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Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
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1

Blue Ruthenium Dimer Catalysis for Hydrogen Generation | Advanced Photon  

NLE Websites -- All DOE Office Websites (Extended Search)

A High-Pressure Nano-imaging Breakthrough A High-Pressure Nano-imaging Breakthrough Protein Structure Could Lead to Better Treatments for HIV, Early Aging The Superpower behind Iron Oxyfluoride Battery Electrodes Watching a Protein as it Functions Shedding Light on Chemistry with a Biological Twist Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 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 intermediates in the water oxidation catalytic cycle of the blue dimer characterized by x-ray spectroscopy. Optimization of the reactivity toward water (purple arrow) and oxidation of the resulting peroxo-intermediate (blue arrow) are needed for improved catalytic activity.

2

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

SciTech Connect

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.

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

3

UHV and electrochemical studies of CO and methanol adsorbed at platinum/ruthenium surfaces, and reference to fuel cell catalysis  

Science Journals Connector (OSTI)

This paper reviews surface chemistry of carbon monoxide and methanol in ultra high vacuum (UHV) and in the electrochemical environment on clean and Ru modified Pt single crystal surfaces, and on Pt and Pt/Ru nanoparticles. The results show that CO behaves very similarly in UHV and in the electrochemical environment. Cyclic voltammetry (CV), temperature programmed desorption (TPD) and radioactive labeling all show similar behavior in terms of numbers of peaks, peak splitting etc. Both UHV and CV measurements show that there is about a 200-meV change in the potential for CO removal in the presence of ruthenium. Earlier 13C EC-NMR data indicated a 30% reduction in the Ef-LDOS of CO bound to Ru islands deposited on platinum, and 15% of CO bound to Pt sites, and TPD and CV also show that the binding of CO is modified. The present data confirm that Pt atoms away from Ru are only weakly affected, and the overall CO binding energy modification is quite moderate. We conclude that the changes in the CO binding energy only play a small role in enhancing methanol electrooxidation rates. Instead, the main effect of the ruthenium is to activate water to form OH. Quantitative estimates of the reduction in CO desorption barrier indicate that the effect of bifunctional mechanism is about four times larger than that of ligand effect. In contrast to the results for CO, methanol behaves quite differently in UHV and in an electrochemical environment. Pt(111) is unreactive at room temperature in UHV, while Pt(110) is quite reactive. Initially, clean Pt(111) is less reactive than clean Pt(110) even in the electrochemical environment. However, Pt(110) is quickly poisoned in the electrochemical environment, so at steady state, Pt(111) is more reactive than Pt(110). Another issue is that the mechanism of methanol decomposition is quite different in UHV and in the electrochemical environment. There are three pathways in UHV, a simple decomposition via a methoxonium (CH3O?(ad)) intermediate, an SN1 pathway via a methoxonium cation ([CH3OH2]+), and an SN2 pathway via a methoxonium intermediate. So far, none of these pathways have been observed in an electrochemical environment. Instead, the decomposition goes mainly through a hydroxymethyl (?CH2OH(ad)) intermediate. These results show that there are both similarities and differences in the behavior of simple molecules in UHV and in the electrochemical environment.

P. Waszczuk; G.-Q. Lu; A. Wieckowski; C. Lu; C. Rice; R.I. Masel

2002-01-01T23:59:59.000Z

4

Ruthenium-Catalyzed ROM?RCM of Cycloalkene-yne  

Science Journals Connector (OSTI)

Ruthenium-Catalyzed ROM?RCM of Cycloalkene-yne ... ROM?RCM (ring-opening and ring-closing metatheses) of cycloalkene-yne was demonstrated using a second-generation ruthenium complex. ... When cycloalkene bearing the alkyne moiety at the C-1 position was reacted with a ruthenium?carbene complex under an atmosphere of ethylene, ROM?RCM proceeded smoothly to give bicyclic compound and/or dimeric compound in good yields. ...

Miwako Mori; Yuichi Kuzuba; Tsuyoshi Kitamura; Yoshihiro Sato

2002-10-04T23:59:59.000Z

5

catalysis | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

catalysis catalysis Leads No leads are available at this time. Magnesium behavior and structural defects in Mg+ ion implanted silicon carbide. Abstract: As a candidate material for...

6

EMSL - catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

catalysis en Duets by molecules and plasmons http:www.emsl.pnl.govemslwebnewsduets-molecules-and-plasmons

7

Catalysis Workshop  

NLE Websites -- All DOE Office Websites (Extended Search)

Opportunities in Catalysis Research Using Synchrotron Radiation Opportunities in Catalysis Research Using Synchrotron Radiation Stanford Synchrotron Radiation Laboratory October 8-9, 2002 Organizer: Anders Nilsson Chemical catalysis is one of the research areas of enormous importance for the industrial society. There are important challenges to be met in the near future where development of new processes and catalysts are a necessity. We need to find a way to make methanol from methane, split water into hydrogen using sunlight, find replacement of platinum metals, etc. The fundamental understanding of many catalytic processes is still emerging and there seems to be a new opportunity with the recent development in experimental and theoretical methods. The intention of workshop was to bring researchers from many different disciplines together to discuss how synchrotron radiation can be applied to address some fundamental questions in catalysis.

8

INSTITUTE FOR INTEGRATED CATALYSIS Catalysis Research for  

E-Print Network (OSTI)

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

9

Organotextile Catalysis  

Science Journals Connector (OSTI)

...1242196 Ji-Woong Lee Thomas Mayer-Gall Klaus Opwis Choong Eui Song Jochen Stefan Gutmann Benjamin List 1Max-Planck-Institut...Catalysis Ji-Woong Lee, Thomas Mayer-Gall, Klaus Opwis, Choong Eui Song, Jochen Stefan Gutmann, Benjamin List Materials/Methods...

Ji-Woong Lee; Thomas Mayer-Gall; Klaus Opwis; Choong Eui Song; Jochen Stefan Gutmann; Benjamin List

2013-09-13T23:59:59.000Z

10

Synthesis and Hydrodeoxygenation Properties of Ruthenium Phosphide...  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrodeoxygenation Properties of Ruthenium Phosphide Catalysts. Synthesis and Hydrodeoxygenation Properties of Ruthenium Phosphide Catalysts. Abstract: Ru2PSiO2 and RuPSiO2...

11

Enzyme catalysis Enzyme catalysis is the catalysis of chemical reactions by  

E-Print Network (OSTI)

Enzyme catalysis Enzyme catalysis is the catalysis of chemical reactions by specialized proteins known as enzymes. Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions. The mechanism of enzyme catalysis is similar in principle to other

Cavanagh, John

12

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

SciTech Connect

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.

Pant,K.; Crane, B.

2005-01-01T23:59:59.000Z

13

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

Williams) Transition~Metal Carbides Heterogeneous CatalysisActivity of Transition-Metal Carbides Wendell S. Williamsand testing of transition-metal carbide electrodes for

Authors, Various

2011-01-01T23:59:59.000Z

14

EMSL - In situ catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

situ-catalysis en Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR http:www.emsl.pnl.govemslweb...

15

Fundamental Catalysis Research in Japan  

Science Journals Connector (OSTI)

Fundamental Catalysis Research in Japan ... Japan is one of the foremost nations in catalysis research. ... Dr. Horiuti responded with information on what he and other Japanese research workers were doing, and subsequently I decided to visit Japan to study catalysis during my sabbatical leave from New York University last spring. ...

JOHN HAPPEL

1966-05-30T23:59:59.000Z

16

Energy Programs | Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Catalysis Driving Toward Alternative Fuels Page 1 of 2 About 85 percent of the nation's energy needs are met by the combustion of fossil fuels such as oil, natural gas, and coal - finite resources that make the United States dependent upon other countries while polluting the environment through carbon emissions. In order to achieve energy security in an environmentally friendly manner, the nation's energy strategy must include alternative technologies based on renewable sources such as biofuels, solar, wind, and nuclear power. A central challenge, however, is the development of new processes and materials capable of tapping these sources and feeding the country's vast energy needs. A key part of the solution involves catalysis, the process of speeding up and

17

Fuel Cell Technologies Office: Catalysis Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Catalysis Working Group to someone by E-mail Share Fuel Cell Technologies Office: Catalysis Working Group on Facebook Tweet about Fuel Cell Technologies Office: Catalysis Working Group on Twitter Bookmark Fuel Cell Technologies Office: Catalysis Working Group on Google Bookmark Fuel Cell Technologies Office: Catalysis Working Group on Delicious Rank Fuel Cell Technologies Office: Catalysis Working Group on Digg Find More places to share Fuel Cell Technologies Office: Catalysis Working Group on AddThis.com... Key Activities Plans, Implementation, & Results Accomplishments Organization Chart & Contacts Quick Links Hydrogen Production Hydrogen Delivery Hydrogen Storage Fuel Cells Technology Validation Manufacturing Codes & Standards Education Systems Analysis

18

DOE Catalysis Working Group Meeting  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

PEMFC Performance and Durability - Jim Waldecker (Ford) 9:45 - 10:00 Degradation of Nanoparticle Pt alloy and De-alloyed Pt Catalysts - Debbie Myers (ANL) Catalysis Working Group...

19

Molecular ingredients of heterogeneous catalysis  

SciTech Connect

The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described.

Somorjai, G.A.

1982-06-01T23:59:59.000Z

20

Magnetic catalysis in flavored ABJM  

E-Print Network (OSTI)

We study the magnetic catalysis of chiral symmetry breaking in the ABJM Chern-Simons matter theory with unquenched flavors in the Veneziano limit. We consider a magnetized D6-brane probe in the background of a flavored black hole which includes the backreaction of massless smeared flavors in the ABJM geometry. We find a holographic realization for the running of the quark mass due to the dynamical flavors. We compute several thermodynamic quantities of the brane probe and analyze the effects of the dynamical quarks on the fundamental condensate and on the phase diagram of the model. The dynamical flavors have an interesting effect on the magnetic catalysis. At zero temperature and fixed magnetic field, the magnetic catalysis is suppressed for small bare quark masses whereas it is enhanced for large values of the mass. When the temperature is non-zero there is a critical magnetic field, above which the magnetic catalysis takes place. This critical magnetic field decreases with the number of flavors, which we interpret as an enhancement of the catalysis.

Niko Jokela; Alfonso V. Ramallo; Dimitrios Zoakos

2013-11-25T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Cobalt-ruthenium catalysts for Fischer-Tropsch synthesis  

SciTech Connect

A hydrocarbon synthesis process is described which comprises reacting hydrogen and carbon monoxide in the presence of a catalyst comprised of cobalt and ruthenium on titania, at reaction conditions suitable for the formation of higher hydrocarbons. The catalyst is prepared by impregnating titania with solutions of cobalt and ruthenium salts, drying the impregnated support, reducing the cobalt and ruthenium, treating the reduced metals with an oxygen containing stream at conditions sufficient to form oxides of cobalt and oxides of ruthenium and reducing the cobalt and ruthenium oxides.

Iglesia, E.; Soled, S.L.; Fiato, R.A.

1989-04-18T23:59:59.000Z

22

ALD and Pulsed CVD of Ruthenium and Ruthenium Dioxide Thin Films From an Amidinate Precursor  

E-Print Network (OSTI)

Narrow window of O2 exposure (e.g. 0.02~0.04 Torr·s @ 325ºC) to obtain high quality pure Ru filmALD and Pulsed CVD of Ruthenium and Ruthenium Dioxide Thin Films From an Amidinate Precursor Xinwei, China Introduction Experimental ALD with O2 Ru metal film Pulsed CVD with NH3+H2 Ru metal film Pulsed

23

One-Pot Formation of Functionalized Indole and Benzofuran Derivatives Using a Single Bifunctional Ruthenium Catalyst  

E-Print Network (OSTI)

Bifunctional Ruthenium Catalyst Reji N. Nair Paul J. Lee bifunctional ruthenium catalyst for cyclization of terminalof transi- tion metal based catalysts have been reported to

Nair, Reji N; Lee, Paul J; Grotjahn, Douglas B

2010-01-01T23:59:59.000Z

24

A method for activation analysis of ruthenium in sea water  

E-Print Network (OSTI)

of these isotopes in the marine environment, it is essential that a method for the analysis of trace amounts of stable ruthenium be developed, and applied to the study of the chemical and physical dis- tribution of ruthenium in sea water, marine biota... 100 27. 2 82 34. 8 100 30. 2 91 30. 6 92 26. 9 81 8 (Tracer Only) 34. 5 100 Standard 33. 3 Average Counting time ? Eorty minutes 103 Tracer ? Ru 93 Stable ruthenium added ? 0. Z6 ug 14 TABLE 4 Nuclear Data for Ruthenium Isotope Per Cent...

Dixon, Bryan William

2012-06-07T23:59:59.000Z

25

CO oxidation on ruthenium: The nature of the active catalytic...  

NLE Websites -- All DOE Office Websites (Extended Search)

ruthenium 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...

26

SOUTHWEST CATALYSIS SOCIETY 2008 SPRING SYMPOSIUM  

E-Print Network (OSTI)

Design: FCC Feed Hydrotreating Catalysis 11:35 AM Lunch Break/Poster Preview 1:00 PM Zachary T. Ball

Natelson, Douglas

27

Transmural Catalysis - High Efficiency Catalyst Systems for NOx...  

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

Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Presentation...

28

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

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

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

29

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

NLE Websites -- All DOE Office Websites (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...

30

BERKELEY CATALYSIS CENTER Monday October 13  

E-Print Network (OSTI)

of an industrial catalyst shaped by extrusion with alumina. The catalytic assessment took place with two reactionsBERKELEY CATALYSIS CENTER Seminar Monday October 13 The McCollum Room 775 Tan Hall 9:00 am Dr. Jean parrafinic feedstocks. It also illustrates the type of cooperation between industrial and academic catalysis

Iglesia, Enrique

31

The use of Tafel back extrapolation to clarify the influence of ruthenium and palladium alloying on the corrosion behaviour of titanium in concentrated hydrochloric acid  

Science Journals Connector (OSTI)

Tafel back extrapolation of the cathodic reaction was used to interpret polarization data obtained for titanium alloyed with small amounts of ruthenium and palladium in concentrated hydrochloric acid. It was found that the ruthenium and palladium stimulated the cathodic reaction, but that the anodic behaviour of the titanium was unchanged. The results indicate that the corrosion of the titanium is increased by the small amount of alloying as the catalysis of the hydrogen reduction reaction was not strong enough to cause passivity of the titanium under these conditions. This was even so at longer times of exposure when significant enrichment of the ruthenium and palladium occurred on the surface of the titanium. Thermodynamic data were used to give further perspective to the results. Although excellent Tafel behaviour was found for the cathodic reaction, the exchange current densities and Tafel slopes obtained, are specific to the prior exposure time and surface enrichment of the alloying elements, and should not be interpreted as steady state data.

R.F. Sandenbergh; E. Van der Lingen

2005-01-01T23:59:59.000Z

32

"Nanocrystal bilayer for tandem catalysis"  

SciTech Connect

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

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

33

Magnetic Catalysis vs Magnetic Inhibition  

E-Print Network (OSTI)

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.

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06T23:59:59.000Z

34

Phase-Transfer Catalysis: Industrial Perspective  

Science Journals Connector (OSTI)

In the early 1990s, it was estimated that approximately 500 commercial phase-transfer catalysis (PTC) processes were being performed using at least 25 million pounds per year of catalyst. It was also estimated...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

35

Basic Concepts in Phase-Transfer Catalysis  

Science Journals Connector (OSTI)

Phase-transfer catalysis (PTC) is a powerful tool in many areas of chemistry. It is a technique for conducting reactions between two or more reagents in two or more phases, when reaction is inhibited because t...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

36

Catalysis Working Group Meeting: June 2014  

Energy.gov (U.S. Department of Energy (DOE))

Agenda and presentations from the Catalysis Working Group held on June 16, 2014, in Washington, D.C., in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting.

37

Single-molecule kinetics of nanoparticle catalysis  

Science Journals Connector (OSTI)

Owing to their structural dispersion, the catalytic properties of nanoparticles are challenging to characterize in ensemble-averaged measurements. The single-molecule approach enables studying the catalysis of na...

Weilin Xu; Hao Shen; Guokun Liu; Peng Chen

2009-12-01T23:59:59.000Z

38

Synthesis of Biodiesel via Acid Catalysis  

Science Journals Connector (OSTI)

Synthesis of Biodiesel via Acid Catalysis ... Biodiesel is synthesized via the transesterification of lipid feedstocks with low molecular weight alcohols. ... Nonetheless, acid-catalyzed processes could produce biodiesel from low-cost feedstocks, lowering production costs. ...

Edgar Lotero; Yijun Liu; Dora E. Lopez; Kaewta Suwannakarn; David A. Bruce; James G. Goodwin, Jr.

2005-01-25T23:59:59.000Z

39

Fiber optic D dimer biosensor  

DOE Patents (OSTI)

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.

Glass, Robert S. (Livermore, CA); Grant, Sheila A. (Pleasanton, CA)

1999-01-01T23:59:59.000Z

40

Isolated Palladium Atoms Allow Highly-Selective Catalysis of...  

Office of Science (SC) Website

or alloys based on platinum, palladium (Pd), rhodium, andor ruthenium. To reduce the cost and potentially increase reactivity, BES-funded researchers at Tufts University coated...

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Advanced Resources for Catalysis Science; Recommendations for a National Catalysis Research Institute  

SciTech Connect

Catalysis is one of the most valuable contributors to our economy and historically an area where the United States has enjoyed, but is now losing, international leadership. While other countries are stepping up their work in this area, support for advanced catalysis research and development in the U.S. has diminished. Yet, more than ever, innovative and improved catalyst technologies are imperative for new energy production processes to ease our dependence on imported resources, for new energy-efficient and environmentally benign chemical production processes, and for new emission reduction technologies to minimize the environmental impact of an active and growing economy. Addressing growing concerns about the future direction of U.S. catalysis science, experts from the catalysis community met at a workshop to determine and recommend advanced resources needed to address the grand challenges for catalysis research and development. The workshop's primary conclusion: To recapture our position as the leader in catalysis innovation and practice, and promote crucial breakthroughs, the U.S. must establish one or more well-funded and well-equipped National Catalysis Research Institutes competitively selected, centered in the national laboratories and, by charter, networked to other national laboratories, universities, and industry. The Institute(s) will be the center of a national collaboratory that gives catalysis researchers access to the most advanced techniques available in the scientific enterprise. The importance of catalysis to our energy, economic, and environmental security cannot be overemphasized. Catalysis is a vital part of our core industrial infrastructure, as it is integral to chemical processing and petroleum refining, and is critical to proposed advances needed to secure a sustainable energy future. Advances in catalysis could reduce our need for foreign oil by making better use of domestic carbon resources, for example, allowing cost-effective and zero emission conversion of coal into transportation fuels. No matter what energy sources are being considered (oil, natural gas, coal, biomass, solar, or nuclear based), a clean, sustainable energy future will involve catalysis to improve energy efficiency and storage and use options, and to mitigate environmental impacts. Recent revolutionary advances in nanotechnology and high-performance computing are enabling the breakthroughs in catalysis science and technology essential for a secure energy future. Thus, the time is right for substantially increased investments in catalysis science and technology.

Peden, Charles HF.; Ray, Douglas

2005-10-05T23:59:59.000Z

42

Ultrafast Electron Transfer Dynamics in Ruthenium Polypyridyl Complexes with a -Conjugated Ligand  

E-Print Network (OSTI)

to the solvent and orders of magnitude more rapidly than in previously studied ruthenium-diquat or ruthenium [(bpy)2RuLDQ]4+ (Chart 1) by broadband femtosecond transient absorption spectroscopy in acetonitrile

Dutta, Prabir K.

43

Catalysis Working Group Kick-Off Meeting Agenda  

Office of Environmental Management (EM)

1 Catalysis Working Group 2012 Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting Arlington, VA - May 14, 2012 Catalysis Working Group Kick-off Meeting...

44

Fuel Cell Technologies Office: Catalysis Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Group Catalysis Working Group The Catalysis Working Group (CWG) meets twice per year to exchange information, create synergies, and collaboratively develop both an understanding of and tools for studying electrocatalysis for polymer electrolyte fuel cells (PEFCs) and other low- and intermediate-temperature fuel cell systems, including direct methanol fuel cells (DMFCs), alkaline fuel cells (AFCs), alkaline membrane fuel cells (AMFCs), and phosphoric acid fuel cells (PAFCs). The CWG members include principal and co-principal investigators in electrocatalysis projects funded by the U.S. Department of Energy (DOE), as well as supporting DOE personnel. More information on DOE electrocatalysis activities can be found in the Multi-Year Research, Development, and Demonstration Plan.

45

Opportunities in Catalysis Research Using Synchrotron Radiation  

NLE Websites -- All DOE Office Websites (Extended Search)

in Catalysis Research Using Synchrotron Radiation in Catalysis Research Using Synchrotron Radiation Tuesday 10/8/02 Chair: Lars Pettersson 1:30-1:40 Anders Nilsson Welcome 1:40-2:30 Gabor Somorjai University of California, Berkeley and LBLN Need for New Directions of Research at the Frontiers of Catalysis Science 2:30-3:00 Geoff Thornton University of Manchester Influence of defects on the reactivity of ZnO 3:00-3:30 Anders Nilsson Stanford Synchrotron Radiation Laboratory Soft X-ray Spectroscopy of Surfaces and Reactions 3:30-3:45 Break Chair: Anders Nilsson 3:45-4:15 Lars Pettersson Stockholm University Adsorbate-Substrate Bonding: An Experimental and Theoretical MO Picture 4:15-4:45 Miquel Salmeron Lawrence Berkeley National Laboratory Photoelectron Spectroscopy studies of surfaces in high pressure gas

46

Catalysis: Reactivity and Structure Group | Chemistry Department |  

NLE Websites -- All DOE Office Websites (Extended Search)

Group Members Group Members Principal Investigators Jose Rodriguez Catalysis and surface science. Interaction and reaction of molecules with surfaces of metals, oxides, sulfides and carbides. Use of synchrotron-based techniques in surface and materials characterization (core and valence photoemission, x-ray absorption spectroscopy, x-ray diffraction). Modeling of surface reactions. Ping Liu Theoretical description of nanostructures, supported nanostructures, surfaces and their catalytic applications in heterogeneous catalysis and electrocatalysis. Density functional calculations, kinetic modeling and sensitivity analysis are employed to obtain a fundamental understanding of catalytic processes Dario Stacchiola Nano-Catalysis, Model mixed metal oxides, In-situ catalytic reactions at ambient pressures (AP). (Synchrotron PES, AP-XPS, AP-STM, AP-IRRAS, Inverse Catalyst, Nanoparticles, Graphene)

47

A Very Short Ruthenium(II) - Nitrogen Heterocycle Bond  

NLE Websites -- All DOE Office Websites (Extended Search)

Very Short Ruthenium(II) - Nitrogen Heterocycle Bond: The Crystal Very Short Ruthenium(II) - Nitrogen Heterocycle Bond: The Crystal Structures of Pentaammine(N-methylpyrazinium)ruthenium(II) Iodide and Pentaammine(N-methylpyrazinium)ruthenium(III) p-Toluenesulfonate Pentahydrate James F. Wishart, Avi Bino and Henry Taube Inorg. Chem. 25, 3318-3321 (1986) Abstract: The crystal structures of [(NH3)5Ru(NC4H4NCH3)] I3 and [(NH3)5Ru(NC4H4NCH3)] (CH3C6H4SO3)4°5H2O have been solved to weighted R factors of 0.053 and 0.083, respectively. For the former structure, the space group is Pmma with a = 10.655(2)Å, b = 7.704(1)Å, c = 21.488(3)Å, and Z = 4. The Ru(II)-N(Mepyz) distance of 1.95(1)Å in this complex is the shortest yet reported for a ruthenium(II) to heteroctclic nitrogen bond. A difference of 0.04(1)Å between the cis (2.122(7)Å and 2.136(8)Å) and

48

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

Office of Science (SC) Website

Catalysis Catalysis Basic Energy Sciences Advisory Committee (BESAC) BESAC Home Meetings Meeting Presentations History Logistics Members Charges/Reports Charter .pdf file (41KB) BES Committees of Visitors BES Home Meetings Catalysis Print Text Size: A A A RSS Feeds FeedbackShare Page Tuesday, May 14, 2002 - Opening Plenary Session Catalysis and Nanoscience Activities in BES - William Millman Energy Generation, Carbon Mgmt., and Methodology - John Frost Nanoscience and Catalysis - D. Wayne Goodman Wednesday, May 15, 2002 - 2nd Day Plenary Session Heterogeneous Catalysis - J. K. Norskov Homogeneous and Single-Site Heterogeneous Catalysis - Tobin Marks Thursday, May 16, 2002 - Breakout Summary Reports Catalysts Design Driven by Fundamental Research - Barteau Linking Basic Research to Applications - Bare Bell

49

Carbon dioxide adsorption and methanation on ruthenium  

SciTech Connect

The adsorption and methanation of carbon dioxide on a ruthenium-silica catalyst were studied using temperature-programmed desorption (TPD) and temperature-programmed reaction (TPR). Carbon dioxide adsorption was found to be activated; CO/sub 2/ adsorption increased significantly as the temperature increased from 298 to 435 K. During adsorption, some of the CO/sub 2/ dissociated to carbon monoxide and oxygen; upon hydrogen exposure at room temperature, the oxygen reacted to water. Methanation of adsorbed CO and of adsorbed CO/sub 2/, using TPR in flowing hydrogen, yielded a CH/sub 4/ peak with a peak temperature of 459 K for both adsorbates, indicating that both reactions follow the same mechanism after adsorption. This peak temperature did not change with initial surface coverage of CO, indicating that methanation is first order in CO coverage. The desorption and reaction spectra for Ru/SiO/sub 2/ were similar to those previously obtained for Ni/SiO/sub 2/, but both CO/sub 2/ formation and CH/sub 4/ formation proceeded faster on Ru. Also, the details of CO desorption and the changes in CO/sub 2/ and CO desorptions with initial coverage were different on the two metals. 5 figures, 3 tables.

Zagli, E.; Falconer, J.L.

1981-05-01T23:59:59.000Z

50

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

NLE Websites -- All DOE Office Websites (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...

51

Isotopic equilibration of carbon monoxide catalyzed by supported ruthenium  

SciTech Connect

Isotopic equilibration of carbon monoxide catalyzed by supported ruthenium was studied with oxygen-18 and carbon-13 labeled carbon monoxide in the presence and absence of hydrogen. The results showed that carbon monoxide was present on commercial alumina-supported ruthenium in a reactive undissociated form at 373/sup 0/K; that it adsorbed as a single carbonyl and in a geminal dicarbonyl form; and that hydrogen inhibited the exchange reaction by competitive adsorption and by stabilizing the carbonyl bond. The results elucidate the carbon monoxide methanation and Fischer-Tropsch reactions on this catalyst.

Bossi, A. (Cent. Ric. Novara); Zanderighi, L.; Carnisio, G.; Garbassi, F.; Giunchi, G.; Petrini, G.

1980-09-01T23:59:59.000Z

52

Cleavage of the Carbon-Sulfur Bonds in Thiophenes by a Binuclear Ruthenium Complex  

E-Print Network (OSTI)

.; Massoth, F. E. Hydrotreating Catalysis; Springer-Verlag: Berlin, 1996. (2) Bianchini, C.; Masi, D.; Meli

Jones, William D.

53

Nanoscale Advances in Catalysis and Energy Applications  

SciTech Connect

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.

Li, Yimin; Somorjai, Gabor A.

2010-05-12T23:59:59.000Z

54

Theoretical/Computational Tools for Energy-Relevant Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

Tools for Energy-Relevant Catalysis FWPProject Description: Project Leader(s): James Evans, Mark Gordon Principal Investigators: James Evans, Mark Gordon This project...

55

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

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

Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx Treatment Catalysis by Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx...

56

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...

57

Center for Biological Electron Transfer and Catalysis (BETCy...  

Office of Science (SC) Website

Center for Biological Electron Transfer and Catalysis (BETCy) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News &...

58

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

NLE Websites -- All DOE Office Websites (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...

59

Homogeneous and Interfacial Catalysis in 3D Controlled Environment...  

NLE Websites -- All DOE Office Websites (Extended Search)

Homogeneous and Interfacial Catalysis in 3D Controlled Environment FWPProject Description: Project Leader(s): Marek Pruski Principal Investigators: Andreja Bakac, Marek Pruski,...

60

University of Delaware | Catalysis Center for Energy Innovation...  

NLE Websites -- All DOE Office Websites (Extended Search)

Modeling Activity map produced from the new high-throughput computational engine. Example for ethylene glycol catalysis. Reforming, hydrodeoxygenation, dehydrogenation, and...

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Single Bifunctional Ruthenium Catalyst for One-Pot Cyclization and Hydration giving Functionalized Indoles and Benzofurans  

E-Print Network (OSTI)

Soc. 2004, 126, 12232. Catalyst 1 is now available from7992 7995 Bifunctional Ruthenium Catalyst COMMUNICATIONuse of bifunctional catalyst 1 for hydration and cycliza-

Nair, Reji??N.; Lee, Paul??J.; Rheingold, Arnold??L.; Grotjahn, Douglas??B.

2010-01-01T23:59:59.000Z

62

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

E-Print Network (OSTI)

-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

Pennycook, Steve

63

Ruthenium Bisbipyridine Complexes of Horse Heart Cytochrome c  

NLE Websites -- All DOE Office Websites (Extended Search)

Ruthenium Bisbipyridine Complexes of Horse Heart Cytochrome c: Ruthenium Bisbipyridine Complexes of Horse Heart Cytochrome c: Characterization and Comparative Intramolecular Electron Transfer Rates Determined by Pulse Radiolysis and Flash Photolysis J. Luo, K. B. Reddy, A. S. Salameh, J. F. Wishart and S. S. Isied Inorg. Chem. 39, 2321-2329 (2000) [Find paper at ACS Publications] Abstract: The reaction of [Ru(bpy)2L(H2O)]2+ (bpy = 2,2'-bipyridine, L = imidazole, water) with reduced horse heart cytochrome c results in coordination of [RuII(bpy)2L] at the His 33 and His 26 sites. Coordination at the His 33 site gave a diastereomeric [RuII(bpy)2L]-His-cyt c (II) mixture favoring the L-Ru form regardless of the substituent on the bipyridine ligands, while substitution at the more buried His 26 site gave isomeric distribution that varies according to the substituent on the bipyridine

64

Hydrogen and oxygen adsorption stoichiometries on silica supported ruthenium nanoparticles  

SciTech Connect

Treatment under H{sub 2} at 300 C of Ru(COD)(COT) dispersed on silica yields 2 nm ruthenium nanoparticles, [Ru{sub p}/SiO{sub 2}], according to EXAFS, HRTEM and XPS. H{sub 2} adsorption measurements on [Ru{sub p}/SiO{sub 2}] in the absence of O{sub 2} show that Ru particles adsorb up to ca. 2 H per surface ruthenium atoms (2H/Ru{sub s}) on various samples; this technique can therefore be used to measure the dispersion of Ru particles. In contrast, O{sub 2} adsorption on [Ru{sub p}/SiO{sub 2}] leads to a partial oxidation of the bulk at 25 C, to RuO{sub 2} at 200 C and to sintering upon further reduction under H{sub 2}, showing that O{sub 2} adsorption cannot be used to measure the dispersion of Ru particles.

Berthoud, Romain; Delichere, Pierre; Gajan, David; Lukens, Wayne; Pelzer, Katrin; Basset, Jean-Marie; Candy, Jean-Pierre; Coperet, Christophe

2008-12-01T23:59:59.000Z

65

Synthesis of Ruthenium Carbonyl Complexes with Phosphine or Substituted Cp Ligands, and Their Activity in the Catalytic Deoxygenation of 1,2-Propanediol  

SciTech Connect

A ruthenium hydride with a bulky tetra-substituted Cp ligand, (Cp{sup iPr{sub 4}})Ru(CO){sub 2}H (Cp{sup iPr{sub 4}} = C{sub 5}(i-C{sub 3}H{sub 7}){sub 4}H) was prepared from the reaction of Ru{sub 3}(CO){sub 12} with 1,2,3,4-tetraisopropylcyclopentadiene. The molecular structure of (Cp{sup iPr{sub 4}})Ru(CO){sub 2}H was determined by X-ray crystallography. The ruthenium hydride complex (C{sub 5}Bz{sub 5})Ru(CO){sub 2}H (Bz = CH{sub 2}Ph) was similarly prepared. The Ru-Ru bonded dimer, [(1,2,3-trimethylindenyl)Ru(CO){sub 2}]{sub 2}, was produced from the reaction of 1,2,3-trimethylindene with Ru{sub 3}(CO){sub 12}, and protonation of this dimer with HOTf gives {l_brace}[(1,2,3-trimethylindenyl)Ru(CO){sub 2}]{sub 2}-({mu}-H){r_brace}{sup +}OTf{sup -}. A series of ruthenium hydride complexes CpRu(CO)(L)H [L = P(OPh){sub 3}, PCy{sub 3}, PMe{sub 3}, P(p-C{sub 6}H{sub 4}F){sub 3}] were prepared by reaction of Cp(CO){sub 2}RuH with added L. Protonation of (Cp{sup iPr{sub 4}})Ru(CO){sub 2}H, Cp*Ru(CO){sub 2}H, or CpRu(CO)[P-(OPh){sub 3}]H by HOTf at -80 C led to equilibria with the cationic dihydrogen complexes, but H{sub 2} was released at higher temperatures. Protonation of CpRu[P(OPh){sub 3}]{sub 2}H with HOTf gave an observable dihydrogen complex, {l_brace}CpRu[P-(OPh){sub 3}]{sub 2}({eta}{sup 2}-H{sub 2}){r_brace}+OTf{sup -} that was converted at -20 C to the dihydride complex {l_brace}CpRu[P(OPh){sub 3}]{sub 2}(H){sub 2}{r_brace}{sup +}OTf{sup -}. These Ru complexes serve as catalyst precursors for the catalytic deoxygenation of 1,2-propanediol to give n-propanol. The catalytic reactions were carried out in sulfolane solvent with added HOTf under H{sub 2} (750 psi) at 110 C.

Bullock, R.M.; Ghosh, P.; Fagan, P.J.; Marshall, W.J.; Hauptman, E.

2009-07-20T23:59:59.000Z

66

Stereoselective Binding of Ruthenium Complexes to Cytochrome c  

NLE Websites -- All DOE Office Websites (Extended Search)

Site-Dependent Stereoselective Binding of Ruthenium Aquobipyridine Site-Dependent Stereoselective Binding of Ruthenium Aquobipyridine Complexes to Histidine Side Chains in Horse Heart Cytochrome c Jian Luo, James F. Wishart, and Stephan S. Isied J. Am. Chem. Soc. 120, 12970-12971 (1998) [Find paper at ACS Publications] Abstract: Stereoselective covalent binding of the ruthenium complexes cis-[Ru(bpy)2(H2O)2]2+ (bpy = 2,2'-bipyridine) and cis-[Ru(dmbpy)2(H2O)2]2+ (dmbpy = 4,4'-dimethyl-2,2'-bipyridine) to the surface His 33 residue and the more buried His 26 residues of Horse heart cytochrome c (Hh cyt c) to form large enantiomeric excess of D-[Ru(dmbpy)2(H2O)]-His 26-cyt c (38%), but little or no excess of D-[Ru(bpy)2(H2O)]-His 26-cyt c (6%). At the surface exposed His 33 site, equal entiomeric excess of L-[Ru(dmbpy)2(H2O)]-His 33-cyt c and L-[Ru(bpy)2(H2O)]-His 33-cyt c (34%)

67

XPS Investigations of Ruthenium Deposited onto Representative Inner Surfaces of Nuclear Reactor Containment Buildings  

E-Print Network (OSTI)

XPS Investigations of Ruthenium Deposited onto Representative Inner Surfaces of Nuclear Reactor in a nuclear power plant, interactions of gaseous RuO4 with reactor containment building surfaces (stainless, during nuclear reactor operation, the fission-product ruthenium will accumulate in the fuel. The quantity

Paris-Sud XI, Université de

68

Vapor Deposition of Ruthenium from an Amidinate Precursor Huazhi Li,a  

E-Print Network (OSTI)

Vapor Deposition of Ruthenium from an Amidinate Precursor Huazhi Li,a Damon B. Farmer,b Roy G School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA October 11, 2007. Thin films of ruthenium have many current and potential appli- cations. They can be used

69

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

Office of Science (SC) Website

Catalysis Science Catalysis Science Chemical Sciences, Geosciences, & Biosciences (CSGB) Division CSGB Home About Research Areas Energy Frontier Research Centers (EFRCs) DOE Energy Innovation Hubs Scientific Highlights Reports & Activities Principal Investigators' Meetings BES Home Research Areas Catalysis Science Print Text Size: A A A RSS Feeds FeedbackShare Page This research area develops the fundamental scientific principles enabling rational catalyst design and chemical transformation control. Research includes the identification of the elementary steps of catalytic reaction mechanisms and their kinetics; construction of catalytic sites at the atomic level; synthesis of ligands, metal clusters, and bio-inspired reaction centers designed to tune molecular-level catalytic activity and

70

Comparative study of dimer-vacancies and dimer-vacancy lines on Si(001) and Ge(001)  

E-Print Network (OSTI)

Comparative study of dimer-vacancies and dimer-vacancy lines on Si(001) and Ge(001) Cristian V that dimer- vacancy (DV) defects self-organize into vacancy lines (VLs) on Si(0 0 1), but not on Ge(0 0 1 the vacancies on Si(0 0 1) and Ge(0 0 1). We identify three energetic parameters which characterize the DVs

Ciobanu, Cristian

71

Instrumentation @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

Instrumentation Instrumentation The Catalysis Group at BNL is leading research initiatives into the development of new tools and techniques that focus on the characterization of heterogeneous catalytic reactions and catalysts using imaging, spectroscopy and scattering techniques and integrated combinations of them under reaction conditions to unravel the morphology, chemical and structural properties, of catalysts, respectively. These efforts revolve around the use of synchrotron radiation (NSLS), electrons (CFN) and quantum tunneling tools with particular thrusts into imaging, spectroscopy and scattering. Groups Instrumentation(BNL) Three UHV chambers with diverse instrumentation for surface characterization: LEED, UPS, XPS, AES, TPD, ISS, PM-AP-IRRAS, Reactivity Cell. All the systems include ancillary instrumentation such as sputtering guns and metal evaporators. The IRRAS system was retrofitted with an ambient pressure (AP) cell on top of the UHV system. The sample can be prepared and characterized in UHV and then transfer in vacuum to the AP cell.

