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Sample records for chemolithoautotrophic thiosulfate oxidation

  1. Whole-Genome Transcriptional Analysis of Chemolithoautotrophic Thiosulfate Oxidation by Thiobacillus denitrificans Under Aerobic vs. Denitrifying Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Beller, H R; Letain, T E; Chakicherla, A; Kane, S R; Legler, T C; Coleman, M A

    2006-04-22

    Thiobacillus denitrificans is one of the few known obligate chemolithoautotrophic bacteria capable of energetically coupling thiosulfate oxidation to denitrification as well as aerobic respiration. As very little is known about the differential expression of genes associated with ke chemolithoautotrophic functions (such as sulfur-compound oxidation and CO2 fixation) under aerobic versus denitrifying conditions, we conducted whole-genome, cDNA microarray studies to explore this topic systematically. The microarrays identified 277 genes (approximately ten percent of the genome) as differentially expressed using Robust Multi-array Average statistical analysis and a 2-fold cutoff. Genes upregulated (ca. 6- to 150-fold) under aerobic conditions included a cluster of genes associated with iron acquisition (e.g., siderophore-related genes), a cluster of cytochrome cbb3 oxidase genes, cbbL and cbbS (encoding the large and small subunits of form I ribulose 1,5-bisphosphate carboxylase/oxygenase, or RubisCO), and multiple molecular chaperone genes. Genes upregulated (ca. 4- to 95-fold) under denitrifying conditions included nar, nir, and nor genes (associated respectively with nitrate reductase, nitrite reductase, and nitric oxide reductase, which catalyze successive steps of denitrification), cbbM (encoding form II RubisCO), and genes involved with sulfur-compound oxidation (including two physically separated but highly similar copies of sulfide:quinone oxidoreductase and of dsrC, associated with dissimilatory sulfite reductase). Among genes associated with denitrification, relative expression levels (i.e., degree of upregulation with nitrate) tended to decrease in the order nar > nir > nor > nos. Reverse transcription, quantitative PCR analysis was used to validate these trends.

  2. Kinetic enrichment of 34S during proteobacterial thiosulfate oxidation and the conserved role of SoxB in S-S bond breaking

    Digital Repository Service at National Institute of Oceanography (India)

    Alam, M.; Pyne, P.; Mazumdar, A.; Peketi, A.; Ghosh, W.

    During chemolithoautotrophic thiosulfate oxidation the phylogenetically-diverged proteobacteria Paracoccus pantotrophus, Tetrathiobacter kashmirensis and Thiomicrospira crunogena rendered steady enrichment of 34S in the end product...

  3. Sulfur formation and recovery in a thiosulfate-oxidizing bioreactor.

    Science.gov (United States)

    González-Sánchez, A; Meulepas, R; Revah, S

    2008-08-01

    This work describes the design and performance of a thiosulfate-oxidizing bioreactor that allowed high elemental sulfur production and recovery efficiency. The reactor system, referred to as a Supernatant-Recycling Settler Bioreactor (SRSB), consisted of a cylindrical upflow reactor and a separate aeration vessel. The reactor was equipped with an internal settler and packing material (structured corrugated PVC sheets) to facilitate both cell retention and the settling of the formed elemental sulfur. The supernatant from the reactor was continuously recirculated through the aerator. An inlet thiosulfate concentration of 100 mmol l(-1) was used. The reactor system was fed with 89 mmol l(-1) d(-1) thiosulfate reaching 98 to 100% thiosulfate conversion with an elemental sulfur yield of 77%. Ninety-three percent of the produced sulfur was harvested from the bottom of the reactor as sulfur sludge. The dry sulfur sludge contained 87% elemental sulfur. The inclusion of an internal settler and packing material in the reactor system resulted in an effective retention of sulfur and biomass inside the bioreactor, preventing the oxidation of thiosulfate and elemental sulfur to sulfate in the aerator and, therefore, improving the efficiency of elemental sulfur formation and recovery.

  4. Separation and distribution of thiosulfate-oxidizing enzyme, tetrathionate reductase, and thiosulfate reductase in extracts of marine heterotroph strain 16B.

    OpenAIRE

    Whited, G M; Tuttle, J.H.

    1983-01-01

    Thiosulfate-oxidizing enzyme (TSO), tetrathionate reductase (TTR), and thiosulfate reductase (TSR) were demonstrated in cell-free extracts of the marine heterotrophic thiosulfate-oxidizing bacterium strain 16B. Extracts prepared from cells cultured aerobically in the absence of thiosulfate or tetrathionate exhibited constitutive TSO and TTR activity which resided in the soluble fraction of ultracentrifuged crude extracts. Constitutive TSO and TTR cochromatographed on DEAE-Sephadex A-50, Celle...

  5. Thiobacter subterraneus gen. nov., sp. nov., an obligately chemolithoautotrophic, thermophilic, sulfur-oxidizing bacterium from a subsurface hot aquifer.

    Science.gov (United States)

    Hirayama, Hisako; Takai, Ken; Inagaki, Fumio; Nealson, Kenneth H; Horikoshi, Koki

    2005-01-01

    A novel, thermophilic, obligately chemolithoautotrophic, sulfur/thiosulfate-oxidizing bacterium was isolated from subsurface geothermal aquifer water (temperature approximately 70 degrees C) in the Hishikari gold mine, Japan. Cells of the isolate, designated strain C55T, were motile, straight rods with a single polar flagellum. Growth was observed at temperatures between 35 and 62 degrees C (optimum 50-55 degrees C; 60 min doubling time) and pH between 5.2 and 7.7 (optimum pH 6.5-7.0). High growth rate of strain C55T was observed on either thiosulfate or elemental sulfur as a sole energy source, with molecular oxygen as the only electron acceptor. None of the organic compounds tested supported or stimulated growth of strain C55T. The G+C content of the genomic DNA was 66.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain C55T was affiliated to the beta-Proteobacteria, but was distantly related to recognized genera. On the basis of its physiological and molecular properties, strain C55T (=JCM12421T=DSM 16629T=ATCC BAA-941T) is proposed as the type strain of Thiobacter subterraneus gen. nov., sp. nov.

  6. Genome-enabled studies of anaerobic, nitrate-dependent iron oxidation in the chemolithoautotrophic bacterium Thiobacillus denitrificans

    Directory of Open Access Journals (Sweden)

    Harry R Beller

    2013-08-01

    Full Text Available Thiobacillus denitrificans is a chemolithoautotrophic bacterium capable of anaerobic, nitrate-dependent U(IV and Fe(II oxidation, both of which can strongly influence the long-term efficacy of in situ reductive immobilization of uranium in contaminated aquifers. We previously identified two c-type cytochromes involved in nitrate-dependent U(IV oxidation in T. denitrificans and hypothesized that c-type cytochromes would also catalyze Fe(II oxidation, as they have been found to play this role in anaerobic phototrophic Fe(II-oxidizing bacteria. Here we report on efforts to identify genes associated with nitrate-dependent Fe(II oxidation, namely (a whole-genome transcriptional studies [using FeCO3, Fe2+, and U(IV oxides as electron donors under denitrifying conditions], (b Fe(II oxidation assays performed with knockout mutants targeting primarily highly expressed or upregulated c-type cytochromes, and (c random transposon-mutagenesis studies with screening for Fe(II oxidation. Assays of mutants for 26 target genes, most of which were c-type cytochromes, indicated that none of the mutants tested were significantly defective in nitrate-dependent Fe(II oxidation. The non-defective mutants included the c1-cytochrome subunit of the cytochrome bc1 complex (complex III, which has relevance to a previously proposed role for this complex in nitrate-dependent Fe(II oxidation and to current concepts of reverse electron transfer. A transposon mutant with a disrupted gene associated with NADH:ubiquinone oxidoreductase (complex I was ~35% defective relative to the wild-type strain; this strain was similarly defective in nitrate reduction with thiosulfate as the electron donor. Overall, our results indicate that nitrate-dependent Fe(II oxidation in T. denitrificans is not catalyzed by the same c-type cytochromes involved in U(IV oxidation, nor have other c-type cytochromes yet been implicated in the process.

  7. Thiomicrospira hydrogeniphila sp. nov., an aerobic, hydrogen- and sulfur-oxidizing chemolithoautotroph isolated from a seawater tank containing a block of beef tallow.

    Science.gov (United States)

    Watsuji, Tomo-O; Hada, Emi; Miyazaki, Masayuki; Ichimura, Masako; Takai, Ken

    2016-09-01

    A moderately psychrophilic, aerobic, hydrogen- and sulfur-oxidizing bacterium, designated strain MAS2T, was isolated from a tank containing coastal seawater from Tokyo Bay and a block of beef tallow added as organic material. Growth occurred under aerobic chemolithoautotrophic conditions in the presence of molecular hydrogen, thiosulfate, tetrathionate, elemental sulfur or sulfide as the sole energy source and bicarbonate as a carbon source. The isolate represented a Gram-staining-negative rod with a single polar flagellum and grew in artificial seawater medium with thiosulfate at 2-40 °C (optimum 30 °C). The isolate grew in media with thiosulfate at Na+ concentrations between 30 and 1380 mM (optimum 270 mM). MAS2T possessed C16 : 0, C16 : 1 and C18 : 1 as the major fatty acids. The G+C content of the genomic DNA was 39.6 mol%. The 16S rRNA gene sequence similarity analysis showed that the isolate represented a member of the genus Thiomicrospira within the class Gammaproteobacteria and was most closely related to Thiomicrospira frisia JB-A2T. On the basis of phenotypic and molecular properties, the isolate represents a novel species of the genus Thiomicrospira, for which the name Thiomicrospira hydrogeniphila sp. nov. is proposed (type strain, MAS2T=JCM 30760T=DSM 100274T).

  8. Thiocyanate hydrolase, the primary enzyme initiating thiocyanate degradation in the novel obligately chemolithoautotrophic halophilic sulfur-oxidizing bacterium Thiohalophilus thiocyanoxidans.

    Science.gov (United States)

    Bezsudnova, Ekaterina Yu; Sorokin, Dimitry Yu; Tikhonova, Tamara V; Popov, Vladimir O

    2007-12-01

    Thiohalophilus thiocyanoxidans is a first halophilic sulfur-oxidizing chemolithoautotrophic bacterium capable of growth with thiocyanate as an electron donor at salinity up to 4 M NaCl. The cells, grown with thiocyanate, but not with thiosulfate, contained an enzyme complex hydrolyzing thiocyanate to sulfide and ammonia under anaerobic conditions with carbonyl sulfide as an intermediate. Despite the fact of utilization of the , high cyanase activity was also detected in thiocyanate-induced cells. Three-stage column chromotography resulted in a highly purified thiocyanate-hydrolyzing protein with an apparent molecular mass of 140 kDa that consists of three subunits with masses 17, 19 and 29 kDa. The enzyme is a Co,Fe-containing protein resembling on its function and subunit composition the enzyme thiocyanate hydrolase from the Betaproteobacterium Thiobacillus thioparus. Cyanase, copurified with thiocyanate hydrolase, is a bisubstrate multisubunit enzyme with an apparent subunit molecular mass of 14 kDa. A possible role of cyanase in thiocyanate degradation by T. thiocyanoxidans is discussed.

  9. The effect of thiosulfate-oxidizing bacteria on the stability of the gold-thiosulfate complex

    Science.gov (United States)

    Lengke, Maggy F.; Southam, Gordon

    2005-08-01

    An Acidithiobacillus thiooxidans spp., isolated from the Driefontein Consolidated Gold Mine, Witwatersrand Basin, Republic of South Africa was able to precipitate gold from Au(S 2O 3) 23- in the presence of up to 0.26 mM gold. In chemical control experiments and with the presence of dead bacteria, gold was not precipitated under similar experimental conditions and duration. During growth, the pH of the culture medium decreased from pH 5.4 to 1.9, while the Eh increased from 0.3 to between 0.5 to 0.6 V within a period of 75 days. In the active (live) bacterial culture systems, acid production enhanced thiosulfate disproportionation, after which the elemental sulfur and any other intermediate sulfur species were oxidized completely to sulfate. The gold, Au(S 2O 3) 23-, was stable in the bacterial systems until sulfur oxidation was complete; then the bacteria precipitated gold from Au(S 2O 3) 23-. The bacterial systems (0.02-0.26 mM gold) precipitated 87 to 100% of the gold under diurnal light exposure, while only 11 to 69% of the gold was precipitated in the dark. The presence of gold (≥0.08 mM) reduced bacterial growth, disrupted cell division causing cell elongation, and was ultimately toxic to this bacterium, killing the cultures. The gold was precipitated inside the bacterial cells as fine-grained colloids ranging between 5 and 10 nm in diameter and in the bulk fluid phase as crystalline micrometer-scale gold. Observations using transmission electron microscopy revealed that the gold was deposited throughout the cell; however, it was concentrated in the cell envelope, especially along the cytoplasmic membrane, suggesting that gold precipitation was likely enhanced via electron transport processes associated with energy generation. Seven months after population growth had stopped, the gold had formed coiled or wire gold, irregular and rounded structures with an approximate size ranging from 0.5 to 5 μm, and crystalline octahedral gold.

  10. Engineering the iron-oxidizing chemolithoautotroph Acidithiobacillus ferrooxidans for biochemical production.

    Science.gov (United States)

    Kernan, Timothy; Majumdar, Sudipta; Li, Xiaozheng; Guan, Jingyang; West, Alan C; Banta, Scott

    2016-01-01

    There is growing interest in developing non-photosynthetic routes for the conversion of CO2 to fuels and chemicals. One underexplored approach is the transfer of energy to the metabolism of genetically modified chemolithoautotrophic bacteria. Acidithiobacillus ferrooxidans is an obligate chemolithoautotroph that derives its metabolic energy from the oxidation of iron or sulfur at low pH. Two heterologous biosynthetic pathways have been expressed in A. ferrooxidans to produce either isobutyric acid or heptadecane from CO2 and the oxidation of Fe(2+). A sevenfold improvement in productivity of isobutyric acid was obtained through improved media formulations in batch cultures. Steady-state efficiencies were lower in continuous cultures, likely due to ferric inhibition. If coupled to solar panels, the photon-to-fuel efficiency of this proof-of-principle process approaches estimates for agriculture-derived biofuels. These efforts lay the foundation for the utilization of this organism in the exploitation of electrical energy for biochemical synthesis.

  11. Anaerobic, Nitrate-Dependent Oxidation of U(IV) Oxide Minerals by the Chemolithoautotrophic Bacterium Thiobacillus denitrificans

    Energy Technology Data Exchange (ETDEWEB)

    Beller, H R

    2004-06-25

    Under anaerobic conditions and at circumneutral pH, cells of the widely-distributed, obligate chemolithoautotrophic bacterium Thiobacillus denitrificans oxidatively dissolved synthetic and biogenic U(IV) oxides (uraninite) in nitrate-dependent fashion: U(IV) oxidation required the presence of nitrate and was strongly correlated to nitrate consumption. This is the first report of anaerobic U(IV) oxidation by an autotrophic bacterium.

  12. Separation and distribution of thiosulfate-oxidizing enzyme, tetrathionate reductase, and thiosulfate reductase in extracts of marine heterotroph strain 16B.

    Science.gov (United States)

    Whited, G M; Tuttle, J H

    1983-11-01

    Thiosulfate-oxidizing enzyme (TSO), tetrathionate reductase (TTR), and thiosulfate reductase (TSR) were demonstrated in cell-free extracts of the marine heterotrophic thiosulfate-oxidizing bacterium strain 16B. Extracts prepared from cells cultured aerobically in the absence of thiosulfate or tetrathionate exhibited constitutive TSO and TTR activity which resided in the soluble fraction of ultracentrifuged crude extracts. Constitutive TSO and TTR cochromatographed on DEAE-Sephadex A-50, Cellex D, Sephadex G-150, and orange A dye-ligand affinity gels. Extracts prepared from cells cultured anaerobically with tetrathionate or aerobically with thiosulfate followed by oxygen deprivation showed an 11- to 30-fold increase in TTR activity, with no increase in TSO activity. The inducible TTR resided in both the ultracentrifuge pellet and supernatant fractions and was readily separated from constitutive TSO and TTR in the latter by DEAE-Sephadex chromatography. Inducible TTR exhibited TSR activity, which was also located in both membrane and soluble extract fractions and which cochromatographed with inducible TTR. The results indicate that constitutive TSO and TTR in marine heterotroph 16B represent reverse activities of the same enzyme whose major physiological function is thiosulfate oxidation. Evidence is also presented which suggests a possible association of inducible TTR and TSR in strain 16B.

  13. Transposon mutagenesis affecting thiosulfate oxidation in Bosea thiooxidans, a new chemolithoheterotrophic bacterium.

    Science.gov (United States)

    Das, S K; Mishra, A K

    1996-06-01

    Transposon insertion mutagenesis was used to isolate mutants of Bosea thiooxidans which are impaired in thiosulfate oxidation. Suicide plasmid pSUP5011 was used to introduce the transposon Tn5 into B. thiooxidans via Escherichia coli S17.1-mediated conjugation. Neomycin-resistant transconjugants occurred at a frequency of 2.2 X 10(-4) per donor. Transconjugants defective in thiosulfate oxidation were categorized into three classes on the basis of growth response, enzyme activities, and cytochrome patterns. Class I mutants were deficient in cytochrome c, and no thiosulfate oxidase activity was detected. Class II mutants retained the activities of key enzymes of thiosulfate metabolism, although at reduced levels. Mutants of this class grown on mixed-substrate agar plates deposited elemental sulfur on the colony surfaces. Class III mutants were unable to utilize thiosulfate, though they had normal levels of cytochrome c. The transposon insertions occurred at different chromosomal positions, as confirmed by Southern blotting of chromosomal DNA of mutants deficient in thiosulfate oxidation, a deficiency which resulted from single insertions of Tn5.

  14. Mechanism of oxidation of inorganic sulfur compounds by thiosulfate-grown Thiobacillus thiooxidans.

    Science.gov (United States)

    Masau, R J; Oh, J K; Suzuki, I

    2001-04-01

    Thiobacillus thiooxidans was grown at pH 5 on thiosulfate as an energy source, and the mechanism of oxidation of inorganic sulfur compounds was studied by the effect of inhibitors, stoichiometries of oxygen consumption and sulfur, sulfite, or tetrathionate accumulation, and cytochrome reduction by substrates. Both intact cells and cell-free extracts were used in the study. The results are consistent with the pathway with sulfur and sulfite as the key intermediates. Thiosulfate was oxidized after cleavage to sulfur and sulfite as intermediates at pH 5, the optimal growth pH on thiosulfate, but after initial condensation to tetrathionate at pH 2.3 where the organism failed to grow. N-Ethylmaleimide (NEM) inhibited sulfur oxidation directly and the oxidation of thiosulfate or tetrathionate indirectly. It did not inhibit the sulfite oxidation by cells, but inhibited any reduction of cell cytochromes by sulfur, thiosulfate, tetrathionate, and sulfite. NEM probably binds sulfhydryl groups, which are possibly essential in supplying electrons to initiate sulfur oxidation. 2-Heptyl-4-hydroxy-quinoline N-oxide (HQNO) inhibited the oxidation of sulfite directly and that of sulfur, thiosulfate, and tetrathionate indirectly. Uncouplers, carbonyl cyanide-m-chlorophenylhydrazone (CCCP) and 2,4-dinitrophenol (DNP), inhibited sulfite oxidation by cells, but not the oxidation by extracts, while HQNO inhibited both. It is proposed that HQNO inhibits the oxidation of sulfite at the cytochrome b site both in cells and extracts, but uncouplers inhibit the oxidation in cells only by collapsing the energized state of cells, delta muH+, required either for electron transfer from cytochrome c to b or for sulfite binding.

  15. Bacterial community succession during the enrichment of chemolithoautotrophic arsenite oxidizing bacteria at high arsenic concentrations

    Institute of Scientific and Technical Information of China (English)

    Nguyen Ai Le; Akiko Sato; Daisuke Inoue; Kazunari Sei; Satoshi Soda; Michihiko Ike

    2012-01-01

    To generate cost-effective technologies for the removal of arsenic from water,we developed an enrichment culture of chemolithoautotrophic arsenite oxidizing bacteria (CAOs) that could effectively oxidize widely ranging concentrations of As(Ⅲ) to As(Ⅴ).In addition,we attempted to elucidate the enrichment process and characterize the microbial composition of the enrichment culture.A CAOs enrichment culture capable of stably oxidizing As(Ⅲ) to As(Ⅴ) was successfully constructed through repeated batch cultivation for more than 700 days,during which time the initial As(Ⅲ) concentrations were increased in a stepwise manner from l to 10-12 mmol/L.As(Ⅲ) oxidation activity of the enrichment culture gradually improved,and 10-12 mmol/L As(Ⅲ) was almost completely oxidized within four days.Terminal restriction fragment length polymorphism analysis showed that the dominant bacteria in the enrichment culture varied drastically during the enrichment process depending on the As(Ⅲ) concentration.Isolation and characterization of bacteria in the enrichment culture revealed that the presence of multiple CAOs with various As(Ⅲ) oxidation abilities enabled the culture to adapt to a wide range of As(Ⅲ) concentrations.The CAOs enrichment culture constructed here may he useful for pretreatment of water from which arsenic is being removed.

  16. Three enzymatic activities catalyze the oxidation of sulfide to thiosulfate in mammalian and invertebrate mitochondria.

    Science.gov (United States)

    Hildebrandt, Tatjana M; Grieshaber, Manfred K

    2008-07-01

    Hydrogen sulfide is a potent toxin of aerobic respiration, but also has physiological functions as a signalling molecule and as a substrate for ATP production. A mitochondrial pathway catalyzing sulfide oxidation to thiosulfate in three consecutive reactions has been identified in rat liver as well as in the body-wall tissue of the lugworm, Arenicola marina. A membrane-bound sulfide : quinone oxidoreductase converts sulfide to persulfides and transfers the electrons to the ubiquinone pool. Subsequently, a putative sulfur dioxygenase in the mitochondrial matrix oxidizes one persulfide molecule to sulfite, consuming molecular oxygen. The final reaction is catalyzed by a sulfur transferase, which adds a second persulfide from the sulfide : quinone oxidoreductase to sulfite, resulting in the final product thiosulfate. This role in sulfide oxidation is an additional physiological function of the mitochondrial sulfur transferase, rhodanese.

  17. Characterization of Comamonas thiooxidans sp. nov., and comparison of thiosulfate oxidation with Comamonas testosteroni and Comamonas composti.

    Science.gov (United States)

    Narayan, Kunwar Digvijay; Pandey, Shachindra K; Das, Subrata K

    2010-10-01

    Comamonas thiooxidans (strain S23(T)) capable of oxidizing thiosulfate under a mixotrophic growth condition was isolated from a sulfur spring. DNA-DNA homology study showed 55% similarity with Comamonas testosteroni KCTC2990(T) and 52% with Comamonas composti LMG24008(T), the nearest phylogenetic relative (16S rRNA sequence similarity thiooxidans sp. nov. is proposed. In addition, thiosulfate oxidation potential of the strain S23(T) was compared with Comamonas testosteroni and Comamonas composti.

  18. Genome sequence of the chemolithoautotrophic nitrite-oxidizing bacterium Nitrobacter winogradskyi Nb-255

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, Loren John [ORNL; Land, Miriam L [ORNL; Larimer, Frank W [ORNL; Arp, D J [Oregon State University; Hickey, W J [University of Wisconsin, Madison

    2006-03-01

    The alphaproteobacterium Nitrobacter winogradskyi (ATCC 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. Sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. There were extensive similarities to genes in two alphaproteobacteria, Bradyrhizobium japonicum USDA110 (1,300 genes) and Rhodopseudomonas palustris CGA009 CG (815 genes). Genes encoding pathways for known modes of chemolithotrophic and chemoorganotrophic growth were identified. Genes encoding multiple enzymes involved in anapleurotic reactions centered on C2 to C4 metabolism, including a glyoxylate bypass, were annotated. The inability of N. winogradskyi to grow on C6 molecules is consistent with the genome sequence, which lacks genes for complete Embden-Meyerhof and Entner-Doudoroff pathways, and active uptake of sugars. Two gene copies of the nitrite oxidoreductase, type I ribulose-1,5-bisphosphate carboxylase/oxygenase, cytochrome c oxidase, and gene homologs encoding an aerobic-type carbon monoxide dehydrogenase were present. Similarity of nitrite oxidoreductases to respiratory nitrate reductases was confirmed. Approximately 10% of the N. winogradskyi genome codes for genes involved in transport and secretion, including the presence of transporters for various organic-nitrogen molecules. The N. winogradskyi genome provides new insight into the phylogenetic identity and physiological capabilities of nitrite-oxidizing bacteria. The genome will serve as a model to study the cellular and molecular processes that control nitrite oxidation and its interaction with other nitrogen-cycling processes.

  19. Complete Genome Sequence of the Marine, Chemolithoautotrophic, Ammonia-Oxidizing Bacterium Nitrosococcus oceani ATCC 19707

    Energy Technology Data Exchange (ETDEWEB)

    Klots, Martin G. [University of Louisville, Louisville; Arp, D J [Oregon State University; Chain, Patrick S [ORNL; El-Sheikh, Amal F. [University of Louisville, Louisville; Hauser, Loren John [ORNL; Hommes, Norman G. [Oregon State University; Larimer, Frank W [ORNL; Malfatti, Stephanie [Lawrence Livermore National Laboratory (LLNL); Norton, Jeanette M. [Utah State University (USU); Poret-Peterson, Amisha T. [University of Louisville, Louisville; Vergez, Lisa [Lawrence Livermore National Laboratory (LLNL); Ward, Bess B. [Princeton University

    2006-01-01

    The gammaproteobacterium Nitrosococcus oceani (ATCC 19707) is a gram-negative obligate chemolithoautotroph capable of extracting energy and reducing power from the oxidation of ammonia to nitrite. Sequencing and annotation of the genome revealed a single circular chromosome (3,481,691 bp; G+C content of 50.4%) and a plasmid (40,420 bp) that contain 3,052 and 41 candidate protein-encoding genes, respectively. The genes encoding proteins necessary for the function of known modes of lithotrophy and autotrophy were identified. Contrary to betaproteobacterial nitrifier genomes, the N. oceani genome contained two complete rrn operons. In contrast, only one copy of the genes needed to synthesize functional ammonia monooxygenase and hydroxylamine oxidoreductase, as well as the proteins that relay the extracted electrons to a terminal electron acceptor, were identified. The N. oceani genome contained genes for 13 complete two-component systems. The genome also contained all the genes needed to reconstruct complete central pathways, the tricarboxylic acid cycle, and the Embden-Meyerhof-Parnass and pentose phosphate pathways. The N. oceani genome contains the genes required to store and utilize energy from glycogen inclusion bodies and sucrose. Polyphosphate and pyrophosphate appear to be integrated in this bacterium's energy metabolism, stress tolerance, and ability to assimilate carbon via gluconeogenesis. One set of genes for type I ribulose-1,5-bisphosphate carboxylase/oxygenase was identified, while genes necessary for methanotrophy and for carboxysome formation were not identified. The N. oceani genome contains two copies each of the genes or operons necessary to assemble functional complexes I and IV as well as ATP synthase (one H+-dependent F0F1 type, one Na+-dependent V type).

  20. The Complete Genome Sequence of the Marine, Chemolithoautotrophic, Ammonia-Oxidizing Bacterium Nitrosococcus oceani ATCC19707

    Energy Technology Data Exchange (ETDEWEB)

    Klotz, M G; Arp, D J; Chain, P S; El-Sheikh, A F; Hauser, L J; Hommes, N G; Larimer, F W; Malfatti, S A; Norton, J M; Poret-Peterson, A T; Vergez, L M; Ward, B B

    2006-08-03

    The Gammaproteobacterium, Nitrosococcus oceani (ATCC 19707), is a Gram-negative obligate chemolithoautotroph capable of extracting energy and reducing power from the oxidation of ammonia to nitrite. Sequencing and annotation of the genome revealed a single circular chromosome (3,481,691 bp; 50.4% G+C) and a plasmid (40,420 bp) that contain 3052 and 41 candidate protein-encoding genes, respectively. The genes encoding proteins necessary for the function of known modes of lithotrophy and autotrophy were identified. In contrast to betaproteobacterial nitrifier genomes, the N. oceani genome contained two complete rrn operons. In contrast, only one copy of the genes needed to synthesize functional ammonia monooxygenase and hydroxylamine oxidoreductase, as well as the proteins that relay the extracted electrons to a terminal electron acceptor were identified. The N. oceani genome contained genes for 13 complete two-component systems. The genome also contained all the genes needed to reconstruct complete central pathways, the tricarboxylic acid cycle and the Embden-Meyerhof-Parnass and pentose phosphate pathways. The N. oceani genome contains the genes required to store and utilize energy from glycogen inclusion bodies and sucrose. Polyphosphate and pyrophosphate appear to be integrated in this bacterium's energy metabolism, stress tolerance and the ability to assimilate carbon via gluconeogenesis. One set of genes for type I RuBisCO was identified, while genes necessary for methanotrophy and for carboxysome formation were not identified. The N. oceani genome contains two copies each of the genes or operons necessary to assemble functional complexes I and IV as well as ATP synthase (one H{sup +}-dependent F{sub 0}F{sub 1}-type, one Na{sup +}-dependent V-type).

  1. Characterization of a novel thiosulfate dehydrogenase from a marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH.

    Science.gov (United States)

    Sharmin, Sultana; Yoshino, Eriko; Kanao, Tadayoshi; Kamimura, Kazuo

    2016-01-01

    A marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH, was isolated to develop a bioleaching process for NaCl-containing sulfide minerals. Because the sulfur moiety of sulfide minerals is metabolized to sulfate via thiosulfate as an intermediate, we purified and characterized the thiosulfate dehydrogenase (TSD) from strain SH. The enzyme had an apparent molecular mass of 44 kDa and was purified 71-fold from the solubilized membrane fraction. Tetrathionate was the product of the TSD-oxidized thiosulfate and ferricyanide or ubiquinone was the electron acceptor. Maximum enzyme activity was observed at pH 4.0, 40 °C, and 200 mM NaCl. To our knowledge, this is the first report of NaCl-stimulated TSD activity. TSD was structurally different from the previously reported thiosulfate-oxidizing enzymes. In addition, TSD activity was strongly inhibited by 2-heptyl-4-hydroxy-quinoline N-oxide, suggesting that the TSD is a novel thiosulfate:quinone reductase.

  2. Complete Genome Sequence of the Unclassified Iron-Oxidizing, Chemolithoautotrophic Burkholderiales Bacterium GJ-E10, Isolated from an Acidic River.

    Science.gov (United States)

    Fukushima, Jun; Tojo, Fuyumi; Asano, Ryoki; Kobayashi, Yayoi; Shimura, Yoichiro; Okano, Kunihiro; Miyata, Naoyuki

    2015-02-05

    Burkholderiales bacterium GJ-E10, isolated from the Tamagawa River in Akita Prefecture, Japan, is an unclassified, iron-oxidizing chemolithoautotrophic bacterium. Its single circular genome, consisting of 3,276,549 bp, was sequenced by using three types of next-generation sequencers and the sequences were then confirmed by PCR-based Sanger sequencing.

  3. From Chemolithoautotrophs to Electrolithoautotrophs: CO2 Fixation by Fe(II-Oxidizing Bacteria Coupled with Direct Uptake of Electrons from Solid Electron Sources

    Directory of Open Access Journals (Sweden)

    Takumi eIshii

    2015-09-01

    Full Text Available At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe2+ ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex and a cytochrome bc1 complex (bc1 complex in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD+ through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats.

  4. Influence of salts and pH on growth and activity of a novel facultatively alkaliphilic, extremely salt-tolerant, obligately chemolithoautotrophic sufur-oxidizing Gammaproteobacterium Thioalkalibacter halophilus gen. nov., sp. nov. from South-Western Siberian soda lakes

    NARCIS (Netherlands)

    Banciu, H.L.; Sorokin, D.Y.; Tourova, T.P.; Galinski, E.A.; Muntyan, M.S.; Kuenen, J.G.; Muyzer, G.

    2008-01-01

    A chemolithoautotrophic sulfur-oxidizing bacterium (SOB) strain ALCO 1 capable of growing at both near-neutral and extremely alkaline pH was isolated from hypersaline soda lakes in S-W Siberia (Altai, Russia). Strain ALCO 1 represents a novel separate branch within the halothiobacilli in the Gammapr

  5. Thermocrinis jamiesonii sp. nov., a thiosulfate-oxidizing, autotropic thermophile isolated from a geothermal spring

    Energy Technology Data Exchange (ETDEWEB)

    Ong, John C.; Dodsworth, Jeremy A.; Hedlund, Brian P.; Dohnalkova, Alice C.; Williams, Amanda J.

    2015-12-01

    An obligately thermophilic, chemolithotrophic, microaerophilic bacterium, designated strain GBS1T, was isolated from the water column of Great Boiling Spring, Nevada, USA. Thiosulfate was required for growth. Although capable of autotrophy, growth of GBS1T was enhanced in the presence of acetate, peptone, or Casamino acids. Growth occurred at 70-85 °C with an optimum at 80 °C, at pH 6.5-7.75 with an optimum at pH 7.25, at 0.5-8% oxygen with an optimum at 1-2%, and at ≤200 mM sodium chloride. The doubling time under optimal growth conditions was 1.3 hrs, with a final cell density of 6.2±0.5 x 107 cells/mL. Non-motile, rod-shaped cells 1.4-2.4 x 0.4-0.6 µm occurred singly or in pairs. Major cellular fatty acids (>5% of total) were C20:1ω9c (44.8%), C18:0 (26.0%), C16:0 (9.9%) and C20:0 (5.4%). Phylogenetic analysis of the GBS1T 16S rRNA gene sequence indicated an affiliation with Thermocrinis ruber and other Thermocrinis spp., but comparisons of 16S rRNA gene identity (≤97.10%) and in silico estimated DNA-DNA hybridization values (≤18.4%) with Thermocrinis spp. indicate that his strain is distinct from described species. Based on phenotypic, genotypic, and phylogenetic characteristics, the name Thermocrinis jamiesonii sp. nov. is proposed, with GBS1T (= JCM 19133T = DSM 27162T) as the type strain.

  6. Dyella thiooxydans sp. nov., a facultatively chemolithotrophic, thiosulfate-oxidizing bacterium isolated from rhizosphere soil of sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Anandham, Rangasamy; Kwon, Soon-Wo; Indira Gandhi, Pandiyan; Kim, Soo-Jin; Weon, Hang-Yeon; Kim, Yi-Seul; Sa, Tong-Min; Kim, Yong-Ki; Jee, Hyeong-Jin

    2011-02-01

    A Gram-negative, aerobic, motile, rod-shaped, thiosulfate-oxidizing bacterium, designated ATSB10(T), was isolated from rhizosphere soil of sunflower (Helianthus annuus L.). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ATSB10(T) was closely related to members of the genera Dyella (96.4-98.1 % 16S rRNA gene sequence similarity) and Luteibacter (96.4-97.0 %) and Fulvimonas soli LMG 19981(T) (96.7 %) and Frateuria aurantia IFO 3245(T) (97.8 %). The predominant fatty acids were iso-C(16 : 0), iso-C(17 : 1)ω9c and iso-C(15 : 0). The major quinone was Q-8. The G+C content of the genomic DNA was 66.0 mol%. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidyldimethylethanolamine, an unknown phospholipid, unknown aminophospholipids and an unknown aminolipid. On the basis of phenotypic properties, phylogenetic distinctiveness and DNA-DNA relatedness, strain ATSB10(T) represents a novel species in the genus Dyella, for which the name Dyella thiooxydans sp. nov. is proposed. The type strain is ATSB10(T) (=KACC 12756(T) =LMG 24673(T)).

  7. Enhanced fatty acid production in engineered chemolithoautotrophic bacteria using reduced sulfur compounds as energy sources

    DEFF Research Database (Denmark)

    Beller, Harry R.; Zhou, Peng; Jewell, Talia N.M.;

    2016-01-01

    Chemolithoautotrophic bacteria that oxidize reduced sulfur compounds, such as H2S, while fixing CO2 are an untapped source of renewable bioproducts from sulfide-laden waste, such as municipal wastewater. In this study, we report engineering of the chemolithoautotrophic bacterium Thiobacillus...

  8. Isolation and properties of obligately chemolithoautotrophic and extremely alkali-tolerant ammonia-oxidizing bacteria from Mongolian soda lakes.

    Science.gov (United States)

    Sorokin, D; Tourova, T; Schmid, M C; Wagner, M; Koops, H P; Kuenen, J G; Jetten, M

    2001-09-01

    Five mixed samples prepared from the surface sediments of 20 north-east Mongolian soda lakes with total salt contents from 5 to 360 g/l and pH values from 9.7 to 10.5 were used to enrich for alkaliphilic ammonia-oxidizing bacteria. Successful enrichments at pH 10 were achieved on carbonate mineral medium containing 0.6 M total Na(+) and < or =4 mM NH(4)Cl. Five isolates (ANs1-ANs5) of ammonia-oxidizing bacteria capable of growth at pH 10 were obtained from the colonies developed on bilayered gradient plates. The cells were motile and coccoid, with well-developed intracytoplasmic membranes (ICPM) and carboxysomes. At pH 10.0, ammonia was toxic for growth at concentrations higher than 5 mM NH(4)Cl. The bacteria were able to grow within the salinity range of 0.1-1.0 M of total Na+ (optimum 0.3 M). In media containing 0.3-0.6 M total Na(+), optimal growth in batch cultures occurred in the presence of a bicarbonate/carbonate buffer system within the pH range 8.5-9.5, with the highest pH limit at pH 10.5. At pH lower than 8.0, growth was slower, most probably due to decreasing free ammonia. The pH profile of the respiratory activity was broader, with limits at 6.5-7.0 and 11.0 and an optimum at 9.5-10.0. In pH-controlled, NH(3)-limited continuous culture, isolate ANs5 grew up to pH 11.3, which is the highest pH limit known for ammonia-oxidizing bacteria so far. This showed the existence of extremely alkali-tolerant ammonia-oxidizing bacteria in the soda lakes. Comparative 16S rDNA sequence analysis of the five isolates demonstrated that they possess identical 16S rDNA genes and that they are closely related to Nitrosomonas halophila (sequence similarity 99.3%), a member of the beta-subclass of the Proteobacteria. This affiliation was confirmed by comparative sequence analysis of the amoA gene, encoding the active-site subunit of the ammonia-monoxygenase, of one of the isolates. DNA-DNA hybridization data further supported that the soda lake isolates are very similar to

  9. The Two-component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation in Acidithiobacillus caldus

    Directory of Open Access Journals (Sweden)

    Zhaobao Wang

    2016-11-01

    Full Text Available Acidithiobacillus caldus (A. caldus is a common bioleaching bacterium that possesses a sophisticated and highly efficient inorganic sulfur compound metabolism network. Thiosulfate, a central intermediate in the sulfur metabolism network of A. caldus and other sulfur-oxidizing microorganisms, can be metabolized via the tetrathionate intermediate (S4I pathway catalyzed by thiosulfate:quinol oxidoreductase (Tqo or DoxDA and tetrathionate hydrolase (TetH. In A. caldus, there is an additional two-component system called RsrS-RsrR. Since rsrS and rsrR are arranged as an operon with doxDA and tetH in the genome, we suggest that the regulation of the S4I pathway may occur via the RsrS-RsrR system. To examine the regulatory role of the two-component system RsrS-RsrR on the S4I pathway, ΔrsrR and ΔrsrS strains were constructed in A. caldus using a newly developed markerless gene knockout method. Transcriptional analysis of the tetH cluster in the wild type and mutant strains revealed positive regulation of the S4I pathway by the RsrS-RsrR system. A 19bp inverted repeat sequence (IRS, AACACCTGTTACACCTGTT located upstream of the tetH promoter was identified as the binding site for RsrR by using electrophoretic mobility shift assays (EMSAs in vitro and promoter-probe vectors in vivo. In addition, ΔrsrR and ΔrsrS strains cultivated in K2S4O6- medium exhibited significant growth differences when compared with the wild type. Transcriptional analysis indicated that the absence of rsrS or rsrR had different effects on the expression of genes involved in sulfur metabolism and signaling systems. Finally, a model of tetrathionate sensing by RsrS, signal transduction via RsrR, and transcriptional activation of tetH-doxDA was proposed to provide insights towards the understanding of sulfur metabolism in A. caldus. This study also provided a powerful genetic tool for studies in A. caldus.

  10. Low expression of thiosulfate sulfurtransferase (rhodanese) predicts mortality in hemodialysis patients

    DEFF Research Database (Denmark)

    Krueger, Katharina; Koch, Kathrin; Jühling, Anja;

    2010-01-01

    To test the hypothesis that impaired expression of the thiosulfate sulfurtransferase rhodanese is associated with oxidative stress and may predict mortality in hemodialysis patients.......To test the hypothesis that impaired expression of the thiosulfate sulfurtransferase rhodanese is associated with oxidative stress and may predict mortality in hemodialysis patients....

  11. Purification and properties of thiosulfate dehydrogenase from Acidithiobacillus thiooxidans JCM7814.

    Science.gov (United States)

    Nakamura, K; Nakamura, M; Yoshikawa, H; Amano, Y

    2001-01-01

    A key enzyme of the thiosulfate oxidation pathway in Acidithiobacillus thiooxidans JCM7814 was investigated. As a result of assaying the enzymatic activities of thiosulfate dehydrogenase, rhodanese, and thiosulfate reductase at 5.5 of intracellular pH, the activity of thiosulfate dehydrogenase was measured as the key enzyme. The thiosulfate dehydrogenase of A. thiooxidans JCM7814 was purified using three chromatographies. The purified sample was electrophoretically homogeneous. The molecular mass of the enzyme was 27.9 kDa and it was a monomer. This enzyme had cytochrome c. The optimum pH and temperature of this enzyme were 3.5 and 35 degrees C. The enzyme was stable in the pH range from 5 to 7, and it was stable up to 45 degrees C. The isoelectric point of the enzyme was 8.9. This enzyme reacted with thiosulfate as a substrate. The Km was 0.81 mM.

  12. Permanent draft genome of Thermithiobaclillus tepidarius DSM 3134(T), a moderately thermophilic, obligately chemolithoautotrophic member of the Acidithiobacillia.

    Science.gov (United States)

    Boden, Rich; Hutt, Lee P; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha; Mikhailova, Natalia; Stamatis, Dimitrios; Reddy, Tatiparthi; Ngan, Chew Yee; Daum, Chris; Shapiro, Nicole; Markowitz, Victor; Ivanova, Natalia; Woyke, Tanja; Kyrpides, Nikos

    2016-01-01

    Thermithiobacillus tepidarius DSM 3134(T) was originally isolated (1983) from the waters of a sulfidic spring entering the Roman Baths (Temple of Sulis-Minerva) at Bath, United Kingdom and is an obligate chemolithoautotroph growing at the expense of reduced sulfur species. This strain has a genome size of 2,958,498 bp. Here we report the genome sequence, annotation and characteristics. The genome comprises 2,902 protein coding and 66 RNA coding genes. Genes responsible for the transaldolase variant of the Calvin-Benson-Bassham cycle were identified along with a biosynthetic horseshoe in lieu of Krebs' cycle sensu stricto. Terminal oxidases were identified, viz. cytochrome c oxidase (cbb3, EC 1.9.3.1) and ubiquinol oxidase (bd, EC 1.10.3.10). Metalloresistance genes involved in pathways of arsenic and cadmium resistance were found. Evidence of horizontal gene transfer accounting for 5.9 % of the protein-coding genes was found, including transfer from Thiobacillus spp. and Methylococcus capsulatus Bath, isolated from the same spring. A sox gene cluster was found, similar in structure to those from other Acidithiobacillia - by comparison with Thiobacillus thioparus and Paracoccus denitrificans, an additional gene between soxA and soxB was found, annotated as a DUF302-family protein of unknown function. As the Kelly-Friedrich pathway of thiosulfate oxidation (encoded by sox) is not used in Thermithiobacillus spp., the role of the operon (if any) in this species remains unknown. We speculate that DUF302 and sox genes may have a role in periplasmic trithionate oxidation.

  13. In Situ Gene Expression Responsible for Sulfide Oxidation and CO2 Fixation of an Uncultured Large Sausage-Shaped Aquificae Bacterium in a Sulfidic Hot Spring.

    Science.gov (United States)

    Tamazawa, Satoshi; Yamamoto, Kyosuke; Takasaki, Kazuto; Mitani, Yasuo; Hanada, Satoshi; Kamagata, Yoichi; Tamaki, Hideyuki

    2016-06-25

    We investigated the in situ gene expression profile of sulfur-turf microbial mats dominated by an uncultured large sausage-shaped Aquificae bacterium, a key metabolic player in sulfur-turfs in sulfidic hot springs. A reverse transcription-PCR analysis revealed that the genes responsible for sulfide, sulfite, and thiosulfate oxidation and carbon fixation via the reductive TCA cycle were continuously expressed in sulfur-turf mats taken at different sampling points, seasons, and years. These results suggest that the uncultured large sausage-shaped bacterium has the ability to grow chemolithoautotrophically and plays key roles as a primary producer in the sulfidic hot spring ecosystem in situ.

  14. Nitrolancea hollandica gen. nov., sp. nov., a chemolithoautotrophic nitrite-oxidizing bacterium isolated from a bioreactor belonging to the phylum Chloroflexi

    NARCIS (Netherlands)

    Sorokin, D.Y.; Vejmelkova, D.; Lücker, S.; Streshinskaya, G.M.; Rijpstra, W.I.C.; Sinninghe Damste, J.S.; Kleerbezem, R.; van Loosdrecht, M.; Muyzer, G.; Daims, H.

    2014-01-01

    A novel nitrite-oxidizing bacterium (NOB), strain LbT, was isolated from a nitrifying bioreactor with a high loading of ammonium bicarbonate in a mineral medium with nitrite as the energy source. The cells were oval (lancet-shaped) rods with pointed edges, non-motile, Gram-positive (by staining and

  15. Sulfuriferula thiophila sp. nov., a chemolithoautotrophic sulfur-oxidizing bacterium, and correction of the name Sulfuriferula plumbophilusWatanabe, Kojima and Fukui 2015 to Sulfuriferula plumbiphila corrig.

    Science.gov (United States)

    Watanabe, Tomohiro; Kojima, Hisaya; Fukui, Manabu

    2016-05-01

    A novel sulfur-oxidizing bacterium designated strain mst6T was isolated from spring water of Masutomi hot spring in Japan. The cells were rod-shaped (1.2-4.0 × 0.5-0.7 μm) and Gram-stain-negative. The G+C content of genomic DNA was around 52.6 mol%. The isolate possessed summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C12 : 0 as major cellular fatty acids. Strain mst6T grew by inorganic carbon fixation and oxidation of inorganic sulfur compounds with oxygen as an electron acceptor. The isolate grew over a temperature range of 5-34 °C, a NaCl concentration range of 0-110 mM and a pH range of 4.6-8.1. Optimum growth occurred at 32 °C, in the absence of NaCl and at pH 5.9-6.2. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain mst6T belongs to the family Sulfuricellaceae in the class Betaproteobacteria. The closest cultured relative was Sulfuriferula multivorans TTNT with a 16S rRNA gene sequence similarity of 97.0 %. On the basis of the data obtained in this study, strain mst6T represents a novel species of the genus Sulfuriferula, for which the name Sulfuriferula thiophila sp. nov. is proposed. The type strain is mst6T ( = NBRC 111150T = DSM 101871T). In addition, we propose correcting the name Sulfuriferula plumbophilus Watanabe, Kojima and Fukui 2015 to Sulfuriferula plumbiphila corrig. based on Rule 12c, Rule 61 and Appendix 9 of the International Code of Nomenclature of Prokaryotes.

  16. Pretreatment and thiosulfate leaching of refractory gold-bearing arsenosulfide concentrates

    Institute of Scientific and Technical Information of China (English)

    Yuqun Meng

    2005-01-01

    A hydrometallurgical process for refractory gold-bearing arsenosulfide concentrates at ambient temperature and pressure was presented, including fine grinding with intensified alkali-leaching (FGIAL), enhanced agitation alkali-leaching (EAAL), thiosulfate leaching and displacement. Experimental results on a refractory gold concentrate showed that the total consumption of NaOH in alkaline leaching is only 41% of those theoretically calculated under the conditions of full oxidization for the same amount of arsenides and sulfides transformed into arsenates and sulfates, and 72.3% of gold is synchro-dissoluted by thiosulfate self-generated during alkaline leaching. After alkaline leaching, thiosulfate leaching was carried out for 24 h. The dissolution of gold is increased to 91.9% from 4.6% by cyanide without the pretreatment. The displacement of gold by zinc powder in the solution gets to 99.2%. Due to an amount of thiosulfate self-generated during alkaline leaching, the reagent addition in thiosulfate leaching afterwards is lower than the normal.

  17. Pathways and Microbiology of Thiosulfate Transformations and Sulfate Reduction in a Marine Sediment (Kattegat, Denmark)

    DEFF Research Database (Denmark)

    JØRGENSEN, BB; BAK, F.

    1991-01-01

    Reductive and oxidative pathways of the sulfur cycle were studied in a marine sediment by parallel radiotracer experiments with (SO4(2-))-S-35, (H2S)-S-35, and (S2O3(2-))-S-35 injected into undisturbed sediment cores. The distributions of viable populations of sulfate- and thiosulfate-reducing ba...

  18. The genome of deep-sea vent chemolithoautotroph Thiomicrospira crunogena XCL-2.

    Directory of Open Access Journals (Sweden)

    Kathleen M Scott

    2006-11-01

    Full Text Available Presented here is the complete genome sequence of Thiomicrospira crunogena XCL-2, representative of ubiquitous chemolithoautotrophic sulfur-oxidizing bacteria isolated from deep-sea hydrothermal vents. This gammaproteobacterium has a single chromosome (2,427,734 base pairs, and its genome illustrates many of the adaptations that have enabled it to thrive at vents globally. It has 14 methyl-accepting chemotaxis protein genes, including four that may assist in positioning it in the redoxcline. A relative abundance of coding sequences (CDSs encoding regulatory proteins likely control the expression of genes encoding carboxysomes, multiple dissolved inorganic nitrogen and phosphate transporters, as well as a phosphonate operon, which provide this species with a variety of options for acquiring these substrates from the environment. Thiom. crunogena XCL-2 is unusual among obligate sulfur-oxidizing bacteria in relying on the Sox system for the oxidation of reduced sulfur compounds. The genome has characteristics consistent with an obligately chemolithoautotrophic lifestyle, including few transporters predicted to have organic allocrits, and Calvin-Benson-Bassham cycle CDSs scattered throughout the genome.

  19. The Genome of Deep-Sea Vent Chemolithoautotroph Thiomicrospira crunogena XCL-2

    Energy Technology Data Exchange (ETDEWEB)

    Scott, K M; Sievert, S M; Abril, F N; Ball, L A; Barrett, C J; Blake, R A; Boller, A J; Chain, P G; Clark, J A; Davis, C R; Detter, C; Do, K F; Dobrinski, K P; Faza, B I; Fitzpatrick, K A; Freyermuth, S K; Harmer, T L; Hauser, L J; Hugler, M; Kerfeld, C A; Klotz, M G; Kong, W W; Land, M; Lapidus, A; Larimer, F W; Longo, D L; Lucas, S; Malfatti, S A; Massey, S E; Martin, D D; McCuddin, Z; Meyer, F; Moore, J L; Ocampo Jr., L H; Paul, J H; Paulsen, I T; Reep, D K; Ren, Q; Ross, R L; Sato, P Y; Thomas, P; Tinkham, L E; Zerugh, G T

    2007-01-10

    Presented here is the complete genome sequence of Thiomicrospira crunogena XCL-2, representative of ubiquitous chemolithoautotrophic sulfur-oxidizing bacteria isolated from deep-sea hydrothermal vents. This gammaproteobacterium has a single chromosome (2,427,734 bp), and its genome illustrates many of the adaptations that have enabled it to thrive at vents globally. It has 14 methyl-accepting chemotaxis protein genes, including four that may assist in positioning it in the redoxcline. A relative abundance of CDSs encoding regulatory proteins likely control the expression of genes encoding carboxysomes, multiple dissolved inorganic nitrogen and phosphate transporters, as well as a phosphonate operon, which provide this species with a variety of options for acquiring these substrates from the environment. T. crunogena XCL-2 is unusual among obligate sulfur oxidizing bacteria in relying on the Sox system for the oxidation of reduced sulfur compounds. A 38 kb prophage is present, and a high level of prophage induction was observed, which may play a role in keeping competing populations of close relatives in check. The genome has characteristics consistent with an obligately chemolithoautotrophic lifestyle, including few transporters predicted to have organic allocrits, and Calvin-Benson-Bassham cycle CDSs scattered throughout the genome.

  20. Sulfate Reduction and Thiosulfate Transformations in a Cyanobacterial Mat during a Diel Oxygen Cycle

    DEFF Research Database (Denmark)

    JØRGENSEN, BB

    1994-01-01

    Bacterial sulfate reduction and transformations of thiosulfate were studied with radiotracers in a Microcoleus chthono-plastes-dominated microbial mat growing in a hypersaline pond at the Red Sea. The study showed how a diel cycle of oxygen evolution affected respiration by sulfate-reducing bacte......Bacterial sulfate reduction and transformations of thiosulfate were studied with radiotracers in a Microcoleus chthono-plastes-dominated microbial mat growing in a hypersaline pond at the Red Sea. The study showed how a diel cycle of oxygen evolution affected respiration by sulfate......-reducing bacteria and the metabolism of thiosulfate through oxidative and reductive pathways. Sulfate reduction occurred in both oxic and anoxic layers of the mat and varied diurnally, apparently according to temperature rather than to oxygen. Time course experiments showed that the radiotracer method...... of the mat, there was a shift from predominant oxidation in the oxic zone to predominant reduction below. Concurrent disproportionation of thiosulfate to sulfate and sulfide occurred in all zones and was an important pathway of the sulfur cycle in the mat....

  1. Stoichiometric modeling of oxidation of reduced inorganic sulfur compounds (Riscs) in Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Bobadilla Fazzini, Roberto A; Cortés, Maria Paz; Padilla, Leandro; Maturana, Daniel; Budinich, Marko; Maass, Alejandro; Parada, Pilar

    2013-08-01

    The prokaryotic oxidation of reduced inorganic sulfur compounds (RISCs) is a topic of utmost importance from a biogeochemical and industrial perspective. Despite sulfur oxidizing bacterial activity is largely known, no quantitative approaches to biological RISCs oxidation have been made, gathering all the complex abiotic and enzymatic stoichiometry involved. Even though in the case of neutrophilic bacteria such as Paracoccus and Beggiatoa species the RISCs oxidation systems are well described, there is a lack of knowledge for acidophilic microorganisms. Here, we present the first experimentally validated stoichiometric model able to assess RISCs oxidation quantitatively in Acidithiobacillus thiooxidans (strain DSM 17318), the archetype of the sulfur oxidizing acidophilic chemolithoautotrophs. This model was built based on literature and genomic analysis, considering a widespread mix of formerly proposed RISCs oxidation models combined and evaluated experimentally. Thiosulfate partial oxidation by the Sox system (SoxABXYZ) was placed as central step of sulfur oxidation model, along with abiotic reactions. This model was coupled with a detailed stoichiometry of biomass production, providing accurate bacterial growth predictions. In silico deletion/inactivation highlights the role of sulfur dioxygenase as the main catalyzer and a moderate function of tetrathionate hydrolase in elemental sulfur catabolism, demonstrating that this model constitutes an advanced instrument for the optimization of At. thiooxidans biomass production with potential use in biohydrometallurgical and environmental applications.

  2. Urinary thiosulfate determined by suppressed ion chromatography with conductimetric detection.

    Science.gov (United States)

    Cole, D E; Evrovski, J; Pirone, R

    1995-10-01

    Thiosulfate is a naturally occurring product of sulfur metabolism. Assays of urinary thiosulfate have been based on the reaction with cyanide to form thiocyanate. However, matrix interferences and background variation in endogenous thiocyanate excretion place serious constraints on this method for determination of physiological amounts of thiosulfate in urine. We describe a column-switching ion chromatographic separation for urinary thiosulfate that allows for sensitive and accurate detection by ion conductimetry. In 20 adult volunteers, we found a lower urinary thiosulfate (8.50 +/- 7.39 mumol/24 h, mean +/- S.D.) than others have described, although the upward skew of the results (median, 6.90; range, 0.84-32 mumol/24 h) was similar. However, we have not observed any of the interferences and the sensitivity of our technique (< 0.2 mumol/24 h) allows for detection of thiosulfate in all control samples. This sort of methodological improvement will be essential for any study of physiological thiosulfate metabolism.

  3. Evidence of biogenic corrosion of titanium after exposure to a continuous culture of thiobacillus ferrooxidans grown in thiosulfate medium

    Energy Technology Data Exchange (ETDEWEB)

    Horn, J M; Martin, S I; Masterson, B

    2000-12-07

    Experiments were undertaken to evaluate extreme conditions under which candidate materials intended for use in a proposed nuclear waste repository might be susceptible to corrosion by endogenous microorganisms. Thiobucillus ferrooxidans, a sulfur-oxidizing bacterium, was grown in continuous culture using thiosulfate as an energy source; thiosulfate is oxidized to sulfate as a metabolic endproduct by this organism. Culture conditions were optimized to produce a high-density, metabolically active culture throughout a period of long term incubation in the presence of Alloy 22 (a high nickel-based alloy) and Titanium grade 7 (Tigr7) material coupons. After seven months incubation under these conditions, material coupons were withdrawn and analyzed by high resolution microscopy and energy dispersive x-ray analyses. Alloy 22 coupons showed no detectable signs of corrosion. Tigr7, however, demonstrated distinct roughening of the coupon surface, and [presumably solubilized and precipitated] titanium was detected on Alloy 22 coupons incubated in the same T. ferrooxiduns culture vessel. Control coupons of these materials incubated in sterile thiosulfate medium did not demonstrate any signs of corrosion, thus showing that observed corrosive effects were due to the T. ferrooxidans metabolic activities. T. ferrooxidans intermediates of thiosulfate oxidation or sulfate may have caused the corrosive effects observed on Tigr7.

  4. Thiosulfate as a metabolic product: the bacterial fermentation of taurine.

    Science.gov (United States)

    Denger, K; Laue, H; Cook, A M

    1997-10-01

    Thiosulfate (S2O32-) is a natural product that is widely utilized in natural ecosystems as an electron sink or as an electron donor. However, the major biological source(s) of this thiosulfate is unknown. We present the first report that taurine (2-aminoethanesulfonate), the major mammalian solute, is subject to fermentation. This bacterial fermentation was found to be catalyzed by a new isolate, strain GKNTAU, a strictly anaerobic, gram-positive, motile rod that formed subterminal spores. Thiosulfate was a quantitative fermentation product. The other fermentation products were ammonia and acetate, and all could be formed by cell-free extracts.

  5. Genetic manipulation of the obligate chemolithoautotrophic bacterium Thiobacillus denitrificans

    Energy Technology Data Exchange (ETDEWEB)

    Beller, H.R.; Legler, T.C.; Kane, S.R.

    2011-07-15

    Chemolithoautotrophic bacteria can be of industrial and environmental importance, but they present a challenge for systems biology studies, as their central metabolism deviates from that of model organisms and there is a much less extensive experimental basis for their gene annotation than for typical organoheterotrophs. For microbes with sequenced genomes but unconventional metabolism, the ability to create knockout mutations can be a powerful tool for functional genomics and thereby render an organism more amenable to systems biology approaches. In this chapter, we describe a genetic system for Thiobacillus denitrificans, with which insertion mutations can be introduced by homologous recombination and complemented in trans. Insertion mutations are generated by in vitro transposition, the mutated genes are amplified by the PCR, and the amplicons are introduced into T. denitrificans by electroporation. Use of a complementation vector, pTL2, based on the IncP plasmid pRR10 is also addressed.

  6. Synthesis, properties and supramolecular structure of piperazinediium thiosulfate monohydrate

    Indian Academy of Sciences (India)

    Bikshandarkoil R Srinivasan; Ashish R Naik; Sunder N Dhuri; Christian Näther; Wolfgang Bensch

    2011-01-01

    Aqueous reaction of ammonium thiosulfate with piperazine (pip) results in the formation of the title compound (pipH2)[S2O3]$\\cdot$H2O 1 (pipH2 = piperazinediium) in good yield. 1 was characterized by elemental analysis, IR, Raman andNMRspectra, X-ray powder pattern and its structure was determined. On heating at 100°C, 1 transforms to anhydrous piperazinediium thiosulfate 2, which can be rehydrated to the monohydrate on exposure tomoisture. The structure of 1 consists of two crystallographically independent piperazinediium (pipH2)2+ cations located on inversion centers, a thiosulfate anion and a lattice water. The organic cations, thiosulfate anion and lattice water are linked by six varieties of hydrogen bond namely O-H$\\cdots$O, O-H$\\cdots$S, N-H$\\cdots$O, N-H$\\cdots$S, C-H$\\cdots$O and C-H$\\cdots$S, leading to the formation of alternating layers of (pipH2)2+ cations and water linked thiosulfate chains. A comparative study of several compounds charge balanced by the piperazinediium cation is described.

