Physical Sciences and Mathematics Commons^™

Characteristics And Stability Of Oxide Films On Plutonium Surfaces, Harry Guillermo García Flores

Department of Chemistry: Dissertations, Theses, and Student Research

The oxidation of plutonium (Pu) metal continues to be an area of considerable activity. The reaction characteristics have significant implications for production use, storage, and disposition of this radiological material. Developing an accurate physical model of the structures, oxidation states, and oxygen concentration gradients present during oxidation are essential to understanding this process. Traditionally, the stable oxides of Pu have been thought to be plutonium sesquioxide (Pu₂O₃, O/Pu = 1.5, Pu³⁺) and plutonium dioxide (PuO₂, O/Pu = 2.0, Pu⁴⁺), existing in a layered structure on Pu metal. Many of the …

Low Temperature Photo-Oxidation Of Chloroperoxidase Compound Ii, Xinting Yuan, Xin Sheng, John A. Horner, Brian Bennett, Leslie W. -M. Fung, Martin Newcomb

Physics Faculty Research and Publications

Oxidation of the heme-thiolate enzyme chloroperoxidase (CPO) from Caldariomyces fumago with peroxynitrite (PN) gave the Compound II intermediate, which was photo-oxidized with 365 nm light to give a reactive oxidizing species. Cryo-solvents at pH ≈ 6 were employed, and reactions were conducted at temperatures as low as − 50 °C. The activity of CPO as evaluated by the chlorodimedone assay was unaltered by treatment with PN or by production of the oxidizing transient and subsequent reaction with styrene. EPR spectra at 77 K gave the amount of ferric protein at each stage in the reaction sequence. The PN oxidation step …

Effects Of Open And Closed System Oxidation On Texture And Magnetic Response Of Remelted Basaltic Glass, Katherine Burgess, Reid F. Cooper, Julie A. Bowles, Jeffrey S. Gee, Daniele J. Cherniak

Geosciences Faculty Articles

As part of an experimental and observational study of the magnetic response of submarine basaltic glass (SBG), we have examined, using ion backscattering spectrometry (RBS), transmission and scanning electron microscopy, energy dispersive X-ray spectrometry, and surface X-ray diffraction, the textures wrought by the controlled, open and closed system oxidation of glasses prepared by the controlled environment remelting and quenching of natural SBG. Initial compositions with ~9 wt % FeO* were melted at 1430°C with the oxygen fugacity buffered at fayalite-magnetite-quartz; melts were cooled at a rate of 200°C min⁻¹ near the glass transition (T_g = 680°C). In open …

Ion-Molecule Reactions Of O,S-Dimethyl Methylphosphonothioate: Evidence For Intramolecular Sulfur Oxidation During Vx Perhydrolysis, Jilliarne Williams, Martin Paine, Stephen J. Blanksby, Michael L. Rogers, Andrew M. Mcanoy

Stephen Blanksby

The alkaline perhydrolysis of the nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) was investigated by studying the ion-molecule reactions of HOO- with O,S-dimethyl methylphosphonothioate in a modified linear ion-trap mass spectrometer. In addition to simple proton transfer, two other abundant product ions are observed at m/z 125 and 109 corresponding to the S-methyl methylphosphonothioate and methyl methylphosphonate anions, respectively. The structure of these product ions is demonstrated by a combination of collision-induced dissociation and isotope-labeling experiments that also provide evidence for their formation by nucleophilic reaction pathways, namely, (i) S(N)2 at carbon to yield the S-methyl methylphosphonothioate anion and (ii) nucleophilic …

Synthesis, Kinetic And Photocatalytic Studies Of Porphyrin-Ruthenium-Oxo Complexes, Yan Huang

Masters Theses & Specialist Projects

Macrocyclic ligand-complexed transition metal-oxo intermediates are the active oxidizing species in a variety of important biological and catalytic oxidation reactions. Many transition metal catalysts have been designed to mimic the predominant oxidation catalysts in Nature, namely the cytochrome P450 enzymes. Ruthenium porphyrin complexes have been the center of the research and have successfully been utilized, as catalysts, in major oxidation reactions such as the hydroxylation of alkanes. This study focuses on kinetic and photocatalytic studies of oxidation reactions with wellcharacterized high-valent ruthenium-oxo porphyrin complexes.
The trans-dioxoruthenium(VI) porphyrins have been among the best characterized metal-oxo intermediates and their involvement as …

Molecular Characterization Of The Soluble Fraction Of Atmospheric Particulate Matter Obtained By Chemical Oxidation With Nitric Acid, Amanda Susan Priest

Chemistry & Biochemistry Theses & Dissertations

The availability of information regarding the composition of ambient atmospheric particulate matter and the transformations that these compounds may undergo upon atmospheric transit is surprisingly absent. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry is used in this study to rapidly evaluate the composition of the water-soluble organic fraction of standard and collected atmospheric particulate matter samples, and the changes that these mixtures undergo upon oxidation with nitric acid. The standard samples include representative particulate matter collected over the course of a year in Washington, D.C. and particulate matter from the exhaust of a diesel-powered engine. The collected sample …

Oxidation Of Dibenzothiophene To Dibenzothiophene Using Metal Nanoparticles Supported On Silica, Karina Castillo

Open Access Theses & Dissertations

Silica and nanoparticles of Pt, Au, and Ag supported on silica were tested for the ability to oxidize dibenzothiophene (DBT) to sulfone. High performance liquid chromatography was used to study the removal of DBT from solution. In addition, X- ray diffraction, infrared spectroscopy and Raman Spectroscopy were used to characterize the product of the oxidation reaction. Further studies involved the use X-ray absorption spectroscopy to characterize the nanoparticle catalysts before and after the oxidation reaction.

To better understand the reaction, silica was synthesized at different pHs using three different acids. The acids used to synthesize the silica were HCl, HNO3, …

Oxidation Of Reduced Sulfur Compounds: A Triple-Oxygen-Isotope Perspective, Issaku E. Kohl

LSU Doctoral Dissertations

The Earth’s geochemical evolution is recorded in the rocks that compose its lithosphere. Specifically, sulfate minerals have been identified as being repositories of information concerning the past hydrosphere, atmosphere and biosphere. This is due to the non-labile nature of SO42- and its ability to store a record of the oxidative reactions and oxygen sources involved in its formation. Microbial dissimilatory sulfate reduction (MDSR) and sulfide oxidation cause oxygen from H2O and O2 to be trapped to varying degrees in ambient, dissolved SO42-. In order to better interpret the H2O and O2 signals in SO42-, we must deepen our understanding of …