Physical Sciences and Mathematics Commons^™

Thermodynamic Study Of The Gaseous Molecules Al2n, Aln, And Al2n2 By Knudsen Cell Mass Spectrometry, Giovanni Meloni, Karl A. Gingerich

Chemistry Faculty Publications

The Knudsen effusion mass spectrometric method has been employed to measure the equilibrium partial pressures of the Al2N molecule over the AlN–Au–graphite system. Theoretical computations were carried out to determine the structure, molecular parameters, and thermodynamic properties of Al2N. The partial pressures have been combined with the calculated thermal functions to determine the atomization enthalpy,ΔaHo0, and enthalpy of formation,ΔfHo298.15, in kJ mol⁻¹, of 783.2±15 and 342.7±15 for Al2N, respectively. Upper values for the dissociation energy of AlN, Do0(AlN,g)⩽368±15 kJ mol−1, and for the atomization enthalpy of Al2N2, ΔaHo0(Al2N2,g)⩽1402 kJ mol−1 have been obtained. These results are discussed and …

Characterization Of Chimeric Lipopolysaccharides From Escherichia Coli Strain Jm109 Transformed With Lipooligosaccharide Synthesis Genes (Lsg) From Haemophilus Influenzae, Nancy J. Phillips, T. J. Miller, J. J. Engstrom, William Melaugh, R. Mclaughlin, M A. Apicella, B W. Gibson

Chemistry Faculty Publications

Previously, we reported the expression of chimeric lipopolysaccharides (LPS) in Escherichia coli strain JM109 (a K-12 strain) transformed with plasmids containing Haemophilus influenzae lipooligosaccharide synthesis genes (lsg) (Abu Kwaik, Y., McLaughlin, R. E., Apicella, M. A., and Spinola, S. M. (1991) Mol. Microbiol. 5, 2475–2480). In this current study, we have analyzed the O-deacylated LPS and free oligosaccharides from three transformants (designated pGEMLOS-4, pGEMLOS- 5, and pGEMLOS-7) by matrix-assisted laser desorption ionization, electrospray ionization, and tandem mass spectrometry techniques, along with composition and linkage analyses. These data show that the chimeric LPS consist of the complete E. coli LPS core …

Photoabsorption Spectra Of Argon Cation Clusters: Monte Carlo Simulations Using Many-Body Polarization, Jose A. Gascon, Randall W. Hall

Collected Faculty and Staff Scholarship

A simple, semiempirical model that includes many-body polarization is used to study the ground and excited stateproperties of Ar+N clusters (N=3–23) at 80 K. For purposes of comparison, a model that does not include many-body polarization is used to study clusters with N=3–27.Monte Carlo simulations are used to calculate the average properties of these clusters. The model is similar to one previously used to study argon cation clusters without many-body polarization. The photoabsorptionspectrum is in good agreement with experiment; in particular, the photoabsorptionspectra for cluster sizes 4–10 do not show the blueshift that is seen with models that do not …

Solidification/Stabilization Of Lead And Chromium With The Aid Of Bagasse As An Additive To Portland Cement, Michael A. Janusa

Faculty Presentations

No abstract provided.

Aqueous Equilibria: Acids, Bases, And Solubility. A General Chemistry Laboratory Experiment, Michael A. Janusa

Faculty Publications

We refer to two major types of general chemistry freshman laboratory experiments: discovery and cookbook. The typical Freshman enrolled in general chemistry has the skills to perform an experiment that is somewhere between cookbook and discovery, and we have developed a laboratory experiment that is midway between these extremes. This experiment aids the student's understanding of the concept of aqueous equilibria. In this experiment, students are asked to prepare and measure the pH of a variety of acidic and basic solutions. Students are also asked to calculate pH values from literature dissociation constants and dissociation constants from their experimental pH …

Solidification / Stabilization Of Lead With The Aid Of Bagasse As An Additive To Portland Cement, Michael A. Janusa

Faculty Publications

Solidification/stabilization (S/S) of hazardous waste is a widely used technology; therefore, it is crucial to evaluate its effectiveness and make attempts to improve the technique. A better matrix for S/S of hazardous waste was designed that is effective and economically feasible. This was accomplished by adding bagasse (byproduct of milling or diffusing sugar cane) to the waste/cement matrix. Lead nitrate was used as the model heavy metal waste with a 10or 15% lead by weight to cement loading. Samples were cured for 7, 14, and 28 days at 24°C. Samples containing bagasse typically resulted in TCLP (modified) extract lead concentrations …

