.J.; Yin, D.D.; Yuan, J.

    2015-01-15

    The tensile and compressive creep behavior of an extruded Mg–10Gd–3Y–0.5Zr (wt.%) alloy was investigated at temperatures ranging from 200 °C to 300 °C and under stresses ranging from 30 MPa to 120 MPa. There existed an asymmetry in the tensile and compressive creep properties. The minimum creep rate of the alloy was slightly greater in tension than in compression. The measured values of the transient strain and initial creep rate in compression were greater than those in tension. The creep stress exponent was approximately 2.5 at low temperatures (T < 250 °C) and 3.4 at higher temperatures both in tension and in compression. The compression creep activation energy at low temperatures and high temperatures was 83.4 and 184.3 kJ/mol respectively, while one activation energy (184 kJ/mol) represented the tensile–creep behavior over the temperature range examined. Dislocation creep was suggested to be the main mechanism in tensile creep and in the high-temperature regime in compressive creep, while grain boundary sliding was suggested to dominate in the low-temperature regime in compressive creep. Precipitate free zones were observed near grain boundaries perpendicular to the loading direction in tension and parallel to the loading direction in compression. Electron backscattered diffraction analysis revealed that the texture changed slightly during creep. Non-basal slip was suggested to contribute to the deformation after basal slip was introduced. In the tensile–creep ruptured specimens, intergranular cracks were mainly observed at general high-angle boundaries. - Highlights: • Creep behavior of an extruded Mg–RE alloy was characterized by EBSD. • T5 aging treatment enhanced the tension–compression creep asymmetry. • The grains grew slightly during tensile creep, but not for compressive creep. • Precipitate free zones (PFZs) were observed at specific grain boundaries. • Intergranular fracture was dominant and cracks mainly originated at

  20. Temperature dependent dielectric and conductivity studies of polyvinyl alcohol-ZnO nanocomposite films by impedance spectroscopy

    SciTech Connect

    Hemalatha, K. S.; Damle, R.; Rukmani, K.; Sriprakash, G.; Ambika Prasad, M. V. N.

    2015-10-21

    Dielectric and conductivity behaviors of nano ZnO doped polyvinyl alcohol (PVA) composites for various concentrations of dopant were investigated using impedance spectroscopy for a wide range of temperatures (303 K–423 K) and frequencies (5 Hz–30 MHZ). The dielectric properties of host polymer matrix have been improved by the addition of nano ZnO and are found to be highly temperature dependent. Anomalous dielectric behavior was observed in the frequency range of 2.5 MHz–5 MHz. Increase in dielectric permittivity and dielectric loss was observed with respect to temperature. The Cole-Cole plot could be modeled by low resistance regions in a high resistance matrix and the lowest resistance was observed for the 10 mol. % films. The imaginary part of the electric modulus showed asymmetric peaks with the relaxation following Debye nature below and non-Debye nature above the peaks. The ac conductivity is found to obey Jonscher's power law, whereas the variation of dc conductivity with temperature was found to follow Arrhenius behavior. Two different activation energy values were obtained from Arrhenius plot indicating that two conduction mechanisms are involved in the composite films. Fitting the ac conductivity data to Jonscher's law indicates that large polaron assisted tunneling is the most likely conduction mechanism in the composites. Maximum conductivity is observed at 423 K for all the samples and it is optimum for 10 mol. % ZnO doped PVA composite film. Significant increase in dc and ac conductivities in these composite films makes them a potential candidate for application in electronic devices.

  1. Effect of hydroxamate siderophores on Fe release and Pb(II) adsorption by goethite

    SciTech Connect

    Kraemer, Stephan M.; Cheah, Sing-Foong; Zapf, Rita; Xu, Jide; Raymond, Kenneth N.; Sposito, Garrison

    1998-08-01

    Hydroxamate siderophores are biologically-synthesized, Fe(III)-specific ligands which are common in soil environments. In this paper, we report an investigation of their adsorption by the iron oxyhydroxide, goethite; their influence on goethite dissolution kinetics; and their ability to affect Pb(II) adsorption by the goethite surface. The siderophores used were desferrioxamine B (DFO-B), a fungal siderophore, and desferrioxamine D1, an acetyl derivative of DFO-B (DFO-D1). Siderophore adsorption isotherms yielded maximum surface concentrations of 1.5 (DFO-B) or 3.5 (DFO-D1) mu-mol/g at pH 6.6, whereas adsorption envelopes showed either cation-like (DFO-B) or ligand-like (DFO-D1) behavior. Above pH 8, the adsorbed concentrations of both siderophores were similar. The dissolution rate of goethite in the presence of 240 mu M DFO-B or DFO-D1 was 0.02 or 0.17 mu-mol/g hr, respectively. Comparison of these results with related literature data on the reactions between goethite and acetohydroxamic acid, a monohydroxamate ligand, suggested that the three hydroxamate groups in DFO-D1 coordinate to Fe(III) surface sites relatively independently. The results also demonstrated a significant depleting effect of 240 mu-M DFO-B or DFO-D1 on Pb(II) adsorption by goethite at pH > 6.5, but there was no effect of adsorbed Pb(II) on the goethite dissolution rate.

  2. On the thermal stability of physical vapor deposited oxide-hardened nanocrystalline gold thin films

    SciTech Connect

    Argibay, Nicolas; Mogonye, J. E.; Michael, Joseph R.; Goeke, Ronald S.; Kotula, Paul G.; Scharf, T. W.; Dugger, Michael Thomas; Prasad, Somuri V.

    2015-04-08

    We describe a correlation between electrical resistivity and grain size for PVD synthesized polycrystalline oxide-hardened metal-matrix thin films in oxide-dilute (<5 vol. % oxide phase) compositions. The correlation is based on the Mayadas-Shatzkes (M-S) electron scattering model, predictive of grain size evolution as a function of composition in the oxide-dilute regime for 2 ?m thick Au-ZnO films. We describe a technique to investigate grain boundary (GB) mobility and the thermal stability of GBs based on in situelectrical resistivity measurements during annealing experiments, interpreted using a combination of the M-S model and the Michels et al. model describing solute drag stabilized grain growth kinetics. Using this technique, activation energy and pre-exponential Arrhenius parameter values of Ea = 21.6 kJ/mol and Ao = 2.3 1017 m2/s for Au-1 vol. % ZnO and Ea =12.7 kJ/mol and Ao = 3.1 1018 m2/s for Au-2 vol.% ZnO were determined. In the oxide-dilute regime, the grain size reduction of the Au matrix yielded a maximum hardness of 2.6 GPa for 5 vol. % ZnO. A combined model including percolation behavior and grain refinement is presented that accurately describes the composition dependent change in electrical resistivity throughout the entire composition range for Au-ZnO thin films. As a result, the proposed correlations are supported by microstructural characterization using transmission electron microscopy and electron diffraction mapping for grain size determination.

  3. Dynamics of the reaction of C{sub 2} with C{sub 6}H{sub 2}: An implication for the formation of interstellar C{sub 8}H

    SciTech Connect

    Sun, Yi-Lun; Huang, Wen-Jian; Chin, Chih-Hao; Lee, Shih-Huang

    2014-11-21

    The reaction C{sub 2} + C{sub 6}H{sub 2} → C{sub 8}H + H was investigated for the first time. Reactant C{sub 2} (C{sub 6}H{sub 2}) was synthesized from 1% C{sub 3}F{sub 6}/He (5% C{sub 2}H{sub 2}/He) by pulsed high-voltage discharge. We measured the translational-energy distribution, the angular distribution, and the photoionization spectrum of product C{sub 8}H in a crossed molecular-beam apparatus using synchrotron vacuum-ultraviolet ionization. This reaction released average translational energy of 8.5 kcal mol{sup −1} corresponding to a fraction of 0.37 in translation. C{sub 8}H was identified as octatetranyl based on the maximal translational-energy release 23 ± 2 kcal mol{sup −1} and the ionization threshold 8.9 ± 0.2 eV. Kinematic constraints can qualitatively account for the nearly isotropic angular distribution. The quantum-chemical calculations indicate that the exothermic reactions C{sub 2} (X {sup 1}Σ{sub g}{sup +}/a {sup 3}Π{sub u}) + HC{sub 6}H → C{sub 8}H + H can proceed without entrance and exit barriers, implying the importance in the cold interstellar medium. This work verifies that interstellar C{sub 8}H can be formed through the C{sub 2} + C{sub 6}H{sub 2} reaction.

  4. Effects of lithium salt concentration on graphited carbon microbead anodes in the piperidinium-based hybrid electrolytes

    SciTech Connect

    Gao, Kun; Li, Shu-Dan

    2015-01-15

    Graphical abstract: “Lithium aggregates” usually cause a significant decrease in Li{sup +} mobility and transfer efficiency. Therefore, as important as the problem of SEI, the content of lithium salt and the interaction between Li{sup +} and ILs’ anions should be taken into consideration in the optimization of ILs-based electrolytes for Li-ion batteries. - Highlights: • “Lithium aggregates” in piperidinium-based electrolytes are evidenced by IR and NMR. • High LiPF{sub 6} content could decrease Li{sup +} mobility due to “ionic aggregates”. • Lithium salt concentration is an important factor affecting graphite performances. - Abstract: The variations in LiPF{sub 6} concentration lead to the very different electrochemical performances of carbon microbeads anodes in the piperidinium-based hybrid electrolytes. The “two peaks” behaviors of lithium plating observed in cyclic voltammetry tests, and some detailed changes in infrared spectra and nuclear magnetic resonance indicates that the formation of “ionic aggregates” related to lithium ions”. Therefore, the excessive lithium salts in the piperidinium-based hybrid electrolytes, usually cause a significant decrease in Li{sup +} mobility and transfer efficiency. The main behaviors are that, when LiPF{sub 6} concentrations increased from 0.2 to 1.2 mol kg{sup −1}, the apparent migration energies (E{sub a}) increase largely from 8.83 to 21.16 kJ mol{sup −1}, while the lithium transference numbers (t{sub Li{sup +}}) drop markedly from 0.538 to 0.292.

  5. Chemical modification and inactivation of rat liver microsomal cytochrome P-450c by 2-bromo-4'-nitroacetophenone

    SciTech Connect

    Parkinson, A.; Ryan, D.E.; Thomas, P.E.; Jerina, D.M.; Sayer, J.M.; van Bladeren, P.J.; Haniu, M.; Shively, J.E.; Levin, W.

    1986-09-05

    The alkylating agent 2-bromo-4'-nitroacetophenone (BrNAP) binds covalently to each of 10 isozymes of purified rat liver microsomal cytochrome P-450 (P-450a-P-450j) but substantially inhibits the catalytic activity of only cytochrome P-450c. Regardless of pH, incubation time, presence of detergents, or concentration of BrNAP, treatment of cytochrome P-450c with BrNAP resulted in no more than 90% inhibition of catalytic activity. Alkylation with BrNAP did not cause the release of heme from the holoenzyme or alter the spectral properties of cytochrome P-450c, data that exclude the putative heme-binding cysteine, Cys-460, as the major site of alkylation. Two residues in cytochrome P-450c reacted rapidly with BrNAP, for which reason maximal loss of catalytic activity was invariably associated with the incorporation of approximately 1.5 mol of BrNAP/mol of cytochrome P-450c. Two major radio-labeled peptides were isolated from a tryptic digest of (/sup 14/CC)BrNAP-treated cytochrome P-450c by reverse-phase high performance liquid chromatography. The amino acid sequence of each peptide was determined by microsequence analysis, but the identification of the residues alkylated by BrNAP was complicated by the tendency of the adducts to decompose when subjected to automated Edman degradation. However, results of competitive binding experiments with the sulfhydryl reagent 4,4'-dithiodipyridine identified Cys-292 as the major site of alkylation and Cys-160 as the minor site of alkylation by BrNAP in cytochrome P-450c.

  6. One Year Clinical Outcomes of Renal Artery Stenting: The Results of ODORI Registry

    SciTech Connect

    Sapoval, M.; Tamari, I.; Goffette, P.; Downes, M.; Senechal, Q.; Fanelli, F.; Reimer, P.; Negaiwi, Z.; Cassin, P. De; Heye, S.; Korobov, V.; Tsetis, D.; Abada, H.

