Size Effect Of Ruthenium Nanoparticles In Catalytic Carbon Monoxide Oxidation, 2010 University of California - Berkeley
Size Effect Of Ruthenium Nanoparticles In Catalytic Carbon Monoxide Oxidation, Sang Hoon Joo, Jeong Y. Park, J. Russell Renzas, Derek R. Butcher, Wenyu Huang, Gabor A. Somorjai
Wenyu Huang
Carbon monoxide oxidation over ruthenium catalysts has shown an unusual catalytic behavior. Here we report a particle size effect on CO oxidation over Ru nanoparticle (NP) catalysts. Uniform Ru NPs with a tunable particle size from 2 to 6 nm were synthesized by a polyol reduction of Ru(acac)3 precursor in the presence of poly(vinylpyrrolidone) stabilizer. The measurement of catalytic activity of CO oxidation over two-dimensional Ru NPs arrays under oxidizing reaction conditions (40 Torr CO and 100 Torr O2) showed an activity dependence on the Ru NP size. The CO oxidation activity increases with NP size, and the 6 nm …
Highly Active Heterogeneous Palladium Nanoparticle Catalysts For Homogeneous Electrophilic Reactions In Solution And The Utilization Of A Continuous Flow Reactor, 2010 University of California - Berkeley
Highly Active Heterogeneous Palladium Nanoparticle Catalysts For Homogeneous Electrophilic Reactions In Solution And The Utilization Of A Continuous Flow Reactor, Wenyu Huang, Jack Hung Chang Liu, Pinar Alayoglu, Yimin Li, Cole A. Whitman, Chia-Kuang Tsung, F. Dean Toste, Gabor A/ Somorjai
Wenyu Huang
highly active heterogeneous Pd-nanoparticle catalyst for the intramolecular addition of phenols to alkynes was developed and employed in a continuous flow reaction system. Running the reaction in flow mode revealed reaction kinetics, such as the activation energy and catalyst deactivation, and provides many potential practical advantages.
Seedless Polyol Synthesis And Co Oxidation Activity Of Monodisperse (111)- And (100)-Oriented Rhodium Nanocrystals In Sub-10 Nm Sizes, 2010 University of California - Berkeley
Seedless Polyol Synthesis And Co Oxidation Activity Of Monodisperse (111)- And (100)-Oriented Rhodium Nanocrystals In Sub-10 Nm Sizes, Yawen Zhang, Michael E. Grass, Wenyu Huang, Gabor A. Somoraji
Wenyu Huang
Monodisperse sub-10 nm (6.5 nm) sized Rh nanocrystals with (111) and (100) surface structures were synthesized by a seedless polyol reduction in ethylene glycol, with poly(vinylpyrrolidone) as a capping ligand. When using [Rh(Ac)2]2 as the metal precursor, (111)-oriented Rh nanopolyhedra containing 76% (111)-twinned hexagons (in 2D projection) were obtained; whereas, when employing RhCl3 as the metal precursor in the presence of alkylammonium bromide, such as tetramethylammonium bromide and trimethyl(tetradecyl)ammonium bromide, (100)-oriented Rh nanocubes were obtained with 85% selectivity. The {100} faces of the Rh nanocrystals are stabilized by chemically adsorbed Br− ions from alkylammonium bromides, which led to (100)-oriented nanocubes. …
Furan Hydrogenation Over Pt(111) And Pt(100) Single-Crystal Surfaces And Pt Nanoparticles From 1 To 7 Nm: A Kinetic And Sum Frequency Generation Vibrational Spectroscopy Study, 2010 University of California - Berkeley
Furan Hydrogenation Over Pt(111) And Pt(100) Single-Crystal Surfaces And Pt Nanoparticles From 1 To 7 Nm: A Kinetic And Sum Frequency Generation Vibrational Spectroscopy Study, Christopher J. Kliewer, Cesar Aliaga, Marco Bieri, Wenyu Huang, Chia-Kuang Tsung, Jennifer B. Wood, Kyriankos Komvopoulos, Gabor A. Somorjai
Wenyu Huang
Sum frequency generation surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to systematically study the adsorption and hydrogenation of furan over Pt(111) and Pt(100) single-crystal surfaces and size-controlled 1.0-nm, 3.5-nm and 7.0-nm Pt nanoparticles at Torr pressures (10 Torr of furan, 100 Torr of H2) to form dihydrofuran, tetrahydrofuran, and the ring-cracking products butanol and propylene. As determined by SFG, the furan ring lies parallel to all Pt surfaces studied under hydrogenation conditions. Upright THF and the oxametallacycle intermediate are observed over the nanoparticle catalysts under reaction conditions. Butoxy increases in surface concentration over Pt(111) with …
Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, 2010 University of Nevada, Las Vegas
Sulfur K-Edge Photo-Fragmentation Of Ethylene Sulfide, Wayne C. Stolte, Gunnar Ohrwall
Chemistry and Biochemistry Faculty Research
We have investigated the photofragmentation properties of the three-membered ring heterocyclic molecule ethylene sulfide or thiirane, C2H4S, by time-of-flight mass spectroscopy. Positive ions have been collected as a function of photon energy around the S K ionization threshold. Branching ratios were derived for all detected ions, which are informative of the decay dynamics and photofragmentation patterns of the core-excited species. We present a new assignment of the spectral features around the S K-edge.
