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Full-Text Articles in Physical Sciences and Mathematics
Xiao Cheng Zeng Bibliography (April 2016), Xiao Cheng Zeng
Xiao Cheng Zeng Bibliography (April 2016), Xiao Cheng Zeng
Xiao Cheng Zeng Publications
397 articles sorted by topics
The Origin Of Amino Acids In Lunar Regolith Samples, Jamie E. Elsila, Michael P. Callahan, Jason P. Dworkin, Daniel P. Glavin, Hannah L. Mclain, Sarah K. Noble, Everett K. Gibson Jr.
The Origin Of Amino Acids In Lunar Regolith Samples, Jamie E. Elsila, Michael P. Callahan, Jason P. Dworkin, Daniel P. Glavin, Hannah L. Mclain, Sarah K. Noble, Everett K. Gibson Jr.
Michael Callahan
We analyzed the amino acid content of seven lunar regolith samples returned by the Apollo 16 and Apollo 17 missions and stored under NASA curation since collection using ultrahigh-performance liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Consistent with results from initial analyses shortly after collection in the 1970s, we observed amino acids at low concentrations in all of the curated samples, ranging from 0.2 parts-per-billion (ppb) to 42.7 ppb in hot-water extracts and 14.5–651.1 ppb in 6 M HCl acid-vapor-hydrolyzed, hot-water extracts. Amino acids identified in the Apollo soil extracts include glycine, d- and l-alanine, d- and l-aspartic …
Novel Techniques For Enhancing Sensitivity In Static Headspace, Nicholas Snow, G.P Bullock
Novel Techniques For Enhancing Sensitivity In Static Headspace, Nicholas Snow, G.P Bullock
Nicholas A Snow
No abstract provided.
Simultaneous Determination Of Pramoxine Hcl And Benzalkonium Chloride In Wound Care Solutions By Hplc, Panagiotis Tavlarakis, Jonine Greyling, Nicholas Snow
Simultaneous Determination Of Pramoxine Hcl And Benzalkonium Chloride In Wound Care Solutions By Hplc, Panagiotis Tavlarakis, Jonine Greyling, Nicholas Snow
Nicholas A Snow
No abstract provided.
Analysis Of Salvinorin A In Plants, Water, And Urine Using Solid-Phase Microextraction-Comprehensive Two-Dimensional Gas Chromatography–Time Of Flight Mass Spectrometry, Brian Barnes, Nicholas Snow
Analysis Of Salvinorin A In Plants, Water, And Urine Using Solid-Phase Microextraction-Comprehensive Two-Dimensional Gas Chromatography–Time Of Flight Mass Spectrometry, Brian Barnes, Nicholas Snow
Nicholas A Snow
No abstract provided.
The Analysis Of Muonium Hyperfine Interaction Measurements Of Thermal Rate Constants For Addition Reactions, Ronald Duchovic, A Wagner, R Turner, D Garner, D Fleming
The Analysis Of Muonium Hyperfine Interaction Measurements Of Thermal Rate Constants For Addition Reactions, Ronald Duchovic, A Wagner, R Turner, D Garner, D Fleming
Ronald J. Duchovic
A new model is developed for the analysis of muon spin relaxation (mu-SR) measurements of muonium (Mu) reaction rates with other chemical species. The kinetics component of the model is specifically developed for addition reactions but can be extended to direct reactions. The polarization component of the model assumes that the adduct formed possesses a single, effective spin precession frequency. The complete model is solved to obtain an analytic expression for the mu-SR signal as a function of time. Both a time-ordered sequence method and a Boltzmann spin equation method give equivalent solutions. These solutions are analyzed under various kinetic …
Teaching College General Chemistry: Techniques Designed To Communicate A Conceptual Framework, Ronald Duchovic
Teaching College General Chemistry: Techniques Designed To Communicate A Conceptual Framework, Ronald Duchovic
Ronald J. Duchovic
General chemistry at the college level is often perceived as a major hurdle by typical undergraduates. Both Freshmen and more advanced students undertake courses in general chemistry either ill-prepared or convinced that the subject matter is beyond their comprehension. With the exception of potential chemistry majors, the vast majority of general chemistry students enter the class simply to satisfy a graduation requirement of their degree program. Consequently, instructors must both communicate an understanding of the subject matter and overcome major barriers to the learning process itself. This paper discusses two techniques which have been utilized for five semesters in general …
Mustard Gas: Its Pre-World War I History, Ronald Duchovic, Joel Vilensky
Mustard Gas: Its Pre-World War I History, Ronald Duchovic, Joel Vilensky
Ronald J. Duchovic
No abstract provided.
