The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Jörg Rethmeier - One of the best experts on this subject based on the ideXlab platform.
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SULFUR ISOTOPE FRACTIONATION DURING Bacterial Reduction AND DISPROPORTIONATION OF THIOSULFATE AND SULFITE
Geochimica et Cosmochimica Acta, 1998Co-Authors: Kirsten Silvia Habicht, Donald E Canfield, Jörg RethmeierAbstract:In Bacterial cultures we measured sulfur isotope fractionation during transformations of thiosulfate (S2O32−) and sulfite (SO32−), pathways which may be of considerable importance in the cycling of sulfur in marine sediments and euxinic waters. We documented isotope fractionations during the Reduction and disproportionation of S2O32− and SO32− by Bacterial enrichments and pure Bacterial cultures from marine and freshwater environments. We also measured the isotope fractionation associated with the anoxygenic phototrophic oxidation of H2S to S2O32− by cyanobacteria. Except for SO32− Reduction, isotope fractionations for these processes have not been previously reported. During the dissimilatory Reduction of SO32−, H2S was depleted in 34S by 6‰, and during the Reduction of S2O32− to H2S, depletions were between 7‰ and 11‰. The largest observed isotope fractionation was associated with the Bacterial disproportionation of SO32− which caused a 34S depletion in H2S of 20–37‰ and a 34S enrichment in sulfate of 7–12‰. During the Bacterial disproportionation of S2O32−, isotope fractionations between the outer sulfane sulfur and H2S and between the inner sulfonate sulfur and SO42− were
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sulfur isotope fractionation during Bacterial Reduction and disproportionation of thiosulfate and sulfite
Geochimica et Cosmochimica Acta, 1998Co-Authors: Kirsten Silvia Habicht, Donald E Canfield, Jörg RethmeierAbstract:In Bacterial cultures we measured sulfur isotope fractionation during transformations of thiosulfate (S2O32−) and sulfite (SO32−), pathways which may be of considerable importance in the cycling of sulfur in marine sediments and euxinic waters. We documented isotope fractionations during the Reduction and disproportionation of S2O32− and SO32− by Bacterial enrichments and pure Bacterial cultures from marine and freshwater environments. We also measured the isotope fractionation associated with the anoxygenic phototrophic oxidation of H2S to S2O32− by cyanobacteria. Except for SO32− Reduction, isotope fractionations for these processes have not been previously reported. During the dissimilatory Reduction of SO32−, H2S was depleted in 34S by 6‰, and during the Reduction of S2O32− to H2S, depletions were between 7‰ and 11‰. The largest observed isotope fractionation was associated with the Bacterial disproportionation of SO32− which caused a 34S depletion in H2S of 20–37‰ and a 34S enrichment in sulfate of 7–12‰. During the Bacterial disproportionation of S2O32−, isotope fractionations between the outer sulfane sulfur and H2S and between the inner sulfonate sulfur and SO42− were <4‰. We observed isotope exchange between the two sulfur atoms of S2O32− leading to a depletion of34S in H2S by up to 12‰ with a comparable enrichment of 34S in SO42−. No isotope fractionation was associated with the anoxygenic phototrophic oxidation of H2S to S2O32−. The depletion of 34S into H2S during the Bacterial Reduction and disproportionation of S2O32− and SO32− may, in addition to sulfate Reduction and the Bacterial disproportionation of elemental sulfur, contribute to the generation of 34S-depleted sedimentary sulfides.
Kirsten Silvia Habicht - One of the best experts on this subject based on the ideXlab platform.