  7. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20

    Directory of Open Access Journals (Sweden)

    William D. Leavitt

    2014-11-01

    Full Text Available Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is identifiable from geological materials. By extension, sulfur isotope records are used to infer the redox balance of marine sedimentary environments, and the oxidation state of Earth’s oceans and atmosphere. However, recent work suggests that our understanding of microbial sulfate reducers (MSRs may be missing complexity associated with the presence and role of key chemical intermediates in the reductive process. This study provides a test of proposed metabolic models of sulfate reduction by growing an axenic culture of the well-studied MSRs, Desulfovibrio alaskensis strain G20, under electron donor limited conditions on the terminal electron acceptors sulfate, sulfite or thiosulfate, and tracking the multiple S isotopic consequences of each condition set. The dissimilatory reduction of thiosulfate and sulfite produce unique minor isotope effects, as compared to the reduction of sulfate. Further, these experiments reveal a complex biochemistry associated with sulfite reduction. That is, under high sulfite concentrations, sulfur is shuttled to an intermediate pool of thiosulfate. Site-specific isotope fractionation (within thiosulfate is very large (34ε ~ 30‰ while terminal product sulfide carries only a small fractionation from the initial sulfite (34ε < 10‰: a signature similar in magnitude to sulfate and thiosulfate reduction. Together these findings show that microbial sulfate reduction (MSR is highly sensitive to the concentration of environmentally important sulfur-cycle intermediates (sulfite and thiosulfate, especially when thiosulfate and the large site-specific isotope effects are involved.

  8. Novel sulfur-oxidizing streamers thriving in perennial cold saline springs of the Canadian high Arctic.

    Science.gov (United States)

    Niederberger, Thomas D; Perreault, Nancy N; Lawrence, John R; Nadeau, Jay L; Mielke, Randall E; Greer, Charles W; Andersen, Dale T; Whyte, Lyle G

    2009-03-01

    The perennial springs at Gypsum Hill (GH) and Colour Peak (CP), situated at nearly 80 degrees N on Axel Heiberg Island in the Canadian high Arctic, are one of the few known examples of cold springs in thick permafrost on Earth. The springs emanate from deep saline aquifers and discharge cold anoxic brines rich in both sulfide and sulfate. Grey-coloured microbial streamers form during the winter months in snow-covered regions of the GH spring run-off channels (-1.3 degrees C to 6.9 degrees C, approximately 7.5% NaCl, 0-20 p.p.m. dissolved sulfide, 1 p.p.m. dissolved oxygen) but disappear during the Arctic summer. Culture- and molecular-based analyses of the 16S rRNA gene (FISH, DGGE and clone libraries) indicated that the streamers were uniquely dominated by chemolithoautotrophic sulfur-oxidizing Thiomicrospira species. The streamers oxidized both sulfide and thiosulfate and fixed CO(2) under in situ conditions and a Thiomicrospira strain isolated from the streamers also actively oxidized sulfide and thiosulfate and fixed CO(2) under cold, saline conditions. Overall, the snow-covered spring channels appear to represent a unique polar saline microhabitat that protects and allows Thiomicrospira streamers to form and flourish via chemolithoautrophic, phototrophic-independent metabolism in a high Arctic winter environment characterized by air temperatures commonly below -40 degrees C and with an annual average air temperature of -15 degrees C. These results broaden our knowledge of the physical and chemical boundaries that define life on Earth and have astrobiological implications for the possibility of life existing under similar Martian conditions.

  9. Thiosulfate leaching of gold from waste mobile phones.

    Science.gov (United States)

    Ha, Vinh Hung; Lee, Jae-chun; Jeong, Jinki; Hai, Huynh Trung; Jha, Manis K

    2010-06-15

    The present communication deals with the leaching of gold from the printed circuit boards (PCBs) of waste mobile phones using an effective and less hazardous system, i.e., a copper-ammonia-thiosulfate solution, as an alternative to the conventional and toxic cyanide leaching of gold. The influence of thiosulfate, ammonia and copper sulfate concentrations on the leaching of gold from PCBs of waste mobile phones was investigated. Gold extraction was found to be enhanced with solutions containing 15-20 mM cupric, 0.1-0.14 M thiosulfate, and 0.2-0.3 M ammonia. Similar trends were obtained for the leaching of gold from two different types of scraps and PCBs of waste mobile phones. From the scrap samples, 98% of the gold was leached out using a solution containing 20 mM copper, 0.12 M thiosulfate and 0.2 M ammonia. Similarly, the leaching of gold from the PCBs samples was also found to be good, but it was lower than that of scrap samples in similar experimental conditions. In this case, only 90% of the gold was leached, even with a contact time of 10h. The obtained data will be useful for the development of processes for the recycling of gold from waste mobile phones.

  10. Permanent draft genome of Thiobacillus thioparus DSM 505(T), an obligately chemolithoautotrophic member of the Betaproteobacteria.

    Science.gov (United States)

    Hutt, Lee P; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha; Mikhailova, Natalia; Stamatis, Dimitrios; Reddy, Tatiparthi; Daum, Chris; Shapiro, Nicole; Ivanova, Natalia; Kyrpides, Nikos; Woyke, Tanja; Boden, Rich

    2017-01-01

    Thiobacillus thioparus DSM 505(T) is one of first two isolated strains of inorganic sulfur-oxidising Bacteria. The original strain of T. thioparus was lost almost 100 years ago and the working type strain is Culture C(T) (=DSM 505(T) = ATCC 8158(T)) isolated by Starkey in 1934 from agricultural soil at Rutgers University, New Jersey, USA. It is an obligate chemolithoautotroph that conserves energy from the oxidation of reduced inorganic sulfur compounds using the Kelly-Trudinger pathway and uses it to fix carbon dioxide It is not capable of heterotrophic or mixotrophic growth. The strain has a genome size of 3,201,518 bp. Here we report the genome sequence, annotation and characteristics. The genome contains 3,135 protein coding and 62 RNA coding genes. Genes encoding the transaldolase variant of the Calvin-Benson-Bassham cycle were also identified and an operon encoding carboxysomes, along with Smith's biosynthetic horseshoe in lieu of Krebs' cycle sensu stricto. Terminal oxidases were identified, viz. cytochrome c oxidase (cbb3, EC 1.9.3.1) and ubiquinol oxidase (bd, EC 1.10.3.10). There is a partial sox operon of the Kelly-Friedrich pathway of inorganic sulfur-oxidation that contains soxXYZAB genes but lacking soxCDEF, there is also a lack of the DUF302 gene previously noted in the sox operon of other members of the 'Proteobacteria' that can use trithionate as an energy source. In spite of apparently not growing anaerobically with denitrification, the nar, nir, nor and nos operons encoding enzymes of denitrification are found in the T. thioparus genome, in the same arrangements as in the true denitrifier T. denitrificans.

  11. Adipocyte induced arterial calcification is prevented with sodium thiosulfate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Neal X., E-mail: xuechen@iupui.edu [Divison of Nephrology, Indiana University School of Medicine, Indianapolis, IN (United States); O’Neill, Kalisha; Akl, Nader Kassis [Divison of Nephrology, Indiana University School of Medicine, Indianapolis, IN (United States); Moe, Sharon M. [Divison of Nephrology, Indiana University School of Medicine, Indianapolis, IN (United States); Roudebush VA Medical Center, Indianapolis, IN (United States)

    2014-06-20

    Highlights: • High phosphorus can induce calcification of adipocytes, even when fully differentiated. • Adipocytes can induce vascular calcification in an autocrine manner. • Sodium thiosulfate inhibits adipocyte calcification. - Abstract: Background: Calcification can occur in fat in multiple clinical conditions including in the dermis, breasts and in the abdomen in calciphylaxis. All of these are more common in patients with advanced kidney disease. Clinically, hyperphosphatemia and obesity are risk factors. Thus we tested the hypothesis that adipocytes can calcify in the presence of elevated phosphorus and/or that adipocytes exposed to phosphorus can induce vascular smooth muscle cell (VSMC) calcification. Methods: 3T3-L1 preadipocytes were induced into mature adipocytes and then treated with media containing high phosphorus. Calcification was assessed biochemically and PCR performed to determine the expression of genes for osteoblast and adipocyte differentiation. Adipocytes were also co-cultured with bovine VSMC to determine paracrine effects, and the efficacy of sodium thiosulfate was determined. Results: The results demonstrated that high phosphorus induced the calcification of differentiated adipocytes with increased expression of osteopontin, the osteoblast transcription factor Runx2 and decreased expression of adipocyte transcription factors peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding protein α (CEBPα), indicating that high phosphorus led to a phenotypic switch of adipocytes to an osteoblast like phenotype. Sodium thiosulfate, dose dependently decreased adipocyte calcification and inhibited adipocyte induced increase of VSMC calcification. Co-culture studies demonstrated that adipocytes facilitated VSMC calcification partially mediated by changes of secretion of leptin and vascular endothelial growth factor (VEGF) from adipocytes. Conclusion: High phosphorus induced calcification of mature adipocytes, and

  12. Characterization of the product of the thiosulfate process for desulfurization of flue gases

    Energy Technology Data Exchange (ETDEWEB)

    Gadalla, A.M.; Gupta, A. (Texas A M Univ., College Station, TX (United States). Chemical Engineering Dept.)

    1994-05-01

    X-ray diffraction, infrared spectroscopy, thermal analysis, scanning electron microscopy, and particle size analysis were used to characterize the product of the thiosulfate process. It was found to consist of a mixture of a solid solution of calcium sulfate in calcium sulfite hemihydrate, calcium sulfate dihydrate, and calcium carbonate. Reactions taking place on heating the byproduct were identified in oxidizing and reducing atmospheres. Pure calcium sulfite hemihydrate as well as solid solutions of CaSO[sub 4] in CaSO[sub 3] [center dot] (1/2)H[sub 2]O with different sulfate concentrations were synthesized in the laboratory. Thermal analyses of pure solid solutions proved that the higher the sulfate content, the higher is the dehydration temperature. Accordingly, taking SO[sub 4][sup 2[minus

  13. Bacterial leaching of metal sulfides proceeds by two indirect mechanisms via thiosulfate or via polysulfides and sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Schippers, A.; Sand, W. [Univ. Hamburg (Germany). Inst. fuer Allgemeine Botanik

    1999-01-01

    Bacterial leaching, the biooxidation of metal sulfides to soluble metal sulfates and sulfuric acid, is effected by specialized bacteria. The acid-insoluble metal sulfides FeS{sub 2}, MoS{sub 2}, and WS{sub 2} are chemically attacked by iron(III) hexahydrate ions, generating thiosulfate, which is oxidized to sulfuric acid. Other metal sulfides are attacked by iron(III) ions and by protons, resulting in the formation of elemental sulfur via intermediary polysulfides. Sulfur is biooxidized to sulfuric acid. This explains leaching of metal sulfides by Thiobacillus thiooxidans.

  14. Extraction of Copper(I Thiosulfate by Modified Chitosan

    Directory of Open Access Journals (Sweden)

    Okky Anggraito

    2014-06-01

    Full Text Available Chitosan is one of non-toxic natural biopolymer and abundance in nature. Chitosan have two active sites such as amine and hydroxyl groups. Amine groups (-NH2 in chitosan can be modified into secondary amine (-NHR. In this research, copper was dissolved as copper(I thiosulfate as anion complex (Cu(S2O323- and chitosan was modified by trimethylamine sulfur trioxide (TMAS. One of hydrogen atom in –NH2 was substituted by –SO3Na. The result of this research, the modified chitosan was identified by FT-IR. FT-IR spectra gave characteristic band at 3600-3200 cm-1 (O-H and N-H; 1648 cm-1 (C=O; 1115,74 cm-1 (S=O and 617,18 cm-1 (N-S. The result of surface analysis using SEM and TEM showed that the surface morphology of sulfated chitosan as a result of modification is different in comparison with chitosan. Based on chitosan, pH extraction was adjusted to pH 3 until 8. After optimum pH of extraction was obtained then re-extraction was done by using thiosulfate solution at 0.05 ; 0.10 ; 0.50 ; and 1.00 M. Extraction and re-extraction of copper(I thiosulfate was analyzed by Atomic Absorption Spectrophotometer (AAS. The highest efficiency extraction using modified chitosan and chitosan respectively at pH 3 and 6. The efficiency re-extraction using modified chitosan and chitosan respectively 100% and below 100%.

  15. Extraction of Copper(I Thiosulfate by Modified Chitosan

    Directory of Open Access Journals (Sweden)

    Okky Anggraito

    2013-12-01

    Full Text Available Chitosan is one of non-toxic natural biopolymer and abundance in nature. Chitosan have two active sites such as amine and hydroxyl groups. Amine groups (-NH2 in chitosan can be modified into secondary amine (-NHR. In this research, copper was dissolved as copper(I thiosulfate as anion complex (Cu(S2O323- and chitosan was modified by trimethylamine sulfur trioxide (TMAS. One of hydrogen atom in –NH2 was substituted by –SO3Na. The result of this research, the modified chitosan was identified by FT-IR. FT-IR spectra gave characteristic band at 3600-3200 cm-1 (O-H and N-H; 1648 cm-1 (C=O; 1115,74 cm-1 (S=O and 617,18 cm-1 (N-S. The result of surface analysis using SEM and TEM showed that the surface morphology of sulfated chitosan as a result of modification is different in comparison with chitosan. Based on chitosan, pH extraction was adjusted to pH 3 until 8. After optimum pH of extraction was obtained then re-extraction was done by using thiosulfate solution at 0.05 ; 0.10 ; 0.50 ; and 1.00 M. Extraction and re-extraction of copper(I thiosulfate was analyzed by Atomic Absorption Spectrophotometer (AAS. The highest efficiency extraction using modified chitosan and chitosan respectively at pH 3 and 6. The efficiency re-extraction using modified chitosan and chitosan respectively 100% and below 100%.

  16. Sulfur geochemistry of hydrothermal waters in Yellowstone National Park, Wyoming, USA. II. Formation and decomposition of thiosulfate and polythionate in Cinder Pool

    Science.gov (United States)

    Xu, Y.; Schoonen, M.A.A.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.

    2000-01-01

    Cinder Pool is an acid-sulfate-chloride boiling spring in Norris Geyser Basin, Yellowstone National Park. The pool is unique in that its surface is partially covered with mm-size, black, hollow sulfur spherules, while a layer of molten sulfur resides at the bottom of the pool (18 m depth). The sulfur speciation in the pool was determined on four different days over a period of two years. Samples were taken to evaluate changes with depth and to evaluate the importance of the sulfur spherules on sulfur redox chemistry. All analyses were conducted on site using a combination of ion chromatography and colorimetric techniques. Dissolved sulfide (H2S), thiosulfate (S2O32−), polythionates (SxO62−), and sulfate were detected. The polythionate concentration was highly variable in time and space. The highest concentrations were found in surficial samples taken from among the sulfur spherules. With depth, the polythionate concentrations dropped off. The maximum observed polythionate concentration was 8 μM. Thiosulfate was rather uniformly distributed throughout the pool and concentrations ranged from 35 to 45 μM. Total dissolved sulfide concentrations varied with time, concentrations ranged from 16 to 48 μM. Sulfate was relatively constant, with concentrations ranging from 1150 to 1300 μM. The sulfur speciation of Cinder Pool is unique in that the thiosulfate and polythionate concentrations are significantly higher than for any other acid-sulfate spring yet sampled in Yellowstone National Park. Complementary laboratory experiments show that thiosulfate is the intermediate sulfoxyanion formed from sulfur hydrolysis under conditions similar to those found in Cinder Pool and that polythionates are formed via the oxidation of thiosulfate by dissolved oxygen. This last reaction is catalyzed by pyrite that occurs as a minor constituent in the sulfur spherules floating on the pool's surface. Polythionate decomposition proceeds via two pathways: (1) a reaction with H2S

  17. Oxidation of dimethylsulfide to tetrathionate by Methylophaga thiooxidans sp. nov.: a new link in the sulfur cycle.

    Science.gov (United States)

    Boden, Rich; Kelly, Donovan P; Murrell, J Colin; Schäfer, Hendrik

    2010-10-01

    A new pathway of dimethylsulfide (DMS) metabolism was identified in a novel species of Gammaproteobacteria, Methylophaga thiooxidans sp. nov., in which tetrathionate (S(4)O(6)(2-)) was the end-product of DMS oxidation. Inhibitor evidence indicated that DMS degradation was initiated by demethylation, catalysed by a corrinoid demethylase. Thiosulfate was an intermediate, which was oxidized to tetrathionate by a cytochrome-linked thiosulfate dehydrogenase. Thiosulfate oxidation was coupled to ATP synthesis, and M. thiooxidans could also use exogenous thiosulfate as an energy source during chemolithoheterotrophic growth on DMS or methanol. Cultures grown on a variety of substrates oxidized thiosulfate, indicating that thiosulfate oxidation was constitutive. The observations have relevance to interactions among sulfur-metabolizing bacteria in the marine environment. The production of tetrathionate from an organosulfur precursor is previously undocumented and represents a potential step in the biogeochemical sulfur cycle, providing a 'shunt' across the cycle.

  18. The Genome of the Epsilonproteobacterial Chemolithoautotroph Sulfurimonas dentrificans

    Energy Technology Data Exchange (ETDEWEB)

    USF Genomics Class; Sievert, Stefan M.; Scott, Kathleen M.; Klotz, Martin G.; Chain, Patrick S.G.; Hauser, Loren J.; Hemp, James; Hugler, Michael; Land, Miriam; Lapidus, Alla; Larimer, Frank W.; Lucas, Susan; Malfatti, Stephanie A.; Meyer, Folker; Paulsen, Ian T.; Ren, Qinghu; Simon, Jorg

    2007-08-08

    Sulfur-oxidizing epsilonproteobacteria are common in a variety of sulfidogenic environments. These autotrophic and mixotrophic sulfur-oxidizing bacteria are believed to contribute substantially to the oxidative portion of the global sulfur cycle. In order to better understand the ecology and roles of sulfur-oxidizing epsilonproteobacteria, in particular those of the widespread genus Sulfurimonas, in biogeochemical cycles, the genome of Sulfurimonas denitrificans DSM1251 was sequenced. This genome has many features, including a larger size (2.2 Mbp), that suggest a greater degree of metabolic versatility or responsiveness to the environment than seen for most of the other sequenced epsilonproteobacteria. A branched electron transport chain is apparent, with genes encoding complexes for the oxidation of hydrogen, reduced sulfur compounds, and formate and the reduction of nitrate and oxygen. Genes are present for a complete, autotrophic reductive citric acid cycle. Many genes are present that could facilitate growth in the spatially and temporally heterogeneous sediment habitat from where Sulfurimonas denitrificans was originally isolated. Many resistance-nodulation-development family transporter genes (10 total) are present; of these, several are predicted to encode heavy metal efflux transporters. An elaborate arsenal of sensory and regulatory protein-encoding genes is in place, as are genes necessary to prevent and respond to oxidative stress.

  19. Iron meteorites can support the growth of acidophilic chemolithoautotrophic microorganisms.

    Science.gov (United States)

    González-Toril, Elena; Martínez-Frías, Jesús; Gómez Gómez, José María; Rull, Fernando; Amils, Ricardo

    2005-06-01

    Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy. The alteration of the surface of the exposed piece of meteorite, the solubilization of its oxidized metal constituents, mainly ferric iron, and the formation of goethite precipitates all clearly indicate that iron-meteorite-based chemolithotrophic metabolism is viable.

  20. Physiology of Haloalkaliphilic Sulfur-oxidizing Bacteria

    NARCIS (Netherlands)

    Banciu, H.L.

    2004-01-01

    The inorganic sulfur oxidation by obligate haloalkaliphilic chemolithoautotrophs was only recently discovered and investigated. These autotrophic sulfur oxidizing bacteria (SOB), capable of oxidation of inorganic sulfur compounds at moderate to high salt concentration and at high pH, can be divided

  1. Metagenome of a Versatile Chemolithoautotroph from Expanding Oceanic Dead Zones

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, David A.; Zaikova, Elena; Howes, Charles L.; Song, Young; Wright, Jody; Tringe, Susannah G.; Tortell, Philippe D.; Hallam, Steven J.

    2009-07-15

    Oxygen minimum zones (OMZs), also known as oceanic"dead zones", are widespread oceanographic features currently expanding due to global warming and coastal eutrophication. Although inhospitable to metazoan life, OMZs support a thriving but cryptic microbiota whose combined metabolic activity is intimately connected to nutrient and trace gas cycling within the global ocean. Here we report time-resolved metagenomic analyses of a ubiquitous and abundant but uncultivated OMZ microbe (SUP05) closely related to chemoautotrophic gill symbionts of deep-sea clams and mussels. The SUP05 metagenome harbors a versatile repertoire of genes mediating autotrophic carbon assimilation, sulfur-oxidation and nitrate respiration responsive to a wide range of water column redox states. Thus, SUP05 plays integral roles in shaping nutrient and energy flow within oxygen-deficient oceanic waters via carbon sequestration, sulfide detoxification and biological nitrogen loss with important implications for marine productivity and atmospheric greenhouse control.

  2. Catabolic and anabolic energy for chemolithoautotrophs in deep-sea hydrothermal systems hosted in different rock types

    Science.gov (United States)

    Amend, Jan P.; McCollom, Thomas M.; Hentscher, Michael; Bach, Wolfgang

    2011-10-01

    Active deep-sea hydrothermal vents are hosted by a range of different rock types, including basalt, peridotite, and felsic rocks. The associated hydrothermal fluids exhibit substantial chemical variability, which is largely attributable to compositional differences among the underlying host rocks. Numerical models were used to evaluate the energetics of seven inorganic redox reactions (potential catabolisms of chemolithoautotrophs) and numerous biomolecule synthesis reactions (anabolism) in a representative sampling of these systems, where chemical gradients are established by mixing hydrothermal fluid with seawater. The wide ranging fluid compositions dictate demonstrable differences in Gibbs energies (Δ G r) of these catabolic and anabolic reactions in three peridotite-hosted, six basalt-hosted, one troctolite-basalt hybrid, and two felsic rock-hosted systems. In peridotite-hosted systems at low to moderate temperatures (10), hydrogen oxidation yields the most catabolic energy, but the oxidation of methane, ferrous iron, and sulfide can also be moderately exergonic. At higher temperatures, and consequent SW:HF mixing ratios catabolic energy source at all temperatures (and SW:HF ratios) considered. The energetics of catabolism at the troctolite-basalt hybrid system were intermediate to these extremes. Reaction energetics for anabolism in chemolithoautotrophs—represented here by the synthesis of amino acids, nucleotides, fatty acids, saccharides, and amines—were generally most favorable at moderate temperatures (22-32 °C) and corresponding SW:HF mixing ratios (˜15). In peridotite-hosted and the troctolite-basalt hybrid systems, Δ G r for primary biomass synthesis yielded up to ˜900 J per g dry cell mass. The energetics of anabolism in basalt- and felsic rock-hosted systems were far less favorable. The results suggest that in peridotite-hosted (and troctolite-basalt hybrid) systems, compared with their basalt (and felsic rock) counterparts, microbial

  3. Microbial- and Thiosulfate-Mediated Dissolution of Mercury Sulfide Minerals and Transformation to Gaseous Mercury

    Directory of Open Access Journals (Sweden)

    Adiari eVázquez-Rodríguez

    2015-06-01

    Full Text Available Mercury (Hg is a toxic heavy metal that poses significant human and environmental health risks. Soils and sediments, where Hg can exist as the Hg sulfide mineral metacinnabar (β-HgS, represent major Hg reservoirs in aquatic environments. Metacinnabar has historically been considered a sink for Hg in all but severely acidic environments, and thus disregarded as a potential source of Hg back to aqueous or gaseous pools. Here, we conducted a combination of field and laboratory incubations to identify the potential for metacinnabar as a source of dissolved Hg within near neutral pH environments and the underpinning (abiotic mechanisms at play. We show that the abundant and widespread sulfur-oxidizing bacterium Thiobacillus extensively colonized metacinnabar chips incubated within aerobic, near neutral pH creek sediments. Laboratory incubations of axenic Thiobacillus cultures lead to the release of metacinnabar-hosted Hg(II and subsequent volatilization to Hg(0. This dissolution and volatilization was greatly enhanced in the presence of the sulfur intermediate, thiosulfate, which served a dual role by enhancing HgS dissolution and providing an additional metabolic substrate for Thiobacillus. These findings reveal a new coupled abiotic-biotic pathway for the transformation of metacinnabar-bound Hg(II to Hg(0, while expanding the sulfide substrates available for neutrophilic chemosynthetic bacteria to Hg-laden sulfides. They also point to mineral-hosted Hg as an underappreciated source of gaseous elemental Hg to the environment.

  4. RATES OF SULFATE REDUCTION AND THIOSULFATE CONSUMPTION IN A MARINE MICROBIAL MAT

    NARCIS (Netherlands)

    VISSCHER, PT; PRINS, RA; VANGEMERDEN, H

    1992-01-01

    The sulfur cycle in a microbial mat was studied by determining viable counts of sulfate-reducing bacteria, chemolithoautotrophic sulfur bacteria and anoxygenic phototrophic bacteria. All three functional groups of sulfur bacteria revealed a maximum population density in the uppermost 5 mm of the mat

  5. Primary hepatocytes from mice lacking cysteine dioxygenase show increased cysteine concentrations and higher rates of metabolism of cysteine to hydrogen sulfide and thiosulfate.

    Science.gov (United States)

    Jurkowska, Halina; Roman, Heather B; Hirschberger, Lawrence L; Sasakura, Kiyoshi; Nagano, Tetsuo; Hanaoka, Kenjiro; Krijt, Jakub; Stipanuk, Martha H

    2014-05-01

    The oxidation of cysteine in mammalian cells occurs by two routes: a highly regulated direct oxidation pathway in which the first step is catalyzed by cysteine dioxygenase (CDO) and by desulfhydration-oxidation pathways in which the sulfur is released in a reduced oxidation state. To assess the effect of a lack of CDO on production of hydrogen sulfide (H2S) and thiosulfate (an intermediate in the oxidation of H2S to sulfate) and to explore the roles of both cystathionine γ-lyase (CTH) and cystathionine β-synthase (CBS) in cysteine desulfhydration by liver, we investigated the metabolism of cysteine in hepatocytes isolated from Cdo1-null and wild-type mice. Hepatocytes from Cdo1-null mice produced more H2S and thiosulfate than did hepatocytes from wild-type mice. The greater flux of cysteine through the cysteine desulfhydration reactions catalyzed by CTH and CBS in hepatocytes from Cdo1-null mice appeared to be the consequence of their higher cysteine levels, which were due to the lack of CDO and hence lack of catabolism of cysteine by the cysteinesulfinate-dependent pathways. Both CBS and CTH appeared to contribute substantially to cysteine desulfhydration, with estimates of 56 % by CBS and 44 % by CTH in hepatocytes from wild-type mice, and 63 % by CBS and 37 % by CTH in hepatocytes from Cdo1-null mice.

  6. Dealing with the sulfur part of cysteine: four enzymatic steps degrade l-cysteine to pyruvate and thiosulfate in Arabidopsis mitochondria.

    Science.gov (United States)

    Höfler, Saskia; Lorenz, Christin; Busch, Tjorven; Brinkkötter, Mascha; Tohge, Takayuki; Fernie, Alisdair R; Braun, Hans-Peter; Hildebrandt, Tatjana M

    2016-07-01

    Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of l-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate, the sulfhydryl group from l-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light-limiting conditions. Characterization of a double mutant produced from Arabidopsis thaliana T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence.

  7. Importance of Hydrogen Sulfide, Thiosulfate, and Methylmercaptan for Growth of Thiobacilli during Simulation of Concrete Corrosion.

    Science.gov (United States)

    Sand, W

    1987-07-01

    Biogenic sulfuric acid corrosion of concrete surfaces caused by thiobacilli was reproduced in simulation experiments. At 9 months after inoculation with thiobacilli, concrete blocks were severely corroded. The sulfur compounds hydrogen sulfide, thiosulfate, and methylmercaptan were tested for their corrosive action. With hydrogen sulfide, severe corrosion was noted. The flora was dominated by Thiobacillus thiooxidans. Thiosulfate led to medium corrosion and a dominance of Thiobacillus neapolitanus and Thiobacillus intermedius. Methylmercaptan resulted in negligible corrosion. A flora of heterotrophs and fungi grew on the blocks. This result implies that methylmercaptan cannot be degraded by thiobacilli.

  8. 77 FR 71006 - Sodium Nitrite Injection and Sodium Thiosulfate Injection Drug Products Labeled for the Treatment...

    Science.gov (United States)

    2012-11-28

    ... HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2012-N-1134 Sodium Nitrite Injection and Sodium Thiosulfate Injection Drug Products Labeled for the Treatment of Cyanide Poisoning; Enforcement... products containing sodium nitrite labeled for the treatment of cyanide poisoning and unapproved...

  9. Effect of Additional Sulfide and Thiosulfate on Corrosion of Q235 Carbon Steel in Alkaline Solutions

    Directory of Open Access Journals (Sweden)

    Bian Li Quan

    2016-01-01

    Full Text Available This paper investigated the effect of additional sulfide and thiosulfate on Q235 carbon steel corrosion in alkaline solutions. Weight loss method, scanning electron microscopy (SEM equipped with EDS, X-ray photoelectron spectroscopy (XPS, and electrochemical measurements were used in this study to show the corrosion behavior and electrochemistry of Q235 carbon steel. Results indicate that the synergistic corrosion rate of Q235 carbon steel in alkaline solution containing sulfide and thiosulfate is larger than that of sulfide and thiosulfate alone, which could be due to redox reaction of sulfide and thiosulfate. The surface cracks and pitting characteristics of the specimens after corrosion were carefully examined and the corrosion products film is flake grains and defective. The main corrosion products of specimen induced by S2− and S2O32- are FeS, FeS2, Fe3O4, and FeOOH. The present study shows that the corrosion mechanism of S2− and S2O32- is different for the corrosion of Q235 carbon steel.

  10. Roles of thermophilic thiosulfate-reducing bacteria and methanogenic archaea in the biocorrosion of oil pipelines.

    Science.gov (United States)

    Liang, Renxing; Grizzle, Robert S; Duncan, Kathleen E; McInerney, Michael J; Suflita, Joseph M

    2014-01-01

    Thermophilic sulfide-producing microorganisms from an oil pipeline network were enumerated with different sulfur oxyanions as electron acceptors at 55°C. Most-probable number (MPN) analysis showed that thiosulfate-reducing bacteria were the most numerous sulfidogenic microorganisms in pipeline inspection gauge (PIG) scrapings. Thiosulfate-reducing and methanogenic enrichments were obtained from the MPN cultures that were able to use yeast extract as the electron donor. Molecular analysis revealed that both enrichments harbored the same dominant bacterium, which belonged to the genus Anaerobaculum. The dominant archaeon in the methanogenic enrichment was affiliated with the genus Methanothermobacter. With yeast extract as the electron donor, the general corrosion rate by the thiosulfate-reducing enrichment (8.43 ± 1.40 milli-inch per year, abbreviated as mpy) was about 5.5 times greater than the abiotic control (1.49 ± 0.15 mpy), while the comparable measures for the methanogenic culture were 2.03 ± 0.49 mpy and 0.62 ± 0.07 mpy, respectively. Total iron analysis in the cultures largely accounted for the mass loss of iron measured in the weight loss determinations. Profilometry analysis of polished steel coupons incubated in the presence of the thiosulfate-reducing enrichment revealed 59 pits over an area of 71.16 mm(2), while only 6 pits were evident in the corresponding methanogenic incubations. The results show the importance of thiosulfate-utilizing, sulfide-producing fermentative bacteria such as Anaerobaculum sp. in the corrosion of carbon steel, but also suggest that Anaerobaculum sp. are of far less concern when growing syntrophically with methanogens.

  11. Roles of thermophilic thiosulfate-reducing bacteria and methanogenic archaea in the biocorrosion of oil pipelines

    Directory of Open Access Journals (Sweden)

    Renxing eLiang

    2014-03-01

    Full Text Available Thermophilic sulfide-producing microorganisms from an oil pipeline network were enumerated with different sulfur oxyanions as electron acceptors at 55 oC. Most-probable number (MPN analysis showed that thiosulfate-reducing bacteria were the most numerous sulfidogenic microorganisms in pipeline inspection gauge (PIG scrapings. Thiosulfate-reducing and methanogenic enrichments were obtained from the MPN cultures that were able to use yeast extract as the electron donor. Molecular analysis revealed that both enrichments harbored the same dominant bacterium, which belonged to the genus Anaerobaculum. The dominant archaeon in the methanogenic enrichment was affiliated with the genus Methanothermobacter. With yeast extract as the electron donor, the general corrosion rate by the thiosulfate-reducing enrichment (8.43 ± 1.40 milli-inch per year, abbreviated as mpy was about 5.5 times greater than the abiotic control (1.49 ± 0.15 mpy, while the comparable measures for the methanogenic culture were 2.03 ± 0.49 mpy and 0.62 ± 0.07 mpy, respectively. Total iron analysis in the cultures largely accounted for the mass loss of iron measured in the weight loss determinations. Profilometry analysis of polished steel coupons incubated in the presence of the thiosulfate-reducing enrichment revealed 59 pits over an area of 71.16 mm2, while only 6 pits were evident in the corresponding methanogenic incubations. The results show the importance of thiosulfate-utilizing, sulfide-producing fermentative bacteria such as Anaerobaculum sp. in the corrosion of carbon steel, but also suggest that Anaerobaculum sp. are of far less concern when growing syntrophically with methanogens.

  12. Assessment of the stoichiometry and efficiency of CO2 fixation coupled to reduced sulfur oxidation

    NARCIS (Netherlands)

    Klatt, Judith M.; Polerecky, Lubos

    2015-01-01

    Chemolithoautotrophic sulfur oxidizing bacteria (SOB) couple the oxidation of reduced sulfur compounds to the production of biomass. Their role in the cycling of carbon, sulfur, oxygen, and nitrogen is, however, difficult to quantify due to the complexity of sulfur oxidation pathways. We describe a

  13. The role of silver nano-particles and silver thiosulfate on the longevity of cut carnation (Dianthus caryophyllus) flowers.

    Science.gov (United States)

    Hashemabadi, Davood

    2014-07-01

    The purpose of this study was to evaluate the efficacy of silver nano-particles (SNP) and silver thiosulfate (STS) in extending the vase life of cut carnation (Dianthus caryophyllus L. cv. 'Tempo') flowers. Pulse treatments of SNP @ 0, 5, 10 and 15 mg l(-1) and STS @ 0, 0.1, 0.2 and 0.3 mM were administered to carnation flowers for 24 hr. The longest vase life (16.1 days) was observed in flowers treated with 15 mg l(-1) of SNP + 0.2 mM STS. The least chlorophyll was destroyed in flowers treated with 15 mg I(-1) of SNP + 0.3 mM STS. Our findings showed that the 15 mg l(-1) SNP treatment inhibited bacterial growth in the preservative solution. The control flowers bloomed faster than the treated flowers. The maximum peroxidase activity and the minimum lipid peroxidation were obtained in cut flowers that were treated with 15 mg l(-1) of SNP and 0.3 mM STS. Overall, results of the study revealed that SNP and STS treatment extended the longevity of cut carnation 'Tempo' flowers by reducing oxidative stress, improving anti-oxidant system, reducing bacterial populations and delaying flowering.

  14. Method for aqueous gold thiosulfate extraction using copper-cyanide pretreated carbon adsorption

    Science.gov (United States)

    Young, Courtney; Melashvili, Mariam; Gow, Nicholas V

    2013-08-06

    A gold thiosulfate leaching process uses carbon to remove gold from the leach liquor. The activated carbon is pretreated with copper cyanide. A copper (on the carbon) to gold (in solution) ratio of at least 1.5 optimizes gold recovery from solution. To recover the gold from the carbon, conventional elution technology works but is dependent on the copper to gold ratio on the carbon.

  15. Gold cementation on copper in thiosulfate solution: Kinetic, electrochemical, and morphological studies

    Science.gov (United States)

    Lee, Jaeheon

    2003-08-01

    Cyanidation has been used for more than a century for precious metal recovery and it is still in use today. Cyanide is a very toxic chemical and if not used appropriately will cause environmental problems. There is considerable attention devoted to the development of non-cyanide lixiviants for the process of gold and silver ores. Thiosulfate solution is one of the proposed alternatives to cyanide and gold cementation by copper has been suggested as a promising method for gold recovery from leaching solution. Copper powder and rotating disc electrode were used for the kinetic study. The rate of gold cementation on copper disc is proportional to the initial gold concentration and disc rotating speed. The cementation reaction exhibited two distinct kinetic regions, an initial slow rate followed by an enhanced rate. The activation energy of the reaction was 5.9 kJ/mol at low copper concentration and the reaction is mass transport controlled. With 30 ppm initial copper concentration, there was noticeable decrease in the reaction rate in high temperature range. EDS, XRD, and XPS analysis revealed that the deposits are a Au-Cu alloy instead of pure gold. The alloy composition ranged from Au 3Cu to AuCu3 depending on the initial Cu/Au mole ratio in solution and applied potential. Electrochemical studies were performed using rotating disc electrode and electrochemical quartz crystal nanobalance. Evans' diagrams were constructed under various experimental conditions. Corrosion current increased with increasing gold concentration, disc rotating speed, as well as thiosulfate concentration. These results confirmed those obtained in the kinetic study. Corrosion potential measurements indicated that passivation onset time was changed by gold concentration, copper concentration and disc rotating speed. Gold(I)-thiosulfate reduction was found to occur at approximately -250 mV vs. SHE using EQCN. Copper adions on the gold surface contributed to the underpotential deposition of

  16. Complete Genome Sequence of Nitrosomonas cryotolerans ATCC 49181, a Phylogenetically Distinct Ammonia-Oxidizing Bacterium Isolated from Arctic Waters.

    Science.gov (United States)

    Rice, Marlen C; Norton, Jeanette M; Stein, Lisa Y; Kozlowski, Jessica; Bollmann, Annette; Klotz, Martin G; Sayavedra-Soto, Luis; Shapiro, Nicole; Goodwin, Lynne A; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Varghese, Neha; Mikhailova, Natalia; Palaniappan, Krishna; Ivanova, Natalia; Mukherjee, Supratim; Reddy, T B K; Yee Ngan, Chew; Daum, Chris; Kyrpides, Nikos; Woyke, Tanja

    2017-03-16

    Nitrosomonas cryotolerans ATCC 49181 is a cold-tolerant marine ammonia-oxidizing bacterium isolated from seawater collected in the Gulf of Alaska. The high-quality complete genome contains a 2.87-Mbp chromosome and a 56.6-kbp plasmid. Chemolithoautotrophic modules encoding ammonia oxidation and CO2 fixation were identified.

  17. Complete genome sequence of Nitrosomonas sp. Is79, an ammonia oxidizing bacterium adapted to low ammonium concentrations

    NARCIS (Netherlands)

    Bollmann, A.; Sedlacek, C.J.; Norton, J.; Laanbroek, H.J.; Suwa, Y.; Stein, L.Y.; Klotz, M.G.; Arp, D.; Sayavedra-Soto, L.; Lu, M.; Bruce, D.; Detter, C.; Tapia, R.; Han, J.; Woyke, T.; Lucas, S.; Pitluck, S.; Pennacchio, L.; Nolan, M.; Land, M.L.; Huntemann, M.; Deshpande, S.; Han, C.; Chen, A.; Kyrpides, N.; Mavromatis, K.; Markowitz, V.; Szeto, E.; Ivanova, N.; Mikhailova, N.; Pagani, I.; Pati, A.; Peters, L.; Ovchinnikova, G.; Goodwin, L.

    2013-01-01

    Nitrosomonas sp. Is79 is a chemolithoautotrophic ammonia-oxidizing bacterium that belongs to the family Nitrosomonadaceae within the phylum Proteobacteria. Ammonia oxidation is the first step of nitrification, an important process in the global nitrogen cycle ultimately resulting in the production o

  18. Acute Cyanide Poisoning: Hydroxocobalamin and Sodium Thiosulfate Treatments with Two Outcomes following One Exposure Event

    Directory of Open Access Journals (Sweden)

    Andrew Meillier

    2015-01-01

    Full Text Available Cyanide is rapidly reacting and causes arrest of aerobic metabolism. The symptoms are diffuse and lethal and require high clinical suspicion. Remediation of symptoms and mortality is highly dependent on quick treatment with a cyanide antidote. Presently, there are two widely accepted antidotes: sodium thiosulfate and hydroxocobalamin. These treatments act on different components of cyanide’s metabolism. Here, we present two cases resulting from the same source of cyanide poisoning and the use of both antidotes separately used with differing outcomes.

  19. Crystal structure of bis(1,4-diazabicyclo[2.2.2]octan-1-ium thiosulfate dihydrate

    Directory of Open Access Journals (Sweden)

    Gorgui Awa Seck

    2016-03-01

    Full Text Available The crystal structure of the hydrated title salt, 2C6H13N2+·S2O32−·2H2O, contains a centrosymmetric cyclic motif of eight hydrogen-bonded molecular subunits. Two DABCOH+ cations (DABCO = 1,4-diazabicyclo[2.2.2]octane are linked to two water molecules and two thiosulfate anions via O—H...N and O—H...O hydrogen bonds, respectively. Two other water molecules close the cyclic motif through O—H...O contacts to the first two water molecules and to the two thiosulfate anions. A second pair of DABCOH+ cations is N—H...O hydrogen bonded to the two anions and is pendant to the ring. Adjacent cyclic motifs are bridged into a block-like arrangement extending along [100] through O—H...O interactions involving the second pair of water molecules and neighbouring thiosulfate anions.

  20. Recovery of gold from solutions with ammonia and thiosulfate using activated carbon; Recuperacion de oro a partir de disoluciones de amoniaco y tiosulfato utilizando carbon activado

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, C.; Navarro, P.; Araya, E.; Pavez, F.; Alguacil, F. J.

    2006-07-01

    The recovery of gold from solutions containing thiosulfate and ammonia using granular activated carbon was studied,evaluating the adsorption and elution stages. The influence of ammonia and thiosulfate concentration and the presence of impurities such as copper and zinc were also evaluated. In the presence of ammonia there was a concentration which maximized the adsorption of gold, while thiosulfate and impurities presence was harmful for the adsorption of gold. during elution, ammonia and thiosulfate concentration, pH regulator and temperature were evaluated. Ammonia favored the process as long as thiosulfate showed a maximum starting from which the elution diminishes. The effect of the pH regulator was very important; If was revealed that when the pH was regulated with caustic ammonia, a synergic effect appeared which favored the elution. Temperature favored the elution process, with activation energy of 9.13 kJ/mol. (Author) 25 refs.

  1. Kinetics of the initial steps in the aqueous oxidation of thiosulfate by chlorine dioxide.

    Science.gov (United States)

    Pan, Changwei; Stanbury, David M

    2014-08-28

    The reaction of ClO2(•) with S2O3(2-) in aqueous solution is a component of the "crazy clock" reaction of ClO2(-) with S2O3(2-), and under conditions of excess S2O3(2-) the absorbance at 360 nm due to ClO2(•) decays with sigmoidal kinetics. A chain reaction mechanism is inferred on the basis that very small concentrations of SO3(2-) accelerate the reaction, and methionine inhibits the reaction. Pseudo-first-order kinetics is observed in the presence of relatively large methionine concentrations, leading to the simple rate law -d[ClO2]/dt = (ka[S2O3(2-)] + kb[S2O3(2-)](2))[ClO2], with ka = 452 ± 16 M(-1) s(-1) and kb = (5.7 ± 0.2) × 10(5) M(-2) s(-1) at 25 °C and pH 7.6. Under these conditions, the initial products are ClO2(-) and S4O6(2-). A classical electron-transfer mechanism is assigned to the reaction that occurs under conditions of methionine inhibition.

  2. Multi-Modal Treatment Of Calciphylaxis With Sodium-Thiosulfate, Cinacalcet And Sevelamer Including Long-Term Data

    Directory of Open Access Journals (Sweden)

    Hermann Salmhofer

    2013-09-01

    Full Text Available Background: Calciphylaxis is a rare, yet life-threatening disease mainly occurring in dialysis patients. Traditional options of treatment remain unsatisfactory. Methods: Here we present a novel, combined approach, treating calciphylaxis with IV sodium thiosulfate, cinacalcet and sevelamer. In a case series five hemodialysis patients, have been successfully treated with this regimen. Treatment and survival data were analyzed using descriptive statistics. Results: In all patients, a rapid decrease in pain, improvement of general condition and wound healing within six months occurred. Side effects were low. Drug dosages: IV sodium thiosulfate initial dose 119.4 +/- 84.9 g/m2/week, maintenance dose 40.6 +/- 9 g/m2/week; cinacalcet: maintenance dose 36 +/- 32.9 mg/d and sevelamer maintenance dose 3320 +/-1671 mg/d. One and two year survivals were 100 % and 80 %, respectively. We also report on long-term application of IV sodium thiosulfate of up to 52 months. Patient survival after diagnosis was 52, 84, 21, 36 and 30 months, respectively. Survival since initiation of hemodialysis was 76, 136, 89, 36 and 35 months, respectively. Conclusion: This novel combined approach, a multi-modal treatment of calciphylaxis with persistent hyperparathyroidism, using IV sodium thiosulfate, cinacalcet and sevelamer seems to improve the outcome of this devastating disease.

  3. Sodium Thiosulfate Versus Hydroxocobalamin in the Treatment of Acute, Severe Cyanide Induced Cardiotoxicity in a Swine (Sus Scrofa) Model

    Science.gov (United States)

    2011-09-22

    IUIVIJ:lt:M Sodium thiosulfate versus hydroxocoba~amin in the treatment of acute, severe cyanide induced cardiotoxicity in a swine (Sus Scrofa )model on...treatment of acute, severe cyanide induced cardiotoxicity in a swine (Sus Scrofa ) model .. 4. Principal Investigator (PI): ’ ~ I ’ ·, .. Name Rank Date

  4. Surface effects of monolayer-protected gold nanoparticles on the redox reactions between ferricyanide and thiosulfate

    Institute of Scientific and Technical Information of China (English)

    LI Di; SUN Chunyan; HUANG Yunjie; LI Jinghong; CHEN Shaowei

    2005-01-01

    Electron transfer through the self-assembled monolayers (SAMs) on gold nanoparticles is investigated by using the monolayer protected gold nanoclusters (MPCs) as electron-transfer mediators. 3-Mercaptopropionic acid (MPA) and 11-meraptoundecanoic acid (MUA) MPCs were employed to catalyze the redox reaction between potassium ferricyanide and sodium thiosulfate. The catalytic mechanism was proposed that the MPCs act as diffusing electron-mediators and electron transfers to and from the MPCs surface. Therefore the electron transfer rate through the capping layers would be proportional to the MPCs catalyzed reaction rate, which was monitored by the UV absorbance of ferricyanide. The calculated apparent rate constant was orders of magnitude smaller than that of the maximum of tunneling current, which was attributed to the splited energy level of the nanoscale particles.

  5. Long-lasting patch reactions to gold sodium thiosulfate occurs frequently in healthy volunteers

    DEFF Research Database (Denmark)

    Andersen, Klaus E; Jensen, Charlotte D

    2007-01-01

    with a contact allergic reaction, and the crescendo type of the response speaks in favour of an allergic nature. Further, 8 of the 31 (26%) developed long-lasting test reactions. A follow-up interview among 28/31 participants 10 years later showed that none had experienced long-term consequences in the form......In a skin irritancy study in healthy volunteers with 3 metal salts, aqueous gold sodium thiosulfate (GSTS) in a dilution series caused unexpectedly frequent and strong patch test reactions on volar forearm skin in 22 of 31 participants (71%). The reactions showed morphological features consistent...... of skin and/or mucosal complaints related to exposure to gold items. The results indicate that inclusion of GSTS in routine patch testing may cause problems regarding interpretation and clinical relevance of positive GSTS patch tests, which fulfil the clinical criteria of a contact allergy....

  6. Penile calciphylaxis: a life-threatening condition successfully treated with sodium thiosulfate.

    Science.gov (United States)

    Sandhu, Gagangeet; Gini, Marcelo Barrios; Ranade, Aditi; Djebali, David; Smith, Steven

    2012-01-01

    Calciphylaxis or calcific uremic arteriolopathy is a life-threatening condition that predominantly affects patients with end-stage renal disease on hemodialysis. A prevalence of up to 4% and a 6-month mortality rate of up to 80% have been reported in those with proximal disease (thighs, abdomen wall, and buttocks). Penile calciphylaxis is very rare but has a mortality rate of 69% within 6 months. Its treatment is controversial. For small lesions, conservative treatment with local wound care and debridement may suffice. Partial or complete penectomy may be needed for more extensive lesions, and especially those associated with signs of local infection. In addition to surgical intervention, as with any other case of calcific uremic arteriolopathy, the cornerstones of therapy should be to keep serum phosphorus sodium thiosulfate was used in addition to the standard medical and surgical therapy. Two months after surgery, the patient's wound completely healed and he has experienced no new lesions over the past 11 months.

  7. Separation of sulfite, sulfate, and thiosulfate by ion chromatography with gradient elution

    Energy Technology Data Exchange (ETDEWEB)

    Sunden, T. (Univ. of Umea, Sweden); Lindgren, M.; Cedergren, A.; Siemer, D.D.

    1983-01-01

    A simple gradient apparatus, consisting of a peristaitic pump in addition to a standard high-pressure pump, is described. The device is used to make a single-run ion chromotographic separation of sulfite, sulfate, and thiosulfate in less than 15 min. This separation required a step gradient with 4.8 mM NaHCO/sub 3//4.7 mM Na/sub 2/CO/sub 3/ as start eluent and 6.9 mM NaHCO/sub 3//8.6 mM Na/sub 2/CO/sub 3/ is final eluent when two (4 x 50) mm Dionex anion precolumns in series were used as separator. The eluent compositions were simplex optimized.

  8. Evaluation of thiosulfate as a substitute for hydrogen sulfide in sour corrosion fatigue studies

    Science.gov (United States)

    Kappes, Mariano Alberto

    This work evaluates the possibility of replacing hydrogen sulfide (H 2S) with thiosulfate anion (S2O32- ) in sour corrosion fatigue studies. H2S increases the corrosion fatigue crack growth rate (FCGR) and can be present in carbon steel risers and flowlines used in off-shore oil production. Corrosion tests with gaseous H2S require special facilities with safety features, because H2S is a toxic and flammable gas. The possibility of replacing H2S with S2O32-, a non-toxic anion, for studying stress corrosion cracking of stainless and carbon steels in H2S solutions was first proposed by Tsujikawa et al. ( Tsujikawa et al., Corrosion, 1993. 49(5): p. 409-419). In this dissertation, Tsujikawa work will be extended to sour corrosion fatigue of carbon steels. H2S testing is often conducted in deareated condition to avoid oxygen reaction with sulfide that yields sulfur and to mimic oil production conditions. Nitrogen deareation was also adopted in S2O3 2- testing, and gas exiting the cell was forced through a sodium hydroxide trap. Measurements of the sulfide content of this trap were used to estimate the partial pressure of H2S in nitrogen, and Henry's law was used to estimate the content of H2S in the solution in the cell. H2S was produced by a redox reaction of S2O 32-, which required electrons from carbon steel corrosion. This reaction is spontaneous at the open circuit potential of steel. Therefore, H2S concentration was expected to be maximum at the steel surface, and this concentration was estimated by a mass balance analysis. Carbon steel specimens exposed to S2O32- containing solutions developed a film on their surface, composed by iron sulfide and cementite. The film was not passivating and a good conductor of electrons. Hydrogen permeation experiments proved that this film controls the rate of hydrogen absorption of steels exposed to thiosulfate containing solutions. The absorption of hydrogen in S2O3 2- solutions was compared with the absorption of hydrogen in

  9. Quantitation of sulfate and thiosulfate in clinical samples by ion chromatography.

    Science.gov (United States)

    Cole, D E; Evrovski, J

    1997-11-21

    For assay of serum sulfate, quantitation by ion conductimetry after separation by anion-exchange chromatography is the method of choice. In comparison to classical barium precipitation methods, chromatographic methods demonstrate increased precision, specificity and sensitivity, and they may be superior to spectrophotometric methods that rely on organic cation precipitation of sulfate. The increased sensitivity and specificity, as well as the inherent capacity of chromatographic methods for simultaneous determination of other anions, has led to its increasing use in the determination of excreted sulfate in clinical profiles of urinary anion composition. Ion chromatography can also be used to quantitate free sulfate in other clinical samples, including cerebrospinal fluid, sweat, saliva, breast milk and human tissues. Finally, ion chromatography shows promise as a more precise and sensitive method for measurement of total acid-labile sulfoesters and thiosulfate.

  10. Genes and pathways for CO2 fixation in the obligate, chemolithoautotrophic acidophile, Acidithiobacillus ferrooxidans, Carbon fixation in A. ferrooxidans

    Directory of Open Access Journals (Sweden)

    Esparza Mario

    2010-08-01

    Full Text Available Abstract Background Acidithiobacillus ferrooxidans is chemolithoautotrophic γ-proteobacterium that thrives at extremely low pH (pH 1-2. Although a substantial amount of information is available regarding CO2 uptake and fixation in a variety of facultative autotrophs, less is known about the processes in obligate autotrophs, especially those living in extremely acidic conditions, prompting the present study. Results Four gene clusters (termed cbb1-4 in the A. ferrooxidans genome are predicted to encode enzymes and structural proteins involved in carbon assimilation via the Calvin-Benson-Bassham (CBB cycle including form I of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO, EC 4.1.1.39 and the CO2-concentrating carboxysomes. RT-PCR experiments demonstrated that each gene cluster is a single transcriptional unit and thus is an operon. Operon cbb1 is divergently transcribed from a gene, cbbR, encoding the LysR-type transcriptional regulator CbbR that has been shown in many organisms to regulate the expression of RubisCO genes. Sigma70-like -10 and -35 promoter boxes and potential CbbR-binding sites (T-N11-A/TNA-N7TNA were predicted in the upstream regions of the four operons. Electrophoretic mobility shift assays (EMSAs confirmed that purified CbbR is able to bind to the upstream regions of the cbb1, cbb2 and cbb3 operons, demonstrating that the predicted CbbR-binding sites are functional in vitro. However, CbbR failed to bind the upstream region of the cbb4 operon that contains cbbP, encoding phosphoribulokinase (EC 2.7.1.19. Thus, other factors not present in the assay may be required for binding or the region lacks a functional CbbR-binding site. The cbb3 operon contains genes predicted to encode anthranilate synthase components I and II, catalyzing the formation of anthranilate and pyruvate from chorismate. This suggests a novel regulatory connection between CO2 fixation and tryptophan biosynthesis. The presence of a form II Rubis

  11. Molecular analysis of the distribution and phylogeny of the soxB gene among sulfur-oxidizing bacteria - evolution of the Sox sulfur oxidation enzyme system.

    Science.gov (United States)

    Meyer, Birte; Imhoff, Johannes F; Kuever, Jan

    2007-12-01

    The soxB gene encodes the SoxB component of the periplasmic thiosulfate-oxidizing Sox enzyme complex, which has been proposed to be widespread among the various phylogenetic groups of sulfur-oxidizing bacteria (SOB) that convert thiosulfate to sulfate with and without the formation of sulfur globules as intermediate. Indeed, the comprehensive genetic and genomic analyses presented in the present study identified the soxB gene in 121 phylogenetically and physiologically divergent SOB, including several species for which thiosulfate utilization has not been reported yet. In first support of the previously postulated general involvement of components of the Sox enzyme complex in the thiosulfate oxidation process of sulfur-storing SOB, the soxB gene was detected in all investigated photo- and chemotrophic species that form sulfur globules during thiosulfate oxidation (Chromatiaceae, Chlorobiaceae, Ectothiorhodospiraceae, Thiothrix, Beggiatoa, Thiobacillus, invertebrate symbionts and free-living relatives). The SoxB phylogeny reflected the major 16S rRNA gene-based phylogenetic lineages of the investigated SOB, although topological discrepancies indicated several events of lateral soxB gene transfer among the SOB, e.g. its independent acquisition by the anaerobic anoxygenic phototrophic lineages from different chemotrophic donor lineages. A putative scenario for the proteobacterial origin and evolution of the Sox enzyme system in SOB is presented considering the phylogenetic, genomic (sox gene cluster composition) and geochemical data.

  12. Complete genome sequence of the facultatively chemolithoautotrophic and methylotrophic alpha Proteobacterium Starkeya novella type strain (ATCC 8093T)

    Energy Technology Data Exchange (ETDEWEB)

    Kappler, Ulrike [University of Queensland, The, Brisbane, Queensland, Australia; Davenport, Karen W. [Los Alamos National Laboratory (LANL); Beatson, Scott [University of Queensland, The, Brisbane, Queensland, Australia; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Berry, Kerrie W. [U.S. Department of Energy, Joint Genome Institute; Glavina Del Rio, Tijana [U.S. Department of Energy, Joint Genome Institute; Hammon, Nancy [U.S. Department of Energy, Joint Genome Institute; Dalin, Eileen [U.S. Department of Energy, Joint Genome Institute; Tice, Hope [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Bruce, David [Los Alamos National Laboratory (LANL); Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Han, Cliff [Los Alamos National Laboratory (LANL); Tapia, Roxanne [Los Alamos National Laboratory (LANL); Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Chang, Yun-Juan [ORNL; Jeffries, Cynthia [Oak Ridge National Laboratory (ORNL); Land, Miriam L [ORNL; Hauser, Loren John [ORNL; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Goker, Markus [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute

    2012-01-01

    Starkeya novella (Starkey 1934) Kelly et al. 2000 is a member of the family Xanthobacteraceae in the order Rhizobiales , which is thus far poorly characterized at the genome level. Cultures from this spe- cies are most interesting due to their facultatively chemolithoautotrophic lifestyle, which allows them to both consume carbon dioxide and to produce it. This feature makes S. novella an interesting model or- ganism for studying the genomic basis of regulatory networks required for the switch between con- sumption and production of carbon dioxide, a key component of the global carbon cycle. In addition, S. novella is of interest for its ability to grow on various inorganic sulfur compounds and several C1- compounds such as methanol. Besides Azorhizobium caulinodans, S. novella is only the second spe- cies in the family Xanthobacteraceae with a completely sequenced genome of a type strain. The cur- rent taxonomic classification of this group is in significant conflict with the 16S rRNA data. The ge- nomic data indicate that the physiological capabilities of the organism might have been underestimat- ed. The 4,765,023 bp long chromosome with its 4,511 protein-coding and 52 RNA genes was se- quenced as part of the DOE Joint Genome Institute Community Sequencing Program (CSP) 2008.

  13. Thiosulfate and Sulfite Distributions in Porewater of Marine-Sediments Related to Manganese, Iron, and Sulfur Geochemistry

    DEFF Research Database (Denmark)

    Thamdrup, B; Finster, Kai; Fossing, Henrik;

    1994-01-01

    Depth distributions of thiosulfate (S2O32-) and sulfite (SO32-) were measured in the porewaters of a Danish salt marsh and subtidal marine sediments by HPLC analysis after derivatization with DTNP [2,2'-dithiobis(5-nitropyridine)]. The distributions were compared to the redox zonation as indicate...... by Eh and Mn2+, Fe2+, and H2S distributions. Concentrations Of S2O32- varied from below detection (...

  14. The Genome of Deep-Sea Vent Chemolithoautotroph Thiomicrospiracrunogena XCL-2

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Kathleen M.; Sievert, Stefan M.; Abril, Fereniki N.; Ball,Lois A.; Barrett, Chantell J.; Blake, Rodrigo A.; Boller, Amanda J.; Chain, Patrick S.G.; Clark, Justine A.; Davis, Carisa R.; Detter, Chris; Do, Kimberly F.; Dobrinski, Kimberly P.; Faza, BrandonI.; Fitzpatrick,Kelly A.; Freyermuth, Sharyn K.; Harmer, Tara L.; Hauser, Loren J.; Hugler, Michael; Kerfeld, Cheryl A.; Klotz, Martin G.; Kong, William W.; Land, Miriam; Lapidus, Alla; Larimer, Frank W.; Longo, Dana L.; Lucas,Susan; Malfatti, Stephanie A.; Massey, Steven E.; Martin, Darlene D.; McCuddin, Zoe; Meyer, Folker; Moore, Jessica L.; Ocampo, Luis H.; Paul,John H.; Paulsen, Ian T.; Reep, Douglas K.; Ren, Qinghu; Ross, Rachel L.; Sato, Priscila Y.; Thomas, Phaedra; Tinkham, Lance E.; Zeruth, Gary T.

    2006-08-23

    Presented here is the complete genome sequence ofThiomicrospira crunogena XCL-2, representative of ubiquitouschemolithoautotrophic sulfur-oxidizing bacteria isolated from deep-seahydrothermal vents. This gammaproteobacterium has a single chromosome(2,427,734 bp), and its genome illustrates many of the adaptations thathave enabled it to thrive at vents globally. It has 14 methyl-acceptingchemotaxis protein genes, including four that may assist in positioningit in the redoxcline. A relative abundance of CDSs encoding regulatoryproteins likely control the expression of genes encoding carboxysomes,multiple dissolved inorganic nitrogen and phosphate transporters, as wellas a phosphonate operon, which provide this species with a variety ofoptions for acquiring these substrates from the environment. T. crunogenaXCL-2 is unusual among obligate sulfur oxidizing bacteria in relying onthe Sox system for the oxidation of reduced sulfur compounds. A 38 kbprophage is present, and a high level of prophage induction was observed,which may play a role in keeping competing populations of close relativesin check. The genome has characteristics consistent with an obligatelychemolithoautotrophic lifestyle, including few transporters predicted tohave organic allocrits, and Calvin-Benson-Bassham cycle CDSs scatteredthroughout the genome.

