Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 182-187). Also available via the Internet.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3843. Adviser: Kenneth S. Suslick. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

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Reversible cis-trans isomerisation of a series of commercially interesting yellow azo dyes has been studied using the technique of Nuclear Magnetic Resonance (NMR) spectroscopy with in situ laser irradiation. Photostationary state (PSS) spectra of the azo dyes, provided by coupling laser irradiation into the sample within the probe of the NMR spectrometer, have allowed observation of azo cis isomer species that would otherwise elude detection and characterisation by NMR due to their rapid thermal decay times. The NMR results have been combined with geometry optimised structures obtained through ab initio (DFT) calculations in order to allow visualisation of the trans and cis isomer species, and explain NMR spectral features. In the majority of cases, these in vacuo calculated structures show a great deal of correlation with NMR observations of asymmetric, cis-trans isomerisation-induced chemical shift changes for protons adjacent to the azo bond. The cis isomer spectral pattern for substituted naphthyl group protons can hence be used as a diagnostic tool in determining the correct cis isomer conformation in molecules where more than one conformation may exist. In addition to the aforementioned characterisation studies, in situ irradiation has provided the opportunity to undertake a thorough investigation of the kinetics of photoand thermal isomerisation for the same yellow dye series. The results of these studies have been combined with previous work on similar systems to provide an extensive data set, and conduct analysis in a systematic fashion. Adding fibre-reactive groups, varying phenyl and chlorotriazine ring substituents, and altering naphthyl group sulfonation patterns have a profound effect on both the photochemical and thermal rates of isomerisation in these systems. In certain cases, the same structural calculations noted earlier have proved useful in rationalising the identified kinetic differences. The presence of phenyl substituents ortho to the azo bond has been shown to increase the rate of thermal cis isomer decay. Additionally, substituents bonded to a fibrereactive group distant from the azo bond have an appreciable effect on the barrier to thermal cis-trans isomerisation, but little effect on the photochemical characteristics of each isomer. Several sulfonated naphthyl group patterns have been studied, leading to an observation that sulfonate groups positioned ortho to the azo bond assist in retarding thermal isomerisation, with sulfonate groups in other positions having a much smaller effect. One particular molecule, a component of a currently available commercial dye, was studied for its interesting and previously unexplained behaviour, both photochemical and chemical. The dye demonstrated photoisomerisation at low concentrations only, with aggregation preventing formation of the cis isomer at higher concentrations. The trans isomer was found to undergo degradation to a product which did not photoisomerise. This product was identified as a benzotriazinium compound by multinuclear 2D correlation NMR spectroscopy, formed by a reversible cyclisation reaction involving the azo bond.

Thesis (Ph. D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Vita. Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references and index.

Master of Science / Department of Chemical Engineering / Larry E. Erickson / The reaction chemistry of uranium metal has been well documented for use in the development of nuclear fuels. The oxidation of uranium from the thermal stress of nearby combustion is different than that of a reactor environment due to the selectivity of the various competing reactions. This work extracts available information in literature and various experiments over the last 60 years to provide a critical look at the response of uranium metal to thermal stress. The oxide fume formed and the equilibrium phase shifts during the dispersal of the airborne particulate are of principal interest when determining potential consequences to the health and safety of the workers, members of the public, and the environment. The transport phenomena and reaction kinetics of the oxide fume are also discussed at various distances from the source material. Uranium is a versatile element that can form numerous compounds, of which the oxides are the forms that are most readily generated under thermal stress and also pose the largest health risk to human beings, primarily through inhalation. A general summary of uranium and the dry compounds (oxides and carbides) is provided discussing the different structures of each state. The reaction kinetics and selectivity as the oxidation progresses is discussed for typical uranium metal forms at temperatures above and below the ignition point. Characteristics of potential fires are qualified for determining thermal stress. The creation of the oxide fume is outlined followed by dispersal characteristics of the aerosol. These molecular processes are related to the release fractions of uranium under fire scenarios which are compared with available experimental data from the regulatory handbooks. A critical look at the conclusions of the handbook with recommendations for revising the existing guidelines and additional testing are made in the interest of ensuring that derived controls are appropriate to reduce the risk of accidents involving the oxidation of uranium metal.

Thesis (Ph. D.)--University of California, Riverside, 2008. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 10, 2010). Includes bibliographical references. Also issued in print.