    2010-06-15

    The safety, efficacy and long term clinical benefits of renal artery revascularization by stenting are still a matter of debate. The aim of our study was to define the safety and efficacy of renal artery stenting with the Tsunami peripheral stent (Terumo Corporation, Tokyo, Japan). The ODORI was a prospective, multicentre registry which enrolled 251 consecutive patients, (276 renal arteries) in 36 centres across Europe. The primary endpoint was acute procedural success defined as <30% residual stenosis after stent placement. Secondary endpoints included major adverse events, blood pressure control, serum creatinine level, and target lesion revascularization (TLR) at 6 and 12 months. Patients were 70 {+-} 10 years old, 59% were male, 33% had diabetes, and 96% hypertension. The main indications for renal stent implantation were hypertension in 83% and renal salvage in 39%. Direct stent implantation was performed in 76% of the cases. Acute success rate was 100% with residual stenosis of 2.5 {+-} 5.4%. Systolic/diastolic blood pressure decreased from a mean of 171/89 at baseline to 142/78 mmHg at 6 months (p < 0.0001 vs. baseline), and 141/80 mmHg at 12 months (p < 0.0001 vs. baseline). Mean serum creatinine concentration did not change significantly in the total population. However, there was significant improvement in the highest tercile (from 283 {mu}mol/l at baseline to 205 and 209 {mu}mol/l at 6 and 12 months respectively). At 12-months, rates of restenosis and TLR were 6.6 and 0.8% respectively. The 12 month cumulative rate of all major clinical adverse events was 6.4% while the rate of device or procedure related events was 2.4%. In hypertensive patients with atherosclerotic renal artery stenosis Tsunami peripheral balloon-expandable stent provides a safe revascularization strategy, with a potential beneficial impact on hypertension control and renal function in the highest risk patients.

  7. The Edgewater Coolside process demonstration

    SciTech Connect

    McCoy, D.C.; Scandrol, R.O.; Statnick, R.M.; Stouffer, M.R.; Winschel, R.A.; Withum, J.A.; Wu, M.M.; Yoon, H. )

    1992-02-01

    The Edgewater Coolside process demonstration met the program objectives which were to determine Coolside SO[sub 2] removal performance, establish short-term process operability, and evaluate the economics of the process versus a limestone wet scrubber. On a flue gas produced from the combustion of 3% sulfur coal, the Coolside process achieved 70% SO[sub 2] removal using commercially-available hydrated lime as the sorbent. The operating conditions were Ca/S mol ratio 2.0, Na/Ca mol ratio 0.2, and 20[degree]F approach to adiabatic saturation temperature ([del]T). During tests using fresh plus recycle sorbent, the recycle sorbent exhibited significant capacity for additional SO[sub 2] removal. The longest steady state operation was eleven days at nominally Ca/S = 2, Na/Ca = 0.22, [del]T = 20--22[degree]F, and 70% SO[sub 2] removal. The operability results achieved during the demonstration indicate that with the recommended process modifications, which are discussed in the Coolside process economic analysis, the process could be designed as a reliable system for utility application. Based on the demonstration program, the Coolside process capital cost for a hypothetical commercial installation was minimized. The optimization consisted of a single, large humidifier, no spare air compressor, no isolation dampers, and a 15 day on-site hydrated lime storage. The levelized costs of the Coolside and the wet limestone scrubbing processes were compared. The Coolside process is generally economically competitive with wet scrubbing for coals containing up to 2.5% sulfur and plants under 350 MWe. Site-specific factors such as plant capacity factor, SO[sub 2] emission limit, remaining plant life, retrofit difficulty, and delivered sorbent cost affect the scrubber-Coolside process economic comparison.

  8. The Edgewater Coolside process demonstration

    SciTech Connect

    McCoy, D.C.; Scandrol, R.O.; Statnick, R.M.; Stouffer, M.R.; Winschel, R.A.; Withum, J.A.; Wu, M.M.; Yoon, H.

    1992-02-01

    The Edgewater Coolside process demonstration met the program objectives which were to determine Coolside SO{sub 2} removal performance, establish short-term process operability, and evaluate the economics of the process versus a limestone wet scrubber. On a flue gas produced from the combustion of 3% sulfur coal, the Coolside process achieved 70% SO{sub 2} removal using commercially-available hydrated lime as the sorbent. The operating conditions were Ca/S mol ratio 2.0, Na/Ca mol ratio 0.2, and 20{degree}F approach to adiabatic saturation temperature ({del}T). During tests using fresh plus recycle sorbent, the recycle sorbent exhibited significant capacity for additional SO{sub 2} removal. The longest steady state operation was eleven days at nominally Ca/S = 2, Na/Ca = 0.22, {del}T = 20--22{degree}F, and 70% SO{sub 2} removal. The operability results achieved during the demonstration indicate that with the recommended process modifications, which are discussed in the Coolside process economic analysis, the process could be designed as a reliable system for utility application. Based on the demonstration program, the Coolside process capital cost for a hypothetical commercial installation was minimized. The optimization consisted of a single, large humidifier, no spare air compressor, no isolation dampers, and a 15 day on-site hydrated lime storage. The levelized costs of the Coolside and the wet limestone scrubbing processes were compared. The Coolside process is generally economically competitive with wet scrubbing for coals containing up to 2.5% sulfur and plants under 350 MWe. Site-specific factors such as plant capacity factor, SO{sub 2} emission limit, remaining plant life, retrofit difficulty, and delivered sorbent cost affect the scrubber-Coolside process economic comparison.

  9. The role of catalyst precursor anions in coal gasification. Third quarterly report

    SciTech Connect

    Abotsi, G.M.K.

    1992-08-28

    The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a North Dakota lignite (PSOC 1482) and its demineralized derivative with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. Catalyst loading will be conducted under well-controlled conditions of solution pH and ionic strength. In the last quarter, the surface charge properties of the coal was determined as a function of acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sup 3}{sup {minus}}), carbonate (CO{sub 3}{sup 2{minus}}) or sulfate (SO{sub 4}{sup 2{minus}})concentration using the respective potassium salts of these anions. In general, low anion concentrations (10{sup {minus}3} or 10{sup {minus}2} mol/L) had little effect on the zeta potentials of the coals. However, the surface charge densities of the coal become less negative at 10-1 mol/L of the nitrate, carbonate or sulfate anions. These trends suggest that the surface charge density of the coal is controlled by the adsorption of potassium ions (K{sup +}) onto the coal particles. The net negative charge on the coal panicles creates a repulsive force between the anions and the coal surface and prevents the anions from exerting any significant effect on the coal`s electrokinetic properties.

  10. The role of catalyst precursor anions in coal gasification

    SciTech Connect

    Abotsi, G.M.K.

    1992-08-28

    The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a North Dakota lignite (PSOC 1482) and its demineralized derivative with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. Catalyst loading will be conducted under well-controlled conditions of solution pH and ionic strength. In the last quarter, the surface charge properties of the coal was determined as a function of acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sup 3}{sup {minus}}), carbonate (CO{sub 3}{sup 2{minus}}) or sulfate (SO{sub 4}{sup 2{minus}})concentration using the respective potassium salts of these anions. In general, low anion concentrations (10{sup {minus}3} or 10{sup {minus}2} mol/L) had little effect on the zeta potentials of the coals. However, the surface charge densities of the coal become less negative at 10-1 mol/L of the nitrate, carbonate or sulfate anions. These trends suggest that the surface charge density of the coal is controlled by the adsorption of potassium ions (K{sup +}) onto the coal particles. The net negative charge on the coal panicles creates a repulsive force between the anions and the coal surface and prevents the anions from exerting any significant effect on the coal's electrokinetic properties.

  11. Ab initio calculation of excess properties of La{sub 1−x}(Ln,An){sub x}PO{sub 4} solid solutions

    SciTech Connect

    Li, Yan; Kowalski, Piotr M.; Blanca-Romero, Ariadna; Vinograd, Victor; Bosbach, Dirk

    2014-12-15

    We used ab initio computational approach to predict the excess enthalpy of mixing and the corresponding regular/subregular model parameters for La{sub 1−x}Ln{sub x}PO{sub 4} (Ln=Ce,…, Tb) and La{sub 1−x}An{sub x}PO{sub 4} (An=Pu, Am and Cm) monazite-type solid solutions. We found that the regular model interaction parameter W computed for La{sub 1−x}Ln{sub x}PO{sub 4} solid solutions matches the few existing experimental data. Within the lanthanide series W increases quadratically with the volume mismatch between LaPO{sub 4} and LnPO{sub 4} endmembers (ΔV=V{sub LaPO{sub 4}}−V{sub LnPO{sub 4}}), so that W(kJ/mol)=0.618(ΔV(cm{sup 3}/mol)){sup 2}. We demonstrate that this relationship also fits the interaction parameters computed for La{sub 1−x}An{sub x}PO{sub 4} solid solutions. This shows that lanthanides can be used as surrogates for investigation of the thermodynamic mixing properties of actinide-bearing solid solutions. - Highlights: • The excess enthalpies of mixing for monazite-type solid solutions are computed. • The excess enthalpies increase with the endmembers volume mismatch. • The relationship derived for lanthanides is transferable to La{sub 1−x}An{sub x}PO{sub 4} systems.

  12. Low-cost copper complexes as p-dopants in solution processable hole transport layers

    SciTech Connect

    Kellermann, Renate; Taroata, Dan; Maltenberger, Anna; Hartmann, David; Schmid, Guenter; Brabec, Christoph J.

    2015-09-07

    We demonstrate the usage of the Lewis-acidic copper(II)hexafluoroacetylacetonate (Cu(hfac){sub 2}) and copper(II)trifluoroacetylacetonate (Cu(tfac){sub 2}) as low-cost p-dopants for conductivity enhancement of solution processable hole transport layers based on small molecules in organic light emitting diodes (OLEDs). The materials were clearly soluble in mixtures of environmentally friendly anisole and xylene and spin-coated under ambient atmosphere. Enhancements of two and four orders of magnitude, reaching 4.0 × 10{sup −11} S/cm with a dopant concentration of only 2 mol% Cu(hfac){sub 2} and 1.5 × 10{sup −9} S/cm with 5 mol% Cu(tfac){sub 2} in 2,2′,7,7′-tetra(N,N-ditolyl)amino-9,9-spiro-bifluorene (spiro-TTB), respectively, were achieved. Red light emitting diodes were fabricated with reduced driving voltages and enhanced current and power efficiencies (8.6 lm/W with Cu(hfac){sub 2} and 5.6 lm/W with Cu(tfac){sub 2}) compared to the OLED with undoped spiro-TTB (3.9 lm/W). The OLED with Cu(hfac){sub 2} doped spiro-TTB showed an over 8 times improved LT{sub 50} lifetime of 70 h at a starting luminance of 5000 cd/m{sup 2}. The LT{sub 50} lifetime of the reference OLED with PEDOT:PSS was only 8 h. Both non-optimized OLEDs were operated at similar driving voltage and power efficiency.

  13. Advanced heat exchanger development for molten salts

    SciTech Connect

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.

  14. MAIN-BELT COMET P/2012 T1 (PANSTARRS)

    SciTech Connect

    Hsieh, Henry H.; Kaluna, Heather M.; Yang Bin; Haghighipour, Nader; Micheli, Marco; Denneau, Larry; Jedicke, Robert; Kleyna, Jan; Veres, Peter; Wainscoat, Richard J.; Ansdell, Megan; Elliott, Garrett T.; Keane, Jacqueline V.; Meech, Karen J.; Riesen, Timm E.; Sonnett, Sarah; Novakovic, Bojan; Fitzsimmons, Alan; Moskovitz, Nicholas A.; Sheppard, Scott S.; and others

    2013-07-01

    We present initial results from observations and numerical analyses aimed at characterizing the main-belt comet P/2012 T1 (PANSTARRS). Optical monitoring observations were made between 2012 October and 2013 February using the University of Hawaii 2.2 m telescope, the Keck I telescope, the Baade and Clay Magellan telescopes, Faulkes Telescope South, the Perkins Telescope at Lowell Observatory, and the Southern Astrophysical Research Telescope. The object's intrinsic brightness approximately doubles from the time of its discovery in early October until mid-November and then decreases by {approx}60% between late December and early February, similar to photometric behavior exhibited by several other main-belt comets and unlike that exhibited by disrupted asteroid (596) Scheila. We also used Keck to conduct spectroscopic searches for CN emission as well as absorption at 0.7 {mu}m that could indicate the presence of hydrated minerals, finding an upper limit CN production rate of Q{sub CN} < 1.5 Multiplication-Sign 10{sup 23} mol s{sup -1}, from which we infer a water production rate of Q{sub H{sub 2O}}<5 Multiplication-Sign 10{sup 25} mol s{sup -1}, and no evidence of the presence of hydrated minerals. Numerical simulations indicate that P/2012 T1 is largely dynamically stable for >100 Myr and is unlikely to be a recently implanted interloper from the outer solar system, while a search for potential asteroid family associations reveals that it is dynamically linked to the {approx}155 Myr old Lixiaohua asteroid family.

