Sample records for ruthenium dimer catalysis

  1. Blue Ruthenium Dimer Catalysis for Hydrogen Generation | Advanced...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Blue Ruthenium Dimer Catalysis for Hydrogen Generation APRIL 15, 2013 Bookmark and Share Key...

  2. Structure and Electronic Configurations of the Intermediates of Water Oxidation in Blue Ruthenium Dimer Catalysis

    SciTech Connect (OSTI)

    Moonshiram, Dooshaye; Jurss, Jonah W.; Concepcion, Javier J.; Zakharova, Taisiya; Alperovich, Igor; Meyer, Thomas J.; Pushkar, Yulia (Purdue); (UNC)

    2013-04-08T23:59:59.000Z

    Catalytic O{sub 2} evolution with cis,cis-[(bpy){sub 2}(H{sub 2}O)Ru{sup III}ORu{sup III}(OH{sub 2})(bpy){sub 2}]{sup 4+} (bpy is 2,2-bipyridine), the so-called blue dimer, the first designed water oxidation catalyst, was monitored by UV-vis, EPR, and X-ray absorption spectroscopy (XAS) with ms time resolution. Two processes were identified, one of which occurs on a time scale of 100 ms to a few seconds and results in oxidation of the catalyst with the formation of an intermediate, here termed [3,4]'. A slower process occurring on the time scale of minutes results in the decay of this intermediate and O{sub 2} evolution. Spectroscopic data suggest that within the fast process there is a short-lived transient intermediate, which is a precursor of [3,4]'. When excess oxidant was used, a highly oxidized form of the blue dimer [4,5] was spectroscopically resolved within the time frame of the fast process. Its structure and electronic state were confirmed by EPR and XAS. As reported earlier, the [3,4]' intermediate likely results from reaction of [4,5] with water. While it is generated under strongly oxidizing conditions, it does not display oxidation of the Ru centers past [3,4] according to EPR and XAS. EXAFS analysis demonstrates a considerably modified ligand environment in [3,4]'. Raman measurements confirmed the presence of the O-O fragment by detecting a new vibration band in [3,4]' that undergoes a 46 cm{sup -1} shift to lower energy upon {sup 16}O/{sup 18}O exchange. Under the conditions of the experiment at pH 1, the [3,4]' intermediate is the catalytic steady state form of the blue dimer catalyst, suggesting that its oxidation is the rate-limiting step.

  3. Sensitivity of the Properties of Ruthenium Blue Dimer”...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Sensitivity of the Properties of Ruthenium Blue Dimer” to Method, Basis Set, and Continuum Model. Sensitivity of the Properties of Ruthenium Blue Dimer” to Method,...

  4. Sensitivity of the Properties of Ruthenium “Blue Dimer” to Method, Basis Set, and Continuum Model

    SciTech Connect (OSTI)

    Ozkanlar, Abdullah; Clark, Aurora E.

    2012-05-23T23:59:59.000Z

    The ruthenium “blue dimer” [(bpy)2RuIIIOH2]2O4+ is best known as the first well-defined molecular catalyst for water oxidation. It has been subject to numerous computational studies primarily employing density functional theory. However, those studies have been limited in the functionals, basis sets, and continuum models employed. The controversy in the calculated electronic structure and the reaction energetics of this catalyst highlights the necessity of benchmark calculations that explore the role of density functionals, basis sets, and continuum models upon the essential features of blue-dimer reactivity. In this paper, we report Kohn-Sham complete basis set (KS-CBS) limit extrapolations of the electronic structure of “blue dimer” using GGA (BPW91 and BP86), hybrid-GGA (B3LYP), and meta-GGA (M06-L) density functionals. The dependence of solvation free energy corrections on the different cavity types (UFF, UA0, UAHF, UAKS, Bondi, and Pauling) within polarizable and conductor-like polarizable continuum model has also been investigated. The most common basis sets of double-zeta quality are shown to yield results close to the KS-CBS limit; however, large variations are observed in the reaction energetics as a function of density functional and continuum cavity model employed.

  5. catalysis | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    analysis radionuclides aerosols catalysis renewable energy subsurface geological field battery materials catalyst beds geochemistry ion microprobe high sensitivity high mass...

  6. Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis

    E-Print Network [OSTI]

    RajanBabu, T. V. "Babu"

    , 151. (b) Chauvin, Y.; Olivier, H. Dimerization and Codimerization. In Applied Homogeneous Catalysis) Jolly, P. W.; Wilke, G. Hydrovinylation. In Applied Homoge- neous Catalysis with Organometallic to Asymmetric Catalysis T. V. RajanBabu,* Nobuyoshi Nomura, Jian Jin, Malay Nandi, Haengsoon Park, and Xiufeng

  7. INSTITUTE FOR INTEGRATED CATALYSIS Catalysis Research for

    E-Print Network [OSTI]

    . This work includes catalysis for upgrading biomass feedstocks; for chemical energy storage, retrieval

  8. Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for Lithium-O2 Batteries

    SciTech Connect (OSTI)

    Bhattacharya, Priyanka; Nasybulin, Eduard N.; Engelhard, Mark H.; Kovarik, Libor; Bowden, Mark E.; Li, Shari; Gaspar, Daniel J.; Xu, Wu; Zhang, Jiguang

    2014-12-01T23:59:59.000Z

    Dendrimer-encapsulated ruthenium nanoparticles (DEN-Ru) have been used as catalysts in lithium-O2 batteries for the first time. Results obtained from UV-vis spectroscopy, electron microscopy and X-ray photoelectron spectroscopy show that the nanoparticles synthesized by the dendrimer template method are ruthenium oxide instead of metallic ruthenium reported earlier by other groups. The DEN-Ru significantly improve the cycling stability of lithium (Li)-O2 batteries with carbon black electrodes and decrease the charging potential even at low catalyst loading. The monodispersity, porosity and large number of surface functionalities of the dendrimer template prevent the aggregation of the ruthenium nanoparticles making their entire surface area available for catalysis. The potential of using DEN-Ru as stand-alone cathode materials for Li-O2 batteries is also explored.

  9. 2012 Catalysis Lectures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Bert Weckhuysen, who holds the chair of Inorganic Chemistry and Catalysis at Utrecht University, will give a series of catalysis lectures during his sabbatical period at...

  10. Heterogeneous Catalysis Environmental Catalysis and Processes

    E-Print Network [OSTI]

    Vardi, Amichay

    Department of Chemical Engineering Ben ­ Gurion University of the Negev Blechner Center for Applied CatalysisHeterogeneous Catalysis Environmental Catalysis and Processes Renewable Fuels M. Herskowitz Nanotechnology and advanced methods are applied in use inspired research #12;Fundamental research of catalytic

  11. Catalysis Workshop

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced. C o w l i t z C o . C lKieling ,Catalysis Science

  12. How Serotonin Receptors Can Shape Drug Effects, from LSD to Migraine...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    X-rays Paint a Picture of Picasso's Pigments Antibody Evolution Could Guide HIV Vaccine Development Blue Ruthenium Dimer Catalysis for Hydrogen Generation A High-Pressure...

  13. SOUTHWEST CATALYSIS 2012 SPRING SYMPOSIUM

    E-Print Network [OSTI]

    ) "Catalysis to Meet the Energy Challenge" 11:00 AM Southwest Catalysis Society Excellence in Applied CatalysisSOUTHWEST CATALYSIS SOCIETY 2012 SPRING SYMPOSIUM April 20, 2012 Duncan Hall - McMurtry Auditorium registration fee is $50, which includes North American Catalysis Society and SWCS yearly membership dues, along

  14. Structure of a Loose Dimer: an Intermediate in Nitric Oxide Synthase Assembly

    SciTech Connect (OSTI)

    Pant,K.; Crane, B.

    2005-01-01T23:59:59.000Z

    Cooperativity among ligand binding, subunit association, and protein folding has implications for enzyme regulation as well as protein aggregation events associated with disease. The binding of substrate l-arginine or cofactor tetrahydrobiopterin converts nitric oxide synthases (NOSs) from a 'loose dimer', with an exposed active center and higher sensitivity to proteolysis, to a 'tight dimer' competent for catalysis. The crystallographic structure of the Bacillus subtilis NOS loose dimer shows an altered association state with severely destabilized subdomains. Ligand binding or heme reduction converts loose dimers to tight dimers in solution and crystals. Mutations at key positions in the dimer interface that distinguish prokaryotic from eukaryotic NOSs affect the propensity to form loose dimers. The loose dimer structure indicates that non-native interactions can mediate subunit association in NOS.

  15. EMSL - In situ catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    situ-catalysis en New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella http:www.emsl.pnl.govemslwebpublications...

  16. Computational Catalysis and Electrocatalysis

    E-Print Network [OSTI]

    · Hydrogen storage · Photocatalysis #12;Fuel cell electrocatalysts Parallelism between bimetallics projects: photo-catalysis water decomposes over a catalyst producing oxygen and hydrogen From members

  17. Moderated ruthenium fischer-tropsch synthesis catalyst

    DOE Patents [OSTI]

    Abrevaya, Hayim (Wilmette, IL)

    1991-01-01T23:59:59.000Z

    The subject Fischer-Tropsch catalyst comprises moderated ruthenium on an inorganic oxide support. The preferred moderator is silicon. Preferably the moderator is effectively positioned in relationship to ruthenium particles through simultaneous placement on the support using reverse micelle impregnation.

  18. SOUTHWEST CATALYSIS 2013 SPRING SYMPOSIUM

    E-Print Network [OSTI]

    Natelson, Douglas

    -free Substrates" 11:05 AM Southwest Catalysis Society Excellence in Applied Catalysis Award James "Jerry" SpiveySOUTHWEST CATALYSIS SOCIETY 2013 SPRING SYMPOSIUM Friday, April 26, 2013 Grand Hall of the Ley registration fee is $50, which includes North American Catalysis Society and SWCS yearly membership dues, along

  19. Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for Lithium-O2 Batteries. Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for Lithium-O2 Batteries....

  20. Catalysis Research for Energy Independence

    E-Print Network [OSTI]

    yields insights into improving the industrial catalyst for oil refining, chemicals processing into chemical fuels. In addition, we conduct applied catalysis research with industrial, academic, and other collaborate with catalysis leaders in academia, industry, and national laboratories. Research in Science

  1. Cationic Ruthenium Catalysts for Olefin Hydrovinylation 

    E-Print Network [OSTI]

    Sanchez, Richard P., Jr

    2010-01-14T23:59:59.000Z

    ............................................... 11 1.5 Specific Aim............................................................................. 13 II INVESTIGATION OF A RUTHENIUM-BASED CATALYST SYSTEM FOR THE HYDROVINYLATION REACTION................ 15 2.1 Initial Study... and Application.................................................... 15 2.2 Mode of Deactivation............................................................... 20 III INTRODUCING CHELATING, BIDENTATE PHOSPHINE LIGANDS TO THE RUTHENIUM METAL CENTER...

  2. Heterogeneous Catalysis on Atomically Dispersed Supported Metals...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Catalysis on Atomically Dispersed Supported Metals: CO2 Reduction on Multifunctional Pd Catalysts. Heterogeneous Catalysis on Atomically Dispersed Supported Metals: CO2 Reduction...

  3. Platinum-ruthenium-nickel fuel cell electrocatalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2005-07-26T23:59:59.000Z

    A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum, ruthenium, and nickel, wherein the nickel is at a concentration that is less than about 10 atomic percent.

  4. Cationic Ruthenium Catalysts for Olefin Hydrovinylation

    E-Print Network [OSTI]

    Sanchez, Richard P., Jr

    2010-01-14T23:59:59.000Z

    CATIONIC RUTHENIUM CATALYSTS FOR OLEFIN HYDROVINYLATION A Thesis by RICHARD P. SANCHEZ, JR. Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 2009 Major Subject: Chemistry CATIONIC RUTHENIUM CATALYSTS FOR OLEFIN HYDROVINYLATION A Thesis by RICHARD P. SANCHEZ, JR. Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment...

  5. asymmetric catalysis stereoelectronic: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    X Lewis Acid Catalysis Brnsted Acid Catalysis X Johnson, Jeff S. 2 Multidimensional free energy relationships in asymmetric catalysis. Open Access Theses and Dissertations...

  6. Magnetic catalysis and inverse magnetic catalysis in QCD

    E-Print Network [OSTI]

    Niklas Mueller; Jan M. Pawlowski

    2015-02-27T23:59:59.000Z

    We investigate the effects of strong magnetic fields on the QCD phase structure at vanishing density by solving the gluon and quark gap equations, and by studying the dynamics of the quark scattering with the four-fermi coupling. The chiral crossover temperature as well as the chiral condensate are computed. For asymptotically large magnetic fields we find magnetic catalysis, while we find inverse magnetic catalysis for intermediate magnetic fields. Moreover, for large magnetic fields the chiral phase transition for massless quarks turns into a crossover. The underlying mechanisms are then investigated analytically within a few simplifications of the full numerical analysis. We find that a combination of gluon screening effects and the weakening of the strong coupling is responsible for the phenomenon of inverse catalysis. In turn, the magnetic catalysis at large magnetic field is already indicated by simple arguments based on dimensionality.

  7. Synthetic Catalysis of Amide Isomerization

    E-Print Network [OSTI]

    Lectka, Thomas

    , they may play other roles in vivo, including the catalysis of protein folding, functioning as auxiliary seem to be a possible way to catalyze protein folding in vitro, and experiments along these lines

  8. Enhanced Micellar Catalysis LDRD.

    SciTech Connect (OSTI)

    Betty, Rita G.; Tucker, Mark David; Taggart, Gretchen; Kinnan, Mark K.; Glen, Crystal Chanea; Rivera, Danielle; Sanchez, Andres; Alam, Todd Michael

    2012-12-01T23:59:59.000Z

    The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesota's Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

  9. Fuel Synthesis Catalysis Laboratory (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2011-07-01T23:59:59.000Z

    This fact sheet provides information about Fuel Synthesis Catalysis Laboratory capabilities and applications at NREL's National Bioenergy Center.

  10. Fuel Synthesis Catalysis Laboratory (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2013-07-01T23:59:59.000Z

    This fact sheet provides information about Fuel Synthesis Catalysis Laboratory capabilities and applications at NREL's National Bioenergy Center.

  11. A method for activation analysis of ruthenium in sea water 

    E-Print Network [OSTI]

    Dixon, Bryan William

    1965-01-01T23:59:59.000Z

    of Ruthenium in the Gulf of Mexico . 8 Solubility of Ruthenium in Sea Water C H A P T E R I INTRODUCTION Ruthenium, the rarest of the platinum metals, was discovered in 1845 by Klaus. Sidgewick (1950) and Goldschmidt (1954) state an abundance of about 0... of allow ing for the detection of the contributing physical and chemical forms to the total present. It is thought that the method is applicable to marine biota and sediments as well as water samples. The concentrations of soluble ruthenium found...

  12. PHOTOCHEMICAL CO2 REDUCTION BY RHENUIM AND RUTHENIUM COMPLEXES.

    SciTech Connect (OSTI)

    FUJITA,E.; MUCKERMAN, J.T.; TANAKA, K.

    2007-11-30T23:59:59.000Z

    Photochemical conversion of CO{sub 2} to fuels or useful chemicals using renewable solar energy is an attractive solution to both the world's need for fuels and the reduction of greenhouse gases. Rhenium(I) and ruthenium(II) diimine complexes have been shown to act as photocatalysts and/or electrocatalysts for CO{sub 2} reduction to CO. We have studied these photochemical systems focusing on the identification of intermediates and the bond formation/cleavage reactions between the metal center and CO{sub 2}. For example, we have produced the one-electron-reduced monomer (i.e. Re(dmb)(CO){sub 3}S where dmb = 4,4'-dimethy-2,2'-bipyridine and S = solvent) either by reductive quenching of the excited states of fac-[Re(dmb)(CO){sub 3}(CH{sub 3}CN)]PF{sub 6} or by photo-induced homolysis of [Re(dmb)(CO){sub 3}]{sub 2}. We previously found that: (1) the remarkably slow dimerization of Re(dmb)(CO){sub 3}S is due to the absence of a vacant coordination site for Re-Re bond formation, and the extra electron is located on the dmb ligand; (2) the reaction of Re(dmb)(CO){sub 3}S with CO{sub 2} forms a CO{sub 2}-bridged binuclear species (CO){sub 3}(dmb)Re-CO(O)-Re(dmb)(CO){sub 3} as an intermediate in CO formation; and (3) the kinetics and mechanism of reactions are consistent with the interaction of the CO{sub 2}-bridged binuclear species with CO{sub 2} to form CO and CO{sub 3}{sup 2-}.

  13. Icosahedral phase formation in rapidly quenched aluminum-ruthenium alloys

    E-Print Network [OSTI]

    Anlage, Steven

    Icosahedral phase formation in rapidly quenched aluminum- ruthenium alloys Steven M. Anlagea phases as a function of composition. We have chosen the aluminum-ruthenium alloy system because. %. The solidified alloys have been studied by electron microscopy and x-ray diffraction to determine

  14. Fischer-Tropsch synthesis process employing a moderated ruthenium catalyst

    DOE Patents [OSTI]

    Abrevaya, H.

    1990-07-31T23:59:59.000Z

    A Fischer-Tropsch type process produces hydrocarbons from carbon monoxide and hydrogen using a novel catalyst comprising moderated ruthenium on an inorganic oxide support. The preferred moderator is silicon. Preferably the moderator is effectively positioned in relationship to ruthenium particles through simultaneous placement on the support using reverse micelle impregnation. 1 fig.

  15. Fischer-Tropsch synthesis process employing a moderated ruthenium catalyst

    DOE Patents [OSTI]

    Abrevaya, Hayim (Wilmette, IL)

    1990-01-01T23:59:59.000Z

    A Fischer-Tropsch type process produces hydrocarbons from carbon monoxide and hydrogen using a novel catalyst comprising moderated ruthenium on an inorganic oxide support. The preferred moderator is silicon. Preferably the moderator is effectively positioned in relationship to ruthenium particles through simultaneous placement on the support using reverse micelle impregnation.

  16. Charge Transfer and Support Effects in Heterogeneous Catalysis

    E-Print Network [OSTI]

    Hervier, Antoine

    2012-01-01T23:59:59.000Z

    T. ; Haruta, M.  Applied Catalysis A:  General 1998, 169, Albert Vannice, M.  Applied Catalysis A: General 1994, 113, Viswanath, R.  P.  Applied Catalysis A: General 2001, 208, 

  17. Charge Transfer and Catalysis at the Metal-Support Interface

    E-Print Network [OSTI]

    Baker, Lawrence Robert

    2012-01-01T23:59:59.000Z

    A. ; Miko?ajska, A. Applied Catalysis A: General 2002, 233,T. ; Haruta, M. Applied Catalysis A: General 1998, 169,Albert Vannice, M. Applied Catalysis A: General 1994, 113, (

  18. Basic Research Needs: Catalysis for Energy

    SciTech Connect (OSTI)

    Bell, Alexis T.; Gates, Bruce C.; Ray, Douglas; Thompson, Michael R.

    2008-03-11T23:59:59.000Z

    The report presents results of a workshop held August 6-8, 2007, by DOE SC Basic Energy Sciences to determine the basic research needs for catalysis research.

  19. Workshop: Synchrotron Applications in Chemical Catalysis | Stanford...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Applications in Chemical Catalysis Tuesday, October 25, 2011 - 8:00am 2011 SSRLLCLS Annual Users Conference This workshop, part of the 2011 SSRLLCLS Annual Users...

  20. Plasma Assisted Catalysis System for NOx Reduction

    Broader source: Energy.gov (indexed) [DOE]

    2 NOXTECH NOXTECH PLASMA ASSISTED CATALYSIS SYSTEM FOR NOx REDUCTION BY NOXTECH With the Support & Cooperation of DOE Noxtech, Inc. *Delaware Corporation registered to do business...

  1. Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts The Bioenergy...

  2. Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis . Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis . Abstract: The research described in...

  3. Ruthenium / aerogel nanocomposits via Atomic Layer Deposition

    SciTech Connect (OSTI)

    Biener, J; Baumann, T F; Wang, Y; Nelson, E J; Kucheyev, S O; Hamza, A V; Kemell, M; Ritala, M; Leskela, M

    2006-08-28T23:59:59.000Z

    We present a general approach to prepare metal/aerogel nanocomposites via template directed atomic layer deposition (ALD). In particular, we used a Ru ALD process consisting of alternating exposures to bis(cyclopentadienyl)ruthenium (RuCp{sub 2}) and air at 350 C to deposit metallic Ru nanoparticles on the internal surfaces of carbon and silica aerogels. The process does not affect the morphology of the aerogel template and offers excellent control over metal loading by simply adjusting the number of ALD cycles. We also discuss the limitations of our ALD approach, and suggest ways to overcome these.

  4. DOE Laboratory Catalysis Research Symposium - Abstracts

    SciTech Connect (OSTI)

    Dunham, T.

    1999-02-01T23:59:59.000Z

    The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.

  5. Column Asymmetric Catalysis for -Lactam Synthesis

    E-Print Network [OSTI]

    Lectka, Thomas

    Column Asymmetric Catalysis for -Lactam Synthesis Ahmed M. Hafez, Andrew E. Taggi, Harald Wack that constitute the packing of a series of "reaction columns". This process was applied to the catalytic- and diastereoselectivity. In the realm of chiral synthesis and drug discovery, asym- metric catalysis1 and solid

  6. Topics in Catalysis ISSN 1022-5528

    E-Print Network [OSTI]

    Frenkel, Anatoly

    1 23 Topics in Catalysis ISSN 1022-5528 Top Catal DOI 10.1007/s11244-013-0053-y Characterization ubiquitous catalytic systems commonly used [1­6]. Despite significant progress made in developing catalysis, the challenge remains in the co-interpretation of their results since these methods are commonly applied

  7. Synthesis and Characterization of Hydrous Ruthenium Oxide-Carbon Supercapacitors

    E-Print Network [OSTI]

    Popov, Branko N.

    as compared to bare carbon. An electroless deposition process was used to synthesize the ruthenium oxideO2, Co3O4, and NiO2. Nickel oxide films have been synthesized both electrochemically4 and also

  8. Nickel/ruthenium catalyst and method for aqueous phase reactions

    DOE Patents [OSTI]

    Elliott, Douglas C. (Richland, WA); Sealock, John L. (West Richland, WA)

    1998-01-01T23:59:59.000Z

    A method of hydrogenation using a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional ruthenium metal deposited onto the support in a second dispersed phase. The additional ruthenium metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase thereby increasing the life time of the catalyst during hydrogenation reactions.

  9. "Nanocrystal bilayer for tandem catalysis"

    SciTech Connect (OSTI)

    Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

    2011-01-24T23:59:59.000Z

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

  10. asymmetric catalysis solvent-free: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    X Lewis Acid Catalysis Brnsted Acid Catalysis X Johnson, Jeff S. 2 Multidimensional free energy relationships in asymmetric catalysis. Open Access Theses and Dissertations...

  11. The CRAC channel consists of a tetramer formed by Stim-induced dimerization of Orai dimers

    E-Print Network [OSTI]

    Parker, Ian

    LETTERS The CRAC channel consists of a tetramer formed by Stim-induced dimerization of Orai dimers terminus of Stim thus induces Orai dimers to dimerize, forming tetramers that constitute the Ca21-treated cells14 , whereas functional measurements of expressed tandem Orai multimers indicate a tetramer

  12. Nanocrystal assembly for tandem catalysis

    DOE Patents [OSTI]

    Yang, Peidong; Somorjai, Gabor; Yamada, Yusuke; Tsung, Chia-Kuang; Huang, Wenyu

    2014-10-14T23:59:59.000Z

    The present invention provides a nanocrystal tandem catalyst comprising at least two metal-metal oxide interfaces for the catalysis of sequential reactions. One embodiment utilizes a nanocrystal bilayer structure formed by assembling sub-10 nm platinum and cerium oxide nanocube monolayers on a silica substrate. The two distinct metal-metal oxide interfaces, CeO.sub.2--Pt and Pt--SiO.sub.2, can be used to catalyze two distinct sequential reactions. The CeO.sub.2--Pt interface catalyzed methanol decomposition to produce CO and H.sub.2, which were then subsequently used for ethylene hydroformylation catalyzed by the nearby Pt--SiO.sub.2 interface. Consequently, propanal was selectively produced on this nanocrystal bilayer tandem catalyst.

  13. Magnetic Catalysis vs Magnetic Inhibition

    E-Print Network [OSTI]

    Kenji Fukushima; Yoshimasa Hidaka

    2012-09-06T23:59:59.000Z

    We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

  14. Height fluctuations in interacting dimers

    E-Print Network [OSTI]

    Alessandro Giuliani; Vieri Mastropietro; Fabio Lucio Toninelli

    2015-05-05T23:59:59.000Z

    We consider a non-integrable model for interacting dimers on the two-dimensional square lattice. Configurations are perfect matchings of $\\mathbb Z^2$, i.e. subsets of edges such that each vertex is covered exactly once ("close-packing" condition). Dimer configurations are in bijection with discrete height functions, defined on faces $\\boldsymbol{\\xi}$ of $\\mathbb Z^2$. The non-interacting model is "integrable" and solvable via Kasteleyn theory; it is known that all the moments of the height difference $h_{\\boldsymbol{\\xi}}-h_{\\boldsymbol{\\eta}}$ converge to those of the massless Gaussian Free Field (GFF), asymptotically as $|{\\boldsymbol{\\xi}}-{\\boldsymbol{\\eta}}|\\to \\infty$. We prove that the same holds for small non-zero interactions, as was conjectured in the theoretical physics literature. Remarkably, dimer-dimer correlation functions are instead not universal and decay with a critical exponent that depends on the interaction strength. Our proof is based on an exact representation of the model in terms of lattice interacting fermions, which are studied by constructive field theory methods. In the fermionic language, the height difference $h_{\\boldsymbol{\\xi}}-h_{\\boldsymbol{\\eta}}$ takes the form of a non-local operator, consisting of a sum of monomials along an {\\it arbitrary} path connecting $\\boldsymbol{\\xi}$ and $\\boldsymbol{\\eta}$. As in the non-interacting case, this path-independence plays a crucial role in the proof.

  15. Fiber optic D dimer biosensor

    DOE Patents [OSTI]

    Glass, R.S.; Grant, S.A.

    1999-08-17T23:59:59.000Z

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy. 4 figs.

  16. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    SciTech Connect (OSTI)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01T23:59:59.000Z

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  17. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Broader source: Energy.gov (indexed) [DOE]

    rappe.pdf More Documents & Publications Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO Oxidation Catalysis in...

  18. UNCORRECTEDPROOF Applied Catalysis B: Environmental 793 (2000) 19

    E-Print Network [OSTI]

    Jardim, Wilson de Figueiredo

    2000-01-01T23:59:59.000Z

    UNCORRECTEDPROOF Applied Catalysis B: Environmental 793 (2000) 1­9 Catalyst deactivation in the gas;UNCORRECTEDPROOF 2 R.M. Alberici et al. / Applied Catalysis B: Environmental 793 (2000) 1­9 when photo-oxidizing 1

  19. Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsourc...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Shining Light on Catalysis Tuesday, July 19, 2011 - 4:38pm SSRL Conference Room 137-322 Jeroen A. van Bokhoven, Professor for Heterogeneous Catalysis Institute for Chemical and...

  20. aqueous phase catalysis: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    corroborate asymmetry of catalysis in F0F1-ATP synthase. Zarrabi, Nawid; Diez, Manuel; Graeber, Peter; Wrachtrup, Joerg; Boersch, Michael 2007-01-01 292 Magnetic catalysis in hot...

  1. Nickel/ruthenium catalyst and method for aqueous phase reactions

    DOE Patents [OSTI]

    Elliott, D.C.; Sealock, J.L.

    1998-09-29T23:59:59.000Z

    A method of hydrogenation is described using a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional ruthenium metal deposited onto the support in a second dispersed phase. The additional ruthenium metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase thereby increasing the life time of the catalyst during hydrogenation reactions. 2 figs.

  2. Catalysis by Supported Gold Nanoclusters D. Wayne Goodman

    E-Print Network [OSTI]

    Goodman, Wayne

    by the selective oxidation of propylene to propylene oxide by gold,[4] alkene and arene hydrogenation catalysis,[5

  3. SouthWest Catalysis Society 2011 Spring Symposium

    E-Print Network [OSTI]

    Natelson, Douglas

    Award for Excellence in Applied Catalysis later in the day. On-site registration will begin at 7:30 AMSouthWest Catalysis Society 2011 Spring Symposium April 15, 2011 BioScience Research Collaborative in teaching and in the field of catalysis. Additionally, the Society is proud to present the inaugural SWCS

  4. Geometrically induced magnetic catalysis and critical dimensions

    E-Print Network [OSTI]

    Antonino Flachi; Kenji Fukushima; Vincenzo Vitagliano

    2015-02-21T23:59:59.000Z

    We discuss the combined effect of magnetic fields and geometry in interacting fermionic systems. At leading order in the heat-kernel expansion, the infrared singularity (that in flat space leads to the magnetic catalysis) is regulated by the chiral gap effect and the catalysis is deactivated by effect of the curvature. We discover that an infrared singularity may reappear from higher-order terms in the heat kernel expansion leading to a novel form of geometrically induced magnetic catalysis (absent in flat space). The dynamical mass squared is then modified not only due to the chiral gap effect by an amount proportional to the curvature, but also by a magnetic shift $\\propto (4-D)eB$ where $D$ represents the number of space-time dimensions. We argue that $D=4$ is a critical dimension across which the behaviour of the magnetic shift changes qualitatively.

  5. Geometrically induced magnetic catalysis and critical dimensions

    E-Print Network [OSTI]

    Flachi, Antonino; Vitagliano, Vincenzo

    2015-01-01T23:59:59.000Z

    We discuss the combined effect of magnetic fields and geometry in interacting fermionic systems. At leading order in the heat-kernel expansion, the infrared singularity (that in flat space leads to the magnetic catalysis) is regulated by the chiral gap effect and the catalysis is deactivated by effect of the curvature. We discover that an infrared singularity may reappear from higher-order terms in the heat kernel expansion leading to a novel form of geometrically induced magnetic catalysis (absent in flat space). The dynamical mass squared is then modified not only due to the chiral gap effect by an amount proportional to the curvature, but also by a magnetic shift $\\propto (4-D)eB$ where $D$ represents the number of space-time dimensions. We argue that $D=4$ is a critical dimension across which the behaviour of the magnetic shift changes qualitatively.

  6. Geometrically induced magnetic catalysis and critical dimensions

    E-Print Network [OSTI]

    Antonino Flachi; Kenji Fukushima; Vincenzo Vitagliano

    2015-04-27T23:59:59.000Z

    We discuss the combined effect of magnetic fields and geometry in interacting fermionic systems. At leading order in the heat-kernel expansion, the infrared singularity (that in flat space leads to the magnetic catalysis) is regulated by the chiral gap effect, and the catalysis is deactivated by the effect of the scalar curvature. We discover that an infrared singularity is found in higher-order terms that mix the magnetic field with curvature, and these lead to a novel form of geometrically induced magnetic catalysis. The dynamical mass squared is then modified not only due to the chiral gap effect by an amount proportional to the curvature, but also by a magnetic shift $\\propto (4-D)eB$, where $D$ represents the number of space-time dimensions. We argue that $D=4$ is a critical dimension across which the behavior of the magnetic shift changes qualitatively.

  7. Discovery of Yttrium, Zirconium, Niobium, Technetium, and Ruthenium Isotopes

    E-Print Network [OSTI]

    A. Nystrom; M. Thoennessen

    2011-02-11T23:59:59.000Z

    Currently, thirty-four yttrium, thirty-five zirconium, thirty-four niobium, thirty-five technetium, and thirty-eight ruthenium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  8. Discovery of Yttrium, Zirconium, Niobium, Technetium, and Ruthenium Isotopes

    E-Print Network [OSTI]

    Nystrom, A

    2011-01-01T23:59:59.000Z

    Currently, thirty-four yttrium, thirty-five zirconium, thirty-four niobium, thirty-five technetium, and thirty-eight ruthenium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  9. Dimerization specificities of leucine zipper mutants

    E-Print Network [OSTI]

    Rieker, Jennifer Dawn

    2013-02-22T23:59:59.000Z

    The dimerization specificity of a leucine zipper is partially determined by the interactions of charged amino acids on the surfaces of dimer interfaces (e and g positions). A series of e and g position GCN4 mutants has been described that do...

  10. Benzene Dimer: Dynamic Structure and Thermodynamics Derived from...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Benzene Dimer: Dynamic Structure and Thermodynamics Derived from On-the-Fly ab initio DFT-D Molecular Dynamic Simulations. Benzene Dimer: Dynamic Structure and Thermodynamics...

  11. Platinum-ruthenium-nickel alloy for use as a fuel cell catalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2004-04-20T23:59:59.000Z

    An improved noble metal alloy composition for a fuel cell catalyst, the alloy containing platinum, ruthenium, and nickel. The alloy shows methanol oxidation activity.

  12. Platinum-ruthenium-nickel alloy for use as a fuel cell catalyst

    DOE Patents [OSTI]

    Gorer, Alexander (Sunnyvale, CA)

    2003-01-01T23:59:59.000Z

    An improved noble metal alloy composition for a fuel cell catalyst, the alloy containing platinum, ruthenium, and nickel. The alloy shows methanol oxidation activity.

  13. Thermodynamic data bases for multivalent elements: An example for ruthenium

    SciTech Connect (OSTI)

    Rard, J.A.

    1987-11-01T23:59:59.000Z

    A careful consideration and understanding of fundamental chemistry, thermodynamics, and kinetics is absolutely essential when modeling predominance regions and solubility behavior of elements that exhibit a wide range of valence states. Examples of this are given using the ruthenium-water system at 298.15 K, for which a critically assessed thermochemical data base is available. Ruthenium exhibits the widest range of known aqueous solution valence states. Known solid anhydrous binary oxides of ruthenium are crystalline RuO/sub 2/, RuO/sub 4/, and possibly RuO/sub 3/ (thin film), and known hydroxides/hydrated oxides (all amorphous) are Ru(OH)/sub 3/ . H/sub 2/O, RuO/sub 2/ . 2H/sub 2/O, RuO/sub 2/ . H/sub 2/O, and a poorly characterized Ru(V) hydrous oxide. Although the other oxides, hydroxides, and hydrous oxides are generally obtained as precipitates from aqueous solutions, they are thermodynamically unstable with regard to RuO/sub 2/(cr) formation. Characterized aqueous species of ruthenium include RuO/sub 4/ (which slowly oxidizes water and which dissociates as a weak acid), RuO/sub 4//sup -/ and RuO/sub 4//sup 2 -/ (which probably contain lesser amounts of RuO/sub 3/(OH)/sub 2//sup -/ and RuO/sub 3/(OH)/sub 2//sup 2 -/, respectively, and other species), Ru(OH)/sub 2//sup 2 +/, Ru/sub 4/(OH)/sub 12//sup 4 +/, Ru(OH)/sub 4/, Ru/sup 3 +/, Ru(OH)/sup 2 +/, Ru(OH)/sub 2//sup +/, Ru/sup 2 +/, and some hydroxytetramers with formal ruthenium valences of 3.75 greater than or equal to Z greater than or equal to 2.0. Potential pH diagrams of the predominance regions change significantly with concentration due to polymerization/depolymerization reactions. Failure to consider the known chemistry of ruthenium can yield large differences in predicted solubilities.

  14. Heterogeneous Catalysis DOI: 10.1002/anie.201304610

    E-Print Network [OSTI]

    Iglesia, Enrique

    and Selectivity of Fischer­ Tropsch Synthesis on Ruthenium Catalysts** David D. Hibbitts, Brett T. Loveless, Matthew Neurock,* and Enrique Iglesia* Ru and Co catalyze Fischer­Tropsch synthesis (FTS) with high rates

  15. Complex of transferrin with ruthenium for medical applications

    DOE Patents [OSTI]

    Richards, Powell (Bayport, NY); Srivastava, Suresh C. (Setauket, NY); Meinken, George E. (Middle Island, NY)

    1984-05-15T23:59:59.000Z

    A novel Ruthenium-transferrin complex, prepared by reacting iron-free human transferrin dissolved in a sodium acetate solution at pH 7 with ruthenium by heating at about 40.degree. C. for about 2 hours, and purifying said complex by means of gel chromotography with pH 7 sodium acetate as eluent. The mono- or di-metal complex produced can be used in nuclear medicine in the diagnosis and/or treatment of tumors and abscesses. Comparative results with Ga-67-citrate, which is the most widely used tumor-localizing agent in nuclear medicine, indicate increased sensitivity of detection and greater tumor uptake with the Ru-transferrin complex.

  16. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01T23:59:59.000Z

    Catalytic Processes Applied Catalysis A: General 221 (2001)Kamp, J.J.F. Scholten Applied Catalysis A. : General 89 (77. S. Xie, M. Qiao Applied Catalysis A: General 176 (1999)

  17. Benzene Dimer DOI: 10.1002/anie.201300653

    E-Print Network [OSTI]

    Benzene Dimer DOI: 10.1002/anie.201300653 Structure of the Benzene Dimer--Governed by Dynamics van der Avoird* The benzene dimer is a prototypical system for studying noncovalent interactions in the structure and dynamic behavior of proteins and DNA. The first (1975) experimental study of the benzene dimer

  18. Nanoscale Advances in Catalysis and Energy Applications

    SciTech Connect (OSTI)

    Li, Yimin; Somorjai, Gabor A.

    2010-05-12T23:59:59.000Z

    In this perspective, we present an overview of nanoscience applications in catalysis, energy conversion, and energy conservation technologies. We discuss how novel physical and chemical properties of nanomaterials can be applied and engineered to meet the advanced material requirements in the new generation of chemical and energy conversion devices. We highlight some of the latest advances in these nanotechnologies and provide an outlook at the major challenges for further developments.

  19. USD Catalysis Group for Alternative Energy

    SciTech Connect (OSTI)

    James D. Hoefelmeyer, Ranjit Koodali, Grigoriy Sereda, Dan Engebretson, Hao Fong, Jan Puszynski, Rajesh Shende, Phil Ahrenkiel

    2012-03-13T23:59:59.000Z

    The South Dakota Catalysis Group (SDCG) is a collaborative project with mission to develop advanced catalysts for energy conversion with two primary goals: (1) develop photocatalytic systems in which polyfunctionalized TiO2 are the basis for hydrogen/oxygen synthesis from water and sunlight (solar fuels group), (2) develop new materials for hydrogen utilization in fuel cells (fuel cell group). In tandem, these technologies complete a closed chemical cycle with zero emissions.

  20. "Seeing" hydrogen atoms to unveil enzyme catalysis | ornl.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    "Seeing" hydrogen atoms to unveil enzyme catalysis Image shows nuclear density maps in the active site of DHFR where the catalytic group Asp27 and substrate folate have...

  1. Catalysis by Design - Theoretical and Experimental Studies of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Lean NOx Traps - Microstructural Studies of Real World and Model Catalysts Catalysts via First Principles Catalysis by Design: Bridging the Gap between Theory and Experiments...

  2. Catalysis by Design: Bridging the Gap between Theory and Experiments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    between Theory and Experiments Catalysis by Design: Bridging the Gap between Theory and Experiments Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research...

  3. Catalysis by Design: Bridging the Gap Between Theory and Experiments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Between Theory and Experiments at Nanoscale Level Catalysis by Design: Bridging the Gap Between Theory and Experiments at Nanoscale Level Studies on a simple platinum-alumina...

  4. Environment assisted energy transfer in dimer system

    SciTech Connect (OSTI)

    Khan, Salman, E-mail: sksafi@comsats.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Chak Shahzad, Islamabad (Pakistan)] [Department of Physics, COMSATS Institute of Information Technology, Chak Shahzad, Islamabad (Pakistan); Ibrahim, M.; Khan, M.K. [Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan)] [Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan)

    2014-02-15T23:59:59.000Z

    The influence of collective and multilocal environments on the energy transfer between the levels of a dimer is studied. The dynamics of energy transfer are investigated by considering coupling of collective environment with the levels of the dimer in the presence of both two individuals and mutually correlated multilocal environments. It is shown that every way of coupling we consider assists, though differently, the probability of transition between the levels of dimer. The probability of transition is strongly enhanced when the two local environments are mutually correlated. -- Highlights: • The dynamics of energy transfer between the levels of a dimer are studied. • Coupling of collective as well as individual environments are considered. • The environments are in spin star configurations. • The environment assists the energy transfer between the levels. • For correlated multilocal environments, the transition probability is almost 100%.

  5. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    SciTech Connect (OSTI)

    Overbury, Steven {Steve} H [ORNL; Coates, Leighton [ORNL; Herwig, Kenneth W [ORNL; Kidder, Michelle [ORNL

    2011-10-01T23:59:59.000Z

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  6. Synthesis, Characterization and Reactivity of Electrophilic Organometallic Compounds of Ruthenium, Tantalum and Silicon

    E-Print Network [OSTI]

    Ramirez, Rodrigo

    2014-12-11T23:59:59.000Z

    SYNTHESIS, CHARACTERIZATION AND REACTIVITY OF ELECTROPHILIC ORGANOMETALLIC COMPOUNDS OF RUTHENIUM, TANTALUM AND SILICON A Dissertation by RODRIGO RAMIREZ Submitted to the Office of Graduate and Professional Studies of Texas A... December 2014 Major Subject: Chemistry Copyright 2014 Rodrigo Ramírez ii ABSTRACT The work presented herein will discuss the synthesis, characterization and reactivity of electrophilic organometallic compounds of ruthenium, tantalum...

  7. A Literature Review on Ruthenium Behaviour in Nuclear Power Plant Severe Accidents

    E-Print Network [OSTI]

    Boyer, Edmond

    A Literature Review on Ruthenium Behaviour in Nuclear Power Plant Severe Accidents C. MUN , L Literature Review on Ruthenium Behaviour in Nuclear Power Plant Severe Accidents C. MUN a , L. CANTREL a , C Accidents Majeurs (DPAM), CEN Cadarache - France 1 b Commissariat à l'Energie Atomique (CEA), Direction de l'Energie

  8. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    E-Print Network [OSTI]

    Pennycook, Steve

    -EM Fischer Tropsch Catalysis on Fe- or Co-catalysts, ,,CTL" Coal to Liquids ­ ,a rough (?) analogy #12;Peter Albers, AQ-EM Carbonaceous Deposits on Catalysts #12;Peter Albers, AQ-EM IINS on Coked Catalysts from Industrial Plants High-temperature and low-temperature cokes deposited on catalysts during

  9. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    Frontiers in Catalysis Science and Engineering Seminar Series "Frustrated Lewis Pairs": Metal and applied to develop metal-free hydrogenations for C=N bonds in a variety of organic substrates. In addition, alkynes, cyclopropanes, CO2 and N2O. The implications of the discovery of such systems to catalysis

  10. Periodic Solutions of a Nonlinear Evolution Problem from Heterogeneous Catalysis

    E-Print Network [OSTI]

    Bothe, Dieter

    Periodic Solutions of a Nonlinear Evolution Problem from Heterogeneous Catalysis Dieter Bothe for heterogeneous catalysis in a stirred multi-phase chemical reactor. Since the appearance of T-periodic feeds for this evolution problem are provided and applied to the class of reaction-diffusion systems mentioned above. AMS

  11. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    Frontiers in Catalysis Science and Engineering Seminar Series Heterogenized M-Salen Catalysts complexes are widely applied as catalysts for numerous important enantioselective reactions. The reactions catalysis (e.g. Co-salen for epoxide ring-opening or Al-salen conjugate additions of cyanide). The design

  12. Materials and interfaces for catalysis, separation, storage, and environmental applications

    E-Print Network [OSTI]

    Li, Mo

    Materials and interfaces for catalysis, separation, storage, and environmental applications collaborative effort in cutting-edge fundamental and applied research to discover and develop polymeric' problems such as inexpensive CO2 capture, energy-efficient and high-performance catalysis and separations

  13. Heterogeneous Catalysis DOI: 10.1002/anie.201209476

    E-Print Network [OSTI]

    Kik, Pieter

    Heterogeneous Catalysis DOI: 10.1002/anie.201209476 Trends in the Binding Strength of Surface? These questions are at the heart of many fundamental and practical problems, ranging from heterogeneous catalysis to important applied processes con- nected to materials science. In particular the interaction of oxygen

  14. Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands

    E-Print Network [OSTI]

    Collum, David B.

    Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands Antonio Ramirez of a lithium diisopropylamide (LDA)-mediated ester enolization. Hemilabile amino ether MeOCH2CH2NMe2, binding-based catalysis are thwarted by the occlusion of the catalyst on the lithium salt products and byproducts (eq 1

  15. Dynamic control of catalysis within biological cells

    E-Print Network [OSTI]

    Biman Jana; Biman Bagchi

    2011-05-26T23:59:59.000Z

    We develop a theory of enzyme catalysis within biological cells where the substrate concentration [S](t) is time dependent, in contrast to the Michaelis-Menten theory that assumes a steady state. We find that the time varying concentration can combine, in a non-linear way, with the ruggedness of the free energy landscape of enzymes (discovered both in single molecule studies and in simulations) to provide a highly efficient switch (or, bifurcation) between two catalytically active states, at a critical substrate concentration. This allows a dynamic control of product synthesis in cell.

  16. Deposition of ruthenium nanoparticles on carbon aerogels for high energy density supercapacitor electrodes

    SciTech Connect (OSTI)

    Miller, J.M.; Dunn, B. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering; Tran, T.D.; Pekala, R.W. [Lawrence Livermore National Labs., CA (United States). Chemical Sciences Div.

    1997-12-01T23:59:59.000Z

    The preparation and characterization of high surface area ruthenium/carbon aerogel composite electrodes for use in electrochemical capacitors is reported. These new materials have been prepared by the chemical vapor impregnation of ruthenium into carbon aerogels to produce a uniform distribution of adherent {approx}20 {angstrom} nanoparticles on the aerogel surface. The electrochemically oxidized ruthenium particles contribute a pseudocapacitance to the electrode and dramatically improve the energy storage characteristics of the aerogel. These composites have demonstrated specific capacitances in excess of 200 F/g, in comparison to 95 F/g for the untreated aerogel.

  17. Universal bosonic tetramers of dimer-atom-atom structure

    E-Print Network [OSTI]

    A. Deltuva

    2012-03-28T23:59:59.000Z

    Unstable four-boson states having an approximate dimer-atom-atom structure are studied using momentum-space integral equations for the four-particle transition operators. For a given Efimov trimer the universal properties of the lowest associated tetramer are determined. The impact of this tetramer on the atom-trimer and dimer-dimer collisions is analyzed. The reliability of the three-body dimer-atom-atom model is studied.

