WorldWideScience

Sample records for bacterial sulfur globules

  1. X-Ray Absorption Spectroscopy as a Probe of Microbial Sulfur Biochemistry: the Nature of Bacterial Sulfur Globules Revisited ▿

    OpenAIRE

    George, Graham N.; Gnida, Manuel; Dennis A Bazylinski; Prince, Roger C.; Pickering, Ingrid J.

    2008-01-01

    The chemical nature of the sulfur in bacterial sulfur globules has been the subject of controversy for a number of years. Sulfur K-edge X-ray absorption spectroscopy (XAS) is a powerful technique for probing the chemical forms of sulfur in situ, but two groups have used it with very different conclusions. The root of the controversy lies with the different detection strategies used by the two groups, which result in very different spectra. This paper seeks to resolve the controversy. We exper...

  2. In Situ Analysis of Sulfur Species in Sulfur Globules Produced from Thiosulfate by Thermoanaerobacter sulfurigignens and Thermoanaerobacterium thermosulfurigenes▿ †

    OpenAIRE

    Lee, Yong-Jin; Prange, Alexander; Lichtenberg, Henning; Rohde, Manfred; Dashti, Mona; Wiegel, Juergen

    2007-01-01

    The Firmicutes Thermoanaerobacter sulfurigignens and Thermoanaerobacterium thermosulfurigenes convert thiosulfate, forming sulfur globules inside and outside cells. X-ray absorption near-edge structure analysis revealed that the sulfur consisted mainly of sulfur chains with organic end groups similar to sulfur formed in purple sulfur bacteria, suggesting the possibility that the process of sulfur globule formation by bacteria is an ancient feature.

  3. 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

    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 dsrU/CT...... (sqrB/CT0117 and sqrD/CT1087) were deleted, exhibited a decreased sulfide oxidation rate (~50% of wild type), yet formation and consumption of sulfur globules were not affected. The observation that mutants lacking the DSR system maintain efficient growth, suggests that the DSR system is dispensable...... in environments with sufficient sulfide concentrations. Thus, the DSR system in GSB may have been acquired by horizontal gene transfer in a response to a need for improved substrate utilization in sulfide-limiting habitats....

  4. Sub-micrometer-scale mapping of magnetite crystals and sulfur globules in magnetotactic bacteria using confocal Raman micro-spectrometry.

    Science.gov (United States)

    Eder, Stephan H K; Gigler, Alexander M; Hanzlik, Marianne; Winklhofer, Michael

    2014-01-01

    The ferrimagnetic mineral magnetite Fe3O4 is biomineralized by magnetotactic microorganisms and a diverse range of animals. Here we demonstrate that confocal Raman microscopy can be used to visualize chains of magnetite crystals in magnetotactic bacteria, even though magnetite is a poor Raman scatterer and in bacteria occurs in typical grain sizes of only 35-120 nm, well below the diffraction-limited optical resolution. When using long integration times together with low laser power (greigite (cubic Fe3S4; Raman lines of 253 and 351 cm(-1)) is often found in the Deltaproteobacteria class, it is not present in our samples. In intracellular sulfur globules of Candidatus Magnetobacterium bavaricum (Nitrospirae), we identified the sole presence of cyclo-octasulfur (S8: 151, 219, 467 cm(-1)), using green (532 nm), red (638 nm) and near-infrared excitation (785 nm). The Raman-spectra of phosphorous-rich intracellular accumulations point to orthophosphate in magnetic vibrios and to polyphosphate in magnetic cocci. Under green excitation, the cell envelopes are dominated by the resonant Raman lines of the heme cofactor of the b or c-type cytochrome, which can be used as a strong marker for label-free live-cell imaging of bacterial cytoplasmic membranes, as well as an indicator for the redox state. PMID:25233081

  5. Sub-micrometer-scale mapping of magnetite crystals and sulfur globules in magnetotactic bacteria using confocal Raman micro-spectrometry.

    Directory of Open Access Journals (Sweden)

    Stephan H K Eder

    Full Text Available The ferrimagnetic mineral magnetite Fe3O4 is biomineralized by magnetotactic microorganisms and a diverse range of animals. Here we demonstrate that confocal Raman microscopy can be used to visualize chains of magnetite crystals in magnetotactic bacteria, even though magnetite is a poor Raman scatterer and in bacteria occurs in typical grain sizes of only 35-120 nm, well below the diffraction-limited optical resolution. When using long integration times together with low laser power (<0.25 mW to prevent laser induced damage of magnetite, we can identify and map magnetite by its characteristic Raman spectrum (303, 535, 665 cm(-1 against a large autofluorescence background in our natural magnetotactic bacteria samples. While greigite (cubic Fe3S4; Raman lines of 253 and 351 cm(-1 is often found in the Deltaproteobacteria class, it is not present in our samples. In intracellular sulfur globules of Candidatus Magnetobacterium bavaricum (Nitrospirae, we identified the sole presence of cyclo-octasulfur (S8: 151, 219, 467 cm(-1, using green (532 nm, red (638 nm and near-infrared excitation (785 nm. The Raman-spectra of phosphorous-rich intracellular accumulations point to orthophosphate in magnetic vibrios and to polyphosphate in magnetic cocci. Under green excitation, the cell envelopes are dominated by the resonant Raman lines of the heme cofactor of the b or c-type cytochrome, which can be used as a strong marker for label-free live-cell imaging of bacterial cytoplasmic membranes, as well as an indicator for the redox state.

  6. Bacterial iron-sulfur cluster sensors in mammalian pathogens

    Science.gov (United States)

    Miller, Halie K.; Auerbuch, Victoria

    2015-01-01

    Iron-sulfur clusters act as important cofactors for a number of transcriptional regulators in bacteria, including many mammalian pathogens. The sensitivity of iron-sulfur clusters to iron availability, oxygen tension, and reactive oxygen and nitrogen species enables bacteria to use such regulators to adapt their gene expression profiles rapidly in response to changing environmental conditions. In this review, we discuss how the [4Fe-4S] or [2Fe-2S] cluster-containing regulators FNR, Wbl, aconitase, IscR, NsrR, SoxR, and AirSR contribute to bacterial pathogenesis through control of both metabolism and classical virulence factors. In addition, we briefly review mammalian iron homeostasis as well as oxidative/nitrosative stress to provide context for understanding the function of bacterial iron-sulfur cluster sensors in different niches within the host. PMID:25738802

  7. Biologically produced sulfur

    NARCIS (Netherlands)

    Kleinjan, W.E.; Keizer, de A.; Janssen, A.J.H.

    2003-01-01

    Sulfur compound oxidizing bacteria produce sulfur as an intermediate in the oxidation of hydrogen sulfide to sulfate. Sulfur produced by these microorganisms can be stored in sulfur globules, located either inside or outside the cell. Excreted sulfur globules are colloidal particles which are stabil

  8. Isolation and characterization of organic-sulfur degradation bacterial strain

    Institute of Scientific and Technical Information of China (English)

    YANG Yu; DIAO Meng-xue; SHI Wu-yang; LI Li; DAI Qin-yun; QIU Guan-zhou

    2007-01-01

    A bacterial strain that was capable of degrading organic sulfur (dibenzothiophene) was isolated by enrichment techniques from the petroleum-contaminated soil collected from Zhongyuan Oil Field. The strain is named ZYX and is gram-positive.This strain undergoes bacilus-coccus morphological change, and forms yellow-pigment glossy circular colonies with 1.5 mm in diameter on average after 2 d incubation on Luria-Bertani(LB) plates. The full-length of 16S rDNA sequence of strain ZYX was determined and analyzed. Strain ZYX is found most relative with the genus of Arthrobacter. The similarity values between ZYX and Arthrobacter sp. P2 is 99.53%. The main morphological, biochemical and physiological features of strain ZYX accord with those of Arthrobacter. It is found that the optimal initial pH for growth is about 7.0, and the optimal concentration of dibenzothiophene(DBT)for growth is 0.10 g/L. Additionally, the results show that the best carbon source and nitrogen source are glycerol and glutamine,respectively.

  9. Antagonistic Activities of Purple Non-sulfur Bacterial Extracts Against Antibiotic Resistant Vibrio sp.

    OpenAIRE

    Chandrasekaran, R.; Ashok Kumar, G. V.

    2011-01-01

    Solvent extracts of native purple non-sulfur bacterial (PNSB) isolates from the effluents of brackish shrimp culture ponds, near Nagapattinam coast (South India) were evaluated for antibacterial activity by the disc diffusion method. Best results were shown by the chloroform extracts against oxytetracycline resistant Vibrio harveyi and Vibrio fischerii. Among the purple non-sulfur bacterial isolates, Rhodobacter sphaeroides, showed maximum antagonistic activity. The findings suggest that the...

  10. Sulfur cycling and metabolism of phototrophic and filamentous sulfur bacteria

    Science.gov (United States)

    Guerrero, R.; Brune, D.; Poplawski, R.; Schmidt, T. M.

    1985-01-01

    Phototrophic sulfur bacteria taken from different habitate (Alum Rock State Park, Palo Alto salt marsh, and Big Soda Lake) were grown on selective media, characterized by morphological and pigment analysis, and compared with bacteria maintained in pure culture. A study was made of the anaerobic reduction of intracellular sulfur globules by a phototrophic sulfur bacterium (Chromatium vinosum) and a filamentous aerobic sulfur bacterium (Beggiatoa alba). Buoyant densities of different bacteria were measured in Percoll gradients. This method was also used to separate different chlorobia in mixed cultures and to assess the relative homogeneity of cultures taken directly or enriched from natural samples (including the purple bacterial layer found at a depth of 20 meters at Big Soda Lake.) Interactions between sulfide oxidizing bacteria were studied.

  11. Antagonistic Activities of Purple Non-sulfur Bacterial Extracts Against Antibiotic Resistant Vibrio sp.

    Directory of Open Access Journals (Sweden)

    Chandrasekaran, R.

    2011-01-01

    Full Text Available Solvent extracts of native purple non-sulfur bacterial (PNSB isolates from the effluents of brackish shrimp culture ponds, near Nagapattinam coast (South India were evaluated for antibacterial activity by the disc diffusion method. Best results were shown by the chloroform extracts against oxytetracycline resistant Vibrio harveyi and Vibrio fischerii. Among the purple non-sulfur bacterial isolates, Rhodobacter sphaeroides, showed maximum antagonistic activity. The findings suggest that the antagonistic extracts from Rba. sphaeroides could be used as an effective antibiotic in controlling Vibrio spp., in aquaculture systems.

  12. Novel bacterial sulfur oxygenase reductases from bioreactors treating gold-bearing concentrates

    DEFF Research Database (Denmark)

    Chen, Z-W; Liu, Y-Y; Wu, J-F;

    2007-01-01

    The microbial community and sulfur oxygenase reductases of metagenomic DNA from bioreactors treating gold-bearing concentrates were studied by 16S rRNA library, real-time polymerase chain reaction (RT-PCR), conventional cultivation, and molecular cloning. Results indicated that major bacterial......) of bacteria and archaea were 4.59 x 10(9) and 6.68 x 10(5), respectively. Bacterial strains representing Acidithiobacillus, Leptospirillum, and Sulfobacillus were isolated from the bioreactors. To study sulfur oxidation in the reactors, pairs of new PCR primers were designed for the detection of sulfur...... oxygenase reductase (SOR) genes. Three sor-like genes, namely, sor (Fx), sor (SA), and sor (SB) were identified from metagenomic DNAs of the bioreactors. The sor (Fx) is an inactivated SOR gene and is identical to the pseudo-SOR gene of Ferroplasma acidarmanus. The sor (SA) and sor (SB) showed...

  13. Bacterial sulfur cycle shapes microbial communities in surface sediments of an ultramafic hydrothermal vent field

    DEFF Research Database (Denmark)

    Schauer, Regina; Røy, Hans; Augustin, Nico;

    2011-01-01

    RNA sequence analysis, was characterized by the capability to metabolize sulfur components. High sulfate reduction rates as well as sulfide depleted in (34)S further confirmed the importance of the biogeochemical sulfur cycle. In contrast, methane was found to be of minor relevance for microbial life in mat......, these sediments were investigated in order to determine biogeochemical processes and key organisms relevant for primary production. Temperature profiling at two mat-covered sites showed a conductive heating of the sediments. Elemental sulfur was detected in the overlying mat and metal-sulfides in the upper......-covered surface sediments. Our data indicate that in conductively heated surface sediments microbial sulfur cycling is the driving force for bacterial biomass production although ultramafic-hosted systems are characterized by fluids with high levels of dissolved methane and hydrogen....

  14. 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.

  15. Controls on stable sulfur isotope fractionation during bacterial sulfate reduction in Arctic sediments

    DEFF Research Database (Denmark)

    Bruchert, V.; Knoblauch, C.; Jørgensen, BB

    2001-01-01

    Sulfur isotope fractionation experiments during bacterial sulfate reduction were performed with recently isolated strains of cold-adapted sulfate-reducing bacteria from Arctic marine sediments with year-round temperatures below 2 degreesC. The bacteria represent quantitatively important members...... parts per thousand and 8 parts per thousand above 25 degreesC, respectively. In absence of significant differences in sulfate reduction rates in the high and low temperature range, respectively, we infer that different genera of sulfate-reducing bacteria dominate the sulfate-reducing bacterial community...

  16. Anomalous Diffusion in Fractal Globules

    Science.gov (United States)

    Tamm, M. V.; Nazarov, L. I.; Gavrilov, A. A.; Chertovich, A. V.

    2015-05-01

    The fractal globule state is a popular model for describing chromatin packing in eukaryotic nuclei. Here we provide a scaling theory and dissipative particle dynamics computer simulation for the thermal motion of monomers in the fractal globule state. Simulations starting from different entanglement-free initial states show good convergence which provides evidence supporting the existence of a unique metastable fractal globule state. We show monomer motion in this state to be subdiffusive described by ⟨X2(t )⟩˜tαF with αF close to 0.4. This result is in good agreement with existing experimental data on the chromatin dynamics, which makes an additional argument in support of the fractal globule model of chromatin packing.

  17. Bacterial-type oxygen detoxification and iron-sulfur cluster assembly in amoebal relict mitochondria.

    Science.gov (United States)

    Maralikova, Barbora; Ali, Vahab; Nakada-Tsukui, Kumiko; Nozaki, Tomoyoshi; van der Giezen, Mark; Henze, Katrin; Tovar, Jorge

    2010-03-01

    The assembly of vital reactive iron-sulfur (Fe-S) cofactors in eukaryotes is mediated by proteins inherited from the original mitochondrial endosymbiont. Uniquely among eukaryotes, however, Entamoeba and Mastigamoeba lack such mitochondrial-type Fe-S cluster assembly proteins and possess instead an analogous bacterial-type system acquired by lateral gene transfer. Here we demonstrate, using immunomicroscopy and biochemical methods, that beyond their predicted cytosolic distribution the bacterial-type Fe-S cluster assembly proteins NifS and NifU have been recruited to function within the relict mitochondrial organelles (mitosomes) of Entamoeba histolytica. Both Nif proteins are 10-fold more concentrated within mitosomes compared with their cytosolic distribution suggesting that active Fe-S protein maturation occurs in these organelles. Quantitative immunoelectron microscopy showed that amoebal mitosomes are minute but highly abundant cellular structures that occupy up to 2% of the total cell volume. In addition, protein colocalization studies allowed identification of the amoebal hydroperoxide detoxification enzyme rubrerythrin as a mitosomal protein. This protein contains functional Fe-S centres and exhibits peroxidase activity in vitro. Our findings demonstrate the role of analogous protein replacement in mitochondrial organelle evolution and suggest that the relict mitochondrial organelles of Entamoeba are important sites of metabolic activity that function in Fe-S protein-mediated oxygen detoxification. PMID:19888992

  18. Dusty globules in the Crab Nebula

    CERN Document Server

    Grenman, Tiia; Elfgren, Erik

    2016-01-01

    From existing broad-band images obtained with the Hubble Space Telescope, we located 92 globules, for which we derived positions, dimensions, orientations, extinctions, masses, proper motions, and their distributions. The globules have mean radii ranging from 400 to 2000 AU and are not resolved in current infrared images of the nebula. The extinction law for dust grains in these globules matches a normal interstellar extinction law. Derived masses of dust range from 1 to 60 x 10^(-6) solar masses, and the total mass contained in globules constitute a fraction of approximately 2% or less of the total dust content of the nebula. The globules are spread over the outer part of the nebula, and a fraction of them coincide in position with emission filaments, where we find elongated globules that are aligned with these filaments. Only 10% of the globules are coincident in position with the numerous H2-emitting knots found in previous studies. All globules move outwards from the centre with transversal velocities of ...

  19. Sub-aqueous sulfur volcanos at Waiotapu, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, S.; Rickard, D. [University of Wales, Cardiff (United Kingdom). Dept. of Earth Sciences; Browne, P.; Simmons, S. [University of Auckland (New Zealand). Geothermal Institute and Geology Dept.; Jull, T. [University of Arizona, Tucson (United States). AMS Facility

    1999-12-01

    Exhumed, sub-aqueous sulfur mounds occur in the Waiotapu geothermal area, New Zealand. The extinct mounds are < 2 m high and composed of small (< 0.5 cm) hollow spheres, and occasional teardrop-shaped globules. They are located within a drained valley that until recently was connected to Lake Whangioterangi. They were formed a maximum of 820 {+-} 80 years BP as a result of the rapid sub-aqueous deposition of sulfur globules, formed when fumarolic gases discharged through molten sulfur pools. Similar globules are now being formed by the discharge of fumarolic gases through a sub-aqueous molten sulfur pool in Lake Whangioterangi. (author)

  20. Dominance of a clonal green sulfur bacterial population in a stratified lake

    DEFF Research Database (Denmark)

    Gregersen, Lea H; Habicht, Kirsten S; Peduzzi, Sandro;

    2009-01-01

    For many years, the chemocline of the meromictic Lake Cadagno, Switzerland, was dominated by purple sulfur bacteria. However, following a major community shift in recent years, green sulfur bacteria (GSB) have come to dominate. We investigated this community by performing microbial diversity...

  1. Magnetic field evolution in Bok globules

    CERN Document Server

    Wolf, S; Henning, T; Wolf, Sebastian; Launhardt, Ralf; Henning, Thomas

    2003-01-01

    Using the Submillimeter Common-User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT), we obtained submillimeter polarization maps of the Bok globules B335, CB230, and CB244 at 850micron. We find strongly aligned polarization vectors in the case of B335 and CB230, indicating a strong coupling of the magnetic field to the dust grains. Based on the distribution of the orientation and strength of the linear polarization we derive the magnetic field strengths in the envelopes of the globules. In agreement with previous submillimeter polarization measurements of Bok globules we find polarization degrees of several percent decreasing towards the centers of the cores. Furthermore, we compare the magnetic field topology with the spatial structure of the globules, in particular with the orientation of the outflows and the orientation of the nonspherical globule cores. In case of the globules B335 and CB230, the outflows are oriented almost perpendicular to the symmetry axis of the globule cores. The ...

  2. Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling

    Directory of Open Access Journals (Sweden)

    Mina eAziz

    2016-04-01

    Full Text Available Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant’s growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03 transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm. In contrast, a previously-characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against beet armyworm feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense.

  3. Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling.

    Science.gov (United States)

    Aziz, Mina; Nadipalli, Ranjith K; Xie, Xitao; Sun, Yan; Surowiec, Kazimierz; Zhang, Jin-Lin; Paré, Paul W

    2016-01-01

    Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant's growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03) transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm, BAW). In contrast, a previously characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against BAW feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense. PMID:27092166

  4. Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Bacterial Oxidation of the Sulfur Product Layer Increases the Rate of Zinc Sulfide Dissolution at High Concentrations of Ferrous Ions

    OpenAIRE

    Fowler, T. A.; Crundwell, F. K.

    1999-01-01

    This paper reports the results of leaching experiments conducted with and without Thiobacillus ferrooxidans at the same conditions in solution. The extent of leaching of ZnS with bacteria is significantly higher than that without bacteria at high concentrations of ferrous ions. A porous layer of elemental sulfur is present on the surfaces of the chemically leached particles, while no sulfur is present on the surfaces of the bacterially leached particles. The analysis of the data using the shr...

  5. Microbial interactions involving sulfur bacteria : implications for the ecology and evolution of bacterial communities

    NARCIS (Netherlands)

    Overmann, J; van Gemerden, H

    2000-01-01

    A major goal of microbial ecology is the identification and characterization of those microorganisms which govern transformations in natural ecosystems. This review summarizes our present knowledge of microbial interactions in the natural sulfur cycle. Central to the discussion is the recent progres

  6. Antiquity and evolutionary status of bacterial sulfate reduction: sulfur isotope evidence.

    Science.gov (United States)

    Schidlowski, M

    1979-09-01

    The presently available sedimentary sulfur isotope record for the Precambrian seems to allow the following conclusions: (1) In the Early Archaean, sedimentary delta 34S patterns attributable to bacteriogenic sulfate reduction are generally absent. In particular, the delta 34S spread observed in the Isua banded iron formation (3.7 x 10(9) yr) is extremely narrow and coincides completely with the respective spreads yielded by contemporaneous rocks of assumed mantle derivation. Incipient minor differentiation of the isotope pattersn notably of Archaean sulfates may be accounted for by photosynthetic sulfur bacteria rather than by sulfate reducers. (2) Isotopic evidence of dissimilatory sulfate reduction is first observed in the upper Archaean of the Aldan Shield, Siberia (approximately 3.0 x 10(9) yr) and in the Michipicoten and Woman River banded iron formations of Canada (2.75 x 10(9) yr). This narrows down the possible time of appearance of sulfate respirers to the interval 2.8--3.1 x 10(9) yr. (3) Various lines of evidence indicate that photosynthesis is older than sulfate respiration, the SO4(2-) Utilized by the first sulfate reducers deriving most probably from oxidation of reduced sulfur compounds by photosynthetic sulfur bacteria. Sulfate respiration must, in turn, have antedated oxygen respiration as O2-respiring multicellular eucaryotes appear late in the Precambrian. (4) With the bulk of sulfate in the Archaean oceans probably produced by photosynthetic sulfur bacteria, the accumulation of SO4(2-) in the ancient seas must have preceded the buildup of appreciable steady state levels of free oxygen. Hence, the occurrence of sulfate evaporites in Archaean sediments does not necessarily provide testimony of oxidation weathering on the ancient continents and, consequently, of the existence of an atmospheric oxygen reservoir.

  7. A mechanism for bacterial transformation of dimethylsulfide to dimethylsulfoxide: a missing link in the marine organic sulfur cycle.

    Science.gov (United States)

    Lidbury, Ian; Kröber, Eileen; Zhang, Zhidong; Zhu, Yijun; Murrell, J Colin; Chen, Yin; Schäfer, Hendrik

    2016-09-01

    The volatile organosulfur compound, dimethylsulfide (DMS), plays an important role in climate regulation and global sulfur biogeochemical cycles. Microbial oxidation of DMS to dimethylsulfoxide (DMSO) represents a major sink of DMS in surface seawater, yet the underlying molecular mechanisms and key microbial taxa involved are not known. Here, we reveal that Ruegeria pomeroyi, a model marine heterotrophic bacterium, can oxidize DMS to DMSO using trimethylamine monooxygenase (Tmm). Purified Tmm oxidizes DMS to DMSO at a 1:1 ratio. Mutagenesis of the tmm gene in R. pomeroyi completely abolished DMS oxidation and subsequent DMSO formation. Expression of Tmm and DMS oxidation in R. pomeroyi is methylamine-dependent and regulated at the post-transcriptional level. Considering that Tmm is present in approximately 20% of bacterial cells inhabiting marine surface waters, particularly the marine Roseobacter clade and the SAR11 clade, our observations contribute to a mechanistic understanding of biological DMSO production in surface seawater. PMID:27114231

  8. Effective bioleaching of chromium in tannery sludge with an enriched sulfur-oxidizing bacterial community.

    Science.gov (United States)

    Zeng, Jing; Gou, Min; Tang, Yue-Qin; Li, Guo-Ying; Sun, Zhao-Yong; Kida, Kenji

    2016-10-01

    In this study, a sulfur-oxidizing community was enriched from activated sludge generated in tannery wastewater treatment plants. Bioleaching of tannery sludge containing 0.9-1.2% chromium was investigated to evaluate the effectiveness of the enriched community, the effect of chromium binding forms on bioleaching efficiency, and the dominant microbes contributing to chromium bioleaching. Sludge samples inoculated with the enriched community presented 79.9-96.8% of chromium leaching efficiencies, much higher than those without the enriched community. High bioleaching efficiencies of over 95% were achieved for chromium in reducible fraction, while 60.9-97.9% were observed for chromium in oxidizable and residual fractions. Acidithiobacillus thiooxidans, the predominant bacteria in the enriched community, played an important role in bioleaching, whereas some indigenous heterotrophic species in sludge might have had a supporting role. The results indicated that A. thiooxidans-dominant enriched microbial community had high chromium bioleaching efficiency, and chromium binding forms affected the bioleaching performance.

  9. Globules of annealed amphiphilic copolymers: Surface structure and interactions

    Science.gov (United States)

    Jarkova, E.; Johner, A.; Maresov, E. A.; Semenov, A. N.

    2006-12-01

    A mean-field theory of globules of random amphiphilic copolymers in selective solvents is developed for the case of an annealed copolymer sequence: each unit can be in one of two states, H (insoluble) or P (soluble or less insoluble). The study is focussed on the regime when H and P units tend to form long blocks, and when P units dominate in the dilute phase, but are rare in the globule core. A first-order coil-to-globule transition is predicted at some T = Tcg. The globule core density at the transition point increases as the affinity of P units to the solvent, tildeɛ, is increased. Two collapse transitions, coil → “loose” globule and “loose” globule → “dense” globule, are predicted if tildeɛ is high enough and P units are marginally soluble or weakly insoluble. H and P concentration profiles near the globule surface are obtained and analyzed in detail. It is shown that the surface excess of P units rises as tildeɛ is increased. The surface tension decreases in parallel. Considering the interaction between close enough surfaces of two globules, we show that they always attract each other at a complete equilibrium. It is pointed out, however, that such equilibrium may be difficult to reach, so that partially equilibrium structures (defined by the condition that a chain forming one globule does not penetrate into the core of the other globule) are relevant. It is shown that at such partial equilibrium the interaction is repulsive, so the globules may be stabilized from aggregation. The strongest repulsion is predicted at the coil-to-globule transition point Tcg: the repulsion force decreases with the distance between the surfaces according to a power law. In the general case (apart from Tcg) the force vs. distance decay becomes exponential; the decay length ξ diverges as T → Tcg. The developed theory explains certain anomalous properties observed for globules of amphiphilic homopolymers.

  10. Bacterial ethane formation from reduced, ethylated sulfur compounds in anoxic sediments

    Science.gov (United States)

    Oremland, R.S.; Whiticar, Michael J.; Strohmaier, F.E.; Kiene, R.P.

    1988-01-01

    Trace levels of ethane were produced biologically in anoxic sediment slurries from five chemically different aquatic environments. Gases from these locations displayed biogenic characteristics, having 12C-enriched values of ??13CH4 (-62 to -86%.), ??13C2H6 (-35 to -55%.) and high ratios (720 to 140,000) of CH4 [C2H6 + C3H8]. Endogenous production of ethane by slurries was inhibited by autoclaving or by addition of the inhibitor of methanogenic bacteria, 2-bromoethanesulfonic acid (BES). Ethane formation was stimulated markedly by ethanethiol (ESH), and, to a lesser extent, by diethylsulfide (DES). Formation of methane and ethane in ESH- or DES-amended slurries was blocked by BES. Experiments showed that ethionine (or an analogous compound) could be a precursor of ESH. Ethylamine or ethanol additions to slurries caused only a minor stimulation of ethane formation. Similarly, propanethiol additions resulted in only a minor enhancement of propane formation. Cell suspensions of a methyltrophic methanogen produced traces of ethane when incubated in the presence of DES, although the organism did not grow on this compound. These results indicate that methanogenic bacteria produce ethane from the traces of ethylated sulfur compounds present in recent sediments. Preliminary estimates of stable carbon isotope fractionation associated with sediment methane formation from dimethylsulfide was about 40%., while ethane formation from DES and ESH was only 4. 6 and 6.5%., respectively. ?? 1988.

  11. Formation and Evolution of Cometary Globules

    Science.gov (United States)

    Lefloch, Bertrand

    1994-06-01

    We have conducted a detailed study both numerical and analytical of Cometary Globules (CGs), related to their possible mechanism of formation. CGs are small dense clouds commonly found in the vicinity of O--B stars in HII regions; they consist of a dense head, surrounded by a bright rim, prolonged by a diffuse tail. Recent surveys have shown that CGs are active sites of star formation. One of the models advanced to explain the formation and the evolution of CGs is the ``Radiation-Driven Implosion''(RDI): the UV flux of the O--B association ionizes the external layers of the cloud. The ionised gas expands freely into the interstellar medium while an ionization front preceded by a shock propagates into the cloud. We have built a 2-D radiative hydrodynamical code based on the piece-wise linear method. The equations of radiative transfer are solved using the "on-the-spot" approximation. The equation of state P = P(ρ,x), where x is the ionised fraction per atom, couples the equations of hydrodynamics and radiation. Gravity is neglected. We have shown that photo-ionisation alone can account for the formation and evolution of CGs. For physical parameters typical of H II regions, RDI is a two-stage process: a brief collapse phase (~105 yrs, 10% of the cloud life) followed by a transient phase during which the cloud undergoes a series of radial expansions and re-compressions, leading to the commonly observed cometary phase. The collapse phase is characterised by a double kinematic emission component, the second component being associated with shocked gas. In the cometary phase, the globule is in a quasi-hydrostatic equilibrium and has no remarkable spectroscopic signature. This phase lasts a few 105 to 106 yrs. The results of numerical simulations were confirmed by a simple analytic model and extended to the case of a non-thermal support. It appears that small- and large-scale instabilities, Rayleigh-Taylor like, similar to the surface corrugations observed in CGs of the

  12. Interstellar organic globules in meteorites and comets

    Science.gov (United States)

    Messenger, Scott; Nakamura-Messenger, Keiko; Keller, Lindsay

    Organic matter in primitive meteorites and interplanetary dust particles (IDPs) is often enriched in D/H and 15N/14N relative to terrestrial values [1-3] due to preservation of interstellar cold molecular cloud material [1]. Some meteorites and IDPs contain micrometer-size inclusions with extreme H and N isotopic anomalies [2-4], possibly due to preserved primordial organic grains. In the Tagish Lake meteorite the main carriers of these anomalies are sub-micrometer, hollow organic globules [5]. Similar objects have been observed in extracts of other chondritic meteorites, but little is known about their N and H isotopic compositions [6-8]. We have measured the H, C, and N isotopic compositions of organic globules in the Bells CM2 carbonaceous chondrite meteorite, NASA Stardust (comet Wild-2) mission samples, and in ‘cometary' IDPs. High-resolution TEM imaging and EELS show that the globules consist of structurally amorphous carbon lacking long range order or development of graphite-like domains. In almost all cases the organic globules have strong enrichments in D/H and 15N/14N. These isotopic anomalies likely resulted from low temperature ( 10 K) chemical reactions in a cold molecular cloud or at the outer regions of the protosolar nebula. These results show that microscopic organic grains were widespread constituents of the protoplanetary disk. Microscopic organic globules may thus have been a common form of prebiotic organic matter delivered to the early Earth by comets and meteorites. References: [1] Messenger S. and Walker R.M. in Astrophysical Implications of the Laboratory Study of Presolar Materials (1997), p.545. [2] Messenger S. (2000) Nature 404, 968. [3] Busemann H. et al. (2006), Science 312, 727. [4] Floss C. et al. (2004) Science 303, 1355. [5] Nakamura-Messenger K. et al. (2006) Science, 314, 1439. [6] Claus G. and Nagy B., (1961) Nature 192, 594 [7] Aoki T., Akai J., Makino K. (2003) Int Symp.Evol. of Solar System Materials 5 [8] Garvie L

  13. Mature ovarian teratoma with large floating fat globules

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hye Min; Kim, See Hyung; Hwang, Il Seon [Keimyung University School of Medicine, Dongsan Medical Center, Daegu (Korea, Republic of)

    2016-04-15

    Mature ovarian teratoma (dermoid cyst), a germ cell neoplasm, is one of the most common ovarian tumors. It is composed of derivatives of three germ cell layers. A mature ovarian teratoma with intracystic fat globules is rare. The pathogenesis on the formation of fat globules is unclear. Here we present a pathologically proven cystic ovarian teratoma with three large floating fat globules in a young woman with CT and MR findings.

  14. Hier ist wahrhaftig ein Loch im Himmel - The NGC 1999 dark globule is not a globule

    CERN Document Server

    Stanke, T; Tobin, J J; Ali, B; Megeath, S T; Krause, O; Linz, H; Allen, L; Bergin, E; Calvet, N; Di Francesco, J; Fischer, W J; Furlan, E; Hartmann, L; Henning, T; Manoj, P; Maret, S; Muzerolle, J; Myers, P C; Neufeld, D; Osorio, M; Pontoppidan, K; Poteet, C A; Watson, D M; Wilson, T

    2010-01-01

    The NGC 1999 reflection nebula features a dark patch with a size of ~10,000 AU, which has been interpreted as a small, dense foreground globule and possible site of imminent star formation. We present Herschel PACS far-infrared 70 and 160mum maps, which reveal a flux deficit at the location of the globule. We estimate the globule mass needed to produce such an absorption feature to be a few tenths to a few Msun. Inspired by this Herschel observation, we obtained APEX LABOCA and SABOCA submillimeter continuum maps, and Magellan PANIC near-infrared images of the region. We do not detect a submillimer source at the location of the Herschel flux decrement; furthermore our observations place an upper limit on the mass of the globule of ~2.4x10^-2 Msun. Indeed, the submillimeter maps appear to show a flux depression as well. Furthermore, the near-infrared images detect faint background stars that are less affected by extinction inside the dark patch than in its surroundings. We suggest that the dark patch is in fac...

  15. Cytoplasmic Sulfurtransferases in the Purple Sulfur Bacterium Allochromatium vinosum: Evidence for Sulfur Transfer from DsrEFH to DsrC

    OpenAIRE

    Yvonne Stockdreher; Venceslau, Sofia S.; Michaele Josten; Hans-Georg Sahl; Pereira, Inês A. C.; Christiane Dahl

    2012-01-01

    While the importance of sulfur transfer reactions is well established for a number of biosynthetic pathways, evidence has only started to emerge that sulfurtransferases may also be major players in sulfur-based microbial energy metabolism. Among the first organisms studied in this regard is the phototrophic purple sulfur bacterium Allochromatium vinosum. During the oxidation of reduced sulfur species to sulfate this Gammaproteobacterium accumulates sulfur globules. Low molecular weight organi...

  16. Organic matter heterogeneities in 2.72 Ga stromatolites: Alteration versus preservation by sulfur incorporation

    Science.gov (United States)

    Lepot, Kevin; Benzerara, Karim; Rividi, Nicolas; Cotte, Marine; Brown, Gordon E., Jr.; Philippot, Pascal

    2009-11-01

    The stromatolites of the weakly metamorphosed 2.72 Ga Tumbiana Formation present abundant organic globules that resemble in size, shape and distribution the microorganisms observed in modern stromatolites. In order to evaluate the significance of these cell-like organic materials, we characterized organic matter in-situ down to the nanoscale using a combination of Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman microspectroscopy, scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). These analyses revealed the occurrence of two distinct types of organic matter forming μm-scale textural and chemical heterogeneities distributed in distinct mineralogical laminae of the stromatolites. Type A organic matter, which is by far the most abundant, consists of sulfur-poor organic matter that is located in mud-type laminae at grain boundaries, mostly in association with silicate minerals. In contrast, Type B organic matter is rare and preserved as inclusions in the core of calcite grains forming laminates. It occurs as micrometer-sized cell-like globules containing variable amounts of organic sulfur likely in the form of thiophenes. Different scenarios may account for these compositional heterogeneities in the kerogen. Based on textural and compositional analogies with modern stromatolites, it is argued that Type B sulfur-rich globules may represent microbial cells protected by mineral encapsulation and selectively preserved through polymerization by early diagenetic sulfurization. In modern sediments, this reaction is fuelled by bacterial sulfate reduction (BSR). This metabolism has been widely considered as a major driver in modern stromatolites calcification and could thus have played an important role in the formation of the Tumbiana Formation stromatolites. In contrast, Type A sulfur-poor organic matter corresponds to either fossil extracellular polymer substances (EPS) or recondensed kerogen

  17. Interactions between milk fat globules and green tea catechins.

    Science.gov (United States)

    Rashidinejad, Ali; Birch, E John; Everett, David W

    2016-05-15

    The determination of putative chemical interactions between the milk fat globule membrane and green tea catechins provided useful information about the role of milk fat globules (MFGs) in high-fat dairy systems, such as cheese, and containing bioactive compounds, such as tea catechins. Catechins from green tea (125-1,000 ppm), including (+)-catechin, (-)-epigallocatechin gallate, and green tea extract were added to washed MFGs to examine possible interactions. The addition of catechins gave a significant change in the size and ζ-potential of MFGs. The recovery of different catechins from the milk fat globule suspensions was found to vary, suggesting selective association with the milk fat globule membranes. The interactions were further investigated using transmission electron microscopy and Fourier transform infra-red spectroscopy. It is suggested that catechins are localised in association with milk fat globule membrane domains as they contain both hydrophobic and hydrophilic moieties with potential points of molecular interaction.