72

Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsource  

NLE Websites -- All DOE Office Websites (Extended Search)

Shining Light on Catalysis 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 Bioengineering ETH Zurich Head of Laboratory for Catalysis and Sustainable Chemistry (LSK) Swiss Light Source Paul Scherrer Institute Understanding a functioning catalyst requires understanding at the atomic scales in a time-resolved manner. X-rays can be readily used to accomplish that task, because of the large penetration depth of hard X-rays, in situ or operando experiments are possible. In addition, complementary techniques, such as the vibrational spectroscopies can be simultaneously applied. Recent development in instrumentation to perform quick EXAFS and secondary emission spectroscopy has provided exciting new opportunities to

73

Catalysis Working Group Kick-Off Meeting: May 2012  

Energy.gov (U.S. Department of Energy (DOE))

Information from the Catalysis Working Group kick-off meeting held May 14, 2012, in Arlington, Virginia, in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting.

74

Theoretical investigation of solar energy conversion and water oxidation catalysis  

E-Print Network (OSTI)

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 ...

Wang, Lee-Ping

2011-01-01T23:59:59.000Z

75

Catalysis Working Group Kick-Off Meeting Agenda | Department...  

Energy Savers (EERE)

Kick-Off Meeting Agenda 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,...

76

Phase-Transfer Catalysis Reaction with Strong Bases  

Science Journals Connector (OSTI)

Among the vast scope of phase-transfer catalysis (PTC) applications, the largest sector involves the reaction of anions that are reacted and/or generated under PTC conditions with species containing electrophi...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

77

Phase-Transfer Catalysis Displacement Reactions with Simple Anions  

Science Journals Connector (OSTI)

Phase-transfer catalysis (PTC) is an excellent technique both in liquidliquid and liquidsolid (and sometimes in liquidvapor) modes for conducting displacement reactions with anions.

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

78

Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation  

SciTech Connect

The bridging ligand, 1,8-bis(2,2':6',2{double_prime}-terpyrid-4'-yl)anthracene (btpyan) was synthesized by the Miyaura-Suzuki cross coupling reaction of anthracenyl-1,8-diboronic acid and 4'-triflyl-2,2':6'-2{double_prime}-terpyridine in the presence of Pd(PPh{sub 3}){sub 4} (5 mol%) with 68% in yield. Three ruthenium-dioxolene dimers, [Ru{sub 2}(OH){sub 2}(dioxolene){sub 2}(btpyan)]{sup 0} (dioxolene = 3,6-di-tert-butyl-1,2-benzosemiquinone ([1]{sup 0}), 3,5-dichloro-1,2-benzosemiquinone ([2]{sup 0}) and 4-nitro-1,2-benzosemiquinone ([3]{sup 0})) were prepared by the reaction of [Ru{sub 2}Cl{sub 6}(btpyan)]{sup 0} with the corresponding catechol. The electronic structure of [1]{sup 0} is approximated by [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} (sq = semiquinonato). On the other hand, the electronic states of [2]{sup 0} and [3]{sup 0} are close to [Ru{sub 2}{sup III}(OH){sub 2} (cat){sub 2}(btpyan)]{sup 0} (cat = catecholato), indicating that a dioxolene having electron-withdrawing groups stabilizes [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0} rather than [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} as resonance isomers. No sign was found of deprotonation of the hydroxo groups of [1]{sup 0}, whereas [2]{sup 0} and [3]{sup 0} showed an acid-base equilibrium in treatments with t-BuOLi followed by HClO{sub 4}. Furthermore, controlled potential electrolysis of [1]{sup 0} deposited on an ITO (indium-tin oxide) electrode catalyzed the four-electron oxidation of H{sub 2}O to evolve O{sub 2} at potentials more positive than +1.6 V (vs. SCE) at pH 4.0. On the other hand, the electrolysis of [2]{sup 0} and [3]{sup 0} deposited on ITO electrodes did not show catalytic activity for water oxidation under similar conditions. Such a difference in the reactivity among [1]{sup 0}, [2]{sup 0} and [3]{sup 0} is ascribed to the shift of the resonance equilibrium between [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} and [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0}.

Wada, T.; Muckerman, J.; Fujita, E.; Tanaka, K.

2010-12-23T23:59:59.000Z

79

On the Acid-Base Mechanism for Ruthenium Water Oxidation Catalysts  

E-Print Network (OSTI)

We present a detailed theoretical study of the pathway for water oxidation in synthetic ruthenium-based catalysts. As a first step, we consider a recently discovered single center catalyst, where experimental observations ...

Wang, Lee-Ping

80

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

DOE Patents (OSTI)

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.

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

2014-10-28T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Novel Hydride Transfer Catalysis for Carbohydrate Conversions  

SciTech Connect

5-Hydroxymethylfurfural (HMF), an important versatile sugar derivative has been synthesized from glucose using catalytic amounts of CrCl2 in 1-ethyl-3-methylimidizolium chloride. Glycerol and glyceraldehyde were tested as sugar model compounds. Glycerol is unreactive and does not interfere with glucose conversion. Glyceraldehyde is reactive and does interfere with glucose conversion in competitive experiments. MnCl2 or FeCl2 catalyze dehydration of glyceraldehyde dimer to form compound I, a cyclic hemiacetal with an exocyclic double bond. Upon aqueous work-up I forms pyruvaldehyde. CrCl2 or VCl3 further catalyze a hydride transfer of I to form lactide. Upon aqueous work-up lactide is converted to lactic acid.

Holladay, John E.; Brown, Heather M.; Appel, Aaron M.; Zhang, Z. Conrad

2008-04-03T23:59:59.000Z

82

Publications @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

List of Publications since 2010 List of Publications since 2010 2013 "Unique properties of ceria nanoparticles supported on metals: Novel inverse ceria/copper catalysts for CO oxidation and the water-gas shift reaction" Senanayake, S.D., Stacchiola, D., and Rodriguez, J.A. Accounts of Chemical Research, 2013. 46(8): p. 1702-1711. "Characterization of metal-oxide catalysts in operando conditions by combining x-ray absorption and raman spectroscopies in the same experiment" Patlolla, A., Baumann, P., Xu, W., Senanayake, S.D., Rodriguez, J.A., and Frenkel, A.I. Topics in Catalysis, 2013. 56(11): p. 896-904. "In situ time-resolved x-ray diffraction study of the synthesis of Mo2C with different carburization agents" Guzman, H.J., Xu, W.Q., Stacchiola, D., Vitale, G., Scott, C.E., Rodriguez, J.A., and Pereira-Almao, P. Canadian Journal of Chemistry-Revue Canadienne De Chimie, 2013. 91(7): p. 573-582.

83

Some General Themes in Catalysis at LANL  

SciTech Connect

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.

Gordon, John C. [Los Alamos National Laboratory

2012-07-19T23:59:59.000Z

84

Helium 4 Dimer in Two Coaxial Adjacent Nanotubes  

Science Journals Connector (OSTI)

The ground state properties of the helium 4 dimer, within the geometry defined by two adjacent nanotubes with different radii and hard core walls,...

J. Brana; S. Kili?; L. Vranje

2002-01-01T23:59:59.000Z

85

Selective Aerobic Oxidation of 5-Hydroxymethylfurfural in Water Over Solid Ruthenium Hydroxide Catalysts with Magnesium-Based Supports  

Science Journals Connector (OSTI)

Solid catalyst systems comprised of ruthenium hydroxide supported on magnesium-based carrier materials (spinel, magnesium oxide and hydrotalcite) were investigated for the selective, aqueous aerobic oxidation of ...

Yury Y. Gorbanev; Sren Kegns; Anders Riisager

2011-12-01T23:59:59.000Z

86

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

SciTech Connect

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/

Metiu, Horia [University of California, Santa Barbara

2014-08-22T23:59:59.000Z

87

Single-Molecule Kinetics of Nanoparticle Catalysis , Hao Shen, Guokun Liu, and Peng Chen  

E-Print Network (OSTI)

#12;Single-Molecule Kinetics of Nanoparticle Catalysis Weilin Xu , Hao Shen, Guokun Liu, and Peng to characterize in ensemble-averaged measurements. The single-molecule approach enables studying the catalysis single-molecule Áuorescence studies of single Au-nanoparticle catalysis, focusing on the theoretical

Chen, Peng

88

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

SciTech Connect

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)

Not Available

1990-03-01T23:59:59.000Z

89

Evidence from bond lengths and bond angles for enneacovalence of cobalt, rhodium, iridium, iron, ruthenium, and osmium in compounds with elements of medium electronegativity  

Science Journals Connector (OSTI)

...enneacovalence of cobalt, rhodium, iridium, iron, ruthenium, and osmium in compounds...enneacovalence of cobalt, rhodium, iridium, iron, ruthenium, and osmium in compounds...CO)10(diop)] 274.4 45 acac, acetylacetonate; diop, di-o-phthalate. Chemistry...

Linus Pauling

1984-01-01T23:59:59.000Z

90

PNNL: Institute for Integrated Catalysis (IIC) at Pacific Northwest  

NLE Websites -- All DOE Office Websites (Extended Search)

Institute for Integrated Catalysis Institute for Integrated Catalysis The Institute for Integrated Catalysis at Pacific Northwest National Laboratory facilitates collaborative research and development in catalysts for a secure energy future. Latest Announcements When Less Is More: Fewer Proton Relays Improve Catalytic Rates First direct comparison of three nickel-based complexes shows complexes with 2 proton relays outperform those with 4 (January 2014) Wind and other renewable energy sources are limited because the power must be used when it's generated, as it currently cannot be stored. Scientists want to store the energy in compact, easy-to-release chemical bonds. A major challenge is designing an affordable, efficient, and fast catalyst to make the chemical bonds. At the Center for Molecular Electrocatalysis,

91

Tandem Catalysis in Nanocrystal Interfaces | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Tandem Catalysis in Nanocrystal Interfaces Tandem Catalysis in Nanocrystal Interfaces Tandem Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View(active tab) Edit Workflow Addthis A unique new bilayer nanocatalyst system. | Image courtesy of Yang group A unique new bilayer nanocatalyst system. | Image courtesy of Yang group What does this mean for me? A prime example of these applications is artificial photosynthesis -- the effort to capture energy from the sun and transform it into electricity or chemical fuels. Catalysts (substances that speed up the rates of chemical reactions without themselves being chemically changed) are used to initiate virtually every industrial manufacturing process that involves chemistry. With the advent of nano-sized catalysts, metal and metal oxide catalysts have surged in

92

Jeffrey T. Miller Wins Award for Excellence in Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

van Veenendaal of X-ray Science Division wins 2009 NIU Presidential van Veenendaal of X-ray Science Division wins 2009 NIU Presidential Research Professorship 2009 APSUO Compton Award to Grübel, Mochrie, and Sutton New Era of Research Begins as World's First Hard X-ray Laser Achieves "First Light" Unique Uranium Source in Naturally Bioreduced Sediment Jonathan Lang Named 2008 PSC Supervisor of the Year APS News Archives: 2012 | 2011 | 2010 | 2009 2008 | 2007 | 2006 | 2005 2004 | 2003 | 2002 | 2001 2000 Subscribe to APS News rss feed Jeffrey T. Miller Wins Award for Excellence in Catalysis JUNE 15, 2009 Bookmark and Share Jeffrey T. Miller Jeffrey T. Miller, leader of the Heterogeneous Catalysis Group in the Argonne National Laboratory Chemical Sciences and Engineering Division (CSE), has been presented with the 2009 Award for Excellence in Catalysis

93

Theoretical Study on Catalysis by Protein Enzymes and Ribozyme  

NLE Websites -- All DOE Office Websites (Extended Search)

Theoretical Study on Theoretical Study on Catalysis by Protein Enzymes and Ribozyme Theoretical Study on Catalysis by Protein Enzymes and Ribozyme 2000 NERSC Annual Report 17shkarplus.jpg The energetics were determined for three mechanisms proposed for TIM catalyzed reactions. Results from reaction path calculations suggest that the two mechanisms that involve an enediol intermediate are likely to occur, while the direct intra-substrate proton transfer mechanism (in green) is energetically unfavorable due to the presence of His95 in the active site. Principal Investigator: Martin Karplus, Harvard University Research Objectives The goal of this project is to develop a greater understanding of the mechanisms involved in enzyme catalysis and related protein functions. We are studying two types of enzymes: proteins and a nucleic acid (hammerhead

94

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

SciTech Connect

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.

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

1995-02-01T23:59:59.000Z

95

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

E-Print Network (OSTI)

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

Heflin, Randy

96

Origins of catalysis by computationally designed retroaldolase enzymes  

E-Print Network (OSTI)

Origins of catalysis by computationally designed retroaldolase enzymes Jonathan K. Lassilaa , David enzymes with the goal of understanding the extent and the origins of their catalytic power. Direct comparison of the designed enzymes to primary amine catalysts in solution revealed a rate acceleration of 105

Herschlag, Dan

97

Solar Energy without Neutrinos: Fusion Catalysis by Quarks  

Science Journals Connector (OSTI)

... some features of fusion catalysis by quarks and the consequences relating to release of stellar energy. In particular, the recent non-observation8 of ... . In particular, the recent non-observation8 of solar neutrinos which rules out9-12 the carbon cycle as the main mechanism for ...

L. MARSHALL LIBBY; F. J. THOMAS

1969-06-28T23:59:59.000Z

98

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network (OSTI)

THE CATALYTIC UPGRADE OF PYROLYSIS OIL IN VAPOR AND LIQUID PHASES Presented by... Daniel E. Resasco ·Douglas Engineering ·University of Oklahoma Abstract An effective approach to stabilize pyrolysis oil is conducting for Interfacial Reaction Engineering (CIRE) http://www.ou.edu/catalysis/ Center for Biomass Befining (CBR) http

99

The Catalysis of the Carbon Monoxide-Steam Reaction  

Science Journals Connector (OSTI)

...The Catalysis of the Carbon Monoxide-Steam Reaction F. J. Long K. W. Sykes The kinetics of the carbon monoxide-steam reaction occurring heterogeneously at...nearly unity, while that with respect to steam is correspondingly lowered; a slight...

1952-01-01T23:59:59.000Z

100

Catalysis in the preparation of fragrances and flavours  

Science Journals Connector (OSTI)

This review, with more than 250 references in the field of fragrance and flavour chemistry, summarises recent progress in industrial catalysis. Applications in classical reactions, such as hydrogenations, isomerisations, hydride reductions, oxidations, hydroformylations, metathesis, aldol and FriedelCrafts condensations in achiral, racemic and asymmetric fashion are discussed.

Christian Chapuis; Denis Jacoby

2001-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

A Single-Molecule Study of RNA Catalysis and Folding  

E-Print Network (OSTI)

A Single-Molecule Study of RNA Catalysis and Folding Xiaowei Zhuang,1 * Laura E. Bartley,2 * Hazen and undocks from the ribozyme core was observed directly in single-molecule time trajectories, allowing. These results establish single-molecule fluorescence as a pow- erful tool for examining RNA folding. Virtually

Herschlag, Dan

102

Overview of surface science and catalysis by Qifei Wu  

E-Print Network (OSTI)

surfaces: single crystal transition metals, metal nanoparticles (Au), metal oxides, sulfides, carbides: · Metcars are the better catalysts for HDS than the other metal carbide materials. · Metcars have better: Sulfides (RuS2), carbides (MoC, TiC) #12;Density Functional Theory in Catalysis Employ DFT to understand

103

Transport of Molecular Motor Dimers in Burnt-Bridge Models  

E-Print Network (OSTI)

Dynamics of molecular motor dimers, consisting of rigidly bound particles that move along two parallel lattices and interact with underlying molecular tracks, is investigated theoretically by analyzing discrete-state stochastic continuous-time burnt-bridge models. In these models the motion of molecular motors is viewed as a random walk along the lattices with periodically distributed weak links (bridges). When the particle crosses the weak link it can be destroyed with a probability $p$, driving the molecular motor motion in one direction. Dynamic properties and effective generated forces of dimer molecular motors are calculated exactly as a function of a concentration of bridges $c$ and burning probability $p$ and compared with properties of the monomer motors. It is found that the ratio of the velocities of the dimer and the monomer can never exceed 2, while the dispersions of the dimer and the monomer are not very different. The relative effective generated force of the dimer (as compared to the monomer) also cannot be larger than 2 for most sets of parameters. However, a very large force can be produced by the dimer in the special case of $c=1/2$ for non-zero shift between the lattices. Our calculations do not show the significant increase in the force generated by collagenase motor proteins in real biological systems as predicted by previous computational studies. The observed behavior of dimer molecular motors is discussed by considering in detail the particle dynamics near burnt bridges.

Alexander Yu. Morozov; Anatoly B. Kolomeisky

2007-09-21T23:59:59.000Z

104

Adsorption of silver dimer on graphene - A DFT study  

SciTech Connect

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.

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

105

Isomerization of methyl linoleate on ruthenium(III) alkoxide complex; Mathematical modeling  

SciTech Connect

The isomerization of methyl linoleate using ruthenium alkoxide complexes is described. With alcohols, such as isopropyl alcohol (IPA), 1-butanol, 1-hexanol, and 1-octanol, isomerization of double bonds to produce a conjugated system is the main reaction, with hydrogenation being the side reaction. The latter is formed via the conjugated product. Based on kinetic and infrared spectroscopic data, it is concluded that the active catalytic species is a ruthenium hydride complex formed by the decomposition of the unstable alkoxide. The reaction is mathematically modeled, and the rate parameters are obtained by fitting the simulation to experimental data. These values are compared with data obtained from reactions carried out with supported ruthenium-nickel heterogeneous catalyst.

Mukesh, D.; Narasimhan, C.S.; Ramnarayan, K.; Deshpande, V.M

1989-08-01T23:59:59.000Z

106

Zeeman Effects in the Arc Spectrum of Ruthenium  

Science Journals Connector (OSTI)

Measurements on resolved Zeeman patterns of 450 lines of normal ruthenium are reported. Five exposures to each polarized component of the light from a 4-ampere arc, operated in magnetic fields of intensity between 71,000 and 92,200 gauss, resulted in 85 plates which were measured on an automatic comparator. J and g values have been determined from the various patterns. When data from the various lines arising from a given term are averaged, g values for 140 terms are obtained which appear to be correct to within 0.003 unit. The results obtained have been used to further the classification of Ru I, and to aid in the assignment of L and S values to highly perturbed terms. Though g values frequently depart strongly from values calculated for LS coupling, it is usually possible to assign meaningful L and S designations. Asymmetrical patterns in lines arising from the terms y5D30 and y5D40 are discussed.

George R. Harrison and J. Rand McNally; Jr.

1940-10-15T23:59:59.000Z

107

Selective oxidative synthesis of meso-beta fused porphyrin dimers  

NLE Websites -- All DOE Office Websites (Extended Search)

Selective oxidative synthesis of meso-beta fused porphyrin dimers Authors: Brennan, B.J., Arero, J., Liddell, P.A., Moore, T.A., Moore, A.L., and Gust, D. Title: Selective...

108

Argonne Chemical Sciences & Engineering - People - Catalysis and Energy  

NLE Websites -- All DOE Office Websites (Extended Search)

Management and Support Management and Support Heterogeneous Catalysis Homogeneous Catalysis Fuel Cell Engineering Hydrogen and Fuel Cell Materials Ceramic Electrochemistry Electrochemical Projects Support Management and Support Theodore R. Krause, Chemical Engineer and Department Manager phone: 630/252-4356, fax: 630/972-4463, e-mail: krauset@anl.gov PhD, Chemical Engineering, University of Delaware Catalyst formulations and characterization Reaction kinetics Catalyst fundamentals Hydrogen production technologies Laurie A. Carbaugh, Administrative Secretary phone: 630/252-7556, fax: 630/252-9917, e-mail: laurie.carbaugh@anl.gov Romesh Kumar, Senior Chemical Engineer phone: 630/252-4342, fax: 630/252-4176, e-mail: kumar@anl.gov PhD, Chemical Engineering, University of California, Berkeley

109

Pacific Northwest National Laboratory Catalysis Highlights for FY2007  

SciTech Connect

To reduce the nations dependence on imported oil, the U.S. Department of Energy (DOE) and other federal and private agencies are investing in understanding catalysis. This report focuses on catalysis research conducted by Pacific Northwest National Laboratory (PNNL) and its collaborators. Using sophisticated instruments in DOEs Environmental Molecular Sciences Laboratory, a national scientific user facility, research was conducted to answer key questions related to the nations use of automotive fuels. Research teams investigated how hydrogen can be safely stored and efficiently released, critical questions to use this alternative fuel. Further, they are answering key questions to design molecular catalysts to control the transfer of hydrogen atoms, hydrides, and protons important to hydrogen production. In dealing with todays fuels, researchers examined adsorption of noxious nitrous oxides in automotive exhaust. Beyond automotive fuel, researchers worked on catalysts to harness solar power. These catalysts include the rutile and anatase forms of titanium dioxide. Basic research was conducted on designing catalysts for these and other applications. Our scientists examined how to build catalysts with the desired properties atom by atom and molecule by molecule. In addition, this report contains brief descriptions of the outstanding accomplishments of catalysis experts at PNNL.

Garrett, Bruce C.

2007-11-15T23:59:59.000Z

110

{sup 106}Ruthenium Plaque Therapy (RPT) for Retinoblastoma  

SciTech Connect

Purpose: To evaluate the effectiveness of episcleral {sup 106}ruthenium plaque therapy (RPT) in the management of retinoblastoma. Methods and Materials: One hundred one RPTs were retrospectively analyzed that were performed in 90 eyes of 85 patients with retinoblastoma at National Cancer Center Hospital between 1998 and 2008. Each RPT had a corresponding tumor and 101 tumors were considered in the analysis of local control. Median follow-up length was 72.8 months. Median patient age at the RPT was 28 months. Median prescribed doses at reference depth and outer surface of the sclera were 47.4 Gy and 162.3 Gy, respectively. Results: Local control rate (LCR) and ocular retention rate (ORR) at 2 years were 33.7% and 58.7%, respectively. Unilateral disease, International Classification of Retinoblastoma group C or more advanced at the first presentation or at the time of RPT, vitreous and/or subretinal seeding, tumor size greater than 5 disc diameter (DD), reference depth greater than 5 mm, dose rate at reference depth lower than 0.7 Gy/hour, dose at the reference depth lower than 35 Gy, and (biologically effective dose with an {alpha}/{beta} ratio of 10 Gy) at the reference depth lower than 40 Gy{sub 10} were associated with unfavorable LCR. Two patients died of metastatic disease. Radiation complications included retinal detachment in 12 eyes (13.3%), proliferative retinopathy in 6 (6.7%), rubeosis iris in 2 (2.2%), and posterior subcapsular cataract in 23 (25.6%). Conclusion: RPT is an effective eye-preserving treatment for retinoblastoma.

Murakami, Naoya, E-mail: namuraka@ncc.go.jp [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan)] [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan); Suzuki, Shigenobu [Department of Ophthalmic Oncology, National Cancer Center Hospital, Tokyo (Japan)] [Department of Ophthalmic Oncology, National Cancer Center Hospital, Tokyo (Japan); Ito, Yoshinori [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan)] [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan); Yoshimura, Ryoichi [Department of Diagnostic Radiology and Oncology, Head and Neck Reconstruction Division, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan)] [Department of Diagnostic Radiology and Oncology, Head and Neck Reconstruction Division, Graduate School, Tokyo Medical and Dental University, Tokyo (Japan); Inaba, Koji; Kuroda, Yuki; Morota, Madoka; Mayahara, Hiroshi; Sakudo, Mototake; Wakita, Akihisa; Okamoto, Hiroyuki; Sumi, Minako; Kagami, Yoshikazu [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan)] [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan); Nakagawa, Keiichi; Ohtomo, Kuni [Department of Radiology, University of Tokyo Hospital, Tokyo (Japan)] [Department of Radiology, University of Tokyo Hospital, Tokyo (Japan); Itami, Jun [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan)] [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan)

2012-09-01T23:59:59.000Z

111

Catalysis Center for Energy Innovation (CCEI) | U.S. DOE Office...  

Office of Science (SC) Website

Catalysis Center for Energy Innovation (CCEI) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News & Events...

112

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

E-Print Network (OSTI)

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

Wan, Xin-hua

113

Vapor Deposition of Ruthenium from an Amidinate Precursor Huazhi Li,a  

E-Print Network (OSTI)

Vapor Deposition of Ruthenium from an Amidinate Precursor Huazhi Li,a Damon B. Farmer,b Roy G. Gordon* ,a Youbo Lin,b Joost Vlassakb a Department of Chemistry and Chemical Biology and b School and potential applications. They can be used as electrodes for capacitors, in which their high work function

114

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

SciTech Connect

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.

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

115

Highly stable tetrathiafulvalene radical dimers in [3]catenanes  

SciTech Connect

Two [3]catenane 'molecular flasks' have been designed to create stabilized, redox-controlled tetrathiafulvalene (TTF) dimers, enabling their spectrophotometric and structural properties to be probed in detail. The mechanically interlocked framework of the [3]catenanes creates the ideal arrangement and ultrahigh local concentration for the encircled TTF units to form stable dimers associated with their discrete oxidation states. These dimerization events represent an affinity umpolung, wherein the inversion in electronic affinity replaces the traditional TTF-bipyridinium interaction, which is over-ridden by stabilizing mixed-valence (TTF){sub 2}{sup {sm_bullet}+} and radical-cation (TTF{sup {sm_bullet}+}){sub 2} states inside the 'molecular flasks.' The experimental data, collected in the solid state as well as in solution under ambient conditions, together with supporting quantum mechanical calculations, are consistent with the formation of stabilized paramagnetic mixed-valence dimers, and then diamagnetic radical-cation dimers following subsequent one-electron oxidations of the [3]catenanes.

Spruell, Jason M.; Coskun, Ali; Friedman, Douglas C.; Forgan, Ross S.; Sarjeant, Amy A.; Trabolsi, Ali; Fahrenbach, Albert C.; Barin, Gokhan; Paxton, Walter F.; Dey, Sanjeev K.; Olson, Mark A.; Bentez, Diego; Tkatchouk, Ekaterina; Colvin, Michael T.; Carmielli, Raanan; Caldwell, Stuart T.; Rosair, Georgina M.; Hewage, Shanika Gunatilaka; Duclairoir, Florence; Seymour, Jennifer L.; Slawin, Alexandra M.Z.; Goddard, III, William A.; Wasielewski, Michael R.; Cooke, Graeme; Stoddart, J. Fraser (CNRS-UMR); (CIT); (NWU); (Glasgow); (Heriot-Watt); (St Andrews)

2010-12-03T23:59:59.000Z

116

TEMPERATURE-PROGRAMMED DESORPTION AND REACTION OF CO AND H2 ON ALUMINA-SUPPORTED RUTHENIUM CATALYST  

E-Print Network (OSTI)

over Group VIII Metal Catalysts" J.T. Kummer and P.H.and Fischer- Iron Catalyst", to be published. P.R. Wentrek,on Alumina-supported Ruthenium Catalyst" to be published. M.

Low, Gordon Gongngai

2011-01-01T23:59:59.000Z

117

Ruthenium(VI) catalyzed oxidation of sodium salts of lactic, tartaric and glycolic acid by alkaline hexacyanoferrate(III)  

Science Journals Connector (OSTI)

The kinetics of ruthenium(VI) catalyzed oxidation of sodium salts of lactic, tartaric and glycolic acid by hexacyanoferrate(III) in aqueous alkaline medium have been studied at constant ionic strength. The rea...

P. Kumar; K. C. Gupta; K. Vehari

1985-01-01T23:59:59.000Z

118

Application of Atmospheric Non Thermal Plasma-Catalysis Hybrid System for Air Pollution Control: Toluene removal.  

E-Print Network (OSTI)

1 Application of Atmospheric Non Thermal Plasma-Catalysis Hybrid System for Air Pollution Control for these technologies. As an alternative to conventional VOCs abatement techniques, atmospheric non-thermal plasma (NTP rue d'Issoudun, BP 6744, 45067 Orléans Cedex 02, France. Keywords: Non thermal Plasma, Catalysis

Paris-Sud XI, Université de

119

Magnetic-field induced absorption of zero-phonon lines in tris(bipyridine)ruthenium(2+) bis(hexafluorophosphate) and diperchlorate single crystals  

Science Journals Connector (OSTI)

Magnetic-field induced absorption of zero-phonon lines in tris(bipyridine)ruthenium(2+) bis(hexafluorophosphate) and diperchlorate single crystals ...

G. Hensler; E. Gallhuber; H. Yersin

1987-06-01T23:59:59.000Z

120

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Ceramic Electrochemistry Ceramic Electrochemistry * Members * Contact * Publications * Overview * Solid Oxide Fuel Cells * Steam Electrolysis Catalysis & Energy Conversion Home Ceramic Electrochemistry Dave Carter and solid oxide fuel cell Materials scientist John David Carter prepares a solid oxide electrochemical cell for high temperature testing. Research activities in the Ceramic Electrochemistry Group are focused on the development of ceramic-based electrochemical devices and components, such as Solid Oxide Fuel Cells (SOFC) and High Temperature Steam Electrolyzers (HTSE). This extends to materials synthesis, fabrication, and characterization. Solid Oxide Fuel Cell Research As part of the Solid State Energy Conversion Alliance (SECA) Core Technology Program, the goal of this research is the development of solid

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis  

SciTech Connect

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.

Thorn, David [Los Alamos National Laboratory

2012-06-13T23:59:59.000Z

122

Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles  

SciTech Connect

Prompted by the need for a self-supported, chemically stable, and functionally flexible catalytic nanoparticle system, we explore a system involving Pd clusters coated with a monolayer of polyhedral oligomeric silsesquioxane (POSS) cages. With an initial theoretical focus on hydrogen catalysis and sequestration in the Pd-POSS system, we report Density Functional Theory (DFT) results on POSS binding energies to the Pd(110) surface, hydrogen storing ability of POSS, and possible pathways of hydrogen radicals from the catalyst surface to unsaturated bonds away from the surface.

Maiti, A; Gee, R H; Maxwell, R; Saab, A

2007-02-01T23:59:59.000Z

123

Zn?Zn Porphyrin Dimer-Sensitized Solar Cells: Toward 3-D Light Harvesting  

Science Journals Connector (OSTI)

Zn?Zn porphyrin dimers have been incorporated into thin dye-sensitized solar cells (DSSCs) to boost their light harvesting efficiency. The photoexcited dimers show efficient and fast electron injection into TiO2 indicating that both photoexcited ...

Attila J. Mozer; Matthew J. Griffith; George Tsekouras; Pawel Wagner; Gordon G. Wallace; Shogo Mori; Kenji Sunahara; Masanori Miyashita; John C. Earles; Keith C. Gordon; Luchao Du; Ryuzi Katoh; Akihiro Furube; David L. Officer

2009-10-09T23:59:59.000Z

124

Mercury dimer spectroscopy and an Einstein-Podolsky-Rosen experiment  

E-Print Network (OSTI)

The dissociation of a 199Hg2 dimer prepares an entangled state of two spatially separated 199Hg atoms, each with nuclear spin 1/2, and with zero total electron and nuclear spin angular momenta. This is identical to the entangled state of the two...

Qu, Xinmei

2009-05-15T23:59:59.000Z

125

Click Dimers To Target HIV TAR RNA Conformation Sunil Kumar,  

E-Print Network (OSTI)

toward HIV TAR RNA, when compared to the fluorescent Tat peptide, and show increased selectivity over acid protein) and regulates the level of transcription of HIV.4,5 The cooperative interaction of TatClick Dimers To Target HIV TAR RNA Conformation Sunil Kumar, Patrick Kellish, W. Edward Robinson

Stuart, Steven J.

126

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

SciTech Connect

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.

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

2012-01-01T23:59:59.000Z

127

Materials Design and Discovery: Catalysis and Electrical Energy Storage  

NLE Websites -- All DOE Office Websites (Extended Search)

and Discovery: Catalysis and Discovery: Catalysis and Electrical Energy Storage Presenter: N ichols A . R omero, A LCF ESP p ost---doc: Anouar B enali, A LCF PI: L arry C urAss, A NL M SD a nd C NM Comments from a reviewer on "Material Design and Discovery" from a proposal § How c ould t his m achine w ith t hese p rograms b e u sed t o d esign a n ew s olar c ell? Or a n ew c ure f or A IDS? O r a n ew h igh---T s uperconductor? T his i s n ot i ntended a s a trivial q uesAon. T he p resent m ethod o f D ISCOVERY r elies o n t he t rained h uman mind ( insight) a nd e xperiment ( serendipity). C omputaAonal s cience s o f ar h as n ot delivered a ny n ew d iscoveries b ecause i t l acks t he p ossibility o f s erendipity. T he greatest s uccess o f c omputaAonal c hemistry h as b een i mproved i nsight i nto t he way m aterial b ehaves

128

Polyribosomes in Rat Tissues: IV. On the Abnormal Dimer Peak in Hepatomas  

Science Journals Connector (OSTI)

...previously (11) that the dimer peak which is present in both the...between the monomer and dimer peaks. Also only slight changes are...height of the monomer and dimer peaks when the Novikoff hepatoma was...in an equal volume of mineral oil 12 hr before removal of the...

Thomas E. Webb and Van R. Potter

1966-05-01T23:59:59.000Z

129

Precise ruthenium fission product isotopic analysis using dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)  

SciTech Connect

99Tc is a subsurface contaminant of interest at numerous federal, industrial, and international facilities. However, as a mono-isotopic fission product, 99Tc lacks the ability to be used as a signature to differentiate between the different waste disposal pathways that could have contributed to subsurface contamination at these facilities. Ruthenium fission-product isotopes are attractive analogues for the characterization of 99Tc sources because of their direct similarity to technetium with regard to subsurface mobility, and their large fission yields and low natural background concentrations. We developed an inductively coupled plasma mass spectrometry (ICP-MS) method capable of measuring ruthenium isotopes in groundwater samples and extracts of vadose zone sediments. Samples were analyzed directly on a Perkin Elmer ELAN DRC II ICP-MS after a single pass through a 1-ml bed volume of Dowex AG 50W-X8 100-200 mesh cation exchange resin. Precise ruthenium isotopic ratio measurements were achieved using a low-flow Meinhard-type nebulizer and long sample acquisition times (150,000 ms). Relative standard deviations of triplicate replicates were maintained at less than 0.5% when the total ruthenium solution concentration was 0.1 ng/ml or higher. Further work was performed to minimize the impact caused by mass interferences using the dynamic reaction cell (DRC) with O2 as the reaction gas. The aqueous concentrations of 96Mo and 96Zr were reduced by more than 99.7% in the reaction cell prior to injection of the sample into the mass analyzer quadrupole. The DRC was used in combination with stable-mass correction to quantitatively analyze samples containing up to 2-orders of magnitude more zirconium and molybdenum than ruthenium. The analytical approach documented herein provides an efficient and cost-effective way to precisely measure ruthenium isotopes and quantitate total ruthenium (natural vs. fission-product) in aqueous matrixes.

Brown, Christopher F.; Dresel, P. Evan; Geiszler, Keith N.; Farmer, Orville T.

2006-05-09T23:59:59.000Z

130

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen and Fuel Cell Materials Hydrogen and Fuel Cell Materials * Members * Contact * Publications * Overview * Alternative Electrocatalysts * Electrocatalyst Durability * Hydrogen Storage * Electrocatalyst Degradation Catalysis & Energy Conversion Home Hydrogen and Fuel Cell Materials Polymer electrolyte fuel cell (PEFC) systems are promising alternatives to conventional power systems for transportation, portable, and stationary applications due to their high efficiency of converting fuel to electricity, low emissions, and low operating temperatures. Three major issues for PEFC systems, especially for portable and transportation use, are cost, lifetime, and fuel storage, with the fuel of choice being hydrogen. Argonne's Hydrogen and Fuel Cell Materials group has active research projects in these three areas, to enable the use of this promising technology in a variety of applications.

131

Key Accomplishments @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

Recent Key Accomplishments Recent Key Accomplishments WGS: Importance of the Metal-Oxide Interface in Catalysis: In Situ Studies of the Water-Gas Shift Reaction by Ambient-Pressure X-ray Photoelectron Spectroscopy A New Type of Strong Metal-Support Interaction and the Production of H-2 through the Transformation of Water on Pt/CeO2(111) and Pt/CeOx/TiO2(110) Catalysts In situ studies of CeO2-supported Pt, Ru, and Pt-Ru alloy catalysts for the water-gas shift reaction: Active phases and reaction intermediates In situ/operando studies for the production of hydrogen through the water-gas shift on metal oxide catalysts Mechanistic understanding of WGS catalysts from first principles: Au(111) Supported Oxide Nanoparticles Theoretical catalyst optimization of WGS catalysts: Cu(111) supported oxide nanostructures

132

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Atom-Efficient Chemical Transformations Atom-Efficient Chemical Transformations iact logo Argonne National Laboratory along with its academic partners has established an Energy Frontier Research Center, the Institute for Atom-efficient Chemical Transformations (IACT) whose focus is to advance the science of catalysis for the efficient conversion of energy resources into usable forms. IACT is one of 46 Energy Frontier Research Centers that DOE has established in the United States. IACT is a partnership among world-class scientists at Argonne National Laboratory, Northwestern University, Purdue University, University of Wisconsin-Madison, and Brookhaven National Laboratory. Using a multidisciplinary approach involving integrated catalyst synthesis, advanced characterization, catalytic experimentation, and computation, IACT is addressing key

133

Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis  

SciTech Connect

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.

Cutler, A. R.