  18. Universal bosonic tetramers of dimer-atom-atom structure

    E-Print Network [OSTI]

    Deltuva, A

    2012-01-01T23:59:59.000Z

    Unstable four-boson states having an approximate dimer-atom-atom structure are studied using momentum-space integral equations for the four-particle transition operators. For a given Efimov trimer the universal properties of the lowest associated tetramer are determined. The impact of this tetramer on the atom-trimer and dimer-dimer collisions is analyzed. The reliability of the three-body dimer-atom-atom model is studied.

  19. Volume$3, number 3 CHEMICAL. PHYSICS LETTERS 1 Februrf 1978 INTERACTION OF METHANOL WITH RUTHENIUM

    E-Print Network [OSTI]

    Goodman, Wayne

    Volume$3, number 3 CHEMICAL. PHYSICS LETTERS 1 Februrf 1978 INTERACTION OF METHANOL WITH RUTHENIUM of methanol with a clean methods. Methanol dissociates upon adsorption at 300 K and yields Ha(g) and chemisorbed CO as the domiwt

  20. Dye Sensitization of Nanocrystalline Titanium Dioxide with Osmium and Ruthenium Polypyridyl Complexes

    E-Print Network [OSTI]

    Sauvé, Geneviève

    Dye Sensitization of Nanocrystalline Titanium Dioxide with Osmium and Ruthenium Polypyridyl synthesized and used to sensitize nanoporous titanium dioxide electrodes to solar illumination. The spectral optimization in operating photoelectrochemical cells for solar energy conversion applications. Of the materials

  1. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    DOE Patents [OSTI]

    Corbea, Javier Jesus Concepcion; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L.; Hoertz, Paul; Meyer, Thomas J.

    2013-09-03T23:59:59.000Z

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  2. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    SciTech Connect (OSTI)

    Concepcion Corbea, Javier Jesus; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L; Hoertz, Paul; Meyer, Thomas J

    2014-10-28T23:59:59.000Z

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  3. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOE Patents [OSTI]

    Pierantozzi, R.

    1985-04-02T23:59:59.000Z

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  4. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOE Patents [OSTI]

    Pierantozzi, R.

    1985-04-09T23:59:59.000Z

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  5. Novel Ruthenium complexes and their application in dye sensitised solar cells 

    E-Print Network [OSTI]

    McCall, Keri Laura

    2009-01-01T23:59:59.000Z

    This work focuses on the design, synthesis and characterisation of novel ruthenium bipyridyl complexes and their use in dye sensitised solar cells (DSSCs). Four series of dyes have been synthesised with the general formula ...

  6. Ruthenium on rutile catalyst, catalytic system, and method for aqueous phase hydrogenations

    DOE Patents [OSTI]

    Elliot, Douglas C. (Richland, WA); Werpy, Todd A. (West Richland, WA); Wang, Yong (Richland, WA); Frye, Jr., John G. (Richland, WA)

    2001-01-01T23:59:59.000Z

    An essentially nickel- and rhenium-free catalyst is described comprising ruthenium on a titania support where the titania is greater than 75% rutile. A catalytic system containing a nickel-free catalyst comprising ruthenium on a titania support where the titania is greater than 75% rutile, and a method using this catalyst in the hydrogenation of an organic compound in the aqueous phase is also described.

  7. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    National Laboratory U.S. Department of Energy Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Ken Rapp, Liyu Li, Jonathan Male, Dave King...

  8. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    D.C. acep03rappe.pdf More Documents & Publications Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO...

  9. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (OFCVT). deer07rappe.pdf More Documents & Publications Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO...

  10. Redox, haem and CO in enzymatic catalysis and regulation

    E-Print Network [OSTI]

    Ragsdale, Stephen W.

    The present paper describes general principles of redox catalysis and redox regulation in two diverse systems. The first is microbial metabolism of CO by the Wood–Ljungdahl pathway, which involves the conversion of CO or ...

  11. Theoretical investigation of solar energy conversion and water oxidation catalysis

    E-Print Network [OSTI]

    Wang, Lee-Ping

    2011-01-01T23:59:59.000Z

    Solar energy conversion and water oxidation catalysis are two great scientific and engineering challenges that will play pivotal roles in a future sustainable energy economy. In this work, I apply electronic structure ...

  12. Frontiers in Catalysis Science and Engineering Materials Science

    E-Print Network [OSTI]

    Frontiers in Catalysis Science and Engineering Materials Science Chemical Imaging Date: May 13 the quality of human life but also critical to our survival. To power the planet for a better future

  13. Catalysis Working Group Kick-Off Meeting Agenda

    Broader source: Energy.gov [DOE]

    Agenda for the kick-off meeting of the U.S. Department of Energy Fuel Cell Technologies Program's Catalysis Working Group, held May 14, 2012, in Arlington, Virginia.

  14. Size Effect of Ruthenium Nanoparticles in Catalytic Carbon Monoxide Oxidation

    SciTech Connect (OSTI)

    Joo, Sang Hoon; Park, Jeong Y.; Renzas, J. Russell; Butcher, Derek R.; Huang, Wenyu; Somorjai, Gabor A.

    2010-04-04T23:59:59.000Z

    Carbon monoxide oxidation over ruthenium catalysts has shown an unusual catalytic behavior. Here we report a particle size effect on CO oxidation over Ru nanoparticle (NP) catalysts. Uniform Ru NPs with a tunable particle size from 2 to 6 nm were synthesized by a polyol reduction of Ru(acac){sub 3} precursor in the presence of poly(vinylpyrrolidone) stabilizer. The measurement of catalytic activity of CO oxidation over two-dimensional Ru NPs arrays under oxidizing reaction conditions (40 Torr CO and 100 Torr O{sub 2}) showed an activity dependence on the Ru NP size. The CO oxidation activity increases with NP size, and the 6 nm Ru NP catalyst shows 8-fold higher activity than the 2 nm catalysts. The results gained from this study will provide the scientific basis for future design of Ru-based oxidation catalysts.

  15. The physics doped Quantum Dimer Models

    E-Print Network [OSTI]

    Paris-Sud 11, Université de

    -charge separation ­ Topological defects and holon statistics · Approach based on the Quantum Dimer Model ­ A wide ­ Hole doping: exotic properties of holons #12;3 Collaborators · Arnaud Ralko (Toulouse) · Frédéric Mila superconductor under doping Holon (Q=e, S=0) « spin-charge separation » #12;8 Variational approach of RVB #12

  16. Applied Catalysis B: Environmental 140141 (2013) 468477 Contents lists available at SciVerse ScienceDirect

    E-Print Network [OSTI]

    Alvarez, Pedro J.

    2013-01-01T23:59:59.000Z

    Applied Catalysis B: Environmental 140­141 (2013) 468­477 Contents lists available at SciVerse ScienceDirect Applied Catalysis B: Environmental journal homepage: www

  17. Development of a stable cobalt-ruthenium Fisher-Tropsch catalyst. Final report

    SciTech Connect (OSTI)

    Frame, R.R.; Gala, H.B.

    1995-02-01T23:59:59.000Z

    The reverse micelle catalyst preparation method has been used to prepare catalysts on four supports: magnesium oxide, carbon, alumina- titania and steamed Y zeolite. These catalysts were not as active as a reference catalyst prepared during previous contracts to Union Carbide Corp. This catalyst was supported on steamed Y zerolite support and was impregnated by a pore-filling method using a nonaqueous solvent. Additional catalysts were prepared via pore- filling impregnation of steamed Y zeolites. These catalysts had levels of cobalt two to three and a half times as high as the original Union Carbide catalyst. On a catalyst volume basis they were much more active than the previous catalyst; on an atom by atom basis the cobalt was about of the same activity, i.e., the high cobalt catalysts` cobalt atoms were not extensively covered over and deactivated by other cobalt atoms. The new, high activity, Y zerolite catalysts were not as stable as the earlier Union Carbide catalyst. However, stability enhancement of these catalysts should be possible, for instance, through adjustment of the quantity and/or type of trace metals present. A primary objective of this work was determination whether small amounts of ruthenium could enhance the activity of the cobalt F-T catalyst. The reverse micelle catalysts were not activated by ruthenium, indeed scanning transmission electronic microscopy (STEM) analysis provided some evidence that ruthenium was not present in the cobalt crystallites. Ruthenium did not seem to activate the high cobalt Y zeolite catalyst either, but additional experiments with Y zeolite-supported catalysts are required. Should ruthenium prove not to be an effective promoter under the simple catalyst activation procedure used in this work, more complex activation procedures have been reported which are claimed to enhance the cobalt/ruthenium interaction and result in activity promotion by ruthenium.

  18. Solvation and Acid Strength Effects on Catalysis by Faujasite Zeolites

    SciTech Connect (OSTI)

    Gounder, Rajamani P.; Jones, Andrew J.; Carr, Robert T.; Iglesia, Enrique

    2012-02-01T23:59:59.000Z

    Kinetic, spectroscopic, and chemical titration data indicate that differences in monomolecular isobutane cracking and dehydrogenation and methanol dehydration turnover rates (per H+) among FAU zeolites treated thermally with steam (H-USY) and then chemically with ammonium hexafluorosilicate (CDHUSY) predominantly reflect differences in the size and solvating properties of their supercage voids rather than differences in acid strength. The number of protons on a given sample was measured consistently by titrations with Na+, with CH3 groups via reactions of dimethyl ether, and with 2,6-di-tert-butylpyridine during methanol dehydration catalysis; these titration values were also supported by commensurate changes in acidic OH infrared band areas upon exposure to titrant molecules. The number of protons, taken as the average of the three titration methods, was significantly smaller than the number of framework Al atoms (Alf) obtained from X-ray diffraction and 27Al magic angle spinning nuclear magnetic resonance spectroscopy on H-USY (0.35 H+/Alf) and CD-HUSY (0.69 H+/Alf). These data demonstrate that the ubiquitous use of Alf sites as structural proxies for active H+ sites in zeolites can be imprecise, apparently because distorted Al structures that are not associated with acidic protons are sometimes detected as Alf sites. Monomolecular isobutane cracking and dehydrogenation rate constants, normalized non-rigorously by the number of Alf species, decreased with increasing Na+ content on both H-USY and CD-HUSY samples and became undetectable at sub-stoichiometric exchange levels (0.32 and 0.72 Na+/Alf ratios, respectively), an unexpected finding attributed incorrectly in previous studies to the presence of minority ‘‘super-acidic’’ sites. These rate constants, when normalized rigorously by the number of residual H+ sites were independent of Na+ content on both H-USY and CD-HUSY samples, reflecting the stoichiometric replacement of protons that are uniform in reactivity by Na+ cations. Monomolecular isobutane cracking and dehydrogenation rate constants (per H+; 763 K), however, were higher on H-USY than CD-HUSY (by a factor of 1.4). Equilibrium constants for the formation of protonated methanol dimers via adsorption of gaseous methanol onto adsorbed methanol monomers, determined from kinetic studies of methanol dehydration to dimethyl ether (433 K), were also higher on H-USY than CD-HUSY (by a factor of 2.1). These larger constants predominantly reflect stronger dispersive interactions in H-USY, consistent with its smaller supercage voids that result from the occlusion of void space by extraframework Al (Alex) residues. These findings appear to clarify enduring controversies about the mechanistic interpretation of the effects of Na+ and Alex species on the catalytic reactivity of FAU zeolites. They also illustrate the need to normalize rates by the number of active sites instead of more convenient but less accurate structural proxies for such sites.

  19. Some General Themes in Catalysis at LANL

    SciTech Connect (OSTI)

    Gordon, John C. [Los Alamos National Laboratory

    2012-07-19T23:59:59.000Z

    Some general themes in catalysis at LANL are: (1) Storage and release of energy within chemical bonds (e.g. H{sub 2} storage in and release from covalent bonds, N{sub 2} functionalization, CO{sub 2} functionalization, H{sub 2} oxidation/evolution, O{sub 2} reduction/evolution); (2) Can we control the chemistry of reactive substrates to effect energy relevant transformations in non-traditional media (e.g. can we promote C-C couplings, dehydrations, or hydrogenations in water under relatively mild conditions)? (3) Can we supplant precious metal or rare earth catalysts to effect these transformations, by using earth abundant metals/elements instead? Can we use organocatalysis and circumvent the use of metals completely? (4) Can we improve upon existing rare earth catalyst systems (e.g. in rare earth oxides pertinent to fluid cracking or polymerization) and reduce amounts required for catalytic efficacy? Carbohydrates can be accessed from non-food based biomass sources such as woody residues and switchgrass. After extracted from the plant source, our goal is to upgrade these classes of molecules into useful fuels.

  20. E-Print Network 3.0 - alkane oxidation catalysis Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    hydrogen... Reforming of Methane 10 Gas Phase Incorporation of Pd onto Iron-Ceria Aerogels for Water Gas Shift Catalysis... at the 20 North American Meeting of the Catalysis...

  1. Applied Catalysis A: General 243 (2003) 1524 On the potential role of hydroxyl groups in

    E-Print Network [OSTI]

    Marks, Laurence D.

    2003-01-01T23:59:59.000Z

    Applied Catalysis A: General 243 (2003) 15­24 On the potential role of hydroxyl groups in CO.K. Costello et al. / Applied Catalysis A: General 243 (2003) 15­24 sensitivity may also account, in part

  2. Applied Catalysis A: General 392 (2011) 5768 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Auerbach, Scott M.

    2011-01-01T23:59:59.000Z

    Applied Catalysis A: General 392 (2011) 57­68 Contents lists available at ScienceDirect Applied Catalysis A: General journal homepage: www.elsevier.com/locate/apcata Liquid phase aldol condensation

  3. GTPase Catalysis by Ras and Other G-proteins: Insights from Substrate Directed SuperImposition

    E-Print Network [OSTI]

    Kosloff, Mickey

    GTPase Catalysis by Ras and Other G-proteins: Insights from Substrate Directed Super usage of similar approaches to comparison of enzyme catalytic machineries. We applied SDSI to various G catalysis; GTPase; guanine nucleotides; conformational rearrangement; structure comparison

  4. Applied Catalysis B: Environmental 105 (2011) 5060 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Frenkel, Anatoly

    2011-01-01T23:59:59.000Z

    Applied Catalysis B: Environmental 105 (2011) 50­60 Contents lists available at ScienceDirect Applied Catalysis B: Environmental journal homepage: www.elsevier.com/locate/apcatb Cobalt

  5. acid-base catalysis ii: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    corroborate asymmetry of catalysis in F0F1-ATP synthase. Zarrabi, Nawid; Diez, Manuel; Graeber, Peter; Wrachtrup, Joerg; Boersch, Michael 2007-01-01 232 Magnetic catalysis in hot...

  6. High contrast solid state electrochromic devices based on Ruthenium Purple nanocomposites fabricated by layer-by-layer assemblyw

    E-Print Network [OSTI]

    Heflin, Randy

    High contrast solid state electrochromic devices based on Ruthenium Purple nanocomposites: 10.1039/b803915a Electrochromic Ruthenium Purple­polymer nanocomposite films, fabricated by multilayer assembly, were found to exhibit sub-second switching speed and the highest electrochromic con

  7. Gold(I)-Mediated Nucleophilic Additions to Allenes: from Enantioselective Catalysis to Supramolecular Chemistry

    E-Print Network [OSTI]

    Wang, Zhan

    2012-01-01T23:59:59.000Z

    supramolecular catalysis where the capsule itself serves as a molecular reaction vessel, product can bind competitively with the starting material.

  8. ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai Ed., G.A.

    2007-01-01T23:59:59.000Z

    K. Lee Semiconductor Photocatalysis in Advanced Oxidationthermal) catalysis or photocatalysis on nanoporous supportswith Heterogeneous Photocatalysis using Nanostructured

  9. Development of carbon-metal oxide supercapacitors from sol-gel derived carbon-ruthenium xerogels

    SciTech Connect (OSTI)

    Lin, C.; Ritter, J.A.; Popov, B.N.

    1999-09-01T23:59:59.000Z

    There has been increasing interest in electrochemical capacitors as energy storage systems because of their high power density and long cycle life, compared to battery devices. According to the mechanism of energy storage, there are two types of electrochemical capacitors. One type is based on double layer (dl) formation due to charge separation, and the other type is based on a faradaic process due to redox reactions. Sol-gel derived high surface area carbon-ruthenium xerogels were prepared from carbonized resorcinol-formaldehyde resins containing an electrochemically active form of ruthenium oxide. The electrochemical capacitance of these materials increased with an increase in the ruthenium content indicating the presence of pseudocapacitance associated with the ruthenium oxide undergoing reversible faradaic redox reactions. A specific capacitance of 256 F/g (single electrode) was obtained from a carbon xerogel containing 14 wt% Ru, which corresponded to more than 50% utilization of the ruthenium. The double layer accounted for 40% of this capacitance. This material was also electrochemically stable, showing no change in a cyclic voltammogram for over 2,000 cycles.

  10. An efficient dimer method with preconditioning and linesearch

    E-Print Network [OSTI]

    Nicholas I. M. Gould

    2014-07-30T23:59:59.000Z

    Jul 30, 2014 ... An efficient dimer method with preconditioning and linesearch. Nicholas I. M. Gould (nick.gould ***at*** stfc.ac.uk) Christoph Ortner (C.Ortner ...

  11. Quantum Phase Transition in Dimerized Spin-1/2 Chains

    E-Print Network [OSTI]

    Aparajita Das; Sreeparna Bhadra; Sonali Saha

    2015-03-30T23:59:59.000Z

    Quantum phase transition in dimerized antiferromagnetic Heisenberg spin chain has been studied. A staircase structure in the variation of concurrence within strongly coupled pairs with that of external magnetic field has been observed indicating multiple critical points. Emergence of entanglement due to external magnetic field or magnetic entanglement is observed for weakly coupled spin pairs in the same dimer chain. Though closed dimerized isotropic XXX Heisenberg chains with different dimer strengths were mainly explored, analogous studies on open chains as well as closed anisotropic (XX interaction) chains with tilted external magnetic field have also been studied.

  12. Applied Catalysis A: General 391 (2011) 342349 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Goodman, Wayne

    2011-01-01T23:59:59.000Z

    Applied Catalysis A: General 391 (2011) 342­349 Contents lists available at ScienceDirect Applied Catalysis A: General journal homepage: www.elsevier.com/locate/apcata Preparation and characterization of Co in the last several decades due to their practical applications in many industrial areas such as catalysis

  13. Applied Catalysis B: Environmental 29 (2001) 327336 Gas-phase photo-oxidation of toluene using

    E-Print Network [OSTI]

    2001-01-01T23:59:59.000Z

    Applied Catalysis B: Environmental 29 (2001) 327­336 Gas-phase photo-oxidation of toluene using reserved. PII: S0926-3373(00)00211-3 #12;328 A.J. Maira et al. / Applied Catalysis B: Environmental 29.V. All rights reserved. Keywords: Photo-catalysis; Titanium dioxide; Nanoparticles; Volatile organic

  14. Applied Catalysis A: General 477 (2014) 102108 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Cao, Guozhong

    2014-01-01T23:59:59.000Z

    Applied Catalysis A: General 477 (2014) 102­108 Contents lists available at ScienceDirect Applied Catalysis A: General journal homepage: www.elsevier.com/locate/apcata Ordered mesoporous tungsten carbide, in particular, catalysis [21­24]. A key issue for improving this class of meso- porous structure

  15. Seventh BES (Basic Energy Sciences) catalysis and surface chemistry research conference

    SciTech Connect (OSTI)

    Not Available

    1990-03-01T23:59:59.000Z

    Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases. (CBS)

  16. Final technical report, Symposium on New Theoretical Concepts and Directions in Catalysis

    SciTech Connect (OSTI)

    Metiu, Horia [University of California, Santa Barbara

    2014-08-22T23:59:59.000Z

    We organized in August 2013 a “Symposium on New Theoretical Concepts and Directions in Catalysis” with the participation of 20 invited distinguished quantum chemists and other researchers who use computations to study catalysis. Symposium website; http://catalysis.cnsi.ucsb.edu/

  17. DOI: 10.1002/ijch.201100102 Single-Molecule Studies of HIV-1 Protease Catalysis

    E-Print Network [OSTI]

    Myong, Sua

    DOI: 10.1002/ijch.201100102 Single-Molecule Studies of HIV-1 Protease Catalysis Enabled by Chemical. Introduction Understanding the chemistry of enzyme catalysis has been an important objective of chemical of the chemistry occurring in the enzyme­substrate complex. The physical organic chemistry of enzyme catalysis

  18. Methane activation on ruthenium: the nature of the surface intermediates T.V. Choudhary and D.W. Goodman*

    E-Print Network [OSTI]

    Goodman, Wayne

    ,7]; following this step the syn-gas is con- verted to hydrocarbons directly via Fischer­Tropsch catalysis [8

  19. Porphyrin dimers as photosensitizers in photodynamic therapy

    SciTech Connect (OSTI)

    Pandey, R.K.; Smith, K.M.; Dougherty, T.J. (Oncologic Foundation of Buffalo, NY (USA))

    1990-07-01T23:59:59.000Z

    Porphyrin dimers 9 with either linkages and possible isomers bis(1-(6,7-bis(2-(methoxycarbonyl)ethyl)-1,3,5,8-tetramethyl-2- vinylporphin-4-yl)ethyl) ether (10) bis(1-(6,7-bis(2-(methoxycarbonyl)ethyl)-1,3,5,8-tetramethyl-4- vinylporphin-2-yl)ethyl) ether (11), and 1-(6,7-bis(2-(methoxycarbonyl)ethyl)-1,3,5,8-tetramethyl-2-vinylporph in- 4-yl)ethyl 1-(6,7-bis(2-(methoxycarbonyl)ethyl)-1,3,5,8-tetramethyl-4-vinylporph in- 2-yl)ethyl ether (12) were synthesized from the corresponding (1-hydroxyethyl)vinyldeuteroporphyrin IX dimethyl esters (Hvd). The pure Hvd isomers 2-(1-hydroxyethyl)-4-vinyldeuteroporphyrin IX dimethyl ester (7) and 4-(1-hydroxyethyl)-2-vinyldeuteroporphyrin IX dimethyl ester (8) were obtained from 2-acetyl-4-(1-hydroxyethyl) deuteroporphyrin IX dimethyl ester (3) and 4-acetyl-2-(1-hydroxyethyl)deuteroporphyrin IX dimethyl ester (4). Porphyrins 3 and 4 were prepared either by partial reduction of 2,4-diacetyldeuteroporphyrin IX dimethyl ester (2) or by oxidation of hematoporphyrin IX dimethyl ester (1) by using tetra-n-propylammonium perruthenate (Prn4N)(RuO4) with N-methylmorpholine N-oxide as an oxidizing agent. The in vivo photosensitizing ability and therapeutic ratios of dimers 9-12 were compared with that of Photofrin II in the SMT-F tumor growing subcutaneously in DBA/2 Ha mice. These dimers were found to have better tumoricidal activity than Photofrin II with reduced skin phototoxicity.

  20. Exhaust aftertreatment using plasma-assisted catalysis

    SciTech Connect (OSTI)

    Penetrante, B

    2000-01-20T23:59:59.000Z

    In the field of catalysis, one application that has been classified as a breakthrough technology is the catalytic reduction of NO{sub x} in oxygen-rich environments using hydrocarbons. This breakthrough will require dramatic improvements in both catalyst and engine technology, but the benefits will be substantial for energy efficiency and a cleaner environment. Engine and automobile companies are placing greater emphasis on the diesel engine because of its potential for saving fuel resources and reducing CO{sub 2} emissions. The modern direct-injection diesel engine offers demonstrated fuel economy advantages unmatched by any other commercially-viable engine. The main drawback of diesel engines is exhaust emissions. A modification of existing oxidation catalyst/engine technology is being used to address the CO, hydrocarbon and particulates. However, no satisfactory solution currently exists for NO{sub x}. Diesel engines operate under net oxidizing conditions, thus rendering conventional three-way catalytic converters ineffective for the controlling the NO{sub x} emission. NO{sub x} reduction catalysts, using ammonia as a reductant, do exist for oxygen-rich exhausts; however, for transportation applications, the use of on-board hydrocarbon fuels is a more feasible, cost-effective, and environmentally-sound approach. Selective catalytic reduction (SCR) by hydrocarbons is one of the leading catalytic aftertreatment technologies for the reduction of NO{sub x} in lean-burn engine exhaust (often referred to as lean-NO{sub x}). The objective is to chemically reduce the pollutant molecules of NO{sub x} to benign molecules such as N{sub 2}. Aftertreatment schemes have focused a great deal on the reduction of NO because the NO{sub x} in engine exhaust is composed primarily of NO. Recent studies, however, have shown that the oxidation of NO to NO{sub 2} serves an important role in enhancing the efficiency for reduction of NO{sub x} to N{sub 2}. It has become apparent that preconverting NO to NO{sub 2} could improve both the efficiency and durability of lean-NO{sub x} catalysts. A non-thermal plasma is an efficient means for selective partial oxidation of NO to NO{sub 2}. The use of a non-thermal plasma in combination with a lean-NO{sub x} catalyst opens the opportunity for catalysts that are more efficient and more durable compared to conventional catalysts. In the absence of hydrocarbons, the O radicals will oxidize NO to NO{sub 2}, and the OH radicals will further oxidize NO{sub 2} to nitric acid. In plasma-assisted catalysis it is important that the plasma oxidize NO to NO{sub 2} without further producing acids.

  1. Center for Catalysis at Iowa State University

    SciTech Connect (OSTI)

    Kraus, George A.

    2006-10-17T23:59:59.000Z

    The overall objective of this proposal is to enable Iowa State University to establish a Center that enjoys world-class stature and eventually enhances the economy through the transfer of innovation from the laboratory to the marketplace. The funds have been used to support experimental proposals from interdisciplinary research teams in areas related to catalysis and green chemistry. Specific focus areas included: • Catalytic conversion of renewable natural resources to industrial materials • Development of new catalysts for the oxidation or reduction of commodity chemicals • Use of enzymes and microorganisms in biocatalysis • Development of new, environmentally friendly reactions of industrial importance These focus areas intersect with barriers from the MYTP draft document. Specifically, section 2.4.3.1 Processing and Conversion has a list of bulleted items under Improved Chemical Conversions that includes new hydrogenation catalysts, milder oxidation catalysts, new catalysts for dehydration and selective bond cleavage catalysts. Specifically, the four sections are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D) All funded projects are part of a soybean or corn biorefinery. Two funded projects that have made significant progress toward goals of the MYTP draft document are: Catalysts to convert feedstocks with high fatty acid content to biodiesel (Kraus, Lin, Verkade) and Conversion of Glycerol into 1,3-Propanediol (Lin, Kraus). Currently, biodiesel is prepared using homogeneous base catalysis. However, as producers look for feedstocks other than soybean oil, such as waste restaurant oils and rendered animal fats, they have observed a large amount of free fatty acids contained in the feedstocks. Free fatty acids cannot be converted into biodiesel using homogeneous base-mediated processes. The CCAT catalyst system offers an integrated and cooperative catalytic system that performs both esterification (of free fatty acids) and transesterification (of soybean oil) in a one-pot fashion. This will allow the biodiesel producers to use the aforementioned cheap feedstocks without any pretreatment. In addition, the catalyst system is heterogeneous and is highly recyclable and reusable. Although markets currently exist for glycerin, concern is mounting that the price of glycerin may plummet to $.05 - $.10 per pound if future production exceeds demand. Developing a system to make high value chemicals such as 1,3-propanediol from the glycerin stream will add value for biodiesel producers who implement the new technology. Given the fact that both DuPont and Shell chemicals have announced the commercialization of two new PDO-based polymers, a rapid increase of market demand for a cheaper PDO source is very likely. 4. Comparison of actual accomplishments with goals and objectives From our progress reports, the four areas are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D)

  2. High-Spin Cobalt Hydrides for Catalysis

    SciTech Connect (OSTI)

    Holland, Patrick L. [Yale University] [Yale University

    2013-08-29T23:59:59.000Z

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  3. Catalysis-by-design impacts assessment

    SciTech Connect (OSTI)

    Fassbender, L L; Young, J K [Pacific Northwest Lab., Richland, WA (USA); Sen, R K [Sen (R.K.) and Associates, Washington, DC (USA)

    1991-05-01T23:59:59.000Z

    Catalyst researchers have always recognized the need to develop a detailed understanding of the mechanisms of catalytic processes, and have hoped that it would lead to developing a theoretical predictive base to guide the search for new catalysts. This understanding allows one to develop a set of hierarchical models, from fundamental atomic-level ab-initio models to detailed engineering simulations of reactor systems, to direct the search for optimized, efficient catalyst systems. During the last two decades, the explosions of advanced surface analysis techniques have helped considerably to develop the building blocks for understanding various catalytic reactions. An effort to couple these theoretical and experimental advances to develop a set of hierarchical models to predict the nature of catalytic materials is a program entitled Catalysis-by-Design (CRD).'' In assessing the potential impacts of CBD on US industry, the key point to remember is that the value of the program lies in developing a novel methodology to search for new catalyst systems. Industrial researchers can then use this methodology to develop proprietary catalysts. Most companies involved in catalyst R D have two types of ongoing projects. The first type, what we call market-driven R D,'' are projects that support and improve upon a company's existing product lines. Project of the second type, technology-driven R D,'' are longer term, involve the development of totally new catalysts, and are initiated through scientists' research ideas. The CBD approach will impact both types of projects. However, this analysis indicates that the near-term impacts will be on market-driven'' projects. The conclusions and recommendations presented in this report were obtained by the authors through personal interviews with individuals involved in a variety of industrial catalyst development programs and through the three CBD workshops held in the summer of 1989. 34 refs., 7 figs., 7 tabs.

  4. Coordination of dibensothiophenes and corannulenes to organometallic ruthenium (II) fragments

    SciTech Connect (OSTI)

    Vecchi, Paul Anthony

    2005-05-01T23:59:59.000Z

    This dissertation contains five papers in the format required for journal publication which describe (in part) my research accomplishments as a graduate student at Iowa State University. This work can be broadly categorized as the binding of weakly-coordinating ligands to cationic organometallic ruthenium fragments, and consists of two main areas of study. Chapters 2-4 are investigations into factors that influence the binding of dibenzothiophenes to {l_brace}Cp'Ru(CO){sub 2}{r_brace}{sup +} fragments, where Cp' = {eta}{sup 5}-C{sub 5}H{sub 5} (Cp) and {eta}{sup 5}-C{sub 5}Me{sub 5} (Cp*). Chapters 5 and 6 present the synthesis and structural characterization of complexes containing corannulene buckybowls that are {eta}{sup 6}-coordinated to {l_brace}Cp*Ru{r_brace}{sup +} fragments. The first chapter contains a brief description of the difficulty in lowering sulfur levels in diesel fuel along with a review of corannulene derivatives and their metal complexes. After the final paper is a short summary of the work herein (Chapter 7). Each chapter is independent, and all equations, schemes, figures, tables, references, and appendices in this dissertation pertain only to the chapter in which they appear.

  5. Enantioselective Alkenylation of Aldehydes with Boronic Acids via the Synergistic Combination of Copper(II) and Amine Catalysis

    E-Print Network [OSTI]

    MacMillan, David W. C.

    recently applied the synergistic catalysis paradigm to the development of several new asymmetric bond of Copper(II) and Amine Catalysis Jason M. Stevens and David W. C. MacMillan* Merck Center for Catalysis combination of copper and chiral amine catalysis. The merger of two highly utilized and robust catalytic

  6. Allylation of acetanilides with allyl acetate under conditions of metal-complex catalysis combined with phase-transfer catalysis

    SciTech Connect (OSTI)

    Lebedev, S.A.; Leonova, Yu.P.; Berestova, S.S.; Petrov, E.S.

    1988-10-20T23:59:59.000Z

    Acetanilides are alkylated at the nitrogen atom under the conditions of phase-transfer catalysis. For the case of the reaction of acetanilides with allyl acetate the authors showed that 2-alkenyl esters can be used for the alkylation of acetanilides under the conditions of phase-transfer catalysis in the presence of the complexes of zero valent palladium. N-Acetylskatole was obtained with a yield of 50% from N-allyl-2-bromoacetanilide by intramolecular cyclization in the presence of Od(OAc)/sub 2/ as catalyst.

  7. Anthraquinone-Imide-Based Dimers: Synthesis, Piezochromism, Liquid Crystalline,

    E-Print Network [OSTI]

    Wan, Xin-hua

    Anthraquinone-Imide-Based Dimers: Synthesis, Piezochromism, Liquid Crystalline, and Near-mail: xhwan@pku.edu.cn A series of anthraquinone-imide-based dimers, C5Ã? -AQI-Si2, C5Ã? -AQI-Si3, C5Ã? -AQI-Si4- oxy)phenyl)anthraquinone-2,3-dicarboxylic imide and hydride-terminated siloxanes with different

  8. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    in internal combustion engines and power plants. Copper-exchanged promising as selective catalytic reduction ) are a major atmospheric pollutant produced through the combustion of fossil fuels in internal combustionFrontiers in Catalysis Science and Engineering Seminar Series Small Pore Zeolites: Effective

  9. Homogeneous Catalysis Selective Oxidation of Methane to Methanol

    E-Print Network [OSTI]

    Goddard III, William A.

    Homogeneous Catalysis Selective Oxidation of Methane to Methanol Catalyzed, with CÀH Activation (generated by dissolution[6] of Au2O3) react with methane at 1808C to selectively generate methanol (as a mixture of the ester and methanol) in high yield (Table 1, entries 1 and 2). As expected, the irreversible

  10. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    Frontiers in Catalysis Science and Engineering Seminar Series On the role of hydrogen of Chemical & Biological Engineering ·University of Wisconsin - Madison Abstract Hydrogen is a frequent principles governing the role of hydrogen in a wide range of catalytic transformations begin to emerge

  11. Overview of surface science and catalysis by Qifei Wu

    E-Print Network [OSTI]

    of hydrodesulfurization catalysis Crude oil contains S-impurity (R-S; environmental hazard) H2 + R-S RH + H2S catalyst P. Hydrodesulfurization (HDS) on metcar nanoparticles C4H4S(g) +3H2(g) C4H8(g) +H2S(g) According to our DFT calculations

  12. Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis

    E-Print Network [OSTI]

    Collum, David B.

    Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis Lekha Gupta, 2008 Ortholithiations of a range of arenes mediated by lithium diisopropylamide (LDA) in THF at -78 °C protocols with unpurified commercial samples of n-butyl- lithium to prepare LDA or commercially available

  13. JOURNAL OF CATALYSIS 177, 343351 (1998) ARTICLE NO. CA982143

    E-Print Network [OSTI]

    Iglesia, Enrique

    1998-01-01T23:59:59.000Z

    - modynamically favorable at high temperatures, but often leads to high yields of coke and smaller hydrocarbons, but it requires a selective catalyst in order to avoid complete oxidation to CO and CO2. A number of recentJOURNAL OF CATALYSIS 177, 343­351 (1998) ARTICLE NO. CA982143 Structure and Properties of Vanadium

  14. Corrosion behavior of a high-chromium duplex stainless steel with minor additions of ruthenium in sulfuric acid

    SciTech Connect (OSTI)

    Potgieter, J.H. [Pretoria Portland Cement, Johannesburg (South Africa). Technical Services Dept.; Brookes, H.C. [Univ. of Natal, Durban (South Africa). Dept. of Chemistry

    1995-04-01T23:59:59.000Z

    The influence of small ruthenium additions on the corrosion behavior of high-chromium duplex stainless steels (DSS) was studied. Ruthenium additions ({le} 0.28%) increased the corrosion resistance of the base alloy by simultaneously improving hydrogen evolution efficiency and inhibiting anodic dissolution. The corrosion behavior of the high-chromium DSS with small ruthenium additions differed somewhat from behavior of similar duplex alloys of the 22%-Cr type. The lowering of hydrogen overpotential, which promotes an elevated corrosion potential leading to passivity, was much more significant in the 29%-Cr duplex alloys than in the 22%-Cr types.

  15. Investigation of ruthenium dioxide formation mechanisms in containment glass synthesized by liquid feed

    SciTech Connect (OSTI)

    Sawada, K.; Shimada, T.; Sako, N.; Enokida, Y. [Graduate School of Engineering, Nagoya University (Japan); Schuller, S.; Angeli, F. [CEA-DEN-DTCD-LCV-SECM, 30207 Bagnols-sur-Ceze (France); Charpentier, T. [CEA-Saclay, DSM-IRAMIS-SIS2M, 91191 Gif-sur-Yvette (France)

    2013-07-01T23:59:59.000Z

    The presenting paper focuses on the structural configuration of ruthenium in vitreous matrices with the objective of obtaining more insight into ruthenium incorporation and solubilization mechanisms in borosilicate glasses. To determine the structural effect of an increasing RuO{sub 2} in a borosilicate glass, a series of glass samples were selected from a benchmark composition. {sup 11}B NMR shows that the borate network is influenced by the presence of RuO{sub 2} in the glass: the addition of 2% RuO{sub 2} in a borosilicate glass led to a significant rise of BO{sub 4}. RuO{sub 2} precipitated in the glass does not seem to be the cause of this modification because when RuO{sub 2} increase there is no further change of BO{sub 4} fraction. This effect can be therefore attributed to RuO{sub 2} dissolved in the glass. RuO{sub 2} is known to have a very low solubility in borosilicate glasses (50 to 2000 ppm depending on the temperature, sodium concentration and conditions of synthesis). The link between the ruthenium and the borated network is not yet clearly identified, however, assumptions can be made such as the formation of Ru-O-B when a sufficient quantity of Ru is add (> 400 ppm). Ruthenium could play the role of silicon in increasing the possibility of bridging bond formation with boron coordination number IV.

  16. Method for producing electricity using a platinum-ruthenium-palladium catalyst in a fuel cell

    DOE Patents [OSTI]

    Gorer, Alexander

    2004-01-27T23:59:59.000Z

    A method for producing electricity using a fuel cell that utilizes a ternary alloy composition as a fuel cell catalyst, the ternary alloy composition containing platinum, ruthenium and palladium. The alloy shows increased activity as compared to well-known catalysts.

  17. Adsorption of Ruthenium and Iron Metallocenes on Silica: A Solid-State NMR Study

    E-Print Network [OSTI]

    Bluemel, Janet

    Adsorption of Ruthenium and Iron Metallocenes on Silica: A Solid- State NMR Study Kyle J. Cluff on silica surfaces by grinding the polycrystalline materials with silica. The adsorption process proceeds dry silica surface, wet and TMS- capped silica have been used as supports. The adsorption leads

  18. The Reactivity Limit for Methanol Oxidation on Platinum/Ruthenium Catalysts

    E-Print Network [OSTI]

    The Reactivity Limit for Methanol Oxidation on Platinum/Ruthenium Catalysts A. Wieckowski 0.5 1.0 1.5 2.0 2.5 3.0 Pt/Ru Decorated (UIUC) PtRu Alloy (JM) E = 0.4 V Oxidation in 0.5 M Methanol

  19. Near-Infrared Electrochromic and Electroluminescent Polymers Containing Pendant Ruthenium Complex Groups

    E-Print Network [OSTI]

    Wan, Xin-hua

    Near-Infrared Electrochromic and Electroluminescent Polymers Containing Pendant Ruthenium ComplexVised Manuscript ReceiVed August 30, 2006 ABSTRACT: A series of near-infrared (NIR) electrochromic. All the polymers are near-infrared (NIR) electrochromic, displaying an intense absorption centered

  20. Characterization of hydrous ruthenium oxide/carbon nanocomposite supercapacitors prepared by a colloidal method

    E-Print Network [OSTI]

    Popov, Branko N.

    , the recent research has focused on devel- oping structures of RuO2/carbon composite materials. Miller 20 July 2001 Abstract Amorphous nanostructured composite materials with different RuO2 loadings converted to ruthenium oxide after annealing at 100 8C. The speci®c capacitance of RuO2/carbon composite

  1. Electrodeposited ruthenium oxide thin films for supercapacitor: Effect of surface treatments

    E-Print Network [OSTI]

    Chow, Lee

    Electrodeposited ruthenium oxide thin films for supercapacitor: Effect of surface treatments V Supercapacitor is similar to a regular capacitor in operation; however, it offers a very high capacitance for supercapacitor should be able to get oxidized and reduce reversibility between various oxidation states [1

  2. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    SciTech Connect (OSTI)

    Hartwig, J.F.

    1990-12-01T23:59:59.000Z

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

  3. Adsorption of silver dimer on graphene - A DFT study

    SciTech Connect (OSTI)

    Kaur, Gagandeep, E-mail: gaganj1981@yahoo.com [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and Chandigarh Engineering College, Landran, Mohali-140307, Punjab (India); Gupta, Shuchi [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and University Institute of Engineering and Technology, Panjab University, Chandigarh -160014 (India); Rani, Pooja; Dharamvir, Keya [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014 (India)

    2014-04-24T23:59:59.000Z

    We performed a systematic density functional theory (DFT) study of the adsorption of silver dimer (Ag{sub 2}) on graphene using SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Ag2-graphene system are calculated. The minimum energy configuration for a silver dimer is parallel to the graphene sheet with its two atoms directly above the centre of carbon-carbon bond. The negligible charge transfer between the dimer and the surface is also indicative of a weak bond. The methodology demonstrated in this paper may be applied to larger silver clusters on graphene sheet.

  4. Molecular-Level Design of Heterogeneous Chiral Catalysis

    SciTech Connect (OSTI)

    Francisco Zaera

    2012-03-21T23:59:59.000Z

    The following is a proposal to continue our multi-institutional research on heterogeneous chiral catalysis. Our team combines the use of surface-sensitive analytical techniques for the characterization of model systems with quantum and statistical mechanical calculations to interpret experimental data and guide the design of future research. Our investigation focuses on the interrelation among the three main mechanisms by which enantioselectivity can be bestowed to heterogeneous catalysts, namely: (1) by templating chirality via the adsorption of chiral supramolecular assemblies, (2) by using chiral modifiers capable of forming chiral complexes with the reactant and force enantioselective surface reactions, and (3) by forming naturally chiral surfaces using imprinting chiral agents. Individually, the members of our team are leaders in these various aspects of chiral catalysis, but the present program provides the vehicle to generate and exploit the synergies necessary to address the problem in a comprehensive manner. Our initial work has advanced the methodology needed for these studies, including an enantioselective titration procedure to identify surface chiral sites, infrared spectroscopy in situ at the interface between gases or liquids and solids to mimic realistic catalytic conditions, and DFT and Monte Carlo algorithms to simulate and understand chirality on surfaces. The next step, to be funded by the monies requested in this proposal, is to apply those methods to specific problems in chiral catalysis, including the identification of the requirements for the formation of supramolecular surface structures with enantioselective behavior, the search for better molecules to probe the chiral nature of the modified surfaces, the exploration of the transition from supramolecular to one-to-one chiral modification, the correlation of the adsorption characteristics of one-to-one chiral modifiers with their physical properties, in particular with their configuration, and the development of ways to imprint chiral centers on achiral solid surfaces. Chiral catalysis is not only a problem of great importance in its own right, but also the ultimate test of how to control selectivity in catalysis. The time is ripe for fundamental work in heterogeneous chiral catalysis to provide the U.S. with a leadership role in developing the next generation of catalytic processes for medicinal and agrochemical manufacturing. Our team provides the required expertise for a synergistic and comprehensive integration of physical and chemical experimentation with solid state and molecular reactivity theories to solve this problem.

  5. Palladium- and Ruthenium-Catalyzed Decarboxylative Allylations and Michael Addition-Allylation Reactions. Applications in Nitrogen Heterocycle Synthesis

    E-Print Network [OSTI]

    Wang, Chao

    2008-08-21T23:59:59.000Z

    Our group has a long-standing interest in Pd or Ru-catalyzed decarboxylative coupling reactions. It has been shown that allyl ?-ketoesters, upon treatment with palladium or ruthenium, generate freely diffusing enolates and ...

  6. Selective catalytic reduction system and process for treating NOx emissions using a palladium and rhodium or ruthenium catalyst

    SciTech Connect (OSTI)

    Sobolevskiy, Anatoly (Orlando, FL); Rossin, Joseph A. (Columbus, OH); Knapke, Michael J. (Columbus, OH)

    2011-07-12T23:59:59.000Z

    A process for the catalytic reduction of nitrogen oxides (NOx) in a gas stream (29) in the presence of H.sub.2 is provided. The process comprises contacting the gas stream with a catalyst system (38) comprising zirconia-silica washcoat particles (41), a pre-sulfated zirconia binder (44), and a catalyst combination (40) comprising palladium and at least one of rhodium, ruthenium, or a mixture of ruthenium and rhodium.

  7. A structural investigation of the chemokine dimer interface

    E-Print Network [OSTI]

    Hayes, Garret Lance

    2013-02-22T23:59:59.000Z

    , the ability of scientists to predict structure is much less tangible and underlines thc need for even more inquiries into the fundamental properties that lead to protein folding (Heringa, 2000). The search for an all-cncompassing structural viewpoint.... Conveniently then, the study of dimerization is one satisfying method to investigate protein folding. By studying the processes and interactions that lead to dimerization, a firmer grasp of the generic rubric that governs protein folding can be realized...

  8. Selective catalysis utilizing bifunctionalized MCM-41 mesoporous materials

    SciTech Connect (OSTI)

    Strosahl, Kasey Jean

    2005-05-01T23:59:59.000Z

    Selective catalysis is a field that has been under intense investigation for the last 100 years. The most widely used method involves catalysts with stereochemical selectivity. In this type of catalysis, the catalyst controls which reactants will be transformed into the desired product. The secret to employing this type of catalysis, though, is to design the proper catalyst, which can be difficult. One may spend as much time developing the catalyst as spent separating the various products achieved. Another method of selective catalysis is now being explored. The method involves utilizing a multifunctional mesoporous silica catalyst with a gate-keeping capability. Properly functionalized mesoporous materials with well-defined pore morphology and surface properties can provide an ideal three-dimensional environment for anchoring various homogeneous catalysts. These materials can circumvent the multi-sited two-dimensional nature most heterogeneous systems have without adversely impacting the reactant diffusivity. These single-site nanostructured catalysts with ordered geometrical structure are advantageous in achieving high selectivity and reactivity. Mesoporous materials can be prepared to include pores lined homogeneously with tethered catalysts via co-condensation. Additionally, these materials can be reacted with another (RO){sub 3}Si{approx}Z group by using the traditional grafting method; this group is anchored predominantly at the entrances to the pores rather than inside the pores. Thus, if these {approx}Z groups are chosen properly, they can select certain molecules to enter the pores and be converted to products (Scheme 1). In such multifunctional catalysts, the selectivity depends on the discrimination of the gatekeeper. Gate-keeping MCM-41 materials are at the forefront of catalytic substances.

