Petroleum spills causes contamination of drinking water with carcinogenic aromatic compounds including benzene and cresol. Current knowledge of anaerobic benzene and cresol degradation is extremely limited and it makes bioremediation challenging. Geobacter daltonii strain FRC-32 is a metal-reducing bacterium isolated from radionuclides and hydrocarbon-contaminated subsurface sediments. It is notable for its anaerobic oxidation of benzene and its unique ability to metabolize p-, m-, or o-cresol as a sole carbon source. Location of genes involved in aromatic compound degradation and genes unique to G. daltonii were elucidated by genomic analysis using BLAST. Genes predicted to play a role in aromatic degradation cluster into an aromatic island near the start of the genome. Of particular note, G. daltonii has two copies of the bss genes, which are responsible for the first step in anaerobic toluene oxidation. This bacterium is unique among the family Geobacteraceae and other toluene degraders in this aspect. The a subunits have 74% identity to one another. The remaining genes in each operon are not identical. BssA was upregulated when G. daltonii was grown on benzene and toluene while the grlA was upregulated during growth on m-cresol. Toluene was accumulated during degradation of benzene by cell lysate. Cells grown with benzene and toluene exhibited a similar protein profile compared to cells grown with benzoate. These results indicate that benzene is converted to toluene and further degraded via the toluene pathway. Both the bss and grl operons were predicted to have sigma54-dependent promoters. This was confirmed using 5' RACE and sequence analysis. E. coli transformed with the bss operon were able to grow in the presence of toluene but lost this capability when sigma 54 was knocked out. Growth was restored with complementation of sigma 54. The sigma 54-dependent signaling system bamVW was upregulated in the presence of all aromatic compounds tested. These results suggest that the bss operon is regulated via sigma 54-dependent mechanisms. This study significantly contributes to anaerobic aromatic gene regulation which is crucial in effective oil spill bioremediation.

No description available.

As the need for developing environmentally friendly chemistry continues to become more apparent, catalytic asymmetric hydrogenation has risen to the forefront as a reliable and eco-friendly method for enantioselective synthesis. We herein describe our progress toward the synthesis of valuable structural motifs via hydrogenation: chiral 1,2-diamines, 1,3-diamines and substituted cyclohexanes. We propose a strategy whereby protected 1,2-diimine and 1,3-diimine surrogates can be hydrogenated selectively and deprotected to furnish the desired chiral amines. Using this strategy, it was demonstrated that imidazolone precursors could be hydrogenated with >20:1 diastereoselectivity to give latent 1,2-diamines, albeit with no enantiomeric excess. We further propose that substituted benzene rings linked to an oxazolidinone chiral-auxiliary can be diastereoselectively hydrogenated using a heterogeneous metal catalyst. Following hydrogenation, the chiral cyclohexanes could be obtained in up to quantitative yield and 99% diastereomeric excess.

As the need for developing environmentally friendly chemistry continues to become more apparent, catalytic asymmetric hydrogenation has risen to the forefront as a reliable and eco-friendly method for enantioselective synthesis. We herein describe our progress toward the synthesis of valuable structural motifs via hydrogenation: chiral 1,2-diamines, 1,3-diamines and substituted cyclohexanes. We propose a strategy whereby protected 1,2-diimine and 1,3-diimine surrogates can be hydrogenated selectively and deprotected to furnish the desired chiral amines. Using this strategy, it was demonstrated that imidazolone precursors could be hydrogenated with >20:1 diastereoselectivity to give latent 1,2-diamines, albeit with no enantiomeric excess. We further propose that substituted benzene rings linked to an oxazolidinone chiral-auxiliary can be diastereoselectively hydrogenated using a heterogeneous metal catalyst. Following hydrogenation, the chiral cyclohexanes could be obtained in up to quantitative yield and 99% diastereomeric excess.