Erratum: Theoretical Characterization Of The Potential Energy Surface For H + O2 Ho2* Oh + O. Iii. Computed Points To Define A Global Potential Energy Surface, S Walch, Ronald Duchovic
Erratum: Theoretical Characterization Of The Potential Energy Surface For H + O2 Ho2* Oh + O. Iii. Computed Points To Define A Global Potential Energy Surface, S Walch, Ronald Duchovic
Ronald J. Duchovic
No abstract provided.
A Quasiclassical Trajectory Study Of The Reaction H + O2 Oh + O With The O2 Reagent Vibrationally Excited, Ronald Duchovic, Marla Parker
A Quasiclassical Trajectory Study Of The Reaction H + O2 Oh + O With The O2 Reagent Vibrationally Excited, Ronald Duchovic, Marla Parker
Ronald J. Duchovic
No abstract provided.
Potlib 2001: A Potential Energy Surface Library For Chemical Systems, Ronald Duchovic, Y Volobuev, G Lynch, D Truhlar, T Allison, A Wagner, B Garret, J Corchado
Potlib 2001: A Potential Energy Surface Library For Chemical Systems, Ronald Duchovic, Y Volobuev, G Lynch, D Truhlar, T Allison, A Wagner, B Garret, J Corchado
Ronald J. Duchovic
POTLIB 2001 is a computer program library of global chemical potential energy surface (PES) functions (91 functions in version 1.0) along with test data, a suite of utility programs, and a convenient user interface. The PES programs are written in ANSI standard FORTRAN77 and can be used to determine the Born–Oppenheimer potential energy of chemical systems as a function of the internal coordinates. The accompanying test data allow users to verify local implementations of this library. Finally, the utility programs permit use of this library in conjunction with a variety of chemical dynamics and chemical kinetics computer codes. Interface routines …
Thermal Rate Constants For H + Ch3 Ch4 Recombination. Ii. Comparison Of Experiment And Canonical Variational Transition State Theory, W Hase, S Mondro, Ronald Duchovic, D Hirst
Thermal Rate Constants For H + Ch3 Ch4 Recombination. Ii. Comparison Of Experiment And Canonical Variational Transition State Theory, W Hase, S Mondro, Ronald Duchovic, D Hirst
Ronald J. Duchovic
Canonical variational transition state theory is used to calculate bimolecular rate constants for H + CH, and D + CH, recombination. The calculations are performed on an analytic potential energy surface derived from recent ab initio calculations. Rate constants calculated for this surface are in very good agreement with the experimental values. The H(D)- - -CH3 transitional rocking modes are treated as quantum harmonic oscillators or classical hindered rotors in the calculations. These two treatments give rate constants which agree to within 15%. The variational transition states become tighter as the temperature is increased.
[Erratum] A Correction To The Potlib Library Described In "Potlib 2001: A Potential Energy Surface Library For Chemical Systems": [Computer Physics Communications 144 (2002) 169-187], Ronald Duchovic
Ronald J. Duchovic
No abstract provided.
Venus96: A General Chemical Dynamics Computer Program, W Hase, Ronald Duchovic, X Hu, A Komornicki, K Lim, D-H Lu, G Peslherbe, K Swamy, S Vande Linde, A.J Varandas, H Wang, R Wolf
Venus96: A General Chemical Dynamics Computer Program, W Hase, Ronald Duchovic, X Hu, A Komornicki, K Lim, D-H Lu, G Peslherbe, K Swamy, S Vande Linde, A.J Varandas, H Wang, R Wolf
Ronald J. Duchovic
No abstract provided.