  9. Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    2002deeraardahl.pdf More Documents & Publications Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated Lean NOx Catalysis Selective reduction of NOx in...

  10. Support for U.S. Participants at the 15th International Congress on Catalysis

    SciTech Connect (OSTI)

    Wachs, Israel E.

    2013-08-05T23:59:59.000Z

    The grant was used to partially assist the travel expenses of U.S. academic scientists to attend the 15th International Congress on Catalysis. The conference was held in Munich, Germany from July 1-6, 2012. The importance of the International Congress was to bring together the international community of faculty members who participate in catalysis research, and to share information that would lead to further developments and directions in the field of study. Graduate students and Post Docs were invited to apply for travel assistance based on criteria established by the North American Catalysis Society (NACS) and the local Catalysis Clubs.

  11. Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions...

    Broader source: Energy.gov (indexed) [DOE]

    Lean NOx Catalysis l Chemistry l Reducing Agent Effects l Collaboration with LEP CRADA l Aging Studies Plasma Initiation - + Electron Avalanche e - e - e - e - e - e - e -...

  12. Experimental Investigation of the Kinetics of a Ruthenium-Catalyzed Deconstruction of Lignin Model Compounds

    SciTech Connect (OSTI)

    Bu, L.; Nimlos, M. R.; Shirts, M. R.; Himmel, M. E.; Crowley, M. F.; Beckham, G. T.

    2012-01-01T23:59:59.000Z

    Lignin is a major component of plant cell walls that is typically underutilized in selective conversion strategies for renewable fuels and chemicals. The mechanisms by which thermal and catalytic treatments deconstruct lignin remain elusive. In this work, we have investigated the kinetics of the catalytic deconstruction of lignin model compounds using a ruthenium catalyst reported by Bergman et al. in 2010. A series of investigations using NMR spectroscopy and GC/MS will be presented. In addition, we propose detailed mechanisms for lignin depolymerization with ruthenium catalysts. We have also used DFT to compute transition state geometries of catalytic cycle intermediates and compare the values determined computationally with those observed experimentally. Ultimately, our objective is to apply our methods to the design of new homogeneous and heterogeneous catalysts for the effective deconstruction and valorization of lignin.

  13. Complex of transferrin with ruthenium for medical applications. [Ru 97, Ru 103

    DOE Patents [OSTI]

    Richards, P.; Srivastava, S.C.; Meinken, G.E.

    1980-11-03T23:59:59.000Z

    A novel Ruthenium-transferrin complex, prepared by reacting iron-free human transferrin dissolved in a sodium acetate solution at pH 7 with ruthenium by heating at about 40/sup 0/C for about 2 hours, and purifying said complex by means of gel chromatography with pH 7 sodium acetate as eluent. The mono- or di-metal complex produced can be used in nuclear medicine in the diagnosis and/or treatment of tumors and abscesses. Comparitive results with Ga-67-citrate, which is the most widely used tumor-localizing agent in nuclear medicine, indicate increased sensitivity of detection and greater tumor uptake with the Ru-transferrin complex.

  14. Applied Catalysis A: General 232 (2002) 219235 An EXAFS study of the co-ordination chemistry of hydrogen

    E-Print Network [OSTI]

    Regalbuto, John R.

    2002-01-01T23:59:59.000Z

    Applied Catalysis A: General 232 (2002) 219­235 An EXAFS study of the co-ordination chemistry)00116-3 #12;220 W.A. Spieker et al. / Applied Catalysis A: General 232 (2002) 219­235 dissociation

  15. The research at the department of Biochemistry is focused on enzyme catalysis, applied enzymology and ecological plant biochemistry. There are two main activities within enzyme catalysis, one towards synthesis

    E-Print Network [OSTI]

    Lagergren, Jens

    The research at the department of Biochemistry is focused on enzyme catalysis, applied enzymology and ecological plant biochemistry. There are two main activities within enzyme catalysis, one towards synthesis of enzyme catalysis based on a broad interdisciplinary competence in enzymology, molecular biology, organic

  16. Removal of Toluene in Air by Non Thermal Plasma-Catalysis Hybrid , H. T. Pham

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Removal of Toluene in Air by Non Thermal Plasma-Catalysis Hybrid System A. Khacef , H. T. Pham , A Orléans Cedex 02, France * Institute of Applied Material Science, VAST, 1 Mac Dinh Chi, HCMC, Vietnam with heterogeneous catalysts. This combination can be either single-stage (in-plasma catalysis, IPC) or two

  17. Probing the chemistry of thioredoxin catalysis Arun P. Wiita1,2

    E-Print Network [OSTI]

    Fernandez, Julio M.

    LETTERS Probing the chemistry of thioredoxin catalysis with force Arun P. Wiita1,2 , Raul Perez organisms1 . Although catalysis is thought to proceed through a substitution nucleophilic bimolecular (SN2 (Trx). We applied mechanical force in the range of 25­600 pN to a disulphide bond substrate

  18. Advanced Synthesis & Catalysis Terminal alkyne metathesis: a further step towards selectivity.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Advanced Synthesis & Catalysis Terminal alkyne metathesis: a further step towards selectivity 320436585 E-mail: andre.mortreux@ensc-lille.fr , Received alkyne / metathesis / catalysis / carbyne,[2] the latter giving rise to much more active catalysts, allowing the reaction to be applied

  19. Amine a-heteroarylation via photoredox catalysis: a homolytic aromatic substitution pathway

    E-Print Network [OSTI]

    MacMillan, David W. C.

    Amine a-heteroarylation via photoredox catalysis: a homolytic aromatic substitution pathway accomplished via photoredox catalysis to generate valuable benzylic amine pharmacophores. A variety of five substitution (SNAr)3 or transi- tion metal-catalyzed approaches,4 have been extensively studied and applied

  20. Applied Catalysis A: General 226 (2002) 183192 NO reduction by urea under lean conditions

    E-Print Network [OSTI]

    Gulari, Erdogan

    2002-01-01T23:59:59.000Z

    Applied Catalysis A: General 226 (2002) 183­192 NO reduction by urea under lean conditions over.V. All rights reserved. PII: S0926-860X(01)00901-2 #12;184 E. Seker et al. / Applied Catalysis A: General

  1. Journal of Catalysis 260 (2008) 342350 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Regalbuto, John R.

    2008-01-01T23:59:59.000Z

    Journal of Catalysis 260 (2008) 342­350 Contents lists available at ScienceDirect Journal of Catalysis www.elsevier.com/locate/jcat The synthesis of highly dispersed noble and base metals on silica via The catalyst synthesis method of strong electrostatic adsorption (SEA) was applied to mesoporous silica SBA-15

  2. Journal of Catalysis 260 (2008) 329341 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    Regalbuto, John R.

    2008-01-01T23:59:59.000Z

    Journal of Catalysis 260 (2008) 329­341 Contents lists available at ScienceDirect Journal of Catalysis www.elsevier.com/locate/jcat The synthesis of highly dispersed noble and base metals on silica via and after reduction. The results showed that the SEA method can be applied for many ammine complexes

  3. Z .Journal of Molecular Catalysis A: Chemical 153 2000 155163 www.elsevier.comrlocatermolcata

    E-Print Network [OSTI]

    Truong, Thanh N.

    Z .Journal of Molecular Catalysis A: Chemical 153 2000 155­163 www and Applied Chemistry, Chemistry Department, Faculty of Science, Kasetsart UniÕersity, Bangkok 10900, Thailand. q 2000 Elsevier Science B.V. All rights reserved. 1. Introduction Zeolite catalysis is of prime

  4. Bifunctional Lewis Acid-Nucleophile-Based Asymmetric Catalysis: Mechanistic Evidence for Imine Activation Working

    E-Print Network [OSTI]

    Lectka, Thomas

    Bifunctional Lewis Acid-Nucleophile-Based Asymmetric Catalysis: Mechanistic Evidence for Imine that substantial progress has been made in the use of well- defined bifunctional systems as applied to asymmetric catalysis.4 Several of these systems combine a metal ion (usually as part of a chiral Lewis acid complex

  5. Tandem Catalysis A Highly Efficient and Rapid Approach to Synthetic Elaboration

    E-Print Network [OSTI]

    Stoltz, Brian M.

    diiodide catalyzed Mukaiyama Michael-aldol reactions C.) Zirconium catalyzed synthesis of !-cyanohydrins D and rhodium catalyzed annulation. B.) Cobalt catalyzed annulation and cycloaddition C.) Rapid synthesis of pyrroles and furans D.) Organocatalytic / Lewis acid tandem catalysis 5.) Conclusions Tandem catalysis

  6. Single-molecule enzymology of RNA: Essential functional groups impact catalysis from a distance

    E-Print Network [OSTI]

    Walter, Nils G.

    Single-molecule enzymology of RNA: Essential functional groups impact catalysis from a distance the site of catalysis have on the individual rate constants. We find that all ribozyme variants show rate constants. This leads to heterogeneous cleavage activity as com- monly observed for RNA enzymes

  7. Physica A 249 (1998) 558564 Mutual catalysis in sets of prebiotic

    E-Print Network [OSTI]

    Pilpel, Yitzhak

    1998-01-01T23:59:59.000Z

    Physica A 249 (1998) 558­564 Mutual catalysis in sets of prebiotic organic molecules : Evolution on the origin of life needs to delineate a chemically rigorous, self-consistent path from highly heterogeneous Replication Domain (GARD) model for explicit kinetic analysis of mutual catalysis in sets of random oligomers

  8. Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis

    SciTech Connect (OSTI)

    Thorn, David [Los Alamos National Laboratory

    2012-06-13T23:59:59.000Z

    Making or breaking C-H, B-H, C-C bonds has been at the core of catalysis for many years. Making or breaking these bonds to store or recover energy presents us with fresh challenges, including how to catalyze these transformations in molecular systems that are 'tuned' to minimize energy loss and in molecular and material systems present in biomass. This talk will discuss some challenging transformations in chemical hydrogen storage, and some aspects of the inorganic chemistry we are studying in the development of catalysts for biomass utilization.

  9. Catalysis Science | U.S. DOE Office of Science (SC)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced. C o w l i t z C o . C lKieling ,Catalysis Science Chemical

  10. Theoretical Study on Catalysis by Protein Enzymes and Ribozyme

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin Transition in theTheoretical Study on Catalysis by Protein Enzymes

  11. Catalysis Working Group Meeting: June 2014 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof Energy Change RequestFirstchampions, checklists,CaseyCatalysis Working

  12. Catalysis Working Group Meeting: May 2013 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof Energy Change RequestFirstchampions, checklists,CaseyCatalysis

  13. Catalysis by Design - Theoretical and Experimental Studies of Model

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny: Theof Energy Change RequestFirstchampions, checklists,CaseyCatalysisCatalysts

  14. Catalysis | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurTheBrookhaven National Laboratory Laboratory Policy (LP) LPCMSNFScienceCatalysis

  15. Optofluidic taming of a colloidal dimer with a silicon nanocavity

    SciTech Connect (OSTI)

    Pin, C.; Renaut, C. [Groupe d'Optique de Champ Proche - LRC CEA n°DSM-08-36, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS n°6303- Université de Bourgogne, Dijon (France); University Grenoble Alpes, INAC-SP2M-SINAPS, F-38000 Grenoble, France and CEA, INAC-SP2M-SINAPS, F-38000 Grenoble (France); University Grenoble Alpes, CNRS, CEA-Leti Minatec, LTM, F-38054 Grenoble Cedex (France); Cluzel, B., E-mail: benoit.cluzel@u-bourgogne.fr; Fornel, F. de [Groupe d'Optique de Champ Proche - LRC CEA n°DSM-08-36, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS n°6303- Université de Bourgogne, Dijon (France); Peyrade, D. [University Grenoble Alpes, CNRS, CEA-Leti Minatec, LTM, F-38054 Grenoble Cedex (France); Picard, E.; Hadji, E. [University Grenoble Alpes, INAC-SP2M-SINAPS, F-38000 Grenoble, France and CEA, INAC-SP2M-SINAPS, F-38000 Grenoble (France)

    2014-10-27T23:59:59.000Z

    We report here the optical trapping of a heterogeneous colloidal dimer above a photonic crystal nanocavity used as an on-chip optical tweezer. The trapped dimer consists of a cluster of two dielectric microbeads of different sizes linked by van der Waals forces. The smallest bead, 1??m in diameter, is observed to be preferentially trapped by the nanotweezer, leaving the second bead untrapped. The rotational nature of the trapped dimer Brownian motion is first evidenced. Then, in the presence of a fluid flow, control of its orientation and rotation is achieved. The whole system is found to show high rotational degrees of freedom, thereby acting as an effective flow-sensitive microscopic optical ball joint.

  16. Transition Metal Dimer Internuclear Distances from Measured Force Constants Joseph L. Jules and John R. Lombardi*

    E-Print Network [OSTI]

    Lombardi, John R.

    Transition Metal Dimer Internuclear Distances from Measured Force Constants Joseph L. Jules distances, have been extended to the transition metal dimers to test which one gives the most accurate fit's and Guggenheimer's for the transition metal dimers. Although Pauling's rule gives the best results, the remarkable

  17. Click Dimers To Target HIV TAR RNA Conformation Sunil Kumar,

    E-Print Network [OSTI]

    Stuart, Steven J.

    with high affinity toward TAR show promising anti-HIV activity. Ribonucleic acid-protein interactionsClick Dimers To Target HIV TAR RNA Conformation Sunil Kumar, Patrick Kellish, W. Edward Robinson and length in the linker region to target the human immunode- ficiency virus type 1 (HIV-1) TAR RNA region

  18. Spontaneous generation of local CP violation and inverse magnetic catalysis

    E-Print Network [OSTI]

    Lang Yu; Hao Liu; Mei Huang

    2014-09-14T23:59:59.000Z

    In the chiral symmetric phase, the polarized instanton--anti-instanton molecule pairing induces a nontrivial repulsive interaction in the iso-scalar axial-vector channel. As a consequence, one unusual property is observed that in the chiral restoration phase, there is a first order phase transition for the spontaneous generation of local CP violation and chiral imbalance. Furthermore, it is found that external magnetic fields will lower the critical temperature for the local CP-odd phase transition and catalyze the chiral imbalance, which destroys the chiral condensate with pairing quarks between different chiralities. A reasonable strength of the repulsive interaction in the iso-scalar axial-vector channel can naturally explain the inverse magnetic catalysis around the critical temperature under external magnetic fields.

  19. Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis

    SciTech Connect (OSTI)

    Cutler, A. R.

    2001-04-14T23:59:59.000Z

    Manganese carbonyl complexes serve as hydrosilation precatalysts for selectively transforming a carbonyl group into a siloxy methylene or a fully reduced methylene group. Substrates of interest include (1) aldehydes, ketones, carboxylic acids, silyl esters, and esters, and (2) their organometallic acyl counterparts. Three relevant catalytic reactions are shown. Two types of manganese precatalysts have been reported: (a) alkyl and acyl complexes (L)(C0){sub 4}MnR [L = CO, PPh{sub 3}; R = COCH{sub 3}, COPh, CH{sub 3}] and (b) halides (CO){sub 5}MnX and [(CO){sub 4}MnX]{sub 2} (X = Br, I). The former promote hydrosilation and deoxygenation catalysis; the latter promote dehydrogenative silation of alcohols and carboxylic acids as well as hydrosilation and deoxygenation of some metallocarboxylic acid derivatives. In every case studied, these Mn precatalysts are far more reactive or selective than traditional Rh(I) precatalysts.

  20. Studies toward biomimetic claisen condensation using nucleic acid templates and ribozyme catalysis

    E-Print Network [OSTI]

    Ryu, Youngha

    2005-08-29T23:59:59.000Z

    Many different experimental approaches were attempted to achieve carbon-carbon bond formation by nucleic acid template-directed reactions and ribozyme catalysis as potential lipid synthesizing machineries in the RNA world. A novel biomimetic...

  1. Two-Stage Plasma-Catalysis for Diesel NOx Emission Control. ...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    producing nitrogen. Citation: Hoard J, and RG Tonkyn.2003."Two-Stage Plasma-Catalysis for Diesel NOx Emission Control."Journal of Advanced Oxidation Technologies 6(2):158-165....

  2. Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial

    E-Print Network [OSTI]

    Boyer, Edmond

    Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial ainsi que des exemples d'applications industrielles. Abstract -- Transformation of Sorbitol to Biofuels and biodiesel production led to first generation biofuels. Nowadays, research is focused on lignocellulosic

  3. Molecular computations for reactions and phase transitions: applications to protein stabilization, hydrates and catalysis

    E-Print Network [OSTI]

    Anderson, Brian J.

    In this work we have made significant contributions in three different areas of interest: therapeutic protein stabilization, thermodynamics of natural gas clathrate-hydrates, and zeolite catalysis. In all three fields, ...

  4. Dendrimer-encapsulated metal nanoparticles: synthesis, characterization, and applications to catalysis 

    E-Print Network [OSTI]

    Niu, Yanhui

    2004-09-30T23:59:59.000Z

    The research in this dissertation examines the chemistry and applications of dendrimers in homogeneous catalysis. We examined interactions between dendrimers and charged probe molecules, prepared dendrimer-encapsulated metal nanoparticles...

  5. Analytical modeling of the interaction of enzyme catalysis and diffusion processes at the intracellular level

    E-Print Network [OSTI]

    Faith, Duane Willbern

    1977-01-01T23:59:59.000Z

    ANALYTICAL MODELING OF THE INTERACTION OF ENZYME CATALYSIS AND DIFFUSION PROCESSES AT THE INTRACELLULAR LEVEL A Thesis by Duane Nillbern Faith Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE May 1977 Major Subject: Bioengineering ANALYTICAL MODELING OF THE INTERACTION OF ENZYME CATALYSIS AND DIFFUSION PROCESSES AT THE INTRACELLULAR LEVEL A Thesis by Duane Willbern Faith Approved as to style and content by...

  6. Studies of the relationship of protein structure to regulation and catalysis in tyrosine hydroxylase

    E-Print Network [OSTI]

    Sura, Giri Raju

    2007-09-17T23:59:59.000Z

    STUDIES OF THE RELATIONSHIP OF PROTEIN STRUCTURE TO REGULATION AND CATALYSIS IN TYROSINE HYDROXYLASE A Dissertation by GIRI RAJU SURA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of DOCTOR OF PHILOSOPHY May 2006 Major Subject: Biochemistry STUDIES OF THE RELATIONSHIP OF PROTEIN STRUCTURE TO REGULATION AND CATALYSIS IN TYROSINE HYDROXYLASE A Dissertation by GIRI RAJU...

  7. Final Report on Kokes Awards for the 20th North American Catalysis Society Meeting

    SciTech Connect (OSTI)

    Wong, Michael S

    2008-12-31T23:59:59.000Z

    This Final Report describes how the Kokes Awards program was carried out for the 2007 meeting with regard to selection of students and disbursement of funds received from DOE and other sources. The objective of the Richard J. Kokes Travel Award program of the American Catalysis Society is to encourage graduate students to attend and participate meaningfully in the biennial North American Catalysis Society Meeting.

  8. UV resonance Raman analysis of trishomocubane and diamondoid dimers

    SciTech Connect (OSTI)

    Meinke, Reinhard, E-mail: rene@physik.tu-berlin.de; Thomsen, Christian; Maultzsch, Janina [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany)] [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Richter, Robert; Merli, Andrea [Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany)] [Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Fokin, Andrey A. [Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany) [Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany); Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev (Ukraine); Koso, Tetyana V.; Schreiner, Peter R. [Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany)] [Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany); Rodionov, Vladimir N. [Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev (Ukraine)] [Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev (Ukraine)

    2014-01-21T23:59:59.000Z

    We present resonance Raman measurements of crystalline trishomocubane and diamantane dimers containing a C=C double bond. Raman spectra were recorded with excitation energies between 2.33 eV and 5.42 eV. The strongest enhancement is observed for the C=C stretch vibration and a bending mode involving the two carbon atoms of the C=C bond, corresponding to the B{sub 2g} wagging mode of ethylene. This is associated with the localization of the ?-HOMO and LUMO and the elongation of the C=C bond length and a pyramidalization of the two sp{sup 2}-hybridized carbon atoms at the optical excitation. The observed Raman resonance energies of the trishomocubane and diamantane dimers are significantly lower than the HOMO-LUMO gaps of the corresponding unmodified diamondoids.

  9. Binding Energies in Benzene Dimers: Nonlocal Density Functional Calculations

    E-Print Network [OSTI]

    Aaron Puzder; Maxime Dion; David C. Langreth

    2005-09-15T23:59:59.000Z

    The interaction energy and minimum energy structure for different geometries of the benzene dimer has been calculated using the recently developed nonlocal correlation energy functional for calculating dispersion interactions. The comparison of this straightforward and relatively quick density functional based method with recent calculations can elucidate how the former, quicker method might be exploited in larger more complicated biological, organic, aromatic, and even infinite systems such as molecules physisorbed on surfaces, and van der Waals crystals.

  10. On the structure of the Nx phase of symmetric dimers

    E-Print Network [OSTI]

    Anke Hoffmann; Alexandros G. Vanakaras; Alexandra Kohlmeier; Georg H. Mehl; Demetri J. Photinos

    2014-07-07T23:59:59.000Z

    NMR measurements on a selectively deuteriated liquid crystal dimer CB-C9-CB exhibiting two nematic phases show that the molecules in the lower temperature nematic phase, Nx, experience a chiral environment and are ordered about a unique direction. The results are contrasted with previous reports that proposed a twist-bend spatial variation of the director. A structural model is proposed wherein the molecules show organization into highly correlated assemblies of opposite chirality.

  11. Benchmark calculations for elastic fermion-dimer scattering

    E-Print Network [OSTI]

    Shahin Bour; H. -W. Hammer; Dean Lee; Ulf-G. Meißner

    2012-06-08T23:59:59.000Z

    We present continuum and lattice calculations for elastic scattering between a fermion and a bound dimer in the shallow binding limit. For the continuum calculation we use the Skorniakov-Ter-Martirosian (STM) integral equation to determine the scattering length and effective range parameter to high precision. For the lattice calculation we use the finite-volume method of L\\"uscher. We take into account topological finite-volume corrections to the dimer binding energy which depend on the momentum of the dimer. After subtracting these effects, we find from the lattice calculation kappa a_fd = 1.174(9) and kappa r_fd = -0.029(13). These results agree well with the continuum values kappa a_fd = 1.17907(1) and kappa r_fd = -0.0383(3) obtained from the STM equation. We discuss applications to cold atomic Fermi gases, deuteron-neutron scattering in the spin-quartet channel, and lattice calculations of scattering for nuclei and hadronic molecules at finite volume.

  12. Exploring ruthenium dye synthesis and TiO2-dye-I-/I3- electron transfer reactions in a dye-sensitised solar cell. 

    E-Print Network [OSTI]

    Chadwick, Nina

    2013-11-28T23:59:59.000Z

    Octahedral, six co-ordinate ruthenium complexes containing acid substituted polypyridyl ligands have proved particularly successful as dyes for Dye-Sensitised Solar Cells (DSSCs); thus there have been hundreds, if not ...

  13. Calculation of the Dimer Equilibrium Constant of Heavy Water Saturated Vapor

    E-Print Network [OSTI]

    L. A. Bulavin; S. V. Khrapatiy; V. N. Makhlaichuk

    2015-03-13T23:59:59.000Z

    Water is the most common substance on Earth.The discovery of heavy water and its further study have shown that the change of hydrogen for deuterium leads to the significant differences in their properties.The triple point temperature of heavy water is higher,at the same time the critical temperature is lower.Experimental values of the second virial coefficient of the EOS for the vapor of normal and heavy water differ at all temperatures.This fact can influence the values of the dimerization constant for the heavy water vapor.The equilibrium properties of the dimerization process are described with the methods of chemical thermodynamics.The chemical potentials for monomers (m) and dimers (d)are the functions of their concentrations.The interactions of monomer-dimer and dimer-dimer types are taken into account within the solution of equation for chemical potentials.The obtained expression for the dimerization constant contains the contributions of these types.The averaged potentials are modeled by the Sutherland potential.Theoretical values of the dimerization constant for the heavy water vapor at different temperatures are compared to those for normal water.We see the exceeding of the values for the heavy water at all temperatures.This fact is in good agreement with all experimental data that is available.The excess is related to the differences in the character of the heat excitations of the dimers of normal and heavy water,their rotational constants and energy of their vibrational excitations.Significant role is also played by the monomer-dimer and dimer-dimer interactions.

  14. Structure-based redesign of the dimerization interface reduces the toxicity of zinc-finger nucleases

    E-Print Network [OSTI]

    Szczepek, Michal; Brondani, Vincent; Büchel, Janine; Serrano, Luis; Segal, David J; Cathomen, Toni

    2007-01-01T23:59:59.000Z

    energy with respect to the combination of two wild-typewild-type configuration (top) and for the variants (bottom). (i) In silico computation of dimerization energy.

  15. Radiation-induced tetramer-to-dimer transition of Escherichia coli lactose repressor

    SciTech Connect (OSTI)

    Goffinont, S. [Centre de Biophysique Moleculaire, CNRS, rue C. Sadron, 45071 Orleans (France)] [Centre de Biophysique Moleculaire, CNRS, rue C. Sadron, 45071 Orleans (France); Davidkova, M. [Department of Radiation Dosimetry, Nuclear Physics Institute AS CR, Na Truhlarce 39/64, 18086, Prague 8 (Czech Republic)] [Department of Radiation Dosimetry, Nuclear Physics Institute AS CR, Na Truhlarce 39/64, 18086, Prague 8 (Czech Republic); Spotheim-Maurizot, M., E-mail: spotheim@cnrs-orleans.fr [Centre de Biophysique Moleculaire, CNRS, rue C. Sadron, 45071 Orleans (France)

    2009-08-21T23:59:59.000Z

    The wild type lactose repressor of Escherichia coli is a tetrameric protein formed by two identical dimers. They are associated via a C-terminal 4-helix bundle (called tetramerization domain) whose stability is ensured by the interaction of leucine zipper motifs. Upon in vitro {gamma}-irradiation the repressor losses its ability to bind the operator DNA sequence due to damage of its DNA-binding domains. Using an engineered dimeric repressor for comparison, we show here that irradiation induces also the change of repressor oligomerisation state from tetramer to dimer. The splitting of the tetramer into dimers can result from the oxidation of the leucine residues of the tetramerization domain.

  16. Applied Catalysis A: General 192 (2000) 227234 Hydrogen production via the direct cracking of methane over Ni/SiO2

    E-Print Network [OSTI]

    zur Loye, Hans-Conrad

    2000-01-01T23:59:59.000Z

    Applied Catalysis A: General 192 (2000) 227­234 Hydrogen production via the direct cracking al. / Applied Catalysis A: General 192 (2000) 227­234 to be the diffusion of carbon through the metal

  17. Journal of Catalysis 191, 4654 (2000) doi:10.1006/jcat.1999.2798, available online at http://www.idealibrary.com on

    E-Print Network [OSTI]

    Androulakis, Ioannis (Yannis)

    2000-01-01T23:59:59.000Z

    high-temperature processes based on heterogeneous catalysis may involve homogeneous gas-phase reactionsJournal of Catalysis 191, 46­54 (2000) doi:10.1006/jcat.1999.2798, available online at http

  18. Synthesis, structures and properties of new hybrid solids containing ruthenium complexes and polyoxometalates

    SciTech Connect (OSTI)

    Yan Bangbo, E-mail: bangbo.yan@wku.edu [Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101 (United States); Hodsdon, Samantha A.; Li Yanfen; Carmichael, Christopher N.; Cao Yan; Pan Weiping [Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101 (United States)

    2011-12-15T23:59:59.000Z

    Two new organic-inorganic hybrid solids containing Keggin ions and ruthenium complexes have been synthesized and characterized by FT-IR, UV-vis, luminescence, X-ray, and TG analysis. In KNa[Ru(bpy){sub 3}]{sub 2}[H{sub 2}W{sub 12}O{sub 40}]{center_dot}8H{sub 2}O (1), the [Ru(bpy){sub 3}]{sup 2+} (bpy=2,2 Prime -bipyridine) complex ions are located in between the infinite one-dimensional double-chains formed by adjacent Keggin anions [H{sub 2}W{sub 12}O{sub 40}]{sup 6-} linked through {l_brace}KO{sub 7}{r_brace} and {l_brace}NaO{sub 6}{r_brace} polyhedra, while in K{sub 6}[Ru(pzc){sub 3}]{sub 2}[SiW{sub 12}O{sub 40}] Bullet 12H{sub 2}O (2), the [Ru(pzc){sub 3}]{sup -} (pzc=pyrazine-2-carboxylate) complex anions are confined by layered networks of the [SiW{sub 12}O{sub 40}]{sup 4-} clusters connected by potassium ions. Both compounds exhibit three-dimensional frameworks through noncovalent interactions such as hydrogen bonds and anion Midline-Horizontal-Ellipsis {pi} interactions. Additionally, compound 1 shows strong luminescence at 604 nm in solid state at room temperature. - Graphical abstract: Two three-dimensional framework solids are constructed from polyoxoanions and ruthenium-organic complexes through noncovalent interactions. Highlights: Black-Right-Pointing-Triangle Ru complexes form hybrid solids with polyoxometalates. Black-Right-Pointing-Triangle Anion Midline-Horizontal-Ellipsis {pi} interaction between polyoxometalates and metal complexes was observed. Black-Right-Pointing-Triangle Noncovalent interactions play an important role in the assembly of solids. Black-Right-Pointing-Triangle The hybrid solid shows luminescence properties.

  19. Jamming probabilities for a vacancy in the dimer model

    E-Print Network [OSTI]

    V. S. Poghosyan; V. B. Priezzhev; P. Ruelle

    2008-01-28T23:59:59.000Z

    Following the recent proposal made by Bouttier et al [Phys. Rev. E 76, 041140 (2007)], we study analytically the mobility properties of a single vacancy in the close-packed dimer model on the square lattice. Using the spanning web representation, we find determinantal expressions for various observable quantities. In the limiting case of large lattices, they can be reduced to the calculation of Toeplitz determinants and minors thereof. The probability for the vacancy to be strictly jammed and other diffusion characteristics are computed exactly.

  20. Simulations on the effects of confinement and Ni-catalysis on the formation of tubular fullerene structures from peapod precursors

    E-Print Network [OSTI]

    Goddard III, William A.

    Simulations on the effects of confinement and Ni-catalysis on the formation of tubular fullerene April 2007 We applied the recently developed reactive force field ReaxFF to study the dynamics buckyballs. This barrier is lowered by 40% with the aid of Ni-catalysis. This research can help the community

  1. Asymmetric Catalysis on Sequentially-Linked Columns Ahmed M. Hafez, Andrew E. Taggi, Travis Dudding, and Thomas Lectka*

    E-Print Network [OSTI]

    Lectka, Thomas

    Asymmetric Catalysis on Sequentially-Linked Columns Ahmed M. Hafez, Andrew E. Taggi, Travis Dudding of a series of "reaction columns". This process was applied to the catalytic asymmetric synthesis of -lactams that they conduct chemical reactions. In regard to chiral synthesis and drug discovery, asymmetric catalysis1

  2. Catalysis of Protein Disulfide Bond Isomerization in a Homogeneous Substrate Elizabeth A. Kersteen,, Seth R. Barrows, and Ronald T. Raines*,,|

    E-Print Network [OSTI]

    Raines, Ronald T.

    Catalysis of Protein Disulfide Bond Isomerization in a Homogeneous Substrate Elizabeth A. Kersteen in these assays are, however, heterogeneous, which complicates mechanistic analyses. Here, we report the first use this continuous assay to analyze catalysis by wild-type human PDI and a variant in which the C

  3. Converting Homogeneous to Heterogeneous in Electrophilic Catalysis using Monodisperse Metal Nanoparticles

    SciTech Connect (OSTI)

    Witham, Cole A.; Huang, Wenyu; Tsung, Chia-Kuang; Kuhn, John N.; Somorjai, Gabor A.; Toste, F. Dean

    2009-10-15T23:59:59.000Z

    A continuing goal in catalysis is the transformation of processes from homogeneous to heterogeneous. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this conversion is supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl{sub 2}, and catalyze a range of {pi}-bond activation reactions previously only homogeneously catalyzed. Multiple experimental methods are utilized to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, our size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared to larger, polymer-capped analogues.

  4. Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications

    SciTech Connect (OSTI)

    Parks, II, James E [ORNL; Storey, John Morse [ORNL; Theiss, Timothy J [ORNL; Ponnusamy, Senthil [ORNL; Ferguson, Harley Douglas [ORNL; Williams, Aaron M [ORNL; Tassitano, James B [ORNL

    2007-09-01T23:59:59.000Z

    Distributed energy is an approach for meeting energy needs that has several advantages. Distributed energy improves energy security during natural disasters or terrorist actions, improves transmission grid reliability by reducing grid load, and enhances power quality through voltage support and reactive power. In addition, distributed energy can be efficient since transmission losses are minimized. One prime mover for distributed energy is the natural gas reciprocating engine generator set. Natural gas reciprocating engines are flexible and scalable solutions for many distributed energy needs. The engines can be run continuously or occasionally as peak demand requires, and their operation and maintenance is straightforward. Furthermore, system efficiencies can be maximized when natural gas reciprocating engines are combined with thermal energy recovery for cooling, heating, and power applications. Expansion of natural gas reciprocating engines for distributed energy is dependent on several factors, but two prominent factors are efficiency and emissions. Efficiencies must be high enough to enable low operating costs, and emissions must be low enough to permit significant operation hours, especially in non-attainment areas where emissions are stringently regulated. To address these issues the U.S. Department of Energy and the California Energy Commission launched research and development programs called Advanced Reciprocating Engine Systems (ARES) and Advanced Reciprocating Internal Combustion Engines (ARICE), respectively. Fuel efficiency and low emissions are two primary goals of these programs. The work presented here was funded by the ARES program and, thus, addresses the ARES 2010 goals of 50% thermal efficiency (fuel efficiency) and <0.1 g/bhp-hr emissions of oxides of nitrogen (NOx). A summary of the goals for the ARES program is given in Table 1-1. ARICE 2007 goals are 45% thermal efficiency and <0.015 g/bhp-hr NOx. Several approaches for improving the efficiency and emissions of natural gas reciprocating engines are being pursued. Approaches include: stoichiometric engine operation with exhaust gas recirculation and three-way catalysis, advanced combustion modes such as homogeneous charge compression ignition, and extension of the lean combustion limit with advanced ignition concepts and/or hydrogen mixing. The research presented here addresses the technical approach of combining efficient lean spark-ignited natural gas combustion with low emissions obtained from a lean NOx trap catalyst aftertreatment system. This approach can be applied to current lean engine technology or advanced lean engines that may result from related efforts in lean limit extension. Furthermore, the lean NOx trap technology has synergy with hydrogen-assisted lean limit extension since hydrogen is produced from natural gas during the lean NOx trap catalyst system process. The approach is also applicable to other lean engines such as diesel engines, natural gas turbines, and lean gasoline engines; other research activities have focused on those applications. Some commercialization of the technology has occurred for automotive applications (both diesel and lean gasoline engine vehicles) and natural gas turbines for stationary power. The research here specifically addresses barriers to commercialization of the technology for large lean natural gas reciprocating engines for stationary power. The report presented here is a comprehensive collection of research conducted by Oak Ridge National Laboratory (ORNL) on lean NOx trap catalysis for lean natural gas reciprocating engines. The research was performed in the Department of Energy's ARES program from 2003 to 2007 and covers several aspects of the technology. All studies were conducted at ORNL on a Cummins C8.3G+ natural gas engine chosen based on industry input to simulate large lean natural gas engines. Specific technical areas addressed by the research include: NOx reduction efficiency, partial oxidation and reforming chemistry, and the effects of sulfur poisons on the partial oxidation

  5. 2010 CATALYSIS GORDON RESEARCH CONFERENCE, JUNE 27 - JULY 2, 2010, NEW LONDON, NEW HAMPSHIRE

    SciTech Connect (OSTI)

    Abhaya Datye

    2010-07-02T23:59:59.000Z

    Catalysis is a key technology for improving the quality of life while simultaneously reducing the adverse impact of human activities on the environment. The discovery of new catalytic processes and the improvement of existing ones are also critically important for securing the nation's energy supply. The GRC on Catalysis is considered one the most prestigious conference for catalysis research, bringing together leading researchers from both academia, industry and national labs to discuss the latest, most exciting research in catalysis and the future directions for the field. The 2010 GRC on Catalysis will follow time-honored traditions and feature invited talks from the world's leading experts in the fundamentals and applications of catalytic science and technology. We plan to have increased participation from industry. The extended discussions in the company of outstanding thinkers will stimulate and foster new science. The conference will include talks in the following areas: Alternative feedstocks for chemicals and fuels, Imaging and spectroscopy, Design of novel catalysts, Catalyst preparation fundamentals, Molecular insights through theory, Surface Science, Catalyst stability and dynamics. In 2010, the Catalysis conference will move to a larger conference room with a new poster session area that will allow 40 posters per session. The dorm rooms provide single and double accommodations, free WiFi and the registration fee includes all meals and the famous lobster dinner on Thursday night. Afternoons are open to enjoy the New England ambiance with opportunities for hiking, sailing, golf and tennis to create an outstanding conference that will help you network with colleagues, and make long lasting connections.

  6. Ionization satellites of the ArHe dimer

    SciTech Connect (OSTI)

    Miteva, Tsveta; Klaiman, Shachar; Gokhberg, Kirill [Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany); Gromov, Evgeniy V., E-mail: Evgeniy.Gromov@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany); Laboratory of Quantum Chemistry, Computer Center, Irkutsk State University, K. Marks 1, 664003 Irkutsk (Russian Federation)

    2014-05-28T23:59:59.000Z

    Ionization satellites are key ingredients in the control of post ionization processes such as molecular dissociation and interatomic Coulombic decay. Here, using the high-level ab initio method of multi-reference configuration interaction up to triple excitations, we study the potential energy curves (PECs) of the ionization satellites of the ArHe dimer. With this model system, we demonstrate that the simple model used in alkaline earth metal and rare gas complexes to describe the satellites as a Rydberg electron moving on top of a dicationic core does not fully hold for the rare gas clusters. The more complex valence structure in the rare gas atom leads to the mixing of different electronic configurations of the dimer. This prevents one from assigning a single dicationic parent state to some of the ionization satellites. We further analyze the structure of the different PECs, demonstrating how the density of the Rydberg electron is reflected in the structure of the PEC wherever the simple model is applicable.

  7. Electrochemistry and photocurrents of the tris(bipyridine)ruthenium(II) and methyl viologen cations immobilized in carrageenan hydrogel. [tris(2,2'-bipyridine)ruthenium(II)

    SciTech Connect (OSTI)

    Rillema, D.P.; Edwards, A.K. (Univ., of North Carolina, Charlotte (United States)); Perine, S.C.; Crumbliss, A.L. (Duke Univ., Durham, NC (United States))

    1991-11-13T23:59:59.000Z

    A procedure for immobilization of both a photochromophore, tris(2,2{prime}-bipyridine)ruthenium(II) (Ru(bpy){sub 3}{sup 2+}), and a quencher, methyl viologen (MV{sup 2+}), within a carrageenan hydrogel matrix at an electrode surface is described. Ru(bpy){sub 3}{sup 2+} and MV{sup 2+} exhibited diffusion coefficients that ranged from 10{sup {minus} 7} to 10{sup {minus} 6} cm{sup 2}/s in the hydrogel, which represents an improvement over other immobilization matrices. Photolysis of the resulting hydrogel surface modified electrodes gave rise to a significant photocurrent which depended on the concentrations of Ru(bpy){sub 3}{sup 2+}, MV{sup 2+}, and triethanolamine and resulted in a maximum value of 12 {mu}A/cm{sup 2} after the hydrogel was cured with a solution containing 5 mM Ru(bpy){sub 3}{sup 2+} and 50 mM MV{sup 2+}. The photocurrent was the result of reoxidation of MV{sup +} at the electrode surface following reduction of MV{sup 2+} by photoexcited Ru(bpy){sub 3}{sup 2+}. The quenching rate constant of Ru(bpy){sub 3}{sup 2+} by MV{sup 2+} in the hydrogel was 4.2 {times} 10{sup 8} M{sup {minus}1} s{sup {minus}1}. The photocurrent action spectrum was consistent with Ru(bpy){sub 3}{sup 2+} acting as the photochromophore. Offsetting the potential of the hydrogel electrode verified the role of the MV{sup 2+}/{sup +} redox couple as the source of the current.

  8. Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

    SciTech Connect (OSTI)

    Sun, Jie, E-mail: jie.sun@chalmers.se; Lindvall, Niclas; Yurgens, August [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Nam, Youngwoo [Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Cole, Matthew T. [Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, CB3 0FA Cambridge (United Kingdom); Teo, Kenneth B. K. [AIXTRON Nanoinstruments Ltd., Swavesey, CB24 4FQ Cambridge (United Kingdom); Woo Park, Yung [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2014-04-14T23:59:59.000Z

    A model of the graphene growth mechanism of chemical vapor deposition on platinum is proposed and verified by experiments. Surface catalysis and carbon segregation occur, respectively, at high and low temperatures in the process, representing the so-called balance and segregation regimes. Catalysis leads to self-limiting formation of large area monolayer graphene, whereas segregation results in multilayers, which evidently “grow from below.” By controlling kinetic factors, dominantly monolayer graphene whose high quality has been confirmed by quantum Hall measurement can be deposited on platinum with hydrogen-rich environment, quench cooling, tiny but continuous methane flow and about 1000?°C growth temperature.

  9. Electron-nuclear correlations for photo-induced dynamics in molecular dimers

    E-Print Network [OSTI]

    January 2004; accepted 11 March 2004 Ultrafast photoinduced dynamics of electronic excitation in molecularElectron-nuclear correlations for photo-induced dynamics in molecular dimers Dmitri S. Kilin, Yuri dimers is drastically affected by the dynamic reorganization of inter- and intra- molecular nuclear

  10. Proton transfer in adsorbed water dimers Xiao Liang Hu, Jir i Klimes and Angelos Michaelides*

    E-Print Network [OSTI]

    Alavi, Ali

    Proton transfer in adsorbed water dimers Xiao Liang Hu, Jir i´ Klimes and Angelos Michaelides) reveal rapid proton transfer within clusters of just two water molecules. Facile dissociation and recombination of the molecules within the dimers along with a concerted surface-mediated exchange of protons

  11. Disulfide bond-mediated dimerization of HLA-G on the cell surface

    E-Print Network [OSTI]

    Strominger, Jack L.

    . Here, we demonstrate that HLA-G forms disulfide-linked dimers that are present on the cell surface. Immunoprecipitation of HLA-G from surface biotinylated transfec- tants using the anti- 2-microglobulin mAb BBM.1 linkage formed exclusively through this residue. A possible interaction between the HLA-G monomer or dimer

  12. Charge localization and JahnTeller distortions in the benzene dimer cation Piotr A. Pieniazek, Stephen E. Bradforth,a

    E-Print Network [OSTI]

    Krylov, Anna I.

    Charge localization and Jahn­Teller distortions in the benzene dimer cation Piotr A. Pieniazek August 2008 Jahn­Teller JT distortions and charge localization in the benzene dimer cation are analyzed.1063/1.2969107 I. INTRODUCTION The benzene dimer cation is an important model system for radiation

  13. 337th Catalysis Research Center (CRC) Colloquium Fluorine Industry in China

    E-Print Network [OSTI]

    Ishii, Hitoshi

    337th Catalysis Research Center (CRC) Colloquium Fluorine Industry in China Lu Long (Shanghai industries in China, the second largest economy in the world. In this presentation, fluorine industry in China and the potential business opportunity will be discussed briefly, including inorganic fluorides

  14. Enzyme-Like Catalysis of the Nazarov Cyclization by Supramolecular Encapsulation

    SciTech Connect (OSTI)

    Hastings, Courtney; Pluth, Michael; Bergman, Robert; Raymond, Kenneth

    2010-03-29T23:59:59.000Z

    A primary goal in the design and synthesis of molecular hosts has been the selective recognition and binding of a variety of guests using non-covalent interactions. Supramolecular catalysis, which is the application of such hosts towards catalysis, has much in common with many enzymatic reactions, chiefly the use of both spatially appropriate binding pockets and precisely oriented functional groups to recognize and activate specific substrate molecules. Although there are now many examples which demonstrate how selective encapsulation in a host cavity can enhance the reactivity of a bound guest, all have failed to reach the degree of increased reactivity typical of enzymes. We now report the catalysis of the Nazarov cyclization by a self-assembled coordination cage, a carbon-carbon bond-forming reaction which proceeds under mild, aqueous conditions. The acceleration in this system is over a million-fold, and represents the first example of supramolecular catalysis that achieves the level of rate enhancement comparable to that observed in several enzymes. We explain the unprecedented degree of rate increase as due to the combination of (a) preorganization of the encapsulated substrate molecule, (b) stabilization of the transition state of the cyclization by constrictive binding, and (c) increase in the basicity of the complexed alcohol functionality.

  15. Challenges for the application of quantum chemical calculations to problems in catalysis

    E-Print Network [OSTI]

    Bell, Alexis T.

    2004) A long-standing goal of researchers in the field of catalysis is to develop first-principles of a catalysed reaction occurring in a reactor given knowledge only of reactor configuration, catalyst accurate determinations of reactor performance given a set of rate parameters describing catalyst

  16. Enantioselective Organocatalytic Indole Alkylations. Design of a New and Highly Effective Chiral Amine for Iminium Catalysis

    E-Print Network [OSTI]

    MacMillan, David W. C.

    structural motifs of established value in medicinal chemistry or complex target synthesis. In this regard the capacity of iminium catalysis to mediate the enantioselective coupling of pyrroles and R, -unsaturated alde nucleophiles. Despite struc- tural similarities, it has long been established7 that the pyrrole -system

  17. Applied Catalysis A: General 254 (2003) 97106 Photoionization detection (PID) as a high throughput

    E-Print Network [OSTI]

    Senkan, Selim M.

