With increasing global population comes an increase in the need to safe and clean drinking water. Contaminants can arise in drinking water either naturally, or by the interaction of disinfection chemicals with naturally occurring materials, or simply due to by-products of the disinfection mechanism itself. Due to the oxidative nature of our disinfection treatments, these species are in highly oxidized states, and in some cases require chemical reduction to become less harmful. The present work demonstrates the capabilities of aqueous phase corona plasma in reductive treatment of oxidized contaminants found in drinking water. This study focuses on the treatment of the nitrate ion, bromate ion, chlorate ion and monobromoacetic acid, all of which can be found in typical drinking water systems. The second and third chapters within this thesis establish the optimal water matrix conditions for the treatment of bromate, chlorate and nitrate. These experiments investigate the influence of pH, temperature, presence and types of oxidative scavengers, dissolved gases and by-products that are made by this treatment process with these compounds. The main conclusion of these works is that aqueous phase corona discharge is capable of producing chemical compounds with sufficient energy to chemically reduce the nitrate, bromate and chlorate anions. Acidic conditions, under low dissolved oxygen scenarios facilitated the highest amount of reduction of the target contaminants, as well as having the presence of oxidative species scavengers. It was also observed that the anoxic environment could be obtained by introducing alcohols into the contaminated solution which generated sufficient cavitation and bubbling to strip the oxygen from solution. Through a comparison of various carbonaceous compounds as oxidative species scavengers, it was determined that the volatile alcohols provided a better performance than other soluble carbon sources, due to the decrease in dissolved oxygen. The fourth chapter considers different methods of introducing argon, oxygen and nitrogen into the test solution for the effect they would have on the treatment of solutions containing the bromate anion or monobromoacetic acid. The optimal pH for the treatment of monobromoacetic acid was also established, where again the acidic conditions prevailed. Tests were conducted to consider the effect of having the solution pre-saturated with the test gas, continually sparged, or with the gas passing through a hollow discharge electrode. The tests in which gas was blown through the discharge electrode greatly surpassed all other treatment regimes, where nitrogen provided the best removal for both contaminants under acidic conditions for bromate and under acidic and basic conditions for monobromoacetic acid. The fifth chapter provides conclusions for the overall thesis and recommendations for future work. / Thesis / Doctor of Philosophy (PhD)

<p> The objectives of the present study were to investigate the reaction mechanisms and the effects of certain physical variables on the overall reaction rate of the conversion of aqueous Na2S to gaseous H2S by bubbling with CO2 gas, which is a simultaneous absorption-desorption reaction.</p> <p> The dependence of reaction rate on the physical variables investigated were the volumetric flow rate and the CO2 partial pressure of inlet gas and reaction temperature. Potential advantages of a pressurized reaction system were also studied. It was found that the effect of reaction temperature on the overall reaction rate was relatively small as compared to that of inlet gas flow rate and CO2 partial pressure.</p> <p> Gas-liquid interfacial area was estimated and the overall reaction rate constant determined. It was found that the carbonation conversion of Na2S is first order with respect to both the HS- ion concentration of the liquid phase and the CO2 partial pressure of the inlet gas.</p> <p> The rate limiting step of the overall conversion reaction, under the present laboratory conditions, appeared to be the desorption of hydrogen sulfide.</p> / Thesis / Master of Science (MSc)

No description available.

No description available.

No description available.

No description available.