Two-Dimensional To Three-Dimensional Structural Transition Of Gold Cluster Au 10 During Soft Landing On Tio 2 Surface And Its Effect On Co Oxidation, 2010 University of Nebraska-Lincoln
Two-Dimensional To Three-Dimensional Structural Transition Of Gold Cluster Au 10 During Soft Landing On Tio 2 Surface And Its Effect On Co Oxidation, Hui Li, Yong Pei, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We investigate the possible structural transition of a planar Au10 cluster during its soft landing on a TiO2 (110) surface with or with no oxygen defects. The collision between the gold cluster and the oxide surface is simulated using the Car–Parrinello quantum molecular dynamics method. Both high-speed and low-speed conditions typically implemented in soft-landing experiments are simulated. It is found that under a high-speed condition, the gold cluster Au10 can undergo a sequence of structural transitions after colliding with a defect-free TiO2 (110) surface. When the TiO2 (110) surface possesses oxygen vacancies, however, chemical bonds …
Icosahedral B12-Containing Core–Shell Structures Of B80, 2010 University of Nebraska-Lincoln
Icosahedral B12-Containing Core–Shell Structures Of B80, Hui Li, Nan Shao, Bo Shang, Lan-Feng Yuan, Jinlong Yang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Low-lying icosahedral (Ih) B12-containing structures of B80 are explored, and a number of core–shell isomers are found to have lower energy than the previous predicted B80 fullerene. The structural transformation of boron clusters from tubular structure to core–shell structure may occur at a critical size less than B80.
Graphene-Like Bilayer Hexagonal Silicon Polymorph, 2010 University of Nebraska-Lincoln
Graphene-Like Bilayer Hexagonal Silicon Polymorph, Jaeil Bai, Hideki Tanaka, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
We present molecular dynamics simulation evidence for a freezing transition from liquid silicon to quasi-twodimensional (quasi-2D) bilayer silicon in a slit nanopore. This new quasi-2D polymorph of silicon exhibits a bilayer hexagonal structure in which the covalent coordination number of every silicon atom is four. Quantum molecular dynamics simulations show that the stand-alone bilayer silicon (without the confinement) is still stable at 400 K. Electronic band-structure calculations suggest that the bilayer hexagonal silicon is a quasi-2D semimetal, similar to a graphene monolayer, but with an indirect zero band gap.
Reduced Electronic Spaces For Modeling Donor/Acceptor Interactions, 2010 Harvey Mudd College
Reduced Electronic Spaces For Modeling Donor/Acceptor Interactions, Robert J. Cave, Stephen T. Edwards '06, John A, Kouzelos '07, Marshall D. Newton
All HMC Faculty Publications and Research
Diabatic states for donor (D) and acceptor (A) interactions in electron transfer (ET) processes are formulated and evaluated, along with coupling elements (HDA) and effective D/A separation distances (rDA), for reduced electronic spaces of variable size, using the generalized Mulliken Hush model (GMH), applicable to an arbitrary state space and nuclear configuration, and encompassing Robin−Day class III and as well as class II situations. Once the electronic state space is selected (a set of n ≥ 2 adiabatic states approximated by an orbital space based on an effective 1-electron (1-e) Hamiltonian), the charge-localized GMH …
Mechanistic Importance Of Redox Potentials And Conformational Flexibility In Electron-Transferring Flavoproteins, 2010 University of Denver
Mechanistic Importance Of Redox Potentials And Conformational Flexibility In Electron-Transferring Flavoproteins, Michael Anthony Swanson
Electronic Theses and Dissertations
The mitochondrial matrix flavoproteins electron transfer flavoprotein (ETF) and electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) are responsible for linking fatty acid β-oxidation with the main mitochondrial respiratory chain. Electrons derived from flavoprotein dehydrogenases are transferred sequentially through ETF and ETF-QO to ubiquinone and then into the respiratory chain via complex III. In this study, the effects of changes in ETF-QO redox potentials on its activity and the conformational flexibility of ETF were investigated.