  15. Ethylene, 1-methylcyclopropene and silver thiosulfate on the post-production of ornamental pepper

    Directory of Open Access Journals (Sweden)

    Paula Cristina Carvalho Lima

    Full Text Available ABSTRACT: Species from Capsicum genus are used for different purposes and in more recent years as ornamental potted plant. Despite the increased commercial importance, there are only a few studies on the environmental factors affecting the post-production shelf life of these ornamental plants. The presence of ethylene induces various responses on potted peppers, reducing the shelf life of sensitive cultivars. This study aimed to evaluate the effects of ethylene and the inhibitors of ethylene action, 1-methylcyclopropene (1-MCP and silver thiosulfate (STS on the shelf life of potted 'Calypso' and 'MG 302' peppers. Cultivar 'MG 302' showed intermediate sensitivity to ethylene action, while the cultivar 'Calypso' showed complete abscission of leaves when exposed to ethylene. In both cultivars, treatment with STS + Ethylene presented symptoms of phytotoxicity in plants, while treatment with 1-MCP + Ethylene was effective in delaying senescence and abscission for the cultivar 'MG 302', while cultivar 'Calypso' showed abscission similar to control plants. Plants treated with STS showed the longest durability when compared to the other treatments, about six days for 'Calypso' and 18 days for 'MG 302'. Nevertheless, plants treated with 1-MCP also exhibited good shelf life, about six days for 'Calypso' and nine days for the 'MG 302'. Although the treatment with STS was more efficient on the plants shelf life, did not completely block the action of ethylene and exhibited some phytotoxicity, while the treatment with 1-MCP had good efficiency without inducing any toxicity.

  16. 氰化法、硫代硫酸盐法、硫脲法浸出某难浸银精矿比较研究%Comparisons of leaching a silver ore with cyanide, thiosulfate and thiourea solutions

    Institute of Scientific and Technical Information of China (English)

    张帅; 曾怀远; 张村; 方夕辉

    2015-01-01

    对某浮选银精矿采用氰化法、硫代硫酸盐法、硫脲法进行银浸出实验,以评估3种不同浸出方法对该银精矿浸出效果.研究结果表明:在最优的工艺参数下[氰化法:碱预处理后加入铵盐,氰化钠浓度0.15 mol/L,pH值为11,液固比(浸出液体积与试样质量之比,单位是mL/g,下同)2∶1,搅拌强度500 r/min,浸出时间为48 h;硫代硫酸盐法:氧化焙烧预处理,氨水浓度1.0 mol/L,硫酸铜浓度0.01 mol/L,硫代硫酸钠浓度0.2 mol/L,pH值为10,液固比4∶1,搅拌强度500 r/min,浸出时间12 h;硫脲法:氧化焙烧和稀硫酸预浸处理,Fe3+浓度7.5×10-3 mol/L,硫脲浓度0.18 mol/L,pH=1.0,液固比为3∶1,搅拌速度250 r/min,浸出时间24 h],硫代硫酸盐方法获得的Ag浸出率为78.58%,硫脲相应获得的Ag浸出率为62.43%,比氰化法获得的浸出率低约3.33%.%The leaching experiments are performed on samples collected from a silver concentrate with cyanide, thiosulfate and thiourea solutions respectively to compare their extraction effects. The result indicates that, under the optimal process parameters, (Cyanide: ammonium salt added on the pretreated alkali, sodium cyanide concentration being 0.15 mol/L, pH value being 11, liquid-solid rate 2∶1, mixing strength 500 r/min, leaching time 48 h; Thiosulfate: oxidizing roasting pretreatment, ammonia concentration of 1.0 mol/L, copper sulfate concentration of 0.01 mol/L, sodium thiosulfate concentration of 0.2 mol/L, pH of 10, liquid-solid rate of 4∶1, mixing strength of 500 r/min, leaching time of 12 h;Thiourea:oxidizing roasting and then dilute sulphuric pretreatment acid pre-leaching, Fe3+ concentration of 7.5 ×10-3 mol/L, thiourea concentration of 0.18 mol/L, pH of 1.0, liquid-solid rate of 3∶1, mixing strength of 250 r/min, leaching time of 24 h], the leaching rate of Ag with the method of thiosulfate is 78.58 %, while the rate in the thiourea

  17. 硫代硫酸钠-铁氰化钾体系提取含金物料中金银的研究%Silver Leaching with the Thiosulfate-potassium Ferricyanide Alternative System

    Institute of Scientific and Technical Information of China (English)

    肖力; 吕翠翠; 王永良; 叶树峰

    2016-01-01

    The leaching of silver with the environmental effective sodium thiosulfate-potassium ferricyanide-sodium ferrocyanide alternative system has been studied.The thiosulfate leaching system was used to replace the widely-used cyanide.In this new thiosulfate leaching system,the more stable potassium ferricyanide was used to replace the traditional tetra-amine copper as oxidant.The effect of thiosulfate concentration,ratio of ferricyanide to ferrocyanide, pH,and temperature on silver leaching has been investigated.The results showed that this leaching system was quietly efficient to the dissolution of silver,the silver leaching rate was extremely fast when the ferricyanide acted as oxidation in the initial stage.After the complete consumption of potassium ferricyanide,silver dissolution was driven by oxygen and leaching rate decreased.A high silver leaching rate could be achieved in the case of a slight excess of lixiviant.In the leaching of sulfuric acid residue,leaching conditions were 0.05 M Na2S2O3·5H2O,1 mM K3Fe(CN)6,at pH=7,the extraction rate of gold and silver were 88% and 92% respectively after a leaching time of 48 hours.%研究采用一种环保、高效的硫代硫酸盐—铁氰化钾体系替代广泛使用的氰化法提取物料中的金银。在这种新的硫代硫酸盐体系中,利用更加稳定的 K3Fe(CN)6替代传统的四氨合铜作为氧化剂。考察了硫代硫酸盐浓度、K3Fe(CN)6浓度以及溶液的初始 pH 值对浸出效果的影响。实验证明,这种新的体系能够快速有效地溶解金银,反应初始阶段铁氰化钾作氧化剂时,银的溶解速度非常快,铁氰化钾消耗完之后,银的溶解机理转变为氧气驱动的过程,此时银的溶解速率下降较多。该体系在浸出剂略微过量的情况下即可实现对金银的有效浸出。将该体系用于硫酸渣中金银的提取,在浸出条件为:0.05 M 五水合硫代硫酸钠、1 mM 铁氰化钾、pH=8时,浸出48 h

  18. Effects of Sodium Thiosulfate and Sodium Sulfide on the Corrosion Behavior of Carbon Steel in an MDEA-Based CO2 Capture Process

    Science.gov (United States)

    Emori, W.; Jiang, S. L.; Duan, D. L.; Zheng, Y. G.

    2016-12-01

    The corrosion behavior of carbon steel has been tested in the presence of sodium thiosulfate and sodium sulfide in an MDEA-based CO2 capture system using electrochemical methods, weight loss measurements and surface analysis. The results of electrochemical measurements revealed that both thiosulfate and sulfide showed corrosion resistance properties to carbon steel corrosion. The corrosion resistance for the system with thiosulfate increased with concentration, while the system with sulfide yielded better corrosion resistance to carbon steel at lower concentrations as increase in sulfide concentration decreased the corrosion resistance. The corrosion inhibition behaviors for both systems at 0.05 M salt concentrations were confirmed by weight loss measurement, and the solution with sodium sulfide exhibited a better inhibition with time.

  19. Effects of Sodium Thiosulfate and Sodium Sulfide on the Corrosion Behavior of Carbon Steel in an MDEA-Based CO2 Capture Process

    Science.gov (United States)

    Emori, W.; Jiang, S. L.; Duan, D. L.; Zheng, Y. G.

    2017-01-01

    The corrosion behavior of carbon steel has been tested in the presence of sodium thiosulfate and sodium sulfide in an MDEA-based CO2 capture system using electrochemical methods, weight loss measurements and surface analysis. The results of electrochemical measurements revealed that both thiosulfate and sulfide showed corrosion resistance properties to carbon steel corrosion. The corrosion resistance for the system with thiosulfate increased with concentration, while the system with sulfide yielded better corrosion resistance to carbon steel at lower concentrations as increase in sulfide concentration decreased the corrosion resistance. The corrosion inhibition behaviors for both systems at 0.05 M salt concentrations were confirmed by weight loss measurement, and the solution with sodium sulfide exhibited a better inhibition with time.

  20. Isolation of a Sulfur-oxidizing Bacterium That can Grow under Alkaline pH, from Corroded Concrete.

    Science.gov (United States)

    Maeda, T; Negishi, A; Oshima, Y; Nogami, Y; Kamimura, K; Sugio, T

    1998-01-01

    To study the early stages of concrete corrosion by bacteria, sulfur-oxidizing bacterium strain RO-1, which grows in an alkaline thiosulfate medium (pH 10.0) was isolated from corroded concreate and characterized. Strain RO-1 was a Gram negative, rod-shaped bacterium (0.5-0.6×0.9-1.5 μm). The mean G+C content of the DNA of strain RO-1 was 65.0 mol%. Optimum pH and temperature for growth were 8.0. and 30-37°C, respectively. When grown in thiosulfate medium with pH 10.0, growth rate of the strain was 48% of that observed at the optimum pH for growth. Strain RO-1 used sulfide, thiosulfate, and glucose, but not elemental sulfur or tetrathionate, as a sole energy source. Strain RO-1 grew under anaerobic conditions in pepton-NO3 (-) medium containing sodium nitrate as an electron acceptor, and had enzyme activities that oxidized sulfide, elemental sulfur, thiosulfate, sulfite, and glucose, but not tetrathionate. The bacterium had an activity to assimilate (14)CO2 into the cells when thiosulfate was used as an energy source. These results suggest that strain RO-1 is Thiobacillus versutus. Strain RO-1 exuded Ca(2+) from concrete blocks added to thiosulfate medium with pH 9.0 and the pH of the medium decreased from 9.0 to 5.5 after 22 days of cultivation. In contrast, Thiobacillus thiooxidans strain NB1-3 could not exude Ca(2+) in the same thiosulfate medium, suggesting that strain RO-1, but not T. thiooxidans NB1-3, is involved in the early stage of concrete corrosion because concrete structures just after construction contain calcium hydroxide and have a pH of 12-13.

  1. The Genome of Nitrospina gracilis Illuminates the Metabolism and Evolution of the Major Marine Nitrite Oxidizer

    OpenAIRE

    2013-01-01

    In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this orga...

  2. The genome of Nitrospina gracilis illuminates the metabolism and evolution of the major marine nitrite oxidizer

    OpenAIRE

    2013-01-01

    In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this orga...

  3. Carbon isotope fractionation by the marine ammonia-oxidizing archaeon Nitrosopumilus maritimus

    OpenAIRE

    Könneke, Martin; Lipp, Julius Sebastian; Hinrichs, Kai-Uwe

    2012-01-01

    Abstract Ammonia-oxidizing archaea (AOA) are abundant and widely distributed microorganisms in aquatic and terrestrial habitats. By catalyzing the first and rate limiting step in nitrification, these chemolithoautotrophs play a significant role in the global nitrogen cycle and contribute to primary production. Here, the carbon isotopic fractionation relative to inorganic carbon source was determined for bulk biomass, biphytanes and polar lipid bound sugars of a marine AOA pure culture. Bu...

  4. [Effect of sodium thiosulfate on coronary artery calcification in maintenance hemodialysis patients].

    Science.gov (United States)

    Yu, Y; Bi, Z M; Wang, Y; Chen, Z Q; Xu, S W

    2016-12-13

    Objective: To investigate the factors correlated to coronary artery calcification (CAC)in maintenance hemodialysis (MHD) patients and observe the effect of sodium thiosulfate (STS) on the progression of vascular calcification and its safety. Methods: Thirty-eight subjects from Fuzhou Genernal Hospital who underwent coronary artery CT scan using Philip's spiral CT were enrolled and the calcification degree was evaluated by CAC scores from December 2013 to December 2014. The hemodialysis patients were divided into CAC group (CAC scores>10, 27 cases) and non-CAC group (CAC scores≤10, 11 cases)according to the CT scan results.The differences of age, duration of dialysis, blood pressure and other hematological indices between the two groups were analyzed to investigate the factors correlated to CAC. Next, those with CAC (CAC scores≥50) received intravenous 0.18 g/kg STS (dissolved in 100 ml saline) in 30 minutes after each dialysis for 3 months (n=17, only 15 patients completed STS treatment) or received conventional treatment (n=10). Baseline data between the two groups before treatment had no significant statistical difference. All examination indices were evaluated before and after the treatment course. The changes of vascular calcification imaging, CAC scores, biochemical indices and bone mineral density were compared between two groups before and after the treatment. Besides, adverse reactions were observed during the treatment of STS. This study was approved by the Ethics Committee of Fuzhou General Hospital(2013No1). Results: Twenty-seven out of 38 patients (71.05%) had CAC, and the patients with CAC had significantly higher age, phosphate, the product of calcium and phosphate, intact parathyroid hormone (hPTH), hypersensitive C-reactive protein (hsCRP), and longer duration of dialysis (P=0.017, 0.038, 0.037, 0.012, 0.002, 0.037) and lower serum albumin (P=0.026) than patients without CAC.There was no significant statistical difference in the baseline

  5. Possibly enhanced Gd-excretion in dialysate, but no clinical benefit of 3-5 months treatment with sodium thiosulfate in nephrogenic systemic fibrosis

    DEFF Research Database (Denmark)

    Marckmann, P.; Nielsen, A.H.; Sloth, Jens Jørgen

    2008-01-01

    motion and skin abnormalities. The dialysate Gd content was raised by the treatment, up to fivefold. Conclusions. We could not confirm that sodium thiosulfate treatment results in marked and rapid improvement in late stages of Gd-related nephrogenic systemic fibrosis. However, dialysate contents of Gd...

  6. Possibly enhanced Gd excretion in dialysate, but no major clinical benefit of 3-5 months of treatment with sodium thiosulfate in late stages of nephrogenic systemic fibrosis

    DEFF Research Database (Denmark)

    Marckmann, P.; Sloth, J.J.; Nielsen, Arne Høj

    2008-01-01

    motion and skin abnormalities. The dialysate Gd content was raised by the treatment, up to fivefold. Conclusions. We could not confirm that sodium thiosulfate treatment results in marked and rapid improvement in late stages of Gd-related nephrogenic systemic fibrosis. However, dialysate contents of Gd...

  7. Feasibility Study of the Use of Thiosulfate as Extractant Agent in the Electrokinetic Remediation of a Soil Contaminated by Mercury from Almadén

    DEFF Research Database (Denmark)

    Subires-Muñoz, José Diego; García-Rubio, Ana; Vereda-Alonso, Carlos

    2010-01-01

    Natural soils are rather complex, making the predictability of the behavior of some remediation techniques very complicated. In this paper, the remediation of a Hg contaminated soil close to Almadén using a thiosulfate solution as extractant agent is studied. In addition, the use of the BCR...

  8. Complex kinetics of a Landolt-type reaction: the later phase of the thiosulfate-iodate reaction.

    Science.gov (United States)

    Varga, Dénes; Nagypál, István; Horváth, Attila K

    2010-05-13

    The thiosulfate-iodate reaction has been studied spectrophotometrically in slightly acidic medium at 25.0 +/- 0.1 degrees C in acetate/acetic acid buffer by monitoring the absorbance at 468 nm at the isosbestic point of iodine-triiodide ion system. The formation of iodine after the Landolt time follows a rather complex kinetic behavior depending on the pH and on the concentration of the reactants as well. It is shown that the key intermediate of the reaction is I(2)O(2), its equilibrium formation from the well-known Dushman reaction along with their further reactions followed by subsequent reactions of HOI, HIO(2), S(2)O(3)OH(-), and S(2)O(3)I(-) adequately accounts for all the experimentally measured characteristics of the kinetic curves. A 19-step kinetic model is proposed and discussed with 13 fitted and 7 fixed parameters in detail.

  9. [N,N-Bis(2-aminoethylethane-1,2-diamine](ethane-1,2-diaminenickel(II thiosulfate trihydrate

    Directory of Open Access Journals (Sweden)

    Beatrix Seidlhofer

    2012-02-01

    Full Text Available The title compound, [Ni(C2H8N2(C6H18N4]S2O3·3H2O, was accidentally synthesized under solvothermal conditions applying [Ni(en3]Cl2 (en is ethane-1,2-diamine as the Ni source. The asymmetric unit consists of one discrete [Ni(tren(en]2+ complex [tren is N,N-bis(2-aminoethylethane-1,2-diamine] in which the Ni2+ cation is sixfold coordinated within a slightly distorted octahedron, one thiosulfate anion and three water molecules. In the crystal, the complex cations, anions and water molecules are linked by an intricate hydrogen-bonding network. One C atom of the tren ligand, as well as one O atom of a water molecule, are disordered over two sites and were refined using a split model (occupancy ratios = 0.85:15 and 0.60:0.40, respectively.

  10. Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields.

    Science.gov (United States)

    Qin, Ruijun; Gao, Suduan; McDonald, Jason A; Ajwa, Husein; Shem-Tov, Shachar; Sullivan, David A

    2008-06-01

    Plastic tarps are commonly used in raised bed strawberry production to minimize emissions of preplant soil fumigants and are left in place throughout the growing season as part of the standard cultural practices. Soil amendments with chemicals such as thiosulfate (S2O3(2-)) can reduce fumigant emissions. A field study was conducted near Santa Maria, CA to determine the effects of low density polyethylene (LDPE) and virtually impermeable film (VIF) over raised-beds and applying potassium thiosulfate (KTS) in furrows on reducing chloropicrin (CP) emissions from a strawberry field. Four fields (or treatments) were tested with 224 kg ha(-1) CP drip-applied threecm under the soil surface. The CP flux from bed tops and furrows and gas-phase concentrations under the tarps were monitored for five d. The CP emission flux and concentration under tarp were highest immediately following application. Diurnal temperature change affected CP concentration and emission fluxes (higher values during the day and lower at night). Slightly higher CP cumulative emission occurred using LDPE tarp (19%) compared to VIF (17%). Normalized flux (CP emission flux from the beds divided by CP concentration under the tarp) being estimated from field measurement was slightly higher for LDPE than VIF indicating different tarp permeability in the field. Because of extremely low emissions from the furrows (emission loss), KTS application to furrow treatments did not show further emission reductions than non-KTS treatments. This indicates that emission reduction should focus on the tarp above raised-beds when fumigant was drip-applied near bed-surface.

  11. Organization of the human mitochondrial hydrogen sulfide oxidation pathway.

    Science.gov (United States)

    Libiad, Marouane; Yadav, Pramod Kumar; Vitvitsky, Victor; Martinov, Michael; Banerjee, Ruma

    2014-11-07

    Sulfide oxidation is expected to play an important role in cellular switching between low steady-state intracellular hydrogen sulfide levels and the higher concentrations where the physiological effects are elicited. Yet despite its significance, fundamental questions regarding how the sulfide oxidation pathway is wired remain unanswered, and competing proposals exist that diverge at the very first step catalyzed by sulfide quinone oxidoreductase (SQR). We demonstrate that, in addition to sulfite, glutathione functions as a persulfide acceptor for human SQR and that rhodanese preferentially synthesizes rather than utilizes thiosulfate. The kinetic behavior of these enzymes provides compelling evidence for the flow of sulfide via SQR to glutathione persulfide, which is then partitioned to thiosulfate or sulfite. Kinetic simulations at physiologically relevant metabolite concentrations provide additional support for the organizational logic of the sulfide oxidation pathway in which glutathione persulfide is the first intermediate formed.

  12. Experiment Study of the Synthesis of Sodium Thiosulfate under Microwave Irradiation%微波合成硫代硫酸钠实验研究

    Institute of Scientific and Technical Information of China (English)

    杨骏; 胡小莉; 代永锐; 李原芳

    2012-01-01

    The original method of synthesizing sodium thiosulfate described in "Inorganic Synthesis" course has the drawbacks of long reaction time, lots of burner alcohol and low yield. Sometimes, white powders are obtained and no crystal separates out even with the addition of crystal seeds. Herein, we have developed a method for sodium thiosulfate preparation with the help of microwave heating for its features of fast heating, high efficiency and energy conservation. The effects of experimental conditions such as microwave power, reaction time,methods of crystallization and wetting of sulfur powder with ethanol on yield of sodium thiosulfate have been investigated. Therefore, a relatively simple experimental scheme for the "inorganic synthesis" course is recommended for the synthesis of sodium thiosulfate.%大学本科《无机制备》实验课程中硫代硫酸钠的制备方法,反应时间长,灯用酒精耗量大,产率较低,且有时得到的是白色粉状物,加品种也无晶体析出.为此,利用微波加热均匀、快速、高效节能等特点来制备硫代硫酸钠.研究了微波功率、反应时间、结晶的方法、硫粉是否用乙醇润湿等实验条件对硫代硫酸钠产率的影响,为大学本科学生《无机制备》实验课程开设该实验提供了一套较为成熟的实验方案.

  13. Remediation of Cr(VI) contaminated soil using long-duration sodium thiosulfate supported by micro–nano networks

    Energy Technology Data Exchange (ETDEWEB)

    He, Lulu [School of Life Sciences, Anhui Agricultural University, Hefei 230036 (China); Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Wang, Min; Zhang, Guilong [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Qiu, Guannan [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Cai, Dongqing, E-mail: dqcai@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Zhang, Xin, E-mail: xinzhang@ahau.edu.cn [School of Life Sciences, Anhui Agricultural University, Hefei 230036 (China)

    2015-08-30

    Highlights: • This work aims to develop a long-duration remediation agent (LRA). • LRA was obtained using Na{sub 2}S{sub 2}O{sub 3} supported by attapulgite (ATP) micro–nano networks. • ATP micro–nano networks was induced by high-energy electron beam irradiation. • LRA can effectively control the migration of Cr(VI) and reducing Cr(VI) to Cr(III). • LRA displayed high performance on the remediation of heavy metal contaminated soil. - Abstract: In this work, a long-duration remediation agent (LRA) on hexavalent chromium (Cr(VI)) was developed using sodium thiosulfate (ST) supported by attapulgite (ATP) micro–nano networks induced through high-energy electron beam (HEEB) irradiation. The ATP networks could effectively reduce the leaching amount of Cr(VI) in soil. More importantly, the ATP networks could significantly control the leaching behavior of ST, and then prolong the duration and increase the reduction efficiency of ST on Cr(VI). As a result, LRA displayed high performance on controlling the migration of Cr(VI) and reducing Cr(VI) to Cr(III). Additionally, pot experiment indicated that LRA could effectively decrease the absorbed amount of Cr(VI) in corn, and reduce the inhibition effect of Cr(VI) on the growth of corn. Therefore, this work could provide a facile approach to remediate the Cr(VI)-contaminated soil and lower the harmful effect of Cr(VI) on crop.

  14. Anodic dissolution of gold in alkaline solutions containing thiourea, thiosulfate and sulfite ions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Gold dissolves electrochemically in alkaline solutions containing ligands to form complex ions with gold ion. Therefore, selective leaching of noble metals is expected without dissolution of base metals such as steels, aluminum alloys in scrap treatment. Gold electrodes were investigated using linear sweep voltammetry, EQCM method and potentiostatic electrolysis in alkaline solutions containing thiourea, Na2SO3 and Na2S2O3. The solution composition, electrode potential affect gold dissolution rate and current efficiency. The gold dissolved from anode electrode forms complex ions, suspension particles as compound precipitates and deposits on cathode electrode as a metal. Anodic efficiency for gold dissolution is between 10% and 22%. This is caused by the oxidation decomposition of sulfite ions and thiourea. The stability of the alkaline solution containing these elements was also estimated by capillary electrophoresis technique.

  15. Complete genome sequence of Nitrosomonas sp. Is79, an ammonia oxidizing bacterium adapted to low ammonium concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Bollmann, Annette [Miami University, Oxford, OH; Sedlacek, Christopher J [Miami University, Oxford, OH; Laanbroek, Hendrikus J [Netherlands Institute of Ecology (NIOO-KNAW); Suwa, Yuichi [Chuo University, Tokyo, Japan; Stein, Lisa Y [University of California, Riverside; Klotz, Martin G [University of Louisville, Louisville; Arp, D J [Oregon State University; Sayavedra-Soto, LA [Oregon State University; Lu, Megan [Los Alamos National Laboratory (LANL); Bruce, David [Los Alamos National Laboratory (LANL); Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Tapia, Roxanne [Los Alamos National Laboratory (LANL); Han, James [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Pennacchio, Len [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Huntemann, Marcel [U.S. Department of Energy, Joint Genome Institute; Deshpande, Shweta [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Chen, Amy [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Szeto, Ernest [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Pagani, Ioanna [U.S. Department of Energy, Joint Genome Institute; Pati, Amrita [U.S. Department of Energy, Joint Genome Institute; Peters, Lin [U.S. Department of Energy, Joint Genome Institute; Ovchinnikova, Galina [U.S. Department of Energy, Joint Genome Institute; Goodwin, Lynne A. [Los Alamos National Laboratory (LANL)

    2013-01-01

    Nitrosomonas sp. Is79 is a chemolithoautotrophic ammonia-oxidizing bacterium that belongs to the family Nitrosomonadaceae within the phylum Proteobacteria. Ammonia oxidation is the first step of nitrification, an important process in the global nitrogen cycle ultimately resulting in the production of nitrate. Nitrosomonas sp. Is79 is an ammonia oxidizer of high interest because it is adapted to low ammonium and can be found in freshwater environments around the world. The 3,783,444-bp chromosome with a total of 3,553 protein coding genes and 44 RNA genes was sequenced by the DOE-Joint Genome Institute Program CSP 2006.

  16. Wet-air oxidation cleans up black wastewater

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    Sterling Organics produces the analgesic paracetamol (acetaminophen) at its Dudley, England, plant. The wastewater from the batch process contains intermediates such as para-aminophenol (PAP) and byproducts such as thiosulfates, sulfites and sulfides. To stay ahead of increasingly strict environmental legislation, Sterling Organics installed a wet-air oxidation system at the Dudley facility in August 1992. The system is made by Zimpro Environmental Inc. (Rothschild, Wis.). Zimpro's wet-air oxidation system finds a way around the limitations of purely chemical or physical processes. In the process, compressed air at elevated temperature and pressure oxidizes the process intermediates and byproducts and removes the color from the wastewater.

  17. 硫代硫酸钠对涤纶织物化学镀银的影响%Influences of sodium thiosulfate on electroless silver plating on PET fabrics

    Institute of Scientific and Technical Information of China (English)

    徐文龙; 熊杰; 徐勤; 刘志才; 焦玉雪; 陈虎

    2011-01-01

    研究硫代硫酸钠对化学镀银镀液稳定性、镀层表面形貌、镀层成分、结晶情况、镀银速率、表面电阻以及电磁屏蔽效能的影响.结果表明:添加硫代硫酸钠能使镀液的稳定性得到明显提高,但若浓度过高,会出现镀层结构疏松的现象;镀层中银的结晶形态是立方面心(fcc)结构,晶粒尺寸随硫代硫酸钠浓度的增加而减小;硫代硫酸钠的加入使镀银速率下降,但速率对温度的敏感性增加,当硫代硫酸钠质量浓度增大到0.6 mg/L时,会使镀银速率大幅降低,对化学镀银带来不利影响;当硫代硫酸钠质量浓度在0.4 mg/L以内,对织物的表面电阻和电磁屏蔽效能影响不大.%The influences of sodium thiosulfate on the stability of plating solution, surface morphology, chemical composition, crystal structure, deposition rate, surface resistance and electromagnetic interference shielding effectiveness (EMI SE) of the silver coated fabric were investigated. The results revealed that the stability of plating solution was significantly improved with addition of sodium thiosulfate. But high concentration of sodium thiosulfate leads to loose deposited layer. The crystalline structure of silver in deposit is of face centered cubic (fee) structure. The grain size decreases with the increase of the concentration of sodium thiosulfate. The deposition rate decreases with the addition of sodium thiosulfate. However, the sensitivity of deposition rate on temperature increases in the presence of sodium thiosulfate. The deposition rate greatly decreases and it will bring above adverse effect on electroless silver plating when the concentration of sodium thiosulfate is higher than 0. 6 mg/L. Surface resistance and electromagnetic interference shielding effectiveness had no significant change when the concentration of sodium thiosulfate is lower than 0. 4 mg/L.

  18. Effects of inhibitors and NaCl on the oxidation of reduced inorganic sulfur compounds by a marine acidophilic, sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH.

    Science.gov (United States)

    Kamimura, Kazuo; Higashino, Emi; Kanao, Tadayoshi; Sugio, Tsuyoshi

    2005-02-01

    The effect of NaCl and the pathways of the oxidation of reduced inorganic sulfur compounds were studied using resting cells and cell-free extracts of Acidithiobacillus thiooxidans strain SH. This isolate specifically requires NaCl for growth. The oxidation of sulfur and sulfite by resting cells was strongly inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide. Carbonylcyanide m-chlorophenyl-hydrazone and monensin were also relatively strong inhibitors. Thiosulfate-oxidizing activity was not inhibited by these uncouplers. Valinomycin did not inhibit the oxidation of sulfur compounds. NaCl stimulated the sulfur- and sulfite-oxidizing activities in resting cells but not in cell-free extracts. The tetrathionate-oxidizing activity in resting cells was slightly stimulated by NaCl, whereas it did not influence the thiosulfate-oxidizing activity. Sulfide oxidation was biphasic, suggesting the formation of intermediate sulfur. The initial phase of sulfide oxidation was not affected by NaCl, whereas the subsequent oxidation of sulfur in the second phase was Na+-dependent. A model is proposed for the role of NaCl in the metabolism of reduced sulfur compounds in A. thiooxidans strain SH.

  19. Mechanisms and evolution of oxidative sulfur metabolism in green sulfur bacteria

    DEFF Research Database (Denmark)

    Gregersen, Lea Haarup; Bryant, Donald A.; Frigaard, Niels-Ulrik

    2011-01-01

    Green sulfur bacteria (GSB) constitute a closely related group of photoautotrophic and thiotrophic bacteria with limited phenotypic variation. They typically oxidize sulfide and thiosulfate to sulfate with sulfur globules as an intermediate. Based on genome sequence information from 15 strains......, the distribution and phylogeny of enzymes involved in their oxidative sulfur metabolism was investigated. At least one homolog of sulfide:quinone oxidoreductase (SQR) is present in all strains. In all sulfur-oxidizing GSB strains except the earliest diverging Chloroherpeton thalassium, the sulfide oxidation...... and SOX systems. Finally, based upon structural, biochemical, and phylogenetic analyses, a uniform nomenclature is suggested for sqr genes in prokaryotes....

  20. Dethiosulfatibacter aminovorans gen. nov., sp. nov., a novel thiosulfate-reducing bacterium isolated from coastal marine sediment via sulfate-reducing enrichment with Casamino acids.

    Science.gov (United States)

    Takii, Susumu; Hanada, Satoshi; Tamaki, Hideyuki; Ueno, Yutaka; Sekiguchi, Yuji; Ibe, Akihiro; Matsuura, Katsumi

    2007-10-01

    A sulfate-reducing enrichment culture originating from coastal marine sediment of the eutrophic Tokyo Bay, Japan, was successfully established with Casamino acids as a substrate. A thiosulfate reducer, strain C/G2(T), was isolated from the enrichment culture after further enrichment with glutamate. Cells of strain C/G2(T) were non-motile rods (0.6-0.8 microm x 2.2-4.8 microm) and were found singly or in pairs and sometimes in short chains. Spores were not formed. Cells of strain C/G2(T) stained Gram-negatively, despite possessing Gram-positive cell walls. The optimum temperature for growth was 28-30 degrees C, the optimum pH was around 7.8 and the optimum salt concentration was 20-30 g l(-1). Lactate, pyruvate, serine, cysteine, threonine, glutamate, histidine, lysine, arginine, Casamino acids, peptone and yeast extract were fermented as single substrates and no sugar was used as a fermentative substrate. A Stickland reaction was observed with some pairs of amino acids. Fumarate, alanine, proline, phenylalanine, tryptophan, glutamine and aspartate were utilized only in the presence of thiosulfate. Strain C/G2(T) fermented glutamate to H2, CO2, acetate and propionate. Thiosulfate and elemental sulfur were reduced to sulfide. Sulfate, sulfite and nitrate were not utilized as electron acceptors. The growth of strain C/G2(T) on Casamino acids or glutamate was enhanced by co-culturing with Desulfovibrio sp. isolated from the original mixed culture enriched with Casamino acids. The DNA G+C content of strain C/G2(T) was 41.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain C/G2(T) formed a distinct cluster with species of the genus Sedimentibacter. The closest relative was Sedimentibacter hydroxybenzoicus (with a gene sequence similarity of 91 %). On the basis of its phylogenetic and phenotypic properties, strain C/G2(T) (=JCM 13356(T)=NBRC 101112(T)=DSM 17477(T)) is proposed as representing a new genus and novel species, Dethiosulfatibacter

  1. Vascular ossification – calcification in metabolic syndrome, type 2 diabetes mellitus, chronic kidney disease, and calciphylaxis – calcific uremic arteriolopathy: the emerging role of sodium thiosulfate

    Directory of Open Access Journals (Sweden)

    Sowers James R

    2005-03-01

    Full Text Available Abstract Background Vascular calcification is associated with metabolic syndrome, diabetes, hypertension, atherosclerosis, chronic kidney disease, and end stage renal disease. Each of the above contributes to an accelerated and premature demise primarily due to cardiovascular disease. The above conditions are associated with multiple metabolic toxicities resulting in an increase in reactive oxygen species to the arterial vessel wall, which results in a response to injury wound healing (remodeling. The endothelium seems to be at the very center of these disease processes, acting as the first line of defense against these multiple metabolic toxicities and the first to encounter their damaging effects to the arterial vessel wall. Results The pathobiomolecular mechanisms of vascular calcification are presented in order to provide the clinician – researcher a database of knowledge to assist in the clinical management of these high-risk patients and examine newer therapies. Calciphylaxis is associated with medial arteriolar vascular calcification and results in ischemic subcutaneous necrosis with vulnerable skin ulcerations and high mortality. Recently, this clinical syndrome (once thought to be rare is presenting with increasing frequency. Consequently, newer therapeutic modalities need to be explored. Intravenous sodium thiosulfate is currently used as an antidote for the treatment of cyanide poisioning and prevention of toxicities of cisplatin cancer therapies. It is used as a food and medicinal preservative and topically used as an antifungal medication. Conclusion A discussion of sodium thiosulfate's dual role as a potent antioxidant and chelator of calcium is presented in order to better understand its role as an emerging novel therapy for the clinical syndrome of calciphylaxis and its complications.

  2. Sulfur globule oxidation in green sulfur bacteria is dependent on the dissimilatory sulfite reductase system

    DEFF Research Database (Denmark)

    Holkenbrink, Carina; Ocón Barbas, Santiago; Mellerup, Anders;

    2011-01-01

    Green sulfur bacteria oxidize sulfide and thiosulfate to sulfate with extracellular globules of elemental sulfur as intermediate. Here we investigated which genes are involved in the formation and consumption of these sulfur globules in the green sulfur bacterium Chlorobaculum tepidum. We show...... that sulfur globule oxidation is strictly dependent on the dissimilatory sulfite reductase (DSR) system. Deletion of dsrM/CT2244 or dsrT/CT2245 or the two dsrCABL clusters (CT0851-CT0854, CT2247-2250) abolished sulfur globule oxidation and prevented formation of sulfate from sulfide, whereas deletion of dsr...

  3. Oxidation of Elemental Sulfur in Selected Soils of China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An incubation experiment was carried out in laboratory to study the effect of temperature, moisture,phosphorus, organic matter, cropping and previous elemental sulfur application on elemental sulfur oxidation in four selected soils, fluvo-aquic soil, black soil, yellow-brown soil and red soil. In all the soils tested, sulfur oxidation rate was influenced by temperature and the temperature coefficient (Q10) values at the range from 10to 30 ℃ were 4.41, 4.05, 6.19 and 3.71 for the four soils, respectively. The rate of sulfur oxidation was parabolically related to soil water content. The optimum moisture content for the maximum oxidation rate was different among soils. Phosphorus increased the oxidation rate of elemental sulfur by 57.7%, 33.1%, 21.7% and 26.4% for the above four soils, respectively, compared with the control (no phosphorus applied). Organic material of corn straw which was ground and passed through a 0.5-mm sieve also increased the oxidation rate of elemental sulfur in the four soils by 59.8%, 7.8%, 39.2% and 540.4%, respectively. Elemental sulfur which was applied previously to soils significantly enhanced the oxidation of elemental sulfur subsequently added and increased sulfur-oxidizing populations such as autotrophic elemental sulfur oxidizers with pH optimum 6.8, autotrophic thiosulfate oxidizers with pH optimum 6.8, heterotrophic thiosulfate oxidizers and heterotrophic sulfate producers. Cropping had little effect on lemental sulfur-oxidizing potentiality of soils.

  4. Sulfite oxidation in Sinorhizobium meliloti.

    Science.gov (United States)

    Wilson, Jeremy J; Kappler, Ulrike

    2009-12-01

    Sulfite-oxidizing enzymes (SOEs) are crucial for the metabolism of many cells and are particularly important in bacteria oxidizing inorganic or organic sulfur compounds. However, little is known about SOE diversity and metabolic roles. Sinorhizobium meliloti contains four candidate genes encoding SOEs of three different types, and in this work we have investigated the role of SOEs in S. meliloti and their possible link to the metabolism of the organosulfonate taurine. Low level SOE activity (approximately 1.4 U/mg) was present under all conditions tested while growth on taurine and thiosulfate induced high activities (5.5-8.8 U/mg) although S. meliloti cannot metabolize thiosulfate. Protein purification showed that although expression of two candidate genes matched SOE activity patterns, only a single group 2 SOE, SorT (SMc04049), is responsible for this activity. SorT is a heme-free, periplasmic homodimer (78 kDa) that has low homology to other bacterial SOEs. SorT has an apparent k(cat) of 343 s(-1) and high affinities for both sulfite (K(Mapp_pH8) 15.5 microM) and ferricyanide (K(Mapp_pH8) 3.44 microM), but not cytochrome c, suggesting a need for a high redox potential natural electron acceptor. K(Mapp_sulfite) was nearly invariant with pH which is in contrast to all other well characterized SOEs. SorT is part of an operon (SMc04049-04047) also containing a gene for a cytochrome c and an azurin, and these might be the natural electron acceptors for the enzyme. Phylogenetic analysis of SorT-related SOEs and enzymes of taurine degradation indicate that there is no link between the two processes.

  5. Radioprotective Effect of Alk(enyl Thiosulfates Derived from Allium Vegetables against DNA Damage Caused by X-Ray Irradiation in Cultured Cells: Antiradiation Potential of Onions and Garlic

    Directory of Open Access Journals (Sweden)

    Hye-Sook Chang

    2012-01-01

    Full Text Available To evaluate a radioprotective effect of sodium n-propyl thiosulfate (NPTS and sodium 2-propenyl thiosulfate (2PTS derived from onions and garlic, respectively, rat hepatoma H4IIE cells and mouse lymphoma L5178Y cells were preincubated with each of these compounds for 48 hours at 37°C before receiving 10 Gy of X-ray irradiation. Cell damage caused by the irradiation was quantified as comet tail moment, which represents the degree of DNA damage. X-ray-induced DNA damage was significantly decreased in both H4IIE and L5178Y cells by micromolar concentrations of NPTS and 2PTS compared with the control without the compounds. The protective effect was more potent with 2PTS than NPTS. Onions and garlic have antiradiation potential.

  6. 预浮选-硫代硫酸钠浸金试验研究%The study on gold leaching with preflotation-sodium thiosulfate process

    Institute of Scientific and Technical Information of China (English)

    张开永; 刘渝燕; 张军

    2013-01-01

    Based on the analysis of ore ore properties, the author studied the gold leaching using preflotation-sodium thiosulfate flowsheet. Flotation reagents for sodium silicate, sodium sulfide, butyl xanthate,pine oil were 1800g/t,40g/t,80g/t,24g/t with one roughing and one scavenging. With preleaching (4h)-leaching (24 h)-five times washing process, normal temperature and pressure, slurry concentration 33% ,0. l0kg/t protective agent,sodium thiosulfate l0kg/t,additive concentration 0. 76%o>ammonia 1. 27%, lime 2kg/t,the final recovery rate of gold was more than 86%. This method was not only small toxicity, green environmental protection, but also provided technology feasible, economically reasonable process and conditions for the gold pilot recovery.%通过对某矿原矿矿石性质的分析,采用预浮选—硫代硫酸盐法进行浸金工艺试验研究.浮选采用一粗一精浮选流程,药剂用量为硅酸钠1800g/t,硫化钠40g/t,丁基黄药80g/t,松油24g/t.浸出采用预浸(4h)-浸出(24h)-五次洗涤流程,常温常压、矿浆浓度33%、保护剂0.10kg/t、硫代硫酸钠10kg/t、助剂浓度0.76‰、氨水1.27%、石灰用量2kg/t,最终金浸出率达到86%以上.采用该法不仅毒性小,绿色环保,而且为金的中试回收提供了技术可行、经济合理的工艺流程和条件.

  7. Conifer somatic embryogenesis: improvements by supplementation of medium with oxidation-reduction agents.

    Science.gov (United States)

    Pullman, Gerald S; Zeng, Xiaoyan; Copeland-Kamp, Brandi; Crockett, Jonathan; Lucrezi, Jacob; May, Sheldon W; Bucalo, Kylie

    2015-02-01

    A major barrier to the commercialization of somatic embryogenesis technology in loblolly pine (Pinus taeda L.) is recalcitrance of some high-value crosses to initiate embryogenic tissue (ET) and continue early-stage somatic embryo growth. Developing initiation and multiplication media that resemble the seed environment has been shown to decrease this recalcitrance. Glutathione (GSH), glutathione disulfide (GSSG), ascorbic acid and dehydroascorbate analyses were performed weekly throughout the sequence of seed development for female gametophyte and zygotic embryo tissues to determine physiological concentrations. Major differences in stage-specific oxidation-reduction (redox) agents were observed. A simple bioassay was used to evaluate potential growth-promotion of natural and inorganic redox agents added to early-stage somatic embryo growth medium. Compounds showing statistically significant increases in early-stage embryo growth were then tested for the ability to increase initiation of loblolly pine. Low-cost reducing agents sodium dithionite and sodium thiosulfate increased ET initiation for loblolly pine and Douglas fir (Mirb) Franco. Germination medium supplementation with GSSG increased somatic embryo germination. Early-stage somatic embryos grown on medium with or without sodium thiosulfate did not differ in GSH or GSSG content, suggesting that sodium thiosulfate-mediated growth stimulation does not involve GSH or GSSG. We have developed information demonstrating that alteration of the redox environment in vitro can improve ET initiation, early-stage embryo development and somatic embryo germination in loblolly pine.

  8. Effect of mitochondrial potassium channel on the renal protection mediated by sodium thiosulfate against ethylene glycol induced nephrolithiasis in rat model

    Directory of Open Access Journals (Sweden)

    N. Baldev

    2015-12-01

    Full Text Available Purpose: Sodium thiosulfate (STS is clinically reported to be a promising drug in preventing nephrolithiasis. However, its mechanism of action remains unclear. In the present study, we investigated the role of mitochondrial KATP channel in the renal protection mediated by STS. Materials and Methods: Nephrolithiasis was induced in Wistar rats by administrating 0.4% ethylene glycol (EG along with 1% ammonium chloride for one week in drinking water followed by only 0.75% EG for two weeks. Treatment groups received STS, mitochondrial KATP channel opener and closer exclusively or in combination with STS for two weeks. Results: Animals treated with STS showed normal renal tissue architecture, supported by near normal serum creatinine, urea and ALP activity. Diazoxide (mitochondria KATP channel opening treatment to the animal also showed normal renal tissue histology and improved serum chemistry. However, an opposite result was shown by glibenclamide (mitochondria KATP channel closer treated rats. STS administered along with diazoxide negated the renal protection rendered by diazoxide alone, while it imparted protection to the glibenclamide treated rats, formulating a mitochondria modulated STS action. Conclusion: The present study confirmed that STS render renal protection not only through chelation and antioxidant effect but also by modulating the mitochondrial KATP channel for preventing urolithiasis.

  9. 硫代硫酸根插层水滑石的层间限域反应%Interlayer Reaction of Thiosulfate in a Confined Region of Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    王力耕; 袁庭; 李远; 施炜; 倪哲明

    2012-01-01

    将无机阴离子硫代硫酸根(S2O2-3)限域在锌铝水滑石(LDH)层间,并研究了其在水滑石层板限域空间内被铁氰根(Fe(CN)3-6)氧化的反应过程.通过X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱仪对反应的中间产物和最终产物进行的表征发现,氧化产物连四硫酸根(S4O2-6)进入到溶液中,还原产物亚铁氰根(Fe(CN)4-6)则保留在水滑石层间.进一步系统研究了该反应的动力学过程,考察了硫代硫酸根插层水滑石用量、铁氰化钾浓度和温度对反应的影响.结果表明该氧化还原反应符合球体内扩散模型.根据温度对反应速率影响,得出了该反应的表观活化能为24.6 kJ·mol-1,比相同条件下溶液中反应活化能降低了约13.7 kJ·mol-1.采用分子动力学(MD)模拟计算了水分子含量对硫代硫酸根插层水滑石层间距大小的影响.计算表明:在水溶液环境中,水滑石微反应器的尺寸在特定方向具有可调控性.根据实验表征和理论计算对该层间反应的机理进行了探讨.因此,该类层状材料可以作为一种新型纳米级微反应器应用于调控化学反应.%The thiosulfate anion (S2O3") was intercalated into a ZnAI layered double hydroxide (LDH), and its oxidation reaction with hexacyanoferrate(lll) (Fe(CN)e') in the confined region between the layers of LDH has been discussed. Based measurements of the intermediate state and final product using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the oxidation product tetrathionate (Soxidation reaction were studied. The reaction follows a diffusion-controlled process represented by Crank-Ginstling and

  10. A pilot study of the effect of sodium thiosulfate on urinary lithogenicity and associated metabolic acid load in non-stone formers and stone formers with hypercalciuria.

    Directory of Open Access Journals (Sweden)

    Onyeka W Okonkwo

    Full Text Available BACKGROUND AND OBJECTIVES: Sodium thiosulfate (STS reduced calcium stone formation in both humans and genetic hypercalciuric stone forming (GHS rats. We sought to measure urine chemistry changes resulting from STS administration in people. DESIGN SETTING PARTICIPANTS MEASUREMENTS: STS was given to healthy and hypercalciuric stone forming adults. Five normal non-stone forming adults (mean age 33 years, and 5 people with idiopathic hypercalciuria and calcium kidney stones (mean age 66 years participated. Two baseline 24-hour urine collections were performed on days 2 and 3 of 3 days of self-selected diets. Subjects then drank STS 10 mmol twice a day for 7 days and did urine collections while repeating the self-selected diet. Results were compared by non-parametric Wilcoxon signed rank test. The primary outcome was the resulting change in urine chemistry. RESULTS: STS administration did not cause a significant change in urinary calcium excretion in either group. In both groups, 24 hour urinary ammonium (P = 0.005 and sulfate excretion (P = 0.007 increased, and urinary pH fell (P = 0.005; citrate excretion fell (P<0.05 in hypercalciuric participants but not in non-stone formers. Among stone formers with hypercalciuria, 3 of 5 patients had measurement of serum HCO3 concentration after the STS period: it did not change. The net effect was an increase in supersaturation of uric acid, and no change in supersaturation of calcium oxalate or calcium phosphate. CONCLUSIONS: The basis for studies demonstrating that STS prevented stones in rats and people was not reflected by the changes in urine chemistry reported here. Although serum HCO3 did not change, urine tests suggested an acid load in both non-stone forming and hypercalciuric stone-forming participants. The long term safety of STS needs to be determined before the drug can be tested in humans for long-term prevention of stone recurrence.

  11. Hydrogen and thiosulfate limits for growth of a thermophilic, autotrophic Desulfurobacterium species from a deep-sea hydrothermal vent.

    Science.gov (United States)

    Stewart, Lucy C; Llewellyn, James G; Butterfield, David A; Lilley, Marvin D; Holden, James F

    2016-04-01

    Hydrothermal fluids (341°C and 19°C) were collected < 1 m apart from a black smoker chimney and a tubeworm mound on the Boardwalk edifice at the Endeavour Segment in the northeastern Pacific Ocean to study anaerobic microbial growth in hydrothermal mineral deposits. Geochemical modelling of mixed vent fluid and seawater suggests the mixture was anoxic above 55°C and that low H2 concentrations (79 μmol kg(-1) in end-member hydrothermal fluid) limit anaerobic hydrogenotrophic growth above this temperature. A thermophilic, hydrogenotrophic sulfur reducer, Desulfurobacterium strain HR11, was isolated from the 19°C fluid raising questions about its H2 -dependent growth kinetics. Strain HR11 grew at 40-77°C (Topt 72-75°C), pH 5-8.5 (pHopt 6-7) and 1-5% (wt vol(-1) ) NaCl (NaClopt 3-4%). The highest growth rates occurred when S2 O3 (2-) and S° were reduced to H2 S. Modest growth occurred by NO3 (-) reduction. Monod constants for its growth were Ks of 30 μM for H2 and Ks of 20 μM for S2 O3 (2-) with a μmax of 2.0 h(-1) . The minimum H2 and S2 O3 (2-) concentrations for growth were 3 μM and 5 μM respectively. Possible sources of S2 O3 (2-) and S° are from abiotic dissolved sulfide and pyrite oxidation by O2 .

  12. The genome sequence of Desulfatibacillum alkenivorans AK-01: a blueprint for anaerobic alkane oxidation.

    Science.gov (United States)

    Callaghan, A V; Morris, B E L; Pereira, I A C; McInerney, M J; Austin, R N; Groves, J T; Kukor, J J; Suflita, J M; Young, L Y; Zylstra, G J; Wawrik, B

    2012-01-01

    Desulfatibacillum alkenivorans AK-01 serves as a model organism for anaerobic alkane biodegradation because of its distinctive biochemistry and metabolic versatility. The D. alkenivorans genome provides a blueprint for understanding the genetic systems involved in alkane metabolism including substrate activation, CoA ligation, carbon-skeleton rearrangement and decarboxylation. Genomic analysis suggested a route to regenerate the fumarate needed for alkane activation via methylmalonyl-CoA and predicted the capability for syntrophic alkane metabolism, which was experimentally verified. Pathways involved in the oxidation of alkanes, alcohols, organic acids and n-saturated fatty acids coupled to sulfate reduction and the ability to grow chemolithoautotrophically were predicted. A complement of genes for motility and oxygen detoxification suggests that D. alkenivorans may be physiologically adapted to a wide range of environmental conditions. The D. alkenivorans genome serves as a platform for further study of anaerobic, hydrocarbon-oxidizing microorganisms and their roles in bioremediation, energy recovery and global carbon cycling.

  13. Biogenesis of reactive sulfur species for signaling by hydrogen sulfide oxidation pathways.

    Science.gov (United States)

    Mishanina, Tatiana V; Libiad, Marouane; Banerjee, Ruma

    2015-07-01

    The chemical species involved in H2S signaling remain elusive despite the profound and pleiotropic physiological effects elicited by this molecule. The dominant candidate mechanism for sulfide signaling is persulfidation of target proteins. However, the relatively poor reactivity of H2S toward oxidized thiols, such as disulfides, the low concentration of disulfides in the reducing milieu of the cell and the low steady-state concentration of H2S raise questions about the plausibility of persulfide formation via reaction between an oxidized thiol and a sulfide anion or a reduced thiol and oxidized hydrogen disulfide. In contrast, sulfide oxidation pathways, considered to be primarily mechanisms for disposing of excess sulfide, generate a series of reactive sulfur species, including persulfides, polysulfides and thiosulfate, that could modify target proteins. We posit that sulfide oxidation pathways mediate sulfide signaling and that sulfurtransferases ensure target specificity.

  14. Influence of microstructure in corrosion behavior of an Inconel 600 commercial alloy in 0.1 M sodium thiosulfate solution; Influencia de la microestructura en el comportamiento a la corrosion de una aleacion comercial Inconel 600 en solucion de Tiosulfato de sodio 0.1 M

    Energy Technology Data Exchange (ETDEWEB)

    Granados, J.; Rodriguez, F.J.; Arganis, C. [Facultad de Quimica, UNAM, C.P. 04510 Mexico D.F. (Mexico)

    1999-07-01

    The Inconel 600 is used in diverse components of BWR and PWR type reactors, where diverse cases of intergranular stress corrosion have been presented. It has been reported susceptibility to the corrosion of this alloy, in presence of thiosulfates, which come from the degradation of the ion exchange resins of water treatments that use the reactors. The objective of this work is to study the influence of metallurgical condition in the corrosion velocity of Inconel 600 commercial alloy, in a 0.1 M thiosulfates solution. (Author)

  15. Scientific Opinion on the safety evaluation of the active substances iron, sodium chloride, water, silica gel, activated carbon, monosodium glutamate, potassium acid tartrate, powdered cellulose, malic acid, chabazite, hydroxypropyl cellulose, potassium carbonate, sodium thiosulfate, propylene glycol, glycerin, polyethyleneglycol sorbitan monooleate, sodium propionate and clinoptilolite for use in food contact materials

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2013-04-01

    Full Text Available This scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety evaluation of iron based oxygen absorber systems comprising iron, sodium chloride, water, silica gel, activated carbon, monosodium glutamate, potassium acid tartrate, powdered cellulose, malic acid, chabazite, hydroxypropyl cellulose, potassium carbonate, sodium thiosulfate, propylene glycol, glycerin, polyethyleneglycol sorbitan monooleate, sodium propionate and clinoptilolite, incorporated in sachets, patches and cards. Iron, the main active ingredient reacts with oxygen to form iron hydroxide and iron oxide, thereby removing oxygen from the primary packaging. Only activated carbon has not been evaluated as such, but it meets the specifications for activated charcoal which is authorised as additive for plastic materials and articles in contact with foods. All other ingredients of the oxygen absorber formulations have been evaluated and approved for use as additives in plastic food contact materials and/or as food additives and/or food supplements or feed additives. The active system being based on solid ingredients and not intended for direct contact with liquid food or food with an external liquid surface, migration through the gas phase was screened for 9 representative active systems. No volatiles derived from the active mixtures were detected. Therefore the CEF Panel concluded that the substances do not raise a safety concern when used in oxygen absorbers in sachets, patches or cards, placed in the headspace of the packaging or when used in direct contact with food, excluding liquid food or foods that have an external aqueous liquid phase on the surface such as sliced fruits and fresh meat.

  16. Active ammonia oxidizers in an acidic soil are phylogenetically closely related to neutrophilic archaeon.

    Science.gov (United States)

    Wang, Baozhan; Zheng, Yan; Huang, Rong; Zhou, Xue; Wang, Dongmei; He, Yuanqiu; Jia, Zhongjun

    2014-03-01

    All cultivated ammonia-oxidizing archaea (AOA) within the Nitrososphaera cluster (former soil group 1.1b) are neutrophilic. Molecular surveys also indicate the existence of Nitrososphaera-like phylotypes in acidic soil, but their ecological roles are poorly understood. In this study, we present molecular evidence for the chemolithoautotrophic growth of Nitrososphaera-like AOA in an acidic soil with pH 4.92 using DNA-based stable isotope probing (SIP). Soil microcosm incubations demonstrated that nitrification was stimulated by urea fertilization and accompanied by a significant increase in the abundance of AOA rather than ammonia-oxidizing bacteria (AOB). Real-time PCR analysis of amoA genes as a function of the buoyant density of the DNA gradient following the ultracentrifugation of the total DNA extracted from SIP microcosms indicated a substantial growth of soil AOA during nitrification. Pyrosequencing of the total 16S rRNA genes in the "heavy" DNA fractions suggested that archaeal communities were labeled to a much greater extent than soil AOB. Acetylene inhibition further showed that (13)CO2 assimilation by nitrifying communities depended solely on ammonia oxidation activity, suggesting a chemolithoautotrophic lifestyle. Phylogenetic analysis of both (13)C-labeled amoA and 16S rRNA genes revealed that most of the active AOA were phylogenetically closely related to the neutrophilic strains Nitrososphaera viennensis EN76 and JG1 within the Nitrososphaera cluster. Our results provide strong evidence for the adaptive growth of Nitrososphaera-like AOA in acidic soil, suggesting a greater metabolic versatility of soil AOA than previously appreciated.

  17. Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems.

    Science.gov (United States)

    Chandran, Kartik; Stein, Lisa Y; Klotz, Martin G; van Loosdrecht, Mark C M

    2011-12-01

    Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO₂⁻) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N₂O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O₂) is associated with N₂O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N₂O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N₂O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N₂O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N₂O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

  18. Leaching Gold Using Oxidation Products of Elemental Sulfur in Ca(OH)2 Solution under Oxygen Pressure

    Institute of Scientific and Technical Information of China (English)

    方兆珩; 韩宝玲

    2002-01-01

    A gold leaching process by using in situ oxidation products of added elemental sulfur in Ca(OH)2 solution was investigated. A gold concentrate containing 45 g/t Au was tested and 85%~87% of gold were leached. The leached gold depends mainly on the initial molar ratio of elemental sulfur to the hydroxyl ion, the consumption of oxygen and the reaction temperature. Adding some surfactants, such as lignosulfonic calcium, at lower concentration increased the leached Au but at higher concentration decreased it. Both of thermodynamic analysis and experimental results show that thiosulfate is the major complexing agent for gold in the process.

  19. Mechanisms and evolution of oxidative sulfur metabolism in green sulfur bacteria

    Directory of Open Access Journals (Sweden)

    Lea Haarup Gregersen

    2011-05-01

    Full Text Available Green sulfur bacteria (GSB constitute a closely related group of photoautotrophic and thiotrophic bacteria with limited phenotypic variation. They typically oxidize sulfide and thiosulfate to sulfate with sulfur globules as an intermediate. Based on genome sequence information from 15 strains, the distribution and phylogeny of enzymes involved in their oxidative sulfur metabolism was investigated. At least one homolog of sulfide:quinone oxidoreductase (SQR is present in all strains. In all sulfur-oxidizing GSB strains except the earliest diverging Chloroherpeton thalassium, the sulfide oxidation product is further oxidized to sulfite by the dissimilatory sulfite reductase (DSR system. This system consists of components horizontally acquired partly from sulfide-oxidizing and partly from sulfate-reducing bacteria. Depending on the strain, the sulfite is probably oxidized to sulfate by one of two different mechanisms that have different evolutionary origins: adenosine-5’-phosphosulfate reductase (APR or polysulfide reductase-like complex 3 (PSRLC3. Thiosulfate utilization by the SOX system in GSB has apparently been acquired horizontally from proteobacteria. SoxCD does not occur in GSB, and its function in sulfate formation in other bacteria has been replaced by the DSR system in GSB. Sequence analyses suggested that the conserved soxJXYZAKBW gene cluster was horizontally acquired by Chlorobium phaeovibrioides DSM 265 from the Chlorobaculum lineage and that this acquisition was mediated by a mobile genetic element. Thus, the last common ancestor of currently known GSB was probably photoautotrophic, hydrogenotrophic, and contained SQR but not DSR or SOX. In addition, the predominance of the Chlorobium-Chlorobaculum-Prosthecochloris lineage among cultured GSB could be due to the horizontally acquired DSR and SOX systems. Finally, based upon structural, biochemical, and phylogenetic analyses, a uniform nomenclature is suggested for sqr genes in

  20. The putative thiosulfate sulfurtransferases PspE and GlpE contribute to virulence of Salmonella Typhimurium in the mouse model of systemic disease

    DEFF Research Database (Denmark)

    Wallrodt, Inke; Jelsbak, Lotte; Thorndahl, Lotte;

    2013-01-01

    contribute to S. Typhimurium virulence, as a glpE and pspE double deletion strain showed significantly decreased virulence in a mouse model of systemic infection. However, challenge of cultured epithelial cells and macrophages did not reveal any virulence-associated phenotypes. We hypothesized...... that their contribution to virulence could be in sulfur metabolism or by contributing to resistance to nitric oxide, oxidative stress, or cyanide detoxification. In vitro studies demonstrated that glpE but not pspE was important for resistance to H2O2. Since the double mutant, which was the one affected in virulence......, was not affected in this assay, we concluded that resistance tooxidative stress and the virulence phenotype was most likely not linked. The two genes did not contribute to nitric oxide stress, to synthesis of essential sulfur containing amino acids, nor to detoxification of cyanide. Currently, the precise...

  1. Aerobic bacterial pyrite oxidation and acid rock drainage during the Great Oxidation Event.

    Science.gov (United States)

    Konhauser, Kurt O; Lalonde, Stefan V; Planavsky, Noah J; Pecoits, Ernesto; Lyons, Timothy W; Mojzsis, Stephen J; Rouxel, Olivier J; Barley, Mark E; Rosìere, Carlos; Fralick, Phillip W; Kump, Lee R; Bekker, Andrey

    2011-10-19

    The enrichment of redox-sensitive trace metals in ancient marine sedimentary rocks has been used to determine the timing of the oxidation of the Earth's land surface. Chromium (Cr) is among the emerging proxies for tracking the effects of atmospheric oxygenation on continental weathering; this is because its supply to the oceans is dominated by terrestrial processes that can be recorded in the Cr isotope composition of Precambrian iron formations. However, the factors controlling past and present seawater Cr isotope composition are poorly understood. Here we provide an independent and complementary record of marine Cr supply, in the form of Cr concentrations and authigenic enrichment in iron-rich sedimentary rocks. Our data suggest that Cr was largely immobile on land until around 2.48 Gyr ago, but within the 160 Myr that followed--and synchronous with independent evidence for oxygenation associated with the Great Oxidation Event (see, for example, refs 4-6)--marked excursions in Cr content and Cr/Ti ratios indicate that Cr was solubilized at a scale unrivalled in history. As Cr isotope fractionations at that time were muted, Cr must have been mobilized predominantly in reduced, Cr(III), form. We demonstrate that only the oxidation of an abundant and previously stable crustal pyrite reservoir by aerobic-respiring, chemolithoautotrophic bacteria could have generated the degree of acidity required to solubilize Cr(III) from ultramafic source rocks and residual soils. This profound shift in weathering regimes beginning at 2.48 Gyr ago constitutes the earliest known geochemical evidence for acidophilic aerobes and the resulting acid rock drainage, and accounts for independent evidence of an increased supply of dissolved sulphate and sulphide-hosted trace elements to the oceans around that time. Our model adds to amassing evidence that the Archaean-Palaeoproterozoic boundary was marked by a substantial shift in terrestrial geochemistry and biology.