2001-04-14T23:59:59.000Z

134

Tandem Catalysis in Nanocrystal Interfaces | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Interfaces Interfaces Tandem Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View(active tab) Edit Workflow Addthis A unique new bilayer nanocatalyst system. | Image courtesy of Yang group A unique new bilayer nanocatalyst system. | Image courtesy of Yang group What does this mean for me? A prime example of these applications is artificial photosynthesis -- the effort to capture energy from the sun and transform it into electricity or chemical fuels. Catalysts (substances that speed up the rates of chemical reactions without themselves being chemically changed) are used to initiate virtually every industrial manufacturing process that involves chemistry. With the advent of nano-sized catalysts, metal and metal oxide catalysts have surged in importance. Recently, researchers at the Department's Lawrence Berkeley National

135

Structural and Functional Analysis of Mutations along the Crystallographic Dimer Interface of the Yeast TATA Binding Protein  

Science Journals Connector (OSTI)

...titration of recombinant TBP standards, spiked into a null...crystallographic dimer interface were mutated. Mutation...crystallographic dimer interface. Shown is a space-filling...wild type; std., standard. FIG. 3. Dimerization...crystallographic dimer interface. (A) Shown are space-filling...

Haiping Kou; Jordan D. Irvin; Kathryn L. Huisinga; Madhusmita Mitra; B. Franklin Pugh

2003-05-01T23:59:59.000Z

136

Ab initio correlated calculations of rare-gas dimer quadrupoles  

SciTech Connect

This paper reports ab initio calculations of rare gas (RG=Kr, Ar, Ne, and He) dimer quadrupoles at the second order of Moeller-Plesset perturbation theory (MP2). The study reveals the crucial role of the dispersion contribution to the RG{sub 2} quadrupole in the neighborhood of the equilibrium dimer separation. The magnitude of the dispersion quadrupole is found to be much larger than that predicted by the approximate model of Hunt. As a result, the total MP2 quadrupole moment is significantly smaller than was assumed in virtually all previous related studies. An analytical model for the distance dependence of the RG{sub 2} quadrupole is proposed. The model is based on the effective-electron approach of Jansen, but replaces the original Gaussian approximation to the electron density in an RG atom by an exponential one. The role of the nonadditive contribution in RG{sub 3} quadrupoles is discussed.

Donchev, Alexander G. [Algodign, LLC, Bolshaya Sadovaya 8, Moscow 123001 (Russian Federation)

2007-10-15T23:59:59.000Z

137

UV resonance Raman analysis of trishomocubane and diamondoid dimers  

SciTech Connect

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 2.33eV and 5.42eV. 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.

Meinke, Reinhard, E-mail: rene@physik.tu-berlin.de; Thomsen, Christian; Maultzsch, Janina [Institut fr Festkrperphysik, Technische Universitt Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany)] [Institut fr Festkrperphysik, Technische Universitt Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Richter, Robert; Merli, Andrea [Institut fr Optik und Atomare Physik, Technische Universitt Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany)] [Institut fr Optik und Atomare Physik, Technische Universitt 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

138

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

E-Print Network (OSTI)

337th Catalysis Research Center (CRC) Colloquium Fluorine Industry in China Lu Long (Shanghai, Central Research & Development, Experimental Station, DuPont Company, USA 1994.9 to1996.9 Postdoctoral

Ishii, Hitoshi

139

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

E-Print Network (OSTI)

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

Boyer, Edmond

140

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

E-Print Network (OSTI)

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...

Ryu, Youngha

2005-08-29T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts  

Energy.gov (U.S. Department of Energy (DOE))

The Bioenergy Technologies Office works with industry to develop pathways that use heat, pressure, and catalysis to convert domestic, non-food biomass into gasoline, jet fuel, and other products.

142

Variables in Reaction Design for Laboratory and Industrial Applications of Phase-Transfer Catalysis  

Science Journals Connector (OSTI)

Many factors, known and unknown, contribute to the effective selection of a catalyst and other conditions for a given phase-transfer catalysis (PTC) application. Therefore, no simple single guideline exists fo...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

143

Pressure dependent diffraction and spectroscopy of a dimerized antiferromagnet  

SciTech Connect

We present pressure dependent neutron diffraction and inelastic neutron scattering measurements of the dimerized antiferromagnet Ba$_3$Mn$_2$O$_8$. The room temperature diffraction measurements reveal a linear decrease in lattice constant as a function of applied pressure. No structural transitions are observed. The low-temperature neutron spectroscopy measurements indicate a small change in magnetic scattering intensity in the vicinity of the spin gap for pressures up to $P=0.6$~kbar.

Stone, Matthew B [ORNL; Tulk, Christopher A [ORNL; dos Santos, Antonio M. [Oak Ridge National Laboratory (ORNL); Molaison, Jamie J [ORNL; Chang, S. [Ames Laboratory; Leo, J B [National Institute of Standards and Technology (NIST), Gaithersburg, MD; Samulon, Eric C [Stanford University; Shapiro, Max C [Stanford University; Fisher, Ian R [Stanford University

2011-01-01T23:59:59.000Z

144

Dynamics of microcavity exciton polaritons in a Josephson double dimer  

Science Journals Connector (OSTI)

We study the dynamics of exciton polaritons in a double-well configuration. The system consists of two weakly coupled Bose-Josephson junctions, each corresponding to a different circular polarization of the polaritons, forming a Josephson double dimer. We show that the Josephson oscillation between the wells is strongly coupled to the polarization rotation and that, consequently, Josephson excitation is periodically exchanged between the two polarizations. Linearized analysis agrees well with numerical simulations using typical experimental parameters.

Christine Khripkov; Carlo Piermarocchi; Amichay Vardi

2013-12-10T23:59:59.000Z

145

Coherence oscillations between weakly coupled Bose-Hubbard dimers  

Science Journals Connector (OSTI)

We study theoretically the dynamics of two weakly coupled Bose-Josephson junctions, prepared with the same particle number N and Josephson excitation number ? but with different reduced one-particle purity ?. An entropy oscillation mode is predicted, in which one-particle coherence is transferred between the Bose-Hubbard dimers with no particle or energy transfer. We explain this purity oscillation using a semiclassical picture.

Christine Khripkov and Amichay Vardi

2014-05-30T23:59:59.000Z

146

On the photophysics and photochemistry of the water dimer  

SciTech Connect

The photochemistry of the water dimer irradiated by UV light is studied by means of the complete active space perturbation theory//complete active space self-consistent field (CASPT2//CASSCF) method and accurate computational approaches like as minimum energy paths. Both electronic structure computations and ab initio molecular dynamics simulations are carried out. The results obtained show small shifts relative to a single water molecule on the vertical excitation energies of the dimer due to the hydrogen bond placed between the water donor (W{sub D}) and the water acceptor (W{sub A}). A red-shift and a blue-shift are predicted for the W{sub D} and W{sub A}, respectively, supporting previous theoretical and experimental results. The photoinduced chemistry of the water dimer is described as a process occurring between two single water molecules in which the effect of the hydrogen bond plays a minor role. Thus, the photoinduced decay routes correspond to two photodissociation processes, one for each water molecule. The proposed mechanism for the decay channels of the lowest-lying excited states of the system is established as the photochemical production of a hydrogen-bonded H{sub 2}O Horizontal-Ellipsis HO species plus a hydrogen H atom.

Segarra-Marti, Javier; Merchan, Manuela [Instituto de Ciencia Molecular, Universitat de Valencia, P.O. Box 22085, 46071 Valencia (Spain); Roca-Sanjuan, Daniel; Lindh, Roland [Department of Chemistry - Angstroem, Theoretical Chemistry Program, Uppsala University, Box 518, 75120 Uppsala (Sweden)

2012-12-28T23:59:59.000Z

147

On the origin of the selectivity of oxygen reduction of ruthenium-containing electrocatalysts in methanol-containing electrolyte  

SciTech Connect

The reactivity with water and methanol of oxygen-reducing (Ru{sub 1{minus}x}Mo{sub x}SeO{sub z}) and oxygen (from water)-evolving electrocatalysts (RuS{sub 2}, RuO{sub 2}), which permit electron transfer via ruthenium d-states, was studied using electrochemical techniques and differential electrochemical mass spectroscopy (DEMS). In contrast to platinum, which is depolarized by methanol, ruthenium compounds show a high reactivity with water species and an extremely low reactivity with methanol. The authors conclude that the ruthenium-centered coordination chemical reactivity with water channels electrochemical currents, thus producing kinetic selectivity. The reason for the higher reactivity with water of Ru d-states as compared to platinum is seen in the higher density of d-states near the Fermi level as shown by this comparative study.

Alonso-Vante, N.; Bogdanoff, P.; Tributsch, H.

2000-03-10T23:59:59.000Z

148

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

SciTech Connect

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.

Wong, Michael S.

2008-01-01T23:59:59.000Z

149

Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal  

NLE Websites -- All DOE Office Websites (Extended Search)

Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Catalyst in MEAs Title Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Catalyst in MEAs Publication Type Journal Article Year of Publication 2012 Authors Zhu, Xiaobing, John B. Kerr, Qinggang He, Gi Suk Hwang, Zulima Martin, Kyle Clark, Adam Z. Weber, and Nana Zhao Journal ECS Transactions Volume 45 Issue 2 Pagination 143 - 152 Date Published 04/2012 ISSN 1938-6737 Abstract Transition metal porphyrin complexes have been mounted in a three dimensional homogenous distribution inside the ionomer of catalyst layers in MEAs to achieve competitive fuel cell catalysis activity. The effect of electrode components including ionomer, carbon, catalyst, and mediator, and ionomer film thickness, is investigated in fuel cell molecular catalysis system. Membrane electrode assembly (MEA) durability testing has been conducted. SEM and TEM techniques are employed to investigate molecular catalysis electrode micro- and nano- structure and morphology. To date, surprisingly, the best fuel cell performance, i.e. 1280 mA/cm2 of maximum/short-circuit current density is achieved, approaching that of Pt-based electrode, indicating higher turnover frequencies than Pt although with poorer voltages.

150

A problem on a dimer adsorbed at single-sheet graphene  

SciTech Connect

In the context of the previously proposed M model for the density of states in graphene (Davydov and Sabirova [3]), two adatoms coupled via the amplitude of electron transitions from one adatom to the other (direct exchange) are considered. An analytical expression for the energy density of states in/for the dimer is derived, and the dependence of the charge of the dimer's constituent atoms on the parameters of the problem is analyzed. The effect of image forces is investigated. In the context of the surface molecule model, a dimer composed of hydrogen adatoms is considered. The dissociation and desorption energies of such a dimer are estimated.

Davydov, S. Yu., E-mail: Sergei_Davydov@mail.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2012-03-15T23:59:59.000Z

151

Application of solid ash based catalysts in heterogeneous catalysis  

SciTech Connect

Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe{sub 2}O{sub 3} could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H{sub 2} production, deSOx, deNOx, hydrocarbon oxidation, and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. 107 refs., 4 figs., 2 tabs.

Shaobin Wang [Curtin University of Technology, Perth, WA (Australia). Department of Chemical Engineering

2008-10-01T23:59:59.000Z

152

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Fuel Cell Engineering Fuel Cell Engineering A H. Adachi, S. Ahmed, S. H. D. Lee, D. Papadias, R. K. Ahluwalia, J. C. Bendert, S. A. Kanner, and Y. Yamazaki, "A Natural-Gas Fuel Processor for a Residential Fuel Cell System," Journal of Power Sources, accepted for publication (2009) S. Ahmed, "Renewable Power Sources," (invited talk), University of Houston, Houston, TX, March 22-23, 2012. S. Ahmed, "Fuel Cell Based Combined Heat and Power for Small Systems (1-100 kW)," (invited talk), University of Houston, Houston, TX, March 22-23, 2012. S. Ahmed, R. Ahluwalia, S. H. D. Lee and S. Lottes, "A Gasoline Fuel Processor Designed to Study Quick-Start Performance," Journal of Power Sources 154(1), 214-222 (2006) C S. Y. Choung, M. Ferrandon, and T. Krause, "Pt-Re Bimetallic Supported on CeO2-ZrO2 Mixed Oxides as Water-Gas Shift Catalysts," Catalysis Today 99, 257-262 (2005)

153

Reaction of trans-dichloro-bis[N(1)-methyl-2-(arylazo)imidazole] ruthenium(II) with tertiary phosphines  

Science Journals Connector (OSTI)

Trans-dichloro-bis[N(1)-methyl-2-(arylazo)imidazol e] ruthenium(II) (tcc-Ru(MeL)2Cl2) reacts with tertiary phosphines giving rise to species of type [RuCl(P)-(MeL)2]+ and [Ru(P-P)(MeL)2]2+ in which Cl, P and P...

Tarun Kumar Misra; Chittaranjan Sinha

1999-04-01T23:59:59.000Z

154

Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source Tools |  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

1.2011]: Energy Efficiency, Catalysis and Open Source 1.2011]: Energy Efficiency, Catalysis and Open Source Tools Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source Tools March 11, 2011 - 4:37pm Addthis L. Keith Woo | Photo courtesy of Ames National Laboratory L. Keith Woo | Photo courtesy of Ames National Laboratory Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs Ames Laboratory researcher and Iowa State University professor L. Keith Woo is on the search for catalysts that lead to more efficient, safer and cleaner chemical reactions that work at lower pressures and temperatures and create less waste. In one project, Dr. Woo is working to understand the chemistry behind fast pyrolysis for creating bio-oil from biomass. Fast pyrolysis quickly heats up biomass (such as corn stalks and leaves) in the absence of oxygen to

155

THE 3D DIMER AND ISING PROBLEMS REVISITED MARTIN LOEBL AND LENKA ZDEBOROV  

E-Print Network (OSTI)

THE 3D DIMER AND ISING PROBLEMS REVISITED MARTIN LOEBL AND LENKA ZDEBOROV #19; A Abstract. We adjacency matrices, and the #12;nite 3D Ising partition sum as a linear combination of products over in basic statistical physics models, the Ising and the Dimer models. Let us mention two such recent

Loebl, Martin

156

An ethanol-solvated centrosymmetric dimer of bismuth(III) and thiosaccharinate resulting from `semicoordination' contacts  

Science Journals Connector (OSTI)

In an ethanol-solvated centrosymmetric dimer of bismuth(III) and thiosaccharinate, the Bi3+ cation is coordinated by three thiosaccharinate ligands, all of them acting as bidentate chelates through the N and exocyclic S atoms (in a 2N,S mode). Centrosymmetric dimers result from the association of molecules via - interactions.

Dennehy, M.

2014-05-28T23:59:59.000Z

157

Photochemical dimerization of a fluorinated dibenzylideneacetone in chloroform solution  

Science Journals Connector (OSTI)

(1E,4E)-1,5-Bis(2,6-difluorophenyl)penta-1,4-dien-3-one dimerizes under sunlight in chloroform solution to form the corresponding cyclobutane derivative. The dimer shows the `truxillic acid'-type arrangement of crystallographic centres of inversion, with cell dimensions closely related to those of the monomer.

Schwarzer, A.

2014-01-09T23:59:59.000Z

158

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 millimeter-wave data yielded the precise location of 33 new energy levels of A+ symmetry and 20 levels of A extensive millimeter-wave measurements of the 12C16O dimer have been made, and more than 300 new spectral

159

Complexation of fisetin with novel cyclosophoroase dimer to improve solubility and bioavailability  

Science Journals Connector (OSTI)

Abstract Rhizobium species produce cyclosophoraose (Cys), which is an unbranched cyclic ?-(1,2)-glucan. We synthesized novel cationic cyclosophoraose dimer (Cys dimer) and its structure was confirmed via NMR spectroscopy and MALDI-TOF mass spectrometry analysis. In this study, we investigated the complexation of hardly soluble drug fisetin (3,3?,4?,7-tetrahydroxyflavone) with Cys dimer to improve the solubility of fisetin, and its solubility was increased up to 6.5-fold. The solubility of fisetin with Cys dimer showed 2.4-fold better than with ?-cyclodextrin. The fisetinCys dimer complex was characterized by using, phase solubility diagram, 2D NMR, FT-IR spectroscopy, SEM, DSC analysis and molecular modeling. Through the molecular docking simulations, complexation ability of fisetin with host molecules were in the following order: Cys dimer>Cys monomer>?-CD. The fisetinCys dimer complex showed also higher cytotoxicity to HeLa cells than free fisetin, indicating that the Cys dimer to improve bioavailability of fisetin.

Daham Jeong; Jae Min Choi; Youngjin Choi; Karpjoo Jeong; Eunae Cho; Seunho Jung

2013-01-01T23:59:59.000Z

160

Nonlinear friction of a damped dimer sliding on a periodic substrate S. Gonalves,1,2,  

E-Print Network (OSTI)

Nonlinear friction of a damped dimer sliding on a periodic substrate S. Gonçalves,1,2, * V. M, USA (Received 23 July 2004; published 12 November 2004) The nonlinear sliding friction of a dimer over that the friction force has an approximate v-3 depen- dence if the velocity is sufficiently large

Kenkre, V.M.

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Modulation of Substrate Efflux in Bacterial Small Multidrug Resistance Proteins by Mutations at the Dimer Interface  

Science Journals Connector (OSTI)

...WT structure by measuring the intermonomer...the propagated standard errors of the means...was determined by measuring bacterial cell...TM4 dimerization interface have different...2003. Three-dimensional structure of the...mutations at the dimer interface. | Bacteria evade...

Bradley E. Poulsen; Fiona Cunningham; Kate K. Y. Lee; Charles M. Deber

2011-09-02T23:59:59.000Z

162

Crossover energetics for halogenated Si(100): Vacancy line defects, dimer vacancy lines, and atom vacancy lines  

Science Journals Connector (OSTI)

We investigated surface patterning of I-Si(100)-(21) both experimentally and theoretically. Using scanning tunneling microscopy, we first examined I destabilization of Si(100)-(21) at near saturation. Dimer vacancies formed on the terraces at 600 K, and they grew into lines that were perpendicular to the dimer rows, termed vacancy line defects. These patterns were distinctive from those induced by Cl and Br under similar conditions since the latter formed atom and dimer vacancy lines that were parallel to the dimer rows. Using first-principles density functional theory, we determined the steric repulsive interactions associated with iodine and showed how the observed defect patterns were related to these interactions. Concentration-dependent studies showed that the vacancy patterns were sensitive to the I concentration. Dimer and atom vacancy lines that were elongated along the dimer row direction were favored at lower coverage. Atom vacancy lines dominated at ?0.8ML, they coexisted with dimer vacancy lines at ?0.6-0.7ML, and dimer vacancy lines were exclusively observed below ?0.5ML. These surface patterns reflect the mean strength of the adatom repulsive interactions.

G. J. Xu; N. A. Zarkevich; Abhishek Agrawal; A. W. Signor; B. R. Trenhaile; D. D. Johnson; J. H. Weaver

2005-03-30T23:59:59.000Z

163

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

E-Print Network (OSTI)

processes are accompanied by a noticeable growth of the nuclear coordinate dispersion associatedElectron-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

164

Supported Molten Metal Catalysis. A New Class of Catalysts  

SciTech Connect

We describe a new class of heterogeneous catalysts called supported molten metal catalysis (SMMC), in which molten metal catalysts are dispersed as nanodroplets on the surface of porous supports, allowing much larger active surface area than is possible in conventional contacting techniques for catalytic metals that are molten under reaction conditions, thus greatly enhancing their activity and potential utility. Specific examples of different types of reactions are provided to demonstrate the broad applicability of the technique in designing active, selective, and stable new catalysts. It is shown that dispersing the molten metal on a support in the suggested manner can enhance the rate of a reaction by three to four orders of magnitude as a result of the concomitant increase in the active surface area. New reaction examples include {gamma}-Al{sub 2}O{sub 3} supported molten Te (melting point 450 C) and Ga (MP 30 C) catalysts for bifunctional methylcyclohexane dehydrogenation. These catalysts provide activity similar to conventional Pt-based catalysts for this with better resistance to coking. In addition, results are described for a controlled pore glass supported molten In (MP 157 C) catalyst for the selective catalytic reduction of NO with ethanol in the presence of water, demonstrating activities superior to conventional catalysts for this reaction. A discussion is also provided on the characterization of the active surface area and dispersion of these novel supported catalysts. It is clear based on the results described that the development of new active and selective supported molten metal catalysts for practical applications is entirely plausible.

Ravindra Datta; Ajeet Singh; Manuela Serban; Istvan Halasz

2006-06-02T23:59:59.000Z

165

Superfluidity and Dimerization in a Multilayered System of Fermionic Polar Molecules  

SciTech Connect

We consider a layered system of fermionic molecules with permanent dipole moments aligned perpendicular to the layers by an external field. The dipole interactions between fermions in adjacent layers are attractive and induce interlayer pairing. Because of the competition for pairing among adjacent layers, the mean-field ground state of the layered system is a dimerized superfluid, with pairing only between every other layer. We construct an effective Ising-XY lattice model that describes the interplay between dimerization and superfluid phase fluctuations. In addition to the dimerized superfluid ground state, and high-temperature normal state, at intermediate temperature, we find an unusual dimerized ''pseudogap'' state with only short-range phase coherence. We propose light-scattering experiments to detect dimerization.

Potter, Andrew C. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Berg, Erez; Halperin, Bertrand I.; Demler, Eugene [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Wang, Daw-Wei [Physics Department and NCTS, National Tsing-Hua University, Hsinchu 30013, Taiwan (China)

2010-11-26T23:59:59.000Z

166

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

SciTech Connect

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.

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

167

Human Macrophage Inflammatory Protein 3?: Protein and Peptide Nuclear Magnetic Resonance Solution Structures, Dimerization, Dynamics, and Anti-Infective Properties  

Science Journals Connector (OSTI)

...directly across the dimer interface on top of the b sheet...away from the dimer interface and is therefore not...the core b strands, measuring about 76 2.0 (59...by the use of two-dimensional homonuclear proton...His40 in the dimer interface. Moreover, a constrained...

David I. Chan; Howard N. Hunter; Brian F. Tack; Hans J. Vogel

2007-12-17T23:59:59.000Z

168

New Strategies for Organic Catalysis: The First Enantioselective Organocatalytic 1,3-Dipolar  

E-Print Network (OSTI)

Versity of California Berkeley, California 94720 DiVision of Chemistry and Chemical Engineering California Institute of broadly useful new strategies for enantioselective catalysis that utilize organic chemicals as reaction platform for the develop- ment of enantioselective organocatalytic Diels-Alder reactions (eq 2

MacMillan, David W. C.

169

Catalysis by dihydrofolate reductase and other enzymes arises from electrostatic preorganization,  

E-Print Network (OSTI)

Catalysis by dihydrofolate reductase and other enzymes arises from electrostatic preorganization dynamical effects. We then generate the catalytic land- scape of the enzyme and demonstrate that motions catalytic power of enzymes has been attempted to be rationalized by several proposals. Here, we would like

Barton, Paul I.

170

Structural model of F1ATPase and the implications for rotary catalysis  

Science Journals Connector (OSTI)

...and R. M. Simmons Structural model of F1-ATPase and the implications for rotary...crystal structure of bovine mitochondrial F1-ATPase is described. Several features...approximately spherical alpha3beta3 sub-assembly. F1-ATPase|crystal structure|rotary catalysis...

2000-01-01T23:59:59.000Z

171

High-throughput metal nanoparticle catalysis by pulsed laser ablation Selim Senkan a,*, Michael Kahn a  

E-Print Network (OSTI)

High-throughput metal nanoparticle catalysis by pulsed laser ablation Selim Senkan a,*, Michael online 18 July 2006 Abstract A high-throughput pulsed laser ablation (HT-PLA) system was developed-TEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The supported nanoparticles created by HT

Senkan, Selim M.

172

Pacific Northwest National Laboratory: INstItute for INterfacIaL cataLysIs  

E-Print Network (OSTI)

-pressure hydrogen may be the fuel/energy carrier in the long term, strategies to help supply and maintain the nation and diesel. the Institute for Interfacial catalysis is supporting PNNL's energy conversion Initiative conversion of coal to liquid transportation fuels. IndIReCt LIqueFaCtIon: MoRe VaLuabLe PRoduCts FoR Less

173

Journal of Catalysis 225 (2004) 300306 www.elsevier.com/locate/jcat  

E-Print Network (OSTI)

shown that methanol can be produced by using N2O as the oxidant, rather than O2 [1­3]. More recently framework positions and ex- traframework Fe) can be used to produce methanol from CH4 and N2O. Above 523 KJournal of Catalysis 225 (2004) 300­306 www.elsevier.com/locate/jcat Methanol formation on Fe

Bell, Alexis T.

174

Catalysis Today 53 (1999) 433441 New insights into methanol synthesis catalysts from X-ray absorption  

E-Print Network (OSTI)

O and Cr2O3 mixtures and produced methanol in low yields from CO­H2 mixtures at high temperatures (593Catalysis Today 53 (1999) 433­441 New insights into methanol synthesis catalysts from X a consistent structural picture of methanol synthesis catalysts. Copper metal is the principal Cu species

Iglesia, Enrique

175

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

E-Print Network (OSTI)

-734-763-0459. E-mail address: gulari@engin.umich.edu (E. Gulari). burn gasoline or a diesel engine. Early studiesApplied Catalysis A: General 226 (2002) 183­192 NO reduction by urea under lean conditions over, Jiraporn Leeratc, Somchai Osuwanc a Chemical Engineering Department, University of Michigan, Ann Arbor, MI

Gulari, Erdogan

176

ANL/ALCF/ESP-13/2 Materials Design and Discovery: Catalysis and  

E-Print Network (OSTI)

electronic) degrees of freedom are relevant, the methods of choice in the surface science, condensed matter) project was to perform fast-accurate DFT calculations on materials for energy and catalysis using the GPAW[1, 2, 3] code on Blue Gene/Q. The types of calculations included significantly reduced time

Kemner, Ken

177

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

E-Print Network (OSTI)

organisms1 . Although catalysis is thought to proceed through a substitution nucleophilic bimolecular (SN2) reaction1,2 , the role of the enzyme in modulating this chemical reaction is unknown. Here, using single of the catalytic reaction, the first requiring a reorientation of the substrate disulphide bond, causing a short

Fernandez, Julio M.

178

Diversity of chemical mechanisms in thioredoxin catalysis revealed by single-molecule force spectroscopy  

E-Print Network (OSTI)

-origin Trxs show both nucleophilic substitution (SN2) and SET reactions. A computational analysis of Trx-origin Trxs reduce disulfide bonds through a single-electron transfer reaction (SET), whereas bacterial of Trx catalysis. Enzymes are exceptional catalysts that can accelerate reaction rates by several orders

Berne, Bruce J.

179

Catalysis looks to the future. Panel on new directions in catalytic science and technology  

SciTech Connect

Catalysts play a vital role in providing society with fuels, commodity and fine chemicals, pharmaceuticals, and means for protecting the environment. To be useful, a good catalyst must have a high turnover frequency (activity), produce the right kind of product (selectivity), and have a long life (durability), all at an acceptable cost. Research in the field of catalysis provides the tools and understanding required to facilitate and accelerate the development of improved catalysts and to open opportunities for the discovery of new catalytic processes. The aim of this report is to identify the research opportunities and challenges for catalysis in the coming decades and to detail the resources necessary to ensure steady progress. Chapter 2 discusses opportunities for developing new catalysts to meet the demands of the chemical and fuel industries, and the increasing role of catalysis in environmental protection. The intellectual challenges for advancing the frontiers of catalytic science are outlined in Chapter 3. The human and institutional resources available in the US for carrying out research on catalysis are summarized in Chapter 4. The findings and recommendations of the panel for industry, academe, the national laboratories, and the federal government are presented in Chapter 5.

Not Available

1992-12-31T23:59:59.000Z

180

Matching measure, Benjamini-Schramm convergence and the monomer-dimer free energy  

E-Print Network (OSTI)

We define the matching measure of a lattice L as the spectral measure of the tree of self-avoiding walks in L. We connect this invariant to the monomer-dimer partition function of a sequence of finite graphs converging to L. This allows us to express the monomer-dimer free energy of L in terms of the measure. Exploiting an analytic advantage of the matching measure over the Mayer series then leads to new, rigorous bounds on the monomer-dimer free energies of various Euclidean lattices. While our estimates use only the computational data given in previous papers, they improve the known bounds significantly.

Mikls Abrt; Pter Csikvri; Tams Hubai

2014-05-26T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
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181

Solvent Viscosity and Interrelated Effects on Electrochemiluminescence Intensity of Tris(2,2-bipyridyl)ruthenium(II)  

Science Journals Connector (OSTI)

Solvent Viscosity and Interrelated Effects on Electrochemiluminescence Intensity of Tris(2,2-bipyridyl)ruthenium(II) ... 1 The mechanism accepted in the literature1b is the following: Clearly several processes occur in the mechanism, and each is dependent upon solvent properties to a certain degree. ... Solvent viscosity maps the macroscopic transition between the liquid and solid states and affects each component process of ECL. ...

Amy M. Scott; Radha Pyati

2001-08-02T23:59:59.000Z

182

Environmentally Friendly Oxidation of Biomass Derived 5-Hydroxymethylfurfural into 2,5-Diformylfuran Catalyzed by Magnetic Separation of Ruthenium Catalyst  

Science Journals Connector (OSTI)

Environmentally Friendly Oxidation of Biomass Derived 5-Hydroxymethylfurfural into 2,5-Diformylfuran Catalyzed by Magnetic Separation of Ruthenium Catalyst ... In this study, aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) was studied over a magnetic catalyst [Fe3O4@SiO2-NH2-Ru(III)]. ... 5-Hydroxymethylfurfural (HMF), which is generated by the dehydration of C6-based carbohydrates, is considered to be a key platform molecule. ...

Shuguo Wang; Zehui Zhang; Bing Liu; Jinlin Li

2014-03-12T23:59:59.000Z

183

E-Print Network 3.0 - active dimeric form Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

dimers, with the aim of explaining how these form at a comparatively low temperature. Disilane (which... to di11;use at 400500K 3 . When two groups are on adjacent ... Source:...

184

Relationship between Ultraviolet-B Sensitivity and Cyclobutane Pyrimidine Dimer Photorepair in Rice  

Science Journals Connector (OSTI)

......or photorepair, at least three independent experiments were car- ried out. The data taken from these experiments were averaged...Sutherland, B. M. (2000) UV-sensitive Norin 1 rice contains defective cyclobutane pyrimidine dimer photolyase. Plant Cell 12: 15691578......

Jun Hidema; Il-Kyung Song; Tadashi Sato; Tadashi Kumagai

2001-09-01T23:59:59.000Z

185

Photoionization spectra of silver dimers adsorbed on the surface of a ZnS single crystal  

Science Journals Connector (OSTI)

We use the photostimulated luminescence flash method to measure photoionization spectra of Ag2 clusters adsorbed on the surface of a ZnS single crystal. Adsorbed dimers of silver are prepared by treatment of the ...

O. V. Ovchinnikov; D. A. Minakov; M. S. Smirnov

2007-07-01T23:59:59.000Z

186

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

E-Print Network (OSTI)

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.

Omar Mustafa

2015-01-27T23:59:59.000Z

187

Conformational Diversity and Sub-states in Enzyme Catalysis | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Conformational Diversity and Sub-states in Enzyme Catalysis Conformational Diversity and Sub-states in Enzyme Catalysis November 01, 2013 Enzymes are great biocatalysts, and have attracted significant interest for industrial applications (including cellulosic ethanol) due to their remarkable catalytic efficiencies. The understanding of factors that enable enzymes to achieve the high catalytic efficiency will have large impact through design of new and powerful biocatalysts. Unfortunately, the understanding of these factors have largely remain a mystery so far. Using joint computational-experimental methodology we have developed a unique technique named quasi-anharmonic analysis (QAA) for identification of conformational diversity and conformational sub-states associated with enzyme function. As a result of this approach we have been able to develop

188

Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis.  

SciTech Connect

Experimental discoveries followed by theoretical interpretations that pave the way of further advances by experimentalists is a developing pattern in modern surface chemistry and catalysis. The revolution of modern surface science started with the development of surface-sensitive techniques such as LEED, XPS, AES, ISS and SIMS, in which the close collaboration between experimentalists and theorists led to the quantitative determination of surface structure and composition. The experimental discovery of the chemical activity of surface defects and the trends in the reactivity of transitional metals followed by the explanations from the theoretical studies led to the molecular level understanding of active sites in catalysis. The molecular level knowledge, in turn, provided a guide for experiments to search for new generation of catalysts. These and many other examples of successes in experiment-and-theory-combined studies demonstrate the importance of the collaboration between experimentalists and theorists in the development of modern surface science.

Somorjai, Gabor A.; Li, Yimin

2009-11-21T23:59:59.000Z

189

An infrared study of the influence of CO adsorption on the topology of supported ruthenium  

SciTech Connect

The interaction of CO with alumina-supported ruthenium, reduced at different temperatures, was investigated by following the development of infrared bands due to adsorbed CO. It was concluded that the adsorption of Co on Ru at 170-350 K leads to the oxidative disruption of Ru clusters as indicated by the slow transformation of the band at 2020-2040 cm{sup {minus}1} due to Ru{sub x}-CO to bands at 2140 and 2075 cm{sup {minus}1} attributed to Ru{sup n+}(CO){sub 2} species (n = 1-3). This process occurred more slowly under dry conditions, and in the presence of hydrogen, whereas it was accelerated by H{sub 2}O addition. Analysis of spectral features suggested the involvement of the isolated OH groups on the alumina support in the oxidative disruption process. It was demonstrated that at higher temperatures, namely at around 500 K, the presence of CO causes the reductive agglomeration of Ru{sup n+} sites, i.e., the reformation of Ru{sub x} clusters.

Solymosi, F.; Rasko, J. (Univ. of Szeged (Hungary))

1989-01-01T23:59:59.000Z

190

Impact of catalysis on the production of the top 50 US commodity chemicals  

SciTech Connect

Information on each chemical is stored in an accompanying Excel{trademark} 4.0 spreadsheet (``top5Ochem.xcl``). This analysis tool allows the user to make assumptions about process yield improvements and evaluate the corresponding impact on the process and feedstock energy. Many scenarios have been investigated and are reported in the text. If all of the catalytic processes associated with the top 50 chemicals were raised to their maximum process yields, the corresponding process and feedstock energy savings would exceed 0.47 quads per year. More realistic process yield improvements of 1%, 5%, and 10% where possible, would save 0.03, 0.14, and 0.23 quads per year. Many of the commodity chemicals face limitations from both the current catalyst and process. Catalysis is vital, but catalysis alone is not the answer to maximizing energy savings. Integration of catalysis development with process engineering research can lead to significant energy savings during the production of the top 50 chemicals.

Tonkovich, A.L.Y.

1994-03-01T23:59:59.000Z

191

NMR Computational Studies of Solid Acidity/Fundamental Studies of Catalysis by Solid Acids  

SciTech Connect

This project focused on catalysis by zeolites and the synergy of spectroscopic characterization and theoretical modeling. In collaboration with the Waroquier group in Belgium we used state-of-the-art quantum chemical simulations on a supramolecular model of both the HZSM-5 zeolite and the co-catalytic hydrocarbon pool species and calculated a full catalytic cycle (including all rate constants) for methanol-to-olefin (MTO) catalysis involving a hydrocarbon pool species. This work not only represents the most robust computational analysis of a successful MTO route to date, but it also succeeds in tying together the many experimental clues. That work was featured on the cover of Angewandte Chemie. More recently we elucidated several unsuspected roles for formaldehyde in methanol to olefin catalysis. Formaldehyde proves to be a key species responsible for both the growth of the catalytically active hydrocarbon pool and its inevitable aging into deactivated polycyclic aromatic species. The apparent inevitability of formaldehyde formation at high temperatures, in particular in contact with active metal or metal oxide surfaces, may put some fundamental limitations on the economic potential of conversion of methanol to olefins.

James F. Haw

2008-06-28T23:59:59.000Z

192

Electron-electron interaction effects on Peierls dimerization in a half-filled band  

Science Journals Connector (OSTI)

A novel real-space approach to dimerization in a half-filled band is developed to investigate effects of electron-electron interactions on the Peierls instability. Dimerization is shown to be a result of imperfect resonance between pairs of electron configurations related to each other by a mirror-plane symmetry passing through the longest diagonal of the infinite ring, and the kinetic- and potential-energy contributions to the barrier to resonance are identified separately. The effects of including the on-site, nearest-neighbor, and next-nearest-neighbor interactions are investigated, and in each case it is shown that the enhancement or reduction in dimerization can be predicted from elementary physical arguments. These predictions are then substantiated by exact numerical calculations on a ten-site ring, and finite-size effects are shown to be small. The principal results that are obtained are the following: (i) The on-site correlation U strongly enhances the dimerization, the enhancement being strongest for U?4t0, where 4t0 is the bandwidth of the uniform chain; (ii) the nearest-neighbor interaction V1 further enhances the dimerization until V1?12U, while V1>12U favors a uniform chain with a different broken-symmetry ground state, an on-site charge-density wave; (iii) for V1?12U, the second-neighbor interaction V2 reduces the dimerization slightly, although the dimerization is still stronger than that with an effective nearest-neighbor interaction V1-V2; (iv) for V1>12U, V2 destroys the on-site charge-density wave and the ground state is strongly dimerized again. The complete Parisier-Parr-Pople (PPP) Hamiltonian is discussed, and it is pointed out that the above results, together with the excited-state orderings in the PPP Hamiltonian, strongly indicate that the ground state of the PPP Hamiltonian is the dimerized state. The excited-state orderings in finite polyenes, spin-density distributions in polyacetylene, and our theoretical results all indicate then that explicit inclusion of Coulomb interactions may be necessary for an accurate description of the ground and excited states in polyacetylene.

S. N. Dixit and S. Mazumdar

1984-02-15T23:59:59.000Z

193

Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet  

NLE Websites -- All DOE Office Websites (Extended Search)

Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2011 J. Phys.: Condens. Matter 23 416003 (http://iopscience.iop.org/0953-8984/23/41/416003) Download details: IP Address: 128.219.49.9 The article was downloaded on 17/10/2011 at 17:07 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more Home Search Collections Journals About Contact us My IOPscience IOP PUBLISHING JOURNAL OF PHYSICS: CONDENSED MATTER J. Phys.: Condens. Matter 23 (2011) 416003 (9pp) doi:10.1088/0953-8984/23/41/416003 Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet M B Stone 1 , A Podlesnyak 1 , G Ehlers

194

Dimerization Induced Deprotonation of Water on RuO2(110)  

SciTech Connect

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).

