Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: Michael J. McGlinchey. Includes bibliographical references (leaves 172-192). Also available via World Wide Web.

“Nanomaterials” is a generic term used to describe nano-sized crystals and bulk homogenous materials with a structural disorder at the nanoscale. Ancient (and modern) ceramics and glasses derive some of their properties (eg. pliability and low sintering temperature) from the fact that their raw material namely natural clay is nanosized. Furthermore the pigments used to colour ceramics and glasses need to have particle sizes <500 nm for the object to appear homogenously coloured to the human eye. Raman spectroscopy intrinsically probes chemical bonds and is therefore one of the few techniques that has been proven useful to provide information at the nanoscale. It is an excellent tool to study ceramics and glasses as a Raman spectrum can be used to identify phases, analyse amorphous domains in the silicate network and identify pigments on a nano-scale. The characteristics of a glass, ceramic or ceramic glaze derived through its Raman spectrum can then be linked to the technology used to produce an artefact and in this way provide information about its relative age and provenance. Likewise, the identification of pigments and binders in San rock art might provide information about production techniques and assist in the developement of conservation procedures. In this thesis micro-Raman spectroscopy (with X-ray fluorescence, X-ray powder diffraction, electronmicroscopy and photoluminescence as supportive techniques) was utilised to study archaeological artefacts from the Mapungubwe Collection and San rock art. It was possible to re-date celadon shards excavated on Mapungubwe hill in 1934 to the Yuan or even later Ming dynasty in stead of its original classification as Song. A profile of the glass technology used to produce the Mapungubwe oblates, small trade beads from the “royal burials” on Mapungubwe hill was determined and quite a few unique characteristics of the beads may eventually help to establish their provenance. The possible influence of the presence of rock hyraces at rock art sites on the deterioration of rock art were investigated and during the study very rare polymorphs of CaCO3 (vaterite and monohydrocalcite) were discovered in rock hyrax urine. This study was extended to analyse a San rock art fragment and another first was the identification of animal fat on the fragment, but the exact origin of the fat has to be verified by similar experiments. / Thesis (PhD)--University of Pretoria, 2009. / Physics / unrestricted

Molecular orbital calculations have been successively applied to mineralogical studies of equilibrium molecular geometry, electronic charge distributions, electronic spectra and bulk modulus calculations. To date, these studies have modelled bonding at atmospheric pressure. With the ever increasing interest in high pressure phases and mantle mineralogy, bonding studies of molecular groups at simulated high pressure can be an invaluable aid to understanding high pressure crystal chemistry, bond energetics and electronic spectra. This investigation tests the feasibility of various models to simulate pressure in ab initio SCF MO calculations on common metal-oxygen polyhedra. Pressure is simulated in the cluster, H₆Si₂O₇, by systematically stepping helium atoms directed^ along the Si-O bridging vectors toward the bridging oxygen. Changes in the Si-0 bond lengths, SiOSi angles and Si-0 force constants are monitored with increasing pressure. For an increase of 60 kbar pressure, the Si-0 bond length and SiOSi angle decrease 0.30% and 4.5%, respectively, which compares well with the 0.30% and 6.6% decrease observed in c-quartz for a similar increment of pressure. The linear correlation of Si-0 bond length and -sec(SiOSi), known to occur at one bar, holds at elevated pressure. In addition, the Si-0 stretching and SiOSi bending force constants show a percentage increase in the ratio 1:6 up to an estimated pressure of 140 kbar. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Given the prevalence of primary amines in biologically active molecules, an important area of research is devoted to creating methods to site-selectively functionalize their C(sp³)-H bonds. For simple aliphatic primary amines, many of these C-H bonds are chemically indistinguishable due to their similar electronics and sometimes, steric environments. Through strategic choice of activating group, site-selective functionalization at both α- and ẟ- positions is achieved. Exploiting inductive effect allows for a photoredox-catalyzed α-C(sp³)-H alkylation of trifluoromethanesulfonamides. In the case of trifluoroacetamides, functionalization is directed to a distal C(sp³)-H site via [1,5]-hydrogen atom transfer which results in a formal delta-aminomethylation and delta-cyanation. Lastly, by subjecting primary amines to an electron-rich benzaldehyde activating group, we leverage C-N bonds as a functional handle for deaminative radical cross-couplings.

No description available.

The following investigation was undertaken to find a method for the oxidative cleavage of the double bond, using oleic acid. The primary purpose of this investigation was to find a cheap method of splitting the double bond in oleic acid and obtaining the saturated fatty acids formed therefrom. The procedure used in the attempt to accomplish these results was the auto-oxidation of the oleic acid. This was carried out with and without a catalyst, and also, in the presence of a chemical oxidizing agent. The results from the runs, with and without a catalyst, were poor in that no split of the double bond took place, but in most cases more favorable results were obtained in the presence of catalysts. The results were positive in the one case in which the chemical oxidizing agent was used with the catalyst. This run gave a split of the double bond and warrants further investigation. 1. No split of the double linkage in oleic acid was obtained from its autoxidation over a period of four hundred twenty-five hours, with or without a catalyst. 2. The ozonide of oleic acid was not formed, although the presence of peroxide oxygen was detected. 3. Iron oxide (Fe₃O₄) was a positive autoxidation catalyst, whereas, vanadium pentoxide was a negative catalyst. 4. Cleavage of the double linkage was obtained when concentrated nitric acid was used as the oxidizing agent in presence of vanadium pentoxide as the catalyst. The split was very slight, as only 0.4 gram of suberic acid was isolated from 89.5 grams of oleic acid. / M.S.

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

Several phenyl alkyl bonded phases for liquid chromatography were synthesized and characterized by liquid chromatography, gas chromatography and ¹³C nuclear magnetic resonance (NMR) spectroscopy. The chromatographic physical parameters investigated include a quantitative determination of the mobile phase volume and the stationary phase volume. The stationary phase volume was determined to be a function of the bonded moiety chain length and the chromatographic solvent system employed. The interpretation of the stationary phase volume is discussed in terms of the porous nature of the silica gel support. The chemical parameters determined include a quantitative determination of the mobile phase and stationary phase composition (which were different from each other). The selectivity of the chromatographic separations was dependent on the chemical composition and the volume of both the stationary and mobile phases. Carbon 13 NMR spectroscopy provided information about the environment of the bonded moiety in the stationary phase. The liquid-like nature of the bonded moiety was influenced by the chain length of the attached species, the choice of organic modifier, and the chemical composition of the solvents. Temperature did not appear to play a role in the line widths under the experimental conditions examined. The separation of several peptide diastereoisomers on different commercially available hydrocarbon bonded adsorbents is also reported. Select diastereoisomers of arginine vasopressin and oxytocin are extremely sensitive to differences in the composition of the stationary phase. The selectivity and elution order were dependent upon the choice of adsorbent and solvent system employed. The addition of a second organic modifier provided a method for the dynamic modification of the stationary phase. The ability to dynamically modify the stationary phase can enhance the selectivity for the separation of selected peptide diastereoisomers.