  2. Validation of algal viability treated with total residual oxidant and organic matter by flow cytometry.

    Science.gov (United States)

    Lee, Junghyun; Choi, Eun Joo; Rhie, Kitae

    2015-08-15

    Algal cell growth after starch and oxidant treatments in seawater species (Isochrysis galbana and Phaeodactylum tricornutum) and freshwater species (Selenastrum capricornutum and Scenedesmus obliquus) were evaluated by flow cytometry with fluorescein diacetate (FDA) staining to determine algal viability. Growth of algal cell was found to be significantly different among groups treated with NaOCl, starch and/or sodium thiosulfate, which are active substance (Total Residual Oxidant; TRO as Cl2), organic compound to meet efficacy testing standard and neutralizer of TRO by Ballast Water Management Convention of International Maritime Organization, respectively. The viability of algal cell treated with TRO in starch-add culture of 5days after treatment and neutralization was decreased significantly. ATP contents of the treated algal cells corresponded to the FL1 fluorescent signal of flow cytometry with FDA staining. I. galbana was the most sensitive to TRO-neutralized cultures during viability analysis.

  3. Iron oxide and pyrocatechol: a spectroscopy study of the reaction products

    Directory of Open Access Journals (Sweden)

    Wagner José Barreto

    2006-12-01

    Full Text Available The reaction of 1,2-dihydroxy-benzene (pyrocatechol (C6H6O2 with iron oxide (Fe2O3 and sodium thiosulfate (Na2S2O3 in aqueous medium (pH 7 was investigated. Pyrocatechol suffers autoxidation and coordinates with Fe3+ in solution. The presence of S2O3(2- in solution was fundamental to generate and stabilize the pyrocatechol oxidation products as o-semiquinones. This compound was isolated and its structure characterized using FT-IR, EPR and UV-Vis Spectroscopy as [CTA][Fe(SQ2(Cat]. A thermal mass loss mechanism was proposed based on Thermogravimetric Analysis (TG to support the structural characterization.

  4. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

    Energy Technology Data Exchange (ETDEWEB)

    Beam, Jake; Bernstein, Hans C.; Jay, Z.; Kozubal, Mark; Jennings, Ryan; Tringe, Susannah G.; Inskeep, William P.

    2016-02-15

    Iron oxide microbial mats are ubiquitous geobiological features on Earth and occur in extant acidic hot springs of Yellowstone National Park (YNP), WY, USA, and form as a result of microbial processes. The relative contribution of different organisms to the development of these mat ecosystems is of specific interest. We hypothesized that chemolithoautotrophic organisms contribute to the early development and production of Fe(III)-oxide mats, which could support later-colonizing heterotrophic microorganisms. Sterile glass slides were incubated in the outflow channels of two acidic geothermal springs in YNP, and spatiotemporal changes in Fe(III)-oxide accretion and abundance of relevant community members were measured. Lithoautotrophic Hydrogenobaculum spp. were first colonizers and the most abundant taxa identified during early successional stages (7 – 40 days). Populations of M. yellowstonensis colonized after ~ 7 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized after 30 days, and emerge as the dominant functional guild in mature iron oxide mats (1 – 2 cm thick) that form after 70 – 120 days. First-order rate constants of iron oxide accretion ranged from 0.05 – 0.046 day-1, and reflected the absolute amount of iron accreted. Micro- and macroscale microterracettes were identified during iron oxide mat development, and suggest that the mass transfer of oxygen limits microbial growth. This was also demonstrated using microelectrode measurements of oxygen as a function of mat depth, which showed steep gradients in oxygen from the aqueous mat interface to ~ 1 mm. The formation and succession of amorphous Fe(III)-oxide mat communities follows a predictable pattern of distinct stages and growth. The successional stages and microbial signatures observed in these extant Fe(III)-oxide mat communities may be relevant to other past or present Fe(III)-oxide mineralizing systems.

  5. Arsenite Oxidation and Arsenite Resistance by Bacillus sp. PNKP-S2

    Directory of Open Access Journals (Sweden)

    Pranee Pattanapipitpaisal

    2015-01-01

    Full Text Available Arsenic causes human health problems after accumulate in the body for 10-15 years and arsenite [As(III] is generally regarded as being more mobile and toxic than other oxidation states. In this study, two-hundred and three bacterial strains were isolated from groundwater and soil samples collecting in Ubon Ratchathani Province, Thailand. All strains were screened for arsenic tolerant efficiency at 1-10 mM of sodium arsenite. Eighteen selected strains which had the highest resistance to 10 mM of As(III were further studied for their As(III-oxidizing activity and growth in enrichment and growth medium (EG medium supplemented with 0.58 mM of As(III. It was found that strain PNKP-S2 was able to grow in the medium with As(III as a sole energy source and had 89.11% As(III removal within 48 h. The PCR-based 16S rDNA sequencing analysis revealed that the strain PNKP-S2 was closed relative to Bacillus sp. This is the first report on Bacillus sp. chemolithoautotrophic As(III-oxidizer and this strain could be a potential candidate for application in arsenic remediation of contaminated water.

  6. Biogeochemical processes governing natural pyrite oxidation and release of acid metalliferous drainage.

    Science.gov (United States)

    Chen, Ya-ting; Li, Jin-tian; Chen, Lin-xing; Hua, Zheng-shuang; Huang, Li-nan; Liu, Jun; Xu, Bi-bo; Liao, Bin; Shu, Wen-sheng

    2014-05-20

    The oxidative dissolution of sulfide minerals (principally pyrite) is responsible for the majority of acid metalliferous drainage from mine sites, which represents a significant environmental problem worldwide. Understanding the complex biogeochemical processes governing natural pyrite oxidation is critical not only for solving this problem but also for understanding the industrial bioleaching of sulfide minerals. To this end, we conducted a simulated experiment of natural pyrite oxidative dissolution. Pyrosequencing analysis of the microbial community revealed a distinct succession across three stages. At the early stage, a newly proposed genus, Tumebacillus (which can use sodium thiosulfate and sulfite as the sole electron donors), dominated the microbial community. At the midstage, Alicyclobacillus (the fifth most abundant genus at the early stage) became the most dominant genus, whereas Tumebacillus was still ranked as the second most abundant. At the final stage, the microbial community was dominated by Ferroplasma (the tenth most abundant genus at the early stage). Our geochemical and mineralogical analyses indicated that exchangeable heavy metals increased as the oxidation progressed and that some secondary sulfate minerals (including jarosite and magnesiocopiapite) were formed at the final stage of the oxidation sequence. Additionally, we propose a comprehensive model of biogeochemical processes governing the oxidation of sulfide minerals.

  7. Microbiological oxidation of antimony(III) with oxygen or nitrate by bacteria isolated from contaminated mine sediments

    Science.gov (United States)

    Terry, Lee R.; Kulp, Thomas R.; Wiatrowski, Heather A.; Miller, Laurence G.; Oremland, Ronald S.

    2015-01-01

    Bacterial oxidation of arsenite [As(III)] is a well-studied and important biogeochemical pathway that directly influences the mobility and toxicity of arsenic in the environment. In contrast, little is known about microbiological oxidation of the chemically similar anion antimonite [Sb(III)]. In this study, two bacterial strains, designated IDSBO-1 and IDSBO-4, which grow on tartrate compounds and oxidize Sb(III) using either oxygen or nitrate, respectively, as a terminal electron acceptor, were isolated from contaminated mine sediments. Both isolates belonged to the Comamonadaceae family and were 99% similar to previously described species. We identify these novel strains as Hydrogenophagataeniospiralis strain IDSBO-1 and Variovorax paradoxus strain IDSBO-4. Both strains possess a gene with homology to the aioA gene, which encodes an As(III)-oxidase, and both oxidize As(III) aerobically, but only IDSBO-4 oxidized Sb(III) in the presence of air, while strain IDSBO-1 could achieve this via nitrate respiration. Our results suggest that expression of aioA is not induced by Sb(III) but may be involved in Sb(III) oxidation along with an Sb(III)-specific pathway. Phylogenetic analysis of proteins encoded by the aioA genes revealed a close sequence similarity (90%) among the two isolates and other known As(III)-oxidizing bacteria, particularly Acidovorax sp. strain NO1. Both isolates were capable of chemolithoautotrophic growth using As(III) as a primary electron donor, and strain IDSBO-4 exhibited incorporation of radiolabeled [14C]bicarbonate while oxidizing Sb(III) from Sb(III)-tartrate, suggesting possible Sb(III)-dependent autotrophy. Enrichment cultures produced the Sb(V) oxide mineral mopungite and lesser amounts of Sb(III)-bearing senarmontite as precipitates.

  8. Microbiological oxidation of antimony(III) with oxygen or nitrate by bacteria isolated from contaminated mine sediments.

    Science.gov (United States)

    Terry, Lee R; Kulp, Thomas R; Wiatrowski, Heather; Miller, Laurence G; Oremland, Ronald S

    2015-12-01

    Bacterial oxidation of arsenite [As(III)] is a well-studied and important biogeochemical pathway that directly influences the mobility and toxicity of arsenic in the environment. In contrast, little is known about microbiological oxidation of the chemically similar anion antimonite [Sb(III)]. In this study, two bacterial strains, designated IDSBO-1 and IDSBO-4, which grow on tartrate compounds and oxidize Sb(III) using either oxygen or nitrate, respectively, as a terminal electron acceptor, were isolated from contaminated mine sediments. Both isolates belonged to the Comamonadaceae family and were 99% similar to previously described species. We identify these novel strains as Hydrogenophaga taeniospiralis strain IDSBO-1 and Variovorax paradoxus strain IDSBO-4. Both strains possess a gene with homology to the aioA gene, which encodes an As(III)-oxidase, and both oxidize As(III) aerobically, but only IDSBO-4 oxidized Sb(III) in the presence of air, while strain IDSBO-1 could achieve this via nitrate respiration. Our results suggest that expression of aioA is not induced by Sb(III) but may be involved in Sb(III) oxidation along with an Sb(III)-specific pathway. Phylogenetic analysis of proteins encoded by the aioA genes revealed a close sequence similarity (90%) among the two isolates and other known As(III)-oxidizing bacteria, particularly Acidovorax sp. strain NO1. Both isolates were capable of chemolithoautotrophic growth using As(III) as a primary electron donor, and strain IDSBO-4 exhibited incorporation of radiolabeled [(14)C]bicarbonate while oxidizing Sb(III) from Sb(III)-tartrate, suggesting possible Sb(III)-dependent autotrophy. Enrichment cultures produced the Sb(V) oxide mineral mopungite and lesser amounts of Sb(III)-bearing senarmontite as precipitates.

  9. Verification of Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS)Agar Medium Industrial Standard%硫代硫酸盐-柠檬酸盐-胆盐-蔗糖琼脂培养基行业标准验证

    Institute of Scientific and Technical Information of China (English)

    孙楠; 黄杰; 于婷; 孙彬裕; 高尚先; 曲守方

    2014-01-01

    Objective To verify the application of professional standard for Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS)agar medium.Methods TCBS agar medium produced by different factories are obtained for pH value and microbiological grow test according to the formulated medium standard.pH value and solution of medium are determined and bacterial cultures of the control strains are inoculated in the medium to detected bacterial growth.Results pH value and solution of medium were within the specified range. The control strains grew well. Conclusion As the recommended industrial standard, TCBS agar medium standard may be applied to evaluate and supervise the TCBS agar medium quality in our country.%目的:按照修订的硫代硫酸盐-柠檬酸盐-胆盐-蔗糖(TCBS)琼脂培养基行业标准中的要求进行试验,验证该行业标准的适用性。方法取不同厂家生产的TCBS琼脂培养基,根据TCBS琼脂培养基行业标准的要求,进行pH值、水分的测定和微生物生长试验。测定了TCBS琼脂培养基的pH值和水分,并将质控菌株的培养物接种到受试的培养基平皿中进行微生物生长试验。结果TCBS琼脂培养基的pH值和水分均符合行业标准的规定,且各质控菌株生长良好。结论作为推荐性的国家行业标准,TCBS琼脂培养基行业标准可以用于我国该培养基的质量评价和监管工作的需要。

  10. Hydrogen sulfide and nitric oxide metabolites in the blood of free-ranging brown bears and their potential roles in hibernation

    DEFF Research Database (Denmark)

    Revsbech, Inge G; Shen, Xinggui; Chakravarti, Ritu

    2014-01-01

    inhibitors of mitochondrial respiration, hydrogen sulfide (H2S) and nitric oxide (NO), in winter-hibernating and summer-active free-ranging Scandinavian brown bears. We found that levels of sulfide metabolites were overall similar in summer-active and hibernating bears but their composition in the plasma...... differed significantly, with a decrease in bound sulfane sulfur in hibernation. High levels of unbound free sulfide correlated with high levels of cysteine (Cys) and with low levels of bound sulfane sulfur, indicating that during hibernation H2S, in addition to being formed enzymatically from the substrate...... Cys, may also be regenerated from its oxidation products, including thiosulfate and polysulfides. In the absence of any dietary intake, this shift in the mode of H2S synthesis would help preserve free Cys for synthesis of glutathione (GSH), a major antioxidant found at high levels in the red blood...

  11. The genome of Nitrospina gracilis illuminates the metabolism and evolution of the major marine nitrite oxidizer

    Directory of Open Access Journals (Sweden)

    Sebastian eLuecker

    2013-02-01

    Full Text Available In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this organism were available and its phylogenetic affiliation was uncertain. In this study, the draft genome sequence of Nitrospina gracilis strain 3/211 was obtained. Unexpectedly for an aerobic organism, N. gracilis lacks classical reactive oxygen defense mechanisms and uses the reductive tricarboxylic acid cycle for carbon fixation. These features indicate microaerophilic ancestry and are consistent with the presence of Nitrospina in marine oxygen minimum zones. Fixed carbon is stored intracellularly as glycogen, but genes for utilizing external organic carbon sources were not identified. N. gracilis also contains a full gene set for oxidative phosphorylation with oxygen as terminal electron acceptor and for reverse electron transport from nitrite to NADH. A novel variation of complex I may catalyze the required reverse electron flow to low-potential ferredoxin. Interestingly, comparative genomics indicated a strong evolutionary link between Nitrospina, the nitrite-oxidizing genus Nitrospira, and anaerobic ammonium oxidizers, apparently including the horizontal transfer of a periplasmically oriented nitrite oxidoreductase and other key genes for nitrite oxidation at an early evolutionary stage. Further, detailed phylogenetic analyses using concatenated marker genes provided evidence that Nitrospina forms a novel bacterial phylum, for which we propose the name Nitrospinae.

  12. The Genome of Nitrospina gracilis Illuminates the Metabolism and Evolution of the Major Marine Nitrite Oxidizer.

    Science.gov (United States)

    Lücker, Sebastian; Nowka, Boris; Rattei, Thomas; Spieck, Eva; Daims, Holger

    2013-01-01

    In marine systems, nitrate is the major reservoir of inorganic fixed nitrogen. The only known biological nitrate-forming reaction is nitrite oxidation, but despite its importance, our knowledge of the organisms catalyzing this key process in the marine N-cycle is very limited. The most frequently encountered marine NOB are related to Nitrospina gracilis, an aerobic chemolithoautotrophic bacterium isolated from ocean surface waters. To date, limited physiological and genomic data for this organism were available and its phylogenetic affiliation was uncertain. In this study, the draft genome sequence of N. gracilis strain 3/211 was obtained. Unexpectedly for an aerobic organism, N. gracilis lacks classical reactive oxygen defense mechanisms and uses the reductive tricarboxylic acid cycle for carbon fixation. These features indicate microaerophilic ancestry and are consistent with the presence of Nitrospina in marine oxygen minimum zones. Fixed carbon is stored intracellularly as glycogen, but genes for utilizing external organic carbon sources were not identified. N. gracilis also contains a full gene set for oxidative phosphorylation with oxygen as terminal electron acceptor and for reverse electron transport from nitrite to NADH. A novel variation of complex I may catalyze the required reverse electron flow to low-potential ferredoxin. Interestingly, comparative genomics indicated a strong evolutionary link between Nitrospina, the nitrite-oxidizing genus Nitrospira, and anaerobic ammonium oxidizers, apparently including the horizontal transfer of a periplasmically oriented nitrite oxidoreductase and other key genes for nitrite oxidation at an early evolutionary stage. Further, detailed phylogenetic analyses using concatenated marker genes provided evidence that Nitrospina forms a novel bacterial phylum, for which we propose the name Nitrospinae.

  13. Enrichment and genome sequence of the group I.1a ammonia-oxidizing Archaeon "Ca. Nitrosotenuis uzonensis" representing a clade globally distributed in thermal habitats.

    Directory of Open Access Journals (Sweden)

    Elena V Lebedeva

    Full Text Available The discovery of ammonia-oxidizing archaea (AOA of the phylum Thaumarchaeota and the high abundance of archaeal ammonia monooxygenase subunit A encoding gene sequences in many environments have extended our perception of nitrifying microbial communities. Moreover, AOA are the only aerobic ammonia oxidizers known to be active in geothermal environments. Molecular data indicate that in many globally distributed terrestrial high-temperature habits a thaumarchaeotal lineage within the Nitrosopumilus cluster (also called "marine" group I.1a thrives, but these microbes have neither been isolated from these systems nor functionally characterized in situ yet. In this study, we report on the enrichment and genomic characterization of a representative of this lineage from a thermal spring in Kamchatka. This thaumarchaeote, provisionally classified as "Candidatus Nitrosotenuis uzonensis", is a moderately thermophilic, non-halophilic, chemolithoautotrophic ammonia oxidizer. The nearly complete genome sequence (assembled into a single scaffold of this AOA confirmed the presence of the typical thaumarchaeotal pathways for ammonia oxidation and carbon fixation, and indicated its ability to produce coenzyme F420 and to chemotactically react to its environment. Interestingly, like members of the genus Nitrosoarchaeum, "Candidatus N. uzonensis" also possesses a putative artubulin-encoding gene. Genome comparisons to related AOA with available genome sequences confirmed that the newly cultured AOA has an average nucleotide identity far below the species threshold and revealed a substantial degree of genomic plasticity with unique genomic regions in "Ca. N. uzonensis", which potentially include genetic determinants of ecological niche differentiation.

  14. Composition and distribution of TCBS bacteria groups from sediments of Jiulong River estuary%九龙江口沉积物TCBS(Thiosulfate Citrate Bile Salts Sucrose)菌群的分布

    Institute of Scientific and Technical Information of China (English)

    陈明霞; 李和阳; 马云飞; 史莹鑫; 傅毅凌; 郑天凌; 郑森林; 陈彬

    2012-01-01

    [Objective]To investigate potential pathogens in waters of Xiamen from Jiulong River, and to provide useful information for the prevention and control of potential pathogen infections. [Methods] All samples were spread on Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar plates, and then incubated at 26 ± 1℃ for 24 ±2 h. In total 158 TCBS strains were isolated from TCBS agar plates and pure-cultivated on 2216E agar plates. All strains were identified using the 16S rRNA gene- Restriction fragment length polymorphism (RFLP) , 16S rRNA sequence analysis, GenBank database Basic Local Alignment Search Tool (BLAST) and phylogenetic analysis. [Results] The results show that 158 TCBS strains from the sediments of Jiulong River estuary were classfied as 7 genus, which were Pseudomonas (28%), Aeromonas (24%) , Pseudoalteromonas (19%) , Shewanella (13%) , Bacillus (11%) , Vibrio (4%) and Psychrobacter (1%). The composition and distribution of TCBS bacteria groups varied with stations. Non-halophilic or haloduric bacteria groups were dominant in the upper area of Jiulong River estuary, and halophilic and haloduric bacteria were dominant in the lower area, which characterized a typical estuary feature. The salinity played a key role in the distribution of TCBS groups. Vibrios did not constitute a significant proportion (6% - 19%) of the total TCBS strains at different stations, and most of the them distributed at the lower region. [Conclusion] There were a lot of potential pathogens in Jiulong River estuary. Aeromonas, a typical genus of halotolerant bacteria, was the potentially terrigenous bacteria contamination to the waters of Xiamen. Most Vibrio specieses were marine aborigines, which was not directly contaminated from the runoff of Jiulong River.%[目的]调查九龙江流域对厦门海域潜在的病原菌“污染”,为相关侵染性病害的预防和控制提供有价值的资料.[方法]通过TCBS(Thiosulfate Citrate Bile Salts Sucrose)培养基从九龙

  15. The mechanisms of pyrite oxidation and leaching: A fundamental perspective

    Science.gov (United States)

    Chandra, A. P.; Gerson, A. R.

    2010-09-01

    Pyrite is the earth's most abundant sulfide mineral. Its frequent undesirable association with minerals of economic value such as sphalerite, chalcopyrite and galena, and precious metals such as gold necessitates costly separation processes such as leaching and flotation. Additionally pyrite oxidation is a major contributor to the environmental problem of acid rock drainage. The surface oxidation reactions of pyrite are therefore important both economically and environmentally. Significant variations in electrical properties resulting from lattice substitution of minor and trace elements into the lattice structure exist between pyrite from different geographical locations. Furthermore the presence of low coordination surface sites as a result of conchoidal fracture causes a reduction in the band gap at the surface compared to the bulk thus adding further electrochemical variability. Given the now general acceptance after decades of research that electrochemistry dominates the oxidation process, the geographical location, elemental composition and semi-conductor type (n or p) of pyrite are important considerations. Aqueous pyrite oxidation results in the production of sulfate and ferrous iron. However other products such as elemental sulfur, polysulfides, hydrogen sulfide, ferric hydroxide, iron oxide and iron(III) oxyhydroxide may also form. Intermediate species such as thiosulfate, sulfite and polythionates are also proposed to occur. Oxidation and leach rates are generally influenced by solution Eh, pH, oxidant type and concentration, hydrodynamics, grain size and surface area in relation to solution volume, temperature and pressure. Of these, solution Eh is most critical as expected for an electrochemically controlled process, and directly correlates with surface area normalised rates. Studies using mixed mineral systems further indicate the importance of electrochemical processes during the oxidation process. Spatially resolved surface characterisation of fresh

  16. Hydrometallurgical recovery of silver from waste silver oxide button cells

    Energy Technology Data Exchange (ETDEWEB)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P. [Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2006-10-27

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000{sup o}C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated. (author)

  17. Magnesium Oxide

    Science.gov (United States)

    Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some ... to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative ...

  18. Sulfur speciation and sulfide oxidation in the water column of the Black Sea

    Science.gov (United States)

    Luther, George W., III; Church, Thomas M.; Powell, David

    We have applied sulfur speciation techniques to understand the chemistry and cycling of sulfur in Black Sea waters. The only reduced dissolved inorganic sulfur species detected (above the low minimum detection limits of the voltammetric methods employed) in the water column was hydrogen sulfide. The maximum concentration of sulfide (423 μM) is similar to previous reports. Using a cathodic stripping square wave voltammetry (CSSWV) method for nanomolar levels of sulfide, we determined the precise boundary between the "free" hydrogen sulfide (sulfidic) zone and the upper (oxic/suboxic) water column at the two stations studied. This boundary has apparently moved up by about 50 m in the past 20 years. Our results help demonstrate three chemically distinct zones of water in the central basin of the Black Sea: (1) the oxic [0-65 m], (2) the anoxic/nonsulfidic [65-100 m] and (3) the sulfidic [>100 m]. Sulfide bound to metals ("complexed" sulfide) is observed in both the oxic and anoxic/nonsulfidic zones of the water column. This supports previous studies on metal sulfide forms. From the electrochemical data, it is possible to estimate the strength of the complexation of sulfide to metals (log K = 10 to 11). Thiosulfate and sulfite were below our minimum detectable limit (MDL) of 50 nM using CSSWV. Elemental sulfur (MDL 5 nM) was detected below the onset of the hydrogen sulfide zone (90-100 m) with a maximum of 30-60 nM near 120 m. The sulfur speciation results for the Black Sea are lower by one order of magnitude or more than other marine systems such as the Cariaco Trench and salt marshes. New HPLC techniques were applied to detect thiols at submicromolar levels. The presence of thiols (2-mercaptoethylamine, 2-mercaptoethanol, N-acetylcysteine and glutathione) is correlated with the remineralization of organic matter at the oxic and anoxic/nonsulfidic interface. Water samples collected from the upper 50 m of the sulfidic zone showed significant sulfide oxidation on

  19. Carbon dioxide fixation by Metallosphaera yellowstonensis and acidothermophilic iron-oxidizing microbial communities from Yellowstone National Park

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, Ryan; Whitmore, Laura M.; Moran, James J.; Kreuzer, Helen W.; Inskeep, William P.

    2014-05-01

    The fixation of inorganic carbon (as carbon dioxide) has been documented in all three domains of life and results in the biosynthesis of a diverse suite of organic compounds that support the growth of heterotrophic organisms. The primary aim of this study was to assess the importance of carbon dioxide fixation in high-temperature Fe(III)-oxide mat communities and in pure cultures of one of the dominant Fe(II)-oxidizing organisms (Metallosphaera yellowstonensis strain MK1) present in situ. Protein-encoding genes of the complete 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) carbon fixation pathway were identified in pure-cultures of M. yellowstonensis strain MK1. Metagenome sequencing from the same environments also revealed genes for the 3-HP/4-HB pathway belonging to M. yellowstonensis populations, as well as genes for a complete reductive TCA cycle from Hydrogenobaculum spp. (Aquificales). Stable isotope (13CO2) labeling was used to measure the fixation of CO2 by M. yellowstonensis strain MK1, and in ex situ assays containing live Fe(III)-oxide microbial mats. Results showed that M. yellowstonensis strain MK1 fixes CO2 via the 3-HP/4-HB pathway with a fractionation factor of ~ 2.5 ‰. Direct analysis of the 13C composition of dissolved inorganic C (DIC), dissolved organic C (DOC), landscape C and microbial mat C showed that mat C is comprised of both DIC and non-DIC sources. The estimated contribution of DIC carbon to biomass C (> ~ 35%) is reasonably consistent with the relative abundance of known chemolithoautotrophs and corresponding CO2 fixation pathways detected in metagenome sequence. The significance of DIC as a major source of carbon for Fe-oxide mat communities provides a foundation for examining microbial interactions in these systems that are dependent on the activity of autotrophic organisms such as Hydrogenobaculum and Metallosphaera spp.

  20. Development of reactor configurations for an electrofuels platform utilizing genetically modified iron oxidizing bacteria for the reduction of CO2 to biochemicals.

    Science.gov (United States)

    Guan, Jingyang; Berlinger, Sarah A; Li, Xiaozheng; Chao, Zhongmou; Sousa E Silva, Victor; Banta, Scott; West, Alan C

    2017-03-10

    Electrofuels processes are potentially promising platforms for biochemical production from CO2 using renewable energy. When coupled to solar panels, this approach could avoid the inefficiencies of photosynthesis and there is no competition with food agriculture. In addition, these systems could potentially be used to store intermittent or stranded electricity generated from other renewable sources. Here we develop reactor configurations for continuous electrofuels processes to convert electricity and CO2 to isobutyric acid (IBA) using genetically modified (GM) chemolithoautotrophic Acidithiobacillus ferrooxidans. These cells oxidize ferrous iron which can be electrochemically reduced. During two weeks of cultivation on ferrous iron, stable cell growth and continuous IBA production from CO2 were achieved in a process where media was circulated between electrochemical and biochemical rectors. An alternative process with an additional electrochemical cell for accelerated ferrous production was developed, and this system achieved an almost three-fold increase in steady state cell densities, and an almost 4-fold increase in the ferrous iron oxidation rate. Combined, this led to an almost 8-fold increase in the steady state volumetric productivity of IBA up to 0.063±0.012mg/L/h, without a decline in energy efficiency from previous work. Continued development of reactor configurations which can increase the delivery of energy to the genetically modified cells will be required to increase product titers and volumetric productivities.

  1. RNA oxidation

    DEFF Research Database (Denmark)

    Kjaer, L. K.; Cejvanovic, V.; Henriken, T.

    2015-01-01

    RNA modification has attracted increasing interest as it is realized that epitranscriptomics is important in disease development. In type 2 diabetes we have suggested that high urinary excretion of 8-oxo-2'-Guanosine (8oxoGuo), as a measure of global RNA oxidation, is associated with poor survival.......9 significant hazard ratio for death compared with the quartile with the lowest 8oxoGuo excretion when adjusted for age, sex, BMI, smoker status, s-HbA1c, urine protein excretion and s-cholesterol. We conclude that it is now established that RNA oxidation is an independent risk factor for death in type 2...... diabetes. In agreement with our previous finding, DNA oxidation did not show any prognostic value. RNA oxidation represents oxidative stress intracellularly, presumably predominantly in the cytosol. The mechanism of RNA oxidation is not clear, but hypothesized to result from mitochondrial dysfunction...

  2. [Nitric oxide].

    Science.gov (United States)

    Rovira, I

    1995-01-01

    Nitric oxide was identified as the relaxing factor derived from the endothelium in 1987. Nitric oxide synthesis allows the vascular system to maintain a state of vasodilation, thereby regulating arterial pressure. Nitric oxide is also found in platelets, where it inhibits adhesion and aggregation; in the immune system, where it is responsible for the cytotoxic action of macrophages; and in the nervous system, where it acts as neurotransmitter. A deficit in endogenous synthesis of nitric oxide contributes to such conditions as essential arterial hypertension, pulmonary hypertension and heart disease. An excess of nitrous oxide induced by endotoxins and cytokinins, meanwhile, is believed to be responsible for hypotension in septic shock and for hyperdynamic circulatory state in cirrhosis of the liver. Nitric oxide has also been implicated in the rejection of transplanted organs and in cell damage after reperfusion. Inhaled nitrous oxide gas reduces pulmonary hypertension without triggering systemic hypotension in both experimental and clinical conditions. It also produces selective vasodilation when used to ventilate specific pulmonary areas, thereby improving the ventilation/perfusion ratio and, hence, oxygenation. Nitric oxide inhalation is effective in pulmonary hypertension-coincident with chronic obstructive lung disease, in persistent neonatal pulmonary hypertension and in pulmonary hypertension with congenital or acquired heart disease. Likewise, it reduces intrapulmonary shunt in acute respiratory failure and improves gas exchange. Under experimental conditions nitric oxide acts as a bronchodilator, although it seems to be less effective for this purpose in clinical use.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Metatranscriptomic analysis of sulfur oxidation genes in the endosymbiont of Solemya velum

    Directory of Open Access Journals (Sweden)

    Frank eStewart

    2011-06-01

    Full Text Available Thioautotrophic endosymbionts in the Domain Bacteria mediate key sulfur transformations in marine reducing environments. However, the molecular pathways underlying symbiont metabolism and the extent to which these pathways are expressed in situ are poorly characterized for almost all symbioses. This is largely due to the difficulty of culturing symbionts apart from their hosts. Here, we use pyrosequencing of community RNA transcripts (i.e., the metatranscriptome to characterize enzymes of dissimilatory sulfur metabolism in the model symbiosis between the coastal bivalve Solemya velum and its intracellular thioautotrophic symbionts. High-throughput sequencing of total RNA from the symbiont-containing gill of a single host individual generated 1.6 million sequence reads (500 Mbp. Of these, 43,735 matched Bacteria protein-coding genes in BLASTX searches of the NCBI database. The taxonomic identities of the matched genes indicated relatedness to diverse species of sulfur-oxidizing Gammaproteobacteria, including other thioautotrophic symbionts and the purple sulfur bacterium Allochromatium vinosum. Manual querying of these data identified 28 genes from diverse pathways of sulfur energy metabolism, including the dissimilatory sulfite reductase (Dsr pathway for sulfide oxidation to sulfite, the APS pathway for sulfite oxidation, and the Sox pathway for thiosulfate oxidation. In total, reads matching sulfur energy metabolism genes represented 7% of the Bacteria mRNA pool. Together, these data highlight the dominance of thioautotrophy in the context of symbiont community metabolism, identify the likely pathways mediating sulfur oxidation, and illustrate the utility of metatranscriptome sequencing for characterizing community gene transcription of uncultured symbionts.

  4. Metatranscriptomic analysis of sulfur oxidation genes in the endosymbiont of solemya velum.

    Science.gov (United States)

    Stewart, Frank J; Dmytrenko, Oleg; Delong, Edward F; Cavanaugh, Colleen M

    2011-01-01

    Thioautotrophic endosymbionts in the Domain Bacteria mediate key sulfur transformations in marine reducing environments. However, the molecular pathways underlying symbiont metabolism and the extent to which these pathways are expressed in situ are poorly characterized for almost all symbioses. This is largely due to the difficulty of culturing symbionts apart from their hosts. Here, we use pyrosequencing of community RNA transcripts (i.e., the metatranscriptome) to characterize enzymes of dissimilatory sulfur metabolism in the model symbiosis between the coastal bivalve Solemya velum and its intracellular thioautotrophic symbionts. High-throughput sequencing of total RNA from the symbiont-containing gill of a single host individual generated 1.6 million sequence reads (500 Mbp). Of these, 43,735 matched Bacteria protein-coding genes in BLASTX searches of the NCBI database. The taxonomic identities of the matched genes indicated relatedness to diverse species of sulfur-oxidizing Gammaproteobacteria, including other thioautotrophic symbionts and the purple sulfur bacterium Allochromatium vinosum. Manual querying of these data identified 28 genes from diverse pathways of sulfur energy metabolism, including the dissimilatory sulfite reductase (Dsr) pathway for sulfur oxidation to sulfite, the APS pathway for sulfite oxidation, and the Sox pathway for thiosulfate oxidation. In total, reads matching sulfur energy metabolism genes represented 7% of the Bacteria mRNA pool. Together, these data highlight the dominance of thioautotrophy in the context of symbiont community metabolism, identify the likely pathways mediating sulfur oxidation, and illustrate the utility of metatranscriptome sequencing for characterizing community gene transcription of uncultured symbionts.

  5. Enhanced metabolic versatility of planktonic sulfur-oxidizing γ-proteobacteria in an oxygen-deficient coastal ecosystem

    Directory of Open Access Journals (Sweden)

    Alejandro A. Murillo

    2014-07-01

    Full Text Available Sulfur-oxidizing Gamma-proteobacteria are abundant in marine oxygen-deficient waters, and appear to play a key role in a previously unrecognized cryptic sulfur cycle. Metagenomic analyses of members of the uncultured SUP05 lineage in the Canadian seasonally anoxic fjord Saanich Inlet (SI, hydrothermal plumes in the Guaymas Basin (GB and single cell genomics analysis of two ARCTIC96BD-19 representatives from the South Atlantic Sub-Tropical Gyre (SASG have shown them to be metabolically versatile. However, SI and GB SUP05 bacteria seem to be obligate chemolithoautotrophs, whereas ARCTIC96BD-19 has the genetic potential for aerobic respiration. Here, we present results of a metagenomic analysis of sulfur-oxidizing Gamma-proteobacteria (GSO, closely related to the SUP05/ARCTIC96BD-19 clade, from a coastal ecosystem in the eastern South Pacific (ESP. This ecosystem experiences seasonal anoxia and accumulation of nitrite and ammonium at depth, with a corresponding increase in the abundance of GSO representatives. The ESP-GSOs appear to have a significantly different gene complement than those from Saanich Inlet, Guaymas Basin and SASG. Genomic analyses of de novo assembled contigs indicate the presence of a complete aerobic respiratory complex based on the cytochrome bc1 oxidase. Furthermore, they appear to encode a complete TCA cycle and several transporters for dissolved organic carbon species, suggesting a mixotrophic lifestyle. Thus, the success of sulfur-oxidizing Gamma-proteobacteria in oxygen-deficient marine ecosystems appears due not only to their previously recognized anaerobic metabolic versatility, but also to their capacity to function under aerobic conditions using different carbon sources. Finally, members of ESP-GSO cluster also have the genetic potential for reducing nitrate to ammonium based on the nirBD genes, and may therefore facilitate a tighter coupling of the nitrogen and sulfur cycles in oxygen-deficient waters.

  6. Isolation of iron-oxidizing bacteria from corroded concretes of sewage treatment plants.

    Science.gov (United States)

    Maeda, T; Negishi, A; Komoto, H; Oshima, Y; Kamimura, K; Sugio, T

    1999-01-01

    Thirty-six strains of iron-oxidizing bacteria were isolated from corroded concrete samples obtained at eight sewage treatment plants in Japan. All of the strains isolated grew autotrophically in ferrous sulfate (3.0%), elemental sulfur (1.0%) and FeS (1.0%) media (pH 1.5). Washed intact cells of the 36 isolates had activities to oxidize both ferrous iron and elemental sulfur. Strain SNA-5, a representative of the isolated strains, was a gram-negative, rod-shaped bacterium (0.5-0.6x0.9-1.5 microm). The mean G+C content of its DNA was 55.9 mol%. The pH and temperature optima for growth were 1.5 and 30 degrees C, and the bacterium had activity to assimilate 14CO2 into the cells when ferrous iron or elemental sulfur was used as a sole source of energy. These results suggest that SNA-5 is Thiobacillus ferrooxidans strain. The pHs and numbers of iron-oxidizing bacteria in corroded concrete samples obtained by boring to depths of 0-1, 1-3, and 3-5 cm below the concrete surface were respectively 1.4, 1.7, and 2.0, and 1.2 x 10(8), 5 x 10(7), and 5 x 10(6) cells/g concrete. The degree of corrosion in the sample obtained nearest to the surface was more severe than in the deeper samples. The findings indicated that the levels of acidification and corrosion of the concrete structure corresponded with the number of iron-oxidizing bacteria in a concrete sample. Sulfuric acid produced by the chemolithoautotrophic sulfur-oxidizing bacterium Thiobacillus thiooxidansis known to induce concrete corrosion. Since not only T. thiooxidans but also T. ferrooxidans can oxidize reduced sulfur compounds and produce sulfuric acid, the results strongly suggest that T. ferrooxidans as well as T. thiooxidans is involved in concrete corrosion.

  7. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  8. Iron Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Nikolla; Amonette, James E.

    2016-09-19

    Abstract: Fe oxides are common clay-sized oxide, oxyhydroxide and hydroxide soil minerals. They are compounds of Fe, O, and H that have structures based on close-packed arrays of O. The octahedral and tetrahedral cavities within these arrays are filled with either Fe3+ or Fe2+ to form Fe(O/OH)6, FeO6, or FeO4 structural units. All of the naturally occurring Fe oxide minerals usually undergo some degree of isomorphous substitution of other metal ions for Fe in their structures. Relatively simple techniques may be used to identify Fe oxides in the field based on their typical colors and magnetic properties. In the laboratory, a variety of instrumental techniques can be used to confirm phase identity and to quantify amount. Of these, X-ray diffraction, infrared spectroscopy, electron microscopy, thermal analysis, and Mössbauer spectroscopy are the most commonly used techniques. As oxides, the functional groups on their surfaces may have positive, negative, or no charge depending on pH and on the concentration and nature of other ions in the contact solution. A net positive surface charge usually is observed in soils because Fe oxides have a point-of-zero-charge in the neutral or slightly basic pHs. The functional groups on the surface form complexes with cations and anions from the aqueous phase. Their sorption and electron-buffering properties significantly affect the geochemical cycles of almost all elements having agronomic or environmental significance.

  9. Oxidation catalyst

    Science.gov (United States)

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  10. 'Low-acid' sulfide oxidation using nitrate-enriched groundwater

    Science.gov (United States)

    Donn, Michael; Boxall, Naomi; Reid, Nathan; Meakin, Rebecca; Gray, David; Kaksonen, Anna; Robson, Thomas; Shiers, Denis

    2016-04-01

    Acid drainage (AMD/ARD) is undoubtedly one of the largest environmental, legislative and economic challenges facing the mining industry. In Australia alone, at least 60m is spent on AMD related issues annually, and the global cost is estimated to be in the order of tens of billions US. Furthermore, the challenge of safely and economically storing or treating sulfidic wastes will likely intensify because of the trend towards larger mines that process increasingly higher volumes of lower grade ores and the associated sulfidic wastes and lower profit margins. While the challenge of managing potentially acid forming (PAF) wastes will likely intensify, the industrial approaches to preventing acid production or ameliorating the effects has stagnated for decades. Conventionally, PAF waste is segregated and encapsulated in non-PAF tips to limit access to atmospheric oxygen. Two key limitations of the 'cap and cover' approach are: 1) the hazard (PAF) is not actually removed; only the pollutant linkage is severed; and, 2) these engineered structures are susceptible to physical failure in short-to-medium term, potentially re-establishing that pollutant linkage. In an effort to address these concerns, CSIRO is investigating a passive, 'low-acid' oxidation mechanism for sulfide treatment, which can potentially produce one quarter as much acidity compared with pyrite oxidation under atmospheric oxygen. This 'low-acid' mechanism relies on nitrate, rather than oxygen, as the primary electron accepter and the activity of specifically cultured chemolithoautotrophic bacteria and archaea communities. This research was prompted by the observation that, in deeply weathered terrains of Australia, shallow (oxic to sub-oxic) groundwater contacting weathering sulfides are commonly inconsistent with the geochemical conditions produced by ARD. One key characteristic of these aquifers is the natural abundance of nitrate on a regional scale, which becomes depleted around the sulfide bodies, and

  11. Comparative analysis of the mechanisms of sulfur anion oxidation and reduction by dsr operon to maintain environmental sulfur balance.

    Science.gov (United States)

    Ghosh, Semanti; Bagchi, Angshuman

    2015-12-01

    Sulfur metabolism is one of the oldest known redox geochemical cycles in our atmosphere. These redox processes utilize different sulfur anions and the reactions are performed by the gene products of dsr operon from phylogenetically diverse sets of microorganisms. The operon is involved in the maintenance of environmental sulfur balance. Interestingly, the dsr operon is found to be present in both sulfur anion oxidizing and reducing microorganisms and in both types of organisms DsrAB protein complex plays a vital role. Though there are various reports regarding the genetics of dsr operon there are practically no reports dealing with the structural aspects of sulfur metabolism by dsr operon. In our present study, we tried to compare the mechanisms of sulfur anion oxidation and reduction by Allochromatium vinosum and Desulfovibrio vulgaris respectively through DsrAB protein complex. We analyzed the modes of bindings of sulfur anions to the DsrAB protein complex and observed that for sulfur anion oxidizers, sulfide and thiosulfate are the best substrates whereas for reducers sulfate and sulfite have the best binding abilities. We analyzed the binding interaction pattern of the DsrA and DsrB proteins while forming the DsrAB protein complexes in Desulfovibrio vulgaris and Allochromatium vinosum. To our knowledge this is the first report that analyzes the differences in binding patterns of sulfur substrates with DsrAB protein from these two microorganisms. This study would therefore be essential to predict the biochemical mechanism of sulfur anion oxidation and reduction by these two microorganisms i.e., Desulfovibrio vulgaris (sulfur anion reducer) and Allochromatium vinosum (sulfur anion oxidizer). Our observations also highlight the mechanism of sulfur geochemical cycle which has important implications in future study of sulfur metabolism as it has a huge application in waste remediation and production of industrial bio-products viz. vitamins, bio-polyesters and bio-hydrogen.

  12. Oxidative stress

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2012-01-01

    Full Text Available The unceasing need for oxygen is in contradiction to the fact that it is in fact toxic to mammals. Namely, its monovalent reduction can have as a consequence the production of short-living, chemically very active free radicals and certain non-radical agents (nitrogen-oxide, superoxide-anion-radicals, hydroxyl radicals, peroxyl radicals, singlet oxygen, peroxynitrite, hydrogen peroxide, hypochlorous acid, and others. There is no doubt that they have numerous positive roles, but when their production is stepped up to such an extent that the organism cannot eliminate them with its antioxidants (superoxide-dismutase, glutathione-peroxidase, catalase, transferrin, ceruloplasmin, reduced glutathion, and others, a series of disorders is developed that are jointly called „oxidative stress.“ The reactive oxygen species which characterize oxidative stress are capable of attacking all main classes of biological macromolecules, actually proteins, DNA and RNA molecules, and in particular lipids. The free radicals influence lipid peroxidation in cellular membranes, oxidative damage to DNA and RNA molecules, the development of genetic mutations, fragmentation, and the altered function of various protein molecules. All of this results in the following consequences: disrupted permeability of cellular membranes, disrupted cellular signalization and ion homeostasis, reduced or loss of function of damaged proteins, and similar. That is why the free radicals that are released during oxidative stress are considered pathogenic agents of numerous diseases and ageing. The type of damage that will occur, and when it will take place, depends on the nature of the free radicals, their site of action and their source. [Projekat Ministarstva nauke Republike Srbije, br. 173034, br. 175061 i br. 31085

  13. Chlorobaculum tepidum Modulates Amino Acid Composition in Response to Energy Availability, as Revealed by a Systematic Exploration of the Energy Landscape of Phototrophic Sulfur Oxidation.

    Science.gov (United States)

    Levy, Amalie T; Lee, Kelvin H; Hanson, Thomas E

    2016-11-01

    Microbial sulfur metabolism, particularly the formation and consumption of insoluble elemental sulfur (S(0)), is an important biogeochemical engine that has been harnessed for applications ranging from bioleaching and biomining to remediation of waste streams. Chlorobaculum tepidum, a low-light-adapted photoautolithotrophic sulfur-oxidizing bacterium, oxidizes multiple sulfur species and displays a preference for more reduced electron donors: sulfide > S(0) > thiosulfate. To understand this preference in the context of light energy availability, an "energy landscape" of phototrophic sulfur oxidation was constructed by varying electron donor identity, light flux, and culture duration. Biomass and cellular parameters of C. tepidum cultures grown across this landscape were analyzed. From these data, a correction factor for colorimetric protein assays was developed, enabling more accurate biomass measurements for C. tepidum, as well as other organisms. C. tepidum's bulk amino acid composition correlated with energy landscape parameters, including a tendency toward less energetically expensive amino acids under reduced light flux. This correlation, paired with an observation of increased cell size and storage carbon production under electron-rich growth conditions, suggests that C. tepidum has evolved to cope with changing energy availability by tuning its proteome for energetic efficiency and storing compounds for leaner times.

  14. Feeding low or pharmacological concentrations of zinc oxide changes the hepatic proteome profiles in weaned piglets.

    Directory of Open Access Journals (Sweden)

    Angelika Bondzio

    Full Text Available Pharmacological levels of zinc oxide can promote growth and health of weaning piglets, but the underlying molecular mechanisms are yet not fully understood. The aim of this study was to determine changes in the global hepatic protein expression in response to dietary zinc oxide in weaned piglets. Nine half-sib piglets were allocated to three dietary zinc treatment groups (50, 150, 2500 mg/kg dry matter. After 14 d, pigs were euthanized and liver samples taken. The increase in hepatic zinc concentration following dietary supplementation of zinc was accompanied by up-regulation of metallothionein mRNA and protein expression. Global hepatic protein profiles were obtained by two-dimensional difference gel electrophoresis following matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. A total of 15 proteins were differentially (P<0.05 expressed between groups receiving control (150 mg/kg or pharmacological levels of zinc (2500 mg/kg with 7 down- (e.g. arginase1, thiosulfate sulfurtransferase, HSP70 and 8 up-regulated (e.g. apolipoprotein AI, transferrin, C1-tetrahydrofolate synthase proteins. Additionally, three proteins were differentially expressed with low zinc supply (50 mg/kg Zn in comparison to the control diet. The identified proteins were mainly associated with functions related to cellular stress, transport, metabolism, and signal transduction. The differential regulation was evaluated at the mRNA level and a subset of three proteins of different functional groups was selected for confirmation by western blotting. The results of this proteomic study suggest that zinc affects important liver functions such as blood protein secretion, protein metabolism, detoxification and redox homeostasis, thus supporting the hypothesis of intermediary effects of pharmacological levels of zinc oxide fed to pigs.

  15. Feeding low or pharmacological concentrations of zinc oxide changes the hepatic proteome profiles in weaned piglets.

    Science.gov (United States)

    Bondzio, Angelika; Pieper, Robert; Gabler, Christoph; Weise, Christoph; Schulze, Petra; Zentek, Juergen; Einspanier, Ralf

    2013-01-01

    Pharmacological levels of zinc oxide can promote growth and health of weaning piglets, but the underlying molecular mechanisms are yet not fully understood. The aim of this study was to determine changes in the global hepatic protein expression in response to dietary zinc oxide in weaned piglets. Nine half-sib piglets were allocated to three dietary zinc treatment groups (50, 150, 2500 mg/kg dry matter). After 14 d, pigs were euthanized and liver samples taken. The increase in hepatic zinc concentration following dietary supplementation of zinc was accompanied by up-regulation of metallothionein mRNA and protein expression. Global hepatic protein profiles were obtained by two-dimensional difference gel electrophoresis following matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. A total of 15 proteins were differentially (P<0.05) expressed between groups receiving control (150 mg/kg) or pharmacological levels of zinc (2500 mg/kg) with 7 down- (e.g. arginase1, thiosulfate sulfurtransferase, HSP70) and 8 up-regulated (e.g. apolipoprotein AI, transferrin, C1-tetrahydrofolate synthase) proteins. Additionally, three proteins were differentially expressed with low zinc supply (50 mg/kg Zn) in comparison to the control diet. The identified proteins were mainly associated with functions related to cellular stress, transport, metabolism, and signal transduction. The differential regulation was evaluated at the mRNA level and a subset of three proteins of different functional groups was selected for confirmation by western blotting. The results of this proteomic study suggest that zinc affects important liver functions such as blood protein secretion, protein metabolism, detoxification and redox homeostasis, thus supporting the hypothesis of intermediary effects of pharmacological levels of zinc oxide fed to pigs.

  16. Genome Analysis of Thermosulfurimonas dismutans, the First Thermophilic Sulfur-Disproportionating Bacterium of the Phylum Thermodesulfobacteria

    Science.gov (United States)

    Mardanov, Andrey V.; Beletsky, Alexey V.; Kadnikov, Vitaly V.; Slobodkin, Alexander I.; Ravin, Nikolai V.

    2016-01-01

    Thermosulfurimonas dismutans S95T, isolated from a deep-sea hydrothermal vent is the first bacterium of the phylum Thermodesulfobacteria reported to grow by the disproportionation of elemental sulfur, sulfite, or thiosulfate with carbon dioxide as the sole carbon source. In contrast to its phylogenetically close relatives, which are dissimilatory sulfate-reducers, T. dismutans is unable to grow by sulfate respiration. The features of this organism and its 2,1 Mb draft genome sequence are described in this report. Genome analysis revealed that the T. dismutans genome contains the set of genes for dissimilatory sulfate reduction including ATP sulfurylase, the AprA and B subunits of adenosine-5′-phosphosulfate reductase, and dissimilatory sulfite reductase. The oxidation of elemental sulfur to sulfite could be enabled by APS reductase-associated electron transfer complex QmoABC and heterodisulfide reductase. The genome also contains several membrane-linked molybdopterin oxidoreductases that are thought to be involved in sulfur metabolism as subunits of thiosulfate, polysulfide, or tetrathionate reductases. Nitrate could be used as an electron acceptor and reduced to ammonium, as indicated by the presence of periplasmic nitrate and nitrite reductases. Autotrophic carbon fixation is enabled by the Wood–Ljungdahl pathway, and the complete set of genes that is required for nitrogen fixation is also present in T. dismutans. Overall, our results provide genomic insights into energy and carbon metabolism of chemolithoautotrophic sulfur-disproportionating bacterium that could be important primary producer in microbial communities of deep-sea hydrothermal vents. PMID:27379079

  17. The microbial sulfur cycle at extremely haloalkaline conditions of soda lakes.

    Science.gov (United States)

    Sorokin, Dimitry Y; Kuenen, J Gijs; Muyzer, Gerard

    2011-01-01

    Soda lakes represent a unique ecosystem with extremely high pH (up to 11) and salinity (up to saturation) due to the presence of high concentrations of sodium carbonate in brines. Despite these double extreme conditions, most of the lakes are highly productive and contain a fully functional microbial system. The microbial sulfur cycle is among the most active in soda lakes. One of the explanations for that is high-energy efficiency of dissimilatory conversions of inorganic sulfur compounds, both oxidative and reductive, sufficient to cope with costly life at double extreme conditions. The oxidative part of the sulfur cycle is driven by chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria (SOB), which are unique for soda lakes. The haloalkaliphilic SOB are present in the surface sediment layer of various soda lakes at high numbers of up to 10(6) viable cells/cm(3). The culturable forms are so far represented by four novel genera within the Gammaproteobacteria, including the genera Thioalkalivibrio, Thioalkalimicrobium, Thioalkalispira, and Thioalkalibacter. The latter two were only found occasionally and each includes a single species, while the former two are widely distributed in various soda lakes over the world. The genus Thioalkalivibrio is the most physiologically diverse and covers the whole spectrum of salt/pH conditions present in soda lakes. Most importantly, the dominant subgroup of this genus is able to grow in saturated soda brines containing 4 M total Na(+) - a so far unique property for any known aerobic chemolithoautotroph. Furthermore, some species can use thiocyanate as a sole energy source and three out of nine species can grow anaerobically with nitrogen oxides as electron acceptor. The reductive part of the sulfur cycle is active in the anoxic layers of the sediments of soda lakes. The in situ measurements of sulfate reduction rates and laboratory experiments with sediment slurries using sulfate, thiosulfate, or elemental sulfur as

  18. PREFACE: Semiconducting oxides Semiconducting oxides

    Science.gov (United States)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  19. Hydrogen sulfide and nitric oxide metabolites in the blood of free-ranging brown bears and their potential roles in hibernation.

    Science.gov (United States)

    Revsbech, Inge G; Shen, Xinggui; Chakravarti, Ritu; Jensen, Frank B; Thiel, Bonnie; Evans, Alina L; Kindberg, Jonas; Fröbert, Ole; Stuehr, Dennis J; Kevil, Christopher G; Fago, Angela

    2014-08-01

    During winter hibernation, brown bears (Ursus arctos) lie in dens for half a year without eating while their basal metabolism is largely suppressed. To understand the underlying mechanisms of metabolic depression in hibernation, we measured type and content of blood metabolites of two ubiquitous inhibitors of mitochondrial respiration, hydrogen sulfide (H2S) and nitric oxide (NO), in winter-hibernating and summer-active free-ranging Scandinavian brown bears. We found that levels of sulfide metabolites were overall similar in summer-active and hibernating bears but their composition in the plasma differed significantly, with a decrease in bound sulfane sulfur in hibernation. High levels of unbound free sulfide correlated with high levels of cysteine (Cys) and with low levels of bound sulfane sulfur, indicating that during hibernation H2S, in addition to being formed enzymatically from the substrate Cys, may also be regenerated from its oxidation products, including thiosulfate and polysulfides. In the absence of any dietary intake, this shift in the mode of H2S synthesis would help preserve free Cys for synthesis of glutathione (GSH), a major antioxidant found at high levels in the red blood cells of hibernating bears. In contrast, circulating nitrite and erythrocytic S-nitrosation of glyceraldehyde-3-phosphate dehydrogenase, taken as markers of NO metabolism, did not change appreciably. Our findings reveal that remodeling of H2S metabolism and enhanced intracellular GSH levels are hallmarks of the aerobic metabolic suppression of hibernating bears.

  20. Metagenomic Assembly of the Dominant Zetaproteobacteria in an Iron-oxidizing Hydrothermal Microbial Mat

    Science.gov (United States)

    Moyer, C. L.; Fullerton, H.

    2013-12-01

    Iron is the fourth most abundant element in the Earth's crust and is potentially one of the most abundant energy sources on the earth as an electron donor for chemolithoautotrophic growth coupled to Fe(II) oxidation. Despite the rapid abiotic oxidation rate of iron, many microbes have adapted to feeding off this fleeting energy source. One such bacterial class is the Zetaproteobacteria. Iron-dominated microbial mat material was collected with a small-scale syringe sampler from Loihi Seamount, Hawaii. From this sample, gDNA was extracted and prepared for paired-end Illumina sequencing. Reconstruction of SSU rDNA genes using EMERGE allowed for comparison to previous SSU rDNA surveys. Clone libraries and qPCR show these microbial mats to be dominated by Zetaproteobacteria. Results from our in silico reconstruction confirm these initial findings. RDP classification of the EMERGE reconstructed sequences resulted in 44% of the community being identified as Zetaproteobacteria. The most abundant SSU rDNA has 99% similarity to Zeta OTU-2, and only a 94% similarity to M. ferrooxidans PV-1. Zeta OTU-2 has been shown to be the most cosmopolitan population in iron-dominated hydrothermal systems from across Pacific Ocean. Metagenomic assembly has resulted in many contigs with high identity to M. ferrooxidans as identified, by BLAST. However, with large differences in SSU rRNA similarity, M. ferrooxidans PV-1 is not an adequate reference. Current work is focusing on reconstruction of the dominant microbial mat member, without the use of a reference genome through an iterative assembly approach. The resulting 'pan-genome' will be compared to other Zetaproteobacteria (at the class level) and the functional ecology of this cosmopolitan microbial mat community member will be extrapolated. Thus far, we have detected multiple housekeeping genes involved in DNA replication, transcription and translation. The most abundant metabolic gene we have found is Aconitase, a key enzyme in the

  1. Engineering Bacterial Thiosulfate and Tetrathionate Sensors for Detecting Gut Inflammation

    Science.gov (United States)

    2017-04-03

    known geneti- cally encoded tetrathionate sensor is the TtrSR two-component system (TCS) from S. typhimurium (Hensel et al, 1999; Price -Carter et al...presence of tetrathionate. Phosphorylated TtrR (TtrR~P) activates transcription of the tetrathionate reductase operon, ttrBCA, via the ttrB promoter ...PttrB). However, PttrB is repressed by O2 and nitrate via the global regulator FNR and an unknown pathway, respectively ( Price -Carter et al, 2001

  2. Thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

    2011-01-01

    A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

  3. Photo-oxidation catalysts

    Science.gov (United States)

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  4. Biochemical, oxidative and histological changes caused by sub-acute oral exposure of some synthetic cyanogens in rats: ameliorative effect of α-ketoglutarate.

    Science.gov (United States)

    Bhattacharya, Rahul; Rao, Pooja; Singh, Poonam; Yadav, Shiv Kumar; Upadhyay, Preeti; Malla, Sandhya; Gujar, Niranjan Laxman; Lomash, Vinay; Pant, Satish Chandra

    2014-05-01

    Time-dependent cyanide generation and acute toxicity of six different cyanogens were reported earlier, out of which malononitrile (MCN), propionitrile (PCN), and sodium nitroprusside (SNP) were found to be very toxic. We report here 14 d sub-acute toxicity of MCN, PCN, and SNP (oral; 1/10 LD50 daily) in female rats, and its amelioration by α-ketoglutarate (α-KG; oral; 5.26 mmol/kg; +5 min), a potential cyanide antidote. Significant decrease in white blood cells (PCN, SNP), platelets count (PCN), and blood glucose levels (MCN, PCN, SNP) was accompanied by elevated levels of alanine aminotransferase, lactate dehydrogenase (MCN, PCN, SNP), and aspartate aminotransferase (PCN, SNP). Oxidative damage was evidenced by diminished total antioxidant status in plasma and enhanced malondialdehyde levels in liver and kidney. This was accompanied by diminished levels of reduced glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase in the brain, liver and kidney. We also observed increased levels of blood cyanide and thiocyanate, together with inhibition of cytochrome c oxidase and thiosulfate-sulfur transferase activities in total brain and liver homogenate, respectively. Cyanogens also produced several histological changes in all the organs studied. Post-treatment with α-KG significantly abrogated the toxicity of cyanogens, indicating its utility as an antidote for long-term cyanogen exposure.

  5. Oxidative stress and myocarditis.

    Science.gov (United States)

    Tada, Yuko; Suzuki, Jun-Ichi

    2016-01-01

    Reactive oxygen species (ROS) such as superoxide anion and hydrogen peroxide are produced highly in myocarditis. ROS, which not only act as effectors for pathogen killing but also mediate signal transduction in the stress responsive pathways, are closely related with both innate and adaptive immunity. On the other hand, oxidative stress overwhelming the capacity of anti-oxidative system generated in severe inflammation has been suggested to damage tissues and exacerbate inflammation. Oxidative stress worsens the autoimmunological process of myocarditis, and suppression of the anti-oxidative system and long-lasting oxidative stress could be one of the pathological mechanisms of cardiac remodeling leading to inflammatory cardiomyopathy. Oxidative stress is considered to be one of the promising treatment targets of myocarditis. Evidences of anti-oxidative treatments in myocarditis have not been fully established. Basic strategies of anti-oxidative treatments include inhibition of ROS production, activation of anti-oxidative enzymes and elimination of generated free radicals. ROS are produced by mitochondrial respiratory chain reactions and enzymes including NADPH oxidases, cyclooxygenase, and xanthine oxidase. Other systems involved in inflammation and stress response, such as NF-κB, Nrf2/Keap1, and neurohumoral factors also influence oxidative stress in myocarditis. The efficacy of anti-oxidative treatments could also depend on the etiology and the phases of myocarditis. We review in this article the pathological significance of ROS and oxidative stress, and the potential anti-oxidative treatments in myocarditis.

