M.Sc.(Chemistry) / Fourier transform infrared and ultraviolet-visible spectroscopy were used in this study. The relative merits of dispersive and interferometric instrumentation were investigated and the latter revealed a dramatic improvement in accuracy. In the infrared study transmission and diffuse reflectance techniques were used and compared. The diffuse reflectance technique provides more information regarding surface species, like OH-groups and interactions between adsorbent and adsorbate, than the transmission technique ...

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Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Engineering and the Built Environment, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, 2017 / Three medium rank C coals and a discard coal from different coalfields within the Karoo Basin were investigated. In this study, physico-chemical properties, ash fusion tests, quantitative single particle -electron probe X-ray microanalysis (SPAEPXMA), petrography, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), and micro-Raman spectroscopy (mRs) were used as analytical techniques of choice to investigate the heterogeneous nature of coals, including mineralogical structure, mode of occurrence, and association of mineral matter in coals. The aim of the work was to highlight the significance of understanding the heterogeneous nature of coals, and to develop comprehensive and reliable approaches of characterising coals, coal ashes, and predict the behaviour of coals in coal conversion processes. The FTIR technique identified a well ordered kaolinite of authigenetic origin, characterised by inner hydroxyl group with H2O vibration at 3618 cm-1 absorption bands as the major mineral. Smectite and muscovite were identified at peaks 797 cm-1 and 799 cm-1 respectively, with quartz confirmed by the υ (Si-O-Si) and δ (Si-O) bands. The SPA-EPXMA data, modelled using principal component analysis (PCA) and chemical boundary classification (CBC), identified a diverse range of minerals such as alunite, chlorite, fayalite, almandine, anatase, ilmenite, brushite, goyazite, gypsum, dolomite, calcite, sodalite, rhodochrocite, and halite in raw coal samples. The mRs technique showed that in addition to bassinite, other oxidation products that formed at low temperature included lepidocrite and coquimbite. The technique proved to be ideal for the characterisation of high temperature ashes. High spatial resolution of mRs confirmed the presence of mixtures of anatase, brookite, and rutile, hematite, nephaline, apatite, crednerite and apatite in high temperature ashes. The SPA-EPMXA and mRs technique probed minerals on a micro-scale and their application could be extended to prediction of slagging and fouling behaviour in coals. The multiple technique approach revealed the importance of using a combination of techniques to characterise coals, and provided useful information that can help understand and relate the mineralogical and elemental composition of coals. This knowledge could be useful in designing conversion processes, and necessary downstream manipulations. / XL2018

Tsui Shu Ki. / Bibliography: leaves 110-112 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaf 61.

David Lai. / Thesis -- Chinese University of Hong Kong. / Bibliography: l. 103-104. / Acknowledgement --- p.v / Abstract --- p.vi / Format of the Thesis --- p.viii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Experimental Techniques / Chapter 2.1 --- Introduction --- p.10 / Chapter 2.2 --- Arrangement for Fluorescence Spectrum Measurements --- p.10 / Chapter 2.3 --- Fluorescence Spectrum Measurements by Photographic Method --- p.11 / Chapter 2.4 --- Arrangement for Fluorescence Decay Rate Measurements --- p.11 / Chapter Chapter 3 --- Soda-lime Glass Matrix / Chapter 3.1 --- Introduction --- p.17 / Chapter 3.2 --- Theory --- p.19 / Chapter 3.3 --- Samples --- p.23 / Chapter 3.4 --- Experiments and Results --- p.26 / Chapter 3.5 --- Discussion / Chapter 3.5.1 --- Fluorescence Spectra --- p.35 / Chapter 3.5.2 --- Decay Rate Measurements --- p.39 / Table (3-1) --- p.43 / Table (3-3) --- p.43 / Table (3-2) --- p.44 / Chapter Chapter 4 --- Lithium Phosphate Glass / Chapter 4.1 --- Introduction --- p.45 / Chapter 4.2 --- Samples --- p.46 / Chapter 4.3 --- Experiments and Results --- p.47 / Chapter 4.4 --- Discussion --- p.54 / Table (4-1) --- p.64 / Table (4-2) --- p.65 / Table (4-3) --- p.66 / Table (4-4) --- p.66 / Chapter Chapter 5 --- Hydrogen Oxide (H20) and Deuterium Oxide (D20) / Chapter 5.1 --- Introduction --- p.67 / Chapter 5.2 --- Theory --- p.69 / Chapter 5.3 --- Experiments and Results --- p.71 / Chapter 5.4 --- Discussion --- p.71 / Table (5-1) --- p.78 / Table (5-2) --- p.79 / Chapter Chapter 6 --- Conclusion --- p.80 / Appendix I --- p.82 / Appendix II --- p.83 / Appendix III --- p.84 / Appendix IV --- p.85 / Appendix V --- p.86 / Appendix VI --- p.90 / Appendix VII --- p.91 / Appendix VIII --- p.95 / Appendix IX --- p.96 / Appendix X --- p.102 / References --- p.103

