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Embryonic exposure to the anticonvulsant drug Dilantin has been shown to have detrimental effects on development. Some of the observed effects include growth retardation, craniofacial defects, and even death. As the drug is metabolized, toxic intermediates form, which could be causing the characteristic abnormalities observed in embryos exposed to Dilantin. Culture of preimplantation mouse embryos in the presence of IOµg/mL or 20µglmL Dilantin show a slowing of development inl9.3% and 19.1% ofembryos respectively at Day 3 of culture. The toxic intermediates could be causing alterations in cyclin expression, cell cycle proteins, or the cell cycle timing itself. Previous research determined an in vivo baseline expression for cyclins B 1, E, D, A and cdk2, which was used to compare the expression of these cyclins and cdks between in vivo and Dilantin cultured embryos. Altered patterns in cultured embryos suggested that an alteration in cell cycle timing, therefore, S phase timing was determined in cultured untreated embryos utilizing 5'-Bromo-2-deoxyuridine (BrdU) incorporation and indirect immunofluorescence staining. The results of the experiment showed the second S phase was at 30 hpf, approximately 9 hours later, and the third S phase was at 54 hpf, approximately 3 hours later than previous in vivo literature reports. S phase timing in NaOH vehicle controls did not appear different from untreated controls. Dilantin showed S phase peaks at 24 and 55 hpf. In the Dilantin treated embryos, the nuclear staining intensity for the second S phase did not decrease as rapidly as had been observed in control embryos. Embryos that developed beyond the 2-cell stage demonstrated two distinct S phase peaks at 45 and 54 hpf, while embryos at the 2-cell stage did pass through the second S phase but not the third S phase. These data suggested that the Dilantin could be causing a delay in G2. Future experiments would be necessary to determine if the expression of G2 cyclins are being altered in Dilantin treated embryos. / Department of Biology

There is a lack of available technology to make small-scale power from biomass cost effectively. The proposed Hybrid Brayton cycle is an indirectly heated Brayton cycle with evaporative cooling for combined heat and power generation. It converts a direct fired microturbine to an indirectly heated power system. The Hybrid Brayton cycle offers a flexible biomass power generation platform in the 30 to 250 kWe range, achieving competitive efficiencies and advantages compared to other systems of similar power level. This cycle is designed to be implemented in remote and off-grids communities, small industries and net-zero communities, where local biomass feedstock is sustainably available. This proposed platform keeps operator qualifications to a minimum. In an effort to validate this new power cycle, a 30 kWe experimental facility was developed and initial commission phases performed. This facility purpose is to validate numerical model predictions and is used for optimization. The facility is described and results of the commissioning tests are reported with various problems encountered, solutions implemented and recommendations proposed. The thermodynamic model of the Hybrid Brayton cycle is also implemented in the MatLAB environment, incorporating experimental findings and new properties for humidified air at high temperatures. The MatLAB model confirms that an indirect fired Brayton cycle with evaporative cooling could be a viable approach for small scale distributed power generation using biomass. Additional experimental data of humidified air at elevated temperatures would provide more certainty in property predictions. The MatLAB model provides a modeling tool to allow resolving the issues identified during the commissioning of the test facility and offers alternatives to optimize various design configurations, implementing the most up to date property correlations for humidified air at elevated temperatures.

Growth is cyclic in nature, periods of activity alternating with periods of comparative rest (PEARL, 1925; WIGGLESWORTH, 1939). Many authors have attempted to construct mathematical expressions for this cyclic growth, in addition to ideal growth curves as an aid in the study of bionomics. Some of these will be dealt with later in this thesis where they prove relevant to the theme. The term “cyclic growth” may be broken down into its constituent parts: (a) it is well known that growth or increase in the bodily dimensions of an animal (or plant) can occur in two main ways, viz. (1) by increase in cell number (cell division); (2) by increase in the size of the cells already present. (Of course, production of cell products may also be considered growth.) The two modes of growth are not mutually exclusive. (b) The definition of “cycle” put forth by KLEITMAN (1949) will be used in this thesis, viz., “A cycle ..... is a repetitive series of events or successive changes of states, thus being either qualitative or quantitative in nature, and its own distinctive feature is one of order of occurrence, rather than duration. Cycles are intrinsic in origin; they may be influenced by inernal and/or external conditions, which affect them quantitatively, but seldom qualitatively.”[...]