  6. Zinc oxide overdose

    Science.gov (United States)

    Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used ... prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of ...

  7. Bridged graphite oxide materials

    Science.gov (United States)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  8. Nitrous Oxide Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nitrous Oxide (N20) flux is the net rate of nitrous oxide exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS...

  9. Oxidative Stress in Neurodegeneration

    Directory of Open Access Journals (Sweden)

    Varsha Shukla

    2011-01-01

    Full Text Available It has been demonstrated that oxidative stress has a ubiquitous role in neurodegenerative diseases. Major source of oxidative stress due to reactive oxygen species (ROS is related to mitochondria as an endogenous source. Although there is ample evidence from tissues of patients with neurodegenerative disorders of morphological, biochemical, and molecular abnormalities in mitochondria, it is still not very clear whether the oxidative stress itself contributes to the onset of neurodegeneration or it is part of the neurodegenerative process as secondary manifestation. This paper begins with an overview of how oxidative stress occurs, discussing various oxidants and antioxidants, and role of oxidative stress in diseases in general. It highlights the role of oxidative stress in neurodegenerative diseases like Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis. The last part of the paper describes the role of oxidative stress causing deregulation of cyclin-dependent kinase 5 (Cdk5 hyperactivity associated with neurodegeneration.

  10. Electrolytic oxidation of anthracite

    Science.gov (United States)

    Senftle, F.E.; Patton, K.M.; Heard, I.

    1981-01-01

    An anthracite slurry can be oxidized only with difficulty by electrolytic methods in which aqueous electrolytes are used if the slurry is confined to the region of the anode by a porous pot or diaphragm. However, it can be easily oxidized if the anthracite itself is used as the anode. No porous pot or diaphragm is needed. Oxidative consumption of the coal to alkali-soluble compounds is found to proceed preferentially at the edges of the aromatic planes. An oxidation model is proposed in which the chief oxidants are molecular and radical species formed by the electrolytic decomposition of water at the coal surface-electrolyte interface. The oxidation reactions proposed account for the opening of the aromatic rings and the subsequent formation of carboxylic acids. The model also explains the observed anisotropic oxidation and the need for the porous pot or diaphragm used in previous studies of the oxidation of coal slurries. ?? 1981.

  11. Oxidative Stress in BPH

    Directory of Open Access Journals (Sweden)

    Murat Savas

    2009-01-01

    The present study has shown that there were not relationship between potency of oxidative stress and BPH. Further well designed studies should be planned to find out whether the oxidative stress-related parameters play role in BPH as an interesting pathology in regard of the etiopathogenesis. Keywords: benign prostatic hyperplasia, oxidative stress, prostate

  12. All-Oxide Photovoltaics.

    Science.gov (United States)

    Rühle, Sven; Anderson, Assaf Y; Barad, Hannah-Noa; Kupfer, Benjamin; Bouhadana, Yaniv; Rosh-Hodesh, Eli; Zaban, Arie

    2012-12-20

    Recently, a new field in photovoltaics (PV) has emerged, focusing on solar cells that are entirely based on metal oxide semiconductors. The all-oxide PV approach is very attractive due to the chemical stability, nontoxicity, and abundance of many metal oxides that potentially allow manufacturing under ambient conditions. Already today, metal oxides (MOs) are widely used as components in PV cells such as transparent conducting front electrodes or electron-transport layers, while only very few MOs have been used as light absorbers. In this Perspective, we review recent developments of all-oxide PV systems, which until today were mostly based on Cu2O as an absorber. Furthermore, ferroelectric BiFeO3-based PV systems are discussed, which have recently attracted considerable attention. The performance of all-oxide PV cells is discussed in terms of general PV principles, and directions for progress are proposed, pointing toward the development of novel metal oxide semiconductors using combinatorial methods.

  13. Wet oxidation of quinoline

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Kilen, H.H.

    1998-01-01

    The influence of oxygen pressure (0.4 and 2 MPa). reaction time (30 and 60 min) and temperature (260 and 280 degrees C) on the wet oxidation of quinoline has been studied. The dominant parameters for the decomposition of quinoline were oxygen pressure and reaction temperature. whereas the reaction...... time was less important within the range studied. Nitrifying bacteria were used to measure the inhibition from wet oxidative-treated samples to study the effect of the (wet oxidation) reaction conditions. Wet oxidation made quinoline more toxic to Nitrosomonas. This was observed for Nitrobacter as well....... The combined wet oxidation and biological treatment of reaction products resulted in 91% oxidation of the parent compound to CO2 and water. Following combined wet oxidation and biological treatment the sample showed low toxicity towards Nitrosomonas and no toxicity towards Nitrobacter. (C) 1998 Elsevier...

  14. Oxidation Resistant Graphite Studies

    Energy Technology Data Exchange (ETDEWEB)

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

  15. Subsurface Uranium Fate and Transport: Integrated Experiments and Modeling of Coupled Biogeochemical Mechanisms of Nanocrystalline Uraninite Oxidation by Fe(III)-(hydr)oxides - Project Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Peyton, Brent M. [Montana State Univ., Bozeman, MT (United States); Timothy, Ginn R. [Univ. of California, Davis, CA (United States); Sani, Rajesh K. [South Dakota School of Mines and Technology, Rapid City, SD (United States)

    2013-08-14

    Subsurface bacteria including sulfate reducing bacteria (SRB) reduce soluble U(VI) to insoluble U(IV) with subsequent precipitation of UO2. We have shown that SRB reduce U(VI) to nanometer-sized UO2 particles (1-5 nm) which are both intra- and extracellular, with UO2 inside the cell likely physically shielded from subsequent oxidation processes. We evaluated the UO2 nanoparticles produced by Desulfovibrio desulfuricans G20 under growth and non-growth conditions in the presence of lactate or pyruvate and sulfate, thiosulfate, or fumarate, using ultrafiltration and HR-TEM. Results showed that a significant mass fraction of bioreduced U (35-60%) existed as a mobile phase when the initial concentration of U(VI) was 160 µM. Further experiments with different initial U(VI) concentrations (25 - 900 M) in MTM with PIPES or bicarbonate buffers indicated that aggregation of uraninite depended on the initial concentrations of U(VI) and type of buffer. It is known that under some conditions SRB-mediated UO2 nanocrystals can be reoxidized (and thus remobilized) by Fe(III)-(hydr)oxides, common constituents of soils and sediments. To elucidate the mechanism of UO2 reoxidation by Fe(III) (hydr)oxides, we studied the impact of Fe and U chelating compounds (citrate, NTA, and EDTA) on reoxidation rates. Experiments were conducted in anaerobic batch systems in PIPES buffer. Results showed EDTA significantly accelerated UO2 reoxidation with an initial rate of 9.5 M day-1 for ferrihydrite. In all cases, bicarbonate increased the rate and extent of UO2 reoxidation with ferrihydrite. The highest rate of UO2 reoxidation occurred when the chelator promoted UO2 and Fe(III) (hydr)oxide dissolution as demonstrated with EDTA. When UO2 dissolution did not occur, UO2 reoxidation likely proceeded through an aqueous Fe(III) intermediate as observed for both NTA and

  16. Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

    Science.gov (United States)

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

  17. Oxidizer Scoping Studies

    Energy Technology Data Exchange (ETDEWEB)

    Chancellor, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-07

    The purpose of this report is to present the results of the acceptable knowledge (AK) review of oxidizers present in active waste streams, provide a technical analysis of the oxidizers, and report the results of the scoping study testing. This report will determine the fastest burning oxidizer to be used in the development of a Test Plan for Preparation and Testing of Sorbents Mixed with Oxidizer found in Transuranic Waste (DWT-TP-001). The companion report, DWT-RPT-002, Sorbent Scoping Studies, contains similar information for sorbents identified during the AK review of TRU waste streams. The results of the oxidizer and sorbent scoping studies will be used to inform the QL1 test plan. The QL1 test results will support the development of a basis of knowledge document that will evaluate oxidizing chemicals and sorbents in TRU waste and provide guidance for treatment.

  18. Metal oxides as photocatalysts

    Directory of Open Access Journals (Sweden)

    Mohammad Mansoob Khan

    2015-09-01

    Full Text Available Metal oxides are of great technological importance in environmental remediation and electronics because of their capability to generate charge carriers when stimulated with required amount of energy. The promising arrangement of electronic structure, light absorption properties, and charge transport characteristics of most of the metal oxides has made possible its application as photocatalyst. In this article definition of metal oxides as photocatalyst, structural characteristics, requirements of the photocatalyst, classification of photocatalysts and the mechanism of the photocatalytic process are discussed.

  19. METAL OXIDE NANOPARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

    2007-10-01

    This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

  20. Molecular water oxidation catalysis

    CERN Document Server

    Llobet, Antoni

    2014-01-01

    Photocatalytic water splitting is a promising strategy for capturing energy from the sun by coupling light harvesting and the oxidation of water, in order to create clean hydrogen fuel. Thus a deep knowledge of the water oxidation catalysis field is essential to be able to come up with useful energy conversion devices based on sunlight and water splitting. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes presents a comprehensive and state-of-the-art overview of water oxidation catalysis in homogeneous phase, describing in detail the most importan

  1. Sulfur metabolism in the extreme acidophile Acidithiobacillus caldus

    Directory of Open Access Journals (Sweden)

    Stefanie eMangold

    2011-02-01

    Full Text Available Given the challenges to life at low pH, an analysis of inorganic sulfur compound oxidation was initiated in the chemolithoautotrophic extremophile Acidithiobacillus caldus. A. caldus is able to metabolize elemental sulfur and a broad range of inorganic sulfur compounds. It has been implicated in the production of environmentally damaging acidic solutions as well as participating in industrial bioleaching operations where it forms part of microbial consortia used for the recovery of metal ions. Based upon the recently published A. caldus type strain genome sequence, a bioinformatic reconstruction of elemental sulfur and inorganic sulfur compound metabolism predicted genes included: sulfide quinone reductase (sqr, tetrathionate hydrolase (tth, two sox gene clusters potentially involved in thiosulfate oxidation (soxABXYZ, sulfur oxygenase reductase (sor, and various electron transport components. RNA transcript profiles by semi-quantitative reverse transcription PCR suggested up-regulation of sox genes in the presence of tetrathionate. Extensive gel based proteomic comparisons of total soluble and membrane enriched protein fractions during growth on elemental sulfur and tetrathionate identified differential protein levels from the two Sox clusters as well as several chaperone and stress proteins up-regulated in the presence of elemental sulfur. Proteomics results also suggested the involvement of heterodisulfide reductase (HdrABC in A. caldus inorganic sulfur compound metabolism. A putative new function of Hdr in acidophiles is discussed. Additional proteomic analysis evaluated protein expression differences between cells grown attached to solid, elemental sulfur versus planktonic cells. This study has provided insights into sulfur metabolism of this acidophilic chemolithotroph and gene expression during attachment to solid elemental sulfur.

  2. Detecting Organic Compounds Released from Iron Oxidizing Bacteria using Sample Analysis at Mars (SAM) Like Instrument Protocols

    Science.gov (United States)

    Glavin, D. P.; Popa, R.; Martin, M. G.; Freissinet, C.; Fisk, M. R.; Dworkin, J. P.; Mahaffy, P. R.

    2012-01-01

    Mars is a planet of great interest for Astrobiology since its past environmental conditions are thought to have been favourable for the emergence life. At present, the Red Planet is extremely cold and dry and the surface is exposed to intense UV and ionizing radiation, conditions generally considered to be incompatible with life as we know it on Earth. It was proposed that the shallow subsurface of Mars, where temperatures can be above freezing and liquid water can exist on rock surfaces, could harbor chemolithoautotrophic bacteria such as the iron oxidizing microorganism Pseudomonas sp. HerB. The Mars Science Laboratory (MSL) mission will provide the next opportunity to carry out in situ measurements for organic compounds of possible biological origin on Mars. One instrument onboard MSL, called the Sample Analysis at Mars (SAM) instrument suite, will carry out a broad and sensitive search for organic compounds in surface samples using either high temperature pyrolysis or chemical extraction followed by gas chromatography mass spectrometry. We present gas chromatograph mass spectrometer (GC/MS) data on crushed olivine rock powders that have been inoculated with Pseudomonas sp. HerB at different concentrations ranging from approx 10(exp 2) to 10(exp 7) cells per gram. The inoculated olivine samples were heated under helium carrier gas flow at 500 C and the pyrolysis products concentrated using a SAM-like hydrocarbon trap set at -20 C followed by trap heating and analysis by GC/Ms. In addition, the samples were also extracted using a low temperature "one-pot" chemical extraction technique using N-methyl, N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) as the silylating agent prior to GC/MS analysis. We identified several aldehydes, thiols, and alkene nitriles after pyrolysis GC/MS analysis of the bacteria that were not found in the olivine control samples that had not been inoculated with bacteria. The distribution of pyrolysis products extracted from the

  3. Pyrite oxidation by microbial consortia

    Science.gov (United States)

    Bostick, B. C.; Revill, K. L.; Doyle, C.; Kendelewicz, T.; Brown, G. E.; Spormann, A. M.; Fendorf, S.

    2003-12-01

    Acid mine drainage (AMD) is formed through pyrite oxidation, which produces acidity and releases toxic metals associated with pyrite and other sulfide minerals. Microbes accelerate pyrite oxidation markedly, thereby playing a major role in the production of AMD. Here, we probe pyrite oxidation by consortia of Thiobacillus ferrooxidans and thiooxidans using surface-sensitive photoelectron spectroscopy and X-ray absorption spectroscopy and compare them with surfaces oxidized through chemical and single species cultures. Microbial oxidation resulted in the formation of distinct oxidized surface species distributed non-uniformly over the pyrite surface; consortia produced a surface both more heterogeneous and more oxidized. In contrast, chemical oxidation proceeds without the build-up of passivating oxidation products. Surface morphology was not correlated with sites of nucleation or oxidation in any obvious manner. These results demonstrate that microbial oxidation occurs through a similar mechanism to chemical oxidation, but that the presence of complex microbial communities may impact the manner by which pyrite oxidation proceeds.

  4. Catalytic process for formaldehyde oxidation

    Science.gov (United States)

    Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); D'Ambrosia, Christine M. (Inventor)

    1996-01-01

    Disclosed is a process for oxidizing formaldehyde to carbon dioxide and water without the addition of energy. A mixture of formaldehyde and an oxidizing agent (e.g., ambient air containing formaldehyde) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.

  5. Markers of protein oxidation

    DEFF Research Database (Denmark)

    Headlam, Henrietta A; Davies, Michael Jonathan

    2004-01-01

    Exposure of proteins to radicals in the presence of O2 gives both side-chain oxidation and backbone fragmentation. These processes can be interrelated, with initial side-chain oxidation giving rise to backbone damage via transfer reactions. We have shown previously that alkoxyl radicals formed on...

  6. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  7. Reducible oxide based catalysts

    Science.gov (United States)

    Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

    2010-04-06

    A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

  8. RNA modifications by oxidation

    DEFF Research Database (Denmark)

    Poulsen, Henrik E; Specht, Elisabeth; Broedbaek, Kasper

    2012-01-01

    The past decade has provided exciting insights into a novel class of central (small) RNA molecules intimately involved in gene regulation. Only a small percentage of our DNA is translated into proteins by mRNA, yet 80% or more of the DNA is transcribed into RNA, and this RNA has been found...... to encompass various classes of novel regulatory RNAs, including, e.g., microRNAs. It is well known that DNA is constantly oxidized and repaired by complex genome maintenance mechanisms. Analogously, RNA also undergoes significant oxidation, and there are now convincing data suggesting that oxidation......, and the consequent loss of integrity of RNA, is a mechanism for disease development. Oxidized RNA is found in a large variety of diseases, and interest has been especially devoted to degenerative brain diseases such as Alzheimer disease, in which up to 50-70% of specific mRNA molecules are reported oxidized, whereas...

  9. Protein oxidation in aquatic foods

    DEFF Research Database (Denmark)

    Baron, Caroline P.

    2014-01-01

    The chapter discusses general considerations about protein oxidation and reviews the mechanisms involved in protein oxidation and consequences of protein oxidation on fish proteins. It presents two case studies, the first deals with protein and lipid oxidation in frozen rainbow trout, and the sec......The chapter discusses general considerations about protein oxidation and reviews the mechanisms involved in protein oxidation and consequences of protein oxidation on fish proteins. It presents two case studies, the first deals with protein and lipid oxidation in frozen rainbow trout...... oxidation. The protein carbonyl group measurement is the widely used method for estimating protein oxidation in foods and has been used in fish muscle. The chapter also talks about the impact of protein oxidation on protein functionality, fish muscle texture, and food nutritional value. Protein oxidation...... may not only induce quality losses but may be desirable in some type of foods, such as salted herring....

  10. Highly oxidized graphene oxide and methods for production thereof

    Energy Technology Data Exchange (ETDEWEB)

    Tour, James M.; Kosynkin, Dmitry V.

    2016-08-30

    A highly oxidized form of graphene oxide and methods for production thereof are described in various embodiments of the present disclosure. In general, the methods include mixing a graphite source with a solution containing at least one oxidant and at least one protecting agent and then oxidizing the graphite source with the at least one oxidant in the presence of the at least one protecting agent to form the graphene oxide. Graphene oxide synthesized by the presently described methods is of a high structural quality that is more oxidized and maintains a higher proportion of aromatic rings and aromatic domains than does graphene oxide prepared in the absence of at least one protecting agent. Methods for reduction of graphene oxide into chemically converted graphene are also disclosed herein. The chemically converted graphene of the present disclosure is significantly more electrically conductive than is chemically converted graphene prepared from other sources of graphene oxide.

  11. Lignite oxidative desulphurization

    Institute of Scientific and Technical Information of China (English)

    Volodymyr Gunka; Serhiy Pyshyev

    2014-01-01

    The process of lignite desulphurization via its treatment by an oxidant (air or air–steam mixture) has been studied. The research objective was useful determination of steam application in oxidative lignite desulphurization. It has been proved that the water steam should be included in the oxidant composition to increase the hydrogen sulphide and combustible constituent content in the gases obtained during the processes under research. The impact of factors which affect the reactions between solid (in our case–lignite) and gaseous reagent (oxidant, i.e. air and or air–steam mixture) upon the research process has been investigated, if these reactions occur in the kinetic area. Such factors are linear rate of oxidant movement and coal grain size. The values of oxidant movement linear rate and coal grain size, which the reaction transfer from pyrite sulphur and organic content of lignite from diffusion into kinetic area occurs by, have been determined. Under these‘‘transfer’’ conditions, the values of coefficients of oxidant mass transfer (b, m/s) as well as Sherwood criteria and boiling layer differences have been calculated.

  12. Paraffin Oxidation Studies

    Directory of Open Access Journals (Sweden)

    Mrs. S. J. Purohit

    2013-02-01

    Full Text Available The oxidation of paraffin has been studied with keen interest by several workers from all over the world; as oxidation leads to the introduction of various functional groups in hydrocarbon chains. Processes involving the Oxidation of Paraffin’s in the liquid phase, using air or oxygen are of great importance to industrialized economies because of their role in converting petroleum hydrocarbon feed stocks such as alkanes, olefins and aromatics into industrial organic chemicals important in the polymer, petrochemicals ,cosmetics and detergent industries. The oxidation leads predominantly to the formation of secondary alcohols consisting of a mixture of all possible isomers with the same number of carbon atoms in the molecules as the initial hydrocarbons. The secondary alcohols which are oxidation products of paraffin exhibit excellent hydrolytic, oxidative and color stability, because of the nature of their branching. These alcohols have lower melting points than straight chain alcohols of corresponding length, while retaining their high temperature stability. The oxidation of paraffin wax to fatty acids is carried out in temperature range 110 0C- 140 0C. Paraffin oxidation which is carried out by ALFOL, Oxo-processes, are high temperature, high pressure processes which utilize expensive catalysts, making them energy intensive as well as expensive. The maximum conversion achieved yet by existing processes is 15�0for a batch time of 4 hours. A cheaper alternative in this article has been studied, in which paraffin Oxidation has been carried out in a foam reactor at moderate temperature and pressure with suitable catalyst , the output of the products is increased up to 62%.

  13. Low-temperature hydration, oxidation and hydrogen production from Oman peridotite

    Science.gov (United States)

    Miller, H. M.; Mayhew, L.; Templeton, A. S.

    2013-12-01

    Peridotite in the shallow subsurface undergoes hydration and oxidation (serpentinization) during reactions with percolating fluids, generating hydrogen gas and releasing magnesium, iron, and calcium into solution. In the presence of fluids enriched in dissolved carbon dioxide, extensive precipitation of carbonate minerals occurs. This reaction has large-scale implications for mitigating climate change by providing a stable, geological carbon repository. The Samail Ophiolite in Oman contains large quantities of ultramafic rocks that are currently undergoing serpentinization at low temperatures (30°C) and forming carbonate minerals. The production of hydrogen gas provides an electron donor for subsurface chemolithoautotrophic life which can contribute to carbon cycling in the subsurface as microorganisms utilize carbon dioxide as an inorganic carbon source. Serpentinization reactions require the oxidation of Fe (II) to Fe (III) to reduce water to H2, but the mechanisms of hydrogen generation in low-temperature systems is poorly characterized. To address this question, we conducted low temperature (100°C) water-rock reactions with Oman peridotite, measured H2 and characterized the speciation of Fe-bearing minerals before and after water-rock interaction using micro-X-ray Absorption Near Edge Structure (μXANES) spectra obtained from Stanford Synchrotron Radiation Lightsource. The experimental water-rock reactions produce H2 at a pH of 9, which corresponds with observations of ultrabasic springs in the Samail ophiolite and the presence of H2 in these spring waters. Significant hydrogen production occurs for two and a half months of reaction, peaking at 400 nmol/gram of reacted peridotite and then steadily decreases with time. These maximum values of hydrogen production from Oman peridotite are greater than observed by our laboratory and others during aqueous alteration of San Carlos peridotite and isolated pyroxenes and olivines (e.g. Mayhew et al. 2013 [1]). The

  14. Mercuric oxide poisoning

    Science.gov (United States)

    ... of mercury salt. There are different types of mercury poisonings . This article discusses poisoning from swallowing mercuric oxide. ... Disinfectants Fungicides There have been reports of inorganic mercury poisoning from the use of skin-lightening creams. Note: ...

  15. CATALYTIC ENANTIOSELECTIVE ALLYLIC OXIDATION

    NARCIS (Netherlands)

    Rispens, Minze T.; Zondervan, Charon; Feringa, Bernard

    1995-01-01

    Several chiral Cu(II)-complexes of cyclic amino acids catalyse the enantioselective allylic oxidation of cyclohexene to cyclohexenyl esters. Cyclohexenyl propionate was obtained in 86% yield with e.e.'s up to 61%.

  16. Cathodoluminescence of uranium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Winer, K.; Colmenares, C.; Wooten, F.

    1984-08-09

    The cathodoluminescence of uranium oxide surfaces prepared in-situ from clean uranium exposed to dry oxygen was studied. The broad asymmetric peak observed at 470 nm is attributed to F-center excitation.

  17. Fatty Acid Oxidation Disorders

    Science.gov (United States)

    ... acid oxidation disorders are tested for in newborn screening? The March of Dimes recommends that all babies ... in behavior Diarrhea, nausea (feeling sick to your stomach) and throwing up Drowsiness Fever Fussiness Little appetite ...

  18. Periodontal treatment decreases plasma oxidized LDL level and oxidative stress.

    Science.gov (United States)

    Tamaki, Naofumi; Tomofuji, Takaaki; Ekuni, Daisuke; Yamanaka, Reiko; Morita, Manabu

    2011-12-01

    Periodontitis induces excessive production of reactive oxygen species in periodontal lesions. This may impair circulating pro-oxidant/anti-oxidant balance and induce the oxidation of low-density lipoprotein (LDL) in blood. The purpose of this study was to monitor circulating oxidized LDL and oxidative stress in subjects with chronic periodontitis following non-surgical periodontal treatment. Plasma levels of oxidized LDL and oxidative stress in 22 otherwise healthy non-smokers with chronic periodontitis (mean age 44.0 years) were measured at baseline and at 1 and 2 months after non-surgical periodontal treatment. At baseline, chronic periodontitis patients had higher plasma levels of oxidized LDL and oxidative stress than healthy subjects (p surgical periodontal treatment were effective in decreasing oxLDL, which was positively associated with a reduction in circulating oxidative stress.

  19. Isolation and Identification of Hydrogen-oxidizing Bacteria in Medicago sativa Rhizosphere%紫花苜蓿根际氢氧化细菌的分离与鉴定

    Institute of Scientific and Technical Information of China (English)

    付博; 王卫卫; 郝莹; 王莉娟; 唐明; 陈兴都

    2009-01-01

    利用气体循环培养体系从陕西乾县HUP-豆科植物紫花苜蓿(Medicago sativa)根际土壤中分离获得37株细菌.菌株氧化氢能力测定结果表明,8株菌氧化氢和自养生长能力较强,初步确定为氢氧化细菌类群;根据其形态特征、培养特征和生理生化特性,鉴定为7个不同属:假单胞菌属(Pseudomonas)、邻单胞菌属(Plesiomonas)、脂肪杆菌属(Pimelobacter)、黄色杆菌属(Xanthobacter)、勒米诺氏菌属(Leminorella)、地杆菌属(Terrabacter)和稀有杆菌属(Rarobacter);其中氧化氢能力最强的优势菌株WMQ-7 16S rDNA序列(GenBank登录号为EU807744)长度为1 451bp,GC含量为53.8%,其核苷酸序列与假单胞菌属同源性高于99%,在系统发育树上位于同一分支,将WMQ-7菌株鉴定为假单胞菌属(Pseudomonas).图2表5参16%Gas-cycle incubation system was used to enrich the Medicago sativa rhizosphere soil collected in Shaanxi Province, China and 37 strains of bacteria were isolated. Among them, 8 stains had stronger ability to oxidize hydrogen and could grow chemolithoautotrophically, so they were preliminarily identified as hydrogen-oxidizing bacteria. According to their cells, colony forms and biochemical characteristics, the 8 strains were identified as Pseudomonas, Plesiomonas, Pimelobacter, Xanthobacter, Leminorella, Terrabacter and Rarobacte. Strain WMQ-7 had the strongest ability to oxidize hydrogen, and its 16S rDNA sequence (GenBank accession number EU807744) was 1 451 bp and GC content was 53.8%. Strain WMQ-7 was clustered together with Pseuclomonas in phylogenic tree, with the sequence identity of 99%, Therefore, strain WMQ-7 was identified as Pseudomonas. Fig 2, Tab 5, Ref 16

  20. Reduction property of rare earth oxide doped molybdenum oxide

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Rare earth oxide doped molybdenum powders were prepared by the reduction of rare earth nitrites doped MoO3. The effect of rare earth oxide on the reduction behavior of molybdenum oxide had been studied by means of Temperature Programmed Reduction (TPR), thermal analysis, X-ray diffraction. Doping rare earth oxide in the powder could lower the reduction temperature of molybdenum oxide and decrease the particle size of molybdenum. The mechanism for the effects had been discussed in this paper.

  1. Silver(II) Oxide or Silver(I,III) Oxide?

    Science.gov (United States)

    Tudela, David

    2008-01-01

    The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

  2. Pyrite oxidation by sulfolobus acidocaldarius

    Energy Technology Data Exchange (ETDEWEB)

    Tobita, M.; Yokozeki, M.; Nishikawa, N.; Kawakami, Y. (Institute of Research and Innovation, Kashiwa (Japan). Dept. of Biotechnology)

    1994-04-01

    Two strains of Sulfolobus acidocaldarius, a thermoacidophilic archaebacterium, were examined for their pyrite-oxidizing ability. S. acidocaldarius ATCC 33909 was shown to possess iron-oxidizing activity by ferrous sulfate oxidizing experiments, but S. acidocaldarius No. 7 did not have it. Pyrite-oxidizing rate of S. acidocaldarius ATCC 33909 was 1.6-fold higher than that of strain 7 though they had a similar level of self-oxidizing ability. These results show that the iron-oxidizing activity accelerates pyrite oxidation.

  3. Staphylococcal response to oxidative stress

    Directory of Open Access Journals (Sweden)

    Rosmarie eGaupp

    2012-03-01

    Full Text Available Staphylococci are a versatile genus of bacteria that are capable of causing acute and chronic infections in diverse host species. The success of staphylococci as pathogens is due in part to their ability to mitigate endogenous and exogenous oxidative and nitrosative stress. Endogenous oxidative stress is a consequence of life in an aerobic environment; whereas, exogenous oxidative and nitrosative stress are often due to the bacteria’s interaction with host immune systems. To overcome the deleterious effects of oxidative and nitrosative stress, staphylococci have evolved protection, detoxification, and repair mechanisms that are controlled by a network of regulators. In this review, we summarize the cellular targets of oxidative stress, the mechanisms by which staphylococci sense oxidative stress and damage, oxidative stress protection and repair mechanisms, and regulation of the oxidative stress response. When possible, special attention is given to how the oxidative stress defense mechanisms help staphylococci control oxidative stress in the host.

  4. Enargite oxidation: A review

    Science.gov (United States)

    Lattanzi, Pierfranco; Da Pelo, Stefania; Musu, Elodia; Atzei, Davide; Elsener, Bernhard; Fantauzzi, Marzia; Rossi, Antonella

    2008-01-01

    Enargite, Cu 3AsS 4, is common in some deposit types, e.g. porphyry systems and high sulphidation epithermal deposits. It is of environmental concern as a potential source of arsenic. In this communication, we review the current knowledge of enargite oxidation, based on the existing literature and our own original data. Explicit descriptions of enargite oxidation in natural environments are scarce. The most common oxidized alteration mineral of enargite is probably scorodite, FeAsO 4.2H 2O, with iron provided most likely by pyrite, a phase almost ubiquitously associated with enargite. Other secondary minerals after enargite include arsenates such as chenevixite, Cu 2Fe 2(AsO 4) 2(OH) 4.H 2O, and ceruleite, Cu 2Al 7(AsO 4) 4.11.5H 2O, and sulphates such as brochantite, Cu 4(SO 4)(OH) 6, and posnjakite, Cu 4(SO 4)(OH) 6·H 2O. Detailed studies of enargite field alteration at Furtei, Sardinia, suggest that most alteration occurs through dissolution, as testified by the appearance of etch pits at the surface of enargite crystals. However, apparent replacement by scorodite and cuprian melanterite was observed. Bulk oxidation of enargite in air is a very slow process. However, X-ray photoelectron spectroscopy (XPS) reveals subtle surface changes. From synchrotron-based XPS it was suggested that surface As atoms react very fast, presumably by forming bonds with oxygen. Conventional XPS shows the formation, on aged samples, of a nanometer-size alteration layer with an appreciably distinct composition with respect to the bulk. Mechanical activation considerably increases enargite reactivity. In laboratory experiments at acidic to neutral pH, enargite oxidation/dissolution is slow, although it is accelerated by the presence of ferric iron and/or bacteria such as Acidithiobacillus ferrooxidans and Sulfolobus BC. In the presence of sulphuric acid and ferric iron, the reaction involves dissolution of Cu and formation of native sulphur, subsequently partly oxidized to sulphate

  5. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress.

    Science.gov (United States)

    Liu, Shaobin; Zeng, Tingying Helen; Hofmann, Mario; Burcombe, Ehdi; Wei, Jun; Jiang, Rongrong; Kong, Jing; Chen, Yuan

    2011-09-27

    Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model-Escherichia coli. Under similar concentration and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest average size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O(2)(•-)) induced reactive oxygen species (ROS) production is detected. However, the four types of materials can oxidize glutathione, which serves as redox state mediator in bacteria. Conductive rGO and Gt have higher oxidation capacities than insulating GO and GtO. Results suggest that antimicrobial actions are contributed by both membrane and oxidation stress. We propose that a three-step antimicrobial mechanism, previously used for carbon nanotubes, is applicable to graphene-based materials. It includes initial cell deposition on graphene-based materials, membrane stress caused by direct contact with sharp nanosheets, and the ensuing superoxide anion-independent oxidation. We envision that physicochemical properties of graphene-based materials, such as density of functional groups, size, and conductivity, can be precisely tailored to either reducing their health and environmental risks or increasing their application potentials.

  6. The oxidative coupling of methane

    Energy Technology Data Exchange (ETDEWEB)

    Helton, T.; Anthony, R.G.; Gadalla, A.M. (Texas A and M Univ., College Park, TX (US))

    1988-01-01

    In this paper the spinel phase of cobalt oxide is evaluated as a potential coupling catalyst for converting methane to C/sub 2/+ hydrocarbons. Thermodynamic calculations indicate that the Gibbs free energies for forming higher hydrocarbons using the spinel form of cobalt oxide are similar to the free energies obtained for manganese (III) oxide. The oxidative coupling of methane was performed in an oxidation-reduction cycle.

  7. Stabilized tin-oxide-based oxidation/reduction catalysts

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

    2008-01-01

    The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

  8. Alkalilimnicola ehrlichii sp. nov., a novel, arsenite-oxidizing haloalkaliphilic gammaproteobacterium capable of chemoautotrophic or heterotrophic growth with nitrate or oxygen as the electron acceptor

    Science.gov (United States)

    Hoeft, S.E.; Blum, J.S.; Stolz, J.F.; Tabita, F.R.; Witte, B.; King, G.M.; Santini, J.M.; Oremland, R.S.

    2007-01-01

    A facultative chemoautotrophic bacterium, strain MLHE-1T, was isolated from Mono Lake, an alkaline hypersaline soda lake in California, USA. Cells of strain MLHE-1T were Gram-negative, short motile rods that grew with inorganic electron donors (arsenite, hydrogen, sulfide or thiosulfate) coupled with the reduction of nitrate to nitrite. No aerobic growth was attained with arsenite or sulfide, but hydrogen sustained both aerobic and anaerobic growth. No growth occurred when nitrite or nitrous oxide was substituted for nitrate. Heterotrophic growth was observed under aerobic and anaerobic (nitrate) conditions. Cells of strain MLHE-1T could oxidize but not grow on CO, while CH4 neither supported growth nor was it oxidized. When grown chemoautotrophically, strain MLHE-1T assimilated inorganic carbon via the Calvin-Benson-Bassham reductive pentose phosphate pathway, with the activity of ribulose 1,5-bisphosphate carboxylase (RuBisCO) functioning optimally at 0.1 M NaCl and at pH 7.3. Strain MLHE-1T grew over broad ranges of pH (7.3-10.0; optimum, 9.3), salinity (115-190 g l-1; optimum 30 g l-1) and temperature (113-40 ??C; optimum, 30 ??C). Phylogenetic analysis of 16S rRNA gene sequences placed strain MLHE-1T in the class Gammaproteobacteria (family Ectothiorhodospiraceae) and most closely related to Alkalispirillum mobile (98.5%) and Alkalilimnicola halodurans (98.6%), although none of these three haloalkaliphilic micro-organisms were capable of photoautotrophic growth and only strain MLHE-1T was able to oxidize As(III). On the basis of physiological characteristics and DNA-DNA hybridization data, it is suggested that strain MLHE-1T represents a novel species within the genus Alkalilimnicola for which the name Alkalilimnicola ehrlichii is proposed. The type strain is MLHE-1T (=DSM 17681T =ATCC BAA-1101T). Aspects of the annotated full genome of Alkalilimnicola ehrlichii are discussed in the light of its physiology. ?? 2007 IUMS.

  9. Erythropoietin and oxidative stress.

    Science.gov (United States)

    Maiese, Kenneth; Chong, Zhao Zhong; Hou, Jinling; Shang, Yan Chen

    2008-05-01

    Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor kappaB. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care.

  10. Methanol partial oxidation reformer

    Science.gov (United States)

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    1999-01-01

    A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

  11. Low thermal conductivity oxides

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei; Phillpot, Simon R.; Wan, Chunlei; Chernatynskiy, Aleksandr; Qu, Zhixue

    2012-10-09

    Oxides hold great promise as new and improved materials for thermal-barrier coating applications. The rich variety of structures and compositions of the materials in this class, and the ease with which they can be doped, allow the exploration of various mechanisms for lowering thermal conductivity. In this article, we review recent progress in identifying specific oxides with low thermal conductivity from both theoretical and experimental perspectives. We explore the mechanisms of lowering thermal conductivity, such as introducing structural/chemical disorder, increasing material density, increasing the number of atoms in the primitive cell, and exploiting the structural anisotropy. We conclude that further systematic exploration of oxide crystal structures and chemistries are likely to result in even further improved thermal-barrier coatings.

  12. Nitric oxide supersensitivity

    DEFF Research Database (Denmark)

    Olesen, J; Iversen, Helle Klingenberg; Thomsen, L L

    1993-01-01

    in a double blind design to 17 migraine patients, 17 age and sex matched healthy controls and 9 subjects with tension-type headache. The nitroglycerin-induced headache was significantly more severe in migraine sufferers, lasted longer and fulfilled diagnostic criteria for migraine more often. We have...... previously shown a similar supersensitivity to histamine which in human cerebral arteries activates endothelial H1 receptors and causes endothelial production of nitric oxide. Migraine patients are thus supersensitive to exogenous nitric oxide from nitroglycerin as well as to endothelially produced nitric...

  13. Crystalline mesoporous metal oxide

    Institute of Scientific and Technical Information of China (English)

    Wenbo Yue; Wuzong Zhou

    2008-01-01

    Since the discovery of many types of mesoporous silicas, such as SBA-15, KIT-6, FDU-12 and SBA-16, porous crystalline transition metal oxides, such as Cr2O3, Co3O4, In2O3, NiO, CeO2, WO3, Fe2O3 and MnO2, have been synthesized using the mesoporous silicas as hard templates. Several synthetic methods have been developed. These new porous materials have high potential applications in catalysis, Li-ion rechargeable batteries and gas sensors. This article gives a brief review of the research of porous crystals of metal oxides in the last four years.

  14. Copolymerization Kinetics of Ethylene Oxide and Propylene Oxide

    Institute of Scientific and Technical Information of China (English)

    尹红; 陈志荣

    2002-01-01

    The copolymerization kinetics of ethylene oxide and propylene oxide in an atomizing-circulation reactorunder semi-continuous operation is studied which is of great importance for molecular designation. The kineticparameters are obtained by numerical optimization of the kinetic model.

  15. Effect of Oxide Layer in Metal-Oxide-Semiconductor Systems

    Directory of Open Access Journals (Sweden)

    Fan Jung-Chuan

    2016-01-01

    Full Text Available In this work, we investigate the electrical properties of oxide layer in the metal-oxide semiconductor field effect transistor (MOSFET. The thickness of oxide layer is proportional to square root of oxidation time. The feature of oxide layer thickness on the growth time is consistent with the Deal-Grove model effect. From the current-voltage measurement, it is found that the threshold voltages (Vt for MOSFETs with different oxide layer thicknesses are proportional to the square root of the gate-source voltages (Vgs. It is also noted that threshold voltage of MOSFET increases with the thickness of oxide layer. It indicates that the bulk effect of oxide dominates in this MOSFET structure.

  16. Doped zinc oxide microspheres

    Science.gov (United States)

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  17. Solid Oxide Fuel Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The solid oxide fuel cell comprising a metallic support material, an active anode layer consisting of a good hydrocarbon cracking catalyst, an electrolyte layer, an active cathode layer, and a transition layer consisting of preferably a mixture of LSM and a ferrite to the cathode current collector...

  18. Dopamine Oxidation and Autophagy

    Directory of Open Access Journals (Sweden)

    Patricia Muñoz

    2012-01-01

    Full Text Available The molecular mechanisms involved in the neurodegenerative process of Parkinson's disease remain unclear. Currently, there is a general agreement that mitochondrial dysfunction, α-synuclein aggregation, oxidative stress, neuroinflammation, and impaired protein degradation are involved in the neurodegeneration of dopaminergic neurons containing neuromelanin in Parkinson's disease. Aminochrome has been proposed to play an essential role in the degeneration of dopaminergic neurons containing neuromelanin by inducing mitochondrial dysfunction, oxidative stress, the formation of neurotoxic α-synuclein protofibrils, and impaired protein degradation. Here, we discuss the relationship between the oxidation of dopamine to aminochrome, the precursor of neuromelanin, autophagy dysfunction in dopaminergic neurons containing neuromelanin, and the role of dopamine oxidation to aminochrome in autophagy dysfunction in dopaminergic neurons. Aminochrome induces the following: (i the formation of α-synuclein protofibrils that inactivate chaperone-mediated autophagy; (ii the formation of adducts with α- and β-tubulin, which induce the aggregation of the microtubules required for the fusion of autophagy vacuoles and lysosomes.

  19. Oxidative stress in myopia.

    Science.gov (United States)

    Francisco, Bosch-Morell; Salvador, Mérida; Amparo, Navea

    2015-01-01

    Myopia affected approximately 1.6 billion people worldwide in 2000, and it is expected to increase to 2.5 billion by 2020. Although optical problems can be corrected by optics or surgical procedures, normal myopia and high myopia are still an unsolved medical problem. They frequently predispose people who have them to suffer from other eye pathologies: retinal detachment, glaucoma, macular hemorrhage, cataracts, and so on being one of the main causes of visual deterioration and blindness. Genetic and environmental factors have been associated with myopia. Nevertheless, lack of knowledge in the underlying physiopathological molecular mechanisms has not permitted an adequate diagnosis, prevention, or treatment to be found. Nowadays several pieces of evidence indicate that oxidative stress may help explain the altered regulatory pathways in myopia and the appearance of associated eye diseases. On the one hand, oxidative damage associated with hypoxia myopic can alter the neuromodulation that nitric oxide and dopamine have in eye growth. On the other hand, radical superoxide or peroxynitrite production damage retina, vitreous, lens, and so on contributing to the appearance of retinopathies, retinal detachment, cataracts and so on. The objective of this review is to suggest that oxidative stress is one of the key pieces that can help solve this complex eye problem.

  20. Highly oxidized superconductors

    Science.gov (United States)

    Morris, Donald E.

    1994-01-01

    Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known syntheses in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed.

  1. Oxidative Stress in Myopia

    Directory of Open Access Journals (Sweden)

    Bosch-Morell Francisco

    2015-01-01

    Full Text Available Myopia affected approximately 1.6 billion people worldwide in 2000, and it is expected to increase to 2.5 billion by 2020. Although optical problems can be corrected by optics or surgical procedures, normal myopia and high myopia are still an unsolved medical problem. They frequently predispose people who have them to suffer from other eye pathologies: retinal detachment, glaucoma, macular hemorrhage, cataracts, and so on being one of the main causes of visual deterioration and blindness. Genetic and environmental factors have been associated with myopia. Nevertheless, lack of knowledge in the underlying physiopathological molecular mechanisms has not permitted an adequate diagnosis, prevention, or treatment to be found. Nowadays several pieces of evidence indicate that oxidative stress may help explain the altered regulatory pathways in myopia and the appearance of associated eye diseases. On the one hand, oxidative damage associated with hypoxia myopic can alter the neuromodulation that nitric oxide and dopamine have in eye growth. On the other hand, radical superoxide or peroxynitrite production damage retina, vitreous, lens, and so on contributing to the appearance of retinopathies, retinal detachment, cataracts and so on. The objective of this review is to suggest that oxidative stress is one of the key pieces that can help solve this complex eye problem.

  2. Nanostructured transition metal oxides useful for water oxidation catalysis

    Science.gov (United States)

    Frei, Heinz M; Jiao, Feng

    2013-12-24

    The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

  3. Staged membrane oxidation reactor system

    Science.gov (United States)

    Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

    2013-04-16

    Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

  4. Nitrous Oxide Micro Engines Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Nitrous Oxide Micro Engines (NOME) are a new type of nitrous oxide dissociation thruster designed to generate low levels of thrust that can be used for RCS control...

  5. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  6. REVIEW OF PLUTONIUM OXIDATION LITERATURE

    Energy Technology Data Exchange (ETDEWEB)

    Korinko, P.

    2009-11-12

    A brief review of plutonium oxidation literature was conducted. The purpose of the review was to ascertain the effect of oxidation conditions on oxide morphology to support the design and operation of the PDCF direct metal oxidation (DMO) furnace. The interest in the review was due to a new furnace design that resulted in oxide characteristics that are different than those of the original furnace. Very little of the published literature is directly relevant to the DMO furnace operation, which makes assimilation of the literature data with operating conditions and data a convoluted task. The oxidation behavior can be distilled into three regimes, a low temperature regime (RT to 350 C) with a relatively slow oxidation rate that is influenced by moisture, a moderate temperature regime (350-450 C) that is temperature dependent and relies on more or less conventional oxidation growth of a partially protective oxide scale, and high temperature oxidation (> 500 C) where the metal autocatalytically combusts and oxidizes. The particle sizes obtained from these three regimes vary with the finest being from the lowest temperature. It is surmised that the slow growth rate permits significant stress levels to be achieved that help break up the oxides. The intermediate temperatures result in a fairly compact scale that is partially protective and that grows to critical thickness prior to fracturing. The growth rate in this regime may be parabolic or paralinear, depending on the oxidation time and consequently the oxide thickness. The high temperature oxidation is invariant in quiescent or nearly quiescent conditions due to gas blanketing while it accelerates with temperature under flowing conditions. The oxide morphology will generally consist of fine particles (<15 {micro}m), moderately sized particles (15 < x < 250 {micro}m) and large particles (> 250 {micro}m). The particle size ratio is expected to be < 5%, 25%, and 70% for fine, medium and large particles, respectively, for

  7. Oxidants and antioxidants in disease

    DEFF Research Database (Denmark)

    Lykkesfeldt, Jens; Svendsen, Ove

    2007-01-01

    Important infectious diseases in farm animals, such as pneumonia and enteritis, are thought to be associated with the so-called oxidative stress, i.e. a chemical phenomenon involving an imbalance in the redox status of the individual animal. The specifics of oxidative stress and how it may result...... theoretically, oxidative stress should be easily prevented with antioxidants yet the use of antioxidants as therapy remains controversial. The present knowledge on oxidative stress in farm animals is the topic of this review....

  8. Molybdenum oxide nanowires: synthesis & properties

    Directory of Open Access Journals (Sweden)

    Liqiang Mai

    2011-07-01

    Full Text Available Molybdenum oxide nanowires have been found to show promise in a diverse range of applications, ranging from electronics to energy storage and micromechanics. This review focuses on recent research on molybdenum oxide nanowires: from synthesis and device assembly to fundamental properties. The synthesis of molybdenum oxide nanowires will be reviewed, followed by a discussion of recent progress on molybdenum oxide nanowire based devices and an examination of their properties. Finally, we conclude by considering future developments.

  9. Oxidative Stress and Antioxidant Defense

    OpenAIRE

    2012-01-01

    Abstract Reactive oxygen species (ROS) are produced by living organisms as a result of normal cellular metabolism and environmental factors, such as air pollutants or cigarette smoke. ROS are highly reactive molecules and can damage cell structures such as carbohydrates, nucleic acids, lipids, and proteins and alter their functions. The shift in the balance between oxidants and antioxidants in favor of oxidants is termed “oxidative stress.” Regulation of reducing and oxidizing (redox) state i...

  10. Self-assembled manganese oxide structures through direct oxidation

    KAUST Repository

    Zhao, Chao

    2012-12-01

    The morphology and phase of self-assembled manganese oxides during different stages of thermal oxidation were studied. Very interesting morphological patterns of Mn oxide films were observed. At the initial oxidation stage, the surface was characterized by the formation of ring-shaped patterns. As the oxidation proceeded to the intermediate stage, concentric plates formed to relax the compressive stress. Our experimental results gave a clear picture of the evolution of the structures. We also examined the properties of the structures. © 2012 Elsevier B.V.

  11. Catalytic oxidation of dimethyl ether

    Science.gov (United States)

    Zelenay, Piotr; Wu, Gang; Johnston, Christina M.; Li, Qing

    2016-05-10

    A composition for oxidizing dimethyl ether includes an alloy supported on carbon, the alloy being of platinum, ruthenium, and palladium. A process for oxidizing dimethyl ether involves exposing dimethyl ether to a carbon-supported alloy of platinum, ruthenium, and palladium under conditions sufficient to electrochemically oxidize the dimethyl ether.

  12. Riboflavin photosensitized oxidation of myoglobin

    DEFF Research Database (Denmark)

    Grippa, Juliana M.; de Zawadzki, Andressa; Grossi, Alberto Blak;

    2014-01-01

    The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation o...

  13. Oxidation of Quercetin by Myeloperoxidase

    OpenAIRE

    Tatjana Momić; Jasmina Savić; Vesna Vasić

    2009-01-01

    Study of effect of myeloperoxidase on quercetin at pH 6.0 indicated quercetin oxidation via the formation of the oxidation product. The stability of quercetin and oxidation product was investigated as a function of time by using spectrophotometric and HPLC techniques. The apparent pseudo first-order rate constants were calculated and discussed.

  14. Oxide fiber targets at ISOLDE

    DEFF Research Database (Denmark)

    Köster, U.; Bergmann, U.C.; Carminati, D.

    2003-01-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at so...

  15. Oxidation kinetics of aluminum nitride at different oxidizing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Hou Xinmei [Metallurgical and Ecological Engineering School, University of Science and Technology Beijing, Beijing 100083 (China); Chou, K.-C. [Metallurgical and Ecological Engineering School, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: kcc126@126.com; Zhong Xiangchong [High Temperature Ceramics Institute, Zhengzhou University, Henan Province 450052 (China); Seetharaman, Seshadri [Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm (Sweden)

    2008-10-06

    In the present work, the oxidation kinetics of AlN powder was investigated by using thermogravimetric analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experiments were carried out both in isothermal as well as non-isothermal modes under two different oxidizing atmospheres. The results showed that the oxidation reaction started at around 1100 K and the rate increased significantly beyond 1273 K forming porous aluminum oxide as the reaction product. The oxidation rate was affected by temperature and oxygen partial pressure. A distinct change in the oxidation mechanism was noticed in the temperature range 1533-1543 K which is attributed to the phase transformation in oxidation product, viz. alumina. Diffusion is the controlling step during the oxidation process. Based on the experimental data, a new model for predicting the oxidation process of AlN powder had been developed, which offered an analytic form expressing the oxidation weight increment as a function of time, temperature and oxygen partial pressure. The application of this new model to this system demonstrated that this model could be used to describe the oxidation behavior of AlN powder.

  16. Model catalytic oxidation studies using supported monometallic and heterobimetallic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Ekerdt, J.G.

    1992-02-03

    This research program is directed toward a more fundamental understanding of the effects of catalyst composition and structure on the catalytic properties of metal oxides. Metal oxide catalysts play an important role in many reactions bearing on the chemical aspects of energy processes. Metal oxides are the catalysts for water-gas shift reactions, methanol and higher alcohol synthesis, isosynthesis, selective catalytic reduction of nitric oxides, and oxidation of hydrocarbons. A key limitation to developing insight into how oxides function in catalytic reactions is in not having precise information of the surface composition under reaction conditions. To address this problem we have prepared oxide systems that can be used to study cation-cation effects and the role of bridging (-O-) and/or terminal (=O) surface oxygen anion ligands in a systematic fashion. Since many oxide catalyst systems involve mixtures of oxides, we selected a model system that would permit us to examine the role of each cation separately and in pairwise combinations. Organometallic molybdenum and tungsten complexes were proposed for use, to prepare model systems consisting of isolated monomeric cations, isolated monometallic dimers and isolated bimetallic dimers supported on silica and alumina. The monometallic and bimetallic dimers were to be used as models of more complex mixed- oxide catalysts. Our current program was to develop the systems and use them in model oxidation reactions.

  17. Photocatalytic oxidation of methane over silver decorated zinc oxide nanocatalysts.

    Science.gov (United States)

    Chen, Xuxing; Li, Yunpeng; Pan, Xiaoyang; Cortie, David; Huang, Xintang; Yi, Zhiguo

    2016-07-20

    The search for active catalysts that efficiently oxidize methane under ambient conditions remains a challenging task for both C1 utilization and atmospheric cleansing. Here, we show that when the particle size of zinc oxide is reduced down to the nanoscale, it exhibits high activity for methane oxidation under simulated sunlight illumination, and nano silver decoration further enhances the photo-activity via the surface plasmon resonance. The high quantum yield of 8% at wavelengths oxide nanostructures shows great promise for atmospheric methane oxidation. Moreover, the nano-particulate composites can efficiently photo-oxidize other small molecular hydrocarbons such as ethane, propane and ethylene, and in particular, can dehydrogenize methane to generate ethane, ethylene and so on. On the basis of the experimental results, a two-step photocatalytic reaction process is suggested to account for the methane photo-oxidation.

  18. Factors Affection Cr(Ⅲ) Oxidation by Manganese Oxides

    Institute of Scientific and Technical Information of China (English)

    CHENYINGXU; CHENYIYI; 等

    1997-01-01

    The high oxidation ability of manganese oxides or soils was used to study effects of PH and coating on Cr(Ⅲ) oxidation,The results indicated that Cr(Ⅲ) oxidation peaked in PH 4.0-6.5,The amount and rate of Cr(Ⅲ) being oxidized by uncoated δ-MnO2 were larger than those by Fe oxide- of CaCo3-coated one.Inorganic Cr(Ⅲ) wa more easily oxidzed by MnO2 than organic complex Cr(Ⅲ) due to different surface affinities. Precipitated Cr(Ⅲ) and adsorbed Cr(Ⅲ) might be transferred onto MnO2 surface and then oxidized to Cr(Ⅵ)

  19. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  20. Manganese Oxidation by Bacteria: Biogeochemical Aspects

    Digital Repository Service at National Institute of Oceanography (India)

    Sujith, P.P.; LokaBharathi, P.A.

    Manganese is an essential trace metal that is not as readily oxidizable like iron. Several bacterial groups posses the ability to oxidize Mn effectively competing with chemical oxidation. The oxides of Mn are the strongest of the oxidants, next...

  1. Defects at oxide surfaces

    CERN Document Server

    Thornton, Geoff

    2015-01-01

    This book presents the basics and characterization of defects at oxide surfaces. It provides a state-of-the-art review of the field, containing information to the various types of surface defects, describes analytical methods to study defects, their chemical activity and the catalytic reactivity of oxides. Numerical simulations of defective structures complete the picture developed. Defects on planar surfaces form the focus of much of the book, although the investigation of powder samples also form an important part. The experimental study of planar surfaces opens the possibility of applying the large armoury of techniques that have been developed over the last half-century to study surfaces in ultra-high vacuum. This enables the acquisition of atomic level data under well-controlled conditions, providing a stringent test of theoretical methods. The latter can then be more reliably applied to systems such as nanoparticles for which accurate methods of characterization of structure and electronic properties ha...

  2. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...

  3. Oxidative stress & male infertility.

    Science.gov (United States)

    Makker, Kartikeya; Agarwal, Ashok; Sharma, Rakesh

    2009-04-01

    The male factor is considered a major contributory factor to infertility. Apart from the conventional causes for male infertility such as varicocoele, cryptorchidism, infections, obstructive lesions, cystic fibrosis, trauma, and tumours, a new and important cause has been identified: oxidative stress. Oxidative stress is a result of the imbalance between reactive oxygen species (ROS) and antioxidants in the body. It is a powerful mechanism that can lead to sperm damage, deformity and eventually, male infertility. This review discusses the physiological need for ROS and their role in normal sperm function. It also highlights the mechanism of production and the pathophysiology of ROS in relation to the male reproductive system and enumerate the benefits of incorporating antioxidants in clinical and experimental settings.

  4. Oxidation of visbreaker bitumens

    Energy Technology Data Exchange (ETDEWEB)

    Giavarini, C.; Saporito, S.

    1989-07-01

    A series of oxidation tests was carried out on a small-scale blowing unit fed with two different visbreaker (VB) bitumens, and with two straight-run (SR) soft bitumens for reference. The purpose was to study the possibility of applying the blowing process to VB feeds, and to evaluate process kinetics and product characteristics. The results showed that industrial blowing of VB bitumens is feasible and that the rate of reaction can be expressed by a first order equation with respect to change in softening point. Production of distillate oils was quite high, especially when iron trichloride was used as a catalyst; in industrial application it is suggested that VB bitumens may be oxidized without any catalyst, the kinetics of the non-catalytic process being satisfactory. Air consumption was unsteady compared with the SR operation, and plugging of the air coil was more frequent. 20 refs., 3 figs., 3 tabs.

  5. Hemoglobin oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Croci, S.; Ortalli, I.; Pedrazzi, G. [University of Parma, Istituto di Scienze Fisiche, INFM-Udr Parma (Italy); Passeri, G. [University of Parma, Dipartimento di Medicina Interna e Scienze Biomediche (Italy); Piccolo, P. [University of Parma, Istituto di Clinica chirurgica Generale, Toracica e Vascolare (Italy)

    2000-07-15

    Venous blood obtained from healthy donors and from patients suffering from breast cancer have been treated with acetylphenylhydrazine (APH) for different time. Moessbauer spectra of the packed red cells have been recorded and compared. The largest difference occurs after 50 min of treatment with APH where the patient samples show a broad spectral pattern indicating an advanced hemoglobin oxidation. These results may have some relevance in early cancer diagnosis.

  6. Lipid oxidation induced oxidative degradation of cereal beta-glucan.

    Science.gov (United States)

    Wang, Yu-Jie; Mäkelä, Noora; Maina, Ndegwa Henry; Lampi, Anna-Maija; Sontag-Strohm, Tuula

    2016-04-15

    In food systems, lipid oxidation can cause oxidation of other molecules. This research for the first time investigated oxidative degradation of β-glucan induced by lipid oxidation using an oil-in-water emulsion system which simulated a multi-phased aqueous food system containing oil and β-glucan. Lipid oxidation was monitored using peroxide value and hexanal production while β-glucan degradation was evaluated by viscosity and molecular weight measurements. The study showed that while lipid oxidation proceeded, β-glucan degradation occurred. Emulsions containing β-glucan, oil and ferrous ion showed significant viscosity and molecular weight decrease after 1 week of oxidation at room temperature. Elevated temperature (40°C) enhanced the oxidation reactions causing higher viscosity drop. In addition, the presence of β-glucan appeared to retard the hexanal production in lipid oxidation. The study revealed that lipid oxidation may induce the degradation of β-glucan in aqueous food systems where β-glucan and lipids co-exist.

  7. Autotrophic Biofilters for Oxidation of Nitric Oxide

    Institute of Scientific and Technical Information of China (English)

    陈建孟; 陈浚; LanceHershman; 王家德; DanielP.Y.Chang

    2004-01-01

    Carbon foam—a kind of new engineering material as packing material was adopted in three biofilters with different pore dimensions and adapted autotrophic nitrite nitrobacteria to investigate the purification of nitric oxide (NO) in a gas stream. The biofilm was developed on the surface of carbon foams using nitrite as its only nitric source. The moisture in the filter was maintained by ultrasonic aerosol equipment which can minimize the thickness of the liquid film. The liquid phase nitrification test was conducted to determine the variability and the potential of performance among the three carbon foam biofilters. The investigation showed that during the NO2-—N inlet concentration of 200 g·L-1·min-1 to 800 g·L-1·min-1, the 24PPC (pores per centimeter) carbon foam biofilter had the greatest potential, achieving the NO2-—N removal efficiency of 94% to 98%. The 8PPC and 18PPC carbon foam biofilters achieved the NO2-—N removal efficiency of 15% to 21% and of 30% to 40%, respectively. The potential for this system to remove NO from a gas stream was shown on the basis of a steady removal efficiency of 41% to 50% which was attained for the 24PPC carbon foam biofilter at specified NO inlet concentration of 66.97 mg·m-3 to 267.86mg·m-3 and an empty-bed residence time of 3.5 min.

  8. Arsenite oxidation by three types of manganese oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Oxidation of As(Ⅲ) by three types of manganese oxides and the effects of pH, ion strength and tartaric acid on the oxidation were investigated by means of chemical analysis, equilibrium redox, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Three synthesized Mn oxide minerals, birnessite, cryptomelane, and hausmarnite, which widely occur in soil and sediments, could actively oxidize As(Ⅲ) to As(Ⅴ). However, their ability in As(Ⅲ)-oxidation varied greatly depending on their structure, composition and surface properties. Tunnel structured cryptomelane exhibited the highest ability of As (Ⅲ) oxidation, followed by the layer structured birnessite and the lower oxide hausmannite. The maximum amount of As (Ⅴ) produced by the oxidation was in the order (mmol/kg) ofcryptomelane (824.2) > birnessite (480.4) > hausmannite (117.9). As pH increased from the very low value(pH 2.5), the amount of As(Ⅲ) oxidized by the tested Mn oxides was firstly decreased, then negatively peaked in pH 3.0-6.5,and eventually increased remarkably. Oxidation of As(Ⅲ) by the Mn oxides had a buffering effects on the pH variation in the solution.It is proposed that the oxidative reaction processes between As( Ⅲ ) and birnessite(or cryptomelane) are as follows: (1) at lower pH condition: (MnO2)x + H3AsO3 + 0.5H+=0.5H2AsO4- + 0.5HAsO42- +Mn2++ (MnO2)x-1 + H2O; (2) at higher pH condition: (MnO2)x +cryptomelane decreased and was negatively correlated with ion strength. However, ion strength had little influence on As (Ⅲ) oxidation by the hausmannite. The presence of tartaric acid promoted oxidation of As(Ⅲ) by birnessite. As for cryptomelane and hausmannite, the same effect was observed when the concentration of tartaric acid was below 4 mmol/L, otherwise the oxidized As(Ⅲ)decreased. These findings are of great significance in improving our understanding of As geochemical cycling and controlling As contamination.

