Physical Sciences and Mathematics Commons^™

The Reduction Of Oxygen To Hydrogen Peroxide At The Poly(O-Phenylenediamine)-Filmed Electrode, Zhaoe Lu, Tiangeng Zhong, Guanyong Zhang

Journal of Electrochemistry

The poly(o-phenylenediamine)(PPD)filmed graphite electrode was formed byelectro-polymerization of o-phenylenediamine in acidified(pH=1)0.2 mol·L-1 Na_2SO_4 solutionusing the cyclic voltammetric methed. The catalytic effect of the electrcareduction of oxygen in acidsolution was demonstrated by the voltammogram of the electrede in the oxygen saturated acid solutionof Na_2SO_4. The current efficiency of the reduction of oxygen to hydrogen peroxide was determined byIhe electrolysis in a divided cell under the condition of constant current. The various effectsinfluencing the accm ulation of H_2O_2 in the catholyte were discussed.

The Formation And Voltammetric Behavior Of Manganese Chlorophyll, Qingdong Qiao

Journal of Electrochemistry

The formation and voltam metric behavior of manganese chlorophyll werestudied.The electrochemical red uction mechanism of Mn chlorophyll a (MnChla)in aqueous solutionwas investigated and discussed.During the electrored uction of MnChla ,the porphyrin ring was singlyreduced with 2 electrons and the Mn￣(2+) ion remained its original state,The reduction rate constant k_m=0.36/s was gained.

Whaling Error, Robert L. Brownell Jr.

United States Department of Commerce: Staff Publications

You published recently (Nature 374, 587; 1995) a report headed "Error re-opens 'scientific' whaling debate".

The error in question, however, relates to commercial whaling, not to scientific whaling. Although Norway cites science as a basis for the way in which it sets its own quota. scientific whaling means something quite different. namely killing whales for research purposes. Any member of the International Whaling Commission (IWC) has the right to conduct a research catch under the International Convention for the Regulation of Whaling. 1946. The IWC has reviewed new research or scientific whaling programs for Japan and Norway since the …

Nanoscale Visualization And Control Of Ferroelectric Domains By Atomic Force Microscopy, Oleg Kolosov, Alexei Gruverman, Jun Hatano, Koichiro Takahashi, Hiroshi Tokumoto

Alexei Gruverman Publications

The nanoscale visualization and control of domain structure with atomic force microscopy (AFM) in the ferroelectric crystal guanidinium aluminum sulfate hexahydrate is reported. The origin of the domain contrast in the topographic of AFM images is explained by the piezoelectric deformation of the crystal surface in the internal electric field. The domain structure was modified by applying a voltage to the conductive AFM tip. The dynamics of domain growth has been directly observed for the first time with a resolution of 10 nm.

State-Selected Ion-Molecule Reactions: Statistical Calculations With Constraints, Cornelis J. Uiterwaal, J. Van Eck, A. Niehaus

C.J.G.J. Uiterwaal Publications

For the two reactive systems, NH₃⁺(E_int)+N H₃→NH₄⁺+NH₂ and H₂⁺ (E_int)+H₂→H₃⁺ + H, for which the relative cross sections were measured earlier in our group for E_c.m.≈40 meV we calculated the relative cross section as a function of internal energy using the statistical Rice– Ramsperger–Kassel–Marcus (RRKM) theory that implicitly conserves total energy and total angular momentum. We found satisfactory agreement between theory and experiment by imposing rather mild constraints upon the loose transition state configuration. These constraints involve …

Infrared Emission And Dynamics Of Outlfows In Late-Type Stars, Željko Ivezić, Moshe Elitzur

Physics and Astronomy Faculty Publications

The dynamical structure and infrared emission of winds around late-type stars are studied in a self-consistent model that couples the equations of motion and radiative transfer. Thanks to its scaling properties, both the dynamics and IR spectrum of the solution are fully characterized by τ_F, the flux-averaged optical depth of the wind. Five types of dust grains are considered: astronomical silicate, crystalline olivine, graphite, amorphous carbon and SiC, as well as mixtures. Analysis of infrared signatures provides constraints on the grain chemical composition and indications for the simultaneous existence of silicate and carbon grains. The abundances of crystalline …

