LD2668 .T4 1947 P38 / Master of Science

Call number: LD2668 .T4 1961 B89

Four different trivalent and tetravalent metal phthalocyanine systems (chlorogallium, chloroindium, vanadyl, and titanyl phthalocyanines) were used singly to prepare thin films (0.05-2.0 micron thickness) on gold, optically transparent substrates. The photoelectronic properties of these electrodes could be modified either by altering the growth conditions (i.e. rate of sublimation, cleanliness of substrate) or by dosing the thin films with either hydrogen or oxygen at elevated temperatures (150°C). The properties of these thin films were monitored by electron microscopy, UV-visible spectrophotometry, X-ray and Ultra-violet surface spectroscopies, and a variety of electrochemical and photoelectrochemical techniques. All four systems behaved in a manner similar to a p-type semiconductor when prepared at rapid rates (10-20 A/min) on gold substrates. In the dark, for contacting redox couples with Eᵒ’ values negative of +0.6V, the phthalocyanine electrodes showed negligible dark currents. Upon illumination, the photoelectrodes only produced positive photopotentials. Chlorogallium phthalocyanine thin films could be made to produce both positive and negative photopotentials when grown at slow rates (1-5 A/min) on clean, gold substrates. These chlorogallium phthalocyanine electrodes regained the properties of a p-type semiconductor after being dosed with oxygen for 48 hours at 150°C. X-ray Photoelectron Spectroscopy confirmed the presence of a high concentration of oxygen at the surface of all of the p-type phthalocyanine electrodes. The oxygen may accept electron density from the phthalocyanine macrocycle to cause the Fermi level to move down in energy toward its valence band edge. Dosing the film with hydrogen caused the electrode to exhibit its original intrinsic characteristics. This variability in electrical properties as a function of gas dopant may lead to the development of a sensitive gas sensing device. Ultra-violet Photoelectron Spectroscopy, as well as molecular orbital calculations, were applied to the chlorogallium phthalocyanine system to determine the molecular orbital contributions to its valence and conduction bands. Photoelectrochemical cells made from electrodes of chlorogallium and vanadyl phthalocyanines exhibited power conversion efficiencies in excess of 0.1%. The vanadyl and titanyl phthalocyanine electrodes were also effective catalysts for the photoreduction of H⁺ to H₂.

Variation in pigmentation of hair and skin is one of the most striking forms of human diversity. Human pigmentation and sun sensitivity is a complex trait. The melanocortin 1 receptor gene (MC1R) (OMIM 15555) has been shown to be a key determinant of hair and skin colour. Recently a number of other genes have been implicated in human pigmentation. This thesis presents the relationship between human pigmentary phenotypes and genetic variation at MC1R and 34 other candidate loci from 159 individuals. The relationship between experimentally induced cutaneous erythemal and facultative pigmentary response to UVB radiation and MC1R and other pigmentation genotypes was investigated in a subset of 98 individuals. Some of this work involved the development of novel methods of assaying phenotype. I present a detailed description of human pigmentation and facultative pigmentation with respect to a number of key variables (e.g. sex, site, freckling, skin type) and seek to explain the variation in pigmentation in relation to these factors. The effect of MC1R on hair colour is large, but MC1R explains a smaller amount of the variation for skin colour. I found that a number of loci including MC1R, oculocutaneous albinism type 2 OCA2 (OMIM 611409), KIT oncogene ligand KITLG (OMIM 184745) and the Hermansky-Pudlak syndrome 3 HPS3 (OMIM 606118) are determinants of pigmentary phenotype. Some of these findings are in keeping with previous work and some are novel. I present data showing novel SNPs in genes Hermansky-Pudlak syndrome 3 (HPS3) and KIT ligand (KITLG) to be associated with human skin and hair colour variation. Association of HPS3 to eye colour was also found and has to be confirmed in another population. The possible putative mechanisms for the novel association finding in HPS3 are discussed. I am in the process of confirming these positive significant findings in collaboration with another laboratory in Denmark. Further experiments are proposed to confirm other associations and phenotypes.

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As aquaculture has become a significant provider of the human diet, the interest to have better quality of sea and fresh products has been increasing. However the potential hazards associated with pathogenic agents resulting in losses to the industry are major concerns that provided the motivation for this study.The use of ultraviolet irradiation is an alternative to disinfect water in inlet and outlet water sources. However the ultraviolet disinfection method has some drawbacks including no disinfectant residuals and high cost of lamp fouling and replacement. The ultraviolet system needs to be calibrated according with the life time of the ultraviolet lamps.The MS-2 coliphage in this study is an approach to determine a good indicator for determining if an ultraviolet system can be effective in an aquaculture recirculation system. The susceptibility of this system can provide an indication if WSSV can be inactivated and possible other pathogenic agents.The WSSV experiment was successful in reducing mortality. Further studies have to be completed and analyzed before recommending for control of other pathogens.

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