  15. Decomposition and vibrational relaxation in CH{sub 3}I and self-reaction of CH{sub 3} radicals.

    SciTech Connect

    Yang, X.; Goldsmith, C. F.; Tranter, R. S.

    2009-07-01

    Vibrational relaxation and dissociation of CH{sub 3}I, 2-20% in krypton, have been investigated behind incident shock waves in a diaphragmless shock tube at 20, 66, 148, and 280 Torr and 630-2200 K by laser schlieren densitometry. The effective collision energy obtained from the vibrational relaxation experiments has a small, positive temperature dependence, {Delta}E{sub down} = 63 x (T/298){sup 0.56} cm{sup -1}. First-order rate coefficients for dissociation of CH{sub 3}I show a strong pressure dependence and are close to the low-pressure limit. Restricted-rotor Gorin model RRKM calculations fit the experimental results very well with {Delta}E{sub down} = 378 x (T/298){sup 0.457} cm{sup -1}. The secondary chemistry of this reaction system is dominated by reactions of methyl radicals and the reaction of the H atom with CH{sub 3}I. The results of the decomposition experiments are very well simulated with a model that incorporates methyl recombination and reactions of methylene. Second-order rate coefficients for ethane dissociation to two methyl radicals were derived from the experiments and yield k = (4.50 {+-} 0.50) x 10{sup 17} exp(-32709/T) cm{sup 3} mol{sup -1} s{sup -1}, in good agreement with previous measurements. Rate coefficients for H + CH{sub 3}I were also obtained and give k = (7.50 {+-} 1.0) x 10{sup 13} exp(-601/T) cm{sup 3} mol{sup -1} s{sup -1}, in reasonable agreement with a previous experimental value.

  16. Activation of ethane in the presence of solid acids: Sulfated zirconia, iron- and manganese-promoted sulfated zirconia, and zeolites

    SciTech Connect

    Cheung, Tsz-Keung; Gates, B.

    1997-06-01

    Ethane was activated in the presence of solid acids [sulfated zirconia (SZ), iron- and manganese-promoted sulfated zirconia (FMSZ), HZSM-5, and USY zeolite] at 1 atm, 200-450{degrees}C, and ethane partial pressures in the range 0.014.2 atm. The data were measured with a flow reactor at low conversions (<0.005) such that reaction of ethane took place in the near absence of alkenes. Catalysis was demonstrated for ethane conversion in the presence of FMSZ at 450{degrees}C and 0.2 atm ethane partial pressure, but the reactions were not shown to be catalytic for the other solid acids and other conditions. FMSZ was active for converting ethane into methane, ethene, and butane at an ethane partial pressure of 0.2 atm and at temperatures of 200-300{degrees}C; the other solid acids had no detectable activities under these conditions. At higher temperatures, each of the solid acids was active for conversion of ethane into ethene; butane and methane were also formed in the presence of FMSZ, HZSM-5, and USY zeolite, whereas methane was the only other hydrocarbon observed in the presence of SZ. The initial (5 min on stream) selectivities to ethene at approximately 0.1 % conversion, ethane partial pressure of 0.2 atm, and 450{degrees}C were approximately 98, 94, 97, and 99%, for SZ, FMSZ, HZSM-5, and USY zeolite, respectively. Under the same reaction conditions, the initial rates of ethane conversion were 0. 1 5 x 10{sup -8}, 3.5 x 10{sup -8} 3.9 x 10{sup -8}, and 0.56 x 10{sup -8} mol/(s {circ} g) for SZ, FMSZ, HZSM-5, and USY zeolite, respectively. The reactivities are consistent with chemistry analogous to that occurring in superacidic solutions and with the suggestion that FMSZ is a stronger acid than the others investigated here. 25 refs., 13 figs., 1 tab.

  17. Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the Nine R/V Korr Cruises Comprising the Indian Ocean CO2Survey (WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2; December 1, 1994-January 19, 1996)

    SciTech Connect

    Kozyr, A.V.

    2003-09-15

    This document describes the procedures and methods used to measure total carbon dioxide (TCO{sub 2}) and total alkalinity (TALK) at hydrographic stations taken during the R/V Knorr Indian Ocean cruises (Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2) in 1994-1996. The measurements were conducted as part of the World Ocean Circulation Experiment (WOCE). The expedition began in Fremantle, Australia, on December 1, 1994, and ended in Mombasa, Kenya, on January 22, 1996. During the nine cruises, 12 WOCE sections were occupied. Total carbon dioxide was extracted from water samples and measured using single-operator multiparameter metabolic analyzers (SOMMAs) coupled to coulometers. The overall precision and accuracy of the analyses was {+-} 1.20 {micro}mol/kg. The second carbonate system parameter, TALK, was determined by potentiometric titration. The precision of the measurements determined from 962 analyses of certified reference material was {+-} 4.2 {micro}mol/kg (REFERENCE). This work was supported by grants from the National Science Foundation, the U. S. Department of Energy, and the National Oceanographic and Atmospheric Administration. The R/V Knorr Indian Ocean data set is available as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center (CDIAC). The NDP consists of 18 oceanographic data files, two FORTRAN 77 data retrieval routine files, a readme file, and this printed documentation, which describes the contents and format of all files as well as the procedures and methods used to obtain the data. Instructions for accessing the data are provided.

  18. Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

    SciTech Connect

    Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel; Tansel, Berrin

    2013-09-05

    ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperatures of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.

  19. Global scale environmental control of plant photosynthetic capacity

    SciTech Connect

    Ali, Ashehad; Xu, Chonggang; Rogers, Alistair; McDowell, Nathan G.; Medlyn, Belinda E.; Fisher, Rosie A.; Wullschleger, Stan D.; Reich, Peter B.; Bauerle, William L.; Wilson, Cathy J.; Vrugt, Jasper A.; Santiago, Louis S.

    2015-12-01

    Photosynthetic capacity, determined by light harvesting and carboxylation reactions, is a key plant trait that determines the rate of photosynthesis; however, in Earth System Models (ESMs) at a reference temperature, it is either a fixed value for a given plant functional type or derived from a linear function of leaf nitrogen content. In this study, we conducted a comprehensive analysis that considered correlations of environmental factors with photosynthetic capacity as determined by maximum carboxylation (Vc,m) rate scaled to 25°C (i.e., Vc,25; μmol CO2·m–2·s–1) and maximum electron transport rate (Jmax) scaled to 25°C (i.e., J25; μmol electron·m–2·s–1) at the global scale. Our results showed that the percentage of variation in observed Vc,25 and J25 explained jointly by the environmental factors (i.e., day length, radiation, temperature, and humidity) were 2–2.5 times and 6–9 times of that explained by area-based leaf nitrogen content, respectively. Environmental factors influenced photosynthetic capacity mainly through photosynthetic nitrogen use efficiency, rather than through leaf nitrogen content. The combination of leaf nitrogen content and environmental factors was able to explain ~56% and ~66% of the variation in Vc,25 and J25 at the global scale, respectively. As a result, our analyses suggest that model projections of plant photosynthetic capacity and hence land–atmosphere exchange under changing climatic conditions could be substantially improved if environmental factors are incorporated into algorithms used to parameterize photosynthetic capacity in ESMs.

  20. Inorganic-organic composite solid polymer electrolytes

    SciTech Connect

    Abraham, K.M.; Koch, V.R.; Blakley, T.J.

    2000-04-01

    Inorganic-organic composite solid polymer electrolytes (CSPEs) have been prepared from the poly(ethylene oxide) (PEO)-like electrolytes of the general formula polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-PEO{sub n}-LiX and Li{sup +}-conducting ceramic powders. In the PEO-like electrolytes, PVdF-HFP is the copolymer of PVdF and HFP, PEO{sub n} is a nonvolatile oligomeric polyethylene oxide of {approximately}400 g/mol molecular weight, and LiX is lithium bis(trifluoroethylsulfonyl)imide. Two types of inorganic oxide ceramic powders were used: a highly Li{sup +}-conducting material of the composition 14 mol % Li{sub 2}O-9Al{sub 2}O{sub 3}-38TiO{sub 2}-39P{sub 2}O{sub 5}, and the poorly Li{sup +}-conducting Li-silicates Li{sub 4{minus}x}M{sub x}SiO{sub 4} where M is Ca or Mg and x is 0 or 0.05. The composite electrolytes can be prepared as thin membranes in which the Li{sup +} conductivity and good mechanical strength of the Li{sup +}-conducting inorganic ceramics are complemented by the structural flexibility and high conductivity of organic polymer electrolytes. Excellent electrochemical and thermal stabilities have been demonstrated for the electrolyte films. Li//composite electrolyte//LiCoO{sub 2} rechargeable cells have been fabricated and cycled at room temperature and 50 C.

  1. On the thermal stability of physical vapor deposited oxide-hardened nanocrystalline gold thin films

    DOE PAGES [OSTI]

    Argibay, Nicolas; Mogonye, J. E.; Michael, Joseph R.; Goeke, Ronald S.; Kotula, Paul G.; Scharf, T. W.; Dugger, Michael Thomas; Prasad, Somuri V.

    2015-04-08

    We describe a correlation between electrical resistivity and grain size for PVD synthesized polycrystalline oxide-hardened metal-matrix thin films in oxide-dilute (<5 vol. % oxide phase) compositions. The correlation is based on the Mayadas-Shatzkes (M-S) electron scattering model, predictive of grain size evolution as a function of composition in the oxide-dilute regime for 2 μm thick Au-ZnO films. We describe a technique to investigate grain boundary (GB) mobility and the thermal stability of GBs based on in situelectrical resistivity measurements during annealing experiments, interpreted using a combination of the M-S model and the Michels et al. model describing solute drag stabilizedmore » grain growth kinetics. Using this technique, activation energy and pre-exponential Arrhenius parameter values of Ea = 21.6 kJ/mol and Ao = 2.3 × 10-17 m2/s for Au-1 vol. % ZnO and Ea =12.7 kJ/mol and Ao = 3.1 × 10-18 m2/s for Au-2 vol.% ZnO were determined. In the oxide-dilute regime, the grain size reduction of the Au matrix yielded a maximum hardness of 2.6 GPa for 5 vol. % ZnO. A combined model including percolation behavior and grain refinement is presented that accurately describes the composition dependent change in electrical resistivity throughout the entire composition range for Au-ZnO thin films. As a result, the proposed correlations are supported by microstructural characterization using transmission electron microscopy and electron diffraction mapping for grain size determination.« less

  2. Investigations of α-helix↔β-sheet transition pathways in a miniprotein using the finite-temperature string method

    SciTech Connect

    Ovchinnikov, Victor; Karplus, Martin

    2014-05-07

    A parallel implementation of the finite-temperature string method is described, which takes into account the invariance of coordinates with respect to rigid-body motions. The method is applied to the complex α-helix↔β-sheet transition in a β-hairpin miniprotein in implicit solvent, which exhibits much of the complexity of conformational changes in proteins. Two transition paths are considered, one derived from a linear interpolant between the endpoint structures and the other derived from a targeted dynamics simulation. Two methods for computing the conformational free energy (FE) along the string are compared, a restrained method, and a tessellation method introduced by E. Vanden-Eijnden and M. Venturoli [J. Chem. Phys. 130, 194103 (2009)]. It is found that obtaining meaningful free energy profiles using the present atom-based coordinates requires restricting sampling to a vicinity of the converged path, where the hyperplanar approximation to the isocommittor surface is sufficiently accurate. This sampling restriction can be easily achieved using restraints or constraints. The endpoint FE differences computed from the FE profiles are validated by comparison with previous calculations using a path-independent confinement method. The FE profiles are decomposed into the enthalpic and entropic contributions, and it is shown that the entropy difference contribution can be as large as 10 kcal/mol for intermediate regions along the path, compared to 15–20 kcal/mol for the enthalpy contribution. This result demonstrates that enthalpic barriers for transitions are offset by entropic contributions arising from the existence of different paths across a barrier. The possibility of using systematically coarse-grained representations of amino acids, in the spirit of multiple interaction site residue models, is proposed as a means to avoid ad hoc sampling restrictions to narrow transition tubes.

