2012 MU dissertations - Freely available online
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Item Experimental and simulation analysis of the jitter response of a single-shot oil switch with a high-K particle suspension(University of Missouri--Columbia, 2012) Yeckel, Christopher; Yeckel, ChristopherThis dissertation investigates an oil switching system to address and reduce the jitter observed in the breakdown electric field strength of a pressurized, oil dielectric. The experimental work is conducted in two phases, the first of which examines the effects of oil chemistry on breakdown statistics, and the second of which considers the effects of high-K particle additions to the best-performing fluids. A single-shot high voltage advanced dielectric test stand (HVADTS) was designed and built to test these oils. The HVADTS is capable of applying a 250 kV pulse with a 1-cos rise-time of 1.6 us to a pressurized oil dielectric. Numerous oil chemistries were evaluated, including straight-chain hydrocarbons and branched olefins, silicone and ester fluids, alkylbenzene and transformer oil. Following the oil chemistry evaluation, a high-K particle dielectric was added in concentrations up to 5 % (by weight) to the best-performing fluids. Parameters such as particle concentration, gap spacing, electrode surface conditions and ambient fluid pressure are investigated experimentally. The experimental analysis is supported by PIC electrostatic simulations and a suite of diagnostics such as SEM imagery, optical profilometry, water titration, mass-spectrometry, and particle measurements. This dissertation discusses several methods to successfully reduce the switch jitter of a self-break oil switch.Item Emerging adults views about couple and personal satisfaction in various gGender role relationships(University of Missouri--Columbia, 2012) Sells, Tamara G. Coon; Sells, Tamara G. CoonHuman development and Family studiesItem Bioreductive metabolism of small molecule nitroaromatics and N-oxides in hypoxia(University of Missouri--Columbia, 2012) Rajapakse, Anuruddha; Rajapakse, AnuruddhaHypoxia in tumors causes adverse effects to therapy and negatively impacts on patient prognosis. Identification and quantification of hypoxia is considered to have a strong impact on treatments in tumor therapy. Fluorescent-based detection to mark hypoxia may be vital to be used along with available methods such as radiochemical and immunohistochemical staining. In this work, the non-fluorescent 6-nitroquinoline (42) was used to investigate the production of a fluorescent 6-aminoquinoline (43) and other metabolites under bio-reducing hypoxic conditions. In the presence of the enzymatic reducing system NADPH:cytochrome P450 reductase/NADPH, 6-nitroquinoline (42) produced the fluorescent helicene (44), along with the non-florescent azo (45). An authentic sample of (44) was chemically synthesized and characterized and used to confirm the production of this molecule in the enzymatic process. Interestingly, the expected fluorophore (43) is not produced by NADPH:cytochrome P450 reductase/NADPH. In another study, the enzymatic reducing system xanthine/xanthine oxidase was used to reduce (42) under hypoxia to obtain (43). In these experiments (43) was produced and the yield is increased with xanthine concentration. Metabolic identification revealed that intermediates of typical nitro reduction pathway are present along with 6-nitroquinolone (51).which is formed by xanthine oxidase mediated oxidation of (42). The absence of (44) as a metabolite with xanthine/xanthine oxidase system highlights the complexity of bioreduction of nitroaromatics under hypoxia. In our laboratory, bio-activation of di-N-oxides such as tirapazamine (TPZ, 42) has been studied. TPZ undergoes one-electron bio-reduction to produce oxidizing radical, which causes DNA damage under hypoxia. In our laboratory, the mechanism by which TPZ mediated DNA damage has been investigated using TPZ and its analogs. Our evidence suggests that upon undergoing bio-reduction, TPZ produces hydroxyl radical as the DNA damaging radical species. Others have suggested another mechanism, which proposes the formation benzotriazine radical (38) upon dehydration process over the bio-reduction step. In the current work, TPZ analog 1,2,4-benzotraizine-1,4-dioxide (55) and deuterated (60) were used to test the dehydration mechanism. Isotopic content analysis of metabolites, derived from bio-reducing metabolism of (55) and its deuterated analog (60), using HRMS show evidence against the dehydration mechanism.Item Improving the usability and utilization of cancer registry data : the need to identify a core data set(University of Missouri--Columbia, 2012) Zachary, Iris; Boren, S. A. (Suzanne Austin)Cancer registries in the US and Canada have a long history of data standards and data collection that have developed from a minimal dataset to the standard dataset that is used now. Central Cancer Registries (CCRs) are good resources for cancer data, but are often underutilized. CCRs are recognized for high quality data standards by the Centers for Disease Control and Prevention (CDC) National Program of Cancer Registries (NPCR) or the National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) Program and receive certification from the North American Association of Central Registries (NAACCR). Each year, there are many changes to the data that are collected in the cancer registry field. Standards, requirements, and medical knowledge change frequently. The changes in the data collection process cause interference and decrease in quality of data fields, but also delays in the timely collection of cancer registry data. The objective of this study is to identify what essentially needs to be collected and what can be collected optionally in a cancer registry. The goal is a robust dataset that can be used for other disease registries, cancer data surveillance, public health, and research. CCRs and Cancer Centers (CR) were surveyed to identify and describe the data items that are collected and needed to achieve a dataset that can serve cancer surveillance and research. The surveys were analyzed to identify overlaps of common and special interests, as well as barriers. The results showed that cancer registries have data available, but need to look at the timely release of a core dataset for use in cancer surveillance and research. The surveys also evaluated the barriers to data use from cancer registries and barriers for data use of collected datasets to identify the initial data request process. Data in the cancer registry are in a format that can easily be adopted by public health, surveillance, and research. The requesting process needs to be accessible, understandable, and streamlined to enable successful use of the data.Item Structural diversity of proline catabolic enzymes revealed by small angle x-ray scattering, x-ray crystallography and light scattering(University of Missouri--Columbia, 2012) Singh, Ranjan Kumar; Tanner, John J., 1961-; University of Missouri-Columbia. Graduate School. Theses and Dissertations. Dissertations. 2012 DissertationsThe proline catabolic enzymes catalyze the 4-electron oxidation of proline to glutamate. The reaction involves two enzymes, proline dehydrogenase (PRODH) and Δ1-pyrroline -5-carboxylate dehydrogenase (P5CDH). Some bacterial organisms have both of these enzymes fused together, and the fused bifunctional enzymes are called Proline utilization A (PutA). In addition to these bifunctional enzymes, some PutAs are trifunctional, because they moonlight as transcription repressors of their own gene. Our lab recently reported that the quaternary structure of the bifunctional PutA from B. japonicam (BjPutA) is a ring-shaped tetramer. However, the structural organization of PutAs from other organisms is still unknown. In particular, there are no structures available for moonlighting trifunctional PutAs. We therefore utilized small angle X-ray scattering (SAXS) to obtain the overall shape of a trifunctional PutA from Escherichia coli (EcPutA). In addition, rigid body modeling of full-length PutA has been done with the help of SAXS data and crystal structures of DNA-binding and PRODH domains of EcPutA, and BjPutA crystal structure. Unique structural features of PutA have also been explored through multiple sequence alignments and homology modeling using the webservers like ClustalW, Espript, Phyre, and Swiss Model. The results obtained from sequence alignment study led us to work on finding the diversity in oligomeric states of PutAs. Finally, the structural basis of HPII disease that is related to disorder in human P5CDH was determined through X-ray crystallographic studies.