  18. Fractal Globules: A New Approach to Artificial Molecular Machines

    Science.gov (United States)

    Avetisov, Vladik A.; Ivanov, Viktor A.; Meshkov, Dmitry A.; Nechaev, Sergei K.

    2014-01-01

    The over-damped relaxation of elastic networks constructed by contact maps of hierarchically folded fractal (crumpled) polymer globules was investigated in detail. It was found that the relaxation dynamics of an anisotropic fractal globule is very similar to the behavior of biological molecular machines like motor proteins. When it is perturbed, the system quickly relaxes to a low-dimensional manifold, M, with a large basin of attraction and then slowly approaches equilibrium, not escaping M. Taking these properties into account, it is suggested that fractal globules, even those made by synthetic polymers, are artificial molecular machines that can transform perturbations into directed quasimechanical motion along a defined path. PMID:25418305

  19. Gypsum amendment to rice paddy soil stimulated bacteria involved in sulfur cycling but largely preserved the phylogenetic composition of the total bacterial community.

    Science.gov (United States)

    Wörner, Susanne; Zecchin, Sarah; Dan, Jianguo; Todorova, Nadezhda Hristova; Loy, Alexander; Conrad, Ralf; Pester, Michael

    2016-06-01

    Rice paddies are indispensable for human food supply but emit large amounts of the greenhouse gas methane. Sulfur cycling occurs at high rates in these water-submerged soils and controls methane production, an effect that is increased by sulfate-containing fertilizers or soil amendments. We grew rice plants until their late vegetative phase with and without gypsum (CaSO4 ·2H2 O) amendment and identified responsive bacteria by 16S rRNA gene amplicon sequencing. Gypsum amendment decreased methane emissions by up to 99% but had no major impact on the general phylogenetic composition of the bacterial community. It rather selectively stimulated or repressed a small number of 129 and 27 species-level operational taxonomic units (OTUs) (out of 1883-2287 observed) in the rhizosphere and bulk soil, respectively. Gypsum-stimulated OTUs were affiliated with several potential sulfate-reducing (Syntrophobacter, Desulfovibrio, unclassified Desulfobulbaceae, unclassified Desulfobacteraceae) and sulfur-oxidizing taxa (Thiobacillus, unclassified Rhodocyclaceae), while gypsum-repressed OTUs were dominated by aerobic methanotrophs (Methylococcaceae). Abundance correlation networks suggested that two abundant (>1%) OTUs (Desulfobulbaceae, Rhodocyclaceae) were central to the reductive and oxidative parts of the sulfur cycle. PMID:27085098

  20. Utilization of 'elemental' sulfur by different phototrophic sulfur bacteria (Chromatiaceae, Ectothiorhodospiraceae): A sulfur K-edge XANES spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Franz, B; Prange, A [Niederrhein University of Applied Sciences, Competence Center for Microbiology and Biotechnology (CCMB), Rheydter Strasse 277, 41065 Moenchengladbach (Germany); Lichtenberg, H; Hormes, J [Louisiana State University, Center for Advanced Microstructures and Devices (CAMD), 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Dahl, C, E-mail: A.Prange@gmx.d [University of Bonn, Institute for Microbiology and Biotechnology, Meckenheimer Allee 168, 53115 Bonn (Germany)

    2009-11-15

    Phototrophic sulfur bacteria are generally able to use elemental sulfur as an electron donor for anoxygenic photosynthesis. Elemental sulfur is mainly a mixture of cyclo-octasulfur and polymeric sulfur. The purple sulfur bacterium Allochromatium vinosum strongly prefers the polymeric sulfur fraction showing that sulfur speciation has a strong influence on availability of elemental sulfur. X-ray absorption near edge structure (XANES) spectroscopy was used to investigate whether polymeric sulfur is also the preferred sulfur species in other purple sulfur bacteria belonging to the families Chromatiaceae and Ecothiorodospiraceae. The cultures were fed with 50 mM of elemental sulfur consisting of 68% polymeric sulfur and 30% cyclo-octasulfur. In all cultures, elemental sulfur was converted into intra- or extracellular sulfur globules, respectively, and further oxidized to sulfate. Sulfate concentrations were determined by HPLC and turbidometric assays, respectively. However, the added elemental sulfur was only partly used by the bacteria, one part of the 'elemental sulfur' remained in the cultures and was not taken up. XANES spectroscopy revealed that only the polymeric sulfur fraction was taken up by all cultures investigated. This strongly indicates that polymeric 'chain-like' sulfur is the form preferably used by phototrophic sulfur bacteria.

  1. Magnetic field dispersion in the neighbourhood of Bok Globules

    Science.gov (United States)

    Rodrigues, C. V.; Magalhães, V. de S.; Vilas-Boas, J. W.; Racca, G.; Pereyra, A.

    2014-08-01

    We performed an observational study of the relation between the interstellar magnetic field alignment and star formation in twenty (20) sky regions containing Bok Globules. The presence of young stellar objects in the globules is verified by a search of infrared sources with spectral energy distribution compatible with a pre main-sequence star. The interstellar magnetic field direction is mapped using optical polarimetry. These maps are used to estimate the dispersion of the interstellar magnetic field direction in each region from a Gaussian fit, σ B . In addition to the Gaussian dispersion, we propose a new parameter, η, to measure the magnetic field alignment that does not rely on any function fitting. Statistical tests show that the dispersion of the magnetic field direction is different in star forming globules relative to quiescent globules. Specifically, the less organised magnetic fields occur in regions having young stellar objects.

  2. Magnetic field dispersion in the neighbourhood of Bok Globules

    CERN Document Server

    Rodrigues, C V; Vilas-Boas, J W; Racca, G; Pereyra, A

    2013-01-01

    We performed an observational study of the relation between the interstellar magnetic field alignment and star formation in twenty (20) sky regions containing Bok Globules. The presence of young stellar objects in the globules is verified by a search of infrared sources with spectral energy distribution compatible with a pre main-sequence star. The interstellar magnetic field direction is mapped using optical polarimetry. These maps are used to estimate the dispersion of the interstellar magnetic field direction in each region from a Gaussian fit, sigma_B. In addition to the Gaussian dispersion, we propose a new parameter, eta, to measure the magnetic field alignment that does not rely on any function fitting. Statistical tests show that the dispersion of the magnetic field direction is different in star forming globules relative to quiescent globules. Specifically, the less organised magnetic fields occur in regions having young stellar objects.

  3. On the origins of polarization holes in Bok globules

    Science.gov (United States)

    Brauer, R.; Wolf, S.; Reissl, S.

    2016-04-01

    Context. Polarimetric observations of Bok globules frequently show a decrease in the degree of polarization towards their central dense regions (polarization holes). This behaviour is usually explained with increased disalignment owing to high density and temperature, or insufficient angular resolution of a possibly complex magnetic field structure. Aims: We investigate whether a significant decrease in polarized emission of dense regions in Bok globules is possible under certain physical conditions. For instance, we evaluate the impact of optical depth effects and various properties of the dust phase. Methods: We use radiative transfer modelling to calculate the temperature structure of an analytical Bok globule model and simulate the polarized thermal emission of elongated dust grains. For the alignment of the dust grains, we consider a magnetic field and include radiative torque and internal alignment. Results: Besides the usual explanations, selected conditions of the temperature and density distribution, the dust phase and the magnetic field are also able to significantly decrease the polarized emission of dense regions in Bok globules. Taking submm/mm grains and typical column densities of existing Bok globules into consideration, the optical depth is high enough to decrease the degree of polarization by up to ΔP ~ 10%. If limited to the densest regions, dust grain growth to submm/mm size and accumulated graphite grains decrease the degree of polarization by up to ΔP ~ 10% and ΔP ~ 5%, respectively. However, the effect of the graphite grains occurs only if they do not align with the magnetic field.

  4. On the origins of polarization holes in Bok globules

    CERN Document Server

    Brauer, R; Reissl, S

    2016-01-01

    Context. Polarimetric observations of Bok globules frequently show a decrease in the degree of polarization towards their central dense regions (polarization holes). This behaviour is usually explained with increased disalignment owing to high density and temperature, or insufficient angular resolution of a possibly complex magnetic field structure. Aims. We investigate whether a significant decrease in polarized emission of dense regions in Bok globules is possible under certain physical conditions. For instance, we evaluate the impact of optical depth effects and various properties of the dust phase. Methods. We use radiative transfer modelling to calculate the temperature structure of an analytical Bok globule model and simulate the polarized thermal emission of elongated dust grains. For the alignment of the dust grains, we consider a magnetic field and include radiative torque and internal alignment. Results. Besides the usual explanations, selected conditions of the temperature and density distribution,...

  5. Sulfur Mustard

    Science.gov (United States)

    ... Matters What's New A - Z Index Facts About Sulfur Mustard What sulfur mustard is Sulfur mustard is a type of ... it is in liquid or solid form. Where sulfur mustard is found and how it is used ...

  6. Fat globule size distribution in milk of a German buffalo herd

    OpenAIRE

    Thiele, M; Swalve, H. H.; R. Schmidt; R. Schafberg

    2010-01-01

    The volume-surface average diameter of fat globules are larger in buffalo milk than in cow milk and the volume frequency distribution in buffalo milk is more balanced. The globule size was affected by animal, stage of lactation, and test day. An interesting contrast compared to cow milk is the negative correlation between diurnal fat yield and globule size.

  7. Fat globule size distribution in milk of a German buffalo herd

    Directory of Open Access Journals (Sweden)

    M. Thiele

    2010-02-01

    Full Text Available The volume-surface average diameter of fat globules are larger in buffalo milk than in cow milk and the volume frequency distribution in buffalo milk is more balanced. The globule size was affected by animal, stage of lactation, and test day. An interesting contrast compared to cow milk is the negative correlation between diurnal fat yield and globule size.

  8. ISO Observations of Starless Bok Globules: Usually No Embedded Stars

    Science.gov (United States)

    Clemens, D.; Byrne, A.; Yun, J.; Kane, B.

    1996-01-01

    We have used ISOCAM to search the cores of a sample of small Bok globules previously classified to be mostly starless based on analysis of IRAS data. The ISO observations at 6.75microns (LW2 filter) and 14.5microns (LW3 filter) were sufficiently deep to enable detection of any low-mass hydrogen burning star or young stellar object (YSO) embedded in these globules. Of the 20 Bok globules observed by ISOCAM to date, we have reduced the data for 14. Of these, 13 show no evidence for faint red (S(sub v)(LW3) greater than S(sub v)(LW2)) stars missed by IRAS. One (CB68) does show the first mid-infrared detection of the very cool IRAS source toward this cloud, and may be a Class I or 0 YSO. We conclude, based on these new ISO observations, that Bok globules which have no IRAS sources are in general bona fide starless molecular clouds.

  9. The Bok Globule BHR 160: structure and star formation

    CERN Document Server

    Haikala, Lauri K

    2016-01-01

    BHR 160 is a virtually unstudied cometary globule within the Sco OB4 association in Scorpius at a distance of 1600pc. It is part of a system of cometary clouds which face the luminous O star HD155806. BHR 160 is special because it has an intense bright rim. We attempt to derive physical parameters for BHR 160 and to understand its structure and the origin of its peculiar bright rim. BHR 160 was mapped in the $^{12}$CO, $^{13}$CO and C$^{18}$O (2-1) and (1-0) and CS (3-2) and (2-1) lines. These data, augmented with stellar photometry derived from the ESO VVV survey, were used to derive the mass and distribution of molecular material in BHR 160 and its surroundings. Archival mid-infrared data from the WISE satellite was used to find IR excess stars in the globule and its neighbourhood. An elongated 1' by 0.6' core lies adjacent to the globule bright rim. $^{12}$CO emission covers the whole globule, but the $^{13}$CO, C$^{18}$CO and CS emission is more concentrated to the core. The $^{12}$CO line profiles indica...

  10. Molecular Composition of Carbonaceous Globules in the Bells (CM2) Chondrite

    Science.gov (United States)

    Clemett, S. J.; Nakamura-Messenger, K.; Thomas-Keprta, K. L.; Robinson, G.-A.; Mckay, D. S.

    2009-01-01

    Some meteorites and IDPs contain micron-size carbonaceous globules that are associated with significant H and/or N isotopic anomalies. This has been interpreted as indicating that such globules may contain at least partial preserved organic species formed in the outer reaches of the proto-solar disk or the presolar cold molecular cloud. Owing to their small sizes, relatively little is known about their chemical compositions. Here we present in situ measurements of aromatic molecular species in organic globules from the Bells (CM2) chondrite by microprobe two-step laser mass spectrometry. This meteorite was chosen for study because we have previously found this meteorite to contain high abundances of globules that often occur in clusters. The Bells (CM2) globules are also noteworthy for having particularly high enrichments in H-2. and N-15. In this study, we identified individual globules and clusters of globules using native UV fluorescence.

  11. Milk fat globule membrane and buttermilks: from composition to valorization

    Directory of Open Access Journals (Sweden)

    Vanderghem, C.

    2010-01-01

    Full Text Available Buttermilk, the by-product from butter manufacture, is low cost and available in large quantities but has been considered for many years as invaluable. However, over the last two decades it has gained considerable attention due to its specific composition in proteins and polar lipids from the milk fat globule membrane (MFGM. The aim of this review is to take stock of current buttermilk knowledge. Firstly, the milk fat globule membrane composition and structure are described. Secondly, buttermilk and its associated products are defined according to the milk fat making process. Structure and mean composition of these products are summarized from recent dairy research data and related to technological properties, especially the emulsifying properties provided by MFGM components. Finally, new applications are presented, leading to promising valorizations of buttermilk and its derivate products.

  12. Magnetic field geometry of the large globule CB 34

    CERN Document Server

    Das, A; Medhi, Biman J; Wolf, S

    2016-01-01

    We report the results of optical polarimetric observations of a Bok globule CB34 to study magnetic field structure on large scales ($10^5-10^6$ AU), which is combined with archival sub-mm observations to characterize the magnetic field structure of CB34 on small scales ($10^4 - 10^5$ AU). The optical polarization measurements indicate that the magnetic field in the globule is constrained to a maximum radius of $10^5$AU around the core, out to densities not smaller than $10^4$cm$^{-3}$. Our study is mainly concentrated on two submillimeter cores C1 and C2 of CB34. The direction of magnetic field of core C2 is found to be nearly perpendicular to the CO outflow direction of the globule. The magnetic field of core C1 is almost aligned with the minor axis of the core which is typical for magnetically dominated star formation models. The mean value of offset between the minor axis of core C2 and the outflow direction is found to be $14^\\circ$ which suggests that the direction of the outflow is almost aligned with t...

  13. Phototrophic bacteria and their role in the biogeochemical sulfur cycle

    Science.gov (United States)

    Trueper, H. G.

    1985-01-01

    An essential step that cannot be bypassed in the biogeochemical cycle of sulfur today is dissimilatory sulfate reduction by anaerobic bacteria. The enormous amounts of sulfides produced by these are oxidized again either anaerobically by phototrophic bacteria or aerobically by thiobacilli and large chemotrophic bacteria (Beggiatoa, Thiovulum, etc.). Phototrophic bacteria use sulfide, sulfur, thiosulfate, and sulfite as electron donors for photosynthesis. The most obvious intermediate in their oxidative sulfur metabolism is a long chain polysulfide that appears as so called sulfur globules either inside (Chromatiaceae) or outside (Ectothiorhodospiraceae, Chlorobiaceae, and some of the Rhodospirillaceae) the cells. The assimilation of sulfur compounds in phototrophic bacteria is in principle identical with that of nonphototrophic bacteria. However, the Chlorobiaceae and some of the Chromatiaceae and Rhodospirillaceae, unable to reduce sulfate, rely upon reduced sulfur for biosynthetic purposes.

  14. Mars Life? - Orange-colored Carbonate Mineral Globules

    Science.gov (United States)

    1996-01-01

    This photograph shows orange-colored carbonate mineral globules found in a meteorite, called ALH84001, believed to have once been a part of Mars. These carbonate minerals in the meteorite are believed to have been formed on Mars more than 3.6 billion years ago. Their structure and chemistry suggest that they may have been formed with the assistance of primitive, bacteria-like living organisms. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils inside of carbonate minerals such as these in the meteorite.

  15. Discovery of a Hot Corino in the Bok Globule B335

    CERN Document Server

    Imai, Muneaki; Oya, Yoko; López-Sepulcre, Ana; Watanabe, Yoshimasa; Ceccarelli, Cecilia; Lefloch, Bertrand; Caux, Emmanuel; Vastel, Charlotte; Kahane, Claudine; Sakai, Takeshi; Hirota, Tomoya; Aikawa, Yuri; Yamamoto, Satoshi

    2016-01-01

    We report the first evidence of a hot corino in a Bok globule. This is based on the ALMA observations in the 1.2 mm band toward the low-mass Class 0 protostar IRAS 19347+0727 in B335. Saturated complex organic molecules (COMs), CH$_3$CHO, HCOOCH$_3$, and NH$_2$CHO, are detected in a compact region within a few 10 au around the protostar. Additionally, CH$_3$OCH$_3$, C$_2$H$_5$OH, C$_2$H$_5$CN, and CH$_3$COCH$_3$ are tentatively detected. Carbon-chain related molecules, CCH and c-C$_3$H$_2$, are also found in this source, whose distributions are extended over a few 100 au scale. On the other hand, sulfur-bearing molecules CS, SO, and SO$_2$, have both compact and extended components. Fractional abundances of the COMs relative to H$_2$ are found to be comparable to those in known hot-corino sources. Though the COMs lines are as broad as 5-8 km s$^{-1}$, they do not show obvious rotation motion in the present observation. Thus, the COMs mainly exist in a structure whose distribution is much smaller than the synt...

  16. In situ observation of D-rich carbonaceous globules embedded in NWA 801 CR2 chondrite

    Science.gov (United States)

    Hashiguchi, Minako; Kobayashi, Sachio; Yurimoto, Hisayoshi

    2013-12-01

    Eighty-five D-rich carbonaceous particles were identified in the matrix of the NWA 801 CR2 chondrite using isotope microscopy. The occurrence of 67 D-rich carbonaceous particles was characterized using secondary electron microscopy combined with X-ray elemental mapping. The close association of H and C, and D-enrichment suggests that the D-rich carbonaceous particles correspond to organic matter. The D-rich organic particles were scattered ubiquitously throughout the matrix at a concentration of approximately 660 ppm. The morphology of the D-rich carbonaceous particles is globular up to about 1 μm in diameter and is classified into four types: ring globules, round globules, irregular-shaped globules, and globule aggregates. The ring globules are ring-shaped organic matter containing silicate and/or oxide, with or without a void in the center. This is the first report of silicate and oxide grains surrounded by D-rich organic matter. The globule aggregates are composed of several D-rich organic globules mixed with silicates. Morphology of ring globules is very similar to core-mantle grain produced in the molecular cloud or in the outer solar nebula inferring by astronomy, suggesting that the organic globules have formed by UV photolysis in the ice mantle. Silicates or oxides attached to D-rich organic globules are the first observation among chondrites so far and may be unique nature of CR2 chondrites. The hydrogen isotopic compositions of the ring globules, round globules, irregular-shaped globules, and globule aggregates are δD = 3000-4800, 2900-8100, 2700-11,000, and 2500-11,000‰, respectively. Variations of D/H ratio of these organic globules seemed to be attributed to variations of D/H ratio of the organic radicals or differences of content of the D-rich organic radicals. There are no significant differences in the hydrogen isotopic compositions among the four types of D-rich carbonaceous matter. The D-enrichments suggest that these organic globules have

  17. Proteomics of the milk fat globule membrane from Camelus dromedarius.

    Science.gov (United States)

    Saadaoui, Besma; Henry, Céline; Khorchani, Touhami; Mars, Mohamed; Martin, Patrice; Cebo, Christelle

    2013-04-01

    Camel milk has been widely characterized with regards to casein and whey proteins. However, in camelids, almost nothing is known about the milk fat globule membrane (MFGM), the membrane surrounding fat globules in milk. The purpose of this study was thus to identify MFGM proteins from Camelus dromedarius milk. Major MFGM proteins (namely, fatty acid synthase, xanthine oxidase, butyrophilin, lactadherin, and adipophilin) already evidenced in cow milk were identified in camel milk using MS. In addition, a 1D-LC-MS/MS approach led us to identify 322 functional groups of proteins associated with the camel MFGM. Dromedary MFGM proteins were then classified into functional categories using DAVID (the Database for Annotation, Visualization, and Integrated Discovery) bioinformatics resources. More than 50% of MFGM proteins from camel milk were found to be integral membrane proteins (mostly belonging to the plasma membrane), or proteins associated to the membrane. Enriched GO terms associated with MFGM proteins from camel milk were protein transport (p-value = 1.73 × 10(-14)), translation (p-value = 1.08 × 10(-11)), lipid biosynthetic process (p-value = 6.72 × 10(-10)), hexose metabolic process (p-value = 1.89 × 10(-04)), and actin cytoskeleton organization (p-value = 2.72 × 10(-04)). These findings will help to contribute to a better characterization of camel milk. Identified MFGM proteins from camel milk may also provide new insight into lipid droplet formation in the mammary epithelial cell.

  18. Star formation in the Cometary Globule Ori I-2

    CERN Document Server

    Mookerjea, B

    2009-01-01

    We investigate the young stellar population in and near the cometary globule Ori,I-2. The analysis is based on deep Nordic Optical Telescope R-band and H-alpha images, JCMT SCUBA 450 and 850 micron images combined with near-infrared 2MASS photometry and mid-infrared archival Spitzer images obtained with the IRAC (3.6, 4.5, 5.8 and 8 micron), and MIPS (24 and 70 micron) instruments. We identify a total of 125 sources within the 5'x5' region imaged by IRAC. Of these sources 87 are detected in the R-band image and 51 are detected in the 2MASS survey. The detailed physical properties of the sources are explored using a combination of near/mid-infrared color-color diagrams, greybody fitting of SEDs and an online SED fitting tool that uses a library of 2D radiation transfer based accretion models of young stellar objects with disks. Ori I-2 shows clear evidence of triggered star formation with four young low luminosity pre-main sequence stars embedded in the globule. At least two, possibly as many as four, addition...

  19. A Two Micron All Sky Survey Analysis of the Stability of Southern Bok Globules

    Science.gov (United States)

    Racca, Germán A.; Vilas-Boas, José W. S.; de la Reza, Ramiro

    2009-10-01

    We used near-infrared Two Micron All Sky Survey data to construct visual extinction maps of a sample of Southern Bok globules utilizing the NICE method. We derived radial extinction profiles of dense cores identified in the globules and analyzed their stability against gravitational collapse with isothermal Bonnor-Ebert spheres. The frequency distribution of the stability parameter (ξmax) of these cores shows that a large number of them are located in stable states, followed by an abrupt decrease of cores in unstable states. This decrease is steeper for globules with associated IRAS point sources than for starless globules. Moreover, globules in stable states have a Bonnor-Ebert temperature of T = 15 ± 6 K, while the group of critical plus unstable globules has a different temperature of T = 10 ± 3 K. Distances were estimated to all the globules studied in this work and the spectral class of the IRAS sources was calculated. No variations were found in the stability parameters of the cores and the spectral class of their associated IRAS sources. On the basis of 13CO J = 1 - 0 molecular line observations, we identified and modeled a blue-asymmetric line profile toward a globule of the sample, obtaining an upper limit infall speed of 0.25 km s-1. Based on a Ph.D. thesis made at Observatório Nacional, Rio de Janeiro, Brazil.

  20. Topological switching between an a-ß parallel protein and a remarkably helical molten globule.

    NARCIS (Netherlands)

    Nabuurs, S.M.; Westphal, A.H.; Toorn, aan den M.; Lindhoud, S.; Mierlo, van C.P.M.

    2009-01-01

    Partially folded protein species transiently exist during folding of most proteins. Often these species are molten globules, which may be on- or off-pathway to native protein. Molten globules have a substantial amount of secondary structure but lack virtually all the tertiary side-chain packing char

  1. Topological switching between an alpha-beta parallel protein and a remarkably helical molten globule.

    NARCIS (Netherlands)

    Nabuurs, S.M.; Westphal, A.H.; Toorn, M. aan den; Lindhoud, S.; Mierlo, C.P. van

    2009-01-01

    Partially folded protein species transiently exist during folding of most proteins. Often these species are molten globules, which may be on- or off-pathway to native protein. Molten globules have a substantial amount of secondary structure but lack virtually all the tertiary side-chain packing char

  2. Nitrogen, carbon, and sulfur metabolism in natural Thioploca samples

    DEFF Research Database (Denmark)

    Otte, S.; Kuenen, JG; Nielsen, LP;

    1999-01-01

    Filamentous sulfur bacteria of the genus Thioploca occur as dense mats on the continental shelf off the coast of Chile and Peru. Since little is known about their nitrogen, sulfur, and carbon metabolism, this study was undertaken to investigate their (eco)physiology. Thioploca is able to store...... internally high concentrations of sulfur globules and nitrate. It has been previously hypothesized that these large vacuolated bacteria can oxidize sulfide by reducing their internally stored nitrate. We examined this nitrate reduction by incubation experiments of washed Thioploca sheaths,vith trichomes in......) mg of protein(-1). The ammonium and sulfate production rates were not influenced by the addition of sulfide, suggesting that sulfide is first oxidized to elemental sulfur, and in a second independent step elemental sulfur is oxidized to sulfate. The average sulfide oxidation rate measured was 5 nmol...

  3. Influence of shear on globule formation in dilute solutions of flexible polymers

    Science.gov (United States)

    Radhakrishnan, Rangarajan; Underhill, Patrick T.

    2015-04-01

    Polyelectrolytes, polymers in poor solvents, polymers mixed with particles, and other systems with attractions and repulsions show formation of globules/structures in equilibrium or in flow. To study the flow behavior of such systems, we developed a simple coarse-grained model with short ranged attractions and repulsions. Polymers are represented as charged bead-spring chains and they interact with oppositely charged colloids. Neglecting hydrodynamic interactions, we study the formation of compact polymer structures called globules. Under certain conditions, increase in shear rate decreases the mean first passage time to form a globule. At other conditions, shear flow causes the globules to breakup, similar to the globule-stretch transition of polymers in poor solvents.

  4. Star Formation in the Cometary Globule Ori I-2

    Science.gov (United States)

    Mookerjea, Bhaswati; Sandell, Göran

    2009-11-01

    We investigate the young stellar population in and near the cometary globule Ori I-2. The analysis is based on deep Nordic Optical Telescope R-band and Hα images, JCMT SCUBA 450 and 850 μm images combined with near-infrared Two Micron All Sky Survey (2MASS) photometry and mid-infrared archival Spitzer images obtained with the Infrared Array Camera (IRAC; 3.6, 4.5, 5.8, and 8 μm), and MIPS (24 and 70 μm) instruments. We identify a total of 125 sources within the 5'×5' region imaged by the IRAC. Of these sources, 87 are detected in the R-band image and 51 are detected in the 2MASS. The detailed physical properties of the sources are explored using a combination of near/mid-infrared color-color diagrams, graybody fitting of spectral energy distributions (SEDs) and an online SED fitting tool that uses a library of two-dimensional radiation transfer based accretion models of young stellar objects with disks. Ori I-2 shows clear evidence of triggered star formation with four young low-luminosity pre-main-sequence (PMS) stars embedded in the globule. At least two, possibly as many as four, additional low-mass PMS objects were discovered in the field which are probably part of the young σ Orionis cluster. Among the PMS stars which have formed in the globule, MIR-54 is a young, deeply embedded Class 0/I object; MIR-51 and 52 are young Class II sources, while MIR-89 is a more evolved, heavily extincted Class II object with its apparent colors mimicking a Class 0/I object. The Class 0/I object MIR-54 coincides with a previously known IRAS source and is a strong submillimeter source. It is most likely the source for the molecular outflow and the large parsec-scale Herbig-Haro (HH) flow. However, the nearby Class II source, MIR-52, which is strong a Hα emission line star, also appears to drive an outflow approximately aligned with the outflow from MIR-54, and because of the proximity of the two outflows, either star could contribute. MIR-89 appears to excite a low

  5. The Environment and Magnetic Field of Cometary Globule CG30

    Science.gov (United States)

    Hickel, Gabriel R.; Vilas-Boas, José W. S.

    2005-09-01

    In this work, we combine observations of optical linear polarization (R band), IRAS far-infrared images and radio molecular lines to investigate the cometary globule CG30 (at IRAS Vela Shell). CG30 shows Herbig-Haro objects, molecular outflows, hosts a very young binary star and has a star formation efficiency of about 6% to 17%. Its magnetic field is important to support the CG structure and shows evidence of torsion and compression of the field lines. The quadrupolar outflow of the binary star affects the temperature of the molecular gas, and changes the degree of polarization of the dust grains in the environment of CG30. This work is based on observations collected at LNA/CNPq, Brazil and SEST/ESO, Chile.

  6. A 2MASS Analysis of the Stability of Southern Bok Globules

    CERN Document Server

    Racca, Germán A; de la Reza, Ramiro

    2008-01-01

    We used near-infrared 2MASS data to construct visual extinction maps of a sample of Southern Bok globules utilizing the NICE method. We derived radial extinction profiles of dense cores identified in the globules and analyzed their stability against gravitational collapse with isothermal Bonnor-Ebert spheres. The frequency distribution of the stability parameter xi_max of these cores shows that a large number of them are located in stable states, followed by an abrupt decrease of cores in unstable states. This decrease is steeper for globules with associated IRAS point sources than for starless globules. Moreover, globules in stable states have a Bonnor-Ebert temperature of T = 15 +- 6 K, while the group of critical plus unstable globules has a different temperature of T = 10 +- 3 K. Distances were estimated to all the globules studied in this work and the spectral class of the IRAS sources was calculated. No variations were found in the stability parameters of the cores and the spectral class of their associ...

  7. Intramedullary fat globules related to bone trauma: a new MR imaging finding

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Adelaine; Grando, Higor; Fliszar, Evelyne; Pathria, Mini; Resnick, Donald [UCSD Radiology, Musculoskeletal Division, San Diego, CA (United States); Chang, Eric Y. [UCSD Radiology, Musculoskeletal Division, San Diego, CA (United States); VA San Diego Healthcare System, Department of Radiology, San Diego, CA (United States)

    2014-12-15

    The purpose of this study is to describe intraosseous fat globules related to bone trauma that are detectable with magnetic resonance imaging (MRI), to define the relationship of this finding to fracture and bone contusion, to establish the frequency and associated findings. A proposed pathogenesis is presented. We retrospectively reviewed 419 knee MRI examinations in patients with a history of recent injury and MRI findings of fracture or bone contusion. As a control population, 268 knee MRI examinations in patients without MRI findings of recent bone injury were also reviewed. Eight of 419 (1.9 %) patients with acute or subacute knee injury with positive findings of osseous trauma on MRI demonstrated intraosseous fat globules. The mean age of patients with fat globules was greater than that of those without fat globules, and the finding was more commonly seen in women. Fat globules were hyperintense to the normal fatty marrow present elsewhere in the bone on TI-weighted imaging and had a surrounding halo of high signal intensity on fluid-sensitive imaging. Intramedullary fat globules related to bone injury visible on MRI are thought to be due to coalesced fat released by the necrosis of fatty marrow cells. The pathogenesis is supported by histologic studies of fat globules related to osteomyelitis, bone contusions and fractures. As the medullary cavity of long bones in older patients contains more fat than hematopoetic bone marrow, it is likely that this finding is more common with advancing age. (orig.)

  8. Sulfur Cycle

    Science.gov (United States)

    Hariss, R.; Niki, H.

    1985-01-01

    Among the general categories of tropospheric sulfur sources, anthropogenic sources have been quantified the most accurately. Research on fluxes of sulfur compounds from volcanic sources is now in progress. Natural sources of reduced sulfur compounds are highly variable in both space and time. Variables, such as soil temperature, hydrology (tidal and water table), and organic flux into the soil, all interact to determine microbial production and subsequent emissions of reduced sulfur compounds from anaerobic soils and sediments. Available information on sources of COS, CS2, DMS, and H2S to the troposphere in the following paragraphs are summarized; these are the major biogenic sulfur species with a clearly identified role in tropospheric chemistry. The oxidation of SO2 to H2SO4 can often have a significant impact on the acidity of precipitation. A schematic representation of some important transformations and sinks for selected sulfur species is illustrated.

  9. Milk fat globules in different dairy cattle breeds Part II: relationship to fatty acid composition

    Directory of Open Access Journals (Sweden)

    P. Verità

    2011-03-01

    Full Text Available Several studies have pointed out that even under similar environmental conditions, fatty acid composition in milk from dairy cattle of different breeds may be not homogeneous (Beaulieu and Palmquist, 2000; Palmquist et al., 1993; Bitman et al., 1995. The higher percentage of polyunsaturated fatty acids in Friesian milk, compared to that of Jerseys, may be related to the physical characteristics of fat globules (Timmen and Patton, 1988; Jensen et al., 1991; Scolozzi, 2002. Milk fat globules of heterogeneous dimensions have been described for many years (Walstra, 1969, but it is still uncertain whether a link exists between the morphometric characteristics of fat globules and their chemical composition (Polidori et al., 1995. In this study we proposed to investigate the relationship between milk fatty acid composition and the morphometric characteristics of fat globules.

  10. Genome-wide transcriptional profiling of the purple sulfur bacterium Allochromatium vinosum DSM 180T during growth on different reduced sulfur compounds.

    Science.gov (United States)

    Weissgerber, Thomas; Dobler, Nadine; Polen, Tino; Latus, Jeanette; Stockdreher, Yvonne; Dahl, Christiane

    2013-09-01

    The purple sulfur bacterium Allochromatium vinosum DSM 180(T) is one of the best-studied sulfur-oxidizing anoxygenic phototrophic bacteria, and it has been developed into a model organism for laboratory-based studies of oxidative sulfur metabolism. Here, we took advantage of the organism's high metabolic versatility and performed whole-genome transcriptional profiling to investigate the response of A. vinosum cells upon exposure to sulfide, thiosulfate, elemental sulfur, or sulfite compared to photoorganoheterotrophic growth on malate. Differential expression of 1,178 genes was observed, corresponding to 30% of the A. vinosum genome. Relative transcription of 551 genes increased significantly during growth on one of the different sulfur sources, while the relative transcript abundance of 627 genes decreased. A significant number of genes that revealed strongly enhanced relative transcription levels have documented sulfur metabolism-related functions. Among these are the dsr genes, including dsrAB for dissimilatory sulfite reductase, and the sgp genes for the proteins of the sulfur globule envelope, thus confirming former results. In addition, we identified new genes encoding proteins with appropriate subcellular localization and properties to participate in oxidative dissimilatory sulfur metabolism. Those four genes for hypothetical proteins that exhibited the strongest increases of mRNA levels on sulfide and elemental sulfur, respectively, were chosen for inactivation and phenotypic analyses of the respective mutant strains. This approach verified the importance of the encoded proteins for sulfur globule formation during the oxidation of sulfide and thiosulfate and thereby also documented the suitability of comparative transcriptomics for the identification of new sulfur-related genes in anoxygenic phototrophic sulfur bacteria. PMID:23873913

  11. The endoplasmic reticulum and casein-containing vesicles contribute to milk fat globule membrane.

    Science.gov (United States)

    Honvo-Houéto, Edith; Henry, Céline; Chat, Sophie; Layani, Sarah; Truchet, Sandrine

    2016-10-01

    During lactation, mammary epithelial cells secrete huge amounts of milk from their apical side. The current view is that caseins are secreted by exocytosis, whereas milk fat globules are released by budding, enwrapped by the plasma membrane. Owing to the number and large size of milk fat globules, the membrane surface needed for their release might exceed that of the apical plasma membrane. A large-scale proteomics analysis of both cytoplasmic lipid droplets and secreted milk fat globule membranes was used to decipher the cellular origins of the milk fat globule membrane. Surprisingly, differential analysis of protein profiles of these two organelles strongly suggest that, in addition to the plasma membrane, the endoplasmic reticulum and the secretory vesicles contribute to the milk fat globule membrane. Analysis of membrane-associated and raft microdomain proteins reinforces this possibility and also points to a role for lipid rafts in milk product secretion. Our results provide evidence for a significant contribution of the endoplasmic reticulum to the milk fat globule membrane and a role for SNAREs in membrane dynamics during milk secretion. These novel aspects point to a more complex model for milk secretion than currently envisioned.

  12. Isolated milk fat globules as substrate for lipoprotein lipase: study of factors relevant to spontaneous lipolysis in milk

    International Nuclear Information System (INIS)

    Fat globules isolated from normal and from spontaneous milk samples were compared as substrates for purified lipoprotein lipase. Only slight differences were observed. Fat globules isolated from fresh warm milk were almost resistant to lipolysis. This included globules from milk prone to spontaneous lipolysis. Cooling made the globules accessible to rapid lipolysis even if they were from normal milk. Rewarming the fat globules did not reverse the process. Maximum rate of lipolysis (after rewarming) required fat globules be stored at 100C or below for 5 to 10 h. Lipolysis at 40C usually started after a lag time of 3 to 5 h, but with fat globules from spontaneous milk the lag time was shorter. Fat globules isolated from cold milk were a poor substrate at 40C but were lipolyzed when warmed. When 125I-labeled lipase was added to fresh warm milk, some of the lipase bound to the milk fat globules but it caused little lipolysis. Binding increased after cooling, as did lipolysis. Both binding of lipase and lipolysis were impeded by the presence of skim milk. Another way to make fat globules isolated from fresh warm milk susceptible to lipolysis was to treat them with chemicals known to remove proteins

  13. Lunar sulfur

    Science.gov (United States)

    Kuck, David L.

