This study was conducted with the purpose of evaluating the possibilities of biologically oxidizing thiosulfate in a fluidized bed. A laboratory scale, autotrophic fluidized bed was continuously operated using a synthetic thiosulfate waste. The reactor was maintained at a hydraulic loading rate of 16.1 gpm/ft² and an influent thiosulfate concentration of 100 mg/1. The void space detention time at this loading rate was approximately 0.6 minutes. Through a series of influent pH adjustments, the fluidized bed demonstrated the ability to remove up to 75 percent of the applied thiosulfate, but the intermediate thiosulfate metabolic product, polythionate, proved difficult to oxidize. Due to the high oxygen demand of thiosulfate and the high concentration of volatile solids in the reactor, aeration with high purity oxygen was required to maintain an aerobic environment. Continuous operation of the fluidized bed also verified the preference of Thiobacillus bacteria to attach to a solid surface. Ammonia nitrogen and phosphorus requirements of the fluidized bed Thiobacillus culture were evaluated in a series of batch and oxygen uptake experiments. Unlike nitrogen, phosphorus was demonstrated to be an influential nutrient in the oxidation of thiosulfate. Trace nutrients which included zinc, iron, molybdenum, copper, and cobalt were also shown to influence the metabolic activity of the Thiobacilli. Acid decomposition of thiosulfate was briefly evaluated. Acidification below a pH of 3.0 resulted in rapid thiosulfate destruction and suggested a second mechanism for the removal of thiosulfate in biological waste treatment systems. / Doctor of Philosophy

The intricate dynamics and tensions of social histories--the realities of adversity-and anticipations of African American women greatly inhibit many of them from reaching their potential. Despite the adverse experiences, African American women have succeeded in achieving socioeconomic upward mobility. Their ability to defeat the odds has drawn attention to their patterns of adaptation and the process by which transformative experiences evolve. There is a strong need for qualitative research focusing exclusively on the early learning experiences of African American women and the transformative learning process; since studies of this topic are limited and most of them relate to a particular characteristic and its development. The purpose of this study was to examine the transformative learning processes of African American females who, despite their lower class origins, transcended the negative social and economic forces inherent in their backgrounds, thus moving beyond the status of their parents. Mezirow's transformative learning model, perspective transformation, was the conceptual framework guiding this inquiry. The research questions for this study were: 1. How has a small selected group of African American women from lower socioeconomic backgrounds been able to break the particular poverty cycle that their parents endured to become upwardly mobile achievers? 2. What transformative learning process did they engage to overcome specific obstacles in order to attain a higher level of socioeconomic mobility? 3. To what extent are the steps of perspective transformation descriptive of the process as experienced by the women in this study? A multiple-case study design was selected to accomplish the objective of the research. Participants were recruited through informal requests and referrals. Eight women were selected from an initial pool of twelve potential participants. The data were gathered through in-depth personal interviews and analyzed using Ethnograph coding software. Data were presented in descriptive narrative case study profiles. Four categories of major themes were identified as common among the participants: (a) a value laden upbringing, (b) productive self perception, (c) influences of others, and (d) significant mobility experiences. Findings revealed only a partial experience of transformational learning from these women. A strong maternal influence led to the indoctrination of lifelong values and beliefs consistent with a process in which mothers and grandmothers had begun but were unable to complete. This intergenerational transformative learning process passed down to the next generation, in this study. Results revealed upward socioeconomic mobility and a decline of the poverty cycle. Recommendations for educators and future studies were addressed. / Ph. D.