    Applied Catalysis A: General 254 (2003) 97­106 Photoionization detection (PID) as a high throughput 2002 Abstract A versatile photoionization detection (PID) system has been developed to rapidly screen libraries of catalytic materials. The PID approach involves the use of an appropriately selected dc

  18. High surface area crystalline titanium dioxide: potential and limits in electrochemical energy storage and catalysis

    E-Print Network [OSTI]

    Pfeifer, Holger

    High surface area crystalline titanium dioxide: potential and limits in electrochemical energy-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz, Germany Abstract Titanium dioxide is one, as support in catalysis etc. Common synthesis methods of titanium dioxide typically require a high

  19. Argonne National Laboratory Chemical Engineering Division Water-gas shift catalysis

    E-Print Network [OSTI]

    Argonne National Laboratory Chemical Engineering Division Water-gas shift catalysis Sara Yu Choung Engineering Division Argonne National Laboratory Hydrogen, Fuel Cells, and Infrastructure Technologies 2003 Merit Review Berkeley, CA May 19-22, 2003 #12;Argonne National Laboratory Chemical Engineering Division

  20. Catalysis Today 77 (2002) 6578 CO-free fuel processing for fuel cell applications

    E-Print Network [OSTI]

    Goodman, Wayne

    2002-01-01T23:59:59.000Z

    Catalysis Today 77 (2002) 65­78 CO-free fuel processing for fuel cell applications T.V. Choudhary In view of the stringent CO intolerance of the state-of-the-art proton exchange membrane (PEM) fuel cells of hydrocarbons has been proposed for production of CO-free hydrogen for fuel cell applications. The decomposition

  1. Author's personal copy Catalysis of imido group hydrolysis in a maleimide conjugate

    E-Print Network [OSTI]

    Raines, Ronald T.

    Author's personal copy Catalysis of imido group hydrolysis in a maleimide conjugate Jeet Kaliaa, resulting in undesirable heterogeneity. Here, a chromophoric maleimide is used to demonstrate that both for molybdate and chromate, and provides a strategy for decreasing the heterogeneity of bioconjugates derived

  2. ISHHC XIII International Symposium on the Relations betweenHomogeneous and Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Somorjai (Ed.), G.A.

    2007-06-11T23:59:59.000Z

    The International Symposium on Relations between Homogeneous and Heterogeneous Catalysis (ISHHC) has a long and distinguished history. Since 1974, in Brussels, this event has been held in Lyon, France (1977), Groeningen, The Netherlands (1981); Asilomar, California (1983); Novosibirsk, Russia (1986); Pisa, Italy (1989); Tokyo, Japan (1992); Balatonfuered, Hungary (1995); Southampton, United Kingdom (1999); Lyon, France (2001); Evanston, Illinois (2001) and Florence, Italy (2005). The aim of this international conference in Berkeley is to bring together practitioners in the three fields of catalysis, heterogeneous, homogeneous and enzyme, which utilize mostly nanosize particles. Recent advances in instrumentation, synthesis and reaction studies permit the nanoscale characterization of the catalyst systems, often for the same reaction, under similar experimental conditions. It is hoped that this circumstance will permit the development of correlations of these three different fields of catalysis on the molecular level. To further this goal we aim to uncover and focus on common concepts that emerge from nanoscale studies of structures and dynamics of the three types of catalysts. Another area of focus that will be addressed is the impact on and correlation of nanosciences with catalysis. There is information on the electronic and atomic structures of nanoparticles and their dynamics that should have importance in catalyst design and catalytic activity and selectivity.

  3. Asymmetric Catalysis at the Mesoscale: Gold Nanoclusters Embedded in Chiral Self-Assembled Monolayer as Heterogeneous

    E-Print Network [OSTI]

    Asymmetric Catalysis at the Mesoscale: Gold Nanoclusters Embedded in Chiral Self of the catalytically active metallic sites and the surrounding chiral SAM for the formation of a mesoscale the catalytically active site from the nanoscale to the mesoscale, which implies a principle of operating systems

  4. Calculation of the Dimer Equilibrium Constant of Heavy Water Saturated Vapor

    E-Print Network [OSTI]

    Bulavin, L A; Makhlaichuk, V N

    2015-01-01T23:59:59.000Z

    Water is the most common substance on Earth.The discovery of heavy water and its further study have shown that the change of hydrogen for deuterium leads to the significant differences in their properties.The triple point temperature of heavy water is higher,at the same time the critical temperature is lower.Experimental values of the second virial coefficient of the EOS for the vapor of normal and heavy water differ at all temperatures.This fact can influence the values of the dimerization constant for the heavy water vapor.The equilibrium properties of the dimerization process are described with the methods of chemical thermodynamics.The chemical potentials for monomers (m) and dimers (d)are the functions of their concentrations.The interactions of monomer-dimer and dimer-dimer types are taken into account within the solution of equation for chemical potentials.The obtained expression for the dimerization constant contains the contributions of these types.The averaged potentials are modeled by the Sutherlan...

  5. Enhancing quantum entanglement and quantum teleportation for two-mode squeezed vacuum state by local quantum-optical catalysis

    E-Print Network [OSTI]

    Xue-xiang Xu

    2015-03-17T23:59:59.000Z

    I investigate how the entanglement properties of a two-mode squeezed vacuum state (TMSVS) can be enhanced by operating quantum-optical catalysis, proposed by Lovvky and Mlynek [Phys. Rev. Lett. 88, 250404 (2002)], on each mode. I show that the degree of entanglement, the Eistein-Podolsky-Rosen-type correlation, and the performance of quantum teleportation can be all enhanced for the output state when the appropriate quantum-optical catalysis is applied to a TMSVS. It is found that all the enhancements are happened in the small-squeezing and small-catalysis parameter regime.

  6. The pure rotational spectrum of ruthenium monocarbide, RuC, and relativistic ab initio predictions

    SciTech Connect (OSTI)

    Wang, Fang; Steimle, Timothy C.; Adam, Allan G. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States)] [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States); Cheng, Lan; Stanton, John F. [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)] [Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2013-11-07T23:59:59.000Z

    The J = 1 ? J = 0 and J = 2 ? J = 1 rotational transitions of ruthenium monocarbide, RuC, have been recorded using the separated field pump/probe microwave optical double resonance technique and analyzed to determine the fine and hyperfine parameters for the X{sup 1}?{sup +} state. The {sup 101}Ru(I = 5/2) electric quadrupole parameter, eq{sub 0}Q, and nuclear spin-rotation interaction parameter, C{sub I}{sup eff}, were determined to be 433.19(8) MHz and ?0.049(6) MHz, respectively. The equilibrium bond distance, r{sub e}, was determined to be 1.605485(2) Å. Hartree-Fock and coupled-cluster calculations were carried out for the properties of the X{sup 1}?{sup +} state. Electron-correlation effects are pronounced for all properties studied. It is shown that (a) the moderate scalar-relativistic contribution to eq{sub 0}Q is entirely due to the coupling between scalar-relativistic and electron-correlation effects, (b) the spin-free exact two-component theory in its one-electron variant offers a reliable and efficient treatment of scalar-relativistic effects, and (c) non-relativistic theory performs quite well for the prediction of C{sub I}{sup elec}, provided that electron correlation is treated accurately.

  7. Behavior of molybdenum nitrides as materials for electrochemical capacitors: Comparison with ruthenium oxide

    SciTech Connect (OSTI)

    Liu, T.C.; Pell, W.G.; Conway, B.E. [Univ. of Ottawa, Ontario (Canada). Dept. of Chemistry; Roberson, S.L. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering

    1998-06-01T23:59:59.000Z

    Ruthenium oxide (RuO{sub 2}), formed as a thin film on a Ru or Ti metal substrate, exhibits a large specific (cm{sup {minus}2}) and almost constant, electrochemical capacitance over a 1.35 V range in aqueous H{sub 2}SO{sub 4}. This behavior has led to its investigation and use as a material for fabrication of supercapacitor devices. However, its cost has encouraged search for other materials exhibiting similar behavior. Work reported in the present paper evaluates two nitrides of Mo, Mo{sub 2}N and MoN, as substitutes for RuO{sub 2}. It is shown that very similar capacitance behavior to that of RuO{sub 2} films arises, e.g., in cyclic voltammetry and dc charging curves; in the former, almost mirror-image anodic and cathodic current-response profiles, characteristic of a capacitor, arise. However, the nitride materials have a substantially smaller voltage operating range of only some 0.7 V due to electrochemical decomposition above ca. 0.7 V vs. RHE. This limits their usefulness as a substitute for RuO{sub 2}. Of interest is that the nitride films exhibit potential-decay and potential-recovery on open circuit after respective charge and forced discharge. The decay and recovery processes are logarithmic in time, indicating the role of internal faradaic charge redistribution processes.

  8. Hydrous ruthenium oxide nanoparticles anchored to graphene and carbon nanotube hybrid foam for supercapacitors

    SciTech Connect (OSTI)

    Wang, Wei [Univ. of California, Riverside, CA (United States); Guo, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lee, I. [Univ. of California, Riverside, CA (United States); Ahmed, K. [Univ. of California, Riverside, CA (United States); Zhong, J. [Univ. of California, Riverside, CA (United States); Favors, Z. [Univ. of California, Riverside, CA (United States); Zaera, F. [Univ. of California, Riverside, CA (United States); Ozkan, M. [Univ. of California, Riverside, CA (United States); Ozkan, C. S [Univ. of California, Riverside, CA (United States)

    2014-03-25T23:59:59.000Z

    In real life applications, supercapacitors (SCs) often can only be used as part of a hybrid system together with other high energy storage devices due to their relatively lower energy density in comparison to other types of energy storage devices such as batteries and fuel cells. Increasing the energy density of SCs will have a huge impact on the development of future energy storage devices by broadening the area of application for SCs. Here, we report a simple and scalable way of preparing a three-dimensional (3D) sub-5 nm hydrous ruthenium oxide (RuO?) anchored graphene and CNT hybrid foam (RGM) architecture for high-performance supercapacitor electrodes. This RGM architecture demonstrates a novel graphene foam conformally covered with hybrid networks of RuO? nanoparticles and anchored CNTs. SCs based on RGM show superior gravimetric and per-area capacitive performance (specific capacitance: 502.78 F g?¹, areal capacitance: 1.11 F cm?²) which leads to an exceptionally high energy density of 39.28 Wh kg?¹ and power density of 128.01 kW kg?¹. The electrochemical stability, excellent capacitive performance, and the ease of preparation suggest this RGM system is promising for future energy storage applications.

  9. Photoelectron spectroscopy of nickel group dimers: Ni:, PdF, and Ptc Joe Ho,`) Mark L. Polak,b) Kent M. Ervin,C) and W. C. Lineberger

    E-Print Network [OSTI]

    Lineberger, W. Carl

    Photoelectron spectroscopy of nickel group dimers: Ni:, PdF, and Ptc Joe Ho,`) Mark L. Polak are tentatively assigned.Comparison of the nickel group dimers to the coinage metal dimers shedslight on the d orbital contribution to the metal bonding in the nickel group dimers. I. INTRODUCTION Spectroscopicstudy

  10. The roles of redox active cofactors in catalysis : structural studies of iron sulfur cluster and flavin dependent enzymes

    E-Print Network [OSTI]

    Goldman, Peter John

    2013-01-01T23:59:59.000Z

    Cofactors are highly prevalent in biological systems and have evolved to take on many functions in enzyme catalysis. Two cofactors, flavin adenine dinucleotide (FAD) and [4Fe-4S] clusters, were originally determined to aid ...

  11. HOMOGENEOUS CATALYSIS AND MASS TRANSFER IN BIPHASIC IONIC LIQUID SYSTEMS WITH COMPRESSED CO2 AND ORGANIC COMPOUNDS

    E-Print Network [OSTI]

    Ahosseini, Azita

    ABSTRACT Homogeneous catalysis in which the catalyst, solvents and reactants are all in the same phase can yield high activity and selectivity and efficiently produce chemical products. However, the main problem with these ...

  12. On the ro-vibrational energies for the lithium dimer; maximum-possible rotational levels

    E-Print Network [OSTI]

    Omar Mustafa

    2015-03-02T23:59:59.000Z

    The Deng-Fan potential is used to discuss the reliability of the improved Greene-Aldrich approximation and the factorization recipe of Badawi et al.'s [17] for the central attractive/repulsive core. The factorization recipe is shown to be a more reliable approximation and is used to obtain the ro-vibrational energies for the lithium dimer. For each vibrational state only a limited number of the rotational levels are found to be supported by the lithium dimer.

  13. The oxidative dimerization of methane over promoted and unpromoted magnesium oxide monoliths

    E-Print Network [OSTI]

    Aigler, Jane Marie

    1989-01-01T23:59:59.000Z

    for the degree of MASTER OF SCIENCE May 1989 Major Subject: Chemistry THE OXIDATIVE DIMERIZATION OF METHANE OVER PROMOTED AND UNPROMOTED MAGNESIUM OxiDE MONOLITHS A Thesis by JANE MARIE AIGLER Approved as to style and content by: uns or (Chair of Commi... ee) os e (Member) nt ony (Member) a (Head of Department) May 1989 ABSTRACT The Oxidative Dimerization of Methane over Promoted and Unpromoted Magnesium Oxide Monoliths. (May 1989) Jane Marie Aigier, B. S. , Pennsylvania State University...

  14. Reaction and spectroscopic study of silica-supported molybdenum(IV) and tungsten(IV) dimers

    SciTech Connect (OSTI)

    Sullivan, D.L.; Roark, R.D.; Ekerdt, J.G. [Univ. of Texas, Austin, TX (United States); Deutsch, S.E.; Gates, B.C. [Univ. of California, Davis, CA (United States)

    1995-03-16T23:59:59.000Z

    Cyclopentadienyl molybdenum di- and tricarbonyl dimer and cyclopentadienyl tungsten di- and tricarbonyl dimer complexes were added to silica as precursors to supported metal dimers. These complexes are shown to yield metal dimers following attachment to the silica and carbonyl ligand removal. Reductive carbonyl coupling of acetaldehyde and acetone was used as a molecular probe to determine whether dimers formed, with each metal atom being in the 4+ oxidation state. Acetaldehyde and acetone reductively coupled to produce cis- and trans-2-butenes and 2,3-dimethyl-2-butene, respectively. Diolates formed as intermediate products during the coupling reaction. Infrared bands were observed at 2969, 2925, and 2859 cm-1 that correspond to {nu}{sub asym}(CH{sub 3}), {nu}(CH), and {nu}{sub sym}(CH{sub 3}), respectively, for the 2,3-butanediolate formed from acetaldehyde. The hydrogens on the methyl groups for the acetone reductive coupling intermediate, 2,3-dimethyl-2,3-butanediolate, were not equivalent, resulting in the appearance of three C-H stretching frequencies at 2977, 2939, and 2891 cm{sup {minus}1} that are assigned to A{prime}{sub asym}, A{prime}, A{prime}{sub sym} of CH{sub 3}, respectively. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to characterize a sample prepared from cyclopentadienyl tungsten dicarbonyl dimer on silica. 74 refs., 7 figs., 5 tabs.

  15. Role of Human DNA Polymerase kappa in Extension Opposite from a cis-syn Thymine Dimer

    SciTech Connect (OSTI)

    R Vasquez-Del Carpio; T Silverstein; S Lone; R Johnson; L Prakash; S Prakash; A Aggarwal

    2011-12-31T23:59:59.000Z

    Exposure of DNA to UV radiation causes covalent linkages between adjacent pyrimidines. The most common lesion found in DNA from these UV-induced linkages is the cis-syn cyclobutane pyrimidine dimer. Human DNA polymerase {Kappa} (Pol{Kappa}), a member of the Y-family of DNA polymerases, is unable to insert nucleotides opposite the 3'T of a cis-syn T-T dimer, but it can efficiently extend from a nucleotide inserted opposite the 3'T of the dimer by another DNA polymerase. We present here the structure of human Pol{Kappa} in the act of inserting a nucleotide opposite the 5'T of the cis-syn T-T dimer. The structure reveals a constrained active-site cleft that is unable to accommodate the 3'T of a cis-syn T-T dimer but is remarkably well adapted to accommodate the 5'T via Watson-Crick base pairing, in accord with a proposed role for Pol{Kappa} in the extension reaction opposite from cyclobutane pyrimidine dimers in vivo.

  16. Structure of a Rabbit Muscle Fructose-1,6-Bisphosphate Aldolase A Dimer Variant

    SciTech Connect (OSTI)

    Sherawat,M.; Tolan, D.; Allen, K.

    2008-01-01T23:59:59.000Z

    Fructose-1,6-bisphosphate aldolase (aldolase) is an essential enzyme in glycolysis and gluconeogenesis. In addition to this primary function, aldolase is also known to bind to a variety of other proteins, a property that may allow it to perform 'moonlighting' roles in the cell. Although monomeric and dimeric aldolases possess full catalytic activity, the enzyme occurs as an unusually stable tetramer, suggesting a possible link between the oligomeric state and these noncatalytic cellular roles. Here, the first high-resolution X-ray crystal structure of rabbit muscle D128V aldolase, a dimeric form of aldolase mimicking the clinically important D128G mutation in humans associated with hemolytic anemia, is presented. The structure of the dimer was determined to 1.7 Angstroms resolution with the product DHAP bound in the active site. The turnover of substrate to produce the product ligand demonstrates the retention of catalytic activity by the dimeric aldolase. The D128V mutation causes aldolase to lose intermolecular contacts with the neighboring subunit at one of the two interfaces of the tetramer. The tertiary structure of the dimer does not significantly differ from the structure of half of the tetramer. Analytical ultracentrifugation confirms the occurrence of the enzyme as a dimer in solution. The highly stable structure of aldolase with an independent active site is consistent with a model in which aldolase has evolved as a multimeric scaffold to perform other noncatalytic functions.

  17. Shear-response of the spectrin dimer-tetramer equilibrium in the red blood cell membrane

    SciTech Connect (OSTI)

    An, Xiuli; Lecomte, M. Christine; Chasis, Joel Anne; Mohandas, Narla; Gratzer, Walter

    2003-06-18T23:59:59.000Z

    The red cell membrane derives its elasticity and resistance to mechanical stresses from the membrane skeleton, a network composed of spectrin tetramers. These are formed by the head-to-head association of pairs of heterodimers attached at their ends to junctional complexes of several proteins. Here we examine the dynamics of the spectrin dimer-dimer association in the intact membrane. We show that univalent fragments of spectrin, containing the dimer self-association site, will bind to spectrin on the membrane and thereby disrupt the continuity of the protein network. This results in impairment of the mechanical stability of the membrane. When, moreover, the cells are subjected to a continuous low level of shear, even at room temperature, the incorporation of the fragments and the consequent destabilization of the membrane are greatly accentuated. It follows that a modest shearing force, well below that experienced by the red cell in the circulation, is sufficient to sever dimer-dimer links in the network. Our results imply (1) that the membrane accommodates the enormous distortions imposed on it during the passage of the cell through the micro vasculature by means of local dissociation of spectrin tetramers to dimers, (2) that the network in situ is in a dynamic state and under goes a ''breathing'' action of tetramer dissociation and re-formation.

  18. Rhodium mediated bond activation: from synthesis to catalysis

    SciTech Connect (OSTI)

    Ho, Hung-An

    2012-03-06T23:59:59.000Z

    Recently, our lab has developed monoanionic tridentate ligand, To{sup R}, showing the corresponding coordination chemistry and catalyst reactivity of magnesium, zirconium, zinc and iridium complexes. This thesis details synthetic chemistry, structural study and catalytic reactivity of the To{sup R}-supported rhodium compounds. Tl[To{sup R}] has been proved to be a superior ligand transfer agent for synthesizing rhodium complexes. The salt metathesis route of Tl[To{sup M}] with [Rh({mu}-Cl)(CO)]{sub 2} and [Rh({mu}- Cl)(COE)]{sub 2} gives To{sup M}Rh(CO){sub 2} (2.2) and To{sup M}RhH({eta}{sup 3}-C{sub 8}H{sub 13}) (3.1) respectively while Tl[To{sup P}] with [Rh({mu}-Cl)(CO)]{sub 2} affords To{sup P}Rh(CO){sub 2} (2.3). 2.2 reacts with both strong and weak electrophiles, resulting in the oxazoline N-attacked and the metal center-attacked compounds correspondingly. Using one of the metal center-attacked electrophiles, 2.3 was demonstrated to give high diastereoselectivity. Parallel to COE allylic C-H activation complex 3.1, the propene and allylbenzene allylic C-H activation products have also been synthesized. The subsequent functionalization attempts have been examined by treating with Brønsted acids, Lewis acids, electrophiles, nucleophiles, 1,3-dipolar reagents and reagents containing multiple bonds able to be inserted. Various related complexes have been obtained under these conditions, in which one of the azide insertion compounds reductively eliminates to give an allylic functionalization product stoichiometrically. 3.1 reacts with various primary alcohols to give the decarbonylation dihydride complex To{sup M}Rh(H){sub 2}CO (4.1). 4.1 shows catalytic reactivity for primary alcohol decarbonylation under a photolytic condition. Meanwhile, 2.2 has been found to be more reactive than 4.1 for catalytic alcohol decarbonylation under the same condition. Various complexes and primary alcohols have been investigated as well. The proposed mechanism is based on the stochiometric reactions of the possible metal and organic intermediates. Primary amines, hypothesized to undergo a similar reaction pathway, have been verified to give dehydrogenative coupling product, imines. In the end, the well-developed neutral tridentate Tpm coordinates to the rhodium bis(ethylene) dimer in the presence of TlPF{sub 6} to give the cationic complex, [TpmRh(C{sub 2}H{sub 4}){sub 2}][PF{sub 6}] (5.1). 5.1 serves as the first example of explicit determination of the solid state hapticity, evidenced by X-ray structure, among all the cationic Tpm{sup R}M(C{sub 2}H{sub 4}){sub 2}{sup +} (Tpm{sup R} = Tpm, Tpm*, M = Rh, Ir) derivatives. The substitution chemistry of this compound has been studied by treating with soft and hard donors. The trimethylphosphine-sbustituted complex activates molecular hydrogen to give the dihydride compound.

  19. Charge Transfer and Support Effects in Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Hervier, Antoine

    2011-12-21T23:59:59.000Z

    The kinetic, electronic and spectroscopic properties of two?dimensional oxide?supported catalysts were investigated in order to understand the role of charge transfer in catalysis. Pt/TiO{sub 2} nanodiodes were fabricated and used as catalysts for hydrogen oxidation. During the reaction, the current through the diode, as well as its I?V curve, were monitored, while gas chromatography was used to measure the reaction rate. The current and the turnover rate were found to have the same temperature dependence, indicating that hydrogen oxidation leads to the non?adiabatic excitation of electrons in Pt. A fraction of these electrons have enough energy to ballistically transport through Pt and overcome the Schottky barrier at the interface with TiO{sub 2}. The yield for this phenomenon is on the order of 10{sup ?4} electrons per product molecule formed, similar to what has been observed for CO oxidation and for the adsorption of many different molecules. The same Pt/TiO{sub 2} system was used to compare currents in hydrogen oxidation and deuterium oxidation. The current through the diode under deuterium oxidation was found to be greater than under hydrogen oxidation by a factor of three. Weighted by the difference in turnover frequencies for the two isotopes, this would imply a chemicurrent yield 5 times greater for D{sub 2} compared to H{sub 2}, contrary to what is expected given the higher mass of D{sub 2}. Reversible changes in the rectification factor of the diode are observed when switching between D{sub 2} and H{sub 2}. These changes are a likely cause for the differences in current between the two isotopes. In the nanodiode experiments, surface chemistry leads to charge flow, suggesting the possibility of creating charge flow to tune surface chemistry. This was done first by exposing a Pt/Si diode to visible light while using it as a catalyst for H{sub 2} oxidation. Absorption of the light in the Si, combined with the band bending at the interface, gives rise to a steady?state flow of hot holes to the surface. This leads to a decrease in turnover on the surface, an effect which is enhanced when a reverse bias is applied to the diode. Similar experiments were carried out for CO oxidation. On Pt/Si diodes, the reaction rate was found to increase when a forward bias was applied. When the diode was exposed to visible light and a reverse bias was applied, the rate was instead decreased. This implies that a flow of negative charges to the surface increases turnover, while positive charges decrease it. Charge flow in an oxide supported metal catalyst can be modified even without designing the catalyst as a solid state electronic device. This was done by doping stoichiometric and nonstoichiometric TiO{sub 2} films with F, and using the resulting oxides as supports for Pt films. In the case of stoichiometric TiO{sub 2}, F was found to act as an n?type dopant, creating a population of filled electronic states just below the conduction band, and dramatically increasing the conductivity of the oxide film. The electrons in those states can transfer to surface O, activating it for reaction with CO, and leading to increased turnover for CO oxidation. This reinforces the hypothesis that CO oxidation is activated by a flow of negative charges to the surface. The same set of catalysts was used for methanol oxidation. The electronic properties of the TiO{sub 2} films again correlated with the turnover rates, but also with selectivity. With stoichiometric TiO{sub 2} as the support, F?doping caused an increase in selectivity toward the formation of partial oxidation products, formaldehyde and methyl formate, versus the total oxidation product, CO{sub 2}. With non?stoichiometric TiO{sub 2}, F?doping had the reverse effect. Ambient Pressure X?Ray Photoelectron Spectroscopy was used to investigate this F?doping effect in reaction conditions. In O2 alone, and in CO oxidation conditions, the O1s spectrum showed a high binding energy peak that correlated in intensity with the activity of the different films: for stoichiomet

  20. On the role of interfacial hydrogen bonds in "on-water" catalysis

    E-Print Network [OSTI]

    Kristof Karhan; Rustam Z. Khaliullin; Thomas D. Kühne

    2014-08-21T23:59:59.000Z

    Numerous experiments have demonstrated that many classes of organic reactions exhibit increased reaction rates when performed in heterogeneous water emulsions. Despite enormous practical importance of the observed "on-water" catalytic effect and several mechanistic studies, its microscopic origins remains unclear. In this work, the second generation Car-Parrinello molecular dynamics method is extended to self-consistent charge density-functional based tight-binding in order to study "on-water" catalysis of the Diels-Alder reaction between dimethyl azodicarboxylate and quadricyclane. We find that the stabilization of the transition state by dangling hydrogen bonds exposed at the aqueous interfaces plays a significantly smaller role in "on-water" catalysis than has been suggested previously.

  1. Kokes Awards for the 22nd North American Catalysis Society Meeting, June 5-10, 2011

    SciTech Connect (OSTI)

    Fabio H. Ribeiro

    2011-06-05T23:59:59.000Z

    The biennial North American Catalysis Society (NACS) Meetings are the premiere conferences in the area of catalysis, surface science, and reaction engineering. The 22nd meeting will be held the week of June 5-10, 2011 in Detroit, Michigan. The objective of the Meetings is to bring together leading researchers for intensive scientific exchange and interactions. Financial support that offsets some of the associated costs (specifically, registration fee, airline tickets, and hotel accommodations) would encourage graduate students, and for the first time undergraduate students, to attend and participate meaningfully in this conference. The funds sought in this proposal will help support the Richard J. Kokes Travel Award program. Graduate students eligible for these merit-based Awards are those who study at a North American university and who will present at the Meeting. We have currently 209 applications and we expect to be able to fund about half of them. The NACS has traditionally sought to encourage graduate student, and this year for the first time undergraduate studies, participation at the National Meetings and providing financial support is the most effective means to do so. Their attendance would contribute significantly to their scientific training and communication and presentation skills. They would be exposed to the leading researchers from the US and abroad; they would meet their peers from other universities; they would learn about cutting-edge results that could benefit their research projects; and they may become interested in becoming active participants in the catalysis community. These young investigators represent the next generation of scientists and engineers, and their proper training will lead to future scientific breakthroughs and technological innovations that benefit the US economy. Advances in catalysis can come in the form of more energy-efficient and environmentally-friendly chemical processes, improved fuel cell performance, efficient hydrogen production, and a cleaner environment.

  2. Electrochemical DNA biosensor for detection of porcine oligonucleotides using ruthenium(II) complex as intercalator label redox

    SciTech Connect (OSTI)

    Halid, Nurul Izni Abdullah; Hasbullah, Siti Aishah; Heng, Lee Yook; Karim, Nurul Huda Abd [School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia); Ahmad, Haslina; Harun, Siti Norain [Chemistry Department, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang, Selangor (Malaysia)

    2014-09-03T23:59:59.000Z

    A DNA biosensor detection of oligonucleotides via the interactions of porcine DNA with redox active complex based on the electrochemical transduction is described. A ruthenium(II) complex, [Ru(bpy){sub 2}(PIP)]{sup 2+}, (bpy = 2,2?bipyridine, PIP = 2-phenylimidazo[4,5-f[[1,10-phenanthroline]) as DNA label has been synthesized and characterized by 1H NMR and mass spectra. The study was carried out by covalent bonding immobilization of porcine aminated DNA probes sequences on screen printed electrode (SPE) modified with succinimide-acrylic microspheres and [Ru(bpy){sub 2}(PIP)]{sup 2+} was used as electrochemical redox intercalator label to detect DNA hybridization event. Electrochemical detection was performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the potential range where the ruthenium (II) complex was active. The results indicate that the interaction of [Ru(bpy){sub 2}(PIP)]{sup 2+} with hybridization complementary DNA has higher response compared to single-stranded and mismatch complementary DNA.

  3. Structure of a rabbit muscle fructose-1, 6-bisphosphate aldolase A dimer variant

    SciTech Connect (OSTI)

    Sherawat, Manashi [Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2394 (United States); Tolan, Dean R., E-mail: tolan@bu.edu [Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215 (United States); Allen, Karen N., E-mail: tolan@bu.edu [Department of Physiology and Biophysics, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118-2394 (United States)

    2008-05-01T23:59:59.000Z

    The X-ray crystallographic structure of a dimer variant of fructose-1, 6-bisphosphate aldolase demonstrates a stable oligomer that mirrors half of the native tetramer. The presence of product demonstrates that this is an active form. Fructose-1, 6-bisphosphate aldolase (aldolase) is an essential enzyme in glycolysis and gluconeogenesis. In addition to this primary function, aldolase is also known to bind to a variety of other proteins, a property that may allow it to perform ‘moonlighting’ roles in the cell. Although monomeric and dimeric aldolases possess full catalytic activity, the enzyme occurs as an unusually stable tetramer, suggesting a possible link between the oligomeric state and these noncatalytic cellular roles. Here, the first high-resolution X-ray crystal structure of rabbit muscle D128V aldolase, a dimeric form of aldolase mimicking the clinically important D128G mutation in humans associated with hemolytic anemia, is presented. The structure of the dimer was determined to 1.7 Å resolution with the product DHAP bound in the active site. The turnover of substrate to produce the product ligand demonstrates the retention of catalytic activity by the dimeric aldolase. The D128V mutation causes aldolase to lose intermolecular contacts with the neighboring subunit at one of the two interfaces of the tetramer. The tertiary structure of the dimer does not significantly differ from the structure of half of the tetramer. Analytical ultracentrifugation confirms the occurrence of the enzyme as a dimer in solution. The highly stable structure of aldolase with an independent active site is consistent with a model in which aldolase has evolved as a multimeric scaffold to perform other noncatalytic functions.

  4. Structure of the dimerization domain of DiGeorge critical region 8

    SciTech Connect (OSTI)

    Senturia, R.; Faller, M.; Yin, S.; Loo, J.A.; Cascio, D.; Sawaya, M.R.; Hwang, D.; Clubb, R.T.; Guo, F. (UCLA)

    2010-09-27T23:59:59.000Z

    Maturation of microRNAs (miRNAs, {approx}22nt) from long primary transcripts [primary miRNAs (pri-miRNAs)] is regulated during development and is altered in diseases such as cancer. The first processing step is a cleavage mediated by the Microprocessor complex containing the Drosha nuclease and the RNA-binding protein DiGeorge critical region 8 (DGCR8). We previously reported that dimeric DGCR8 binds heme and that the heme-bound DGCR8 is more active than the heme-free form. Here, we identified a conserved dimerization domain in DGCR8. Our crystal structure of this domain (residues 298-352) at 1.7 {angstrom} resolution demonstrates a previously unknown use of a WW motif as a platform for extensive dimerization interactions. The dimerization domain of DGCR8 is embedded in an independently folded heme-binding domain and directly contributes to association with heme. Heme-binding-deficient DGCR8 mutants have reduced pri-miRNA processing activity in vitro. Our study provides structural and biochemical bases for understanding how dimerization and heme binding of DGCR8 may contribute to regulation of miRNA biogenesis.

  5. Dimerization Induced Deprotonation of Water on RuO2(110)

    SciTech Connect (OSTI)

    Mu, Rentao; Cantu Cantu, David; Lin, Xiao; Glezakou, Vassiliki Alexandra; Wang, Zhitao; Lyubinetsky, Igor; Rousseau, Roger J.; Dohnalek, Zdenek

    2014-10-02T23:59:59.000Z

    RuO2 has proven to be indispensable as a co-catalyst in numerous systems designed for photocatalytic water splitting. In this study we have carried out a detailed mechanistic study of water behavior on the most stable RuO2 face, RuO2(110), by employing variable temperature scanning tunneling microscopy and density functional theory calculations. We show that water monomers adsorb molecularly on Ru sites, become mobile above 238 K, diffuse along the Ru rows and form water dimers. The onset for dimer diffusion is observed at ~277 K indicating significantly higher diffusion barrier than that for monomers. More importantly, we find that water dimers deprotonate readily to form Ru-bound H3O2 and bridging OH species. The observed behavior is compared and contrasted with that observed for water on isostructural rutile TiO2(110).

  6. Terminal Interface Conformations Modulate Dimer Stability Prior to Amino Terminal Autoprocessing of HIV-1 Protease

    SciTech Connect (OSTI)

    Agniswamy, Johnson; Sayer, Jane M.; Weber, Irene T.; Louis, John M. (GSU); (NIH)

    2012-04-17T23:59:59.000Z

    The HIV-1 protease (PR) mediates its own release (autoprocessing) from the polyprotein precursor, Gag-Pol, flanked by the transframe region (TFR) and reverse transcriptase at its N- and C-termini, respectively. Autoprocessing at the N-terminus of PR mediates stable dimer formation essential for catalytic activity, leading to the formation of infectious virus. An antiparallel {beta}-sheet interface formed by the four N- and C-terminal residues of each subunit is important for dimer stability. Here, we present the first high-resolution crystal structures of model protease precursor-clinical inhibitor (PI darunavir or saquinavir) complexes, revealing varying conformations of the N-terminal flanking (S{sup -4}FNF{sup -1}) and interface residues (P{sup 1}QIT{sup 4}). A 180{sup o} rotation of the T{sup 4}-L{sup 5} peptide bond is accompanied by a new Q{sup 2}-L{sup 5} hydrogen bond and complete disengagement of PQIT from the {beta}-sheet dimer interface, which may be a feature for intramolecular autoprocessing. This result is consistent with drastically lower thermal stability by 14-20 C of PI complexes of precursors and the mature PR lacking its PQIT residues (by 18.3 C). Similar to the TFR-PR precursor, this deletion also results in a darunavir dissociation constant (2 x 10{sup 4})-fold higher and a markedly increased dimer dissociation constant relative to the mature PR. The terminal {beta}-sheet perturbations of the dimeric structure likely account for the drastically poorer inhibition of autoprocessing of TFR-PR relative to the mature PR, even though significant differences in active site-PI interactions in these structures were not observed. The novel conformations of the dimer interface may be exploited to target selectively the protease precursor prior to its N-terminal cleavage.

  7. Complete characterization of the water dimer vibrational ground state and testing the VRT(ASP-W)III,

    E-Print Network [OSTI]

    Cohen, Ronald C.

    Complete characterization of the water dimer vibrational ground state and testing the VRT(ASP-W)III, SAPT-5st, and VRT(MCY-5f) surfaces FRANK N. KEUTSCH1 , NIR GOLDMAN2 , HEATHER A. HARKER3 , CLAUDE of the water dimer very well. The VRT(MCY-5f) and especially the VRT(ASP-W)III potentials show larger

  8. Theoretical Study of Adsorption of Water Dimer on the Perfect MgO(100) Surface: Molecular Adsorption versus Dissociative Chemisorption

    E-Print Network [OSTI]

    Truong, Thanh N.

    Theoretical Study of Adsorption of Water Dimer on the Perfect MgO(100) Surface: Molecular Adsorption versus Dissociative Chemisorption Yan Wang and Thanh N. Truong* Henry Eyring Center on the mode of adsorption of the water dimer on the perfect MgO(100) surface using the ab initio embedded

  9. Coupled cluster benchmarks of water monomers and dimers extracted from density-functional theory liquid water: The importance of monomer

    E-Print Network [OSTI]

    Alavi, Ali

    Coupled cluster benchmarks of water monomers and dimers extracted from density-functional theory functionals in simulations of liquid water, water monomers and dimers were extracted from a PBE simulation liquid water: The importance of monomer deformations Biswajit Santra,1 Angelos Michaelides,1,2,a

  10. Electronic structure of the benzene dimer cation Piotr A. Pieniazek, Anna I. Krylov, and Stephen E. Bradforth

    E-Print Network [OSTI]

    Krylov, Anna I.

    Electronic structure of the benzene dimer cation Piotr A. Pieniazek, Anna I. Krylov, and Stephen E-0482 Received 20 March 2007; accepted 22 May 2007; published online 31 July 2007 The benzene and benzene dimer benzene. Both sandwich and t-shaped structures feature intense charge resonance bands, whose location

  11. Parallel Dimers and Anti-parallel Tetramers Formed by Epidermal Growth Factor Receptor Pathway Substrate Clone 15 (EPS15)*

    E-Print Network [OSTI]

    Kirchhausen, Tomas

    Parallel Dimers and Anti-parallel Tetramers Formed by Epidermal Growth Factor Receptor Pathway- dependent endocytic traffic. We report here that Eps15 forms dimers and tetramers of distinct shape. The Eps tetramer has a "dumbbell" shape, 31 nm in length; it is formed by the anti-parallel association of two Eps

  12. Theoretical/Computational Tools for Energy-Relevant Catalysis | The Ames

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin Transition in theTheoretical Study on Catalysis by

  13. Linking local structure and properties in perovskites containing equal concentrations of manganese and ruthenium

    SciTech Connect (OSTI)

    King, Graham; Ricciardo, Rebecca A.; Soliz, Jennifer R.; Woodward, Patrick M.; Llobet, Anna (OSU); (LANL)

    2011-08-16T23:59:59.000Z

    The local structures of six perovskite compounds containing equal amounts of manganese and ruthenium on the B-site have been investigated by neutron and x-ray pair distribution function analysis. The compounds SrMn{sub 0.5}Ru{sub 0.5}O{sub 3}, Sr{sub 0.5}Ca{sub 0.5}Mn{sub 0.5}Ru{sub 0.5}O{sub 3}, and CaMn{sub 0.5}Ru{sub 0.5}O{sub 3} were studied to investigate the effects of pure chemical pressure on the local structure and valency ratio between Mn{sup 3+}/Ru{sup 5+} and Mn{sup 4+}/Ru{sup 4+}. Reverse Monte Carlo simulations confirm that there is a shift in the B-site cation charge distribution from nearly equal amounts of Mn{sup 3+}, Ru{sup 5+}, Mn{sup 4+}, and Ru{sup 4+} for SrMn{sub 0.5}Ru{sub 0.5}O{sub 3} to primarily Mn{sup 4+} and Ru{sup 4+} for CaMn{sub 0.5}Ru{sub 0.5}O{sub 3}. The compounds Ba{sub 0.5}La{sub 0.5}Mn{sub 0.5}Ru{sub 0.5}O{sub 3}, Ca{sub 0.5}La{sub 0.5}Mn{sub 0.5}Ru{sub 0.5}O{sub 3}, and Sr{sub 0.5}Ca{sub 0.25}La{sub 0.25}Mn{sub 0.5}Ru{sub 0.5}O{sub 3} were also investigated to study the effects of changing the charge of the A-site cation. Although substitution of La{sup 3+} for a divalent alkaline earth ion increases the Mn{sup 3+} content, this series of compounds also shows a relative increase in the concentration of Mn{sup 4+} as the average size of the A-site cation is decreased. In all compounds the octahedra containing Mn{sup 3+} are found to be Jahn-Teller distorted regardless of whether or not long-range orbital ordering is observed, while the Ru-centered octahedra are symmetric. No evidence for short-range cation ordering at either the A- or B-sites was found for any of the compositions. This study also reports that locally the A-site cations lie closer to the Mn ions than to the Ru ions and this asymmetry appears to be correlated to the degree of octahedral tilting.

  14. Water dimer hydrogen bond stretch, donor torsion overtone, and ``in-plane bend'' vibrations

    E-Print Network [OSTI]

    Cohen, Ronald C.

    Water dimer hydrogen bond stretch, donor torsion overtone, and ``in-plane bend'' vibrations Frank N. Brown Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Heather A. Harker and Poul B. © 2003 American Institute of Physics. DOI: 10.1063/1.1614774 I. INTRODUCTION Water clusters have been

  15. Ultralow-power local laser control of the dimer density in alkali-metal vapors

    E-Print Network [OSTI]

    Jha, Pankaj K; Yi, Zhenhuan; Yuan, Luqi; Sautenkov, Vladimir A; Rostovtsev, Yuri V; Welch, George R; Zheltikov, Aleksei M; Scully, Marlan O

    2011-01-01T23:59:59.000Z

    Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.

  16. ERK Nuclear Translocation Is Dimerization-independent but Controlled by the Rate of Phosphorylation*S

    E-Print Network [OSTI]

    Rieger, Bernd

    ERK Nuclear Translocation Is Dimerization-independent but Controlled by the Rate of Phosphorylation, Universite´ de Nice, Centre A. Lacassagne, 06189 Nice, France Upon activation, ERKs translocate from the molecular mechanisms that regulate ERK nuclear translocation are not fully understood. We have used a mouse

  17. Higher Energy States in the CO Dimer: Millimeter-Wave Spectra and Rovibrational Calculations

    E-Print Network [OSTI]

    Higher Energy States in the CO Dimer: Millimeter-Wave Spectra and Rovibrational Calculations Leonid, Russia Ge´ W. M. Vissers Department of Chemistry, The Ohio State UniVersity, Columbus, Ohio 43210 Ad van millimeter-wave data yielded the precise location of 33 new energy levels of A+ symmetry and 20 levels of A

  18. Isotope effects in the CO dimer: Millimeter wave spectrum and rovibrational calculations of ,,12

    E-Print Network [OSTI]

    . M. Vissers Department of Chemistry, The Ohio State University, Columbus, Ohio 43210 A. van der. The isotopic dependence of the A+ /A- energy splitting, the intermolecular separation R, and the energy in understanding the previously mysteri- ous spectra of the carbon monoxide dimer as well as its energy level

  19. 2010 Macmillan Publishers Limited. All rights reserved. Highly stable tetrathiafulvalene radical dimers in

    E-Print Network [OSTI]

    Goddard III, William A.

    Stoddart1 * Two [3]catenane `molecular flasks' have been designed to create stabilized, redox observation of p­p radical-cation dimers on the redox stimulation of electron rich or poor heterocycles, rather than the fundamental cornerstone of functional devices7 . Specifically, methyl viologen (MV2þ

  20. Analyzing human epidermal growth factor receptor family dimerization and activation using Duolink

    E-Print Network [OSTI]

    Cai, Long

    dimerization and activation. Two different cell lines, SKBR3 (known to express EGFR and high levels of HER2 using an anti- EGFR antibody (Y-1068). However, only the SKBR3 cell line gave a detectable signal after. Both cell lines responded to EGF stimulation by phosphorylation of EGFR (Fig. 2), which was measured

  1. Synthesis of a 7-Azaindole by Chichibabin Cyclization: Reversible Base-Mediated Dimerization of 3-Picolines

    E-Print Network [OSTI]

    Collum, David B.

    Synthesis of a 7-Azaindole by Chichibabin Cyclization: Reversible Base-Mediated Dimerization of 3 of heteroannulation- appending a pyrrole to a pyridine or vice versa.1,2 In connection with a program at Sanofi-Aventis to synthesize polycyclic pyrrole derivatives to be tested for the treatment of asthma,2c the conversion of 2

  2. Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Imido Dimer Formation and

    E-Print Network [OSTI]

    Schlegel, H. Bernhard

    Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Imido Dimer Formation- ization of Ti(NR2)2NH in the chemical vapor deposition (CVD) of titanium nitride films. This study uses lead to the formation of higher oligomers. Introduction Titanium nitride thin films have a number

  3. Close Mimicry of Lung Surfactant Protein B by ``Clicked'' Dimers of Helical, Cationic Peptoids

    E-Print Network [OSTI]

    Barron, Annelise E.

    Close Mimicry of Lung Surfactant Protein B by ``Clicked'' Dimers of Helical, Cationic Peptoids-protein mixture that lines the air-liquid (a/l) interface of vertebrate lungs and varies surface tension (c, mN m, maximizes lung Michelle T. Dohm and Shannon L. Seurynck-Servoss contributed equally to this work. Contract

  4. Recognition of HIV TAR RNA by triazole linked neomycin dimers Sunil Kumar, Dev P. Arya

    E-Print Network [OSTI]

    Stuart, Steven J.

    protein, (a 86 amino acid protein) and regulates the transcription of HIV virus. TAR RNA­Tat proteinRecognition of HIV TAR RNA by triazole linked neomycin dimers Sunil Kumar, Dev P. Arya Laboratory synthesized using `click chemistry' with varying linker function- ality and length to target the TAR RNA

  5. Molecular Dynamics Simulation of Amyloid b Dimer Formation B. Urbanc,* L. Cruz,* F. Ding,*y

    E-Print Network [OSTI]

    Stanley, H. Eugene

    of amyloid plaques. Hence, finding the conformation of these oligo- meric forms of Ab may be important; Thompson, 2003). The most common view is that Ab(1­40) and Ab(1­ 42) in fibrils form parallel bMolecular Dynamics Simulation of Amyloid b Dimer Formation B. Urbanc,* L. Cruz,* F. Ding,*y D

  6. A Novel Dimerization Interface of Cyclic Nucleotide Binding Domain, which is

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 A Novel Dimerization Interface of Cyclic Nucleotide Binding Domain, which is Disrupted Modeling 18, 9 (2012) 4053-4060" DOI : 10.1007/s00894-012-1404-5 #12;2 ABSTRACT Cyclic nucleotide binding and eukaryota. CNBD activation by cyclic nucleotide monophosphate (cNMP) is studied well in case of several

  7. Functional Characterization of Rhodopsin Monomers and Dimers in Detergents*S

    E-Print Network [OSTI]

    Palczewski, Krzysztof

    International Institute of Molecular and Cell Biology, Warsaw PL-02109, Poland Rhodopsin (Rho) is a G protein-coupled from atomic force microscopy, transmission electron microscopy, and chemical cross-linking experiments resistant to heat denaturation. Both Rho* mono- mers and dimers are capable of activating Gt, and both

  8. The Mechanical Fingerprint of a Parallel Polyprotein Dimer Atom Sarkar, Sofia Caamano, and Julio M. Fernandez

    E-Print Network [OSTI]

    Fernandez, Julio M.

