The diesel-degrading capabilities of Acinetobacter calcoaceticus isolates LT1, LT1A and V2 were established in previous studies. LT1 and LT1A were isolated from diesel-contaminated soil and V2 was from soil contaminated with used engine oil. Isolates were grown in Bushnell-Haas medium supplemented with 1% sterile diesel. Determination of diesel-degradation patterns by gravimetric analysis and harvesting of cells for RNA extraction were performed at regular time intervals over a 60 day period. The involvement of genes alkM, alkR, rubA, rubB, estB, lipA, lipB, and xcpR in hydrocarbon degradation has been reported in previous studies. LT1, LT1A, and V2 were compared in terms of gene expression levels by real-time quantitative PCR. Expression levels were assessed by relative quantification and normalized against the 16S rRNA reference gene using the Relative Expression Software Tool - XL (REST-XL). Amplification of all genes, except rubB, was achieved with a high degree of efficiency. The expression of rubA, alkM, alkR, xcpR, and lipB based on pair-wise randomization, was all down-regulated in LT1A in relation to LT1. Highest expression levels of the aforementioned genes were documented during the initial stages of incubation for LT1 while LT1A showed highest expression levels midway through the study period. LT1, LT1A, and V2 achieved 58.6%, 51.7%, and 48.3% diesel degradation after 5 days of incubation, respectively. The higher percentage of diesel degradation achieved by LT1 can be attributed to higher levels of overall gene expression in the initial stages of degradation. Amplification of alkane hydroxylase alkM of V2 revealed a possible second hydroxylase gene that was expressed after 20 days of incubation. Amplification of alkR and xcpR in V2 isolates also resulted in multiple product formation. Very low lipB and lipA expression was detected in LT1 and LT1A and the absence of lipA expression in V2 suggests that lipases were not involved in diesel degradation. In contrast, estB was predominantly expressed in V2, and suspected to be involved in the release of a bioemulsifier that was only observed in V2 samples. Although all three isolates were comparably efficient in degrading diesel, the results of this study suggest that different mechanisms may be employed in the degradation process. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

Bacteria of the genus Acinetobacter are known to be involved in the degradation, leaching and removal of various hazardous compounds from the environment. Several studies of Acinetobacter spp. have reported on the genes involved in alkane degradation; but less is known about the proteins that are expressed at certain points within the degradation period. Acinetobacter sp. LT1A and Acinetobacter sp. V2 were isolated from diesel- and used engine oil-contaminated soils respectively. In a previous investigation (Toolsi, 2008), these isolates have been shown to demonstrate different gene expression patterns during diesel degradation using real time PCR. The real time PCR data showed that isolate V2 made use of multiple alkane hydroxylases whereas LT1A made use of only one, and the expression of the alkane hydroxylase regulator alkR and secretory protein xcpR also revealed multiple product formations in isolate V2 as compared to LT1A. Thus the objectives for the current investigation were to monitor the hydrocarbon degradation ability of Acinetobacter sp. isolates V2 and LT1A using medium chain (C14) and long chain (C28) hydrocarbon substrates and to compare the hydrocarbon degradation abilities and protein expression patterns of both isolates. To achieve this, the isolates were grown for 20 days in Bushnell Haas liquid medium supplemented with tetradecane (C14) or octocosane (C28) as a sole carbon source. Gravimetric analysis was used to monitor degradation and whole cell protein was extracted from the culture medium throughout the 20-day study period. The protein expression patterns were visualized using 1D and 2D PAGE. The 2D PAGE images were analyzed using the PDQuest Advanced 2D image analysis software (BIORAD). By day 20, approximately 90% of C14 was degraded by both isolates, whereas only 36% of C28 had been broken down. In both the C14 and C28 degradation assays, the isolates achieved significant amounts of hydrocarbon degradation as compared to the abiotic controls. One-dimensional and 2D SDS-PAGE gels indicated that there are observable differences in protein expression patterns between the isolates during C14 and C28 degradation. Both isolates achieved similar rates of hydrocarbon usage, but appear to do so using different, unidentified, protein systems. Analysis of the 2D-SDS PAGE gel images revealed that more proteins were required for the utilization of the long chain alkane (C28) as compared to the medium chain alkane (C14) for both isolates. Potential spots of interest were identified from the 2D SDS-PAGE images and sequenced. The identities of these proteins were found to be: a conserved hypothetical protein, TonB-dependent receptor protein, Peptidyl-prolyl-cis-trans isomerase and a Protein containing DUF1559. No alkane hydroxylase components were detected in this study. This investigation demonstrated the need for more studies at the proteomic level. Future investigations should focus on the insoluble subproteome of the isolates and make use of larger sample sizes (replicates) to reduce variation in spot detection and quantification. Genomic sequencing of the isolates will also shed light on the genetics and biochemistry of alkane metabolism in these Acinetobacter sp. isolates. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.