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SULFUR ISOTOPE FRACTIONATION DURING Bacterial Reduction AND DISPROPORTIONATION OF THIOSULFATE AND SULFITE
Geochimica et Cosmochimica Acta, 1998Co-Authors: Kirsten Silvia Habicht, Donald E Canfield, Jörg RethmeierAbstract:In Bacterial cultures we measured sulfur isotope fractionation during transformations of thiosulfate (S2O32−) and sulfite (SO32−), pathways which may be of considerable importance in the cycling of sulfur in marine sediments and euxinic waters. We documented isotope fractionations during the Reduction and disproportionation of S2O32− and SO32− by Bacterial enrichments and pure Bacterial cultures from marine and freshwater environments. We also measured the isotope fractionation associated with the anoxygenic phototrophic oxidation of H2S to S2O32− by cyanobacteria. Except for SO32− Reduction, isotope fractionations for these processes have not been previously reported. During the dissimilatory Reduction of SO32−, H2S was depleted in 34S by 6‰, and during the Reduction of S2O32− to H2S, depletions were between 7‰ and 11‰. The largest observed isotope fractionation was associated with the Bacterial disproportionation of SO32− which caused a 34S depletion in H2S of 20–37‰ and a 34S enrichment in sulfate of 7–12‰. During the Bacterial disproportionation of S2O32−, isotope fractionations between the outer sulfane sulfur and H2S and between the inner sulfonate sulfur and SO42− were
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sulfur isotope fractionation during Bacterial Reduction and disproportionation of thiosulfate and sulfite
Geochimica et Cosmochimica Acta, 1998Co-Authors: Kirsten Silvia Habicht, Donald E Canfield, Jörg RethmeierAbstract:In Bacterial cultures we measured sulfur isotope fractionation during transformations of thiosulfate (S2O32−) and sulfite (SO32−), pathways which may be of considerable importance in the cycling of sulfur in marine sediments and euxinic waters. We documented isotope fractionations during the Reduction and disproportionation of S2O32− and SO32− by Bacterial enrichments and pure Bacterial cultures from marine and freshwater environments. We also measured the isotope fractionation associated with the anoxygenic phototrophic oxidation of H2S to S2O32− by cyanobacteria. Except for SO32− Reduction, isotope fractionations for these processes have not been previously reported. During the dissimilatory Reduction of SO32−, H2S was depleted in 34S by 6‰, and during the Reduction of S2O32− to H2S, depletions were between 7‰ and 11‰. The largest observed isotope fractionation was associated with the Bacterial disproportionation of SO32− which caused a 34S depletion in H2S of 20–37‰ and a 34S enrichment in sulfate of 7–12‰. During the Bacterial disproportionation of S2O32−, isotope fractionations between the outer sulfane sulfur and H2S and between the inner sulfonate sulfur and SO42− were <4‰. We observed isotope exchange between the two sulfur atoms of S2O32− leading to a depletion of34S in H2S by up to 12‰ with a comparable enrichment of 34S in SO42−. No isotope fractionation was associated with the anoxygenic phototrophic oxidation of H2S to S2O32−. The depletion of 34S into H2S during the Bacterial Reduction and disproportionation of S2O32− and SO32− may, in addition to sulfate Reduction and the Bacterial disproportionation of elemental sulfur, contribute to the generation of 34S-depleted sedimentary sulfides.
Donald E Canfield - One of the best experts on this subject based on the ideXlab platform.