    The Mechanical Fingerprint of a Parallel Polyprotein Dimer Atom Sarkar, Sofia Caamano, and Julio M and in final form 22 November 2006. Address reprint requests and inquiries to Atom Sarkar, E-mail: atom.sarkar@osumc.edu; or Julio M. Fernandez, E-mail: jfernandez@columbia.edu. Atom Sarkar's present address is Dept

  9. Proton Mediated Chemistry and Catalysis in a Self-Assembled Supramolecular Host

    SciTech Connect (OSTI)

    Pluth, Michael; Bergman, Robert; Raymond, Kenneth

    2009-04-10T23:59:59.000Z

    Synthetic supramolecular host assemblies can impart unique reactivity to encapsulated guest molecules. Synthetic host molecules have been developed to carry out complex reactions within their cavities, despite the fact that they lack the type of specifically tailored functional groups normally located in the analogous active sites of enzymes. Over the past decade, the Raymond group has developed a series of self-assembled supramolecules and the Bergman group has developed and studied a number of catalytic transformations. In this Account, we detail recent collaborative work between these two groups, focusing on chemical catalysis stemming from the encapsulation of protonated guests and expanding to acid catalysis in basic solution. We initially investigated the ability of a water-soluble, self-assembled supramolecular host molecule to encapsulate protonated guests in its hydrophobic core. Our study of encapsulated protonated amines revealed rich host-guest chemistry. We established that self-exchange (that is, in-out guest movement) rates of protonated amines were dependent on the steric bulk of the amine rather than its basicity. The host molecule has purely rotational tetrahedral (T) symmetry, so guests with geminal N-methyl groups (and their attendant mirror plane) were effectively desymmetrized; this allowed for the observation and quantification of the barriers for nitrogen inversion followed by bond rotation. Furthermore, small nitrogen heterocycles, such as N-alkylaziridines, N-alkylazetidines, and N-alkylpyrrolidines, were found to be encapsulated as proton-bound homodimers or homotrimers. We further investigated the thermodynamic stabilization of protonated amines, showing that encapsulation makes the amines more basic in the cavity. Encapsulation raises the effective basicity of protonated amines by up to 4.5 pK{sub a} units, a difference almost as large as that between the moderate and strong bases carbonate and hydroxide. The thermodynamic stabilization of protonated guests was translated into chemical catalysis by taking advantage of the potential for accelerating reactions that take place via positively charged transition states, which could be potentially stabilized by encapsulation. Orthoformates, generally stable in neutral or basic solution, were found to be suitable substrates for catalytic hydrolysis by the assembly. Orthoformates small enough to undergo encapsulation were readily hydrolyzed by the assembly in basic solution, with rate acceleration factors up to 3900 compared with those of the corresponding uncatalyzed reactions. Furthering the analogy to enzymes that obey Michaelis-Menten kinetics, we observed competitive inhibition with the inhibitor NPr{sub 4}{sup +}, thereby confirming that the interior cavity of the assembly was the active site for catalysis. Mechanistic studies revealed that the assembly is required for catalysis and that the rate-limiting step of the reaction involves proton transfer from hydronium to the encapsulated substrate. Encapsulation in the assembly changes the orthoformate hydrolysis from an A-1 mechanism (in which decomposition of the protonated substrate is the rate-limiting step) to an A-S{sub E}2 mechanism (in which proton transfer is the rate-limiting step). The study of hydrolysis in the assembly was next extended to acetals, which were also catalytically hydrolyzed by the assembly in basic solution. Acetal hydrolysis changed from the A-1 mechanism in solution to an A-2 mechanism inside the assembly, where attack of water on the protonated substrate is rate limiting. This work provides rare examples of assembly-catalyzed reactions that proceed with substantial rate accelerations despite the absence of functional groups in the cavity and with mechanisms fully elucidated by quantitative kinetic studies.

  10. General basic and coordination catalysis in reactions of haloaromatic compounds with ammonia in the presence of copper(I) compounds

    SciTech Connect (OSTI)

    Chumak, V.T.; Shein, S.M.

    1985-11-01T23:59:59.000Z

    This paper presents a study made to detect general basic catalysis by ammonia (reagent) in reactions of ammonolysis of haloaromatic compounds in the presence of Cu/sup +/ ions, as well as to determine the generality of the mechanisms of the catalytic replacement of a halogen atom by an amino group in the anthraquinone and benzene series.

  11. Effects of catalysis on particle motion in plane-parallel and cylindrical channels in a catalytic reactor

    SciTech Connect (OSTI)

    Kabanov, A.N.; Murashkevich, F.I.; Shulimanova, Z.L.; Shukin, E.R.

    1987-09-01T23:59:59.000Z

    A theoretical study is made on aerosol behavior in a catalysis zone for a plane-parallel or cylindrical channel in a catalytic reactor. It is found that the thermophoretic trapping coefficient may attain 10-15% in a laminar flow having longitudinal Pe and Re >> 1 even for small relative temperature differences.

  12. Decarboxylative Arylation of Amino Acids via Photoredox Catalysis: A One-Step Conversion of Biomass to Drug

    E-Print Network [OSTI]

    MacMillan, David W. C.

    Decarboxylative Arylation of Amino Acids via Photoredox Catalysis: A One-Step Conversion of Biomass. This method offers rapid entry to prevalent benzylic amine architectures from an abundant biomass the worldwide abundance of biomass6 that incorporates carboxylate functionality (e.g., amino acids, -hydroxy

  13. Approved Module Information for CH3010, 2014/5 Module Title/Name: Catalysis Module Code: CH3010

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for CH3010, 2014/5 Module Title/Name: Catalysis Module Code: CH3010 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module Credits: 10 in which available: BSc/MChem Applied Chemistry. BSc/MChem Chemistry. BEng/MEng Chemical Engineering. MEng

  14. Structure of Human Epoxide Hydrolase Reveals Mechanistic Inferences on Bifunctional Catalysis in Epoxide and Phosphate Ester Hydrolysis,

    E-Print Network [OSTI]

    Hammock, Bruce D.

    is unclear. Recent experiments demonstrate that the N-terminal domain of human sEH catalyzes the metalStructure of Human Epoxide Hydrolase Reveals Mechanistic Inferences on Bifunctional Catalysis ReceiVed February 4, 2004 ABSTRACT: The X-ray crystal structure of human soluble epoxide hydrolase (s

  15. Applied Catalysis A: General 219 (2001) 215222 Structural analysis of unpromoted Fe-based FischerTropsch

    E-Print Network [OSTI]

    Iglesia, Enrique

    2001-01-01T23:59:59.000Z

    Applied Catalysis A: General 219 (2001) 215­222 Structural analysis of unpromoted Fe-based Fischer­Tropsch by Mössbauer emission and X-ray absorption spectroscopies after use in the Fischer­Tropsch synthesis (FTS reactant mixture. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Fischer­Tropsch synthesis; X

  16. Zeolite catalysis

    SciTech Connect (OSTI)

    Chu, P.; Garwood, W.E.; Schwartz, A.B.

    1988-11-29T23:59:59.000Z

    This patent describes a process for preparing hydrocarbons boiling in the gasoline and/or distillate range by contacting a feedstock comprising lower molecular weight olefins in a reaction zone under conditions of elevated temperature and pressure with a shape selective crystalline aluminosilicate catalyst, comprising: reducing the non-shape selective surface-cracking and/or surface isomerization activity of the aluminosilicate catalyst by a process comprising: preparing an aqueous solution comprising colloidal silica, optionally an organic directing agent, and a source of hydroxide ions; mixing the aqueous solution with an aqueous dispersion of shape-selective crystalline aluminosilicate to form a homogeneous mixture which is subsequently heated; adding an aqueous solution comprising a source of fluoride ions to the homogeneous mixture to form a reactive composition; heating the reactive composition at a temperature to effectively form a surface-deactivated catalyst comprising a crystalline fluoride-containing silica outer shell on an aluminosilicate; withdrawing the surface-deactivated catalyst from the reactive composition for washing, drying, and calcining of the catalyst; and removing the catalyst to the reaction zone for contact with the olefin feedstock.

  17. Asymmetry of rotational catalysis of single membrane-bound F0F1-ATP synthase

    E-Print Network [OSTI]

    Zarrabi, Nawid; Diez, Manuel; Graeber, Peter; Wrachtrup, Joerg; Boersch, Michael

    2007-01-01T23:59:59.000Z

    Synthesis of the cellular 'energy currency' ATP is catalyzed by membrane-bound F0F1-ATP synthases. The chemical reaction at three binding sites in the F1 part is coupled to proton translocation through the membrane-integrated F0 part by an internal rotation of subunits. We examined the rotary movements of the epsilon-subunit of the 'rotor' with respect to the b-subunits of the 'stator' by single-molecule fluorescence resonance energy transfer (FRET). Rotation of epsilon during ATP hydrolysis is divided into three major steps with constant FRET level corresponding to three binding sites. Different catalytic activities of the individual binding sites were observed depending on the relative orientation of the 'rotor'. Computer simulations of the FRET signals and non-equally distributed orientations of epsilon strongly corroborate asymmetry of catalysis in F0F1-ATP synthase.

  18. Methane Oxidation to Methanol without CO2 Emission: Catalysis by Atomic Negative Ions

    E-Print Network [OSTI]

    Tesfamichael, Aron; Felfli, Zineb; Msezane, Alfred Z

    2014-01-01T23:59:59.000Z

    The catalytic activities of the atomic Y-, Ru-, At-, In-, Pd-, Ag-, Pt-, and Os- ions have been investigated theoretically using the atomic Au- ion as the benchmark for the selective partial oxidation of methane to methanol without CO2 emission. Dispersion-corrected density-functional theory has been used for the investigation. From the energy barrier calculations and the thermodynamics of the reactions, we conclude that the catalytic effect of the atomic Ag-, At-, Ru-, and Os- ions is higher than that of the atomic Au- ion catalysis of CH4 conversion to methanol. By controlling the temperature around 290K (Os-), 300K (Ag-), 310K (At-), 320K (Ru-) and 325K (Au-) methane can be completely oxidized to methanol without the emission of CO2. We conclude by recommending the investigation of the catalytic activities of combinations of the above negative ions for significant enhancement of the selective partial oxidation of methane to methanol.

  19. Is It Homogeneous or Heterogeneous Catalysis Derived from [RhCp*Cl2]2? In Operando-XAFS, Kinetic and Crucial Kinetic Poisoning Evidence for Subnanometer Rh4 Cluster-Based Benzene Hydrogenation Catalysis

    SciTech Connect (OSTI)

    Bayram, Ercan; Linehan, John C.; Fulton, John L.; Roberts, John A.; Szymczak, Nathaniel; Smurthwaite, Tricia D.; Ozkar, Saim; Balasubramanian, Mahalingam; Finke, Richard G.

    2011-11-23T23:59:59.000Z

    Determining the true, kinetically dominant catalytically active species, in the classic benzene hydrogenation system pioneered by Maitlis and co-workers 34 years ago starting with [RhCp*Cl2]2 (Cp* = [{eta}5-C5(CH3)5]), has proven to be one of the most challenging case studies in the quest to distinguish single-metal-based 'homogeneous' from polymetallic, 'heterogeneous' catalysis. The reason, this study will show, is the previous failure to use the proper combination of (i) operando spectroscopy to determine the dominant form(s) of the precatalyst's mass under catalysis (i.e., operating) conditions, plus then and crucially also (ii) the previous lack of the necessary kinetic studies, catalysis being a 'wholly kinetic phenomenon' as J. Halpern long ago noted. An important contribution from this study will be to reveal the power of quantitiative kinetic poisoning experiments for distinguishing single-metal, or in this case subnanometer Rh4 cluster-based catalysis from larger, polymetallic Rh(0)n nanoparticle catalysis, at least under favorable conditions. The combined operando-XAFS (X-ray absorption fine structure) spectroscopy and kinetic evidences provide a compelling case for Rh4-based, with average stoichiometry 'Rh4Cp*2.4Cl4Hc', benzene hydrogenation catalysis in 2-propanol with added Et3N and at 100 C and 50 atm initial H2 pressure. The results also reveal, however, that if even ca. 1.4% of the total soluble Rh(0)n had formed nanoparticles, then those Rh(0)n nanoparticles would have been able to account for all the observed benzene hydrogenation catalytic rate (using commercial, ca. 2 nm, polyethyleneglycol-dodecylether hydrosol stabilized Rh(0)n nanoparticles as a model system). The results 'especially the poisoning methodology developed and employed' are of significant, broader interest since determining the nature of the true catalyst continues to be a central, often vexing issue in any and all catalytic reactions. The results are also of fundamental interest in that they add to a growing body of evidence indicating that certain, appropriately ligated, coordinatively unsaturated, subnanometer M4 transition-metal clusters can be relatively robust catalysts. Also demonstrated herein is that Rh4 clusters are poisoned by Hg(0), demonstrating for the first time that the classic Hg(0) poisoning test of 'homogeneous' vs 'heterogeneous'catalysts cannot distinguish Rh4-based subnanometer catalysts from Rh(0)n nanoparticle catalysts, at least for the present examples of these two specific, Rh-based catalysts.

  20. Elastic properties of the degenerate f.c.c. crystal of polydisperse soft dimers at zero temperature

    E-Print Network [OSTI]

    J. W. Narojczyk; K. W. Wojciechowski

    2015-04-12T23:59:59.000Z

    Elastic properties of soft, three-dimensional dimers, interacting through site-site n-inverse-power potential, are determined by computer simulations at zero temperature. The degenerate crystal of dimers exhibiting (Gaussian) size distribution of atomic diameters - i.e. size polydispersity - is studied at the molecular number density $1/\\sqrt{2}$; the distance between centers of atoms forming dimers is considered as a length unit. It is shown that, at the fixed number density of the dimers, increasing polydispersity causes, typically, an increase of pressure, elastic constants and Poisson's ratio; the latter is positive in most direction. A direction is found, however, in which the size polydispersity causes substantial decrease of Poisson's ratio, down to negative values for large $n$. Thus, the system is partially auxetic for large polydispersity and large n.

  1. Elastic properties of the degenerate f.c.c. crystal of polydisperse soft dimers at zero temperature

    E-Print Network [OSTI]

    Narojczyk, J W

    2015-01-01T23:59:59.000Z

    Elastic properties of soft, three-dimensional dimers, interacting through site-site n-inverse-power potential, are determined by computer simulations at zero temperature. The degenerate crystal of dimers exhibiting (Gaussian) size distribution of atomic diameters - i.e. size polydispersity - is studied at the molecular number density $1/\\sqrt{2}$; the distance between centers of atoms forming dimers is considered as a length unit. It is shown that, at the fixed number density of the dimers, increasing polydispersity causes, typically, an increase of pressure, elastic constants and Poisson's ratio; the latter is positive in most direction. A direction is found, however, in which the size polydispersity causes substantial decrease of Poisson's ratio, down to negative values for large $n$. Thus, the system is partially auxetic for large polydispersity and large n.

  2. A Concise and Versatile Double-Cyclization Strategy for the Highly Stereoselective Synthesis and Arylative Dimerization of Aspidosperma Alkaloids

    E-Print Network [OSTI]

    Medley, Jonathan William

    Building cycles: A strategy for the concise, stereoselective synthesis of aspidosperma alkaloids and related structures via a common putative diiminium ion intermediate is reported. The approach enables the dimerization ...

  3. Superacid catalysis of light hydrocarbon conversion. Sixth quarterly report, January 1, 1995--March 31, 1995

    SciTech Connect (OSTI)

    Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

    1995-08-01T23:59:59.000Z

    Iron- and Manganese-promoted sulfated zirconia is a catalyst for the conversion of propane, but the rate of conversion of propane is much less than the rate of conversion of butane. Whereas this catalyst appears to be a good candidate for practical, industrial conversion of butane, it appears to lack sufficient activity for practical conversion of propane. Perhaps more active catalysts will be useful for propane conversion. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversions; they are consistent with the inference that the catalyst is a superacid and that the chemistry is analogous to. that determined in superacid solutions by G.A. Olah, who was awarded the most recent Nobel Prize in chemistry for his work. The catalyst was tested for conversion of propane at 1 bar, 200--300{degrees}C and propane partial pressures in the range of 0.01--0.05 bar. At 250{degrees}C, catalysis was demonstrated, as the number of propane molecules converted was at least 1 per sulfate group after 16 days of operation in a continues flow reactor. Propane was converted in high yield to butanes, but the conversions were low, for example being only a fraction of a percent at a space velocity of 9.1 {times} 10{sup {minus}7} mol(g of catalysis {center_dot} s) and 250{degrees}C. Coke formation was rapid. The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.

  4. Molecular orbital calculations on transition metal dimers containing a linear dinitrogen bridge

    E-Print Network [OSTI]

    Powell, Mary Cynthia

    1984-01-01T23:59:59.000Z

    Cp2(NZ)}2- (NZ)] dimer. Molecular orbital diagram for the [{Re(PH3)4C1}- {MoC14(OH}] dimer. . . . . . . . . . . . . . . . . . 28 Molecular orbital plots of the le, 2e, 3e, and 4e MOs for [{Ru(NH3)6}2(NZ)] in the xz plane . . . 31 4+ . Molecular... orbital plots of the le, 2e, 3e, and 4e MOs for [{Nb(CHZ)(CH3)(PH3)2}2(N2)] in the xz plane Molecular orbital plots of the 3e MO for [{Nb(CHZ)(CH3)(PH3)2}2(N2)] in the plane con- taining the CZ axis and the plane perpendicular to the C2 axis...

  5. Atomic site sensitive processes in low energy ion-dimer collisions

    E-Print Network [OSTI]

    W. Iskandar; J. Matsumoto; A. Leredde; X. Fléchard; B. Gervais; S. Guillous; D. Hennecart; A. Méry; J. Rangama; C. L. Zhou; H. Shiromaru; A. Cassimi

    2014-05-12T23:59:59.000Z

    Electron capture processes for low energy Ar9+ ions colliding on Ar2 dimer targets are investigated, focusing attention on charge sharing as a function of molecule orientation and impact parameter. A preference in charge-asymmetric dissociation channels is observed, with a strong correlation between the projectile scattering angle and the molecular ion orientation. The measurements provide here clear evidences that projectiles distinguish each atom in the target and, that electron capture from near-site atom is favored. Monte Carlo calculations based on the classical over-the-barrier model, with dimer targets represented as two independent atoms, are compared to the data. They give a new insight into the dynamics of the collision by providing, for the di erent electron capture channels, the two-dimensional probability maps p(~b), where ~b is the impact parameter vector in the molecular frame.

  6. Modeling theta-theta Interactions with the Effective Fragment Potential Method: The Benzene Dimer and Substituents

    SciTech Connect (OSTI)

    Toni Smithl; Lyudmila V. Slipchenko; Mark S. Gordon

    2008-02-27T23:59:59.000Z

    This study compares the results of the general effective fragment potential (EFP2) method to the results of a previous combined coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] and symmetry-adapted perturbation theory (SAPT) study [Sinnokrot and Sherrill, J. Am. Chem. Soc., 2004, 126, 7690] on substituent effects in {pi}-{pi} interactions. EFP2 is found to accurately model the binding energies of the benzene-benzene, benzene-phenol, benzene-toluene, benzene-fluorobenzene, and benzene-benzonitrile dimers, as compared with high-level methods [Sinnokrot and Sherrill, J. Am. Chem. Soc., 2004, 126, 7690], but at a fraction of the computational cost of CCSD(T). In addition, an EFP-based Monte Carlo/simulated annealing study was undertaken to examine the potential energy surface of the substituted dimers.

  7. Interaction energies of monosubstituted benzene dimers via nonlocal density functional theory

    E-Print Network [OSTI]

    T. Thonhauser; Aaron Puzder; David C. Langreth

    2005-09-15T23:59:59.000Z

    We present density-functional calculations for the interaction energy of monosubstituted benzene dimers. Our approach utilizes a recently developed fully nonlocal correlation energy functional, which has been applied to the pure benzene dimer and several other systems with promising results. The interaction energy as a function of monomer distance was calculated for four different substituents in a sandwich and two T-shaped configurations. In addition, we considered two methods for dealing with exchange, namely using the revPBE generalized gradient functional as well as full Hartree-Fock. Our results are compared with other methods, such as Moller-Plesset and coupled-cluster calculations, thereby establishing the usefulness of our approach. Since our density-functional based method is considerably faster than other standard methods, it provides a computational inexpensive alternative, which is of particular interest for larger systems where standard calculations are too expensive or infeasible.

  8. Molecular Beam Scattering of Aligned Oxygen Molecules. The Nature of the Bond in the O2-O2 Dimer

    E-Print Network [OSTI]

    Pirani, Fernando

    . These results indicate that most of the bonding in the dimer comes from van der Waals forces, but chemical (spin that it is not paramagnetic." He also gave a value of 5.60 meV for the heat of dissociation of the O2-O2 dimer. Actually from different spin coupling of the monomers in the ground electronic state. Spin coupling leads

  9. Vapor Synthesis and Thermal Modification of Supportless Platinum-Ruthenium Nanotubes and Application as Methanol Electrooxidation Catalysts

    SciTech Connect (OSTI)

    Atkinson III, Robert [University of Tennessee (UT); Unocic, Raymond R [ORNL; Unocic, Kinga A [ORNL; Veith, Gabriel M [ORNL; Papandrew, Alexander B [ORNL; Zawodzinski, Thomas A [ORNL

    2015-01-01T23:59:59.000Z

    Metallic, mixed-phase, and alloyed bimetallic Pt-Ru nanotubes were synthesized by a novel route based on the sublimation of metal acetylacetonate precursors and their subsequent vapor deposition within anodic alumina templates. Nanotube architectures were tuned by thermal annealing treatments. As-synthesized nanotubes are composed of nanoparticulate, metallic platinum and hydrous ruthenium oxide whose respective thicknesses depend on the sample chemical composition. The Pt-decorated, hydrous Ru oxide nanotubes may be thermally annealed to promote a series of chemical and physical changes to the nanotube structures including alloy formation, crystallite growth and morphological evolution. Annealed Pt-Ru alloy nanotubes and their as-synthesized analogs demonstrate relatively high specific activities for the oxidation of methanol. As-synthesized, mixed-phase Pt-Ru nanotubes (0.39 mA/cm2) and metallic alloyed Pt64Ru36NTs (0.33 mA/cm2) have considerably higher area-normalized activities than PtRu black (0.22 mA/cm2) at 0.65 V vs. RHE.

  10. Adsorption of Ruthenium, Rhodium and Palladium from Simulated High-Level Liquid Waste by Highly Functional Xerogel - 13286

    SciTech Connect (OSTI)

    Onishi, Takashi [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan)] [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan); Koyama, Shin-ichi [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan)] [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan); Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University Aramaki-Aza-Aoba 6-6-01-2,Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan)] [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University Aramaki-Aza-Aoba 6-6-01-2,Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan)

    2013-07-01T23:59:59.000Z

    Fission products are generated by fission reactions in nuclear fuel. Platinum group (Pt-G) elements, such as palladium (Pd), rhodium (Rh) and ruthenium (Ru), are also produced. Generally, Pt-G elements play important roles in chemical and electrical industries. Highly functional xerogels have been developed for recovery of these useful Pt-G elements from high - level radioactive liquid waste (HLLW). An adsorption experiment from simulated HLLW was done by the column method to study the selective adsorption of Pt-G elements, and it was found that not only Pd, Rh and Ru, but also nickel, zirconium and tellurium were adsorbed. All other elements were not adsorbed. Adsorbed Pd was recovered by washing the xerogel-packed column with thiourea solution and thiourea - nitric acid mixed solution in an elution experiment. Thiourea can be a poison for automotive exhaust emission system catalysts, so it is necessary to consider its removal. Thermal decomposition and an acid digestion treatment were conducted to remove sulfur in the recovered Pd fraction. The relative content of sulfur to Pd was decreased from 858 to 0.02 after the treatment. These results will contribute to design of the Pt-G element separation system. (authors)

  11. The reaction dynamics of alkali dimer molecules and electronically excited alkali atoms with simple molecules

    SciTech Connect (OSTI)

    Hou, H. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.

    1995-12-01T23:59:59.000Z

    This dissertation presents the results from the crossed molecular beam studies on the dynamics of bimolecular collisions in the gas phase. The primary subjects include the interactions of alkali dimer molecules with simple molecules, and the inelastic scattering of electronically excited alkali atoms with O{sub 2}. The reaction of the sodium dimers with oxygen molecules is described in Chapter 2. Two reaction pathways were observed for this four-center molecule-molecule reaction, i.e. the formations of NaO{sub 2} + Na and NaO + NaO. NaO{sub 2} products exhibit a very anisotropic angular distribution, indicating a direct spectator stripping mechanism for this reaction channel. The NaO formation follows the bond breaking of O{sub 2}, which is likely a result of a charge transfer from Na{sub 2} to the excited state orbital of O{sub 2}{sup {minus}}. The scattering of sodium dimers from ammonium and methanol produced novel molecules, NaNH{sub 3} and Na(CH{sub 3}OH), respectively. These experimental observations, as well as the discussions on the reaction dynamics and the chemical bonding within these molecules, will be presented in Chapter 3. The lower limits for the bond dissociation energies of these molecules are also obtained. Finally, Chapter 4 describes the energy transfer between oxygen molecules and electronically excited sodium atoms.

  12. The HPr Proteins from the Thermophile Bacillus stearothermophilus Can Form Domain-swapped Dimers

    SciTech Connect (OSTI)

    Sridharan, Sudharsan; Razvi, Abbas; Scholtz, J. Martin; Sacchettini, James C. (TAM)

    2010-07-20T23:59:59.000Z

    The study of proteins from extremophilic organisms continues to generate interest in the field of protein folding because paradigms explaining the enhanced stability of these proteins still elude us and such studies have the potential to further our knowledge of the forces stabilizing proteins. We have undertaken such a study with our model protein HPr from a mesophile, Bacillus subtilis, and a thermophile, Bacillus stearothermophilus. We report here the high-resolution structures of the wild-type HPr protein from the thermophile and a variant, F29W. The variant proved to crystallize in two forms: a monomeric form with a structure very similar to the wild-type protein as well as a domain-swapped dimer. Interestingly, the structure of the domain-swapped dimer for HPr is very different from that observed for a homologous protein, Crh, from B. subtilis. The existence of a domain-swapped dimer has implications for amyloid formation and is consistent with recent results showing that the HPr proteins can form amyloid fibrils. We also characterized the conformational stability of the thermophilic HPr proteins using thermal and solvent denaturation methods and have used the high-resolution structures in an attempt to explain the differences in stability between the different HPr proteins. Finally, we present a detailed analysis of the solution properties of the HPr proteins using a variety of biochemical and biophysical methods.

  13. The Structure of the Poxvirus A33 Protein Reveals a Dimer of Unique C-Type Lectin-Like Domains

    SciTech Connect (OSTI)

    Su, Hua-Poo; Singh, Kavita; Gittis, Apostolos G.; Garboczi, David N. (NIH)

    2010-11-03T23:59:59.000Z

    The current vaccine against smallpox is an infectious form of vaccinia virus that has significant side effects. Alternative vaccine approaches using recombinant viral proteins are being developed. A target of subunit vaccine strategies is the poxvirus protein A33, a conserved protein in the Chordopoxvirinae subfamily of Poxviridae that is expressed on the outer viral envelope. Here we have determined the structure of the A33 ectodomain of vaccinia virus. The structure revealed C-type lectin-like domains (CTLDs) that occur as dimers in A33 crystals with five different crystal lattices. Comparison of the A33 dimer models shows that the A33 monomers have a degree of flexibility in position within the dimer. Structural comparisons show that the A33 monomer is a close match to the Link module class of CTLDs but that the A33 dimer is most similar to the natural killer (NK)-cell receptor class of CTLDs. Structural data on Link modules and NK-cell receptor-ligand complexes suggest a surface of A33 that could interact with viral or host ligands. The dimer interface is well conserved in all known A33 sequences, indicating an important role for the A33 dimer. The structure indicates how previously described A33 mutations disrupt protein folding and locates the positions of N-linked glycosylations and the epitope of a protective antibody.

  14. Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection

    SciTech Connect (OSTI)

    Daniela Rodica Radu

    2005-12-19T23:59:59.000Z

    The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu{sup 2+} as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on the surface of MSN and utilize them to complex cationic DNA. The p-EGFP-CI gene-coated MSN nanocomposite was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. The gene carrier ability of MSNs was further proved by transfecting primary cells and cotransfecting of two different genes in cancer cell lines. In sum, MSN are versatile partners in several types of applications.

  15. Probing the Impact of the EchinT C-Terminal Domain on Structure and Catalysis

    SciTech Connect (OSTI)

    S Bardaweel; J Pace; T Chou; V Cody; C Wagner

    2011-12-31T23:59:59.000Z

    Histidine triad nucleotide binding protein (Hint) is considered as the ancestor of the histidine triad protein superfamily and is highly conserved from bacteria to humans. Prokaryote genomes, including a wide array of both Gram-negative bacteria and Gram-positive bacteria, typically encode one Hint gene. The cellular function of Hint and the rationale for its evolutionary conservation in bacteria have remained a mystery. Despite its ubiquity and high sequence similarity to eukaryote Hint1 [Escherichia coli Hint (echinT) is 48% identical with human Hint1], prokaryote Hint has been reported in only a few studies. Here we report the first conformational information on the full-length N-terminal and C-terminal residues of Hint from the E. coli complex with GMP. Structural analysis of the echinT-GMP complex reveals that it crystallizes in the monoclinic space group P2{sub 1} with four homodimers in the asymmetric unit. Analysis of electron density for both the N-terminal residues and the C-terminal residues of the echinT-GMP complex indicates that the loops in some monomers can adopt more than one conformation. The observation of conformational flexibility in terminal loop regions could explain the presence of multiple homodimers in the asymmetric unit of this structure. To explore the impact of the echinT C-terminus on protein structure and catalysis, we conducted a series of catalytic radiolabeling and kinetic experiments on the C-terminal deletion mutants of echinT. In this study, we show that sequential deletion of the C-terminus likely has no effect on homodimerization and a modest effect on the secondary structure of echinT. However, we observed a significant impact on the folding structure, as reflected by a significant lowering of the T{sub m} value. Kinetic analysis reveals that the C-terminal deletion mutants are within an order of magnitude less efficient in catalysis compared to wild type, while the overall kinetic mechanism that proceeds through a fast step, followed by a rate-limiting hydrolysis step, was conserved. Nevertheless, the ability of the C-terminal deletion mutants to hydrolyze lysyl-AMP generated by LysU was greatly impaired. Taken together, our results highlight the emerging role of the C-terminus in governing the catalytic function of Hints.

  16. MOLYBDENUM, RUTHENIUM, AND THE HEAVY r-PROCESS ELEMENTS IN MODERATELY METAL-POOR MAIN-SEQUENCE TURNOFF STARS

    SciTech Connect (OSTI)

    Peterson, Ruth C. [Astrophysical Advances, 607 Marion Place, Palo Alto, CA 94301 (United States)

    2013-05-01T23:59:59.000Z

    The ratios of elemental abundances observed in metal-poor stars of the Galactic halo provide a unique present-day record of the nucleosynthesis products of its earliest stars. While the heaviest elements were synthesized by the r- and s-processes, dominant production mechanisms of light trans-ironic elements were obscure until recently. This work investigates further our 2011 conclusion that the low-entropy regime of a high-entropy wind (HEW) produced molybdenum and ruthenium in two moderately metal-poor turnoff stars that showed extreme overabundances of those elements with respect to iron. Only a few, rare nucleosynthesis events may have been involved. Here we determine abundances for Mo, Ru, and other trans-Fe elements for 28 similar stars by matching spectral calculations to well-exposed near-UV Keck HIRES spectra obtained for beryllium abundances. In each of the 26 turnoff stars with Mo or Ru line detections and no evidence for s-process production (therefore old), we find Mo and Ru to be three to six times overabundant. In contrast, the maximum overabundance is reduced to factors of three and two for the neighboring elements zirconium and palladium. Since the overproduction peaks sharply at Mo and Ru, a low-entropy HEW is confirmed as its origin. The overabundance level of the heavy r-process elements varies significantly, from none to a factor of four, but is uncorrelated with Mo and Ru overabundances. Despite their moderate metallicity, stars in this group trace the products of different nucleosynthetic events: possibly very few events, possibly events whose output depended on environment, metallicity, or time.

  17. Development of empirical potential functions for the study of molecular geometry, and applications to chlorophyll a dimers. [Dissertation

    SciTech Connect (OSTI)

    Oie, Tetsuro

    1980-01-01T23:59:59.000Z

    A purpose of the present studies is twofold: (1) development of an empirical potential function (EPF) and (2) application of it to the studies of photoreaction center chlorophyll a dimer. The reliable estimate of geometric structures and energies of large molecules by quantum mechanical methods is not possible at the present time. An alternative method is, therefore, needed for the studies of large molecular systems, and Chapter I is dedicated to the development of this tool, i.e., an empirical potential function, which could suffice this purpose. Because of a large number of variable chemical compositions and functional groups characteristically present in a large molecule, it is important to include a large number of structurally diverse molecules in the development of the EPF. In Chapter II, the EPF is applied to study the geometrical structure of a chlorophyll a (Chl a) dimer, which is believed to exist at the photoreaction center of green plants and is known to play an essential role in photosynthetic energy conversion. Although various models have been proposed for this dimer structure, there is still a great need for information concerning the detailed geometric structure of this dimer. Therefore, in this chapter the structural stabilities of various dimer models are examined by the EPF, and detailed and quantitative information on the structure and stability of these models is provided.

  18. The retroviral RNA dimer linkage: different structures may reflect different roles

    E-Print Network [OSTI]

    Greatorex, Jane S

    2004-08-18T23:59:59.000Z

    's Hospital, Hills Road, Cambridge, CB2 2QQ, UK Email: Jane Greatorex* - jg10018@mole.bio.cam.ac.uk * Corresponding author Abstract Retroviruses are unique among virus families in having dimeric genomes. The RNA sequences and structures that link the two... stem-loop H1 (278–303) and new roles for stem-loops H2 (310–352) and H3 (355–374). Biochem-Page 8 of 10 (page number not for citation purposes) istry 1998, 37:6077-6085. 23. Rasmussen SV, Mikkelsen JG, Pedersen FS: Modulation of homo...

  19. Spectroscopic accuracy directly from quantum chemistry: application to ground and excited states of beryllium dimer

    E-Print Network [OSTI]

    Sharma, Sandeep; Booth, George H; Umrigar, C J; Chan, Garnet Kin-Lic

    2014-01-01T23:59:59.000Z

    We combine explicit correlation via the canonical transcorrelation approach with the density matrix renormalization group and initiator full configuration interaction quantum Monte Carlo methods to compute a near-exact beryllium dimer curve, {\\it without} the use of composite methods. In particular, our direct density matrix renormalization group calculations produce a well-depth of $D_e$=931.2 cm$^{-1}$ which agrees very well with recent experimentally derived estimates $D_e$=929.7$\\pm 2$~cm$^{-1}$ [Science, 324, 1548 (2009)] and $D_e$=934.6~cm$^{-1}$ [Science, 326, 1382 (2009)

  20. Covalent features in the hydrogen bond of a water dimer: molecular orbital analysis

    E-Print Network [OSTI]

    Wang, Bo; Dai, Xing; Gao, Yang; Wang, Zhigang; Zhang, Rui-Qin

    2015-01-01T23:59:59.000Z

    The covalent-like characteristics of hydrogen bonds offer a new perspective on intermolecular interactions. Here, using density functional theory and post-Hartree-Fock methods, we reveal that there are two bonding molecular orbitals (MOs) crossing the O and H atoms of the hydrogen-bond in water dimer. Energy decomposition analysis also shows a non-negligible contribution of the induction term. These results illustrate the covalent-like character of the hydrogen bond between water molecules, which contributes to the essential understanding of ice, liquid water, related materials, and life sciences.

  1. Hydrogen atom trapping in a self-organized one-dimensional dimer

    SciTech Connect (OSTI)

    Takami, Tsuyoshi, E-mail: takami@phys.sci.osaka-u.ac.jp [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan); Kawamura, Kazushi [Analytical Measurement Room, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)

    2014-09-01T23:59:59.000Z

    Metal–organic frameworks (MOFs) have attracted widespread attention owing to their unusual structure and properties produced by their nanospaces. However, many MOFs possess the similar three-dimensional frameworks, limiting their structural variety and operating capacity for hydrogen storage under ambient conditions. Here we report the synthesis and structural characterization of a single-crystal one-dimensional dimer whose structure, operating capacity, and physical mechanism contrast with those of existing MOFs. The hydrogen storage capacity of 2.6 wt.% is comparable to the highest capacity achieved by existing MOFs at room temperature. This exceptional storage capacity is realized by self-organization during crystal growth using a weak base.

  2. Synergistic Catalysis between Pd and Fe in Gas Phase Hydrodeoxygenation of m-Cresol

    SciTech Connect (OSTI)

    Hong, Yongchun; Zhang, He; Sun, Junming; Karim, Ayman M.; Hensley, Alyssa; Gu, Meng; Engelhard, Mark H.; McEwen, Jean-Sabin; Wang, Yong

    2014-10-31T23:59:59.000Z

    In this work, a series of Pd/Fe2O3 catalysts were synthesized, characterized, and evaluated for the hydrodeoxygenation (HDO) of m-cresol. It was found that the addition of Pd remarkably promotes the catalytic activity of Fe while the product distributions resemble that of monometallic Fe catalyst, showing high selectivity towards the production of toluene (C-O cleavage without saturation of aromatic ring and C-C cleavage). Reduced catalysts featured with Pd patches on the top of reduced Fe nanoparticle surface, and the interaction between Pd and Fe was further confirmed using X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM) and X-ray absorption near edge fine structure (XANES). A possible mechanism, including Pd assisted H2 dissociation and Pd facilitated stabilization of metallic Fe surface as well as Pd enhanced product desorption, is proposed to be responsible for the high activity and HDO selectivity in Pd-Fe catalysts. The synergic catalysis derived from Pd-Fe interaction found in this work was proved to be applicable to other precious metal promoted Fe catalysts, providing a promising strategy for future design of highly active and selective HDO catalysts.

  3. Catalysis Center for Energy Innovation for Biomass Processing: Research Strategies and Goals

    SciTech Connect (OSTI)

    Vlachos, Dion G.; Chen, Jingguang; Gorte, R. J.; Huber, George W.; Tsapatsis, Michael

    2010-01-01T23:59:59.000Z

    Production of energy and chemicals from biomass is of critical importance in meeting some of the challenges associated with decreasing availability of fossil fuels and addressing global climate change. In the current article, we outline a perspective on key challenges of biomass processing. We also introduce the Catalysis Center for Energy Innovation (CCEI), one of the 46 Energy Frontier Research Centers established by the Department of Energy in the spring of 2009, and CCEI’s overall research strategies and goals along with its cross-cutting research thrusts that can enable potential technological breakthroughs in the utilization of biomass and its derivatives. The center focuses on developing innovative heterogeneous catalysts and processing schemes that can lead to viable biorefineries for the conversion of biomass to chemicals, fuels, and electricity. In order to achieve this goal, a group of over twenty faculty members from nine institutions has been assembled to bring together complementary expertise covering novel materials synthesis, advanced characterization, multiscale modeling, surface science, catalytic kinetics, and microreactors.

  4. Steam catalysis in CaO carbonation under low steam partial pressure

    SciTech Connect (OSTI)

    Yang, S.J.; Xiao, Y.H. [Chinese Academy of Science, Beijing (China)

    2008-06-15T23:59:59.000Z

    CaO was widely used to capture CO{sub 2} in direct hydrogen production process, where steam always existed simultaneously. The effect of steam on CaO carbonation performance under low steam partial pressure was investigated using a pressurized thermogravimetric apparatus. The experimental results revealed that steam improved CaO carbonation performance significantly no matter whether Ca(OH){sub 2} was produced or not. At 823 K and 0.5 MPa of steam partial pressure, effect of steam on CaO carbonation performance could not be attributed mainly to production of Ca(OH){sub 2} because the hydration rate of CaO was very slow. The main reason was steam catalysis in CaO carbonation. Enhancement of steam on CaO carbonation performance without Ca(OH){sub 2} production could not be attributed to improvement of steam on the physical property, but to catalytic effect of steam. Effects of CaO precursors, CO{sub 2} partial pressure, steam partial pressure, and temperature with steam addition on CaO carbonation performance were also investigated.

  5. Molecular Insights into Substrate Recognition and Catalysis by Tryptophan 2,3-dioxygenase

    SciTech Connect (OSTI)

    Forouhar,F.; Ross Anderson, J.; Mowat, C.; Vorobiev, S.; Hussain, A.; Abashidze, M.; Bruckmann, C.; Thackray, S.; Seetharaman, J.; et al.

    2007-01-01T23:59:59.000Z

    Tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO) constitute an important, yet relatively poorly understood, family of heme-containing enzymes. Here, we report extensive structural and biochemical studies of the Xanthomonas campestris TDO and a related protein SO4414 from Shewanella oneidensis, including the structure at 1.6-{angstrom} resolution of the catalytically active, ferrous form of TDO in a binary complex with the substrate l-Trp. The carboxylate and ammonium moieties of tryptophan are recognized by electrostatic and hydrogen-bonding interactions with the enzyme and a propionate group of the heme, thus defining the l-stereospecificity. A second, possibly allosteric, l-Trp-binding site is present at the tetramer interface. The sixth coordination site of the heme-iron is vacant, providing a dioxygen-binding site that would also involve interactions with the ammonium moiety of l-Trp and the amide nitrogen of a glycine residue. The indole ring is positioned correctly for oxygenation at the C2 and C3 atoms. The active site is fully formed only in the binary complex, and biochemical experiments confirm this induced-fit behavior of the enzyme. The active site is completely devoid of water during catalysis, which is supported by our electrochemical studies showing significant stabilization of the enzyme upon substrate binding.

  6. Magnetic coupling in neutral and charged Cr{sub 2}, Mn{sub 2}, and CrMn dimers

    SciTech Connect (OSTI)

    Desmarais, N. [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland)] [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland); Reuse, F. A. [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland)] [Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, CH-1015 Lausanne, (Switzerland); Khanna, S. N. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)

    2000-04-01T23:59:59.000Z

    Theoretical ab initio studies of neutral, cationic and anionic Cr{sub 2}, Mn{sub 2}, and CrMn dimers have been carried out to explore the progression of magnetic coupling with the number of electrons. It is shown that while Cr{sub 2} and Cr{sub 2}{sup -} have antiferromagnetically coupled atomic spins, Cr{sub 2}{sup +} has a ferromagnetic ground state closely followed by an antiferromagnetic state. On the other hand, all Mn{sub 2} dimers are ferromagnetic, irrespective of the charge. The neutral CrMn is ferrimagnetic while the charged CrMn are antiferromagnetic. In all cases, the charged dimers are found to be more stable than the neutral ones. The results are compared with available calculations and experiments and the difficulties associated with theoretical description and the experimental interpretations are discussed. (c) 2000 American Institute of Physics.

  7. Electrochemical investigations of polymer films and monolayers on electrode surfaces: Determination of the reaction entropy for Os(bpy)[sub 3][sup 3+/2+] in nafion, and the influence of supporting electrolyte activity on the formal potential of a monolayer containing a ruthenium redox center, and, Synthesis and characterization of monometallic and bimetallic complexes of ruthenium(II) and iron(II) with 4,4[prime]bipyrimidine (4,4[prime]BPM) and pyridyl viologen (PV[sup 2+])

    SciTech Connect (OSTI)

    Tunison, H.M.

    1992-01-01T23:59:59.000Z

    This thesis is comprised of two major projects: An analytical project and an inorganic synthesis project. The first project dealt with the investigation of the electrochemistry of thin polymer films and monolayers on electrode surfaces. The second project dealt with the synthesis of novel monometallic and bimetallic complexes of ruthenium and iron in which the metals were bridged by either 4, 4[prime] bipyrimidine or pyridyl viologen. The first project involved the investigation of the reaction entropy for a redox couple which had been exchanged into an ion-exchange polymer on an electrode surface. The measured values for the reaction entropy were shown to be dominated by the entropy change for partitioning the redox couple into the film and by supporting electrolyte cation transfer between the film and the polymer. Electrochemical studies were also carried out on an alkanethiol monolayer which contained a ruthenium redox center at the monolayer/solution interface. The electrochemistry supported the fact that the monolayer was displaying permselective behavior with the exclusion of supporting electrolyte cations from the monolayer. Equations were presented that described the electrochemical nature of the monolayer and the dependence of the formal potential for the monolayer on the supporting electrolyte cation transfer at the monolayer/solution interface. The second section of the thesis dealt with the synthesis and characterization of a number of novel ruthenium and iron complexes utilizing 4,4[prime] bipyrimidine and pyridyl viologen. The complexes show shifts in the energy of the MLCT bands and reduction potentials which can be correlated to either the reduction potential of the ligand involved in the complex or the relationship between iron and ruthenium in the group VIII family. Comparisons are made between the complexes studied and a number of ruthenium and iron complexes of nitrogen heterocycles from the literature.

  8. Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

    DOE Patents [OSTI]

    Smith, L.A. Jr.; Jones, E.M. Jr.; Hearn, D.

    1984-05-08T23:59:59.000Z

    Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150 to 250 F at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C[sub 3] to C[sub 6] and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom. 2 figs.

  9. Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

    DOE Patents [OSTI]

    Smith, Jr., Lawrence A. (Bellaire, TX); Jones, Jr., Edward M. (Friendswood, TX); Hearn, Dennis (Houston, TX)

    1984-01-01T23:59:59.000Z

    Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150.degree. to 250.degree. F. at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C.sub.3 to C.sub.6 and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom.

  10. Computational Mechanistic Studies of Acid-Catalyzed Lignin Model Dimers for Lignin Depolymerization

    SciTech Connect (OSTI)

    Kim, S.; Sturgeon, M. R.; Chmely, S. C.; Paton, R. S.; Beckham, G. T.