Ph.D. Thesis Proprosal: Transportable Agents, Robert S. Gray

Computer Science Technical Reports

One of the paradigms that has been suggested for allowing efficient access to remote resources is transportable agents. A transportable agent is a named program that can migrate from machine to machine in a heterogeneous network. The program chooses when and where to migrate. It can suspend its execution at an arbitrary point, transport to another machine and resume execution on the new machine. Transportable agents have several advantages over the traditional client/server model. Transportable agents consume less network bandwidth and do not require a connection between communicating machines -- this is attractive in all networks and particularly attractive in …

Use Of Fractals And Kinetic Equations To Model Thermally Induced Hillock Formation And Growth In Thin Metal Films, Joseph Chaiken, Jerry Goodisman

Chemistry - All Scholarship

We investigated the applicability of a model based on fractals and the Smoluchowski kinetic equations to describe hillock formation in thin metal films. We have previously used this model to analyze cluster and ultrafine particle production. We show how to extract two parameters from measured hillock size distributions which may reveal the scaling of the mobility of clusters and vacancies in films with varying hillock size. On the basis of our application of this model to certain data taken from the literature, the model shows considerable potential for being able to provide an internally consistent quantitative basis for monitoring thermally …

Spin-Polarized Photoemission Studies Of The Exchange Splitting Of The Gd 5d Electrons Near The Curie Temperature, Dongqi Li, J. Pearson, S.D. Bader, D.N. Mcilroy, C. Waldfried, Peter A. Dowben

Peter Dowben Publications

Spin-polarized photoemission was employed to investigate the temperature dependence of the exchange splitting of Gd(0001) for both the surface state near the Fermi level E_F and the 5d bulk bands. The bulk bands at 1–2 eV below E _F show Stoner-like behavior where two peaks with opposite spin polarization shift toward each other as the temperature increases. In contrast, the temperature dependence of the surface state indicates spin-mixing behavior due to fluctuating local moments. These differences are attributed to the degree of itinerancy of the 5d electrons in the two cases.

Cosmological Histories For The New Variables Of Ashtekar, Seth Major, L. Smolin

Articles

Histories and measures for quantum cosmology are investigated through a quantization of the Bianchi type IX cosmology using path integral techniques. The result, derived in the context of Ashtekar variables, is compared with earlier work.

Transitions In Masculinity And Hemingway's Developed "Code", Daniel Polk

Honors Theses

The "Hemingway Code" is much more than two words that fit nicely together for a scholar's usage; the words signify a much deeper championing of masculinity, almost a haunting presence. For Ernest Hemingway living life every day, every moment with its fullest masculine fervor, became an obsession, a never-ending quest to be at one with the attitude of never complaining, never crying out, panicking, thinking too much, or regretting. To live a manly life in a series of tactical victories, performed with steadfast ritualistic mannerisms, is to embody masculinity, and therefore the "Hemingway Code."

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Electrocrystallization Of Strongly Adherent Brushite Coatings On Prosthetic Alloys (Continuation), Jody G. Redepenning

Chemistry Department: Faculty Publications

An electrolytic method for providing bone-emulating, phosphate coatings on prosthetic appliances. Such coatings serve to enhance bone furation after implantation of the appliances. The method of the invention is an electrolysis process wherein the appliance to be coated is immersed in a phosphate-containing electrolyte to serve as the cathode of the electrolysis process. When current is appIied to the electrolysis cell, the electrolyte solution, which includes calcium ions and dihydrogen phosphate ions, is caused to rapidly increase in (localized) pH proximate the cathode element. The localized pH increase creates a supersaturated local condition causing less soluble calcium phosphate salts to …

Magnetic Force Microscopy Of The Submicron Magnetic Assembly In A Magnetotactic Bacterium, R. B. Proksch, T. E. Schäffer, B. M. Moskowitz, E. D. Dahlberg, Dennis A. Bazylinski, Richard B. Frankel

Physics

A magnetic force microscope (MFM) was used to image topography and magnetic forces from a chain of submicron single magnetic domain particles produced by and contained in isolated magnetotactic bacteria. The noncontact magnetic force microscope data were used to determine a value for the magnetic moment of an individual bacterial cell, of order 10⁻¹³ emu, consistent with the average magnetic moment of bacteria from the same sample, obtained by superconducting quantum interference device magnetometry. The results represent the most sensitive quantification of a magnetic force microscope image to date.