    Ideas introduced by Vaniman, Pettit and Heiken in their 1988 Uses of Lunar Sulfur are expanded. Particular attention is given to uses of SO2 as a mineral-dressing fluid. Also introduced is the concept of using sulfide-based concrete as an alternative to the sulfur-based concretes proposed by Leonard and Johnson. Sulfur is abundant in high-Ti mare basalts, which range from 0.16 to 0.27 pct. by weight. Terrestrial basalts with 0.15 pct. S are rare. For oxygen recovery, sulfur must be driven off with other volatiles from ilmenite concentrates, before reduction. Troilite (FeS) may be oxidized to magnetite (Fe3O4) and SO2 gas, by burning concentrates in oxygen within a magnetic field, to further oxidize ilmenite before regrinding the magnetic reconcentration. SO2 is liquid at -20 C, the mean temperature underground on the Moon, at a minimum of 0.6 atm pressure. By using liquid SO2 as a mineral dressing fluid, all the techniques of terrestrial mineral separation become available for lunar ores and concentrates. Combination of sulfur and iron in an exothermic reaction, to form iron sulfides, may be used to cement grains of other minerals into an anhydrous iron-sulfide concrete. A sulfur-iron-aggregate mixture may be heated to the ignition temperature of iron with sulfur to make a concrete shape. The best iron, sulfur, and aggregate ratios need to be experimentally established. The iron and sulfur will be by-products of oxygen production from lunar minerals.

  14. 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

    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......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...... 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...

  15. A novel infant milk formula concept: Mimicking the human milk fat globule structure.

    Science.gov (United States)

    Gallier, Sophie; Vocking, Karin; Post, Jan Andries; Van De Heijning, Bert; Acton, Dennis; Van Der Beek, Eline M; Van Baalen, Ton

    2015-12-01

    Human milk (HM) provides all nutrients to support an optimal growth and development of the neonate. The composition and structure of HM lipids, the most important energy provider, have an impact on the digestion, uptake and metabolism of lipids. In HM, the lipids are present in the form of dispersed fat globules: large fat droplets enveloped by a phospholipid membrane. Currently, infant milk formula (Control IMF) contains small fat droplets primarily coated by proteins. Recently, a novel IMF concept (Concept IMF) was developed with a different lipid architecture, Nuturis(®), comprising large fat droplets with a phospholipid coating. Confocal laser scanning microscopy (CLSM), with appropriate fluorescent probes, and transmission electron microscopy were used to determine and compare the interfacial composition and structure of HM fat globules, Concept IMF fat droplets and Control IMF fat droplets. The presence of a trilayer-structured HM fat globule membrane, composed of phospholipids, proteins, glycoproteins and cholesterol, was confirmed; in addition exosome-like vesicles are observed within cytoplasmic crescents. The Control IMF fat droplets had a thick protein-only interface. The Concept IMF fat droplets showed a very thin interface composed of a mixture of phospholipids, proteins and cholesterol. Furthermore, the Concept IMF contained fragments of milk fat globule membrane, which has been suggested to have potential biological functions in infants. By mimicking more closely the structure and composition of HM fat globules, this novel IMF concept with Nuturis(®) may have metabolic and digestive properties that are more similar to HM compared to Control IMF.

  16. Influence of Mucilage Viscosity On The Globule Structure And Stability Of Certain Starch Emulsions

    Directory of Open Access Journals (Sweden)

    Uhumwangho MU

    2005-05-01

    Full Text Available A study was carried out to determine the influence of mucilage viscosity on the globule structure (i.e. size and number of certain starch emulsions. The starches investigated were cassava, potato and maize. The emulsions were prepared by mixing the starch mucilage of a predetermined concentration 4%w/v with arachis oil in the ratio 50:50, using a silverson mixer fitted with a dispersator head. The emulsions were stored at room temperature (28±20C for 7 days. Changes in globule size were monitored by photomicroscopy. Viscosities of the mucilage and those of resulting emulsions were determined using a capillary flow method. The viscosities of the emulsions expressed as time of flow (seconds, were 680 (cassava starch, 369 (potato starch and 270 (Maize starch, and for the mucilage 510 (cassava, 336 (potato and 248 (maize. The corresponding mean globule sizes of the fresh emulsions were (µm 28±6, 42±6 and 45±5 respectively. The increase in globule size during storage (measure of globule coalescence rate was 1.8±0.2µm day -1 (cassava, 3.5±0.2µm day -1 (potato and 4.6±0.3µm day -1 (maize. Thus, a higher viscosity of the dispersion medium is associated with the production of finer and more stable emulsions.

  17. Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part B--Nitrogen-, Sulfur-, and Oxygen-Containing Heterocyclic Aromatic Compounds.

    Science.gov (United States)

    Oberoi, Akashdeep Singh; Philip, Ligy; Bhallamudi, S Murty

    2015-07-01

    Present study focused on the biodegradation of various heterocyclic nitrogen, sulfur, and oxygen (NSO) compounds using naphthalene-enriched culture. Target compounds in the study were pyridine, quinoline, benzothiophene, and benzofuran. Screening studies were carried out using different microbial consortia enriched with specific polycyclic aromatic hydrocarbon (PAH) and NSO compounds. Among different microbial consortia, naphthalene-enriched culture was the most efficient consortium based on high substrate degradation rate. Substrate degradation rate with naphthalene-enriched culture followed the order pyridine > quinoline > benzofuran > benzothiophene. Benzothiophene and benzofuran were found to be highly recalcitrant pollutants. Benzothiophene could not be biodegraded when concentration was above 50 mg/l. It was observed that 2-(1H)-quinolinone, benzothiophene-2-one, and benzofuran-2,3-dione were formed as metabolic intermediates during biodegradation of quinoline, benzothiophene, and benzofuran, respectively. Quinoline-N and pyridine-N were transformed into free ammonium ions during the biodegradation process. Biodegradation pathways for various NSO compounds are proposed. Monod inhibition model was able to simulate single substrate biodegradation kinetics satisfactorily. Benzothiophene and benzofuran biodegradation kinetics, in presence of acetone, was simulated using a generalized multi-substrate model.

  18. Study of grain alignment efficiency and a distance estimate for small globule CB4

    International Nuclear Information System (INIS)

    We study the polarization efficiency (defined as the ratio of polarization to extinction) of stars in the background of the small, nearly spherical and isolated Bok globule CB4 to understand the grain alignment process. A decrease in polarization efficiency with an increase in visual extinction is noticed. This suggests that the observed polarization in lines of sight which intercept a Bok globule tends to show dominance of dust grains in the outer layers of the globule. This finding is consistent with the results obtained for other clouds in the past. We determined the distance to the cloud CB4 using near-infrared photometry (2MASS JHKS colors) of moderately obscured stars located at the periphery of the cloud. From the extinction-distance plot, the distance to this cloud is estimated to be (459 ± 85) pc. (paper)

  19. Organic Globules in the Tagish Lake Meteorite: Remnants of the Protosolar Disk

    Science.gov (United States)

    Nakamura-Messenger, Keiko; Messenger, Scott; Keller, Lindsay P.; Clemett, Simon J.; Zolensky, Michael E.

    2006-12-01

    Coordinated transmission electron microscopy and isotopic measurements of organic globules in the Tagish Lake meteorite shows that they have elevated ratios of nitrogen-15 to nitrogen-14 (1.2 to 2 times terrestrial) and of deuterium to hydrogen (2.5 to 9 times terrestrial). These isotopic anomalies are indicative of mass fractionation during chemical reactions at extremely low temperatures (10 to 20 kelvin), characteristic of cold molecular clouds and the outer protosolar disk. The globules probably originated as organic ice coatings on preexisting grains that were photochemically processed into refractory organic matter. The globules resemble cometary carbon, hydrogen, oxygen, and nitrogen (CHON) particles, suggesting that such grains were important constituents of the solar system starting materials.

  20. Study of the "Sulfur-turf" : a Community of Colorless Sulfur Bacteria Growing in Hot Spring Effluent

    OpenAIRE

    MAKI, Yonosuke

    1991-01-01

    Sulfur-turf is one of the so-called "sulfureta" which are massive aggregates of colorless sulfur bacteria. Interest in the ecological and physiological aspects of the sulfuretum has strongly increased not only due to the discovery of massive occurrence of colorless sulfur bacteria in an area of hydrothermal vents but also due to the possibility of its significant contribution to the sulfur cycle in the coastal region. Here, I review the types, habitats, and bacterial constituents of the sulfu...

  1. Tracing the evolutionary stage of Bok globules: CCS and NH3

    OpenAIRE

    Marka, C.; Schreyer, K.; Launhardt, R.; Semenov, D. A.; Henning, Th.

    2011-01-01

    We pursue the investigation of a previously proposed correlation between chemical properties and physical evolutionary stage of isolated low-mass star-forming regions. In the past, the NH3/CCS abundance ratio was suggested to be a potentially useful indicator for the evolutionary stage of cloud cores. We aim to study its applicability for isolated Bok globules. A sample of 42 Bok globules with and without signs of current star formation was searched for CCS(2-1) emission, the observations wer...

  2. Cytoplasmic sulfurtransferases in the purple sulfur bacterium Allochromatium vinosum: evidence for sulfur transfer from DsrEFH to DsrC.

    Directory of Open Access Journals (Sweden)

    Yvonne Stockdreher

    Full Text Available While the importance of sulfur transfer reactions is well established for a number of biosynthetic pathways, evidence has only started to emerge that sulfurtransferases may also be major players in sulfur-based microbial energy metabolism. Among the first organisms studied in this regard is the phototrophic purple sulfur bacterium Allochromatium vinosum. During the oxidation of reduced sulfur species to sulfate this Gammaproteobacterium accumulates sulfur globules. Low molecular weight organic persulfides have been proposed as carrier molecules transferring sulfur from the periplasmic sulfur globules into the cytoplasm where it is further oxidized via the "Dsr" (dissimilatory sulfite reductase proteins. We have suggested earlier that the heterohexameric protein DsrEFH is the direct or indirect acceptor for persulfidic sulfur imported into the cytoplasm. This proposal originated from the structural similarity of DsrEFH with the established sulfurtransferase TusBCD from E. coli. As part of a system for tRNA modification TusBCD transfers sulfur to TusE, a homolog of another crucial component of the A. vinosum Dsr system, namely DsrC. Here we show that neither DsrEFH nor DsrC have the ability to mobilize sulfane sulfur directly from low molecular weight thiols like thiosulfate or glutathione persulfide. However, we demonstrate that DsrEFH binds sulfur specifically to the conserved cysteine residue DsrE-Cys78 in vitro. Sulfur atoms bound to cysteines in DsrH and DsrF were not detected. DsrC was exclusively persulfurated at DsrC-Cys111 in the penultimate position of the protein. Most importantly, we show that persulfurated DsrEFH indeed serves as an effective sulfur donor for DsrC in vitro. The active site cysteines Cys78 of DsrE and Cys20 of DsrH furthermore proved to be essential for sulfur oxidation in vivo supporting the notion that DsrEFH and DsrC are part of a sulfur relay system that transfers sulfur from a persulfurated carrier molecule to the

  3. Sulfur cycle

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.

    Ecological Society Symposium held jointly with the Linnean Society of London. Oxford: Blackwell. Huston MH and Smith T (1987) Plant succession: Life history and competition. American Naturalist 130: 168–198. Sulfur Cycle P A Loka Bharathi, National Institute.... Vegetatio 110: 115–147. Odum EP (1969) The strategy of ecosystem development. Science 164: 262–270. Walker KR and Alberstadt LP(1975) Ecological succession asan aspect of structure in fossil communities. Paleobiology 1: 238–257. Author's personal copy S 4 O...

  4. Coil–globule transition of a polymer involved in excluded-volume interactions with macromolecules

    Energy Technology Data Exchange (ETDEWEB)

    Odagiri, Kenta [School of Network and Information, Senshu University, Kawasaki 214-8580 (Japan); Seki, Kazuhiko, E-mail: k-seki@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, Tsukuba, Ibaraki 305-8565 (Japan)

    2015-10-07

    Polymers adopt extended coil and compact globule states according to the balance between entropy and interaction energies. The transition of a polymer between an extended coil state and compact globule state can be induced by changing thermodynamic force such as temperature to alter the energy/entropy balance. Previously, this transition was theoretically studied by taking into account the excluded-volume interaction between monomers of a polymer chain using the partition function. For binary mixtures of a long polymer and short polymers, the coil-globule transition can be induced by changing the concentration of the shorter polymers. Here, we investigate the transition caused by short polymers by generalizing the partition function of the long polymer to include the excluded-volume effect of short polymers. The coil-globule transition is studied as a function of the concentration of mixed polymers by systematically varying Flory’s χ-parameters. We show that the transition is caused by the interplay between the excluded-volume interaction and the dispersion state of short polymers in the solvent. We also reveal that the same results can be obtained by combining the mixing entropy and elastic energy if the volume of a long polymer is properly defined.

  5. Topological switching between an alpha-beta parallel protein and a remarkably helical molten globule.

    Science.gov (United States)

    Nabuurs, Sanne M; Westphal, Adrie H; aan den Toorn, Marije; Lindhoud, Simon; van Mierlo, Carlo P M

    2009-06-17

    Partially folded protein species transiently exist during folding of most proteins. Often these species are molten globules, which may be on- or off-pathway to native protein. Molten globules have a substantial amount of secondary structure but lack virtually all the tertiary side-chain packing characteristic of natively folded proteins. These ensembles of interconverting conformers are prone to aggregation and potentially play a role in numerous devastating pathologies, and thus attract considerable attention. The molten globule that is observed during folding of apoflavodoxin from Azotobacter vinelandii is off-pathway, as it has to unfold before native protein can be formed. Here we report that this species can be trapped under nativelike conditions by substituting amino acid residue F44 by Y44, allowing spectroscopic characterization of its conformation. Whereas native apoflavodoxin contains a parallel beta-sheet surrounded by alpha-helices (i.e., the flavodoxin-like or alpha-beta parallel topology), it is shown that the molten globule has a totally different topology: it is helical and contains no beta-sheet. The presence of this remarkably nonnative species shows that single polypeptide sequences can code for distinct folds that swap upon changing conditions. Topological switching between unrelated protein structures is likely a general phenomenon in the protein structure universe.

  6. Enzymic characteristics of fat globule membranes from bovine colostrum and bovine milk

    Science.gov (United States)

    1977-01-01

    Fat globule membranes have been isolated from bovine colostrum and bovine milk by the dispersion of the fat in sucrose solutions at 4 degrees C and fractionation by centrifugation through discontinuous sucrose gradients. The morphology and enzymic characteristics of the separated fractions were examined. Fractions comprising a large proportion of the total extracted membrane were thus obtained having high levels of the Golgi marker enzymes UDP-galactose N- acetylglucosamine beta-4-galactosyltransferase and thiamine pyrophosphatase. A membrane-derived form of the galactosyltransferase has been solubilized from fat and purified to homogeneity. This enzyme is larger in molecular weight than previously studied soluble galactosyltransferases, but resembles in size the galactosyltransferase of lactating mammary Golgi membranes. In contrast, when fat globule membranes were prepared by traditional procedures, which involved washing the fat at higher temperatures, before extraction, galactosyltransferase was not present in the membranes, having been released into supernatant fractions, When the enzyme released by this procedure was partially purified and examined by gel filtration, it was found to be of a degraded form resembling in size the soluble galactosyltransferase of milk. The release is therefore attributed to the action of proteolytic enzymes. Our observations contrast with previous biochemical studies which suggested that Golgi membranes do not contribute to the milk fat globule membrane. They are, however, consistent with electron microscope studies of the fat secretion process, which indicate that secretory vesicle membranes, derived from the Golgi apparatus, may provide a large proportion of the fat globule membrane. PMID:402369

  7. Mechanical unfolding of a homopolymer globule studied by self-consistent field modeling

    NARCIS (Netherlands)

    Polotsky, A.A.; Charlaganov, M.; Leermakers, F.A.M.; Daoud, M.; Borisov, O.V.; Birshtein, T.M.

    2009-01-01

    We present results of numerical self-consistent field (SCF) calculations for the equilibrium mechanical unfolding of a globule formed by a single flexible polymer chain collapsed in a poor solvent. In accordance with earlier scaling theory and stochastic dynamics simulations findings we have identif

  8. Globules and pillars seen in the [CII] 158 micron line with SOFIA

    CERN Document Server

    Schneider, N; Tremblin, P; Hennemann, M; Minier, V; Hill, T; Comerón, F; Requena-Torres, M A; Kraemer, K E; Simon, R; Röllig, M; Stutzki, J; Djupvik, A A; Zinnecker, H; Marston, A; Csengeri, T; Cormier, D; Lebouteiller, V; Audit, E; Motte, F; Bontemps, S; Sandell, G; Allen, L; Megeath, T; Gutermuth, R A

    2012-01-01

    Molecular globules and pillars are spectacular features, found only in the interface region between a molecular cloud and an HII-region. Impacting Far-ultraviolet (FUV) radiation creates photon dominated regions (PDRs) on their surfaces that can be traced by typical cooling lines. With the GREAT receiver onboard SOFIA we mapped and spectrally resolved the [CII] 158 micron atomic fine-structure line and the highly excited 12CO J=11-10 molecular line from three objects in Cygnus X (a pillar, a globule, and a strong IRAS source). We focus here on the globule and compare our data with existing Spitzer data and recent Herschel Open-Time PACS data. Extended [CII] emission and more compact CO-emission was found in the globule. We ascribe this emission mainly to an internal PDR, created by a possibly embedded star-cluster with at least one early B-star. However, external PDR emission caused by the excitation by the Cyg OB2 association cannot be fully excluded. The velocity-resolved [CII] emission traces the emission ...

  9. Polymer globule with fractal properties caused by intramolecular nanostructuring and spatial constrains.

    Science.gov (United States)

    Glagoleva, Anna A; Vasilevskaya, Valentina V; Khokhlov, Alexei R

    2016-06-21

    By means of computer simulation, we studied macromolecules composed of N dumbbell amphiphilic monomer units with attractive pendant groups. In poor solvents, these macromolecules form spherical globules that are dense in the case of short chains (the gyration radius RG∼N(1/3)), or hollow inside and obey the RG∼N(1/2) law when the macromolecules are sufficiently long. Due to the specific intramolecular nanostructuring, the vesicle-like globules of long amphiphilic macromolecules posses some properties of fractal globules, by which they (i) could demonstrate the same scaling statistics for the entire macromolecule and for short subchains with m monomer units and (ii) possess a specific territorial structure. Within a narrow slit, the globule loses its inner cavity, takes a disk-like shape and scales as N(1/2) for much shorter macromolecules. However, the field of end-to-end distance r(m) ∼m(1/2) dependence for subchains becomes visibly smaller. The results obtained were compared with the homopolymer case. PMID:27198966

  10. Na-Fe-Phosphate Globules in Impact Metal-Troilite Associations of Chelyabinsk Meteorite

    Science.gov (United States)

    Sharygin, V. V.; Karmanov, N. S.; Podgornykh, N. M.

    2016-08-01

    Multi- and monophase phosphate globules have been found in the impact metal-troilite aggregates of the Chelyabinsk chondrite. Their phase composition varies and they contain galileiite, sarcopside, graftonite and Na-Fe-phosphate Na2(Fe,Mn)5(PO4)4.

  11. The dynamics of the biological membrane surrounding the buffalo milk fat globule investigated as a function of temperature.

    Science.gov (United States)

    Nguyen, Hanh T H; Madec, Marie-Noëlle; Ong, Lydia; Kentish, Sandra E; Gras, Sally L; Lopez, Christelle

    2016-08-01

    The biological membrane surrounding fat globules in milk (the MFGM) is poorly understood, despite its importance in digestion and in determining the properties of fat globules. In this study, in situ structural investigations of buffalo MFGM were performed as a function of temperature (4-60°C), using confocal microscopy. We demonstrate that temperature and rate of temperature change affected the lipid domains formed in the MFGM with the lateral segregation (i) of high Tm lipids and cholesterol in a Lo phase for both TTm and (ii) of high Tm lipids in a gel phase for Tfat globules during processing and digestion.

  12. Sulfur metabolism in phototrophic sulfur bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Dahl, Christiane

    2008-01-01

    in other types of anoxygenic phototrophic bacteria. The biochemistry and genetics of sulfur compound oxidation in PSB and GSB are described in detail. A variety of enzymes catalyzing sulfur oxidation reactions have been isolated from GSB and PSB (especially Allochromatium vinosum, a representative......Phototrophic sulfur bacteria are characterized by oxidizing various inorganic sulfur compounds for use as electron donors in carbon dioxide fixation during anoxygenic photosynthetic growth. These bacteria are divided into the purple sulfur bacteria (PSB) and the green sulfur bacteria (GSB......). They utilize various combinations of sulfide, elemental sulfur, and thiosulfate and sometimes also ferrous iron and hydrogen as electron donors. This review focuses on the dissimilatory and assimilatory metabolism of inorganic sulfur compounds in these bacteria and also briefly discusses these metabolisms...

  13. Modulation of current through a nanopore induced by a charged globule: implications for DNA-docking

    CERN Document Server

    Chinappi, Mauro; Cecconi, Fabio; Marconi, Umberto Marini Bettolo; Melchionna, Simone

    2015-01-01

    The passage of DNA through a nanopore can be effectively decomposed into two distinct phases, docking and actual translocation. In experiments each phase is characterized by a distinct current signature which allows the discrimination of the two events. However, at low voltages a clear distinction of the two phases is lost. By using numerical simulations we clarify how the current signature associated to the docking events depends on the applied voltage. The simulations show that at small voltage the DNA globule enhances the pore conductance due to an enrichment of charge carriers. At high voltage, the globule drains substantial charge carriers from the pore region, thereby reducing the overall conductance. The results provide a new interpretation to the experimental data on conductance and show how docking interferes with the translocation signal, of potential interest for sequencing applications.

  14. Comparative proteomics of milk fat globule membrane in different species reveals variations in lactation and nutrition.

    Science.gov (United States)

    Lu, Jing; Wang, Xinyu; Zhang, Weiqing; Liu, Lu; Pang, Xiaoyang; Zhang, Shuwen; Lv, Jiaping

    2016-04-01

    In present study, 312, 554, 175 and 143 proteins were identified and quantified by label-free quantitative proteomics in human, cow, goat and yak milk fat globule membrane (MFGM), respectively. Fifty proteins involved in vesicle mediate transport and milk fat globule secretion were conserved among species. Moreover, proteins involved in lipid synthesis and secretion (xanthine dehydrogenase/oxidase, stomatin and CD36), showed different expression pattern and the host defense proteins exhibited various profiles within species. Notably, the content and activity of lipid catabolic enzymes were significantly higher in human MFGM, which could be indicative of the superior fat utilization in breast fed infants. Our findings unraveled the significant differences in protein composition of human milk and conventionally used substitutes of it. The in-depth study of lipid metabolic enzymes in human MFGM will probably contribute to the improvement of the fat utilization through modulation of lipid catabolic enzymes in infant formula.

  15. Spitzer Observations of a 24 μm Shadow: Bok Globule CB 190

    Science.gov (United States)

    Stutz, Amelia M.; Bieging, John H.; Rieke, George H.; Shirley, Yancy L.; Balog, Zoltan; Gordon, Karl D.; Green, Elizabeth M.; Keene, Jocelyn; Kelly, Brandon C.; Rubin, Mark; Werner, Michael W.

    2007-08-01

    We present Spitzer observations of the dark globule CB 190 (LDN 771). We observe a roughly circular 24 μm shadow with a 70" radius. The extinction profile of this shadow matches the profile derived from 2MASS photometry at the outer edges of the globule and reaches a maximum of ~32 visual magnitudes at the center. The corresponding mass of CB 190 is ~10 Msolar. Our 12CO and 13CO J=2-1 data over a 10'×10' region centered on the shadow show a temperature ~10 K. The thermal continuum indicates a similar temperature for the dust. The molecular data also show evidence of freezeout onto dust grains. We estimate a distance to CB 190 of 400 pc using the spectroscopic parallax of a star associated with the globule. Bonnor-Ebert fits to the density profile, in conjunction with this distance, yield ξmax=7.2, indicating that CB 190 may be unstable. The high temperature (56 K) of the best-fit Bonnor-Ebert model is in contradiction with the CO and thermal continuum data, leading to the conclusion that the thermal pressure is not enough to prevent free-fall collapse. We also find that the turbulence in the cloud is inadequate to support it. However, the cloud may be supported by the magnetic field, if this field is at the average level for dark globules. Since the magnetic field will eventually leak out through ambipolar diffusion, it is likely that CB 190 is collapsing or in a late precollapse stage. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.

  16. Sequential star formation in a cometary globule (BRC37) of IC1396

    CERN Document Server

    Ikeda, Hisashi; Watanabe, Makoto; Fukuda, Naoya; Tamura, Motohide; Nakajima, Yasushi; Pickles, Andrew J; Nagashima, Chie; Nagayama, Takahiro; Nakaya, Hidehiko; Nakano, Makoto; Nagata, Tetsuya

    2008-01-01

    We have carried out near-IR/optical observations to examine star formation toward a bright-rimmed cometary globule (BRC37) facing the exciting star(s) of an HII region (IC1396) containing an IRAS source, which is considered to be an intermediate-mass protostar. With slit-less spectroscopy we detected ten H_alpha emission stars around the globule, six of which are near the tip of the globule and are aligned along the direction to the exciting stars. There is evidence that this alignment was originally towards an O9.5 star, but has evolved to align towards a younger O6 star when that formed. Near-IR and optical photometry suggests that four of these six stars are low-mass young stellar objects (YSOs) with masses of ~0.4 M_sun. Their estimated ages of ~1 Myr indicate that they were formed at the tip in advance of the formation of the IRAS source. Therefore, it is likely that sequential star formation has been taking place along the direction from the exciting stars towards the IRAS source, due to the UV impact o...

  17. Spitzer observations of a 24 micron shadow: Bok Globule CB190

    CERN Document Server

    Stutz, Amelia M; Rieke, George H; Shirley, Yancy L; Balog, Zoltan; Gordon, Karl D; Green, Elizabeth M; Keene, Jocelyn; Kelly, Brandon C; Rubin, Mark; Werner, Michael W

    2007-01-01

    We present Spitzer observations of the dark globule CB190 (L771). We observe a roughly circular 24 micron shadow with a 70 arcsec radius. The extinction profile of this shadow matches the profile derived from 2MASS photometry at the outer edges of the globule and reaches a maximum of ~32 visual magnitudes at the center. The corresponding mass of CB190 is ~10 Msun. Our 12CO and 13CO J = 2-1 data over a 10 arcmin X 10 arcmin region centered on the shadow show a temperature ~10 K. The thermal continuum indicates a similar temperature for the dust. The molecular data also show evidence of freezeout onto dust grains. We estimate a distance to CB190 of 400 pc using the spectroscopic parallax of a star associated with the globule. Bonnor-Ebert fits to the density profile, in conjunction with this distance, yield xi_max = 7.2, indicating that CB190 may be unstable. The high temperature (56 K) of the best fit Bonnor-Ebert model is in contradiction with the CO and thermal continuum data, leading to the conclusion that ...

  18. Solvent extraction of elemental sulfur from coal and a determination of its source using stable sulfur isotopes

    Science.gov (United States)

    Hackley, Keith C.; Buchanan, D.H.; Coombs, K.; Chaven, C.; Kruse, C.W.

    1990-01-01

    Hot tetrachloroethene (perchloroethylene, PCE) extracts significant amounts of elemental sulfur (So) from weathered coals but not from pristine coals. The objective of this study was to determine whether So extracted by PCE is an oxidation product of pyrite or whether it originates in some way from unstable, organically-bound sulfur. The isotopic composition of the PCE-extracted So was compared to the isotopic compositions of the pyritic and the organic sulfur in a coal. The So was shown to have an isotopic signature similar to the pyritic sulfur. Additionally, the isotopic differences observed between the pyritic, So and sulfatic sulfur were consistent with bacterial mediated oxidation of sulfide sulfur (pyrite) as the source of both the sulfatic and elemental sulfur. ?? 1990.

  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. Morphology of globules and cenospheres in heavy fuel oil burner experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kwack, E.Y.; Shakkottai, P.; Massier, P.F.; Back, L.H. (Jet Propulsion Lab., California Inst. of Technology, Pasadena, CA (US))

    1992-04-01

    Number 6 fuel oil was heated, sprayed, and burned in an enclosure using a small commercial oil burner. Samples of residues that emerged from the flame were collected at various locations outside the flame and observed by a scanning electron microscope. Porous cenospheres, larger globules (of size 80 {mu}m to 200 {mu}m) that resemble soap bubbles formed from the very viscous liquid residue, and unburned oil drops were the types of particle collected. This paper reports on the qualitative relationships of the morphology of these particles to the temperature history to which they were subjected were made.

  1. Phase transitions of a polymer threading a membrane coupled to coil-globule transitions

    OpenAIRE

    Matsuyama, Akihiko

    2004-01-01

    We theoretically study phase transitions of a polymer threading through a pore imbedded in a membrane. We focus on the coupling between a partition of the polymer segments through the membrane and a coil-globule transition of the single polymer chain. Based on the Flory model for collapse transitions of a polymer chain, we calculate the fraction of polymer segments and the expansion factor of a polymer coil on each side of the membrane. We predict a first-order phase transition of a polymer t...

  2. Explicit-ion Effects in the Coil-Globule Transition of Weak Polyelectrolytes

    Science.gov (United States)

    Sikora, Benjamin J.; Whitmer, Jonathan K.

    The first-order coil-globule transition in weak (annealed) polyelectrolytes involves a subtle balance of pH, charge strength, and solvation forces. In this work, we utilize a coarse-grain hybrid grand-canonical Monte Carlo and Molecular Dynamics approach to explore the free energetic topography of a model hydrophobic polybase [representing poly(2-vinylpyridine) (P2VP)] and explore the role of salt concentration/valency in influencing polyelectrolyte conformations using both an implicit Debye-Hückel and explicit salt approach. Our simulations reproduce the experimentally measured behavior for dilute annealed polyelectrolytes, and present a solid foundation for understanding pH responsive polyelectrolyte materials.

  3. The Sulfur Cycle

    Science.gov (United States)

    Kellogg, W. W.; And Others

    1972-01-01

    A model estimating the contributions of sulfur compounds by natural and human activities, and the rate of removal of sulfur from the atmosphere, is based on a review of the existing literature. Areas requiring additional research are identified. (AL)

  4. The dynamics of the biological membrane surrounding the buffalo milk fat globule investigated as a function of temperature.

    Science.gov (United States)

    Nguyen, Hanh T H; Madec, Marie-Noëlle; Ong, Lydia; Kentish, Sandra E; Gras, Sally L; Lopez, Christelle

    2016-08-01

    The biological membrane surrounding fat globules in milk (the MFGM) is poorly understood, despite its importance in digestion and in determining the properties of fat globules. In this study, in situ structural investigations of buffalo MFGM were performed as a function of temperature (4-60°C), using confocal microscopy. We demonstrate that temperature and rate of temperature change affected the lipid domains formed in the MFGM with the lateral segregation (i) of high Tm lipids and cholesterol in a Lo phase for both TTm and (ii) of high Tm lipids in a gel phase for Tglobules during processing and digestion. PMID:26988511

  5. Properties of protostars in the Elephant Trunk globule IC 1396A

    CERN Document Server

    Reach, William T; Rho, Jeonghee; Boogert, Adwin; Tappe, Achim; Jarrett, Thomas H; Morris, Patrick; Cambresy, Laurent; Palla, Francesco; Valdettaro, Riccardo

    2008-01-01

    Extremely red objects, identified in the early Spitzer Space Telescope observations of the bright-rimmed globule IC 1396A and photometrically classified as Class I protostars Class II T Tauri stars based on their mid-infrared colors, were observed spectroscopically at 5.5 to 38 microns (IRS), at the 22 GHz water maser frequency (GBT), and in the optical (Palomar). The sources photometrically identified as Class I are confirmed as objects dominated by accretion luminosity from dense envelopes, with accretion rates 1e-5 to 1e-6 Msun/yr. The ice/silicate absorption ratio in the envelope is exceptionally low for the IC 1396A protostars, compared to those in nearby star-forming regions, suggesting the envelope chemistry is altered by the radiation field or globule pressure. Only one 22 GHz water maser was detected in IC 1396A; its infrared counterpart has luminosity <0.1 Lsun, the first H2O maser from such a low-luminosity object. The objects photometrically classified as Class II are confirmed as classical T T...

  6. Fitting a Turbulent Cloud Model to CO Observations of Starless Bok Globules

    Science.gov (United States)

    Hegmann, M.; Hengel, C.; Röllig, M.; Kegel, W. H.

    We present observations of five starless Bok globules in transitions of 12CO (J=2-1 and {J=3-2}), 13CO (J=2-1), and C18O (J=2-1) which have been obtained at the Heinrich-Hertz-Telescope. For an analysis of the data we use the model of Kegel et al. (see e.g. Piehler & Kegel 1995, A&A 297, 841; Hegmann & Kegel 2000, A&A 359, 405) which describes an isothermal sphere stabilized by turbulent and thermal pressure. This approach deals with the full NLTE radiative transfer problem and accounts for a turbulent velocity field with finite correlation length. By a comparison of observed and calculated line profiles we are able not only to determine the kinetic temperature, hydrogen density and CO coloumn density of the globules, but also to study the properties of the turbulent velocity field, i.e. the variance of its one-point-distribution and its correlation length. We consider our model to be an alternative tool for the evaluation of molecular lines emitted by molecular clouds. The model assumptions are certainly closer to reality than the assumptions behind the standard evaluation models, as for example the LVG model. Our current study shows that that the results obtained from our model can differ significantly from those obtained from a LVG analysis.

  7. Ribosomal Protein P2 from apicomplexan parasite Toxoplasma gondii is intrinsically a molten globule.

    Science.gov (United States)

    Mishra, Pushpa; Choudhary, Sinjan; Hosur, Ramakrishna V

    2015-01-01

    Toxoplasma gondii is an apicomplexan parasite, which causes toxoplasmosis. Toxoplasma P2 (TgP2) is a ribosomal protein and exists as supramolecular assembly with other proteins in the ribosome. It is also shown that TgP2 is involved in some extra ribosomal functions. However, till date the protein has evaded structural characterization by any of the known techniques. In this background, we report here a systematic study using a variety of biophysical techniques and NMR, under different conditions of pH and temperature, and deduce that TgP2 consists of only helices and unstructured regions, is a monomer at low pH but forms multimers at higher pH, and has intrinsically a molten globule structure. The C-terminal half is flexible and the helices are concentrated in the N-terminal half of the chain. The dynamism inherent to the molten globule structure may have functional implications for its extra-ribosomal functions. which is contrast to that of human P2. PMID:25866913

  8. Pillars and globules at the edges of H ii regions, Confronting Herschel observations and numerical simulations

    CERN Document Server

    Tremblin, P; Schneider, N; Audit, E; Hill, T; Didelon, P; Peretto, N; Arzoumanian, D; Motte, F; Zavagno, A; Bontemps, S; Anderson, L D; Andre, Ph; Bernard, J P; Csengeri, T; Di Francesco, J; Elia, D; Hennemann, M; Konyves, V; Marston, A P; Luong, Q Nguyen; Rivera-Ingraham, A; Roussel, H; Sousbie, T; Spinoglio, L; White, G J; Williams, J

    2013-01-01

    Pillars and globules are present in many high-mass star-forming regions, such as the Eagle nebula (M16) and the Rosette molecular cloud, and understanding their origin will help characterize triggered star formation. The formation mechanisms of these structures are still being debated. Recent numerical simulations have shown how pillars can arise from the collapse of the shell in on itself and how globules can be formed from the interplay of the turbulent molecular cloud and the ionization from massive stars. The goal here is to test this scenario through recent observations of two massive star-forming regions, M16 and Rosette. The column density structure of the interface between molecular clouds and H ii regions was characterized using column density maps obtained from far-infrared imaging of the Herschel HOBYS key programme. Then, the DisPerSe algorithm was used on these maps to detect the compressed layers around the ionized gas and pillars in different evolutionary states. Finally, their velocity structu...

  9. Sulfuric acid on Europa and the radiolytic sulfur cycle

    Science.gov (United States)

    Carlson, R. W.; Johnson, R. E.; Anderson, M. S.

    1999-01-01

    A comparison of laboratory spectra with Galileo data indicates that hydrated sulfuric acid is present and is a major component of Europa's surface. In addition, this moon's visually dark surface material, which spatially correlates with the sulfuric acid concentration, is identified as radiolytically altered sulfur polymers. Radiolysis of the surface by magnetospheric plasma bombardment continuously cycles sulfur between three forms: sulfuric acid, sulfur dioxide, and sulfur polymers, with sulfuric acid being about 50 times as abundant as the other forms. Enhanced sulfuric acid concentrations are found in Europa's geologically young terrains, suggesting that low-temperature, liquid sulfuric acid may influence geological processes.

  10. Coil-globule transition for regular, random and specially designed copolymers: Monte Carlo simulation and self-consistent field theory

    NARCIS (Netherlands)

    Oever, J.M.P.; Leermakers, F.A.M.; Fleer, G.J.; Ivanov, V.A.; Shusharina, N.P.; Khokhlov, A.R.; Khalatur, P.G.

