Magister Legum - LLM

It is common practice to design water chiller units and heat exchangers in such a way that they do not operate within the transition region. This is mainly due to the perceived chaotic behaviour as well as the paucity of information in this region. Due to design constraints or change of operating conditions, however, exchangers are often forced to operate in this region. This is even worse for enhanced tubes as much less information within this region is available. It is also well known that the entrance has an influence on where transition occurs, adding to the woes of available information. The purpose of this study is thus to obtain heat transfer and friction factor data in the transition region of fully developed and developing flows inside smooth and enhanced tubes, using water as the working fluid, and to develop correlations from these results. The use of different inlets, tube diameters and enhanced tubes was also investigated with regards to the commencement of transition. Heat transfer and pressure drop data were obtained from six different types of tubes with diameters of 15.88 mm (5/8′′) and 19.02 mm (3/4′′). Low fin enhanced tubes with a fin height to diameter ratio of 0.4 and helix angles of 18◦ and 27◦ were investigated. Heat transfer was obtained by means of an in-tube heat exchanger with the cooling of water being used as the test fluid. Reynolds numbers ranged between 1 000 and 20 000 while Prandtl numbers were in the order of 4 to 6. Uncertainties in heat transfer coefficient and friction factors were on average below 2.5% and 10% respectively. Adiabatic friction factor results showed that the use of different inlets influenced the commencement of transition. The smoother the inlet profile the more transition was delayed, confirming previous work done. The effect of increasing tube diameters had a slight delay in transition. Enhanced tubes caused transition to occur at lower Reynolds numbers which was accounted for by the fin height and not the helix angle. Heat transfer results showed that transition occurred at approximately the same Reynolds number for all the different inlets and enhanced tubes. This was attributed to the secondary flow forces influencing the growing hydrodynamic boundary layer. These secondary flow forces also influenced the laminar heat transfer and diabatic friction factors with both these parameters being higher. Turbulent enhanced tube heat transfer results were higher than those of the smooth tube, with the tube with the greatest helix angle showing the greatest increase. Correlations were developed for all the tubes and their inlets and predicted all the data on average to within 3%. / Thesis (PhD)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

Orientador: Andrigo Barboza De Nardi / Resumo: Os anti-inflamatórios não esteroidais (AINEs) COX-2 seletivos possuem efeito antitumoral mais potente que os AINEs tradicionais e desencadeiam menos efeitos colaterais. Dentre estes efeitos indesejáveis cabe citar alterações gastrintestinais e da perfusão renal, quando administrados por longos períodos para o tratamento auxiliar da dor ou do próprio câncer. Com estes preceitos hipotetizou-se que o carprofeno como AINEs seletivo usado por um período de três meses tem um efeito benéfico em pacientes afetados por carcinoma mamário e que os efeitos sobre o sistema renal vão ser moderados e apenas ligados à alteração da perfusão renal e não à alteração de sua função, assim, objetivou-se avaliar a hemodinâmica renal por meio das técnicas ultrassonográficas Doppler e ultrassonografia contrastada por microbolhas (CEUS), os parâmetros clínicos e laboratoriais rotineiros de função renal e a evolução clínica de cadelas com carcinomas mamário, submetidas à mastectomia, e tratadas ou não com carprofeno. Foi realizado um estudo clínico prospetivo, aleatorizado em 26 cadelas, distribuídas equitativamente em um grupo tratado que recebeu carprofeno 4,4 mg/kg/dia por 90 dias e um grupo controle que não recebia medicação anti-inflamatória. Foram obtidos os parâmetros Dopplerfluxométricos da artéria renal, caraterísticas da perfusão renal pela CEUS, análises celulares e bioquímicas hematológicas e analise clínicas uma vez por mês durante seis meses. Estes dados foram submetidos a comparação entr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Selective COX-2 nonsteroidal anti-inflammatory drugs (NSAIDs) have a more potent antitumoral effect than traditional NSAIDs and trigger fewer side effects. Among these undesirable effects, it is important mentioning gastrointestinal and renal perfusion changes, when administered for long periods in the auxiliary treatment of pain or cancer. With these precepts, it was hypothesized that carprofen as selective NSAIDs used for a period of three months has a beneficial effect on patients affected by breast carcinoma and that the effects on the renal system will be moderate, linked only to renal perfusion alteration and not to function alteration, consequently, the objective was to evaluate renal hemodynamics by Doppler ultrasound and microbubbles contrast enhancement ultrasound (CEUS) techniques, routine clinical and laboratorial parameters of renal function and clinical evolution of bitches with breast carcinomas, submitted to mastectomy, and treated or not with carprofen. A prospective, randomized clinical study was carried out on 26 bitches, equally distributed in a treated group that received carprofen 4.4 mg/kg/day for 90 days and a control group that did not receive NSAIDs medication. Dopplerfluxometric parameters of the renal artery, CEUS renal perfusion characteristics, cell and biochemical hematological analysis and clinical analysis were obtained once a month for six months. These data were subjected to comparison between groups and moments by analysis of variance (ANOV... (Complete abstract click electronic access below) / Mestre