The paradigm of sustainable development has moved center-stage in the development community and strategies for achieving sustainable development are proliferating. However, the capacity of institutions to support sustainable development in non-industrialized countries has not been adequately addressed. There is a need to solve the sustainable development problem conceptually by linking strategy content and implementation issues with processes of strategy formulation internal to institutions. This study investigated the hypothesis that the dominant "technocratic" approach to strategy formulation, in which development problems are treated as technical, apolitical problems, creates strategies that probably will not implement sustainable development as intended. The World Bank's Strategy for Achieving Sustainable Development in Developing Countries (1992) was applied to the international tourism industry by twenty-five persons from industry, academia, non-government organizations and consultancies to identify implementation issues and problems that might be attributed to use of the technocratic approach. The study found that the World Bank's strategy probably will not implement sustainable development as intended due to fundamental conflicts in assumptions about how sustainable development can and should be achieved. The findings of this study support the argument made in the literature that a change in approach to strategy formulation is required. The findings also suggest that the proposed alternative to the technocratic approach may not be sufficient, because it is little more than a modification of the latter approach and does not resolve the fundamental contradiction between "induced" and "sustainable" development. A more fundamental shift in the values governing development may be required to adapt the modus operandi of development institutions to sustainable development and resolve the value conflicts that continue to diminish the possibility of consensus and action. Although this study provides knowledge of a limited scope, its findings and recommendations may guide an improved perception of the complex problem of identifying requirements for sustainable development and adapting institutions accordingly. / Ph. D.

The cell extract protein content of acetate- and methanol-grown Methanosarcina thermophila was examined by two-dimensional polyacrylamide gel electrophoresis to determine the extent of regulation by the growth substrate. More than 100 mutually-exclusive spots were present in acetate- and methanol-grown cells suggesting a high degree of regulation. Spots corresponding to acetate kinase, phosphotransacetylase, and the five subunits of the nickel-containing carbon monoxide dehydrogenase (CODH) complex were identified in acetate-grown cells. The nickel-containing methyl coenzyme M methylreductase from acetate-grown M. thermophila was purified 16-fold from a cell extract to apparent homogeneity. The enzyme had a native molecular weight of between 132,000 and 141,000 and contained three subunits with a configuration of a1B1y1-. The as-isolated enzyme was inactive, but could be reductively reactivated by either titanium (III) citrate or reduced ferredoxin. Reactivation with ferredoxin was a simplification over previously reported reactivation systems. ATP stimulated, but was not required for reactivation. The CO dehydrogenase enzyme complex from M. thermophila was purified and separated into its respective components: the CO-oxidizing nickel/iron-sulfur (Ni/Fe-S) component and the cobalt-containing corrinoid/iron sulfur (Co/Fe-S) component. EPR spectroscopy and spectroelectrochemical titration of the Fe-S centers of the Ni/Fe-S component indicated the presence of two low-potential [4Fe-4S]2+/1+ centers and third high-potential center whose Fe-S configuration is unknown. When reduced with CO, the NilFe-S component exhibited a previously unobserved Ni-Fe-C EPR signal. The Co/Fe-S component contained one [4Fe-4S]2+/1+ cluster, and the as-isolated corrinoid in the component was in the base-off conformation suggesting that modulation of the electron density of the cobalt ion may result in a modified reactivity of the active site of the corrin. The CODH enzyme complex and isolated Co/Fe-S component reductively dechlorinated trichloroethylene to cis-dichloroethylene, trans-dichloroethylene, 1,1-dichloroethylene, vinyl chloride, and ethylene. Factor III also catalyzed the dechlorination of trichloroethylene when in the presence of titanium (III) citrate. Reconstitution of the Co/Fe-S component with the CO-reduced NilFe-S component also allowed dechlorination demonstrating an electron transfer from the reduced Ni/Fe-S component to the Co/Fe-S component. / Ph. D.

In order to elucidate the function of the nifU gene product in nitrogenase maturation in Azotobacter vinelandii. the gene product has been hyperexpressed in Escherichia coli and characterized by various biophysical techniques. Following the initial characterization, site-directed mutagenesis of conserved cysteinyl residues was performed in order to gain further insight into the structure/function relationship of NifU. Both the Fe protein and the MoFe protein of nitrogenase require processing by additional nif genes including nifM (Fe protein), and nifE, N, B, H, V, and Q (MoFe protein). Two additional genes, nifU and nifS, are required for the maturation of both nitrogenase component proteins. It has been proposed that they may somehow be involved in metallocluster biosynthesis (Jacobson et al., 1989b). Our laboratory has determined that the nifS gene product (Nifs) is a pyridoxal-phosphate containing enzyme capable of catalyzing the desulfurization of L-cysteine and can provide the inorganic sulfide necessary for in vitro metallocluster biosynthesis of the Fe protein (Zheng, et al., 1993: Zheng, et al., 1994). / Ph. D.