Palladium-Catalyzed Carboxylative Coupling Of Allylstannanes And Allyl Halides, Russell J. Franks

Faculty Publications

A three-component carboxylative coupling between allyl halides, allylstannanes, and CO2 to produce allyl esters is catalyzed by Pd and Pt phosphine complexes. Allyl chloride and allyltributylstannane are thus converted to propenyl butenoate in excellent yield. Cross coupling of two different allyl components produces a nearly statistical mixture of all four possible esters. Tentative mechanistic pathways for the catalytic reaction are proposed.

The Influence Of The Isomerization Reactions On The Soybean Oil Hydrogenation Process, Zeljko D. Cupic

Zeljko D Cupic

No abstract provided.

Unified Matrix Processor Design For Fct-Iv And Fst-Iv Hartley Based Transforms, Philadelphia University

Philadelphia University, Jordan

No abstract provided.

Behavior Of Grain Boundary Resistivity In Metals Predicted By A Two-Dimensional Model, Rand Dannenberg, Alexander H. King

Alexander H. King

The behavior of a model for the specific grain boundary resistivity in metallic bamboo conductor lines is developed and compared to other theoretical treatments, and to experiment. The grain boundary is modeled as an array of scatterers on a plane. The scatterers are called “vacancy-ion” complexes, in which the vacancy represents the boundary free volume, and the ion is an atom adjacent to the vacancy. Three cases are investigated, that of noninterfering scatterers, a continuum of interfering scatterers, and discrete interfering scatterers. The approximations used lead to a specific grain boundary resistivity ∼10−16 Ω m2 for aluminum, in agreement with …

Structural Change Of The Mn Cluster During The S2→S3 State Transition Of The Oxygen-Evolving Complex Of Photosystem Ii. Does It Reflect The Onset Of Water/Substrate Oxidation? Determination By Mn X-Ray Absorption Spectroscopy, Wenchuan Liang, Theo A. Toelofs, Roehl M. Cinco, Annette Rompel, Matthew J. Latimer, Edward Yu, Kenneth Sauer, Melvin P. Klein, Vittal K. Yachandra

Edward Yu

The oxygen-evolving complex of Photosystem II in plants and cyanobacteria catalyzes the oxidation of two water molecules to one molecule of dioxygen. A tetranuclear Mn complex is believed to cycle through five intermediate states (S0−S4) to couple the four-electron oxidation of water with the one-electron photochemistry occurring at the Photosystem II reaction center. We have used X-ray absorption spectroscopy to study the local structure of the Mn complex and have proposed a model for it, based on studies of the Mn K-edges and the extended X-ray absorption fine structure of the S1 and S2 states. The proposed model consists of …

Sixth Pacific Polymer Conference, Ppc-6 Guangzhou, China, Otto Vogl, Xu Mao

Otto Vogl

No abstract provided.

Electronic Properties Of Small Neutral And Charged Beryllium Clusters, Andrew M. Kolchin, Randall W. Hall

Collected Faculty and Staff Scholarship

We determine the atomic and electronic structures for neutral and singly positively chargedberyllium clusters containing from two to six atoms using density functional theory in the local spin density approximation. Ions are moved with a steepest descent method and the electronic wave functions optimized using a fictitious dynamics with simulated annealing, as conceived by Car and Parrinello [Phys. Rev. Lett. 55, 2471 (1985)]. Shell-like orbitals, filling angular momentum states in the order: 1s 1p 2s 1d are obtained. We employ a Mulliken population analysis using an atomic basis to examine how the shell orbitals arise from atomic orbitals. This analysis …

Abstracts Of Student-Faculty Publications

The Corinthian

Abstracts of Student-Faculty Publications

Spin-Exchange Term In The Solvent Equation Of State Near The Critical Point For Electron Transfer Reactions, Juana Vivó Acrivos

Faculty Publications, Chemistry

Phenomenological Equations of State (EOS) for fluids near their critical point have been obtained using literature compression factor data, Zc = Pc Vc/(n R Tc) = 0.40 to 0.10 in Table I (Pc, Vc/n, Tc are the pressure, volume per n mole, and the absolute temperature of the fluid at the critical point). The objective is to explain the deviations from the van der Waals value, Zc(vdW) = 3/8 (-70 % for molten Se and alkali metals up to 6 % for molten Pb, Hg, and In) by including in the commonly used phenomenological thermodynamic relations a term which explicitly …