  9. The competing oxide and sub-oxide formation in metal-oxide molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, Patrick; Bierwagen, Oliver [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

    2015-02-23

    The hetero-epitaxial growth of the n-type semiconducting oxides β-Ga{sub 2}O{sub 3}, In{sub 2}O{sub 3}, and SnO{sub 2} on c- and r-plane sapphire was performed by plasma-assisted molecular beam epitaxy. The growth-rate and desorbing flux from the substrate were measured in-situ under various oxygen to metal ratios by laser reflectometry and quadrupole mass spectrometry, respectively. These measurements clarified the role of volatile sub-oxide formation (Ga{sub 2}O, In{sub 2}O, and SnO) during growth, the sub-oxide stoichiometry, and the efficiency of oxide formation for the three oxides. As a result, the formation of the sub-oxides decreased the growth-rate under metal-rich growth conditions and resulted in etching of the oxide film by supplying only metal flux. The flux ratio for the exclusive formation of the sub-oxide (e.g., the p-type semiconductor SnO) was determined, and the efficiency of oxide formation was found to be the highest for SnO{sub 2}, somewhat lower for In{sub 2}O{sub 3}, and the lowest for Ga{sub 2}O{sub 3}. Our findings can be generalized to further oxides that possess related sub-oxides.

  10. The 2016 oxide electronic materials and oxide interfaces roadmap

    DEFF Research Database (Denmark)

    Lorenz, M.; Rao, M. S. Ramachandra; Venkatesan, T.

    2016-01-01

    Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale...... form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics...... of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap...

  11. Partial Oxidation of Methane Over the Perovskite Oxides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ba0.sSr0.5Co0.8Fe0.2O3-δ and Ba0.5Sr0.5Co0.8Ti0.2O3-δ oxides were synthesized by a combined EDTA-citrate complexing method. The catalytic behavior of these two oxides with the perovskite structure was studied during the reaction of methane oxidation. The pre-treatment with methane has different effect on the catalytic activities of both the oxides. The methane pre-treatment has not resulted in the change of the catalytic activity of BSCFO owing to its excellent reversibility of the perovskite structure resulting from the excellent synergistic interaction between Co and Fe in the oxide. However, the substitution with Ti on Fe-site in the lattice makes the methane pre-treatment have an obvious influence on the activity of the formed BSCTO oxide.

  12. The oxidative hypothesis of senescence

    Directory of Open Access Journals (Sweden)

    Gilca M

    2007-01-01

    Full Text Available The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g., those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc. This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal β -oxidation and respiratory burst of phagocytic cells, antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol, alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

  13. The oxidative hypothesis of senescence.

    Science.gov (United States)

    Gilca, M; Stoian, I; Atanasiu, V; Virgolici, B

    2007-01-01

    The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g, those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc). This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal beta -oxidation and respiratory burst of phagocytic cells), antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol), alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

  14. Fabrication of titanium oxide nanotube arrays by anodic oxidation

    Science.gov (United States)

    Zhao, Jianling; Wang, Xiaohui; Chen, Renzheng; Li, Longtu

    2005-06-01

    The formation of titanium oxide nanotube arrays on titanium substrates was investigated in HF electrolytes. Under optimized electrolyte and oxidation conditions, well-ordered nanotubes of titania were fabricated. Topologies of the anodized titanium change remarkably along with the changing of applied voltages, electrolyte concentration and oxidation time. Electrochemical determination and scanning electron microscope indicate the nanotubes are formed due to the competition of titania formation and dissolution under the assistance of electric field. A possible growth mechanism has also been presented.

  15. Complete nitrification by Nitrospira bacteria

    DEFF Research Database (Denmark)

    Daims, Holger; Lebedeva, Elena V.; Pjevac, Petra

    2015-01-01

    Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be a two-step process catalysed by chemolithoautotrophic microorganisms oxidizing either ammonia or nitrite. No known nitrifier carries out both steps, although complete nitrification should be energetic...

  16. Unusual inherent electrochemistry of graphene oxides prepared using permanganate oxidants.

    Science.gov (United States)

    Eng, Alex Yong Sheng; Ambrosi, Adriano; Chua, Chun Kiang; Saněk, Filip; Sofer, Zdeněk; Pumera, Martin

    2013-09-16

    Graphene and graphene oxides are materials of significant interest in electrochemical devices such as supercapacitors, batteries, fuel cells, and sensors. Graphene oxides and reduced graphenes are typically prepared by oxidizing graphite in strong mineral acid mixtures with chlorate (Staudenmaier, Hofmann) or permanganate (Hummers, Tour) oxidants. Herein, we reveal that graphene oxides pose inherent electrochemistry, that is, they can be oxidized or reduced at relatively mild potentials (within the range ±1 V) that are lower than typical battery potentials. This inherent electrochemistry of graphene differs dramatically from that of the used oxidants. Graphene oxides prepared using chlorate exhibit chemically irreversible reductions, whereas graphene oxides prepared through permanganate-based methods exhibit very unusual inherent chemically reversible electrochemistry of oxygen-containing groups. Insight into the electrochemical behaviour was obtained through cyclic voltammetry, chronoamperometry, and X-ray photoelectron spectroscopy experiments. Our findings are of extreme importance for the electrochemistry community as they reveal that electrode materials undergo cyclic changes in charge/discharge cycles, which has strong implications for energy-storage and sensing devices.

  17. The 2016 oxide electronic materials and oxide interfaces roadmap

    Science.gov (United States)

    Lorenz, M.; Ramachandra Rao, M. S.; Venkatesan, T.; Fortunato, E.; Barquinha, P.; Branquinho, R.; Salgueiro, D.; Martins, R.; Carlos, E.; Liu, A.; Shan, F. K.; Grundmann, M.; Boschker, H.; Mukherjee, J.; Priyadarshini, M.; DasGupta, N.; Rogers, D. J.; Teherani, F. H.; Sandana, E. V.; Bove, P.; Rietwyk, K.; Zaban, A.; Veziridis, A.; Weidenkaff, A.; Muralidhar, M.; Murakami, M.; Abel, S.; Fompeyrine, J.; Zuniga-Perez, J.; Ramesh, R.; Spaldin, N. A.; Ostanin, S.; Borisov, V.; Mertig, I.; Lazenka, V.; Srinivasan, G.; Prellier, W.; Uchida, M.; Kawasaki, M.; Pentcheva, R.; Gegenwart, P.; Miletto Granozio, F.; Fontcuberta, J.; Pryds, N.

    2016-11-01

    Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on ‘oxide electronic materials and oxide interfaces’. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by

  18. Protein oxidation and ageing

    DEFF Research Database (Denmark)

    Linton, S; Davies, Michael Jonathan; Dean, R T

    2001-01-01

    of redox-active metal ions that could catalyse oxidant formation. As a result of this decrease in antioxidant defences, and increased rate of ROS formation, it is possible that the impact of ROS increases with age. ROS are known to oxidise biological macromolecules, with proteins an important target....... If the argument that the impact of ROS increases with age is true, then proteins would be expected to accumulate oxidised materials with age, and the rate of such accumulation should increase with time, reflecting impaired inefficiency of homeostasis. Here we review the evidence for the accumulation of oxidised......, or modified, extra- and intra-cellular proteins in vivo....

  19. Semiconductor Oxide Interface States.

    Science.gov (United States)

    1981-05-01

    0C for 30 minutes. B 9 7 and B17 curves were taken before forming gas annealing and A297 and A77 were taken after annealing in forming gas... A297 and A77’ AL .show a substantial reduction of interface states and a slight increase of positive oxide charges. The reduction of the interface...states is deduced from the voltage differences between A297 and the A77 C-V curves both above and below the cross-over point which are smaller than the

  20. Nanostructures of zinc oxide

    Directory of Open Access Journals (Sweden)

    Zhong Lin Wang

    2004-06-01

    Full Text Available Zinc oxide (ZnO is a unique material that exhibits semiconducting, piezoelectric, and pyroelectric multiple properties. Using a solid-vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobows, nanobelts, nanowires, and nanocages of ZnO have been synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO is probably the richest family of nanostructures among all materials, both in structures and properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers, and biomedical science because it is bio-safe.

  1. Protein oxidation and peroxidation

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2016-01-01

    and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function....... Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides...

  2. Sputtered tin oxide and titanium oxide thin films as alternative transparent conductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Boltz, Janika

    2011-12-12

    Alternative transparent conductive oxides to tin doped indium oxide have been investigated. In this work, antimony doped tin oxide and niobium doped titanium oxide have been studied with the aim to prepare transparent and conductive films. Antimony doped tin oxide and niobium doped titanium oxide belong to different groups of oxides; tin oxide is a soft oxide, while titanium oxide is a hard oxide. Both oxides are isolating materials, in case the stoichiometry is SnO{sub 2} and TiO{sub 2}. In order to achieve transparent and conductive films free carriers have to be generated by oxygen vacancies, by metal ions at interstitial positions in the crystal lattice or by cation doping with Sb or Nb, respectively. Antimony doped tin oxide and niobium doped titanium oxide films have been prepared by reactive direct current magnetron sputtering (dc MS) from metallic targets. The process parameters and the doping concentration in the films have been varied. The films have been electrically, optically and structurally analysed in order to analyse the influence of the process parameters and the doping concentration on the film properties. Post-deposition treatments of the films have been performed in order to improve the film properties. For the deposition of transparent and conductive tin oxide, the dominant parameter during the deposition is the oxygen content in the sputtering gas. The Sb incorporation as doping atoms has a minor influence on the electrical, optical and structural properties. Within a narrow oxygen content in the sputtering gas highly transparent and conductive tin oxide films have been prepared. In this study, the lowest resistivity in the as deposited state is 2.9 m{omega} cm for undoped tin oxide without any postdeposition treatment. The minimum resistivity is related to a transition to crystalline films with the stoichiometry of SnO{sub 2}. At higher oxygen content the films turn out to have a higher resistivity due to an oxygen excess. After post

  3. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  4. Pyrite oxidation by thermophilic archaebacteria

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, L.; Olsson, G.; Holst, O.; Karlsson, H.T. (Lund Univ. (Sweden))

    1990-03-01

    Three species of thermophilic archaebacteria of the genera Sulfolobus (Sulfolobus acidocaldarius and S. solfataricus) and Acidianus (Acidianus brierleyi) were tested for their ability to oxidize pyrite and to grow autotropbically on pyrite, to explore their potential for use in coal desulfurization. Only A. brierleyi was able to oxidize and grow autotrophically on pyrite. Jarosite was formed during the pyrite oxidation, resulting in the precipitation of sulfate and iron. The medium composition affected the extent of jarosite formation.

  5. Nanoporous silicon oxide memory.

    Science.gov (United States)

    Wang, Gunuk; Yang, Yang; Lee, Jae-Hwang; Abramova, Vera; Fei, Huilong; Ruan, Gedeng; Thomas, Edwin L; Tour, James M

    2014-08-13

    Oxide-based two-terminal resistive random access memory (RRAM) is considered one of the most promising candidates for next-generation nonvolatile memory. We introduce here a new RRAM memory structure employing a nanoporous (NP) silicon oxide (SiOx) material which enables unipolar switching through its internal vertical nanogap. Through the control of the stochastic filament formation at low voltage, the NP SiOx memory exhibited an extremely low electroforming voltage (∼ 1.6 V) and outstanding performance metrics. These include multibit storage ability (up to 9-bits), a high ON-OFF ratio (up to 10(7) A), a long high-temperature lifetime (≥ 10(4) s at 100 °C), excellent cycling endurance (≥ 10(5)), sub-50 ns switching speeds, and low power consumption (∼ 6 × 10(-5) W/bit). Also provided is the room temperature processability for versatile fabrication without any compliance current being needed during electroforming or switching operations. Taken together, these metrics in NP SiOx RRAM provide a route toward easily accessed nonvolatile memory applications.

  6. Magnetoexcitons in cuprous oxide

    Science.gov (United States)

    Schweiner, Frank; Main, Jörg; Wunner, Günter; Freitag, Marcel; Heckötter, Julian; Uihlein, Christoph; Aßmann, Marc; Fröhlich, Dietmar; Bayer, Manfred

    2017-01-01

    Two of the most striking experimental findings when investigating exciton spectra in cuprous oxide using high-resolution spectroscopy are the observability and the fine structure splitting of F excitons reported by J. Thewes et al. [Phys. Rev. Lett. 115, 027402 (2015), 10.1103/PhysRevLett.115.027402]. These findings show that it is indispensable to account for the complex valence band structure and the cubic symmetry of the solid in the theory of excitons. This is all the more important for magnetoexcitons, where the external magnetic field reduces the symmetry of the system even further. We present the theory of excitons in Cu2O in an external magnetic field and especially discuss the dependence of the spectra on the direction of the external magnetic field, which cannot be understood from a simple hydrogenlike model. Using high-resolution spectroscopy, we also present the corresponding experimental spectra for cuprous oxide in Faraday configuration. The theoretical results and experimental spectra are in excellent agreement as regards not only the energies but also the relative oscillator strengths. Furthermore, this comparison allows for the determination of the fourth Luttinger parameter κ of this semiconductor.

  7. Magnetic frustration of graphite oxide

    Science.gov (United States)

    Lee, Dongwook; Seo, Jiwon

    2017-01-01

    Delocalized π electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, π electrons develop ferromagnetism due to the unique structure of the material. The π electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negative Curie temperature, field irreversibility, and slow relaxation. The overall results indicate that magnetic moments in graphite oxide slowly interact and develop magnetic frustration. PMID:28327606

  8. Continuous lengths of oxide superconductors

    Science.gov (United States)

    Kroeger, Donald M.; List, III, Frederick A.

    2000-01-01

    A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.

  9. The chemistry of graphene oxide.

    Science.gov (United States)

    Dreyer, Daniel R; Park, Sungjin; Bielawski, Christopher W; Ruoff, Rodney S

    2010-01-01

    The chemistry of graphene oxide is discussed in this critical review. Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure. Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed. This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references).

  10. Trends in reactivity of oxides

    DEFF Research Database (Denmark)

    Toftelund, Anja

    , and I) and OH on a wide range of rutile oxide surfaces. Furthermore, Brønsted-Evans-Polanyi (BEP) relations are found for the adsorption of a large number of molecules (including Cl, Br and I) on transition metal oxides. In these relations the activation energies scale linearly with the dissociative...... chemisorption energies. It turns out that the BEP relation for rutile oxides is almost coinciding with the dissociation line, i.e. no barrier exists for the reactive surfaces. The heterogeneous catalytic oxidation of hydrogen halides (HCl, HBr, and HI) is investigated. A micro-kinetic model is solved...

  11. Low Temperature Oxidation of Methane: The Influence of Nitrogen Oxides

    DEFF Research Database (Denmark)

    Bendtsen, Anders Broe; Glarborg, Peter; Dam-Johansen, Kim

    2000-01-01

    An experimental investigation of methane oxidation in the presence of NO and NO2 has been made in an isothermal plug-flow reactor at 750-1250K. The temperature for on-set of oxidation was lowered by 250 K in the presence of NO or NO2 at residence times of 200 ms. At shorter residence times (140 ms...

  12. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide;

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s...

  13. Heterogeneous oxidation of carbonyl sulfide on mineral oxides

    Institute of Scientific and Technical Information of China (English)

    LIU YongChun; LIU JunFeng; HE Hong; YU YunBo; XUE Li

    2007-01-01

    Heterogeneous oxidation of carbonyl sulfide (OCS) on mineral oxides including SiO2, Fe2O3, CaO, MgO, ZnO and TiO2, which are the main components of atmospheric particles, were investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), ion chromatography (IC), temperature-programmed desorption (TPD), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) methods. The main products and intermediates of the heterogeneous oxidation of OCS on these oxides were identified with in situ DRIFTS and IC. The reaction mechanism and kinetics were also discussed. It is found that the reaction mechanism on these mineral oxides is the same as that on Al2O3 for the same final products and the intermediates at room temperature. Namely, OCS can be catalytically oxidized to produce surface SO42- species and gaseous CO2 through the surface hydrogen thiocarbonate (HSCO2-) and HSO3- species. The activity series for heterogeneous oxidation of OCS follows: Al2O3 ≈ CaO>MgO>TiO2 ≈ ZnO>Fe2O3>SiO2. The specific area, basic hydroxyl and surface basicity of these oxides have effect on the reactivity. This study suggests that heterogeneous reactions of OCS on mineral dust may be an unneglectable sink of OCS.

  14. Semiconductor-oxide heterostructured nanowires using postgrowth oxidation.

    Science.gov (United States)

    Wallentin, Jesper; Ek, Martin; Vainorious, Neimantas; Mergenthaler, Kilian; Samuelson, Lars; Pistol, Mats-Erik; Reine Wallenberg, L; Borgström, Magnus T

    2013-01-01

    Semiconductor-oxide heterointerfaces have several electron volts high-charge carrier potential barriers, which may enable devices utilizing quantum confinement at room temperature. While a single heterointerface is easily formed by oxide deposition on a crystalline semiconductor, as in MOS transistors, the amorphous structure of most oxides inhibits epitaxy of a second semiconductor layer. Here, we overcome this limitation by separating epitaxy from oxidation, using postgrowth oxidation of AlP segments to create axial and core-shell semiconductor-oxide heterostructured nanowires. Complete epitaxial AlP-InP nanowire structures were first grown in an oxygen-free environment. Subsequent exposure to air converted the AlP segments into amorphous aluminum oxide segments, leaving isolated InP segments in an oxide matrix. InP quantum dots formed on the nanowire sidewalls exhibit room temperature photoluminescence with small line widths (down to 15 meV) and high intensity. This optical performance, together with the control of heterostructure segment length, diameter, and position, opens up for optoelectrical applications at room temperature.

  15. EDITORIAL: Oxide semiconductors

    Science.gov (United States)

    Kawasaki, M.; Makino, T.

    2005-04-01

    non-equilibrium growth has rekindled the recent extensive investigation and progress in the field of ZnO epitaxy. In this special issue, Ohtomo and Tsukazaki, Cho et al, and Yi et al, respectively, describe the various fabrication processes such as pulsed laser deposition, molecular-beam epitaxy and metal-organic chemical vapour deposition. It should be noted that the last work among the above-mentioned papers has the potential to pave the way to nano-technology based on ZnO. This material has found other important applications as well, such as transparent conducting oxides (TCO). This field has a long research history, as is reviewed by Minami. Relatively speaking, ZnO was one of the earliest crystals (after Si, Ge, and InSb) to be prepared in a pure form, and the resultant long research history has given rise to the availability of large-area substrates. Recent progress in this topic is explained by two representative groups of authors in this field: Nause and Nemeth at Cermet Inc., and Maeda et al at Tokyo Denpa Co. Ltd. In order to overcome the bottleneck of p-type conduction and control the material's properties, a clear understanding of the physical processes in ZnO is necessary. Look et al are known as the first group to report on the growth and properties of p-type ZnO layers with a valid and reasonable set of experimental data (2002 Appl. Phys. Lett. 81 1830). Here, Look contributes a more comprehensive review to this issue. Optical studies on single crystals were conducted and are reviewed here by Meyer et al and Chichibu et al. Band-gap engineering and fabrication of heterojunction or quantum structures are important technological issues. It should be emphasized that by choosing an appropriate set of concentrations (x and y), perfect lattice-matching between MgxZn1-xO and CdyZn1-yO can be attained (Makino T et al 2001 Appl. Phys. Lett. 78 1237). Exciton properties of multiple quantum well structures are reported by Makino et al in this issue. Other than

  16. Ferromagnet / superconductor oxide superlattices

    Science.gov (United States)

    Santamaria, Jacobo

    2006-03-01

    The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peña^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic

  17. Room Temperature Chemical Oxidation of Delafossite-Type Oxides

    Science.gov (United States)

    Trari, M.; Töpfer, J.; Doumerc, J. P.; Pouchard, M.; Ammar, A.; Hagenmuller, P.

    1994-07-01

    Examination of the delafossite-type structure of CuLaO 2 and CuYO 2 suggests that there is room enough to accomodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu + into Cu 2+. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu 2+ is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: whereas CuLaO 2+ x appears as a single phase, CuYO 2+ x corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported by Cava et al. Comparison is stressed between the oxides obtained by oxidation at room and those obtained at higher temperatures.

  18. Oxide anode materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Fergus, Jeffrey W. [Auburn University, Materials Research and Education Center, 275 Wilmore Laboratories, Auburn, AL 36849 (United States)

    2006-07-15

    A major advantage of solid oxide fuel cells (SOFCs) over polymer electrolyte membrane (PEM) fuel cells is their tolerance for the type and purity of fuel. This fuel flexibility is due in large part to the high operating temperature of SOFCs, but also relies on the selection and development of appropriate materials - particularly for the anode where the fuel reaction occurs. This paper reviews the oxide materials being investigated as alternatives to the most commonly used nickel-YSZ cermet anodes for SOFCs. The majority of these oxides form the perovskite structure, which provides good flexibility in doping for control of the transport properties. However, oxides that form other crystal structures, such as the cubic fluorite structure, have also shown promise for use as SOFC anodes. In this paper, oxides are compared primarily in terms of their transport properties, but other properties relative to SOFC anode performance are also discussed. (author)

  19. Chaperones, but not oxidized proteins, are ubiquitinated after oxidative stress

    DEFF Research Database (Denmark)

    Kästle, Marc; Reeg, Sandra; Rogowska-Wrzesinska, Adelina;

    2012-01-01

    After oxidative stress proteins which are oxidatively modified are degraded by the 20S proteasome. However, several studies documented an enhanced ubiquitination of yet unknown proteins. Since ubiqutination is a prerequisite for degradation by the 26S proteasome in an ATP-dependent manner......, we were able to confirm an increase of ubiquitinated proteins 16h upon oxidative stress. Therefore, we isolated ubiquitinated proteins from hydrogen peroxide treated cells, as well as from control and lactacystin, an irreversible proteasome inhibitor, treated cells, and identified some......, ubiquitinated proteins confirm the thesis that ubiquitination upon oxidative stress is no random process to degrade the mass of oxidized proteins, but concerns a special group of functional proteins....

  20. Hydrogen oxidation in Azospirillum brasilense

    Energy Technology Data Exchange (ETDEWEB)

    Tibelius, K.

    1984-01-01

    Hydrogen oxidation by Azospirillum brasilense Sp7 was studied in N/sub 2/-fixing and NH/sub 4//sup +/-grown batch cultures. The K/sub m/ for H/sub 2/ of O/sub 2/-dependent H/sup 3/H oxidation in whole cells was 9 uM. The rates of H/sup 3/H and H/sub 2/ oxidation were very similar, indicating that the initial H/sub 2/ activation step in the overall H/sub 2/ oxidation reaction was not rate-limiting and that H/sup 3/H oxidation was a valid measure of H/sub 2/-oxidation activity. Hydrogen-oxidation activity was inhibited irreversibly by air. In N-free cultures the O/sub 2/ optima for O/sub 2/-dependent H/sub 2/ oxidation, ranging from 0.5-1.25% O/sub 2/ depending on the phase of growth, were significantly higher than those of C/sub 2/H/sub 2/ reduction, 0.15-0.35%, suggesting that the H/sub 2/-oxidation system may have a limited ability to aid in the protection of nitrogenase against inactivation by O/sub 2/. Oxygen-dependent H/sub 2/ oxidation was inhibited by NO/sub 2//sup +/, NO, CO, and C/sub 2/H/sub 2/ with apparent K/sub 1/ values of 20, 0.4, 28, and 88 uM, respectively. Hydrogen-oxidation activity was 50 to 100 times higher in denitrifying cultures when the terminal electron acceptor for growth was N/sub 2/O rather than NO/sub 3//sup -/, possibly due to the irreversible inhibition of hydrogenase by NO/sub 2//sup -/ and NO in NO/sub 3//sup -/-grown cultures.

  1. Oxidation pathways underlying the pro-oxidant effects of apigenin.

    Science.gov (United States)

    Andueza, Aitor; García-Garzón, Antonia; Ruiz de Galarreta, Marina; Ansorena, Eduardo; Iraburu, María J; López-Zabalza, María J; Martínez-Irujo, Juan J

    2015-10-01

    Apigenin, a natural flavone, is emerging as a promising compound for the treatment of several diseases. One of the hallmarks of apigenin is the generation of intracellular reactive oxygen species (ROS), as judged by the oxidation of reduced dichlorofluorescein derivatives seen in many cell types. This study aimed to reveal some mechanisms by which apigenin can be oxidized and how apigenin-derived radicals affect the oxidation of 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein (H(2)DCF), a probe usually employed to detect intracellular ROS. Apigenin induced a rapid oxidation of H(2)DCF in two different immortalized cell lines derived from rat and human hepatic stellate cells. However, apigenin did not generate ROS in these cells, as judged by dihydroethidium oxidation and extracellular hydrogen peroxide production. In cell-free experiments we found that oxidation of apigenin leads to the generation of a phenoxyl radical, which directly oxidizes H(2)DCF with catalytic amounts of hydrogen peroxide. The net balance of the reaction was the oxidation of the probe by molecular oxygen due to redox cycling of apigenin. This flavonoid was also able to deplete NADH and glutathione by a similar mechanism. Interestingly, H(2)DCF oxidation was significantly accelerated by apigenin in the presence of horseradish peroxidase and xanthine oxidase, but not with other enzymes showing peroxidase-like activity, such as cytochrome c or catalase. We conclude that in cells treated with apigenin oxidation of reduced dichlorofluorescein derivatives does not measure intracellular ROS and that pro- and antioxidant effects of flavonoids deduced from these experiments are inconclusive and must be confirmed by other techniques.

  2. Effects of Oxidation on Oxidation-Resistant Graphite

    Energy Technology Data Exchange (ETDEWEB)

    Windes, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Rebecca [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carroll, Mark [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-05-01

    The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.

  3. Solid Oxide Electrolyser Cell

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard

    Solid oxide fuel cells (SOFCs) produced at Risø National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 °C and a cell voltage of 1.48V the current density was -3.6A/cm2 with app. 30% H2 + 70% H2O in the inlet...... it is possible to achieve a production price of 0.7 US$/kg H2 with an electricity price of 1.3 US¢/kWh. The cell voltage was measured as function of time. In test ofabout two month of duration a long-term degradation was observed. At 850 °C, -0.5 A/cm2 with 50 vol% H2 the degradation rate was app. 20 mV/1000h...

  4. Phosphine oxide surfactants revisited.

    Science.gov (United States)

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (C(n)DMPO) and alkyl diethyl (C(n)DEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties.

  5. Main Oxidizer Valve Design

    Science.gov (United States)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  6. Zinc Oxide Nanoparticle Photodetector

    Directory of Open Access Journals (Sweden)

    Sheng-Po Chang

    2012-01-01

    Full Text Available A zinc oxide (ZnO nanoparticle photodetector was fabricated using a simple method. Under a 5 V applied bias, its dark current and photocurrent were 1.98×10-8 and 9.42×10-7 A, respectively. In other words, a photocurrent-to-dark-current contrast ratio of 48 was obtained. Under incident light at a wavelength of 375 nm and a 5 V applied bias, the detector’s measured responsivity was 3.75 A/W. The transient time constants measured during the turn-ON and turn-OFF states were τON=204 s and τOFF=486 s, respectively.

  7. Wet oxidation of a spacecraft model waste

    Science.gov (United States)

    Johnson, C. C.; Wydeven, T.

    1985-01-01

    Wet oxidation was used to oxidize a spacecraft model waste under different oxidation conditions. The variables studied were pressure, temperature, duration of oxidation, and the use of one homogeneous and three heterogeneous catalysts. Emphasis is placed on the final oxidation state of carbon and nitrogen since these are the two major components of the spacecraft model waste and two important plant nutrients.

  8. Detecting Organic Compounds Released from Iron Oxidizing Bacteria using Sample Analysis at Mars (SAM)-like Instrument Protocols

    Science.gov (United States)

    Glavin, D. P.; Popa, R.; Martin, M. G.; Freissinet, C.; Fisk, M. R.; Dworkin, J. P.; Mahaffy, P. R.

    2012-12-01

    Mars is a planet of great interest for Astrobiology since its past environmental conditions are thought to have been favourable for the emergence life. At present, the Red Planet is extremely cold and dry and the surface is exposed to intense UV and ionizing radiation, conditions generally considered to be incompatible with life as we know it on Earth. It was proposed that the shallow subsurface of Mars, where temperatures can be above freezing and liquid water can exist on rock surfaces, could harbor chemolithoautotrophic bacteria such as the iron oxidizing microorganism Pseudomonas sp. HerB [Popa et al. 2012]. The Mars Science Laboratory (MSL) mission will provide the next opportunity to carry out in situ measurements for organic compounds of possible biological origin on Mars. One instrument onboard MSL, called the Sample Analysis at Mars (SAM) instrument suite, will carry out a broad and sensitive search for organic compounds in surface samples using either high temperature pyrolysis or chemical extraction followed by gas chromatography mass spectrometry [Mahaffy et al. 2012]. We present gas chromatograph mass spectrometer (GC/MS) data on crushed olivine rock powders that have been inoculated with Pseudomonas sp. HerB at different concentrations ranging from ~102 to 107 cells per gram. The inoculated olivine samples were heated under helium carrier gas flow at 500°C and the pyrolysis products concentrated using a SAM-like hydrocarbon trap set at -20°C followed by trap heating and analysis by GC/MS. In addition, the samples were also extracted using a low temperature "one-pot" chemical extraction technique using N-methyl, N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) as the silylating agent prior to GC/MS analysis [Stalport et al. 2012]. We identified several aldehydes, thiols, and alkene nitriles after pyrolysis GC/MS analysis of the bacteria that were not found in the olivine control samples that had not been inoculated with bacteria. The

  9. Bilirubin oxidation in brain.

    Science.gov (United States)

    Hansen, T W

    2000-01-01

    Bilirubin is a product of heme catabolism which by virtue of its lipid solubility can cross the blood-brain barrier and enter the brain. Neonatal jaundice is a common transitional phenomenon which is due to the combination of increased heme catabolism and rate limitations as far as hepatic conjugation and biliary excretion of bilirubin. In the great majority of cases this is an innocuous condition, which is even posited to have some beneficial effects due to the ability of bilirubin to quench free oxygen radicals. However, because bilirubin is neurotoxic, hyperbilirubinemia in the newborn may exceptionally result in death in the neonatal period, or survival with severe neurological sequelae (kernicterus). Bilirubin enters the brain through an intact blood-brain barrier. Clearance of bilirubin from brain partly involves retro-transfer through the blood-brain barrier, and possibly also through the brain-CSF barrier into CSF. Work in our lab during the past 5 years has substantiated earlier work which had suggested that bilirubin may also be metabolized in brain. The responsible enzyme is found on the inner mitochondrial membrane, and oxidizes bilirubin at a rate of 100-300 pmol bilirubin/mg protein/minute. The enzyme activity is lower in the newborn compared with the mature animal, and is also lower in neurons compared with glia. Studies of different rat strains have documented genetic variability. The enzyme is cytochrome-c-dependent, but has as yet not been unequivocally identified. The rate of oxidation of bilirubin is such that this enzyme probably contributes meaningfully to the clearance of bilirubin from brain.

  10. Oxidative stress in Parkinson's disease.

    Science.gov (United States)

    Nikam, Shashikant; Nikam, Padmaja; Ahaley, S K; Sontakke, Ajit V

    2009-01-01

    Oxidative stress contributes to the cascade, leading to dopamine cell degeneration in Parkinson's disease. However, oxidative stress is intimately linked to other components of the degenerative process, such as mitochondrial dysfunction, excitotoxicity, nitric oxide toxicity and inflammation. It is therefore difficult to determine whether oxidative stress leads to or is a consequence of, these events. Oxidative stress was assessed by estimating lipid peroxidation product in the form of thiobarbituric acid reactive substances, nitric oxide in the form of nitrite & nitrate. Enzymatic antioxidants in the form of superoxide dismutase, glutathione peroxidase, catalase, ceruloplasmin and non enzymatic antioxidant vitamins e.g. vitamin E and C in either serum or plasma or erythrocyte in 40 patients of Parkinson's disease in the age group 40-80 years. Trace elements e.g. copper, zinc and selenium were also estimated. Plasma thiobarbituric acid reactive substances and nitric oxide levels were Significantly high but superoxide dismutase, glutathione peroxidase, catalase, ceruloplasmin, vitamin-E, vitamin-C, copper, zinc and selenium levels were significantly low in Parkinson's disease when compared with control subjects. Present study showed that elevated oxidative stress may be playing a role in dopaminergic neuronal loss in substentia nigra pars compacta and involved in pathogenesis of the Parkinson's disease.

  11. Inhibiting Wet Oxidation of Ammonia

    Science.gov (United States)

    Onisko, D. B. L.

    1985-01-01

    Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

  12. Stabilization of elusive silicon oxides.

    Science.gov (United States)

    Wang, Yuzhong; Chen, Mingwei; Xie, Yaoming; Wei, Pingrong; Schaefer, Henry F; Schleyer, Paul von R; Robinson, Gregory H

    2015-06-01

    Molecular SiO2 and other simple silicon oxides have remained elusive despite the indispensable use of silicon dioxide materials in advanced electronic devices. Owing to the great reactivity of silicon-oxygen double bonds, as well as the low oxidation state of silicon atoms, the chemistry of simple silicon oxides is essentially unknown. We now report that the soluble disilicon compound, L:Si=Si:L (where L: = :C{N(2,6-(i)Pr2C6H3)CH}2), can be directly oxidized by N2O and O2 to give the carbene-stabilized Si2O3 and Si2O4 moieties, respectively. The nature of the silicon oxide units in these compounds is probed by spectroscopic methods, complementary computations and single-crystal X-ray diffraction.

  13. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  14. Nanotoxicology of Metal Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Amedea B. Seabra

    2015-06-01

    Full Text Available This review discusses recent advances in the synthesis, characterization and toxicity of metal oxide nanoparticles obtained mainly through biogenic (green processes. The in vitro and in vivo toxicities of these oxides are discussed including a consideration of the factors important for safe use of these nanomaterials. The toxicities of different metal oxide nanoparticles are compared. The importance of biogenic synthesized metal oxide nanoparticles has been increasing in recent years; however, more studies aimed at better characterizing the potent toxicity of these nanoparticles are still necessary for nanosafely considerations and environmental perspectives. In this context, this review aims to inspire new research in the design of green approaches to obtain metal oxide nanoparticles for biomedical and technological applications and to highlight the critical need to fully investigate the nanotoxicity of these particles.

  15. BRCA1 and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Yong Weon Yi

    2014-04-01

    Full Text Available The breast cancer susceptibility gene 1 (BRCA1 has been well established as a tumor suppressor and functions primarily by maintaining genome integrity. Genome stability is compromised when cells are exposed to oxidative stress. Increasing evidence suggests that BRCA1 regulates oxidative stress and this may be another mechanism in preventing carcinogenesis in normal cells. Oxidative stress caused by reactive oxygen species (ROS is implicated in carcinogenesis and is used strategically to treat human cancer. Thus, it is essential to understand the function of BRCA1 in oxidative stress regulation. In this review, we briefly summarize BRCA1’s many binding partners and mechanisms, and discuss data supporting the function of BRCA1 in oxidative stress regulation. Finally, we consider its significance in prevention and/or treatment of BRCA1-related cancers.

  16. Ethylene oxide removal by sorption on aluminium oxide

    Directory of Open Access Journals (Sweden)

    Arsenijević Zorana Lj.

    2009-01-01

    Full Text Available The dynamics of ethylene oxide sorption and desorption on Al2O3 sorbent were investigated. The investigations of ethylene oxide sorption on Al2O3 show that significant sorption appeared above 125°C. The removal of sorbed ethylene oxide from Al2O3 was achieved by continuous increasing of the temperature up to 450°C in air stream. The analysis of desorbed products show that 90% of adsorbed ethylene oxide is converted to CO2 and the rest consists of the three derivatives of ethylene oxide. The exact composition of desorbed organic products will be determined in further investigation. The desorption temperature profiles point out the presence of two exothermic picks, as was confirmed by detection of CO2 and derivates of ethylene oxide at these temperatures. Investigation of textural characteristics and thermal stability of Al2O3 sorbent show that there are no changes of any characteristics of Al2O3 in sorption/desorption operating temperatures regimes. Only at 700°C the specific surface area of Al2O3 decreases of about 10%. This indicates that the investigated Al2O3 is convenient material for removal of ethylene oxide by sorption.

  17. Periodate Oxidation of Methylcellulose: Characterization and Properties of Oxidized Derivatives

    Directory of Open Access Journals (Sweden)

    Marguerite Rinaudo

    2010-10-01

    Full Text Available In this paper, the behavior of oxidized methylcelluloses is compared with that of the initial methylcellulose, an amphiphilic cellulose derivative. Methylcelluloses are important for many applications in the cosmetic and food industries. The mechanism of thermo-gelation of methylcellulose is briefly explained as well as the method of oxidation of polysaccharides. Then, our experiments involve the preparation of oxidized methylcelluloses: three degrees of oxidation are prepared and the new polymers are characterized by NMR, IR, SEC and rheology. Oxidation with periodate theoretically allows introduction of two aldehydic groups on C2–C3 glycol positions of anhydroglucose units. This reaction not only enhances the flexibility of the cellulosic backbone, but also causes a decrease in the molecular weight. In particular, the rheological behavior of methylcellulose and oxidized methylcellulose as a function of temperature is examined. The oxidized methylcelluloses prepared, being rich in aldehyde functions, become interesting intermediaries to prepare new cellulose derivatives. In this paper, three examples of reductive amination based on the reaction of modified methylcelluloses and −NH2 groups of different molecules are described: β-alanine produces a polyelectrolyte; chitosan and hyaluronan-ADH (derivative obtained with adipic dihydrazide allowing introduction of −NH2 functions on HA backbone are crosslinked and give new biocompatible hydrogels.

  18. Trends for Methane Oxidation at Solid Oxide Fuel Cell Conditions

    DEFF Research Database (Denmark)

    Kleis, Jesper; Jones, Glenn; Abild-Pedersen, Frank;

    2009-01-01

    the Ni surfaces to other metals of interest. This allows the reactivity over the different metals to be understood in terms of two reactivity descriptors, namely, the carbon and oxygen adsorption energies. By combining a simple free-energy analysis with microkinetic modeling, activity landscapes of anode......First-principles calculations are used to predict a plausible reaction pathway for the methane oxidation reaction. In turn, this pathway is used to obtain trends in methane oxidation activity at solid oxide fuel cell (SOFC) anode materials. Reaction energetics and barriers for the elementary...

  19. Oxidants, antioxidants and carcinogenesis.

    Science.gov (United States)

    Ray, Gibanananda; Husain, Syed Akhtar

    2002-11-01

    Reactive oxygen metabolites (ROMs), such as superoxide anions (O2*-) hydrogen peroxide (H2O2), and hydroxyl radical (*OH), malondialdehyde (MDA) and nitric oxide (NO) are directly or indirectly involved in multistage process of carcinogenesis. They are mainly involved in DNA damage leading sometimes to mutations in tumour suppressor genes. They also act as initiator and/or promotor in carcinogenesis. Some of them are mutagenic in mammalian systems. O2*-, H2O2 and *OH are reported to be involved in higher frequencies of sister chromatid exchanges (SCEs) and chromosome breaks and gaps (CBGs). MDA, a bi-product of lipid peroxidation (LPO), is said to be involved in DNA adduct formations, which are believed to be responsible for carcinogenesis. NO, on the other hand, plays a duel role in cancer. At high concentration it kills tumour cells, but at low concentration it promotes tumour growth and metastasis. It causes DNA single and double strand breaks. The metabolites of NO such as peroxynitrite (OONO-) is a potent mutagen that can induce transversion mutations. NO can stimulate O2*-/H2O2/*OH-induced LPO. These deleterious actions of oxidants can be countered by antioxidant defence system in humans. There are first line defense antioxidants such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). SOD converts O2*- to H2O2, which is further converted to H2O with the help of GPx and CAT. SOD inhibits *OH production. SOD also act as antipoliferative agent, anticarcinogens, and inhibitor at initiation and promotion/transformation stage in carcinogenesis. GPx is another antioxidative enzyme which catalyses to convert H2O2, to H2O. The most potent enzyme is CAT. GPx and CAT are important in the inactivation of many environmental mutagens. CAT is also found to reduce the SCE levels and chromosomal aberrations. Antioxidative vitamins such as vitamin A, E, and C have a number of biological activities such as immune stimulation, inhibition of

  20. The oxidation and corrosion of ODS alloys

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1990-01-01

    The oxidation and hot corrosion of high temperature oxide dispersion strengthened (ODS) alloys are reviewed. The environmental resistance of such alloys are classified by oxide growth rate, oxide volatility, oxide spalling, and hot corrosion limitations. Also discussed are environmentally resistant coatings for ODS materials. It is concluded that ODS NiCrAl and FeCrAl alloys are highly oxidation and corrosion resistant and can probably be used uncoated.

  1. Oxidation And Hot Corrosion Of ODS Alloy

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1993-01-01

    Report reviews oxidation and hot corrosion of oxide-dispersion-strengthened (ODS) alloys, intended for use at high temperatures. Classifies environmental resistances of such alloys by rates of growth of oxides, volatilities of oxides, spalling of oxides, and limitations imposed by hot corrosion. Also discusses environmentally resistant coatings for ODS materials. Concludes ODS NICrAl and FeCrAl alloys highly resistant to oxidation and corrosion and can be used uncoated.

  2. Bio-oxidation of arsenopyrite

    Institute of Scientific and Technical Information of China (English)

    JIANG Tao; LI Qian; YANG Yong-bin; LI Guang-hui; QIU Guan-zhou

    2008-01-01

    Oxidation of arsenopyrite with Acidithiobacillus ferrooxidans was studied.The electrochemical results show that arsenopyrite is firstly oxidized to As2S2 at the potential of 0.2-0.3 V (vs SHE) and As2S2 covers the electrode and retards the process continuously.While at higher potential over 0.3 V (vs SHE),As2S2 is oxidized to H3AsO3,and H3AsO3 is then oxidized to H3AsO4 at 0.8 V (vs SHE).The leaching results show that the addition of FeS2 can promote the oxidation of As3+ to As5+ and increase the activity of the bacteria.The best bio-oxidation technical parameters are the initial pH of 1.8-2.0,particle sizes less than 0.074 mm,temperature in the range of 25-30 ℃ and rotating speed of the orbital incubator of 100-160 r/min.The results provide theoretical and technological supports of bio-oxidation arsenopyrite for pretreating refractory arsenic gold ores.

  3. Room temperature chemical oxidation of delafossite-type oxides

    Energy Technology Data Exchange (ETDEWEB)

    Trari, M.; Toepfer, J.; Doumerc, J.P.; Pouchard, M.; Hagenmuller, P. (Laboratoire de Chimie du Solide du CNRS, Talence (France)); Ammar, A. (Universite Cadi Ayyad, Marrakech (Morocco))

    1994-07-01

    Examination of the delafossite-type structure of CuLaO[sub 2] and CuYO[sub 2] suggests that there is room enough to accommodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu[sup +] into Cu[sup 2+]. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu[sup 2+] is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: Whereas CuLaO[sub 2+x] appears as a single phase, CuYO[sub 2+x] corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported. Comparison is stressed between the oxides obtained at higher temperatures.

  4. Selective propene oxidation on mixed metal oxide catalysts

    CERN Document Server

    James, D W

    2002-01-01

    Selective catalytic oxidation processes represent a large segment of the modern chemical industry and a major application of these is the selective partial oxidation of propene to produce acrolein. Mixed metal oxide catalysts are particularly effective in promoting this reaction, and the two primary candidates for the industrial process are based on iron antimonate and bismuth molybdate. Some debate exists in the literature regarding the operation of these materials and the roles of their catalytic components. In particular, iron antimonate catalysts containing excess antimony are known to be highly selective towards acrolein, and a variety of proposals for the enhanced selectivity of such materials have been given. The aim of this work was to provide a direct comparison between the behaviour of bismuth molybdate and iron antimonate catalysts, with additional emphasis being placed on the component single oxide phases of the latter. Studies were also extended to other antimonate-based catalysts, including coba...

  5. Oxidative desulfurization: kinetic modelling.

    Science.gov (United States)

    Dhir, S; Uppaluri, R; Purkait, M K

    2009-01-30

    Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H(2)O(2) over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel.

  6. Nitric oxide and cardiovascular system.

    Science.gov (United States)

    Cengel, Atiye; Sahinarslan, Asife

    2006-12-01

    Endothelium has many important functions including the control of blood-tissue permeability and vascular tonus, regulation of vascular surface properties for homeostasis and inflammation. Nitric oxide is the chief molecule in regulation of endothelial functions. Nitric oxide deficiency, which is also known as endothelial dysfunction, is the first step for the occurrence of many disease states in cardiovascular system including heart failure, hypertension, dyslipidemia, insulin resistance, diabetes mellitus, hyperhomocysteinemia and smoking. This review deals with the importance of nitric oxide for cardiovascular system. It also includes the latest improvements in the diagnosis and treatment of endothelial dysfunction.

  7. Abiotic oxidation of catechol by soil metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Colarieti, Maria Letizia [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, Naples (Italy); Toscano, Giuseppe [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, Naples (Italy)]. E-mail: giuseppe.toscano@unina.it; Ardi, Maria Raffaella [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, Naples (Italy); Greco, Guido [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, Naples (Italy)

    2006-06-30

    The mechanism of catechol oxidation by soil metal oxides is investigated in a slurry reactor. This abiotic transformation is shown to consist in a three-step process. The first step is a heterogeneous reaction. Catechol undergoes fast, partial oxidation at the expenses of Fe and Mn oxides contained in the soil. In the second step, reduced Fe and Mn are released into the aqueous solution and immediately complexed by catechol. Metal-catecholate complexes are stable at the very low dissolved-oxygen concentration levels attained under nitrogen sparging. The third step is a homogenous reaction. The highly reactive intermediate produced by catechol partial oxidation initiates catechol polymerisation. Under nitrogen sparging, the polymerisation process ends rather rapidly, thus yielding only partial conversion of the phenol and producing low-molecular weight, water-soluble polymers. Further oxidation of the metal-catecholate complexes formed in the second step only occurs under air sparging. Thus, reactive intermediates are formed at much higher concentration levels than those attained when nearly no oxygen is present in solution. The polymerisation proceeds at a much faster rate until, under the experimental conditions adopted, complete catechol conversion is attained and high-molecular-weight, insoluble polymers are produced.

  8. Nanometer bismuth oxide produced by resistance heating vapor oxidation

    Institute of Scientific and Technical Information of China (English)

    HU Han-xiang; QIU Ke-qiang

    2006-01-01

    Bismuth oxide has wide applications in superconductive material, photoelectric material, electronic ceramic, electrolyte, and catalysts. To produce ultrafine bismuth oxide powders, some costly heating sources, such as plasma, high frequency induction, electron beam or laser, have to be used in the conventional vapor oxidation methods. The vapor oxidation method was improved by adding a reducing agent in the reaction system, where heating source was resistance tubular oven, instead of special heat source requirement. Nanometer bismuth oxide was prepared at 1 000-1 140 ℃, and the particle characteristics were investigated by XRD, SEM, DTA, laser sedimentograph. With low oxygen concentration (less than 20%) in the carrier gas, the bismuth oxide particle was near-sphere β-Bi2O3 with uniform and fine particle size (d0.5=65 nm, GSD=1.42); while with higher oxygen content (more than 50%), the powders were mixture of Bi2O2CO3 and β-Bi2O3.

  9. Synthesis of vertically aligned metal oxide nanostructures

    KAUST Repository

    Roqan, Iman S.

    2016-03-03

    Metal oxide nanostructure and methods of making metal oxide nanostructures are provided. The metal oxide nanostructures can be 1 -dimensional nanostructures such as nanowires, nanofibers, or nanotubes. The metal oxide nanostructures can be doped or undoped metal oxides. The metal oxide nanostructures can be deposited onto a variety of substrates. The deposition can be performed without high pressures and without the need for seed catalysts on the substrate. The deposition can be performed by laser ablation of a target including a metal oxide and, optionally, a dopant. In some embodiments zinc oxide nanostructures are deposited onto a substrate by pulsed laser deposition of a zinc oxide target using an excimer laser emitting UV radiation. The zinc oxide nanostructure can be doped with a rare earth metal such as gadolinium. The metal oxide nanostructures can be used in many devices including light-emitting diodes and solar cells.

  10. Catastrophic Oxidation of Copper: A Brief Review

    Science.gov (United States)

    Belousov, V. V.; Klimashin, A. A.

    2012-10-01

    A brief review of the current understanding of copper accelerated oxidation in the presence of low-melting oxides (Bi2O3, MoO3, and V2O5) is given. Special attention is paid to the kinetics, thermodynamics, and mechanisms of accelerated oxidation of copper. The mechanisms of two stages (fast and superfast) of the copper accelerated oxidation are considered. It is shown that the fast oxidation of copper occurs by a diffusion mechanism. Oxygen diffusion along the liquid channels in the oxide scale is the rate-limiting step in the overall mechanism. The superfast oxidation of copper occurs by a fluxing mechanism. Realization of the particular mechanism depends on the mass ratio of low-melting oxide to the metal. The mass ratios of low-melting oxide to the metal and the oxygen partial pressures for superfast oxidation of copper are established. A model of the fast oxidation of copper is discussed.

  11. Non-conventional halide oxidation pathways : oxidation by imidazole triplet and surface specific oxidation by ozone

    Science.gov (United States)

    Ammann, Markus; Corral-Arroyo, Pablo; Aellig, Raphael; Orlando, Fabrizio; Lee, Ming-Tao; Artiglia, Luca

    2016-04-01

    Oxidation of halide ions (chloride, bromide, iodide) are the starting point of halogen release mechanisms out of sea water, marine aerosol or other halide containing continental aerosols. Slow oxidation of chloride and bromide by ozone in the bulk aqueous phase is of limited relevance. Faster surface specific oxidation has been suggested based on heterogeneous kinetics experiments. We provide first insight into very efficient bromide oxidation by ozone at the aqueous solution - air interface by surface sensitive X-ray photoelectron spectroscopy indicating significant build-up of an oxidized intermediate at the surface within millisecond time scales. The second source of oxidants in the condensed we have considered is the absorption of light by triplet forming photosensitizers at wavelengths longer than needed for direct photolysis and radical formation. We have performed coated wall flow tube experiments with mixtures of citric acid (CA) and imidazole-2-carboxaldehyde (IC) to represent secondary organic material rich marine aerosol. The halide ions bromide and iodide have been observed to act as efficient electron donors leading to their oxidation, HO2 formation and finally release of molecular halogen compounds. The photosensitization of imidazole-2-carboxaldehyde (IC) involves a well-known mechanism where the triplet excited state of IC is reduced by citric acid to a reduced ketyl radical that reacts with halide ions. A competition kinetics approach has been used to evaluate the rate limiting steps and to assess the significance of this source of halogens to the gas phase.

  12. Resonating Nitrous Oxide Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AeroAstro proposes decomposing nitrous oxide (N2O) as an alternative propellant to existing spacecraft propellants. Decomposing N2O can be used as either a high Isp,...

  13. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    Science.gov (United States)

    This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. This information is provided to assist remedial project managers, contractors...

  14. Oxidative stability of marine phospholipids

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline Pascale

    Many studies have shown that marine phospholipids (MPL) provide more advantages than fish oil. They have better bioavailability, better resistance towards oxidation and higher content of eicosapentaenoic acids (EPA) and docosahexaenoic acids (DHA) than oily triglycerides (fish oil). The objective...

  15. Inorganic chemistry: Deconstructing water oxidation

    Science.gov (United States)

    Cook, Sarah A.; Borovik, A. S.

    2013-04-01

    During photosynthesis, the oxygen-evolving complex oxidizes water to produce molecular oxygen. Now, a possible role for the calcium ion in this complex has been proposed based on the electrochemical properties of a series of synthetic heterometallic clusters.

  16. Millisecond Oxidation of Alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Scott Han

    2011-09-30

    This project was undertaken in response to the Department of Energy's call to research and develop technologies 'that will reduce energy consumption, enhance economic competitiveness, and reduce environmental impacts of the domestic chemical industry.' The current technology at the time for producing 140 billion pounds per year of propylene from naphtha and Liquified Petroleum Gas (LPG) relied on energy- and capital-intensive steam crackers and Fluidized Catalytic Cracking (FCC) units. The propylene is isolated from the product stream in a costly separation step and subsequently converted to acrylic acid and other derivatives in separate production facilities. This project proposed a Short Contact Time Reactor (SCTR)-based catalytic oxydehydrogenation process that could convert propane to propylene and acrylic acid in a cost-effective and energy-efficient fashion. Full implementation of this technology could lead to sizeable energy, economic and environmental benefits for the U. S. chemical industry by providing up to 45 trillion BTUs/year, cost savings of $1.8 billion/year and a combined 35 million pounds/year reduction in environmental pollutants such as COx, NOx, and SOx. Midway through the project term, the program directive changed, which approval from the DOE and its review panel, from direct propane oxidation to acrylic acid at millisecond contact times to a two-step process for making acrylic acid from propane. The first step was the primary focus, namely the conversion of propane to propylene in high yields assisted by the presence of CO2. The product stream from step one was then to be fed directly into a commercially practiced propylene-to-acrylic acid tandem reactor system.

  17. Oxidative stress and hypertension.

    Science.gov (United States)

    Harrison, David G; Gongora, Maria Carolina

    2009-05-01

    This review has summarized some of the data supporting a role of ROS and oxidant stress in the genesis of hypertension. There is evidence that hypertensive stimuli, such as high salt and angiotensin II, promote the production of ROS in the brain, the kidney, and the vasculature and that each of these sites contributes either to hypertension or to the untoward sequelae of this disease. Although the NADPH oxidase in these various organs is a predominant source, other enzymes likely contribute to ROS production and signaling in these tissues. A major clinical challenge is that the routinely used antioxidants are ineffective in preventing or treating cardiovascular disease and hypertension. This is likely because these drugs are either ineffective or act in a non-targeted fashion, such that they remove not only injurious ROS Fig. 5. Proposed role of T cells in the genesis of hypertension and the role of the NADPH oxidase in multiple cells/organs in modulating this effect. In this scenario, angiotensin II stimulates an NADPH oxidase in the CVOs of the brain, increasing sympathetic outflow. Sympathetic nerve terminals in lymph nodes activate T cells, and angiotensin II also directly activates T cells. These stimuli also activate expression of homing signals in the vessel and likely the kidney, which attract T cells to these organs. T cells release cytokines that stimulate the vessel and kidney NADPH oxidases, promoting vasoconstriction and sodium retention. SFO, subfornical organ. 630 Harrison & Gongora but also those involved in normal cell signaling. A potentially important and relatively new direction is the concept that inflammatory cells such as T cells contribute to hypertension. Future studies are needed to understand the interaction of T cells with the CNS, the kidney, and the vasculature and how this might be interrupted to provide therapeutic benefit.

  18. Environmentally Friendly Zirconium Oxide Pretreatment

    Science.gov (United States)

    2013-05-01

    chemistries and is intended to coat interstitial spaces between crystals, and to provide a more insoluble layer at the crystal surface.12 Because...distinct layers (metal/metal oxide and organic coatings), it must have functional groups that interact with both layers. In general, organometallic ...fluorides. In sol-gel chemistry , the applied coating must progress through condensation reactions to transform from a mixed oxide/hydroxide state to

  19. In-Situ Chemical Oxidation

    Science.gov (United States)

    2006-08-01

    desirable in ISFO; therefore, pretreatment via acid injection or acidification of the injected H2O2 solution is common. The overall Fenton-driven...catalyzed by several substances including solid alkalis , metals, metal oxides, carbon, and moisture in the gas phase. Depending on the reactivity...biostimulation with sodium lactate, and at the other two sites, a significant increase in the post-oxidation microbial biomass , and the post-oxi- dation

  20. Functional Hybrid Nano-Oxides

    Science.gov (United States)

    2015-10-26

    ABSTRACT This project was dedicated to investigate and engineer novel properties of oxide based materials , nanostructures and devices with properties that...mechanism for the metal-insulator transition and it also opens up the possibility for the preparation of unique nanostructured materials . A second major...spare time since the funding ended before. Development of novel synthesis and characterization methods in area of Nano-Oxides paved the way to

  1. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square-root relati......-root relationship between the rate of change of resistivity and the resistivity change. The saturation defect density at room temperature is estimated on the basis of a model for defect creation in cuprous oxide....

  2. Catalytic Chemistry on Oxide Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek; Kay, Bruce D.; Rodriquez, Jose A.; Rousseau, Roger J.; Stacchiola, Dario; Weaver, Jason F.

    2016-05-29

    Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus on demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.

  3. 21 CFR 186.1300 - Ferric oxide.

    Science.gov (United States)

    2010-04-01

    ... iron hydroxide oxide. The product is red-brown to black trigonal crystals. (b) In accordance with § 186... Substances Affirmed as GRAS § 186.1300 Ferric oxide. (a) Ferric oxide (iron (III) oxide, Fe2O3, CAS Reg....

  4. Metal oxide nanostructures with hierarchical morphology

    Science.gov (United States)

    Ren, Zhifeng; Lao, Jing Yu; Banerjee, Debasish

    2007-11-13

    The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

  5. 49 CFR 173.337 - Nitric oxide.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Nitric oxide. 173.337 Section 173.337... SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be... valve and valve seat that will not deteriorate in contact with nitric oxide. Cylinders or valves may...

  6. Solid oxide electrolyser cell

    Energy Technology Data Exchange (ETDEWEB)

    Hoejgaard Jensen, S.

    2006-12-15

    Solid oxide fuel cells (SOFCs) produced at Riso National Laboratory was tested as steam electrolysers under various current densities, operating temperatures and steam partial pressures. At 950 deg. C and a cell voltage of 1.48V the current density was -3.6 A/cm{sup 2} with app. 30% H{sub 2} + 70% H{sub 2}O in the inlet gas and a H{sub 2}O utilization of app. 40%. The tested SOECs were also used for CO{sub 2} electrolysis. Economy studies of CO and H2 production show that especially H{sub 2} production can be competitive in areas with cheap electricity. Assuming the above described initial performance and a lifetime of 10 years it is possible to achieve a production price of 0.7 US dollar/kg H{sub 2} with an electricity price of 1.3 US cent/kWh. The cell voltage was measured as function of time. In test of about two month of duration a long-term degradation was observed. At 850 deg. C, -0.5 A/cm{sup 2} with 50 vol% H{sub 2} the degradation rate was app. 20 mV/1000h. It was shown that the degradation happens at Ni/YSZ-electrode. The long term degradation is probably caused by coarsening of the Ni-particles. After onset of electrolysis operation a transient passivation/reactivation phenomena with duration of several days was observed. It was shown that the phenomenon is attributed to the SiO{sub 2} contamination at the Ni/YSZ electrode-electrolyte interface. The SiO{sub 2} arises from the albite glass sealing (NaAlSi{sub 3}O{sub 8}) that surrounds the electrode. Si may enter the Ni/YSZ electrode via the reaction Si(OH){sub 4}(g) {r_reversible} SiO{sub 2}(l)+H{sub 2}O(g). At the active sites of the Ni/YSZ electrode steam is reduced via the reaction H{sub 2}O - 2e {yields} H{sub 2}+O{sup 2-} . This shifts the equilibrium of the first reaction to form SiO{sub 2}(l) at the active sites. After a certain time the sealing crystallizes and the SiO{sub 2}(l) evaporates from the active sites and the cell reactivates. The passivation is shown to relate to a build up of a

  7. Protein oxidation in muscle foods: A review

    DEFF Research Database (Denmark)

    Lund, Marianne; Heinonen, Marina; Baron, Caroline P.

    2011-01-01

    insight into the reactions involved in the oxidative modifications undergone by muscle proteins. Moreover, a variety of products derived from oxidized muscle proteins, including cross-links and carbonyls, have been identified. The impact of oxidation on protein functionality and on specific meat quality...... and consequences of Pox in muscle foods. The efficiency of different anti-oxidant strategies against the oxidation of muscle proteins is also reported.......Protein oxidation in living tissues is known to play an essential role in the pathogenesis of relevant degenerative diseases, whereas the occurrence and impact of protein oxidation (Pox) in food systems have been ignored for decades. Currently, the increasing interest among food scientists...

  8. Size of oxide vacancies in fluorite and perovskite structured oxides

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Norby, Poul; Hendriksen, Peter Vang

    2015-01-01

    An analysis of the effective radii of vacancies and the stoichiometric expansion coefficient is performed on metal oxides with fluorite and perovskite structures. Using the hard sphere model with Shannon ion radii we find that the effective radius of the oxide vacancy in fluorites increases...... with increasing ion radius of the host cation and that it is significantly smaller than the radius of the oxide ion in all cases, from 37% smaller for HfO2 to 13 % smaller for ThO2. The perovskite structured LaGaO3 doped with Sr or Mg or both is analyzed in some detail. The results show that the effective radius...... of an oxide vacancy in doped LaGaO3 is only about 6 % smaller than the oxide ion. In spite of this the stoichiometric expansion coefficient (a kind of chemical expansion coefficient) of the similar perovskite, LaCrO3, is significantly smaller than the stoichiometric expansion coefficient of the fluorite...

