This work takes a closer look at ceria catalyst synthesis through micelle self-assembly. We compare surfactants, precursors, solvent systems, and doping. The surfactants are the building blocks upon which the ceria can crystallize. The samples are calcinated to test their thermal stability. Characterization is performed using pXRD as well as physisorption. The samples that exhibited a higher thermal stability were characterized to have a high surface area as well as low fluctuations in crystallite size, pore volume, and pore size. Ceria synthesized with cerium (III) nitrate hexahydrate and CTAB in a water:ethanol mixture using sodium hydroxide showed to be the most effective at providing a thermally stable product. Doping the catalyst with titanium increased the thermal stability significantly. Select samples were run in a variety of fuel to oxygen ratios to determine the best conditions in which we could perform partial methane oxidation to recuperate hydrogen gas. Most of the experiments show oxygen depletion with minor changes in other gas levels indicating that there is no oxidation occurring. Curiously the oxygen levels do decrease. There is a possibility that there is a reaction occurring initially at room temperature and being exacerbated with further temperature increase.

No description available.

Acidified dairy products are one of the oldest types of food products. Unfortunately all of them are low in dietary fibre. Thus, to improve health benefit of these products the idea of fortifying them with dietary fibre seems attractive. However dairy products enriched with Glucagel (a commercial product that is high in barley β-glucan) were found to suffer from textural defects. When the Glucagel concentration exceeded a certain value (5 g/L), dramatic phase separation was observed in set yogurt and yogurt drink with volume fraction of casein micelles greater then 0.108. To investigate interactions of β-glucan polymers and casein micelles in the milk prior to setting of yogurt, mixtures of yogurt milk and Glucagel were systematically studied. Depending on the volume fraction of casein micelles and the Glucagel concentration, a stable phase or a gel or a sedimented material could exist. The driving force for phase separation was depletion flocculation of casein micelles in the presence of β-glucan. The phase separation responsible for textural defects in yogurt systems supplemented with high amounts of Glucagel can be avoided by the reduction of β-glucan molecular weight, a process that limits the range of attraction between micelles. Incubation of Glucagel with lichenase for 90 min resulted in homogeneous (stable) yogurt systems with Glucagel concentrations as high as 10 g/L.

This work takes a closer look at ceria catalyst synthesis through micelle self-assembly. We compare surfactants, precursors, solvent systems, and doping. The surfactants are the building blocks upon which the ceria can crystallize. The samples are calcinated to test their thermal stability. Characterization is performed using pXRD as well as physisorption. The samples that exhibited a higher thermal stability were characterized to have a high surface area as well as low fluctuations in crystallite size, pore volume, and pore size. Ceria synthesized with cerium (III) nitrate hexahydrate and CTAB in a water:ethanol mixture using sodium hydroxide showed to be the most effective at providing a thermally stable product. Doping the catalyst with titanium increased the thermal stability significantly. Select samples were run in a variety of fuel to oxygen ratios to determine the best conditions in which we could perform partial methane oxidation to recuperate hydrogen gas. Most of the experiments show oxygen depletion with minor changes in other gas levels indicating that there is no oxidation occurring. Curiously the oxygen levels do decrease. There is a possibility that there is a reaction occurring initially at room temperature and being exacerbated with further temperature increase.

Acidified dairy products are one of the oldest types of food products. Unfortunately all of them are low in dietary fibre. Thus, to improve health benefit of these products the idea of fortifying them with dietary fibre seems attractive. However dairy products enriched with Glucagel (a commercial product that is high in barley β-glucan) were found to suffer from textural defects. When the Glucagel concentration exceeded a certain value (5 g/L), dramatic phase separation was observed in set yogurt and yogurt drink with volume fraction of casein micelles greater then 0.108. To investigate interactions of β-glucan polymers and casein micelles in the milk prior to setting of yogurt, mixtures of yogurt milk and Glucagel were systematically studied. Depending on the volume fraction of casein micelles and the Glucagel concentration, a stable phase or a gel or a sedimented material could exist. The driving force for phase separation was depletion flocculation of casein micelles in the presence of β-glucan. The phase separation responsible for textural defects in yogurt systems supplemented with high amounts of Glucagel can be avoided by the reduction of β-glucan molecular weight, a process that limits the range of attraction between micelles. Incubation of Glucagel with lichenase for 90 min resulted in homogeneous (stable) yogurt systems with Glucagel concentrations as high as 10 g/L.