    2002-01-01

    The coil-globule transition has been studied for A-B copolymer chains both by means of lattice Monte Carlo (MC) simulations using bond fluctuation algorithm and by a numerical self-consistent-field (SCF) method. Copolymer chains of fixed length with A and B monomeric units with regular, random, and

  11. Synthesis, structure and spectroscopic characteristics of Ti(O,C)$_2$/carbon nanostructured globules with visible light photocatalytic activity

    Indian Academy of Sciences (India)

    V N KRASIL’NIKOV; E V SHALAEVA; I V BAKLANOVA; M A MELKOZEROVA; M V KUZNETSOV; E V ZABOLOTSKAYA; O I GYRDASOVA; L YU BULDAKOVA; A M MURZAKAEV

    2016-10-01

    A morphology-controlled facile synthesis of titanium-glycolate precursors with subsequent annealing in He and air atmospheres has been exploited for the production of nanostructured composite globules, whiskers and plates of C-modified titanium dioxide. Characterisation tests proved the as-obtained globule composites to exclusively exhibit high-specific surface area (up to 150–170 m$^2$ g$^{−1}$), thus being useful for photocatalytic applications inthe visible-light region. The combination of the electron paramagnetic resonance, X-ray photoelectron spectroscopy, absorption spectroscopy and transmission electron microscopy revealed the presence of three kinds of carbon in the globules: a small bandgap (with measured width of 0.8 eV) amorphous carbon surrounding the anatase nanocrystallites,C-containing radicals including carbonates on the surface of TiO$_2$ and interstitial carbon in the oxygen position of the TiO$_2$ lattice. It was found that the maximum visible-light photocatalytic activity of the globules is determinedby the optimal surface concentration of amorphous carbon of about 0.002 wt.% m$^{−2}$. Under these conditions, the highest synergic photosensitising effect on TiO$_2$ nanocrystallites of all three kinds of carbon is expected.

  12. Comparative proteomics of milk fat globule membrane in goat colostrum and mature milk.

    Science.gov (United States)

    Lu, Jing; Liu, Lu; Pang, Xiaoyang; Zhang, Shuwen; Jia, Zhenhu; Ma, Changlu; Zhao, Lili; Lv, Jiaping

    2016-10-15

    As an important nutrient source in large area of world, the composition and nutritional value of goat milk are not well deliberated. Detailed annotation of protein composition is essential to address the physiological and nutritional value of goat milk. In the present study, 423 colostrum and mature goat milk fat globule membrane (MFGM) proteins were identified. The abundance of 189 proteins was significantly different between colostrums and mature milk MFGM. The acute phase proteins were higher in colostrums MFGM than those in mature milk MFGM which protected newborns at the beginning of life. Proteins related to synthesis and secretion were conserved through lactation to ensure the milk production. Of note, long term depression (LTD) proteins were observed in colostrum and mature milk MFGM. Milk LTD proteins could be potential biomarkers for diagnosis of lactation related depressive syndromes and should be taken into considerations of their effects on newborns. PMID:27173528

  13. Composition and microstructure of colostrum and mature bovine milk fat globule membrane.

    Science.gov (United States)

    Zou, Xiaoqiang; Guo, Zheng; Jin, Qingzhe; Huang, Jianhua; Cheong, Lingzhi; Xu, Xuebing; Wang, Xingguo

    2015-10-15

    The microstructures of colostrum and mature bovine milk fat globule membrane (MFGM) were investigated using confocal laser scanning microscopy (CLSM) at different temperatures, and the relationships between microstructure variations and the chemical compositions of the MFGM were also examined. Using a fluorophore-labeled phospholipid probe, we found that non-fluorescent domains on the MFGM were positively correlated with the amount of sphingomyelin at both room (20 °C) and physiological (37 °C) temperatures. However, at the storage temperature (4 °C), there were more non-fluorescent domains on the MFGM. These results indicate that the heterogeneities in the MFGM are most likely to be the result of the lateral segregation of sphingomyelin at the room and physiological temperatures, and at the storage temperature, phospholipids with saturated fatty acids affect the formation of these domains. PMID:25952880

  14. The protein and lipid composition of the membrane of milk fat globules depends on their size.

    Science.gov (United States)

    Lu, Jing; Argov-Argaman, Nurit; Anggrek, Jeni; Boeren, Sjef; van Hooijdonk, Toon; Vervoort, Jacques; Hettinga, Kasper Arthur

    2016-06-01

    In bovine milk, fat globules (MFG) have a heterogeneous size distribution with diameters ranging from 0.1 to 15 µm. Although efforts have been made to explain differences in lipid composition, little is known about the protein composition of MFG membranes (MFGM) in different sizes of MFG. In this study, protein and lipid analyses were combined to study MFG formation and secretion. Two different sized MFG fractions (7.6±0.9 µm and 3.3±1.2 µm) were obtained by centrifugation. The protein composition of MFGM in the large and small MFG fractions was compared using mass-spectrometry-based proteomics techniques. The lipid composition and fatty acid composition of MFG was determined using HPLC-evaporative light-scattering detector and gas chromatography, respectively. Two frequently studied proteins in lipid droplet biogenesis, perilipin-2 and TIP47, were increased in the large and small MFG fractions, respectively. In the large MFG fraction, besides perilipin-2, cytoplasmic vesicle proteins (heat shock proteins, 14-3-3 proteins, and Rabs), microfilaments and intermediate filament-related proteins (actin and vimentin), host defense proteins (cathelicidins), and phosphatidylinositol were higher in concentration. On the other hand, cholesterol synthesis enzymes [lanosterol synthase and sterol-4-α-carboxylate 3-dehydrogenase (decarboxylating)], cholesterol, unsaturated fatty acids, and phosphatidylethanolamine were, besides TIP47, higher in concentration in the small MFG fraction. These results suggest that vesicle proteins, microfilaments and intermediate filaments, cholesterol, and specific phospholipids play an important role in lipid droplet growth, secretion, or both. The observations from this study clearly demonstrated the difference in protein and lipid composition between small and large MFG fractions. Studying the role of these components in more detail in future experiments may lead to a better understanding of fat globule formation and secretion.

  15. The global sulfur cycle

    Science.gov (United States)

    Sagan, D. (Editor)

    1985-01-01

    The results of the planetary biology microbial ecology's 1984 Summer Research Program, which examined various aspects of the global sulfur cycle are summarized. Ways in which sulfur flows through the many living and chemical species that inhabit the surface of the Earth were investigated. Major topics studied include: (1) sulfur cycling and metabolism of phototropic and filamentous sulfur bacteria; (2) sulfur reduction in sediments of marine and evaporite environments; (3) recent cyanobacterial mats; (4) microanalysis of community metabolism in proximity to the photic zone in potential stromatolites; and (5) formation and activity of microbial biofilms on metal sulfides and other mineral surfaces. Relationships between the global sulfur cycle and the understanding of the early evolution of the Earth and biosphere and current processes that affect global habitability are stressed.

  16. The effect of milk processing on the microstructure of the milk fat globule and rennet induced gel observed using confocal laser scanning microscopy.

    Science.gov (United States)

    Ong, L; Dagastine, R R; Kentish, S E; Gras, S L

    2010-04-01

    Confocal laser scanning microscopy (CLSM) was successfully used to observe the effect of milk processing on the size and the morphology of the milk fat globule in raw milk, raw ultrafiltered milk, and standardized and pasteurized milk prepared for cheese manufacture (cheese-milk) and commercial pasteurized and homogenized milk. Fat globule size distributions for the milk preparations were analyzed using both image analysis and light scattering and both measurements produced similar data trends. Changes to the native milk fat globule membrane (MFGM) were tracked using a MFGM specific fluorescent stain that allowed MFGM proteins and adsorbed proteins to be differentiated on the fat globule surface. Sodium dodecyl sulfate polyacrylamide gel electrophoresis confirmed the identity of native MFGM proteins isolated from the surface of fat globules within raw, UF retentate, and cheese-milk preparations, whereas only casein was detected on the surface of fat globules in homogenized milk. The microstructure, porosity, and gel strength of the rennet induced gel made from raw milk and cheese-milk was also found to be comparable and significantly different to that made from homogenized milk. Our results highlight the potential use of CLSM as a tool to observe the structural details of the fat globule and associated membrane close to its native environment.

  17. Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

    Science.gov (United States)

    Namur, Olivier; Charlier, Bernard; Holtz, Francois; Cartier, Camille; McCammon, Catherine

    2016-08-01

    Chemical data from the MESSENGER spacecraft revealed that surface rocks on Mercury are unusually enriched in sulfur compared to samples from other terrestrial planets. In order to understand the speciation and distribution of sulfur on Mercury, we performed high temperature (1200-1750 °C), low- to high-pressure (1 bar to 4 GPa) experiments on compositions representative of Mercurian lavas and on the silicate composition of an enstatite chondrite. We equilibrated silicate melts with sulfide and metallic melts under highly reducing conditions (IW-1.5 to IW-9.4; IW = iron-wüstite oxygen fugacity buffer). Under these oxygen fugacity conditions, sulfur dissolves in the silicate melt as S2- and forms complexes with Fe2+, Mg2+ and Ca2+. The sulfur concentration in silicate melts at sulfide saturation (SCSS) increases with increasing reducing conditions (from 10 wt.% S at IW-8) and with increasing temperature. Metallic melts have a low sulfur content which decreases from 3 wt.% at IW-2 to 0 wt.% at IW-9. We developed an empirical parameterization to predict SCSS in Mercurian magmas as a function of oxygen fugacity (fO2), temperature, pressure and silicate melt composition. SCSS being not strictly a redox reaction, our expression is fully valid for magmatic systems containing a metal phase. Using physical constraints of the Mercurian mantle and magmas as well as our experimental results, we suggest that basalts on Mercury were free of sulfide globules when they erupted. The high sulfur contents revealed by MESSENGER result from the high sulfur solubility in silicate melt at reducing conditions. We make the realistic assumption that the oxygen fugacity of mantle rocks was set during equilibration of the magma ocean with the core and/or that the mantle contains a minor metal phase and combine our parameterization of SCSS with chemical data from MESSENGER to constrain the oxygen fugacity of Mercury's interior to IW- 5.4 ± 0.4. We also calculate that the mantle of Mercury

  18. Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

    Science.gov (United States)

    Namur, Olivier; Charlier, Bernard; Holtz, Francois; Cartier, Camille; McCammon, Catherine

    2016-08-01

    Chemical data from the MESSENGER spacecraft revealed that surface rocks on Mercury are unusually enriched in sulfur compared to samples from other terrestrial planets. In order to understand the speciation and distribution of sulfur on Mercury, we performed high temperature (1200-1750 °C), low- to high-pressure (1 bar to 4 GPa) experiments on compositions representative of Mercurian lavas and on the silicate composition of an enstatite chondrite. We equilibrated silicate melts with sulfide and metallic melts under highly reducing conditions (IW-1.5 to IW-9.4; IW = iron-wüstite oxygen fugacity buffer). Under these oxygen fugacity conditions, sulfur dissolves in the silicate melt as S2- and forms complexes with Fe2+, Mg2+ and Ca2+. The sulfur concentration in silicate melts at sulfide saturation (SCSS) increases with increasing reducing conditions (from 10 wt.% S at IW-8) and with increasing temperature. Metallic melts have a low sulfur content which decreases from 3 wt.% at IW-2 to 0 wt.% at IW-9. We developed an empirical parameterization to predict SCSS in Mercurian magmas as a function of oxygen fugacity (fO2), temperature, pressure and silicate melt composition. SCSS being not strictly a redox reaction, our expression is fully valid for magmatic systems containing a metal phase. Using physical constraints of the Mercurian mantle and magmas as well as our experimental results, we suggest that basalts on Mercury were free of sulfide globules when they erupted. The high sulfur contents revealed by MESSENGER result from the high sulfur solubility in silicate melt at reducing conditions. We make the realistic assumption that the oxygen fugacity of mantle rocks was set during equilibration of the magma ocean with the core and/or that the mantle contains a minor metal phase and combine our parameterization of SCSS with chemical data from MESSENGER to constrain the oxygen fugacity of Mercury's interior to IW- 5.4 ± 0.4. We also calculate that the mantle of Mercury

  19. ADVANCED SULFUR CONTROL CONCEPTS

    Energy Technology Data Exchange (ETDEWEB)

    Apostolos A. Nikolopoulos; Santosh K. Gangwal; William J. McMichael; Jeffrey W. Portzer

    2003-01-01

    Conventional sulfur removal in integrated gasification combined cycle (IGCC) power plants involves numerous steps: COS (carbonyl sulfide) hydrolysis, amine scrubbing/regeneration, Claus process, and tail-gas treatment. Advanced sulfur removal in IGCC systems involves typically the use of zinc oxide-based sorbents. The sulfides sorbent is regenerated using dilute air to produce a dilute SO{sub 2} (sulfur dioxide) tail gas. Under previous contracts the highly effective first generation Direct Sulfur Recovery Process (DSRP) for catalytic reduction of this SO{sub 2} tail gas to elemental sulfur was developed. This process is currently undergoing field-testing. In this project, advanced concepts were evaluated to reduce the number of unit operations in sulfur removal and recovery. Substantial effort was directed towards developing sorbents that could be directly regenerated to elemental sulfur in an Advanced Hot Gas Process (AHGP). Development of this process has been described in detail in Appendices A-F. RTI began the development of the Single-step Sulfur Recovery Process (SSRP) to eliminate the use of sorbents and multiple reactors in sulfur removal and recovery. This process showed promising preliminary results and thus further process development of AHGP was abandoned in favor of SSRP. The SSRP is a direct Claus process that consists of injecting SO{sub 2} directly into the quenched coal gas from a coal gasifier, and reacting the H{sub 2}S-SO{sub 2} mixture over a selective catalyst to both remove and recover sulfur in a single step. The process is conducted at gasifier pressure and 125 to 160 C. The proposed commercial embodiment of the SSRP involves a liquid phase of molten sulfur with dispersed catalyst in a slurry bubble-column reactor (SBCR).

  20. Sulfur recovery further improved

    Energy Technology Data Exchange (ETDEWEB)

    Borsboom, J.; Grinsven, M. van; Warners, A. van [Jacobs Nederland B.V., (Netherlands); Nisselrooy, P. van [Gastec N.V., (Netherlands)

    2002-04-01

    The original 100-year-old Claus process for producing sulfur from hydrogen sulfide in acid gas is described together with improvements which have been made over the years. The most recent modification, EUROCLAUS, achieves sulfur recoveries of 99-99.9 per cent. Five commercial units are being designed.

  1. Globules and pillars in Cygnus X. I. Herschel far-infrared imaging of the Cygnus OB2 environment

    Science.gov (United States)

    Schneider, N.; Bontemps, S.; Motte, F.; Blazere, A.; André, Ph.; Anderson, L. D.; Arzoumanian, D.; Comerón, F.; Didelon, P.; Di Francesco, J.; Duarte-Cabral, A.; Guarcello, M. G.; Hennemann, M.; Hill, T.; Könyves, V.; Marston, A.; Minier, V.; Rygl, K. L. J.; Röllig, M.; Roy, A.; Spinoglio, L.; Tremblin, P.; White, G. J.; Wright, N. J.

    2016-06-01

    The radiative feedback of massive stars on molecular clouds creates pillars, globules and other features at the interface between the H II region and molecular cloud. Optical and near-infrared observations from the ground as well as with the Hubble or Spitzer satellites have revealed numerous examples of such cloud structures. We present here Herschel far-infrared observations between 70 μm and 500 μm of the immediate environment of the rich Cygnus OB2 association, performed within the Herschel imaging survey of OB Young Stellar objects (HOBYS) program. All of the observed irradiated structures were detected based on their appearance at 70 μm, and have been classified as pillars, globules, evaporating gasous globules (EGGs), proplyd-like objects, and condensations. From the 70 μm and 160 μm flux maps, we derive the local far-ultraviolet (FUV) field on the photon dominated surfaces. In parallel, we use a census of the O-stars to estimate the overall FUV-field, that is 103-104 G0 (Habing field) close to the central OB cluster (within 10 pc) and decreases down to a few tens G0, in a distance of 50 pc. From a spectral energy distribution (SED) fit to the four longest Herschel wavelengths, we determine column density and temperature maps and derive masses, volume densities and surface densities for these structures. We find that the morphological classification corresponds to distinct physical properties. Pillars and globules are massive (~500 M⊙) and large (equivalent radius r ~ 0.6 pc) structures, corresponding to what is defined as "clumps" for molecular clouds. EGGs and proplyd-likeobjects are smaller (r ~ 0.1 and 0.2 pc) and less massive (~10 and ~30 M⊙). Cloud condensations are small (~0.1 pc), have an average mass of 35 M⊙, are dense (~6 × 104 cm-3), and can thus be described as molecular cloud "cores". All pillars and globules are oriented toward the Cyg OB2 association center and have the longest estimated photoevaporation lifetimes, a few million

  2. Multiple sulfur isotopes fractionations associated with abiotic sulfur transformations in Yellowstone National Park geothermal springs

    Science.gov (United States)

    2014-01-01

    Background The paper presents a quantification of main (hydrogen sulfide and sulfate), as well as of intermediate sulfur species (zero-valent sulfur (ZVS), thiosulfate, sulfite, thiocyanate) in the Yellowstone National Park (YNP) hydrothermal springs and pools. We combined these measurements with the measurements of quadruple sulfur isotope composition of sulfate, hydrogen sulfide and zero-valent sulfur. The main goal of this research is to understand multiple sulfur isotope fractionation in the system, which is dominated by complex, mostly abiotic, sulfur cycling. Results Water samples from six springs and pools in the Yellowstone National Park were characterized by pH, chloride to sulfate ratios, sulfide and intermediate sulfur species concentrations. Concentrations of sulfate in pools indicate either oxidation of sulfide by mixing of deep parent water with shallow oxic water, or surface oxidation of sulfide with atmospheric oxygen. Thiosulfate concentrations are low (<6 μmol L-1) in the pools with low pH due to fast disproportionation of thiosulfate. In the pools with higher pH, the concentration of thiosulfate varies, depending on different geochemical pathways of thiosulfate formation. The δ34S values of sulfate in four systems were close to those calculated using a mixing line of the model based on dilution and boiling of a deep hot parent water body. In two pools δ34S values of sulfate varied significantly from the values calculated from this model. Sulfur isotope fractionation between ZVS and hydrogen sulfide was close to zero at pH < 4. At higher pH zero-valent sulfur is slightly heavier than hydrogen sulfide due to equilibration in the rhombic sulfur–polysulfide – hydrogen sulfide system. Triple sulfur isotope (32S, 33S, 34S) fractionation patterns in waters of hydrothermal pools are more consistent with redox processes involving intermediate sulfur species than with bacterial sulfate reduction. Small but resolved differences in ∆33S among

  3. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

  4. Modélisation numérique des formes d’équilibre d’un globule rouge

    OpenAIRE

    Simeoni, Matthieu Martin Jean-Andre

    2013-01-01

    Nous nous proposons dans cette étude de valider le modèle introduit par Canham et Helfrich afin de décrire les formes d’équilibre statique d’un globule rouge. Selon ce modèle, la forme du globule rouge est solution d’un problème d’optimisation sous contrainte: minimisation de l’énergie de Canham Helfrich pour un volume et une aire fixés. Après avoir formaliser le problème matématiquement, nous dérivons la conditionn d’optimalité menant à une équation différentielle ordinaire non linéaire véri...

  5. Redox proteomics of fat globules unveils broad protein lactosylation and compositional changes in milk samples subjected to various technological procedures.

    Science.gov (United States)

    Arena, Simona; Renzone, Giovanni; Novi, Gianfranco; Scaloni, Andrea

    2011-10-19

    The Maillard reaction between lactose and proteins occurs during thermal treatment of milk and lactosylated β-lactoglobulin, α-lactalbumin and caseins have widely been used to monitor the quality of dairy products. We recently demonstrated that a number of other whey milk proteins essential for nutrient delivery, defense against bacteria/virus and cellular proliferation become lactosylated during milk processing. The extent of their modification is associated with the harshness of product manufacturing. Since fat globule proteins are also highly important for the health-beneficial properties of milk, an evaluation of their lactosylation is crucial for a complete understanding of aliment nutritional characteristics. This is more important when milk is the unique dietary source, as in the infant diet. To this purpose, a sequential proteomic procedure involving an optimized milk fat globule (MFG) preparation/electrophoretic resolution, shot-gun analysis of gel portions for protein identification, selective trapping of lactosylated peptides by phenylboronate chromatography and their analysis by nanoLC-ESI-electron transfer dissociation (ETD) tandem MS was used for systematic characterization of fat globule proteins in milk samples subjected to various manufacturing procedures. Significant MFG protein compositional changes were observed between samples, highlighting the progressive adsorption of caseins and whey proteins on the fat globule surface as result of the technological process used. A significant lactosylation of MFG proteins was observed in ultra-high temperature sterilized and powdered for infant nutrition milk preparations, which well paralleled with the harshness of thermal treatment. Globally, this study allowed the identification of novel 157 non-redundant modification sites and 35 MFG proteins never reported so far as being lactosylated, in addition to the 153 ones ascertained here as present on other 21 MFG-adsorbed proteins whose nature was already

  6. Study of the variables which influence the impregnation of globules, compressed tablets and tablet triturates used in homeopathy

    OpenAIRE

    Fernanda Santos de Souza; Mayara Marin Pirolli; Eliana Elisabeth Diehl; Diva Sonaglio

    2012-01-01

    Globules, compressed tablets and tablet triturates are solid dosage forms used in homeopathy. Divergences can be noted between the preparation techniques described in official compendiums as well as those applied in homeopathic pharmacies. The difficulty associated with standardization of the impregnation of these dosage forms occurs due to the lack of detail provided for the techniques in the literature, leaving it up to each pharmacy to decide on the exact method of preparation. The objecti...

  7. Looking into the hearts of Bok globules: MM and submm continuum images of isolated star-forming cores

    OpenAIRE

    Launhardt, R.; Nutter, D.; Ward-Thompson, D.; Bourke, T. L.; Henning, Th.; Khanzadyan, T.; Schmalzl, M.; Wolf, S; Zylka, R.

    2010-01-01

    We present the results of a comprehensive infrared, submillimetre, and millimetre continuum emission study of isolated low-mass star-forming cores in 32 Bok globules, with the aim to investigate the process of star formation in these regions. The submillimetre and millimetre dust continuum emission maps together with the spectral energy distributions are used to model and derive the physical properties of the star-forming cores, such as luminosities, sizes, masses, densities, etc. Comparisons...

  8. Hydrolysis of human milk fat globules by pancreatic lipase: role of colipase, phospholipase A2, and bile salts.

    OpenAIRE

    Bläckberg, L; Hernell, O.; Olivecrona, T

    1981-01-01

    Human milk fat globules were used to explore how dietary triglycerides are hydrolyzed by pancreatic lipase. These triglycerides were hydrolyzed very slowly by lipase alone as if the surface layer of proteins and phospholipids impeded the action of the enzyme. The inhibition of lipase activity could be overcome by addition either of colipase or of pancreatic phospholipase A2. Colipase enhanced triglyceride hydrolysis in a dose-dependent manner whether bile salts were present or not. Bile salts...

  9. Globules and Pillars in Cygnus X I. Herschel Far-infrared imaging of the Cyg OB2 environment

    CERN Document Server

    Schneider, N; Motte, F; Blazere, A; Andre, Ph; Anderson, L D; Arzoumanian, D; Comeron, F; Didelon, P; Di Francesco, J; Duarte-Cabral, A; Guarcello, M G; Hennemann, M; Hill, T; Konyves, V; Marston, A; Minier, V; Rygl, K L J; Roellig, M; Roy, A; Spinoglio, L; Tremblin, P; White, G J; Wright, N J

    2016-01-01

    The radiative feedback of massive stars on molecular clouds creates pillars, globules and other features at the interface between the HII region and molecular cloud. We present here Herschel observations between 70 and 500 micron of the immediate environment of the Cygnus OB2 association, performed within the HOBYS program. All structures were detected based on their appearance at 70 micron, and have been classified as pillars, globules, evaporating gasous globules (EGGs), proplyd-like objects, and condensations. From the 70 and 160 micron flux maps, we derive the local FUV field on the PDR surfaces. In parallel, we use a census of the O-stars to estimate the overall FUV-field, that is 10^3-10^4 G_0 close to the central OB cluster (within 10 pc) and decreases down to a few tens G_0, in a distance of 50 pc. From a SED fit to the four longest Herschel wavelengths, we determine column density and temperature maps and derive masses, volume densities and surface densities for these structures. We find that the mor...

  10. Cytoplasmic sulfur trafficking in sulfur-oxidizing prokaryotes.

    Science.gov (United States)

    Dahl, Christiane

    2015-04-01

    Persulfide groups are chemically versatile and participate in a wide array of biochemical pathways. Although it is well documented that persulfurated proteins supply a number of important and elaborate biosynthetic pathways with sulfane sulfur, it is far less acknowledged that the enzymatic generation of persulfidic sulfur, the successive transfer of sulfur as a persulfide between multiple proteins, and the oxidation of sulfane sulfur in protein-bound form are also essential steps during dissimilatory sulfur oxidation in bacteria and archaea. Here, the currently available information on sulfur trafficking in sulfur oxidizing prokaryotes is reviewed, and the idea is discussed that sulfur is always presented to cytoplasmic oxidizing enzymes in a protein-bound form, thus preventing the occurrence of free sulfide inside of the prokaryotic cell. Thus, sulfur trafficking emerges as a central element in sulfur-oxidizing pathways, and TusA homologous proteins appear to be central and common elements in these processes.

  11. Intramedullary and extramedullary fat globules on magnetic resonance imaging as a diagnostic sign for osteomyelitis

    International Nuclear Information System (INIS)

    We retrospectively studied the frequency of persistent foci of fat signal on magnetic resonance (MR) imaging in osteomyelitis to assess its frequency, cause and diagnostic value. The radiographs and MR scans of 100 patients with a final diagnosis of osteomyelitis referred to a specialist orthopaedic oncology service with the presumptive diagnosis of a bone tumour were reviewed. The MR signal and morphological characteristics were recorded with particular attention to the presence of persistent fat signal within the infected area, which was classified as diffuse or focal. Seventeen cases were classified on radiographic grounds as acute, 63 as subacute and 20 as chronic osteomyelitis. In the acute group 12 (70%) showed replacement of the marrow with fluid containing residual fatty signal, diffuse in seven and focal in five cases. Two cases showed predominantly fatty marrow with very early marrow oedema and three cases (18%) showed replacement of marrow fat with fluid and no residual fatty foci. None of the subacute group showed foci of fatty signal and two cases of inactive sclerosing osyeomyelitis in the chronic group showed restoration of normal marrow. Persistent fatty signal within the bone as well as soft tissues on MR imaging is a frequent finding in acute osteomyelitis. Radiological-pathological correlation suggests that the increasing intramedullary pressure leads to septic necrosis with death of the lipocytes and release of free fatty globules. This characteristic, but not pathognomonic, MR finding supports the diagnosis of osteomyelitis and may help to exclude the presence of a tumour. (orig.)

  12. Radiation-MHD models of elephant trunks and globules in H II regions

    CERN Document Server

    Mackey, Jonathan

    2011-01-01

    We study the formation and evolution of pillars of dense gas, known as elephant trunks, at the boundaries of H II regions, formed by shadowing of ionising radiation by dense clumps. The effects of magnetic fields on this process are investigated using 3D radiation-magnetohydrodynamics simulations. For a simulation in which an initially uniform magnetic field of strength |B|=50 uG is oriented perpendicular to the radiation propagation direction, the field is swept into alignment with the pillar during its dynamical evolution, in agreement with observations of the "Pillars of Creation" in M16, and of some cometary globules. This effect is significantly enhanced when the simulation is re-run with a weaker field of 18 uG. A stronger field with |B|=160 uG is sufficient to prevent this evolution completely, also significantly affecting the photoionisation process. Using a larger simulation domain it is seen that the pillar formation models studied in Mackey & Lim (2010) ultimately evolve to cometary structures ...

  13. Study of magnetic field geometry and extinction in Bok globule CB130

    CERN Document Server

    Chakraborty, A

    2016-01-01

    We trace the peripheral magnetic field structure of Bok globule CB130, by estimating the linear polarization of its field stars in the R band. The magnetic field orientation sampled by these stars, aligned on average among themselves and the polarization produced within the cloud has a different direction from that of Galactic plane with an offset of 53$^\\circ$. The offset between minor axis and the mean magnetic field of CB130 is found to be 80$^\\circ$. The estimated strength of the magnetic field in the plane-of-the-sky is $\\sim$ 116$\\pm$19 $\\mu$G. We constructed the visual extinction map using Near Infrared Color Excess (NICE) method to see the dust distribution around CB130. Contours of Herschel {Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA} SPIRE 500$\\mu$m dust continuum emission maps of this cloud is over-plotted on the visual extinction map which shows the regions having higher optical ...

  14. Separation of sulfur isotopes

    Science.gov (United States)

    DeWitt, Robert; Jepson, Bernhart E.; Schwind, Roger A.

    1976-06-22

    Sulfur isotopes are continuously separated and enriched using a closed loop reflux system wherein sulfur dioxide (SO.sub.2) is reacted with sodium hydroxide (NaOH) or the like to form sodium hydrogen sulfite (NaHSO.sub.3). Heavier sulfur isotopes are preferentially attracted to the NaHSO.sub.3, and subsequently reacted with sulfuric acid (H.sub.2 SO.sub.4) forming sodium hydrogen sulfate (NaHSO.sub.4) and SO.sub.2 gas which contains increased concentrations of the heavier sulfur isotopes. This heavy isotope enriched SO.sub.2 gas is subsequently separated and the NaHSO.sub.4 is reacted with NaOH to form sodium sulfate (Na.sub.2 SO.sub.4) which is subsequently decomposed in an electrodialysis unit to form the NaOH and H.sub.2 SO.sub.4 components which are used in the aforesaid reactions thereby effecting sulfur isotope separation and enrichment without objectionable loss of feed materials.

  15. Sulfur cycling in freshwater sediments

    Science.gov (United States)

    Klug, M. J.

    1985-01-01

    Organic sulfur containing compounds represent greater than 80% of the total sulfur in sediments of eutrophic freshwater lakes. Although sedimentary sulfur is predominantly in the form of organic compounds, more sulfur is transformed by sulfate reduction than by any other process. Rates of sulfate reduction in these sediments average 7 mmol/sq m/day. This rate is 19 times greater than the net rate of production of inorganic sulfur from organic compounds on an annual basis.

  16. Molten globule of hemoglobin proceeds into aggregates and advanced glycated end products.

    Directory of Open Access Journals (Sweden)

    Afshin Iram

    Full Text Available Conformational alterations of bovine hemoglobin (Hb upon sequential addition of glyoxal over a range of 0-90% v/v were investigated. At 20% v/v glyoxal, molten globule (MG state of Hb was observed by altered tryptophan fluorescence, high ANS binding, existence of intact heme, native-like secondary structure as depicted by far-UV circular dichroism (CD and ATR-FTIR spectra as well as loss in tertiary structure as confirmed by near-UV CD spectra. In addition, size exclusion chromatography analysis depicted that MG state at 20% v/v glyoxal corresponded to expanded pre-dissociated dimers. Aggregates of Hb were detected at 70% v/v glyoxal. These aggregates of Hb had altered tryptophan environment, low ANS binding, exposed heme, increased β-sheet secondary structure, loss in tertiary structure, enhanced thioflavin T (ThT fluorescence and red shifted Congo Red (CR absorbance. On incubating Hb with 30% v/v glyoxal for 0-20 days, advanced glycation end products (AGEs were detected on day 20. These AGEs were characterised by enhanced tryptophan fluorescence at 450 nm, exposure of heme, increase in intermolecular β-sheets, enhanced ThT fluorescence and red shift in CR absorbance. Comet assay revealed aggregates and AGEs to be genotoxic in nature. Scanning electron microscopy confirmed the amorphous structure of aggregates and branched fibrils of AGEs. The transformation of α-helix to β-sheet usually alters the normal protein to amyloidogenic resulting in a variety of protein conformational disorders such as diabetes, prion and Huntington's.

  17. Shocked and Scorched: Free-Floating Evaporating Gas Globules and Star Formation in Cygnus

    Science.gov (United States)

    Sahai, Raghvendra; Claussen, M. J.; Morris, M. R.

    2012-05-01

    We report molecular line observations of a new class of Free-floating Evaporating Gas Globules with tadpole shapes (i.e., FrEGGs), recently discovered in the Cygnus star-forming region. We serendipitously found two of these in an HST imaging survey, including one of the most prominent members of this class (IRAS20324+4057: the Tadpole). Our molecular-line observations, carried out with the Arizona Radio Observatory's mm-wave telescopes, include on-the-fly maps in the CO and 13CO J=2-1 lines as well as pointed observations in the J=3-2 line of the high-density tracers HCO+ and N2H+. These data show the presence of dense molecular cores with total masses of cold molecular gas exceeding one to a few Msun in almost all FrEGGs. Our radio continuum imaging of 3 FrEGGs, as well as Halpha images from the IPHAS survey reveal bright photo-ionized peripheries around these objects. We infer that FrEGGs are dense, star-forming molecular cores that originated in the Cygnus cloud and are now being photoevaporated by the ultraviolet radiation field of the Cyg OB2 cluster, and shaped by the ram pressure of strong wind sources. The extended tails in some of the largest objects show wiggles likely resulting from Kelvin-Helmoltz instabilities. We find evidence for non-thermal radio emission in the Tadpole, with the radio emission peaking strongly along the shock/ionization front at its head, possibly as a result of a compressed magnetic layer in this front that is interacting with cosmic rays associated with the Cyg OB2 association.

  18. Study of magnetic field geometry and extinction in Bok globule CB130

    Science.gov (United States)

    Chakraborty, A.; Das, H. S.

    2016-09-01

    We trace the peripheral magnetic field structure of Bok globule CB130 by estimating the linear polarization of its field stars in the R band. The magnetic field orientation sampled by these stars, aligned on average among themselves, and the polarization produced within the cloud has a different direction from that of Galactic plane with an offset of 53°. The offset between minor axis and the mean magnetic field of CB130 is found to be 80°. The estimated strength of the magnetic field in the plane-of-the-sky is ˜116±19 μG. We constructed the visual extinction map using the Near Infrared Color Excess (NICE) method to see the dust distribution around CB130. Contours of Herschel (Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA) SPIRE 500 μm dust continuum emission map of this cloud is over-plotted on the visual extinction map, which shows that the regions having higher optical extinction correspond to higher densities of dust. Three distinct high dust density cores (named as C1, C2, and C3) are identified in the extinction map. It is observed that the cores C1 and C3 are located close to two previously known cores CB130-1 and CB130-2, respectively. Estimates of visual extinction of some moderately obscured stars of CB130 are made utilizing near-infrared photometry. It is observed that there is a feeble dependence of polarization on extinction, and the polarization efficiency (defined as p/AV) of the dust grains decreases with the increase in extinction.

  19. Shocked and Scorched - Free-Floating Evaporating Gas Globules and Star Formation

    Science.gov (United States)

    Sahai, Raghvendra; Morris, Mark R.; Claussen, Mark J.

    2014-07-01

    Massive stars have a strong feedback effect on their environment, via their winds, UV radiation, and ultimately, supernova blast waves, all of which can alter the likelihood for the formation of stars in nearby clouds and limit the accretion process of nearby protostars. Free-floating Evaporating Gaseous Globules, or frEGGs, are a newly recognized class of stellar nurseries embedded within the giant HII regions found in massive star-formation region (MSFRs). We recently discovered the prototype frEGG in the Cygnus MSFR with HST. Further investigation using the Spitzer and Herschel archives have revealed a much larger number (>50) in Cygnus and other MSFRs. Our molecular-line observations of these show the presence of dense clouds with total masses of cool molecular gas exceeding 0.5 to a few Msun associated with these objects, thereby disproving the initial hypothesis based on their morphology that these have an origin similar to the proplyds (cometary-shaped photoevaporating protoplanetary disks) found in Orion. We report the results of our molecular-line studies and detailed high-resolution optical (with HST) or near-IR (with AO at the Keck Observatory) imaging of a few frEGGs in Cygnus, Carina and the W5 MSFRs. The images show the presence of young stars with associated outflow cavities and/or jets in the heads of the tadpole-shaped frEGGs. These results support our hypothesis that frEGGs are density concentrations originating in giant molecular clouds, that, when subject to the compression by the strong winds and ionization from massive stars in these MSFRs, become active star-forming cores. In summary, by virtue of their distinct, isolated morphologies, frEGGs offer us a clean probe of triggered star formation on small scales in the vicinity of massive stars.

  20. Comparative proteomics of milk fat globule membrane proteins from transgenic cloned cattle.

    Science.gov (United States)

    Sui, Shunchao; Zhao, Jie; Wang, Jianwu; Zhang, Ran; Guo, Chengdong; Yu, Tian; Li, Ning

    2014-01-01

    The use of transgenic livestock is providing new methods for obtaining pharmaceutically useful proteins. However, the protein expression profiles of the transgenic animals, including expression of milk fat globule membrane (MFGM) proteins, have not been well characterized. In this study, we compared the MFGM protein expression profile of the colostrum and mature milk from three lines of transgenic cloned (TC) cattle, i.e., expressing recombinant human α-lactalbumin (TC-LA), lactoferrin (TC-LF) or lysozyme (TC-LZ) in the mammary gland, with those from cloned non-transgenic (C) and conventionally bred normal animals (N). We identified 1, 225 proteins in milk MFGM, 166 of which were specifically expressed only in the TC-LA group, 265 only in the TC-LF group, and 184 only in the TC-LZ group. There were 43 proteins expressed only in the transgenic cloned animals, but the concentrations of these proteins were below the detection limit of silver staining. Functional analysis also showed that the 43 proteins had no obvious influence on the bovine mammary gland. Quantitative comparison revealed that MFGM proteins were up- or down-regulated more than twofold in the TC and C groups compared to N group: 126 in colostrum and 77 in mature milk of the TC-LA group; 157 in colostrum and 222 in mature milk of the TC-LF group; 49 in colostrum and 98 in mature milk of the TC-LZ group; 98 in colostrum and 132 in mature milk in the C group. These up- and down-regulated proteins in the transgenic animals were not associated with a particular biological function or pathway, which appears that expression of certain exogenous proteins has no general deleterious effects on the cattle mammary gland.