Solid State Phase Transitions Characterized By Esr And Xas, Juana Vivó Acrivos

Faculty Publications, Chemistry

Measurements of the relaxation time,  of electron systems to a disturbance, by two different spectroscopic methods are examined in detail, with the purpose to establish how the presence of fluctuations near a solid state phase transition are made evident in insulators, conductors and superconductors. The absolute temperature and the relaxation time determine the thermodynamic stability of the electronic system near a phase transition by the Uncertainty Principle. At a given temperature T, Landau and Lifshitz obtain the stability from the lower limit of the uncertainty in entropy in units of the Boltzmann constant, S/kB << 1 when T  >> 3.82 K ps. Magnetic resonance …

Kinetics Of The Photolysis Of Benzenetricarbonylchromium(0) In Chloroform, Leslianna Federici, Patrick E. Hoggard

Chemistry and Biochemistry

In contrast to the photolysis of Cr(CO)₃(C₆H₆) in nonhalogenated solvents, in which the products are CrL(CO)₂(C₆H₆) in the presence of a donor L, or Cr(CO)₆ and C₆H₆ if no donor is present, the photo-reaction in chloroform yields CrCl₃. No significant portion of the reaction occurs through absorption of 254nm light by CHCl₃• The quantum yield is 1.4, consistent with a mechanism in which several radicals are formed upon chlorination of the chromium, which then cause further decomposition of the reactant. …

Determination Of Thermal Maturity And Organic Matter Type By Principal Components Analysis Of The Distributions Of Polycyclic Aromatic Compounds, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The thermal maturity and organofacies sensitivity of polycyclic aromatic compound (PAC) distributions was explored by examination of the aromatic fractions of solvent extracts from a diverse set of 53 shales, coals and kerogen macerals which have undergone either natural or artificial maturation and which represent all three principal sedimentary organic matter (OM) types. Systematic changes with maturation were observed in the following groups of isomers: tri- and tetramethylnaphthalenes, methyl- and dimethylphenanthrenes, methyl- and dimethyldibenzothiophenes, methylpyrenes, and methylchrysenes. The maturity differences were quantified by mathematical ratios of the relative concentrations of the more thermally stable isomers to the less stable, on …

Spin-Exchange Term In The Solvent Equation Of State Near The Critical Point For Electron Transfer Reactions, Juana Vivó Acrivos

Juana Vivó Acrivos

Phenomenological Equations of State (EOS) for fluids near their critical point have been obtained using literature compression factor data, Zc = Pc Vc/(n R Tc) = 0.40 to 0.10 in Table I (Pc, Vc/n, Tc are the pressure, volume per n mole, and the absolute temperature of the fluid at the critical point). The objective is to explain the deviations from the van der Waals value, Zc(vdW) = 3/8 (-70 % for molten Se and alkali metals up to 6 % for molten Pb, Hg, and In) by including in the commonly used phenomenological thermodynamic relations a term which explicitly …

Solid State Phase Transitions Characterized By Esr And Xas, Juana Vivó Acrivos

Juana Vivó Acrivos

Measurements of the relaxation time,  of electron systems to a disturbance, by two different spectroscopic methods are examined in detail, with the purpose to establish how the presence of fluctuations near a solid state phase transition are made evident in insulators, conductors and superconductors. The absolute temperature and the relaxation time determine the thermodynamic stability of the electronic system near a phase transition by the Uncertainty Principle. At a given temperature T, Landau and Lifshitz obtain the stability from the lower limit of the uncertainty in entropy in units of the Boltzmann constant, S/kB << 1 when T  >> 3.82 K ps. Magnetic resonance …

Theories Of The Origin And Early Evolution Of Life, David A. Dewitt

Faculty Publications and Presentations

After the theory of spontaneous generation was discredited, only religious explanations were offered to explain the origin of life. Alexander Oparin (1894-1980), an atheist, suggested that natural chemical reactions produced biological molecules that came together to form the first living thing. Later, Stanley Miller tested this hypothesis and produced chemical "building blocks" but not life itself. In spite of much progress, there is still no clear consensus on how life originated on Earth. Some scientists are even looking to outer space for the origin of life.