ETF-QO contains one [4Fe-4S]2+,1+ and one flavin adenine dinucleotide (FAD). In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring …
Hydrophobic Silicas With Well-Defined Chemistry And Geometry: Synthesis, Adsorption, And Interfacial Properties, 2010 Seton Hall University
Hydrophobic Silicas With Well-Defined Chemistry And Geometry: Synthesis, Adsorption, And Interfacial Properties, Francis Bernardoni
Seton Hall University Dissertations and Theses (ETDs)
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Elucidating The Structure Of Protein Aggregates By Raman Spectroscopy, 2010 University at Albany, State University of New York
Elucidating The Structure Of Protein Aggregates By Raman Spectroscopy, Ludmila A. Popova
Legacy Theses & Dissertations (2009 - 2024)
The structures and properties of amyloid fibrils are of considerable interest due to their associations with numerous neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and transmissible spongiform encephalopaties (prion diseases). Understanding fibrillogenesis at a molecular level requires detailed structural characterization of amyloid fibrils. However amyloid fibrils are difficult objects to study due to their non-crystalline and insoluble nature. These properties make the application of classical tools of structural biology, such as X-Ray crystallography and solution Nuclear Magnetic Resonance spectroscopy, impractical for structural characterization of protein fibrils.
Analysis Of The Electron Withdrawing Capability Of Acetylene Groups For Promoting Nucleophilic Aromatic Substitution, 2010 Colby College
Analysis Of The Electron Withdrawing Capability Of Acetylene Groups For Promoting Nucleophilic Aromatic Substitution, Eric D. Braunstein
Honors Theses
It is well known that electron withdrawing groups, such as nitro or carbonyl groups, activate benzene rings for nucleophilic aromatic substitution. However, little research has been done to investigate the electron withdrawing capability of acetylene groups for substitution of aromatic halides. Experimental and computational investigations on the reactivity of halogenated phenylacetylenes with oxygen and other nucleophiles will be described.
Dynamic Path Bifurcation For The Beckmann Reaction: Observation And Implication, 2010 University of South Carolina - Columbia
Dynamic Path Bifurcation For The Beckmann Reaction: Observation And Implication, H. Yamataka, M. Sato, H. Hasegawa, Salai Cheettu Ammal
Faculty Publications
The reaction of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles instead of amides when the cations have reasonable stability. The reactions of oxime derivatives of 1-substituted-phenyl-2-propanones and 3-substituted-phenyl-2-butanones in aqueous solvents gave both rearrangement and fragmentation products, the ratio of which was dependent on substituents. Transition state (TS) optimizations and intrinsic reaction coordinate (IRC) calculations for the reaction of 1-phenyl-2-propanone oximes showed that there is a single TS for each substituted compound. The IRC path from the TS either led to a rearrangement product or a fragmentation product depending on the …
Molecular Dynamics Studies Of Simple Model Fluids And Water Confined In Carbon Nanotube, 2010 University of Nebraska - Lincoln
Molecular Dynamics Studies Of Simple Model Fluids And Water Confined In Carbon Nanotube, Jun Wang
Department of Chemistry: Dissertations, Theses, and Student Research
Molecular Dynamics (MD) simulation is one of the most important computational techniques with broad applications in physics, chemistry, chemical engineering, materials design and biological science. Traditional computational chemistry refers to quantum calculations based on solving Schrodinger equations. Later developed Density Functional Theory (DFT) based on solving Kohn-Sham equations became the more popular ab initio calculation technique which could deal with ~1000 atoms by explicitly considering electron interactions. In contrast, MD simulation based on solving classical mechanics equations of motion is a totally different technique in the field of computational chemistry. Electron interactions were implicitly included in the empirical atom-based potential …
Development Of Metal-Based Luminescent Probes For Applications In Biomolecular Structure And Dynamics, 2010 University of Montana