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23074号 / 医博第4701号 / 新制||医||1049(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 妹尾 浩, 教授 増永 慎一郎, 教授 川口 義弥 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

The presented thesis deals with preparation of GaN nanocrystals with a metal core. In the theoretical part of the thesis GaN with its properties and applications is introduced. Further, some of the preparation methods of GaN are presented, mainly focusing on MBE growth. Deposition of metal NPs from colloidal solution and the state of the art approaches to enhance luminescence of GaN based structures is discussed. The experimental part follows three steps of preparation of GaN crystals with the Ag core. In the first step the Ag NPs are deposited on the Si(111) substrate. In the second step the Ga deposition process is optimized and in the third step the deposited Ga is transformed into GaN. After the Ga deposition the samples were analyzed by SEM/EDX and SAM/AES. The properties of prepared GaN crystals with the Ag core were studied by XPS, photoluminescence and Raman spectroscopy.

The transition to efficient, affordable, reliable, and clean sources of energy is one of the major challenges of this century. Despite advances in renewable energy technologies, fossil fuels remain the primary source of energy, and are expected to remain so for decades to come. Natural gas, a relatively cleaner fossil fuel vital to many industries such as power generation, is expected to play a more prominent role in the global energy mix. However, with the decline in conventional gas discoveries, it is crucial to improve recovery from mature reservoirs to satisfy the growing demand for energy. On the other hand, the combustion of fossil fuels significantly contributes to carbon dioxide (CO2) emissions and climate change, an issue of major concern. CO2-based enhanced gas recovery (EGR) is a useful method to improve gas recovery, and simultaneously store CO2 securely in depleted gas reservoirs, therefore reducing net CO2 emissions. However, CO2 injection for EGR has a drawback of excess mixing with the methane therefore reducing the quality of gas produced, and leading to early breakthrough. Although this issue has been identified as a major obstacle in CO2-based EGR, few strategies have been suggested to mitigate this problem. In this study, we propose a novel hybrid EGR method to reduce mixing and delay breakthrough. We propose the injection of a slug of carbonated water before beginning CO2 injection. Carbonated water hinders CO2-methane mixing, and reduces CO2 mobility therefore delaying breakthrough. We use reservoir simulation to assess the feasibility and benefit of the proposed method. Through a structured design of experiments (DoE) framework, we perform sensitivity analysis, uncertainty quantification, and optimization to identify the ideal operation and transition conditions. We show that the proposed method has an overall benefit for up to ~3% pore volumes of carbonated water injected. The proposed method is mainly influenced by the heterogeneity of the reservoir, slug volume injected, and production rates. Through Monte Carlo simulation we show that high recovery factors and storage ratios can be achieved while keeping recycled CO2 ratios low. These results are encouraging and highlight the overall benefit of the proposed hybrid EGR method.

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Session presented on Monday, November 9, 2015: The purpose of this study was to evaluate the effectiveness of a pilot project designed to assist student learning by incorporating weekly post-lecture quizzes intended to increase the spacing time of studying. Numerous studies have reported the positive effect that test-enhanced learning (TEL) has on the long-term retention of information, or what is known as the testing effect, and that it is an effective teaching/learning strategy. We hypothesized that weekly quizzes would increase the frequency and time that a student spent studying lecture material and that the result would be better long-term retention of information and increased grades. Using a pretest-posttest study design, we used three retrospective sets of data from second semester baccalaureate nursing students for fall 2013 (n = 75) and spring 2014 (n = 105). Data gathered included: the Assessment Technologies Institute (ATI) Registered Nurse Content Mastery Exam for Fundamentals; the number of students with a grade of <75 prior to the final exam; and the number of students that failed the course. Standard teaching/learning strategies were used fall 2013 (pretest group), while TEL was implemented in spring 2014 (posttest group). For the pretest group's ATI scores, there were 6 (6%) Level 3, 61 (58%) Level 2, 13 (17%) Level 1, and 1 (<1%) below Level 1. For the posttest group's ATI scores, there were 18 (23%) Level 3, 46 (59%) Level 2, 13 (17%) Level 1, and no students below Level 1. There were 52 (50%) students with a grade <75 before the final exam in the pretest group, and 6 (8%) students in the posttest group. A total of 6 (6%) students failed the course in the pretest group, compared to 5 (6%) in the posttest group. The findings indicate that TEL is an effective teaching/learning strategy that had a positive impact on the retention of course material. Limitations include that the study was not randomized, used a small sample size, was conducted at a single institution, and in a single course. Additional research is needed to determine the effectiveness of TEL in other settings and courses.

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