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SULFUR ISOTOPE FRACTIONATION DURING Bacterial Reduction AND DISPROPORTIONATION OF THIOSULFATE AND SULFITE
Geochimica et Cosmochimica Acta, 1998Co-Authors: Kirsten Silvia Habicht, Donald E Canfield, Jörg RethmeierAbstract:In Bacterial cultures we measured sulfur isotope fractionation during transformations of thiosulfate (S2O32−) and sulfite (SO32−), pathways which may be of considerable importance in the cycling of sulfur in marine sediments and euxinic waters. We documented isotope fractionations during the Reduction and disproportionation of S2O32− and SO32− by Bacterial enrichments and pure Bacterial cultures from marine and freshwater environments. We also measured the isotope fractionation associated with the anoxygenic phototrophic oxidation of H2S to S2O32− by cyanobacteria. Except for SO32− Reduction, isotope fractionations for these processes have not been previously reported. During the dissimilatory Reduction of SO32−, H2S was depleted in 34S by 6‰, and during the Reduction of S2O32− to H2S, depletions were between 7‰ and 11‰. The largest observed isotope fractionation was associated with the Bacterial disproportionation of SO32− which caused a 34S depletion in H2S of 20–37‰ and a 34S enrichment in sulfate of 7–12‰. During the Bacterial disproportionation of S2O32−, isotope fractionations between the outer sulfane sulfur and H2S and between the inner sulfonate sulfur and SO42− were
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sulfur isotope fractionation during Bacterial Reduction and disproportionation of thiosulfate and sulfite
Geochimica et Cosmochimica Acta, 1998Co-Authors: Kirsten Silvia Habicht, Donald E Canfield, Jörg RethmeierAbstract:In Bacterial cultures we measured sulfur isotope fractionation during transformations of thiosulfate (S2O32−) and sulfite (SO32−), pathways which may be of considerable importance in the cycling of sulfur in marine sediments and euxinic waters. We documented isotope fractionations during the Reduction and disproportionation of S2O32− and SO32− by Bacterial enrichments and pure Bacterial cultures from marine and freshwater environments. We also measured the isotope fractionation associated with the anoxygenic phototrophic oxidation of H2S to S2O32− by cyanobacteria. Except for SO32− Reduction, isotope fractionations for these processes have not been previously reported. During the dissimilatory Reduction of SO32−, H2S was depleted in 34S by 6‰, and during the Reduction of S2O32− to H2S, depletions were between 7‰ and 11‰. The largest observed isotope fractionation was associated with the Bacterial disproportionation of SO32− which caused a 34S depletion in H2S of 20–37‰ and a 34S enrichment in sulfate of 7–12‰. During the Bacterial disproportionation of S2O32−, isotope fractionations between the outer sulfane sulfur and H2S and between the inner sulfonate sulfur and SO42− were <4‰. We observed isotope exchange between the two sulfur atoms of S2O32− leading to a depletion of34S in H2S by up to 12‰ with a comparable enrichment of 34S in SO42−. No isotope fractionation was associated with the anoxygenic phototrophic oxidation of H2S to S2O32−. The depletion of 34S into H2S during the Bacterial Reduction and disproportionation of S2O32− and SO32− may, in addition to sulfate Reduction and the Bacterial disproportionation of elemental sulfur, contribute to the generation of 34S-depleted sedimentary sulfides.
Giorgio Micheli - One of the best experts on this subject based on the ideXlab platform.
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Nd:YAG laser clinical assisted in class II furcation treatment
Lasers in Medical Science, 2008Co-Authors: Ana Karina Pinto Andrade, Ilíria Salomão Feist, Cláudio Mendes Pannuti, Denise Maria Zezell, Giorgio MicheliAbstract:The Nd:YAG laser efficacy associated with conventional treatment for Bacterial Reduction has been investigated throughout literature. The purpose of this study was to evaluate the Bacterial Reduction after Nd:YAG laser irradiation associated with scaling and root planning in class II furcation defects in patients with chronic periodontitis. Thirty-four furcation lesions were selected from 17 subjects. The control group received conventional treatment, and the experimental group received the same treatment followed by Nd:YAG laser irradiation (100 mJ/pulse; 15 Hz; 1.5 W, 60 s, 141.5 J/cm^2). Both treatments resulted in improvements of most clinical parameters. A significant Reduction of colony forming unit (CFU) of total bacteria number was observed in both groups. The highest Reduction was noted in the experimental group immediately after the treatment. The number of dark pigmented bacteria and the percentage of patients with Porphyromonas gingivalis , Prevotella intermedia , and Actinobacillus actinomycetemcomitans reduced immediately after the treatment and returned to values close to the initial ones 6 weeks after the baseline for both groups. The Nd:YAG laser associated with conventional treatment promoted significant Bacterial Reduction in class II furcation immediately after irradiation, although this Reduction was not observed 6 weeks after the baseline.