  3. On the thermal stability of physical vapor deposited oxide-hardened nanocrystalline gold thin films

    SciTech Connect

    Argibay, Nicolas; Mogonye, J. E.; Michael, Joseph R.; Goeke, Ronald S.; Kotula, Paul G.; Scharf, T. W.; Dugger, Michael Thomas; Prasad, Somuri V.

    2015-04-08

    We describe a correlation between electrical resistivity and grain size for PVD synthesized polycrystalline oxide-hardened metal-matrix thin films in oxide-dilute (<5 vol. % oxide phase) compositions. The correlation is based on the Mayadas-Shatzkes (M-S) electron scattering model, predictive of grain size evolution as a function of composition in the oxide-dilute regime for 2 μm thick Au-ZnO films. We describe a technique to investigate grain boundary (GB) mobility and the thermal stability of GBs based on in situelectrical resistivity measurements during annealing experiments, interpreted using a combination of the M-S model and the Michels et al. model describing solute drag stabilized grain growth kinetics. Using this technique, activation energy and pre-exponential Arrhenius parameter values of Ea = 21.6 kJ/mol and Ao = 2.3 × 10-17 m2/s for Au-1 vol. % ZnO and Ea =12.7 kJ/mol and Ao = 3.1 × 10-18 m2/s for Au-2 vol.% ZnO were determined. In the oxide-dilute regime, the grain size reduction of the Au matrix yielded a maximum hardness of 2.6 GPa for 5 vol. % ZnO. A combined model including percolation behavior and grain refinement is presented that accurately describes the composition dependent change in electrical resistivity throughout the entire composition range for Au-ZnO thin films. As a result, the proposed correlations are supported by microstructural characterization using transmission electron microscopy and electron diffraction mapping for grain size determination.

  4. Advanced heat exchanger development for molten salts

    SciTech Connect

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.

  5. Performance of Coupled Cluster Theory in Thermochemical Calculations of Small Halogenated Compounds

    SciTech Connect

    Feller, David F. ); Peterson, Kirk A.; De Jong, Wibe A. ); Dixon, David A. )

    2003-02-23

    Atomization energies at 0 K and heats of formation at 298 K were obtained for a collection of small halogenated molecules from coupled cluster theory including noniterative, quasi-perturbative triple excitations calculations with large basis sets (up through augmented septuple zeta quality in some cases). In order to achieve near chemical accuracy (1 kcal/mol) in the thermodynamic properties, we adopted a composite theoretical approach which incorporated estimated complete basis set binding energies based on frozen core coupled cluster theory energies and (up to) five corrections: (1) a core/valence correction; (2) a Douglas-Kroll-Hess scalar relativistic correction; (3) a first order atomic spin-orbit correction; (4) a second order spin-orbit correction for heavy elements and (5) an approximate correction to account for the remaining correlation energy. The last of these corrections is based on a recently proposed approximation to full configuration interaction via a continued fraction approximant for coupled cluster theory (CCSD(T)-cf). Failure to consider corrections (1) to (4) can introduce errors significantly in excess of the target accuracy of 1 kcal/mol. Although some cancellation of error may occur if one or more of these corrections is omitted, such a situation is by no means universal and cannot be relied upon for high accuracy. The accuracy of the Douglas-Kroll-Hess approach was calibrated against both new and previously published 4-component Dirac Coulomb results at the coupled cluster level of theory. In addition, vibrational zero point energies were computed at the coupled cluster level of theory for those polyatomic systems lacking an experimental anharmonic value.

  6. Density functional theory based generalized effective fragment potential method

    SciTech Connect

    Nguyen, Kiet A. E-mail: ruth.pachter@wpafb.af.mil; Pachter, Ruth E-mail: ruth.pachter@wpafb.af.mil; Day, Paul N.

    2014-06-28

    We present a generalized Kohn-Sham (KS) density functional theory (DFT) based effective fragment potential (EFP2-DFT) method for the treatment of solvent effects. Similar to the original Hartree-Fock (HF) based potential with fitted parameters for water (EFP1) and the generalized HF based potential (EFP2-HF), EFP2-DFT includes electrostatic, exchange-repulsion, polarization, and dispersion potentials, which are generated for a chosen DFT functional for a given isolated molecule. The method does not have fitted parameters, except for implicit parameters within a chosen functional and the dispersion correction to the potential. The electrostatic potential is modeled with a multipolar expansion at each atomic center and bond midpoint using Stone's distributed multipolar analysis. The exchange-repulsion potential between two fragments is composed of the overlap and kinetic energy integrals and the nondiagonal KS matrices in the localized molecular orbital basis. The polarization potential is derived from the static molecular polarizability. The dispersion potential includes the intermolecular D3 dispersion correction of Grimme et al. [J. Chem. Phys. 132, 154104 (2010)]. The potential generated from the CAMB3LYP functional has mean unsigned errors (MUEs) with respect to results from coupled cluster singles, doubles, and perturbative triples with a complete basis set limit (CCSD(T)/CBS) extrapolation, of 1.7, 2.2, 2.0, and 0.5 kcal/mol, for the S22, water-benzene clusters, water clusters, and n-alkane dimers benchmark sets, respectively. The corresponding EFP2-HF errors for the respective benchmarks are 2.41, 3.1, 1.8, and 2.5 kcal/mol. Thus, the new EFP2-DFT-D3 method with the CAMB3LYP functional provides comparable or improved results at lower computational cost and, therefore, extends the range of applicability of EFP2 to larger system sizes.

  7. {gamma}-Radiolysis of NaCl Brine in the Presence of UO{sub 2}(s): Effects of Hydrogen and Bromide

    SciTech Connect

    Metz, Volker; Bohnert, Elke; Kelm, Manfred; Schild, Dieter; Kienzler, Bernhard

    2007-07-01

    A concentrated NaCl solution was {gamma}-irradiated in autoclaves under a pressure of 25 MPa. A set of experiments were conducted in 6 mol (kg H{sub 2}O){sup -1} NaCl solution in the presence of UO{sub 2}(s) pellets; in a second set of experiments, {gamma}-radiolysis of the NaCl brine was studied without UO{sub 2}(s). Hydrogen, oxygen and chlorate were formed as long-lived radiolysis products. Due to the high external pressure, all radiolysis products remained dissolved. H{sub 2} and O{sub 2} reached steady state concentrations in the range of 5.10{sup -3} to 6.10{sup -2} mol (kg H{sub 2}O){sup -1} corresponding to a partial gas pressure of {approx}2 to {approx}20 MPa. Radiolytic formation of hydrogen and oxygen increased with the concentration of bromide added to solution. Both, in the presence of bromide, resulting in a relatively high radiolytic yield, and in the absence of bromide surfaces of the UO{sub 2}(s) samples were oxidized, and concentration of dissolved uranium reached the solubility limit of the schoepite / NaUO{sub 2}O(OH)(cr) transition. At the end of the experiments, the pellets were covered by a surface layer of a secondary solid phase having a composition close to Na{sub 2}U{sub 2}O{sub 7}. The experimental results demonstrate that bromide counteracts an H{sub 2} inhibition effect on radiolysis gas production, even at a concentration ratio of [H{sub 2}] / [Br{sup -}] > 100. The present observations are related to the competitive reactions of OH radicals with H{sub 2}, Br{sup -} and Cl{sup -}. A similar competition of hydrogen and bromide, controlling the yield of {gamma}-radiolysis products, is expected for solutions of lower Cl{sup -} concentration. (authors)

  8. The Negative Ion Photoelectron Spectrum of meta-Benzoquinone Radical Anion (MBQ•−): A Joint Experimental and Computational Study

    SciTech Connect

    Chen, Bo; Hrovat, David; Deng, Shihu; Zhang, Jian; Wang, Xue B.; Borden, Weston

    2014-02-19

    Negative ion photoelectron (NIPE) spectra of the radical anion of meta-benzoquinone (MBQ, m-OC6H4O) have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show well-resolved peaks and complex spectral patterns. The electron affinity of MBQ is determined from the first resolved peak to be 2.875 ±17 0.010 eV. Single-point, CASPT2/aug-cc-pVTZ//CASPT2/ aug-cc-pVDZ calculations predict accurately the positions of the 0−0 bands in the NIPE spectrum for formation of the four lowest electronic states of neutral MBQ from the 2A2 state of MBQ•−. In addition, the Franck−Condon factors that are computed from the CASPT2/aug-cc-pVDZ optimized geometries,vibrational frequencies, and normal mode vectors, successfully simulate the intensities and frequencies of the vibrational peaks in the NIPE spectrum that are associated with each of these electronic states. The successful simulation of the NIPE spectrum of MBQ•− allows the assignment of 3B2 as the ground state of MBQ, followed by the 1B2 and 1A1 electronic states, respectively 9.0 ± 0.2 and 16.6 ± 0.2 kcal/mol higher in energy than the triplet. These experimental energy differences are in good agreement with the calculated values of 9.7 and 15.7 kcal/mol. The relative energies of these two singlet states in MBQ confirm the previous prediction that their relative energies would be reversed from those in meta-benzoquinodimethane (MBQDM, m-CH2C6H4CH2).

  9. The Negative Ion Photoelectron Spectrum of Cyclopropane-1,2,3-Trione Radical Anion (CO)(3)•- - A Joint Experimental and Computational Study

    SciTech Connect

    Chen, Bo; Hrovat, David; West, Robert C.; Deng, Shihu; Wang, Xue B.; Borden, Weston

    2014-09-03

    Negative Ion Photoelectron (NIPE) spectra of the radical anion of cyclopropane-1,2,3-trione, (CO)3•−, have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show broadened bands, due to the short lifetimes of both the singlet and triplet states of (CO)3. The smaller intensity of the band with the lower electron binding energy suggests that the singlet is the ground state of (CO)3. From the NIPE spectra, the electron affinity (EA) and the singlet-triplet energy gap of (CO)3 are estimated to be, respectively, EA = 3.1 ± 0.1 eV and EST = −14 ± 3 kcal/mol. High-level, (U)CCSD(T)/aug-cc-pVQZ//(U)CCSD(T)/aug-cc-pVTZ, calcu-lations give EA = 3.04 eV for the 1A1´ ground state of (CO)3 and EST = −13.8 kcal/mol for the energy gap between the 1A1´ and 3A2 states, in excellent agreement with values from the NIPE spectra. In addition, simulations of the vibrational structures for formation of these states of (CO)3 from the 2A2˝ state of (CO)3•− provide a good fit to the shapes of broad bands in the 266 nm NIPE spectrum. The NIPE spectrum of (CO)3•− and the analysis of the spectrum by high-quality electronic structure calculations demonstrate that NIPES can not only access and provide information about transition structures, but NIPES can also access and provide information about hilltops on potential energy surfaces.