    2013-01-01T23:59:59.000Z

    Lignin is a heterogeneous alkyl-aromatic polymer that constitutes up to 30% of plant cell walls, and is used for water transport, structure, and defense. The highly irregular and heterogeneous structure of lignin presents a major obstacle in the development of strategies for its deconstruction and upgrading. Here we present mechanistic studies of the acid-catalyzed cleavage of lignin aryl-ether linkages, combining both experimental studies and quantum chemical calculations. Quantum mechanical calculations provide a detailed interpretation of reaction mechanisms including possible intermediates and transition states. Solvent effects on the hydrolysis reactions were incorporated through the use of a conductor-like polarizable continuum model (CPCM) and with cluster models including explicit water molecules in the first solvation shell. Reaction pathways were computed for four lignin model dimers including 2-phenoxy-phenylethanol (PPE), 1-(para-hydroxyphenyl)-2-phenoxy-ethanol (HPPE), 2-phenoxy-phenyl-1,3-propanediol (PPPD), and 1-(para-hydroxyphenyl)-2-phenoxy-1,3-propanediol (HPPPD). Lignin model dimers with a para-hydroxyphenyl ether (HPPE and HPPPD) show substantial differences in reactivity relative to the phenyl ether compound (PPE and PPPD) which have been clarified theoretically and experimentally. The significance of these results for acid deconstruction of lignin in plant cell walls will be discussed.

  11. Structural and mechanistic insights into cooperative assembly of dimeric Notch transcription complexes

    SciTech Connect (OSTI)

    Arnett, Kelly L.; Hass, Matthew; McArthur, Debbie G.; Ilagan, Ma Xenia G.; Aster, Jon C.; Kopan, Raphael; Blacklow, Stephen C. (WU); (BWH); (DFCI)

    2010-11-12T23:59:59.000Z

    Ligand-induced proteolysis of Notch produces an intracellular effector domain that transduces essential signals by regulating the transcription of target genes. This function relies on the formation of transcriptional activation complexes that include intracellular Notch, a Mastermind co-activator and the transcription factor CSL bound to cognate DNA. These complexes form higher-order assemblies on paired, head-to-head CSL recognition sites. Here we report the X-ray structure of a dimeric human Notch1 transcription complex loaded on the paired site from the human HES1 promoter. The small interface between the Notch ankyrin domains could accommodate DNA bending and untwisting to allow a range of spacer lengths between the two sites. Cooperative dimerization occurred on the human and mouse Hes5 promoters at a sequence that diverged from the CSL-binding consensus at one of the sites. These studies reveal how promoter organizational features control cooperativity and, thus, the responsiveness of different promoters to Notch signaling.

  12. Structural, Spectroscopic, And Theoretical Elucidation of a Redox-Active Pincer-Type Ancillary Applied in Catalysis

    SciTech Connect (OSTI)

    Adhikari, D.; Mossin, S.; Basuli, F.; Huffman, J.C.; Szilagyi, R.K.; Meyer, K.; Mindiola, D.J.

    2009-05-11T23:59:59.000Z

    Pincer-type ligands are believed to be very robust scaffolds that can support multifarious functionalities as well as highly reactive metal motifs applied in organometallic chemistry, especially in the realm of catalysis. In this paper, we describe the redox and, therefore, noninnocent behavior of a PNP (PNP{sup -} = N[2-P(CHMe{sub 2}){sub 2}-4-methylphenyl]{sub 2}) pincer ancillary bound to nickel. A combination of structural, spectroscopic, and theoretical techniques suggests that this type of framework can house an electron hole when coordinated to Ni(II).

  13. Structure, Vol. 10, 673686, May, 2002, 2002 Elsevier Science Ltd. All rights reserved. PII S0969-2126(02)00758-X The Domain-Swapped Dimer of Cyanovirin-N Is

    E-Print Network [OSTI]

    Institute NCI-Frederick Here we report on studies concerning the domain- swapped dimer formed by the potent-2126(02)00758-X The Domain-Swapped Dimer of Cyanovirin-N Is in a Metastable Folded State: Reconciliation of X-Ray and NMR Structures classical example for a domain-swapped dimer is bo- vine pancreatic ribonuclease

  14. Ultralow-power local laser control of the dimer density in alkali-metal vapors through photodesorption

    E-Print Network [OSTI]

    Pankaj K. Jha; Konstantin E. Dorfman; Zhenhuan Yi; Luqi Yuan; Vladimir A. Sautenkov; Yuri V. Rostovtsev; George R. Welch; Aleksei M. Zheltikov; Marlan O. Scully

    2012-10-08T23:59:59.000Z

    Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.

  15. Inhibition of Caspase-9 by Stabilized Peptides Targeting the Dimerization Kristen L. Huber, Sumana Ghosh,* Jeanne A. Hardy

    E-Print Network [OSTI]

    Hardy, Jeanne

    . Huber, Sumana Ghosh,* Jeanne A. Hardy Department of Chemistry, University of Massachusetts Amherst is through caspase regulation. The cas- pases are cysteine aspartate proteases known to propagate apo- ptosis Targeting the Dimerization Interface Correspondence to: Jeanne A. Hardy, University of Massachusetts Amherst

  16. Phase transition between quantum and classical regimes for the escape rate of dimeric molecular nanomagnets in a staggered magnetic field

    E-Print Network [OSTI]

    Solomon Akaraka Owerre; M. B Paranjape

    2014-07-02T23:59:59.000Z

    We study the phase transition of the escape rate of exchange-coupled dimer of single-molecule magnets which are coupled either ferromagnetic ally or antiferromagnetically in a staggered magnetic field and an easy $z$-axis anisotropy. The Hamiltonian for this system has been used to study molecular dimer nanomagnets [Mn$_4$]$_2$. We generalize the method of mapping a single-molecule magnetic spin problem onto a quantum-mechanical particle to dimeric molecular nanomagnets. The problem is mapped to a single particle quantum-mechanical Hamiltonian in terms of the relative coordinate and a coordinate dependent reduced mass. It is shown that the presence of the external staggered magnetic field creates a phase boundary separating the first- from the second-order transition. With the set of parameters used by R. Tiron, $\\textit{et al}$, \\prl {\\bf 91}, 227203 (2003), and S. Hill, $\\textit{et al}$ science {\\bf 302}, 1015 (2003) to fit experimental data for [Mn$_{4}$]$_2$ dimer we find that the critical temperature at the phase boundary is $T^{(c)}_0 =0.29K$. Therefore, thermally activated transitions should occur for temperatures greater than $T^{(c)}_0$.

  17. Investigation of the release of Si from SiO{sub 2} during the formation of manganese/ruthenium barrier layers

    SciTech Connect (OSTI)

    McCoy, A. P.; Casey, P.; Bogan, J.; Byrne, C.; Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)] [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2013-05-20T23:59:59.000Z

    The thermodynamic and structural stability of ruthenium-manganese diffusion barriers on SiO{sub 2} is assessed. A {approx}2 nm film composed of partially oxidized manganese (MnO{sub x} where x < 1) was deposited on a 3 nm thick Ru film and the Mn-MnO{sub x}/Ru/SiO{sub 2} structure was subsequently thermally annealed. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy studies suggest the release and upward diffusion of Si from the dielectric substrate as a result of manganese-silicate formation at the Ru/SiO{sub 2} interface. The migration of Si up through the Ru film results in further manganese-silicate formation upon its interaction with the Mn-MnO{sub x} deposited layer.

  18. Fermion-dimer scattering using an impurity lattice Monte Carlo approach and the adiabatic projection method

    E-Print Network [OSTI]

    Serdar Elhatisari; Dean Lee

    2014-12-01T23:59:59.000Z

    We present lattice Monte Carlo calculations of fermion-dimer scattering in the limit of zero-range interactions using the adiabatic projection method. The adiabatic projection method uses a set of initial cluster states and Euclidean time projection to give a systematically improvable description of the low-lying scattering cluster states in a finite volume. We use L\\"uscher's finite-volume relations to determine the s-wave, p-wave, and d-wave phase shifts. For comparison, we also compute exact lattice results using Lanczos iteration and continuum results using the Skorniakov-Ter-Martirosian equation. For our Monte Carlo calculations we use a new lattice algorithm called impurity lattice Monte Carlo. This algorithm can be viewed as a hybrid technique which incorporates elements of both worldline and auxiliary-field Monte Carlo simulations.

  19. Quantum Non-Demolition Detection of Polar Molecule Complexes: Dimers, Trimers, Tetramers

    E-Print Network [OSTI]

    Mekhov, Igor B

    2011-01-01T23:59:59.000Z

    The optical nondestructive method for in situ detection of the bound states of ultracold polar molecules is developed. It promises a minimally destructive measurement scheme up to a physically exciting quantum non-demolition (QND) level. The detection of molecular complexes beyond simple pairs of quantum particles (dimers, known, e.g., from the BEC-BCS theory) is suggested, including three-body (trimers) and four-body (tertramers) complexes trapped by one-dimensional tubes. The intensity of scattered light is sensitive to the molecule number fluctuations beyond the mean-density approximation. Such fluctuations are very different for various complexes, which leads to radically different light scattering. This type of research extends "quantum optics of quantum gases" to the field of ultracold molecules. Merging the quantum optical and ultracold gas problems will advance the experimental efforts towards the study of the light-matter interaction at its ultimate quantum level, where the quantizations of both ligh...

  20. Structure of a Longitudinal Actin Dimer Assembled by Tandem W Domains: Implications for Actin Filament Nucleation

    SciTech Connect (OSTI)

    Rebowski, Grzegorz; Namgoong, Suk; Boczkowska, Malgorzata; Leavis, Paul C.; Navaza, Jorge; Dominguez, Roberto (IBS) [IBS; (BBRI); (UPENN-MED)

    2013-11-20T23:59:59.000Z

    Actin filament nucleators initiate polymerization in cells in a regulated manner. A common architecture among these molecules consists of tandem WASP homology 2 domains (W domains) that recruit three to four actin subunits to form a polymerization nucleus. We describe a low-resolution crystal structure of an actin dimer assembled by tandem W domains, where the first W domain is cross-linked to Cys374 of the actin subunit bound to it, whereas the last W domain is followed by the C-terminal pointed end-capping helix of thymosin {beta}4. While the arrangement of actin subunits in the dimer resembles that of a long-pitch helix of the actin filament, important differences are observed. These differences result from steric hindrance of the W domain with intersubunit contacts in the actin filament. We also determined the structure of the first W domain of Vibrio parahaemolyticus VopL cross-linked to actin Cys374 and show it to be nearly identical with non-cross-linked W-Actin structures. This result validates the use of cross-linking as a tool for the study of actin nucleation complexes, whose natural tendency to polymerize interferes with most structural methods. Combined with a biochemical analysis of nucleation, the structures may explain why nucleators based on tandem W domains with short inter-W linkers have relatively weak activity, cannot stay bound to filaments after nucleation, and are unlikely to influence filament elongation. The findings may also explain why nucleation-promoting factors of the Arp2/3 complex, which are related to tandem-W-domain nucleators, are ejected from branch junctions after nucleation. We finally show that the simple addition of the C-terminal pointed end-capping helix of thymosin {beta}4 to tandem W domains can change their activity from actin filament nucleation to monomer sequestration.

  1. Improved Modeling of Transition Metals, Applications to Catalysis and Technetium Chemistry

    SciTech Connect (OSTI)

    Cundari, T. R.

    2004-03-05T23:59:59.000Z

    There is considerable impetus for identification of aqueous OM catalysts as water is the ultimate ''green'' solvent. In collaboration with researchers at Ames Lab, we investigated effective fragment and Monte Carlo techniques for aqueous-phase hydroformylation (HyF). The Rh of the HyF catalyst is weakly aquated, in contrast to the hydride of the Rh-H bond. As the insertion of the olefin C=C into Rh-H determines the linear-to-branched aldehyde ratio, it is reasonable to infer that solvent plays an important role in regiochemistry. Studies on aqueous-phase organometallic catalysis were complemented in studies of the gas-phase reaction. A Rh-carbonyl-phosphine catalyst was investigated. Two of the most important implications of this research include (a) pseudorotation among five-coordinate intermediates is significant in HyF, and (b) CO insertion is the rate-determining step. The latter is in contrast to experimental deductions, highlighting the need for more accurate modeling. To this end, we undertook studies of (a) experimentally relevant PR{sub 3} co-ligands (PMe{sub 3}, PPh{sub 3}, P(p-PhSO{sub 3{sup -}}){sub 3}, etc.), and (b) HyF of propene. For the propylene research, simulations indicated that the linear: branched aldehyde ratio (linear is more desirable) is determined by thermodynamic discrimination of two distinct pathways. Other projects include a theory-experiment study of C-H activation by early transition metal systems, which establishes that weakly-bound adducts play a key role in activity selectivity. By extension, more selective catalysts for functionalization of methane (major component of natural gas) will require better understanding of these adducts, which are greatly affected by steric interactions with the ligands. In the de novo design of Tc complexes, we constructed (and are now testing) a coupled quantum mechanics-molecular mechanics protocol. Initial research shows it to be capable of accurately predicting structure ''from scratch.'' Challenges include conformational, geometric, coordination, spin, and particularly linkage (e.g., Tc-SCN versus Tc-NCS) isomerism. In general, our protocol can rapidly (<1 day with desktop software/hardware) predict the structure of diverse Tc complexes with an accuracy commensurate to organics. Our de novo strategy is also being used to investigate tris-pyrazolyl borate (Tp) complexes. Data suggests a fundamental difference in methane activation between TpRe and related CpRe complexes. Furthermore, Tp is a more electronically ''flexible'' platform for catalysts modification than Cp.

  2. SELECTIVE REDUCTION OF NOX IN OXYGEN RICH ENVIRONMENTS WITH PLASMA-ASSISTED CATALYSIS: CATALYST DEVELOPMENT AND MECHANISTIC STUDIES

    SciTech Connect (OSTI)

    Peden, C; Barlow, S; Hoard, J; Kwak, J; *Balmer-Millar, M; *Panov, A; Schmieg, S; Szanyi, J; Tonkyn, R

    2003-08-24T23:59:59.000Z

    The control of NOx (NO and NO2) emissions from so-called ''lean-burn'' vehicle engines remains a challenge. In recent years, there have been a number of reports that show that a plasma device combined with a catalyst can reduce as high as 90% or more of NOx in simulated diesel and other ''lean-burn'' exhaust. In the case of propylene containing simulated diesel exhaust, the beneficial role of a plasma treatment is now thought to be due to oxidation of NO to NO2, and the formation of partially oxidized hydrocarbons that are more active for the catalytic reduction of NO2 than propylene. Thus, the overall system can be most usefully described as hydrocarbon selective catalytic reduction (SCR) enhanced by 'reforming' the exhaust with a non-thermal plasma (NTP) device. For plasma-enhanced catalysis, both zeolite- and alumina-based materials have shown high activity, albeit in somewhat different temperature ranges, when preceded by an NTP reactor. This paper will briefly describe our research efforts aimed at optimizing the catalyst materials for NTP-catalysis devices based, in part, on our continuing studies of the NTP- and catalytic-reaction mechanisms. Various alkali- and alkaline earth-cation-exchanged Y zeolites have been prepared, their material properties characterized, and they have been tested as catalytic materials for NOx reduction in laboratory NTP-catalysis reactors. Interestingly, NO2 formed in the plasma and not subsequently removed over these catalysts, will back-convert to NO, albeit to varying extents depending upon the nature of the cation. Besides this comparative reactivity, we will also discuss selected synthesis strategies for enhancing the performance of these zeolite-based catalyst materials. A particularly important result from our mechanistic studies is the observation that aldehydes, formed during the plasma treatment of simulated diesel exhaust, are the important species for the reduction of NOx to N2. Indeed, acetaldehyde has been found to be especially effective in the thermal reduction of both NO and NO2 over Ba- and Na-Y zeolite catalysts.

  3. Structural studies of polypeptides: Mechanism of immunoglobin catalysis and helix propagation in hybrid sequence, disulfide containing peptides

    SciTech Connect (OSTI)

    Storrs, R.W.

    1992-08-01T23:59:59.000Z

    Catalytic immunoglobin fragments were studied Nuclear Magnetic Resonance spectroscopy to identify amino acid residues responsible for the catalytic activity. Small, hybrid sequence peptides were analyzed for helix propagation following covalent initiation and for activity related to the protein from which the helical sequence was derived. Hydrolysis of p-nitrophenyl carbonates and esters by specific immunoglobins is thought to involve charge complementarity. The pK of the transition state analog P-nitrophenyl phosphate bound to the immunoglobin fragment was determined by [sup 31]P-NMR to verify the juxtaposition of a positively charged amino acid to the binding/catalytic site. Optical studies of immunoglobin mediated photoreversal of cis, syn cyclobutane thymine dimers implicated tryptophan as the photosensitizing chromophore. Research shows the chemical environment of a single tryptophan residue is altered upon binding of the thymine dimer. This tryptophan residue was localized to within 20 [Angstrom] of the binding site through the use of a nitroxide paramagnetic species covalently attached to the thymine dimer. A hybrid sequence peptide was synthesized based on the bee venom peptide apamin in which the helical residues of apamin were replaced with those from the recognition helix of the bacteriophage 434 repressor protein. Oxidation of the disufide bonds occured uniformly in the proper 1-11, 3-15 orientation, stabilizing the 434 sequence in an [alpha]-helix. The glycine residue stopped helix propagation. Helix propagation in 2,2,2-trifluoroethanol mixtures was investigated in a second hybrid sequence peptide using the apamin-derived disulfide scaffold and the S-peptide sequence. The helix-stop signal previously observed was not observed in the NMR NOESY spectrum. Helical connectivities were seen throughout the S-peptide sequence. The apamin/S-peptide hybrid binded to the S-protein (residues 21-166 of ribonuclease A) and reconstituted enzymatic activity.

  4. Structural studies of polypeptides: Mechanism of immunoglobin catalysis and helix propagation in hybrid sequence, disulfide containing peptides

    SciTech Connect (OSTI)

    Storrs, R.W.

    1992-08-01T23:59:59.000Z

    Catalytic immunoglobin fragments were studied Nuclear Magnetic Resonance spectroscopy to identify amino acid residues responsible for the catalytic activity. Small, hybrid sequence peptides were analyzed for helix propagation following covalent initiation and for activity related to the protein from which the helical sequence was derived. Hydrolysis of p-nitrophenyl carbonates and esters by specific immunoglobins is thought to involve charge complementarity. The pK of the transition state analog P-nitrophenyl phosphate bound to the immunoglobin fragment was determined by {sup 31}P-NMR to verify the juxtaposition of a positively charged amino acid to the binding/catalytic site. Optical studies of immunoglobin mediated photoreversal of cis, syn cyclobutane thymine dimers implicated tryptophan as the photosensitizing chromophore. Research shows the chemical environment of a single tryptophan residue is altered upon binding of the thymine dimer. This tryptophan residue was localized to within 20 {Angstrom} of the binding site through the use of a nitroxide paramagnetic species covalently attached to the thymine dimer. A hybrid sequence peptide was synthesized based on the bee venom peptide apamin in which the helical residues of apamin were replaced with those from the recognition helix of the bacteriophage 434 repressor protein. Oxidation of the disufide bonds occured uniformly in the proper 1-11, 3-15 orientation, stabilizing the 434 sequence in an {alpha}-helix. The glycine residue stopped helix propagation. Helix propagation in 2,2,2-trifluoroethanol mixtures was investigated in a second hybrid sequence peptide using the apamin-derived disulfide scaffold and the S-peptide sequence. The helix-stop signal previously observed was not observed in the NMR NOESY spectrum. Helical connectivities were seen throughout the S-peptide sequence. The apamin/S-peptide hybrid binded to the S-protein (residues 21-166 of ribonuclease A) and reconstituted enzymatic activity.

  5. Heat capacity of the site-diluted spin dimer system Ba?(Mn1-xVx)?O?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Samulon, E. C.; Shapiro, M. C.; Fisher, I. R.

    2011-08-01T23:59:59.000Z

    Heat-capacity and susceptibility measurements have been performed on the diluted spin dimer compound Ba?(Mn1-xVx)?O?. The parent compound Ba?Mn?O? is a spin dimer system based on pairs of antiferromagnetically coupled S=1, 3d² Mn?? ions such that the zero-field ground state is a product of singlets. Substitution of nonmagnetic S=0, 3d? V?? ions leads to an interacting network of unpaired Mn moments, the low-temperature properties of which are explored in the limit of small concentrations 0?x?0.05. The zero-field heat capacity of this diluted system reveals a progressive removal of magnetic entropy over an extended range of temperatures, with no evidence for a phase transition. The concentration dependence does not conform to expectations for a spin-glass state. Rather, the data suggest a low-temperature random singlet phase, reflecting the hierarchy of exchange energies found in this system.

  6. Solution of the associative mean spherical approximation for a multicomponent dimerizing hard-sphere multi-Yukawa fluid

    SciTech Connect (OSTI)

    Kalyuzhnyi, Yu. V. [Institute for Condensed Matter Physics, Svientsitskoho 1, 290011 Lviv, (Ukraine)] [Institute for Condensed Matter Physics, Svientsitskoho 1, 290011 Lviv, (Ukraine); Blum, L. [Department of Physics, University of Puerto Rico, Rio Piedras, Puerto Rico 00931 (Puerto Rico)] [Department of Physics, University of Puerto Rico, Rio Piedras, Puerto Rico 00931 (Puerto Rico); Rescic, J. [Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1001 Ljubljana, (Slovenia)] [Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1001 Ljubljana, (Slovenia); Stell, G. [Department of Chemistry, State University of New York at Stony Brook, New York 11794-3400 (United States)] [Department of Chemistry, State University of New York at Stony Brook, New York 11794-3400 (United States)

    2000-07-15T23:59:59.000Z

    The analytical solution of the associative mean spherical approximation (AMSA) for a Yukawa dimerizing multicomponent hard-sphere fluid is derived. The general multi-Yukawa case is discussed. The simpler one-Yukawa case with factorizable coefficients is explicitly solved. As in the previously discussed electrolyte case the solution of the AMSA reduces to the solution of only one nonlinear algebraic equation for the scaling parameter {gamma}{sup B}. The analytical results for the AMSA closure is illustrated by numerical examples and computer simulation for the one-component one-Yukawa dimerizing fluid. Good agreement between theoretical and computer simulation results was found for both the thermodynamic properties and the structure of the system. (c) 2000 American Institute of Physics.

  7. Communication: Towards the binding energy and vibrational red shift of the simplest organic hydrogen bond: Harmonic constraints for methanol dimer

    SciTech Connect (OSTI)

    Heger, Matthias; Suhm, Martin A.; Mata, Ricardo A., E-mail: rmata@gwdg.de [Georg-August-Universität Göttingen, Institut für Physikalische Chemie, Tammannstr. 6, 37077 Göttingen (Germany)

    2014-09-14T23:59:59.000Z

    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})

  8. Methanol Synthesis over Cu/ZnO/Al2O3: The Active Site in Industrial Catalysis

    SciTech Connect (OSTI)

    Behrens, Malte

    2012-03-28T23:59:59.000Z

    Unlike homogeneous catalysts, heterogeneous catalysts that have been optimized through decades are typically so complex and hard to characterize that the nature of the catalytically active site is not known. This is one of the main stumbling blocks in developing rational catalyst design strategies in heterogeneous catalysis. We show here how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. Using a combination of experimental evidence from bulk-, surface-sensitive and imaging methods collected on real high-performance catalytic systems in combination with DFT calculations. We show that the active site consists of Cu steps peppered with Zn atoms, all stabilized by a series of well defined bulk defects and surface species that need jointly to be present for the system to work.

  9. Crystal Structure of 12-Lipoxygenase Catalytic-Domain-Inhibitor Complex Identifies a Substrate-Binding Channel for Catalysis

    SciTech Connect (OSTI)

    Xu, Shu; Mueser, Timothy C.; Marnett, Lawrence J.; Funk, Jr., Max O. (Toledo); (Vanderbilt)

    2014-10-02T23:59:59.000Z

    Lipoxygenases are critical enzymes in the biosynthesis of families of bioactive lipids including compounds with important roles in the initiation and resolution of inflammation and in associated diseases such as diabetes, cardiovascular disease, and cancer. Crystals diffracting to high resolution (1.9 {angstrom}) were obtained for a complex between the catalytic domain of leukocyte 12-lipoxygenase and the isoform-specific inhibitor, 4-(2-oxapentadeca-4-yne)phenylpropanoic acid (OPP). In the three-dimensional structure of the complex, the inhibitor occupied a new U-shaped channel open at one end to the surface of the protein and extending past the redox-active iron site that is essential for catalysis. In models, the channel accommodated arachidonic acid, defining the binding site for the substrate of the catalyzed reaction. There was a void adjacent to the OPP binding site connecting to the surface of the enzyme and providing a plausible access channel for the other substrate, oxygen.

  10. Atomic geometry of mixed Ge-Si dimers in the initial-stage growth of Ge on Si,,001...2 1 X. Chen* and D. K. Saldin

    E-Print Network [OSTI]

    Saldin, Dilano

    Atomic geometry of mixed Ge-Si dimers in the initial-stage growth of Ge on Si,,001...2 1 X. Chen quantitatively the geometry of mixed Ge-Si dimers on a single domain Si 001 2 1 surface by azimuthal scanning core-level photoelectron diffraction. By analyzing Ge 3d diffraction patterns from Ge/Si 001 at 0.1 ML

  11. A Multinuclear Copper(I) Cluster Forms the Dimerization Interface in Copper-Loaded Human Copper Chaperone for Superoxide Dismutase

    SciTech Connect (OSTI)

    Stasser, J.P.; Siluvai, G.S.; Barry, A.N.; Blackburn, N.J.

    2009-06-04T23:59:59.000Z

    Copper binding and X-ray aborption spectroscopy studies are reported on untagged human CCS (hCCS; CCS = copper chaperone for superoxide dismutase) isolated using an intein self-cleaving vector and on single and double Cys to Ala mutants of the hCCS MTCQSC and CSC motifs of domains 1 (D1) and 3 (D3), respectively. The results on the wild-type protein confirmed earlier findings on the CCS-MBP (maltose binding protein) constructs, namely, that Cu(I) coordinates to the CXC motif, forming a cluster at the interface of two D3 polypeptides. In contrast to the single Cys to Ser mutations of the CCS-MBP protein (Stasser, J. P., Eisses, J. F., Barry, A. N., Kaplan, J. H., and Blackburn, N. J. (2005) Biochemistry 44, 3143-3152), single Cys to Ala mutations in D3 were sufficient to eliminate cluster formation and significantly reduce CCS activity. Analysis of the intensity of the Cu-Cu cluster interaction in C244A, C246A, and C244/246A variants suggested that the nuclearity of the cluster was greater than 2 and was most consistent with a Cu4S6 adamantane-type species. The relationship among cluster formation, oligomerization, and metal loading was evaluated. The results support a model in which Cu(I) binding converts the apo dimer with a D2-D2 interface to a new dimer connected by cluster formation at two D3 CSC motifs. The predominance of dimer over tetramer in the cluster-containing species strongly suggests that the D2 dimer interface remains open and available for sequestering an SOD1 monomer. This work implicates the copper cluster in the reactive form and adds detail to the cluster nuclearity and how copper loading affects the oligomerization states and reactivity of CCS for its partner SOD1.

  12. Metal carbonyl-hydrosilane reactions and hydrosilation catalysis. Final report for period May 1, 1995 - August 14, 1999

    SciTech Connect (OSTI)

    Cutler, Alan R.

    2001-04-14T23:59:59.000Z

    Manganese carbonyl complexes serve as hydrosilation precatalysts for selectively transforming a carbonyl group into a doxy methylene or a fully reduced methylene group. Substrates of interest include (1) aldehydes, ketones, carboxylic acids, silyl esters, and esters, and (2) their organometallic acyl counterparts. Two types of manganese precatalysts have been reported: (a) alkyl and acyl complexes (L)(CO){sub 4}MnR [L = CO, PPh{sub 3}; R = COCH{sub 3}, COPh, CH{sub 3}] and (b) halides (CO){sub 5}MnX and [(CO){sub 4}MnX]{sub 2} (X = Br, I). The former promote hydrosilation and deoxygenation catalysis; the latter promote dehydrogenative silation of alcohols and carboxylic acids as well as hydrosilation and deoxygenation of some metallocarboxylic acid derivatives. In every case studied, these Mn precatalysts are far more reactive or selective than traditional Rh(l) precatalysts. The reaction chemistry of the above and other Mn alkyl complexes with hydrosilanes was studied in order to probe catalysis mechanism(s). Thus, Mn(CO){sub 5} methyl, benzyl, acetyl, and benzoyl (4 p-substituents) complexes reacted with hydrosilines by four different mechanisms, which were established. A noteworthy development was that the methyl and benzoyl complexes gave moderate yields of a new ({eta}{sup 2}-Si-H) silane adduct (CO){sub 4}Mn(SiMe{sub 2}Ph)(H-SiMe{sub 2}Ph), which is stable in the presence of excess silane. This silane adduct promotes all three catalytic reactions; its extraordinary activity and potential selectivity are under study.

  13. Spectroscopic signatures of proton transfer dynamics in the water dimer cation

    SciTech Connect (OSTI)

    Kamarchik, Eugene; Kostko, Oleg; Bowman, Joel M.; Ahmed, Musahid; Krylov, Anna I.

    2009-12-21T23:59:59.000Z

    Using full dimensional EOM-IP-CCSD/aug-cc-pVTZ potential energy surfaces, the photoelectron spectrum, vibrational structure, and ionization dynamics of the water dimer radical cation, (H2O)+2, were computed. We also report an experimental photoelectron spectrum which is derived from photoionization efficiency measurements and compares favorably with the theoretical spectrum. The vibrational structure is also compared with the recent experimental work of Gardenier et al. [J. Phys. Chem. A 113, 4772 (2009)] and the recent theoretical calculations by Cheng et al. [J. Phys. Chem. A 113 13779 (2009)]. A reduced dimensionality nuclear Hamiltonian was used to compute the ionization dynamics for both the ground state and first excited state of the cation. The dynamics show markedly different behavior and spectroscopic signatures depending on which state of the cation is accessed by the ionization. Ionization to the ground-state cation surface induces a hydrogen transfer which is complete within 50 femtoseconds, whereas ionization to the first excited state results in a much slower process.

  14. Unbiased charge oscillations in DNA monomer-polymers and dimer-polymers

    E-Print Network [OSTI]

    Lambropoulos, Konstantinos; Morphis, Andreas; Kaklamanis, Konstantinos; Theodorakou, Marina; Simserides, Constantinos

    2015-01-01T23:59:59.000Z

    We call {\\it monomer} a B-DNA base-pair and examine, analytically and numerically, electron or hole oscillations in monomer- and dimer-polymers, i.e., periodic sequences with repetition unit made of one or two monomers. We employ a tight-binding (TB) approach at the base-pair level to readily determine the spatiotemporal evolution of a single extra carrier along a $N$ base-pair polymer. We study HOMO and LUMO eigenspectra as well as the mean over time probabilities to find the carrier at a particular monomer. We use the pure mean transfer rate $k$ to evaluate the easiness of charge transfer. The inverse decay length $\\beta$ for exponential fits $k(d)$, where $d$ is the charge transfer distance, and the exponent $\\eta$ for power law fits $k(N)$ are computed; generally power law fits are better. We illustrate that increasing the number of different parameters involved in the TB description, the fall of $k(d)$ or $k(N)$ becomes steeper and show the range covered by $\\beta$ and $\\eta$. Finally, both for the time-...

  15. Quantum Non-Demolition Detection of Polar Molecule Complexes: Dimers, Trimers, Tetramers

    E-Print Network [OSTI]

    Igor B. Mekhov

    2011-11-16T23:59:59.000Z

    The optical nondestructive method for in situ detection of the bound states of ultracold polar molecules is developed. It promises a minimally destructive measurement scheme up to a physically exciting quantum non-demolition (QND) level. The detection of molecular complexes beyond simple pairs of quantum particles (dimers, known, e.g., from the BEC-BCS theory) is suggested, including three-body (trimers) and four-body (tertramers) complexes trapped by one-dimensional tubes. The intensity of scattered light is sensitive to the molecule number fluctuations beyond the mean-density approximation. Such fluctuations are very different for various complexes, which leads to radically different light scattering. This type of research extends "quantum optics of quantum gases" to the field of ultracold molecules. Merging the quantum optical and ultracold gas problems will advance the experimental efforts towards the study of the light-matter interaction at its ultimate quantum level, where the quantizations of both light and matter are equally important.

  16. Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

    E-Print Network [OSTI]

    Gibson, Andrew J; Handrup, Karsten; Weston, Matthew; Mayor, Louise C; O'Shea, James N

    2014-01-01T23:59:59.000Z

    The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy (RPES) and near edge X-ray absorption fine structure spectroscopy (NEXAFS). Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2&3 in the excited state but not from the LUMO, therefore enabling core-hole clock analysis, which gives an upper limit of $6.0\\pm$2.5fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells (DSSC), which may lead to reduced recombination effe...

  17. Spectroscopic accuracy directly from quantum chemistry: Application to ground and excited states of beryllium dimer

    SciTech Connect (OSTI)

    Sharma, Sandeep; Booth, George H.; Chan, Garnet Kin-Lic, E-mail: gkc1000@gmail.com [Department of Chemistry, Frick Laboratory, Princeton University, New Jersey 08544 (United States); Yanai, Takeshi [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)] [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan); Umrigar, C. J. [Laboratory of Atomic and Solid State Physics, Cornell University, New York 14853 (United States)] [Laboratory of Atomic and Solid State Physics, Cornell University, New York 14853 (United States)

    2014-03-14T23:59:59.000Z

    We combine explicit correlation via the canonical transcorrelation approach with the density matrix renormalization group and initiator full configuration interaction quantum Monte Carlo methods to compute a near-exact beryllium dimer curve, without the use of composite methods. In particular, our direct density matrix renormalization group calculations produce a well-depth of D{sub e} = 931.2 cm{sup ?1} which agrees very well with recent experimentally derived estimates D{sub e} = 929.7±2 cm{sup ?1} [J. M. Merritt, V. E. Bondybey, and M. C. Heaven, Science 324, 1548 (2009)] and D{sub e}= 934.6 cm{sup ?1} [K. Patkowski, V. Špirko, and K. Szalewicz, Science 326, 1382 (2009)], as well the best composite theoretical estimates, D{sub e} = 938±15 cm{sup ?1} [K. Patkowski, R. Podeszwa, and K. Szalewicz, J. Phys. Chem. A 111, 12822 (2007)] and D{sub e}=935.1±10 cm{sup ?1} [J. Koput, Phys. Chem. Chem. Phys. 13, 20311 (2011)]. Our results suggest possible inaccuracies in the functional form of the potential used at shorter bond lengths to fit the experimental data [J. M. Merritt, V. E. Bondybey, and M. C. Heaven, Science 324, 1548 (2009)]. With the density matrix renormalization group we also compute near-exact vertical excitation energies at the equilibrium geometry. These provide non-trivial benchmarks for quantum chemical methods for excited states, and illustrate the surprisingly large error that remains for 1 {sup 1}?{sub g}{sup ?} state with approximate multi-reference configuration interaction and equation-of-motion coupled cluster methods. Overall, we demonstrate that explicitly correlated density matrix renormalization group and initiator full configuration interaction quantum Monte Carlo methods allow us to fully converge to the basis set and correlation limit of the non-relativistic Schrödinger equation in small molecules.

  18. Water dimer equilibrium constant calculation: A quantum formulation including metastable states

    SciTech Connect (OSTI)

    Leforestier, Claude, E-mail: claude.leforestier@univ-montp2.fr [Institut Charles Gerhardt, CNRS 5253, CC 15.01, Université Montpellier II-CNRS, 34095 Montpellier Cedex 05 (France)] [Institut Charles Gerhardt, CNRS 5253, CC 15.01, Université Montpellier II-CNRS, 34095 Montpellier Cedex 05 (France)

    2014-02-21T23:59:59.000Z

    We present a full quantum evaluation of the water second virial coefficient B(T) based on the Takahashi-Imada second order approximation. As the associated trace Tr[e{sup ??H{sub A}{sub B}}?e{sup ??H{sub A}{sub B}{sup o}}] is performed in the coordinate representation, it does also include contribution from the whole continuum, i.e., resonances and collision pairs of monomers. This approach is compared to a Path Integral Monte Carlo evaluation of this coefficient by Schenter [J. Chem. Phys. 117, 6573 (2002)] for the TIP4P potential and shown to give extremely close results in the low temperature range (250–450 K) reported. Using a recent ab initio flexible potential for the water dimer, this new formulation leads to very good agreement with experimental values over the whole range of temperatures available. The virial coefficient is then used in the well known relation K{sub p}(T) = ?(B(T) ? b{sub M})/RT where the excluded volume b{sub M} is assimilated to the second virial coefficient of pure water monomer vapor and approximated from the inner repulsive part of the interaction potential. This definition, which renders b{sub M} temperature dependent, allows us to retrieve the 38?cm{sup 3}?mol{sup ?1} value commonly used, at room temperature. The resulting values for K{sub p}(T) are in agreement with available experimental data obtained from infrared absorption spectra of water vapor.

  19. 2,2[prime]:4,4[double prime]:4[prime],4[prime][double prime]-quaterpyridyl: A building block for the preparation of novel redox reagents. 2. Bis(2,2[prime]-bipyridine)ruthenium(II) complexes

    SciTech Connect (OSTI)

    Bierig, K.; Morgan, R.J.; Tysoe, S.; Gafney, H.D.; Strekas, T.C.; Baker, A.D. (City Univ. of New York, Flushing (United States))

    1991-12-25T23:59:59.000Z

    The syntheses and properties of three new ruthenium(II) complexes based on the ligand 2,2[prime]:4,4[double prime]:4[prime],4[prime][double prime]-quaterpyridyl (qpy) are reported. Each new complex is of the type [Ru(bpy)[sub 2]L][sup n+], where L is the parent qpy ligand or is qpy derivatized by the methylation of one or both of the non-[alpha]-diimine nitrogen atoms and n = 2, 3, or 4. The photophysical and electrochemical properties of the new complex ions are reported. The parent ion [Ru(bpy)[sub 2]qpy][sup 2+] is strongly luminescent and has a relatively long lifetime, e.g. in excess of 1400 ns in acetonitrile solution. In contrast, the lifetime of the dimethyl derivative [Ru(bpy)[sub 2](qpyme[sub 2])][sup 4+] is less than 100 ns. This dimethylated complex has some novel properties. The excited state produced by M-L excitation to the qpyme[sub 2][sup 2+] ligand can be considered in terms of a Ru(III) core and a positively charged ligand. Typically, the excited states of other ruthenium(II) diimine complexes have had neutral or negatively charged ligands. Further, in structural terms, the complex can be considered as an intramolecular assembly of a ruthenium(II) diimine site and a viologen site. Cyclic voltammetry indicates that the first two electrons added to the complex enter the viologen-like acceptor site constituted by the qpyme[sub 2][sup 2+] ligand.

  20. A Novel Dimeric Inhibitor Targeting Beta2GPI in Beta2GPI/Antibody Complexes Implicated in Antiphospholipid Syndrome

    SciTech Connect (OSTI)

    A Kolyada; C Lee; A De Biasio; N Beglova

    2011-12-31T23:59:59.000Z

    {beta}2GPI is a major antigen for autoantibodies associated with antiphospholipid syndrome (APS), an autoimmune disease characterized by thrombosis and recurrent pregnancy loss. Only the dimeric form of {beta}2GPI generated by anti-{beta}2GPI antibodies is pathologically important, in contrast to monomeric {beta}2GPI which is abundant in plasma. We created a dimeric inhibitor, A1-A1, to selectively target {beta}2GPI in {beta}2GPI/antibody complexes. To make this inhibitor, we isolated the first ligand-binding module from ApoER2 (A1) and connected two A1 modules with a flexible linker. A1-A1 interferes with two pathologically important interactions in APS, the binding of {beta}2GPI/antibody complexes with anionic phospholipids and ApoER2. We compared the efficiency of A1-A1 to monomeric A1 for inhibition of the binding of {beta}2GPI/antibody complexes to anionic phospholipids. We tested the inhibition of {beta}2GPI present in human serum, {beta}2GPI purified from human plasma and the individual domain V of {beta}2GPI. We demonstrated that when {beta}2GPI/antibody complexes are formed, A1-A1 is much more effective than A1 in inhibition of the binding of {beta}2GPI to cardiolipin, regardless of the source of {beta}2GPI. Similarly, A1-A1 strongly inhibits the binding of dimerized domain V of {beta}2GPI to cardiolipin compared to the monomeric A1 inhibitor. In the absence of anti-{beta}2GPI antibodies, both A1-A1 and A1 only weakly inhibit the binding of pathologically inactive monomeric {beta}2GPI to cardiolipin. Our results suggest that the approach of using a dimeric inhibitor to block {beta}2GPI in the pathological multivalent {beta}2GPI/antibody complexes holds significant promise. The novel inhibitor A1-A1 may be a starting point in the development of an effective therapeutic for antiphospholipid syndrome.

  1. X-ray Crystallographic Studies of Substrate Binding to Aristolochene Synthase Suggest a Metal Ion Binding Sequence for Catalysis

    SciTech Connect (OSTI)

    Shishova,E.; Yu, F.; Miller, D.; Faraldos, J.; Zhao, Y.; Coates, R.; Allemann, R.; Cane, D.; Christianson, D.

    2008-01-01T23:59:59.000Z

    The universal sesquiterpene precursor, farnesyl diphosphate (FPP), is cyclized in an Mg2+-dependent reaction catalyzed by the tetrameric aristolochene synthase from Aspergillus terreus to form the bicyclic hydrocarbon aristolochene and a pyrophosphate anion (PPi) coproduct. The 2.1- Angstroms resolution crystal structure determined from crystals soaked with FPP reveals the binding of intact FPP to monomers A-C, and the binding of PPi and Mg2+B to monomer D. The 1.89- Angstroms resolution structure of the complex with 2-fluorofarnesyl diphosphate (2F-FPP) reveals 2F-FPP binding to all subunits of the tetramer, with Mg2+Baccompanying the binding of this analogue only in monomer D. All monomers adopt open activesite conformations in these complexes, but slight structural changes in monomers C and D of each complex reflect the very initial stages of a conformational transition to the closed state. Finally, the 2.4- Angstroms resolution structure of the complex with 12,13-difluorofarnesyl diphosphate (DF-FPP) reveals the binding of intact DF-FPP to monomers A-C in the open conformation and the binding of PPi, Mg2+B, and Mg2+C to monomer D in a predominantly closed conformation. Taken together, these structures provide 12 independent 'snapshots' of substrate or product complexes that suggest a possible sequence for metal ion binding and conformational changes required for catalysis.

  2. Ruthenium bis-Diimine Complexes with a Chelating Thioether Ligand: Delineating 1,10-Phenanthrolinyl and 2,2'-Bipyridyl Ligand Substituent Effects

    SciTech Connect (OSTI)

    Al-Rawashdeh, Nathir A.; Chatterjee, Sayandev; Krause, Jeanette A.; Connick, William B.

    2014-01-01T23:59:59.000Z

    A new series of ruthenium(II) bis-diimine complexes with a chelating thioether donor ligand has been prepared: Ru(diimine)2(dpte)2+ (diimine=1,10-phenanthroline (phen) (1); 5-CH3-phen (2), 5-Cl-phen (3); 5-Br-phen (4); 5-NO2-phen (5); 3,4,7,8-tetramethyl-phen (6); 4,7-diphenyl-phen (7); 5,5'-dimethyl-2,2'-bipyridine (8); 4,4'-di-tert-butyl-2,2'-bipyridine (9)). Crystal structures of 2, 5, 7 and 9 show that the complexes form 2 of the 12 possible conformational/configurational isomers, adopting compact C2-symmetric structures with short intramolecular transannular interactions between the diimine ligands and dpte phenyl groups; crystals of 2 and 5 contain non-statistical distributions of geometric isomers. In keeping with the ?-acidity of the dpte, the Ru(III/II) couple, E°'(Ru3+/2+), occurs at relatively high potentials (1.4-1.7 V vs Ag/AgCl), and the lowest spin-allowed MLCT absorption band occurs near 400 nm. Surprisingly, the complexes also exhibit fluid-solution luminescence originating from a lowest MLCT excited state with lifetimes in the 140-750 ns time range; in acetonitrile, compound 8 undergoes photo-induced solvolysis. Variations in the MLCT energies and redox potentials are quantitatively described using a summative Hammett parameter (?T), as well as using Lever's electrochemical parameters (EL). Recommended parameterizations for 2,2'-bipyridyl and 1,10-phenanthrolinyl ligands were derived from analysis of correlations based on 199 measurements of E°'(Ru3+/2+) for 99 homo- and heteroleptic ruthenium(II) tris-diimine complexes. Variations in E°'(Ru3+/2+) due to substituents at the 4- and 4'-positions of bipyridyl ligands and 4- and 7-positions of phenanthrolinyl ligands are significantly more strongly correlated with ?p+ than either ?m or ?p. Substituents at the 5- and 6-positions of phenanthrolinyl ligands are best described by ?m and have effects comparable to those of substituents at the 3- and 8-positions. Correlations of EL with ?T for 20 1,10-phenanthrolinyl ligands and for 35 2,2'-bipyridyl ligands show similar results, except that ?p and ?p+ are almost equally effective in describing the influence of substituents at the 4- and 4'-positions of bipyridyl ligands. For complexes 1-5 having an X-substituent at the 5-position of the phenanthrolinyl ligand, the MLCT absorption and emission energies, as well as the d5/d6-electron redox couple, are correlated with values for several other series of d6-electron metal complexes and give slopes that can be rationalized in terms of the relative number of diimine ligands and X-substituents.

