Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"microbial reduction"”.
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Microbial Reduction of Perchlorate in Fixed Bed Biofilm Reactors for Water Treatment
… of biofilm structures (thin biofilm and large microbial aggregates) growing in porous media and their effect on the responses of a BAC to changes in influent dissolved oxygen (DO) levels was studied. The effect of mass transfer resistance that can reduce oxygen's negative effect on biological …
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Speciation and microbial transformation of chromium, arsenic and mercury in municipal landfill leachate
… in municipal landfill leachate (MLL) to evaluate microbial transformation of the heavy metals in the landfill system. MLL is a complex matrix that contains multiple inorganic and organic contaminants, as well as a consortium of bacteria in an environment of changing pH and redox potential. …
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Uranium isotopic fractionation induced by U(VI) adsorption onto common aquifer minerals
… numerous sites in the western United States. Bioreduction of soluble, mobile U(VI) to U(IV)-bearing solids is a common remediation strategy. Uranium isotopes (238U/235U) have been utilized to track the progress of microbial reduction, with laboratory and field studies finding a ~1‰ isotopic …
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Physical chemistry of microbially-reduced smectites
… to reduce smectite structural Fe and the effect microbial reduction has on clay swelling, flow behavior, and the crystal structure was studied to better understand the reduction process. Structural Fe reduction by combinations of Pseudomonas bacteria is a diffusion driven process in which …
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Development of a Chlorine Dioxide Gas Concentration Monitoring Unit and Kinetic Analysis of the Effect of Chlorine Dioxide Treatment on Color and Microbial Content Change of Spinach
… interest in recent years. In an effort to reduce microbial loads present on fresh produce, gaseous sanitizers are being explored because of their higher diffusivities. In this study, spinach was exposed to chlorine dioxide (ClO2) gas, in an effort to determine concentration and exposure time …
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The behavior of uranium in the environment : bacterial reduction of an aqueous uranium species
… as the electron acceptor in lieu of oxygen. The reduction of U(VI) to U(IV) removes uranium from solution and forms an insoluble compound known as uraninite. Ultraviolet/Visible Spectroscopy was used to analyze uranium ion complexion with several oxazine dyes that included Brilliant Cresyl Blue, …
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Taphonomic studies of fossil preservation in coarse-grained siliciclastic environments
… sandy and silty sediments commonly preserve microbial fossils and textures as well as the fossils of soft-bodied organisms. The rarity of similar fossils and textures in coarse-grained siliciclastic strata of the later Phanerozoic suggests that a taphonomic window facilitated this mode of …
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Synthesis of pyrrolizidine diols via azide-diene cycloadditions
… was also investigated, and was realized in the microbial reduction of only one of the enantiomers of alcohol ill protected as ester 248, providing potential access to either enantiomeric series of pyrrolizidine diols. [see document for diagram of chemical reaction]
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Influence of light and algae on nutrient transformations at the sediment-water interface of an agricultural stream
… the organic matter pool exhibited evidence of microbial reduction. The closed-bottom mesocosm showed NH?⁺ increased likely due to photochemical oxidation. These results show the importance of promoting exchange through the subsurface and across the sediment-water interface due to the positive …
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Investigating uranium mobility using groundwater 238U/235U data and a reactive transport model
… the 238U/235U isotope ratio. Bioremediation, the microbial reductive immobilization of aqueous U(VI) to solid U(IV), has been proposed as a U remediation technique. Both laboratory and field experiments have demonstrated that microbial reduction of U(VI) alters 238U/235U, producing a 238U-enriched …
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Coupled Biogeochemical Cycles of Iron and Organic Carbon in Soils
… Fe and OC during redox processes. We found that microbial reduction of Fe can lead to substantial mobilization of OC in natural soils under anaerobic incubation. OC electron accepting capacity (EAC) strongly regulated Fe reduction, demonstrating that the biogeochemical cycles of Fe and OC are …
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Comparison Of Denitrification Potential Around A Tile Drain And In Aquifer Sediments: Oakes, ND
<p>Denitrification, the microbial reduction of nitrate (NO<sub>3</sub>-) in groundwater, has three requirements: limited oxygen, bacteria capable of mediating the reaction, and electron donors for the bacteria to use in the redox reactions. The critical factor for aquifer denitrification is the …
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Evaluation of the Correlation Between the Oxidation Reduction Potential and Free Chlorine Residual for Different Chlorine Sources Used in Poultry Drinking Water Sanitation
… of all bacteria. In recent years, the oxidation-reduction potential (ORP) meter has been a tool utilized by the poultry industry to monitor chlorine efficacy in drinking water. An ORP reading of 650-750 millivolts (mV) has become the industry standard for assuring an acceptable sanitizing …
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Novel Approaches to Exposure Assessment and Dose Response to Contaminants in Drinking Water and Food
… can be mitigated through a quantitative microbial risk assessment (QMRA) framework that follows a farm-to-fork model. Methods to ensure greatest microbial reduction include: employed intervention strategies at slaughter plants (i.e., water washing of beef carcass), improved cooking times …
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Investigation of Hexavalent Chromium Reduction by Aerobic Bacteria in Water and Soil
… of cost-effective remediation technologies. Microbial reduction of Cr(VI) to non-toxic trivalent chromium (Cr(III)) is a promising technique. In this study, five bacteria were isolated from the soil of Cr(VI) contaminated plating facility in Putnam, CT. Then were identified tentatively as …
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Studies on the biotransformation of chromium (VI) by methane oxidising bacteria.
… study was conducted to investigate the microbial reduction of chromium [Cr(VI)] in general and the potential for biological treatment of Cr(Vl)-containing wastes in particular. Cr(VI) was transformed to non-toxic Cr(III) by Escherichia coli ATCC 33456. It was observed for the first time …
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Fate of Foodborne Pathogens During Osmotic Dehydration and Subsequent Storage of Apples
… 4% and 8% to determine its efficacy as an antimicrobial agent. The storage effect of osmotic dehydrated apples on pathogen survival was also tested for seven days at 4°C. Samples were withdrawn at appropriate time intervals, diluted with 0.1% peptone water and surface plated onto recovery …
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Biosorption of uranium and its effect on uranium transport in groundewater
In past years, microbial reduction has been explored as a remediation method for uranium-contaminated groundwater at U.S. Department of Energy sites with promising results. Although transport models have been improved to include variations in geochemical concentrations, reductive microbial …
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The transport and reaction behavior of arsenic in groundwater : experiments and case studies
… in the environment, but less is know about the reduction and release of arsenic. A continuous injection tracer test was conducted at the USGS Cape Cod research site (Mass.,USA) in order to investigate natural reduction of As(V) to As(III) in an iron reducing environment. As(V) reduction was …
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The antimicrobial effect of orange, lemon and bergamot esential oils against Enterococcus sp
Citrus essential oils (EO) are potential antimicrobials, first described as such in 1949 by Piacentini. Due to their acceptability in terms of fragrance and flavour characteristics, they lend themselves to use both in food and in clinical practice. Lemon (Citrus limon) or sweet orange (Citrus …
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