No description available.

The effects of pollutant burdens on natural cyclic patterns in aquatic ecosystems have been studied, to test the hypothesis that a parameter or parameters describing the <I>pattern of variation </I>in a single determinant, such as DO or pH, may be used to describe the status of a body of water more meaningfully than results from single spot measurements. In this study the background water quality in a Scottish and a Ghanaian lake was assessed, then <I>rafts </I>were built on the lakes (Myrtle Dam and Weija Lake respectively) creating three small lakes to test the effects of pollutant loads (<I>e.g. </I>organics and nutrients) on them. Laboratory investigations to study the behaviour of the pollutants on DO or pH cycles were carried out, and then a dynamic DO model was developed to describe the cyclic behaviour of DO. Finally, the model was used to investigate the effects of added pollutant burdens on the DO cycles. Water quality assessment of Myrtle Dam and Weija Lake by using the <I>Weighted Water Quality Index </I>proved that Weija Lake has doubtful quality with WQI 51, which needs improvement. Myrtle Dam WQI of 73 shows that the lake waters are unpolluted (or recovered from pollution). It is also well oxygenated at the surface and receives no toxic discharge. The <I>raft</I> experiments for Myrtle Dam and the Weija Lake have been used to demonstrate that, in the raft tubes, organic loadings do have effects on the oxygen cycles, and showed that there are two effects. One is that, with a small organic loading, the mean DO value dropped, then increased as the organic loading was consumed. The second is that the amplitude of the DO cycle increased as the organic loading increased from 2.5 to 5.0 mg L^-1 TOC for Myrtle Dam, and decreased for Weija Lake as the organic loading increased from 2.5 to 5.0 mg L^-1 TOC. The laboratory experiments in both Ghana and Aberdeen proved to be useful in explaining the effects of nutrients and trace elements on the DO cycles. It was evident that the higher the algal concentration, the greater was the DO cycle and 30% v/v (<I>c.a. </I>254 mg L^-1 chlorophyll 'a' content ≍ 17 g L^-1 biomass aqueous algal suspension) proved to be the most suitable concentration for investigations, because, with higher organic loadings, the 100% aqueous algal suspension proved to be too concentrated and caused total deoxygenation.

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.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1985. / Bibliography: leaves 82-92. / Microfilm. / vii, 92 leaves, bound ill. 29 cm

Follicular antral oxygen tension is thought to influence subsequent oocyte developmental competence. Despite this, in vitro maturation (IVM) is routinely performed in either 5 or 20% oxygen and while low oxygen has been shown to be beneficial to embryo development in many species, the effects of altering oxygen concentration during IVM have not been adequately investigated. Here we investigated the effects of a range of oxygen concentrations (2, 5, 10 & 20% oxygen) during IVM of mouse oocytes on a range of oocyte and embryonic parameters as well as fetal/placental outcome measures and cumulus cell gene expression. While common short term measures of oocyte developmental competence such as maturation, fertilisation, and embryonic development rates were not affected over the range of oxygen levels used, more in depth investigations found several striking differences. Following IVM at 5% oxygen, the oocyte mitochondria were found to have altered patterns of both membrane potential (a measure of mitochondrial activity) and distribution suggesting altered oocyte metabolism. Following IVF, the cellular make up of embryos was investigated. In blastocysts derived from low IVM oxygen (2%) there was found to be an increased number of trophectoderm cells, an increased level of apoptosis (although this was not of sufficient magnitude to account for the cell number difference) and more cells positive for both Cdx2 and Oct4 (markers of trophectoderm and inner cell mass cell types respectively) suggesting a less differentiated cell type. Furthermore, following embryo transfer, the ability of the embryos to implant or develop was not altered by IVM oxygen concentration; however, fetal and placental weights were reduced in the 5% oxygen group. Cumulus cell gene expression was also examined and was found to be altered both across IVM oxygen treatment groups and when compared to cells isolated from in vivo derived complexes. This change in gene expression elucidates some of the many ways in which oxygen concentration during IVM may be affecting the cumulus-oocyte complex (COC) and its future development. Together, this data highlights the importance of looking past common outcome measures when determining the effects of IVM culture conditions. The results of this study also suggest that while IVM oxygen concentration contributes to the perturbing nature of current IVM systems, it is only one of many constituents that require proper investigation, understanding and optimisation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1368831 / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2009

125 leaves : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1972) from the Dept. of Physics, University of Adelaide

Thesis (Ph. D.)--University of Adelaide, Dept. of Physics, 1983. / Includes bibliographical references (leaves [250]-268).

Thesis (M.S.)--University of British Columbia, 2007. / Includes bibliographical references.

Thesis (Ph.D.) -- McMaster University, 1997. / Includes bibliographical references (leaves 194-236). Also available via World Wide Web.