  10. Up-conversion luminescent properties of La{sub (0.80−x)}VO{sub 4}:Yb{sub x}, Er{sub 0.20} phosphors

    SciTech Connect

    Choi, Dong Hwa; Kang, Deok Hwa; Yi, Soung Soo; Jang, Kiwan; Jeong, Jung Hyun

    2015-11-15

    Highlights: • A novel green and red emitting LaVO{sub 4}:Yb{sub x}{sup 3+}, Er{sub 0.20}{sup 3+} phosphors were synthesized. • Their structures, luminescent properties have also been investigated. • Major laser transition for Er{sup 3+} ion is {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2} (525 nm). • These results suggest the possibility as photonic devices. - Abstract: Yb{sup 3+}, Er{sup 3+} co-doped LaVO{sub 4} phosphors were synthesized by solid state reaction method. Yb{sup 3+} concentrations were changed from 0.01 to 0.20 mol for the fixed Er{sup 3+} concentration at 0.2 mol. The crystalline structure of samples was investigated by X-ray diffraction (XRD). The composition was investigated by X-ray photoelectron spectroscopy (XPS) analysis. The surface morphology was observed by scanning electron microscope (SEM). The red and green up-conversion emissions were observed in Yb{sup 3+}, Er{sup 3+} co-doped LaVO{sub 4} phosphors under the excitation of 980 nm laser diode. Several emissions in green and red regions of the spectrum were observed near 525 nm, 553 nm and 659 nm radiated by {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}, {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2}, and {sup 4}F{sub 3/2} → {sup 4}I{sub 15/2} transitions, respectively.

  11. Luminescence properties of ZrW{sub 2}O{sub 8}:Eu{sup 3+} nanophosphors for white light emitting diodes

    SciTech Connect

    Liao, Jinsheng Liu, Shaohua; Wen, He-Rui; Nie, Liling; Zhong, Laifu

    2015-10-15

    Highlights: • Eu{sup 3+} ions occupy C{sub 1} point group of the Zr{sup 4+} site in ZrW{sub 2}O{sub 8} crystals. • The optimum doping concentration of Eu{sup 3+} was determined for the red emission. • ZrW{sub 2}O{sub 8}:Eu possess high quantum efficiency and suitable chromaticity coordinates. - Abstract: ZrW{sub 2}O{sub 8}:Eu{sup 3+} nanophosphors (ca. 60 nm) with different Eu{sup 3+} doping concentrations were obtained using hydrothermal syntheses. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence excitation and emission spectra as well as decay curve measurements were used for the characterization. Under 466 nm excitation, strong red emission at 616 nm corresponding to {sup 5}D{sub 0}–{sup 7}F{sub 2} transition of Eu{sup 3+} was observed for ZrW{sub 2}O{sub 8}:Eu{sup 3+} (9 mol%) phosphors. The values of intensity parameter Ω{sub 2} and Ω{sub 4} are 17.82 × 10{sup −20} cm{sup 2} and 1.092 × 10{sup −20} cm{sup 2}, respectively. The high quantum efficiency of 83.5% of the ZrW{sub 2}O{sub 8}:Eu{sup 3+} (9 mol%) suggests this material could be promising red phosphor for generating white light in phosphor-converted white light-emitting diodes (LED)

  12. Distinguishing tautomerism in the crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide using DFT-D calculations and {sup 13}C solid-state NMR

    SciTech Connect

    Li, Xiaozhou; Bond, Andrew D.; Johansson, Kristoffer E.; Van de Streek, Jacco

    2014-08-01

    The crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide contains an imine tautomer, rather than the previously reported amine tautomer. The tautomers can be distinguished using dispersion-corrected density functional theory calculations and by comparison of calculated and measured {sup 13}C solid-state NMR spectra. The crystal structure of the title compound, C{sub 11}H{sub 13}N{sub 3}O{sub 2}S{sub 2}, has been determined previously on the basis of refinement against laboratory powder X-ray diffraction (PXRD) data, supported by comparison of measured and calculated {sup 13}C solid-state NMR spectra [Hangan et al. (2010 ▶). Acta Cryst. B66, 615–621]. The mol@@ecule is tautomeric, and was reported as an amine tautomer [systematic name: N-(5-ethyl-1,3,4-thia@@diazol-2-yl)-p-toluene@@sulfonamide], rather than the correct imine tautomer. The protonation site on the mol@@ecule’s 1,3,4-thia@@diazole ring is indicated by the inter@@molecular contacts in the crystal structure: N—H⋯O hydrogen bonds are established at the correct site, while the alternative protonation site does not establish any notable inter molecular inter@@actions. The two tautomers provide essentially identical Rietveld fits to laboratory PXRD data, and therefore they cannot be directly distinguished in this way. However, the correct tautomer can be distinguished from the incorrect one by previously reported qu@@anti@@tative criteria based on the extent of structural distortion on optimization of the crystal structure using dispersion-corrected density functional theory (DFT-D) calculations. Calculation of the {sup 13}C SS-NMR spectrum based on the correct imine tautomer also provides considerably better agreement with the measured {sup 13}C SS-NMR spectrum.

  13. Iron oxidation kinetics for H-2 and CO production via chemical looping

    SciTech Connect

    Stehle, RC; Bobek, MM; Hahn, DW

    2015-01-30

    Solar driven production of fuels by means of an intermediate reactive metal for species splitting has provided a practical and potentially efficient pathway for disassociating molecules at significantly lower thermal energies. The fuels of interest are of or derive from the separation of oxygen from H2O and CO2 to form hydrogen and carbon monoxide, respectively. The following study focuses on iron oxidation through water and CO2 splitting to explore the fundamental reaction kinetics and kinetic rates that are relevant to these processes. In order to properly characterize the reactive metal potential and to optimize a scaled-up solar reactor system, a monolith-based laboratory reactor was implemented to investigate reaction temperatures over a range from 990 to 1400 K. The presence of a single, solid monolith as a reacting surface allowed for a limitation in mass transport effects in order to monitor kinetically driven reaction steps. The formation of oxide layers on the iron monoliths followed Cabrera-Mott models for oxidation of metals with kinetic rates being measured using real-time mass spectrometry to calculate kinetic constants and estimate oxide layer thicknesses. Activation energies of 47.3 kJ/mol and 32.8 kJ/mol were found for water-splitting and CO2 splitting, respectively, and the conclusions of the independent oxidation reactions where applied to experimental results for syngas (H-2-CO) production to explore ideal process characteristics. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  14. Extracting uranium from seawater: Promising AF series adsorbents

    DOE PAGES [OSTI]

    Das, Sadananda; Oyola, Y.; Mayes, Richard T.; Janke, Christopher James; Kuo, Li-Jung; Gill, Gary; Wood, Jordana; Dai, Sheng

    2015-11-02

    Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8more » ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater.« less

  15. Extracting uranium from seawater: Promising AF series adsorbents

    SciTech Connect

    Das, Sadananda; Oyola, Y.; Mayes, Richard T.; Janke, Christopher James; Kuo, Li-Jung; Gill, Gary; Wood, Jordana; Dai, Sheng

    2015-11-02

    Here, a new family of high surface area polyethylene fiber adsorbents (AF series) was recently developed at the Oak Ridge National Laboratory (ORNL). The AF series of were synthesized by radiation-induced graft polymerization of acrylonitrile and itaconic acid (at different monomer/co-monomer mol ratios) onto high surface area polyethylene fibers. The degree of grafting (%DOG) of AF series adsorbents was found to be 154 354%. The grafted nitrile groups were converted to amidoxime groups by treating with hydroxylamine. The amidoximated adsorbents were then conditioned with 0.44M KOH at 80 C followed by screening at ORNL with simulated seawater spiked with 8 ppm uranium. Uranium adsorption capacity in simulated seawater screening ranged from 170-200 g-U/kg-ads irrespective of %DOG. A monomer/co-monomer mol ratio in the range of 7.57-10.14 seemed to be optimum for highest uranium loading capacity. Subsequently, the adsorbents were also tested with natural seawater at Pacific Northwest National Laboratory (PNNL) using flow-through exposure uptake experiments to determine uranium loading capacity with varying KOH conditioning time at 80 C. The highest adsorption capacity of AF1 measured after 56 days of marine testing was demonstrated as 3.9 g-U/kg-adsorbent and 3.2 g-U/kg-adsorbent for 1hr and 3hrs of KOH conditioning at 80 C, respectively. Based on capacity values of several AF1 samples, it was observed that changing KOH conditioning from 3hrs to 1hr at 80 C resulted in 22-27% increase in uranium loading capacity in seawater.

  16. An efficient and practical synthesis of [2-11C]indole via superfast nucleophilic [11C]cyanation and RANEY® Nickel catalyzed reductive cyclization

    DOE PAGES [OSTI]

    So Jeong Lee; Fowler, Joanna S.; Alexoff, David; Schueller, Michael; Kim, Dohyun; Nauth, Alexander; Weber, Carina; Kim, Sung Won; Hooker, Jacob M.; Ma, Ling; et al

    2015-09-21

    We developed a rapid method for the synthesis of carbon-11 radiolabeled indole using a sub-nanomolar quantity of no-carrier-added [11C]cyanide as radio-precursor. Based upon a reported synthesis of 2-(2-nitrophenyl)acetonitrile (2), a highly reactive substrate 2-nitrobenzyl bromide (1) was evaluated for nucleophilic [11C]cyanation. Additionally, related reaction conditions were explored with the goal of obtaining of highly reactive 2-(2-nitrophenyl)-[1-11C]acetonitrile ([11C]-2) while inhibiting its rapid conversion to 2,3-bis(2-nitrophenyl)-[1-11C]propanenitrile ([11C]-3). Next, a Raney Nickel catalyzed reductive cyclization method was utilized for synthesizing the desired [2-11C]indole with hydrazinium monoformate as the active reducing agent. Extensive and iterative screening of basicity, temperature and stoichiometry was required tomore » overcome the large stoichiometry bias that favored 2-nitrobenzylbromide (1) over [11C]cyanide, which both caused further alkylation of the desired nitrile and poisoned the Raney Nickel catalyst. The result is an efficient two-step, streamlined method to reliably synthesize [2-11C]indole with an entire radiochemical yield of 21 ± 2.2% (n = 5, ranging from 18 – 24%). The radiochemical purity of the final product was > 98% and specific activity was 176 ± 24.8 GBq/μmol (n = 5, ranging from 141 – 204 GBq/μmol). The total radiosynthesis time including product purification by semi-preparative HPLC was 50 – 55 min from end of cyclotron bombardment.« less

  17. An efficient and practical synthesis of [2-11C]indole via superfast nucleophilic [11C]cyanation and RANEY® Nickel catalyzed reductive cyclization

    SciTech Connect

    So Jeong Lee; Fowler, Joanna S.; Alexoff, David; Schueller, Michael; Kim, Dohyun; Nauth, Alexander; Weber, Carina; Kim, Sung Won; Hooker, Jacob M.; Ma, Ling; Qu, Wenchao

    2015-09-21

    We developed a rapid method for the synthesis of carbon-11 radiolabeled indole using a sub-nanomolar quantity of no-carrier-added [11C]cyanide as radio-precursor. Based upon a reported synthesis of 2-(2-nitrophenyl)acetonitrile (2), a highly reactive substrate 2-nitrobenzyl bromide (1) was evaluated for nucleophilic [11C]cyanation. Additionally, related reaction conditions were explored with the goal of obtaining of highly reactive 2-(2-nitrophenyl)-[1-11C]acetonitrile ([11C]-2) while inhibiting its rapid conversion to 2,3-bis(2-nitrophenyl)-[1-11C]propanenitrile ([11C]-3). Next, a Raney Nickel catalyzed reductive cyclization method was utilized for synthesizing the desired [2-11C]indole with hydrazinium monoformate as the active reducing agent. Extensive and iterative screening of basicity, temperature and stoichiometry was required to overcome the large stoichiometry bias that favored 2-nitrobenzylbromide (1) over [11C]cyanide, which both caused further alkylation of the desired nitrile and poisoned the Raney Nickel catalyst. The result is an efficient two-step, streamlined method to reliably synthesize [2-11C]indole with an entire radiochemical yield of 21 ± 2.2% (n = 5, ranging from 18 – 24%). The radiochemical purity of the final product was > 98% and specific activity was 176 ± 24.8 GBq/μmol (n = 5, ranging from 141 – 204 GBq/μmol). The total radiosynthesis time including product purification by semi-preparative HPLC was 50 – 55 min from end of cyclotron bombardment.