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Dna Interstrand Crosslinking Efficiencies, Sequence Preferences, And Organic Syntheses Of Diepoxide Metabolites In Fixation, Sara Charnecki

Honors Theses

Molecular Basis of Cancer: Cancer, a disease that has had a devastating and frightening impact on current society in the midst of a chemical revolution, represents a class of diseases comprising over 200 known types that affect various regions of the mammalian body (Farmer & Walker, 1985). This disease strikes randomly and is often diagnosed after the disease has progressed beyond present treatment capabilities. Cancer is the result of irregularities in growth, reproduction, and differentiation of cells due to pennanent flaws in genetic information. Mutations caused by environmental factors can be compounded over time to cause carcinomas of different tissues. …

Bandwidth And Additive Bandwidth Of Graphs, Maria Kujawski

Honors Capstone Projects and Theses

No abstract provided.

A Hydrologic Analysis Of Government Island, Oregon, Scott Gregory Bittinger

Dissertations and Theses

Government Island, located in the Columbia River approximately 16 km (10 mi) upstream of the confluence with the Willamette River, is a wetland mitigation site prompted by expansion of the southwest quadrant of Portland International Airport. The purpose of the study is to predict water levels in two enclosed lowland areas, Jewit Lake and Southeast Pond, based on levels of the Columbia River, precipitation, and evapotranspiration. Mitigation is intended to convert 1.13 km2 (237 acres) of seasonally flooded wetland to 1.27 km2 (267 acres) of semi-permanently flooded wetland and seasonally flooded wetland. Flooding of the wetland is most likely to …

The Parser Converter Loader: An Implementation Of The Computational Chemistry Output Language (Ccol), Donald Randall Abel

Dissertations and Theses

A necessity of managing scientific data is the ability to maintain experimental legacy information without continually modifying the applications that create and use that information. By facilitating the management of scientific data we hope to give scientists the ability to effectively use additional modeling applications and experimental data. We have demonstrated that an extensible interpreter, using a series of stored directives, allows the loading of data from computational chemistry applications into a generic database. Extending the interpreter to support a new application involves supplying a list of directives for each piece of information to be loaded. This research confirms that …

Electrochemical Carbonylation Of Organoiron Methyl Complex: A Study Of Reaction Intermediates, C. Amatore, Mekki Bayachou, J. N. Verpeaux, L. Pospisil, J. Fiedler

Chemistry Faculty Publications

The one-electron reduction of CpFe(CO)2CH3 has been investigated by voltammetry and Fourier transform IR spectroelectrochemistry. The reduction initiates the insertion of CO ligand in the FeCH3 bond. The dissociation of a CO group proceeds in a parallel reaction. Reaction intermediates, the acyl derivative and released CO, form the radical anion of a complex CpFe(CO)2(COCH3) which is able to reduce the parent compound. The reversible redox potential − 1.8 V of CpFe(CO)2(COCH3) allows the regeneration of its radical anion which drives a catalytic cycle. The lifetime of intermediates is shortened by side reactions, one of which is the migration of the …

Studies Directed Toward Enantioselective Catalysis, Brian E. Jones

Open Access Master's Theses (through 2010)

Many organic molecules of modest size and complexity have chirality.That is, these molecules can exist in more than one stereoisomeric form.There is a strong desire to synthesize chiral compounds that exist in the form of a single stereoisomer.The method of synthesizing chiral compounds that was studied in our research employed a less than stoichiometric amount of chiral catalyst to both catalyze and control the stereochemical outcome of the reactions attempted.