  1. Aircraft exhaust sulfur emissions

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R.C.; Anderson, M.R.; Miake-Lye, R.C.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics; Sorokin, A.A.; Buriko, Y.I. [Scientific Research Center `Ecolen`, Moscow (Russian Federation)

    1997-12-31

    The extent to which fuel sulfur is converted to SO{sub 3} during combustion and the subsequent turbine flow in supersonic and subsonic aircraft engines is estimated numerically. The analysis is based on: a flamelet model with non-equilibrium sulfur chemistry for the combustor, and a one-dimensional, two-stream model with finite rate chemical kinetics for the turbine. The results indicate that between 2% and 10% of the fuel sulfur is emitted as SO{sub 3}. It is also shown that, for a high fuel sulfur mass loading, conversion in the turbine is limited by the level of atomic oxygen at the combustor exit, leading to higher SO{sub 2} oxidation efficiency at lower fuel sulfur loadings. While SO{sub 2} and SO{sub 3} are the primary oxidation products, the model results further indicate H{sub 2}SO{sub 4} levels on the order of 0.1 ppm for supersonic expansions through a divergent nozzle. This source of fully oxidized S(6) (SO{sub 3} + H{sub 2}SO{sub 4}) exceeds previously calculated S(6) levels due to oxidation of SO{sub 2} by OH in the exhaust plume outside the engine nozzle. (author) 26 refs.

  2. The effects of low-molecular-weight emulsifiers in O/W-emulsions on microviscosity of non-solidified oil in fat globules and the mobility of emulsifiers at the globule surfaces

    DEFF Research Database (Denmark)

    Munk, Merete B.; Erichsen, Henriette Rifbjerg; Andersen, Mogens Larsen

    2014-01-01

    Electron Spin Resonance spectroscopy (ESR) was used to measure the mobility of the spin probe TEMPO in O/W-emulsions. This allowed determination of temperature-dependent microviscosity of the liquid fraction in lipid globules. Six hydrogenated palm kernel oil (HPKO) based emulsions containing...... caseinate and different combinations of lactic acid ester of monoglyceride (LACTEM), unsaturated monoglycerides (GMU) or saturated monoglyceride (GMS) were studied. The non-solidified oil in emulsions made with LACTEM. +. GMU had a high microviscosity, whereas the emulsion made with GMS had a low...

  3. Corrosion-resistant sulfur concretes

    Science.gov (United States)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  4. The 16S rDNA Phylogenetic Composition of Bacteria Implicated in Sulfur Redox Cycles and Associated Sulfur Isotope Fractionation

    Science.gov (United States)

    Bicknell, B. T.; Batts, J. E.; Krouse, H. R.

    2006-12-01

    The reduction of sulfate ion to sulfide species by sulfate reducing bacteria (SRB) is accompanied by sulfur isotope fractionation, measured in terms of changes in the δ^{34}S values for sulfate and sulfide ions relative to a defined standard. In open environments, the S-isotope compositions of sulfate and sulfide can be affected by loss from the system of sulfide species as gaseous H2S, insoluble metal sulfides such as FeS2, organic complexes or by re-oxidation. The S-isotope fractionation accompanying bacterial sulfate reduction in nature is often much larger than the maxima obtained in chemical and bacterial sulfate reduction experiments in the laboratory. One mechanism postulated for the large natural S-isotope selectivity depends on repetitive reduction-oxidation cycles. In turn, this would require a level of tolerance to oxygen by SRB in the sedimentary environment, contrary to laboratory experience with SRB strains. Bird Lake (The Coorong, South Australia) is a small calcareous, evaporative lake, where average Δ^{34}S (δ^{34}Ssulfate - δ^{34}Ssulfide) values for groundwater at 16 of the 27 sites sampled periodically since 1974, vary from 15.0 ‰ to 62.3 ‰ within the range -1.8 ‰ to 70.6 ‰. Wide fluctuations in δ34Ssulfide values at individual sites are the significant factor affecting the variability of Δ^{34}S values. Values for δ18Osulfate are elevated over that of the sulfate source to an unusual extent, reflecting re-oxidation of sulfur species and O- isotope exchange between some of these species and water. One aspect of investigations at Bird Lake was the evaluation of bacterial populations in subsurface sediments and their role in sulfur cycling. To achieve this, microcosms were established with subsurface sediment and incubated under a nitrogen atmosphere, for up to 119 days. These were sampled at various times to determine sulfur species concentrations and sulfur isotope fractionation and to generate 16S rDNA clone libraries. Results

  5. Characterization of molten globule PopB in absence and presence of its chaperone PcrH.

    Science.gov (United States)

    Dey, Supratim; Basu, Abhishek; Datta, Saumen

    2012-06-01

    The TTSS encoding "translocator operon" of Pseudomonas aeruginosa consists of a major translocator protein PopB, minor translocator protein PopD and their cognate chaperone PcrH. Far-UV CD spectra and secondary structure prediction servers predict an α-helical model for PopB, PcrH and PopB-PcrH complex. PopB itself forms a single species of higher order oligomer (15 mer) as seen from AUC, but in complex with PcrH, both monomeric (1:1) and oligomeric form exist. PopB has large solvent-exposed hydrophobic patches and exists as an unordered molten globule in its native state, but on forming complex with PcrH it gets transformed into an ordered molten globule. Tryptophan fluorescence spectrum indicates that PopB interacts with the first TPR region of dimeric PcrH to form a stable PopB-PcrH complex that has a partial rigid structure with a large hydrodynamic radius and few tertiary contacts. The pH-dependent studies of PopB, PcrH and complex by ANS fluorescence, urea induced unfolding and thermal denaturation experiments prove that PcrH not only provides structural support to the ordered molten globule PopB in complex but also undergoes conformational change to assist PopB to pass through the needle complex of TTSS and form pores in the host cell membrane. ITC experiments show a strong affinity (K(d) ~ 0.37 μM) of PopB for PcrH at pH 7.8, which reduces to ~0.68 μM at pH 5.8. PcrH also loses its rigid tertiary structure at pH 5 and attains a molten globule conformation. This indicates that the decrease in pH releases PopB molecules and thus triggers the TTSS activation mechanism for the formation of a functional translocon. PMID:22585368

  6. Photo-evaporation of Globulettes : Numerical hydrodynamic studies of photo-evaporating low-mass globules in the Rosette Nebula

    OpenAIRE

    Kuutmann, Andrej

    2007-01-01

    In this work, the long-term evolution of globulettes, low-mass globules found in H II regions, is studied through numerical hydrodynamic simulations. It has been proposed by Gahm et al. (2007) that these clouds may form free-floating planetary mass objects due to shock compression, caused by heating from the intense UV radiation of the central OB star cluster. To address this possibility, lifetimes are calculated for three different 3D simulated cases, similar to globulettes found in the Rose...

  7. Mass-dependent sulfur isotope fractionation during reoxidative sulfur cycling

    DEFF Research Database (Denmark)

    Pellerin, André; Bui, Thi Hao; Rough, Mikaella;

    2015-01-01

    of Mangrove Lake appears to include sulfide oxidation to elemental sulfur followed by the disproportionation of the elemental sulfur to sulfate and sulfide. This model also indicates that the reoxidative sulfur cycle of Mangrove Lake turns over from 50 to 80% of the sulfide produced by microbial sulfate...... that the two processes cannot be discriminated from each other....

  8. Lunar Sulfur Capture System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Sulfur Capture System (LSCS) is an innovative method to recover sulfur compounds from lunar soil using sorbents derived primarily from in-situ resources....

  9. Lunar Sulfur Capture System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Sulfur Capture System (LSCS) is an innovative method to capture greater than 90 percent of sulfur gases evolved during thermal treatment of lunar soils....

  10. Sulfur Dioxide Pollution Monitor.

    Science.gov (United States)

    National Bureau of Standards (DOC), Washington, DC.

    The sulfur dioxide pollution monitor described in this document is a government-owed invention that is available for licensing. The background of the invention is outlined, and drawings of the monitor together with a detailed description of its function are provided. A sample stream of air, smokestack gas or the like is flowed through a…

  11. Accidents with sulfuric acid

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2006-01-01

    Full Text Available Sulfuric acid is an important industrial and strategic raw material, the production of which is developing on all continents, in many factories in the world and with an annual production of over 160 million tons. On the other hand, the production, transport and usage are very dangerous and demand measures of precaution because the consequences could be catastrophic, and not only at the local level where the accident would happen. Accidents that have been publicly recorded during the last eighteen years (from 1988 till the beginning of 2006 are analyzed in this paper. It is very alarming data that, according to all the recorded accidents, over 1.6 million tons of sulfuric acid were exuded. Although water transport is the safest (only 16.38% of the total amount of accidents in that way 98.88% of the total amount of sulfuric acid was exuded into the environment. Human factor was the common factor in all the accidents, whether there was enough control of the production process, of reservoirs or transportation tanks or the transport was done by inadequate (old tanks, or the accidents arose from human factor (inadequate speed, lock of caution etc. The fact is that huge energy, sacrifice and courage were involved in the recovery from accidents where rescue teams and fire brigades showed great courage to prevent real environmental catastrophes and very often they lost their lives during the events. So, the phrase that sulfuric acid is a real "environmental bomb" has become clearer.

  12. Characterization of Sulfur Compounds in MTBE

    OpenAIRE

    Mingqing Wu; Chunyan Chang; Tao Li; Jian Zhou; Liping Zhao

    2015-01-01

    A study is carried out on chemical constitution of sulfur compounds in MTBE and their formation mechanisms. These sulfur compounds are classified into three types: common sulfur compounds, newly formed sulfur compounds, and high boiling sulfur compounds. Common sulfur compounds which include mercaptans, low molecule sulfides and disulfides, are directly from C4, one of the stocks for production of MTBE. The newly formed sulfur compounds, with one sulfur atom and five or more total carbon atom...

  13. SULFUR POLYMER ENCAPSULATION

    International Nuclear Information System (INIS)

    Sulfur polymer cement (SPC) is a thermoplastic polymer consisting of 95 wt% elemental sulfur and 5 wt% organic modifiers to enhance long-term durability. SPC was originally developed by the U.S. Bureau of Mines as an alternative to hydraulic cement for construction applications. Previous attempts to use elemental sulfur as a construction material in the chemical industry failed due to premature degradation. These failures were caused by the internal stresses that result from changes in crystalline structure upon cooling of the material. By reacting elemental sulfur with organic polymers, the Bureau of Mines developed a product that successfully suppresses the solid phase transition and significantly improves the stability of the product. SPC, originally named modified sulfur cement, is produced from readily available, inexpensive waste sulfur derived from desulfurization of both flue gases and petroleum. The commercial production of SPC is licensed in the United States by Martin Resources (Odessa, Texas) and is marketed under the trade name Chement 2000. It is sold in granular form and is relatively inexpensive ((approx)$0.10 to 0.12/lb). Application of SPC for the treatment of radioactive, hazardous, and mixed wastes was initially developed and patented by Brookhaven National Laboratory (BNL) in the mid-1980s (Kalb and Colombo, 1985; Colombo et al., 1997). The process was subsequently investigated by the Commission of the European Communities (Van Dalen and Rijpkema, 1989), Idaho National Engineering Laboratory (Darnell, 1991), and Oak Ridge National Laboratory (Mattus and Mattus, 1994). SPC has been used primarily in microencapsulation applications but can also be used for macroencapsulation of waste. SPC microencapsulation has been demonstrated to be an effective treatment for a wide variety of wastes, including incinerator hearth and fly ash; aqueous concentrates such as sulfates, borates, and chlorides; blowdown solutions; soils; and sludges. It is not

  14. Sulfur Biogeochemistry of an Oil Sands Composite Tailings Deposit

    Directory of Open Access Journals (Sweden)

    Lesley A Warren

    2016-02-01

    Full Text Available Composite tailings (CT, an engineered, alkaline, saline mixture of oil sands tailings (FFT, processed sand and gypsum (CaSO4; 1 kg CaSO4 per m3 FFT are used as a dry reclamation strategy in the Alberta Oil Sands Region (AOSR. It is estimated that 9.6 x 108 m3 of CT are either in, or awaiting emplacement in surface pits within the AOSR, highlighting their potential global importance in sulfur cycling. Here, in the first CT sulfur biogeochemistry investigation, integrated geochemical, pyrosequencing and lipid analyses identified high aqueous concentrations of ∑H2S (> 300 uM and highly altered sulfur compounds composition; low cell biomass (3.3 x106 to 6.0 x106 cells g-1 and modest bacterial diversity (H’ range between 1.4 to 1.9 across 5 depths spanning 34 meters of an in situ CT deposit. Pyrosequence results identified a total of 29,719 bacterial 16S rRNA gene sequences, representing 131 OTUs spanning19 phyla including 7 candidate divisions, not reported in oil sands tailings pond studies to date. Legacy FFT common phyla, notably, gamma and beta Proteobacteria, Firmicutes, Actinobacteria and Chloroflexi were represented. However, overall CT microbial diversity and PLFA values were low relative to other contexts. The identified known sulfate/sulfur reducing bacteria constituted at most 2% of the abundance; however, over 90% of the 131 OTUs identified are capable of sulfur metabolism. While PCR biases caution against overinterpretation of pyrosequence surveys, bacterial sequence results identified here, align with phospholipid fatty acid (PLFA and geochemical results. The highest bacterial diversities were associated with the depth of highest porewater [∑H2S] (22-24 m and joint porewater co-occurrence of Fe2+ and ∑H2S (6-8 m. Three distinct bacterial community structure depths corresponded to CT porewater regions of (1 shallow evident Fe(II (< 6 m, (2 co-occurring Fe(II and ∑H2S (6-8 m and (3 extensive ∑H2S (6-34 m (UniFrac. Candidate

  15. Comparison of Milk Fat Globule Membrane (MFGM Proteins of Chianina and Holstein Cattle Breed Milk Samples Through Proteomics Methods

    Directory of Open Access Journals (Sweden)

    Lorraine Pariset

    2009-12-01

    Full Text Available Identification of proteins involved in milk production is important to understand the biology of lactation. Many studies have advanced the understanding of mammary function and milk secretion, but the critical molecular mechanisms implicated in milk fat secretion is still incomplete. Milk Fat Globules are secreted from the apical surface of the mammary cells, surrounded by a thin membrane bilayer, the Milk Fat Globule Membrane (MFGM, formed by proteins which have been suggested to be cholesterolemia-lowering factors, inhibitors of cancer cell growth, vitamin binders, bactericidal, suppressors of multiple sclerosis. Using a proteomic approach, we compared MFGM from milk samples of individuals belonging to two different cattle breeds, Chianina and Holstein, representative of selection for milk and meat traits, respectively. We were able to isolate some of the major MFGM proteins in the examined samples and to identify differences between the protein fractions of the two breeds. We detected differences in the amount of proteins linked to mammary gland development and lipid droplets formation, as well as host defence mechanisms. We have shown that proteomics is a suitable, unbiased method for the study of milk fractions proteins and a powerful tool in nutritional genomics.

  16. Discovery of [FeII]- and H2-emission from protostellar jets in the CB3 and CB230 globules

    CERN Document Server

    Massi, F; Brand, J

    2004-01-01

    Four Bok globules were studied in the Near-Infrared, through narrow-band filters, centered at the 1.644 micron line of [FeII], the H2-line at 2.122 micron, and the adjacent continuum. We report the discovery of [FeII] and H2 protostellar jets and knots in the globules CB3 and CB230. The [FeII]-jet in CB230 is defined by a continuous elongated emission feature, superimposed on which two knots are seen; the brighter one lies at the tip of the jet. The jet is oriented in the same direction as the large-scale CO outflow, and emerges from the nebulosity in which a Young Stellar Object is embedded. The H2 emission associated with this jet is fainter and wider than the [FeII] emission, and is likely coming from the walls of the jet-channel. In CB3 four H2 emission knots are found, all towards the blue-shifted lobe of the large-scale outflow. There is a good correspondence between the location of the knots and the blue-shifted SiO(5-4) emission, confirming that SiO emission is tracing the jet-like flow rather well. N...

  17. Disproportionation of elemental sulfur by haloalkaliphilic bacteria from soda lakes.

    Science.gov (United States)

    Poser, Alexander; Lohmayer, Regina; Vogt, Carsten; Knoeller, Kay; Planer-Friedrich, Britta; Sorokin, Dimitry; Richnow, Hans-H; Finster, Kai

    2013-11-01

    Microbial disproportionation of elemental sulfur to sulfide and sulfate is a poorly characterized part of the anoxic sulfur cycle. So far, only a few bacterial strains have been described that can couple this reaction to cell growth. Continuous removal of the produced sulfide, for instance by oxidation and/or precipitation with metal ions such as iron, is essential to keep the reaction exergonic. Hitherto, the process has exclusively been reported for neutrophilic anaerobic bacteria. Here, we report for the first time disproportionation of elemental sulfur by three pure cultures of haloalkaliphilic bacteria isolated from soda lakes: the Deltaproteobacteria Desulfurivibrio alkaliphilus and Desulfurivibrio sp. AMeS2, and a member of the Clostridia, Dethiobacter alkaliphilus. All cultures grew in saline media at pH 10 by sulfur disproportionation in the absence of metals as sulfide scavengers. Our data indicate that polysulfides are the dominant sulfur species under highly alkaline conditions and that they might be disproportionated. Furthermore, we report the first organism (Dt. alkaliphilus) from the class Clostridia that is able to grow by sulfur disproportionation. PMID:24030483

  18. Reduced sulfur in euxinic sediments of the Cariaco Basin : Sulfur isotope contraints on organic sulfur formation

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Werne, J.; Lyons, T.W.; Hollander, D.J.; Formolo, M.

    2003-01-01

    Reduced sulfur accumulation in Holocene and latest Pleistocene euxinic marine sediments from the Cariaco Basin, Venezuela, was investigated to constrain the timing and possible pathways of organic matter (OM) sulfurization. Data were collected for a diverse suite of sulfur species, including concent

  19. Laboratory and field studies concerning the long-term storage of elemental sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Davis, P.M.; Clark, P.D.; Bernard, F. [Alberta Sulfur Research Ltd., Calgary, AB (Canada)]|[Calgary Univ., Calgary, AB (Canada)

    2004-07-01

    Canadian sour gas processing facilities supply much of the elemental sulfur to the international market. Elemental sulfur is a pure commodity obtained when hydrogen sulfide is removed from raw gases by way of the Claus process. Excess production is usually stored above ground as a bulk solid at the processing facility. It is possible that sulfur may have to be stored in large quantities if a market imbalance may occurs due to expanding exploration in sulfur-bearing formations and increasing regulations on sulfur levels in processing effluents. For that reason, long-term storage methods are being examined in detail. Both above and below ground block storage is considered environmentally acceptable for sulfur storage as long as measures are taken to minimize the physical and biological breakdown of the sulfur. The main concern regarding above ground storage is the generation of sulfur dust from phase transformations within the sulfur itself. Other concerns include acid production from bacterial activity and the weathering of the material when it is exposed to the elements over the long-term. This paper addresses these concerns and presents results from a series of research studies on underground storage of elemental sulfur both in the laboratory and in pilot-scale field studies.

  20. Bacterial Vaginosis

    Science.gov (United States)

    ... 586. Related Content STDs during Pregnancy Fact Sheet Pregnancy and HIV, Viral Hepatitis, and STD Prevention Pelvic Inflammatory Disease ( ... Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ... STDs See Also Pregnancy Reproductive ...

  1. Bacterial Meningitis

    Science.gov (United States)

    ... Schedules Preteen & Teen Vaccines Meningococcal Disease Sepsis Bacterial Meningitis Recommend on Facebook Tweet Share Compartir On this ... serious disease. Laboratory Methods for the Diagnosis of Meningitis This manual summarizes laboratory methods used to isolate, ...

  2. Progression in sulfur isotopic compositions from coal to fly ash: Examples from single-source combustion in Indiana

    Science.gov (United States)

    Yaofa, Jiang; Elswick, E.R.; Mastalerz, Maria

    2008-01-01

    Sulfur occurs in multiple mineral forms in coals, and its fate in coal combustion is still not well understood. The sulfur isotopic composition of coal from two coal mines in Indiana and fly ash from two power plants that use these coals were studied using geological and geochemical methods. The two coal beds are Middle Pennsylvanian in age; one seam is the low-sulfur ( 5%) Springfield Coal Member of the Petersburg Formation. Both seams have ash contents of approximately 11%. Fly-ash samples were collected at various points in the ash-collection system in the two plants. The results show notable difference in ??34S for sulfur species within and between the low-sulfur and high-sulfur coal. The ??34S values for all sulfur species are exclusively positive in the low-sulfur Danville coal, whereas the ??34S values for sulfate, pyritic, and organic sulfur are both positive and negative in the high-sulfur Springfield coal. Each coal exhibits a distinct pattern of stratigraphic variation in sulfur isotopic composition. Overall, the ??34S for sulfur species values increase up the section in the low-sulfur Danville coal, whereas they show a decrease up the vertical section in the high-sulfur Springfield coal. Based on the evolution of ??34S for sulfur species, it is suggested that there was influence of seawater on peat swamp, with two marine incursions occurring during peat accumulation of the high-sulfur Springfield coal. Therefore, bacterial sulfate reduction played a key role in converting sulfate into hydrogen sulfide, sulfide minerals, and elemental sulfur. The differences in ??34S between sulfate sulfur and pyritic sulfur is very small between individual benches of both coals, implying that some oxidation occurred during deposition or postdeposition. The ??34S values for fly ash from the high-sulfur Springfield coal (averaging 9.7???) are greatly enriched in 34S relative to those in the parent coal (averaging 2.2???). This indicates a fractionation of sulfur isotopes

  3. Lunar Sulfur Capture System

    Science.gov (United States)

    Berggren, Mark; Zubrin, Robert; Bostwick-White, Emily

    2013-01-01

    The Lunar Sulfur Capture System (LSCS) protects in situ resource utilization (ISRU) hardware from corrosion, and reduces contaminant levels in water condensed for electrolysis. The LSCS uses a lunar soil sorbent to trap over 98 percent of sulfur gases and about two-thirds of halide gases evolved during hydrogen reduction of lunar soils. LSCS soil sorbent is based on lunar minerals containing iron and calcium compounds that trap sulfur and halide gas contaminants in a fixed-bed reactor held at temperatures between 250 and 400 C, allowing moisture produced during reduction to pass through in vapor phase. Small amounts of Earth-based polishing sorbents consisting of zinc oxide and sodium aluminate are used to reduce contaminant concentrations to one ppm or less. The preferred LSCS configuration employs lunar soil beneficiation to boost concentrations of reactive sorbent minerals. Lunar soils contain sulfur in concentrations of about 0.1 percent, and halogen compounds including chlorine and fluorine in concentrations of about 0.01 percent. These contaminants are released as gases such as H2S, COS, CS2,HCl, and HF during thermal ISRU processing with hydrogen or other reducing gases. Removal of contaminant gases is required during ISRU processing to prevent hardware corrosion, electrolyzer damage, and catalyst poisoning. The use of Earth-supplied, single-use consumables to entirely remove contaminants at the levels existing in lunar soils would make many ISRU processes unattractive due to the large mass of consumables relative to the mass of oxygen produced. The LSCS concept of using a primary sorbent prepared from lunar soil was identified as a method by which the majority of contaminants could be removed from process gas streams, thereby substantially reducing the required mass of Earth-supplied consumables. The LSCS takes advantage of minerals containing iron and calcium compounds that are present in lunar soil to trap sulfur and halide gases in a fixedbed reactor

  4. A comparison of density structures of a star forming and a non-star-forming globule. DCld303.8-14.2 and Thumbprint Nebula

    CERN Document Server

    Kainulainen, J; Väisänen, P; Bronfman, L; Knude, J

    2006-01-01

    We present a study of radial density structure of the star forming globule, DCld303.8-14.2 (DC303), and a non-star forming globule, Thumbprint Nebula (TPN), using near-infrared data taken with the ISAAC instrument on the Very Large Telescope. We derive the extinction through the globules using the color excess technique and examine the radial density distribution using Bonnor-Ebert and power-law models. The two globules have significantly different density structures. The extinction profile of DC303 is best fitted with a single power-law with an exponent p = 2.29 \\pm 0.08. An unstable Bonnor-Ebert model with a dimensionless parameter \\xi_max = 23 \\pm 3 provides equally good fit to data. The extinction profile of TPN flattens at small radii, making the profile significantly different from the profile of DC303. We are unable to fit the Bonnor-Ebert model for TPN in a robust manner, but derive the lower limit \\xi_max > 8 for the dimensionless outer edge. The density profile derived for TPN is typical compared to...

  5. Bovine milk proteome: Quantitative changes in normal milk exosomes, milk fat globule membranes and whey proteomes resulting from Staphylococcus aureus mastitis

    Science.gov (United States)

    Knowledge of milk protein composition/expression in healthy cows and cows with mastitis will provide information important for the dairy food industry, mammary biology and immune function in the mammary gland. To facilitate maximum protein discovery, milk was fractioned into whey, milk fat globule ...

  6. Bacterial carbonatogenesis

    International Nuclear Information System (INIS)

    Several series of experiments in the laboratory as well as in natural conditions teach that the production of carbonate particles by heterotrophic bacteria follows different ways. The 'passive' carbonatogenesis is generated by modifications of the medium that lead to the accumulation of carbonate and bicarbonate ions and to the precipitation of solid particles. The 'active' carbonatogenesis is independent of the metabolic pathways. The carbonate particles are produced by ionic exchanges through the cell membrane following still poorly known mechanisms. Carbonatogenesis appears to be the response of heterotrophic bacterial communities to an enrichment of the milieu in organic matter. The active carbonatogenesis seems to start first. It is followed by the passive one which induces the growth of initially produced particles. The yield of heterotrophic bacterial carbonatogenesis and the amounts of solid carbonates production by bacteria are potentially very high as compared to autotrophic or chemical sedimentation from marine, paralic or continental waters. Furthermore, the bacterial processes are environmentally very ubiquitous; they just require organic matter enrichment. Thus, apart from purely evaporite and autotrophic ones, all Ca and/or Mg carbonates must be considered as from heterotrophic bacterial origin. By the way, the carbon of carbonates comes from primary organic matter. Such considerations ask questions about some interpretations from isotopic data on carbonates. Finally, bacterial heterotrophic carbonatogenesis appears as a fundamental phase in the relationships between atmosphere and lithosphere and in the geo-biological evolution of Earth. (author)

  7. G70.7+1.2: A nonthermal bubble in a globule - nova, supernova remnant, or outflow?

    International Nuclear Information System (INIS)

    Millimeter-wave, near-IR, and 21 cm observations of the radio source G70.7 + 1.2 , which has been proposed to be a recent SNR developing inside a molecular cloud, are presented. A small molecular cloud with properties similar to a large dark cloud or globule is interacting with the nonthermal radio continuum source. The molecular cloud has a lumpy structure with its highest column density portion lying just outside the brightest portion of the radio continuum shell. If the radio source was produced by a supernova explosion, its kinetic energy was several orders of magnitude less than that of most observed supernovae. An OB star wind with certain characteristics is sufficient to drive the bubble, but the high radio continuum nonthermal surface brightness and polarization of the object is not explained by this model. 23 references

  8. [Interconnection between architecture of protein globule and disposition of conformational conservative oligopeptides in proteins from one protein family].

    Science.gov (United States)

    Batianovskiĭ, A V; Filatov, I V; Namiot, V A; Esipova, N G; Volotovskiĭ, I D

    2012-01-01

    It was shown that selective interactions between helical segments of macromolecules can realize in globular proteins in the segments characterized by the same periodicities of charge distribution i.e. between conformationally conservative oligopeptides. It was found that in the macromolecules of alpha-helical proteins conformationally conservative oligopeptides are disposed at a distance being characteristic of direct interactions. For representatives of many structural families of alpha-type proteins specific disposition of conformationally conservative segments is observed. This disposition is inherent to a particular structural family. Disposition of conformationally conservative segments is not related to homology of the amino acid sequence but reflects peculiarities of native 3D-architectures of protein globules.

  9. Expression, purification, and characterization of recombinant human and murine milk fat globule-epidermal growth factor-factor 8.

    Science.gov (United States)

    Castellanos, Erick R; Ciferri, Claudio; Phung, Wilson; Sandoval, Wendy; Matsumoto, Marissa L

    2016-08-01

    Milk fat globule-epidermal growth factor-factor 8 (MFG-E8), as its name suggests, is a major glycoprotein component of milk fat globules secreted by the mammary epithelium. Although its role in milk fat production is unclear, MFG-E8 has been shown to act as a bridge linking apoptotic cells to phagocytes for removal of these dying cells. MFG-E8 is capable of bridging these two very different cell types via interactions through both its epidermal growth factor (EGF)-like domain(s) and its lectin-type C domains. The EGF-like domain interacts with αVβ3 and αVβ5 integrins on the surface of phagocytes, whereas the C domains bind phosphatidylserine found on the surface of apoptotic cells. In an attempt to purify full-length, recombinant MFG-E8 expressed in either insect cells or CHO cells, we find that it is highly aggregated. Systematic truncation of the domain architecture of MFG-E8 indicates that the C domains are mainly responsible for the aggregation propensity. Addition of Triton X-100 to the conditioned cell culture media allowed partial recovery of non-aggregated, full-length MFG-E8. A more comprehensive detergent screen identified CHAPS as a stabilizer of MFG-E8 and allowed purification of a significant portion of non-aggregated, full-length protein. The CHAPS-stabilized recombinant MFG-E8 retained its natural ability to bind both αVβ3 and αVβ5 integrins and phosphatidylserine suggesting that it is properly folded and active. Herein we describe an efficient purification method for production of non-aggregated, full-length MFG-E8.

  10. Rethinking the Ancient Sulfur Cycle

    Science.gov (United States)

    Fike, David A.; Bradley, Alexander S.; Rose, Catherine V.

    2015-05-01

    The sulfur biogeochemical cycle integrates the metabolic activity of multiple microbial pathways (e.g., sulfate reduction, disproportionation, and sulfide oxidation) along with abiotic reactions and geological processes that cycle sulfur through various reservoirs. The sulfur cycle impacts the global carbon cycle and climate primarily through the remineralization of organic carbon. Over geological timescales, cycling of sulfur is closely tied to the redox state of Earth's exosphere through the burial of oxidized (sulfate) and reduced (sulfide) sulfur species in marine sediments. Biological sulfur cycling is associated with isotopic fractionations that can be used to trace the fluxes through various metabolic pathways. The resulting isotopic data provide insights into sulfur cycling in both modern and ancient environments via isotopic signatures in sedimentary sulfate and sulfide phases. Here, we review the deep-time δ34S record of marine sulfates and sulfides in light of recent advances in understanding how isotopic signatures are generated by microbial activity, how these signatures are encoded in marine sediments, and how they may be altered following deposition. The resulting picture shows a sulfur cycle intimately coupled to ambient carbon cycling, where sulfur isotopic records preserved in sedimentary rocks are critically dependent on sedimentological and geochemical conditions (e.g., iron availability) during deposition.

  11. Mobilization of sulfur by green sulfur bacteria : physiological and molecular studies on Chlorobaculum parvum DSM 263

    OpenAIRE

    Donà, Clelia

    2011-01-01

    Green sulfur bacteria are photolithotrophs that use inorganic sulfur compounds as electron donors for photosynthesis. Elemental, solid sulfur is one of the electron donors used. Sulfur is produced by green sulfur bacteria during the oxidation of sulfide to sulfate, and during the oxidation of thiosulfate to sulfur and sulfate. Green sulfur bacteria have been known for long, and the genomes of 12 strains have been sequenced. Yet, it is not clear how green sulfur bacteria can access elemental s...

  12. Obtaining Sulfur from Sulfur Hexafluoride and Studying the Sulfur Isotopes Properties by Using Vibrational Spectroscopy

    OpenAIRE

    Egorov, Nikolai Borisovich; Akimov, Dmitry Vasilievich; Zhuravlev, Nikolay

    2015-01-01

    Scheme of isotopically enriched SF[6] to elemental sulfur with orthorhombic modification conversion is offered. This scheme includes SF[6] reduction to Li2S by using lithium. The yield of isotopically enriched sulfur is not less than 97% with chemical purity not less than 99.9%. The results which show the dependence of the experimental frequencies in the vibrational spectra on the molecular weight of the sulfur isotope have been obtained.

  13. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters......, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...

  14. Bacterial lipases

    NARCIS (Netherlands)

    Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno

    1994-01-01

    Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, mea

  15. The role of "blebbing" in overcoming the hydrophobic barrier during biooxidation of elemental sulfur by Thiobacillus thiooxidans

    Science.gov (United States)

    Knickerbocker, C.; Nordstrom, D.K.; Southam, G.

    2000-01-01

    Brimstone Basin, in southeastern Yellowstone National Park, Wyoming is an ancient hydrothermal area containing solfataric alteration. Drainage waters flowing from Brimstone Basin had pH values as low as 1.23 and contained up to 1.7×106 MPN/ml acidophilic sulfur-oxidizing bacteria. Thiobacillus thiooxidans was the dominant sulfur-oxidizing bacterium recovered from an enrichment culture and was used in a structural examination of bacterial sulfur oxidation. Growth in these sulfur cultures occurred in two phases with cells in association with the macroscopic sulfur grains and in suspension above these grains. Colonization of sulfur grains by individual cells and microcolonies was facilitated by organic material that appeared to be responsible for bacterial adhesion. Transmission electron microscopy of negatively stained (2% [wt./vol.] uranyl acetate), sulfur-grown T. thiooxidans revealed extensive membrane blebbing (sloughing of outer membrane vesicles) and the presence of approximately 100 nm sized sulfur particles adsorbed to membrane material surrounding individual bacteria. Sulfite-grown bacteria did not possess membrane blebs. The amphipathic nature of these outer membrane vesicles appear to be responsible for overcoming the hydrophobic barrier necessary for the growth of T. thiooxidans on elemental sulfur.

  16. Sulfur plant start-up

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, Hank; Grigson, Susan [Ortloff Engineers Ltd. (United States)

    2002-02-01

    The authors discuss an Ortloff sulfur plant design concept using the Claus reaction that differs from accepted 'industry practice': cold reactor bed start-up. The process is designed to eliminate catalyst sulfation, heat damage and furnace overheating in sulfur recovery units. (UK)

  17. Bacterial Ecology

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2011-01-01

    Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...... biogeochemical processes are carried exclusively by bacteria. * Bacteria play an important role in all types of habitats including some that cannot support eukaryotic life....

  18. [Bacterial vaginosis].

    Science.gov (United States)

    Romero Herrero, Daniel; Andreu Domingo, Antonia

    2016-07-01

    Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. PMID:27474242

  19. Sulfur meter speeds coal blending

    International Nuclear Information System (INIS)

    The sulfur content has become the most important criterion that industry looks at when purchasing coal. The exact amount of sulfur in coal being processed by a preparation plant must be known and, if possible, controlled by blending coal streams of various sulfur contents. Present techniques, however, of measuring the sulfur in coal involve laborious and time-consuming sampling and chemical analysis (12 to 24 hr), and the results usually are not available until the following day. By then, the coal barges or trains are already on the way to their destinations. A new nuclear sulfur meter is expected to overcome these difficulties and help lead to true automation in coal preparation plants. Initially developed by the Bureau of Mines' Morgantown Energy Research Center (MERC) at Morgantown, W. Va., and completed after reorganization of the center by the US Energy Research and Development Administration (ERDA), the meter can scan coal to produce a reading within 2 min to an accuracy of 0.04 percent sulfur. The meter is expected to soon result in an element-ash-moisture-Btu meter that would rapidly detect the sulfur, sodium, potassium, and overall mineral content of the coal, as well as its ash and Btu content

  20. Determination of the physical parameters of Bok-globules by means of a stochastical radiative transfer method

    Science.gov (United States)

    Hengel, C.; Hegmann, M.; Röllig, M.; Kegel, W. H.

    During the last years, one of the key projects of the Astrophysics group at the University of Frankfurt was the theoretical examination of the influence of turbulence and density fluctuations on the formation of interstellar molecular lines, especially CO lines (Albrecht & Kegel 1987, Kegel et al. 1993, Piehler & Kegel 1995, Hegmann 1999). Based on an approach by G. Traving and collaborators (cf. Gail et al. 1974), a numerical code has been developed to deal with the NLTE problem in an isothermal spherical cloud being stabelized by turbulent and thermal pressure, considering the turbulent velocity field to be stochastic. Our model has been primarily constructed to achieve theoretical insight in the fundamental mechanisms of line formation under more realistic conditions. In view of the stage of development, the model has actually reached, we seriously think of it as an alternative tool for the evaluation of molecular lines emitted by molecular clouds, especially as the model assumptions are certainly closer to reality than the assumptions behind the standard evaluation methods such as e. g. LVG analysis. The objects the physics of which we believe to be closest to our model assumptions are starless Bok globules. We thus have performed observations at the HHT, where we have collected data of five Bok globules in the CO(2-1), CO(3-2), 13CO(2-1) and C18O(2-1) lines. In my contribution I will adress the question, if and how the physical parameters derived by our analysis of the observational data (central H2 density, temperature, correlation length of the turbulent velocity field, and mean square turbulent velocity) differ from the results of an LVG analysis (they do!) and what these findings imply from a physical point of view as well as from a critical viewpoint on the practice of data evaluation. I will talk about problems of our model at its current stage and possible consequences for an improvement of the model, and I will finally give an outlook, how, with

  1. A statistical theory of coil-to-globule-to-coil transition of a polymer chain in a mixture of good solvents

    Science.gov (United States)

    Budkov, Yu. A.; Kolesnikov, A. L.; Kalikin, N. N.; Kiselev, M. G.