  18. Interactions of aqueous amino acids and proteins with the (110) surface of ZnS in molecular dynamics simulations

    SciTech Connect

    Nawrocki, Grzegorz; Cieplak, Marek

    2014-03-07

    The growing usage of nanoparticles of zinc sulfide as quantum dots and biosensors calls for a theoretical assessment of interactions of ZnS with biomolecules. We employ the molecular-dynamics-based umbrella sampling method to determine potentials of mean force for 20 single amino acids near the ZnS (110) surface in aqueous solutions. We find that five amino acids do not bind at all and the binding energy of the remaining amino acids does not exceed 4.3 kJ/mol. Such energies are comparable to those found for ZnO (and to hydrogen bonds in proteins) but the nature of the specificity is different. Cysteine can bind with ZnS in a covalent way, e.g., by forming the disulfide bond with S in the solid. If this effect is included within a model incorporating the Morse potential, then the potential well becomes much deeperthe binding energy is close to 98 kJ/mol. We then consider tryptophan cage, a protein of 20 residues, and characterize its events of adsorption to ZnS. We demonstrate the relevance of interactions between the amino acids in the selection of optimal adsorbed conformations and recognize the key role of cysteine in generation of lasting adsorption. We show that ZnS is more hydrophobic than ZnO and that the density profile of water is quite different than that forming near ZnOit has only a minor articulation into layers. Furthermore, the first layer of water is disordered and mobile.

  19. The addition of hydrogen atoms to diacetylene and the heats of formation of i-C4H3 and n-C4H3.

    SciTech Connect

    Klippenstein, Stephen J.; Miller, James A.

    2005-01-01

    In this article, we discuss in detail the addition of hydrogen atoms to diacetylene and the reverse dissociation reactions, H + C{sub 4}H{sub 2} {leftrightarrow} i-C{sub 4}H{sub 3} (R1) and H + C{sub 4}H{sub 2} n-C{sub 4}H{sub 3} (R2). The theory utilizes high-level electronic structure methodology to characterize the potential energy surface, Rice-Ramsperger-Kassel-Marcus (RRKM) theory to calculate microcanonical/J-resolved rate coefficients, and a two-dimensional master-equation approach to extract phenomenological (thermal) rate coefficients. Comparison is made with experimental results where they are available. The rate coefficients k{sub 1}(T, p) and k{sub 2}(T, p) are cast in forms that can be used in chemical kinetic modeling. In addition, we predict values of the heats of formation of i-C{sub 4}H{sub 3} and n-C{sub 4}H{sub 3} and discuss their importance in flame chemistry. Our basis-set extrapolated, quadratic-configuration-interaction with single and double excitations (and triple excitations added perturbatively), QCISD(T), predictions of these heats of formation at 298 K are 130.8 kcal/mol for n-C{sub 4}H{sub 3} and 119.3 kcal/mol for the i-isomer; multireference CI calculations with a nine-electron, nine-orbital, complete-active-space (CAS) reference wavefunction give just slightly larger values for these parameters. Our results are in good agreement with the recent focal-point analysis of Wheeler et al. (J. Chem. Phys. 2004, 121, 8800-8813), but they differ substantially for {Delta} H{sub f 298}{sup 0}(n-C{sub 4}H{sub 3}) with the earlier diffusion Monte Carlo predictions of Krokidis et al.

  20. Paramagnetic Defects in Electron-Irradiated Yttria-Stabilized Zirconia: Effect of Yttria Content

    SciTech Connect

    Costantini, Jean-Marc; Beuneu, Francois; Morrison-Smith, Sarah; Devanathan, Ram; Weber, William J

    2011-01-01

    We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic centres were identified for both chemical compositions, namely two electron centres, i.e. i) F+-type centres (involving singly ionized oxygen vacancies), and ii) so-called T centres (Zr3+ in a trigonal symmetry site), and hole-centres. A strong effect is observed on the production of hole-centres which are strongly enhanced when doubling the yttria content. However, no striking effect is found on the electron centres (except the enhancement of an extra line associated to the F+-type centres). It is concluded that hole-centres are produced by inelastic interactions, whereas F+-type centres are produced by elastic collisions with no effect of the yttria content on the defect production rate. In the latter case, the threshold displacement energy (Ed) of oxygen is estimated from the electron-energy dependence of the F+-type centre production rate, with no significant effect of the yttria content on Ed. An Ed value larger than 120 eV is found. Accordingly, classical molecular dynamics (MD) simulations with a Buckingham-type potential show that Ed values for Y and O are likely to be in excess of 200 eV. Due to the difficulty in displacing O or Y atoms, the radiation-induced defects may alternatively be a result of Zr atom displacements for Ed = 80 1 eV with subsequent defect re-arrangement.

  1. Paramagnetic defects in electron-irradiated yttria-stabilized zirconia: Effect of yttria content

    SciTech Connect

    Costantini, Jean-Marc; Beuneu, Francois; Morrison-Smith, Sarah E.; Devanathan, Ramaswami; Weber, William J.

    2011-12-20

    We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic centres were identified for both chemical compositions, namely two electron centres, i.e. i) F+-type centres (involving singly ionized oxygen vacancies), and ii) so-called T centres (Zr3+ in a trigonal symmetry site), and hole-centres. A strong effect is observed on the production of hole-centres which are strongly enhanced when doubling the yttria content. However, no striking effect is found on the electron centres (except the enhancement of an extra line associated to the F+-type centres). It is concluded that hole-centres are produced by inelastic interactions, whereas F+-type centres are produced by elastic collisions with no effect of the yttria content on the defect production rate. In the latter case, the threshold displacement energy (Ed) of oxygen is estimated from the electron-energy dependence of the F+-type centre production rate, with no significant effect of the yttria content on Ed. An Ed value larger than 120 eV is found. Accordingly, classical molecular dynamics (MD) simulations with a Buckingham-type potential show that Ed values for Y and O are likely to be in excess of 200 eV. It is concluded that F+-type centres might be actually oxygen divacancies (F2+-type centres). Due to the difficulty in displacing O or Y atoms, the radiation-induced defects may alternatively be a result of Zr atom displacements for Ed = 80 1 eV with subsequent defect re-arrangement.

  2. A density functional theory study of the oxidation of methanol to formaldehyde over vanadia supported on silica, titania, and zirconia

    SciTech Connect

    Khaliullin, Rustam Z.; Bell, Alexis T.

    2002-09-05

    Density functional theory was used to investigate the mechanism and kinetics of methanol oxidation to formaldehyde over vanadia supported on silica, titania, and zirconia. The catalytically active site was modeled as an isolated VO{sub 4} unit attached to the support. The calculated geometry and vibrational frequencies of the active site are in good agreement with experimental measurements both for model compounds and oxide-supported vanadia. Methanol adsorption is found to occur preferentially with the rupture of a V-O-M bond (M = Si, Ti, Zr) and with preferential attachment of a methoxy group to V. The vibrational frequencies of the methoxy group are in good agreement with those observed experimentally as are the calculated isobars. The formation of formaldehyde is assumed to occur via the transfer of an H atom of a methoxy group to the O atom of the V=O group. The activation energy for this process is found to be in the range of 199-214 kJ/mol and apparent activation energies for the overall oxidation of methanol to formaldehyde are predicted to lie in the range of 112-123 kJ/mol, which is significantly higher than that found experimentally. Moreover, the predicted turnover frequency (TOF) for methanol oxidation is found to be essentially independent of support composition, whereas experiments show that the TOF is 10{sup 3} greater for titania- and zirconia-supported vanadia than for silica-supported vanadia. Based on these findings, it is proposed that the formation of formaldehyde from methoxy groups may require pairs of adjacent VO{sub 4} groups or V{sub 2}O{sub 7} dimer structures.

  3. Probing charge transfer in a novel class of luminescent perovskite-based heterostructures composed of quantum dots bound to RE-activated CaTiO3 phosphors

    DOE PAGES [OSTI]

    Crystal S. Lewis; Wong, Stanislaus S.; Liu, Haiqing; Han, Jinkyu; Wang, Lei; Yue, Shiyu; Brennan, Nicholas A.

    2016-01-04

    We report on the synthesis and structural characterization of novel semiconducting heterostructures composed of cadmium selenide (CdSe) quantum dots (QDs) attached onto the surfaces of novel high-surface area, porous rare-earth-ion doped alkaline earth titanate micron-scale spherical motifs, i.e. both Eu-doped and Pr-doped CaTiO3, composed of constituent, component nanoparticles. These unique metal oxide perovskite building blocks were created by a multi-pronged synthetic strategy involving molten salt and hydrothermal protocols. Subsequently, optical characterization of these heterostructures indicated a clear behavioral dependence of charge transfer in these systems upon a number of parameters such as the nature of the dopant, the reaction temperature,more » and particle size. Specifically, 2.7 nm diameter ligand-functionalized CdSe QDs were anchored onto sub-micron sized CaTiO3-based spherical assemblies, prepared by molten salt protocols. We found that both the Pr- and Eu-doped CaTiO3 displayed pronounced PL emissions, with maximum intensities observed using optimized lanthanide concentrations of 0.2 mol% and 6 mol%, respectively. Analogous experiments were performed on Eu-doped BaTiO3 and SrTiO3 motifs, but CaTiO3 still performed as the most effective host material amongst the three perovskite systems tested. Furthermore, the ligand-capped CdSe QD-doped CaTiO3 heterostructures exhibited effective charge transfer between the two individual constituent nanoscale components, an assertion corroborated by the corresponding quenching of their measured PL signals.« less

  4. Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Meteor Cruise 22/5 in the South Atlantic Ocean (WOCE Section A10, December 1992-January 1993)

    SciTech Connect

    Kozyr, A.

    1998-12-01

    This data documentation discusses the procedures and methods used to measure total carbon dioxide (TCO{sub 2}) and total alkalinity (TALK) at hydrographic stations, as well as the underway partial pressure of CO{sub 2} (pCO{sub 2}) during the R/V Meteor Cruise 22/5 in the South Atlantic Ocean (Section A10). Conducted as part of the World Ocean Circulation Experiment (WOCE), the cruise began in Rio de Janeiro on December 27, 1992, and ended after 36 days at sea in Capetown, South Africa, on January 31, 1993. Measurements made along WOCE Section A10 included pressure, temperature, and salinity [measured by conductivity, temperature, and depth (CTD) sensor], bottle salinity, bottle oxygen, phosphate, nitrate, nitrite, silicate, chlorofluorocarbons (CFC-1 1 , CFC-12), TCO{sub 2}, TALK, and underway pCO{sub 2}. The TCO{sub 2} was measured by using two Single-Operator Multiparameter Metabolic Analyzers (SOMMAs) for extracting CO{sub 2} from seawater samples that were coupled to a coulometer for detection of the extracted CO{sub 2}. The overall precision and accuracy of the analyses was {+-} 1.9 {micro}mol/kg. Samples collected for TALK were measured by potentiometric titration; precision was {+-}2.0 {micro}mol/kg. Underway pCO{sub 2} was measured by infrared photometry with a precision of {+-} 2.0 {micro}atm. The work aboard the R/V Meteor was supported by the U.S. Department of Energy under contract DE-AC02-76CHOO016, and the Bundesministerium fir Forschung und Technologies through grants 03F0545A and MPG 099/1.

  5. Purification and Characterization of OleA from Xanthomonas campestris and Demonstration of a Non-decarboxylative Claisen Condensation Reaction

    SciTech Connect

    Frias, JA; Richman, JE; Erickson, JS; Wackett, LP

    2011-03-25

    OleA catalyzes the condensation of fatty acyl groups in the first step of bacterial long-chain olefin biosynthesis, but the mechanism of the condensation reaction is controversial. In this study, OleA from Xanthomonas campestris was expressed in Escherichia coli and purified to homogeneity. The purified protein was shown to be active with fatty acyl-CoA substrates that ranged from C(8) to C(16) in length. With limiting myristoyl-CoA (C(14)), 1 mol of the free coenzyme A was released/mol of myristoyl-CoA consumed. Using [(14)C] myristoyl-CoA, the other products were identified as myristic acid, 2-myristoylmyristic acid, and 14-heptacosanone. 2-Myristoylmyristic acid was indicated to be the physiologically relevant product of OleA in several ways. First, 2-myristoylmyristic acid was the major condensed product in short incubations, but over time, it decreased with the concomitant increase of 14-heptacosanone. Second, synthetic 2-myristoylmyristic acid showed similar decarboxylation kinetics in the absence of OleA. Third, 2-myristoylmyristic acid was shown to be reactive with purified OleC and OleD to generate the olefin 14-heptacosene, a product seen in previous in vivo studies. The decarboxylation product, 14-heptacosanone, did not react with OleC and OleD to produce any demonstrable product. Substantial hydrolysis of fatty acyl-CoA substrates to the corresponding fatty acids was observed, but it is currently unclear if this occurs in vivo. In total, these data are consistent with OleA catalyzing a non-decarboxylative Claisen condensation reaction in the first step of the olefin biosynthetic pathway previously found to be present in at least 70 different bacterial strains.