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

195

Transformation of carbon monoxide dimer surface structures on yttrium oxide modified by silver  

SciTech Connect

It has been established that introducing ions of silver(II) in yttrium(III) oxide leads to the formation of a significant concentration of a paramagnetic dimer species (CO)/sub 2/-in the course of the adsorption of carbon monoxide, and that these dimers exhibit high thermal stability and reactivity. Reactions are proposed for the formation of the dimer species (CO)/sub 2//sup 2 -/ and (CO)/sub 2//sup -/ on the surface of the Ag/Y/sub 2/O/sub 3/ catalyst that involve the reduction of the anion vacancies and a change in the oxidation state of the silver ions. Modifying the yttrium oxide with ionic silver leads to a marked decrease in the strength of the oxidative ability of the surface of the catalyst for CO, while the nature of the active sites of the yttrium oxide, which adsorbs CO in three forms, remains unchanged.

Vydrin, S.N.; Bobolev, A.V.; Loginov, A.Yu.

1987-09-10T23:59:59.000Z

196

A phenylcarbazole functionalized ruthenium dye for efficient dye-sensitized solar cells  

Science Journals Connector (OSTI)

A new heteroleptic Ru(II) complex of [Ru(Hcpip)(Hdcbpy)(NCS)2]?[N(C4H9)4]+H2O {where Hcpip=2-(4-(9H-carbazol-9-yl)phenyl)-1H-imidazo[4,5-f] [1,10]phenanthroline, Hdcbpy=4-carboxylic acid-4?-carboxylate-2,2?-bipyridine} has been synthesized and demonstrated to function as an efficient sensitizer for nanocrystalline TiO2-based dye-sensitized solar cell (DSSC). The DSSC based on this Ru(II) complex showed a short-circuit photocurrent density of 19.2mAcm?2, an open-circuit photovoltage of 630mV, a fill factor of 57.7%, corresponding to an overall light to electricity conversion efficiency of 6.98% under simulated solar light irradiation at 100mWcm?2. This efficiency value is 2.81- and 1.08-fold efficiency values of 2.48% and 6.47% observed for carbazole-free parent complex [Ru(Hpip)(Hdcbpy)(NCS)2]?[N(C4H9)4]+H2O {where Hpip=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline}- and cis-bis(isothiocyanato)bis(4,4?-dicarboxylic acid-2,2?-bipyridine)ruthenium(II) N3-based solar cells respectively, under identical experimental conditions. The molecular structures and electronic properties of the Ru(II) complexes were also investigated by means of density functional theory calculations in an effort to understand the device performance observed.

Su-Hua Fan; An-Guo Zhang; Chuan-Chuan Ju; Ke-Zhi Wang

2011-01-01T23:59:59.000Z

197

Universal Dimer in a Collisionally Opaque Medium: Experimental Observables and Efimov Resonances  

Science Journals Connector (OSTI)

A universal dimer is subject to secondary collisions with atoms when formed in a cloud of ultracold atoms via three-body recombination. We show that in a collisionally opaque medium, the value of the scattering length that results in the maximum number of secondary collisions may not correspond to the Efimov resonance at the atom-dimer threshold and thus cannot be automatically associated with it. This result explains a number of controversies in recent experimental results on universal three-body states and supports the emerging evidence for the significant finite range corrections to the first excited Efimov energy level.

Olga Machtey; David A. Kessler; Lev Khaykovich

2012-03-30T23:59:59.000Z

198

Dimerization of wild-type and mutant epidermal growth factor receptors prevalent in glioblastoma multiforme, using bioluminescent resonance energy transfer  

Science Journals Connector (OSTI)

...bioluminescent resonance energy transfer Aaron Gajadhar...however, the dimerization status of mutant EGFRs remain...to study dimerization status of wt and mutant EGFRs...bioluminescence resonance energy transfer, or BRET. This...BRET signal will allow us to decipher the different...

Aaron Gajadhar and Abhijit Guha

2007-05-01T23:59:59.000Z

199

Human Macrophage Inflammatory Protein 3?: Protein and Peptide Nuclear Magnetic Resonance Solution Structures, Dimerization, Dynamics, and Anti-Infective Properties  

Science Journals Connector (OSTI)

...hydrodynamic radii for spherical proteins similar in size...manner, with the loop bent toward the face of the...simulations. In the crystal dimer structures of MIP-3a...interactions with Phe4. In the crystal dimer structure of MIP-3a...than they are in the crystal structure (Fig. 5B...

David I. Chan; Howard N. Hunter; Brian F. Tack; Hans J. Vogel

2007-12-17T23:59:59.000Z

200

Functional Networks of Organic and Coordination Polymers: Catalysis of Fructose Conversion  

Science Journals Connector (OSTI)

All chemicals and solvents used were obtained from Sigma-Aldrich Chemical Co. and were of the highest purity available. ... To elucidate the utility of the stable, porous and functional composite materials developed in this work, we focused on the heterogeneous catalysis of the conversion of a biosourced substrate, fructose, into 5-hydroxymethylfurfural (HMF), one of the most important platform molecules for, for example, liquid biofuel and polyester production (SI Figure S10). ... Physical Chemistry Chemical Physics (2012), 14 (40), 13914-13917 CODEN: PPCPFQ; ISSN:1463-9076. ...

Lev Bromberg; Xiao Su; T. Alan Hatton

2014-10-23T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Catalysis and activation of magic states in fault-tolerant architectures  

SciTech Connect

In many architectures for fault-tolerant quantum computing universality is achieved by a combination of Clifford group unitary operators and preparation of suitable nonstabilizer states, the so-called magic states. Universality is possible even for some fairly noisy nonstabilizer states, as distillation can convert many noisy copies into fewer purer magic states. Here we propose protocols that exploit multiple species of magic states in surprising ways. These protocols provide examples of previously unobserved phenomena that are analogous to catalysis and activation well known in entanglement theory.

Campbell, Earl T. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom) and Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany)

2011-03-15T23:59:59.000Z

202

Chromomagnetic catalysis of color superconductivity in a (2+1)-dimensional NambuJona-Lasinio model  

Science Journals Connector (OSTI)

We investigate the influence of a constant uniform external chromomagnetic field H on the formation of color superconductivity. The consideration is made in the framework of a (2+1)-dimensional NambuJona-Lasinio model with two different four-fermionic structures responsible for ?qq? and diquark ?qq? condensates. In particular, it is shown that there exists a critical value Hc of the external chromomagnetic field such that at H>Hc a nonvanishing diquark condensate is dynamically created (the so-called chromomagnetic catalysis effect of color superconductivity). Moreover, external chromomagnetic fields may in some cases enhance the diquark condensate of color superconductivity.

D. Ebert, K. G. Klimenko, and H. Toki

2001-06-13T23:59:59.000Z

203

Extraction behavior of uranium(VI), plutonium(IV), zirconium(IV), ruthenium(III) and europium(III) with ?-pre-irradiated solutions of N,N?-methylbutyl substituted amides in n-dodecane  

Science Journals Connector (OSTI)

The extraction of plutonium(IV), uranium(VI), zirconium(IV), europium(III) and ruthenium(III) with ?-pre-irradiated n-dodecane solutions of methylbutyl substituted hexanamide (MBHA), octanamide (MBOA) and deca...

P. B. Ruikar; M. S. Nagar; M. S. Subramanian

1995-09-15T23:59:59.000Z

204

The critical Z-invariant Ising model via dimers: the periodic case  

E-Print Network (OSTI)

The critical Z-invariant Ising model via dimers: the periodic case C´edric Boutillier , B´eatrice de Tili`ere Abstract We study a large class of critical two-dimensional Ising models namely critical Z-invariant Ising models on periodic graphs, example of which are the classical Z2 , triangular

Boutillier, Cédric

205

The critical Z-invariant Ising model via dimers: locality property  

E-Print Network (OSTI)

The critical Z-invariant Ising model via dimers: locality property C´edric Boutillier , B´eatrice de Tili`ere Abstract We study a large class of critical two-dimensional Ising models, namely critical Z-invariant Ising models. Fisher [Fis66] introduced a correspondence between the Ising model

Boutillier, Cédric

206

Formation of clean dimers during gas-source growth of Si(001) D.R.Bowler  

E-Print Network (OSTI)

-source growth of Si(001) using hydrogen-based precursors (such as SiH 4 , silane, and Si 2 H 6 , disilane observations of the growth of Si(001) from disilane, both at room temperature following anneals 1 dimers, with the aim of explaining how these form at a comparatively low temperature. Disilane (which

Bowler, David

207

Rows of ATP Synthase Dimers in Native Mitochondrial Inner Membranes Nikolay Buzhynskyy,* Pierre Sens,y  

E-Print Network (OSTI)

Rows of ATP Synthase Dimers in Native Mitochondrial Inner Membranes Nikolay Buzhynskyy,* Pierre Marseille, France ABSTRACT The ATP synthase is a nanometric rotary machine that uses a transmembrane electrochemical gradient to form ATP. The structures of most components of the ATP synthase are known, andtheir

Sens, Pierre

208

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

E-Print Network (OSTI)

of intact and dissociated states of water are similar. Proton transfer between water moleculesProton transfer in adsorbed water dimers Xiao Liang Hu, Jir i´ Klimes and Angelos Michaelides 25th February 2010 DOI: 10.1039/b924422k Density functional theory simulations of water on MgO(001

Alavi, Ali

209

Isotope effects and Born-Oppenheimer breakdown in excited singlet states of the lithium dimer  

E-Print Network (OSTI)

Isotope effects and Born-Oppenheimer breakdown in excited singlet states of the lithium dimer A of infrared electronic transitions involving the 1 1 g state of 7 Li2 has instigated an investigation of Born-Oppenheimer and the leading vibrational and/or rotational Born-Oppenheimer breakdown terms for the X 1 g , A 1 u , B 1 u

Le Roy, Robert J.

210

UV Radiation??Sensitive Norin 1 Rice Contains Defective Cyclobutane Pyrimidine Dimer Photolyase  

Science Journals Connector (OSTI)

...increasing UVB doses, kept in the...the no-UV radiation (no dimer...the measured range of initial net...Quantitation of radiation-, chemical...ultraviolet light and ionizing radiation Harm W. Rupert...ultraviolet dose-rate meter...

Jun Hidema; Tadashi Kumagai; Betsy M. Sutherland

211

Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons to Fibrils  

E-Print Network (OSTI)

Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons, San Francisco, California 94143, United States *S Supporting Information ABSTRACT: Enamel matrix self-assembly tested if amelogenin, the main enamel matrix protein, can self-assemble into ribbon-like structures

Sali, Andrej

212

Forster resonance energy transfer in liposomes: Measurements of transmembrane helix dimerization in the native  

E-Print Network (OSTI)

Fo¨rster resonance energy transfer in liposomes: Measurements of transmembrane helix dimerization membranes. ? 2005 Elsevier Inc. All rights reserved. Free energy measurements of transmembrane (TM)1 helix system, however, measuring the thermodynamics of membrane protein association is a challenge. Here we

Wimley, William C.

213

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

E-Print Network (OSTI)

located at 50 -end of all nascent HIV-1 transcripts interacts with a key regulatory protein, Tat 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

Stuart, Steven J.

214

Alignment of molecules in gaseous transport: Alkali dimers in supersonic nozzle beams  

E-Print Network (OSTI)

Alignment of molecules in gaseous transport: Alkali dimers in supersonic nozzle beams M. P. SinhaO) + a.P lcosO), where 0 is the angle between the angular momentum vector J of the molecule and the beam direction. This method is applied to determine the alignment of Na2 molecules in a supersonic nozzle beam

Zare, Richard N.

215

Channeling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J. Fisch  

E-Print Network (OSTI)

, with electrons kept cold, so that the effective fusion reactivity can be increased [9­11]. The meansChanneling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J greatly facilitate controlled nuclear fusion. The parameter range for achieving this temperature disparity

216

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

E-Print Network (OSTI)

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

MacMillan, David W. C.

217

Chemoselective SN2? reaction of nitroalkanes to dialkyl 2-(bromomethyl)fumarates under cetyltrimethylammonium hydroxide (CTAOH) catalysis  

Science Journals Connector (OSTI)

The chemoselective SN2? reaction of a variety of primary nitroalkanes to dialkyl 2-(bromomethyl)fumarates can be efficiently performed under cetyltrimethylammonium hydroxide (CTAOH) catalysis. The ?,?-unsaturated esters were obtained in satisfactory to good yields with the complete retention of the nitro group.

Roberto Ballini; Serena Gabrielli; Alessandro Palmieri

2010-01-01T23:59:59.000Z

218

Selective Transformation of 5-Hydroxymethylfurfural into the Liquid Fuel 2,5-Dimethylfuran over Carbon-Supported Ruthenium  

Science Journals Connector (OSTI)

Selective Transformation of 5-Hydroxymethylfurfural into the Liquid Fuel 2,5-Dimethylfuran over Carbon-Supported Ruthenium ... A simple and efficient process was presented for the selective hydrogenation of 5-hydroxymethylfurfural (HMF) into the high-quality liquid fuel 2,5-dimethylfuran (DMF) in the presence of tetrahydrofuran (THF). ... (1-3) Among the many possible chemicals, 5-hydroxymethylfurfural (HMF), which can be produced from a variety of biomass-derived carbohydrates,(4-8) is recognized as a versatile intermediate (Scheme 1), and it can be further converted into a series of high-quality fuels such as ethyl levulinate (EL),(9) 5-ethoxymethylfurfural (EMF),(10) 2,5-dimethylfuran (DMF),(11) C9C15 alkanes,(12) and high-value chemicals such as levulinic acid (LA),(13) 2,5-dihydroxymethylfurfural (DHMF),(14) 2,5-diformylfuran (DFF),(15) and 2,5-furandicarboxylic acid (FDCA). ...

Lei Hu; Xing Tang; Jiaxing Xu; Zhen Wu; Lu Lin; Shijie Liu

2014-02-02T23:59:59.000Z

219

Atomic site sensitive processes in low energy ion-dimer collisions  

E-Print Network (OSTI)

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.

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

2014-05-12T23:59:59.000Z

220

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

E-Print Network (OSTI)

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 ...

Medley, Jonathan William

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Conditional Glycosylation in Eukaryotic Cells Using a Biocompatible Chemical Inducer of Dimerization  

Science Journals Connector (OSTI)

Here we report a new biocompatible CID, Tmp-SLF, which dimerizes E. coli DHFR and FKBP and has no endogenous mammalian targets that would lead to unwanted in vivo side effects. ... We employed Tmp-SLF to modulate gene expression in a yeast three-hybrid assay. ... Finally, we engineered the Golgi-resident glycosyltransferase FucT7 for tunable control by Tmp-SLF in mammalian cells. ...

Jennifer L. Czlapinski; Michael W. Schelle; Lawrence W. Miller; Scott T. Laughlin; Jennifer J. Kohler; Virginia W. Cornish; Carolyn R. Bertozzi

2008-09-13T23:59:59.000Z

222

A Triphenylamine-Grafted Imidazo[4,5-f][1,10]phenanthroline Ruthenium(II) Complex: Acid?Base and Photoelectric Properties  

Science Journals Connector (OSTI)

A new heteroleptic ruthenium(II) complex of [Ru(Hipdpa)(Hdcbpy)(NCS)2]?0.5H+0.5[N(C4H9)4]+Ru(Hipdpa) {where Hdcbpy = monodeprotonated 4,4?-dicarboxy-2,2?-bipyridine and Hipdpa = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline} was ...

Su-Hua Fan; An-Guo Zhang; Chuan-Chuan Ju; Li-Hua Gao; Ke-Zhi Wang

2010-03-25T23:59:59.000Z

223

Theoretical Studies on Two-Dimensional Nonlinear Optical Chromophores with Pyrazinyl Cores and Organic or Ruthenium(II) Ammine Electron Donors  

Science Journals Connector (OSTI)

Benjamin J. Coe * and Rachel A. Pilkington ... Coe, B. J.; Harris, J. A.; Asselberghs, I.; Persoons, A.; Jeffery, J. C.; Rees, L. H.; Gelbrich, T.; Hursthouse, M. B.Tuning of Charge-Transfer Absorption and Molecular Quadratic Nonlinear Optical Properties in Ruthenium(II) Ammine Complexes J. Chem. ... Coe, Benjamin J.; Harris, James A.; Asselberghs, Inge; Persoons, Andre; Jeffery, John C.; Rees, Leigh H.; Gelbrich, Thomas; Hursthouse, Michael B. ...

Benjamin J. Coe; Rachel A. Pilkington

2014-02-27T23:59:59.000Z

224

Lab Safety: RuO4Lab Safety: RuO4 Ruthenium tetroxide is a strong oxidizing agent and must be stored in the  

E-Print Network (OSTI)

Lab Safety: RuO4Lab Safety: RuO4 RuO4 Note: Ruthenium tetroxide is a strong oxidizing agent with sodium bisulfite solution to decompose RuO4 and then flush with plenty of water. #12;Lab Safety:Lab Safety: Reaction used to create RuO4 for staining: RuCl3 #12;Sodium hypochlorite: HARMFUL IF SWALLOWED

Cohen, Robert E.

225

Argonne CNM Highlight: Gold nanoparticles create visible-light catalysis in  

NLE Websites -- All DOE Office Websites (Extended Search)

Silver chloride-gold nanoparticles Gold-coated silver chloride (AgCl) nanowires at the microscopic level. In the News United Press International | PhysOrg.com | R&D Magazine| Nanotechnology Now | Photonics.com Gold nanoparticles create visible-light catalysis in nanowires A two-step approach has been developed within the Nanophotonics Group to synthesize AgCl nanowires decorated with gold nanoparticles by using silver nanowires as chemical templates. In the first step, the silver nanowires are chemically oxidized and converted to AgCl nanowires. In the second step, ions generated in the first step reduce gold precursors (e.g., NaAuCl4) to deposit gold nanoparticles on the AgCl nanowire surfaces, resulting in the formation of AgCl:gold composite nanowires. Because of the

226

States with identical steady dissipation rate: Role of kinetic constants in enzyme catalysis  

E-Print Network (OSTI)

A non-equilibrium steady state is characterized by a non-zero steady dissipation rate. Chemical reaction systems under suitable conditions may generate such states. We propose here a method that is able to distinguish states with identical values of the steady dissipation rate. This necessitates a study of the variation of the entropy production rate with the experimentally observable reaction rate in regions close to the steady states. As an exactly-solvable test case, we choose the problem of enzyme catalysis. Link of the total entropy production with the enzyme efficiency is also established, offering a desirable connection with the inherent irreversibility of the process. The chief outcomes are finally noted in a more general reaction network with numerical demonstrations.

Banerjee, Kinshuk

2014-01-01T23:59:59.000Z

227

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

E-Print Network (OSTI)

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.

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

2007-01-01T23:59:59.000Z

228

Protein conformational dynamics in the mechanism of HIV-1 protease catalysis  

SciTech Connect

We have used chemical protein synthesis and advanced physical methods to probe dynamics-function correlations for the HIV-1 protease, an enzyme that has received considerable attention as a target for the treatment of AIDS. Chemical synthesis was used to prepare a series of unique analogues of the HIV-1 protease in which the flexibility of the 'flap' structures (residues 37-61 in each monomer of the homodimeric protein molecule) was systematically varied. These analogue enzymes were further studied by X-ray crystallography, NMR relaxation, and pulse-EPR methods, in conjunction with molecular dynamics simulations. We show that conformational isomerization in the flaps is correlated with structural reorganization of residues in the active site, and that it is preorganization of the active site that is a rate-limiting factor in catalysis.

Torbeev, Vladimir Yu.; Raghuraman, H.; Hamelberg, Donald; Tonelli, Marco; Westler, William M.; Perozo, Eduardo; Kent, Stephen B.H. (GSU); (UW); (UC)

2013-09-17T23:59:59.000Z

229

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

SciTech Connect

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.

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

230

The Structure of the MAP2K MEK6 Reveals an Autoinhibitory Dimer  

SciTech Connect

MAP2Ks are dual-specificity protein kinases functioning at the center of three-tiered MAP kinase modules. The structure of the kinase domain of the MAP2K MEK6 with phosphorylation site mimetic aspartic acid mutations (MEK6/{Delta}N/DD) has been solved at 2.3 {angstrom} resolution. The structure reveals an autoinhibited elongated ellipsoidal dimer. The enzyme adopts an inactive conformation, based upon structural queues, despite the phosphomimetic mutations. Gel filtration and small-angle X-ray scattering analysis confirm that the crystallographically observed ellipsoidal dimer is a feature of MEK6/{Delta}N/DD and full-length unphosphorylated wild-type MEK6 in solution. The interface includes the phosphate binding ribbon of each subunit, part of the activation loop, and a rare 'arginine stack' between symmetry-related arginine residues in the N-terminal lobe. The autoinhibited structure likely confers specificity on active MAP2Ks. The dimer may also serve the function in unphosphorylated MEK6 of preventing activation loop phosphorylation by inappropriate kinases.

Min, Xiaoshan; Akella, Radha; He, Haixia; Humphreys, John M.; Tsutakawa, Susan E.; Lee, Seung-Jae; Tainer, John A.; Cobb, Melanie H.; Goldsmith, Elizabeth J.

2009-07-13T23:59:59.000Z

231

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

SciTech Connect

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.

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

2010-07-20T23:59:59.000Z

232

A Novel Dimer Interface and Conformational Changes Revealed by an X-ray Structure of B. subtilis SecA  

SciTech Connect

The SecA ATPase moves polypeptides post-translationally across the plasma membrane of eubacteria, but the mechanism of transport is still unclear. We describe the crystal structure of a novel dimeric form of Bacillus subtilis SecA. Dimerization of SecA occurs at the prominent groove formed by the nucleotide binding domain 2 (nbd2) and the preprotein cross-linking (ppx) domain. The dimer interface is very large, burying approximately 5400 {angstrom}{sup 2} of solvent accessible surface per monomer. Single cysteine disulfide cross-linking shows the presence of this novel SecA dimer in solution. In addition, other dimers also exist in solution, arguing that they all are in equilibrium with monomeric SecA and supporting the idea that the monomer may be the functional species. Dimerization of SecA causes an {alpha}-helix of one subunit to convert to a short {beta}-strand that participates in {beta}-sheet formation with strands in the other subunit. This conversion of secondary structure elements occurs close to the connection between the nbd1 and ppx domains, a potential site of interaction with translocation substrate. Comparing the different X-ray structures of B. subtilis SecA suggests that small changes in the nucleotide binding domains could be amplified via helix 1 of the helical scaffold domain (hsd) to generate larger movements of the domains involved in polypeptide binding.

Zimmer,J.; Li, W.; Rapoport, T.

2006-01-01T23:59:59.000Z

233

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

SciTech Connect

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.

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

2010-11-03T23:59:59.000Z

234

Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Parametric Gasification of Oak Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis Jason Hrdlicka, Calvin Feik, Danny Carpenter, and Marc Pomeroy Technical Report NREL/TP-510-44557 December 2008 Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis Jason Hrdlicka, Calvin Feik, Danny Carpenter, and Marc Pomeroy Prepared under Task No. H2713B13 Technical Report NREL/TP-510-44557 December 2008 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 * www.nrel.gov NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Operated by the Alliance for Sustainable Energy, LLC

235

Critical Endpoint and Inverse Magnetic Catalysis for Finite Temperature and Density Quark Matter in a Magnetic Background  

E-Print Network (OSTI)

In this article we study chiral symmetry breaking for quark matter in a magnetic background, $\\bm B$, at finite temperature and quark chemical potential, $\\mu$, making use of the Ginzburg-Landau effective action formalism. As a microscopic model to compute the effective action we use the renormalized quark-meson model. Our main goal is to study the evolution of the critical endpoint, ${\\cal CP}$, as a function of the magnetic field strength, and investigate on the realization of inverse magnetic catalysis at finite chemical potential. We find that the phase transition at zero chemical potential is always of the second order; for small and intermediate values of $\\bm B$, ${\\cal CP}$ moves towards small $\\mu$, while for larger $\\bm B$ it moves towards moderately larger values of $\\mu$. Our results are in agreement with the inverse magnetic catalysis scenario at finite chemical potential and not too large values of the magnetic field, while at larger $\\bm B$ direct magnetic catalysis sets in.

M. Ruggieri; L. Oliva; P. Castorina; R. Gatto; V. Greco

2014-02-04T23:59:59.000Z

236

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

SciTech Connect

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.

Daniela Rodica Radu

2005-12-19T23:59:59.000Z

237

Directed transport in equilibrium : analysis of the dimer model with inertial terms  

E-Print Network (OSTI)

We have previously shown an analysis of our dimer model in the over-damped regime to show directed transport in equilibrium. Here we analyze the full model with inertial terms present to establish the same result. First we derive the Fokker-Planck equation for the system following a Galilean transformation to show that a uniformly translating equilibrium distribution is possible. Then, we find out the velocity selection for the centre of mass motion using that distribution on our model. We suggest generalization of our calculations for soft collision potentials and indicate to interesting situation with possibility of oscillatory non-equilibrium state within equilibrium.

A. Bhattacharyay

2011-08-15T23:59:59.000Z

238

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

SciTech Connect

Metalorganic 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.

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

239

Structure of the Response Regulator PhoP from Mycobacterium tuberculosis Reveals a Dimer Through the Receiver Domain  

SciTech Connect

The PhoP protein from Mycobacterium tuberculosis is a response regulator of the OmpR/PhoB subfamily, whose structure consists of an N-terminal receiver domain and a C-terminal DNA-binding domain. How the DNA-binding activities are regulated by phosphorylation of the receiver domain remains unclear due to a lack of structural information on the full-length proteins. Here we report the crystal structure of the full-length PhoP of M. tuberculosis. Unlike other known structures of full-length proteins of the same subfamily, PhoP forms a dimer through its receiver domain with the dimer interface involving {alpha}4-{beta}5-{alpha}5, a common interface for activated receiver domain dimers. However, the switch residues, Thr99 and Tyr118, are in a conformation resembling those of nonactivated receiver domains. The Tyr118 side chain is involved in the dimer interface interactions. The receiver domain is tethered to the DNA-binding domain through a flexible linker and does not impose structural constraints on the DNA-binding domain. This structure suggests that phosphorylation likely facilitates/stabilizes receiver domain dimerization, bringing the DNA-binding domains to close proximity, thereby increasing their binding affinity for direct repeat DNA sequences.

S Menon; S Wang

2011-12-31T23:59:59.000Z

240

Electrochemical reductions of Hg(II), ruthenium-nitrosyl complex, chromate, and nitrate in a strong alkaline solution  

SciTech Connect

The electrochemistry of low-level nuclear wastes, the reductions of Hg(II), [RuNO(NO{sub 2}){sub 4}OH]{sup 2{minus}}, CrO{sub 4}{sup 2{minus}}, and NO{sub 3}{sup {minus}} in 1.33 M NaOH solution have been studied primarily at nickel electrodes for electrocatalytic advantages. Hg(II) was reduced to Hg metal [equilibrium potential of 0.099 V vs NHE (normal hydrogen electrode)]. The ruthenium-nitrosyl complex, [RuNO(NO{sub 2}){sub 4}OH]{sup 2{minus}}, was reduced to Ru metal (half-wave potential of {minus}0.38 V vs NHE). Chromate was reduced to chromic hydroxide (equilibrium potential of {minus}0.24 V vs NHE). Nitrate reduction has two different regions of Tafel behavior from which reduction mechanisms are proposed. The exchange current densities for the nitrate reduction at Ni, Pb, Fe, and graphite were measured and the competition of the nitrate reduction with the hydrogen evolution investigated.

Bockris, J.O`M.; Kim, J. [Texas A and M Univ., College Station, TX (United States)

1996-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

A New Scanning Tunneling Microscope Reactor Used for High Pressure and High Temperature Catalysis Studies  

SciTech Connect

We present the design and performance of a home-built high-pressure and high-temperature reactor equipped with a high-resolution scanning tunneling microscope (STM) for catalytic studies. In this design, the STM body, sample, and tip are placed in a small high pressure reactor ({approx}19 cm{sup 3}) located within an ultrahigh vacuum (UHV) chamber. A sealable port on the wall of the reactor separates the high pressure environment in the reactor from the vacuum environment of the STM chamber and permits sample transfer and tip change in UHV. A combination of a sample transfer arm, wobble stick, and sample load-lock system allows fast transfer of samples and tips between the preparation chamber, high pressure reactor, and ambient environment. This STM reactor can work as a batch or flowing reactor at a pressure range of 10{sup -13} to several bars and a temperature range of 300-700 K. Experiments performed on two samples both in vacuum and in high pressure conditions demonstrate the capability of in situ investigations of heterogeneous catalysis and surface chemistry at atomic resolution at a wide pressure range from UHV to a pressure higher than 1 atm.

Tao, Feng; Tang, David C.; Salmeron, Miquel; Somorjai, Gabor A.

2008-05-12T23:59:59.000Z

242

Catalysis and clean environment: What do these two have in common?  

SciTech Connect

The theme of the 1990s, ``Continual Expansion through Sustainable Development,`` is the outcome of interdisciplinary studies undertaken in the preceding two decades to arrest ongoing global environmental deterioration. A critical component of various international efforts to formulate and implement environmentally-sound technologies is the planned involvement of developing countries and countries with economies in-transition which are poised for explosive growth well into the twenty-first century but do not have policies or financial resources to simultaneously manage their environment. Though CO{sub 2}-producing, technologies utilizing relatively abundant and inexpensive carbon-based feedstocks will still play a major role on the scene. Related to this, the aim of the ongoing effort at Brookhaven National Laboratory is to develop technologies for enhancing natural gas and coal usage through liquid phase catalysis. A successful application of this concept in the synthesis of oxygenates is described. The potential impact of this activity on methanol-energy, non-petroleum feedstocks development, H{sub 2}-energy, CO{sub 2}-recycle, and several other areas in relation to CO{sub 2}-mitigation, is also discussed.

Mahajan, D.; Gupta, N.; Kobayashi, A.

1993-07-01T23:59:59.000Z

243

DFT calculations of EPR parameters of transition metal complexes: Implications for catalysis  

SciTech Connect

Transition metal and ligand hyperfine coupling constants for paramagnetic vanadium and copper model complexes have been calculated using DFT methods that are available in commercial software packages. Variations in EPR parameters with ligand identity and ligand orientation are two of the trends that have been investigated with DFT calculations. For example, the systematic variation of the vanadium hyperfine coupling constant with orientation for an imidazole ligand in a VO2+ complex has been observed experimentally and has also been reproduced by DFT calculations. Similarly, changes in the vanadium hyperfine coupling constant with ligand binding have been calculated using model complexes and DFT methods. DFT methods were also used to calculate ligand hyperfine coupling constants in transition metal systems. The variation of the proton hyperfine coupling constant with water ligand orientation was investigated for [VO(H2O)5]2+ and the results were used to interpret high resolution EPR data of VO2+-exchanged zeolites. Nitrogen hyperfine and quadrupole coupling constants for VO2+ model complexes were calculated and compared with experimental data. The computational results were used to enhance the interpretation of the EPR data for vanadium-exchanged zeolites which are promising catalytic materials. The implications of the DFT calculations of EPR parameters with respect to catalysis will be discussed

Saladino, Alexander C.; Larsen, Sarah C.

2005-07-15T23:59:59.000Z

244

Evidence that the Yeast Desaturase Ole1p Exists as a Dimer In Vivo  

SciTech Connect

Desaturase enzymes are composed of two classes, the structurally well characterized soluble class found predominantly in the plastids of higher plants and the more widely distributed but poorly structurally defined integral membrane class. Despite their distinct evolutionary origins, the two classes both require an iron cofactor and molecular oxygen for activity and are inhibited by azide and cyanide, suggesting strong mechanistic similarities. The fact that the soluble desaturase is active as a homodimer prompted us test the hypothesis that an archetypal integral membrane desaturase from Saccharomyces cerevisiae, the {Delta}{sup o}-acyl-Co-A desaturase Ole1p, also exhibits a dimeric organization. Ole1p was chosen because it is one of the best characterized integral membrane desaturase and because it retains activity when fused with epitope tags. FLAG-Ole1p was detected by Western blotting of immunoprecipitates in which anti-Myc antibodies were used for capture from yeast extracts co-expressing Ole1p-Myc and Ole1p-FLAG. Interaction was confirmed by two independent bimolecular complementation assays (i.e. the split ubiquitin system and the split luciferase system). Co-expression of active and inactive Ole1p subunits resulted in an {approx}75% suppression of the accumulation of palmitoleic acid, demonstrating that the physiologically active form of Ole1p in vivo is the dimer in which both protomers must be functional.

Lou, Y.; Shanklin, J.

2010-06-18T23:59:59.000Z

245

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

SciTech Connect

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.

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

2013-01-01T23:59:59.000Z

246

Magnons and continua in a magnetized and dimerized spin-1/2 chain  

SciTech Connect

We examine the magnetic field dependent excitations of the dimerized spin-1/2 chain, copper nitrate, with antiferromagnetic intra-dimer exchange $J_1=0.44$ meV and exchange alternation $\\alpha=J_2/J_1=0.24$. Magnetic excitations in three distinct regimes of magnetization are probed through inelastic neutron scattering at low temperatures. At low and high fields there are three and two long-lived magnon-like modes, respectively. The number of modes and the anti-phase relationship between the wave-vector dependent energy and intensity of magnon scattering reflect the distinct ground states: A singlet ground state at low fields $\\mu_0H < \\mu_0H_{c1} = 2.8$~T and an $S_z=1/2$ product state at high fields $\\mu_0H > \\mu_0H_{c2} = 4.2$~T. In the intermediate field regime, a continuum of scattering for $\\hbar\\omega\\approx J_1$ is indicative of a strongly correlated gapless quantum state without coherent magnons.

Stone, Matthew B [ORNL; Chen, Y. [National Institute of Standards and Technology (NIST); Broholm, C. [Johns Hopkins University; Reich, D. H. [Johns Hopkins University; Xu, Guangyong [Brookhaven National Laboratory (BNL); Copley, John R. D. [National Institute of Standards and Technology (NIST), Gaithersburg, MD; Cook, Jeremy [National Institute of Standards and Technology (NIST)

2014-01-01T23:59:59.000Z

247

Relativistic calculations of $C_6$ and $C_8$ coefficients for strontium dimers  

E-Print Network (OSTI)

The electric dipole and quadrupole polarizabilities of the $5s5p~^3\\!P_1^o$ state and the $C_6$ and $C_8$ coefficients for the $^1\\!S_0 +\\, ^1\\!S_0$ and $^1\\!S_0 +\\, ^3\\!P_1^o$ dimers of strontium are calculated using a high-precision relativistic approach that combines configuration interaction and linearized coupled-cluster methods. Our recommended values of the long range dispersion coefficients for the $0_u$ and $1_u$ energy levels are $C_6(0_u)=3771(32)$ a.u. and $C_6(1_u)= 4001(33)$ a.u., respectively. They are in good agreement with recent results from experimental photoassociation data. We also calculate $C_8$ coefficients for Sr dimers, which are needed for precise determination of long-range interaction potential. We confirm the experimental value for the magic wavelength, where the Stark shift on the $^1\\!S_0$-$^3\\!P_1^o$ transition vanishes. The accuracy of calculations is analyzed and uncertainties are assigned to all quantities reported in this work.

S. G. Porsev; M. S. Safronova; Charles W. Clark

2014-09-21T23:59:59.000Z

248

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

DOE Patents (OSTI)

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.

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

1984-05-08T23:59:59.000Z

249

On the Inner Structure and Topology of Clusters in Two-Component Lipid Bilayers. Comparison of Monomer and Dimer Ising Models  

Science Journals Connector (OSTI)

Comparison of Monomer and Dimer Ising Models ... Clusters of two-component phospholipid bilayers have been simulated by two Ising-type lattice models: the monomer and the dimer model. ... The first theoretical model of a collective system, the model of ferromagnets, was developed by Ernst Ising(17) in 1925. ...

Istvn P. Sugr

2008-08-26T23:59:59.000Z

250

Vibrations, Tunneling, and Transition Dipole Moments in the Water Dimer Michael J. Smit, Gerrit C. Groenenboom, Paul E. S. Wormer, and Ad van der Avoird*  

E-Print Network (OSTI)

shows that only the states of E( symmetry of the water dimer have a permanent dipole moment. A model dipole moment of the E( states. 1. Introduction Liquid water is the most important biological substanceVibrations, Tunneling, and Transition Dipole Moments in the Water Dimer Michael J. Smit, Gerrit C

251

Terahertz Vibration?Rotation?Tunneling Spectroscopy of the Ammonia Dimer. II. A?E States of an Out-of-Plane Vibration and an In-Plane Vibration  

Science Journals Connector (OSTI)

Terahertz Vibration?Rotation?Tunneling Spectroscopy of the Ammonia Dimer. ... In order to proceed toward the ultimate goal of determining an accurate intermolecular potential surface like what has been done for the water dimer, it is necessary to thoroughly characterize the intermolecular vibrations. ... The ab initio harmonic vibrational frequencies are known to be often too high for the weakly bound systems. ...

Wei Lin; Jia-xiang Han; Lynelle K. Takahashi; Jennifer G. Loeser; Richard J. Saykally

2007-09-07T23:59:59.000Z

252

Hydrogenation of Carbon Dioxide Catalyzed by Ruthenium Trimethylphosphine Complexes: A Mechanistic Investigation using High-Pressure NMR Spectroscopy  

SciTech Connect

The previously reported complex, cis-(PMe3)4RuCl(OAc) (1) acts as a catalyst for CO2 hydrogenation into formic acid in the presence of a base and an alcohol co-catalyst. NMR spectroscopy has revealed that 1 exists in solution in equilibrium with fac-(PMe3)3RuCl(h2-OAc) (2), [(PMe3)4Ru(h2-OAc)]Cl (3a), and free PMe3. Complex 2 has been isolated and characterized by elemental analysis, NMR spectroscopy, and X-ray crystallography. 2 has been tested as a CO2 hydrogenation catalyst, however, it performed poorly under the conditions of catalysis used for 1. Complex 3a can be prepared by adding certain alcohols, such as MeOH, EtOH, or o-C6H5OH, to a solution of 1 in CDCl3. The chloride ion of 3a has been exchanged for the non-coordinating anions BPh4 or B(ArF )4 (B(ArF)4 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) to produce [(PMe3)4Ru(h2-OAc)]BPh4 (3b) and [(PMe3)4Ru(h2-OAc)]B(ArF)4 (3c). Both of these complexes have been isolated and characterized by elemental analysis, NMR spectroscopy, and in the case of 3b, X-ray crystallography. Complexes 3b and 3c perform just as well as 1 for CO2 hydrogenation to formic acid in the presence of an alcohol co-catalyst; however, 3b,c perform equally well without the added alcohol. High-pressure NMR has been used to investigate the mechanism of CO2 hydrogenation via 3a,b in the presence of base. Two of the intermediates involved have been identified as cis-(PMe3)4RuH2 (5) and cis-(PMe3)4Ru(H)O2CH (6), and the role of the base includes not only trapping of the formic acid product, but also initiation of the catalysis by aiding the conversion of 3b,c to 5.