A new chiral ligand was developed to be used as part of the chiral catalyst.This new ligand was used in the enantioselective Diels-Alder cycloaddition reaction and the enantioselective allylation reaction …

Riparian Habitats Of The Central Platte As A Corridor For Dispersal Of Small Mammals In Nebraska, Thomas D. Silvia

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Application And Evaluation Of A Biotic Index To Sand Hills And Streams Of Nebraska, Gregory T. Michl

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Synthesis Of Nitrosyl Metallpoprphyrins, Thomas M. Braxton Jr.

McCabe Thesis Collection

Nitric oxide, NO, is a molecule with great versatility and importance. Made up of only a single atom of nitrogen and a single atom of oxygen, nitric oxide is perhaps one of the smallest paramagnetic molecules found in nature. The functions of NO in the body are not all known, but this molecule definitely plays a variety of roles. It is involved in the regulation of blood pressure, and it sometimes acts as a messenger for cells as well as a killer of them. It also is important in the defense of the body against foreign invaders. The significance of …

Population Genetics: Estimation Of Distributions Through Systems Of Non-Linear Differential Equations, Nacer E. Abrouk, Robert J. Lopez

Mathematical Sciences Technical Reports (MSTR)

In stochastic population genetics, the fundamental quantity used for describing the genetic composition of a Mendelian population is the gene frequency. The process of change in the gene frequency is generally modeled as a stochastic process satisfying a stochastic differential equation. The drift and diffusion coefficients in this equation reflect such mechanisms as mutation, selection, and migration that affect the population. Except in very simple cases, it is difficult to determine the probability law of the stochastic process of change in gene frequency. We present a method for obtaining approximations of this process, enabling us to study models more realistic …

A Variable Time-Step Midpoint Scheme For Hamiltonian Systems, Yosi Shibberu

Mathematical Sciences Technical Reports (MSTR)

A smooth time-step selection formula for the midpoint method is derived which minimize deviations in the Hamiltonian function along piecewise-linear phase space trajectories of autonomous Hamiltonian systems. The time-step formula is implemented in a second order pre­dictor/corrector scheme and applied to Kepler's problem. The formula significantly improves energy conservation as well as the accuracy of the configuration space trajectory. Peak errors in position and momentum coordinates are not significantly reduced, but the time behavior of the errors is markedly more regular.

Disorder And Noncollinear Magnetism In Permanent-Magnet Materials With The Thmn12 Structure, R. Lorenz, J. Hafner, Sitaram Jaswal, David J. Sellmyer

David Sellmyer Publications

We report calculations of the noncollinear magnetic structures of YFe_12-xMo_x permanent-magnet materials, using a novel variant of a spin-polarized tight-binding–linear-muffin-tin-orbital technique allowing for local spin-quantization axes on each site and considering spin-orbit coupling. The ternary YFe_12-xMo_x compounds crystallize in the tetragonal ThMn₁₂ structure which can be stabilized only by the partial substitution of Fe by an early transition metal like Mo. We show that the substitutional disorder leads to canted spin structures at low Mo content ( x~1) and to spin-glass-like behavior at higher Mo content (x~3).

59. Otto Kratky, 1902-1995, Otto Vogl, Josef Schurz

Otto Vogl

No abstract provided.

Electron Scattering From 10b, A Cichocki, J Dubach, R S. Hicks, Gerald Alvin Peterson

Gerald Alvin Peterson

Electron scattering measurements have been made in order to determine the longitudinal and transverse form factors of low-lying level in 10B. With the exception of the broad 5.18 MeV level, results were obtained for all known levels up to 6.7 MeV. The measurements span the momentum transfer range q=0.48–2.58 fm-1. The primary objective of this work was to improve the data on the pure isovector M3 form factor of the 1.740 MeV excitation, the transform of which yields the 1p3/2 single-nucleon wave function. A Woods-Saxon potential was found to provide a much better representation of the data than the harmonic …