No description available.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23793号 / 医博第4839号 / 新制||医||1057(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 大森 孝一, 教授 花川 隆, 教授 渡邊 直樹 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Traditionally geothermal energy utilizes naturally occurring steam or hot water trapped in permeable rock formations through naturally occurring extraction wells or by implementing the hydraulic fracturing process by fracturing rock formations with water-based fracturing fluids. In contrast, in Enhanced Geothermal System (EGS) hydraulic fracturing process is utilized to create new or reopen existing fractures by injecting high-pressure fluid into deep Hot Dry Rocks (HDR) under carefully controlled conditions. Fracturing fluids are usually water-based that utilize an immense quantity of water. In EGS, they are essential for conducting hydraulic fracturing which bring the concern of technical approach and environmental impact. Thus, an alternative approach is to use waterless fracturing technologies, such as foam-based fracturing fluid. Foams are a complex mixture of the liquid and gaseous phases, where the liquid phase act as an ambient phase and gas is the dispersed phase. Foam fracturing fluids offer potential advantage over conventional water-based fracturing fluids, including reduced water consumption and environmental impact. Although foam-based fracturing has shown promising results in oil and gas industries, its feasibility has not been demonstrated in EGS conditions that usually involve high temperature and high pressures. One potential barrier to utilizing foam as fracturing fluid in EGS applications is that foams are thermodynamically unstable and will become more unstable with increasing temperature due to phenomena such as liquid drainage, bubble coarsening, and coalescence. Therefore, it is essential to stabilize foam fluids at high temperatures for EGS related applications such as fracking of HDRs. This project aims to evaluate the thermodynamic behavior of foams at high temperature and high pressure conditions closely resembling the geothermal environment. In this research, foam behavior was categorized as foam stability based on its half-life, i.e., the time taken by the foam to decrease to 50% of its original height. A laboratory apparatus was constructed to evaluate the foam half-life for a temperature range of room temperature to 200°C and a pressure range of ambient pressure to > 1000 psi. Two types of dispersed/gaseous phases, nitrogen gas (N2) and carbon dioxide gas (CO2), were investigated. Four different types of commercial foaming agents/surfactants with various concentrations were tested, including alfa olefin sulfonate (AOS), sodium dodecyl sulfonate (SDS), TergitolTM (NP – 40), and cetyltrimethylammonium chloride (CTAC). Moreover, five stabilizing agents, guar gum, bentonite clay, crosslinker, silicon dioxide nanoparticles (SiO2), and graphene oxide dispersions (GO), were also added to the surfactants to enhance foam stability. Experimental results showed that N2 foams were more stable than CO2 foams. It was observed that foam half-life decreased with the increase in temperature. Among all the surfactants, AOS foams showed the most promising thermal stability at high temperatures. Moreover, with the addition of stabilizing agents, foam's half-life was enhanced. Stabilizing agents such as crosslinker and GO dispersion showed the most stable foams with half-life recorded at 20 min and 17 min, respectively, at 200°C and 1000 psi. Finally, pressure also showed a positive effect on foam stability; with increased pressure, foam half-life was increased. Based on the experimental data, analytical models for the effect of temperature and pressure were developed, considering foam degradation is a first-order kinetic reaction that linearly depends on the foam drainage mechanism. The effect of temperature on foam half-life was studied as an exponential decay model. In this model, foam half-life is a function of drainage rate constant (DA) and activation energy (Ea) of the foam system. The effect of pressure on foam half-life was found to obey a power-law model where an increase in pressure showed an increase in foam half-life. Furthermore, a linear relation was studied for the effect of pressure on foam activation energy and drainage rate. Then the, combined effects of temperature and pressure were studied, which yielded an analytical model to predict the foam stabilities in terms of half-life for different foam compositions. This research indicates that with an appropriate selection of surfactants and stabilizing agents, it is possible to obtain stable foams, which could replace conventional water fracturing fluid under EGS conditions. / Mechanical Engineering

Our lab has shown that conditionally disrupting the tcfap2beta gene, responsible for the activating protein-2beta (AP-2beta) transcription factor, exclusively in the craniofacial neural crest cells, leads to anterior segment dysgenesis. Subsequent loss of the corneal endothelium results in the adherence of the iris to the corneal stroma, causing closure of the iridocorneal angle. The activating protein-2beta neural crest cell knockout (AP-2beta NCC KO) model involves a complete blockage of the both the conventional (through the trabecular meshwork) and non-conventional (uveoscleral) pathways for aqueous humor drainage, and therefore it could be used as a powerful experimental model for glaucoma. As shown by our previous work, elevated intraocular pressure (IOP) and a 35% decrease in the number of cells in the retinal ganglion cell (RGC) layer was observed in AP-2beta NCC KO mice by 2 months; 6 to 11 months sooner than other reported mouse models of glaucoma. These observations suggested that the AP-2beta NCC KO mouse could be a novel and cost-effective experimental model for glaucoma if the RGC loss occurred progressively rather than due to a congenital defect. The purpose of this research project was to investigate how the retinal ganglion cell layer and macroglial activity changes with respect to age in the AP-2beta NCC KO mutant through immunofluorescence. Specifically, it was investigated whether the loss of RGCs was progressive and due to the increased IOP caused by the blockage of the uveoscleral drainage pathway. A significant decrease in the number of RGCs was observed between P4 and P10 in the retinal periphery of both WT and AP-2beta NCC KO mice (p<0.05), which is indicative of the programmed cell death that occurs due to retinal pruning during development. No statistical difference between WT and AP-2beta NCC KO mice phenotypes was observed at postnatal day 4 (P4), suggesting that no developmental defect resulted in the significant loss of RGCs at 2 months. In all other time points investigated, while no statistical difference was found between WT and the AP-2 NCC KO mutant, a clear downward trend was present in the AP-2 NCC KO mutant retinal ganglion cell layer from P10 to P40. There was also an expression of glial fibrillary acidic protein (GFAP) by Müller cells, indicating the presence of neuroinflammation at P35 and P40. This substantiates the potential P42 starting point of neurodegeneration our lab previously observed. This was further corroborated with Müller cell-associated expression of GFAP at P35 and P40 exclusively in the AP-2beta NCC KO mouse. Overall, we have shown that the retinal damage observed in our AP-2beta NCC KO mouse is not due to a developmental defect, but rather occurs over time. Thus, this mouse model, which appears to block both the conventional and unconventional uveoscleral pathways, has a profound effect on aqueous humor drainage. As a result, the model requires relatively little time to observe an increase in IOP and subsequent RGC loss. Our findings suggest that the AP-2beta NCC KO mouse can be a novel, powerful, and extremely cost-effective experimental model for glaucoma. / Thesis / Master of Science (MSc)