The Fft Method For Determining Semiclassical Eigenvalues: Application To Asymmetric Top Rigid Rotors, Ronald Duchovic, G Schatz
The Fft Method For Determining Semiclassical Eigenvalues: Application To Asymmetric Top Rigid Rotors, Ronald Duchovic, G Schatz
Ronald J. Duchovic
A Fourier transform method for calculating action variables and semiclassical eigenvalues in molecules starting from Cartesian coordinates and momenta is developed and applied to the determination of rotational semiclassical eigenvalues for rigid asymmetric top molecules. The method involves calculating rotational actions by using Fourier representations of the symmetric top action‐angle variables to express the integrals. The question of what is the optimum quantization axis is considered, and it is found that the same primitive semiclassical eigenvalues are obtained independent of which principal axis is used for quantization provided that the replacement J → J+ 1/2 is made. The replacement J …
An Application Of Conventional Transition State `Theory To Compute High--Pressure Limit Thermal Rate Coefficients For The Reaction: H(D) + O2 H(D)O2* Oh(D) + O, Ronald Duchovic, J Pettigrew
An Application Of Conventional Transition State `Theory To Compute High--Pressure Limit Thermal Rate Coefficients For The Reaction: H(D) + O2 H(D)O2* Oh(D) + O, Ronald Duchovic, J Pettigrew
Ronald J. Duchovic
Several ab initio studies have focused on the minimum energy path region of the hydroperoxyl potential energy surface (PES) (J. Chem. Phys. 1988, 88, 6273) and the saddle point region for H-atom exchange via a T-shaped HO2 complex (J. Chem. Phys. 1989, 91, 2373). Further, the results of additional calculations (J. Chem. Phys. 1991, 94, 7068) have been reported which, when combined with the earlier studies, provide a global description (but not an analytic representation) of the PES for this reaction. In this work, information at the stationary points of the ab initio PES is used within the framework of …
Conventional Transition State Theory/Rice-Ramsperger-Kassel-Marcus Theory Calculations Of Thermal Termolecular Rate Coefficients For H(D) + O2 + M, Ronald Duchovic, J Pettigrew, B Welling, T Shipchandler
Conventional Transition State Theory/Rice-Ramsperger-Kassel-Marcus Theory Calculations Of Thermal Termolecular Rate Coefficients For H(D) + O2 + M, Ronald Duchovic, J Pettigrew, B Welling, T Shipchandler
Ronald J. Duchovic
Several ab initio studies have focused on the minimum energy path region of the hydroperoxyl potential energy surface (PES) [J. Chem. Phys. 88, 6273 (1988)] and the saddle point region for H‐atom exchange via a T‐shaped HO2 complex [J. Chem. Phys. 91, 2373 (1989)]. Further, the results of additional calculations [J. Chem. Phys. 94, 7068 (1991)] have been reported, which, when combined with the earlier studies, provide a global description (but not an analytic representation) of the PES for this reaction. In this work, information at the stationary points of theab initio PES is used within the framework of conventional …
Teaching Science To The Non-Science Major: An Interdisciplinary Approach, Ronald Duchovic, David Maloney, A Majumdar, R Manalis
Teaching Science To The Non-Science Major: An Interdisciplinary Approach, Ronald Duchovic, David Maloney, A Majumdar, R Manalis
Ronald J. Duchovic
No abstract provided.
Theoretical Characterization Of The Minimum Energy Path For Hydrogen Atom Addition To N2: Implications For The Unimolecular Lifetime Of Hn2, S Walch, Ronald Duchovic, C Rohlfing
Theoretical Characterization Of The Minimum Energy Path For Hydrogen Atom Addition To N2: Implications For The Unimolecular Lifetime Of Hn2, S Walch, Ronald Duchovic, C Rohlfing
Ronald J. Duchovic
The minimum energy path (MEP) for the addition of a hydrogen atom to N2 is characterized in CASSCF/externally contracted CI calculations using a [4s3p2d1f/3s2p1d] ANO basis set, with additional single point calculations at the stationary points of the potential energy surface using a [5s4p3d2f/4s3p2s] ANO basis set. These calculations represent the most extensive set of ab initio calculations on HN2 completed to date, yielding a zero-point corrected barrier for HN2 dissociation of ?8.5 kcal mol-1. The lifetime of the HN2 species is estimated from the calculated geometries and energetics using both conventional transition state theory and a method which utilizes …
Interplay Of Hydrogen Bonds And N→Π* Interactions In Proteins, Gail J. Bartlett, Robert W. Newberry, Brett Vanveller, Ronald T. Raines, Derek N. Woolfson
Interplay Of Hydrogen Bonds And N→Π* Interactions In Proteins, Gail J. Bartlett, Robert W. Newberry, Brett Vanveller, Ronald T. Raines, Derek N. Woolfson
Brett VanVeller
Protein structures are stabilized by multiple weak interactions, including the hydrophobic effect, hydrogen bonds, electrostatic effects, and van der Waals interactions. Among these interactions, the hydrogen bond is distinct in having its origins in electron delocalization. Recently, another type of electron delocalization, the n→π* interaction between carbonyl groups, has been shown to play a role in stabilizing protein structure. Here we examine the interplay between hydrogen bonding and n→π* interactions. To address this issue, we used data available from high-resolution protein crystal structures to interrogate asparagine side-chain oxygen atoms that are both acceptors of a hydrogen bond and donors of …