    2016-05-01

    We present an off-lattice statistical model of a single polymer chain in mixed-solvent media. Taking into account the polymer conformational entropy, renormalization of solvent composition near the polymer backbone, the universal intermolecular excluded-volume and van der Waals interactions within the self-consistent field theory, the reentrant coil-to-globule-to-coil transition (co-nonsolvency) has been described in this paper. For convenience we split the system volume in two parts: the volume occupied by the polymer chain and the volume of bulk solution. Considering the equilibrium between two sub-volumes, the polymer solvation free energy as a function of radius of gyration and co-solvent mole fraction within internal polymer volume has been obtained. Minimizing the free energy of solvation with respect to its arguments, we show two qulitatively different regimes of co-nonsolvency. Namely, at sufficiently high temperature the reentrant coil-to-globule-to-coil transition proceeds smoothly. On the contrary, when the temperature drops below a certain threshold value a coil-globule transition occurs in the regime of first-order phase transition, i.e., discontinuous changes of the radius of gyration and the local co-solvent mole fraction near the polymer backbone. We show that, when the collapse of the polymer chain takes place, the entropy and enthalpy contributions to the solvation free energy of the globule strongly grow. From the first principles of statistical thermodynamics we confirm earlier speculations based on the MD simulations results that the co-nonsolvency is the essentially enthalpic-entropic effect and is caused by enthalpy-entropy compensation. We show that the temperature dependences of the solution heat capacity change due to the solvation of the polymer chain are in qualitative agreement with the differential scanning calorimetry data for PNIPAM in aqueous methanol.

  2. 46 CFR 148.04-20 - Sulfur.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Sulfur. 148.04-20 Section 148.04-20 Shipping COAST GUARD... Special Additional Requirements for Certain Material § 148.04-20 Sulfur. (a) When sulfur is loaded in a deep hold with general cargo in the 'tween deck hold above the sulfur, a dust proof wooden...

  3. Effect of feeding camphor (Eucalyptus Globules) levels on some immunity characteristics, growth and gut microflora of japanese quails

    International Nuclear Information System (INIS)

    This experiment was conducted to evaluate the effect of adding Eucalyptus globules Egypt to Japanese quail diet on performance and some metabolic functions and immunity. Four hundred,one day old, unsexed japanese quails were used in this study. Quails were divided equally into four groups containing 100 birds in each. Each group contained 4 replicates of 25 birds. Group one was supplemented with 1% Egypt in basal diet, group two was supplemented with 2% Egypt in basal diet, group three was used as negative control (-ve)without any addition of antibiotic in diet or water, while group four represented the positive control (+ ve) by addition antibiotics (0.5 g neomycin sulphate +0.5 g oxytetracyclin) in drinking water for 5 days post hatching. The experimented diet contained 3200 Kcal ME/kg and 24% crude proteins. The end of the experiment was terminated when birds were 6 weeks old. Body weight, mortality, some organs weighs and some blood parameters were measured and some microbial population of small intestines was counted. Results indicated that the addition of Egypt led to significant increase in quails body weights, spleen, bursa and ovary and the measures of total proteins, globulins, haemagglutination inhibition (HI)and triiodothyronine (T3). Decrease in mortality ratio and less counts of microflora and salmonella of gut were also achieved as a result of diet camphor addition

  4. Study of background star polarization and polarization efficiency of three selected Bok globules CB56, CB60 and CB69

    CERN Document Server

    Chakraborty, A; Paul, D

    2014-01-01

    We present the polarization maps of three selected Bok globules CB56, CB60 and CB69 constructed using a V-band data from a CCD imaging polarimeter. The aim of this work is to measure the optical polarization ($p_v$) of background field stars in order to determine the polarization efficiency, $p_v/A_v$. We find that the local magnetic field of the cloud CB56 is almost aligned with the galactic field, but not in CB60 and CB69. A trend of decreasing polarization efficiency with increasing extinction ($A_v$) is observed: it can be well represented by a power law, $p_v/A_v \\propto A_v^{-\\alpha}$, where $\\alpha = -0.56 \\pm 0.36$, $-0.59 \\pm 0.51$ and $-0.52 \\pm 0.49$ for CB56, CB60 and CB69 respectively. This indicates that the linear polarization of the starlight due to aligned dust grains in these clouds is produced more efficiently in low extinction regions, compared with high obscured lines of sight.

  5. Effect of hydrostatic pressure on conformational changes of canine milk lysozyme between the native, molten globule, and unfolded states.

    Science.gov (United States)

    Watanabe, Masahiro; Aizawa, Tomoyasu; Demura, Makoto; Nitta, Katsutoshi

    2004-11-01

    The effect of pressure on the unfolding of the native (N) and molten globule (MG) state of canine milk lysozyme (CML) was examined using ultraviolet (UV) spectroscopy at pH 4.5 and 2.0, respectively. It appeared that the thermally induced unfolding was promoted by the increase of pressure from atmospheric to 100 MPa, which indicates that both the N and MG states of CML unfolded with the decrease of the partial molar volume change (DeltaV). The volume changes needed for unfolding were estimated from the free energy change vs. pressure plots, and these volume changes became less negative from 20 to 60 degrees C. The DeltaV values at 25 degrees C were obtained for the N-MG (-46 cm3/mol) and MG-unfolded-state (U) transition (-40 cm3/mol). With regards to the MG-U transition, this value is contrastive to that of bovine alpha-lactalbumin (BLA) (0.9 cm3/mol), which is homologous to CML. Previous studies revealed that the MG state of CML was significantly more stable, and closer to the N state in structure, than that of BLA. In contrast to the swollen hydrophobic core of the MG state of BLA, our results suggest that the MG state of CML possesses a tightly packed hydrophobic core into which water molecules cannot penetrate. PMID:15488764

  6. Method of preparing graphene-sulfur nanocomposites for rechargeable lithium-sulfur battery electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun; Lemmon, John P; Yang, Zhenguo; Cao, Yuliang; Li, Xiaolin

    2015-04-07

    A method of preparing a graphene-sulfur nanocomposite for a cathode in a rechargeable lithium-sulfur battery comprising thermally expanding graphite oxide to yield graphene layers, mixing the graphene layers with a first solution comprising sulfur and carbon disulfide, evaporating the carbon disulfide to yield a solid nanocomposite, and grinding the solid nanocomposite to yield the graphene-sulfur nanocomposite. Rechargeable-lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter of less than 50 nm.

  7. 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.

  8. Toxicology of sulfur in ruminants: review

    Energy Technology Data Exchange (ETDEWEB)

    Kandylis, K.

    1984-10-01

    This review deals with the toxicology of sulfur in ruminants including toxicity, neurotoxic effects, and mechanism of toxic action of hydrogen sulfide, clinical signs, and treatment. It will report effects of excessive intake of sulfur by ruminants on feed intake, animal performance, ruminal digestion and motility, rumination, and other physiological functions. Poisoning of animals with sulfur from industrial emissions (sulfur dioxide) also is discussed. Excessive quantities of dietary sulfur (above .3 to .4%) as sulfate or elemental sulfur may cause toxic effects and in extreme cases can be fatal. The means is discussed whereby consumption of excessive amounts of sulfur leads to toxic effects. 53 references, 1 table.

  9. For sale: Sulfur emissions

    International Nuclear Information System (INIS)

    The allowance trading market has started a slow march to maturity. Competitive developers should understand the risks and opportunities now presented. The marketplace for sulfur dioxide (SO2) emissions allowances - the centerpiece of Title 4's acid rain reduction program - remains enigmatic 19 months after the Clean Air Act amendments of 1990 were passed. Yet it is increasingly clear that the emission allowance market will likely confound the gloom and doom of its doubters. The recently-announced $10 million dollar Wisconsin Power and Light allowance sales to Duquesne Light and the Tennessee Valley Authority are among the latest indications of momentum toward a stabilizing market. This trend puts additional pressure on independent developers to finalize their allowance strategies. Developers who understand what the allowance trading program is and what it is not, know the key players, and grasp the unresolved regulatory issues will have a new competitive advantage. The topics addressed in this article include the allowance marketplace, marketplace characteristics, the regulatory front, forward-looking strategies, and increasing marketplace activity

  10. Sulfur dioxide scrubbing system

    Energy Technology Data Exchange (ETDEWEB)

    Dahlstrom, D.A.; Cornell, C.F.

    1976-11-02

    Sulfur dioxide is scrubbed from stack gases in an absorption device by a sodium-based aqueous scrubbing solution, a portion of which is subsequently and continuously regenerated outside the absorption apparatus by a causticizing reaction with slaked lime. The causticized solution is routed through a settling device wherefrom a portion of the aqueous sediment is returned to the causticizing zone to provide seed crystals which encourage the formation of larger sized solid particles; also, a portion of the aqueous sediment from the settling device is continuously mechanically dewatered and then removed from the system. The liquid effluent solution from the settling device is passed to a solids-contacting and reaction device for mixing with sodium carbonate in order to reduce the calcium ion concentration and the solids content of the solution. The underflow of the solids-contacting device is conveyed back to the causticizing zone and the clarified overflow, i.e., the regenerated scrubbing liquor, is conveyed to the absorption apparatus.

  11. 40 CFR 50.5 - National secondary ambient air quality standard for sulfur oxides (sulfur dioxide).

    Science.gov (United States)

    2010-07-01

    ... standard for sulfur oxides (sulfur dioxide). 50.5 Section 50.5 Protection of Environment ENVIRONMENTAL....5 National secondary ambient air quality standard for sulfur oxides (sulfur dioxide). (a) The level... than 0.05 ppm shall be rounded up). (b) Sulfur oxides shall be measured in the ambient air as...

  12. 40 CFR 50.17 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Science.gov (United States)

    2010-07-01

    ... standards for sulfur oxides (sulfur dioxide). 50.17 Section 50.17 Protection of Environment ENVIRONMENTAL....17 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). (a) The level of the national primary 1-hour annual ambient air quality standard for oxides of sulfur is 75...

  13. Graphene-sulfur nanocomposites for rechargeable lithium-sulfur battery electrodes

    Science.gov (United States)

    Liu, Jun; Lemmon, John P; Yang, Zhenguo; Cao, Yuiliang; Li, Xiaolin

    2014-06-17

    Rechargeable lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter less than 50 nm..

  14. Dazhou Becomes China's Sulfur Base

    Institute of Scientific and Technical Information of China (English)

    Zhang He

    2008-01-01

    @@ Located at the juncture of Sichuan, Hubei, Shaanxi provinces and Chongqing municipality, Dazhou,which is a city in the eastem part of Southwest China's Sichuan Province and has convenient transport facilities, boasts natural gas reserves of 3.8 trillion cubic meters, of which 660 billion cubic meters have been found. It will make full use of its natural gas reserves to build Asia's largest sulfur producing base by 2010 when its annual sulfur output is expected to surpass 4 million tons.

  15. Plant sulfur and Big Data.

    Science.gov (United States)

    Kopriva, Stanislav; Calderwood, Alexander; Weckopp, Silke C; Koprivova, Anna

    2015-12-01

    Sulfur is an essential mineral nutrient for plants, therefore, the pathways of its uptake and assimilation have been extensively studied. Great progress has been made in elucidation of the individual genes and enzymes and their regulation. Sulfur assimilation has been intensively investigated by -omics technologies and has been target of several genome wide genetic approaches. This brought a significant step in our understanding of the regulation of the pathway and its integration in cellular metabolism. However, the large amount of information derived from other experiments not directly targeting sulfur has also brought new and exciting insights into processes affecting sulfur homeostasis. In this review we will integrate the findings of the targeted experiments with those that brought unintentional progress in sulfur research, and will discuss how to synthesize the large amount of information available in various repositories into a meaningful dissection of the regulation of a specific metabolic pathway. We then speculate how this might be used to further advance knowledge on control of sulfur metabolism and what are the main questions to be answered. PMID:26706053

  16. Optimizing stratospheric sulfur geoengineering by seasonally changing sulfur injections

    Science.gov (United States)

    Laakso, Anton; Partanen, Antti-Ilari; Kokkola, Harri; Lehtinen, Kari; Korhonen, Hannele

    2015-04-01

    Solar radiation management (SRM) by stratospheric sulfur injection has been shown to have potential in counteracting global warming if reducing of greenhouse gases has not been achieved fast enough and if climate warming will continue. Injecting large amounts of sulfate particles to the stratosphere would increase the reflectivity of the atmosphere and less sunlight would reach the surface. However, the effectivity (per injected sulphur mass unit) of this kind of geoengineering would decrease when amount of injected sulfur is increased. When sulfur concentration increases, stratospheric particles would grow to larger sizes which have larger gravitational settling velocity and which do not reflect radiation as efficiently as smaller particles. In many previous studies, sulfur has been assumed to be injected along the equator where yearly mean solar intensity is the highest and from where sulfur is spread equally to both hemispheres. However, the solar intensity will change locally during the year and sulfate has been assumed to be injected and spread to the hemisphere also during winter time, when the solar intensity is low. Thus sulfate injection could be expected to be more effective, if sulfur injection area is changed seasonally. Here we study effects of the different SRM injection scenarios by using two versions of the MPI climate models. First, aerosol spatial and temporal distributions as well as the resulting radiative properties from the SRM are defined by using the global aerosol-climate model ECHAM6.1-HAM2.2-SALSA. After that, the global and regional climate effects from different injection scenarios are predicted by using the Max Planck Institute's Earth System Model (MPI-ESM). We carried out simulations, where 8 Tg of sulfur is injected as SO2 to the stratosphere at height of 20-22 km in an area ranging over a 20 degree wide latitude band. Results show that changing the sulfur injection area seasonally would lead to similar global mean shortwave

  17. Bacterial Hydrodynamics

    Science.gov (United States)

    Lauga, Eric

    2016-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells, yet they represent the bulk of the world's biomass and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micrometer scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically complex environments. Using hydrodynamics as an organizing framework, I review the biomechanics of bacterial motility and look ahead to future challenges.

  18. Bacterial hydrodynamics

    CERN Document Server

    Lauga, Eric

    2015-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells yet they represent the bulk of the world's biomass, and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds-number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micron scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically-complex environments. Using hydrodynamics as an organizing framework, we review the biomechanics of bacterial motility and look ahead to future challenges.

  19. Interactions of selected bacterial isolates with DBT and solubilized coal

    Energy Technology Data Exchange (ETDEWEB)

    Key, D.H.; Fox, R.V.; Kase, R.S.; Willey, M.S.; Stoner, D.L.; Ward, T.E.

    1990-01-01

    We are studying the interactions of isolated bacteria with dibenzothiophene (DBT), a sulfur-containing model compound, and with a solubilized coal product derived from a high-organic-sulfur lignite. The sensitivity of the tetrazolium assay used to identify and study these strains was improved by substituting tetrazolium violet for triphenyltetrazolium. DBT metabolism by thirteen strains was investigated using qualitative and quantitative GC and GC-MS analyses. Growth medium and incubation time affect the extent of DBT degradation and the production of DBT metabolites. Under specific conditions, seven of the strains produce metabolites which elute close to the position of one or another of the biphenyl standards. However, when these samples are spiked with the standard compounds, the bacterial metabolites do not co-elute with the standards. The modification of solubilized high-organic-sulfur coal by six of these strains was also studied. No selective removal of sulfur relative to carbon was observed. 13 refs., 1 fig., 2 tabs.

  20. Comprehensive phylogenetic analysis of bacterial reverse transcriptases.

    Directory of Open Access Journals (Sweden)

    Nicolás Toro

    Full Text Available Much less is known about reverse transcriptases (RTs in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs, Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L, and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology.

  1. Bacterial Mobilization of Nutrients From Biochar-Amended Soils.

    Science.gov (United States)

    Schmalenberger, A; Fox, A

    2016-01-01

    Soil amendments with biochar to improve soil fertility and increase soil carbon stocks have received some high-level attention. Physical and chemical analyses of amended soils and biochars from various feedstocks are reported, alongside some evaluations of plant growth promotion capabilities. Fewer studies investigated the soil microbiota and their potential to increase cycling and mobilization of nutrients in biochar-amended soils. This review is discussing the latest findings in the bacterial contribution to cycling and mobilizing nitrogen, phosphorus, and sulfur in biochar-amended soils and potential contributions to plant growth promotion. Depending on feedstock, pyrolysis, soil type, and plant cover, changes in the bacterial community structure were observed for a majority of the studies using amplicon sequencing or genetic fingerprinting methods. Prokaryotic nitrification largely depends on the availability of ammonium and can vary considerably under soil biochar amendment. However, denitrification to di-nitrogen and in particular, nitrous oxide reductase activity is commonly enhanced, resulting in reduced nitrous oxide emissions. Likewise, bacterial fixation of di-nitrogen appears to be regularly enhanced. A paucity of studies suggests that bacterial mobilization of phosphorus and sulfur is enhanced as well. However, most studies only tested for extracellular sulfatase and phosphatase activity. Further research is needed to reveal details of the bacterial nutrient mobilizing capabilities and this is in particular the case for the mobilization of phosphorus and sulfur. PMID:26917243

  2. Microbial extraction of sulfur from model coal organosulfur compounds

    Energy Technology Data Exchange (ETDEWEB)

    Purdy, R.F.; Ward, B.; Lepo, J.E. [Mississippi Univ., University, MS (United States)

    1991-12-31

    Several hundred bacterial cultures isolated from a variety of natural sites were screened for their ability to desulfurize the model coal organosulfur compounds, dibenzothiophene (DBT) and DBT-sulfone. A sulfur-stress assay, in which DBT-sulfone was the only bioavailable source of sulfur, was used to screen and select for organisms that selectively desulfurized the organic-sulfur substrate. Only two new isolates, UMX9 and UMX3, and strain IGTS-8, a Rhodococcus rhodochrous provided by the Institute for Gas Technology (Chicago, USA.) as a reference culture, would grow on DBT or DBT-sulfone as a sole source of sulfur. Under sulfur-stress conditions, a desulfurized product identified as 2-hydroxybiphenyl (2-phenylphenol) was detected only for UMX9 and IGTS-8. Biodesulfurization activity for all three organisms occurred only for growing cultures, and was depressed by free sulfate, although more so for UMX3 and IGTS-8 than for UMX9. None of the three cultures exhibited good growth on DBT, DBT-sulfone, or 2-phenylphenol as sole sources of carbon. Taxonomic studies revealed UMX3 to be similar to IGTS-8, whereas UMX9 only exhibited Rhodococcus-like features. Comparative tests for carbohydrate utilization revealed that only UMX9 would grow on glucose, and that only IGTS-8 would grow on L-arabinose. Assays of biodesulfurization activity as a function of temperature or pH revealed further differences between UMX9 and UMX3/IGTS-8. Under optimized assay conditions for each organism, UMX9 exhibited up to 30% greater biodesulfurization activity than did IGTS-8 and UMX3, which were similar in activity.

  3. Sulfur-doped ordered mesoporous carbons: A stability-improving sulfur host for lithium-sulfur battery cathodes

    Science.gov (United States)

    Nitze, Florian; Fossum, Kjell; Xiong, Shizhao; Matic, Aleksandar; Palmqvist, Anders E. C.

    2016-06-01

    We report on sulfur-functionalized ordered mesoporous carbons aimed for lithium-sulfur battery electrode applications with improved charge capacity retention. The carbons were obtained by a hard-template strategy using a mixture of furfuryl alcohol and furfuryl mercaptan. For the application as electrode material in lithium-sulfur batteries, the carbons were additionally loaded with sulfur following a traditional melt-diffusion approach. It was found that the sulfur interacts stronger with the sulfur-functionalized carbon matrix than with the non-functionalized material. Electrodes showed very high capacity in the second discharge-charge cycle amounting to approximately 1500, 1200 and 1400 mAh/g (sulfur) for carbon materials with no, medium and high degrees of sulfur functionalization, respectively. More importantly, the sulfur-functionalization of the carbon was found to increase the capacity retention after 50 discharge-charge cycles by 8 and 5% for the carbons with medium and high degrees of sulfur-functionalization, respectively, compared to carbon with no sulfur-functionalization. We attribute this significant improvement to the presence of covalently bound sulfur groups at the internal surface of the functionalized carbon providing efficient anchoring sites for catenation to the sulfur loaded into the pores of the carbons and provide experimental support for this in the form of results from cyclic voltammetry and X-ray photoelectron spectroscopy.

  4. Dimethylmercury Formation Mediated by Inorganic and Organic Reduced Sulfur Surfaces

    OpenAIRE

    Sofi Jonsson; Nashaat M. Mazrui; Mason, Robert P.

    2016-01-01

    Underlying formation pathways of dimethylmercury ((CH3)2Hg) in the ocean are unknown. Early work proposed reactions of inorganic Hg (HgII) with methyl cobalamin or of dissolved monomethylmercury (CH3Hg) with hydrogen sulfide as possible bacterial mediated or abiotic pathways. A significant fraction (up to 90%) of CH3Hg in natural waters is however adsorbed to reduced sulfur groups on mineral or organic surfaces. We show that binding of CH3Hg to such reactive sites facilitates the formation of...

  5. 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.

  6. Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry for quick detection of sulfur-oxidizing bacteria in environmental water samples

    Science.gov (United States)

    Sun, Chengjun; Jiang, Fenghua; Gao, Wei; Li, Xiaoyun; Yu, Yanzhen; Yin, Xiaofei; Wang, Yong; Ding, Haibing

    2016-03-01

    Detection of sulfur-oxidizing bacteria has largely been dependent on targeted gene sequencing technology or traditional cell cultivation, which usually takes from days to months to carry out. This clearly does not meet the requirements of analysis for time-sensitive samples and/or complicated environmental samples. Since energy-dispersive X-ray spectrometry (EDS) can be used to simultaneously detect multiple elements in a sample, including sulfur, with minimal sample treatment, this technology was applied to detect sulfur-oxidizing bacteria using their high sulfur content within the cell. This article describes the application of scanning electron microscopy imaging coupled with EDS mapping for quick detection of sulfur oxidizers in contaminated environmental water samples, with minimal sample handling. Scanning electron microscopy imaging revealed the existence of dense granules within the bacterial cells, while EDS identified large amounts of sulfur within them. EDS mapping localized the sulfur to these granules. Subsequent 16S rRNA gene sequencing showed that the bacteria detected in our samples belonged to the genus Chromatium, which are sulfur oxidizers. Thus, EDS mapping made it possible to identify sulfur oxidizers in environmental samples based on localized sulfur within their cells, within a short time (within 24 h of sampling). This technique has wide ranging applications for detection of sulfur bacteria in environmental water samples.

  7. Monoclinic sulfur cathode utilizing carbon for high-performance lithium-sulfur batteries

    Science.gov (United States)

    Jung, Sung Chul; Han, Young-Kyu

    2016-09-01

    Sulfur cathodes for lithium-sulfur batteries have been designed to be combined with conductive carbon because the insulating nature of sulfur causes low active material utilization and poor rate capability. This paper is the first to report that carbon can induce a phase transition in a sulfur cathode. The stable form of a sulfur crystal at ambient temperature is orthorhombic sulfur. We found that monoclinic sulfur becomes more stable than orthorhombic sulfur if carbon atoms penetrate into the sulfur at elevated temperatures and the carbon density exceeds a threshold of C0.3S8. The high stability of the carbon-containing monoclinic sulfur persists during lithiation and is attributed to locally formed linear SC3S chains with marked stability. This study provides a novel perspective on the role of carbon in the sulfur cathode and suggests control of the crystal phase of electrodes by composite elements as a new way of designing efficient electrode materials.

  8. Thermodynamic analysis of ANS binding to partially unfolded α-lactalbumin: correlation of endothermic to exothermic changeover with formation of authentic molten globules.

    Science.gov (United States)

    Kim, Ki Hyung; Yun, Soi; Mok, K H; Lee, E K

    2016-09-01

    A fluorescent reporter, 8-anilino-1-naphthalene sulfonic acid (ANS), can serve as a reference molecule for conformational transition of a protein because its aromatic carbons have strong affinity with hydrophobic cores of partially unfolded molten globules. Using a typical calcium-binding protein, bovine α-lactalbumin (BLA), as a model protein, we compared the ANS binding thermodynamics to the decalcified (10 mM EDTA treated) apo-BLA at two representative temperatures: 20 and 40 °C. This is because the authentic molten globule is known to form more heavily at an elevated temperature such as 40 °C. Isothermal titration calorimetry experiments revealed that the BLA-ANS interactions at both temperatures were entropy-driven, and the dissociation constants were similar on the order of 10(-4)  M, but there was a dramatic changeover in the binding thermodynamics from endothermic at 20 °C to exothermic at 40 °C. We believe that the higher subpopulation of authentic molten globules at 40 °C than 20 °C would be responsible for the results, which also indicate that weak binding is sufficient to alter the ANS binding mechanisms. We expect that the thermodynamic properties obtained from this study would serve as a useful reference for investigating the binding of other hydrophobic ligands such as oleic acid to apo-BLA, because oleic acid is known to have tumor-selective cytotoxicity when complexed with partially unfolded α-lactalbumin. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27060481

  9. Biochemical mechanisms for the desulfurization of coal-relevant organic sulfur compounds

    Energy Technology Data Exchange (ETDEWEB)

    Afferden, M. van; Tappe, D.; Beyer, M.; Trueper, H.G.; Klein, J. (DMT-Gesellschaft fuer Forschung und Pruefung mbH, Essen (Germany))

    1993-12-01

    Two microbial strains ([ital Brevibacterium] sp. DO, [ital Pseudomonas aeruginosa] OS1) were isolated for their ability to desulfurize dibenzothiophene (DBT) and benzyl methyl sulfide (BMS). Enrichment was achieved by a sulfur-selective screening system using the model compounds as the sole source of sulfur for bacterial growth. [ital Brevibacterium] sp. DO utilizes DBT as a sole source of sulfur, carbon and energy for growth, whereas [ital Pseudomonas aeruginosa] OS1 metabolizes BMS to only a small extent under sulfur-selective conditions. Investigations of the regulation of enzymes involved in the desulfurization of coal-relevant sulfur compounds indicate that in nature at least two mechanisms exist: 'carbon regulation' and 'sulfur regulation'. The biochemical mechanisms leading to the desulfurization of BMS and DBT are similar. The sulfur atom of both compounds is initially oxidized to the corresponding sulfone, and cleavage of the C-S bond proceeds via the formation of a chemically unstable hemimercaptal (S-oxidized form) by oxidation of the carbon atom adjacent to the sulfur atom. These results indicate that oxidation of sulfur to its highest oxidation state may be the precondition for the oxidative cleavage of the covalent C-S bonds. By isotope-labelling experiments using [sup 18]O[sub 2], the initial enzymes were identified as sulfoxygenases that use molecular oxygen. Cleavage of the C-S bond of DBT and BMS leads to the formation of organic sulfinic acids as intermediates. With DBT the sulfinic acid is desulfurized probably by hydrolysis; this results in the formation of sulfite and benzoate. The desulfurization of BMS proceeds by sulfonic acid-oxidation. The applicability of these biochemical mechanisms to the microbial desulfurization of coal is discussed. 39 refs., 10 figs., 2 tabs.

  10. Microbial Sulfur Geochemistry in Mine Systems (Invited)

    Science.gov (United States)

    Warren, L. A.; Norlund, K. L.; Hitchcock, A.

    2010-12-01

    Acid mine drainage (AMD), metal laden, acidic water, is the most pressing mining environmental issue on a global scale. While it is well recognized that the activity of autotrophic Fe and S bacteria amplify the oxidation of the sulfidic wastes, thereby generating acidity and leaching metals; the underlying microbial geochemistry is not well described. This talk will highlight results revealing the importance of microbial cooperation associated with a novel sulfur-metabolizing consortium enriched from mine waters. Results generated by an integrated approach, combining field characterization, geochemical experimentation, scanning transmission X-ray microscopy (STXM), and fluorescence in situ hybridization (FISH) [1]describing the underlying ecological drivers, the functionally relevant biogeochemical architecture of the consortial macrostructure as well as the identities of this environmental sulphur redox cycling consortium will be presented. The two common mine bacterial strains involved in this consortium, Acidithiobacillus ferroxidans and Acidiphilium sp., are specifically spatially segregated within a macrostructure (pod) of extracellular polymeric substance (EPS) that enables coupled sulphur oxidation and reduction reactions despite bulk, oxygenated conditions. Identical pod formation by type culture strains was induced and linked to ecological conditions. The proposed sulphur geochemistry associated with this bacterial consortium produces 40-90% less acid than expected based on abiotic AMD models, with implications for both AMD mitigation and AMD carbon flux modeling. We are currently investigating the implications of these sulphur-processing pods for metal dynamics in mine systems. These results demonstrate how microbes can orchestrate their geochemical environment to facilitate metabolism, and underscore the need to consider microbial interactions and ecology in constraining their geochemical impacts. [1] Norlund, Southam, Tyliszcczak, Hu, Karunakaran, Obst

  11. Comparative Genomics of Green Sulfur Bacteria

    DEFF Research Database (Denmark)

    Ussery, David; Davenport, C; Tümmler, B

    2010-01-01

    Eleven completely sequenced Chlorobi genomes were compared in oligonucleotide usage, gene contents, and synteny. The green sulfur bacteria (GSB) are equipped with a core genome that sustains their anoxygenic phototrophic lifestyle by photosynthesis, sulfur oxidation, and CO(2) fixation. Whole...

  12. Sulfur Speciation in the Martian Regolith Component in Shergottite Glasses

    Science.gov (United States)

    Rao, M. N.; Nyquist, Laurence E.; Sutton, S.; Huth, J.

    2009-01-01

    We have shown that Gas-Rich Impact-Melt (GRIM) glasses in Shergotty, Zagami, and EET79001 (Lith A and Lith B) contain Martian regolith components that were molten during impact and quenched into glasses in voids of host rock materials based on neutron-capture isotopes, i.e., Sm-150 excesses and Sm-149 deficits in Sm, and Kr-80 excesses produced from Br [1, 2]. These GRIM glasses are rich in S-bearing secondary minerals [3.4]. Evidence for the occurrence of CaSO4 and S-rich aluminosilicates in these glasses is provided by CaO-SO3 and Al2O3-SO3 correlations, which are consistent with the finding of gypsum laths protruding from the molten glass in EET79001 (Lith A) [5]. However, in the case of GRIM glasses from EET79001 (Lith B), Shergotty and Zagami, we find a different set of secondary minerals that show a FeO-SO3 correlation (but no MgOSO3 correlation), instead of CaO-SO3 and Al2O3-SO3 correlations observed in Lith A. These results might indicate different fluidrock interactions near the shergottite source region on Mars. The speciation of sulfur in these salt assemblages was earlier studied by us using XANES techniques [6], where we found that Lith B predominantly contains Fe-sulfide globules (with some sulfate). On the other hand, Lith A showed predominantly Casulfite/ sulfate with some FeS. Furthermore, we found Fe to be present as Fe2+ indicating little oxidation, if any, in these glasses. To examine the sulfide-sulfate association in these glasses, we studied their Fe/Ni ratios with a view to find diagnostic clues for the source fluid. The Fe-sulfide mineral (Fe(0.93)Ni(0.3)S) in EET79001, Lith A is pyrrhotite [7, 8]. It yields an Fe/Ni ratio of 31. In Shergotty, pyrrhotite occurs with a molar ratio of Fe:S of 0.94 and a Ni abundance of 0.12% yielding a Fe/Ni ratio of approx.500 [8]. In this study, we determined a NiO content of approx.0.1% and FeO/NiO ratio of approx.420 in S-rich globules in #507 (EET79001, Lith B) sample using FE-SEM. In the same sample

  13. Ionization fraction and the enhanced sulfur chemistry in Barnard 1

    Science.gov (United States)

    Fuente, A.; Cernicharo, J.; Roueff, E.; Gerin, M.; Pety, J.; Marcelino, N.; Bachiller, R.; Lefloch, B.; Roncero, O.; Aguado, A.

    2016-09-01

    Context. Barnard B1b has been revealed as one of the most interesting globules from the chemical and dynamical point of view. It presents a rich molecular chemistry characterized by large abundances of deuterated and complex molecules. Furthermore, this globule hosts an extremely young Class 0 object and one candidate for the first hydrostatic core (FHSC) proving the youth of this star-forming region. Aims: Our aim is to determine the cosmic ray ionization rate, ζH2, and the depletion factors in this extremely young star-forming region. These parameters determine the dynamical evolution of the core. Methods: We carried out a spectral survey toward Barnard 1b as part of the IRAM large program "IRAM Chemical survey of sun-like star-forming regions" (ASAI) using the IRAM 30-m telescope at Pico Veleta (Spain). This provided a very complete inventory of neutral and ionic C-, N-, and S- bearing species with, from our knowledge, the first secure detections of the deuterated ions DCS+ and DOCO+. We use a state-of-the-art pseudo-time-dependent gas-phase chemical model that includes the ortho and para forms of H2, H, D, H, H2D+, D2H+, D2, and D to determine the local value of the cosmic ray ionization rate and the depletion factors. Results: Our model assumes n(H2) = 105 cm-3 and Tk = 12 K, as derived from our previous works. The observational data are well fitted with ζH2 between 3 × 10-17 s-1 and 10-16 s-1 and the elemental abundances O/H = 3 × 10-5, N/H = 6.4-8 × 10-5, C/H = 1.7 × 10-5, and S/H between 6.0 × 10-7 and 1.0 × 10-6. The large number of neutral/protonated species detected allows us to derive the elemental abundances and cosmic ray ionization rate simultaneously. Elemental depletions are estimated to be ~10 for C and O, ~1 for N, and ~25 for S. Conclusions: Barnard B1b presents similar depletions of C and O as those measured in prestellar cores. The depletion of sulfur is higher than that of C and O, but not as extreme as in cold cores. In fact, it is

  14. Effect of Lenient Steam Injection (LSI) heat treatment of bovine milk on the activities of some enzymes, the milk fat globule and pH

    DEFF Research Database (Denmark)

    Dickow, Jonathan Ahrens; Thorup Nielsen, Martin; Hammershøj, Marianne

    2012-01-01

    This study investigated the effects of Lenient Steam Injection (LSI) treatment at temperatures 70–150 C on the enzymatic activities of the indigenous milk enzymes alkaline phosphatase, lactoperoxidase (LPO), xanthine oxidase (XO), lipoprotein lipase (LPL) and plasmin in comparison with two...... reference heat treatments of 63 C for 30 s and of 72 C for 15 s by indirect heating. Milk fat globule (MFG) size distributions and pH were also monitored. Alkaline phosphatase, LPO, XO and LPL activities decreased with increasing LSI temperature. Plasmin activity was increased at temperatures <80 C and...

  15. The sulfur cycle in the marine atmosphere

    Science.gov (United States)

    Toon, Owen B.; Kasting, James F.; Turco, Richard P.; Liu, May S.

    1987-01-01

    The simulation of the sulfur cycle in the marine atmosphere using a one-dimensional photochemical model is described and evaluated. Theoretical uncertainties concerning the operation of the marine sulfur cycle are examined, and measurements of sulfur gases in the marine atmosphere necessary for developing the model are derived. Previous modeling studies are reviewed, and the data from these studies are compared to the model simulations. Recommendations for improving the simulation of the sulfur cycle in the marine atmosphere are discussed.

  16. Sulfur monochloride in organic synthesis

    International Nuclear Information System (INIS)

    The data on the reactivity of sulfur monochloride published in the past 15 years have been reviewed and systematized. The review focuses on the synthesis of acyclic and heterocyclic compounds with the use of S2Cl2. The bibliography includes 154 references

  17. 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

  18. Sulfur: its clinical and toxicologic aspects.

    Science.gov (United States)

    Komarnisky, Lioudmila A; Christopherson, Robert J; Basu, Tapan K

    2003-01-01

    Although there is no known dietary requirement for inorganic sulfur, it is an essential element for all animal species in as much as they all require the sulfur-containing amino acid methionine. There are three predominate forms of organic sulfur in animals and humans: 1). the thiomethyl of methionine residues in protein; 2). the sulfhydryl disulfides of protein; and 3). the compounds containing ester or amide bound sulfates of glycosaminoglycans, steroids, and many xenobiotic metabolites. Thus, sulfur becomes an important constituent of amino acids, proteins, enzymes, vitamins and other biomolecules. Unlike mammalian species, plants can use inorganic sulfur and synthesize methionine from which are synthesized all the other important sulfur compounds. Hence, sulfur deficiency occurs mainly when plants are grown in sulfur-depleted soils and when humans and animals consume low-protein diets. In recent times, however, the increasing prevalence of refining petroleum and smelting sulfur compounds of metallic minerals into free metals are having a large impact on the balance of sulfur in the environment. Sulfur toxicity is associated mainly with high levels of the element and its toxic volatile substances in the environment. Sulfur dioxide (SO(2)), a major air pollutant, may adversely affect animal and human health by causing bronchitis, bronchoconstriction, and increased pulmonary resistance.