  6. Structural, thermal, optical properties and simulation of white light of titanium-tungstate-tellurite glasses doped with dysprosium

    SciTech Connect

    Jyothi, L. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Upender, G. [Glass Science and Technology Section, Glass Division, CSIR-CGCRI, Kolkata 700032 (India); Kuladeep, R. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Rao, D. Narayana, E-mail: dnrsp@uohyd.ernet.in [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2014-02-01

    Graphical abstract: CIE coordinate diagram of different concentrations of the Dy{sup 3+}-doped TTWD glasses with coordinates in the white light region. - Highlights: Radiative lifetime of {sup 4}F{sub 9/2} level of Dy{sup 3+} ions is longer in the tellurite glass. Quantum efficiency is found to be high. These glasses are suitable materials for generating white light. - Abstract: Structural, thermal, optical properties and simulation of white light of Dy{sup 3+}-doped tellurite glasses of composition TTWD: (75 ? x)TeO{sub 2} ? 10TiO{sub 2} ? 15WO{sub 3} ? xDy{sub 2}O{sub 3} (x = 0, 0.1, 0.5, 1.0 and 2.0 mol%) were investigated. Raman spectra revealed that the glass contains TeO{sub 4}, TeO{sub 3}, WO{sub 4} and WO{sub 6} units. Differential scanning calorimetry (DSC) measurements were carried out to measure the glass transition temperature of all the glasses. From the optical absorption spectra, luminescence spectra and using the JuddOfelt (JO) analysis, we estimated the radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes. The decay curves at lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (?0.5 mol%) due to energy transfer processes. The effective lifetime for the {sup 4}F{sub 9/2} level decreases with increase in Dy{sub 2}O{sub 3} concentration for the glasses under investigation. The non-exponential decay curves could fit well to the InokutiHirayama (IH) model with S = 6, indicating that the nature of interaction responsible for energy transfer is of dipoledipole type. Simulation of white light is examined with varying concentration and the results indicate that these glasses are suitable for white light emitting diode applications.

  7. Subaerial meteoric calcitization and lithification of high-magnesian calcite muds, Belize

    SciTech Connect

    Mazzullo, S.J.; Bischoff, W.D. )

    1991-03-01

    Holocene ({lt}1000-1500 yrs old) high-magnesian calcite-dominated muddy sediments (1 m thick) on subaerially exposed cays in northern Belize are in the process of being converted to low-magnesian calcite micrite. Mineralogic stabilization and attendant lithification result from interaction of the sediments with meteoric fluids believed to be derived from seasonal upward discharge through subjacent Pleistocene limestones. The initial marine-derived sediments, composed of {gt}85% HMC (and minor skeletal aragonite), consist of mud and associated soritid and miliolid foraminifera both with MgCO{sub 3} content of 11-15 mol%, and isotopic compositions of -1.0 to -2.5{per thousand} PDB (O), 0 to +1.5{per thousand} PDB (C). With depth, lithified LMC crusts appear in the section, and the Mg concentration of the sediments and associated crusts decreases rapidly to 3 mol% or less, with a corresponding isotopic depletion to values approaching -7.0{per thousand} (O) and -5.8{per thousand} (C). Concomitantly there is progressive dissolution of skeletal aragonite in the sediments, reduction of porosity due to cementation by LMC, and in the muds, a decrease in Sr and increase in Mn contents. The resultant petrofabric of these lithified LMC deposits, derived from the alteration of HMC-dominated muds, is characterized by micrite with patches of pore-filling micritic and microsparitic LMC cements. Such a fabric is similar to and can be confused easily with calcitized aragonite-dominated precursor muds, except for the relative rarity in the samples examined of aragonite relicts in component microspar and/or pseudospar.

  8. Characteristics of a new creep regime in polycrystalline NiAl

    SciTech Connect

    Raj, S.V.; Farmer, S.C. )

    1995-02-01

    Constant-load creep tests were conducted on fine-grained ([approximately]23 [mu]m) Ni-50.6 (at. pct) Al in the temperature range of 1,000 to 1,400 K. Power-law creep with a stress exponent, n [approx] 6.5, and an activation energy, Q[sub c] [approx] 290 kJ mol[sup [minus]1], was observed above 25 MPa, while a new mechanism with n [approx] 2 and Q[sub c] [approx] 100 kJ mol[sup [minus]1] dominates when [sigma] < 25 MPa, where [sigma] is the applied stress. A comparison of the creep behavior of fine- and course-grained NiAl established that the mechanism in the n [approx] 2 region was dependent on grain size, and the magnitude of the grain-size exponent was estimated to be about 2. Transmission electron microscopy (TEM) observations of the deformed specimens revealed a mixture of dislocation tangles, dipoles, loops, and subboundary networks in the power-law creep regime. The deformation microstructures were inhomogeneous in the n [approx] 2 creep regime, and many grains did not reveal any dislocation activity. However, bands of dislocation loops were observed in a few grains, where these loops appeared to have been emitted from the grain boundaries. The observed creep characteristics of the low-stress region suggest the dominance of an accommodated grain-boundary sliding (GBS) mechanism, although the experimental creep rates were lower than those predicted by theoretical models by over seven orders of magnitude. The low value of Q[sub c] in this region, which is approximately one-third that for lattice self-diffusion, is attributed to the possible existence of interconnected vacancy flow channels, or nanotubes'', at the grain boundaries.

  9. Communication: Orientational self-ordering of spin-labeled cholesterol analogs in lipid bilayers in diluted conditions

    SciTech Connect

    Kardash, Maria E.; Dzuba, Sergei A.

    2014-12-07

    Lipid-cholesterol interactions are responsible for different properties of biological membranes including those determining formation in the membrane of spatial inhomogeneities (lipid rafts). To get new information on these interactions, electron spin echo (ESE) spectroscopy, which is a pulsed version of electron paramagnetic resonance (EPR), was applied to study 3β-doxyl-5α-cholestane (DCh), a spin-labeled analog of cholesterol, in phospholipid bilayer consisted of equimolecular mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine. DCh concentration in the bilayer was between 0.1 mol.% and 4 mol.%. For comparison, a reference system containing a spin-labeled 5-doxyl-stearic acid (5-DSA) instead of DCh was studied as well. The effects of “instantaneous diffusion” in ESE decay and in echo-detected (ED) EPR spectra were explored for both systems. The reference system showed good agreement with the theoretical prediction for the model of spin labels of randomly distributed orientations, but the DCh system demonstrated remarkably smaller effects. The results were explained by assuming that neighboring DCh molecules are oriented in a correlative way. However, this correlation does not imply the formation of clusters of cholesterol molecules, because conventional continuous wave EPR spectra did not show the typical broadening due to aggregation of spin labels and the observed ESE decay was not faster than in the reference system. So the obtained data evidence that cholesterol molecules at low concentrations in biological membranes can interact via large distances of several nanometers which results in their orientational self-ordering.

  10. Characterization of a symbiotic coculture of Clostridium thermohydrosulfuricum YM3 and clostridium thermocellum YM4

    SciTech Connect

    Mori, Yutaka )

    1990-01-01

    Clostridium thermohydrosulfuricum YM3 and C. thermocellum YM4 were isolated from a coculture which was obtained from an enrichment culture inoculated with volcanic soil in Izu Peninsula, Japan. Strain YM3 had advantages over reported C. thermohydrosulfuricum strains in that it fermented inulin and could accumulate ethanol up to 1.3% (wt/vol). The highest ethanol yield obtained was 1.96 mol/mol of anhydroglucose unit in cellobiose. Strain YM4 had features different from those reported in C. thermocellum strains: it formed spores rarely (at a frequency of <10{sup {minus}5}), it required CO{sub 2} and Na{sub 2}CO{sub 3} for growth, and it fermented sucrose. Strain YM4 completely decomposed 1% Avicel within 25 h when the inoculum constituted 2 % of the culture medium volume, and it produced 0.22 U of Avicelase and 2.21 U of carboxymethylcellulase per ml of the medium. The doubling times on Avicel, cellobiose, and glucose were 2.7, 1.1, and 1.6 h, respectively. Reconstructed cocultures of strains YM3 and YM4 were very stable and degraded Avicel more rapidly than did strain YM4 monoculture. Without yeast extract, neither microorganism was able to grow. However, the coculture grew on cellulose without yeast extract and produced ethanol in high yield. Moreover, cell-free spent culture broth of strain YM3 could replace yeast extract in supporting the growth of strain YM4. The symbiotic relationship of the two bacteria in cellulose fermentation is probably a case of mutualism.

  11. Advanced heat exchanger development for molten salts

    DOE PAGES [OSTI]

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet materialmore » in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.« less

  12. Global scale environmental control of plant photosynthetic capacity

    DOE PAGES [OSTI]

    Ali, Ashehad; Xu, Chonggang; Rogers, Alistair; McDowell, Nathan G.; Medlyn, Belinda E.; Fisher, Rosie A.; Wullschleger, Stan D.; Reich, Peter B.; Bauerle, William L.; Wilson, Cathy J.; et al

    2015-12-01

    Photosynthetic capacity, determined by light harvesting and carboxylation reactions, is a key plant trait that determines the rate of photosynthesis; however, in Earth System Models (ESMs) at a reference temperature, it is either a fixed value for a given plant functional type or derived from a linear function of leaf nitrogen content. In this study, we conducted a comprehensive analysis that considered correlations of environmental factors with photosynthetic capacity as determined by maximum carboxylation (Vc,m) rate scaled to 25°C (i.e., Vc,25; μmol CO2·m–2·s–1) and maximum electron transport rate (Jmax) scaled to 25°C (i.e., J25; μmol electron·m–2·s–1) at the global scale.more » Our results showed that the percentage of variation in observed Vc,25 and J25 explained jointly by the environmental factors (i.e., day length, radiation, temperature, and humidity) were 2–2.5 times and 6–9 times of that explained by area-based leaf nitrogen content, respectively. Environmental factors influenced photosynthetic capacity mainly through photosynthetic nitrogen use efficiency, rather than through leaf nitrogen content. The combination of leaf nitrogen content and environmental factors was able to explain ~56% and ~66% of the variation in Vc,25 and J25 at the global scale, respectively. As a result, our analyses suggest that model projections of plant photosynthetic capacity and hence land–atmosphere exchange under changing climatic conditions could be substantially improved if environmental factors are incorporated into algorithms used to parameterize photosynthetic capacity in ESMs.« less

  13. Homoepitaxy of ZnO and MgZnO Films at 90 C

    SciTech Connect

    Ehrentraut, Dirk; Goh, Gregory K.L.; Fujii, Katsushi; Ooi, Chin Chun; Quang, Le Hong; Fukuda, Tsuguo; Kano, Masataka; Zhang, Yuantao; Matsuoka, Takashi

    2014-06-01

    The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, Mg{sub x}Zn{sub 1?x}O, films under very low temperature conditions at T=90 C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na{sub 3}C{sub 6}H{sub 5}O{sub 7}, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO{sub 3}){sub 2}6H{sub 2}O, favors the growth of films with pronounced faceting. - Graphical abstract: Homoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by (1 0 1{sup } 1) facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only. - Highlights: A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films. ZnO growth on (0 0 0 1) and (0 0 0 1{sup }) face resulted in films that are strongly different in their structural and optical quality. Single crystalline MgZnO film was fabricated under mild conditions (90 C and ambient pressure). Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

  14. Sustainable and efficient biohydrogen production via electrohydrogenesis

    SciTech Connect

    Cheng, S.; Logan, B.E.