  3. Electrochemical Oxidation of H2 Catalyzed by Ruthenium Hydride Complexes Bearing P2N2 Ligands With Pendant Amines as Proton Relays

    SciTech Connect (OSTI)

    Liu, Tianbiao L.; Rakowski DuBois, Mary; DuBois, Daniel L.; Bullock, R. Morris

    2014-11-03T23:59:59.000Z

    Two Ru hydride complexes (Cp*Ru(PPh2NBn2)H, 1-H and (Cp*Ru(PtBu2NBn2)H, 2-H) supported by cyclic PR2NR'2 ligands (Cp* = ?5-C5Me5; 1,5-diaza-3,7-diphosphacyclooctane, where R = Ph or tBu and R' = Bn) have been synthesized and fully characterized. Both complexes are demonstrated to be electrocatalysts for oxidation of H2 (1 atm, 22 °C) in the presence of external base, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). The turnover frequency of 2-H is 1.2 s-1, with an overpotential at Ecat/2 of 0.45 V, while catalysis by 1-H has a turnover frequency of 0.6 s-1 and an overpotential of 0.6 V at Ecat/2. Addition of H2O facilitates oxidation of H2 by 2-H and increases its turnover frequency to 1.9 s-1 while , H2O slows down the catalysis by 1-H. The different effects of H2O for 1-H and 2-H are ascribed to different binding affinities of H2O to the Ru center of the corresponding unsaturated species, [Cp*Ru(PPh2NBn2)]+ and [Cp*Ru(PPh2NBn2)]+. In addition, studies of Cp*Ru(dmpm)H (where dmpm = bis(dimethylphosphino)methane), a control complex lacking pendent amines in its diphosphine ligand, confirms the critical roles of the pendent amines of P2N2 ligands for oxidation of H2. We thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, for supporting initial parts of the work. Current work is supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  4. Benchmark Theoretical Study of the ?–? Binding Energy in the Benzene Dimer

    SciTech Connect (OSTI)

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

    2014-09-04T23:59:59.000Z

    We establish a new estimate for the interaction energy between two benzene molecules in the parallel displaced (PD) conformation by systematically converging (i) the intra- and intermolecular geometry at the minimum geometry, (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 replacements [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 (2,772 basis functions), whereas the largest CCSD(T) calculation with the cc-pV5Z basis set (1,752 basis functions). The cluster geometries were optimized with basis sets up to quadruple-? quality, observing that both its intra- and inter-molecular parts have practically converged with the triple-? 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 [to 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 BSSEcorrected binding energies was found to converge to the same CBS limit must 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 obtaining an accurate CBS limit. We considered extrapolations of the uncorrected (?𝐸) and BSSE-corrected (?𝐸!") binding energies, their average value (?𝐸!"#) as well as the average of the latter over the plain and augmented sets (?𝐸!"#) with the cardinal number of the basis set n. Our best estimate of the CCSD(T)/CBS limit for the ?-? interaction energy in the PD benzene dimer is De = 2.65 ± 0.02 kcal/mol. The best CCSD(T)/cc-pV5Z calculated value is 2.62 kcal/mol, just 0.03 kcal/mol away from the CBS limit. For comparison, the MP2/CBS limit estimate is 5.00 ± 0.01 kcal/mol, demonstrating a 90% overbinding with respect to CCSD(T). The Spin-Component-Scaled (SCS) MP2 variant was found to closely reproduce the CCSD(T) results for each basis set, while Scaled-Opposite-Spin (SOS) yielded results that are too low when compared to CCSD(T).

  5. High Throughput Sample Preparation and Analysis for DNA Sequencing, PCR and Combinatorial Screening of Catalysis Based on Capillary Array Technique

    SciTech Connect (OSTI)

    Yonghua Zhang

    2002-05-27T23:59:59.000Z

    Sample preparation has been one of the major bottlenecks for many high throughput analyses. The purpose of this research was to develop new sample preparation and integration approach for DNA sequencing, PCR based DNA analysis and combinatorial screening of homogeneous catalysis based on multiplexed capillary electrophoresis with laser induced fluorescence or imaging UV absorption detection. The author first introduced a method to integrate the front-end tasks to DNA capillary-array sequencers. protocols for directly sequencing the plasmids from a single bacterial colony in fused-silica capillaries were developed. After the colony was picked, lysis was accomplished in situ in the plastic sample tube using either a thermocycler or heating block. Upon heating, the plasmids were released while chromsomal DNA and membrane proteins were denatured and precipitated to the bottom of the tube. After adding enzyme and Sanger reagents, the resulting solution was aspirated into the reaction capillaries by a syringe pump, and cycle sequencing was initiated. No deleterious effect upon the reaction efficiency, the on-line purification system, or the capillary electrophoresis separation was observed, even though the crude lysate was used as the template. Multiplexed on-line DNA sequencing data from 8 parallel channels allowed base calling up to 620 bp with an accuracy of 98%. The entire system can be automatically regenerated for repeated operation. For PCR based DNA analysis, they demonstrated that capillary electrophoresis with UV detection can be used for DNA analysis starting from clinical sample without purification. After PCR reaction using cheek cell, blood or HIV-1 gag DNA, the reaction mixtures was injected into the capillary either on-line or off-line by base stacking. The protocol was also applied to capillary array electrophoresis. The use of cheaper detection, and the elimination of purification of DNA sample before or after PCR reaction, will make this approach an attractive alternative to current methods for genetic analysis and disease diagnosis.

  6. Structural Basis for Catalysis of a Tetrameric Class IIa Fructose 1,6-Bisphosphate Aldolase from Mycobacterium tuberculosis

    SciTech Connect (OSTI)

    Pegan, Scott D.; Ruskseree, Kamolchanok; Franzblau, Scott G.; Mesecar, Andrew D. ((NSTDC)); ((UIC))

    2009-03-04T23:59:59.000Z

    Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), currently infects one-third of the world's population in its latent form. The emergence of multidrug-resistant and extensive drug-resistant strains has highlighted the need for new pharmacological targets within M. tuberculosis. The class IIa fructose 1,6-bisphosphate aldolase (FBA) enzyme from M. tuberculosis (MtFBA) has been proposed as one such target since it is upregulated in latent TB. Since the structure of MtFBA has not been determined and there is little information available on its reaction mechanism, we sought to determine the X-ray structure of MtFBA in complex with its substrates. By lowering the pH of the enzyme in the crystalline state, we were able to determine a series of high-resolution X-ray structures of MtFBA bound to dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, and fructose 1,6-bisphosphate at 1.5, 2.1, and 1.3 {angstrom}, respectively. Through these structures, it was discovered that MtFBA belongs to a novel tetrameric class of type IIa FBAs. The molecular details at the interface of the tetramer revealed important information for better predictability of the quaternary structures among the FBAs based on their primary sequences. These X-ray structures also provide interesting and new details on the reaction mechanism of class II FBAs. Substrates and products were observed in geometries poised for catalysis; in addition, unexpectedly, the hydroxyl-enolate intermediate of dihydroxyacetone phosphate was also captured and resolved structurally. These concise new details offer a better understanding of the reaction mechanisms for FBAs in general and provide a structural basis for inhibitor design efforts aimed at this class of enzymes.

  7. Effect of dimerization on dynamics of spin-charge separation in Pariser-Parr-Pople model: A time-dependent DMRG study

    E-Print Network [OSTI]

    Dutta, Tirthankar

    2011-01-01T23:59:59.000Z

    We investigate the effect of static electron-phonon coupling, on real-time dynamics of spin and charge transport in $\\pi$-conjugated polyene chains. The polyene chain is modeled by the Pariser-Parr-Pople Hamiltonian with dimerized nearest-neighbor parameter $t_{0}(1+\\delta)$ for short bonds and $t_{0}(1-\\delta)$ for long bonds, and long-range electron-electron interactions. We follow the time evolution of the spin and charge using time-dependent DMRG technique, when a hole is injected at one end of the chain in its ground state. We find that spin and charge dynamics followed through spin and charge velocities, depend both on chain length and extent of dimerization, $\\delta$. Analysis of the results requires focusing on physical quantities such as average spin and charge polarizations, particularly in the large dimerization limit. In the dimerization range 0.0 $\\le$ $\\delta$ $\\le$ 0.15, spin-charge dynamics is found to have a well defined behavior, with spin-charge separation (measured as the ratio of charge v...

  8. 'Escherichia Coli' MutS Tetramerization Domain Structure Reveals That Stable Dimers But Not Tetramers are Essential for DNA Mismatch Repair in Vivo

    SciTech Connect (OSTI)

    Mendillo, M.L.; Putnam, C.D.; Kolodner, R.D.; /UC, San Diego

    2007-07-10T23:59:59.000Z

    The E. coli mispair binding protein MutS forms dimers and tetramers in vitro, although the functional form in vivo is under debate. Here we demonstrate that the MutS tetramer is extended in solution using small angle x-ray scattering (SAXS) and the crystal structure of the C-terminal 34 amino acids of MutS containing the tetramer-forming domain fused to maltose binding protein (MBP). Wild-type C-terminal MBP fusions formed tetramers and could bind MutS and MutS-MutL-DNA complexes. In contrast, Asp835Arg and Arg840Glu mutations predicted to disrupt tetrameric interactions only allowed dimerization of MBP. A chromosomal MutS truncation mutation eliminating the dimerization/tetramerization domain eliminated mismatch repair, whereas the tetramer-disrupting MutS Asp835Arg and Arg840Glu mutations only modestly affected MutS function. These results demonstrate that dimerization but not tetramerization of the MutS C- terminus is essential for mismatch repair.

  9. Structure of acostatin, a dimeric disintegrin from Southern copperhead (Agkistrodon contortrix contortrix), at 1.7 Å resolution

    SciTech Connect (OSTI)

    Moiseeva, Natalia [National Synchrotron Light Source, Brookhaven National Laboratory, Building 725D, Upton, NY 11973 (United States); Bau, Robert, E-mail: bau@usc.edu [Chemistry Department, University of Southern California, Los Angeles, CA 90089 (United States); Swenson, Stephen D.; Markland, Francis S. Jr [Department of Biochemistry and Molecular Biology and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 (United States); Choe, Jun-Yong [Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute/California Institute of Technology, Pasadena, CA 91125 (United States); Liu, Zhi-Jie [Departments of Biochemistry and Molecular Biology and Chemistry, University of Georgia, Athens, GA 30602 (United States); Allaire, Marc, E-mail: bau@usc.edu [National Synchrotron Light Source, Brookhaven National Laboratory, Building 725D, Upton, NY 11973 (United States)

    2008-04-01T23:59:59.000Z

    Two acostatin heterodimers interact together to form an ???? tetramer. Disintegrins are a family of small (4–14 kDa) proteins that bind to another class of proteins, integrins. Therefore, as integrin inhibitors, they can be exploited as anticancer and antiplatelet agents. Acostatin, an ?? heterodimeric disintegrin, has been isolated from the venom of Southern copperhead (Agkistrodon contortrix contortrix). The three-dimensional structure of acostatin has been determined by macromolecular crystallography using the molecular-replacement method. The asymmetric unit of the acostatin crystals consists of two heterodimers. The structure has been refined to an R{sub work} and R{sub free} of 18.6% and 21.5%, respectively, using all data in the 20–1.7 Å resolution range. The structure of all subunits is similar and is well ordered into N-terminal and C-terminal clusters with four intramolecular disulfide bonds. The overall fold consists of short ?-sheets, each of which is formed by a pair of antiparallel ?-strands connected by ?-turns and flexible loops of different lengths. Conformational flexibility is found in the RGD loops and in the C-terminal segment. The interaction of two N-terminal clusters via two intermolecular disulfide bridges anchors the ?? chains of the acostatin dimers. The C-terminal clusters of the heterodimer project in opposite directions and form a larger angle between them in comparison with other dimeric disintegrins. Extensive interactions are observed between two heterodimers, revealing an ???? acostatin tetramer. Further experiments are required to identify whether the ???? acostatin complex plays a functional role in vivo.

  10. Structure of Acostatin, a Dimeric Disintegrin From Southern Copperhead (Agkistrodon Contortrix Contortrix), at 1.7 Angstrom Resolution

    SciTech Connect (OSTI)

    Moiseeva, N.; Bau, R.; Swenson, S.D.; Marklund, F.S.; Jr.; Choe, J.-Y.; Liu, Z.-J.; Allaire, M.

    2009-05-26T23:59:59.000Z

    Disintegrins are a family of small (4-14 kDa) proteins that bind to another class of proteins, integrins. Therefore, as integrin inhibitors, they can be exploited as anticancer and antiplatelet agents. Acostatin, an {alpha}{beta} heterodimeric disintegrin, has been isolated from the venom of Southern copperhead (Agkistrodon contortrix contortrix). The three-dimensional structure of acostatin has been determined by macromolecular crystallography using the molecular-replacement method. The asymmetric unit of the acostatin crystals consists of two heterodimers. The structure has been refined to an R{sub work} and R{sub free} of 18.6% and 21.5%, respectively, using all data in the 20-1.7 {angstrom} resolution range. The structure of all subunits is similar and is well ordered into N-terminal and C-terminal clusters with four intramolecular disulfide bonds. The overall fold consists of short {beta}-sheets, each of which is formed by a pair of antiparallel {beta}-strands connected by {beta}-turns and flexible loops of different lengths. Conformational flexibility is found in the RGD loops and in the C-terminal segment. The interaction of two N-terminal clusters via two intermolecular disulfide bridges anchors the {alpha}{beta}chains of the acostatin dimers. The C-terminal clusters of the heterodimer project in opposite directions and form a larger angle between them in comparison with other dimeric disintegrins. Extensive interactions are observed between two heterodimers, revealing an {alpha}{beta}{beta}{alpha} acostatin tetramer. Further experiments are required to identify whether the {alpha}{beta}{beta}{alpha} acostatin complex plays a functional role in vivo.

  11. Positivity of the virial coefficients in lattice dimer models and upper bounds on the number of matchings on graphs

    E-Print Network [OSTI]

    P. Butera; P. Federbush; M. Pernici

    2015-02-24T23:59:59.000Z

    Using a relation between the virial expansion coefficients of the pressure and the entropy expansion coefficients in the case of the monomer-dimer model on infinite regular lattices, we have shown that, on hypercubic lattices of any dimension, the virial coefficients are positive through the 20th order. We have observed that all virial coefficients so far known for this system are positive also on infinite regular lattices with different structure. We are thus led to conjecture that the virial expansion coefficients $m_k $ are always positive. These considerations can be extended to the study of related bounds on finite graphs generalizing the infinite regular lattices, namely the finite grids and the regular biconnected graphs. The validity of the bounds $\\Delta^k {\\rm ln}(i! N(i)) \\le 0$ for $k \\ge 2$, where $N(i)$ is the number of configurations of $i$ dimers on the graph and $\\Delta$ is the forward difference operator, is shown to correspond to the positivity of the virial coefficients. Our tests on many finite lattice graphs indicate that on large lattices these bounds are satisfied, giving support to the conjecture on the positivity of the virial coefficients. An exhaustive survey of some classes of regular biconnected graphs with a not too large number $v$ of vertices shows only few violations of these bounds. We conjecture that the frequency of the violations vanishes as $v \\to \\infty$. We find rigorous upper bounds on $N(i)$ valid for arbitrary graphs and for regular graphs. The similarity between the Heilman-Lieb inequality and the one conjectured above suggests that one study the stricter inequality $m_k \\ge \\frac{1}{2k}$ for the virial coefficients, which is valid for all the known coefficients of the infinite regular lattice models.

  12. Effect of dimerization on dynamics of spin-charge separation in Pariser-Parr-Pople model: A time-dependent density matrix renormalization group study

    E-Print Network [OSTI]

    Tirthankar Dutta; S. Ramasesha

    2011-12-29T23:59:59.000Z

    We investigate the effect of static electron-phonon coupling, on real-time dynamics of spin and charge transport in $\\pi$-conjugated polyene chains. The polyene chain is modeled by the Pariser-Parr-Pople Hamiltonian with dimerized nearest-neighbor parameter $t_{0}(1+\\delta)$ for short bonds and $t_{0}(1-\\delta)$ for long bonds, and long-range electron-electron interactions. We follow the time evolution of the spin and charge using time-dependent density matrix renormalization group technique, when a hole is injected at one end of the chain in its ground state. We find that spin and charge dynamics followed through spin and charge velocities, depend both on chain length and extent of dimerization, $\\delta$. Analysis of the results requires focusing on physical quantities such as average spin and charge polarizations, particularly in the large dimerization limit. In the dimerization range 0.0 $\\le$ $\\delta$ $\\le$ 0.15, spin-charge dynamics is found to have a well defined behavior, with spin-charge separation (measured as the ratio of charge velocity to spin velocity) as well as, the total amount of charge and spin transported in a given time, along the chain, decreasing as dimerization increases. However, in the range 0.3 $\\le$ $\\delta$ $\\le$ 0.5, it is observed that the dynamics of spin and charge transport becomes complicated. It is observed that for large $\\delta$ values, spin-charge separation is suppressed and the injected hole fails to travel the entire length of the chain.

  13. Superacid catalysis of light hydrocarbon conversion. DOE PETC seventh quarterly progress report, April 1, 1995--July 31, 1995

    SciTech Connect (OSTI)

    Gates, B.C. [Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

    1996-02-01T23:59:59.000Z

    Iron- and manganese-promoted sulfated zirconia is a catalyst for the conversion of propane, but the rate of conversion of propane is much less than the rate of conversion of butane. Whereas this catalyst appears to be a good candidate for practical, industrial conversion of butane, it appears to lack sufficient activity for practical conversion of propane. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversion. Solid and catalysts, namely, sulfated zirconia, iron- and manganese-promoted sulfated zirconia, and USY zeolite, were tested for conversion of propane at 1 atm, 200-450{degrees}C, and propane partial pressures in the range of 0.01-0.05 atm. Both promoted and unpromoted sulfated zirconia were found to be active for conversion of propane into butanes, pentanes, methane, ethane, ethylene, and propylene in the temperature range of 200-350{degrees}C, but catalyst deactivation was rapid. At the higher temperatures, only cracking and dehydrogenation products were observed. In contrast to the zirconia-supported catalysts, USY zeolite was observed to convert propane (into propylene, methane, and ethylene) only at temperatures {ge}400{degrees}C. The initial (5 min on stream) rates of propane conversion in the presence of iron- and manganese-promoted sulfated zirconia, sulfated zirconia, and USY zeolite at 450{degrees}C and 0.01 atm propane partial pressure were 3.3 x 10{sup -8}, 0.3 x 10{sup -8}, and 0.06 x 10{sup -8} mol/(s{center_dot}g), respectively. The product distributions in the temperature range 200-450{degrees}C are those of acid-base catalysis, being similar to what has been observed in superacid solution chemistry at temperatures <0{degrees}C. If propane conversion at 450{degrees}C can be considered as a probe of acid strength of the catalyst, the activity comparison suggests that the promoted sulfated zirconia is a stronger acid than sulfated zirconia, which is a stronger acid than USY zeolite.

  14. Ligand Migration and Cavities within Scapharca Dimeric HbI: Studies by Time-Resolved Crystallo- graphy, Xe Binding, and Computational Analysis

    SciTech Connect (OSTI)

    Knapp, James E.; Pahl, Reinhard; Cohen, Jordi; Nichols, Jeffry C.; Schulten, Klaus; Gibson, Quentin H.; Š rajer, Vukica; Royer, Jr., William E.; (UMASS MED); (UIUC); (UC_

    2009-12-01T23:59:59.000Z

    As in many other hemoglobins, no direct route for migration of ligands between solvent and active site is evident from crystal structures of Scapharca inaequivalvis dimeric HbI. Xenon (Xe) and organic halide binding experiments, along with computational analysis presented here, reveal protein cavities as potential ligand migration routes. Time-resolved crystallographic experiments show that photodissociated carbon monoxide (CO) docks within 5 ns at the distal pocket B site and at more remote Xe4 and Xe2 cavities. CO rebinding is not affected by the presence of dichloroethane within the major Xe4 protein cavity, demonstrating that this cavity is not on the major exit pathway. The crystal lattice has a substantial influence on ligand migration, suggesting that significant conformational rearrangements may be required for ligand exit. Taken together, these results are consistent with a distal histidine gate as one important ligand entry and exit route, despite its participation in the dimeric interface.

  15. Kinetic Stability May Determine the Interaction Dynamics of the Bifunctional Protein DCoH1, the Dimerization Cofactor of the Transcription Factor HNF-1[alpha

    SciTech Connect (OSTI)

    Rho, H.; Jones, C.N.; Rose, R.B. (NCSU)

    2010-12-07T23:59:59.000Z

    The two disparate functions of DCoH1 (dimerization cofactor of HNF-1)/PCD (pterin-4a-carbinolamine dehydratase) are associated with a change in oligomeric state. DCoH dimers enhance the activity of the diabetes-associated transcription factor HNF-1{alpha} (hepatocyte nuclear factor-1{alpha}), while the PCD activity of DCoH1 homotetramers aids in aromatic amino acid metabolism. These complexes compete for the same interface of the DCoH dimer. Formation of the DCoH1/HNF-1{alpha} complex requires cofolding. The homotetramer of the DCoH1 paralogue, DCoH2, interacts with HNF-1{alpha} through simple mixing. To further investigate regulation of DCoH/HNF-1{alpha} complex formation, we measured the stability of the DCoH1 homotetramer through unfolding studies by intrinsic tryptophan fluorescence. DCoH2 unfolding is reversible. Surprisingly, the DCoH1 homotetramer is resistant to guanidine unfolding but refolds at a much lower guanidine concentration. We show that a point mutation at the DCoH1 tetramer interface, Thr 51 Ser, overcomes the dissociation barrier of the homotetramer and increases the interaction with HNF-1{alpha}. The 1.8 {angstrom} resolution crystal structure of DCoH1 T51S shows the presence of an ordered water molecule at the tetramer interface, as in DCoH2, which may destabilize the homotetramer. The equilibrium unfolding data were fit to a two-state model with no apparent intermediate. Folding intermediates were detectable by size exclusion chromatography. For wild-type DCoH1 the intermediates changed with time, suggesting a kinetic origin for the unfolding barrier of the homotetramer. We propose an unfolding pathway in which the tetramer unfolds slowly, but the dimer folds reversibly. Implications for regulation of DCoH1/HNF-1{alpha} complex formation are discussed.

  16. ZEOLITE CATALYSIS - TECHNOLOGY

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    hydrogen with a dual functional catalyst possessing both cracking and hydrogenation-dehydrogenation properties.

  17. ZEOLITE CATALYSIS - TECHNOLOGY

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    and after Hydrodewaxing with 2SH-5 Virgin heavy gas oil MMDWprocessed heavy gas oil Properties Gravity, API Pour point,

  18. Catalysis over activated zeolites

    SciTech Connect (OSTI)

    Miale, J.N.; Chang, C.D.

    1985-02-19T23:59:59.000Z

    A process is provided for conducting organic compound conversion over a catalyst composition comprising a supported crystalline zeolite having a high initial silica-to-alumina mole ratio, said supported zeolite being prepared by compositing said crystalline zeolite with alumina, reacting the composite with a particular hydrogen fluoride solution in a specified way, drying the hydrogen fluoride reacted composite, treating the dried composite by hydrolysis, ammonolysis and/or by contact with an ammonium salt solution, and calcining the resulting material.

  19. Catalysis over activated zeolites

    SciTech Connect (OSTI)

    Miale, J. N.; Chang, C. D.

    1985-02-19T23:59:59.000Z

    A process is provided for conducting organic compound conversion over a catalyst comprising a crystalline zeolite which has been treated by impregnation with an ammoniacal aluminum fluoride solution, contact with an ammonium salt solution, and calcination.

  20. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01T23:59:59.000Z

    synthesis gas by coal gasification is very expensive andin the cost of coal gasification would have a significantas K co , to promote gasification would be beneficial s1nce

  1. CATALYSIS SCIENCE AND TECHNOLOGY

    SciTech Connect (OSTI)

    M. ABRAMS; R. BAKER; ET AL

    2000-08-01T23:59:59.000Z

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Our objectives were to develop a multidisciplinary team and capabilities to develop a fundamental understanding of homogeneous, heterogeneous, and heterogenized catalysts. With the aid of theoretical chemistry approaches we explored and characterized the chemical reactivity and physical properties of a large number of catalytic systems.

  2. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01T23:59:59.000Z

    production of SNG or Fischer-Tropsch products Therefore, abe trying to obtain from Fischer-Tropsch synthesis? Answer:intermediates in Fischer-Tropsch synthesis? Answer: It was

  3. HETEROGENEOUS CATALYSIS RESEARCH MEETING

    E-Print Network [OSTI]

    Authors, Various

    2011-01-01T23:59:59.000Z

    is pointed out that coal gasification involves 70% to 80% ofof alkali metals in coal gasification is poorly under- stoodOther methods of catalyzing coal gasification also should be

  4. ZEOLITE CATALYSIS - TECHNOLOGY

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    and Weisz, P. B. , Oil and Gas J. Literature 15. Heinemann,Edinburgh 7. Oblad, A. G. Oil and Gas J. 1972, 70, (13), 84F. E. and Smith, R. B. , Oil & Gas J. 1978, 76, May 22, 81

  5. 2012 Catalysis Lectures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del(ANL-IN-03-032) -Less isNFebruary 2004August 2011 Wed,2011November 2012222012

  6. Calculation of two-centre two-electron integrals over Slater-type orbitals revisited. III. Case study of the beryllium dimer

    E-Print Network [OSTI]

    Micha? Lesiuk; Micha? Przybytek; Monika Musia?; Bogumi? Jeziorski; Robert Moszynski

    2015-01-20T23:59:59.000Z

    In this paper we present results of ab-initio calculations for the beryllium dimer with basis set of Slater-type orbitals (STOs). Nonrelativistic interaction energy of the system is determined using the frozen-core full configuration interaction calculations combined with high-level coupled cluster correction for inner-shell effects. Newly developed STOs basis sets, ranging in quality from double to sextuple zeta, are used in these computations. Principles of their construction are discussed and several atomic benchmarks are presented. Relativistic effects of order ${\\alpha}^2$ are calculated perturbatively by using the Breit-Pauli Hamiltonian and are found to be significant. We also estimate the leading-order QED effects. Influence of the adiabatic correction is found to be negligible. Finally, the interaction energy of the beryllium dimer is determined to be 929.0$\\,\\pm\\,$1.9 $cm^{-1}$, in a very good agreement with the recent experimental value. The results presented here appear to be the most accurate ab-initio calculations for the beryllium dimer available in the literature up to date and probably also one of the most accurate calculations for molecular systems containing more than four electrons.

  7. Design, Synthesis and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2007-03-31T23:59:59.000Z

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rates and selectivities for synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch Synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based materials with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During the fifth and sixth reporting period, we studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influenced the performance of these materials in the Fischer-Tropsch synthesis. We also continued our studies of the kinetic behavior of these materials during the sixth reporting period. Specifically, the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch Synthesis reactions led us to propose a new sequence of elementary steps on Fe and Co Fischer-Tropsch catalysts. Finally, we also started a study of the use of colloidal precipitation methods for the synthesis small Co clusters using recently developed methods to explore possible further improvements in FTS rates and selectivities. We found that colloidal synthesis makes possible the preparation of small cobalt particles, although large amount of cobalt silicate species, which are difficult to reduce, were formed. During this seventh reporting period, we have explored several methods to modify the silanol groups on SiO{sub 2} by using either a homogeneous deposition-precipitation method or surface titration of Si-OH on SiO{sub 2} with zirconium (IV) ethoxide to prevent the formation of unreducible and unreactive CoO{sub x} species during synthesis and FTS catalysis. We have synthesized monometallic Co/ZrO{sub 2}/SiO{sub 2} catalysts with different Co loadings (11-20 wt%) by incipient wetness impregnation methods and characterized the prepared Co supported catalysts by H{sub 2} temperature-programmed reduction (H{sub 2}-TPR) and H{sub 2}-chemisorption. We have measured the catalytic performance in FTS reactions and shown that although the hydroxyl groups on the SiO{sub 2} surface are difficult to be fully titrated by ZrO{sub 2}, modification of ZrO{sub 2} on SiO{sub 2} surface can improve the Co clusters dispersion and lead to a larger number of exposed Co surface atoms after reduction and during FTS reactions. During this seventh reporting period, we have also advanced our development of the reaction mechanism proposed in the previous reporting period. Specifically, we have shown that our novel proposal for the pathways involved in CO activation on Fe and Co catalysts is consistent with state-of-the-art theoretical calculations carried out in collaboration with Prof. Manos Mavrikakis (University of Wisconsin-Madison). Finally, we have also worked on the preparation of several manuscripts describing our findings about the preparation, activation and mechanism of the FTS with Fe-based catalysts and we have started redacting the final report for this project.

  8. Migration and Directional Change of Interstitial Clusters in ?-Fe: Searching for Transition States by the Dimer Method

    SciTech Connect (OSTI)

    Gao, Fei; Heinisch, Howard L.; Kurtz, Richard J.; Osetsky, Yuri N.; Hoagland, Richard G.

    2005-02-01T23:59:59.000Z

    The interstitial clusters produced by cascades in metals have very high mobility and exhibit thermally activated, one-dimensional glide along the crowdion direction, as revealed by molecular dynamics (MD) simulations. Only small interstitial clusters (<4) are observed to change their glide direction during the period of MD simulations ({approx} 10 ns), but the directional change for larger clusters is inaccessible to MD due to the limited time-scale. In order to overcome the ''time barrier'' in MD simulations, the dimer method is employed to search for possible transition states of interstitials and small interstitial clusters in alpha-Fe. The method uses only the first derivatives of the potential energy to find saddle points without knowledge of the final state of the transition. The possible transition states are studied as a function of interstitial cluster size, and the lowest energy barriers correspond to defect migration along (111) directions, as seen in MD simulations. Small clusters change their direction by a (110) fragment mechanism involving rotation of each crowdion into and out of the (110) dumbbell configuration, whereas the directional change for larger clusters is a two-step process consisting of translation along a <100> direction and rotation into an equivalent (111) direction. The mechanism of changing direction for a tri-interstitial cluster is also investigated using MD simulations.

  9. The Nudix Hydrolase CDP-Chase, a CDP-Choline Pyrophosphatase, Is an Asymmetric Dimer with Two Distinct Enzymatic Activities

    SciTech Connect (OSTI)

    Duong-Ly, Krisna C.; Gabelli, Sandra B.; Xu, WenLian; Dunn, Christopher A.; Schoeffield, Andrew J.; Bessman, Maurice J.; Amzel, L. Mario (Loyola); (JHU)

    2011-09-06T23:59:59.000Z

    A Nudix enzyme from Bacillus cereus catalyzes the hydrolysis of CDP-choline to produce CMP and phosphocholine. Here, we show that in addition, the enzyme has a 3{prime} {yields} 5{prime} RNA exonuclease activity. The structure of the free enzyme, determined to a 1.8-{angstrom} resolution, shows that the enzyme is an asymmetric dimer. Each monomer consists of two domains, an N-terminal helical domain and a C-terminal Nudix domain. The N-terminal domain is placed relative to the C-terminal domain such as to result in an overall asymmetric arrangement with two distinct catalytic sites: one with an 'enclosed' Nudix pyrophosphatase site and the other with a more open, less-defined cavity. Residues that may be important for determining the asymmetry are conserved among a group of uncharacterized Nudix enzymes from Gram-positive bacteria. Our data support a model where CDP-choline hydrolysis is catalyzed by the enclosed Nudix site and RNA exonuclease activity is catalyzed by the open site. CDP-Chase is the first identified member of a novel Nudix family in which structural asymmetry has a profound effect on the recognition of substrates.

  10. The structural basis for partitioning of the XRCC1/DNA ligase III-[alpha] BRCT-mediated dimer complexes

    SciTech Connect (OSTI)

    Cuneo, Matthew J.; Gabel, Scott A.; Krahn, Joseph M.; Ricker, Melissa A.; London, Robert E. (NIH)

    2011-11-17T23:59:59.000Z

    The ultimate step common to almost all DNA repair pathways is the ligation of the nicked intermediate to form contiguous double-stranded DNA. In the mammalian nucleotide and base excision repair pathways, the ligation step is carried out by ligase III-{alpha}. For efficient ligation, ligase III-{alpha} is constitutively bound to the scaffolding protein XRCC1 through interactions between the C-terminal BRCT domains of each protein. Although structural data for the individual domains has been available, no structure of the complex has been determined and several alternative proposals for this interaction have been advanced. Interpretation of the models is complicated by the formation of homodimers that, depending on the model, may either contribute to, or compete with heterodimer formation. We report here the structures of both homodimer complexes as well as the heterodimer complex. Structural characterization of the heterodimer formed from a longer XRCC1 BRCT domain construct, including residues comprising the interdomain linker region, revealed an expanded heterodimer interface with the ligase III-{alpha} BRCT domain. This enhanced linker-mediated binding interface plays a significant role in the determination of heterodimer/homodimer selectivity. These data provide fundamental insights into the structural basis of BRCT-mediated dimerization, and resolve questions related to the organization of this important repair complex.

  11. The Structural Basis for Partitioning of the XRCC1/DNA Ligase III-alpha BRCT-mediated Dimer Complexes

    SciTech Connect (OSTI)

    M Cuneo; S Gabel; J Krahn; M Ricker; R London

    2011-12-31T23:59:59.000Z

    The ultimate step common to almost all DNA repair pathways is the ligation of the nicked intermediate to form contiguous double-stranded DNA. In the mammalian nucleotide and base excision repair pathways, the ligation step is carried out by ligase III-{alpha}. For efficient ligation, ligase III-{alpha} is constitutively bound to the scaffolding protein XRCC1 through interactions between the C-terminal BRCT domains of each protein. Although structural data for the individual domains has been available, no structure of the complex has been determined and several alternative proposals for this interaction have been advanced. Interpretation of the models is complicated by the formation of homodimers that, depending on the model, may either contribute to, or compete with heterodimer formation. We report here the structures of both homodimer complexes as well as the heterodimer complex. Structural characterization of the heterodimer formed from a longer XRCC1 BRCT domain construct, including residues comprising the interdomain linker region, revealed an expanded heterodimer interface with the ligase III-{alpha} BRCT domain. This enhanced linker-mediated binding interface plays a significant role in the determination of heterodimer/homodimer selectivity. These data provide fundamental insights into the structural basis of BRCT-mediated dimerization, and resolve questions related to the organization of this important repair complex.

  12. Proton-bound dimers of nitrogen heterocyclic molecules: Substituent effects on the structures and binding energies of homodimers of diazine, triazine, and fluoropyridine

    SciTech Connect (OSTI)

    Attah, Isaac K.; Platt, Sean P.; Meot-Ner, Michael; El-Shall, M. S., E-mail: mselshal@vcu.edu [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284-2006 (United States); Aziz, Saadullah G.; Alyoubi, Abdulrahman O. [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)] [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-03-21T23:59:59.000Z

    The bonding energies of proton-bound homodimers BH{sup +}B were measured by ion mobility equilibrium studies and calculated at the DFT B3LYP/6-311++G{sup **} level, for a series of nitrogen heterocyclic molecules (B) with electron-withdrawing in-ring N and on-ring F substituents. The binding energies (?H°{sub dissoc}) of the proton-bound dimers (BH{sup +}B) vary significantly, from 29.7 to 18.1 kcal/mol, decreasing linearly with decreasing the proton affinity of the monomer (B). This trend differs significantly from the constant binding energies of most homodimers of other organic nitrogen and oxygen bases. The experimentally measured ?H°{sub dissoc} for (1,3-diazine){sub 2}H{sup +}, i.e., (pyrimidine){sub 2}H{sup +} and (3-F-pyridine){sub 2}H{sup +} are 22.7 and 23.0 kcal/mol, respectively. The measured ?H°{sub dissoc} for the pyrimidine{sup ·+}(3-F-pyridine) radical cation dimer (19.2 kcal/mol) is signifcantly lower than that of the proton-bound homodimers of pyrimidine and 3-F-pyridine, reflecting the stronger interaction in the ionic H-bond of the protonated dimers. The calculated binding energies for (1,2-diazine){sub 2}H{sup +}, (pyridine){sub 2}H{sup +}, (2-F-pyridine){sub 2}H{sup +}, (3-F-pyridine){sub 2}H{sup +}, (2,6-di-F-pyridine){sub 2}H{sup +}, (4-F-pyridine){sub 2}H{sup +}, (1,3-diazine){sub 2}H{sup +}, (1,4-diazine){sub 2}H{sup +}, (1,3,5-triazine){sub 2}H{sup +}, and (pentafluoropyridine){sub 2}H{sup +} are 29.7, 24.9, 24.8, 23.3, 23.2, 23.0, 22.4, 21.9, 19.3, and 18.1 kcal/mol, respectively. The electron-withdrawing substituents form internal dipoles whose electrostatic interactions contribute to both the decreased proton affinities of (B) and the decreased binding energies of the protonated dimers BH{sup +}B. The bonding energies also vary with rotation about the hydrogen bond, and they decrease in rotamers where the internal dipoles of the components are aligned efficiently for inter-ring repulsion. For compounds substituted at the 3 or 4 (meta or para) positions, the lowest energy rotamers are T-shaped with the planes of the two rings rotated by 90° about the hydrogen bond, while the planar rotamers are weakened by repulsion between the ortho hydrogen atoms of the two rings. Conversely, in ortho-substituted (1,2-diazine){sub 2}H{sup +} and (2-F-pyridine){sub 2}H{sup +}, attractive interactions between the ortho (C–H) hydrogen atoms of one ring and the electronegative ortho atoms (N or F) of the other ring are stabilizing, and increase the protonated dimer binding energies by up to 4 kcal/mol. In all of the dimers, rotation about the hydrogen bond can involve a 2–4 kcal/mol barrier due to the relative energies of the rotamers.

  13. Electron Transfer Catalyzed [2 + 2] Cycloreversion of Benzene G. Devi Reddy and Olaf Wiest*

    E-Print Network [OSTI]

    Hudlicky, Tomas

    Electron Transfer Catalyzed [2 + 2] Cycloreversion of Benzene Dimers G. Devi Reddy and Olaf Wiest, Florida 32611-7200 Received December 8, 1998 The catalysis of the [2 + 2] cycloreversion of the anti-o,o-benzene dimer 1 and the syn-o,o- naphthalene-benzene dimer 2 through thermal and photoinduced electron transfer

  14. The Atypical Response Regulator Protein ChxR Has Structural Characteristics and Dimer Interface Interactions That Are Unique within the OmpR/PhoB Subfamily

    SciTech Connect (OSTI)

    Hickey, John M.; Lovell, Scott; Battaile, Kevin P.; Hu, Lei; Middaugh, C. Russell; Hefty, P. Scott (Kansas); (HWMRI)

    2013-05-29T23:59:59.000Z

    Typically as a result of phosphorylation, OmpR/PhoB response regulators form homodimers through a receiver domain as an integral step in transcriptional activation. Phosphorylation stabilizes the ionic and hydrophobic interactions between monomers. Recent studies have shown that some response regulators retain functional activity in the absence of phosphorylation and are termed atypical response regulators. The two currently available receiver domain structures of atypical response regulators are very similar to their phospho-accepting homologs, and their propensity to form homodimers is generally retained. An atypical response regulator, ChxR, from Chlamydia trachomatis, was previously reported to form homodimers; however, the residues critical to this interaction have not been elucidated. We hypothesize that the intra- and intermolecular interactions involved in forming a transcriptionally competent ChxR are distinct from the canonical phosphorylation (activation) paradigm in the OmpR/PhoB response regulator subfamily. To test this hypothesis, structural and functional studies were performed on the receiver domain of ChxR. Two crystal structures of the receiver domain were solved with the recently developed method using triiodo compound I3C. These structures revealed many characteristics unique to OmpR/PhoB subfamily members: typical or atypical. Included was the absence of two {alpha}-helices present in all other OmpR/PhoB response regulators. Functional studies on various dimer interface residues demonstrated that ChxR forms relatively stable homodimers through hydrophobic interactions, and disruption of these can be accomplished with the introduction of a charged residue within the dimer interface. A gel shift study with monomeric ChxR supports that dimerization through the receiver domain is critical for interaction with DNA.

  15. Improvement of the chemical and physical stability of the EC1 domain of E-cadherin by blocking its disulfide-mediated dimerization

    E-Print Network [OSTI]

    Trivedi, Maulik

    2008-01-30T23:59:59.000Z

    CD studies 3.2.3.1 Intrinsic fluorescence emission spectroscopy studies 3.3. Results 3.3.1. Alkylation of EC1 3.3.2. Chemical stability of EC1-IN 55 56 56 65 65 73 77... and B chains of EC1 dimer xv 2.9a 2.9b 3.1a 3.1b 3.1c 3.1d 3.2a 3.2b 3.3a 3.3b 80 81 101 102 103 104 106 107...

  16. Calculation of two-centre two-electron integrals over Slater-type orbitals revisited. III. Case study of the beryllium dimer

    E-Print Network [OSTI]

    Lesiuk, Micha?; Musia?, Monika; Jeziorski, Bogumi?; Moszynski, Robert

    2014-01-01T23:59:59.000Z

    In this paper we present results of ab-initio calculations for the beryllium dimer with basis set of Slater-type orbitals (STOs). Nonrelativistic interaction energy of the system is determined using the frozen-core full configuration interaction calculations combined with high-level coupled cluster correction for inner-shell effects. Newly developed STOs basis sets, ranging in quality from double to sextuple zeta, are used in these computations. Principles of their construction are discussed and several atomic benchmarks are presented. Relativistic effects of order ${\\alpha}^2$ are calculated perturbatively by using the Breit-Pauli Hamiltonian and are found to be significant. We also estimate the leading-order QED effects. Influence of the adiabatic correction is found to be negligible. Finally, the interaction energy of the beryllium dimer is determined to be 929.0$\\,\\pm\\,$1.9 $cm^{-1}$, in a very good agreement with the recent experimental value. The results presented here appear to be the most accurate ab-...

  17. CRM1-dependent nuclear export and dimerization with hMSH5 contribute to the regulation of hMSH4 subcellular localization

    SciTech Connect (OSTI)

    Neyton, Sophie; Lespinasse, Francoise; Lahaye, Francois [Equipe M3R, UMR 6543, Universite de Nice Sophia-Antipolis, CNRS, Faculte de Medecine, Avenue de Valombrose 06107, Nice Cedex 2 (France); Staccini, Pascal [Stic, Universite de Nice-Sophia Antipolis, Faculte de Medecine, Avenue de Valombrose 06107, Nice Cedex 2 (France); Paquis-Flucklinger, Veronique [Equipe M3R, UMR 6543, Universite de Nice Sophia-Antipolis, CNRS, Faculte de Medecine, Avenue de Valombrose 06107, Nice Cedex 2 (France); Santucci-Darmanin, Sabine [Equipe M3R, UMR 6543, Universite de Nice Sophia-Antipolis, CNRS, Faculte de Medecine, Avenue de Valombrose 06107, Nice Cedex 2 (France)], E-mail: santucci@hermes.unice.fr

    2007-10-15T23:59:59.000Z

    MSH4 and MSH5 are members of the MutS homolog family, a conserved group of proteins involved in DNA mismatch correction and homologous recombination. Although several studies have provided compelling evidences suggesting that MSH4 and MSH5 could act together in early and late stages of meiotic recombination, their precise roles are poorly understood and recent findings suggest that the human MSH4 protein may also exert a cytoplasmic function. Here we show that MSH4 is present in the cytoplasm and the nucleus of both testicular cells and transfected somatic cells. Confocal studies on transfected cells provide the first evidence that the subcellular localization of MSH4 is regulated, at least in part, by an active nuclear export pathway dependent on the exportin CRM1. We used deletion mapping and mutagenesis to define two functional nuclear export sequences within the C-terminal part of hMSH4 that mediate nuclear export through the CRM1 pathway. Our results suggest that CRM1 is also involved in MSH5 nuclear export. In addition, we demonstrate that dimerization of MSH4 and MSH5 facilitates their nuclear localization suggesting that dimerization may regulate the intracellular trafficking of these proteins. Our findings suggest that nucleocytoplasmic traffic may constitute a regulatory mechanism for MSH4 and MSH5 functions.

  18. Visible-Light Photoredox Catalysis: Selective Reduction of Carbon Dioxide to Carbon Monoxide by a Nickel N-Heterocyclic Carbene-Isoquinoline Complex

    SciTech Connect (OSTI)

    Thoi, VanSara; Kornienko, Nick; Margarit, C; Yang, Peidong; Chang, Christopher

    2013-06-07T23:59:59.000Z

    The solar-driven reduction of carbon dioxide to value-added chemical fuels is a longstanding challenge in the fields of catalysis, energy science, and green chemistry. In order to develop effective CO2 fixation, several key considerations must be balanced, including (1) catalyst selectivity for promoting CO2 reduction over competing hydrogen generation from proton reduction, (2) visible-light harvesting that matches the solar spectrum, and (3) the use of cheap and earth-abundant catalytic components. In this report, we present the synthesis and characterization of a new family of earth-abundant nickel complexes supported by N-heterocyclic carbene amine ligands that exhibit high selectivity and activity for the electrocatalytic and photocatalytic conversion of CO2 to CO. Systematic changes in the carbene and amine donors of the ligand have been surveyed, and [Ni(Prbimiq1)]2+ (1c, where Prbimiq1 = bis(3-(imidazolyl)isoquinolinyl)propane) emerges as a catalyst for electrochemical reduction of CO2 with the lowest cathodic onset potential (Ecat = 1.2 V vs SCE). Using this earth-abundant catalyst with Ir(ppy)3 (where ppy = 2-phenylpyridine) and an electron donor, we have developed a visible-light photoredox system for the catalytic conversion of CO2 to CO that proceeds with high selectivity and activity and achieves turnover numbers and turnover frequencies reaching 98,000 and 3.9 s1, respectively. Further studies reveal that the overall efficiency of this solar-to-fuel cycle may be limited by the formation of the active Ni catalyst and/or the chemical reduction of CO2 to CO at the reduced nickel center and provide a starting point for improved photoredox systems for sustainable carbon-neutral energy conversion.

  19. Global Structure of a Three-Way Junction in a Phi29 Packaging RNA Dimer Determined Using Site-Directed Spin Labeling

    SciTech Connect (OSTI)

    Zhang, Xiaojun; Tung, Chang-Shung; Sowa, Glenna; Hatmal, Ma'mon M.; Haworth, Ian S.; Qin, Peter Z.