  19. Rhodanese functions as sulfur supplier for key enzymes in sulfur energy metabolism.

    Science.gov (United States)

    Aussignargues, Clément; Giuliani, Marie-Cécile; Infossi, Pascale; Lojou, Elisabeth; Guiral, Marianne; Giudici-Orticoni, Marie-Thérèse; Ilbert, Marianne

    2012-06-01

    How microorganisms obtain energy is a challenging topic, and there have been numerous studies on the mechanisms involved. Here, we focus on the energy substrate traffic in the hyperthermophilic bacterium Aquifex aeolicus. This bacterium can use insoluble sulfur as an energy substrate and has an intricate sulfur energy metabolism involving several sulfur-reducing and -oxidizing supercomplexes and enzymes. We demonstrate that the cytoplasmic rhodanese SbdP participates in this sulfur energy metabolism. Rhodaneses are a widespread family of proteins known to transfer sulfur atoms. We show that SbdP has also some unusual characteristics compared with other rhodaneses; it can load a long sulfur chain, and it can interact with more than one partner. Its partners (sulfur reductase and sulfur oxygenase reductase) are key enzymes of the sulfur energy metabolism of A. aeolicus and share the capacity to use long sulfur chains as substrate. We demonstrate a positive effect of SbdP, once loaded with sulfur chains, on sulfur reductase activity, most likely by optimizing substrate uptake. Taken together, these results lead us to propose a physiological role for SbdP as a carrier and sulfur chain donor to these key enzymes, therefore enabling channeling of sulfur substrate in the cell as well as greater efficiency of the sulfur energy metabolism of A. aeolicus. PMID:22496367

  20. Novel Nitrocellulose Made from Bacterial Cellulose

    Science.gov (United States)

    Sun, Dong-Ping; Ma, Bo; Zhu, Chun-Lin; Liu, Chang-Sheng; Yang, Jia-Zhi

    2010-04-01

    Nitrocellulose (NC) is useful in several industrial segments, especially in the production of gun, rocket, and missile propellants. The conventional way to prepare NC is done through the nitration of plant cellulose with nitric acid. In this work, bacterial cellulose nitrate (NBC) is synthesized by bacterial cellulose (BC) and nitro-sulfric acid under heterogeneous conditions. NBC with the degree of substitution (DS) of 1-2.85 was obtained, and the effects of sulfuric to nitric ratio, reaction temperature, and reaction time on the value of DS of NBC are discussed. The samples are also characterized by elemental analysis, thermal analysis, Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction.

  1. Sulfur geochemistry and microbial sulfate reduction during low-temperature alteration of uplifted lower oceanic crust: Insights from ODP Hole 735B

    Science.gov (United States)

    Alford, Susan E.; Alt, Jeffrey C.; Shanks, Wayne C., III

    2011-01-01

    Sulfide petrography plus whole rock contents and isotope ratios of sulfur were measured in a 1.5 km section of oceanic gabbros in order to understand the geochemistry of sulfur cycling during low-temperature seawater alteration of the lower oceanic crust, and to test whether microbial effects may be present. Most samples have low SO4/ΣS values (≤ 0.15), have retained igneous globules of pyrrhotite ± chalcopyrite ± pentlandite, and host secondary aggregates of pyrrhotite and pyrite laths in smectite ± iron-oxyhydroxide ± magnetite ± calcite pseudomorphs of olivine and clinopyroxene. Compared to fresh gabbro containing 100–1800 ppm sulfur our data indicate an overall addition of sulfide to the lower crust. Selection of samples altered only at temperatures ≤ 110 °C constrains microbial sulfate reduction as the only viable mechanism for the observed sulfide addition, which may have been enabled by the production of H2 from oxidation of associated olivine and pyroxene. The wide range in δ34Ssulfide values (− 1.5 to + 16.3‰) and variable additions of sulfide are explained by variable εsulfate-sulfide under open system pathways, with a possible progression into closed system pathways. Some samples underwent oxidation related to seawater penetration along permeable fault horizons and have lost sulfur, have high SO4/ΣS (≥ 0.46) and variable δ34Ssulfide (0.7 to 16.9‰). Negative δ34Ssulfate–δ34Ssulfide values for the majority of samples indicate kinetic isotope fractionation during oxidation of sulfide minerals. Depth trends in sulfide–sulfur contents and sulfide mineral assemblages indicate a late-stage downward penetration of seawater into the lower 1 km of Hole 735B. Our results show that under appropriate temperature conditions, a subsurface biosphere can persist in the lower oceanic crust and alter its geochemistry.

  2. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    Management of bacterial infections is becoming increasingly difficult due to the emergence and increasing prevalence of bacterial pathogens that are resistant to available antibiotics. Conventional antibiotics generally kill bacteria by interfering with vital cellular functions, an approach that ...

  3. Effect of different sulfur levels from various sources on brassica napus growth and soil sulfur fractions

    International Nuclear Information System (INIS)

    A two year field study was conducted at two different locations in northern rain fed Punjab, Pakistan to assess the effect of different rates of sulfur application from various sources on soil sulfur fractions and growth of Brassica napus. The treatments included three sulfur sources i. e., single super phosphate, ammonium sulfate and gypsum each applied at five different rates (0, 10, 20, 30 and 40 kg S ha/sup -1/ ). Sulfur application had a significant positive effect on the growth and yield parameters of Brassica napus. Among the sulfur sources ammonium sulfate resulted in maximum increase in plant growth and yield parameters, followed by single super phosphate. Sulfur content and uptake by crop plants was significantly higher with ammonium sulfate application as compared to other two sulfur sources. Sulfur application also exerted a significant positive effect on different S fractions in the soils. On an average, 18.0% of the applied sulfur got incorporated into CaCl/sub 2/ extractable sulfur fraction, while 15.6% and 35.5% entered into adsorbed and organic sulfur fractions in the soils, respectively. The value cost ratio increased significantly by sulfur application up to 30 kg ha/sup -1/. Among sulfur sources, ammonium sulfate performed best giving the highest net return. (author)

  4. Genomic analysis reveals versatile heterotrophic capacity of a potentially symbiotic sulfur-oxidizing bacterium in sponge.

    Science.gov (United States)

    Tian, Ren-Mao; Wang, Yong; Bougouffa, Salim; Gao, Zhao-Ming; Cai, Lin; Bajic, Vladimir; Qian, Pei-Yuan

    2014-11-01

    Sulfur-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) play essential roles in marine sponges. However, the detailed characteristics and physiology of the bacteria are largely unknown. Here, we present and analyse the first genome of sponge-associated SOB using a recently developed metagenomic binning strategy. The loss of transposase and virulence-associated genes and the maintenance of the ancient polyphosphate glucokinase gene suggested a stabilized SOB genome that might have coevolved with the ancient host during establishment of their association. Exclusive distribution in sponge, bacterial detoxification for the host (sulfide oxidation) and the enrichment for symbiotic characteristics (genes-encoding ankyrin) in the SOB genome supported the bacterial role as an intercellular symbiont. Despite possessing complete autotrophic sulfur oxidation pathways, the bacterium developed a much more versatile capacity for carbohydrate uptake and metabolism, in comparison with its closest relatives (Thioalkalivibrio) and to other representative autotrophs from the same order (Chromatiales). The ability to perform both autotrophic and heterotrophic metabolism likely results from the unstable supply of reduced sulfur in the sponge and is considered critical for the sponge-SOB consortium. Our study provides insights into SOB of sponge-specific clade with thioautotrophic and versatile heterotrophic metabolism relevant to its roles in the micro-environment of the sponge body.

  5. Genomic analysis reveals versatile heterotrophic capacity of a potentially symbiotic sulfur-oxidizing bacterium in sponge

    KAUST Repository

    Tian, Renmao

    2014-08-29

    Sulfur-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) play essential roles in marine sponges. However, the detailed characteristics and physiology of the bacteria are largely unknown. Here, we present and analyse the first genome of sponge-associated SOB using a recently developed metagenomic binning strategy. The loss of transposase and virulence-associated genes and the maintenance of the ancient polyphosphate glucokinase gene suggested a stabilized SOB genome that might have coevolved with the ancient host during establishment of their association. Exclusive distribution in sponge, bacterial detoxification for the host (sulfide oxidation) and the enrichment for symbiotic characteristics (genes-encoding ankyrin) in the SOB genome supported the bacterial role as an intercellular symbiont. Despite possessing complete autotrophic sulfur oxidation pathways, the bacterium developed a much more versatile capacity for carbohydrate uptake and metabolism, in comparison with its closest relatives (Thioalkalivibrio) and to other representative autotrophs from the same order (Chromatiales). The ability to perform both autotrophic and heterotrophic metabolism likely results from the unstable supply of reduced sulfur in the sponge and is considered critical for the sponge-SOB consortium. Our study provides insights into SOB of sponge-specific clade with thioautotrophic and versatile heterotrophic metabolism relevant to its roles in the micro-environment of the sponge body. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  6. Acidithiobacillus caldus Sulfur Oxidation Model Based on Transcriptome Analysis between the Wild Type and Sulfur Oxygenase Reductase Defective Mutant

    OpenAIRE

    Linxu Chen; Yilin Ren; Jianqun Lin; Xiangmei Liu; Xin Pang; Jianqiang Lin

    2012-01-01

    BACKGROUND: Acidithiobacillus caldus (A. caldus) is widely used in bio-leaching. It gains energy and electrons from oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs) for carbon dioxide fixation and growth. Genomic analyses suggest that its sulfur oxidation system involves a truncated sulfur oxidation (Sox) system (omitting SoxCD), non-Sox sulfur oxidation system similar to the sulfur oxidation in A. ferrooxidans, and sulfur oxygenase reductase (SOR). The complexity ...

  7. An integrated method incorporating sulfur-oxidizing bacteria and electrokinetics to enhance removal of copper from contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Maini, G.; Sharman, A.K.; Sunderland, G.; Knowles, C.J.; Jackman, S.A.

    2000-03-15

    The combination of bioleaching and electrokinetics for the remediation of metal contaminated land has been investigated. In bioleaching, bacteria convert reduced sulfur compounds to sulfuric acid, acidifying soil and mobilizing metal ions. In electrokinetics, DC current acidifies soil, and mobilized metals are transported to the cathode by electromigration. When bioleaching was applied to silt soil artificially contaminated with seven metals and amended with sulfur, bacterial activity was partially inhibited and limited acidification occurred. Electrokinetic treatment of silt soil contaminated solely with 1000 mg/kg copper nitrate showed 89% removal of copper from the soil within 15 days. To combine bioleaching and electrokinetics sequentially, preliminary partial acidification was performed by amending copper-contaminated soil with sulfur (to 5% w/w) and incubating at constant moisture (30% w/w) and temperature (20 C) for 90 days. Indigenous sulfur oxidizing bacteria partially acidified the soil from pH 8.1 to 5.4. This soil was then treated by electrokinetics yielding 86% copper removal in 16 days. In the combined process, electrokinetics stimulated sulfur oxidation, by removing inhibitory factors, yielding a 5.1-fold increase in soil sulfate concentration. Preacidification by sulfur-oxidizing bacteria increased the cost-effectiveness of the electrokinetic treatment by reducing the power requirement by 66%.

  8. Characterization of Chemosynthetic Microbial Mats Associated with Intertidal Hydrothermal Sulfur Vents in White Point, San Pedro, CA, USA.

    Science.gov (United States)

    Miranda, Priscilla J; McLain, Nathan K; Hatzenpichler, Roland; Orphan, Victoria J; Dillon, Jesse G

    2016-01-01

    The shallow-sea hydrothermal vents at White Point (WP) in Palos Verdes on the southern California coast support microbial mats and provide easily accessed settings in which to study chemolithoautotrophic sulfur cycling. Previous studies have cultured sulfur-oxidizing bacteria from the WP mats; however, almost nothing is known about the in situ diversity and activity of the microorganisms in these habitats. We studied the diversity, micron-scale spatial associations and metabolic activity of the mat community via sequence analysis of 16S rRNA and aprA genes, fluorescence in situ hybridization (FISH) microscopy and sulfate reduction rate (SRR) measurements. Sequence analysis revealed a diverse group of bacteria, dominated by sulfur cycling gamma-, epsilon-, and deltaproteobacterial lineages such as Marithrix, Sulfurovum, and Desulfuromusa. FISH microscopy suggests a close physical association between sulfur-oxidizing and sulfur-reducing genotypes, while radiotracer studies showed low, but detectable, SRR. Comparative 16S rRNA gene sequence analyses indicate the WP sulfur vent microbial mat community is similar, but distinct from other hydrothermal vent communities representing a range of biotopes and lithologic settings. These findings suggest a complete biological sulfur cycle is operating in the WP mat ecosystem mediated by diverse bacterial lineages, with some similarity with deep-sea hydrothermal vent communities. PMID:27512390

  9. Characterization of Chemosynthetic Microbial Mats Associated with Intertidal Hydrothermal Sulfur Vents in White Point, San Pedro, CA, USA

    Science.gov (United States)

    Miranda, Priscilla J.; McLain, Nathan K.; Hatzenpichler, Roland; Orphan, Victoria J.; Dillon, Jesse G.

    2016-01-01

    The shallow-sea hydrothermal vents at White Point (WP) in Palos Verdes on the southern California coast support microbial mats and provide easily accessed settings in which to study chemolithoautotrophic sulfur cycling. Previous studies have cultured sulfur-oxidizing bacteria from the WP mats; however, almost nothing is known about the in situ diversity and activity of the microorganisms in these habitats. We studied the diversity, micron-scale spatial associations and metabolic activity of the mat community via sequence analysis of 16S rRNA and aprA genes, fluorescence in situ hybridization (FISH) microscopy and sulfate reduction rate (SRR) measurements. Sequence analysis revealed a diverse group of bacteria, dominated by sulfur cycling gamma-, epsilon-, and deltaproteobacterial lineages such as Marithrix, Sulfurovum, and Desulfuromusa. FISH microscopy suggests a close physical association between sulfur-oxidizing and sulfur-reducing genotypes, while radiotracer studies showed low, but detectable, SRR. Comparative 16S rRNA gene sequence analyses indicate the WP sulfur vent microbial mat community is similar, but distinct from other hydrothermal vent communities representing a range of biotopes and lithologic settings. These findings suggest a complete biological sulfur cycle is operating in the WP mat ecosystem mediated by diverse bacterial lineages, with some similarity with deep-sea hydrothermal vent communities. PMID:27512390

  10. Characterization of Chemosynthetic Microbial Mats Associated with Intertidal Hydrothermal Sulfur Vents in White Point, San Pedro, CA, USA.

    Science.gov (United States)

    Miranda, Priscilla J; McLain, Nathan K; Hatzenpichler, Roland; Orphan, Victoria J; Dillon, Jesse G

    2016-01-01

    The shallow-sea hydrothermal vents at White Point (WP) in Palos Verdes on the southern California coast support microbial mats and provide easily accessed settings in which to study chemolithoautotrophic sulfur cycling. Previous studies have cultured sulfur-oxidizing bacteria from the WP mats; however, almost nothing is known about the in situ diversity and activity of the microorganisms in these habitats. We studied the diversity, micron-scale spatial associations and metabolic activity of the mat community via sequence analysis of 16S rRNA and aprA genes, fluorescence in situ hybridization (FISH) microscopy and sulfate reduction rate (SRR) measurements. Sequence analysis revealed a diverse group of bacteria, dominated by sulfur cycling gamma-, epsilon-, and deltaproteobacterial lineages such as Marithrix, Sulfurovum, and Desulfuromusa. FISH microscopy suggests a close physical association between sulfur-oxidizing and sulfur-reducing genotypes, while radiotracer studies showed low, but detectable, SRR. Comparative 16S rRNA gene sequence analyses indicate the WP sulfur vent microbial mat community is similar, but distinct from other hydrothermal vent communities representing a range of biotopes and lithologic settings. These findings suggest a complete biological sulfur cycle is operating in the WP mat ecosystem mediated by diverse bacterial lineages, with some similarity with deep-sea hydrothermal vent communities.

  11. Evidence for iron and sulfur enrichments in hydrothermal plumes at Axial Volcano following the January-February 1998 eruption

    Science.gov (United States)

    Feely, Richard A.; Baker, Edward T.; Lebon, Geoff T.; Gendron, James F.; Resing, Joseph A.; Cowen, James P.

    In response to 12 days of seismic activity at Axial Volcano, Juan de Fuca Ridge in January-February 1998, the NSF/NOAA-sponsored Axial Response Team conducted three response cruises in February, August, and August/September to map and sample hydrothermal plumes over the region. Vertical profiles of particulate Fe and S over the eruption site show high concentrations from about 1400 m to the bottom. Chemical and scanning electron microscope analysis of the February plume samples revealed anhydrite, Fe-ferrihydrites, elemental sulfur, and angular glassy basalt shards up to 190 µm in the longest dimension. Many of these shards had halite coatings, which is consistent with subseafloor basalt seawater reactions at temperatures >450°C at 1500 m depth. In August and September cruises the basalt shards were no longer present in the hydrothermal plumes. Instead, the plumes were predominantly composed of Fe-ferrihydrites, elemental sulfur, and sulfur filaments. A unique feature of this data set is the high concentrations of elemental sulfur in the lower 60 m of the water column. The sulfur results are suggestive of a significant enrichment of the bacterial biomass in the water column over the eruption site with time. Within the Axial caldera, approximately 10-20% of the total sulfur is present as sulfur filaments. These post-eruption particle compositional changes have strong similarities to the results from the 1993 CoAxial eruption on the Juan de Fuca Ridge.

  12. Reduced sulfur compound oxidation by Thiobacillus caldus.

    OpenAIRE

    Hallberg, K. B.; Dopson, M; Lindström, E B

    1996-01-01

    The oxidation of reduced inorganic sulfur compounds was studied by using resting cells of the moderate thermophile Thiobacillus caldus strain KU. The oxygen consumption rate and total oxygen consumed were determined for the reduced sulfur compounds thiosulfate, tetrathionate, sulfur, sulfide, and sulfite in the absence and in the presence of inhibitors and uncouplers. The uncouplers 2,4-dinitrophenol and carbonyl cyanide m-chlorophenyl-hydrazone had no affect on the oxidation of thiosulfate, ...

  13. HYDROCARBON AND SULFUR SENSORS FOR SOFC SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    A.M. Azad; Chris Holt; Todd Lesousky; Scott Swartz

    2003-11-01

    The following report summarizes work conducted during the Phase I program Hydrocarbon and Sulfur Sensors for SOFC Systems under contract No. DE-FC26-02NT41576. For the SOFC application, sensors are required to monitor hydrocarbons and sulfur in order to increase the operation life of SOFC components. This report discusses the development of two such sensors, one based on thick film approach for sulfur monitoring and the second galvanic based for hydrocarbon monitoring.

  14. Thiophenic Sulfur Compounds Released During Coal Pyrolysis.

    Science.gov (United States)

    Xing, Mengwen; Kong, Jiao; Dong, Jie; Jiao, Haili; Li, Fan

    2013-06-01

    Thiophenic sulfur compounds are released during coal gasification, carbonization, and combustion. Previous studies indicate that thiophenic sulfur compounds degrade very slowly in the environment, and are more carcinogenic than polycyclic aromatic hydrocarbons and nitrogenous compounds. Therefore, it is very important to study the principle of thiophenic sulfur compounds during coal conversion, in order to control their emission and promote clean coal utilization. To realize this goal and understand the formation mechanism of thiophenic sulfur compounds, this study focused on the release behavior of thiophenic sulfur compounds during coal pyrolysis, which is an important phase for all coal thermal conversion processes. The pyrolyzer (CDS-5250) and gas chromatography-mass spectrometry (Focus GC-DSQII) were used to analyze thiophenic sulfur compounds in situ. Several coals with different coal ranks and sulfur contents were chosen as experimental samples, and thiophenic sulfur compounds of the gas produced during pyrolysis under different temperatures and heating rates were investigated. Levels of benzothiophene and dibenzothiophene were obtained during pyrolysis at temperatures ranging from 200°C to 1300°C, and heating rates ranging from 6°C/ms to 14°C/ms and 6°C/s to 14°C/s. Moreover, the relationship between the total amount of benzothiophene and dibenzothiophene released during coal pyrolysis and the organic sulfur content in coal was also discussed. This study is beneficial for understanding the formation and control of thiophenic sulfur compounds, since it provides a series of significant results that show the impact that operation conditions and organic sulfur content in coal have on the amount and species of thiophenic sulfur compounds produced during coal pyrolysis. PMID:23781126

  15. Wound Healing of Cutaneous Sulfur Mustard Injuries

    OpenAIRE

    Graham, John S.; Chilcott, Robert P.; Rice, Paul; Milner, Stephen M.; Hurst, Charles G.; Maliner, Beverly I.

    2005-01-01

    Sulfur mustard is an alkylating chemical warfare agent that primarily affects the eyes, skin, and airways. Sulfur mustard injuries can take several months to heal, necessitate lengthy hospitalizations, and result in significant cosmetic and/or functional deficits. Historically, blister aspiration and/or deroofing (epidermal removal), physical debridement, irrigation, topical antibiotics, and sterile dressings have been the main courses of action in the medical management of cutaneous sulfur m...

  16. Prevention of bacterial adhesion

    DEFF Research Database (Denmark)

    Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria

    2010-01-01

    that imposes selection pressure for resistant bacteria. New approaches are urgently needed. Targeting bacterial virulence functions directly is an attractive alternative. An obvious target is bacterial adhesion. Bacterial adhesion to surfaces is the first step in colonization, invasion, and biofilm formation....... As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...

  17. Sulfur use efficiency ofradish as affected by sulfur source and rate in typic ustifluvent soil

    OpenAIRE

    M.V. Sriramachandrasekharan

    2012-01-01

    Radish is one of the most popular root crops inthe tropical and temperate regions. Sulfurdeficiency is common in coarse textured soildue to leachingloss. Rootyieldof radishis reportedtoincreasewith sulfur application.Fieldexperiments was conducted in two seasons to study theeffect of sulfur(S) rate and sourceon radish (Raphanus sativus L.) nutrition, an experimentwas conducted in aPadugai sandy clay loam(TypicUstifluvents) deficient in available sulfur. The treatmentsconsisted of four levels ...

  18. Hydrolysis of bovine and caprine milk fat globules by lipoprotein lipase. Effects of heparin and skim milk on lipase distribution and on lipolysis

    International Nuclear Information System (INIS)

    Heparin can dissociate lipoprotein lipase from casein micelles, and addition of heparin enhances lipolysis in bovine but not in caprine milk. Heparin shortened the lag-time for binding of lipoprotein lipase to milk fat globules and for lipolysis. Heparin counteracted the inhibitory effects of skim milk on binding of lipase and on lipolysis. Heparin stimulated lipolysis in all bovine milk samples when added before cooling and in spontaneously lipolytic milk samples also when added after cooling. Heparin enhanced lipolysis of isolated milk fat globules. Hence, its effect is not solely due to dissociation of lipoprotein lipase from the casein micelles. Cooling of goat milk caused more marked changes in the distribution of lipase than cooling of bovine milk; the fraction of added 125I-labeled lipase that bound to cream increased from about 8 to 60%. In addition, caprine skim milk caused less inhibition of lipolysis than bovine skim milk. These observations provide an explanation for the high degree of cold storage lipolysis in goat milk. Heparin had only small effects on the distribution of lipoprotein lipase in caprine milk, which explains why heparin has so little effect on lipolysis in caprine milk. The distribution of 35S-labeled heparin in bovine milk was studied. In warm milk less than 10% bound to the cream fraction, but when milk was cooled, binding of heparin to cream increased to 45%. These results suggest that there exists in the skim fraction a relatively small amount of a heparin-binding protein, which on cooling of milk adsorbs to the milk fat, or suggests that cooling induces a conformational change in a membrane protein such that its affinity for heparin increases

  19. Cholesterol Decreases the Size and the Mechanical Resistance to Rupture of Sphingomyelin Rich Domains, in Lipid Bilayers Studied as a Model of the Milk Fat Globule Membrane.

    Science.gov (United States)

    Murthy, Appala Venkata Ramana; Guyomarc'h, Fanny; Lopez, Christelle

    2016-07-01

    Sphingomyelin-rich microdomains have been observed in the biological membrane surrounding milk fat globules (MFGM). The role played by cholesterol in these domains and in the physical properties and functions of the MFGM remains poorly understood. The objective of this work was therefore to investigate the phase state, topography, and mechanical properties of MFGM polar lipid bilayers as a function of cholesterol concentration, by combining X-ray diffraction, atomic force microscopy imaging, and force spectroscopy. At room temperature, i.e. below the phase transition temperature of the MFGM polar lipids, the bilayers showed the formation of sphingomyelin-rich domains in the solid ordered (so) phase that protruded about 1 nm above the liquid disordered (ld) phase. These so phase domains have a higher mechanical resistance to rupture than the ld phase (30 nN versus 15 nN). Addition of cholesterol in the MFGM polar lipid bilayers (i) induced the formation of liquid ordered (lo) phase for up to 27 mol % in the bilayers, (ii) decreased the height difference between the thicker ordered domains and the surrounding ld phase, (iii) promoted the formation of small sized domains, and (iv) decreased the mechanical resistance to rupture of the sphingomyelin-rich domains down to ∼5 nN. The biological and functional relevance of the lo phase cholesterol/sphingomyelin-rich domains in the membrane surrounding fat globules in milk remains to be elucidated. This study brought new insight about the functional role of cholesterol in milk polar lipid ingredients, which can be used in the preparation of food emulsions, e.g. infant milk formulas. PMID:27300157

  20. Sulfur transformations in early diagenetic sediments from the Bay of Concepcion, off Chile

    Energy Technology Data Exchange (ETDEWEB)

    Vairavamurth, M.A.; Wang, Shengke; Khandelwal, B.; Manowitz, B. [Brookhaven National Lab., Upton, NY (United States); Ferdelman, T.; Fossing, H. [Max Plank Institute for Marine Microbiology, Bremen (Germany). Dept. of Biogeochemistry

    1995-04-01

    Despite the recognition that both organic sulfur and pyrite form during the very early stages of diagenesis, and that the amount of H{sub 2}S generated in bacterial sulfate reduction primarily limits their formation, the mechanisms and the active species involved still are not clear. In this study, we quantified the major forms of sulfur distributed in sediments to assess the geochemical mechanisms involved in these transformations. XANES spectroscopy, together with elemental analysis, were used to measure sulfur speciation in the organic-rich sediments from the Bay of Concepcion, Chile. Organic polysulfides constituted the major fraction of the organic sulfur, and occurred maximally just below the sediment surface (1--3 cm), where intermediates from H{sub 2}S oxidation were likely to be generated most abundantly. Sulfonates, which could be formed through the reactions of sulfate and thiosulfate, also showed a sub-surface maximum in the vicinity of the ``oxic-anoxic interface``. These results strongly suggest a geochemical origin for organic polysulfides and sulfonates, and illustrate that intermediates from H{sub 2}S oxidation play a dominant role in incorporating sulfur into organic matter. Pyrite was absent in the surficial layer, and first appeared just below the H{sub 2}S maximum, where organic polysulfides began to decrease in abundance. From these results, we argue, that an iron monosulfide precursor formed first from reactions with H{sub 2}S, and then reacts with organic polysulfides, completing the synthesis of pyrite in the sediment column.

  1. Binding mechanism of sulfur and dehydrogenated polyacrylonitrile in sulfur/polymer composite cathode

    Science.gov (United States)

    Doan, The Nam Long; Ghaznavi, Mahmoudreza; Zhao, Yan; Zhang, Yongguang; Konarov, Aishuak; Sadhu, Mikhail; Tangirala, Ravichandra; Chen, P.

    2013-11-01

    A composite consisting of sulfur/dehydrogenated polyacrylonitrile is one of the most promising cathode materials for use in rechargeable lithium-sulfur batteries. However, the reported sulfur contents have been low, less than 50 wt%, which compromise the intrinsic high specific capacity and energy of elemental sulfur and hence decrease significantly the specific energy of the composite. To identify the potential to further increase the sulfur content, we elucidate the binding mechanism of sulfur and polyacrylonitrile in their composite. The heat treatment experiments at varying timespans with excess sulfur showed a constancy of sulfur content after a critical length of timespan, indicating the saturation of sulfur in the structure of dehydrogenated polyacrylonitrile. Based on molecular structure and size consideration, it is proposed that the binding involves the formation of an 8 membered ring of sulfur embedded between 4 heterocyclic rings of dehydrogenated polyacrylonitrile. From this model and experimental results, we show that there exists an upper limit of sulfur content in the sulfur/dehydrogenated polyacrylonitrile composite at 56 wt%.

  2. Graphene-wrapped sulfur nanospheres with ultra-high sulfur loading for high energy density lithium–sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ya; Guo, Jinxin; Zhang, Jun, E-mail: zhangjun@zjnu.cn; Su, Qingmei; Du, Gaohui, E-mail: gaohuidu@zjnu.edu.cn

    2015-01-01

    Graphical abstract: - Highlights: • A graphene-wrapped sulfur nanospheres composite with 91 wt% S is prepared. • It shows highly improved electrochemical performance as cathode for Li–S cell. • The PVP coating and conductive graphene minimize polysulfides dissolution. • The flexible coatings with void space accommodate the volume expansion of sulfur. - Abstract: Lithium–sulfur (Li–S) battery with high theoretical energy density is one of the most promising energy storage systems for electric vehicles and intermittent renewable energy. However, due to the poor conductivity of the active material, considerable weight of the electrode is occupied by the conductive additives. Here we report a graphene-wrapped sulfur nanospheres composite (S-nanosphere@G) with sulfur content up to 91 wt% as the high energy density cathode material for Li–S battery. The sulfur nanospheres with diameter of 400–500 nm are synthesized through a solution-based approach with the existence of polyvinylpyrrolidone (PVP). Then the sulfur nanospheres are uniformly wrapped by conductive graphene sheets through the electrostatic interaction between graphene oxide and PVP, followed by reducing of graphene oxide with hydrazine. The design of graphene wrapped sulfur nanoarchitecture provides flexible conductive graphene coating with void space to accommodate the volume expansion of sulfur and to minimize polysulfide dissolution. As a result, the S-nanosphere@G nanocomposite with 91 wt% sulfur shows a reversible initial capacity of 970 mA h g{sup −1} and an average columbic efficiency > 96% over 100 cycles at a rate of 0.2 C. Taking the total mass of electrode into account, the S-nanosphere@G composite is a promising cathode material for high energy density Li–S batteries.

  3. Sulfur-carbon nanocomposites and their application as cathode materials in lithium-sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chengdu; Dudney, Nancy J; Howe, Jane Y

    2015-05-05

    The invention is directed in a first aspect to a sulfur-carbon composite material comprising: (i) a bimodal porous carbon component containing therein a first mode of pores which are mesopores, and a second mode of pores which are micropores; and (ii) elemental sulfur contained in at least a portion of said micropores. The invention is also directed to the aforesaid sulfur-carbon composite as a layer on a current collector material; a lithium ion battery containing the sulfur-carbon composite in a cathode therein; as well as a method for preparing the sulfur-composite material.

  4. Sulfur oxide adsorbents and emissions control

    Science.gov (United States)

    Li, Liyu; King, David L.

    2006-12-26

    High capacity sulfur oxide absorbents utilizing manganese-based octahedral molecular sieve (Mn--OMS) materials are disclosed. An emissions reduction system for a combustion exhaust includes a scrubber 24 containing these high capacity sulfur oxide absorbents located upstream from a NOX filter 26 or particulate trap.

  5. Stability of sulfur slopes on Io

    Science.gov (United States)

    Clow, G. D.; Carr, M. H.

    1980-01-01

    The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 100-1000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.

  6. Stabilized sulfur binding using activated fillers

    Energy Technology Data Exchange (ETDEWEB)

    Kalb, Paul D.; Vagin, Vyacheslav P.; Vagin, Sergey P.

    2015-07-21

    A method of making a stable, sulfur binding composite comprising impregnating a solid aggregate with an organic modifier comprising unsaturated hydrocarbons with at least one double or triple covalent bond between adjacent carbon atoms to create a modifier-impregnated aggregate; heating and drying the modifier-impregnated aggregate to activate the surface of the modifier-impregnated aggregate for reaction with sulfur.

  7. Heterogeneous photocatalytic reactions of sulfur aromatic compounds.

    Science.gov (United States)

    Samokhvalov, Alexander

    2011-11-18

    Sulfur aromatic compounds, such as mono-, di-, tri-, and tetraalkyl-substituted thiophene, benzothiophenes, dibenzothiophenes, are the molecular components of many fossils (petroleum, oil shale, tar sands, bitumen). Structural units of natural, cross-linked heteroaromatic polymers present in brown coals, turf, and soil are similar to those of sulfur aromatic compounds. Many sulfur aromatic compounds are found in the streams of petroleum refining and upgrading (naphthas, gas oils) and in the consumer products (gasoline, diesel, jet fuels, heating fuels). Besides fossils, the structural fragments of sulfur aromatic compounds are present in molecules of certain organic semiconductors, pesticides, small molecule drugs, and in certain biomolecules present in human body (pheomelanin pigments). Photocatalysis is the frontier area of physical chemistry that studies chemical reactions initiated by absorption of photons by photocatalysts, that is, upon electronic rather than thermal activation, under "green" ambient conditions. This review provides systematization and critical review of the fundamental chemical and physicochemical information on heterogeneous photocatalysis of sulfur aromatic compounds accumulated in the last 20-30 years. Specifically, the following topics are covered: physicochemical properties of sulfur aromatic compounds, major classes of heterogeneous photocatalysts, mechanisms and reactive intermediates of photocatalytic reactions of sulfur aromatic compounds, and the selectivity of these reactions. Quantum chemical calculations of properties and structures of sulfur aromatic compounds, their reactive intermediates, and the structure of adsorption complexes formed on the surface of the photocatalysts are also discussed.

  8. Sulfur extended asphalt pavement evaluation: Executive summary

    Science.gov (United States)

    Mahoney, J. P.

    1982-09-01

    This summary report overviews two previously issued study reports. One report assesses The availability and pricing of sulfur with respect to sulfur extended asphalt (SEA) paving mixture is assessed. A laboratory oriented testing program which was principally used to examine the durability and aging characteristics of SEA paving mixtures is reported.

  9. Effect of Additive on Sulfur-fixation Process of Sulfur-fixation Agent

    Institute of Scientific and Technical Information of China (English)

    XIE Jun-lin; QIU Jian-rong; ZHAO Gai-ju; LOU Jin-ping; HAN Chun-hua

    2003-01-01

    The crystallization behavior of desulfurization product is directly related to its high-temperatureresistant ability. Effects of the additive on the sulfur-fixation efficiency of the Ba-sulfur-fixation agent and also on the crystallization behavior of the sulfur-fixation product were studied when CaCO3 and BaCO3 were used as the desulfurization agent and MgO and SrCO3 used as the assistant sulfur-fixation agent. The result shows that increase of sulfur-fixation capability for the additive is not owe to their directly react to form sulfate or interact with CaCO3 and BaCO3 to form composite mineral heat-resistant in high temperature, but owe to their activation to sulfur-fixation reaction of the sulfur-fixation agent.

  10. Sulfur's price collapse to force market changes

    International Nuclear Information System (INIS)

    Price drops for sulfur over the past 2 years of 50-66% at most major consuming locations are prompting a major industry restructuring, according to Fertecon, a U.K.-based research organization that follows worldwide sulfur production for the fertilizer industry. A recently completed Fertecon study of the cost of producing and marketing sulfur indicates that the attrition in worldwide sulfur-mining capacity has now mostly run its course. Moreover, the burden of balancing the market will fall firmly on major producers of sulfur in the sour-gas industry, especially Canada. The paper discusses supply and demand realities, regional analysis, the role of sour gas, and the outlook for the future

  11. "Immunobiological Consequences of Sulfur Mustard Contamination "

    Directory of Open Access Journals (Sweden)

    Zuhair Mohammad Hassan

    2006-09-01

    Full Text Available Sulfur mustard has been employed in chemical warfare in certain regions including Iran. The short and long term biological effects of sulfur mustard contamination have been studied in both basic and clinical aspects. Sulfur mustard has been shown to induce a vast array of pathological effects in affected persons. In addition to skin, lung, eyes and gastrointestinal disturbances, sulfur mustard has been shown to induce hematological complications and a severe suppression of the immune system. The short and long term immunological (both cellular and humoral, hematological, genetic and biochemical consequences of persons exposed to sulfur mustard are extensively reviewed here. The long term complications of these patients indicate the need to develop effective preventive and therapeutic strategies in the clinic. These strategies may be based upon immunopotentiating intervention and therapy.

  12. Sulfur isotope geochemistry of ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type ore district, Poland

    Science.gov (United States)

    Leach, D.L.; Vets, J.G.; Gent, C.A.