This thesis describes a series of studies to investigate the predator-prey relationships between the Goosander Mergus merganser, a fish-eating duck, and populations of game fish in northern Britain. The distribution and numbers of birds during the breeding season, in northern England and Scotland, were investigated and variations in density, between and within rivers, studied. Relationships between densities in spring and summer survey periods were also investigated. Possible biases in survey data are discussed. Studies of the growth of ducklings reared in captivity allowed estimates to be made of food and energy requirements from hatching up to approximately the time of fledging, at c70 days. Seasonal changes in the body mass and body condition of adult and immature Goosanders were investigated and daily and seasonal food and energy requirements estimated. Time-budget data were collected to investigate how birds partitioned their time between various behaviours. Of particular concern was the temporal and spatial distribution of foraging activities between and within broad habitat types, viz. rivers, standing waters known to be roost sites, and non-roost standing waters. Feeding behaviour was also recorded. The species composition of the diet and the numbers of individual fish represented, were determined by the gut analysis of 54 birds received from various sources. Possible biases in this method are discussed. For salmonids, the size of individual prey items was investigated from regression equations of fork length on vertebrae length, based on a reference collection. Conflicting evidence of damage to fisheries from other studies chiefly in North America, is re-assessed in the light of current knowledge of the population dynamics of salmonids and of results presented here. The potential contribution of depredations by Goosanders to mortality at successive life stages of fish is considered.

Studies were undertaken to investigate the suitability of several molecular and physiological responses as biomarkers of UV-B exposure in several marine macroalgal species. Investigations into the sensitivity of mature plants and the reproductive unicells were also carried out. Furthermore, experiments were conducted to determine the interaction between UV-B radiation and the antifouling compound Irgarol 1051 in both a fouling alga and two non-target algal species. Chlorophyll fluorescence, in vivo thallus absorptance and ion leakage were investigated for their suitability as physiological biomarkers of UV -B exposure in the intertidal alga Enteromorpha intestinalis and the subtidal alga Palmaria palmata. DNA damage (measured by Random Amplification Polymorphic DNA fingerprinting, RAPD) and the cellular stress response (measured by induction of the heat shock 70 protein, HSP 70) were evaluated as molecular biomarkers of UV-B exposure. Measurements of thallus growth were used as a measure of adverse biological effects. Fv/Fm ratio showed potential as a sensitive, nonspecific general biomarker of UV-B exposure in both E. intestinalis and P. palmata. In vivo absorptance at wavelengths corresponding to chlorophyll a, phycoerythrin and/or carotenoids, as well as phycoerythrobilin and phycocyanin decreased in a dose-response dependent manner with UV-B exposure. These changes were associated with decreases in growth rate in P. palmata. The RAPD technique used for measuring DNA damage, showed potential as a tool for assessing UV -induced toxicity. These results illustrated that utilising several responses from different levels of biological organisation offer greater possibilities for detecting UV-B induced effects than do single responses. Experiments with 12 h old reproductive unicells of E. intestinalis demonstrated that asexual zoospores were up to 6 times more sensitive to UV-B exposure than mature thalli (measured as variable fluorescence). After 1 hour exposure to elevated UV-B (equivalent to 27% ozone depletion) reproductive unicells experienced decreases in variable fluorescence, accompanied by a 50 % inhibition of germination success and 16.4 % reduction in growth rates. Moreover, consistent patterns of greater sensitivity in the sexual reproductive part of the life cycle compared to the asexual part of the life cycle emerged throughout the experiments. The interactive relationship between UV-B radiation and the s-triazine Irgarol 1051 was investigated in multi-factorial experiments. Inhibitions in optimal quantum yield of approximately 20% were found after exposure to UV-B or Irgarol 1051 (applied singly). When these two stressors were applied simultaneously, however, an additive effect resulting in further reductions of up to 19.6 % compared to a single treatment occurred. These decreases in Fv/Fm were accompanied by up to a 38.5 % reduction in growth rates. Simultaneous exposure of the same stressors to two non-target macroalgae, P. palmata and P. umbilicalis, revealed that these algae were less sensitive to Irgarol 1051 compared to E. intestinalis. However, similar additive effects measured as reductions in both Fv/Fm ratio and growth rates occurred after simultaneous exposure. These results underline the importance of investigating combination effects between UV-B radiation and xenobiotic compounds, if an under-estimation of the ecological implications of elevated UV-B exposure in the marine environment is to be avoided.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 121-134). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19809

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.Sc. Physics)--University of Waikato, 2006. / Includes bibliographical references (p. 97-102)