A Small-System Ensemble Monte Carlo Simulation Of Supersaturated Vapor: Evaluation Of Barrier To Nucleation, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A small-system grand canonical ensemble Monte Carlo method is developed to evaluate cluster size distribution and barrier to the nucleation in a supersaturated Lennard-Jones vapor. The theoretical foundation is a physical cluster theory in which the Stillinger cluster is used as a prototypical physical cluster. Using method of Mayer’s cluster expansion, the cluster–vapor interaction is effectively taken into account. From a separate canonical ensemble Monte Carlo simulation using a test particle method, the averaged volume of the cluster is obtained and is also incorporated in the small-system ensemble simulation. By this implementation our simulation is computationally more efficient compared to …

Crystal And Magnetic Structures Of Lani₅₋ₓmnₓ, Chiu-Ying Tai, G. K. Marasinghe, Oran Allan Pringle, William Joseph James, Muguo Chen, William B. Yelon, I. Dubenko, Naushad Ali, Ph. I'Héritier

Physics Faculty Research & Creative Works

The crystallographic and magnetic properties of LaN_5-xMn_x with x = 1, 1.5, and 2, have been investigated using x-ray and neutron diffraction, vibrating sample magnetometer and superconducting quantum interference device measurements. All the samples crystallize in the hexagonal CaCu₅-type (P6/mmm) structure. Manganese atoms preferentially occupy the 3 g site in the LaNi₅ structure. The bulk magnetization of the LaNi_5-xMn_x powder samples decreases rapidly as nickel is replaced by manganese. A ferrimagnetic model is applied to describe the magnetic structure of the LaNi_5-xMn_x samples for x = 1.5 and …

Hammett Correlations Of The Sulfonamide Proton Chemical Shift In A Series Of N-(Substituted Aryl)-P-Toluenesulfonamides, Frank L. Setliff, Tyson K. Spradlin

Journal of the Arkansas Academy of Science

No abstract provided.

Heavily Fluorinated Sugar Analogs, Stephen G. Dimagno

Chemistry Department: Faculty Publications

Heavily fluorinated Sugar analogs of formula

wherein R₁ is selected from alkyl, alkenyl, aryl, CH₂OH, -CH₂-O-alkyl, -CH₂-O-aryl, -CH₂OPO₃H, -CH₂-O-carbohydrate, -CH₂-NH-peptide, or -CH₂-O-peptide; wherein R₂ is selected from hydroxy, -O-carbohydrate, -NH-peptide,

wherein R₃ is selected from H, halogen, lower alkyl, lower alkenyl, lower haloalkyl, lower haloalkenyl, amino, mono- or di-lower alkylamino; wherein R₄ is Selected from amino, hydroxy, alkoxy, or halogen; and wherein R₅ is H or amino. The compounds of formula (I) are useful as antiviral and antineoplastic agents …

On-Road Remote Sensing Of Automobile Emissions In The Los Angeles Area: Year 1, Gary A. Bishop, Sajal S. Pokharel, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Rsd Versus Im240 Fleet Average Correlations, Sajal S. Pokharel, Donald H. Stedman, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

Analysis Of Remote Sensing Data For Development Of I/M Program Evaluation Protocols, Sajal S. Pokharel, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

New Emission Test Would Cost More, Do Less, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Solvent As Electron Donor:  Donor/Acceptor Electronic Coupling Is A Dynamical Variable, Edward W. Castner Jr., Darcy Kennedy '00, Robert J. Cave

All HMC Faculty Publications and Research

We combine analysis of measurements by femtosecond optical spectroscopy, computer simulations, and the generalized Mulliken−Hush (GMH) theory in the study of electron-transfer reactions and electron donor−acceptor interactions. Our focus is on ultrafast photoinduced electron-transfer reactions from aromatic amine solvent donors to excited-state acceptors. The experimental results from femtosecond dynamical measurements fall into three categories:  six coumarin acceptors reductively quenched by N,N-dimethylaniline (DMA), eight electron-donating amine solvents reductively quenching coumarin 152 (7-(dimethylamino)-4-(trifluoromethyl)coumarin), and reductive quenching dynamics of two coumarins by DMA as a function of dilution in the nonreactive solvents toluene and chlorobenzene. Applying a combination of molecular …