Anaerobic ammonium oxidation (anammox) is a pathway that has been known for almost 2 decades, but few studies have investigated its importance in natural groundwaters. This thesis investigated the presence of anammox cells and the groundwater geochemistry of 2 sites (Elmira and Putnam) in southwestern Ontario where groundwaters are contaminated with high levels of nitrate and ammonium. Fluorescence in situ hybridization (FISH) was used to quantify the relative abundance of anammox cells in these waters. Our results showed that anammox cells could be detected in many wells at both sites and that their relative abundance varied between 0.45 and 4.81 % at the Putnam site, whereas it ranged between 0.8 to 8.4 % at the Elmira site. These values are within the same range as those obtained for marine and freshwater environments where anammox cells have been detected. In addition, indirect observations point to the fact that N cycling at the 2 sites might be linked to Fe and Mn reduction, but additional experiments are needed. In summary, our results corroborate the findings of N-labeled microcosm experiments which demonstrated that anammox was an important pathway of N cycling in those groundwaters and molecular analyses that detected important anammox organisms at the same sites.

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The provision of high quality analytical data is an essential prerequisite for understanding the biogeochemical cycling of nutrients in the aquatic environment. Due to the instability of samples collected for nutrient determinations however, in situ analysis is preferred. This approach also allows for high temporal and spatial resolution of the data and alteration of the sampling frequency to meet local environmental needs. Chapter One describes the role of nitrogen species, particularly ammonia and nitrate, in the aquatic environment, their sources, and possible environmental effects and summarises analytical techniques for their determination. Solid state miniaturised detectors and their suitability for in situ monitoring are also discussed. The characterisation and evaluation of a miniature Ocean Optics PSD - 1000 spectrometer and its suitability for field deployment is described in Chapter Two. Parameters investigated were optical resolution, wavelength repeatability, photometric linearity and instrumental noise and drift. The incorporation of the Ocean Optics PSD - 1000 miniature spectrometer into a gas diffusion Flow Injection (Fl) manifold for the determination of ammonia in natural waters is detailed in Chapter Three. Optimisation of the Fl parameters and analytical performance are discussed in detail. The development of an immobilised pH indicator and adaptation to a laminar Fl manifold is also considered. Chapter Four describes the use of the miniature spectrometer in a Fl manifold for the determination of nitrate and nitrite, with analytical figures of merit detailed. The increased information potential of the spectrometer (i.e. full spectral acquisition) facilitated the removal of the refractive index problem using dual wavelength correction. Miniaturisation and automation of the optimised nitrate manifold using micro-solenoid pumps and LabView™ graphical programming is described in Chapter Five. Field deployment of the automated system was assessed during a six week British Schools Exploring Society Expedition to Lesotho, S. Africa (in which an intensive biogeochemical survey of the Sehlabathebe National Park was conducted) and a three day campaign on the River Frome, Dorset, U.K. Chapter Six details the ion chromatographic analysis of major anions and cations (including ammonium and nitrate) in precipitation samples. Two sampling campaigns were conducted. One was at an urban site (Plymouth City Centre) from 27/01/98 - 11/05/98, and the influence of aerosol source on the chemical composition of Plymouth precipitation is discussed. The other involved the Austrian precipitation network and wet deposition trends for nitrate, ammonium and sulphate are discussed. The multivariate analysis technique of PCA was applied to both environmental datasets and the interpretation and merits of this statistical approach are considered.

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