2014 MU dissertations - Freely available online
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Item Skill-based reliabilism(University of Missouri--Columbia, 2014) Marshall, Daniel C.; Weirich, Paul, 1946-Item Driven or drafted : is there a connection between principals' motivational factors, leadership style approaches, and perceived effectiveness?(University of Missouri--Columbia, 2014) Aldrich, Donna Lane; Watson, Robert LewisItem Identity and reputation in organizational collectives(University of Missouri--Columbia, 2014) Hofherr, Peter William; Westgren, Randall E.This research explores the attributes of the identity-based mechanisms of group collective action. Recognizing that wine trails are organizational collectives that market themselves and the region in which they reside, the research tests for the presence of identity-based attributes that reflect the social, institutional, cultural and physical aspects of the region. Using exploratory and confirmatory factor analysis, this research finds that the content of both external and internal stakeholders' expectations and perceptions used in the reputational comparative process includes attributes of institutional, place-based, cultural, and social norms. This confirms that the specific content of stakeholders' expectations and perceptions are developed in part from institutional norms, social categories, and structural roles associated with the wine trail organization and the geographic region in which they reside.Item Identification and characterization of atrazine-degrading phytochemicals in eastern gamagrass(University of Missouri--Columbia, 2014) Willett, Cammy Drost; Lerch, Robert N.; Goyne, Keith W.Naturally occurring phytochemicals of the 1,4-benzoxazin-3-one (Bx) class exhibit broad chemical reactivity that includes detoxification of chloro-triazine herbicides. Atrazine (6-chloro-N-ethyl-N’-(1-methylethyl)-1,3,5-triazine-2,4-diamine) contamination of surface and ground water remains an environmental concern that warrants continued research to identify mitigation and decontamination strategies. In this research, the Bx compound DIBOA-Glc (2-β-D-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one) was identified as the atrazine-degrading compound present in eastern gamagrass roots (EG, Tripsacum dactyloides (L.) L.); identifying Bx compounds in the Tripsacum species for the first time. In order to further characterize the reaction between atrazine and DIBOA-Glc, methodology was developed in which bulk quantities of highly pure DIBOA-Glc were produced using HPLC separation of crude methanol extracts of EG roots. The resulting pure DIBOA-Glc was then used to characterize the atrazine-DIBOA-Glc reaction in terms of reaction kinetics, identification of intermediates and products, and pH effects. Findings from these studies demonstrated that DIBOA-Glc was consumed in the reaction and was not acting catalytically. A conjugate of DIBOA-Glc and atrazine was identified as a stable reaction intermediate. Additionally, the formation of hydroxyatrazine (2-hydroxy-4-ethylamino-6-isopropylamino-s-trazine) and Cl[superscript -] as reaction products confirmed that the reaction mechanism was a nucleophilic attack of the hydroxamic acid moiety at the C-2 position. Use of naturally occurring phytochemicals, such as DIBOA-Glc, in concert with existing mitigation practices may allow producers to continue the use of atrazine as a valuable crop protection tool while simultaneously protecting the soil and water resources in environments where atrazine is used.Item Optimizing the tissue engineering of tubular organ structures by bio-printing(University of Missouri--Columbia, 2014) Shafiee, Ashkan; Forgacs, GaborTissue engineering and regenerative medicine may help to save people’s lives by fabricating new organs. Towards this goal our objective is to optimize the conditions for cells to self assemble into functional structures, such as tissues and eventually organoids. To facilitate self-assembly we employ the technology of bioprinting. To maintain the extended cellular assemblies, they need to be vascularized. Thus we first concentrated on the fabrication of blood vessels. We prepared convenient bioink particles, multicellular units composed of the relevant cell types and we deposited them into a configuration, consistent with the shape of the vessel. Self-assembly and the maturation of the construct takes place post-printing in special-purpose bioreactors by the fusion of the bioink units and the rearrangement of the cells within them. The time to achieve near physiological biomechanical properties has so far been found by trial and error. We report the experimental part of an experimental-theoretical-computational framework to optimize the postprinting maturation process, in particular the fusion of the bioink units. The connection between experiments and computer simulations were guided by theory. Here we report the results of extended fusion experiments and on their comparison with predictions of the theory. The excellent agreement we found, on one hand, provided a verification of the theoretical component of the formalism, and, on the other hand, the input for the computational component of the formalism. Specifically, our experiments, together with the theory, allowed the calibration of the basic simulation parameters, which in turn allows the full implementation of the computational component of the formalism to optimize the fabrication of blood vessels through the bioprinting process.