Getty, April D.; Tai, Chih-Cheng; Linehan, John C.; Jessop, Philip G.; Olmstead, Marilyn M.; Rheingold, Arnold

2009-08-26T23:59:59.000Z

253

Opportunities for Catalysis in The 21st Century. A report from the Basic Energy Sciences Advisory Committee  

SciTech Connect

Chemical catalysis affects our lives in myriad ways. Catalysis provides a means of changing the rates at which chemical bonds are formed and broken and of controlling the yields of chemical reactions to increase the amounts of desirable products from these reactions and reduce the amounts of undesirable ones. Thus, it lies at the heart of our quality of life: The reduced emissions of modern cars, the abundance of fresh food at our stores, and the new pharmaceuticals that improve our health are made possible by chemical reactions controlled by catalysts. Catalysis is also essential to a healthy economy: The petroleum, chemical, and pharmaceutical industries, contributors of $500 billion to the gross national product of the United States, rely on catalysts to produce everything from fuels to ''wonder drugs'' to paints to cosmetics. Today, our Nation faces a variety of challenges in creating alternative fuels, reducing harmful by-products in manufacturing, cleaning up the environment and preventing future pollution, dealing with the causes of global warming, protecting citizens from the release of toxic substances and infectious agents, and creating safe pharmaceuticals. Catalysts are needed to meet these challenges, but their complexity and diversity demand a revolution in the way catalysts are designed and used. This revolution can become reality through the application of new methods for synthesizing and characterizing molecular and material systems. Opportunities to understand and predict how catalysts work at the atomic scale and the nanoscale are now appearing, made possible by breakthroughs in the last decade in computation, measurement techniques, and imaging and by new developments in catalyst design, synthesis, and evaluation.

White, J. M.; Bercaw, J.

2002-05-16T23:59:59.000Z

254

Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study  

SciTech Connect

This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

Boszormenyi, I.

1991-05-01T23:59:59.000Z

255

Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study  

SciTech Connect

This (<100 {Angstrom}) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 {times} r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm{sup 2} catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on ``Pt-on-alumina`` and on ``alumina-on-Pt`` are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

Boszormenyi, I.

1991-05-01T23:59:59.000Z

256

Mutations That Hamper Dimerization of Foot-and-Mouth Disease Virus 3A Protein Are Detrimental for Infectivity  

Science Journals Connector (OSTI)

...non-structural proteins of foot-and-mouth disease virus...Donaldson. 2001. Outbreak of foot-and-mouth disease virus...and JM Matthews. 2004. The power of two: protein dimerization...cells: a comparative study with foot-and-mouth disease virus...

Mnica Gonzlez-Magaldi; Ral Postigo; Beatriz G. de la Torre; Yuri A. Vieira; Miguel Rodrguez-Pulido; Eduardo Lpez-Vias; Paulino Gmez-Puertas; David Andreu; Leonor Kremer; Mara F. Rosas; Francisco Sobrino

2012-07-11T23:59:59.000Z

257

A Two-site Kinetic Mechanism for ATP Binding and Hydrolysis by E. coli Rep Helicase Dimer Bound to a  

E-Print Network (OSTI)

A Two-site Kinetic Mechanism for ATP Binding and Hydrolysis by E. coli Rep Helicase Dimer Bound that are coupled to ATP binding and hydrolysis. We have investi- gated the kinetic mechanism of ATP binding 17(?2) s?1 ; KM 3 mM), pre-steady-state studies provide evidence for a two-ATP site mechanism

Lohman, Timothy M.

258

Copyright 01990 by the Genetics Society of America Synapsis-MediatedFusion of Free DNA Ends Forms Inverted Dimer  

E-Print Network (OSTI)

Inverted Dimer Plasmids in Yeast Sam Kunes, David Botstein' and Maurice S. Fox Department of Biology plasmid DNA and the endsof the plasmid do not share homology with the yeast genome, circular inverted of genetically marked plasmids, we show that two plasmid molecules are required to form an inverted dimerplasmid

Botstein, David

259

Mapping of the SecA Signal Peptide Binding Site and Dimeric Interface by Using the Substituted Cysteine Accessibility Method  

Science Journals Connector (OSTI)

...binding induces changes in the oligomeric state and conformation of Sec A in a lipid environment: a small-angle neutron-scattering study. J. Mol. Biol. 332 :23-30. 13. Or E , A Navon, and T Rapoport. 2002. Dissociation of the dimeric...

Meera K. Bhanu; Ping Zhao; Debra A. Kendall

2013-08-09T23:59:59.000Z

260

Quantum dimer model for the spin-12 kagome Z2 spin liquid  

Science Journals Connector (OSTI)

We revisit the description of the low-energy singlet sector of the spin-12 Heisenberg antiferromagnet on kagome in terms of an effective quantum dimer model. With the help of exact diagonalizations of appropriate finite-size clusters, we show that the embedding of a given process in its kagome environment leads to dramatic modifications of the amplitudes of the elementary loop processes, an effect not accessible to the standard approach based on the truncation of the Hamiltonian to the nearest-neighbor valence-bond basis. The resulting parameters are consistent with a Z2 spin liquid rather than with a valence-bond crystal, in agreement with the last density matrix renormalization group results.

Ioannis Rousochatzakis; Yuan Wan; Oleg Tchernyshyov; Frdric Mila

2014-09-15T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Synthesis of a high molecular weight thyroglobulin dimer by two ovine thyroid cell lines: the OVNIS  

Science Journals Connector (OSTI)

The OVNIS 6H and 5H thyroid cells, 2 permanent cell lines isolated 3 years ago from ovine tissue, synthesize a high molecular weight glycosylated protein, immunologically related to ovine thyroglobulin, which is similar to the prothyroid hormone dimer (1719) S: thyroglobulin. Using sucrose gradient centrifugation and cell labelling with [14C]Leu or [3H]G1NH2, radioactivity was observed in proteins purified from cell layers and from cell culture media. Addition of thyrotropin to or removal from the media resulted respectively in an increase (+773%) or decrease (?1090%) of the total radioactivity detected in the (1719)S thyroglobulin fraction. Estimation of thyroglobulin by RIA gave similar though less pronounced effects. These experiments prove (1) that thyroglobulin is still expressed in these OVNIS thyroid cell lines even after 3 years of permanent culture, (2) that TSH modulates the level of this protein through a TSH-receptor functional system.

S. Hovspian; A. Aouani; G. Fayet

1986-01-01T23:59:59.000Z

262

Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet  

SciTech Connect

We present inelastic neutron scattering and thermodynamic measurements characterizing the magnetic excitations in a disordered non-magnetic substituted spin-liquid antiferromagnet. The parent compound Ba3Mn2O8 is a dimerized, quasi-two-dimensional geometrically frustrated quantum disordered antiferromagnet. We substitute this compound with non-magnetic vanadium for the S = 1 manganese atoms, Ba3(Mn1-xVx)2O8, and find that the singlet-triplet excitations which dominate the spectrum of the parent compound persist for the full range of substitution examined, x = 0.02 to 0.3. We also observe additional low-energy magnetic fluctuations which are enhanced at the greatest substitution values. These excitations may be a precursor to a low-temperature random singlet phase which may exist in Ba3(Mn1-xVx)2O8.

Stone, Matthew B [ORNL; Podlesnyak, Andrey A [ORNL; Ehlers, Georg [ORNL; Huq, Ashfia [ORNL; Samulon, Eric C [Stanford University; Shapiro, Max C [Stanford University; Fisher, Ian R [Stanford University

2011-01-01T23:59:59.000Z

263

An Auxiliary-Field Quantum Monte Carlo Study of the Chromium Dimer  

E-Print Network (OSTI)

The chromium dimer (Cr2) presents an outstanding challenge for many-body electronic structure methods. Its complicated nature of binding, with a formal sextuple bond and an unusual potential energy curve, is emblematic of the competing tendencies and delicate balance found in many strongly correlated materials. We present a near-exact calculation of the potential energy curve (PEC) and ground state properties of Cr2, using the auxiliary-field quantum Monte Carlo (AFQMC) method. Unconstrained, exact AFQMC calculations are first carried out for a medium-sized but realistic basis set. Elimination of the remaining finite-basis errors and extrapolation to the complete basis set (CBS) limit is then achieved with a combination of phaseless and exact AFQMC calculations. Final results for the PEC and spectroscopic constants are in excellent agreement with experiment.

Purwanto, Wirawan; Krakauer, Henry

2014-01-01T23:59:59.000Z

264

Human Immunodeficiency Virus Type 1 Gag Polyprotein Multimerization Requires the Nucleocapsid Domain and RNA and Is Promoted by the Capsid-Dimer Interface and the Basic Region of Matrix Protein  

Science Journals Connector (OSTI)

...Analysis of the three-dimensional structure of a protein fragment...identified a hydrophobic dimer interface (). In the context of an...wild-type provirus, the dimer interface mutants are associated with...the affinity of the dimer interface is not very high (), and...

Mark T. Burniston; Andrea Cimarelli; John Colgan; Sean P. Curtis; Jeremy Luban

1999-10-01T23:59:59.000Z

265

Dimer Structure of an Interfacially Impaired Phosphatidylinositol-Specific Pholpholipase C  

SciTech Connect

The crystal structure of the W47A/W242A mutant of phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis has been solved to 1.8{angstrom} resolution. The W47A/W242A mutant is an interfacially challenged enzyme, and it has been proposed that one or both tryptophan side chains serve as membrane interfacial anchors (Feng, J., Wehbi, H., and Roberts, M. F. (2002) J. Biol. Chem. 277, 19867-19875). The crystal structure supports this hypothesis. Relative to the crystal structure of the closely related (97% identity) wild-type PI-PLC from Bacillus cereus, significant conformational differences occur at the membrane-binding interfacial region rather than the active site. The Trp {yields} Ala mutations not only remove the membrane-partitioning aromatic side chains but also perturb the conformations of the so-called helix B and rim loop regions, both of which are implicated in interfacial binding. The crystal structure also reveals a homodimer, the first such observation for a bacterial PI-PLC, with pseudo-2-fold symmetry. The symmetric dimer interface is stabilized by hydrophobic and hydrogen-bonding interactions, contributed primarily by a central swath of aromatic residues arranged in a quasiherringbone pattern. Evidence that interfacially active wild-type PI-PLC enzymes may dimerize in the presence of phosphatidylcholine vesicles is provided by fluorescence quenching of PI-PLC mutants with pyrene-labeled cysteine residues. The combined data suggest that wild-type PI-PLC can form similar homodimers, anchored to the interface by the tryptophan and neighboring membrane-partitioning residues.

Shao,C.; Shi, X.; Wehbi, H.; Zambonelli, C.; Head, J.; Seaton, B.; Roberts, M,.

2007-01-01T23:59:59.000Z

266

Diffusion of the Cu monomer and dimer on Ag(111): Molecular dynamics simulations and density functional theory calculations  

Science Journals Connector (OSTI)

We present results of molecular dynamics (MD) simulations and density functional theory (DFT) calculations of the diffusion of Cu adatom and dimer on Ag(111). We have used potentials generated by the embedded-atom method for the MD simulations and pseudopotentials derived from the projected-augmented-wave method for the DFT calculations. The MD simulations (at three different temperatures: 300, 500, and 700 K) show that the diffusivity has an Arrhenius behavior. The effective energy barriers obtained from the Arrhenius plots are in excellent agreement with those extracted from scanning tunneling microscopy experiments. While the diffusion barrier for Cu monomers on Ag(111) is higher than that reported (both in experiment and theory) for Cu(111), the reverse holds for dimers [which, for Cu(111), has so far only been theoretically assessed]. In comparing our MD result with those for Cu islets on Cu(111), we conclude that the higher barriers for Cu monomers on Ag(111) results from the comparatively large Ag-Ag bond length, whereas for Cu dimers on Ag(111) the diffusivity is taken over and boosted by the competition in optimization of the Cu-Cu dimer bond and the five nearest-neighbor Cu-Ag bonds. Our DFT calculations confirm the relatively large barriers for the Cu monomer on Ag(111)69 and 75 meVcompared to those on Cu(111) and hint a rationale for them. In the case of the Cu dimer, the relatively long Ag-Ag bond length makes available a diffusion route whose highest relevant energy barrier is only 72 meV and which is not favorable on Cu(111). This process, together with another involving an energy barrier of 83 meV, establishes the possibility of low-barrier intercell diffusion by purely zigzag mechanisms.

Sardar Sikandar Hayat; Marisol Alcntara Ortigoza; Muhammad A. Choudhry; Talat S. Rahman

2010-08-03T23:59:59.000Z

267

Interatomic Coulombic Decay as a New Source of Low Energy Electrons in slow Ion-Dimer Collisions  

E-Print Network (OSTI)

We provide the experimental evidence that the single electron capture process in slow collisions between O$^{3+}$ ions and neon dimer targets leads to an unexpected production of low-energy electrons. This production results from the interatomic Coulombic decay process, subsequent to inner shell single electron capture from one site of the neon dimer. Although pure one-electron capture from inner shell is expected to be negligible in the low collision energy regime investigated here, the electron production due to this process overtakes by one order of magnitude the emission of Auger electrons by the scattered projectiles after double-electron capture. This feature is specific to low charge states of the projectile: similar studies with Xe$^{20+}$ and Ar$^{9+}$ projectiles show no evidence of inner shell single-electron capture. The dependence of the process on the projectile charge state is interpreted using simple calculations based on the classical over the barrier model.

Iskandar, W; Leredde, A; Flechard, X; Gervais, B; Guillous, S; Hennecart, D; Mery, A; Rangama, J; Zhou, C L; Shiromaru, H; Cassimi, A

2014-01-01T23:59:59.000Z

268

Assembly of the Alu domain of the signal recognition particle (SRP): dimerization of the two protein components is required for efficient binding to SRP RNA.  

Science Journals Connector (OSTI)

...domain of the signal recognition particle (SRP): dimerization of the two protein components is required for efficient binding to SRP RNA. K Strub P Walter Department of Biochemistry...94143-0448. The signal recognition particle (SRP), a cytoplasmic ribonucleoprotein, plays...

K Strub; P Walter

1990-02-01T23:59:59.000Z

269

Water addition for increased CO/H[sub 2] hydrocarbon synthesis activity over catalysts comprising cobalt, ruthenium and mixtures thereof which may include a promoter metal  

SciTech Connect

A once-through, fixed or slurry bed Fischer Tropsch process is described with enhanced CO conversion activity and C[sub 5] + liquid hydrocarbon selectivity comprising contacting a feed mixture of carbon monoxide and hydrogen in a reaction zone with about 1 Vol % to about 70 Vol % water based on the total volume of feed mixture, at a pressure above one atmosphere and a temperature ranging from about 150 C to about 300 C, with a catalyst selected from the group consisting of cobalt, ruthenium, and mixtures thereof on a titania support, wherein said titania support is less than 40 m[sup 2]/g, converting at least 90 Vol % of the carbon monoxide to liquid hydrocarbons, and in the substantial absence of CO[sub 2] formation.

Kim, C.J.

1993-07-13T23:59:59.000Z

270

Enzymatic synthesis of 3',4'-anhydrovinblastine: a precursor of the clinically important dimeric alkaloids of Catharanthus roseus  

E-Print Network (OSTI)

much work to be done to understand the enzymology and regulation involved from the earliest parts of the pathway to the synthesis of the dimers (McCaskill 1988). Only one of the enzymes which catalyze an early step in the pathway has been purified... to homogeneity. The rest of the enzymes have only been partially purified or remain undiscovered. The most characterized and highly purified enzyme is strictosidine synthase. This enzyme which catalyzes the condensation of tryptamine with secologanin to form...

Rinehart, Cara Louise

1989-01-01T23:59:59.000Z

271

Exact multipoint and multitime correlation functions of a one-dimensional model of adsorption and evaporation of dimers  

Science Journals Connector (OSTI)

In this work, we provide a method that allows us to compute exactly the multipoint and multitime correlation functions of a one-dimensional stochastic model of dimer adsorption evaporation with random (uncorrelated) initial states. In particular, explicit expressions of the two-point noninstantaneous/instantaneous correlation functions are obtained. The long-time behavior of these expressions is discussed in detail and in various physical regimes.

Mauro Mobilia

2002-04-04T23:59:59.000Z

272

Modulation of Bacillus thuringiensis Phosphatidylinositol-Specific Phospholipase C Activity by Mutations in the Putative Dimerization Interface  

SciTech Connect

Cleavage of phosphatidylinositol (PI) to inositol 1,2-(cyclic)-phosphate (cIP) and cIP hydrolysis to inositol 1-phosphate by Bacillus thuringiensis phosphatidylinositol-specific phospholipase C are activated by the enzyme binding to phosphatidylcholine (PC) surfaces. Part of this reflects improved binding of the protein to interfaces. However, crystallographic analysis of an interfacially impaired phosphatidylinositol-specific phospholipase (W47A/W242A) suggested protein dimerization might occur on the membrane. In the W47A/W242A dimer, four tyrosine residues from one monomer interact with the same tyrosine cluster of the other, forming a tight dimer interface close to the membrane binding regions. We have constructed mutant proteins in which two or more of these tyrosine residues have been replaced with serine. Phospholipid binding and enzymatic activity of these mutants have been examined to assess the importance of these residues to enzyme function. Replacing two tyrosines had small effects on enzyme activity. However, removal of three or four tyrosine residues weakened PC binding and reduced PI cleavage by the enzyme as well as PC activation of cIP hydrolysis. Crystal structures of Y247S/Y251S in the absence and presence of myo-inositol as well as Y246S/Y247S/Y248S/Y251S indicate that both mutant proteins crystallized as monomers, were very similar to one another, and had no change in the active site region. Kinetic assays, lipid binding, and structural results indicate that either (i) a specific PC binding site, critical for vesicle activities and cIP activation, has been impaired, or (ii) the reduced dimerization potential for Y246S/Y247S/Y248S and Y246S/Y247S/Y248S/Y251S is responsible for their reduced catalytic activity in all assay systems.

Shi, X.; Shao, C; Zhang, X; Zambonelli, C; Redfield, A; Head, J; Seaton, B; Roberts, M

2009-01-01T23:59:59.000Z

273

Universality of weakly bound dimers and Efimov trimers close to Li-Cs Feshbach resonances  

E-Print Network (OSTI)

We study the interspecies scattering properties of ultracold Li-Cs mixtures in their two energetically lowest spin channels in the magnetic field range between 800 G and 1000 G. Close to two broad Feshbach resonances we create weakly bound LiCs dimers by radio-frequency association and measure the dependence of the binding energy on the external magnetic field strength. Based on the binding energies and complementary atom loss spectroscopy of three other Li-Cs s-wave Feshbach resonances we construct precise molecular singlet and triplet electronic ground state potentials using a coupled-channels calculation. We extract the Li-Cs interspecies scattering length as a function of the external field and obtain almost a ten-fold improvement in the precision of the values for the pole positions and widths of the s-wave Li-Cs Feshbach resonances as compared to our previous work [Pires \\textit{et al.}, Phys. Rev. Lett. \\textbf{112}, 250404 (2014)]. We discuss implications on the Efimov scenario and the universal geome...

Ulmanis, J; Pires, R; Kuhnle, E D; Weidemller, M; Tiemann, E

2015-01-01T23:59:59.000Z

274

An unusual dimeric structure and assembly for TLR4 regulator RP105?MD-1  

SciTech Connect

RP105-MD-1 modulates the TLR4-MD-2-mediated, innate immune response against bacterial lipopolysaccharide (LPS). The crystal structure of the bovine 1:1 RP105-MD-1 complex bound to a putative endogenous lipid at 2.9 {angstrom} resolution shares a similar overall architecture to its homolog TLR4-MD-2 but assembles into an unusual 2:2 homodimer that differs from any other known TLR-ligand assembly. The homodimer is assembled in a head-to-head orientation that juxtaposes the N-terminal leucine-rich repeats (LRRs) of the two RP105 chains, rather than the usual tail-to-tail configuration of C-terminal LRRs in ligand-activated TLR dimers, such as TLR1-TRL2, TLR2-TLR6, TLR3-TLR3 and TLR4-TLR4. Another unusual interaction is mediated by an RP105-specific asparagine-linked glycan, which wedges MD-1 into the co-receptor binding concavity on RP105. This unique mode of assembly represents a new paradigm for TLR complexes and suggests a molecular mechanism for regulating LPS responses.

Yoon, Sung-il; Hong, Minsun; Wilson, Ian A (Scripps)

2011-11-16T23:59:59.000Z

275

Application of a modified generalized Flory dimer theory to normal alkanes  

SciTech Connect

The applicability of chain equations of state to real systems is discussed in this paper. For this purpose, the authors have compared four theories: the perturbed-hard-chain theory (PHCT) of Prausnitz and coworkers, the generalized Flory (GF) and generalized Flory dimer (GFD) theories of Hall and coworkers, and the statistical associating fluid theory (SAFT) of Radosz, Gubbins, and co-workers. In this comparison, the perturbation expansion in the attractive term was truncated after the first-order term for all theories. Comparison of these theories with Monte Carlo simulation data for hard chains and square-well chains showed that the GFD theory, which explicitly takes into account the effect of the formation of chains in both the repulsive and the attractive part of the equations, is in best agreement with the data. The GFD theory was further improved by using the simulations data directly to reevaluate the shape parameters c and q, which were found to be density dependent. The new simplified GFD theory gives a significantly better correlation of the properties of normal alkanes than the other four theories.

Bokis, C.P.; Donohue, M.D. (Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemical Engineering); Hall, C.K. (North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemical Engineering)

1994-05-01T23:59:59.000Z

276

New Family of Tiny Crystals Glow Bright in LED Lights | Advanced Photon  

NLE Websites -- All DOE Office Websites (Extended Search)

How Serotonin Receptors Can Shape Drug Effects, from LSD to Migraine How Serotonin Receptors Can Shape Drug Effects, from LSD to Migraine Medication 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 Nano-imaging Breakthrough Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed New Family of Tiny Crystals Glow Bright in LED Lights JUNE 7, 2013 Bookmark and Share Laue microdiffraction pattern acquired from a nanoribbon in experiments at the APS. Minuscule crystals that glow different colors may be the missing ingredient for white light-emitting diode (LED) lighting that illuminates homes and

277

Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions  

NLE Websites -- All DOE Office Websites (Extended Search)

Molecular-scale, Three-dimensional Non-Platinum Group Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions John B. Kerr Lawrence Berkeley National Laboratory (LBNL) September 30, 2009 Team Members: Adam Weber, Rachel Segalman, Robert Kostecki, Jeff Reimer, John Arnold, Martin Head-Gordon (LBNL). Piotr Zelenay, James Boncella, Yu Seung Kim, Neil Henson, Jerzy Chlistunoff (LANL). Steve Hamrock, Radoslav Atanasoski (3M) Budget: DOE share - $9.58MM over four years; 3M share - in-kind over four years. 2 Objectives 1) Demonstrate that non-platinum group metal catalysts can be used for oxygen reduction in polymer-coated electrode structures based on polyelectrolyte membranes. 2) Incorporate catalysts into polymer binders of composite electrodes for the construction of MEAs to demonstrate that this

278

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

SciTech Connect

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.

Behrens, Malte

2012-03-28T23:59:59.000Z

279

Boron-nitrogen-hydrogen (BNH) compounds: recent developments in hydrogen storage, applications in hydrogenation and catalysis, and new syntheses  

SciTech Connect

The strong efforts devoted to the exploration of BNH compounds for hydrogen storage have led to impressive advances in the field of boron chemistry. This review summarizes progress in this field from three aspects. It starts with the most recent developments in using BNH compounds for hydrogen storage, covering NH3BH3, B3H8 containing compounds, and CBN compounds. The following section then highlights interesting applications of BNH compounds in hydrogenation and catalysis. The last part is focused on breakthroughs in the syntheses and discovery of new BNH organic analogues. The role of N?H?+H?-?B dihydrogen interactions in molecule packing, thermal hydrogen evolution, and syntheses is also discussed within the review. Part of this research is supported by the U.S. Department of Energys Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. Pacific Northwest National Laboratory is operated by Battelle.

Huang, Zhenguo; Autrey, Thomas

2012-11-15T23:59:59.000Z

280

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

SciTech Connect

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.

Cutler, Alan R.

2001-04-14T23:59:59.000Z

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281

Enantioselectivities in electron-transfer and excited state quenching reactions of a chiral ruthenium complex possessing a helical structure  

SciTech Connect

The outer-sphere electron-transfer reactions between diastereomers of Ru(menbyp){sub 3}{sup {sm_bullet}+} (menbpy = 4,4{prime}-di{l_brace}(1R,2S,5R)-({minus})-menthoxycarbonyl{r_brace}-2,2{prime}-bipyridine) and enantiomers of Co(acac){sub 3} and Co(edta){sup {minus}} have been studied by pulse radiolysis. {Delta}-Ru(menbpy){sub 3}{sup {sm_bullet}+} rapidly reduces Co(acac){sub 3} in 85% EtOH/H{sub 2}O (1 mM NaH{sub 2}PO{sub 4}) with second-order rate constants of (2.1 {+-} 0.1) {times} 10{sup 7} and (7.8 {+-} 0.2) {times} 10{sup 6}/M s for the {Delta}- and {Gamma}-Co(acac){sub 3} enantiomers, respectively, and an enantioselectivity factor (EF) of 2.7. {Gamma}-Ru(menbyp){sub 3}{sup {sm_bullet}+} preferentially reduces {Gamma}-Co(acac){sub 3} with an enantioselectivity factor (EF) of 0.8. Activation volume data ({Delta}V{sup {double_dagger}}) suggest that the association between the {Delta}{single_bond}{Delta} isomers in the encounter complex allows closer interaction of the metal centers than between the other isomer combinations. The value of (EF) for the reaction of {Delta}- and {Gamma}-co(edta){sup {minus}} with {Delta}-Ru(menbpy){sub 3}{sup {sm_bullet}+} is 1.2. Electron-transfer reactions of seven racemic Ru(L){sub 3}{sup {sm_bullet}+} (L = substituted phenanthroline) complexes with Co(acac){sub 3} were also studied and gave rate constants of {approx}1.5 {times} 10{sup 9}/M s. The quenching of photoexcited {sup *}Ru(menbpy){sub 3}{sup 2+} by Co(acac){sub 3} and Co(edta){sup {minus}} exhibits small stereoselectivity: For Co(acac){sub 3} in 95 and 85% EtOH/H{sub 2}O the enantioselectivity factor is 1.2 and 1.1, respectively, barely outside the experimental error. For all other cases the selectivity was unity within the experimental error of the measurement. The quenching rate constants were {approx}1 {times} 10{sup 8} and 1.1 {times} 10{sup 9}/M s for Co(acac){sub 3} and Co(edta){sup {minus}}, respectively. Quenching reactions of seven racemic ruthenium(II) phenanthroline complexes with Co(acac){sub 3} were also studied and found to be faster than those of Ru(menbpy){sub 3}{sup 2+} by only a factor of {approx}3 despite an increase in the driving force of {approx}0.5 eV for electron-transfer quenching. The quenching of {sup *}Ru(menbpy){sub 3}{sup 2+} by Co(acac){sub 3} is dominated by an energy-transfer mechanism. This conclusion is supported by the magnitude of the quenching rate constants compared with the rate constants for reduction by Ru(menbpy){sub 3}{sup {sm_bullet}+}, the effect of driving-force changes on the quenching rate constant, the low quantum yield of Co(II) products observed in the CW photolysis, and the lack of long-lived products observed in the flash photolysis experiments. The factors responsible for the selectivity exhibited in the CW photolysis studies of Ru(menbpy){sub 3}{sup 2+} with Co(acac){sub 3} are discussed.

Hamada, Taisuke; Eifuku, Kenji; Sakaki, Shigeyoshi [Kumamoto Univ., Kurokami (Japan). Dept. of Applied Chemistry and Biochemistry] [Kumamoto Univ., Kurokami (Japan). Dept. of Applied Chemistry and Biochemistry; Brunschwig, B.S.; Fujita, E.; Wishart, J.F. [Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.] [Brookhaven National Lab., Upton, NY (United States). Chemistry Dept.; Koerner, M.; Eldik, R. van [Univ. of Erlangen-Nuernberg (Germany). Inst. for Inorganic Chemistry] [Univ. of Erlangen-Nuernberg (Germany). Inst. for Inorganic Chemistry

1999-07-22T23:59:59.000Z

282

Procyanidin dimer B2-mediated IRAK-M induction negatively regulates TLR4 signaling in macrophages  

SciTech Connect

Highlights: Pro B2 elevated the expression of IRAK-M, a negative regulator of TLR signaling. LPS-induced expression of cell surface molecules was inhibited by Pro B2. LPS-induced production of pro-inflammatory cytokines was inhibited by Pro B2. Pro B2 inhibited LPS-induced activation of MAPKs and NF-?B through IRAK-M. Pro B2 inactivated nave T cells by inhibiting LPS-induced cytokines via IRAK-M. -- Abstract: Polyphenolic compounds have been found to possess a wide range of physiological activities that may contribute to their beneficial effects against inflammation-related diseases; however, the molecular mechanisms underlying this anti-inflammatory activity are not completely characterized, and many features remain to be elucidated. In this study, we investigated the molecular basis for the down-regulation of toll-like receptor 4 (TLR4) signal transduction by procyanidin dimer B2 (Pro B2) in macrophages. Pro B2 markedly elevated the expression of the interleukin (IL)-1 receptor-associated kinase (IRAK)-M protein, a negative regulator of TLR signaling. Lipopolysaccharide (LPS)-induced expression of cell surface molecules (CD80, CD86, and MHC class I/II) and production of pro-inflammatory cytokines (tumor necrosis factor-?, IL-1?, IL-6, and IL-12p70) were inhibited by Pro B2, and this action was prevented by IRAK-M silencing. In addition, Pro B2-treated macrophages inhibited LPS-induced activation of mitogen-activated protein kinases such as extracellular signal-regulated kinase 1/2, p38, and c-Jun N-terminal kinase and the translocation of nuclear factor ?B and p65 through IRAK-M. We also found that Pro B2-treated macrophages inactivated nave T cells by inhibiting LPS-induced interferon-? and IL-2 secretion through IRAK-M. These novel findings provide new insights into the understanding of negative regulatory mechanisms of the TLR4 signaling pathway and the immune-pharmacological role of Pro B2 in the immune response against the development and progression of many chronic diseases.

Sung, Nak-Yun [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)] [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Yang, Mi-So [Department of Microbiology, Infection Signaling Network Research Center, College of Medicine, Chungnam National University, Daejeon (Korea, Republic of)] [Department of Microbiology, Infection Signaling Network Research Center, College of Medicine, Chungnam National University, Daejeon (Korea, Republic of); Song, Du-Sub [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of) [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); School of life sciences and Biotechnology, Korea University 5-ka, Anam-Dong, Sungbuk-ku, Seoul 136-701 (Korea, Republic of); Kim, Jae-Kyung; Park, Jong-Heum; Song, Beom-Seok; Park, Sang-Hyun; Lee, Ju-Woon [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)] [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Park, Hyun-Jin [School of life sciences and Biotechnology, Korea University 5-ka, Anam-Dong, Sungbuk-ku, Seoul 136-701 (Korea, Republic of)] [School of life sciences and Biotechnology, Korea University 5-ka, Anam-Dong, Sungbuk-ku, Seoul 136-701 (Korea, Republic of); Kim, Jae-Hun [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)] [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Byun, Eui-Baek, E-mail: ebbyun80@kaeri.re.kr [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)] [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Byun, Eui-Hong, E-mail: ehbyun80@kongju.ac.k [Department of Food Science and Technology, Kongju National University, Yesan 340-800 (Korea, Republic of)] [Department of Food Science and Technology, Kongju National University, Yesan 340-800 (Korea, Republic of)

2013-08-16T23:59:59.000Z

283

Crystal Structure of (+)-[delta]-Cadinene Synthase from Gossypium arboreum and Evolutionary Divergence of Metal Binding Motifs for Catalysis  

SciTech Connect

(+)-{delta}-Cadinene synthase (DCS) from Gossypium arboreum (tree cotton) is a sesquiterpene cyclase that catalyzes the cyclization of farnesyl diphosphate in the first committed step of the biosynthesis of gossypol, a phytoalexin that defends the plant from bacterial and fungal pathogens. Here, we report the X-ray crystal structure of unliganded DCS at 2.4 {angstrom} resolution and the structure of its complex with three putative Mg{sup 2+} ions and the substrate analogue inhibitor 2-fluorofarnesyl diphosphate (2F-FPP) at 2.75 {angstrom} resolution. These structures illuminate unusual features that accommodate the trinuclear metal cluster required for substrate binding and catalysis. Like other terpenoid cyclases, DCS contains a characteristic aspartate-rich D{sup 307}DTYD{sup 311} motif on helix D that interacts with Mg{sub A}{sup 2+} and Mg{sub C}{sup 2+}. However, DCS appears to be unique among terpenoid cyclases in that it does not contain the 'NSE/DTE' motif on helix H that specifically chelates Mg{sub B}{sup 2+}, which is usually found as the signature sequence (N,D)D(L,I,V)X(S,T)XXXE (boldface indicates Mg{sub B}{sup 2+} ligands). Instead, DCS contains a second aspartate-rich motif, D{sup 451}DVAE{sup 455}, that interacts with Mg{sub B}{sup 2+}. In this regard, DCS is more similar to the isoprenoid chain elongation enzyme farnesyl diphosphate synthase, which also contains two aspartate-rich motifs, rather than the greater family of terpenoid cyclases. Nevertheless, the structure of the DCS-2F-FPP complex shows that the structure of the trinuclear magnesium cluster is generally similar to that of other terpenoid cyclases despite the alternative Mg{sub B}{sup 2+} binding motif. Analyses of DCS mutants with alanine substitutions in the D{sup 307}DTYD{sup 311} and D{sup 451}DVAE{sup 455} segments reveal the contributions of these segments to catalysis.

Gennadios, Heather A.; Gonzalez, Veronica; Di Costanzo, Luigi; Li, Amang; Yu, Fanglei; Miller, David J.; Allemann, Rudolf K.; Christianson, David W.; (UPENN); (Cardiff); (UC)

2009-09-11T23:59:59.000Z

284

Spin-gap opening accompanied by a strong magnetoelastic response in the S=1 magnetic dimer system Ba3BiRu2O9  

Science Journals Connector (OSTI)

Neutron diffraction, magnetization, resistivity, and heat-capacity measurements on the 6H-perovskite Ba3BiRu2O9 reveal simultaneous magnetic and structural dimerization driven by strong magnetoelastic coupling. An isostructural but strongly displacive first-order transition on cooling through T*=176 K is associated with a change in the nature of direct RuRu bonds within Ru2O9 face-sharing octahedra. Above T*, Ba3BiRu2O9 is an S=1 magnetic dimer system with intradimer exchange interactions J0/kB=320 K and interdimer exchange interactions J?/kB=?160 K. Below T*, a spin-gapped state emerges with ??220 K. Ab initio calculations confirm antiferromagnetic exchange within dimers, but the transition is not accompanied by long-range magnetic order.

Wojciech Miiller; Maxim Avdeev; Qingdi Zhou; Andrew J. Studer; Brendan J. Kennedy; Gordon J. Kearley; Chris D. Ling

2011-12-15T23:59:59.000Z

285

Protonation effect on the electronic properties of 2-pyridone monomer, dimer and its water clusters: A theoretical study  

SciTech Connect

The CC2 (second order approximate coupled cluster method) has been applied to investigate protonation effect on electronic transition energies of 2-pyridone (2PY), 2-pyridone dimer, and micro-solvated 2-pyridone (0-2 water molecules). The PE profiles of protonated 2-pyridone (2PYH{sup +}) as well as monohydrated 2PYH{sup +} at the different electronic states have been investigated. The {sup 1}??* state in protonated species (2PYH{sup +}) is a barrier free and dissociative state along the O-H stretching coordinate. In this reaction coordinate, the lowest lying {sup 1}??* predissociates the bound S{sub 1}({sup 1}??*) state, connecting the latter to a conical intersection with the S{sub 0} state. These conical intersections lead the {sup 1}??* state to proceed as predissociative state and finally direct the excited system to the ground state. Furthermore, in presence of water molecule, the {sup 1}??* state still remains dissociative but the conical intersection between {sup 1}??* and ground state disappears. In addition, according to the CC2 calculation results, it has been predicted that protonation significantly blue shifts the S{sub 1}-S{sub 0} electronic transition of monomer, dimer, and microhydrated 2-pyridone.

Saed, Behnaz [Department of Chemistry, University of Isfahan, 81746-73441 Isfahan (Iran, Islamic Republic of)] [Department of Chemistry, University of Isfahan, 81746-73441 Isfahan (Iran, Islamic Republic of); Omidyan, Reza, E-mail: r.omidyan@sci.ui.ac.ir, E-mail: reza.omidyan@u-psud.fr [Department of Chemistry, University of Isfahan, 81746-73441 Isfahan (Iran, Islamic Republic of) [Department of Chemistry, University of Isfahan, 81746-73441 Isfahan (Iran, Islamic Republic of); Centre Laser de lUniversit Paris Sud (LUMAT, FR, 2764), Bt. 106, Univ. Paris-Sud 11, 91405 Orsay Cedex (France)

2014-01-14T23:59:59.000Z

286

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

E-Print Network (OSTI)

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...