    2012-02-08T23:59:59.000Z

    The condensation of bacteriophage phi29 genomic DNA into its preformed procapsid requires the DNA packaging motor, which is the strongest known biological motor. The packaging motor is an intricate ring-shaped protein/RNA complex, and its function requires an RNA component called packaging RNA (pRNA). Current structural information on pRNA is limited, which hinders studies of motor function. Here, we used site-directed spin labeling to map the conformation of a pRNA three-way junction that bridges binding sites for the motor ATPase and the procapsid. The studies were carried out on a pRNA dimer, which is the simplest ring-shaped pRNA complex and serves as a functional intermediate during motor assembly. Using a nucleotide-independent labeling scheme, stable nitroxide radicals were attached to eight specific pRNA sites without perturbing RNA folding and dimer formation, and a total of 17 internitroxide distances spanning the three-way junction were measured using Double Electron-Electron Resonance spectroscopy. The measured distances, together with steric chemical constraints, were used to select 3662 viable three-way junction models from a pool of 65 billion. The results reveal a similar conformation among the viable models, with two of the helices (HT and HL) adopting an acute bend. This is in contrast to a recently reported pRNA tetramer crystal structure, in which HT and HL stack onto each other linearly. The studies establish a new method for mapping global structures of complex RNA molecules, and provide information on pRNA conformation that aids investigations of phi29 packaging motor and developments of pRNA-based nanomedicine and nanomaterial.

  20. Characterization of fundamental catalytic properties of MoS2/WS2 nanotubes and nanoclusters for desulfurization catalysis - a surface temperature study

    SciTech Connect (OSTI)

    U. Burghaus

    2012-07-05T23:59:59.000Z

    The prior project consisted of two main project lines. First, characterization of novel nanomaterials for hydrodesulfurization (HDS) applications. Second, studying more traditional model systems for HDS such as vapor-deposited silica-supported Mo and MoSx clusters. In the first subproject, we studied WS2 and MoS2 fullerene-like nanoparticles as well as WS2 nanotubes. Thiophene (C4H4S) was used as the probe molecule. Interestingly, metallic and sulfur-like adsorption sites could be identified on the silica-supported fullerene-particles system. Similar structures are seen for the traditional system (vapor-deposited clusters). Thus, this may be a kinetics fingerprint feature of modern HDS model systems. In addition, kinetics data allowed characterization of the different adsorption sites for thiophene on and inside WS2 nanotube bundles. The latter is a unique feature of nanotubes that has not been reported before for any inorganic nanotube system; however, examples are known for carbon nanotubes, including prior work of the PI. Although HDS has been studied for decades, utilizing nanotubes as nanosized HDS reactors has never been tried before, as far as we know. This is of interest from a fundamental perspective. Unfortunately, the HDS activity of the nanocatalysts at ultra-high vacuum (UHV) conditions was close to the detection limit of our techniques. Therefore, we propose to run experiments at ambient pressure on related nanopowder samples as part of the renewal application utilizing a now-available GC (gas chromatograph) setup. In addition, Ni and Co doped nanocatalyts are proposed for study. These dopants will boost the catalytic activity. In the second subproject of the prior grant, we studied HDS-related chemistry on more traditional supported cluster catalysts. Mo clusters supported by physical vapor deposition (PVD) on silica have been characterized. Two reaction pathways are evident when adsorbing thiophene on Mo and MoSx clusters: molecular adsorption and dissociation. PVD Mo clusters turned out to be very reactive toward thiophene bond activation. Sulfur and carbon residuals form, which poison the catalyst and sulfide the Mo clusters. Sulfided silica-supported MoSx samples are not reactive toward thiophene bond activation. In addition to S and C deposits, H2, H2S, and small organic molecules were detected in the gas phase. Catalyst reactivation procedures, including O2 and atomic hydrogen treatments, have been tested. Cluster size effects have been seen: thiophene adsorbs molecularly with larger binding energies on smaller clusters. However, larger clusters have smaller activation energy for C4H4S bond activation than smaller clusters. The latter is consistent with early catalysis studies. Kinetics and dynamics parameters have been determined quantitatively. We spent a significant amount of time on upgrades of our equipment. A 2nd-hand refurbished X-ray photoelectron spectrometer (XPS) has been integrated into the existing molecular beam scattering system and is already operational (supported by the DoE supplemental grant available in October 2009). We also added a time of flight (TOF) system to the beam scattering apparatus and improved on the accessible impact energy range (new nozzle heater and gas mixing manifold) for the beam scattering experiments. In addition, a GC-based powder atmospheric flow reactor for studies on powder samples is now operational. Furthermore, a 2nd UHV kinetics system has been upgraded as well. In summary, mostly single crystal systems have so far been considered in basic science studies about HDS. Industrial catalysts, however, can be better approximated with the supported cluster systems that we studied in this project. Furthermore, an entirely new class of HDS systems, namely fullerene-like particles and inorganic nanotubes, has been included. Studying new materials and systems has the potential to impact science and technology. The systems investigated are closely related to energy and environmental-related surface science/catalysis. This prior project, conducted at NDSU by a sma

  1. Effects of {pi}-stacking interactions on the near carbon K-edge x-ray absorption fine structure: A theoretical study of the ethylene pentamer and the phthalocyanine dimer

    SciTech Connect (OSTI)

    Linares, Mathieu; Stafstroem, Sven; Norman, Patrick [Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden)

    2009-03-14T23:59:59.000Z

    X-ray absorption spectra have been determined for ethylene and free base phthalocyanine at the carbon K-edge with use of the complex polarization propagator method combined with Kohn-Sham density functional theory and the Coulomb attenuated method B3LYP exchange-correlation functional. Apart from isolated molecules, the study includes {pi}-stacked systems of the phthalocyanine dimer and the ethylene dimer, trimer, tetramer, and pentamer. For ethylene, {pi}-stacking involves a reduction in transition energy of the valence {pi}*-band by some 70 meV and large spectral changes (regarding also shape and intensity) of the Rydberg bands. For phthalocyanine, there are large spectral changes in the entire valence {pi}*-part of the spectrum.

  2. IR mass-resolved spectroscopy of complexes without chromophore: Cyclohexanol·(H{sub 2}O){sub n}, n = 1–3 and cyclohexanol dimer

    SciTech Connect (OSTI)

    León, Iker; Montero, Raúl; Longarte, Asier; Fernández, José A., E-mail: josea.fernandez@ehu.es [Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country-UPV/EHU, Barrio Sarriena s/n, Leioa 48940 (Spain)

    2013-11-07T23:59:59.000Z

    Mass-resolved IR spectra of cyclohexanol-water clusters and cyclohexanol dimer in supersonic expansions are presented for the first time. A combination of ns and fs IR lasers made possible recording such spectra without inclusion of a chromophore or a messenger atom. Furthermore, employment of the recently developed IR{sup 3} technique [I. León, R. Montero, F. Castaño, A. Longarte, and J. A. Fernández, J. Phys. Chem. A 116, 6798 (2012)] allowed us to discriminate between the contribution of different species to the IR spectrum. Comparison of the experimental spectra with the predictions at the M06-2X/6-311++G(d,p) calculation level confirmed the assignment of the spectrum of cyclohexanol·(H{sub 2}O){sub 1} to a structure in which water is accepting a proton from cyclohexanol's OH group, and those of cyclohexanol·(H{sub 2}O){sub 2,3} to structures with cyclic hydrogen bond networks. A comparative analysis of the results obtained with those reported on other aromatic alcohols is also offered.

  3. Scanning tunneling microscopy of dimeric and polymeric products of electroreduced (Re(CO) sub 3 (4-vinyl,4 prime -methyl-2,2 prime -bipyridine)Cl)

    SciTech Connect (OSTI)

    Snyder, S.R.; White, H.S. (Univ. of Minnesota, Minneapolis (USA)); Lopez, S.; Abruna, H.D. (Cornell Univ., Ithaca, NY (USA))

    1990-02-14T23:59:59.000Z

    Scanning tunneling microscopy (STM) was used to image adsorbed products resulting from electroreduction of (Re(CO){sub 3}(vbpy)Cl) (vbpy = 4-vinyl,4{prime}-methyl-2,2{prime}-bipyridine) on highly oriented pyrolytic graphite (HOPG). STM images, in air, of HOPG electrodes following electroreduction of (Re(CO){sub 3}(vbpy)Cl) (in acetonitrile/0.1 M tetra-n-butylammonium perchlorate) by cycling the potential between 0 and {minus}2.0 V vs a sodium saturated colomel electrode (SSCE) show molecular species uniformly distributed on the surface including approximately dumbbell shaped molecules ({approx} 40 {times} 20 {angstrom}). The size and shape of these aggregates is consistent with products derived from vinyl-vinvyl coupling of Re-Re bonded dimers: ((vbpy)(CO){sub 3}Re-Re(CO){sub 3}(vbpyH-vbpyH)(CO){sub 3}Re-Re(CO){sub 3}(vbpy)). STM images of electrodes prepared by cycling the potential between 0 and {minus}1.45 V vs SSCE (less reducing conditions) show highly nonuniform coating of the surface by polymer. Several polymer morphologies were observed with polymer nucleation preferentially occurring at step sites on HOPG.

  4. Photoionization of cold gas phase coronene and its clusters: Autoionization resonances in monomer, dimer, and trimer and electronic structure of monomer cation

    SciTech Connect (OSTI)

    Bréchignac, Philippe, E-mail: philippe.brechignac@u-psud.fr; Falvo, Cyril; Parneix, Pascal; Pino, Thomas; Pirali, Olivier [Institut des Sciences Moléculaires d’Orsay, CNRS UMR8214, Univ Paris-Sud, F-91405 Orsay (France); Garcia, Gustavo A.; Nahon, Laurent [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette (France); Joblin, Christine; Kokkin, Damian; Bonnamy, Anthony [IRAP, Université de Toulouse 3 - CNRS, 9 Av. Colonel Roche, B.P. 44346, F-31028 Toulouse Cedex 4 (France); Mulas, Giacomo [INAF - Osservatorio Astronomico di Cagliari, via della scienza 5, I-09047 Selargius (Italy)

    2014-10-28T23:59:59.000Z

    Polycyclic aromatic hydrocarbons (PAHs) are key species encountered in a large variety of environments such as the Interstellar Medium (ISM) and in combustion media. Their UV spectroscopy and photodynamics in neutral and cationic forms are important to investigate in order to learn about their structure, formation mechanisms, and reactivity. Here, we report an experimental photoelectron-photoion coincidence study of a prototypical PAH molecule, coronene, and its small clusters, in a molecular beam using the vacuum ultraviolet (VUV) photons provided by the SOLEIL synchrotron facility. Mass-selected high resolution threshold photoelectron (TPES) and total ion yield spectra were obtained and analyzed in detail. Intense series of autoionizing resonances have been characterized as originating from the monomer, dimer, and trimer neutral species, which may be used as spectral fingerprints for their detection in the ISM by VUV absorption spectroscopy. Finally, a full description of the electronic structure of the monomer cation was made and discussed in detail in relation to previous spectroscopic optical absorption data. Tentative vibrational assignments in the near-threshold TPES spectrum of the monomer have been made with the support of a theoretical approach based on density functional theory.

  5. Reaction Selectivity in Heterogeneous Catalysis

    E-Print Network [OSTI]

    Somorjai, Gabor A.

    2010-01-01T23:59:59.000Z

    possible adsorption modes of acrolein to a Pt(111) surface,possible adsorption structures of acrolein on Pt(111) energyand 2 Langmuir exposure of acrolein to Pt(111). Figure taken

  6. "Nanocrystal bilayer for tandem catalysis"

    E-Print Network [OSTI]

    Yamada, Yusuke

    2012-01-01T23:59:59.000Z

    Hydrogenolysis of Ethane, Propane, n-Butane and iso-Butanethe Hydroformylation of Propane over Silica-supported Groupproduct and small amount of propane, which is likely to be

  7. Electrochemistry: Catalysis at the boundaries

    SciTech Connect (OSTI)

    Appel, Aaron M.

    2014-04-09T23:59:59.000Z

    Renewable energy provides an opportunity to power society without the potential impacts from the use of fossil fuels, but a major limitation of sources such as solar and wind is their intermittent availability. Efficient storage of energy from these renewable sources is critical in developing their widespread utilization. One approach to the storage of renewable energy is the production of fuels, such as ethanol, from water and carbon dioxide. Unlike traditional centralized fuel production, electrochemical systems can operate under mild pressures and temperatures in dispersed, small-scale reactors. Renewable sources of energy are inherently dispersed, and therefore are well matched with the production of fuels electrochemically. However, the development of efficient catalysts is essential for the intended chemical transformations.

  8. [Studies of supported hydrodesulfurization catalysis

    SciTech Connect (OSTI)

    Not Available

    1992-01-01T23:59:59.000Z

    Research progress is in three areas. First, correlation of the distribution of molybdenum oxidation states in reduced Mo/Al[sub 2]O[sub 3] catalysts with benzene hydrogenation activity. Second, the use of factor analysis curve-fitting to determine the distribution of molybdenum oxidation states educed Mo/TiO[sub 2] catalysts. Third, quantitative Raman and ESCA characterization of W/TiO[sub 2] catalysts.

  9. Neutrons for Catalysis Neutrons as

    E-Print Network [OSTI]

    Pennycook, Steve

    ) decompressor are needed to see this picture. pilot plant new products and processes Q uickTim eTM and a TI FF ( Uncom pr essed) decom pr essor ar e needed t o see t his pict ur e. bench scale cast film in

  10. BNL | CFN: Interface Science & Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    system and the environment. Any solution to these issues will necessarily involve the development of renewable energy sources, together with new strategies for efficient energy...

  11. "Nanocrystal bilayer for tandem catalysis"

    E-Print Network [OSTI]

    Yamada, Yusuke

    2012-01-01T23:59:59.000Z

    Shift Activity of Pt Catalysts Supported on Single (MOx) andComposite (MOx/Al 2O 3 , MOx/TiO 2 ) Metal Oxide Carriers. Catal. Today 127,

  12. This journal is c The Royal Society of Chemistry 2011 Chem. Commun. Cite this: DOI: 10.1039/c0cc05303a

    E-Print Network [OSTI]

    Pandey, Ravi

    05303a One-pot efficient synthesis of dimeric, trimeric, and tetrameric BODIPY dyes for panchromatic for potential solar cell and other applications. In this communication, we report efficient synthesis of dimeric derivatives (3) with an excess of 2,4-dimethyl- pyrrole under acid catalysis, followed by oxidation with 2

  13. Model Catalysis of Ammonia Synthesis ad Iron-Water Interfaces - ASum Frequency Generation Vibrational Spectroscopic Study of Solid-GasInterfaces and Anion Photoelectron Spectroscopic Study of Selected Anionclusters

    SciTech Connect (OSTI)

    Ferguson, Michael James

    2005-12-15T23:59:59.000Z

    The ammonia synthesis reaction has been studied using single crystal model catalysis combined with sum frequency generation (SFG) vibrational spectroscopy. The adsorption of gases N{sub 2}, H{sub 2}, O{sub 2} and NH{sub 3} that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH{sub 2} ({approx}3325 cm{sup -1}) and NH ({approx}3235 cm{sup -1}) under high pressure of ammonia or equilibrium concentrations of reactants and products on Fe(111) surfaces. Special attention was paid to understand how potassium promotion of the iron catalyst affects the intermediates of ammonia synthesis. An Fe(111) surface promoted with 0.2 monolayers of potassium red shifts the vibrational frequencies of the reactive surface intermediates, NH and NH{sub 2}, providing evidence for weakened the nitrogen-hydrogen bonds relative to clean Fe(111). Spectral features of these surface intermediates persisted to higher temperatures for promoted iron surfaces than for clean Fe(111) surfaces implying that nitrogen-iron bonds are stronger for the promoted surface. The ratio of the NH to NH{sub 2} signal changed for promoted surfaces in the presence of equilibrium concentrations of reactants and products. The order of adding oxygen and potassium to promoted surfaces does not alter the spectra indicating that ammonia induces surface reconstruction of the catalyst to produce the same surface morphology. When oxygen is co-adsorbed with nitrogen, hydrogen, ammonia or potassium on Fe(111), a relative phase shift of the spectra occurs as compared to the presence of adsorbates on clean iron surfaces. Water adsorption on iron was also probed using SFG vibrational spectroscopy. For both H{sub 2}O and D{sub 2}O, the only spectral feature was in the range of the free OH or free OD. From the absence of SFG spectra of ice-like structure we conclude that surface hydroxides are formed and no liquid water is present on the surface. Other than model catalysis, gas phase anion photoelectron spectroscopy of the Cl + H{sub 2} van der Waals well, silicon clusters, germanium clusters, aluminum oxide clusters and indium phosphide clusters were studied. The spectra help to map out the neutral potential energy surfaces of the clusters. For aluminum oxide, the structures of the anions and neutrals were explored and for silicon, germanium and indium phosphide the electronic structure of larger clusters was mapped out.

  14. SOUTHWEST CATALYSIS SOCIETY 2008 SPRING SYMPOSIUM

    E-Print Network [OSTI]

    Natelson, Douglas

    for registration (membership due included). Group registration can be accommodated on-site; the group, Micromeritics) 10:05 AM Gary Gildert (Custom Catalytic Solution Inc., La Porte, TX) The Seven Steps

  15. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    n Schematic Drawing of Fixed Bed Cracking Unit BL The suddenThe cyclic operation of the fixed bed units was replaced byprocess was operated in a fixed-bed configuration. The major

  16. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    coal is dissolved in a recycle solvent containing largely aromatic and hydroaromatic hydrocarbons, and the resulting solution and/or slurry

  17. Method for producing catalysis from coal

    DOE Patents [OSTI]

    Farcasiu, Malvina (Pittsburgh, PA); Derbyshire, Frank (Lexington, KY); Kaufman, Phillip B. (Library, PA); Jagtoyen, Marit (Lexington, KY)

    1998-01-01T23:59:59.000Z

    A method for producing catalysts from coal is provided comprising mixing an aqueous alkali solution with the coal, heating the aqueous mixture to treat the coal, drying the now-heated aqueous mixture, reheating the mixture to form carbonized material, cooling the mixture, removing excess alkali from the carbonized material, and recovering the carbonized material, wherein the entire process is carried out in controlled atmospheres, and the carbonized material is a hydrocracking or hydrodehalogenation catalyst for liquid phase reactions. The invention also provides for a one-step method for producing catalysts from coal comprising mixing an aqueous alkali solution with the coal to create a mixture, heating the aqueous mixture from an ambient temperature to a predetermined temperature at a predetermined rate, cooling the mixture, and washing the mixture to remove excess alkali from the treated and carbonized material, wherein the entire process is carried out in a controlled atmosphere.

  18. Nanoscale Advances in Catalysis and Energy Applications

    E-Print Network [OSTI]

    Li, Yimin

    2011-01-01T23:59:59.000Z

    State  Dye-­‐Sensitized  Solar  Cells.   Chemsuschem, in  dye-­‐sensitized  solar  cells  with  energy by  dye-­‐sensitized  photovoltaic  cells.  

  19. Lean NOx Catalysis Research and Development

    Broader source: Energy.gov (indexed) [DOE]

    temperature range, poorly selective (N 2 O) Zeolites (ex. Cu-ZSM-5) active, selective hydro-thermally unstable Metal oxides (ex. AgAl 2 O 3 ) highly selective, stable,...

  20. Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis...

    Energy Savers [EERE]

    the Whole BarrelTo Reduce U.S. Dependence on Oil Breaking the Biological Barriers to Cellulosic Ethanol, June 2006 Breaking the Biological Barriers to Cellulosic Ethanol, June 2006...

  1. BERKELEY CATALYSIS CENTER Distinguished Lecture Series

    E-Print Network [OSTI]

    Iglesia, Enrique

    of a lean pre-burner and highly efficient fuel/air mixer. PdO catalysts under operation for power generation to Commercialization and Back ABSTRACT: The November 2002 start-up of a 1.4-MW Kawasaki gas turbine with a Xonon combustion device for power generation after almost 30 years of R&D world-wide. The module in the 9.5-atm KHI

  2. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    greater in chemical and petrochemical applications than inMonomers Olefin Petrochemicals Bimetallic reformingsales and values; for the Petrochemical Industry (Table B) X

  3. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    glycol, propylene oxide, acrolein, acrylic acid, and1n 1948 the product1on of acrolein from propylene and oxygenIdol who reported yields of acrolein than those obtained in

  4. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    from methane, naphtha, heavy oil, and coal has achievedare suspended in a heavy oil. High-per-pass conversions (95%the catalytic cracking of heavy gas oils can be saturated,

  5. N-heterocyclic carbene catalysis: expansion of

    E-Print Network [OSTI]

    Ogle, James William

    2009-05-15T23:59:59.000Z

    to develop new N-heterocyclic carbene catalysts was developed using the cyanide coupling of aldimines to generate electronically tunable 1,3,4,5-tetraaryl complexes, and X-ray, IR, and calculations were used to elucidate their electronic characteristics...

  6. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    that were suspended in a molten salt heat exchanger, . F'catalyst containers in molten salt medium. Figure taken franwater. The copper salts are molten and sorbed in the alumina

  7. Catalysis over activated high silica zeolites

    SciTech Connect (OSTI)

    Chang, C. D.; Miale, N.

    1985-07-23T23:59:59.000Z

    A process is provided for conducting organic compound conversion over a catalyst composition comprising a crystalline zeolite having a high initial silica-to-alumina mole ratio, said zeolite being prepared by calcining the zeolite, contacting said calcined zeolite with solid aluminum fluoride, and coverting said aluminum fluoride contacted material to hydrogen form.

  8. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    and Weisz, P. B. Oil and Gas Journal, 1968, 66(47), 147.Stein, T. R. , . Rev. Oil Gas Journal, June 6, 1977. Chang,s. and Banks, R. L. Oil Gas Journal, 1968, 66(21), 131. c.

  9. [Studies of supported hydrodesulfurization catalysis]. Progress report

    SciTech Connect (OSTI)

    Not Available

    1991-12-31T23:59:59.000Z

    Research progress to be reviewed here will be in three areas. First, correlation of the distribution of molybdenum oxidation states in reduced Mo/Al{sub 2}O{sub 3} catalysts with benzene hydrogenation activity. Second, the use of factor analysis curve-fitting to determine the distribution of molybdenum oxidation states in reduced Mo/TiO{sub 2} catalysts. Third, quantitative Raman and ESCA characterization of W/TiO{sub 2} catalysts.

  10. [Studies of supported hydrodesulfurization catalysis]. Progress report

    SciTech Connect (OSTI)

    Not Available

    1992-12-01T23:59:59.000Z

    Research progress is in three areas. First, correlation of the distribution of molybdenum oxidation states in reduced Mo/Al{sub 2}O{sub 3} catalysts with benzene hydrogenation activity. Second, the use of factor analysis curve-fitting to determine the distribution of molybdenum oxidation states educed Mo/TiO{sub 2} catalysts. Third, quantitative Raman and ESCA characterization of W/TiO{sub 2} catalysts.

  11. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    production of styrene in the United States lay in the critical need for a substitute for natural rubber

  12. CATALYSIS IN BIOPOLYMER CHEMISTRY Joseph Bartholomew Binder

    E-Print Network [OSTI]

    Raines, Ronald T.

    -organic solvent mixtures. The combination of the second-generation Hoveyda-Grubbs complex and solvents such as 1 civilization. Production of renewable building blocks through such transformations is the focus of the second yields the liquid fuel 2,5-dimethylfuran, offering a two-step direct route from biomass to biofuels

  13. Two component-three dimensional catalysis

    DOE Patents [OSTI]

    Schwartz, Michael (Boulder, CO); White, James H. (Boulder, CO); Sammells, Anthony F. (Boulder, CO)

    2002-01-01T23:59:59.000Z

    This invention relates to catalytic reactor membranes having a gas-impermeable membrane for transport of oxygen anions. The membrane has an oxidation surface and a reduction surface. The membrane is coated on its oxidation surface with an adherent catalyst layer and is optionally coated on its reduction surface with a catalyst that promotes reduction of an oxygen-containing species (e.g., O.sub.2, NO.sub.2, SO.sub.2, etc.) to generate oxygen anions on the membrane. The reactor has an oxidation zone and a reduction zone separated by the membrane. A component of an oxygen containing gas in the reduction zone is reduced at the membrane and a reduced species in a reactant gas in the oxidation zone of the reactor is oxidized. The reactor optionally contains a three-dimensional catalyst in the oxidation zone. The adherent catalyst layer and the three-dimensional catalyst are selected to promote a desired oxidation reaction, particularly a partial oxidation of a hydrocarbon.

  14. Catalysis: UHV Model Catalysts, High Pressure | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    an Omicron EA 125 multichannel energy analyzer. A non-monochromatic Phi Model 04-548 dual (magnesium and aluminum) anode X-ray source and a Kimball Physics Model ILG-2 ion gun...

  15. Catalysis using hydrous metal oxide ion exchangers

    DOE Patents [OSTI]

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21T23:59:59.000Z

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  16. BERKELEY CATALYSIS CENTER March 29, 2005

    E-Print Network [OSTI]

    Iglesia, Enrique

    hydrocarbon fuels into syngas at short contact times: design of monolithic catalysts and process parameters including heat ­ and electric current- conducting ones were designed. The active components are comprised of 800-1100 oC and short contact times, catalysts ensure the equilibrium composition of reformate being

  17. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    process technology is far greater in chemical and petrochemicalprocesses such as hydrotreating and hydrocrack.ing, and for petrochemical

  18. Postdoctoral Scholar position Area: Heterogeneous Catalysis

    E-Print Network [OSTI]

    de Leon, Alex R.

    : Immediately Salary: $40,000-$50,000 per year(plus benefits) The Department of Chemical and Petroleum with high performance and novel catalytic processes for efficient energy utilization in an economical evaluation as well as reactor system design and fabrication Creative problem-solving and strong critical

  19. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    Dealkylation Catalytic Coal Liquefaction and Gasification a)Liquefaction Gasification c) IX Methanation Heterogeneous~IQUEFACTION AND GASIFICATION a) Liquefaction Production of

  20. BERKELEY CATALYSIS CENTER November 11, 2005

    E-Print Network [OSTI]

    Iglesia, Enrique

    improving efficiency. Since no combustion is required no primary pollutants are formed. Furthermore CO2 emissions. The desire for enhanced fuel economy and lower emission of greenhouse gases has suggested) directly to electricity and heat avoiding the thermodynamic limitations imposed by the Carnot Cycle greatly

  1. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    this by ion exchanging rare earth metals for alkali meta lChlorides of rare earths and alkali metals often serve as

  2. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    in a solvent, and the Fischer-Tropsch process involving theWorld War II, and a Fischer-Tropsch plant was built in South50) Conventional iron-type Fischer-Tropsch catalysts are

  3. BERKELEY CATALYSIS CENTER Distinguished Lecture Series

    E-Print Network [OSTI]

    Iglesia, Enrique

    is a subject of great practical importance in the chemical and petrochemical industry. Porous materials propane (CHA) and carbon dioxide from methane (DDR). These separations are of great practical importance

  4. SOUTHWEST CATALYSIS SOCIETY 2006 SPRING SYMPOSIUM

    E-Print Network [OSTI]

    Natelson, Douglas

    XIAO TOTAL PETROCHEMICALS USA, INC. RESEARCH & TECHNOLOGY CENTER Deer Park, TX 77536 (281) 884 in Methane Reactions Catalyzed by Supported Metal Clusters" 8:50 AM Dr. Jon G. McCarty, Catalytica Energy

  5. A BRIEF HISTORY OF INDUSTRIAL CATALYSIS

    E-Print Network [OSTI]

    Heinemann, Heinz

    2013-01-01T23:59:59.000Z

    Gasification In coal gasification there are two worthwhiledemonstrated. Many coal gasification plants are in operationCatalytic Coal Liquefaction and Gasification a) Liquefaction

  6. Basic Research Needs: Catalysis for Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    solar energy to electrical energy at acceptable low costs. Many of these third- generation solar conversion strategies require the fabrication of interdigitated...

  7. Catalysis: Fundamentals and Impact | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    food, chemicals, fuels, pharmaceuticals and engineered materials including almost all plastics, polymers, and fibers. Catalysts are able to transform large quantities of matter...

  8. Catalysis and Synthesis | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for better catalysts has deep connections to our nation's economy. From biofuels to plastics, the majority of the products we depend on in our everyday lives rely on catalysts....

  9. Catalysis Working Group | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742Energy China U.S. Department ofJuneWaste To Wisdom:EnergyJoshuaThis work plan proposesThe

  10. Nanomaterials Engineering and Applications in Catalysis

    E-Print Network [OSTI]

    Zhang, Qiao

    2012-01-01T23:59:59.000Z

    75 Although direct photocatalysis utilizing such plasmoniclittle investigated. In photocatalysis research, anatase TiOthe perspective of photocatalysis, there are also several

  11. Workshop: Synchrotron Applications in Chemical Catalysis | Stanford

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengtheningWildfires may contribute more to &83Stanford

  12. CNEEC - TRG3: Nanoscale Control in Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced. C o w l i t z C o . C l a r k CCLEAN9 HighAnalysis

  13. Opportunities in Catalysis Research Using Synchrotron Radiation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for RenewableSpeeding accessSpeedingOctoberResearchOpen→and Technology, AOT:in

  14. Crystal Structures of Binary and Ternary Complexes of Thymidylate Synthase (ThyA) from Mycobacterium tuberculosis: Insights into Selectivity and Inhibition

    E-Print Network [OSTI]

    Harshbarger, Wayne

    2012-10-19T23:59:59.000Z

    -sheets, including the dimer interface which is a beta-sandwich. Examination of the dUMP binding site allowed the identification of key conserved residues that play a role in ligand binding and catalysis. Comparison of the dUMP-Pemetrexed ternary complex...

  15. Inorg. Chem. 1989, Monomer TI Dimer Monomer

    E-Print Network [OSTI]

    , Pas- adena, CA, under contract with the National Aeronautics and Space Administration. Registry No

  16. Matching, Edge-Colouring, Dimers Alexander Schrijver

    E-Print Network [OSTI]

    Schrijver, Alexander

    into PZrMDEA blends. We2 December 2002 Vol. 48, No. 12 AIChE Journal2788 #12;specifically target exp

  17. Role of Periaxin dimerization in peripheral myelination 

    E-Print Network [OSTI]

    Wu, Lai Man Natalie

    2012-06-22T23:59:59.000Z

    In the peripheral nervous system (PNS), Schwann cells ensheathe and myelinate axons to promote saltatory conduction of nerve impulses. Close interactions between Schwann cells and axons, and Schwann cells and the basal ...

  18. PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)

    E-Print Network [OSTI]

    Africa, 59%; United Kingdom,14%; Russia, 9%; Germany, 5%; and other, 13%. Palladium: Russia, 48%; South the ore body, about 18,500 feet from the portal entrance, by the end of 1999. A second TBM also began

  19. PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)

    E-Print Network [OSTI]

    to convert hydrogen and oxygen to electricity. Palladium will also likely play a role in the fuel cell on gasoline-engine vehicles in favor of palladium. The sales of platinum jewelry are expected to drop

  20. CO oxidation on ruthenium: The nature of the active catalytic...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    has been extensively studied over the last several decades from ultrahigh (UHV) vacuum to ambient pressures. While Ru is an inferior catalyst for this reaction compared to...

  1. Electrooxidation of Alcohols Catalyzed by Amino Alcohol Ligated Ruthenium Complexes

    E-Print Network [OSTI]

    Zare, Richard N.

    Alcohols are attractive chemical fuels for fuel cells due to their high energy densities, established, even the most highly optimized alcohol electrooxidation catalysts suffer from kinetic limitations

  2. Selective Lability of Ruthenium(II) Arene Amino Acid Complexes

    E-Print Network [OSTI]

    Scrase, Tom G.; O’Neill, Michael J.; Peel, Andrew J.; Senior, Paul W.; Matthews, Peter D.; Shi, Heyao; Boss, Sally R.; Barker, Paul D.

    2015-02-16T23:59:59.000Z

    (DAP) 1 -NH2 2 L-2,4-diamino-butanoic acid (DAB) 2 -NH2 3 L-Ornithine 3 -NH2 4 L-Lysine 4 -NH2 5 L-Histidine 2 -Imidazole 6 L-Methionine 2 -SMe 7 * L-Aspartate 2 -COO- Table 1: Summary of the tridentate amino acid complexes under investigation...

  3. PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)

    E-Print Network [OSTI]

    and private effort to develop fuel cell technology. Platinum is the catalyst used in fuel cells to convert for air-pollution abatement in both light- and heavy-duty vehicles. PGMs are also used in the chemical. The desire for an alternative fuel, both for automobiles and to power homes, has led to a large global public

  4. PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)

    E-Print Network [OSTI]

    public and private effort to develop fuel cell technology. Platinum is the catalyst used by fuel cells Events, Trends, and Issues: The desire for an alternative fuel for automobiles has led to a large global platinum loadings on catalysts, especially in light-duty diesel vehicles, as particulate matter emissions

  5. LASER TRANSFERRED HYDROUS RUTHENIUM OXIDE ELECTRODES FOR MICRO-ULTRACAPACITORS

    E-Print Network [OSTI]

    Arnold, Craig B.

    products and telecommunication devices to electric/hybrid vehicles and stand-by power systems is also critical for the operation of autonomous microelectronic systems such as microsensors. These requirements are unable to be met by the current generation of microbatteries or micro-fuel cells alone (4, 5

  6. PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)

    E-Print Network [OSTI]

    and demand. With a short supply, the price of rhodium surged to a 5-year high. An increase in diesel car. Catalysts for air pollution abatement continued to be the leading demand sector for PGMs. In the United in 2004, palladium prices fell in 2005 because of weak demand and oversupply. Meanwhile, the platinum

  7. PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)

    E-Print Network [OSTI]

    and processors to form the Palladium Council (PdC). PdC is a nonprofit research foundation organized for the purpose of conducting research and promoting the use of palladium. PdC research and development

  8. Ruthenium on Carbon Nanostructures for Supercapacitor Electrodes - Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiation Protection TechnicalResonantNovember 15Rotary Firing

  9. Thermoelectric Properties of Rare-Earth-Ruthenium-Germanium Compounds |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening a solidSynthesis of 2DandEnergy ThereceiverInnovationEnergy

  10. Charge Transfer and Catalysis at the Metal-Support Interface

    E-Print Network [OSTI]

    Baker, Lawrence Robert

    2012-01-01T23:59:59.000Z

    potential, and photovoltaic efficiency. Rectification factordepicted in Fig. 1A. Photovoltaic efficiency is determinedthe power conversion efficiency of the photovoltaic device.

  11. FIRST BERKELEY CATALYSIS AND SURFACE SCIENCE CONFERENCE JULY 1980

    E-Print Network [OSTI]

    Authors, Various

    2013-01-01T23:59:59.000Z

    the requirements: the fixed-bed tubular reactor. developedthe slurry-bed reactor. The fixed-bed and fluid-bed reactorsanswer and either the fixed-bed or the slurry-bed reactor

  12. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    and downstream properties of these materials. This is because the molecular composition is an optimal starting comes with a large requirement for model construction and solution time as well as analytical and reactivity information. The challenge of building molecule-based models is due to the staggering complexity

  13. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Development of catalyst materials to facilitate the low-temperature oxidation of hydrocarbons and CO in homogeneous charge compression ignition (HCCI) emissions. deer08...

  14. Hybrid Porous Materials for Controlled Release and Catalysis

    E-Print Network [OSTI]

    Liu, Rui

    2010-01-01T23:59:59.000Z

    report a novel supramolecular nanogated material responsivemulti-responsive supramolecular nanogating hydrid materialssilica materials as solid supports and supramolecular

  15. Progress in transition metal-based enantioselective catalysis

    E-Print Network [OSTI]

    Arp, Forrest O

    2008-01-01T23:59:59.000Z

    In Chapter 1, the first enantioselective cross-coupling reactions of racemic secondary benzylic halides are described (eq 1). This method was applied to the syntheses of intermediates employed by other groups in the ...

  16. The Interplay of Catalysis and Toxicity by Amyloid

    E-Print Network [OSTI]

    Miranker, Andrew

    Words IAPP, amylin, protein folding, -synuclein, A, mechanism Abstract The dynamics, energies, and structures governing protein folding are critical to biological function. Amyloidoses are a class of disease #12;Contents PROTEIN FOLDING DEFINED . . . 126 PROTEIN MISFOLDING AS A BASIS FOR DISEASE

  17. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    times science has used high-brilliance x-rays to look so closely at these reactions. Lead author Dr. David Mueller at the ALS using x-rays to characterize working fuel cells....

  18. JOURNAL OF CATALYSIS 178, 499510 (1998) ARTICLE NO. CA982161

    E-Print Network [OSTI]

    Iglesia, Enrique

    1998-01-01T23:59:59.000Z

    ). The dehydration of ethanol to ethylene, and the coupling and dehydration to diethyl ether increased with Al con activity and selectivity of Mg-Al mixed oxides in ethanol conversion reac- tions depended on composition. The dehydrogenation of ethanol to acetaldehyde and the aldol condensation to n-butanol both in- volved the initial

  19. Neutron Catalysis of Resonance Fusion in Stellar Matter

    E-Print Network [OSTI]

    Nurgali Takibayev

    2005-08-22T23:59:59.000Z

    Within the framework of resonance fusion study in stellar matter the features of system consisted of two alpha particles and one neutron have been investigated at astrophysical energies. Consideration of three body scattering has been carried out on base of well-known Faddeev's equations. It is found that under certain conditions the series of resonance states appear in this system at very low energies. The lifetimes of these three body resonances are close to the lifetime of unstable nucleus 8Be. The simple forms of two body repulsive potentials are taken into account to describe the parameters of the alpha, alpha resonance and to satisfy n, alpha scattering data at very low energies. The explanation of resonance phenomena in n, alpha, alpha system is offered on base of physical model. The effect results from resonance quantum phenomena in few body dynamics. In turn, the resonance fusion can give influence on many astrophysical phenomena. The possibility of catalyzing this new mode of fusion by free neutrons in alpha particle matter is considered too.

  20. Continuous Isosorbide Production From Sorbitol Using Solid Acid Catalysis

    SciTech Connect (OSTI)

    Williamson, R.; Holladay,J.; Jaffe, M.; Brunelle, D.

    2006-09-29T23:59:59.000Z

    This is a final report for a project funded by the US Department of Agriculture and managed by the US Department of Energy. The Iowa Corn Promotion Board was the principal contracting entity for the grant. The Iowa Corn Promotion Board subcontracted with General Electric, Pacific Northwest National Lab and New Jersey Institute of Technology to conduct research in this project. The Iowa Corn Promotion Board and General Electric provided cost share for the project. The purpose of this diverse collaboration was to integrate both the conversion and the polymer applications into one project and increase the likelihood of success. This project has led to additional collaborations among other polymer companies. The goals of the project were to develop a renewable route to isosorbide for commercialization that is economically competitive with all existing production technologies and to develop new applications for isosorbide in various products such as polymers and materials. Under this program a novel process for the production of isosorbide was developed and evaluated. The novel process converts corn based sorbitol into isosorbide using a solid catalyst with integrated water removal and product recovery. In addition the work under this program has identified several novel products based on isosorbide chemistries. These market applications include: epoxy resins, UV stabilizers, plasticizers and polyesters. These market applications have commercial interest within the current polymer industry. This report contains an overview summary of the accomplishments. Six inventions and four patent applications have been written as a result of this project. Additional data will be published in the patent applications. The data developed at New Jersey Institute of Technology was presented at two technical conferences held in June of 2006. Several companies have made inquiries about using this material in their products.

  1. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    on developing new catalytic conversion technologies for renewable biomass-derived feedstocks and activation Abstract The (CH2O)n stoichiometry of biomass implies that its conversion to energy carriers and other for molecular hydrogen for biomass deoxygenation while biomass serves as the oxygen carrier for hydrogen removal

  2. Isolated Palladium Atoms Allow Highly-Selective Catalysis of...

    Office of Science (SC) Website

    a general strategy for designing novel bifunctional heterogeneous catalysts for the production of fuels, agricultural chemicals and medicine. By controlling changes to the amount...

  3. FIRST BERKELEY CATALYSIS AND SURFACE SCIENCE CONFERENCE JULY 1980

    E-Print Network [OSTI]

    Authors, Various

    2013-01-01T23:59:59.000Z

    probably the most versatile petrochemical at the disposal ofbuilding blocks for petrochemicals and substitute naturalapplications in the petrochemical and petroleum refining

  4. Heterogeneous Catalysis DOI: 10.1002/anie.201101378

    E-Print Network [OSTI]

    Oxidation The toxic character of CO, which is produced in large amounts from the emerging petrochemical

  5. Role of adsorption in catalysis: applications of NMR relaxometry

    E-Print Network [OSTI]

    Arias Vecino, Pablo

    2015-06-09T23:59:59.000Z

    for the desired products. A successful example is the three-way catalyst, which effectively reduces pollution from car engines (Niemantsverdriet, 2000). Other important processes involving heterogeneous catalysts include the Haber-Bosch process for ammonia... against the %d-character, defined as the contribution of the d-electrons to the spd hybrid orbitals in Resonance Band Valence Theory. The figure shows a volcano-shaped plot, indicative of the differences between weak adsorption vs. hindered desorption...

  6. Catalysis of 6? Electrocyclizations & Catalytic Disproportionation of Lignin Model Compounds

    E-Print Network [OSTI]

    Bishop, Lee

    2010-01-01T23:59:59.000Z

    that the use of a silyl deuteride would provide a marker forusing triethylsilyl deuteride (Scheme 15, top). A controlScientific; triethylsilyl deuteride (97% D) was obtained

  7. Frontiers in Catalysis Science and Engineering Seminar Series

    E-Print Network [OSTI]

    dioxide to liquid fuels using solar and electrical energy is a global challenge that could impact contained in liquid fuels to electrical energy in fuel cell applications. Recent results in the study the carbon balance by recycling CO2 as fuels. A related challenge is the direct conversion of chemical energy

  8. Theoretical Study on Catalysis by Protein Enzymes and Ribozyme

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    was found to be energetically unfavorable due to the presence of His95. We also applied variational transition state theory (VTST) to investigate the effect of tunneling...

  9. Fundamental Studies in Catalysis Enabled the use of Efficient...

    Office of Environmental Management (EM)

    that has significantly reduced harmful emissions from many of today's fuel-efficient diesel engines. The same research program also advanced the foundational understanding of...

  10. Enantioselective nickel catalysis : exploiting activated C-H bonds

    E-Print Network [OSTI]

    Bencivenga, Nicholas Ernest

    2012-01-01T23:59:59.000Z

    A method for the nickel-catalyzed cross-coupling between benzoxazole and secondary halides was explored. This method was to make use of the activated C-H bond found in benzoxazole at the 2-position to generate the nucleophilic ...

  11. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOE Patents [OSTI]

    Hilsenbeck, S.J.; McCarley, R.E.; Schrader, G.L.; Xie, X.B.

    1999-02-16T23:59:59.000Z

    New amorphous molybdenum/tungsten sulfides with the general formula M{sup n+}{sub 2x/n}(L{sub 6}S{sub 8})S{sub x}, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M{sub 6}S{sub 8}){sup 0} cluster units are present. Vacuum thermolysis of the amorphous Na{sub 2x}(Mo{sub 6}S{sub 8})S{sub x}{hor_ellipsis}yMeOH first produces poorly crystalline NaMo{sub 6}S{sub 8} by disproportionation at 800 C and well-crystallized NaMo{sub 6}S{sub 8} at {>=} 900 C. Ion-exchange of the sodium material in methanol with soluble M{sup 2+} and M{sup 3+} salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M{sup n+}{sub 2x/n}(Mo{sub 6}S{sub 8})S{sub x}{hor_ellipsis}yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M{sup n+}{sub 2x/n}Mo{sub 6}S{sub 8+x}(MeOH){sub y}[MMOS] (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as ``Chevrel phase-like`` in that both contain Mo{sub 6}S{sub 8} cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst is shown to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS{sub 2} catalysts. 9 figs.

  12. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOE Patents [OSTI]

    Hilsenbeck, Shane J. (Ames, IA); McCarley, Robert E. (Ames, IA); Schrader, Glenn L. (Ames, IA); Xie, Xiaobing (College Station, TX)

    1999-02-16T23:59:59.000Z

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y ›MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  13. Polyisobutylene as a Polymer Support for Homogeneous Catalysis

    E-Print Network [OSTI]

    Hongfa, Chayanant

    2010-01-14T23:59:59.000Z

    and filtration. PEG is insoluble in hexane, diethyl ether, tert-butylmethyl ether (TBME), isopropyl alcohol, and cold ethanol. These are the solvents usually used for the precipitation process. 14 PEG is usefully soluble in a wide range of solvents... (>80% ee) and high yield (>80%). The PEG-bound Cinchona alkaloid 6 was recovered (8) 11 by solvent precipitation with diethyl ether and recycled through five cycles with p- chlorostyrene as a substrate. The average yield of all 5 cycles was 93...

  14. Charge Transfer and Support Effects in Heterogeneous Catalysis

    E-Print Network [OSTI]

    Hervier, Antoine

    2012-01-01T23:59:59.000Z

    titanium  oxide  electronic  structure  show  that  the  energy and energy applications. 1–3   Among TMOs, titanium  oxide energy  dependent  imaginary  dielectric  functions  obtained  by  spectroscopic  ellipsometry  for  undoped  titanium 

  15. Charge Transfer and Catalysis at the Metal-Support Interface

    E-Print Network [OSTI]

    Baker, Lawrence Robert

    2012-01-01T23:59:59.000Z

    of titanium oxide films with a high Fermi energy and anthe titanium oxide electronic structure show that the energyand energy applications. 1–3 Among TMOs, titanium oxide has

  16. The Role of Catalyst Surface Structure in Heterogeneous Catalysis...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ceria Nanocrystals as Catalyst and Catalyst Support Apr 23 2014 10:00 AM - 11:00 AM Zili Wu, Chemical Science Division and Center for Nanophase Materials Sciences, ORNL Materials...

  17. VISCOELASTICITY OF POLYETHYLENES PRODUCED WITH SINGLE SITE METALLOCENE CATALYSIS

    E-Print Network [OSTI]

    of the processability characteristics of these two new LLDPEs. Introduction After initial commercialization in the 1940 in the control of distributions of short chain branching (SCB) and long chain branching (LCB) in the polymer [1

  18. Nanostructured transition metal oxides useful for water oxidation catalysis

    DOE Patents [OSTI]

    Frei, Heinz M; Jiao, Feng

    2013-12-24T23:59:59.000Z

    The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

  19. Tandem Catalysis in Nanocrystal Interfaces | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    Recently, researchers at the Department's Lawrence Berkeley National Laboratory (LBNL) created bilayered nanocrystals of metal-oxide metal that are first to feature multiple...

  20. Charge Transfer and Catalysis at the Metal-Support Interface

    E-Print Network [OSTI]

    Baker, Lawrence Robert

    2012-01-01T23:59:59.000Z

    of C=O bond activation is Fischer– Tropsch synthesis for theas the feedstock for Fischer– Tropsch synthesis, the net