Detection Of Boronic Acids Through Excited-State Intramolecular Proton-Transfer Fluorescence, Matthew R. Aronoff, Brett Vanveller, Ronald T. Raines
Detection Of Boronic Acids Through Excited-State Intramolecular Proton-Transfer Fluorescence, Matthew R. Aronoff, Brett Vanveller, Ronald T. Raines
Brett VanVeller
Boronic acids are versatile reagents for the chemical synthesis of organic molecules. They and other boron-containing compounds can be detected readily by the interruption of the excited-state intramolecular proton transfer (ESIPT) of 10-hydroxybenzo[h]quinolone. This method is highly sensitive and selective, and useful for monitoring synthetic reactions and detecting boron-containing compounds on a solid support.
A Divalent Protecting Group For Benzoxaboroles, Brett Vanveller, Matthew R. Aronoff, Ronald T. Raines
A Divalent Protecting Group For Benzoxaboroles, Brett Vanveller, Matthew R. Aronoff, Ronald T. Raines
Brett VanVeller
1-Dimethylamino-8-methylaminonaphthalene is put forth as a protecting group for benzoxaboroles. The ensuing complex is fluorescent, charge-neutral, highly stable under basic conditions, stable to anhydrous acid, and readily cleavable in aqueous acid to return the free benzoxaborole.
N→Π* Interactions Of Amides And Thioamides: Implications For Protein Stability, Robert W. Newberry, Brett Vanveller, Ilia A. Guzei, Ronald T. Raines
N→Π* Interactions Of Amides And Thioamides: Implications For Protein Stability, Robert W. Newberry, Brett Vanveller, Ilia A. Guzei, Ronald T. Raines
Brett VanVeller
Carbonyl–carbonyl interactions between adjacent backbone amides have been implicated in the conformational stability of proteins. By combining experimental and computational approaches, we show that relevant amidic carbonyl groups associate through an n→π* donor–acceptor interaction with an energy of at least 0.27 kcal/mol. The n→π* interaction between two thioamides is 3-fold stronger than between two oxoamides due to increased overlap and reduced energy difference between the donor and acceptor orbitals. This result suggests that backbone thioamide incorporation could stabilize protein structures. Finally, we demonstrate that intimate carbonyl interactions are described more completely as donor–acceptor orbital interactions rather than dipole–dipole interactions.
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
A Reduced Model Of Cavitation Physics For Use In Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonochemistry involves focusing acoustic energy through cavitation bubbles to increase chemical activity. The violent bubble collapses lead to temperatures of several thousand kelvin, which drive chemical reactions. In previous work, we gave a detailed computational model of a single bubble collapse, taking into account phase change, mass diffusion, heat diffusion and chemical reactions. All of these phenomena are important in determining the conditions at collapse. The present work involves development of a much simpler model that includes all the physics relevant to the determination of the reaction products. Comparisons with the more detailed computations are made; the reduced model is …
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Water Vapour, Sonoluminescence And Sonochemistry, Brian Storey, Andrew Szeri
Brian Storey
Sonoluminescence is the production of light from acoustically forced bubbles; sonochemistry is a related chemical processing technique. The two phenomena share a sensitive dependence on the liquid phase. The present work is an investigation of the fate and consequences of water vapour in the interior of strongly forced argon micro–bubbles. Due to the extreme nonlinearity of the volume oscillations, excess water vapour is trapped in the bubble during a rapid inertial collapse. Water vapour is prevented from exiting by relatively slow diffusion and non–equilibrium condensation at the bubble wall. By reducing the compression heating of the mixture and through primarily …
Double Layer In Ionic Liquids: Overscreening Versus Crowding, Martin Z. Bazant, Brian D. Storey, Alexei A. Kornyshev
Double Layer In Ionic Liquids: Overscreening Versus Crowding, Martin Z. Bazant, Brian D. Storey, Alexei A. Kornyshev
Brian Storey
We develop a simple Landau-Ginzburg-type continuum theory of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model captures overscreening from short-range correlations, dominant at small voltages, and steric constraints of finite ion sizes, which prevail at large voltages. Increasing the voltage gradually suppresses overscreening in favor of the crowding of counterions in a condensed inner layer near the electrode. This prediction, the ion profiles, and the capacitance-voltage dependence are consistent with recent computer simulations and experiments on room-temperature ionic liquids, using a correlation length of order the ion size.