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

2014-01-01T23:59:59.000Z

287

Nuclear Factor-KB Dimer Exchange Promotes a p21waf1/cip1 Superinduction Response in Human T Leukemic Cells  

E-Print Network (OSTI)

Nuclear Factor-KB Dimer Exchange Promotes a p21waf1/cip1 Superinduction Response in Human ability to induce p21waf1/cip1 . Here, we provide evidence that sequential NF-KB-activating signals induce heightened NF-KB DNA binding and p21waf1/cip1 induction in CEM and additional T leukemic cell lines

Miyamoto, Shigeki

288

THE JOURNAL OF CHEMICAL PHYSICS VOLUME 58, NUMBER 2 15 JANUARY 1973 Internal state distribution of alkali dimers in supersonic nozzle beams*  

E-Print Network (OSTI)

of alkali dimers in supersonic nozzle beams* M. P. Sinha, A. Schultzt, and R. N. Zare Department o the white light and laser-induced fluorescence excited in a nozzle beam of Na2 molecules, we have measured beams with various stagnation pressures (50-240 torr) of alkali metal and with nozzles of different

Zare, Richard N.

289

Low-temperature emission spectra of 9-alkylanthracene esters: Dimer photodecomposition and monomer pair interactions in polymer hosts  

SciTech Connect

Effects due to variation in the alkyl chain length of photodimers of 9-alkylanthracene esters on their photodecomposition efficiencies at 12 K and, by implication, the photoproduct migration as a function of temperature within polymer hosts are investigated. It is shown that dimers with longer alkyl chains have a lower photodecomposition efficiency. The extent of photoproduct migration within the polymer following photodecomposition was also studied as a function of alkyl chain length. This migration and its modulation of the interaction between the separating monomers is shown to affect the emission spectrum. Thus, monomer migration was studied in temperature cycling experiments. It was also found, for the polymer hosts investigated - poly(methyl methacrylate), poly(vinyl chloride), and polystyrene - that these properties are host dependent. This result is probably due to the void space differences that exist among these polymers. 17 refs., 10 figs.

Salt, K.; Scott, G.W. (Univ. of California, Riverside, CA (United States))

1994-10-06T23:59:59.000Z

290

Preliminary Crystallography Confirms that the Archaeal DNA-binding and Tryptophan-sensing Regulator TrpY is a Dimer  

SciTech Connect

TrpY regulates the transcription of the metabolically expensive tryptophan-biosynthetic operon in the thermophilic archaeon Methanothermobacter thermautotrophicus. TrpY was crystallized using the hanging-drop method with ammonium sulfate as the precipitant. The crystals belonged to the tetragonal space group P4{sub 3}2{sub 1}2 or P4{sub 1}2{sub 1}2, with unit-cell parameters a = b = 87, c = 147 {angstrom}, and diffracted to 2.9 {angstrom} resolution. The possible packing of molecules within the cell based on the values of the Matthews coefficient (V{sub M}) and analysis of the self-rotation function are consistent with the asymmetric unit being a dimer. Determining the structure of TrpY in detail will provide insight into the mechanisms of DNA binding, tryptophan sensing and transcription regulation at high temperature by this novel archaeal protein.

J Cafasso; B Manjasetty; E Karr; K Sandman; M Chance; J Reeve

2011-12-31T23:59:59.000Z

291

Three-body recombination of two-component cold atomic gases into deep dimers in an optical model  

E-Print Network (OSTI)

We consider three-body recombination into deep dimers in a mass-imbalanced two-component atomic gas. We use an optical model where a phenomenological imaginary potential is added to the lowest adiabatic hyper-spherical potential. The consequent imaginary part of the energy eigenvalue corresponds to the decay rate or recombination probability of the three-body system. The method is formulated in details and the relevant qualitative features are discussed as functions of scattering lengths and masses. We use zero-range model in analyses of recent recombination data. The dominating scattering length is usually related to the non-equal two-body systems. We account for temperature smearing which tends to wipe out the higher-lying Efimov peaks. The range and the strength of the imaginary potential determine positions and shapes of the Efimov peaks as well as the absolute value of the recombination rate. The Efimov scaling between recombination peaks is calculated and shown to depend on both scattering lengths. Reco...

Mikkelsen, M; Fedorov, D V; Zinner, N T

2015-01-01T23:59:59.000Z

292

A Twist-Bend Chiral Helix of 8nm Pitch in a Nematic Liquid Crystal of Achiral Molecular Dimers  

E-Print Network (OSTI)

Freeze Fracture Transmission Electron Microscopy (FFTEM) study of the nanoscale structure of the so-called "twist-bend" nematic (NX) phase of the cyanobiphenyl (CB) dimer molecule CB(CH2)7CB reveals a stripe texture of fluid layers periodically arrayed with a bulk spacing of d ~ 8.3 nm. Fluidity and a rigorously maintained spacing produce long-range-ordered fluid layered focal conic domains. Absence of a lamellar x-ray reflection at wavevector q ~ 2{\\pi}/8 nm-1 or its harmonics in synchrotron-based scattering experiments indicates that this periodic structure is achieved with no detectable associated modulation of the electron density, and thus has nematic molecular ordering. A search for periodic ordering with d ~ 8nm in CB(CH2)7CB using atomistic molecular dynamic computer simulation yielded equilibration of a conical twist-bend helixed nematic ground state, of the sort first proposed by Meyer, and envisioned in systems of bent molecules by Dozov and Memmer, We identify {\\theta} ~ 33 degree as the cone angle, and p ~ 8nm as the full pitch of the helix, the shortest ever found in a nematic fluid.

Dong Chen; Jan H. Porada; Justin B. Hooper; Arthur Klittnick; Yongqiang Shen; Eva Korblova; Dmitry Bedrov; David M. Walba; Matthew A. Glaser; Joseph E. Maclennan; Noel A. Clark

2013-06-24T23:59:59.000Z

293

Calculation of two-centre two-electron integrals over Slater-type orbitals revisited. III. Case study of the beryllium dimer  

E-Print Network (OSTI)

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.

Micha? Lesiuk; Micha? Przybytek; Monika Musia?; Bogumi? Jeziorski; Robert Moszynski

2014-10-22T23:59:59.000Z

294

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

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

Authors, Various

2011-01-01T23:59:59.000Z

295

Catalysis to produce hydrogen.  

E-Print Network (OSTI)

??The present study is focused on two studies. The kinetics 0: methane steam reforming over a Ni/MgO catalyst at high pressure is reported in the (more)

Assanee, Natthakich

2008-01-01T23:59:59.000Z

296

Homogeneous Catalysis: Ultimate Selectivity  

Science Journals Connector (OSTI)

...explanation is that the economics are not good right now...aban-doned because of economics. Monsanto thinks the...significant by-product is methane, which may represent...syngas. Syngas made by steam reforming of natural gas con-tains...

THOMAS H. MAUGH II

1983-06-03T23:59:59.000Z

297

Catalysis and Prebiotic Synthesis  

Science Journals Connector (OSTI)

...Dust particles from asteroids and comets float down through the atmosphere and make a soft landing on the Earths surface. Meteorites...present on the primitive Earth. Comets. As noted previously comets formed in the outer regions of the...

James P. Ferris

298

Catalysis: principles, progress, prospects  

Science Journals Connector (OSTI)

...been extensively used since the days of Sabatier. The mechanisms will be discussed by...This catalyst has impressive longevity; reactors filled with it operate for years without...Tennison, S.R 1991Ruthenum catalyst for improved ammonia synthesisJ JenningsIn Catalytic...

2005-01-01T23:59:59.000Z

299

In situ catalysis | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

Leads No leads are available at this time. Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR...

300

Catalysis Without Precious Metals  

SciTech Connect

Written for chemists in industry and academia, this ready reference and handbook summarizes recent progress in the development of new catalysts that do not require precious metals. The research thus presented points the way to how new catalysts may ultimately supplant the use of precious metals in some types of reactions, while highlighting the remaining challenges. This material is based upon work supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

Bullock, R. Morris

2010-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

character- ""'''"'"" ultra-high vacuum (UHV) conditions.To of ESR UHV techniques, which we shall various clean gasesheart of the design is UHV- ESR resonant microwave cavity

Authors, Various

2011-01-01T23:59:59.000Z

302

Computational Catalysis and Electrocatalysis  

E-Print Network (OSTI)

· Hydrogen storage · Photocatalysis #12;Fuel cell electrocatalysts Parallelism between bimetallics;Applications from our research · Fuel cell electrocatalysts · Controlled growth of carbon nanostructures-- Another fuel cell challenge #12;Predictions and challenges Using molecular dynamics simulations we showed

303

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

Activity of Transition-Metal Carbides Wendell S. Williamsand testing of transition-metal carbide electrodes forproperties of transition metal carbides in the writervs

Authors, Various

2011-01-01T23:59:59.000Z

304

Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production  

SciTech Connect

Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory is needed to unravel the basic interactions behind these phenomena and to provide a general framework for the interpretation of experimental results. Ideally, theoretical calculations based on density-functional theory have evolved to the point that one should be able to predict patterns in the activity of catalytic surfaces. As in the case of experimental techniques, no single theoretical approach is able to address the large diversity of phenomena occurring on a catalyst. Catalytic surfaces are usually modeled using either a finite cluster or a two-dimensionally periodic slab. Many articles have been published comparing the results of these two approaches. An important advantage of the cluster approach is that one can use the whole spectrum of quantum-chemical methods developed for small molecules with relatively minor modifications. On the other hand, the numerical effort involved in cluster calculations increases rather quickly with the size of the cluster. This problem does not exist when using slab models. Due to the explicit incorporation of the periodicity of the crystal lattice through the Bloch theorem, the actual dimension of a slab calculation depends only on the size of the unit cell. In practical terms, the slab approach is mainly useful for investigating the behavior of adsorbates at medium and high coverages. Very large unit cells are required at the limit of low to zero coverage, or when examining the properties and chemical behavior of isolated defect sites in a surface. In these cases, from a computational viewpoint, the cluster approach can be much more cost effective than the slab approach. Slab and cluster calculations can be performed at different levels of sophistication: semi-empirical methods, simple ab initio Hartree-Fock, ab initio post-Hartree-Fock (CI, MP2, etc), and density functional theory. Density-functional (DF) based calculations frequently give adsorption geometries with a high degree of accuracy and predict reliable trends for the energetics of adsorption reactions. This article provides a review of recent theoretical studies that deal with the behavior of novel catalysts used for hydrodesulfurization (HDS) reactions and the production of hydrogen (i.e. catalytic processes employed in the generation of clean fuels). These studies involve a strong coupling of theory and experiment. A significant fraction of the review is focused on the importance of size-effects and correlations between the electronic and chemical properties of catalytic materials. The article begins with a discussion of results for the desulfurization of thiophene on metal carbides and phosphides, systems which have the potential to become the next generation of industrial HDS catalysts. Then, systematic studies con

Rodriguez,J.A.; Liu, P.

2008-10-01T23:59:59.000Z

305

Design, Synthesis and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals  

SciTech Connect

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.

Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

2007-03-31T23:59:59.000Z

306

Electronic structure and reactivity in water splitting of the iron oxide dimers and their hexacarbonyls: A density functional study  

SciTech Connect

The iron oxide dimers (FeO){sub 2} and their peroxide isomers are studied with the B3LYP density functional as bare clusters and as hexacarbonyls. Among the bare clusters the planar four-member ring structures are more stable than the non-planar ones and the rhombic dioxide Fe{sub 2}O{sub 2} with antiferromagnetically ordered electrons on iron centers is the global minimum. Water adsorption on the bare diiron dioxide is exothermic, but dissociation does not occur. Carbonylation favors a non-planar Fe{sub 2}O{sub 2} ring for both the dioxides and the peroxides and high electron density at the Fe centers is induced, evidenced by the natural charge distribution, the high proton affinity, and the values of global electronegativity and hardness. The iron dioxide hexacarbonyl Fe{sub 2}O{sub 2}(CO){sub 6} is diamagnetic in the state of the global minimum. It is separated from the next low-lying triplet state by a small energy gap of 0.22 eV. Time-dependent density functional theory methods were applied to examine electron excitations from the ground state to the low-lying triplet states in the hexacarbonyls and their adsorption complexes with water. Singlet-to-triplet state excitations occur via ligand-to-metal charge transfer in the hexacarbonyls; in the adsorption complexes excitations from the oxygen lone pairs to the adsorption center also occur and they appear in the IR-visible region. The lowest energy singlet and triplet state reaction paths for water splitting were followed. On the singlet potential energy surface (PES), water splitting is spontaneous, while for the triplet PES an activation barrier of 14.1 kJ mol{sup ?1} was determined.

Uzunova, Ellie L., E-mail: ellie@svr.igic.bas.bg [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Mikosch, Hans [Institute for Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/E164-EC, 1060 Vienna (Austria)] [Institute for Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/E164-EC, 1060 Vienna (Austria)

2014-01-14T23:59:59.000Z

307

Design of an efficient single photon source from a metallic nanorod dimer: a quasinormal mode finite-difference time-domain approach  

E-Print Network (OSTI)

We describe how the finite-difference time-domain (FDTD) technique can be used to compute the quasinormal mode (QNM) for metallic nano-resonators, which is important for describing and understanding light-matter interactions in nanoplasmonics. We use the QNM to model the enhanced spontaneous emission rate for dipole emitters near a gold nanorod dimer structure using a newly developed QNM expansion technique. Significant enhanced photon emission factors of around 1500 are obtained with large output $\\beta$-factors of about $60\\%$.

Ge, Rong-Chun

2015-01-01T23:59:59.000Z

308

Calculation of two-centre two-electron integrals over Slater-type orbitals revisited. III. Case study of the beryllium dimer  

E-Print Network (OSTI)

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-...

Lesiuk, Micha?; Musia?, Monika; Jeziorski, Bogumi?; Moszynski, Robert

2014-01-01T23:59:59.000Z

309

Biodiesel production from Stauntonia chinensis seed oil (waste from food processing): Heterogeneous catalysis by modified calcite, biodiesel purification, and fuel properties  

Science Journals Connector (OSTI)

Abstract In the present research, the potential of Stauntonia chinensis (SC) seed oil obtained from processing waste was investigated for the first time as biodiesel feedstock, including physicochemical properties of the oil, the heterogeneous catalysis process, purification, and fuel properties. A 29.370.64wt.% of oil content and 2.41mg KOH/g of acid value was found. Under the optimised reaction conditions in the presence of modified calcite, an 88.02% of yield and a 98.90wt.% of FAME content were achieved. According to EN 14124 (2012), SC biodiesel exhibited superior fuel properties compared to the most of other feedstock oils since it had an ideal fatty acid composition (low Cn:0 (8.06wt.%), high Cn:1 (80.16wt.%), and low Cn:2,3 (8.45wt.%)). It was absolutely vital that the use of SC seed oil as a biodiesel feedstock would not compete with its use in food. In summary, SC seed oil should be recommended as a promising feedstock for biodiesel.

Rui Wang; Lili Sun; Xiaolin Xie; Lizhi Ma; Zhigang Liu; Xiaoyan Liu; Ning Ji; Guofang Xie

2014-01-01T23:59:59.000Z

310

-stacking and C-XD (X = H, NO2; D = O, ) interactions in the crystal network of both C-HN and -stacked dimers of 1,2-bis(4-bromophenyl)-1H-benzimidazole and 2-(4-bromophenyl)-1-(4-nitrophenyl)-1H-benzimidazole  

Science Journals Connector (OSTI)

Molecules of two substituted 1H-benzimidazoles are arranged in dimeric units through C-HN and parallel-displaced -stacking interactions. The molecular packing of the dimers arises by the concurrence of a diverse set of weak intermolecular C-XD (X = H, NO2; D = O, ) interactions.

Gonz?lez-Padilla, J.E.

2013-12-21T23:59:59.000Z

311

Lineshape of the singlet-triplet excitations in the dimer system Sr3Cr2O8 to first order in the high-density 1/z expansion  

Science Journals Connector (OSTI)

The Cr5+ ions in Sr3Cr2O8 constitute a strongly correlated spin-1/2 dimer system. Experiments show that the collective singlet-triplet excitations in this system are well defined in the zero-temperature limit, but, when heated, the inelastic neutron scattering peaks decrease rapidly in intensity and acquire a nonzero line width. When including the fluctuations to leading order in 1/z, where z is the coordination number, the diagrammatic high-density expansion is found to offer an accurate description of the singlet-triplet excitations. The theory explains not only the temperature dependencies of the intensities and line widths, but also that strong correlation causes the lineshapes to become asymmetric at temperatures comparable to the excitation energies.

J. Jensen; D. L. Quintero-Castro; A. T. M. N. Islam; K. C. Rule; M. Mnsson; B. Lake

2014-04-11T23:59:59.000Z

312

Global Structure of a Three-Way Junction in a Phi29 Packaging RNA Dimer Determined Using Site-Directed Spin Labeling  

SciTech Connect

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.

Zhang, Xiaojun; Tung, Chang-Shung; Sowa, Glenna; Hatmal, Ma'mon M.; Haworth, Ian S.; Qin, Peter Z.

2012-02-08T23:59:59.000Z

313

Visible-Light Photoredox Catalysis: Selective Reduction of Carbon Dioxide to Carbon Monoxide by a Nickel N-Heterocyclic Carbene-Isoquinoline Complex  

SciTech Connect

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.

Thoi, VanSara; Kornienko, Nick; Margarit, C; Yang, Peidong; Chang, Christopher

2013-06-07T23:59:59.000Z

314

Ab initio calculations in heterogeneous and homogeneous catalysis: I. Methanol to gasoline with ZSM-5. II. Carbonyl ligand effects on metal-metal bonds  

SciTech Connect

This thesis is composed of two studies in catalysis. The first is an exploration, using computational techniques, of the mechanism for the first carbon-carbon bond formation in the methanol to gasoline (MTG) reaction. The second is a study of the factors important to the understanding of ligand effects on metal-metal bonds, and in particular, to metal clusters. Three possibilities were considered as ways to activate a carbon in the MTG process prior to formation of C2 or higher hydrocarbons. These were a free radical mechanism, a surface ylide mechanism, and a possible defect site which might lead to steric crowding of CH[sub 2] groups. Although the free radical mechanism was found to be thermodynamically within the parameters of the MTG process, it contained a high transition state. Consideration of the molecules available prior to hydrocarbon build-up and their specific electronic structure, led to the view that the available carbon atoms (methanol, dimethyl ether, etc.) were unlikely to be activated by a free radical intermediate. The surface-stabilized ylide which has been proposed as an intermediate by many was studied to determine if in fact the ylide was stabilized. The total energy of the ylide was compared to that of the naked site on the zeolite and free methylene. Free methylene ranged, depending on the geometry of the ylide, between 50 and 80 kcal more stable. These numbers are qualitatively correct, but more electron correlation would have to be incorporated in the calculation to get an accurate value for the destabilization. Starting from a defect site, two CH[sub 2] groups were each attached to two oxygen atoms. It was thought that two CH[sub 2] groups would take up considerably more space than either than original Al atom or the four hydrogens. Molecular Mechanics calculations showed the zeolite to be sufficiently flexible to prevent crowding of the CH[sub 2]'s.

Miller, A.E.

1993-01-01T23:59:59.000Z

315

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

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.

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

316

Characterization of fundamental catalytic properties of MoS2/WS2 nanotubes and nanoclusters for desulfurization catalysis - a surface temperature study  

SciTech Connect

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

U. Burghaus

2012-07-05T23:59:59.000Z

317

Global-to-local incompatibility, monogamy of entanglement, and ground-state dimerization: Theory and observability of quantum frustration in systems with competing interactions  

E-Print Network (OSTI)

Frustration in quantum many body systems is quantified by the degree of incompatibility between the local and global orders associated, respectively, to the ground states of the local interaction terms and the global ground state of the total many-body Hamiltonian. This universal measure is bounded from below by the ground-state bipartite block entanglement. For many-body Hamiltonians that are sums of two-body interaction terms, a further inequality relates quantum frustration to the pairwise entanglement between the constituents of the local interaction terms. This additional bound is a consequence of the limits imposed by monogamy on entanglement shareability. We investigate the behavior of local pair frustration in quantum spin models with competing interactions on different length scales and show that valence bond solids associated to exact ground-state dimerization correspond to a transition from generic frustration, i.e. geometric, common to classical and quantum systems alike, to genuine quantum frustration, i.e. solely due to the non-commutativity of the different local interaction terms. We discuss how such frustration transitions separating genuinely quantum orders from classical-like ones are detected by observable quantities such as the static structure factor and the interferometric visibility.

S. M. Giampaolo; B. C. Hiesmayr; F. Illuminati

2015-01-25T23:59:59.000Z

318

Extra sub-Doppler lines in the vicinity of the third-resonance 6S-8P transition of atomic Cs attributed to optically induced Cs dimers  

SciTech Connect

We report on the observation of additional sub-Doppler lines in a saturated absorption experiment when exploring the vicinity of the 6S{sub 1/2}-8P{sub 3/2} transition of Cs ({lambda}=388 nm). These additional lines are observed only under a relatively strong irradiation of both the pump and the probe beams. Extra narrow lines are also observed in copropagating nonlinear spectroscopy, and around the lines of the V-type three-level system 8P{sub 3/2}-6S{sub 1/2}-8P{sub 1/2} ({lambda}{sub 1}=388 nm, {lambda}{sub 2}=389 nm). We attribute theses additional lines to a probing of high-lying molecular cesium, produced as a result of the optical excitation of Cs atoms, as the low Cs atom density ({<=}10{sup 12}cm{sup -3}) is unable to populate significantly the dimer states in the condition of thermal equilibrium.

Passerat de Silans, Thierry; Maurin, Isabelle; Laliotis, Athanasios; Segundo, Pedro Chaves de Souza; Bloch, Daniel [Laboratoire de Physique des Lasers, Institut Galilee, Universite Paris 13, Villetaneuse, UMR 7538 du CNRS, 99 AvenueJ.B. Clement, F-93430 Villetaneuse (France)

2011-04-15T23:59:59.000Z

319

Solution structure of a fragment of the dimerization domain of DP-1 determined by 1H-nuclear magnetic resonance and distance geometry  

Science Journals Connector (OSTI)

The structure of a synthesized peptide with the sequence of NHILPNESAYDQKNIRRRVYDALNVLMAMNIISK that corresponds to residues 151184 of transcription factor DP-1 (Girling et al., Nature 362 (1993) 8387) was determined by 1H-nuclear magnetic resonance in water and 40% d3-trifluoroethanol/water, respectively. Nuclear Overhauser effect cross peaks, ?H chemical shifts and J-coupling constants of ?HNH show that the peptide consists a helix from Ser-8 to Ser-33 in solution. Fifty structures were constructed with 288 upper distance limits and 21 angle constraints by DIANA (Guntert et al., J. Mol. Biol. 217 (1991) 517530). Although the N-terminal of the peptide exhibits a random conformation, the 20 best structures show a root mean square deviation of 0.890.36 for backbone atoms and 1.800.34 for heavy atoms from residue Ser-8 to Ser-33. This result supports the proposal that DP-1 and E2F-1 may dimerize with a coiled-coil type interaction.

Shouhong Guang; Jihui Wu; Tianning Yu; Youlin Xia; Yunyu Shi

1998-01-01T23:59:59.000Z

320

Solution structure of a fragment of the dimerization domain of E2F-1 determined by circular dichroism, 1H nuclear magnetic resonance and distance geometry  

Science Journals Connector (OSTI)

The structure of a synthesized peptide with the sequence GVVDLNWAAEVLKVQKRRIYDITNVLEGIQ which corresponds to residues 149178 of transcription factor E2F-1 was determined by 1H nuclear magnetic resonance in 40% d3-TFE/water. NOE cross peaks and ?H chemical shifts indicate that the peptide consists of a helix from Ala-8 to Leu-26 in this solution. Circular dichroism measurements confirm the presence of nearly 45% helix in TFE/water solution but show no evidence of helicity in water solution of this peptide. Fifty structures were constructed with 329 upper distance limits by DIANA. The 20 best conformers show a RMSD of 0.78 for backbone atoms and 1.78 for heavy atoms from residue Ala-8 to Leu-26. This result, together with our previous work on the solution structure of a fragment of DP-1, supports the proposal that E2F-1 and DP-1 may dimerize with a coiled-coil type interaction.

Shouhong Guang; Jihui Wu; Limei Tao; Youlin Xia; Yunyu Shi

1998-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Homogeneous Catalysis in Supercritical Fluids  

Science Journals Connector (OSTI)

...structure similar to a [2Fe-2S]-type iron-sulfur center. Previ-ously predicted...11. The 2 binding site contains heme a3 iron and copper atoms (CUB) with an interatomic...is no detectable bridging ligand between iron and copper atoms in spite of a strong antifer-romagnetic...

Philip G. Jessop; Takao Ikariya; Ryoji Noyori

1995-08-25T23:59:59.000Z

322

Catalysis and the hydrogen economy  

Science Journals Connector (OSTI)

Perspectives regarding the current and future production of hydrogen are offered. It is important to appreciate...2 is captively produced and not easily committed to a major new market need (such as H2 for fuel c...

J. N. Armor

2005-06-01T23:59:59.000Z

323

Acid Catalysis in Modern Organic  

E-Print Network (OSTI)

catalyst for organic synthesis". That is the starting sentence of this book by Yamamoto and Ishihara, which follows their earlier book "Lewis Acids in Organic Synthesis (2000)", and covers the new developments book that should be available in every well-equipped chemistry library. It will certainly be helpful

Snyder, Scott A.

324

Muon catalysis of hot fusion  

Science Journals Connector (OSTI)

... all rates to the nearest order of magnitude). In other words, stripping of the muon is very probable, and it would thus be able to take part in further ... the confinement time is 109s, and the reaction rate 109s-1, on average each muon would catalyse one reaction, hence the occurrence of Rc (the catalytic chain ratio) ...

E. P. HINCKS; M. K. SUNDARESAN; P. J. S. WATSON

1977-10-13T23:59:59.000Z

325

Center for Environmentally Beneficial Catalysis  

E-Print Network (OSTI)

to Hone Your Wri·ng Skills Thursday, December 4, 2014 9:00-10:30 a.m. Conference Room B CEBC Building B, novel media and separa!ons to develop sustainable technologies for industrially significant chemicals of College Reading and Learning, and the Wri·ng Center Journal. With Rebecca Babcock, she co

326

"Nanocrystal bilayer for tandem catalysis"  

E-Print Network (OSTI)

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

Yamada, Yusuke

2012-01-01T23:59:59.000Z

327

SOUTHWEST CATALYSIS 2013 SPRING SYMPOSIUM  

E-Print Network (OSTI)

9:15 AM Jerry Spivey, LSU Cain Department of Chemical Engineering, Baton Rouge, LA "Natural Gas to Syngas Using Rh-Substituted Pyrochlore (La2Zr2O7) Catalysts" 9:45 AM Coffee Break 10:05 AM Tushar V

Natelson, Douglas

328

Reaction Selectivity in Heterogeneous Catalysis  

E-Print Network (OSTI)

of ultrahigh vacuum (UHV) surface science techniques.low pressure probes typical of UHV surface science. At thesecan be employed in-situ from UHV pressures to above ambient

Somorjai, Gabor A.

2010-01-01T23:59:59.000Z

329

Cr3+Co0.054Ni0.018Mg0.93O Solid-Solution Catalysts for High-Pressure Syngas Production: Effect of Chromium on the Reduction and Catalysis  

Science Journals Connector (OSTI)

Cr3+Co0.054Ni0.018Mg0.93O Solid-Solution Catalysts for High-Pressure Syngas Production: Effect of Chromium on the Reduction and Catalysis ... (1) Reforming CH4 with CO2 (CH4 + CO2 ? 2H2 + 2CO) or H2O (CH4 + H2O ? 3H2 + CO) to produce syngas (CO + H2) is attracting renewed attention because advances in shale gas technology have increased the global supply of recoverable CH4(2-6) and because the process consumes CO2, a global warming gas. ... US natural gas emissions produced in the year 2008, prior to any significant Marcellus shale development. ...

Katsutoshi Nagaoka; Yosuke Abe; Yusaku Hashimoto; Takahiro Ishikawa; Katsutoshi Sato; Yusaku Takita; Toshiya Wakatsuki; Masahiro Kunisu; Eri Suda; Shin Inamoto

2013-05-27T23:59:59.000Z

330

Ruthenium polypyridyl phototriggers: from beginnings to perspectives  

Science Journals Connector (OSTI)

...on a filter paper soaked in LB medium containing RuBi-MTG was illuminated with a given pattern by means of a light-emitting diode (LED)-powered pocket projector, resulting in the localized expression of the target reporter beta-galactosidase...

2013-01-01T23:59:59.000Z

331

Ruthenium polypyridyl phototriggers: from beginnings to perspectives  

Science Journals Connector (OSTI)

...C1428EHA,-Buenos Aires, Argentina One contribution of 18 to...a ligand. Given that the energy of the d-d state is somewhat...temperature, therefore, a higher energy 3MLCT band (which corresponds to a higher energy 1MLCT and a blue-shifted...

2013-01-01T23:59:59.000Z

332

Ruthenium Aluminides: Deformation Mechanisms and Substructure Development  

SciTech Connect

Structural and functional materials that can operate in severe, high temperature environments are key to the operation of a wide range of energy generation systems. Because continued improvements in the energy efficiency of these systems is critical, the need for new materials with higher temperature capabilities is inevitable. Intermetallic compounds, with strong bonding and generally high melting points offer this possibility for a broad array of components such as coatings, electrode materials, actuators and/or structural elements. RuAl is a very unusual intermetallic compound among the large number of B2compounds that have been identified and investigated to date. This material has a very high melting temperature of 2050?C, low thermal expansion, high thermal conductivity and good corrosion resistance. Unlike most other high temperature B2 intermetallics, RuAl possesses good intrinsic deformability at low temperatures. In this program fundamental aspects of low and high temperature mechanical properties and deformation mechanisms in binary and higher order RuAl-based systems have been investigated. Alloying additions of interest included platinum, boron and niobium. Additionally, preliminary studies on high temperature oxidation behavior of these materials have been conducted.

Tresa M. Pollock

2005-05-11T23:59:59.000Z

333

Visualization by BiFC of different C/EBP{beta} dimers and their interaction with HP1{alpha} reveals a differential subnuclear distribution of complexes in living cells  

SciTech Connect

How the co-ordinated events of gene activation and silencing during cellular differentiation are influenced by spatial organization of the cell nucleus is still poorly understood. Little is known about the molecular mechanisms controlling subnuclear distribution of transcription factors, and their interplay with nuclear proteins that shape chromatin structure. Here we show that C/EBP{beta} not only associates with pericentromeric heterochromatin but also interacts with the nucleoskeleton upon induction of adipocyte differentiation of 3T3-L1 cells. Different C/EBP{beta} dimers localize in different nuclear domains. Using BiFC in living cells, we show that LAP (Liver Activating Protein) homodimers localize in euchromatin and heterochromatin. In contrast, LIP (Liver Inhibitory Protein) homodimers localize exclusively in heterochromatin. Importantly, their differential subnuclear distribution mirrors the site for interaction with HP1{alpha}. HP1{alpha} inhibits LAP transcriptional capacity and occupies the promoter of the C/EBP{beta}-dependent gene c/ebp{alpha} in 3T3-L1 preadipocytes. When adipogenesis is induced, HP1{alpha} binding decreases from c/ebp{alpha} promoter, allowing transcription. Thus, the equilibrium among different pools of C/EBP{beta} associated with chromatin or nucleoskeleton, and dynamic changes in their interaction with HP1{alpha}, play key roles in the regulation of C/EBP target genes during adipogenesis.

Susperreguy, Sebastian; Prendes, Luciana P.; Desbats, Maria A.; Charo, Nancy L. [Instituto de Biologia y Medicina Experimental, CONICET, Buenos Aires (Argentina)] [Instituto de Biologia y Medicina Experimental, CONICET, Buenos Aires (Argentina); Brown, Karen [Chromosome Biology Group, Imperial College of London, London (United Kingdom)] [Chromosome Biology Group, Imperial College of London, London (United Kingdom); MacDougald, Ormond A. [Dept. of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI (United States)] [Dept. of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI (United States); Kerppola, Tom [Dept. of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI (United States)] [Dept. of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI (United States); Schwartz, Jessica [Dept. of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI (United States)] [Dept. of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI (United States); Piwien-Pilipuk, Graciela, E-mail: gpiwien@conicet.gov.ar [Instituto de Biologia y Medicina Experimental, CONICET, Buenos Aires (Argentina)] [Instituto de Biologia y Medicina Experimental, CONICET, Buenos Aires (Argentina)

2011-04-01T23:59:59.000Z

334

Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis...  

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

will enable energy-efficient biochemical conversion of lignocellulosic biomass into biofuels that are compatible with today's vehicles and infrastructure. Photos (clockwise from...

335

Method for producing catalysis from coal  

DOE Patents (OSTI)

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.

Farcasiu, Malvina (Pittsburgh, PA); Derbyshire, Frank (Lexington, KY); Kaufman, Phillip B. (Library, PA); Jagtoyen, Marit (Lexington, KY)

1998-01-01T23:59:59.000Z

336

Exploring Nitrilase Sequence Space for Enantioselective Catalysis  

Science Journals Connector (OSTI)

...nitrilase sequence space. While most of the...same environmental library yielded two very...protein sequence space and for solving problems...generating synthetic gene libraries comprised of arrays...nitrilase sequence space for enantioselective...environmental DNA (eDNA) libraries, were characterized...

Dan E. Robertson; Jennifer A. Chaplin; Grace DeSantis; Mircea Podar; Mark Madden; Ellen Chi; Toby Richardson; Aileen Milan; Mark Miller; David P. Weiner; Kelvin Wong; Jeff McQuaid; Bob Farwell; Lori A. Preston; Xuqiu Tan; Marjory A. Snead; Martin Keller; Eric Mathur; Patricia L. Kretz; Mark J. Burk; Jay M. Short

2004-04-01T23:59:59.000Z

337

Exploring Nitrilase Sequence Space for Enantioselective Catalysis  

Science Journals Connector (OSTI)

...nitrilase sequence space. While most of...same environmental library yielded two very...of environmental libraries from which individual...associated dot. The public database enzymes...nitrilase sequence space for enantioselective...environmental DNA (eDNA) libraries, were characterized...

Dan E. Robertson; Jennifer A. Chaplin; Grace DeSantis; Mircea Podar; Mark Madden; Ellen Chi; Toby Richardson; Aileen Milan; Mark Miller; David P. Weiner; Kelvin Wong; Jeff McQuaid; Bob Farwell; Lori A. Preston; Xuqiu Tan; Marjory A. Snead; Martin Keller; Eric Mathur; Patricia L. Kretz; Mark J. Burk; Jay M. Short

2004-04-01T23:59:59.000Z

338

Nanoscale Advances in Catalysis and Energy Applications  

E-Print Network (OSTI)

  Hara,  M. ,   Biomass  conversion  by  a  solid  key  step  in  biomass  conversion. [35-­‐39]  Many catalyst  for  biomass   conversion:  Synthesis  of

Li, Yimin

2011-01-01T23:59:59.000Z

339

Accounting for Scale in Catalysis | EMSL  

NLE Websites -- All DOE Office Websites (Extended Search)

catalyst's heat transfer, thickness, and feedstock movement The thickness of the RuO2 catalyst, along with heat and mass transfer, affect the speed with which carbon monoxide is...

340

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

More recently, Air Products and Chemicals Corporation hasProcess Division of Air Products & Chemicals, Inc. HC Q)air oxidation of isobutane. T-butyl alcohol is a co- product

Heinemann, Heinz

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Nanoscale Advances in Catalysis and Energy Applications  

E-Print Network (OSTI)

 J.Y.  Park,   The  nanoscience  revolution:  Merging  Nanocatalysis.   Nanoscience  and  technology,.    The  impact  of  nanoscience  on  heterogeneous  

Li, Yimin

2011-01-01T23:59:59.000Z

342

Relativistic effects in homogeneous gold catalysis  

Science Journals Connector (OSTI)

... Int. Edn 45, 29012904 (2006) Furstner, A. & Hannen, P. Carene terpenoids by gold-catalyzed cycloisomerization reactions. Chem. Commun. 25462547 (2004) Furstner, ...

David J. Gorin; F. Dean Toste

2007-03-22T23:59:59.000Z

343

Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis...  

Energy Savers (EERE)

BETO works with the emerging U.S. bioindustry to sustainably convert non-food biomass resources into cost-competitive biofuels, biopower, and bioproducts....

344

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

HYDROGENATIONS VINYL CHLORIDE MONOMER ( OXYCHLORINA'I'ION)and other monomers, such as vinyl- chloride, which cannot be

Heinemann, Heinz

2013-01-01T23:59:59.000Z

345

Silica grain catalysis of methanol formation  

Science Journals Connector (OSTI)

......molecules such as acetaldehyde (CH3CH=O), acetylene (C2H2), ethylene (C2H4) and hydrogen cyanide (HCN) where the double and...Surf. Sci., 500, 823. Williams D. A. , Brown W. A., Price S. D., Rawlings J. M. C., Viti S., 2007, Astron......

T. P. M. Goumans; Adrian Wander; C. Richard A. Catlow; Wendy A. Brown

2007-12-21T23:59:59.000Z

346

BERKELEY CATALYSIS CENTER Distinguished Lecture Series  

E-Print Network (OSTI)

® combustion module in Sonoma marks the first commercial application of a natural gas-fired catalytic combustion device for power generation after almost 30 years of R&D world-wide. The module in the 9.5-atm KHI of a lean pre-burner and highly efficient fuel/air mixer. PdO catalysts under operation for power generation

Iglesia, Enrique

347

Two component-three dimensional catalysis  

DOE Patents (OSTI)

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.

Schwartz, Michael (Boulder, CO); White, James H. (Boulder, CO); Sammells, Anthony F. (Boulder, CO)

2002-01-01T23:59:59.000Z

348

BERKELEY CATALYSIS CENTER Friday November 18, 2005  

E-Print Network (OSTI)

. The catalyst employed was silica-supported manganese oxide (MnO2/SiO2) because of the well-known activity it is a common industrial solvent, and the health risks associated with acetone are similar to those of many other VOCs. In order to obtain molecular level information about the various steps in the catalytic

Iglesia, Enrique

349

EMSL and Institute for Integrated Catalysis (IIC)  

NLE Websites -- All DOE Office Websites (Extended Search)

toward advancing our ability to control chemical transformations and chemical-electrical energy inter-conversions. Consistent with recommendations from recent DOE- and...