  9. Oxidative stress and anti-oxidative mobilization in burn injury.

    Science.gov (United States)

    Parihar, Arti; Parihar, Mordhwaj S; Milner, Stephen; Bhat, Satyanarayan

    2008-02-01

    A severe burn is associated with release of inflammatory mediators which ultimately cause local and distant pathophysiological effects. Mediators including Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are increased in affected tissue, which are implicated in pathophysiological events observed in burn patients. The purpose of this article is to understand the role of oxidative stress in burns, in order to develop therapeutic strategies. All peer-reviewed, original and review articles published in the English language literature relevant to the topic of oxidative stress in burns in animals and human subjects were selected for this review and the possible roles of ROS and RNS in the pathophysiology of burns are discussed. Both increased xanthine oxidase and neutrophil activation appear to be the oxidant sources in burns. Free radicals have been found to have beneficial effects on antimicrobial action and wound healing. However following a burn, there is an enormous production of ROS which is harmful and implicated in inflammation, systemic inflammatory response syndrome, immunosuppression, infection and sepsis, tissue damage and multiple organ failure. Thus clinical response to burn is dependent on the balance between production of free radicals and its detoxification. Supplementation of antioxidants in human and animal models has proven benefit in decreasing distant organ failure suggesting a cause and effect relationship. We conclude that oxidative damage is one of the mechanisms responsible for the local and distant pathophysiological events observed after burn, and therefore anti-oxidant therapy might be beneficial in minimizing injury in burned patients.

  10. Draft genome sequence of the extremely acidophilic biomining bacterium Acidithiobacillus thiooxidans ATCC 19377 provides insights into the evolution of the Acidithiobacillus genus.

    Science.gov (United States)

    Valdes, Jorge; Ossandon, Francisco; Quatrini, Raquel; Dopson, Mark; Holmes, David S

    2011-12-01

    Acidithiobacillus thiooxidans is a mesophilic, extremely acidophilic, chemolithoautotrophic gammaproteobacterium that derives energy from the oxidation of sulfur and inorganic sulfur compounds. Here we present the draft genome sequence of A. thiooxidans ATCC 19377, which has allowed the identification of genes for survival and colonization of extremely acidic environments.

  11. Draft Genome Sequence of the Extremely Acidophilic Biomining Bacterium Acidithiobacillus thiooxidans ATCC 19377 Provides Insights into the Evolution of the Acidithiobacillus Genus

    OpenAIRE

    Valdes, Jorge; Ossandon, Francisco; Quatrini, Raquel; Dopson, Mark; Holmes, David S

    2011-01-01

    Acidithiobacillus thiooxidans is a mesophilic, extremely acidophilic, chemolithoautotrophic gammaproteobacterium that derives energy from the oxidation of sulfur and inorganic sulfur compounds. Here we present the draft genome sequence of A. thiooxidans ATCC 19377, which has allowed the identification of genes for survival and colonization of extremely acidic environments.

  12. Graphene-supported metal oxide monolith

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

    2017-01-10

    A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

  13. A Study of Adherent Oxide Formation

    Science.gov (United States)

    1983-10-01

    improve oxide scale adherence to NiCrAl were investigated. Laser-processed materials were isothermally and cyclically oxidized and oxide scale...modified NiCrAl altered the morphology of the alumina scale and promoted the formation of a thinner, dense protective layer. • Thin aluminum oxide films...6 A. Materials. ........................... 6 B. Oxidation Studies. ....................... 7 1. NiCrAl .. .......................... 7a2

  14. Mesoporous metal oxide graphene nanocomposite materials

    Science.gov (United States)

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  15. Opportunities for functional oxides in yttrium oxide-titanium oxide-zirconium oxide system: Applications for novel thermal barrier coatings

    Science.gov (United States)

    Francillon, Wesley

    This dissertation is an investigation of materials and processed under consideration for next generation thermal structural oxides with potential applications as thermal barrier coatings; wherein, high temperature stability and mechanical properties affect durability. Two notable next generation materials systems under investigation are pyrochlore and co-doped zirconia oxides. The motivation for this work is based on current limitations of the currently used thermal barrier material of yttria stabilized zirconia (YSZ) deposited by the plasma spray processes. The rapid quenching associated with the plasma spray process, results in a metastable structure that is a non-transformable tetragonal structure in the yttria partially stabilized zirconia system rather than the equilibrium anticipated two phase mixture of cubic and monoclinic phases. It has been shown that this metastable structure offers enhanced toughness and thus durability during thermomechanical cycling from the operating temperatures in excess of 1000C to ambient. However, the metastable oxides are susceptible to partitioning at temperatures greater than 1200C, thus resulting in a transformation of the tetragonal phase oxides. Transformations of the tetragonal prime phase into the parent cubic and tetragonal prime phase result in coating degradation. Several of the emerging oxides are based on rare earth additions to zirconia. However, there is limited information of the high temperature stability of these oxide coatings and more notably these compositions exhibit limited toughness for durable performance. A potential ternary composition based on the YSZ system that offers the ability to tailor the phase structure is based YO1.5-TiO2 -ZrO2. The ternary of YO1.5-TiO2-ZrO 2 has the current TBC composition of seven molar percent yttria stabilized zirconia, pyrochlore phase oxide and zirconia doped with yttria and titania additions (Ti-YSZ). The Ti-YSZ phase field is of interest because at equilibrium it is

  16. Oxidation of Octopus vulgaris hemocyanin by nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    Salvato, B.; Giacometti, G.M.; Beltramini, M.; Zilio, F.; Giacometti, G.; Magliozzo, R.S.; Peisach, J.

    1989-01-24

    The reaction of Octopus vulgaris hemocyanin with nitrite was studied under a variety of conditions in which the green half-met derivative is formed. Analytical evidence shows that the amount of chemically detectable nitrite in various samples of the derivative is not proportional to the cupric copper detected by EPR. The kinetics of oxidation of hemocyanin as a function of protein concentration and pH, in the presence of nitrite and ascorbate, is consistent with a scheme in which NO/sub 2/ is the reactive oxidant. We suggest that the green half-methemocyanin contains a metal center with one cuprous and one cupric copper without an exogenous nitrogen oxide ligand.

  17. Destruction of methyl bromide sorbed to activated carbon by thiosulfate and electrolysis

    Science.gov (United States)

    Methyl bromide is widely used as a fumigant for post-harvest and quarantine uses at port facilities due to the low treatment times required, but it is vented to the atmosphere after its use. Due to the potential contributions of methyl bromide to stratospheric ozone depletion, technologies for the c...

  18. Heterogeneous Partial (ammOxidation and Oxidative Dehydrogenation Catalysis on Mixed Metal Oxides

    Directory of Open Access Journals (Sweden)

    Jacques C. Védrine

    2016-01-01

    Full Text Available This paper presents an overview of heterogeneous partial (ammoxidation and oxidative dehydrogenation (ODH of hydrocarbons. The review has been voluntarily restricted to metal oxide-type catalysts, as the partial oxidation field is very broad and the number of catalysts is quite high. The main factors of solid catalysts for such reactions, designated by Grasselli as the “seven pillars”, and playing a determining role in catalytic properties, are considered to be, namely: isolation of active sites (known to be composed of ensembles of atoms, Me–O bond strength, crystalline structure, redox features, phase cooperation, multi-functionality and the nature of the surface oxygen species. Other important features and physical and chemical properties of solid catalysts, more or less related to the seven pillars, are also emphasized, including reaction sensitivity to metal oxide structure, epitaxial contact between an active phase and a second phase or its support, synergy effect between several phases, acid-base aspects, electron transfer ability, catalyst preparation and activation and reaction atmospheres, etc. Some examples are presented to illustrate the importance of these key factors. They include light alkanes (C1–C4 oxidation, ethane oxidation to ethylene and acetic acid on MoVTe(SbNb-O and Nb doped NiO, propene oxidation to acrolein on BiMoCoFe-O systems, propane (ammoxidation to (acrylonitrile acrylic acid on MoVTe(SbNb-O mixed oxides, butane oxidation to maleic anhydride on VPO: (VO2P2O7-based catalyst, and isobutyric acid ODH to methacrylic acid on Fe hydroxyl phosphates. It is shown that active sites are composed of ensembles of atoms whose size and chemical composition depend on the reactants to be transformed (their chemical and size features and the reaction mechanism, often of Mars and van Krevelen type. An important aspect is the fact that surface composition and surface crystalline structure vary with reaction on stream until

  19. Nanoelectronics in oxides and semiconductors

    Science.gov (United States)

    Cheng, Guanglei

    The success of silicon industry lies on three major properties of silicon, an easily formed oxide layer to allow field effect operation, tunability of carrier density and high device scalability. All these features exist in oxides, together with some novel properties such as ferroelectricity, magnetic effects and metal-insulator transition. With the recent development in material growth method including molecular beam epitaxy (MBE), pulsed laser deposition (PLD) and reflection high energy electron diffraction (REED), atomically engineered oxide interfaces become available, thus opening the door to the novel oxide nanoelectronics. In this dissertation we create and study nanoelectronics in oxides, semiconductors and hybrid of these two. We used a conductive atomic force microscope tip to write single electron transistors in the 3-unit-cell-LaAlO 3/SrTiO3 heterostructure and observed ferroelectric tunneling behaviors. We also fabricated ferroelectric field transistors directly on silicon using strained SrTiO3 ferroelectric film and further confirmed the ferroelectric properties of this device. Meanwhile, we developed an ultrasensitive microwave capacitance sensor to study the electronic properties of self-assembled quantum dots and the switching mechanism of memristive devices. The integration of this sensor to a home made atomic force microscope provides an important tool to study the dielectric properties at nanoscale.

  20. Oxidation of low cobalt alloys

    Science.gov (United States)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  1. Integrating functional oxides with graphene

    Science.gov (United States)

    Hong, X.; Zou, K.; DaSilva, A. M.; Ahn, C. H.; Zhu, J.

    2012-08-01

    Graphene-oxide hybrid structures offer the opportunity to combine the versatile functionalities of oxides with the excellent electronic transport in graphene. Understanding and controlling how the dielectric environment affects the intrinsic properties of graphene is also critical to fundamental studies and technological development of graphene. Here we review our recent effort on understanding the transport properties of graphene interfaced with ferroelectric Pb(Zr,Ti)O3 (PZT) and high-κ HfO2. Graphene field effect devices prepared on high-quality single crystal PZT substrates exhibit up to tenfold increases in mobility compared to SiO2-gated devices. An unusual and robust resistance hysteresis is observed in these samples, which is attributed to the complex surface chemistry of the ferroelectric. Surface polar optical phonons of oxides in graphene transistors play an important role in the device performance. We review their effects on mobility and the high source-drain bias saturation current of graphene, which are crucial for developing graphene-based room temperature high-speed amplifiers. Oxides also introduce scattering sources that limit the low temperature electron mobility in graphene. We present a comprehensive study of the transport and quantum scattering times to differentiate various scattering scenarios and quantitatively evaluate the density and distribution of charged impurities and the effect of dielectric screening. Our results can facilitate the design of multifunctional nano-devices utilizing graphene-oxide hybrid structures.

  2. Oxide fiber targets at ISOLDE

    Energy Technology Data Exchange (ETDEWEB)

    Koester, U. E-mail: ulli.koster@cern.ch; Bergmann, U.C.; Carminati, D.; Catherall, R.; Cederkaell, J.; Correia, J.G.; Crepieux, B.; Dietrich, M.; Elder, K.; Fedoseyev, V.N.; Fraile, L.; Franchoo, S.; Fynbo, H.; Georg, U.; Giles, T.; Joinet, A.; Jonsson, O.C.; Kirchner, R.; Lau, Ch.; Lettry, J.; Maier, H.J.; Mishin, V.I.; Oinonen, M.; Peraejaervi, K.; Ravn, H.L.; Rinaldi, T.; Santana-Leitner, M.; Wahl, U.; Weissman, L

    2003-05-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce very intense {sup 6}He beams (order of 10{sup 13} ions per second) via the {sup 9}Be(n,{alpha}) reaction using spallation neutrons.

  3. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  4. Absorption and oxidation of nitrogen oxide in ionic liquids

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Thomassen, Peter Langelund; Riisager, Anders;

    2016-01-01

    A new strategy for capturing nitrogen oxide, NO, from the gas phase is presented. Dilute NO gas is removed from the gas phase by ionic liquids under ambient conditions. The nitrate anion of the ionic liquid catalyzes the oxidation of NO to nitric acid by atmospheric oxygen in the presence of water...... investigations of the reaction and products are presented. The procedure reveals a new vision for removing the pollutant NO by absorption into a non-volatile liquid and converting it into a useful bulk chemical, that is, HNO3....

  5. Atomistic stimulation of defective oxides

    CERN Document Server

    Minervini, L

    2000-01-01

    defect processes. The predominant intrinsic disorder reaction and the mechanism by which excess oxygen is accommodated are established. Furthermore, the most favourable migration mechanism and pathway for oxygen ions is predicted. Chapters 7 and 8 investigate pyrochlore oxides. These materials are candidates for solid oxide fuel cell components and as actinide host phases. Such applications require a detailed understanding of the defect processes. The defect energies, displayed as contour maps, are able to account for structure stability and, given an appropriate partial charge potential model, to accurately determine the oxygen positional parameter. In particular, the dependence of the positional parameter on intrinsic disorder is predicted. It is demonstrated, by radiation damage experiments, that these results are able to predict the radiation performance of pyrochlore oxides. Atomistic simulation calculations based on energy minimization techniques and classical pair potentials are used to study several i...

  6. Magnetic disorder in cupric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, S.J.; Borzi, R.A.; Mercader, R.C. [Universidad Nacional de La Plata, C.C. 67, Departamento de Fisica, Facultad de Ciencias Exactas (Argentina)

    1999-11-15

    Investigations of the abnormal magnetic properties of cupric oxide reveal discrepancies between both experimental results and theoretical explanations. Through iron-doping cupric oxide by ball-milling and thermal treatments we have been able to obtain Moessbauer results that are an experimental evidence of semi-disorder. The magnetic hyperfine field of the Cu{sub 0.995}Fe{sub 0.005}O solid solution displays a spin-glass-like thermal dependence that undergoes two transitions, one at about 150 K, that can be assigned to the long-range ordering of the cupric oxide spins, and the second one at some temperature between 4.2 and 15 K, that exposes either the freezing of the Fe{sup 3+} spins into a local canted state or of magnetic clusters in the CuO matrix.

  7. Resveratrol and Endothelial Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Ning Xia

    2014-10-01

    Full Text Available Nitric oxide (NO derived from the endothelial NO synthase (eNOS has antihypertensive, antithrombotic, anti-atherosclerotic and antiobesogenic properties. Resveratrol is a polyphenol phytoalexin with multiple cardiovascular and metabolic effects. Part of the beneficial effects of resveratrol are mediated by eNOS. Resveratrol stimulates NO production from eNOS by a number of mechanisms, including upregulation of eNOS expression, stimulation of eNOS enzymatic activity and reversal of eNOS uncoupling. In addition, by reducing oxidative stress, resveratrol prevents oxidative NO inactivation by superoxide thereby enhancing NO bioavailability. Molecular pathways underlying these effects of resveratrol involve SIRT1, AMPK, Nrf2 and estrogen receptors.

  8. Atmospheric oxidation of selected hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Benter, T.; Olariu, R.I.

    2002-02-01

    This work presents investigations on the gas-phase chemistry of phenol and the cresol isomers performed in a 1080 l quartz glass reactor in Wuppertal and in a large-volume outdoor photoreactor EUPHORE in Valencia, Spain. The studies aimed at clarifying the oxidation mechanisms of the reactions of these compounds with OH and NO{sub 3} radicals. Product investigations on the oxidation of phenol and the cresol isomers initiated by OH radicals were performed in the 1080 l quartz glass reactor with analyses by in situ FT-IR absorption spectroscopy. The primary focus of the investigations was on the determination of product yields. This work represents the first determination and quantification of 1,2-dihydroxybenzenes in the OH oxidation of phenolic compounds. Possible reaction pathways leading to the observed products have been elucidated. (orig.)

  9. CELLULOSE DEGRADATION BY OXIDATIVE ENZYMES

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  10. Oxide Fiber Targets at ISOLDE

    CERN Document Server

    Köster, U; Carminati, D; Catherall, R; Cederkäll, J; Correia, J G; Crepieux, B; Dietrich, M; Elder, K; Fedosseev, V; Fraile-Prieto, L M; Franchoo, S; Fynbo, H O U; Georg, U; Giles, T; Joinet, A; Jonsson, O C; Kirchner, R; Lau, C; Lettry, Jacques; Maier, H J; Mishin, V I; Oinonen, M; Peräjärvi, K; Ravn, H L; Rinaldi, T; Santana-Leitner, M; Wahl, U; Weissman, L

    2003-01-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxyde fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxyde fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce...

  11. Bismuth(V) oxide and silver bismuthate as oxidizing agents for gas-chromatographic elemental microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Shvykin, A.Y.; Platonov, V.V.; Proskuryakov, V.P.; Chilachava, K.B.; Khmarin, E.M.; Kovtun, I.V. [Tolstoy State Pedag University, Tula (Russian Federation)

    2004-07-01

    Bismuth(V) oxide, silver bismuthate, and a mixture of bismuth(V) oxide with fine silver powder were studied as oxidizing additives in gas-chromatographic elemental microanalysis of readily combustible organic substances and coal.

  12. Gas sensitivity of indium oxide

    Institute of Scientific and Technical Information of China (English)

    HUANG Shi-zhen; LIN Wei; CHEN Wen-zhe

    2009-01-01

    The yellow indium oxide nanoparticles were prepared by sintering the white deposition at 500 ℃. The crystalline indium chloride and ammonia were used as the starting material. The results show that, by analyzing the particles through X-ray diffraction and TEM, the particles are very small, spherical, and the particle size is about 40 nm. The direct-heat components made from indium oxide in Cl2 and NO2 was tested respectively, the component is far more sensitive to NO2 than to Cl2 at low heating temperature, and the status is reversed at high heating temperature.

  13. Superconducting interfaces between insulating oxides.

    Science.gov (United States)

    Reyren, N; Thiel, S; Caviglia, A D; Kourkoutis, L Fitting; Hammerl, G; Richter, C; Schneider, C W; Kopp, T; Rüetschi, A-S; Jaccard, D; Gabay, M; Muller, D A; Triscone, J-M; Mannhart, J

    2007-08-31

    At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3. The behavior of the electron gas is that of a two-dimensional superconductor, confined to a thin sheet at the interface. The superconducting transition temperature of congruent with 200 millikelvin provides a strict upper limit to the thickness of the superconducting layer of congruent with 10 nanometers.

  14. Study of Adherent Oxide Scales

    Science.gov (United States)

    1987-09-14

    The bond between alumina and NiCrAl substrate is intrinsically strong. The segregation of sulfur to the interface reduces bond strength, sulfur is...which laser-processing and minor element additions improve oxide scale adherence of a NiCrAl turbine coating composition. However, it was shown at the...adherence. However, significant observations were made with respect to the morphology of the oxide scale that forms on NiCrAl and NiCrAlY and these are

  15. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  16. Zinc oxide doped graphene oxide films for gas sensing applications

    Science.gov (United States)

    Chetna, Kumar, Shani; Garg, A.; Chowdhuri, A.; Dhingra, V.; Chaudhary, S.; Kapoor, A.

    2016-05-01

    Graphene Oxide (GO) is analogous to graphene, but presence of many functional groups makes its physical and chemical properties essentially different from those of graphene. GO is found to be a promising material for low cost fabrication of highly versatile and environment friendly gas sensors. Selectivity, reversibility and sensitivity of GO based gas sensor have been improved by hybridization with Zinc Oxide nanoparticles. The device is fabricated by spin coating of deionized water dispersed GO flakes (synthesized using traditional hummer's method) doped with Zinc Oxide on standard glass substrate. Since GO is an insulator and functional groups on GO nanosheets play vital role in adsorbing gas molecules, it is being used as an adsorber. Additionally, on being exposed to certain gases the electric and optical characteristics of GO material exhibit an alteration in behavior. For the conductivity, we use Zinc Oxide, as it displays a high sensitivity towards conduction. The effects of the compositions, structural defects and morphologies of graphene based sensing layers and the configurations of sensing devices on the performances of gas sensors were investigated by Raman Spectroscopy, X-ray diffraction(XRD) and Keithley Sourcemeter.

  17. Graphene oxide and H2 production from bioelectrochemical graphite oxidation.

    Science.gov (United States)

    Lu, Lu; Zeng, Cuiping; Wang, Luda; Yin, Xiaobo; Jin, Song; Lu, Anhuai; Jason Ren, Zhiyong

    2015-11-17

    Graphene oxide (GO) is an emerging material for energy and environmental applications, but it has been primarily produced using chemical processes involving high energy consumption and hazardous chemicals. In this study, we reported a new bioelectrochemical method to produce GO from graphite under ambient conditions without chemical amendments, value-added organic compounds and high rate H2 were also produced. Compared with abiotic electrochemical electrolysis control, the microbial assisted graphite oxidation produced high rate of graphite oxide and graphene oxide (BEGO) sheets, CO2, and current at lower applied voltage. The resultant electrons are transferred to a biocathode, where H2 and organic compounds are produced by microbial reduction of protons and CO2, respectively, a process known as microbial electrosynthesis (MES). Pseudomonas is the dominant population on the anode, while abundant anaerobic solvent-producing bacteria Clostridium carboxidivorans is likely responsible for electrosynthesis on the cathode. Oxygen production through water electrolysis was not detected on the anode due to the presence of facultative and aerobic bacteria as O2 sinkers. This new method provides a sustainable route for producing graphene materials and renewable H2 at low cost, and it may stimulate a new area of research in MES.

  18. Facile Access to Graphene Oxide from Ferro-Induced Oxidation

    Science.gov (United States)

    Yu, Chao; Wang, Cai-Feng; Chen, Su

    2016-01-01

    Methods allowing the oxidation of graphite to graphene oxide (GO) are vital important for the production of graphene from GO. This oxidation reaction has mainly relied on strong acid strategy for 174 years, which circumvents issues associated with toxicity of reagent and product, complex post-treatment, high cost and waste generation. Here, we report a green route for performing this oxidization reaction via a ferro-induced strategy, with use of water, potassium ferrate (Fe(VI)) and hydrogen peroxide (H2O2) as reagents, to produce about 65% yield of GO (vs. 40% for Hummers’ method, the most commonly used concentrated acid strategy) and non-toxic by-products. Moreover, GO produced from this new method shows equivalent performance to those reported previously. This H2SO4-free strategy makes it possible to process graphite into GO in a safe, low-cost, time-saving, energy-efficient and eco-friendly pathway, opening a promising avenue for the large-scale production of GO and GO-based materials.

  19. Oxidative stress inhibition and oxidant activity by fibrous clays.

    Science.gov (United States)

    Cervini-Silva, Javiera; Nieto-Camacho, Antonio; Gómez-Vidales, Virginia

    2015-09-01

    Fibrous clays (sepiolite, palygorskite) are produced at 1.2m tonnes per year and have a wide range of industrial applications needing to replace long-fibre length asbestos. However, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the effect of sepiolite (Vallecas, Spain) and palygorskite (Torrejón El Rubio, Spain) on cell damage via oxidative stress (determined as the progress of lipid peroxidation, LP). The extent of LP was assessed using the Thiobarbituric Acid Reactive Substances assay. The oxidant activity by fibrous clays was quantified using Electron-Paramagnetic Resonance. Sepiolite and palygorskite inhibited LP, whereby corresponding IC50 values were 6557±1024 and 4250±289μgmL(-1). As evidenced by dose-response experiments LP inhibition by palygorskite was surface-controlled. Fibrous clay surfaces did not stabilize HO species, except for suspensions containing 5000μgmL(-1). A strong oxidant (or weak anti-oxidant) activity favours the inhibition of LP by fibrous clays.

  20. Oxidation mechanisms for alloys in single-oxidant gases

    Energy Technology Data Exchange (ETDEWEB)

    Whittle, D.P.

    1981-03-01

    Scales formed on alloys invariably contain the alloy constituents in a ratio different from that in the alloy, owing to the differing thermodynamic tendencies of the alloy components to react with the oxidant and to differences in diffusion rates in scale and alloy phases. This complex interrelationship between transport rates and the thermodynamics of the alloy-oxidant system can be analyzed using multicomponent diffusion theory when transport-controlled growth of single or multi-layered scales occurs. In particular, the superimposition of the diffusion data on an isothermal section of the appropriate phase diagram indicates the likely morphologies of the reaction products, including the sequence of phases found in the scale, the occurrence of internal oxidation and the development of an irregular metal/scale interface. The scale morphologies on alloys are also time-dependent: there is an initial transient stage, a steady state period, and a final breakdown, the latter often related to mechanical influences such as scale adherence, spallation, thermal or mechanical stresses and void formation. Mechanical influences have a more devastating effect in alloy oxidation due to the changes in alloy surface composition during the steady state period.

  1. Oxidative removal of aqueous steroid estrogens by manganese oxides.

    Science.gov (United States)

    Xu, Lei; Xu, Chao; Zhao, Meirong; Qiu, Yuping; Sheng, G Daniel

    2008-12-01

    This study investigated the oxidative removal of steroid estrogens from water by synthetic manganese oxide (MnO2) and the factors influencing the reactions. Using 1 x 10(-5)M MnO2 at pH 4, estrone (E1), 17beta-estradiol (E2), estriol (E3) and 17alpha-ethinylestradiol (EE2), all at 4 x 10(-6)M, were rapidly removed within 220 min, indicating the effectiveness of MnO2 as an oxidizing agent towards estrogens. E2 removal increased with decreasing pH over the tested range of 4-8, due most likely to increased oxidizing power of MnO2 and a cleaner reactive surface in acidic solutions. Coexisting metal ions of 0.01 M (Cu(II), Zn(II), Fe(III) and Mn(II)) and Mn(II) released from MnO2 reduction competed with E2 for reactive sites leading to reduced E2 removal. Observed differential suppression on E2 removal may be related to different speciations of metals, as suggested by the MINTEQ calculations, and hence their different adsorptivities on MnO2. By suppressing the metal effect, humic acid substantially enhanced E2 removal. This was attributed to complexation of humic acid with metal ions. With 0.01 M ZnCl2 in solutions containing 1 mg l(-1) humic acid, the binding of humic acid for Zn(II) was determined at 251 mmol g(-1). An in vitro assay using human breast carcinoma MCF-7 cells indicated a near elimination of estrogenic activities without secondary risk of estrogen solutions treated with MnO2. Synthetic MnO2 is therefore a promising chemical agent under optimized conditions for estrogen removal from water. Metal chelators recalcitrant to MnO2 oxidation may be properly used to further enhance the MnO2 performance.

  2. [Solidification of volatile oil with graphene oxide].

    Science.gov (United States)

    Yan, Hong-Mei; Jia, Xiao-Bin; Zhang, Zhen-Hai; Sun, E; Xu, Yi-Hao

    2015-02-01

    To evaluate the properties of solidifying volatile oil with graphene oxide, clove oil and zedoary turmeric oil were solidified by graphene oxide. The amount of graphene oxide was optimized with the eugenol yield and curcumol yield as criteria. Curing powder was characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The effects of graphene oxide on dissolution in vitro and thermal stability of active components were studied. The optimum solidification ratio of graphene oxide to volatile oil was 1:1. Dissolution rate of active components had rare influence while their thermal stability improved after volatile oil was solidified. Solidifying herbal volatile oil with graphene oxide deserves further study.

  3. Thermal Oxidation of Structured Silicon Dioxide

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Hansen, Ole; Jensen, Jørgen Arendt

    2014-01-01

    The topography of thermally oxidized, structured silicon dioxide is investigated through simulations, atomic force microscopy, and a proposed analytical model. A 357 nm thick oxide is structured by removing regions of the oxide in a masked etch with either reactive ion etching or hydrofluoric acid....... Subsequent thermal oxidation is performed in both dry and wet ambients in the temperature range 950◦C to 1100◦C growing a 205 ± 12 nm thick oxide in the etched mask windows. Lifting of the original oxide near the edge of the mask in the range 6 nm to 37 nm is seen with increased lifting for increasing...

  4. Oxidative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Gurunathan S

    2012-11-01

    Full Text Available Sangiliyandi Gurunathan, Jae Woong Han, Ahmed Abdal Dayem, Vasuki Eppakayala, Jin-Hoi KimDepartment of Animal Biotechnology, Konkuk University, Seoul, South KoreaBackground: Graphene holds great promise for potential use in next-generation electronic and photonic devices due to its unique high carrier mobility, good optical transparency, large surface area, and biocompatibility. The aim of this study was to investigate the antibacterial effects of graphene oxide (GO and reduced graphene oxide (rGO in Pseudomonas aeruginosa. In this work, we used a novel reducing agent, betamercaptoethanol (BME, for synthesis of graphene to avoid the use of toxic materials. To uncover the impacts of GO and rGO on human health, the antibacterial activity of two types of graphene-based material toward a bacterial model P. aeruginosa was studied and compared.Methods: The synthesized GO and rGO was characterized by ultraviolet-visible absorption spectroscopy, particle-size analyzer, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Further, to explain the antimicrobial activity of graphene oxide and reduced graphene oxide, we employed various assays, such as cell growth, cell viability, reactive oxygen species generation, and DNA fragmentation.Results: Ultraviolet-visible spectra of the samples confirmed the transition of GO into graphene. Dynamic light-scattering analyses showed the average size among the two types of graphene materials. X-ray diffraction data validated the structure of graphene sheets, and high-resolution scanning electron microscopy was employed to investigate the morphologies of prepared graphene. Raman spectroscopy data indicated the removal of oxygen-containing functional groups from the surface of GO and the formation of graphene. The exposure of cells to GO and rGO induced the production of superoxide radical anion and loss of cell viability. Results suggest that the antibacterial activities are contributed to by loss of

  5. Oxidation Mechanism of Copper Selenide

    Science.gov (United States)

    Taskinen, Pekka; Patana, Sonja; Kobylin, Petri; Latostenmaa, Petri

    2014-09-01

    The oxidation mechanism of copper selenide was investigated at deselenization temperatures of copper refining anode slimes. The isothermal roasting of synthetic, massive copper selenide in flowing oxygen and oxygen - 20% sulfur dioxide mixtures at 450-550 °C indicate that in both atmospheres the mass of Cu2Se increases as a function of time, due to formation of copper selenite as an intermediate product. Copper selenide oxidises to copper oxides without formation of thick copper selenite scales, and a significant fraction of selenium is vaporized as SeO2(g). The oxidation product scales on Cu2Se are porous which allows transport of atmospheric oxygen to the reaction zone and selenium dioxide vapor to the surrounding gas. Predominance area diagrams of the copper-selenium system, constructed for selenium roasting conditions, indicate that the stable phase of copper in a selenium roaster gas with SO2 is the sulfate CuSO4. The cuprous oxide formed in decomposition of Cu2Se is further sulfated to CuSO4.

  6. Oxidative Stress and Neurodegenerative Disorders

    Directory of Open Access Journals (Sweden)

    Jie Li

    2013-12-01

    Full Text Available Living cells continually generate reactive oxygen species (ROS through the respiratory chain during energetic metabolism. ROS at low or moderate concentration can play important physiological roles. However, an excessive amount of ROS under oxidative stress would be extremely deleterious. The central nervous system (CNS is particularly vulnerable to oxidative stress due to its high oxygen consumption, weakly antioxidative systems and the terminal-differentiation characteristic of neurons. Thus, oxidative stress elicits various neurodegenerative diseases. In addition, chemotherapy could result in severe side effects on the CNS and peripheral nervous system (PNS of cancer patients, and a growing body of evidence demonstrates the involvement of ROS in drug-induced neurotoxicities as well. Therefore, development of antioxidants as neuroprotective drugs is a potentially beneficial strategy for clinical therapy. In this review, we summarize the source, balance maintenance and physiologic functions of ROS, oxidative stress and its toxic mechanisms underlying a number of neurodegenerative diseases, and the possible involvement of ROS in chemotherapy-induced toxicity to the CNS and PNS. We ultimately assess the value for antioxidants as neuroprotective drugs and provide our comments on the unmet needs.

  7. Riboflavin photosensitized oxidation of myoglobin.

    Science.gov (United States)

    Grippa, Juliana M; de Zawadzki, Andressa; Grossi, Alberto B; Skibsted, Leif H; Cardoso, Daniel R

    2014-02-05

    The reaction of the fresh meat pigment oxymyoglobin, MbFe(II)O₂, and its oxidized form metmyoglobin, MbFe(III), with triplet-state riboflavin involves the pigment protein, which is oxidatively cleaved or dimerized as shown by SDS-PAGE and Western blotting. The overall rate constant for oxidation of MbFe(II)O₂ by ³Rib is (3.0 ± 0.5) × 10⁹ L·mol⁻¹·s⁻¹ and (3.1 ± 0.4) × 10⁹ L·mol⁻¹·s⁻¹ for MbFe(III) in phosphate buffer of pH 7.4 at 25 °C as determined by laser flash photolysis. The high rates are rationalized by ground state hydrophobic interactions as detected as static quenching of fluorescence from singlet-excited state riboflavin by myoglobins using time-resolved fluorescence spectroscopy and a Stern-Volmer approach. Binding of riboflavin to MbFe(III) has K(a) = (1.2 ± 0.2) × 10⁴ mol·L⁻¹ with ΔH° = -112 ± 22 kJ·mol⁻¹ and ΔS° = -296 ± 75 J·mol⁻¹·K⁻¹. For meat, riboflavin is concluded to be a photosensitizer for protein oxidation but not for discoloration.

  8. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

    Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

  9. Durability of Solid Oxide Cells

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Hauch, Anne; Hjelm, Johan

    2011-01-01

    In recent years extended focus has been placed on monitoring and understanding degradation mechanisms in both solid oxide fuel cells and solid oxide electrolysis cells. The time-consuming nature of degradation experiments and the disparate conclusions from experiment reproductions indicates that ...... behaviour and mechanisms are discussed. For ease of navigation, the review is separated into the various cell components – fuel electrode, electrolyte and oxygen electrode. Finally, nano-particle impregnate stability is discussed.......In recent years extended focus has been placed on monitoring and understanding degradation mechanisms in both solid oxide fuel cells and solid oxide electrolysis cells. The time-consuming nature of degradation experiments and the disparate conclusions from experiment reproductions indicates...... that not all degradation mechanisms are fully understood. Traditionally, cell degradation has been attributed to the materials, processing and cell operating conditions. More recently, focus has been placed on the effect of raw material and gas impurities and their long-term effect on cell degradation. Minor...

  10. Method of oxidizing an alcohol

    NARCIS (Netherlands)

    Dijksman, A.; Arends, I.W.C.E.; Sheldon, R.A.

    2000-01-01

    The invention relates to a method of oxidizing an alcohol to form an aldehyde or ketone using a ruthenium ion and oxygen in the presence of a substantially stable N-O free radical compound, wherein two atoms bound to the nitrogen atom are not themselves hydrogen carriers. It has been found that with

  11. Hemoglobin oxidative stress in cancer.

    Science.gov (United States)

    Della Rovere, F; Granata, A; Broccio, M; Zirilli, A; Broccio, G

    1995-01-01

    The role played by free radicals in carcinogenesis and their relationships with antioxidant pool and cancer have already been shown. Free radicals induce increased membrane permeability through membrane lipid peroxidation, protein oxidation and histamine release from mast cells. Free radicals also cause oxyhemoglobin oxidative stress which increases methemoglobin and hemichromes. For this reason, we studied the in vitro formation of methemoglobin at 0' and 90', dosed following the HPLC method, after oxidative stress of blood by means of acetylphenylhydrazine in 40 subjects with cancer and 40 healthy donors. The results showed that methemoglobin formation was highly significant in tumors as compared to controls (P < 0.0001). The statistical analyses we carried out showed that metHb formation is not affected by age, sex, smoking habit, red blood cell number, Hb, Ht or tumor staging. This makes us believe that free radicals alter erythrocyte membrane permeability and predenaturate oxyhemoglobin so that erythrocyte membrane becomes more susceptible to new oxidative stress. This caused the abnormal response we found. Our results clearly underline the role played by free radicals in tumorous disease and provide a successful and easy method to detect early, even in a pre-clinical stage, the presence of tumorous alterations in the human body.

  12. Ediacaran oxidation and biotic evolution.

    Science.gov (United States)

    Grey, Kathleen; Calver, Clive R

    2007-11-29

    The link between the radiation of various lineages of eukaryotes in the latest Proterozoic and massive environmental changes--oxygenation, global ice ages and bolide impact--is the focus of much research interest. Fike et al. use carbon and sulphur isotope-chemostratigraphic data from Oman to propose three stages of oxidation in the Ediacaran oceans, and link the second and third stages to eukaryote diversification. The second stage, signalled by strongly 13C-depleted sedimentary carbonates (the 'Shuram excursion'), is believed to result from oxidation of a large, deep-ocean reservoir of organic carbon. Fike et al. use our data to assert that a correlative carbon isotope excursion in Australia coincided with the initial diversification of acanthomorphic acritarchs. Peak diversity is claimed to have coincided with subsequent deposition of 13C-enriched carbonate and the third oxidation stage. However, the authors seem to have misinterpreted our data, which instead indicate that diversification significantly preceded the Shuram excursion; this weakens their argument for a link between the inferred oxidation events and eukaryote evolution.

  13. Plasma electrolytic oxidation of metals

    Directory of Open Access Journals (Sweden)

    Stojadinović Stevan

    2013-01-01

    Full Text Available In this lecture results of the investigation of plasma electrolytic oxidation (PEO process on some metals (aluminum, titanium, tantalum, magnesium, and zirconium were presented. Whole process involves anodizing metals above the dielectric breakdown voltage where numerous micro-discharges are generated continuously over the coating surface. For the characterization of PEO process optical emission spectroscopy and real-time imaging were used. These investigations enabled the determination of electron temperature, electron number density, spatial density of micro-discharges, the active surface covered by micro-discharges, and dimensional distribution of micro-discharges at various stages of PEO process. Special attention was focused on the results of the study of the morphology, chemical, and phase composition of oxide layers obtained by PEO process on aluminum, tantalum, and titanium in electrolytes containing tungsten. Physicochemical methodes: atomic force microscopy (AFM, scanning electron microscopy (SEM-EDS, x-ray diffraction (XRD, x-ray photoelectron spectroscopy (XPS, and Raman spectroscopy served as tools for examining obtained oxide coatings. Also, the application of the obtained oxide coatings, especially the application of TiO2/WO3 coatings in photocatalysis, were discussed.

  14. Oxidation of pyrite: Consequences and significance

    Directory of Open Access Journals (Sweden)

    Dimitrijević Mile D.

    2002-01-01

    Full Text Available This paper presents the most important studies on the oxidation of pyrite particularly in aqueous solutions. The consequences of pyrite oxidation was examined, as well as its importance, from both the technical-technological and environmental points of view. The oxidation of pyrite was considered in two parts. The spontaneous oxidation of pyrite in nature was described in the first part, with this part comprising pyrite oxidation in deposits depots and mines. It is explained how way natural electrochemical processes lead to the decomposition of pyrite and other minerals associated with pyrite. The oxidation of pyrite occurring during technological processes such as grinding, flotation and leaching, was shown in the second part. Particular emphasis was placed on the oxidation of pyrite during leaching. This part includes the leaching of sulphide and oxide ores, the leaching of pyrite coal and the leaching of refractory gold-bearing ores (pressure oxidation, bacterial oxidation, oxidation by means of strong oxidants and the electrolysis of pyrite suspensions. Various mechanisms of pyrite oxidation and of the galvanic interaction of pyrite with other sulphide minerals are shown.

  15. Oxidation kinetics of aluminum diboride

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, Michael L., E-mail: michaelwhittaker2016@u.northwestern.edu [Department of Materials Science and Engineering, University of Utah, 122S. Central Campus Drive, Salt Lake City, UT 84112 (United States); Sohn, H.Y. [Department of Metallurgical Engineering, University of Utah, 135S 1460 E, Rm 00412, Salt Lake City, UT 84112 (United States); Cutler, Raymond A. [Ceramatec, Inc., 2425S. 900W., Salt Lake City, UT 84119 (United States)

    2013-11-15

    The oxidation characteristics of aluminum diboride (AlB{sub 2}) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB{sub 2} in the onset of oxidation and final conversion fraction, with AlB{sub 2} beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB{sub 2} and Al+2B in both air and oxygen. AlB{sub 2} exhibited O{sub 2}-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O{sub 2} than in air. Differences in the composition and morphology between oxidized Al+2B and AlB{sub 2} suggested that Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} interactions slowed Al+2B oxidation by converting Al{sub 2}O{sub 3} on aluminum particles into a Al{sub 4}B{sub 2}O{sub 9} shell, while the same Al{sub 4}B{sub 2}O{sub 9} developed a needle-like morphology in AlB{sub 2} that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB{sub 2}, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB{sub 2} in air, showing a constantly decreasing activation energy with increasing conversion. Model-free analysis allowed for the calculation of global kinetic parameters despite many simultaneous mechanisms occurring concurrently. (a) Time

  16. Inflammation, Oxidative Stress, and Obesity

    Directory of Open Access Journals (Sweden)

    José A. Morales-González

    2011-05-01

    Full Text Available Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer of certain bioactive substances called adipokines. Among adipokines, we find some inflammatory functions, such as Interleukin-6 (IL-6; other adipokines entail the functions of regulating food intake, therefore exerting a direct effect on weight control. This is the case of leptin, which acts on the limbic system by stimulating dopamine uptake, creating a feeling of fullness. However, these adipokines induce the production of reactive oxygen species (ROS, generating a process known as oxidative stress (OS. Because adipose tissue is the organ that secretes adipokines and these in turn generate ROS, adipose tissue is considered an independent factor for the generation of systemic OS. There are several mechanisms by which obesity produces OS. The first of these is the mitochondrial and peroxisomal oxidation of fatty acids, which can produce ROS in oxidation reactions, while another mechanism is over-consumption of oxygen, which generates free radicals in the mitochondrial respiratory chain that is found coupled with oxidative phosphorylation in mitochondria. Lipid-rich diets are also capable of generating ROS because they can alter oxygen metabolism. Upon the increase of adipose tissue, the activity of antioxidant enzymes such as superoxide dismutase (SOD, catalase (CAT, and glutathione peroxidase (GPx, was found to be significantly diminished. Finally, high ROS production and the decrease in antioxidant capacity leads to various abnormalities, among which we find endothelial dysfunction, which is characterized by a reduction in the bioavailability of vasodilators, particularly nitric oxide (NO, and an increase in endothelium-derived contractile factors, favoring atherosclerotic disease.

  17. Evolution of Oxidative Continental Weathering

    Science.gov (United States)

    Konhauser, Kurt; Lalonde, Stefan

    2014-05-01

    The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen levels increased above 10-5 times the present atmospheric level. This value is based on the loss of sulphur isotope mass independent fractionation (S-MIF) from the rock record, beginning at 2.45 Ga and disappearing by 2.32 Ga. However, a number of recent papers have pushed back the timing for oxidative continental weathering, and by extension, the onset of atmospheric oxygenation several hundreds of million years earlier despite the presence of S-MIF (e.g., Crowe et al., 2013). This apparent discrepancy can, in part, be resolved by the suggestion that recycling of older sedimentary sulphur bearing S-MIF might have led to this signal's persistence in the rock record for some time after atmospheric oxygenation (Reinhard et al., 2013). Here we suggest another possibility, that the earliest oxidative weathering reactions occurred in environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts, riverbed and estuarine sediments, and lacustrine microbial mats. We calculate that the rate of O2 production via oxygenic photosynthesis in these terrestrial microbial ecosystems provides largely sufficient oxidizing potential to mobilise sulphate and a number of redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. These findings reconcile geochemical signatures in the rock record for the earliest oxidative continental weathering with the history of atmospheric sulphur chemistry, and demonstrate the plausible antiquity of a terrestrial biosphere populated by cyanobacteria. Crowe, S.A., Dossing, L.N., Beukes, N.J., Bau, M., Kruger, S.J., Frei, R. & Canfield, D.E. Atmospheric oxygenation three billion years ago. Nature 501, 535-539 (2013). Reinhard, C.T., Planavsky, N.J. & Lyons, T.W. Long-term sedimentary recycling of rare sulphur isotope anomalies. Nature 497

  18. The properties of protective oxide scales containing cerium on alloy 800H in oxidizing and oxidizing/sulphidizing environments

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Fransen, T.; Geerdink, B.; Gellings, P.J.; Stroosnijder, M.F.

    1991-01-01

    The corrosion protection of oxide scales formed by electrophoretic deposition in a cerium-containing sol on Alloy 800H, a 32Ni-20Cr steel, followed by firing in air at 1123 K was studied in oxidizing and mixed oxidizing/sulphidizing environments at elevated temperatures. In particular, the influence

  19. Solid Oxide Fuel Cell Experimental Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s Solid Oxide Fuel Cell Experimental Laboratory in Morgantown, WV, gives researchers access to models and simulations that predict how solid oxide fuel cells...

  20. Electrochemical, Chemical and Enzymatic Oxidations of Phenothiazines

    NARCIS (Netherlands)

    Blankert, B.; Hayen, H.; Leeuwen, van S.M.; Karst, U.; Bodoki, E.; Lotrean, S.; Sandulescu, R.; Mora Diaz, N.; Dominguez, O.; Arcos, J.; Kauffmann, J.-M.

    2005-01-01

    The oxidation of several phenothiazine drugs (phenothiazine, promethazine hydrochloride, promazine hydrochloride, trimeprazine hydrochloride and ethopropazine hydrochloride) has been carried out in aqueous acidic media by electrochemical, chemical and enzymatic methods. The chemical oxidation was pe

  1. Complex oxides useful for thermoelectric energy conversion

    Science.gov (United States)

    Majumdar, Arunava [Orinda, CA; Ramesh, Ramamoorthy [Moraga, CA; Yu, Choongho [College Station, TX; Scullin, Matthew L [Berkeley, CA; Huijben, Mark [Enschede, NL

    2012-07-17

    The invention provides for a thermoelectric system comprising a substrate comprising a first complex oxide, wherein the substrate is optionally embedded with a second complex oxide. The thermoelectric system can be used for thermoelectric power generation or thermoelectric cooling.

  2. Methods for synthesizing metal oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  3. Summary of emissions associated with propylene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hume, G.

    1988-11-01

    This summary describes the industrial production and uses of propylene oxide, documents the methods of calculation used to estimate emissions, and lists the major facilities emitting propylene oxide, along with their estimated emissions.

  4. 46 CFR 153.1010 - Alkylene oxides.

    Science.gov (United States)

    2010-10-01

    ... alkylene oxides are onboard the vessel, the master shall make sure that the oxygen content of the vapor...% by volume. (d) Tankships with independent piping for alkylene oxides must have onboard: (1)...

  5. Cellulose nanocrystal reinforced oxidized natural rubber nanocomposites.

    Science.gov (United States)

    Mariano, Marcos; El Kissi, Nadia; Dufresne, Alain

    2016-02-10

    Natural rubber (NR) latex particles were oxidized using KMnO4 as oxidant to promote the insertion of hydroxyl groups in the surface polyisoprene chains. Different degrees of oxidation were investigated. Both unoxidized and oxidized NR (ONR) latex were used to prepare nanocomposite films reinforced with cellulose nanocrystals (CNCs) by casting/evaporation. The oxidation of NR was carried out to promote chemical interactions between the hydroxyl groups of ONR with those of CNCs through hydrogen bonding. The effect of the degree of oxidation of the NR latex on the rheological behavior of CNC/NR and CNC/ONR suspensions, as well as on the mechanical, swelling and thermal properties of ensuing nanocomposites was investigated. Improved properties were observed for intermediate degrees of oxidation but they were found to degrade for higher oxidation levels.

  6. Ellipsometric investigation of anodic zirconium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Patrito, E.M.; Macagno, V.A. (Univ. Nacional de Cordoba, Cordoba (Argentina). Dept. de Fisicoquimica)

    1993-06-01

    The anodic oxidation of zirconium was studied by in situ ellipsometry together with capacity measurements. The oxides were grown under potentiodynamic, galvanostatic, and potentiostatic conditions up to final potentials of 100 V in 0.5M H[sub 2]SO[sub 4] solution. The refractive index of the oxides changes depending on the growth current. The films were slightly absorbing but their absorption coefficient was independent of the oxide growth conditions. Different methods of surface preparation including etching in hydrofluoric acid-based mixtures, electropolishing and mechanical polishing were used. The surfaces and oxides were characterized by SEM examination and XPS measurements. The surface pretreatment affects both the substrate and the oxide optical constants as well as the rate of oxide growth. The density and dielectric constant of the oxides were calculated performing simultaneous ellipsometric, coulometric, and capacity measurements.

  7. "UCx fission targets oxidation test stand"

    CERN Document Server

    Lacroix, Rachel

    2014-01-01

    "Set up a rig dedicated to the oxidation of UCx and define a procedure for repeatable, reliable and safe method for converting UC2 fission targets into an acceptable uranium carbide oxide waste for subsequent disposal by the Swiss Authorities."

  8. Empirical Criteria of Superconductivity for Some Oxides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The properties of superconductivity of some oxides were investigated by structural parametricdiagrams or pattern recognition with structural chemical parameters. The essential criteria ofsuperconductivity for some oxides have been obtained by using 109 oxides as the training setand seven parameters as features; the results illustrated that the electronegativity difference isthe most important factor among seven parameters. Moreover, the regularity of superconductivetransition temperature Tc for complex oxides is discussed by partial least squares (PL5) method.

  9. Nanostructured Metal Oxides Based Enzymatic Electrochemical Biosensors

    OpenAIRE

    Ansari, Anees A.; Alhoshan, M.; M. S. AlSalhi; Aldwayyan, A.S.

    2010-01-01

    The unique electrocatalytic properties of the metal oxides and the ease of metal oxide nanostructured fabrication make them extremely interesting materials for electrochemical enzymatic biosensor applications. The application of nanostructured metal oxides in such sensing devices has taken off rapidly and will surely continue to expand. This article provides a review on current research status of electrochemical enzymatic biosensors based on various new types of nanostructured metal oxides su...

  10. Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation.

    Science.gov (United States)

    Herzberger, Jana; Niederer, Kerstin; Pohlit, Hannah; Seiwert, Jan; Worm, Matthias; Wurm, Frederik R; Frey, Holger

    2016-02-24

    The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone.

  11. The oxidation and surface speciation of indium and indium oxides exposed to atmospheric oxidants

    Science.gov (United States)

    Detweiler, Zachary M.; Wulfsberg, Steven M.; Frith, Matthew G.; Bocarsly, Andrew B.; Bernasek, Steven L.

    2016-06-01

    Metallic indium and its oxides are useful in electronics applications, in transparent conducting electrodes, as well as in electrocatalytic applications. In order to understand more fully the speciation of the indium and oxygen composition of the indium surface exposed to atmospheric oxidants, XPS, HREELS, and TPD were used to study the indium surface exposed to water, oxygen, and carbon dioxide. Clean In and authentic samples of In2O3 and In(OH)3 were examined with XPS to provide standard spectra. Indium was exposed to O2 and H2O, and the ratio of O2 - to OH- in the O1s XPS region was used to monitor oxidation and speciation of the surface. HREELS and TPD indicate that water dissociates on the indium surface even at low temperature, and that In2O3 forms at higher temperatures. Initially, OH- is the major species at the surface. Pure In2O3 is also OH- terminated following water exposure. Ambient pressure XPS studies of water exposure to these surfaces suggest that high water pressures tend to passivate the surface, inhibiting extensive oxide formation.

  12. Dissolution of Uranium Oxides Under Alkaline Oxidizing Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Steven C.; Peper, Shane M.; Douglas, Matthew; Ziegelgruber, Kate L.; Finn, Erin C.

    2009-11-01

    Bench scale experiments were conducted to determine the dissolution characteristics of uranium oxide powders (UO2, U3O8, and UO3) in aqueous peroxide-carbonate solutions. Experimental parameters included H2O2 concentration, carbonate counter cation (NH4+, Na+, K+, and Rb+), and pH. Results indicate the dissolution rate of UO2 in 1 M (NH4)2CO3 increases linearly with peroxide concentration ranging from 0.05 – 2 M. The three uranium oxide powders exhibited different dissolution patterns however, UO3 exhibited prompt complete dissolution. Carbonate counter cation affected the dissolution kinetics. There is minimal impact of solution pH, over the range 8.8 to 10.6, on initial dissolution rate.

  13. The initial oxidation of magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, M.

    2004-07-01

    Pure Magnesium samples have been oxidised in an UHV chamber under controlled conditions. Pressure range was 10{sup -10} Torr to 10{sup -7} Torr, temperature range was 273 K to 435 K. The samples have then been investigated with XPS, Ellipsometry and HERDA. Additionally, furnace oxidations at 750 Torr and 673 K have been carried out and investigated with XPS. From the XPS measurements data concerning layer thickness, composition, oxidation state and binding state have been gained. The ellipsometrie measurements yielded additional data concerning layer thickness as well as the size of the band gap of the developing oxide. With the HERDA measurements, the oxygen content within the oxide layer has been determined yielding additional information about composition and layer thickness. The layer thickness as a function of time have then been modelled with a kinetic growth model of Fromhold and Cook. For the refinement of the XPS data concerning layer thickness and composition, the pronounced plasmon excitations that occur in magnesium have been determined with two different procedures which have been developed in the methodical part of this work. The layer thickness and composition values have thus been corrected. Results: Two oxidation stages could be identified: a strong increase for the first few Langmuirs (1L = 1s x 10{sup -6} Torr), followed by a saturation'' region which was about 1.2 nm to 1.5 nm in magnitude. XPS and ellipsometry results have thereby been in very good agreement. The composition of the developing oxide showed a clear deviation from stoichiometric MgO, mainly caused by an oxygen deficiency; this deficiency has also been confirmed with the HERDA measurements. The Mg/O ratio as a function of layer thickness showed a continous decay starting from very high values for the thinnest layers (>{proportional_to}2.5) down to a saturation value of about 1.4, even for larger layer thicknesses gained with the furnace oxidations. The determination of

  14. Oxidation of phenolic acids by soil iron and manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, R.G.; Cheng, H.H.; Harsh, J.B.

    Phenolic acids are intermediary metabolites of many aromatic chemicals and may be involved in humus formation, allelopathy, and nutrient availability. Depending on their structures, six phenolic acids were shown to react at different rates with oxidized forms of Fe and Mn in a Palouse soil (fine-silty, mixed, mesic Pachic Ultic Haploxeroll). Increasing methoxy substitution on the aromatic ring of phenolic acids increased the reaction rate. Reaction rate was also increased for longer carboxyl-containing side chains. After 4 h reaction, little of the applied (10 mg kg/sup -1/ soil) p-hydroxybenzoic or p-coumaric acids had reacted, while 0 to 5, 70, 90, and 100% of the vanillic, ferulic, syringic, and sinapic acids, respectively, had reacted. After 72 h under conditions limiting microbial growth, none of the p-hydroxybenzoic, 30% of the p-coumaric, and 50% of the vanillic acids had reacted. The reaction was shown to be predominantly chemical, and not biological, since phenolic acid extractabilities were similar for Palouse soil and for Palouse soil pretreated with LiOBr to remove organic matter. When the Palouse soil was pretreated with a sodium dithionite-citrate solution to remove Fe and Mn oxides, none of the phenolic acids reacted after 1 h. The reaction of sinapic acid with Palouse soil was shown to produce Fe(II) and soluble Mn as reaction products. The reaction of phenolic acids with soil was thus shown to be an oxidation of the phenolic acids, coupled with a reduction of soil Fe and Mn oxides.

  15. Photopromoted and Thermal Decomposition of Nitric Oxide by Metal Oxides

    Science.gov (United States)

    1992-04-01

    Photocatalysis (U) n nMetal Oxides (U) NOx Removal (U) 9. ABSTRACT (Continue on reverse if necessary and identify by block number) This technical...for Photocatalysis and Photosynthesis: An Overview," in Energy Resources through Photochemistry and Catalysis, Graetzel, W., Ed., Academic Press, NY...1983, pp.217-260. 16. Courbon, H., and Pichat, P., "Room-temperature Interaction of N180 with Ultraviolet- illuminated TiO2 ," J. Chem. Soc., Faraday

  16. 21 CFR 582.5431 - Magnesium oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.5431 Section 582.5431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This...

  17. 21 CFR 184.1431 - Magnesium oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium oxide. 184.1431 Section 184.1431 Food and... Substances Affirmed as GRAS § 184.1431 Magnesium oxide. (a) Magnesium oxide (MgO, CAS Reg. No. 1309-48-4... powder (light) or a relatively dense white powder (heavy) by heating magnesium hydroxide or...

  18. 21 CFR 582.1431 - Magnesium oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium oxide. 582.1431 Section 582.1431 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1431 Magnesium oxide. (a) Product. Magnesium oxide. (b) Conditions of use. This substance...

  19. Separation medium containing thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Herrera-Alonso, Margarita (Inventor)

    2012-01-01

    A separation medium, such as a chromatography filling or packing, containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g, wherein the thermally exfoliated graphite oxide has a surface that has been at least partially functionalized.

  20. Er-doped aluminium oxide waveguide amplifiers

    NARCIS (Netherlands)

    Pollnau, M.

    2008-01-01

    Within the EU STREP project "Photonic integrated devices in activated amorphous and crystalline oxides" (PI-OXIDE, http://pi-oxide.el.utwente.nl/), 6 partners are developing integrated optical devices based on erbium-doped layers of amorphous $Al_2O_3$ and crystalline $Y_2O_3)$. In $Al_2O_3$:Er chan

  1. Methane oxidation needs less stressed plants.

    Science.gov (United States)

    Zhou, Xiaoqi; Smaill, Simeon J; Clinton, Peter W

    2013-12-01

    Methane oxidation rates in soil are liable to be reduced by plant stress responses to climate change. Stressed plants exude ethylene into soil, which inhibits methane oxidation when present in the soil atmosphere. Here we discuss opportunities to use 1-aminocyclopropane-1-carboxylate deaminase to manage methane oxidation by regulating plant stress responses.

  2. Myoglobin-induced lipid oxidation : A review

    DEFF Research Database (Denmark)

    Baron, Caroline; Andersen, H.J.

    2002-01-01

    An overview of myoglobin-initiated lipid oxidation in simple model systems, muscle, and muscle-based foods is presented. The potential role of myoglobin spin and redox states in initiating lipid oxidation is reviewed. Proposed mechanisms for myoglobin- initiated lipid oxidation in muscle tissue (p...

  3. 21 CFR 582.5991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc oxide. 582.5991 Section 582.5991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is...

  4. 21 CFR 182.8991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc oxide. 182.8991 Section 182.8991 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally recognized as safe when used...

  5. 21 CFR 73.2991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Zinc oxide. 73.2991 Section 73.2991 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and specifications to the requirements of §...

  6. 21 CFR 73.1991 - Zinc oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Zinc oxide. 73.1991 Section 73.1991 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1991 Zinc oxide. (a) Identity. (1) The color additive zinc...). It is principally composed of Zn. (2) Color additive mixtures for drug use made with zinc oxide...

  7. Dense high temperature ceramic oxide superconductors

    Science.gov (United States)

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  8. Graphene oxide reduction recipes, spectroscopy, and applications

    CERN Document Server

    Gao, Wei

    2015-01-01

    This book focuses on a group of new materials labeled ""graphene oxides."" It provides a comprehensive overview of graphene oxide-based nanomaterials in terms of their synthesis, structures, properties, and extensive applications in catalysis, separation, filtration, energy storage and conversion. The book also covers emerging research on graphite oxides and the impact of the research on fundamental and applied sciences.

  9. Oxidation and Reduction Reactions in Organic Chemistry

    Science.gov (United States)

    Shibley, Ivan A., Jr.; Amaral, Katie E.; Aurentz, David J.; McCaully, Ronald J.

    2010-01-01

    A variety of approaches to the concept of oxidation and reduction appear in organic textbooks. The method proposed here is different than most published approaches. The oxidation state is calculated by totaling the number of heterogeneous atoms, [pi]-bonds, and rings. A comparison of the oxidation states of reactant and product determine what type…

  10. Laser Photoacoustic Technique Detects Photo-Oxidation

    Science.gov (United States)

    Liange, R. H.; Coulter, D. R.; Gupta, A.

    1986-01-01

    Laser photoacoustic instrument detects small amounts of oxidation in polymers. Instrument used to evaluate resistance to oxidation in Sunlight of polymer encapsulants for solar-cell arrays. With instrument, researchers monitor samples for early stages of photooxidation and study primary mechanisms of oxidation and degradation. Effects of these mechanisms masked during later stages.

  11. Processes regulating nitric oxide emissions from soils

    DEFF Research Database (Denmark)

    Pilegaard, Kim

    2013-01-01

    Nitric oxide (NO) is a reactive gas that plays an important role in atmospheric chemistry by influencing the production and destruction of ozone and thereby the oxidizing capacity of the atmosphere. NO also contributes by its oxidation products to the formation of acid rain. The major sources...

  12. Nitrous oxide sedation and sexual phenomena.

    Science.gov (United States)

    Jastak, J T; Malamed, S F

    1980-07-01

    Nine cases of sexual phenomena that occurred with use of nitrous oxide and oxygen sedation are described. Dentists involved routinely used concentrations of nitrous oxide greater than 50% and did not have assistants in the room during dental procedures. Recommendations on the concentrations of nitrous oxide and the presence of an assistant are made.

  13. Advanced methods for the treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Debellefontaine, Hubert; Chakchouk, Mehrez; Foussard, Jean Noel [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France). Dept. de Genie des Procedes Industriels; Tissot, Daniel; Striolo, Phillipe [IDE Environnement S.A., Toulouse (France)

    1993-12-31

    There is a growing concern about the problems of wastes elimination. Various oxidation techniques are suited for elimination of organic aqueous wastes, however, because of the environmental drawbacks of incineration, liquid phase oxidation should be preferred. `Wet Air Oxidation` and `Wet Peroxide Oxidation`are alternative processes which are discussed in this paper. 17 refs., 13 figs., 4 tabs.

