Physical Sciences and Mathematics Commons^™

The Influence Of Cation Size Upon The Infrared Spectrum Of Carbon Monoxide Adsorbed On Platinum Electrodes, Mark Anderson, Jimin Huang

Mark R. Anderson

The infrared spectrum of carbon monoxide adsorbed on polycrystalline platinum electrodes in the presence of acetonitrile solutions is examined. Acetonitrile solutions provide a wide double layer region (approximately 4 V) in which to investigate the observed potential dependence of the infrared peak position. The wider window allows for better comparisons of experimental data with theoretical predictions than those which are available from measurements conducted in aqueous solutions. It is found that (i) near-monolayer surface coverage can be obtained from solutions saturated with CO, (ii) the coverage stays constant over roughly the entire double layer region, (iii) the CO adsorbs to …

Spectroelectrochemical Analysis Of Spontaneously Adsorbed Monolayers, Marilyn O'Grady, Mark Anderson

Mark R. Anderson

No abstract is currently available.

Measurements Of Deuteron Threshold Electrodisintegration: A Probe Of Short-Range Meson Exchange, K S. Lee, W Schmitt, H Baghaei, S Churchwell, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson, K Wang

Gerald Alvin Peterson

The threshold electrodisintegration of the deuteron was measured with good energy resolution to a maximum four-momentum transfer squared of 42 fm-2. The data are compared with meson exchange calculations that show sensitivity to the choice of exchange-current form factor, the nucleon electromagnetic form factors, and the nucleon-nucleon potential. While conventional theories can give a reasonable description of the data, comparison of the data with quark cluster calculations shows poor agreement.

An Analytical Representation Of The Lowest Potential Energy Surface For The Reaction O(3 P)+Hcl (X  1Σ+)→Oh(X  2Π)+Cl(2 P), H. Koizumi, George C. Schatz, Mark S. Gordon

Mark S. Gordon

We present a new analytical representation of the lowest 3 A‘ energy surface for the reaction O(3 P)+HCl(X  1Σ+)→OH(X  2Π)+Cl(2 P). This surface is derived by fitting a b i n i t i o calculations, and adjustments are made to the barrier height so that rate constants derived from accurate quantum scattering calculations match the room temperature thermal rate constants. Contributions to thermal and state resolved rate constants arising from reaction on the lowest 3 A’surface are also considered. Comparisons of thermal and state resolved rate constants with experiment are good except at high temperature where the 3 A’ …

How To Pick Out The Integers In The Rationals - An Application Of Number-Theory To Logic, D. Flath, Stan Wagon

Stan Wagon, Retired

No abstract provided.

A Collaborative Summer Research Program For Community College Students, Chris Craney, Franklin Dehaan

Chris L. Craney

While the benefits of undergraduate research are well established, little attention has been paid toward involving community college students in such research. This paper describes a five-year-experience with a summer research program that includes Los Angeles area community college students working side-by-side with Occidental College students and faculty.

Use Of A Commercially Available Flight Simulator During Aircrew Performance Testing, S. A. Shappell, B. J. Bartosh

Scott Shappell

The Conformational Potential Energy Surface Of Glycine: A Theoretical Study, Jan H. Jensen, Mark S. Gordon

Mark S. Gordon

The conformational potential energy surface of nonionized glycine has been studied by using ab initio (6-310*, ST0-20) and semiempirical (AM1, PM3) methods. The MP2/6-31G*/ /RHF/6-310* potential energy surface was then used to calculate the Boltzmann equilibrium distribution and kinetics of conformational interconversion at various temperatures. The results of this study are compared to previous computational and experimental investigations of gas-phase glycine.

Structures And Bonding Of Group Iv Sulfur And Oxygen Propellane Derivatives, Kiet A. Nguyen, Marhsall T. Carroll, Mark S. Gordon

Mark S. Gordon

The RHF, ROHF, and GVB structures and energetics of group IV 2,4,5-trioxa[l.l.l]metallapropellanes, 2,4,5- trithia [ l.l.l]metallapropellanes, and their bicyclopentane analogues have been determined from ab initio molecular orbital theory by using both the 6-31G(d) basis set for all-electron calculations and the valence basis set with effective core potentials (ECP) developed by Stevens, Basch, and Krauss. Although they have extremely short bridgehead distances, these species possess fairly large natural orbital occupation numbers in the lowest unoccupied molecular orbitals, indicating significant diradical character. Structures and other properties determined by ECP calculations are in good agreement with the 6-31 G(d) all-electron calculations.