350

CNEEC - TRG3: Nanoscale Control in Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

achieve the required catalytic properties to enable efficient and cost-effective energy conversion devices. In this thrust we are focusing our efforts on electro-chemical...

351

Nanoscale Advances in Catalysis and Energy Applications  

Science Journals Connector (OSTI)

(50) Energy conversion and transport in nanomaterials differs significantly from that in bulk materials because of classical and quantum size effects on energy carriers such as photons, phonons, electrons, and molecules. ... (52) Photovoltaic cells convert the photon energy directly to electricity by separating the excited electron?hole pairs in photovoltaic materials. ... By band engineering through controlling the size, shape, chemical composition, and heterojunction of semiconductor materials, nanomaterials provide the opportunity to achieve high efficiencies for sunlight to charge conversion and chemical conversions at the electrode surfaces at the same time. ...

Yimin Li; Gabor A. Somorjai

2010-06-04T23:59:59.000Z

352

UNCORRECTEDPROOF Catalysis Today xxx (2003) xxxxxx  

E-Print Network (OSTI)

most interest- ing crystallographic form of titanium dioxide. Results are compared to the extensively in the adsorption/desorption behavior of water and methanol. The anatase (1 0 0) surface has the second formation on well-characterized anatase surfaces. So 41 far, surface science investigations for titanium

Diebold, Ulrike

353

Phase-Transfer Catalysis in Analytical Chemistry  

Science Journals Connector (OSTI)

In analytical chemistry, analytes must sometimes be reacted with derivatizing reagents to facilitate analysis. Derivatization is needed when the analytes, without modification, cannot be easily separated using...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

354

Phase-Transfer Catalysis: Fundamentals I  

Science Journals Connector (OSTI)

Critical to the success of phase-transfer catalytic (PTC) processes are (1) the maximization of the rate of transfer of reactant anions from the aqueous or solid phase to the organic phase, (2) the maximizatio...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

355

Phase-Transfer Catalysis: Fundamentals II  

Science Journals Connector (OSTI)

Phase-transfer catalytic (PTC) systems are characterized by the presence of at least two phases and at least one interfacial region separating the phases [18]. Reactions taking place in such systems usually i...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

356

CATALYSIS IN BIOPOLYMER CHEMISTRY Joseph Bartholomew Binder  

E-Print Network (OSTI)

produced extraordinarily high yields of 5-hydroxymethylfurfural (HMF) from not only fructose and glucose

Raines, Ronald T.

357

Catalysis: "No Longer a Black Art"  

Science Journals Connector (OSTI)

...known as synthesis gas or syngas; syngas can be converted into...industry ha-ve been natural gas and the light frac-tions...sources, par-ticularly syngas and methanol. The best...research will lead to substitutes that will do the same...

THOMAS H. MAUGH II

1983-02-04T23:59:59.000Z

358

Catalysis Working Group | Department of Energy  

Energy Savers (EERE)

of the main focus areas of research and development activities of DOE's Hydrogen and Fuel Cells Program. In particular, DOE is seeking novel transformative research leading to...

359

Applications of Chiral Anions in Asymmetric Catalysis  

E-Print Network (OSTI)

without further purification. Small-scale reactions werewithout further purification. Small-scale reactions werewithout further purification. Small-scale reactions were

Hamilton, Gregory Lawrence

2011-01-01T23:59:59.000Z

360

Catalysis Today 9395 (2004) 615618 Synthesis and catalysis of nanometer-sized bimodal mesoporous  

E-Print Network (OSTI)

-particle pore. As a result of the special properties of the present material, the hydrothermal stability diffusion if its particle size is in microm- eter scale. As a result, cumulated carbon species can be easily, the hydrothermal stability of the MCM-41 is known to be too weak to use it for catalytic applications

Kim, Ji Man

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Intermolecular ET between Ruthenium Complexes and Cytochrome c  

NLE Websites -- All DOE Office Websites (Extended Search)

Comparative Kinetic Analysis of Reversible Intermolecular Electron-Transfer Comparative Kinetic Analysis of Reversible Intermolecular Electron-Transfer Reactions between a Series of Pentaammineruthenium Complexes and Cytochrome c Martin Meier, Ji Sun, James F. Wishart, and Rudi van Eldik Inorg. Chem. 35, 1564-1570 (1996) [Find paper at ACS Publications] Abstract: In this kinetic and thermodynamic study, the reversible outer-sphere electron-transfer reactions between a series of Ru(NH3)5L3+/2+ complexes (L = etpy, py, lut) (etpy = 4-ethylpyridine; py = pyridine; lut = 3,5-lutidine) and cytochrome c were investigated as a function of ionic strength, buffer, pH, temperature, and pressure. Due to the low driving forces of these systems, it was possible to study all the reactions in both redox directions. The observed rate constants for various L are correlated

362

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

chemicals; in the petroleum refining sector; and in laboratory equipment, including crucibles for growing Defense Stockpile remained suspended through FY 2013. Stockpile Status--9­30­13 4 Uncommitted Authorized; iridium prices were stable until midyear and then decreased markedly toward yearend, reportedly owing

363

Highly efficient and robust molecular ruthenium catalysts for water oxidation  

Science Journals Connector (OSTI)

...driven by solar radiation (H2O...high-capacity energy carrier. One of the obstacles now is the...sustainable energy systems such as solar fuels, much...driven by solar radiation (H...high-capacity energy carrier. One of the obstacles now is the...

Lele Duan; Carlos Moyses Araujo; Mrten S.G. Ahlquist; Licheng Sun

2012-01-01T23:59:59.000Z

364

Selective Lability of Ruthenium(II) Arene Amino Acid Complexes  

E-Print Network (OSTI)

, J.; Gomperts, R.; Strat-mann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, .; Foresman...

Scrase, Tom G.; ONeill, 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

365

Electrochemical capacitors based on electrodeposited ruthenium oxide on nanofibre  

Science Journals Connector (OSTI)

Electrodeposition of RuO2 on electrospun TiO2 nanorods using cyclic voltammetry is shown to increase the capacitance of RuO2. This phenomenon can be attributed to the large surface areas of the nanorods. Among several ranges of deposition, the range from 0.25 to 1.45V with respect to Ag/AgCl was effective. The electrode deposited with this range exhibited a specific capacitance of 534Fg?1 after deposition for 10cycles with a scan rate of 50mVs?1. The structural water content in RuO2 was quite different depending on the deposition potential range. Higher amounts of structural water increased the charge storage capability. The stability of the electrode was tested using cyclic voltammetry over 300cycles.

Young Rack Ahn; Mi Yeon Song; Seong Mu Jo; Chong Rae Park; Dong Young Kim

2006-01-01T23:59:59.000Z

366

XPS Study of a New Heterogeneous Ruthenium Catalyst Precursor  

Science Journals Connector (OSTI)

The catalyst precursor has been synthesized by modifying the silica surface with ClPPh2 followed by a surface reaction with RuCl3. Sup- ports consisting of a thin layer of SiO2 on a...

Smet, P; Verpoort, F; Doncker, G De; Bossuyt, A R; Fiermans, L; Verdonck, L

1997-01-01T23:59:59.000Z

367

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

by companies in Texas and Utah. Catalysts for air pollution abatement continued to be the largest demand sector in the manufacture of catalytic converters. Catalysts were also used in other air-pollution-abatement processes in kilograms, unless otherwise noted) Domestic Production and Use: The Stillwater and East Boulder Mines

368

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

by companies in Texas and Utah. Catalysts for air-pollution- abatement continued to be the leading demand industry in the manufacture of catalytic converters. Catalysts were also used in other air-pollution in kilograms unless otherwise noted) Domestic Production and Use: The Stillwater and East Boulder Mines

369

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

for air-pollution abatement in both light- and heavy-duty vehicles. PGMs are also used in the chemical in kilograms unless otherwise noted) Domestic Production and Use: The Stillwater and East Boulder Mines in south-central Montana were the only primary platinum-group metals (PGMs) mines in the United States

370

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

. Catalysts for air pollution abatement continued to be the largest demand sector for PGM. In the United of catalytic converters. Catalysts were also used in other air-pollution-abatement processes to remove organic in kilograms, unless otherwise noted) Domestic Production and Use: The Stillwater Mine is the only primary

371

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

are also used in other air pollution abatement processes to remove organic vapors, odors, or carbon platinum-group metals (PGM) mine. The mine, located near Nye, MT, processed more than 400,000 metric tons and biomedical devices. Salient Statistics--United States: 1995 1996 1997 1998 1999e Mine production:1 Platinum 1

372

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

automobile exhaust emissions. Oxidation catalysts are also used in many air pollution abatement processes platinum-group metals (PGM) mine. The mine, located near Nye, MT, processed about 430,000 metric tons--United States: 1994 1995 1996 1997 1998e Mine production: Platinum 1,960 1,590 1,840 2,610 3,5001 Palladium 6

373

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

refining by companies in Texas and Utah. Catalysts for air- pollution abatement continued to be the leading demand sector for PGMs. Catalysts were also used in other air- pollution-abatement processes to remove in kilograms unless otherwise noted) Domestic Production and Use: The Stillwater and East Boulder Mines

374

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

for air-pollution abatement in both light- and heavy-duty vehicles. PGMs are also used in the chemical in kilograms unless otherwise noted) Domestic Production and Use: The Stillwater and East Boulder Mines in south-central Montana are the only primary platinum-group metals (PGMs) mines in the United States

375

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

. Automobile catalysts for air pollution abatement continued to be the largest demand sector for PGM of catalysts. Catalysts are also used in other air-pollution-abatement processes to remove organic vapors in kilograms, unless otherwise noted) Domestic Production and Use: The Stillwater Mine is the only primary

376

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

. Catalysts for air pollution abatement continued to be the leading demand sector for PGMs. In the United of catalytic converters. Catalysts were also used in other air-pollution-abatement processes to remove organic in kilograms unless otherwise noted) Domestic Production and Use: The Stillwater and East Boulder Mines

377

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

of catalysts. Oxidation catalysts are also used in other air-pollution-abatement processes to remove organic in kilograms, unless otherwise noted) Domestic Production and Use: The Stillwater Mine is the only primary platinum-group metals (PGM) producer in the United States. The mine, located near Nye, MT, processed more

378

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

automobile exhaust emissions. Oxidation catalysts are also used in many air pollution abatement processes platinum-group metals (PGM) mine. The mine, located near Nye, MT, processed about 350,000 metric tons--United States: 1993 1994 1995 1996 1997e Mine production: Platinum 2,050 1,960 1,590 1,840 2,5002 Palladium 6

379

Ruthenium-Catalyzed Meta Sulfonation of 2-Phenylpyridines  

Science Journals Connector (OSTI)

Ourida Saidi , Jameel Marafie , Araminta E. W. Ledger , Po Man Liu , Mary F. Mahon , Gabriele Kociok-Khn , Michael K. Whittlesey , and Christopher G. Frost * ...

Ourida Saidi; Jameel Marafie; Araminta E. W. Ledger; Po Man Liu; Mary F. Mahon; Gabriele Kociok-Khn; Michael K. Whittlesey; Christopher G. Frost

2011-11-02T23:59:59.000Z

380

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

refining. The leading demand sector for PGMs continued to be catalysts to decrease harmful emissions refining sector; and in the fabrication of laboratory equipment. In the electronics sector, PGMs are used toward the middle of the year, then decreased. The slowly recovering global economy in 2010, compared

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

refining. The leading demand sector for PGMs continued to be catalysts to decrease harmful emissions refining sector; and in laboratory equipment, including crucibles for growing high-purity single crystals­7708, ploferski@usgs.gov] #12;121 PLATINUM-GROUP METALS Events, Trends, and Issues: The global economy continued

382

PLATINUM-GROUP METALS (Platinum, palladium, rhodium, ruthenium, iridium, osmium)  

E-Print Network (OSTI)

refining. The leading demand sector for PGMs continued to be catalysts to decrease harmful emissions refining sector; and in laboratory equipment, including crucibles for growing high-purity single crystals-7708, ploferski@usgs.gov] #12;121 PLATINUM-GROUP METALS Events, Trends, and Issues: The global economy continued

383

A Low Noise Thermometer Readout for Ruthenium Oxide Resistors  

E-Print Network (OSTI)

The thermometer and thermal control system, for the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) experiment, is described, including the design, testing, and results from the first flight of ARCADE. The noise is equivalent to about 1 Omega or 0.15 mK in a second for the RuO_2 resistive thermometers at 2.7 K. The average power dissipation in each thermometer is 1 nW. The control system can take full advantage of the thermometers to maintain stable temperatures. Systematic effects are still under investigation, but the measured precision and accuracy are sufficient to allow measurement of the cosmic background spectrum. Journal-ref: Review of Scientific Instruments Vol 73 #10 (Oct 2002)

D. J. Fixsen; P. G. A. Mirel; A. Kogut; M. Seiffert

2002-08-30T23:59:59.000Z

384

Experimental and theoretical radiative decay rates for highly excited ruthenium atomic levels and the solar abundance of ruthenium  

Science Journals Connector (OSTI)

......Atomic Data. Elsevier, Amsterdam. Harrison G. R. , McNally J. R. Jr., 1940, Phys. Rev., 58, 703. Holweger H...series in Astronomy and Astrophysics, in press. McNally J. R. Jr ., 1941, Thesis, MIT, Cambridge, MA. Meggers......

V. Fivet; P. Quinet; P. Palmeri; . Bimont; M. Asplund; N. Grevesse; A. J. Sauval; L. Engstrm; H. Lundberg; H. Hartman; H. Nilsson

2009-07-11T23:59:59.000Z

385

Monomer-dimer reaction model with asymmetric adsorption of monomer and dimer on the catalyst surface  

Science Journals Connector (OSTI)

The irreversible kinetics of the Ziff-Gulari-Barshad model in the presence of inhomogeneity on a catalyst surface is investigated by means of Monte Carlo simulation. We assume that only part of catalyst surface sites are active for surface catalytic reaction and randomly distributed on the catalyst surface. The adsorption of a O2 molecule is permitted if one site of a nearest-neighbor vacant pair is active. CO can adsorb on all vacant sites, but the adsorption probability is p(p<1) if the site is not active. In our modified model, the O-passivated phase disappears and the continuous phase transition between the O passivated and the reactive state is eliminated. We also find that the transition between the CO passivated and the reactive state is continuous if the concentration of the active sites is small, and it becomes discontinuous with increasing concentrations of active sites. Furthermore, it is shown that a hysteresis loop exists whether the CO-passivated transition is continuous or discontinuous. Our simulation results are in good agreement with many relevant experimental results and may provide an alternative explanation for the experimental observations.

Da-yin Hua and Yu-qiang Ma

2001-10-17T23:59:59.000Z

386

Computational Design of Lignin Depolymerization Catalysts  

SciTech Connect

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, for which quantum mechanical calculations can offer fundamental insights. In this work, a computational approach has been used to elucidate the reductive deconstruction pathway of a ruthenium-catalyzed system. Transition states have been computed to determine the rate-limiting steps for a catalyst that cleaves arylether linkages. Our calculations are supported by experimental synthesis and kinetic and thermodynamic measurements of the deconstruction of model lignin dimers by a ruthenium catalyst with the ultimate objective of designing new catalysts to eventually utilize lignin in biorefineries.

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

2012-01-01T23:59:59.000Z

387

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

High-Temperature Steam Electrolysis High-Temperature Steam Electrolysis High-temperature steam electrolysis (HTSE) can be used to make hydrogen for use in automotive fuel cells or other portable applications. HTSE takes advantage of solid oxide fuel cell (SOFC) technology to split steam into hydrogen and oxygen at high temperatures. This process can use the waste heat from high-temperature industrial processes to lower the need for electrical energy to split water, which gives it an advantage over conventional water electrolysis. Also, unlike steam methane reforming, the current state-of-the-art method for making hydrogen, HTSE does not release any greenhouse gases. As part of the Nuclear Hydrogen Initiative, Argonne has conducted studies of the causes of HTSE component degradation over extended operation time periods. We have developed methods for determining areas where degradation has occurred using X-ray fluorescence mapping, and X-ray Absorption Near Edge Structure (XANES) spectroscopic techniques at the Advanced Photon Source (APS). APS results were complimented by electron microscopy and energy dispersive spectroscopy, as shown in the figure.

388

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Ceramic Electrochemistry Ceramic Electrochemistry A A.Akkoyunlu, R. Koc, J. Mawdsley and J. D. Carter, "Synthesis of Submicron-Size CaB6 Powders Using Various Boron Sources," 35th International Conference and Exposition on Advanced Ceramics and Composites (ICACC'11), Daytona Beach, FL, January 23-28, 2011 B A. B. Bose, R. Shaik, and J. Mawdsley, "Optimization of the Performance of Polymer Electrolyte Fuel Cell Membrane-Electrode Assemblies: Roles of Curing Parameters on the Catalyst and Ionomer Structures and Morphology," Journal of Power Sources 182(1), 61-65 (2008) C J. D. Carter, "Status of Fuel Cell Technologies,"Electric Apparatus Service Association, Willowbrook, IL, September 13, 2011 (viewgraph presentation) J. D. Carter, "Manufacturing Fuel Cell Manhattan Project: Ceramic Fuel Cells (SOFC)," DOE H2/FC Manufacturing R&D Workshop, Washington, DC, August 11, 2011

389

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Durability Durability One of the primary challenges facing the development of polymer electrolyte fuel cells (PEFCs) for automotive and stationary power applications is the durability of the fuel cell materials. Though significant progress has been made toward achieving the technical target of 5,000 operating hours, the current reported durability status for conventional stacks is considerably shorter (~2,000 hours). Typical degradation rates for constant load conditions are 25-40 µ and can be an order of magnitude higher when operating under non-steady-state conditions prevalent in the automotive application, including load and start-stop cycling and extended time at open circuit. The observed degradation under these conditions has reversible and irreversible components with one of the most dominant contributors to irreversible degradation being loss of cathode oxygen reduction activity.

390

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

A simplified schematic showing the various alternatives and steps in the production and distribution of hydrogen A simplified schematic showing the various alternatives and steps in the production and distribution of hydrogen A simplified schematic showing the various alternatives and steps in the production and distribution of hydrogen. Hydrogen for Fuel Cells We work on the production of hydrogen for use with fuel cell systems. We have applied our knowledge of fuel cell systems, their constraints, and infrastructure needs to our research in the field. Our research projects include: Development of catalysts and reactors using autothermal reforming of alcohols and hydrocarbon fuels for on-board fuel cell systems. Reforming of infrastructure fuels (natural gas, liquefied petroleum gas, ethanol, gasoline, and diesel). Integration of fuel processor components (reformer, shift reactor,

391

Argonne Chemical Sciences & Engineering - People - Catalysis and Energy  

NLE Websites -- All DOE Office Websites (Extended Search)

Electrochemical Projects Support Electrochemical Projects Support Walter F. Podolski, Chemical Engineer and Group Leader phone: 630/252-7558, fax: 630/972-4430, podolski@anl.gov Ph.D., Chemical Engineering, Northwestern University Technical contract management and support of research, development, and demonstration of fuel-cell-powered vehicles Thomas G. Benjamin, Chemical Engineer phone: 630/252-1632, fax: 630/252-4176, e-mail: benjamin@anl.gov BS, MS Chemical Engineering, University of Connecticut MBA University of Chicago Polymer electrolyte membrane fuel cells Hydrogen storage William L. Cleary, Mechanical Engineer, Project Manager phone: 202/506-1570 e-mail: bill.cleary@ee.DOE.gov John Kopasz, Inorganic Chemist phone : 630/252-7531, fax : 630/972-4405, e-mail: kopasz@anl.gov Ph.D., Inorganic Chemistry, State University of New York at Buffalo

392

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen and Fuel Cell Materials Hydrogen and Fuel Cell Materials Summary Report, ANL-12/8, Natural Gas and Hydrogen Opportunities Workshop, Argonne National Laboratory, October 18-19, 2011 TM/N/C Cathode Catalyst for in Li-Air Battery Application, 5th International Conference on Polymer Batteries and Fuel Cells (PBFC-5), Argonne, IL, August 1-5, 2011 (poster presentation) Transition Metal--Nitrogen--Carbon Composite as Cathode Catalyst for in Li-air Battery Application, 5th International Conference on Polymer Batteries and Fuel Cells (PBFC-5), Argonne, IL, August 1-5, 2011 (poster presentation) Fundamental Studies of Platinum Electrocatalyst Degradation, 5th International Conference on Polymer Batteries and Fuel Cells (PBFC-5), Argonne, IL, August 1-5, 2011 (poster presentation)

393

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Degradation Degradation One of the primary challenges facing the development of polymer electrolyte fuel cells (PEFCs) for automotive and stationary power applications is the durability of the fuel cell materials. Though significant progress has been made toward achieving the technical target of 5,000 operating hours, the current reported durability status for conventional stacks is considerably shorter (~2,000 hours). Typical degradation rates for constant load conditions are 25-40 µ and can be an order of magnitude higher when operating under non-steady-state conditions prevalent in the automotive application, including load and start-stop cycling and extended time at open circuit. The observed degradation under these conditions has reversible and irreversible components with one of the most dominant contributors to irreversible degradation being loss of cathode oxygen reduction activity.

394

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalytic Removal of Oxides of Nitrogen from Diesel Exhaust Streams Catalytic Removal of Oxides of Nitrogen from Diesel Exhaust Streams Nox removal One of the planet's major pollutants, nitrogen oxides (NOx) are formed in all high temperature fuel-air flames, and so they are a particular emissions problem for diesel engines. Although diesel-fueled engines emit very small amounts of carbon monoxide (CO) and hydrocarbons (HCs), they do, however, release relatively high amounts of NOx and particulate matter (PM) or soot--the emissions that lead to acid rain, smog, and poor health conditions. Thus, removing NOx from emission streams has become a global concern. Argonne researchers have developed an innovative diesel DeNOx catalyst technology that provides industry with a totally passive, easy-to-use system for removing NOx from exhaust streams. Vehicle drivers do not need

395

Muon catalysis for energy production by nuclear fusion  

Science Journals Connector (OSTI)

... mesic molecular ion (dt?-)+. It takes a short time tf for an exothermic nuclear fusion reaction d + t 4 He-hn to occur. When the probability is tdt, ...

Yu. V. Petrov

1980-06-12T23:59:59.000Z

396

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

E-Print Network (OSTI)

and interfaces for a host of sustainable chemical processes that provide renewable (or cleaner) fuels the next generation of catalysts, separation processes, gas and liquid storage technologies, and environmental remediation methods. These materials and technologies are at the heart of industrial processes

Li, Mo

397

Lewis base catalysis of bromo- and iodolactonization, and cycloetherification  

Science Journals Connector (OSTI)

...behaved quite differently. Whereas tetrahydrothiophene (entry 11) was equipotent with...the divalent chalcogen donors tetrahydrothiophene (entry 11) and (PhSe) 2 (entry...ca. 20 times less reactive than tetrahydrothiophene, the pnictogens (Me 2 N) 3 P...

Scott E. Denmark; Matthew T. Burk

2010-01-01T23:59:59.000Z

398

The Role of CO2 Reduction Catalysis in Carbon Capture  

Science Journals Connector (OSTI)

In addition to the algae-mediated process discussed in Chap.7, to generate hydrocarbon-based fuels and useful chemicals from CO2, it is also possible to use electrochemical and photocatalytic processes to carry ...

Prof. Jennifer Wilcox

2012-01-01T23:59:59.000Z

399

Some thoughts on the production of muons for fusion catalysis  

Science Journals Connector (OSTI)

For muon-catalyzed fusion to be of practical interest, a very efficient means of producing muons must be found. We describe here some schemes for producing muons that may be more energy efficient than any heretof...

George Chapline; Ralph Moir

1986-09-01T23:59:59.000Z

400

Lignin valorization through integrated biological funneling and chemical catalysis  

Science Journals Connector (OSTI)

...Beckham a,b,2 a. National Bioenergy Center, National Renewable...Gregg T. Beckham, National Bioenergy Center, National Renewable...Syringol* * Known from previous literature (13- 23) Table S2...Lignocellulosic Feedstocks. 1. Review and Description of Methods...

Jeffrey G. Linger; Derek R. Vardon; Michael T. Guarnieri; Eric M. Karp; Glendon B. Hunsinger; Mary Ann Franden; Christopher W. Johnson; Gina Chupka; Timothy J. Strathmann; Philip T. Pienkos; Gregg T. Beckham

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Theoretical Study on Catalysis by Protein Enzymes and Ribozyme  

NLE Websites -- All DOE Office Websites (Extended Search)

are likely to occur, while the direct intra-substrate proton transfer mechanism (in green) is energetically unfavorable due to the presence of His95 in the active site....

402

Incorporating Green Chemistry Principles in Heterogeneous Catalysis Operations.  

E-Print Network (OSTI)

??Many commercial processes for the production of chemicals involve harsh organic solvents as well as numerous by-products that are detrimental to the environment. For many (more)

Bacik, Deborah

2011-01-01T23:59:59.000Z

403

Lignin valorization through integrated biological funneling and chemical catalysis  

Science Journals Connector (OSTI)

...vanillin and lignosulfonates, markets that would be swamped by orders...a broad range of potential markets, both for small- and large-volume...range of jet (C8-C16) and diesel grade (C8-C21) fuels...electric, fuel cell), thus a market for mcl-PHAs derived from...

Jeffrey G. Linger; Derek R. Vardon; Michael T. Guarnieri; Eric M. Karp; Glendon B. Hunsinger; Mary Ann Franden; Christopher W. Johnson; Gina Chupka; Timothy J. Strathmann; Philip T. Pienkos; Gregg T. Beckham

2014-01-01T23:59:59.000Z

404

Polyisobutylene as a Polymer Support for Homogeneous Catalysis  

E-Print Network (OSTI)

to one (-OCH 3 , -OH termini) or two (two -OH termini) equivalents of ligand or catalyst per mole of polymer. Linkers as shown in eq. 2 are not required but are sometimes used. MeO O OH n O or HO O OH nanioic polymerization MeO O OH n HO O OH n Me... and the SPhos Pd catalyst had a TOF that was 20-fold larger than that of a similar ligated Pd catalyst on SiO 2 . O(CH 22 O) P(Cy) 2 OMe MeO (Cy) 2 P 9 HO PH(Cy) 2 h 70 o C, 12 h l - Cs 2 O 3 , H 3 CN Ms(CH 22 O) n Ms n Cl N H O + 2 mol% Pd(OAc) 2...

Hongfa, Chayanant

2010-01-14T23:59:59.000Z

405

University of Delaware | Catalysis Center for Energy Innovation...  

NLE Websites -- All DOE Office Websites (Extended Search)

Fuel Cells Schematic for a large-scale DCFC system based on molten Sb anodes. CCEI's technology is based on electrolytes that are ceramic oxygen-ion conductors, such as cubic...

406

University of Delaware | Catalysis Center for Energy Innovation...  

NLE Websites -- All DOE Office Websites (Extended Search)

Sugars to Furans Converting sugars to high-value intermediates. CCEI introduced an iconic technology for the isomerization of aldoses to ketoses production via Sn-beta zeolite and...

407

Modeling Acid and Cationic Catalysis on the Reactivity of Duocarmycins  

Science Journals Connector (OSTI)

Mauro Freccero * and Remo Gandolfi ... Modica, Emilia; Zanaletti, Riccardo; Freccero, Mauro; Mella, Mariella ... Zanaletti, Riccardo; Freccero, Mauro ...

Mauro Freccero; Remo Gandolfi

2005-08-05T23:59:59.000Z

408

Generation of Acylnitroso Dienophiles:? A Study of Metal Catalysis  

Science Journals Connector (OSTI)

Mauro F. A. Adamo * and Simone Bruschi ... Adamo, Mauro F. A.; Donati, Donato; Duffy, Eleanor F.; Sarti-Fantoni, Piero ... Adamo, Mauro F. A.; Baldwin, Jack E.; Adlington, Robert M. ...

Mauro F. A. Adamo; Simone Bruschi

2007-02-28T23:59:59.000Z

409

Phase selectively soluble polymer supports to facilitate homogeneous catalysis  

E-Print Network (OSTI)

Soluble polymers that have phase selective solubility are useful in synthesis because they simplify purification and separation. Such selectively soluble polymers simplify catalyst, reagent, and product recovery and enable the use of Green chemistry...

Ortiz-Acosta, Denisse

2009-05-15T23:59:59.000Z

410

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network (OSTI)

of deoxygenation chemistry on metal carbide catalysts. Specifically, the talk will include a discussion of: (i

411

Plasmonic enhancement of catalysis and solar energy conversion.  

E-Print Network (OSTI)

??This thesis is dedicated to exploring the potential applications of plasmonic metal nanoparticles and understanding their fundamental enhancement mechanisms. Photocatalysis and solar energy conversion are (more)

Hung, Wei Hsuan

2011-01-01T23:59:59.000Z

412

Catalysis of 6? Electrocyclizations & Catalytic Disproportionation of Lignin Model Compounds  

E-Print Network (OSTI)

J. D. ; McNally, T. J. Lignin. In Kirk-Othmer EncyclopediaK. ; Gellerstedt, G. Lignin. In Analytical Methods in Woodof a 1-phenylpropane-1,3-diol lignin model compound via ?-

Bishop, Lee

2010-01-01T23:59:59.000Z

413

Frontiers in Catalysis Science and Engineering Materials Science  

E-Print Network (OSTI)

, it is imperative to develop new processes for effective use of energy and to develop sustainable and clean energy in synthesizing novel metal oxide nanostructures for energy harvest and storage will also be discussed. More info Professor, Department of Chemistry & Biochemistry Abstract Energy is not only the driver for improving

414

Lignin valorization through integrated biological funneling and chemical catalysis  

Science Journals Connector (OSTI)

...catalytic upgrading. There is significant versatility and modularity in each step, enabling adaptation to different biomass feedstocks and desired fuel and chemical portfolios, thus holding promise toward industrial application. Namely, lignin depolymerization...

Jeffrey G. Linger; Derek R. Vardon; Michael T. Guarnieri; Eric M. Karp; Glendon B. Hunsinger; Mary Ann Franden; Christopher W. Johnson; Gina Chupka; Timothy J. Strathmann; Philip T. Pienkos; Gregg T. Beckham

2014-01-01T23:59:59.000Z

415

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 of the selectivity for H+ vs. CO2 reduction pathways by UV-Vis and FTIR stopped flow kinetics studies will also

416

Charge Transfer and Catalysis at the Metal-Support Interface  

E-Print Network (OSTI)

a sapphire window and consisted of a thin film of either SiO2 thin film (50 nm) was deposited on the sapphire window bywindow containing the Pt nanoparticles supported on SiO 2 or TiO 2 thin films.

Baker, Lawrence Robert

2012-01-01T23:59:59.000Z

417

Light-driven uncoupling of nitrogenase catalysis from ATP hydrolysis  

E-Print Network (OSTI)

C. , Tezcan, F. A. , 2010. ATP- and iron-protein-independentL. E. , Tezcan, F. A. , 2012. ATP-uncoupled, six-electronRuBP activity under ATP turnover conditions. .

Roth, Lauren E.

2012-01-01T23:59:59.000Z

418

Tensor Rank and Stochastic Entanglement Catalysis for Multipartite Pure States  

E-Print Network (OSTI)

The tensor rank (also known as generalized Schmidt rank) of multipartite pure states plays an important role in the study of entanglement classifications and transformations. We employ powerful tools from the theory of homogeneous polynomials to investigate the tensor rank of symmetric states such as the tripartite state $\\ket{W_3}=\\tfrac{1}{\\sqrt{3}}(\\ket{100}+\\ket{010}+\\ket{001})$ and its $N$-partite generalization $\\ket{W_N}$. Previous tensor rank estimates are dramatically improved and we show that (i) three copies of $\\ket{W_3}$ has rank either 15 or 16, (ii) two copies of $\\ket{W_N}$ has rank $3N-2$, and (iii) $n$ copies of $\\ket{W_N}$ has rank O(N). A remarkable consequence of these results is that certain multipartite transformations, impossible even probabilistically, can become possible when performed in multiple copy bunches or when assisted by some catalyzing state. This effect is impossible for bipartite pure states.

Lin Chen; Eric Chitambar; Runyao Duan; Zhengfeng Ji; Andreas Winter

2010-11-10T23:59:59.000Z

419

Catalysis in chemistry and biochemistry: summary and concluding remarks  

Science Journals Connector (OSTI)

...elaborate network of hydrogen bonds is held responsible...N-HS and other hydrogen bonds) in promoting...absence or presence of hydrogen. Vibrational spectroscopy...alternative catalysts for fuel cells. The presentation...fuel efficiency in cars with, for example...

2005-01-01T23:59:59.000Z

420

Fundamental studies of reactive intermediates in homogeneous catalysis  

SciTech Connect

The studies involve dissociation of Fe(CO){sub n}{sup {minus}}, Ni(CO){sub n}{sub {minus}}, and other carbonyl anions; decarboxylation of (CO){sub 4}FeCOOH{sup {minus}} to form CO{sub 2} and (CO){sub 4}FeH{sup {minus}} in the water gas shift reaction; gas-phase bimolecular reactions of carbonyl anions and O{sub 2}; reaction of O{sub 2} with CpMn(CO){sub 2}{sup {minus}}; gas-phase chemistry of fullerene anions; and gas-phase thermochemistry of bicarbonate ion, bisulfite ion, and their conjugate acids (sulfonate ion was produced).

Not Available

1993-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

JOURNAL OF CATALYSIS 178, 499510 (1998) ARTICLE NO. CA982161  

E-Print Network (OSTI)

clays in which divalent cations within brucite-like layers are replaced by trivalent cations brucite sheets. The general formula for these ma- terials is [MII 1-x MIII x (OH)2]x+ (Ax/n)n- · m H2O

Iglesia, Enrique

422

2013 Catalysis Center for Energy Innovation * University of...  

NLE Websites -- All DOE Office Websites (Extended Search)

wood or other biomass sources and feed them directly into their process, Catalytic Fast Pyrolysis (CFP). Within the reactor, particles of biomass are rapidly heated within...

423

Fuel Synthesis Catalysis Laboratory (Fact Sheet), NREL (National...  

NLE Websites -- All DOE Office Websites (Extended Search)

areas of emphasis are hydrocarbon synthesis from biomass- derived syngas and pyrolysis vapors. Many other catalyst systems can be studied by making minor system modifications. The...

424

University of Delaware | Catalysis Center for Energy Innovation...  

NLE Websites -- All DOE Office Websites (Extended Search)

sample. The next generation of biofuels will be produced by high-temperature (>1000 F) pyrolysis or gasification of lignocellulosic biomass. At these temperatures, large...

425

Transition-metal catalysis of cyclocarbonylation and cycloisomerization reactions  

E-Print Network (OSTI)

Chapter 1. The asymmetric Pauson-Khand cyclization of nitrogen-containing enynes using carbon monoxide and a catalytic amount of (EBTHI)TiMe2 was examined. The influence of the nitrogen substituent and the concentration ...

Sturla, Shana Jocette, 1975-

2001-01-01T23:59:59.000Z

426

Charge Transfer and Catalysis at the Metal Support Interface  

E-Print Network (OSTI)

carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titaniumTitanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide ..Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

Baker, Lawrence Robert

2014-01-01T23:59:59.000Z

427

Charge Transfer and Catalysis at the Metal-Support Interface  

E-Print Network (OSTI)

carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titaniumTitanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide ..Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

Baker, Lawrence Robert

2012-01-01T23:59:59.000Z

428

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network (OSTI)

Titanium Oxide as an Electronically Active Support for PlatinumintheCatalyticOxidationofCarbonMonoxide. . . . . . . . . . . . . carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titaniumTitaniumOxideasanElectronicallyActive SupportforPlatinumin theCatalyticOxidationofCarbon Monoxide

Hervier, Antoine

2012-01-01T23:59:59.000Z

429

Mechanism of iron catalysis of carbon monoxide decomposition in refractories  

SciTech Connect

The authors discuss the catalytic effects of selected iron phases (metals, oxides, sulfides, and carbides) on the Boudouard reaction studied in an effort to more fully understand the disintegration of refractories when exposed to CO for long periods of time. It was found that active Fe atoms generated from the reduction of the iron oxides, especially {alpha}-Fe/sub 2/O/sub 3/, are the actual catalysts for the Boudouard reaction. The catalytic process confirmed by thermodynamic calculations, kinetic data, and X-ray diffraction data, consists of adsorption and decomposition of CO simultaneously forming carbides of iron. The chemisorption and subsequent decomposition of the iron carbides, rather than diffusion, constitute the rate-controlling process for carbon deposition.

Xu, M.W.P.; Brown, J.J. Jr. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (USA). Dept. of Materials Engineering)

1989-01-01T23:59:59.000Z

430

Alkali monolayers on transition metal surfaces: electronic promotion in catalysis  

SciTech Connect

Potassium monolayers on the platinum (111) crystal surface were studied most extensively. Ultraviolet photoelectron spectroscopy showed a large decrease in the work function of the surface when potassium was adsorbed. The heat of desorption of potassium decreased with increasing coverage. Low energy electron diffraction (LEED) showed that potassium forms hexagonal (close packed) overlayer structures. The effects of potassium on the chemisorption of various small molecules on Pt(111) were studied. Oxygen and nitric oxide were readily adsorbed and dissociated by potassium, forming stable potassium-oxide complexes on the surface. Adsorption heat of carbon monoxide on Pt(111) increased with potassium coadsorption. High resolution electron energy loss spectroscopy showed that the carbon-oxygen bond of adsorbed carbon monoxide was weakened by potassium. Adsorption heat of benzene, however, was decreased by coadsorbed potassium. A molecular orbital explanation was given to explain the effects of potassium. CO hydrogenation reactions performed on metal foils showed that the addition of alkali adlayers tends to decrease the overall rate of reaction. Changes in selectivity were noted, shifting the product distribution in favor of higher molecular weight species and from alkanes to alkenes.