  14. Complete Maps for the Internal Oxidation of Ideal Ternary Alloys Forming Insoluble Oxides under High Oxidant Pressures

    Institute of Scientific and Technical Information of China (English)

    F.GESMUNDO; S.WANG; Y.NIU

    2009-01-01

    This paper presents an analysis of the conditions of stability of the different forms of internal oxidation of ideal ternary A-B-C alloys, where A is the most noble and C the most reactive component, forming insoluble oxide and exposed to high pressures of a single oxidant. The treatment, based on an extension to ternary alloys of Wagner's criterion for the transition from internal to external oxidation in binary alloys, allows to predict the existence of three different forms of internal oxidation. In fact, in addition to the most common kinds of internal attack, involving the coupled internal oxidation of B+C beneath external AO scales and the internal oxidation of C beneath external BO scales, a third mode, involving the internal oxidation of C beneath external scales composed of mixtures of AO+BO, becomes also possible under special conditions. A combination of the boundary conditions for the existence of these different types of internal oxidation allows to predict three different kinds of complete maps for the internal oxidation in these systems, one of which involves only two modes, while the other two involve all the three possible modes of internal oxidation.

  15. Microstructural characterization and field emission properties of tungsten oxide and titanium-oxide-doped tungsten oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chia-Hsiang [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan (China); Su, Cherng-Yuh, E-mail: cysu@ntut.edu.tw [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Lin, Yan-Fu [Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan (China)

    2015-03-01

    Tungsten oxide and titanium-oxide-doped tungsten oxide nanowires were synthesized by using the DC magnetron sputtering and infrared furnace annealing processes. Scanning election microscopy (SEM) and transmission electron microscopy (TEM) were utilized to evaluate the topography and sizes. X-ray diffraction (XRD), grazing incidence X-ray diffraction (GI-XRD), and high-resolution transmission electron microscopy (HRTEM) were used to analyze the composition and structure. From the results of HRTEM, it was discovered that the prepared nanowires have a monoclinic single-crystal phase of W{sub 18}O{sub 49} with lattice growth along the (010) lattice plane, and the lattice spacing is 0.378 nm, which agrees with XRD and GI-XRD results. The prepared tungsten oxide and titanium-oxide-doped tungsten oxide nanowires have turn-on voltage of 3.06 V/μm and 1.46 V/μm respectively. They also possess superior field enhancement factors of 5103 and 10667 respectively. Their behavior thus follows the Fowler-Nordheim expression for tunneling. - Highlights: • A simple method to prepare tungsten oxide nanowires by annealing tungsten film. • High aspect ratio of the 1D titanium-oxide-doped tungsten oxide nanowires. • High field enhancement factor of titanium-oxide-doped tungsten oxide nanowires.

  16. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    Directory of Open Access Journals (Sweden)

    C. R. Löscher

    2012-07-01

    Full Text Available The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA over their bacterial counterparts (AOB in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O that occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been reported to produce N2O.

    Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA were detectable throughout the water column of the eastern tropical North Atlantic (ETNA and eastern tropical South Pacific (ETSP Oceans. Particularly in the ETNA, comparable patterns of abundance and expression of archaeal amoA genes and N2O co-occurred in the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved

  17. Production of oceanic nitrous oxide by ammonia-oxidizing archaea

    Directory of Open Access Journals (Sweden)

    C. R. Loescher

    2012-02-01

    Full Text Available The recent finding that microbial ammonia oxidation in the ocean is performed by archaea to a greater extent than by bacteria has drastically changed the view on oceanic nitrification. The numerical dominance of archaeal ammonia-oxidizers (AOA over their bacterial counterparts (AOB in large parts of the ocean leads to the hypothesis that AOA rather than AOB could be the key organisms for the oceanic production of the strong greenhouse gas nitrous oxide (N2O which occurs as a by-product of nitrification. Very recently, enrichment cultures of marine ammonia-oxidizing archaea have been described to produce N2O. Here, we demonstrate that archaeal ammonia monooxygenase genes (amoA were detectable throughout the water column of the Eastern Tropical North Atlantic (ETNA and Eastern Tropical South Pacific Oceans (ETSP. Particularly in the ETNA, maxima in abundance and expression of archaeal amoA genes correlated with the N2O maximum and the oxygen minimum, whereas the abundances of bacterial amoA genes were negligible. Moreover, selective inhibition of archaea in seawater incubations from the ETNA decreased the N2O production significantly. In studies with the only cultivated marine archaeal ammonia-oxidizer Nitrosopumilus maritimus SCM1, we provide the first direct evidence for N2O production in a pure culture of AOA, excluding the involvement of other microorganisms as possibly present in enrichments. N. maritimus showed high N2O production rates under low oxygen concentrations comparable to concentrations existing in the oxycline of the ETNA, whereas the N2O production from two AOB cultures was comparably low under similar conditions. Based on our findings, we hypothesize that the production of N2O in tropical ocean areas results mainly from archaeal nitrification and will be affected by the predicted decrease in dissolved oxygen

  18. [Research on synergy of combining electrochemical oxidation and catalytic wet oxidation].

    Science.gov (United States)

    Wang, Hua; Li, Guang-Ming; Zhang, Fang; Huang, Ju-Wen

    2009-07-15

    A new catalytic wet oxidation fixed-bed reactor combined with three-dimensional electric-field was developed to investigate catalytic wet oxidation, electrochemical oxidation and electroassisted catalytic wet oxidation of the solution containing phenol in the presence of a catalyst Mn-Sn-Sb-3/gamma-Al2O3. Good electroassisted catalytic wet oxidation efficiency was obtained in the setup for the combination system even at mild conditions (T = 130 degrees C, po2 = 1.0 MPa) that the phenol conversion and TOC reduction were up to 94.0% and 88.4% after 27 min treatment, respectively. The result also shows that the rate constants of electroassisted catalytic wet oxidation are much higher than that of not only both catalytic wet oxidation and electrochemical oxidation process alone but also additive efficiencies of catalytic wet oxidation and electrochemical oxidation processes, which indicates an apparent synergetic effect between CWO and ECO processes.

  19. Synthesis of Graphene Oxide by Oxidation of Graphite with Ferrate(VI) Compounds: Myth or Reality?

    Science.gov (United States)

    Sofer, Zdeněk; Luxa, Jan; Jankovský, Ondřej; Sedmidubský, David; Bystroň, Tomáš; Pumera, Martin

    2016-09-19

    It is well established that graphene oxide can be prepared by the oxidation of graphite using permanganate or chlorate in an acidic environment. Recently, however, the synthesis of graphene oxide using potassium ferrate(VI) ions has been reported. Herein, we critically replicate and evaluate this new ferrate(VI) oxidation method. In addition, we test the use of potassium ferrate(VI) for the synthesis of graphene oxide under various experimental routes. The synthesized materials are analyzed by a number of analytical methods in order to confirm or disprove the possibility of synthesizing graphene oxide by the ferrate(VI) oxidation route. Our results confirm the unsuitability of using ferrate(VI) for the oxidation of graphite on graphene oxide because of its high instability in an acidic environment and low oxidation power in neutral and alkaline environments.

  20. Oxidation of Elemental Sulfur to Sulfite by Thiobacillus thiooxidans Cells

    OpenAIRE

    Suzuki, Isamu; Chan, C. W.; Takeuchi, T. L.

    1992-01-01

    Thiobacillus thiooxidans cells oxidized elemental sulfur to sulfite, with 1 mol of O2 consumption per mol of sulfur oxidized to sulfite, when the oxidation of sulfite was inhibited with 2-n-heptyl-4-hydroxyquinoline N-oxide.

  1. Biochemistry of Dissimilatory Sulfur Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Blake II, R.

    2003-05-30

    The long term goals of this research were to define the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during the dissimilatory oxidation of sulfur practiced by various species of the thiobacilli. Specific adhesion of the thiobacilli to elemental sulfur was studied by electrical impedance, dynamic light scattering, laser Doppler velocimetry, and optical trapping methods. The conclusion is that the thiobacilli appear to express specific receptors that enable the bacteria to recognize and adhere to insoluble sulfur. The enzyme tetrathionate oxidase was purified from two species of the thiobacilli. Extensive structural and functional studies were conducted on adenosine 5'-phosphosulfate reductase purified from cell-free extracts of Thiobacillus denitrificans. The kinetic mechanism of rhodanese was studied.

  2. Graphene Oxides Show Angiogenic Properties.

    Science.gov (United States)

    Mukherjee, Sudip; Sriram, Pavithra; Barui, Ayan Kumar; Nethi, Susheel Kumar; Veeriah, Vimal; Chatterjee, Suvro; Suresh, Kattimuttathu Ittara; Patra, Chitta Ranjan

    2015-08-05

    Angiogenesis, a process resulting in the formation of new capillaries from the pre-existing vasculature plays vital role for the development of therapeutic approaches for cancer, atherosclerosis, wound healing, and cardiovascular diseases. In this report, the synthesis, characterization, and angiogenic properties of graphene oxide (GO) and reduced graphene oxide (rGO) have been demonstrated, observed through several in vitro and in vivo angiogenesis assays. The results here demonstrate that the intracellular formation of reactive oxygen species and reactive nitrogen species as well as activation of phospho-eNOS and phospho-Akt might be the plausible mechanisms for GO and rGO induced angiogenesis. The results altogether suggest the possibilities for the development of alternative angiogenic therapeutic approach for the treatment of cardiovascular related diseases where angiogenesis plays a significant role.

  3. Oxidative Stress and HPV Carcinogenesis

    Directory of Open Access Journals (Sweden)

    Federico De Marco

    2013-02-01

    Full Text Available Extensive experimental work has conclusively demonstrated that infection with certain types of human papillomaviruses, the so-called high-risk human papillomavirus (HR-HPV, represent a most powerful human carcinogen. However, neoplastic growth is a rare and inappropriate outcome in the natural history of HPV, and a number of other events have to concur in order to induce the viral infection into the (very rare neoplastic transformation. From this perspective, a number of putative viral, host, and environmental co-factors have been proposed as potential candidates. Among them oxidative stress (OS is an interesting candidate, yet comparatively underexplored. OS is a constant threat to aerobic organisms being generated during mitochondrial oxidative phosphorylation, as well as during inflammation, infections, ionizing irradiation, UV exposure, mechanical and chemical stresses. Epithelial tissues, the elective target for HPV infection, are heavily exposed to all named sources of OS. Two different types of cooperative mechanisms are presumed to occur between OS and HPV: I The OS genotoxic activity and the HPV-induced genomic instability concur independently to the generation of the molecular damage necessary for the emergence of neoplastic clones. This first mode is merely a particular form of co-carcinogenesis; and II OS specifically interacts with one or more molecular stages of neoplastic initiation and/or progression induced by the HPV infection. This manuscript was designed to summarize available data on this latter hypothesis. Experimental data and indirect evidences on promoting the activity of OS in viral infection and viral integration will be reviewed. The anti-apoptotic and pro-angiogenetic role of NO (nitric oxide and iNOS (inducible nitric oxide synthase will be discussed together with the OS/HPV cooperation in inducing cancer metabolism adaptation. Unexplored/underexplored aspects of the OS interplay with the HPV-driven carcinogenesis

  4. Oxidative stress in neurodegenerative diseases

    Institute of Scientific and Technical Information of China (English)

    Xueping Chen; Chunyan Guo; Jiming Kong

    2012-01-01

    Reactive oxygen species are constantly produced in aerobic organisms as by-products of normal oxygen metabolism and include free radicals such as superoxide anion (O2-) and hydroxyl radical (OH-), and non-radical hydrogen peroxide (H2O2). The mitochondrial respiratory chain and enzymatic reactions by various enzymes are endogenous sources of reactive oxygen species. Exogenous reactive oxygen species -inducing stressors include ionizing radiation, ultraviolet light, and divergent oxidizing chemicals. At low concentrations, reactive oxygen species serve as an important second messenger in cell signaling; however, at higher concentrations and long-term exposure, reactive oxygen species can damage cellular macromolecules such as DNA, proteins, and lipids, which leads to necrotic and apoptotic cell death. Oxidative stress is a condition of imbalance between reactive oxygen species formation and cellular antioxidant capacity due to enhanced ROS generation and/or dysfunction of the antioxidant system. Biochemical alterations in these macromolecular components can lead to various pathological conditions and human diseases, especially neurodegenerative diseases. Neurodegenerative diseases are morphologically featured by progressive cell loss in specific vulnerable neuronal cells, often associated with cytoskeletal protein aggregates forming inclusions in neurons and/or glial cells. Deposition of abnormal aggregated proteins and disruption of metal ions homeostasis are highly associated with oxidative stress. The main aim of this review is to present as much detailed information as possible that is available on various neurodegenerative disorders and their connection with oxidative stress. A variety of therapeutic strategies designed to address these pathological processes are also described. For the future therapeutic direction, one specific pathway that involves the transcription factor nuclear factor erythroid 2-related factor 2 is receiving considerable attention.

  5. Graphene oxide physics and applications

    CERN Document Server

    Zhao, Jijun; Li, Fen

    2015-01-01

    This book gives a comprehensive overview of graphene oxides (GO)  from atomic structures and fundamental properties to technological applications. Atomic structural models, electronic properties, mechanical properties, optical properties, and functionalizing and compositing of GO are illustrated. Moreover, the excellent physical and chemical properties offer GO promising applications in electronic nanodevices, chemical sensors and catalyst, energy storage, and biotechnology, which are also presented in this book. Therefore, this book is of interest to researchers in physics, chemistry, materials science, and nanoscience.

  6. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Dezhao, Liu; Hansen, Michael Jørgen;

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  7. Sulfide oxidation in a biofilter

    DEFF Research Database (Denmark)

    Pedersen, Claus Lunde; Liu, Dezhao; Hansen, Michael Jørgen;

    2012-01-01

    Observed hydrogen sulfide uptake rates in a biofilter treating waste air from a pig farm were too high to be explained within conventional limits of sulfide solubility, diffusion in a biofilm and bacterial metabolism. Clone libraries of 16S and 18S rRNA genes from the biofilter found no sulfide o...... higher hydrogen sulfide uptake followed by oxidation catalyzed by iron-containing enzymes such as cytochrome c oxidase in a process uncoupled from energy conservation....

  8. Skin aging and oxidative stress

    OpenAIRE

    Sayeeda Ahsanuddin; Minh Lam; Baron, Elma D.

    2016-01-01

    Skin aging occurs through two main pathways, intrinsic and extrinsic. These pathways have significant interaction in contributing to the aging phenotype, which includes skin laxity, wrinkling, pigmentation irregularities, and the appearance of neoplastic skin lesions. Here, we review the critical role that oxidative stress plays in skin aging, including its effects on signaling pathways involved in skin matrix formation and degradation, proteasome activity, as well as DNA structure. Furthermo...

  9. Oxidation of AsⅢ by Several Manganese Oxide Minerals in Absence and Presence of Goethite

    Institute of Scientific and Technical Information of China (English)

    FENG Xionghan; TAN Wenfeng; LIU Fan; Huada Daniel RUAN; HE Jizheng

    2006-01-01

    Oxidation of AsⅢ by three types of manganese oxide minerals affected by goethite was investigated by chemical analysis, equilibrium redox, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Three synthesized Mn oxide minerals of different types, birnessite,todorokite, and hausmannite, could actively oxidize AsⅢ to AsⅤ, and greatly varied in their oxidation ability. Layer structured birnessite exhibited the highest capacity of AsⅢ oxidation, followed by the tunnel structured todorokite. Lower oxide hausmannite possessed much low capacity of AsⅢ oxidation,and released more Mn2+ than birnessite and todorokite during the oxidation. The maximum amount of Asv produced during the oxidation of AsⅢ by Mn oxide minerals was in the order: birnessite (480.4mmol/kg) > todorokite (279.6 mmol/kg) > hausmannite (117.9 mmol/kg). The oxidation capacity of the Mn oxide minerals was found to be relative to the composition, crystallinity, and surface properties. In the presence of goethite oxidation of AsⅢ by Mn oxide minerals increased, with maximum amounts of Asv being 651.0 mmol/kg for birnessite, 332.3 mmol/kg for todorokite and 159.4 mmol/kg for hausmannite. Goethite promoted AsⅢ oxidation on the surface of Mn oxide minerals through adsorption of the Asv produced, incurring the decrease of Asv concentration in solutions. Thus, the combined effects of the oxidation (by Mn oxide minerals)-adsorption (by goethite) lead to rapid oxidation and immobilization of As in soils and sediments and alleviation of the AsⅢ toxicity in the environments.

  10. Tissue damage and oxidant/antioxidant balance.

    Science.gov (United States)

    Kisaoglu, Abdullah; Borekci, Bunyamin; Yapca, O Erkan; Bilen, Habib; Suleyman, Halis

    2013-02-01

    The oxidant/antioxidant balance in healthy tissues is maintained with a predominance of antioxidants. Various factors that can lead to tissue damage disrupt the oxidant/antioxidant balance in favor of oxidants. In this study, disruptions of the oxidant/antioxidant balance in favor of oxidants were found to be a consequence of the over-consumption of antioxidants. For this reason, antioxidants are considered to be of importance in the prevention and treatment of various types of tissue damage that are aggravated by stress.

  11. Nanoparticular metal oxide/anatase catalysts

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention concerns a method of preparation of nanoparticular metal oxide catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular metal oxide catalyst precursors comprising combustible crystallization seeds upon which...... the catalyst metai oxide is co-precipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step. The present invention also concerns processes wherein the nanoparticular metal oxide catalysts of the invention are used, such as SCR (deNOx) reactions...

  12. Oxide ultrathin films science and technology

    CERN Document Server

    Pacchioni, Gianfranco

    2012-01-01

    A wealth of information in one accessible book. Written by international experts from multidisciplinary fields, this in-depth exploration of oxide ultrathin films covers all aspects of these systems, starting with preparation and characterization, and going on to geometrical and electronic structure, as well as applications in current and future systems and devices. From the Contents: Synthesis and Preparation of Oxide Ultrathin FilmsCharacterization Tools of Oxide Ultrathin FilmsOrdered Oxide Nanostructures on Metal SurfacesUnusual Properties of Oxides and Other Insulators in the Ultrathin Li

  13. Oxidized Form of Creatine Kinase

    Institute of Scientific and Technical Information of China (English)

    王希成; 王帆; 邹晓明; 周海梦

    1994-01-01

    The purified rabbit muscle creatine kinase (R-CK) was previously considered homogeneousand without disulfide bonds.By the method of NR/R two-dimensional diagonal SDS-PAGE,two forms of R-CK,designated respectively "oxidized form" of creatine kinase which contained intrachain disulfide bondsand "reduced form" of creatine kinase which did not have any —S—S— bridges,were for the first time sepa-rated.They were found to be the same in amino acid composition,in subunit molecular Weight and in isoelec-tric point,and were almost identical in enzyme activities.Thus it is hard to isolate one from the other bycommon biochemical methods.More extensive studies show that the oxidized form of CK also contains a pair of reactive thiol groupswhich are essential to the enzyme activity,and it has one intrachain disulfide bond per subunit.In the nativestate,this —S—S— bond cannot be reduced by DTT,but by treating the reduced form of CK with some ox-idants,these —S—S— bonds can be formed in vitro.Thus it is presumed that the disulfide bonds are cross-linked through the oxidization of two shallowly buried —SH groups.

  14. Oxidative stress and glycemic regulation.

    Science.gov (United States)

    Ceriello, A

    2000-02-01

    Oxidative stress is an acknowledged pathogenetic mechanism in diabetic complications. Hyperglycemia is a widely known cause of enhanced free radical concentration, whereas oxidative stress involvement in glycemic regulation is still debated. Glucose transport is a cascade of events starting from the interaction of insulin with its own receptor at the plasma membrane and ending with intracellular glucose metabolism. In this complex series of events, each step plays an important role and can be inhibited by a negative effect of oxidative stress. Several studies show that an acute increase in the blood glucose level may impair the physiological homeostasis of many systems in living organisms. The mechanisms through which acute hyperglycemia exerts these effects may be identified in the production of free radicals. It has been suggested that insulin resistance may be accompanied by intracellular production of free radicals. In adipocytes cultured in vitro, insulin increases the production of hydrogen peroxide, which has been shown to mimic the action of insulin. These data allow us to hypothesize that a vicious circle between hyperinsulinemia and free radicals could be operating: insulin resistance might cause elevated plasma free radical concentrations, which, in turn, might be responsible for a deterioration of insulin action, with hyperglycemia being a contributory factor. Data supporting this hypothesis are available. Vitamin E improves insulin action in healthy, elderly, and non-insulin-dependent diabetic subjects. Similar results can be obtained by vitamin C administration.

  15. Metal oxides for optoelectronic applications.

    Science.gov (United States)

    Yu, Xinge; Marks, Tobin J; Facchetti, Antonio

    2016-04-01

    Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III-V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p-n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

  16. Metal oxides for optoelectronic applications

    Science.gov (United States)

    Yu, Xinge; Marks, Tobin J.; Facchetti, Antonio

    2016-04-01

    Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III-V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p-n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

  17. Oxidation process of lanthanum hexaboride ceramics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Oxidation process of lanthanum hexaboride (LaB6) ceramic powder was investigated . The LaB6 powder samples were heated continually from room temperature to 1 473 K at a heating rate of 10 K/min by differential scanning calorimetry. The oxidation tests were conducted at different exposure temperatures. The phases and morphologies of the samples before and after exposure were analyzed by XRD and SEM. It was pointed out that before 1 273 K, LaB6 has high oxidation resistant ability, which was due to that the oxide layer hinders the oxygen diffusion from outer to the surface of LaB6 grains. The oxide layer was composed of the transition phases, which were composed of La2O3 and B2O3 formed from the initial oxidation; when the oxidation temperature exceeded 1 273 K, protective layer was destroyed due to the vaporization of liquid B2O3. Based on the results of X-ray diffraction analysis, oxidation process of LaB6 ceramic powder can be described as follows: Before 1 273 K, lanthanum borate,La(BO2)3 was formed on the surface of samples, then lanthanum oxide (La2O3) and boron oxide (B2O3) were present on the surface of samples oxidized when the temperature reached to 1 473 K.

  18. Electro-catalytic reduction of nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    McLarnon, C.R.

    1989-12-01

    Nitrogen oxides have been linked to a broad range of air pollution problems including acid rain and the atmospheric production of photochemical ozone. Over twenty million tons of nitrogen oxides are emitted into the atmosphere each year as a result of the high temperature combustion of fossil fuels. Efforts to control nitrogen oxides emissions have lagged because of the generally low discharge concentrations of nitrogen oxides in combustion exhaust and because nitrogen oxides are more difficult to remove due to their lower reactivity. No catalyst has yet been found that will achieve significant reduction of nitrogen oxides in an oxidizing environment. Oxygen in the exhaust stream competes with nitrogen oxides for the active catalyst sites. Also, the dissociated oxygen atoms produced by decomposition of nitrogen oxides deactivate the surface of the catalyst. Externally applied electric fields have been used to control oxygen adsorption on metal and semi-conductor surfaces. In this investigation, a stream containing nitric oxide has been subjected to intense electric fields in the presence of catalyst materials including steel, stainless steel, and gold plated stainless steel wools and glass wool. The electric fields have been generated using DC, AC and rectified AC potentials in the range of 0--20 KV. The effect of parameters such as inlet nitric oxide concentration, oxygen and water content, gas residence time and temperature have also been studied.

  19. Accelerated evaporation of water on graphene oxide.

    Science.gov (United States)

    Wan, Rongzheng; Shi, Guosheng

    2017-03-15

    Using molecular dynamics simulations, we show that the evaporation of nanoscale volumes of water on patterned graphene oxide is faster than that on homogeneous graphene oxide. The evaporation rate of water is insensitive to variation in the oxidation degree of the oxidized regions, so long as the water film is only distributed on the oxidized regions. The evaporation rate drops when the water film spreads onto the unoxidized regions. Further analysis showed that varying the oxidation degree observably changed the interaction between the outmost water molecules and the solid surface, but the total interaction for the outmost water molecules only changed a very limited amount due to the correspondingly regulated water-water interaction when the water film is only distributed on the oxidized regions. When the oxidation degree is too low and some unoxidized regions are also covered by the water film, the thickness of the water film decreases, which extends the lifetime of the hydrogen bonds for the outmost water molecules and lowers the evaporation rate of the water. The insensitivity of water evaporation to the oxidation degree indicates that we only need to control the scale of the unoxidized and oxidized regions for graphene oxide to regulate the evaporation of nanoscale volumes of water.

  20. Measurement of oxide adherence to PFM alloys.

    Science.gov (United States)

    Mackert, J R; Parry, E E; Hashinger, D T; Fairhurst, C W

    1984-11-01

    A method has been reported for evaluating adherence of an oxide to its substrate metal to a maximum value of about 40 MPa. Oxidized alloy plates were cemented between two aluminum cylinders with a high-strength cyanoacrylate cement and loaded in tension until failure occurred either at the oxide/metal interface, within the oxide layer, or in the cement itself. Significant differences were found among the oxide adherence values obtained from different PFM alloys. The oxides formed on five of the alloys exhibited adherence strengths in excess of the published value for cohesive strength of dental opaque porcelain, indicating that they possess sufficient adherence to act as the transition zone between the porcelain and the alloy. In addition, a correspondence was found between the quality of porcelain bond for a given alloy and its oxide adherence strength. These results remove the principal objection to the oxide-layer theory of porcelain bonding in dental alloy systems and emphasize the importance of oxide adherence in the establishment of a bond. It is therefore suggested that future work devoted to porcelain-metal bonding should seek to elucidate the mechanism of oxide adherence to PFM alloys and explore the development of new alloys which form adherent oxides.

  1. Nylon/Graphene Oxide Electrospun Composite Coating

    Directory of Open Access Journals (Sweden)

    Carmina Menchaca-Campos

    2013-01-01

    Full Text Available Graphite oxide is obtained by treating graphite with strong oxidizers. The bulk material disperses in basic solutions yielding graphene oxide. Starting from exfoliated graphite, different treatments were tested to obtain the best graphite oxide conditions, including calcination for two hours at 700°C and ultrasonic agitation in acidic, basic, or peroxide solutions. Bulk particles floating in the solution were filtered, rinsed, and dried. The graphene oxide obtained was characterized under SEM and FTIR techniques. On the other hand, nylon 6-6 has excellent mechanical resistance due to the mutual attraction of its long chains. To take advantage of the properties of both materials, they were combined as a hybrid material. Electrochemical cells were prepared using porous silica as supporting electrode of the electrospun nylon/graphene oxide films for electrochemical testing. Polarization curves were performed to determine the oxidation/reduction potentials under different acidic, alkaline, and peroxide solutions. The oxidation condition was obtained in KOH and the reduction in H2SO4 solutions. Potentiostatic oxidation and reduction curves were applied to further oxidize carbon species and then reduced them, forming the nylon 6-6/functionalized graphene oxide composite coating. Electrochemical impedance measurements were performed to evaluate the coating electrochemical resistance and compared to the silica or nylon samples.

  2. Oxidative stress in neonatology: a review.

    Science.gov (United States)

    Mutinati, M; Pantaleo, M; Roncetti, M; Piccinno, M; Rizzo, A; Sciorsci, R L

    2014-02-01

    Free radicals are highly reactive oxidizing agents containing one or more unpaired electrons. Both in human and veterinary neonathology, it is generally accepted that oxidative stress functions as an important catalysator of neonatal disease. Soon after birth, many sudden physiological and environmental conditions make the newborn vulnerable for the negative effects of oxidative stress, which potentially can impair neonatal vitality. As a clinician, it is important to have in depth knowledge about factors affecting maternal/neonatal oxidative status and the cascades of events that enrol when the neonate is subjected to oxidative stress. This report aims at providing clinicians with an up-to-date review about oxidative stress in neonates across animal species. It will be emphasized which handlings and treatments that are applied during neonatal care or resuscitation can actually impose oxidative stress upon the neonate. Views and opinions about maternal and/or neonatal antioxydative therapy will be shared.

  3. Thermal Oxidation of Silicon Carbide Substrates

    Institute of Scientific and Technical Information of China (English)

    Xiufang Chen; Li'na Ning; Yingmin Wang; Juan Li; Xiangang Xu; Xiaobo Hu; Minhua Jiang

    2009-01-01

    Thermal oxidation was used to remove the subsurface damage of silicon carbide (SiC) surfaces. The anisotrow of oxidation and the composition of oxide layers on Si and C faces were analyzed. Regular pits were observed on the surface after the removal of the oxide layers, which were detrimental to the growth of high quality epitaxial layers. The thickness and composition of the oxide layers were characterized by Rutherford backscat-tering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS), respectively. Epitaxial growth was performed in a metal organic chemical vapor deposition (MOCVD) system. The substrate surface morphol-ogy after removing the oxide layer and gallium nitride (GaN) epilayer surface were observed by atomic force microscopy (AFM). The results showed that the GaN epilayer grown on the oxidized substrates was superior to that on the unoxidized substrates.

  4. Nanowire-based All Oxide Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

    2008-12-07

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

  5. Oxidation-reduction catalyst and its process of use

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor)

    2008-01-01

    This invention relates generally to a ruthenium stabilized oxidation-reduction catalyst useful for oxidizing carbon monoxide, and volatile organic compounds, and reducing nitrogen oxide species in oxidizing environments, substantially without the formation of toxic and volatile ruthenium oxide species upon said oxidizing environment being at high temperatures.

  6. Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Harthøj, Anders; Holt, Tobias; Møller, Per

    2015-01-01

    This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples......, Mn, Fe and Cr oxide and the inner layer consisted of Cr oxide. The CeO2 was present as discrete particles in the outer oxide layer after exposure. The Cr oxide layer thicknesses and oxidations rates were significantly reduced for Co/CeO2 coated samples compared to for Co coated and uncoated samples...... are exposed in air at 800 °C for 3000 h and oxidation rates are measured and oxide scale microstructures are investigated. Area-specific resistances (ASR) in air at 850 °C of coated and uncoated samples are also measured. A dual layered oxide scale formed on all coated samples. The outer layer consisted of Co...

  7. Assay Methods for H2S Biogenesis and Catabolism Enzymes

    Science.gov (United States)

    Banerjee, Ruma; Chiku, Taurai; Kabil, Omer; Libiad, Marouane; Motl, Nicole; Yadav, Pramod K.

    2015-01-01

    H2S is produced from sulfur-containing amino acids, cysteine and homocysteine, or a catabolite, 3-mercaptopyruvate, by three known enzymes: cystathionine β-synthase, γ-cystathionase, and 3-mercaptopyruvate sulfurtransferase. Of these, the first two enzymes reside in the cytoplasm and comprise the transsulfuration pathway, while the third enzyme is found both in the cytoplasm and in the mitochondrion. The following mitochondrial enzymes oxidize H2S: sulfide quinone oxidoreductase, sulfur dioxygenase, rhodanese, and sulfite oxidase. The products of the sulfide oxidation pathway are thiosulfate and sulfate. Assays for enzymes involved in the production and oxidative clearance of sulfide to thiosulfate are described in this chapter. PMID:25725523

  8. Simulation of wet oxidation of silicon based on the interfacial silicon emission model and comparison with dry oxidation

    OpenAIRE

    Uematsu, Masashi; Kageshima, Hiroyuki; Shiraishi, Kenji

    2001-01-01

    Silicon oxidation in wet ambients is simulated based on the interfacial silicon emission model and is compared with dry oxidation in terms of the silicon-atom emission. The silicon emission model enables the simulation of wet oxidation to be done using the oxidant self-diffusivity in the oxide with a single activation energy. The amount of silicon emission from the interface during wet oxidation is smaller than that during dry oxidation. The small emission rate for wet oxidation is responsibl...

  9. High-temperature processing of oxide superconductors and superconducting oxide-silver oxide composite

    Science.gov (United States)

    Wu, M. K.; Loo, B. H.; Peters, P. N.; Huang, C. Y.

    1988-01-01

    High temperature processing was found to partially convert the green 211 phase oxide to 123 phase. High Tc superconductivity was observed in Bi-Sr-Cu-O and Y-Sr-Cu-O systems prepared using the same heat treatment process. High temperature processing presents an alternative synthetic route in the search for new high Tc superconductors. An unusual magnetic suspension with enhancement in critical current density was observed in the 123 and AgO composite.

  10. Improved Understanding of In Situ Chemical Oxidation Contaminant Oxidation Kinetics

    Science.gov (United States)

    2007-12-01

    bond. Evidence for the latter is strong, with many SO4•−-radical adducts having been identified during reactions of SO4•− with alkenes by electron...Greenstock, C.L., Helman, W.P., Ross, A.B., 1988. Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and...oxidation of alkenes and dienes by SO4-·, Cl2-·, and ·OH in acidic aqueous solution. J. Chem. Soc., Perkin Trans. 2, 1809-1815. 21. De Heredia, J.B

  11. Methodology for the effective stabilization of tin-oxide-based oxidation/reduction catalysts

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony N. (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

    2011-01-01

    The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

  12. A Self-Consistent Model for Thermal Oxidation of Silicon at Low Oxide Thickness

    Directory of Open Access Journals (Sweden)

    Gerald Gerlach

    2016-01-01

    Full Text Available Thermal oxidation of silicon belongs to the most decisive steps in microelectronic fabrication because it allows creating electrically insulating areas which enclose electrically conductive devices and device areas, respectively. Deal and Grove developed the first model (DG-model for the thermal oxidation of silicon describing the oxide thickness versus oxidation time relationship with very good agreement for oxide thicknesses of more than 23 nm. Their approach named as general relationship is the basis of many similar investigations. However, measurement results show that the DG-model does not apply to very thin oxides in the range of a few nm. Additionally, it is inherently not self-consistent. The aim of this paper is to develop a self-consistent model that is based on the continuity equation instead of Fick’s law as the DG-model is. As literature data show, the relationship between silicon oxide thickness and oxidation time is governed—down to oxide thicknesses of just a few nm—by a power-of-time law. Given by the time-independent surface concentration of oxidants at the oxide surface, Fickian diffusion seems to be neglectable for oxidant migration. The oxidant flux has been revealed to be carried by non-Fickian flux processes depending on sites being able to lodge dopants (oxidants, the so-called DOCC-sites, as well as on the dopant jump rate.

  13. New developments in oxidation catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Rosowski, F. [BASF SE, Ludwigshafen (Germany)

    2011-07-01

    The impact of heterogeneous catalysis on the economy can be depicted by the global revenue of the chemical industry in 2006, which accounted for 2200 billion Euros with a share of all chemical products produced applying heterogeneous catalysis of about two thirds. [1] The range of products is enormous and they contribute greatly to the quality of our lifes. The advancement in the development of basic and intermediate chemical products is crucially dependent on either the further development of existing catalyst systems or the development of new catalysts and key to success for the chemical industry. Within the context of oxidation catalysis, the following driving forces are guiding research activities: There is a continuous desire to increase the selectivity of a given process in response to both economic as well as ecological needs and taking advantage of higher efficiencies in terms of cost savings and a better utilization of raw materials. A second motivation focuses on raw material change to all abundant and competitive feedstocks requiring both new developments in catalyst design as well as process technology. A more recent motivation refers to the use of metal oxide redox systems which are key to success for the development of novel technologies allowing for the separation of carbon dioxide and the use of carbon dioxide as a feedstock molecule as well as storing renewable energy in a chemical. To date, general ab initio approaches are known for the design of novel catalytic materials only for a few chemical reactions, whereas most industrial catalytic processes have been developed by empirical methods. [2] The development of catalytic materials are either based on the targeted synthesis of catalytic lead structures as well as high throughput methods that allow for the screening of a large range of parameters. [3 - 5] The successful development of catalysts together with reactor technology has led to both significant savings in raw materials and emissions. The

  14. Graphene Oxide/ Ruthenium Oxide Composites for Supercapacitors Electrodes

    Science.gov (United States)

    Amir, Fatima

    Supercapacitors are electrical energy storage devices with high power density, high rate capability, low maintenance cost, and long life cycle. They complement or replace batteries in harvesting applications when high power delivery is needed. An important improvement in performance of supercapacitors has been achieved through recent advances in the development of new nanostructured materials. Here we will discuss the fabrication of graphene oxide/ ruthenium oxide supercacitors electrodes including electrophoretic deposition. The morphology and structure of the fabricated electrodes were investigated and will be discussed. The electrochemical properties were determined using cyclic voltammetry and galvanostatic charge/discharge techniques and the experiments that demonstrate the excellent capacitive properties of the obtained supercapacitors will also be discussed. The fabrication and characterization of the samples were performed at the Center of Functional Nanomaterials at Brookhaven National Lab. The developed approaches in our study represent an exciting direction for designing the next generation of energy storage devices. This work was supported in part by the U.S. Department of Energy through the Visiting Faculty Program and the research used resources of the Center for Functional Nanomaterials at Brookhaven National Laboratory.

  15. Dissolution of Uranium Oxides Under Alkaline Oxidizing Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.C.; Peper, S.M.; Douglas, M.; Ziegelgruber, K.L. [PNNL, PO Box 999, MS P8-08, Richland, WA 99352 (United States)

    2009-06-15

    Understanding the dissolution of uranium oxides is critical for designing and optimizing next-generation spent nuclear fuel (SNF) reprocessing methods. Bench scale experiments were conducted to determine the optimal dissolution parameters for size-fractionated aliquots of UO{sub 2}, UO{sub 3}, and U{sub 3}O{sub 8} powders in aqueous peroxide-carbonate solutions. Experimental parameters included; peroxide and carbonate concentrations, and temperature. Solution pH was varied with ammonium hydroxide. We will present details of the dissolution experiment set-up as well as information on the kinetics of dissolution of the various U-oxides as a function of the above variables. We will also discuss efforts to characterize solution and solid-state complexes in peroxide-carbonate systems. This study will demonstrate the applicability of peroxide-containing alkaline solutions for effectively dissolving SNF, and will enhance the current level of understanding of actinide behavior in peroxide-containing alkaline solutions. (authors)

  16. Oxidant pollution - Effects on health

    Energy Technology Data Exchange (ETDEWEB)

    Bignon, J.

    Oxidizing pollution consists of air-borne gaseous, liquid and particle pollutants acting like reducing agents that can react with oxygen to produce toxic derivatives: superoxide anion, hydrogen peroxide, hydroxyl radicles and other free radicles. The major oxidizing gaseous pollutants are NO/sub x,/ particularly NO/sub 2/, ozone and photo-oxidizing agents as derivatives. Epidemiological studies have generally failed to show any significant relation between NO/sub 2/ concentration and respiratory disorders. Correlations are better with SO/sub 2/ and total suspended particles. In certain very sunny areas with high ozone levels, there is a link between O/sub 3/ concentration and respiratory disorders. Controlled trials comparing healthy and asthmatic volunteers have given variable results with highly raised bronchoreactivity at concentrations of 0.1 to 0.2 ppm NO/sub 2/ and 0.25 ppm O/sub 3/ for 1 to 2 hours in about half the studies. Using this data, the World Health Organisation (WHO) has established maximum exposure levels. Numerous investigations on exposure of animals to NO/sub 2/ and ozone have been performed using rodents, the dog, the cat and the primate. At concentrations close to peak urban air pollution levels various biochemical and cellular changes in the respiratory apparatus are generally observed. The areas most affected by NO/sub 2/ and ozone are the peripheral airways with distal stenosal bronchiolitis. NO/sub 2/ led to emphysematous lesions and O/sub 3/ to fibrosal hyperplasic lesions in alveolar tissue. Short bursts at high levels were generally more toxic than long exposure at low levels. There is an additive effect between NO/sub 2/ and ozone and with other pollutants. Exposure to nitrogen dioxide and ozone is conducive to bacterial and viral infection. Results for genitotoxicity and carcinogenic effects produced by NO/sub 2/ and ozone have hitherto been inconclusive.

  17. Charge transfer in multicomponent oxides

    Science.gov (United States)

    Kohan, A. F.; Ceder, G.

    1998-02-01

    The transfer of charge between different ions in an oxide plays an essential role in the stability of these compounds. Since small variations in charge can introduce large changes in the total energy, a correct description of this phenomenon is critical. In this work, we show that the ionic charge in oxides can strongly depend on its atomic environment. A model to assign point charges to atoms as a function of their atomic environment has recently been proposed for binary alloys [C. Wolverton, A. Zunger, S. Froyen, and S.-H. Wei, Phys. Rev. B 54, 7843 (1996)] and proven to be very successful in screened solids such as semiconductors and metals. Here, we extend this formalism to multicomponent oxides and we assess its applicability. The simple point-charge model predicts a linear relation between the charge on an atom and the number of unlike neighbors, and between the net value of the charge and the Coulomb field at a given site. The applicability of this approach is tested in a large-supercell self-consistent tight-binding calculation for a random Zr-Ca-O alloy. The observed fluctuations of the ionic charge about the average linear behavior (as a function of the number of unlike neighbors) was larger than 0.25 electrons even when many shells of atomic neighbors were considered in the fit. This variation is significant since it can introduce large errors in the electrostatic energy. On the other hand, for small absolute values of the charge, the ionic charge varied linearly with the Coulomb field, in agreement with previous findings. However, for large Coulomb fields, this function saturates at the formal chemical charge.

  18. Oxidative Stress in Cystinosis Patients

    Directory of Open Access Journals (Sweden)

    Maria Helena Vaisbich

    2011-09-01

    Full Text Available Background/Aims: Nephropathic cystinosis (NC is a severe systemic disease and cysteamine improves its prognosis. Lysosomal cystine accumulation is the hallmark of cystinosis and is regarded as the primary defect due to mutations in the CTNS gene. However, there is great evidence that cystine accumulation itself is not responsible for all abnormalities observed in NC. Studies have demonstrated altered ATP metabolism, increased apoptosis, and cell oxidation. An increased number of autophagosomes and autophagic vacuoles have been observed in cystinotic fibroblasts and renal epithelial cells, suggesting that altered autophagy plays a role in NC, leading to increased production of reactive oxygen species. Therefore, cystinosis patients can be more susceptible to oxidative stress (OS and it can contribute to the progression of the renal disease. Our goal was to evaluate a marker of OS (serum TBARS in NC children, and to compare the results with those observed in healthy controls and correlated with renal function parameters. Methods: The study included patients aged under 18 years, with good adherence to the treatment and out of renal replacement therapy. The following parameters were evaluated: serum creatinine, BUN, creatinine clearance estimated by stature and serum TBARS levels. Results: We selected 20 patients aged 8.0 ±3.6 years and observed serum TBARS levels of 4.03 ±1.02 nmol/ml. Serum TBARS levels in the 43 healthy controls, aged 7.4 ±1.1 years, were 1.60 ±0.04 nmol/ml. There was a significant difference between the plasma TBARS levels among the 2 groups (p Conclusion: An increased level of serum TBARS in patients with NC was observed and this abnormality was not correlated with the renal function status degree. This is the first report that shows increased oxidative stress in serum of NC patients.

  19. Simulation of 3D mesoscale structure formation in concentrated aqueous solution of the triblock polymer surfactants (ethylene oxide)(13)(propylene oxide)(30)(ethylene oxide)(13) and (propylene oxide)(19)(ethylene oxide)(33)(propylene oxide)(19). Application of dynamic mean-field density functional theory

    NARCIS (Netherlands)

    van Vlimmeren, BAC; Maurits, NM; Zvelindovsky, AV; Sevink, GJA; Fraaije, JGEM

    1999-01-01

    We simulate the microphase separation dynamics of aqueous solutions of the triblock polymer surfactants (ethylene oxide)(13)(propylene oxide)(30)(ethylene oxide)(13) and (propylene oxide)(19)(ethylene oxide)(33)(propylene oxide)(19) by a dynamic variant of mean-field density functional theory for Ga

  20. Catalytic selective oxidation or oxidative functionalization of methane and ethane to organic oxygenates

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Selective oxidation or oxidative functionalization of methane and ethane by both homogeneous and heterogeneous catalysis is presented concerning: (1) selective oxidation of methane and ethane to organic oxygenates by hydrogen peroxide in a water medium in the presence of homogeneous osmium catalysts, (2) selective oxidation of methane to formaldehyde over highly dispersed iron and copper heterogeneous catalysts, (3) selective oxidation of ethane to acetaldehyde and formaldehyde over supported molybdenum catalysts, and (4) oxidative carbonylation of methane to methyl acetate over heterogeneous catalysts containing dual sites of rhodium and iron.

  1. Comparison of direct and indirect plasma oxidation of NO combined with oxidation by catalyst

    DEFF Research Database (Denmark)

    Jogi, Indrek; Stamate, Eugen; Irimiea, Cornelia

    2015-01-01

    Direct and indirect plasma oxidation of NOx was tested in a medium-scale test-bench at gas flows of 50 slm (3 m(3)/h). For direct plasma oxidation the synthetic flue gas was directed through a stacked DBD reactor. For indirect plasma oxidation, a DBD reactor was used to generate ozone from pure O-2...... of the DBD reactor decreased the long-term efficiency of direct plasma oxidation. At the same time, the efficiency of indirect oxidation increased at elevated reactor temperatures. Additional experiments were carried out to investigate the improvement of indirect oxidation by the introduction of catalyst...

  2. Aqueous colloids of graphene oxide nanosheets by exfoliation of graphite oxide without ultrasonication

    Indian Academy of Sciences (India)

    Tian-You Zhang; Dong Zhang

    2011-02-01

    Aqueous colloids of graphene oxide nanosheets were produced from exfoliation of graphite oxide using a magnetic stirrer and heat treatment in the absence of ultrasonication. Laser particle measurements showed that the particle size distribution of graphite oxide dispersed in de-ionized water was significantly influenced by treatment time indicating an increasing exfoliation level of graphite oxide. Atomic force microscopy (AFM) confirmed that single-layer graphene oxide nanosheets with a thickness of ∼1 nm were obtained after 72 h of magnetic stirring and heat treatment. These findings provide a new methodology for preparation of single-layer graphene oxide nanosheet colloids.

  3. Interaction mechanisms between slurry coatings and solid oxide fuel cell interconnect alloys during high temperature oxidation

    DEFF Research Database (Denmark)

    Persson, Åsa Helen; Mikkelsen, L.; Hendriksen, P.V.;

    2012-01-01

    Six different coatings consisting of fluorite-, corundum-, spinel- or perovskite-type oxides were deposited on a Fe22Cr alloy (Crofer 22APU) and oxidized at 900°C in moisturized air.Five of the coatings prevented break-away oxidation otherwise observed for the uncoated alloy, and the parabolic...... oxidation rate constant was reduced with 50–90% of that for uncoated alloy. One coating consisting of MnCo2O4 did not significantly affect the oxidation rate of the alloy, and just as for uncoated samples break-away oxidation occurred for MnCo2O4 coated samples. The interaction mechanisms between...

  4. Compositional Analysis of the High Molecular Weight Ethylene Oxide Propylene Oxide Copolymer by MALDI Mass Spectrometry

    CERN Document Server

    Houshia, Orwa Jaber

    2012-01-01

    The composition of narrow distribution poly ethylene oxide-propylene oxide copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide copolymer produced oligomers separated by 14 Da. The average resolving power over the entire spectrum was 28,000. Approximately 448 isotopically resolved peaks representing about 56 oligomers are identified. Although agreement between experimental and calculated isotopic distributions was strong, the compositional assignment was difficult. This is due to the large number of possible isobaric components. The purpose of this research is to resolve and study the composition of high mass copolymer such as ethylene oxide-propylene oxide.

  5. Selective oxidation of isobutane on V–Mo–O mixed oxide catalysts

    Directory of Open Access Journals (Sweden)

    GHEORGHITA MITRAN

    2008-01-01

    Full Text Available Four V–Mo–O mixed metal oxides were prepared, characterized and tested for the selective oxidation of isobutane in the temperature range 350–550 °C, at atmospheric pressure. Isobutane was mainly oxidized to iso-butene and carbon oxides. The systems with low vanadium contents showed low activities but high isobutene selectivities, while the systems with high vanadium contents showed high activities with high carbon oxides selectivities. The effects of temperature, contact time and the molar ratio iso-butane to oxygen on the conversion of isobutane and the selectivity of the oxidation were studied.

  6. Oxidative refolding from inclusion bodies.

    Science.gov (United States)

    Nelson, Christopher A; Lee, Chung A; Fremont, Daved H

    2014-01-01

    This protocol describes the growth and purification of bacterial inclusion body proteins with an option to selenomethionine label the targeted protein through feedback inhibition of methionine biosynthesis in common (non-auxotrophic) strains of E. coli. The method includes solubilization of inclusion body proteins by chemical denaturation and disulfide reduction, renaturation of the solubilized material through rapid dilution by pulsed injection into refolding buffer containing arginine and a mixture of oxidized and reduced glutathione, recovery of the recombinant protein using a stirred cell concentrator, and removal of the aggregated or misfolded fraction by passage over size-exclusion chromatography. The quality of the resulting protein can be assessed by SDS-PAGE.

  7. Oxidative Stress in Cardiovascular Disease

    Directory of Open Access Journals (Sweden)

    Gábor Csányi

    2014-04-01

    Full Text Available In the special issue “Oxidative Stress in Cardiovascular Disease” authors were invited to submit papers that investigate key questions in the field of cardiovascular free radical biology. The original research articles included in this issue provide important information regarding novel aspects of reactive oxygen species (ROS-mediated signaling, which have important implications in physiological and pathophysiological cardiovascular processes. The issue also included a number of review articles that highlight areas of intense research in the fields of free radical biology and cardiovascular medicine.

  8. Poly(ethylene oxide) functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Russell Clayton

    2014-04-08

    A simple procedure is provided by which the hydroxyl termini of poly(ethylene oxide) can be appended with functional groups to a useful extent by reaction and precipitation. The polymer is dissolved in warmed toluene, treated with an excess of organic base and somewhat less of an excess of a reactive acylating reagent, reacted for several hours, then precipitated in isopropanol so that the product can be isolated as a solid, and salt byproducts are washed away. This procedure enables functionalization of the polymer while not requiring laborious purification steps such as solvent-solvent extraction or dialysis to remove undesirable side products.

  9. DISSOLUTION OF NEPTUNIUM OXIDE RESIDUES

    Energy Technology Data Exchange (ETDEWEB)

    Kyser, E

    2009-01-12

    This report describes the development of a dissolution flowsheet for neptunium (Np) oxide (NpO{sub 2}) residues (i.e., various NpO{sub 2} sources, HB-Line glovebox sweepings, and Savannah River National Laboratory (SRNL) thermogravimetric analysis samples). Samples of each type of materials proposed for processing were dissolved in a closed laboratory apparatus and the rate and total quantity of off-gas were measured. Samples of the off-gas were also analyzed. The quantity and type of solids remaining (when visible) were determined after post-dissolution filtration of the solution. Recommended conditions for dissolution of the NpO{sub 2} residues are: Solution Matrix and Loading: {approx}50 g Np/L (750 g Np in 15 L of dissolver solution), using 8 M nitric acid (HNO{sub 3}), 0.025 M potassium fluoride (KF) at greater than 100 C for at least 3 hours. Off-gas: Analysis of the off-gas indicated nitric oxide (NO), nitrogen dioxide (NO{sub 2}) and nitrous oxide (N{sub 2}O) as the only identified components. No hydrogen (H{sub 2}) was detected. The molar ratio of off-gas produced per mole of Np dissolved ranged from 0.25 to 0.4 moles of gas per mole of Np dissolved. A peak off-gas rate of {approx}0.1 scfm/kg bulk oxide was observed. Residual Solids: Pure NpO{sub 2} dissolved with little or no residue with the proposed flowsheet but the NpCo and both sweepings samples left visible solid residue after dissolution. For the NpCo and Part II Sweepings samples the residue amounted to {approx}1% of the initial material, but for the Part I Sweepings sample, the residue amounted to {approx}8 % of the initial material. These residues contained primarily aluminum (Al) and silicon (Si) compounds that did not completely dissolve under the flowsheet conditions. The residues from both sweepings samples contained minor amounts of plutonium (Pu) particles. Overall, the undissolved Np and Pu particles in the residues were a very small fraction of the total solids.

  10. Bidirectional reflectance of zinc oxide

    Science.gov (United States)

    Scott, R.

    1973-01-01

    This investigation was undertaken to determine original and useful information about the bidirection reflectance of zinc oxide. The bidirectional reflectance will be studied for the spectra between .25-2.5 microns and the hemisphere above the specimen. The following factors will be considered: (1) surface conditions; (2) specimen preparation; (3) specimen substrate, (4) polarization; (5) depolarization; (6) wavelength; and (7) angles of incident and reflection. The bidirectional reflectance will be checked by experimentally determined angular hemispherical measurements or hemispherical measurements will be used to obtain absolute bidirectional reflectance.

  11. [Nitric oxide and lipid peroxidation].

    Science.gov (United States)

    Cristol, J P; Maggi, M F; Guérin, M C; Torreilles, J; Descomps, B

    1995-01-01

    Nitric oxide (NO) is a free radical produced enzymatically in biological systems from the guanidino group of L-arginine. Its large spectrum of biological effects is achieved through chemical interactions with different targets including oxygen (O2), superoxide (O2o-) and other oxygen reactive species (ROS), transition metals and thiols. Superoxide anions and other ROS have been reported to react with NO to produce peroxynitrite anions that can decompose to form nitrogen dioxide (NO2) and hydroxyl radial (OHo). Thus, NO has been reported to have a dual effect on lipid peroxidation (prooxidant via the peroxynitrite or antioxydant via the chelation of ROS). In the present study we have investigated in different models the in vitro and in vivo action of NO on lipid peroxidation. Copper-induced LDL oxidation were used as an in vitro model. Human LDL (100 micrograms ApoB/ml) were incubated in oxygene-saturated PBS buffer in presence or absence of Cu2+ (2.5 microM) with increasing concentrations of NO donnors (sodium nitroprussiate or nitroso-glutathione). LDL oxidation was monitored continuously for conjugated diene formation (234 nm) and 4-hydroxynonenal (HNE) accumulation. Exogenous NO prevents in a dose dependent manner the progress of copper-induced oxidation. Ischaemia-reperfusion injury (I/R), characterized by an overproduction of ROS, is used as an in vivo model. Anaesthetized rats were submitted to 1 hour renal ischaemia following by 2 hours of reperfusion. Sham-operated rats (SOP) were used as control. Lipid peroxidation was evaluated by measuring the HNE accumulated in rats kidneys in presence or absence of L-arginine or D-arginine infusion. L-arginine, but not D-arginine, enhances HNE accumulation in I/R but not in SOP (< 0.050 pmol/g tissue in SOP versus 0.6 nmol/g tissue in I/R), showing that, in this experimental conditions, NO produced from L-arginine, enhances the toxicity of ROS. This study shows that the pro- or antioxydant effects of NO are different

  12. Microgravity Processing of Oxide Superconductors

    Science.gov (United States)

    Hofmeister, William H.; Bayuzick, Robert J.; Vlasse, Marcus; McCallum, William; Peters, Palmer (Technical Monitor)

    2000-01-01

    The primary goal is to understand the microstructures which develop under the nonequilibrium solidification conditions achieved by melt processing in copper oxide superconductor systems. More specifically, to define the liquidus at the Y- 1:2:3 composition, the Nd-1:2:3 composition, and several intermediate partial substitution points between pure Y-1:2:3 and Nd-1:2:3. A secondary goal has been to understand resultant solidification morphologies and pathways under a variety of experimental conditions and to use this knowledge to better characterize solidification phenomena in these systems.

  13. Theory of Copper Oxide Superconductors

    CERN Document Server

    Kamimura, Hiroshi; Shunichi Matsuno; Tsuyoshi Hamada

    2005-01-01

    This is an advanced textbook for graduate students and researchers wishing to learn about high temperature superconductivity in copper oxides, in particular the Kamimura-Suwa (K-S) model. Because a number of models have been proposed since the discovery of high temperature superconductivity by Bednorz and Müller in 1986, the book first explains briefly the historical development that led to the K-S model. It then focuses on the physical background necessary to understand the K-S model and on the basic principles behind various physical phenomena such as electronic structures, electrical, thermal and optical properties, and the mechanism of high temperature superconductivity.

  14. Preparation of Manganese Oxide Nanobelts

    Institute of Scientific and Technical Information of China (English)

    Jisen WANG; Jinquan SUN; Ying BAO; Xiufang BIAN

    2003-01-01

    Oriented nanobelts of manganese oxide have been firstly and successfully prepared by a microemulsion techniqueunder controlled circumstances. The samples were characterized by X-ray diffraction (XRD), transmission electronmicroscope (TEM). Influences of sodium chloride and annealed temperature on the synthesis of Mn3O4 nanobeltswere investigated. It was found that NaCl is the key factor to synthesize oriented Mn3O4 nanobelts and 827 K isoptimum temperature to produce fine nanobelts. Oriented growth mechanism of Mn3O4 nanobelts was discussed.

  15. Nitrous oxide in emergency medicine.

    Science.gov (United States)

    O'Sullivan, I; Benger, J

    2003-05-01

    Safe and predictable analgesia is required for the potentially painful or uncomfortable procedures often undertaken in an emergency department. The characteristics of an ideal analgesic agent are safety, predictability, non-invasive delivery, freedom from side effects, simplicity of use, and a rapid onset and offset. Newer approaches have threatened the widespread use of nitrous oxide, but despite its long history this simple gas still has much to offer. "I am sure the air in heaven must be this wonder-working gas of delight". Robert Southey, Poet (1774 to 1843)

  16. Equivalent oxide thickness scaling of Al2O3/Ge metal-oxide-semiconductor capacitors with ozone post oxidation

    Institute of Scientific and Technical Information of China (English)

    Sun Jia-Bao; Yang Zhou-Wei; Geng Yang; Lu Hong-Liang; Wu Wang-Ran; Ye Xiang-Dong; David Zhang Wei

    2013-01-01

    Aluminum-oxide films deposited as gate dielectrics on germanium (Ge) by atomic layer deposition were post oxidized in an ozone atmosphere.No additional interracial layer was detected by the high-resolution cross-sectional transmission electron microscopy and X-ray photoelectron spectroscopy measurements made after the ozone post oxidation (OPO) treatment.Decreases in the equivalent oxide thickness of the OPO-treated Al2O3/Ge MOS capacitors were confirmed.Furthermore,a continuous decrease in the gate leakage current was achieved with increasing OPO treatment time.The results can be attributed to the film quality having been improved by the OPO treatment.

  17. Sulfur-oxidizing bacteria in environmental technology.

    Science.gov (United States)

    Pokorna, Dana; Zabranska, Jana

    2015-11-01

    Hydrogen sulfide is widely known as the most undesirable component of biogas that caused not only serious sensoric and toxic problems, but also corrosion of concrete and steel structures. Many agricultural and industrial waste used in biogas production, may contain a large amount of substances that serve as direct precursors to the formation of sulfide sulfur-sources of hydrogen sulfide in the biogas. Biological desulfurization methods are currently promoted to abiotic methods because they are less expensive and do not produce undesirable materials which must be disposed of. The final products of oxidation of sulfides are no longer hazardous. Biological removal of sulfide from a liquid or gaseous phase is based on the activity of sulfur-oxidizing bacteria. They need an oxidizing agent such as an acceptor of electrons released during the oxidation of sulfides-atmospheric oxygen or oxidized forms of nitrogen. Different genera of sulfur-oxidizing bacteria and their technological application are discussed.

  18. Oxidative stability of krill oil (Euphausia superba)

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Jacobsen, Charlotte; Bruheim, I.;

    Krill oil has been reported in many studies to have high oxidative stability when evaluated by peroxide value (PV) and anisidine value (AV). However, recent studies have shown that other compounds than primary and secondary oxidation products are formed when krill oil is exposed to oxidative...... conditions. These compounds include Strecker degradation compounds and pyrroles. Some of these compounds may have antioxidative effect. Commercial scale processing of krill prior to extraction may affect the oxidative stability of krill oil. Therefore, the main objective of this study was to compare lipid...... oxidation in krill oil produced in a commercial process and krill oil carefully extracted from frozen krill in the laboratory. Krill oil was incubated at different temperatures (20, 30 and 40 oC) for 1, 2, 3, 4 and 6 weeks, under conditions of constant stirring while being exposed to air. The oxidative...

  19. Applications of Oxide Coatings in Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Sonya Calnan

    2014-03-01

    Full Text Available Metalloid and metal based oxides are an almost unavoidable component in the majority of solar cell technologies used at the time of writing this review. Numerous studies have shown increases of ≥1% absolute in solar cell efficiency by simply substituting a given layer in the material stack with an oxide. Depending on the stoichiometry and whether other elements are present, oxides can be used for the purpose of light management, passivation of electrical defects, photo-carrier generation, charge separation, and charge transport in a solar cell. In this review, the most commonly used oxides whose benefits for solar cells have been proven both in a laboratory and industrial environment are discussed. Additionally, developing trends in the use of oxides, as well as newer oxide materials, and deposition technologies for solar cells are reported.

  20. Primary atmospheric oxidation mechanism for toluene.

    Science.gov (United States)

    Baltaretu, Cristian O; Lichtman, Eben I; Hadler, Amelia B; Elrod, Matthew J

    2009-01-08

    The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique at temperatures ranging from 228 to 298 K. A major dienedial-producing pathway was detected for the first time for toluene oxidation, and glyoxal and methylglyoxal were found to be minor primary oxidation products. The results suggest that secondary oxidation processes involving dienedial and epoxide primary products are likely responsible for previous observations of glyoxal and methylglyoxal products from toluene oxidation. Because the dienedial-producing pathway is a null cycle for tropospheric ozone production and glyoxal and methylglyoxal are important secondary organic aerosol precursors, these new findings have important implications for the modeling of toluene oxidation in the atmosphere.