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Showing 1 to 20 of 33 for “"reduction rates"”.
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Quantifying the expression of dissimilatory sulfite reductase as a metric for sulfate reduction rates
… (dsr mRNA), a critical enzyme in the sulfate reduction pathway, can serve as an indicator of the rate of sulfate reduction in natural systems. We grew Desulfovibrio vulgaris in fed-batch reactors under electron-donor limiting conditions. To simulate conditions characteristic of oligotrophic …
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An integrated geochemical and microbiological investigation of sulphate reduction in hypersaline pans
… used to derive a holistic picture of sulphate reduction in five hypersaline pans in South Africa. Sulphate reduction rates were determined using a radioactive tracer (35 So/-) technique. This was applied to determination of in situ sulphate reduction rates, the effect of increased salinity on …
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A Study on the Simultaneous Nitrification and Denitrification Process of a Membrane Aerated Bioreactor Augmented by BiOWiSH Aqua
… source and concentration on nitrogen removal rates and biomass growth/behavior were determined through a series of laboratory experiments with Aqua and wastewater. With glucose and solely Aqua cultures, average reduction rates in nitrogen concentrations were 1.2 mg-N/L/hour for all C:N ratios …
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Catalytic Reduction of NO and N2O with Hydrogen in Water by Polymer-Protected Palladium Nanoparticles
… destruction, and N2O is a potent greenhouse gas. Reduction of both gases to harmless dinitrogen by nanoparticulate palladium catalysts is a promising method for treating NO and N2O formed in water. However, creating a better understanding of the method of catalytic activity and corresponding …
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In situ nitrogen (C₂H₂)-fixation in lakes of southern Victorialand, Antarctica
… several antarctic lakes. The observed acetylene reduction occurred in bluegreen algal mats in littoral areas that received maximal sunlight. The benthic bluegreen algal communities in reduced light under 5-6 m of permanent ice showed no detectable nitrogenase activity. The observed nitrogen …
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SEASONAL BIOCHEMISTRY IN THE SEDIMENTS OF THE GREAT BAY ESTUARINE COMPLEX, NEW HAMPSHIRE
… radiometrically as glucose turnover and sulfate reduction rates. Analyses of pore water concentrations of sulfate, chloride, iron and organic carbon, sedimentary concentrations of acid-volatile sulfides, and the abundance of sulfate-reducing bacteria were also made.</p><p>Average annual sulfate …
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Expression of dsr messenger RNA by sulfate reducing bacteria with varying substrate and temperature
… of dsr, a critical gene in the sulfate reduction pathway, in a cell. Because conditions in aquifers can be quite different from those maintained in laboratory experiments, it is unknown whether the results of such studies can be applied to field settings. We test whether dsr expression …
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On the forensic validity of approximated audit logs
… that, while Approx enjoys comparable log reduction rates, it is able to retain 100% of attack-associated log events; in contrast, we make the surprising discovery that prior approaches for log approximation retain as little as 7.3% of forensic evidence under the Attack-Preserving metric. …
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A revised monod-type rate law predicting variable sulfur isotope fractionation factors as a function of microbial sulfate reduction rate
Microbial sulfate reduction is associated with characteristic sulfur isotope partitioning, which can serve as a proxy for the rate of this reactivity in a wide variety of reducing environments. We demonstrate a new model for this functional relationship through the use of a modified Monod-type rate …
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Site-directed mutagenesis of the nitrogenase MoFe protein from Azotobacter vinelandii
… though whole cell and crude extract acetylene reduction activity is lowered. Several substitutions (Cys, Asp, Phe, Asn, Met, Tyr, Leu) are tolerated at the His83 position, these Nif+ mutant strains also have varying acetylene reduction rates and growth rates. All mutants with substitutions at …
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A consecutive reaction model and kinetics of cr2o3 reduction from slag by carbon dissolved in molten iron
… consecutive, two-stage reaction model for the reduction of cr2o3 from slag was developed. The model was applied to the results obtained by studying the effect of various parameters on the rate of reduction of cr2o3 from a CaO-SiO2-Al2o3 slag, by carbon dissolved in molten iron, at temperatures …
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A consecutive reaction model and kinetics of cr2o3 reduction from slag by carbon dissolved in molten iron
… consecutive, two-stage reaction model for the reduction of cr2o3 from slag was developed. The model was applied to the results obtained by studying the effect of various parameters on the rate of reduction of cr2o3 from a CaO-SiO2-Al2o3 slag, by carbon dissolved in molten iron, at temperatures …
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Bioreduction of Hematite Nanoparticles by Shewanella oneidensis MR-1
A dissertation is presented on the bioreduction of hematite (α-Fe2O3) nanoparticles. The study shows that an alternative extracellular electron transfer mechanism other than the classical 'direct-contact' mechanism may be simultaneously employed by Shewanella oneidensis MR-1 during solid-phase …
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Microbial ecology of anaerobic carbon mineralization in Namibian shelf sediments
… carbon (DOC), in particular dissolved carbohydrates, was studied by using both biogeochemical methods and molecular techniques. The bulk sediment composition, pore water chemistry, polysaccharide hydrolysis rates, 35S-sulfate reduction rates, and the abundance of active bacteria involved in the …
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Microbial CR(VI) reduction in indigenous culture of bacteria: characterization and modelling
… high initial Cr(VI) concentrations. The reduction rate using this culture was 3 to 8 times higher than reduction rates reported in bacteria previously isolated and studied in North America and Europe. The culture performed best as a consortium with the different species operating …
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Cycling of Iron and Manganese (Oxyhydr)oxides in the Presence of Organic Matter
… balance between microbial Mn oxidation and photoreduction. In Chapter 3, we further explore Mn oxide photoreduction in the presence of organic matter. We find that photoreduction apparent quantum yields (AQYs) of 𝛿-MnO₂ in humic acid solutions decrease with wavelength regardless of pH, and that …
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A novel semi-passive process for sulphate removal and elemental sulphur recovery centred on a hybrid linear flow channel reactor
… sulphate salinity through biological sulphate reduction catalysed by sulphate reducing bacteria (SRB). These anaerobic bacteria reduce sulphate, in the presence of a suitable electron donor, to sulphide and bicarbonate. However, the hydrogen sulphide product generated is highly toxic, unstable, …
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The role of sulfur in salt marsh metabolism
The rate of sulfate reduction in stands of dwarf Spartina alterniflora in the Great Sippewissett Salt Marsh is approximately 75 moles S04 m2 year-1. This is the highest rate reported for any natural ecosystem. Sulfate reduction is the most important form of respiration in the marsh and results in …
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Mechanistic Study of Fouling and Regeneration of Palladium-Based Bimetallic Catalysts Used for the Removal of Pollutants From Drinking Water
… drinking water. The success of catalytic nitrate reduction however is dependent on the longevity of the catalyst. The primary goals of this work were to assess the effects of non-target water constituents on catalytic nitrate reduction, determine regeneration strategies for fouled-catalysts, and …
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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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