An existing encoder system was analyzed to determine why the system had failed. This encoder system was found to have slipped off the crankshaft, resulting in the need for a new encoder mount system. A new encoder mount was designed and installed on a Detroit Diesel 3-53 engine. The encoder mount was designed to ensure positive contact with the crankshaft while not allowing the mechanism to have the same type of failure that was determined. During the validation of the encoder, the push rod connected to the fuel injector rocker arm failed, preventing further validation of the system. The failure of the push rods is described.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The use of fuels (from crude oil) in vehicles is responsible for one of the biggest environmental challenges; SO2 emission. As a result most countries regulate their sulfur emissions, with the goal of getting to the use of 10 ppm sulfur fuels. These stringent fuel sulfur content requirements have resulted in intensive research being directed at alternative desulfurization technologies which will ensure the treatment of fuels to acceptable sulfur levels. Extractive desulfurization using ionic liquids (IL) may be considered as one of the most promising of these technologies and is the subject of the study presented in this work. This study served two major purposes: (1) to investigate the capacity as well as key parameters which affect the extraction efficiency of the IL; 1-butyl-3-methylimidazolium octylsulfate as a solvent for deep extractive desulfurization of real Fluid Catalytic Cracking Unit (FCCU) diesel fuel samples collected from a typical South African Refinery, (2) to study/find suitable solvents for the regeneration of sulfur-loaded 1-butyl-3-methylimidazolium octylsulfate and the efficiency and effectiveness of the regenerated IL in the desulfurization of diesel fuel. 1-butyl-3-methylimidazolium octylsulfate was selected due to its properties i.e. good extractive ability for S-compounds and insolubility in fuel oils. A 22.1% sulfur removal was achieved in the desulfurization of FCCU feed stream diesel fuel, while 96% sulfur removal was achieved for FCCU product stream diesel fuel. These results show that the IL is more effective in the selective removal of sulfur (S) from FCCU diesel product than from FCCU feed stream, suggesting that fuel sulfur content and stream composition affects the extraction efficiency and effectiveness of the IL. Based on thermodynamic considerations, hexane was selected as the most suitable solvent for the re-extraction of sulfur from spent IL. Regenerated IL was used for desulfurization of diesel and achieved highest sulfur removal of 95% and the IL was regenerated up to four times without appreciable decrease in efficiency. The results obtained herein show that ILs are effective in the desulfurization of real diesel oil samples when the sulfur concentration is not very high. Further studies on the recoverability of ILs as well as their environmental impact need to be done to support findings in this study. / GR2016

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xviii, 144 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 106-113).

Thesis (M.S.)--University of Nevada, Reno, 2008. / "December 2008." Includes bibliographical references (leaves 49-50). Online version available on the World Wide Web.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 162-166).

Respirometric experiments were performed to evaluate the role of nitrogen in aerobic diesel biodegradation. Specific objectives included 1) evaluating the effects of water potential induced by various nitrogen amendments on diesel biodegradation rates in arid region soils, 2) comparing concurrent effects of C:N ratios and soil water potential on diesel degradation rates, and 3), measuring gross rates of nitrogen cycling processes in diesel-contaminated soil to determine duration of fertilizer bioavailability. In all studies, increasing nitrogen fertilization resulted in a decrease in total water potential and correlated with an increase in lag phase and overall reduction in microbial respiration. Highest respiration and estimated diesel degradation was observed in the 250 mg N/kg soil treatments regardless of diesel concentration, nitrogen source, or soil used, suggesting an inhibitory osmotic effect from higher rates of nitrogen application. The depression of water potential resulting in a 50% reduction in respiration was much greater than that observed in humid region soil, suggesting higher salt tolerance by microbial populations of arid region soils. Due to the dependence on contaminant concentrations, use of C:N ratios was problematic in optimizing nitrogen augmentation, leading to over-fertilization in highly contaminated soils. Optimal C:N levels among those tested were 17:1, 34:1, and 68:1 for 5,000, 10,000 and 20,000 mg/kg diesel treatments respectively. Determining nitrogen augmentation on the basis of soil pore water nitrogen (mg N/kg soil H₂0) is independent of hydrocarbon concentration but takes into account soil moisture content. In the soil studied, optimal nitrogen fertilization was observed at an average soil pore water nitrogen level of 1950 mg N/kg H₂0 at all levels of diesel contamination. Based on the nitrogen transformation rates estimated, the duration of fertilizer contribution to the inorganic nitrogen pool at 5,000 mg/kg diesel was estimated at 0.9, 1.9, and 3.2 years in the 250, 500, and 1000 mg/kg nitrogen treatments respectively. The estimation was conservative as ammonium fixation, gross nitrogen immobilization, and nitrification were assumed as losses of fertilizer with only gross mineralization of native organic nitrogen contributing to the most active portion of the nitrogen pool.

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains x, 96 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 61-62).

Thesis (M.S.)--Michigan State University. School of Criminal Justice, 2008. / Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references (p.158-160). Also issued in print.