Mixture Segregation Within Sonoluminescence Bubbles, Brian D. Storey, Andrew J. Szeri
Mixture Segregation Within Sonoluminescence Bubbles, Brian D. Storey, Andrew J. Szeri
Brian Storey
This paper concerns a relaxation of the assumption of uniform mixture composition in the interior of sonoluminescence bubbles. Intense temperature and pressure gradients within the bubble drive relative mass diffusion which overwhelms diffusion driven by concentration gradients. This thermal and pressure diffusion results in a robust compositional inhomogeneity in the bubble which lasts several orders of magnitude longer than the temperature peak or light pulse at the main collapse of the bubble. This effect has important consequences for control of sonoluminescence, gas dynamics, sonochemistry, and the physics of light production.
Dynamical Signature Of The Mott-Hubbard Transition In Ni(S,Se)(2), Yevgeniya Zastavker, Anke Husmann, Deborah Jin, Thomas Rosenbaum, X Yao, J Honig
Dynamical Signature Of The Mott-Hubbard Transition In Ni(S,Se)(2), Yevgeniya Zastavker, Anke Husmann, Deborah Jin, Thomas Rosenbaum, X Yao, J Honig
Yevgeniya V. Zastavker
The transition metal chalcogenide Ni(S,Se)2 is one of the few highly correlated, Mott-Hubbard systems without a strong first-order structural distortion that normally cuts off the critical behavior at the metal-insulator transition. The zero-temperature (T) transition was tuned with pressure, and significant deviations were found near the quantum critical point from the usual T1/2 behavior of the conductivity characteristic of electron-electron interactions in the presence of disorder. The transport data for pressure and temperature below 1 kelvin could be collapsed onto a universal scaling curve.
Polycyclic Aromatic Triptycenes: Oxygen Substitution Cyclization Strategies, Brett Vanveller, Derek J. Schipper, Timothy M. Swager
Polycyclic Aromatic Triptycenes: Oxygen Substitution Cyclization Strategies, Brett Vanveller, Derek J. Schipper, Timothy M. Swager
Brett VanVeller
The cyclization and planarization of polycyclic aromatic hydrocarbons with concomitant oxygen substitution was achieved through acid catalyzed transetherification and oxygen-radical reactions. The triptycene scaffold enforces proximity of the alcohol and arene reacting partners and confers significant rigidity to the resulting π-system, expanding the tool set of iptycenes for materials applications.
Chemical Activity In Yba2cu3o7 − Δ Across The Normal To Superconducting Phase Transition, Juana Vivó Acrivos
Chemical Activity In Yba2cu3o7 − Δ Across The Normal To Superconducting Phase Transition, Juana Vivó Acrivos
Faculty Publications, Chemistry
The Gibbs free enthalpy, chemical activity across the transition temperature to superconductivity, Tc in YBa2Cu3O7 − δ is obtained from reciprocally enhanced X-Ray absorbance, XAS and diffraction, XRD data near the Ba L3,2 edges' energy Ea, and orientations in the X-ray beam for preferred Miller indexed [HKL] planes' scattering, that are enhanced near Tc. The standard enthalpy and entropy for the formation of mixed normal metal/superconducting domains above Tc, determined individually across the two Ba L3,2 edges, to better than a percent accuracy: ΔH≠≥ = − 220 meV, and ΔS≠≥ = − 2 meV/K when 121 ≥ T ≥ 92 …