Elastic Magnetic Electron Scattering From ' C At Q2= 1 Gev2/C, R A. Miskimen, H Baghaei, M Frodyma, R S. Hicks, K S. Lee, Gerald Alvin Peterson

Gerald Alvin Peterson

Electron scattering from C was measured at a momentum transfer of 5.08 fm . No electron events were observed in the vicinity of the elastic peak, giving an upper limit for the elastic cross section of 1.2 x 10 cm /sr with a confidence level of 90%. At this momentum transfer, the square of the elastic M1 form factor apparently continues to fall exponentially with q. Comparison of the data with shell-model calculations indicates that admixtures of 2hu configurations in the C ground state cannot entirely explain the high-q enhancement of the Ml form factor relative to 1p-shell calculations.

The Relevance Of Fouling Models To Crossflow Microfiltration, Caroline Lubert, R. Wakeman, E. Tarleton

Caroline P Lubert

No abstract provided.

Madagascar: Island Of Ghosts, Nat Quansah

Nat Quansah

No abstract provided.

Spectroelectrochemical Analysis Of Metal Surfaces Modified With Thin Organic Films, Marilyn O'Grady, Mark Anderson

Mark R. Anderson

No abstract is currently available.

The Use Of Kindergarten Screening Scores To Identify The Need For Reading Intervention: A Logit Regression Study, Jayn Crail, John Fraas

John W. Fraas

No abstract provided.

First-Principles Study Of Phase Stability In Cu-Zn Substitutional Alloys, P. E. A. Turchi, M. Sluiter, F. J. Pinski, Duane D. Johnson, D. M. Nicholson, G. M. Stocks, J. B. Staunton

Duane D. Johnson

A parameter-free approach to phase stability in Cu-Zn substitutional alloys is shown to describe order-disorder phenomena and structural transformations with remarkable accuracy. The method is based on a multiple-scattering description of the electronic structure properties of the random alloy. Configurational order is treated within the generalized perturbation method and the concentration-functional theory. Thermodynamical properties of α and β brasses are derived from the cluster variation method. This advanced scheme is of general validity and is expected to yield similarly accurate results for other Hume-Rothery alloys.

Predicted Enthalpies Of Formation For Methyl-Substituted Silaethylenes And Disilenes, Jerry A. Boatz, Mark S. Gordon

Mark S. Gordon

Enthalpies of formation of the methyl-substituted silaethylenes (CH3).H2_,Si=CH2 (n = 1, 2) and disilenes (CH3),.H~i=Si(CH3),H:~-m (n, m = Q-2) are predicted by using isodesmic reactions which relate the compound of interest to the parent silaethylene (H2Si=CH2) or disilene (H~i=SiH2), for which accurate enthalpies of formation have recently been determined. In turn, the enthalpies of formation of these methyl-substituted compounds are used in conjunction with homodesmic reactions to reevaluate the enthalpies of formation of the silicon-substituted cyclobutenes C.Si4-0H6 (n = Q-4).

Equatorial Thermospheric Wind Changes During The Solar Cycle: Measurements At Arequipa,Peru From 1983 To 1990, M. A. Biondi, J. W. Meriwether, Bela G. Fejer, S. A. Gonzalesz, D. C. Hallenbeck

Bela G. Fejer

Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over ∼2/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the wind patterns, as well as any additional changes introduced by the progression of the solar cycle. The measured seasonal variations in the wind patterns are more pronounced than the solar cycle variations and are more readily understandable in terms of the …

Reproducibility And Responsiveness Of Health Status Measures. Statistics And Strategies For Evaluation, Paula Diehr, Richard Deyo

Paula Diehr

Before being introduced to wide use, health status instruments should be evaluated for reliability and validity. Increasingly, they are also tested for responsiveness to important clinical changes. Although standards exist for assessing these properties, confusion and inconsistency arise because multiple statistics are used for the same property; controversy exists over how to measure responsiveness; many statistics are unavailable on common software programs; strategies for measuring these properties vary; and it is often unclear how to define a clinically important change in patient status. Using data from a clinical trial of therapy for back pain, we demonstrate the calculation of several …

Stabilization Of Β Positive Charge By Silicon, Germanium, Or Tin, Kiet A. Nguyen, Mark S. Gordon, Gen-Tai Wang, Joseph B. Lambert

Mark S. Gordon

Ab initio molecular orbital theory is used to study the β effect of carbon, silicon, germanium, or tin on the carbenium ions in H2R'MCH2CHR+ (R' = H; R = H, CH3). The relative stabilization energies of carbenium ions provided by M (M = C, Si, Ge, Sn) were determined by calculating the energy change in an isodesmic reaction using MP2/3-21G(d) (at SCF /3-21G* geometries) and MP2/6-31G(d) (at SCF /6- 31G(d) geometries) wave functions. The magnitude of the β effect is predicted to increase in the order C < Si < Ge < Sn. For R = H, the nonvertical cyclic structure is favored for the cations, whereas methyl substitution appears to stabilize the vertical acyclic arrangement.