    2007-11-20

    Hydrogen gas has tremendous potential as an environmentally acceptable energy carrier for vehicles, but most hydrogen is generated from nonrenewable fossil fuels such as natural gas. Here, the authors show that efficient and sustainable hydrogen production is possible from any type of biodegradable organic matter by electrohydrogenesis. In this process, protons and electrons released by exoelectrogenic bateria in specially designed reactors (based on modifying microbial fuel cells) are catalyzed to form hydrogen gas through the addition of a small voltage to the circuit. By improving the materials and reactor architecture, hydrogen gas was produced at yields of 2.01-3.95 mol/mol (50-99% of the theoretical maximum) at applied voltages of 0.2 to 0.8 V using acetic acid, a typical dead-end product of glucose or cellulose fermentation. At an applied voltage of 0.6 V, the overall energy efficiency of the process was 288% based solely on electricity applied, and 82% when the heat of combusion of acetic acid was included in the energy balance, at a gas production rate of 1.1 m{sup 3} of H{sub 2} per cubic meter of reactor per day. Direct high-yield hydrogen gas production was further demonstrated by using glucose, several volatile acids (acetic, butyric, lactic, propionic, and valeric), and cellulose at maximum stoichiometric yields of 54-91% and overall energy efficiencies of 64-82%. This electrohydrogenic process thus provides a highly efficient route for producting hydrogen gas from renewable and carbon-neutral biomass resources.

  15. Isomerization and dissociation in competition: The two-component dissociation rates of methyl propionate ions

    SciTech Connect

    Mazyar, O.A.; Baer, T.

    1999-03-04

    Threshold photoelectron-photoion coincidence (TPEPICO) spectroscopy has been used to investigate the unimolecular chemistry of gas-phase methyl propionate ions. This ion undergoes isomerization to a lower energy enol structure, CH{sub 3}CHC(OH)OCH{sub 3}{sup {sm_bullet}+}, via two different pathways involving two distonic isomers, {sup {sm_bullet}}CH{sub 2}CH{sub 2}C{sup +}(OH)OCH{sub 3} and CH{sub 3}CH{sub 2}C{sup +}(OH)OCH{sub 2}{sup {sm_bullet}}. This isomerization reaction is in competition with the direct CH{sub 3}O{sup {sm_bullet}} loss reaction, which leads to two-component dissociation rates of the methyl propionate ions. Detailed modeling of this complex reaction permitted the extraction of the dissociative photoionization threshold for methyl propionate, which at 0 K is 10.83 {+-} 0.01 eV, as well as the isomerization barrier between the distonic CH{sub 3}CH{sub 2}C{sup +}(OH)OCH{sub 2}{sup {sm_bullet}} and enol CH{sub 3}CHC(OH)OCH{sub 3}{sup {sm_bullet}+} ions of 8.5 kcal/mol (relative to the methyl propionate ion). By combining this with the 0 K heats of formation of methyl propionate and the methoxy radical, the authors derive a 0 K heat of formation of the product propanoyl ion of 147 kcal/mol. Also measured was the adiabatic ionization energy of methyl propionate, 10.03 {+-} 0.05 eV.

  16. Kinetic and Crystallgraphic Studies of a Redesigned Manganese-Binding Site in Cytochrome c Peroxidase

    SciTech Connect

    Pfister,T.; Mirarefi, A.; Gengenbach, A.; Zhao, X.; Danstrom , C.; Conatser, N.; Gao, Y.; Robinson, H.; Zukoski, C.; et al.

    2007-01-01

    Manganese peroxidase (MnP) from the white rot fungus Phanerochaete chrysosporium contains a manganese-binding site that plays a critical role in its function. Previously, a Mn{sup II}-binding site was designed into cytochrome c peroxidase (CcP) based on sequence homology (Yeung et al. in Chem. Biol. 4:215-222, 1997; Gengenbach et al. in Biochemistry 38:11425-11432, 1999). Here, we report a redesign of this site based on X-ray structural comparison of MnP and CcP. The variant, CcP(D37E, V45E, H181E), displays 2.5-fold higher catalytic efficiency (k{sub cat}/k{sub M}) than the variant in the original design, mostly due to a stronger k{sub M} of 1.9 mM (vs. 4.1 mM). High-resolution X-ray crystal structures of a metal-free form and a form with Co{sup II} at the designed Mn{sup II} site were also obtained. The metal ion in the engineered metal-binding site overlays well with Mn{sup II} bound in MnP, suggesting that this variant is the closest structural model of the Mn{sup II}-binding site in MnP for which a crystal structure exists. A major difference arises in the distances of the ligands to the metal; the metal-ligand interactions in the CcP variant are much weaker than the corresponding interactions in MnP, probably owing to partial occupancy of metal ion at the designed site, difference in the identity of metal ions (Co{sup II} rather than Mn{sup II}) and other interactions in the second coordination sphere. These results indicate that the metal ion, the ligands, and the environment around the metal-binding site play important roles in tuning the structure and function of metalloenzymes.

  17. Estimation of the weighted CTDI{sub {infinity}} for multislice CT examinations

    SciTech Connect

    Li Xinhua; Zhang Da; Liu, Bob

    2012-02-15

    Purpose: The aim of this study was to examine the variations of CT dose index (CTDI) efficiencies, {epsilon}(CTDI{sub 100})=CTDI{sub 100}/CTDI{sub {infinity}}, with bowtie filters and CT scanner types. Methods: This was an extension of our previous study [Li, Zhang, and Liu, Phys. Med. Biol. 56, 5789-5803 (2011)]. A validated Monte Carlo program was used to calculate {epsilon}(CTDI{sub 100}) on a Siemens Somatom Definition scanner. The {epsilon}(CTDI{sub 100}) dependencies on tube voltages and beam widths were tested in previous studies. The influences of different bowtie filters and CT scanner types were examined in this work. The authors tested the variations of {epsilon}(CTDI{sub 100}) with bowtie filters on the Siemens Definition scanner. The authors also analyzed the published CTDI measurements of four independent studies on five scanners of four models from three manufacturers. Results: On the Siemens Definition scanner, the difference in {epsilon}(CTDI{sub W}) between using the head and body bowtie filters was 2.5% (maximum) in the CT scans of the 32-cm phantom, and 1.7% (maximum) in the CT scans of the 16-cm phantom. Compared with CTDI{sub W}, the weighted CTDI{sub {infinity}} increased by 30.5% (on average) in the 32-cm phantom, and by 20.0% (on average) in the 16-cm phantom. These results were approximately the same for 80-140 kV and 1-40 mm beam widths (4.2% maximum deviation). The differences in {epsilon}(CTDI{sub 100}) between the simulations and the direct measurements of four previous studies were 1.3%-5.0% at the center/periphery of the 16-cm/32-cm phantom (on average). Conclusions: Compared with CTDI{sub vol}, the equilibrium dose for large scan lengths is 30.5% higher in the 32-cm phantom, and is 20.0% higher in the 16-cm phantom. The relative increases are practically independent of tube voltages (80-140 kV), beam widths (up to 4 cm), and the CT scanners covered in this study.

  18. Near optimal energy selective x-ray imaging system performance with simple detectors

    SciTech Connect

    Alvarez, Robert E.

    2010-02-15

    Purpose: This article describes a method to achieve near optimal performance with low energy resolution detectors. Tapiovaara and Wagner [Phys. Med. Biol. 30, 519-529 (1985)] showed that an energy selective x-ray system using a broad spectrum source can produce images with a larger signal to noise ratio (SNR) than conventional systems using energy integrating or photon counting detectors. They showed that there is an upper limit to the SNR and that it can be achieved by measuring full spectrum information and then using an optimal energy dependent weighting. Methods: A performance measure is derived by applying statistical detection theory to an abstract vector space of the line integrals of the basis set coefficients of the two function approximation to the x-ray attenuation coefficient. The approach produces optimal results that utilize all the available energy dependent data. The method can be used with any energy selective detector and is applied not only to detectors using pulse height analysis (PHA) but also to a detector that simultaneously measures the total photon number and integrated energy, as discussed by Roessl et al. [Med. Phys. 34, 959-966 (2007)]. A generalization of this detector that improves the performance is introduced. A method is described to compute images with the optimal SNR using projections in a ''whitened'' vector space transformed so the noise is uncorrelated and has unit variance in both coordinates. Material canceled images with optimal SNR can also be computed by projections in this space. Results: The performance measure is validated by showing that it provides the Tapiovaara-Wagner optimal results for a detector with full energy information and also a conventional detector. The performance with different types of detectors is compared to the ideal SNR as a function of x-ray tube voltage and subject thickness. A detector that combines two bin PHA with a simultaneous measurement of integrated photon energy provides near ideal

  19. The Tail Wagging the Dog: Insights into Catalysis in R67 Dihydrofolate Reductase

    SciTech Connect

    Kamath, Ganesh K; Agarwal, Pratul K

    2010-01-01

    Plasmid-encoded R67 dihydrofolate reductase (DHFR) catalyzes a hydride transfer reaction between substrate dihydrofolate (DHF) and its cofactor, nicotinamide adenine dinucleotide phosphate (NADPH). R67 DHFR is a homotetramer that exhibits numerous characteristics of a primitive enzyme, including promiscuity in binding of substrate and cofactor, formation of nonproductive complexes, and the absence of a conserved acid in its active site. Furthermore, R67's active site is a pore, which is mostly accessible by bulk solvent. This study uses a computational approach to characterize the mechanism of hydride transfer. Not surprisingly, NADPH remains fixed in one-half of the active site pore using numerous interactions with R67. Also, stacking between the nicotinamide ring of the cofactor and the pteridine ring of the substrate, DHF, at the hourglass center of the pore, holds the reactants in place. However, large movements of the p-aminobenzoylglutamate tail of DHF occur in the other half of the pore because of ion pair switching between symmetry-related K32 residues from two subunits. This computational result is supported by experimental results that the loss of these ion pair interactions (located >13 {angstrom} from the center of the pore) by addition of salt or in asymmetric K32M mutants leads to altered enzyme kinetics [Hicks, S. N., et al. (2003) Biochemistry 42, 10569-10578; Hicks, S. N., et al. (2004) J. Biol. Chem. 279, 46995?47002]. The tail movement at the edge of the active site, coupled with the fixed position of the pteridine ring in the center of the pore, leads to puckering of the pteridine ring and promotes formation of the transition state. Flexibility coupled to R67 function is unusual as it contrasts with the paradigm that enzymes use increased rigidity to facilitate attainment of their transition states. A comparison with chromosomal DHFR indicates a number of similarities, including puckering of the nicotinamide ring and changes in the DHF tail

  20. Final Report for Award DE-FG02-09ER64721

    SciTech Connect

    somerville, chris

    2014-04-26

    The original goal of this award was to develop a proteoglycan chip containing suitable oligosaccharides that could be used as substrates for glycosyltransferases involved in synthesis or proteoglycans in higher plant cell walls. We had previously developed a suite of cloned enzymes that could be used to cleave most of the relevant glycosidic linkages in plant cell walls. The next step, supported by the previous award and this award, was to produce a series of transgenic plants in which synthetic proteins were introduced that contained each of the known sequence motifs that induce prolyl hydroxylation, and subsequent glycosylation. This work was completed and published in Estevez et al (2006). We then engaged on a series of experiments to define the properties of the prolyl hydroxylases that convert certain prolyl resides to hydroxyproline for subsequent glycosylation. This proved to be a challenging goal that required recruitment of an international team of complementary skills and several additional years or research. However, the effort was successful and has been published in Science recenty (Velasquez et al., 2011). In the course of this project, the postdoc supported by the award (Jose Estevez) was asked to provide technical assistance to a colleague at Stanford because of his expertise in marine polysaccharides. This led to the important discovery that marine algae have compounds that could be classified as lignin (Martone et al., 2009). Publications supported by the award Estvez, J.M., Kieliszewski, M.J., Khitrov, N., Somerville, C. (2006) Characterization of synthetic hydroxyproline-rich proteoglycans with AGP- and extensin-motifs in Arabidopsis. Plant Physiol., 142,458-470 Martone, P.T., Estevez, J.M., Lu, F., Ruel, K., Ralph, J., Denny, M.W., Somerville, C.R. (2009) Discovery of lignin in seaweed reveals convergent evolution of cell-wall architecture. Curr. Biol., 19, 169-175 Velasquez, S.M., M. Ricardi, M.M., Dorosz, J.G., Fernandez, P.V., Nadra, A