Development Of Metal-Based Luminescent Probes For Applications In Biomolecular Structure And Dynamics, Ayesha Sharmin
Graduate Student Theses, Dissertations, & Professional Papers
New transition-metal complexes containing luminescent properties have been designed and synthesized for application as structural probes for biomolecules. Potential DNA intercalators, 2- amino-anthracene substituted triosmium clusters, were synthesized by the reactions of 2-aminoanthracene with [Os3(CO)10(CH3CN)2]. The products [Os3(CO)10(μ-η2-(N-C(1))-NH2C14H8)(μ- H)], [Os3(CO)10(μ-η2-(N-C(3))-NHC14H9)(μ-H)], [Os3(CO)9(μ-η2-(N-C(3))-NHC14H8)(μ-H)2] and [Os3(CO)9(μ3-η2-(N-C(3))-NHC10H9)(μ-H)] obtained from this reaction have been structurally characterized by spectroscopic, photophysical and electrochemical techniques. Solid state structures are also reported for the complexes [Os3(CO)10(μ-η2-(N-C(3))-NHC14H9)(μ-H)] and [Os3(CO)9(μ-η2-(N-C(3))-NHC14H8)(μ-H)2]. To investigate bio-macromolecular dynamics on the sub-microsecond-to-microsecond timescale, a series of ruthenium based mono-nuclear metalligand charge-transfer complexes (MLCs) of formula [XRu(CO)(L–L)(L′)2][PF6] (X = H, TFA, Cl; L–L = 2,2′-bipyridyl, 1,10-phenanthroline, 5-amino-1,10-phenanthroline …
Molecular Dynamics Simulations Of Human Quadruplexes In K+ Solution And The Role Of The Carboxyl Terminus Of Bacteriorhodopsin In Protein Stability, 2010 Seton Hall University
Molecular Dynamics Simulations Of Human Quadruplexes In K+ Solution And The Role Of The Carboxyl Terminus Of Bacteriorhodopsin In Protein Stability, Farah Rezae
Seton Hall University Dissertations and Theses (ETDs)
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Enthalpies Of Mixing Of Water And Alkoxyethanols, 2010 University of Texas at El Paso
Enthalpies Of Mixing Of Water And Alkoxyethanols, John Enriquez
Open Access Theses & Dissertations
Alkoxyethanols [CmH2m+1·(OC2H4)·OH] (conveniently abbreviated to CmE1) are a subgroup of the alkyl poly(ethylene glycol) mono-ethers. They are small relatives of a large number of non-ionic detergents. The thermodynamic properties of their mixing in water have been shown to be good sources of information about the interactions of both hydrophilic and hydrophobic groups with water. Theses alkoxyethanols, or glycol ethers, are the ether derivatives of ethylene glycol where one hydroxyl functional group is substituted for an alkoxy functional group. Our group has already published results for aqueous excess properties …
The Effect Of Ion-Pairing On The Open Circuit Potential Of 3-Mercaptoproprionic Acid Modified Gold Electrodes, 2009 Kennesaw State University
The Effect Of Ion-Pairing On The Open Circuit Potential Of 3-Mercaptoproprionic Acid Modified Gold Electrodes, Mark Anderson, Alice Harper
Mark R. Anderson
Open circuit potential (OCP) measurement is used to monitor the charge of a monolayer of 3-mercaptopropionic acid. OCP is determined by the concentrations of the reduced and oxidized forms of a redox couple in the solution adjacent to the modified interface. OCP values were monitored in the presence of the one-electron redox couple Fe(CN)63-/4- as a function of solution pH. The OCP measured at basic pHs was different from the acidic OCP due to differences in electrostatic interactions between the interface and the redox species as described by the Nernst equation. The influence of ion-pairing with the monolayer is studied …
Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, 2009 John Carroll University
Kinetic And Mechanistic Studies Of The Deuterium Exchange In Classical Keto−Enol Tautomeric Equilibrium Reactions, Mark Waner, Michael Nichols
Mark J. Waner
An extension of the classic keto−enol tautomerization of β-dicarbonyl compounds into a kinetic analysis of deuterium exchange is presented. It is shown that acetylacetone and ethyl acetoacetate undergo nearly complete deuterium exchange of the α-methylene carbon when dissolved in methanol-d4. The extent of deuteration may be monitored via NMR spectroscopy as a function of time. A mechanism for deuterium exchange is presented and shown to be consistent with a consecutive first-order process. The data for acetylacetone are consistent with steady-state kinetics, whereas those of ethyl acetoacetate illustrate nonsteady-state behavior, offering an accessible example where students might collect and analyze real …