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While alcohols have successfully undergone kinetic resolutions, amines pose a challenge due to their nucleophilic nature. Aziridines were identified as potential substrates as a result of their synthetic utility and reduced nucleophilicity. Using a helical aminopyridine catalyst, the kinetic resolutions of ketoaziridines were explored. Initial attempts revealed anomalous kinetic behaviour [slow conversion and non-first order]. Non-buffered noncatalytic control reactions demonstrated unexpected reaction dynamics, as gauged by HPLC and 1H NMR. Stopped-flow spectroscopy revealed photochemical sensitivity of the aziridine. As a result of this new information, the project evolved into a study of the photochemical behaviour of ketoaziridines and their spectroscopic properties. UV-vis absorbance and fluorescence spectroscopy were used to probe the photochemical reactivity of ketoaziridines. These studies suggested a two-step mechanism where an azomethine ylide formed a reactive intermediate, ultimately to form 2,5-diphenyloxazole. Kinetic analysis revealed the mechanism was autocatalytic with respect to oxazole formation. TD-DFT calculations suggested the mechanism proceeded via a diradical species upon irradiation. This mechanistic route was studied by investigating the presence of a magnetic field effect on the kinetics of absorption and emission changes, in collaboration with the Manchester Institute of Biotechnology. Further studies demonstrated a radical species, derived from the irradiation of aziridine, may be used as a photoinitiator in the polymerization of methyl methacrylate. This work also involved development of a synthetic platform to diphenyloxazoles, where functionality may be installed in the initial steps. Use of this strategy allowed for the synthesis of a natural product, texaline.

Diseases associated with amyloid aggregation have been a growing focus of medical research in recent years. Altered conformations of amyloidogenic peptides assemble to form soluble aggregates that deposit into the brain and spleen causing disorders such as Alzheimer's disease and Type II diabetes. Emergent theories predict that fibrils may not be the toxic form of amyloidogenic structures and that smaller oligomer and protofibril aggregates may be the primary source of cellular function damage. Studies show that these amyloidogenic aggregates are characterized by an increased number of poorly dehydrated hydrogen backbones and large surface densities of patches of bulk like water which favor protein association. When proteins aggregate to form larger structures, there is a redistribution of water surrounding these proteins. The water dynamics of amyloidogenic aggregation is different than the monomeric form and has a decrease in the number of patches occupied by molecules with bulk-like water behavior. We demonstrate that the redistribution of water during amyloid aggregation is reflected in a change in the dielectric relaxation signal of protein-solvent mixtures. We use dielectric relaxation spectroscopy (DRS) as a tool for studying the dynamics of amyloidogenic peptides--amyloid beta (Ab 1-42) and human islet amyloid polypeptide (hIAPP)--during self-assembly and aggregation. Non-amyloidogenic analogs-- scrambled (Ab 42-1) and rat islet amyloid polypeptide (rIAPP)--were used as controls. We first present studies of amyloidogenic peptides in a deionized water buffer at room temperature as a function of concentration and incubation time. From this we were able to determine differences in amyloidogenic and non-amyloidogenic peptides through the dielectric modulus. We next present the same analytes in a deionized water-glycerol buffer to facilitate the study of the dielectric permittivity at sub-freezing temperatures and model the kinetics of the alpha- and beta- relaxation processes. We conclude our work by studying the peptides in a bovine serum albumin (BSA) and glycerol buffer to demonstrate dielectric spectroscopy as a sensitive tool for measuring amyloidogenic peptides in an in vivo- like condition.