William T. Frankenberger - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Reduction of Selenium
Salinity and Drainage in San Joaquin Valley California, 2013Co-Authors: Yiqiang Zhang, William T. FrankenbergerAbstract:Microbial metabolisms play important roles in reducing soluble selanate to insoluble elemental selenium. Microorganisms capable of undergoing the reductive process have been isolated and identified. The process may be adapted to microbiologically reduce selenium in the saline drainage water generated in the west side of San Joaquin Valley thus minimizing its eco-toxic potential before releases. For effective selenium Reduction, pH, salinity, redox potential and organic carbon content of the drainage water must be optimized. Amendments such as molasses, zero-valent iron, and redox mediators and microbial inoculates will significantly enhance the removal of selenium from saline drainage water.
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Bacterial Reduction of selenate to elemental selenium utilizing molasses as a carbon source
Bioresource Technology, 2008Co-Authors: Yiqiang Zhang, Benedict C Okeke, William T. FrankenbergerAbstract:Abstract Selecting an inexpensive and effective organic carbon source is the key to reducing the cost in selenium (Se) remediation. Five bacteria were screened based on their ability in using molasses as an organic carbon source to reduce selenate [Se(VI)] in drainage water. Efficiency of Se removal differed in the molasses-added drainage water containing different bacteria, with an order of Enterobacter taylorae > Pantoea sp. SSS2 > Klebsiella sp. WRS2 > Citerobacter freundii > Shigella sp. DW2. By using E. taylorae, 97% of the added Se(VI) (1000 μg/L) was reduced to elemental Se [Se(0)] in an artificial drainage water during an 11-day experiment, and 93% of Se(VI) in a natural agricultural drainage water was reduced to Se(0) and organic Se during a 7-day experiment. E. taylorae also rapidly removed Se(VI) in agar-coated sand columns. During 45 days of the experiment, more than 92% of influent Se was removed from the drainage water with a molasses range of 0.01–0.1%. This study reveals that molasses may be a cost-effective organic carbon source used by Se(VI)-reducing bacteria to remove Se from agricultural drainage water in field.
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Bacterial Reduction of perchlorate and nitrate in water
Journal of Environmental Quality, 1999Co-Authors: David C Herman, William T. FrankenbergerAbstract:A Bacterial isolate, strain perc1ace, was shown to reduce the ground water contaminant perchlorate (ClO{sub 4}{sup {minus}}) to levels < 0.005 mg L{sup {minus}1} when grown on acetate under anaerobic conditions. The ability of perc1ace to simultaneously reduce perchlorate and another ground water pollutant, nitrate (NO{sub 3}{sup {minus}}), was examined in batch studies and in a sand packed column under saturated flow conditions. Nitrate removal was monitored using ion chromatography, and perchlorate removal was monitored using a perchlorate specific electrode or ion chromatography, depending on the study. In batch studies, the Reduction of 0.089, 0.92, 12.0, and 122 mg L{sup {minus}1} perchlorate was examined in the presence and absence of 62 mg L{sup {minus}1} NO{sub 3}{sup {minus}}. Perchlorate was reduced more rapidly in the absence of NO{sub 3}{sup {minus}} than in its presence. However, both perchlorate and NO{sub 3}{sup {minus}} were reduced by more than 10-fold within 48 h. A sand-packed column inoculated with perc1ace simulated a flow-through biotreatment system for water contaminated with a low level of perchlorate and a much higher level of NO{sub 3}{sup {minus}}. Biotreatment could reduce perchlorate to < 0.005 mg L{sup {minus}1} in a 3 h residence time. The addition of NO{sub 3}{sup {minus}}more » initially decreased the efficiency of perchlorate removal, however within 1 d the biotreatment system had adjusted such that there was complete removal of perchlorate and the Reduction of NO{sub 3}{sup {minus}} to < 1 mg L{sup {minus}1}.« less