Garfunkel, E.

1983-08-01T23:59:59.000Z

431

Lignin valorization through integrated biological funneling and chemical catalysis  

Science Journals Connector (OSTI)

...polysaccharide-derived fuels and chemicals is heat and power. Here, we demonstrate...the vessel jackets, with a heat ramp of ?2 h. After 30 min at...catalytically converted to hydrocarbons over a platinum-rhenium (Pt-Re) catalyst...Farrell RL ( 1987 ) Enzymatic combustion: The microbial degradation...

Jeffrey G. Linger; Derek R. Vardon; Michael T. Guarnieri; Eric M. Karp; Glendon B. Hunsinger; Mary Ann Franden; Christopher W. Johnson; Gina Chupka; Timothy J. Strathmann; Philip T. Pienkos; Gregg T. Beckham

2014-01-01T23:59:59.000Z

432

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network (OSTI)

is a versatile platform chemical for sustainable production of alternative chemicals based on biomass feedstock

433

Microwaves and Chemistry: The Catalysis of an Exciting Marriage  

E-Print Network (OSTI)

of microwave catalysts employed. We should emphasize that water as a reactant is in the adsorbed state Oil the catalyst's sUlfaces. Indeed, both the hydrocarbon and water are adsorbed on the surfaces and the primary reaction of the oxidation takes place.... For this reason, it is important to realize that the methods of introducing and maintaining the concentrations of adsorbed water on the surfaces effectively control the efficiency and the selectivity of the oxidation products. This is equally true...

Wan, J.

434

Starch-Binding Domain Affects Catalysis in Two Lactobacillus ?-Amylases  

Science Journals Connector (OSTI)

...Starch. Amylase activity...starch, amylose, amylopectin, or corn...starch. Amylase activity...starch, amylose, amylopectin, or raw...B) a-amylases as measured...and 63C. , amylose; , soluble...starch; , amylopectin; , corn...

R. Rodrguez-Sanoja; B. Ruiz; J. P. Guyot; S. Sanchez

2005-01-01T23:59:59.000Z

435

8.3 Rotational Catalysis by F1-ATPase  

Science Journals Connector (OSTI)

F1-ATPase, a water-soluble portion of ATP synthase, is a fully reversible rotary molecular machine in which a central ? subunit rotates inside a cylinder made of three ? and three ? subunits alternately arranged. This motor rotates counterclockwise by hydrolyzing ATP in three catalytic sites but synthesizes ATP when forced to rotate clockwise by an external force. Single-molecule studies have revealed how the chemical reactions that occur in the three catalytic sites are coupled to mechanical rotation.

K. Adachi; T. Nishizaka; K. Kinosita Jr.

2012-01-01T23:59:59.000Z

436

Catalysis by Design: Bridging the Gap between Theory and Experiments  

Energy.gov (U.S. Department of Energy (DOE))

Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's (DOE) Office of FreedomCAR and Vehicle Technologies (OFCVT).

437

Hangman Catalysis for Photo- and Photoelectro- Chemical Activation of Water  

SciTech Connect

The focus of this DOE program is solar fuels specifically the chemistry for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) from water and the oxygen reduction reaction (ORR) to water These three reactions are at the heart of renewable energy conversion. The bond-making and bond-breaking chemistry that underpins these transformations is not well understood. We are developing insight into such chemistry by creating a series of ligand constructs that poise an acid-base functionality over a redox active metal platform. These hangman ligands utilize the acid-base functionality to form a secondary coordination sphere that can assist proton movement and facilitate substrate assembly and activation within the molecular cleft. The grant period funding cycle focused on synthesis and reactivity of hangman porphyrins and corroles for HER, OER and ORR.

Nocera, Daniel

2014-04-15T23:59:59.000Z

438

Catalysis of 6? Electrocyclizations & Catalytic Disproportionation of Lignin Model Compounds  

E-Print Network (OSTI)

Chem. Int. Ed. 2009, 48, 9975. Parker, K. A. ; Wang, Z. Org.Chem. Int. Ed. 2009, 48, 9975. Vicario, J. L. ; Badia, D.

Bishop, Lee

2010-01-01T23:59:59.000Z

439

BERKELEY CATALYSIS CENTER Monday, October 10, 2005 4 pm  

E-Print Network (OSTI)

synthesis of sophisticated mixed ceramic and noble metal composite nanoparticles. These materials seemed, Au or Ag) on ceramic (TiO2, SiO2 and Al2O3) nanoparticles will be shown. For example, the open-ray absorbing matrix. The structural identification at such small concentration turned out to be important since

Iglesia, Enrique

440

RG analysis of magnetic catalysis in dynamical symmetry breaking  

SciTech Connect

We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the {beta}-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs.

Hong, Deog Ki [Pusan National Univ., (Korea). Dept. of Physics]|[Florida Univ., Gainesville, FL (United States); Kim, Youngman [Hanyang Univ., Seoul (Korea). Dept. of Physics

1996-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Quantum Catalysis of Magnetic Phase Transitions in a Quantum Simulator  

E-Print Network (OSTI)

We control quantum fluctuations to create the ground state magnetic phases of a classical Ising model with a tunable longitudinal magnetic field using a system of 6 to 10 atomic ion spins. Due to the long-range Ising interactions, the various ground state spin configurations are separated by multiple first-order phase transitions, which in our zero temperature system cannot be driven by thermal fluctuations. We instead use a transverse magnetic field as a quantum catalyst to observe the first steps of the complete fractal devil's staircase, which emerges in the thermodynamic limit and can be mapped to a large number of many-body and energy-optimization problems.

Philip Richerme; Crystal Senko; Simcha Korenblit; Jacob Smith; Aaron Lee; Rajibul Islam; Wesley C. Campbell; Christopher Monroe

2013-03-27T23:59:59.000Z

442

Engineering enzyme specificity by "substrate-assisted catalysis"  

Science Journals Connector (OSTI)

...acid. Sequences are designated by the single letter amino acid code, and arrows indicate potential His P2 cleavage sites. ACIH...Ca-C1-Cy-C8). The hydrogen bond angles [Oy(Ser)-H8(Ser)-Ns2(His)] were calculated from the measured C13(Ser)-Oy...

P Carter; JA Wells

1987-07-24T23:59:59.000Z

443

Catalysis of concerted reactions by antibodies: the Claisen rearrangement  

Science Journals Connector (OSTI)

...D Hilvert S H Carpenter K D Nared M T Auditor Department of Molecular Biology, Research...KAREN D. NARED, AND MARIA-TERESA M. AUDITOR Department of Molecular Biology, Research...accomplished through the use of binding energy to induce strain into the starting material...

D Hilvert; S H Carpenter; K D Nared; M T Auditor

1988-01-01T23:59:59.000Z

444

Catalysis of concerted reactions by antibodies: the Claisen rearrangement  

Science Journals Connector (OSTI)

...Carpenter K D Nared M T Auditor Department of Molecular...AND MARIA-TERESA M. AUDITOR Department of Molecular...NaCl for 1-2 hr at room temperature, followed...were obtained by direct computer fit of the data to the...through the use of binding energy to induce strain into...

D Hilvert; S H Carpenter; K D Nared; M T Auditor

1988-01-01T23:59:59.000Z

445

CATALYSIS AND INHIBITION OF MYCOBACTERIUM TUBERCULOSIS METHIONINE AMINOPEPTIDASE  

E-Print Network (OSTI)

-3 Domain architechture of Methionine Aminopeptidase....................................12 Figure 1-4 Crystal structures of EcMetAP I,PfMetAP IIa and HsMetAP IIb ...................12 Figure 1-5 The dinuc lear metal centers and the amino acid residues... in EcMetAP I, PfMetAP IIa and HsMetAP IIb........................................................................14 Figure 1-6 Proposed reaction mechanism of dimetalated EcMetAP I ..............................16 Figure 1-7 Proposed reaction...

Lu, Jingping

2010-06-04T23:59:59.000Z

446

Energy conversion catalysis using semiconducting transition metal cluster compounds  

Science Journals Connector (OSTI)

... semiconducting materials that provide a high density of transition metal d-states bordering the forbidden energy region (d-band semiconductors). During a detailed study of RuS2, the best material ... for photo-induced evolution of oxygen3, it became apparent that ~0.5 eV of energy per transferred electron is lost in the course of trapping positive charge carriers in the ...

N. Alonso Vante; H. Tributsch

1986-10-02T23:59:59.000Z

447

Catalysis of Nuclear Reactions between Hydrogen Isotopes by ?- Mesons  

Science Journals Connector (OSTI)

The mechanism by which negative ? mesons catalyze nuclear reactions between hydrogen isotopes is studied in detail. The reaction rate for the process (p+d+?-?He3+?-+5.5 Mev), observed recently by Alvarez et al., is calculated and found to be in accord with the available data. The ?- meson binds two hydrogen nuclei together in the ?-mesonic analog of the ordinary H2+ molecular ion. In their vibrational motion the nuclei have a finite, although small, probability of penetrating the Coulomb barrier to zero separation where they may undergo a nuclear reaction. The intrinsic reaction rates for other, more probable, reactions are also estimated. The results are ?0.3106 sec-1 for the observed p-d reaction, ?0.71011 sec-1 for the d-d reaction, and ?0.41013 sec-1 for the d-t reaction. For the reaction observed by Alvarez rough estimates are made of the partial widths for nonradiative and radiative decay of the excited He3 nucleus. The ejection of the ?- meson by "internal conversion" seems somewhat less likely. Speculations are made on the release of useful amounts of nuclear energy by these catalyzed reactions. The governing factors are not the intrinsic reaction rate once the molecule is formed, but rather the time spent (?10-8 sec) by the ?- meson between the breakup of one molecule and the formation of another and the loss of ?- mesons in "dead-end" processes. These factors are such that practical power production is unlikely. In liquid deuterium, each ?- meson will catalyze only ?10 reactions in its lifetime, while for the d-t process it will induce ?100 disintegrations. A longer lived particle will not be able to catalyze appreciably more reactions.

J. D. Jackson

1957-04-15T23:59:59.000Z

448

Light-driven uncoupling of nitrogenase catalysis from ATP hydrolysis  

E-Print Network (OSTI)

77 Figure 4.1. Genes in the major nif cluster from A.plasmids from digested nif gene inserts. Figure 4.5. Two-82 The Nif Gene

Roth, Lauren E.

2012-01-01T23:59:59.000Z

449

Progress in transition metal-based enantioselective catalysis  

E-Print Network (OSTI)

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 ...

Arp, Forrest O

2008-01-01T23:59:59.000Z

450

Catalysis Today 88 (2004) 139151 Hydrodehalogenation with sonochemically prepared  

E-Print Network (OSTI)

to the formation of even more toxic secondary pollutants such as polyhalogenated dioxins and fu- rans [7­11]. Emissions from incineration plants are a major contributor to the 3000 kg of polyhalogenated dioxins

Suslick, Kenneth S.

451

Phase-Transfer Catalysis: Polymerization and Polymer Modification  

Science Journals Connector (OSTI)

Early in the development of small molecule synthesis by phase-transfer catalytic techniques, the principles of PTC were applied to various aspects of polymer research. Indeed, during the last 15 years an eno...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

452

Phase-Transfer Catalysis-Transition Metal Cocatalyzed Reactions  

Science Journals Connector (OSTI)

Transition metals are active catalysts for a variety of organic reactions. Sometimes they are also useful in conjunction with phase-transfer catalysts, particularly when hydroxide anions and other inorganic sp...

Charles M. Starks; Charles L. Liotta; Marc E. Halpern

1994-01-01T23:59:59.000Z

453

Frontiers in Catalysis Science and Engineering Seminar Series  

E-Print Network (OSTI)

-Surface Interactions: Ab Initio Energies and Entropies Presented by... Prof. Dr. Joachim Sauer � Institut f�r Chemie (H- chabazite). http://www.chemie.hu-berlin.de/forschung/quantenchemie/Group Hosted by: Johannes

454

Continuous Isosorbide Production From Sorbitol Using Solid Acid Catalysis  

SciTech Connect

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.

Williamson, R.; Holladay,J.; Jaffe, M.; Brunelle, D.

2006-09-29T23:59:59.000Z

455

Ribozyme Catalysis via Orbital Steering William G. Scott  

E-Print Network (OSTI)

and uncatalyzed reactions take place via an SN2(P) mechanism in which the attacking nucleophile, the ionized 2H reac- tion is self-cleavage of the phosphodiester back- bone. This reaction takes place via a process at the site of cleavage.1 This reaction is catalyzed by four of the eight known natural ribozymes, i

Scott, William

456

University of Delaware | Catalysis Center for Energy Innovation...  

NLE Websites -- All DOE Office Websites (Extended Search)

Biomass Upgrade Upgrade of furans via hydrodeoxygenation technology. Bio-oil and oxygenated intermediates derived from sugars are oxygen rich. In order to be transformed to fuels...

457

Synthesis of Benzazoles by Hydrogen-Transfer Catalysis  

Science Journals Connector (OSTI)

A. John Blacker *, Mohamed M. Farah , Michael I. Hall , Stephen P. Marsden *, Ourida Saidi and Jonathan M. J. Williams * ...

A. John Blacker; Mohamed M. Farah; Michael I. Hall; Stephen P. Marsden; Ourida Saidi; Jonathan M. J. Williams

2009-04-08T23:59:59.000Z

458

Catalysis of 6? Electrocyclizations & Catalytic Disproportionation of Lignin Model Compounds  

E-Print Network (OSTI)

represent 86% of the total global energy consumed in 2006.source for 1% of the total global energy consumed in 2006, 1the total sustainable global biomass energy production

Bishop, Lee

2010-01-01T23:59:59.000Z

459

University of Delaware | Catalysis Center for Energy Innovation  

NLE Websites -- All DOE Office Websites (Extended Search)

as an Energy Frontier Research Center in 2009 by a grant from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. The center's research focus is...

460

University of Delaware | Catalysis Center for Energy Innovation...  

NLE Websites -- All DOE Office Websites (Extended Search)

Green Aromatics Transition state for the Diels-Alder reaction of 2,5-dimethylfuran and ethylene in zeolite LiY Most polymers and plastics require six-carbon ring structures. Sugars...

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Porous MetalOrganic Frameworks for Heterogeneous Biomimetic Catalysis  

Science Journals Connector (OSTI)

Homogeneous artificial metalloporphyrins can undergo catalytic deactivation via suicidal self-oxidation, which lowers their catalytic activity and sustainability relative to their counterparts in Nature. ... The 3D structure of [Zn2(HCOO)(FeIII(H2O)-TCPP)]guest (7) is made up of layered network of FeIII-TCPP connected with binuclear Zn2(COO)4 paddle-wheel SBUs, and further linked by formate pillars to homogeneously coordinate with Zn2(COO)4 SBUs (Figure 4a). ... pillar linker DPNI to form a three-dimensional porous structure. ...

Min Zhao; Sha Ou; Chuan-De Wu

2014-02-06T23:59:59.000Z

462

Heterogeneous Catalysis DOI: 10.1002/anie.201200699  

E-Print Network (OSTI)

- cial processes unattractive. Several non-noble metal materi- als, such as transition-metal chalcogenides,[2] carbides,[3] and complexes[4] as well as metal alloys[5] have been widely investigated. Nitrides of early transition-metals have been shown to have excellent catalytic activities in a variety

Frenkel, Anatoly

463

Density Functional Theory in Surface Chemistry and Catalysis  

SciTech Connect

Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.

Norskov, Jens

2011-05-19T23:59:59.000Z

464

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen Storage Hydrogen Storage Hydrogen Storage Scott Kirklin, a co-op student researcher, closely examines a polymer sample before characterizing its surface structure. The capacity of on-board hydrogen storage is critical to the development of hydrogen-powered fuel cell vehicles. To be practical, the 2010 performance targets of the hydrogen storage system set by the U.S. Department of Energy (DOE) include a gravimetric capacity of at least 0.06 kg H2/kg and a volumetric capacity of 0.045 kg H2/L at ambient temperature. Furthermore, the adsorbent cost must be less than $4/kWh. These requirements pose significant challenges to the storage material development. Argonne, in collaboration with the University of Chicago (U of C), is addressing these challenges by exploring a new class of hydrogen adsorbent,

465

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Production of Hydrogen using Copper-Chlorine Cycle Production of Hydrogen using Copper-Chlorine Cycle In view of the upcoming hydrogen economy, Argonne researchers are studying thermochemical cycles to determine their potential to produce hydrogen effectively with respect to energy usage and cost. Most emphasis has been placed on baseline sulfur cycles, though a small effort is currently ongoing for alternative cycles, one of which is the copper chloride (Cu-Cl) cycle. The chemistry of this cycle is illustrated in the figure below. Heat/electricity and water are the only inputs, while oxygen and hydrogen are the only products. All of the chemicals are recycled. Production of hydrogen using copper-chlorine cycle diagram The Copper Chloride Cycle Researcher Magali Ferrandon sets up a copper-chloride cycle experiment

466

Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith  

DOE Patents (OSTI)

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.

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

467

The Interplay of Catalysis and Toxicity by Amyloid  

E-Print Network (OSTI)

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

Miranker, Andrew

468

Catalysis of 6? Electrocyclizations & Catalytic Disproportionation of Lignin Model Compounds  

E-Print Network (OSTI)

groups. 13 Finally, the organosolv process extracts ligninWhile a 70% conversion of organosolv lignin to alkanols such

Bishop, Lee

2010-01-01T23:59:59.000Z

469

Facile Dimer Synthesis for DNA-Binding Polyamide Ligands  

Science Journals Connector (OSTI)

Pyrrole-imidazole polyamide ligands are highly sequence specific synthetic DNA-binding ligands that bind with high affinity. ... Regulation of gene expression by synthetic DNA-binding ligands ...

Modi Wetzler; David E. Wemmer

2010-07-13T23:59:59.000Z

470

A structural investigation of the chemokine dimer interface  

E-Print Network (OSTI)

plasmid) were added. PCR products were purified by gel electrophorcsis followed by cleanup with a Qiagen Gel Extraction kit Purified PCR products were then digcstcd in a 31 Eco R I P lac Nsi I sol I on M13 Pst I Hind ill cl oodi 1-132 X los I... by a lac promoter (dark arrow at I:00) This figure is courtesy of Dr. Jim Hu of Texas A&M University. . 32 20pl mixture containing 141tl purified DNA, 21tI New England Biolabs BamH I Buffer, 21tl New England Biolabs 10X BSA buffer, I ltl New England...

Hayes, Garret Lance

2013-02-22T23:59:59.000Z

471

How Magnetic Dimers Interact to Create Long-Range Order  

NLE Websites -- All DOE Office Websites (Extended Search)

distortions. The x-ray data also enabled the researchers to pinpoint the phase transition temperature as being 122 K. Complementary high-resolution powder neutron diffraction...

472

Behavior of Soap Films Stabilized by a Cationic Dimeric Surfactant  

Science Journals Connector (OSTI)

A. Espert , R. v. Klitzing , P. Poulin , A. Colin ,* R. Zana , and D. Langevin ... (47)?Poulin, P.; Bibette, J. Phys. ... Poulin, P.; Bibette, J. ...

A. Espert; R. v. Klitzing; P. Poulin; A. Colin; R. Zana; D. Langevin

1998-07-03T23:59:59.000Z

473

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

E-Print Network (OSTI)

-Infrared Electrochromic Properties Fengkun Chen, Jie Zhang, Xinhua Wan* Introduction Organic materials that respond, but relatively low applied pressure is preferred for many applications in our daily life. Electrochromic (EC lengths. Their liquid crystalline behaviors, and piezochromic and near-infrared electrochromic properties

Wan, Xin-hua

474

Benzene Dimer DOI: 10.1002/anie.201300653  

E-Print Network (OSTI)

** Melanie Schnell,* Undine Erlekam, P. R. Bunker, Gert von Helden, Jens-Uwe Grabow, Gerard Meijer, and Ad

475

Simulating the Self-Assembly of Gemini (Dimeric) Surfactants  

Science Journals Connector (OSTI)

...aggregates formed by surfactant molecules are known...clean-ing, and soil cleanup. Molecular...Simulations at different surfactant concentrations indicate...understanding of surfactant self-assembly...removal of stains in a washing machine (1...surfactants for soil cleanup and enhanced...

S. Karaborni; K. Esselink; P. A. J. Hilbers; B. Smit; J. Karthauser; N. M. van Os; R. Zana

1994-10-14T23:59:59.000Z

476

Coherence oscillations between weakly coupled Bose-Hubbard dimers  

E-Print Network (OSTI)

We study theoretically the dynamics of two weakly-coupled Bose-Josephson junctions, prepared with the same particle number $N$ and Josephson excitation number $\

Christine Khripkov; Amichay Vardi

2014-05-11T23:59:59.000Z

477

New Approach for the Synthesis and Isolation of Dimeric Procyanidins  

Science Journals Connector (OSTI)

(C3?t, C4?t, C3?u, C4?u), 136.2 (C1?u), 132.9 (C1?t), 121.4?120.6 (C6?t, C6?u), 117.4 (C2?u), 116.3?116.1 (C5?t, C5?u), 115.8 (C2?t), 107.9 (C8t), 106.2 (C4u), 101.1 (C4at), 98.2 (C6t), 96.7 (C6u, C8u), 83.3 (C2t), 77.6 (C2u), 69.0 (C3t), 46.8 (C1u), 31.0 (C3u), 30.3 (C4t) ppm. ... 13C NMR (150 MHz, acetone-d6 + 5% D2O, 300 K): 158.2 (C5u, C7u, C9u), 156.6 (C7t), 156.4 (C5t), 155.5 (C8at), 146.3 (C3?, C4?), 146.2 (C3?, C4?), 145.9, (C4?u*) 144.2 (C3?u*), 135.6 (C1?u), 132.5 (C1?t), 120.8 (C6?t, C6?u), 117.0 (C2?u), 116.2 (C5?t), 116.1 (C2?t, C5?u), 108.3 (C6t), 105.9 (C4u), 102.3 (C4at), 96.3 (C6u, C8u), 96.1 (C8t), 83.3 (C2t), 78.2 (C2u), 69.1 (C3t), 46.6 (C1u), 31.0 (C4t), 30.4 (C3u) ppm (* exchangeable). ... (C3?t, C4?t, C3?u, C4?u), 136.2 (C1?u), 133.0 (C1?t), 121.2 (C6?u), 120.1 (C6?t), 117.3 (C2?u), 116.3 (C5?t), 116.1 (C5?u), 115.4 (C2?t), 107.9 (C8t), 106.5 (C4), 99.9 (C4at), 98.2 (C6t), 97.1 (C6u, C8u), 80.2 (C2t), 77.8 (C2u), 67.6 (C3t), 46.3 (C1u), 31.0 (C3u), 30.3 (C4u) ppm. ...

Nils Khler; Victor Wray; Peter Winterhalter

2008-06-10T23:59:59.000Z

478

Nature of Bridging Bonds in Lithium and Potassium Acetate Dimers  

Science Journals Connector (OSTI)

The structures of lithium and potassium acetates were studied by the RHF/6-31G*...3COOLi)2 and (CH3COOK)2 are electrostatic in nature. The bridging lithium bond is intermediate between hydrogen and ionic, ... of ...

I. A. Panteleev; S. G. Semenov; D. N. Glebovskii

479

Cationic Ruthenium Hydrido?Carbonyls Derived from Metallocene-Based Pincers: Unusual Rearrangements and H2 Evolution with Formation of Cationic Ruthenium Metallocenylidenes  

Science Journals Connector (OSTI)

Calculations were performed using the PRIRODA program(20) and PBE functional(21) with 3z (includes functions for elements up to Xe) and sbk (includes functions for elements heavier than Xe up to radon) basis sets. ... This work was partly supported by the Russian Academy of Sciences, OX-01 Program of the Branch of Chemistry and Materials Sciences, the Russian Foundation for Basic Research (Project Nos. ... 10-03-00505, 08-03-01020), and the International Science and Technology Center (ISTC, Grant G 1361). ...

Avthandil A. Koridze; Alexander V. Polezhaev; Sergey V. Safronov; Alexey M. Sheloumov; Fedor M. Dolgushin; Mariam G. Ezernitskaya; Boris V. Lokshin; Pavel V. Petrovskii; Alexander S. Peregudov

2010-09-09T23:59:59.000Z

480

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

E-Print Network (OSTI)

dioxide electrodes.2-4 The highest efficiency reported to date for such systems has been obtained using conversion efficiencies of up to 10% have been reported.4 The approximate energetics for this system while maintaining the excited-state redox potential at the same energy level relative to the TiO2 can

Sauvé, Geneviève

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

CO adsorption-desorption properties of cation-exchanged NaX zeolite and supported ruthenium  

SciTech Connect

The binding states of carbon monoxide over cation-exchanged NaX zeolites and over corresponding Ru-containing samples have been investigated using thermal desorption spectroscopy. Exchange of sodium with cations such as Li{sup +}, Ca{sup 2+}, Mg{sup 2+}, and La{sup 3+} gave rise to additional CO adsorption states, a higher isosteric heat of CO adsorption, an increased density of acid sites, and an increased amount of adsorbed CO, depending on the nature and ionic radius of the charge-balancing cation. The charge-balancing cations at the zeolite surface (e.g., Ca{sub 2+}, La{sup 3+}) function as additional CO adsorption sites in conjunction with surface acid centers (e.g., the Al{sup 3+} center) and metal sites. In addition to surface sites, CO is also found to be held in structural cavities and macropores of the zeolite matrix. The programmed heating of both the metal-free and Ru-containing zeolites subsequent to room temperature CO adsorption gave desorption peaks due to release of CO at temperatures less than {approximately}500 K while the higher temperature peaks were constituted mainly of CO{sub 2}. Electron spectroscopy results have revealed that the exposure of these samples to CO and subsequent thermal treatment resulted in the formation of surface carbonaceous species. The nature of CO adsorption states giving rise to CO{sub 2} formation is discussed.

Gupta, N.M.; Kamble, V.S.; Rao, K.A.; Iyer, R.M. (Bhabha Atomic Research Centre, Bombay (India))

1989-12-01T23:59:59.000Z

482

Carbon monoxide adsorption/desorption processes over NaX zeolite and supported ruthenium catalyst  

SciTech Connect

The binding states of CO on NaX zeolite and RuNaX were investigated by thermal desorption spectroscopy. Desorption peaks centered at around 390, 430, 490, and 520 K were observed from NaX following room-temperature adsorption of CO. The activation energy values corresponding to these peaks were calculated to be 41.4, 45.7, 53.8, and 57.7 kJ mol{sup {minus}1}, respectively. These peaks were also observed in desorption profiles from RuNaX although their temperatures were higher by 10 to 20 K. In addition, the desorption spectra from RuNaX also comprise two high-temperature peaks at around 575 and 640 K. With both the RuNaX and the NaX samples the temperature and relative intensities of the desorption peaks depended on pretreatment conditions and on the lapsed time between CO exposure to the sample and the commencement of programmed heating. Mass spectral analysis revealed that the gas desorbed at 300-500 K consisted mainly of CO while at higher temperatures CO{sub 2} was the main component. The desorption peaks below 500 K are attributed to the release of carbon monoxide from structural and intragranular or intergranular zeolitic pores. Lewis sites on the zeolite surface are found to facilitate activation of CO, resulting in its transformation to CO{sub 2}. The initial adsorption of carbon monoxide in zeolite pores and subsequent diffusion to metal sites leading to its disproportionation/oxidation is found to play an important role in the CO adsorption/desorption process on RuNaX.

Kamble, V.S.; Gupta, N.M.; Iyer, R.M. (Bhabha Atomic Research Centre, Bombay (India))

1988-10-01T23:59:59.000Z

483

Two-Dimensional, Pyrazine-Based Nonlinear Optical Chromophores with Ruthenium(II) Ammine Electron Donors  

Science Journals Connector (OSTI)

Benjamin J. Coe *, John Fielden , Simon P. Foxon , Inge Asselberghs , Koen Clays , and Bruce S. Brunschwig ... (a) Coe, B. J., Harris, J. A., Asselberghs, I., Persoons, A., Jeffery, J. C., Rees, L. H., Gelbrich, T., and Hursthouse, M. B. J. Chem. ... Coe, Benjamin J.; Harris, James A.; Asselberghs, Inge; Persoons, Andre; Jeffery, John C.; Rees, Leigh H.; Gelbrich, Thomas; Hursthouse, Michael B. ...

Benjamin J. Coe; John Fielden; Simon P. Foxon; Inge Asselberghs; Koen Clays; Bruce S. Brunschwig

2010-10-20T23:59:59.000Z

484

Electroabsorption Spectroscopic Studies of Dipolar Ruthenium(II) Complexes Possessing Large Quadratic Nonlinear Optical Responses  

Science Journals Connector (OSTI)

Coe, Benjamin J.; Chamberlain, Michelle C.; Essex-Lopresti, Jonathan P.; Gaines, Simon; Jeffery, John C.; Houbrechts, Stephan; Persoons, Andre ... Coe, Benjamin J.; Harris, James A.; Harrington, Lisa J.; Jeffery, John C.; Rees, Leigh H.; Houbrechts, Stephan; Persoons, Andre ... Coe, Benjamin J.; Harris, James A.; Asselberghs, Inge; Persoons, Andre; Jeffery, John C.; Rees, Leigh H.; Gelbrich, Thomas; Hursthouse, Michael B. ...

Benjamin J. Coe; James A. Harris; Bruce S. Brunschwig

2002-01-17T23:59:59.000Z

485

Straightforward Synthesis of ?,?-Unsaturated Thioesters via Ruthenium-Catalyzed Olefin Cross-Metathesis with Thioacrylate  

Science Journals Connector (OSTI)

Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands ...

Anthoni W. van Zijl; Adriaan J. Minnaard; Ben L. Feringa

2008-06-18T23:59:59.000Z

486

E-Print Network 3.0 - active chiral ruthenium Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

on what has now become a flourishing and dynamic field Source: Zheludev, Nikolay - Optoelectronics Research Centre & School of Physics and Astronomy, University of Southampton...

487

Spectroscopy and Dynamics of Phosphonate-Derivatized Ruthenium Complexes on TiO2  

Science Journals Connector (OSTI)

Paul G. Giokas , Stephen A. Miller , Kenneth Hanson , Michael R. Norris , Christopher R. K. Glasson , Javier J. Concepcion , Stephanie E. Bettis , Thomas J. Meyer *, and Andrew M. Moran * ...

Paul G. Giokas; Stephen A. Miller; Kenneth Hanson; Michael R. Norris; Christopher R. K. Glasson; Javier J. Concepcion; Stephanie E. Bettis; Thomas J. Meyer; Andrew M. Moran

2012-12-12T23:59:59.000Z

488

Palladium and ruthenium supported silver migration in 3Csilicon carbide  

Science Journals Connector (OSTI)

Abstract Surrogate TRISO particles were infiltrated with a Pd Ag mixture and heat treated at 1000C to investigate the effect of Pd on Ag transport through current state of the art TRISO coatings for use in HTGRs. The experiment was repeated with Ru instead of Pd because of the similarities in the reaction between Pd and Ru with SiC. It was found that both Pd and Ru form their respective silicides after heat treatment together with the simultaneous precipitation of graphite. In both cases Ag was concentrated along the leading edge of the reaction zone which itself was concentrated along grain boundaries. However, the effect of Pd was much more pronounced than that of Ru making Ru at most a secondary contributor to Ag migration through SiC in TRISO fuel.

Jacques Herman OConnell; Johannes Henoch Neethling

2015-01-01T23:59:59.000Z

489

Iridium?Ruthenium Alloyed Nanoparticles for the Ethanol Oxidation Fuel Cell Reactions  

SciTech Connect

In this study, carbon supported Ir-Ru nanoparticles with average sizes ranging from 2.9 to 3.7 nm were prepared using a polyol method. The combined characterization techniques, that is, scanning transmission electron microscopy equipped with electron energy loss spectroscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, were used to determine an Ir-Ru alloy nanostructure. Both cyclic voltammetry and chronoamperometry (CA) results demonstrate that Ir{sub 77}Ru{sub 23}/C bears superior catalytic activities for the ethanol oxidation reaction compared to Ir/C and commercial Pt/C catalysts. In particular, the Ir{sub 77}Ru{sub 23}/C catalyst shows more than 21 times higher mass current density than that of Pt/C after 2 h reaction at a potential of 0.2 V vs Ag/AgCl in CA measurement. Density functional theory simulations also demonstrate the superiority of Ir-Ru alloys compared to Ir for the ethanol oxidation reaction.

Su D.; Du, W.; Deskins, N.A.; Teng, X.

2012-06-01T23:59:59.000Z

490

Stability of Supported Ruthenium Catalysts for Lignin Gasification in Supercritical Water  

Science Journals Connector (OSTI)

However, low-temperature methods for lignin gasification are desirable, because waste heat available from high-temperature processes in industry can be utilized for energy generation.1 ... The gasification of lignin proceeded in supercritical water, and all lignin was gasified completely over Ru/TiO2 after 180 min during the first use. ... water for gasification technique of wastes. ...

Mitsumasa Osada; Osamu Sato; Kunio Arai; Masayuki Shirai

2006-09-29T23:59:59.000Z

491

Asymmetric Catalytic Synthesis of P-Stereogenic Phosphines via a Nucleophilic Ruthenium Phosphido Complex  

E-Print Network (OSTI)

SN2 substrate, within 36 h at 45 °C; the resulting methylneopentylphenylphosphine dissociated from@berkeley.edu; fdtoste@berkeley.edu Many reactions rely upon the activation of an electrophile via coordination transition-metal-catalyzed asymmetric reactions,3 but have seen little use to date, due to the dearth

Toste, Dean

492

CO adsorption on ion-exchanged Ru zeolite catalysts  

SciTech Connect

CO adsorption on ion-exchanged Ru zeolite catalysts, studied by IR spectroscopy, revealed the existence of three types of ruthenium which adsorbed the carbon monoxide into three different states. The ruthenium types were atomically or highly dispersed ruthenium, ruthenium clusters which formed ruthenium carbonyl, and larger (> 1 nm) particles, probably on the outer zeolite surfaces.

Goodwin, J.G. (Univ. of Pittsburgh); Naccache, G.

1980-08-01T23:59:59.000Z

493

Modification of Gold Catalysis withModification of Gold Catalysis with Aluminum Phosphate for OxygenAluminum Phosphate for Oxygen--Reduction ReactionReduction Reaction  

E-Print Network (OSTI)

Ford Toshiba Samsung Byungwoo Park's Group #12;Scheme of Fuel Cells Load e- e- Hydrogen Methanol + Water (DMFC· Morphology of Au/AlPO4 Nanocomposite Catalyst · Oxygen Reduction Activity ­ Hydrogen Peroxide Intermediate to Gold Seoul National University Yejun Park et al. 22Byungwoo Park's Group #12;Applications of Fuel Cells

Park, Byungwoo

494

Structural, magnetic, and electrical properties of Li2Ir1?xRuxO3  

Science Journals Connector (OSTI)

The crystal structure, resistivity, and magnetic susceptibility of the Li2Ir1?xRuxO3 (x=01) polycrystals have been investigated. We found that the parent antiferromagnetic phase disappears for x>0.2 and bond dimers appear in the averaged structure for x>0.5 and likely fluctuate for much smaller x. Unexpectedly, this system remains insulating for all the doping levels, contrary to the predictions based on the one-band jeff=1/2 Kitaev-Heisenberg model. These results suggest that the honeycomb iridates doped with ruthenium are a unique 5d-orbital-based platform for studying the interplay of the charge, orbital, spin, and lattice degrees of freedom.

Hechang Lei (???); Wei-Guo Yin (???); Zhicheng Zhong (???); Hideo Hosono

2014-01-31T23:59:59.000Z

495

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

E-Print Network (OSTI)

Catalytic Processes for Sustainable Biomass Con- versionCatalytic Processes for Sustainable Biomass Conversion IstvCatalyses for New Sustainable Green Processes on Catalyst

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

496

Exploration of catalysis activation emergency as a function of gold nanoparticle surface morphology  

E-Print Network (OSTI)

The application of rippled gold nanoparticles with bi-ligand surface morphology as a catalyst was tested. The hydrolysis of 2,4-dinitrophenyl acetate (DNPA) served as the catalytic reaction being analyzed and the bi-ligand ...

Stefanescu, Cristina F

2008-01-01T23:59:59.000Z

497

Developing an approach for first-principles catalyst design: application to carbon-capture catalysis  

Science Journals Connector (OSTI)

An approach to first-principles catalyst design is presented in which models are used to elucidate geometric-energetic-activity relationships. These design principles are then employed to search structural databases for matching candidate catalysts in the example CO2 hydration reaction.

Kulik, H.J.

2014-01-31T23:59:59.000Z

498

Journal of Catalysis 221 (2004) 354364 www.elsevier.com/locate/jcat  

E-Print Network (OSTI)

for hydrotreating processes. However, most studies on these catalysts have focused on alumina-supported systems

Resasco, Daniel

499

Catalysis of hydrocarbon synthesis from CO and H{sub 2} on carbon membranes  

SciTech Connect

This paper describes the preparation of carbon membrane supports from polyacrylonitrile. The membranes were utilized for the preparation of cobalt catalysts. The catalysts were prepared by impregnating the membranes with a cobalt nitrate solution followed by drying on a water bath. The cobalt was sometimes introduced directly into the molding solution before the activation stage. The cobalt catalysts were utilized in the methanation of carbon monoxide. The products were dependent on the conditions utilized to obtain the carbon supports.

Lapidus, A.l.; Krylova, A.Yu.; Strupov, A.N.; Linkov, V.M.; Sanderson, R.D. [Rossiiskaya Akademiya, Nauk (Russian Federation)

1994-12-31T23:59:59.000Z

500

Applied Catalysis A: General 469 (2014) 275283 Contents lists available at ScienceDirect  

E-Print Network (OSTI)

from the standpoint of energy efficiency, compared to endothermic steam reforming (Eq. (2)) and dry2O3 or Ce0.5Zr0.5O2 supports for the partial oxidation of methane Alejandro J. Santis Catalytic partial oxidation Flame spray synthesis a b s t r a c t Catalytic partial oxidation of methane

Daraio, Chiara