Ab Initio Study Of Some Methylene And Silylene Insertion Reactions, David R. Gano, Mark S. Gordon, Jerry A. Boatz

Mark S. Gordon

The theoretical barriers and reaction energetics have been determined, using ab initio calculations at the MP4/6-3IG(d) level, with 3-2IG* geometries, for the insertions of methylene and silylene into the X-Y bonds of ethane, methylsilane, disilane, and cyclopropane and into the X-H bonds of disilane and ethane. A correlation was observed between barrier heights and lengths of substrate bonds. The largest barriers were observed for methylene and silylene inserting into the C-C bonds of ethane. The barriers became successively lower for the C-Si and Si-Si bonds. Steric interactions thus appear to be a major factor in determining barrier heights. The observed …

Nature Of The Si-N Bond In Silatranes, Mark S. Gordon, Marshall T. Carroll, Jan H. Jensen, Larry P. Davis, Larry W. Burggraf, R. Martin Guidry

Mark S. Gordon

Both ab initio and semiempirical calculations are used to investigate the structure and bonding in substituted silatranes. In agreement with gas-phase experiments, which fmd Si-N distances that are 0.25-0.35 A longer than those in the crystal phase, the Si-N distance (for example, in methylsilatrane) is predicted to be much larger than that observed in the crystal. Nonetheless, a bond critical point is found between Si and N, suggesting the existence of an Si-N bond in these compounds. It is found that the energy cost for constraining the Si-N distance in hydroxysilatrane to a value similar to that observed in the …

Average Vertical And Zonal F-Region Plasma Drifts Over Jicamarca, Bela G. Fejer, E. R. De Paula, S. Gonzalez, R. F. Woodman

Bela G. Fejer

The seasonal averages of the equatorial F region vertical and zonal plasma drifts are determined using extensive incoherent scatter radar observations from Jicamarca during 1968–1988. The late afternoon and nighttime vertical and zonal drifts are strongly dependent on the 10.7-cm solar flux. We show that the evening prereversal enhancement of vertical drifts increases linearly with solar flux during equinox but tends to saturate for large fluxes during southern hemisphere winter. We examine in detail, for the first time, the seasonal variation of the zonal plasma drifts and their dependence on solar flux and magnetic activity. The seasonal effects on the …

Boundary C1, Α Regularity For Variational Inequalities, Fang-Hua Lin, Yi Li

Yi Li

No abstract provided.

Chelation Of 2-Substituted 1-Lithoxides: Structural And Energetic Factors Of Relevance To Synthetic Organic Chemistry., Michael Nichols, Andrew Mcphail, Edward Arnett

Michael A Nichols

No abstract provided.

Three-Point Correlations In Driven Diffusive Systems With Ising Symmetry, Beate Schmittmann, R. K. P. Zia

Beate Schmittmann

For equilibrium systems with Ising symmetry, the three-point correlation function is always zero above criticality. When a lattice-gas version of this system is driven to a nonequilibrium steady state, this correlation becomes nontrivial. Its dominant large-scale behavior is found to be a consequence of both the manifest breaking of Ising symmetry by the driving force and the more subtle violation of the fluctuation-dissipation theorem.

Handling Constraints In Genetic Algorithms, Cezary Janikow, Zbigniew Michalewicz

Cezary Janikow

Characterization Of Adsorption By Electrochemical And Spectroscopic Methods, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

Parallel Algorithms For Graph Problems, Panagiotis T. Metaxas

Panagiotis T Metaxas

PhD Thesis about computing connected components in parallel.

Systematic Survey Of Cyclic Silicon-Oxygen Compounds, Michael W. Schmidt, Kiet A. Nguyen, Mark S. Gordon, John A. Montgomery Jr.

Mark S. Gordon

Compounds with 0, 1, 2, or 3 oxygen atoms bridging 2 silicon atoms are investigated by ab initio calculations. Two such series of compounds, with and without a formal central Si-Si bond, are considered. The triplet states of the former set are also examined. For some of these compounds, the present calculations represent the first time they have been examined at a sufficiently rigorous level of theory. For the compounds that are formally bonded, this level is two configuration SCF (TCSCF) for singlets and ROHF for triplet states, using split valence polarized basis sets. The main result is that no …

A Theoretical Study Of Some Reactions Of Hcsi-, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

The ions HCSi- and H2CSiH- produced in recent flowing afterglow experiments are characterized structurally. Reactivity of the former ion with four molecules (C02, OCS, CS2, S02) is examined. Three of these species react in a sequence of intermediates of cyclic followed by acyclic structures, before reaching the final products.