To identify antigens unique to live Pasteurella multocida P1059, 10 week old specific pathogen-free (SPF) chickens were vaccinated three times with one of the following: viable cells from P. multocida P1059, 3865, 3866, or cells from formalin-killed strain PI059 or formalin-killed strain P1059 that were opsonized with antiserum directed against killed strain PI059 prior to immunization. Vaccinated birds were challenged with 1.5 x 10⁷ CFU of live strain P1059. Eight, 71, 86, and 50% of the birds that received live strains P1059, 3865, 3866 and killed strain P1059 (respectively), exhibited clinical signs of fowl cholera. Antisera directed against live strain PI059 recognized 23 proteins ranging from 14- to 92-kilodaltons (kDa); 20 of which were adsorbed by strain 3865. The molecular masses of the three remaining proteins were 25-, 30- and 43-kDa. A genomic library of strain P1059 was constructed using the plasmid vector pUC-19 and screened with antisera against live strain P1059; 12 out of 4,100 clones were recognized. The inserts of the plasmids from these clones ranged from 0.48- to 6.S-kilobases (kb) in length. Five of the 12 clones expressed proteins with molecular masses of 34-, 37-, 42-, 46- and 55-kDa. Escherichia coli CSR603(pOP43- 2G) and CSR603(pOP33-SF) expressed proteins recognized by antisera directed against live strain P1059. E. coli CSR603(pOP43-2G) expressed an epitope(s) which was recognized by antisera directed against strains 3865 and 3866. Conditions for transformation were optimized and attempts were made to create a shuttle vector in order to establish a cloning system for gene expression in P. multocida. The highest efficiency of transformation (1.25 x 10⁷ CFU/μg DNA) was obtained when 7.6 x 10¹⁰ cells of P. multocida R473 were electroporated at 12.5 kV cm⁻¹ for 10 ms with 5 ng of the plasmid, p VM109. Of the six strains tested, representing serogroups A, B, D and E, all were transformed successfully. Vectors including pBR322, pUC19, pJFF224-NX and pSP329 were unable to transform P. multocida. To create a shuttle vector for gene expression in P. multocida, a Pasteurella plasmid (pLAR-1) was cloned in both orientations into the BamH I site of pBR322. These plasmids, pLRBR-21 and pLRBR-67, had a transformation efficiency of 4.5 to 8 x 10⁴ CFU/μg of DNA in strain R473. Chromosomal DNA containing the Brucella abortus copper-zinc superoxide dismutase gene was cloned into the Cla I site of pLRBR-21. The 1.8-kb fragment encoding a 42-kDa Pasteurella protein was cloned into an additional unique site (Nru 1) of pLRBR-21 to determine if this plasmid was a viable shuttle vector for gene expression in P. multocida. / Ph. D.

The Probability of the Adoption of Change (PAC) model (Creamer & Creamer, 1986a, 1986b, 1988, 1989, 1990; Creamer, Creamer, & Ford, 1991) is a planned change model consisting of nine constructs postulated to influence the success of planned change projects. The constructs in the model include circumstances, value compatibility, idea comprehensibility, practicality, superintendency, championship, advantage probability, strategies, and opposition. The PAC model was tested in the context of curriculum revitalization in undergraduate agriculture and life sciences programs. Faculty and administrators from colleges and departments of agriculture and life sciences throughout the United States responded to survey items written to measure the relationship of the PAC model constructs with the success of curriculum revita1ization projects with which they, the respondents, had been involved. Participants also responded to items written to assess their perceptions of the success of the projects. / Ph. D.

This thesis creates a complementarity relationship with the use of timber and concrete as primary structural and accent materials. Key elements of this thesis include (1) The development of a wood latticing system (2) Stairs that posses a strong sculptural language (3) The Lantern, a free standing lobby/box office, clad in wood and glass (4) Circulation towers that accommodate balcony seating. Studies of these elements went through many iterations resulting in over one hundred drawings. Progression of these drawings are directed to the interpretation of building form and the interaction with the site. These concepts are then implemented in the design of a multifaceted music venue located on a hillside in the New River Valley. Minutes from the college town of Blacksburg, Virginia this event complex caters to an array of musical functions. Spaces include The Lantern, which is a multipurpose lobby/lounge, the main auditorium, and an outdoor amphitheater. / Master of Architecture