Benzene is a volatile organic air pollutant that is ubiquitous in the environment. It is frequently reported in urban airsheds, principally as a result of evaporative emissions from motor vehicles. Increasingly stringent fuel quality standards have resulted in lower mean benzene concentrations in many urban airsheds, however the concentrations reported indoors can be higher than those in urban airsheds. Mean indoor benzene concentrations can reach one order of magnitude higher than those reported in urban airsheds. Long term exposure to very high benzene concentrations can result in leukemia, however the health risks of long term non-industrial exposure in the general public are currently uncertain. An important part of determining the risks of non-industrial benzene exposure is to first determine the influence of various activities on 24-hour personal benzene exposure. Previous research has identified commuting in a private motor vehicle and refuelling with low benzene fuel as statistically significant contributors to nonindustrial benzene exposure in the Northern Hemisphere, however none has quantified the increase in benzene exposure as a result of these activities over a 24-hour period in the Mediterranean climate. The results of the 1987 TEAM study in the South Bay section of California reported that automobile exhaust was a significant contributor to non-industrial benzene exposure based on exhaled breath concentrations (p<0.05) and commuting in a private vehicle (p=0.0003) and refuelling (0.05) were important contributors based on personal benzene exposure concentrations (Wallace et al., 1988). The aims of this thesis were to identify the roles and importance of selected activities in personal exposure to benzene, to determine the increase in 24-hour personal benzene exposure attributable to these activities and quantify the risk posed by these activities in a Mediterranean climate. In particular, the aim of this thesis was to investigate whether commuting in a private motor vehicle and refuelling are significant contributors to non-industrial personal benzene exposure in a Mediterranean climate, or whether lifestyle and climate interact. This research was composed of a personal exposure study, a source monitoring study and a risk assessment. A cross-sectional personal exposure study was conducted for two reasons. Firstly, to quantify the mean personal benzene concentrations to which a representative sample of the general public of Perth was exposed as a result of their daily activities and behaviours. Secondly, to quantify the frequency of commuting by private motor vehicle and refuelling with low benzene fuel in Perth. Fifty participants were recruited for the personal exposure study, and asked to wear a monitor for 24-hour period(including weekends) in summer and winter and record their activities and locations in a diary. Prior to the monitoring they were asked to complete a questionnaire seeking background information on their home, lifestyle and behaviours. The results of the research revealed that there was not a statistically significant difference between the personal benzene exposure concentrations in summer and winter. An analysis of the questionnaire and time activity diary data using a generalised linear mixed model revealed that the time spent commuting in a private motor vehicle (â= 0.281, p<0.0001) and refuelling with low benzene fuel (â = 0.194, p=0.033) were statistically significant contributors to non-industrial benzene exposure. Each hour spent commuting resulted in a mean increase in 24-hour personal exposure of 0.74 ìgm-3 (â= 0.729 ìg m-3, p< 0.0001). The mean increase in exposure per hour of commuting in a private motor vehicle was larger in winter (â= 0.8 ìg m-3, p=0.008) than summer (â= 0.67 ìg m-3, p=0.004). Refuelling increased personal exposure by 1.50 ìg m-3 (1.49, p<0.0001) in each 24-period when refuelling was reported. Benzene source monitoring was conducted at selected locations in Perth for two reasons. Firstly, data quantifying non-industrial personal benzene exposure during refuelling and commuting in a private vehicle in Perth was needed, and secondly, to make an assessment of risk attributable to these activities. Benzene source measurements were conducted in two carparks in the Central Business District (CBD), in the vicinity of the northbound and southbound lanes of the Kwinana Freeway, and at a petrol station. The 7- day arithmetic mean benzene concentrations in the carparks were 4.49 ìg m-3 and 1.23 ìg m-3. The 7-day mean benzene concentrations northbound on the Kwinana Freeway was 2.78 ìg m-3, and the mean benzene concentration southbound was 2.57 ìg m-3. Benzene emissions in the carpark and on the Kwinana Freeway were measured during vehicle idling, which is representative of vehicle speed during heavy vehicle traffic. Benzene emissions at the petrol station were monitored in the vicinity of the petrol bowser, which is representative of emissions during refuelling. The 24-hour mean benzene concentration at the petrol station bowser was 38.15 ìg m-3. The results of this research revealed that refuelling and commuting in a private vehicle are the most significant contributors to non-industrial benzene exposure in Perth, and that the contribution of these two activities in Perth is far greater than in previous published research, on the basis of the results obtained from the generalised linear model. The results of this research quantified the increase in non-industrial benzene exposure from refuelling and commuting in a private motor vehicle in a Mediterranean climate for the first time, and quantified the lifetime excess cancer risk attributable to these activities in a Mediterranean climate for the first time. The lifetime excess cancer unit risks of these two activities in a Mediterranean climate were 7.4x10-5 or 7.4 per 100000 population for commuting and 15.03 x 10-4 or 15 per 10000 for refuelling.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 243-262). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Michigan, 1938. / "Reprinted from the Journal of the American chemical society, 60 ... (1938)." Includes bibliographical references.

A.C. Mueller's Thesis (Ph. D.)--University of Michigan, 1937. / Cover title. "Reprinted from Industrial and engineering chemistry, vol. 29, September, 1937." "Literature cited": p. 1072.

Thesis (Ph. D.)--Cornell University, 1916. / "Reprinted from Journal of physical chemistry 21, 48 (1917)."

Thesis--Catholic University of America. / Bibliography: p. 19.