    1996-01-01

    Studies of the sulfur isotopic composition of ore and gangue minerals from the Silesian-Cracow Zn-Pb district were conducted to gain insights into processes that controlled the location and distribution of the ore deposits. Results of this study show that minerals from the Silesian-Cracow ore district have the largest range of sulfur isotope compositions in sulfides observed from any Mississippi Valley-type ore district in the world. The ??34S values for sulfide minerals range from +38 to -32 per mil for the entire paragenetic sequence but individual stages exhibit smaller ranges. There is a well developed correlation between the sulfur isotope composition and paragenetic stage of ore deposition. The first important ore stage contains mostly positive ??34S values, around 5 per mil. The second stage of ore formation are lower, with a median value of around -5 to -15 per mil, and with some values as low as -32 per mil. Late stage barite contains isotopically heavy sulfur around +32 per mil. The range in sulfur isotope compositions can be explained by contributions of sulfur from a variety of source rocks together with sulfur isotope fractionations produced by the reaction paths for sulfate reduction. Much of the variation in sulfur isotope compositions can be explained by bacterial reduction of sedimentary sulfate and disequilibrium reactions by intermediate-valency sulfur species, especially in the late-stage pyrite and sphalerite. Organic reduction of sulfate and thermal release of sulfur from coals in the Upper Silesian Coal Basin may have been important contributors to sulfur in the ore minerals. The sulfur isotopic data, ore mineral textures, and fluid inclusion data, are consistent with the hypothesis that fluid mixing was the dominant ore forming mechanism. The rather distinct lowering of ?? 34S values in sulfides from stage 2 to stage 3 is believed to reflect some fundamental change in the source of reduced sulfur and/or hydrology of the ore

  13. Biological sulfuric acid transformation: Reactor design and process optimization.

    Science.gov (United States)

    Stucki, G; Hanselmann, K W; Hürzeler, R A

    1993-02-01

    As an alternative to the current disposal technologies for waste sulfuric acid, a new combination of recycling processes was developed. The strong acid (H(2)SO(4)) is biologically converted with the weak acid (CH(3)COOH) into two volatile weak acids (H(2)S, H(2)CO(3)) by sulfate-reducing bacteria. The transformation is possible without prior neutralization of the sulfuric acid. The microbially mediated transformation can be followed by physiochemical processes for the further conversion of the H(2)S.The reduction of sulfate to H(2)S is carried out under carbon-limited conditions at pH 7.5 to 8.5. A fixed-bed biofilm column reactor is used in conjunction with a separate gas-stripping column which was installed in the recycle stream. Sulfate, total sulfide, and the carbon substrate (in most cases acetate) were determined quantitatively. H(2)S and CO(2) are continually removed by stripping with N(2). Optimal removal is achieved under pH conditions which are adjusted to values below the pK(a)-values of the acids. The H(2)S concentration in the stripped gas was 2% to 8% (v/v) if H(2)SO(4) and CH(3)COOH are fed to the recycle stream just before the stripping column.Microbiol conversion rates of 65 g of sulfate reduced per liter of bioreactor volume per day are achieved and bacterial conversion efficiencies for sulfate of more than 95% can be maintained if the concentration of undissociated H(2)S is kept below 40 to 50 mg/L. Porous glass spheres, lava beads, and polyurethane pellets are useful matrices for the attachment of the bacterial biomass. Theoretical aspects and the dependence of the overall conversion performance on selected process parameters are illustrated in the Appendix to this article. PMID:18609554

  14. Dimethylsulfoniopropionate in corals and its interrelations with bacterial assemblages in coral surface mucus

    NARCIS (Netherlands)

    Frade, P.R.; Schwaninger, V.; Glasl, B.; Sintes, E.; Hill, R.W.; Simó, R.; Herndl, G.

    2016-01-01

    Corals produce copious amounts of dimethylsulfoniopropionate (DMSP), a sulfur compound thought toplay a role in structuring coral-associated bacterial communities. We tested the hypothesis that a linkage exists betweenDMSP availability in coral tissues and the community dynamics of bacteria in coral

  15. Succession of Sulfur-Oxidizing Bacteria in the Microbial Community on Corroding Concrete in Sewer Systems† ▿

    OpenAIRE

    Okabe, Satoshi; Odagiri, Mitsunori; Ito, Tsukasa; Satoh, Hisashi

    2007-01-01

    Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular ...

  16. Growth Kinetics of Thiobacillus thiooxidans on the Surface of Elemental Sulfur.

    Science.gov (United States)

    Konishi, Y; Asai, S; Yoshida, N

    1995-10-01

    The growth kinetics of Thiobacillus thiooxidans on elemental sulfur in batch cultures at 30(deg)C and pH 1.5 was studied by measuring the time courses of the concentration of adsorbed cells on sulfur, the concentration of free cells suspended in liquid medium, and the amount of sulfur oxidized. As the elemental sulfur was oxidized to sulfate ions, the surface concentration of adsorbed cells per unit mass of sulfur approached a maximum value (maximum adsorption capacity of sulfur particles) whereas the concentration of free cells continued to increase with time. There was a close relationship between the concentrations of free and adsorbed cells during the microbial sulfur oxidation, and the two cell concentrations were well correlated by the Langmuir isotherm with adsorption equilibrium constant K(infA) and maximum adsorption capacity X(infAm) of 2.10 x 10(sup-9) ml per cell and 4.57 x 10(sup10) cells per g, respectively. The total concentration of free and adsorbed cells increased in parallel with the amount of sulfate formed. The total growth on elemental sulfur gave a characteristic growth curve in which a linear-growth phase followed the period of an initial exponential phase. The batch rate data collected under a wide variety of inoculum levels (about 10(sup5) to 10(sup8) cells per ml) were consistent with a kinetic model assuming that the growth rate of adsorbed bacteria is proportional to the product of the concentration, X(infA), of adsorbed cells and the fraction, (theta)(infV), of adsorption sites unoccupied by cells. The kinetic and stoichiometric parameters appearing in the model were estimated from the experimental data, and the specific growth rate, (mu)(infA), and growth yield, Y(infA), were 2.58 day(sup-1) and 2.05 x 10(sup11) cells per g, respectively. The proposed model and the parameter values allowed us to predict quantitatively the surface attachment of T. thiooxidans cells on elemental sulfur and the bacterial growth in both initial

  17. Vimentin in Bacterial Infections

    Directory of Open Access Journals (Sweden)

    Tim N. Mak

    2016-04-01

    Full Text Available Despite well-studied bacterial strategies to target actin to subvert the host cell cytoskeleton, thus promoting bacterial survival, replication, and dissemination, relatively little is known about the bacterial interaction with other components of the host cell cytoskeleton, including intermediate filaments (IFs. IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge about the role of IFs in bacterial infections, focusing on the type III IF protein vimentin. Recent studies have revealed the involvement of vimentin in host cell defenses, acting as ligand for several pattern recognition receptors of the innate immune system. Two main aspects of bacteria-vimentin interactions are presented in this review: the role of vimentin in pathogen-binding on the cell surface and subsequent bacterial invasion and the interaction of cytosolic vimentin and intracellular pathogens with regards to innate immune signaling. Mechanistic insight is presented involving distinct bacterial virulence factors that target vimentin to subvert its function in order to change the host cell fate in the course of a bacterial infection.

  18. Reuse Possibilities for Elemental Sulfur Sludge

    OpenAIRE

    Järvensivu, Roni

    2015-01-01

    Gas collected from the landfill for power generation at Ämmässuo contains hydrogen sulfide, a toxic gas formed from decomposing organic matter. Hydrogen sulfide will form sulfuric acid in the presence of water vapor and is thus corrosive and unwanted in gas treatment systems. In addition to wearing the motors and acidifying the oils used at the combined heat and power plant, combustion of sulfur-containing gasses will result in the formation of sulfur dioxide, a toxic and harmful pollutant. ...

  19. Support for an anaerobic sulfur cycle in two Canadian peatland soils

    Science.gov (United States)

    Blodau, Christian; Mayer, Bernhard; Peiffer, Stefan; Moore, Tim R.

    2007-06-01

    Sulfur cycling in peatlands may affect global CH4 emissions by suppression of methanogenesis through bacterial sulfate reduction (BSR). We sought evidence for anaerobic sulfur cycling in four peat mesocosms irrigated with sulfate at a loading of 0.8 and 3.3 g S m-2 yr-1. To this end we obtained concentration profiles of dissolved O2, C, S, and Fe, and determined 34S/32S ratios of sulfate, reduced inorganic sulfur (TRIS), and total sulfur. To estimate the importance of BSR for anaerobic respiration, peat was incubated with molybdate as inhibitor of BSR. In the mesocosms, pore water concentrations of dissolved sulfate and H2S adjusted to 5-20 μmol L-1 and 0-9 μmol L-1, respectively, whereas concentrations of CO2, CH4, and DOC reached millimolar levels. CO2 production was not explained by methanogenesis and net reduction of inorganic electron acceptors. In the shallow peat, H2S was produced and 34S in sulfate enriched by 3.6 to 6‰, indicating occurrence of BSR. Sulfate reducers also accounted for much of the metabolic activity. Addition of molybdate suppressed CO2 production by 20 to 50%. Deeper into the peat, the sulfate pool was apparently replenished from the peat matrix as sulfate became enriched in 32S, likely stemming from TRIS or organic sulfur in the peat. Sulfur was thus anaerobically cycled between oxidized and reduced pools. An electron acceptor capable of driving this cycle could not be conclusively identified. Regardless of this uncertainty, the results suggest that anaerobic S cycling can maintain BSR and potentially contribute to low methane production in soils of ombrotrophic bogs.

  20. Microbial sulfur metabolism evidenced from pore fluid isotope geochemistry at Site U1385

    Science.gov (United States)

    Turchyn, Alexandra V.; Antler, Gilad; Byrne, David; Miller, Madeline; Hodell, David A.

    2016-06-01

    At Site U1385, drilled during IODP Expedition 339 off the coast of Portugal on the continental slope, high-resolution sulfate concentration measurements in the pore fluids display non-steady-state behavior. At this site there is a zone of sulfate reduction in the uppermost seven meters of sediment, followed by a 38-meter interval where sulfate concentrations do not change, and finally sulfate concentrations are depleted to zero between 45 and 55 meters below seafloor. Below the sulfate minimum zone, there is abundant methane, suggesting that the lower sulfate consumption zone is coupled to anaerobic methane oxidation. We analyze pore water samples from IODP Site U1385 for sulfur and oxygen isotope ratios of dissolved sulfate, as well as the sulfur isotope composition of sedimentary pyrite. The sulfur isotopes in pore fluid sulfate display similar non-steady-state behavior similar to that of the sulfate concentrations, increasing over the uppermost zone of sulfate reduction and again over the lower zone of sulfate-driven anaerobic methane oxidation. The oxygen isotopes in sulfate increase to the 'apparent equilibrium' value in the uppermost zone of sulfate reduction and do not change further. Our calculations support the idea that sulfite to sulfide reduction is the limiting step in microbial sulfate reduction, and that the isotope fractionation expressed in the residual pore water sulfate pool is inversely proportional to the net sulfate reduction rate. The sulfur isotope composition of pyrite acquires one value in the uppermost sediments, which may be overprinted by a second value in the deeper sediments, possibly due to iron release during anaerobic methane oxidation or iron diffusion from a higher zone of bacterial iron reduction. Our results have implications for modeling the sulfur isotope composition of the pyrite burial flux in the global biogeochemical sulfur cycle.

  1. Active sulfur cycling by diverse mesophilic and thermophilic microorganisms in terrestrial mud volcanoes of Azerbaijan.

    Science.gov (United States)

    Green-Saxena, A; Feyzullayev, A; Hubert, C R J; Kallmeyer, J; Krueger, M; Sauer, P; Schulz, H-M; Orphan, V J

    2012-12-01

    Terrestrial mud volcanoes (TMVs) represent geochemically diverse habitats with varying sulfur sources and yet sulfur cycling in these environments remains largely unexplored. Here we characterized the sulfur-metabolizing microorganisms and activity in four TMVs in Azerbaijan. A combination of geochemical analyses, biological rate measurements and molecular diversity surveys (targeting metabolic genes aprA and dsrA and SSU ribosomal RNA) supported the presence of active sulfur-oxidizing and sulfate-reducing guilds in all four TMVs across a range of physiochemical conditions, with diversity of these guilds being unique to each TMV. The TMVs varied in potential sulfate reduction rates (SRR) by up to four orders of magnitude with highest SRR observed in sediments where in situ sulfate concentrations were highest. Maximum temperatures at which SRR were measured was 60°C in two TMVs. Corresponding with these trends in SRR, members of the potentially thermophilic, spore-forming, Desulfotomaculum were detected in these TMVs by targeted 16S rRNA analysis. Additional sulfate-reducing bacterial lineages included members of the Desulfobacteraceae and Desulfobulbaceae detected by aprA and dsrA analyses and likely contributing to the mesophilic SRR measured. Phylotypes affiliated with sulfide-oxidizing Gamma- and Betaproteobacteria were abundant in aprA libraries from low sulfate TMVs, while the highest sulfate TMV harboured 16S rRNA phylotypes associated with sulfur-oxidizing Epsilonproteobacteria. Altogether, the biogeochemical and microbiological data indicate these unique terrestrial habitats support diverse active sulfur-cycling microorganisms reflecting the in situ geochemical environment.

  2. Sulfur Isotopic Characteristics of Coal in China and Sulfur Isotopic Fractionation during Coal—burning Process

    Institute of Scientific and Technical Information of China (English)

    洪业汤; 张鸿斌; 等

    1993-01-01

    The determined results of the sulfur contents and isotopic composition of coal samples from major coal mines in 15 provinces and regions of China show that the coal mined in the north of China is characterized by higher 34S and lower sulfur content, but that in the south of China has lower 34S and higher sulfur content.During the coal-burning process in both indrstrial and daily use of coal as fuel the released sulfur dioxide is always enriched in lighter sulfur isotope relative to the corresponding coal;the particles are always enriched in heavier sulfur isotope.The discussion on the environmental geochemical significance of the above-mentioned results also has been made.

  3. A Carbon-Sulfur Hybrid with Pomegranate-like Structure for Lithium-Sulfur Batteries.

    Science.gov (United States)

    Shi, Yanting; Lv, Wei; Niu, Shuzhang; He, Yanbing; Zhou, Guangmin; Chen, Guohua; Li, Baohua; Yang, Quan-Hong; Kang, Feiyu

    2016-05-01

    A carbon-sulfur hybrid with pomegranate-like core-shell structure, which demonstrates a high rate performance and relatively high cyclic stability, is obtained through carbonization of a carbon precursor in the presence of a sulfur precursor (FeS2 ) and a following oxidation of FeS2 to sulfur by HNO3 . Such a structure effectively protects the sulfur and leaves enough buffer space after Fe(3+) removal and, at the same time, has an interconnected conductive network. The capacity of the obtained hybrid is 450 mA h g(-1) under the current density of 5 C. This work provides a simple strategy to design and prepare various high-performance carbon-sulfur hybrids for lithium-sulfur batteries.

  4. A Carbon-Sulfur Hybrid with Pomegranate-like Structure for Lithium-Sulfur Batteries.

    Science.gov (United States)

    Shi, Yanting; Lv, Wei; Niu, Shuzhang; He, Yanbing; Zhou, Guangmin; Chen, Guohua; Li, Baohua; Yang, Quan-Hong; Kang, Feiyu

    2016-05-01

    A carbon-sulfur hybrid with pomegranate-like core-shell structure, which demonstrates a high rate performance and relatively high cyclic stability, is obtained through carbonization of a carbon precursor in the presence of a sulfur precursor (FeS2 ) and a following oxidation of FeS2 to sulfur by HNO3 . Such a structure effectively protects the sulfur and leaves enough buffer space after Fe(3+) removal and, at the same time, has an interconnected conductive network. The capacity of the obtained hybrid is 450 mA h g(-1) under the current density of 5 C. This work provides a simple strategy to design and prepare various high-performance carbon-sulfur hybrids for lithium-sulfur batteries. PMID:26918663

  5. Amylopectin wrapped graphene oxide/sulfur for improved cyclability of lithium-sulfur battery.

    Science.gov (United States)

    Zhou, Weidong; Chen, Hao; Yu, Yingchao; Wang, Deli; Cui, Zhiming; Disalvo, Francis J; Abruña, Héctor D

    2013-10-22

    An amylopectin wrapped graphene oxide-sulfur composite was prepared to construct a 3-dimensionally cross-linked structure through the interaction between amylopectin and graphene oxide, for stabilizing lithium sulfur batteries. With the help of this cross-linked structure, the sulfur particles could be confined much better among the layers of graphene oxide and exhibited significantly improved cyclability, compared with the unwrapped graphene oxide-sulfur composite. The effect of the electrode mass loading on electrochemical performance was investigated as well. In the lower sulfur mass loading cells, such as 2 mg cm(-2), both the capacity and the efficiency were obviously better than those of the higher sulfur mass loading cells, such as 6 mg cm(-2).

  6. Sulfurized carbon: a class of cathode materials for high performance lithium/sulfur batteries

    Directory of Open Access Journals (Sweden)

    Sheng S. Zhang

    2013-12-01

    Full Text Available Liquid electrolyte lithium/sulfur (Li/S batteries cannot come into practical applications because of many problems such as low energy efficiency, short cycle life, and fast self-discharge. All these problems are related to the dissolution of lithium polysulfide, a series of sulfur reduction intermediates, in the liquid electrolyte, and resulting parasitic reactions with the Li anode. Covalently binding sulfur onto carbon surface is a solution to completely eliminate the dissolution of lithium polysulfide and make the Li/S battery viable for practical applications. This can be achieved by replacing elemental sulfur with sulfurized carbon as the cathode material. This article reviews the current efforts on this subject and discusses the syntheses, electrochemical properties, and prospects of the sulfurized carbon as a cathode material in the rechargeable Li/S batteries.

  7. Single-taxon field measurements of bacterial gene regulation controlling DMSP fate.

    Science.gov (United States)

    Varaljay, Vanessa A; Robidart, Julie; Preston, Christina M; Gifford, Scott M; Durham, Bryndan P; Burns, Andrew S; Ryan, John P; Marin, Roman; Kiene, Ronald P; Zehr, Jonathan P; Scholin, Christopher A; Moran, Mary Ann

    2015-07-01

    The 'bacterial switch' is a proposed regulatory point in the global sulfur cycle that routes dimethylsulfoniopropionate (DMSP) to two fundamentally different fates in seawater through genes encoding either the cleavage or demethylation pathway, and affects the flux of volatile sulfur from ocean surface waters to the atmosphere. Yet which ecological or physiological factors might control the bacterial switch remains a topic of considerable debate. Here we report the first field observations of dynamic changes in expression of DMSP pathway genes by a single marine bacterial species in its natural environment. Detection of taxon-specific gene expression in Roseobacter species HTCC2255 during a month-long deployment of an autonomous ocean sensor in Monterey Bay, CA captured in situ regulation of the first gene in each DMSP pathway (dddP and dmdA) that corresponded with shifts in the taxonomy of the phytoplankton community. Expression of the demethylation pathway was relatively greater during a high-DMSP-producing dinoflagellate bloom, and expression of the cleavage pathway was greater in the presence of a mixed diatom and dinoflagellate community [corrected].These field data fit the prevailing hypothesis for bacterial DMSP gene regulation based on bacterial sulfur demand, but also suggest a modification involving oxidative stress response, evidenced as upregulation of catalase via katG, when DMSP is demethylated. PMID:25700338

  8. Variability of sulfur speciation in sediments from Sulejów Turawa and Siemianówka dam reservoirs (Poland)

    Science.gov (United States)

    Drzewicki, Wojciech; Ciężka, Monika; Jezierski, Piotr; Jędrysek, Mariusz Orion

    2015-06-01

    A study on sulfur circulation in sediments was carried out in dam reservoirs (Sulejów, Siemianówka, Turawa) with different hydrological and age characteristics as well as with a different level of sediment accumulation and organic matter content. Differences in the isotopic composition of SO2-4 in the water column and small variations in the concentration of this ion were observed in the Turawa reservoir. The investigations did not show vertical variation in the watercolumn concentrations and isotopic composition. This is due to the small depths of the reservoir and mixing of water. A part of sulfate sulfur from the water column is reduced by incorporating it into cell structures, while a part of it is deposited in the sediment. The study revealed a small exchange of SO2-4 between thewater column and the sediment. Depending on the season of the year and the sediment sampling site, biogeochemical transformations of sulfur species are observed. A significant variation in the biogeochemical processes was found between the Siemianówka and Sulejów reservoirs, both in the concentrations and in the isotopic composition of particular sulfur species. This primarily results from the different characteristics of either of these reservoirs (flows, sedimentation, and material discharge to the lake). The main source of sulfur supplied to the sediments in the Siemianówka reservoir is organic sulfur contained in organic matter deposited at the bottom. In the sediment, organic sulfur is bacterially oxidized and fixed as SO2-4 . This is manifested in a substantial enrichment of sulfate in 34S. The presence of polysulfides was found in both reservoirs, but a distinct depletion of δ34S(S2-) in the light sulfur isotope was observed in the Siemianówka reservoir. In a part of the Sulejów reservoir, polysulfides are oxidized to SO2-4 ,probably at the sediment/water interface.

  9. Environmental behavior and analysis of agricultural sulfur.

    Science.gov (United States)

    Griffith, Corey M; Woodrow, James E; Seiber, James N

    2015-11-01

    Sulfur has been widely used for centuries as a staple for pest and disease management in agriculture. Presently, it is the largest-volume pesticide in use worldwide. This review describes the sources and recovery methods for sulfur, its allotropic forms and properties and its agricultural uses, including development and potential advantages of nanosulfur as a fungicide. Chemical and microbial reactivity, interactions in soil and water and analytical methods for determination in environmental samples and foodstuffs, including inexpensive analytical methods for sulfur residues in wine, beer and other food/beverage substrates, will be reviewed. The toxicology of sulfur towards humans and agriculturally important fungi is included, with some restrictions on use to promote safety. The review concludes with areas for which more research is warranted.

  10. ROE Total Sulfur Deposition 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset identifies the amount of wet, dry, and total deposition of sulfur in kilograms per hectare from 1989 to 1991 at a set of point locations across the...

  11. ROE Total Sulfur Deposition 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset identifies the amount of wet, dry, and total deposition of sulfur in kilograms per hectare from 2011 to 2013 at a set of point locations across the...

  12. Atmospheric influence of Earth's earliest sulfur cycle

    Science.gov (United States)

    Farquhar; Bao; Thiemens

    2000-08-01

    Mass-independent isotopic signatures for delta(33)S, delta(34)S, and delta(36)S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal. Atmospheric fractionation processes should be considered in the use of sulfur isotopes to study the onset and consequences of microbial fractionation processes in Earth's early history.

  13. Efficient Electrolytes for Lithium-Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    Natarajan eAngulakshmi

    2015-05-01

    Full Text Available This review article mainly encompasses on the state-of-the-art electrolytes for lithium–sulfur batteries. Different strategies have been employed to address the issues of lithium-sulfur batteries across the world. One among them is identification of electrolytes and optimization of their properties for the applications in lithium-sulfur batteries. The electrolytes for lithium-sulfur batteries are broadly classified as (i non-aqueous liquid electrolytes, (ii ionic liquids, (iii solid polymer and (iv glass-ceramic electrolytes. This article presents the properties, advantages and limitations of each type of electrolytes. Also the importance of electrolyte additives on the electrochemical performance of Li-S cells is discussed.

  14. Protected Sulfur Cathode with Mixed Conductive Coating Layer for Lithium Sulfur Battery

    Science.gov (United States)

    Jin, Jun; Wen, Zhaoyin; Wang, Qingsong; Gu, Sui; Huang, Xiao; Chen, Chunhua

    2016-10-01

    A mixed conductive coating layer composed of lithium ion conductive ceramic powder, carbon and binder was introduced on the surface of a sulfur electrode. This coating layer is designed to suppress the migration of lithium polysulfides from the sulfur electrode, and improve the cycling capacity of a lithium sulfur battery. The protected sulfur cathode with a mixed conductive coating layer delivered an initial specific capacity of 1236 mAh g-1 at 0.5C and maintained a capacity of 842 mAh g-1 after 100 cycles. In particular, a soft package battery with protected cathode exhibits improved cycling capacity and excellent rate performance.

  15. Sulfur-centered reactive intermediates derived from the oxidation of sulfur compounds of biological interest

    Energy Technology Data Exchange (ETDEWEB)

    Abedinzadeh, Z. [Lab. de Chimie Physique, UMR, Univ. Rene Descartes, Paris (France)

    2001-02-01

    Sulphur compounds play a central role in the structure and activity of many vital systems. In the living cell, sulfur constitutes an essential part of the defense against oxidative damage and is transformed into a variety of sulfur free radical species. Many studies of the chemistry of sulfur-centered radicals using pulse radiolysis and photolysis techniques to detect and measure the kinetics of these radicals have been published and reviewed. This paper discusses the present state of research on the formation and reactivity of certain sulfur-centered radicals [RS{sup .}, RSS{sup .}, RS{sup .+}, (RSSR){sup .+}] and their implications for biological systems. (author)

  16. Protected Sulfur Cathode with Mixed Conductive Coating Layer for Lithium Sulfur Battery

    Science.gov (United States)

    Jin, Jun; Wen, Zhaoyin; Wang, Qingsong; Gu, Sui; Huang, Xiao; Chen, Chunhua

    2016-08-01

    A mixed conductive coating layer composed of lithium ion conductive ceramic powder, carbon and binder was introduced on the surface of a sulfur electrode. This coating layer is designed to suppress the migration of lithium polysulfides from the sulfur electrode, and improve the cycling capacity of a lithium sulfur battery. The protected sulfur cathode with a mixed conductive coating layer delivered an initial specific capacity of 1236 mAh g-1 at 0.5C and maintained a capacity of 842 mAh g-1 after 100 cycles. In particular, a soft package battery with protected cathode exhibits improved cycling capacity and excellent rate performance.

  17. Electric current generation by sulfur-reducing bacteria in microbial-anode fuel cell

    Science.gov (United States)

    Vasyliv, Oresta M.; Bilyy, Oleksandr I.; Ferensovych, Yaroslav P.; Hnatush, Svitlana O.

    2012-10-01

    Sulfur - reducing bacteria are a part of normal microflora of natural environment. Their main function is supporting of reductive stage of sulfur cycle by hydrogen sulfide production in the process of dissimilative sulfur-reduction. At the same time these bacteria completely oxidize organic compounds with CO2 and H2O formation. It was shown that they are able to generate electric current in the two chamber microbial-anode fuel cell (MAFC) by interaction between these two processes. Microbial-anode fuel cell on the basis of sulfur- and ferric iron-reducing Desulfuromonas acetoxidans bacteria has been constructed. It has been shown that the amount of electricity generation by investigated bacteria is influenced by the concentrations of carbon source (lactate) and ferric iron chloride. The maximal obtained electric current and potential difference between electrodes equaled respectively 0.28-0.29 mA and 0.19-0.2 V per 0.3 l of bacterial suspension with 0.4 g/l of initial biomass that was grown under the influence of 0.45 mM of FeCl3 and 3 g/l of sodium lactate as primal carbon source. It has also been shown that these bacteria are resistant to different concentrations of silver ions.

  18. Ocular Effects of Sulfur Mustard

    Directory of Open Access Journals (Sweden)

    Yunes Panahi

    2013-06-01

    Full Text Available Purpose: To review current knowledge about ocular effects of sulfur mustard (SM and the associated histopathologic findings and clinical manifestationsMethods: Literature review of medical articles (human and animal studies was accomplished using PubMed, Scopus and ISI databases. A total of 274 relevant articles in English were retrieved and reviewed thoroughly.Results: Eyes are the most sensitive organs to local toxic effects of mustard gas. Ocular injuries are mediated through different toxic mechanisms including: biochemical damages, biomolecular and gene expression modification, induction of immunologic and inflammatory reactions, disturbing ultrastructural architecture of the cornea, and long-lasting corneal denervation. The resulting ocular injuries can roughly be categorized into acute or chronic complications. Most of the patients recover from acute injuries, but a minority of victims will suffer from chronic ocular complications. Mustard gas keratopathy (MGK is a devastating late complication of SM intoxication that proceeds from limbal stem cell deficiency (LSCD.Conclusion: SM induces several different damaging changes in case of ocular exposure; hence leading to a broad spectrum of ocular manifestations in terms of severity, timing and form. Unfortunately, no effective strategy has been introduced yet to inhibit or restore these damaging changes.

  19. Polymer Electrolytes for Lithium/Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    The Nam Long Doan

    2012-08-01

    Full Text Available This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes.

  20. Mixed Population Screening for Sulfur Isotopes

    Institute of Scientific and Technical Information of China (English)

    CUI Bin; ZHAO Lei; ZHAN Zhaoyang; HE Zhijun

    2004-01-01

    Quantitative research of the origin of sulfur isotopes is a difficult problem that has puzzled geochemists all along. In the study of the middle and lower reaches of the Yangtze River and the Dongpo orefield in Hunan Province,the authors successfully applied the mathematical model of mixed population screening to quantitatively resolving the problem on the origin of sulfur isotopes, which is significant in finding out the source of mineralizing matter and metallogenic mechanisms.

  1. A Cable-Shaped Lithium Sulfur Battery.

    Science.gov (United States)

    Fang, Xin; Weng, Wei; Ren, Jing; Peng, Huisheng

    2016-01-20

    A carbon nanostructured hybrid fiber is developed by integrating mesoporous carbon and graphene oxide into aligned carbon nanotubes. This hybrid fiber is used as a 1D cathode to fabricate a new cable-shaped lithium-sulfur battery. The fiber cathode exhibits a decent specific capacity and lifespan, which makes the cable-shaped lithium-sulfur battery rank far ahead of other fiber-shaped batteries.

  2. Attachment of Thiobacillus thiooxidans to sulfur crystals.

    Science.gov (United States)

    SCHAEFFER, W I; HOLBERT, P E; UMBREIT, W W

    1963-01-01

    Schaeffer, W. I. (Rutgers, The State University, New Brunswick, N.J.), P. E. Holbert, and W. W. Umbreit. Attachment of Thiobacillus thiooxidans to sulfur crystals. J. Bacteriol. 85:137-140. 1963.-Electron micrographs of replicas of sulfur crystals before and after attack by Thiobacillus thiooxidans show that the microorganisms erode the crystal in the area immediately adjacent to the cell. When there are many cells, the entire crystal surface appears eroded.

  3. Biologically produced sulfur particles and polysulfide ions

    OpenAIRE

    Kleinjan, W.E.

    2005-01-01

    This thesis deals with the effects of particles of biologically produced sulfur (or 'biosulfur') on a biotechnological process for the removal of hydrogen sulfide from gas streams. Particular emphasis is given to the role of polysulfide ions in such a process. These polysulfide ions are formed from reaction of sulfide with biologically produced sulfur. The basic concepts of this H 2 S removal process were developed at the department of Environmental Technology of Wageningen University and the...

  4. Bacterial oxidation activity in heap leaching

    Institute of Scientific and Technical Information of China (English)

    柳建设; 夏海波; 王兆慧; 胡岳华

    2004-01-01

    Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans (T. f. ) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The surveys of production process and the bacterial oxidation activity in the heap bioleaching were investigated. The results show that pH value is high, bacteria biomass and ferric concentration are low, generation time (above 7.13 h)is long in leachate, and less bacteria are adsorbed on the ores. The bacteria in the leachate exposing on the surface and connecting with mineral, have much faster oxidation rate of Fe( Ⅱ ) and shorter generation time, compared with those which are in the reservoir for a long time. There is diversity for oxidation activity of Fe( Ⅱ ), while there is no diversity for oxidation of sulfur. So it is advisable to add sulfuric acid to degrade pH value to 2.0, add nutrients and shorten recycling time of leachate, so as to enhance bacteria concentration of leachate and the leaching efficiency.

  5. Microphysical simulations of sulfur burdens from stratospheric sulfur geoengineering

    Directory of Open Access Journals (Sweden)

    J. M. English

    2012-01-01

    Full Text Available Recent microphysical studies suggest that geoengineering by continuous stratospheric injection of SO2 gas may be limited by the growth of the aerosols. We study the efficacy of SO2, H2SO4 and aerosol injections on aerosol mass and optical depth using a three-dimensional general circulation model with sulfur chemistry and sectional aerosol microphysics (WACCM/CARMA. We find increasing injection rates of SO2 in a narrow band around the equator to have limited efficacy while broadening the injecting zone as well as injecting particles instead of SO2 gas increases the sulfate burden for a given injection rate, in agreement with previous work. We find that injecting H2SO4 gas instead of SO2 does not discernibly alter sulfate size or mass, in contrast with a previous study using a plume model with a microphysical model. However, the physics and chemistry in aircraft plumes, which are smaller than climate model grid cells, need to be more carefully considered. We find equatorial injections increase aerosol optical depth in the Northern Hemisphere more than the Southern Hemisphere, potentially inducing regional climate changes. We also find significant perturbations to tropospheric aerosol for all injections studied, particularly in the upper troposphere and near the poles, where sulfate burden increases by up to 100 times. This enhanced burden could have implications for tropospheric radiative forcing and chemistry. These results highlight the need to mitigate greenhouse gas emissions through means other than geoengineering, and to further study geoengineering before it can be seriously considered as a climate intervention option.

  6. Microphysical simulations of sulfur burdens from stratospheric sulfur geoengineering

    Directory of Open Access Journals (Sweden)

    J. M. English

    2012-05-01

    Full Text Available Recent microphysical studies suggest that geoengineering by continuous stratospheric injection of SO2 gas may be limited by the growth of the aerosols. We study the efficacy of SO2, H2SO4 and aerosol injections on aerosol mass and optical depth using a three-dimensional general circulation model with sulfur chemistry and sectional aerosol microphysics (WACCM/CARMA. We find increasing injection rates of SO2 in a narrow band around the equator to have limited efficacy while broadening the injecting zone as well as injecting particles instead of SO2 gas increases the sulfate burden for a given injection rate, in agreement with previous work. We find that injecting H2SO4 gas instead of SO2 does not discernibly alter sulfate size or mass, in contrast with a previous study using a plume model with a microphysical model. However, the physics and chemistry in aircraft plumes, which are smaller than climate model grid cells, need to be more carefully considered. We also find significant perturbations to tropospheric aerosol for all injections studied, particularly in the upper troposphere and near the poles, where sulfate burden increases by up to 100 times. This enhanced burden could have implications for tropospheric radiative forcing and chemistry. These results highlight the need to mitigate greenhouse gas emissions rather than attempt to cool the planet through geoengineering, and to further study geoengineering before it can be seriously considered as a climate intervention option.

  7. Quantitative proteomic analysis of milk fat globule membrane (MFGM) proteins in human and bovine colostrum and mature milk samples through iTRAQ labeling.

    Science.gov (United States)

    Yang, Mei; Cong, Min; Peng, Xiuming; Wu, Junrui; Wu, Rina; Liu, Biao; Ye, Wenhui; Yue, Xiqing

    2016-05-18

    Milk fat globule membrane (MFGM) proteins have many functions. To explore the different proteomics of human and bovine MFGM, MFGM proteins were separated from human and bovine colostrum and mature milk, and analyzed by the iTRAQ proteomic approach. A total of 411 proteins were recognized and quantified. Among these, 232 kinds of differentially expressed proteins were identified. These differentially expressed proteins were analyzed based on multivariate analysis, gene ontology (GO) annotation and KEGG pathway. Biological processes involved were response to stimulus, localization, establishment of localization, and the immune system process. Cellular components engaged were the extracellular space, extracellular region parts, cell fractions, and vesicles. Molecular functions touched upon were protein binding, nucleotide binding, and enzyme inhibitor activity. The KEGG pathway analysis showed several pathways, including regulation of the actin cytoskeleton, focal adhesion, neurotrophin signaling pathway, leukocyte transendothelial migration, tight junction, complement and coagulation cascades, vascular endothelial growth factor signaling pathway, and adherens junction. These results enhance our understanding of different proteomes of human and bovine MFGM across different lactation phases, which could provide important information and potential directions for the infant milk powder and functional food industries. PMID:27159491

  8. Theoretical studies of the marine sulfur cycle

    Science.gov (United States)

    Toon, Owen B.; Kasting, James B.; Liu, May S.

    1985-01-01

    Several reduced sulfur compounds are produced by marine organisms and then enter the atmosphere, where they are oxidized and ultimately returned to the ocean or the land. The oceanic dimethyl sulfide (DMS) flux, in particular, represents a significant fraction of the annual global sulfur input to the atmosphere. In the atmosphere, this gas is converted to sulfur dioxide (SO2), methane sulfonic acid, and other organic acids which are relatively stable and about which little is known. SO2 is a short lived gas which, in turn, is converted to sulfuric acid and other sulfate compounds which contribute significantly to acid rain. Because of the complexity of the sulfur system, it is not well understood even in the unperturbed atmosphere. However, a number of new observations and experiments have led to a significant increase in the understanding of this system. A number of one dimensional model experiments were conducted on the gas phase part of the marine sulfur cycle. The results indicate the measured concentration of DMS and the amplitude of its diurnal cycle are in agreement with estimates of its global flux. It was also found that DMS can make a large contribution to the background SO2 concentration in the free troposphere. Estimates of CS2 concentrations in the atmosphere are inconsistent with estimated fluxes; however, measured reaction rates are consistent with the observed steep tropospheric gradient in CS2. Observations of CS2 are extremely sparse. Further study is planned.

  9. Interfering with bacterial gossip

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Givskov, Michael

    2011-01-01

    defense. Antibiotics exhibit a rather limited effect on biofilms. Furthermore, antibiotics have an ‘inherent obsolescence’ because they select for development of resistance. Bacterial infections with origin in bacterial biofilms have become a serious threat in developed countries. Pseudomonas aeruginosa...... that appropriately target bacteria in their relevant habitat with the aim of mitigating their destructive impact on patients. In this review we describe molecular mechanisms involved in “bacterial gossip” (more scientifically referred to as quorum sensing (QS) and c-di-GMP signaling), virulence, biofilm formation...

  10. The significance of glucosinolates for sulfur storage in Brassicaceae seedlings

    OpenAIRE

    Aghajanzadeh, Tahereh; Hawkesford, Malcolm J.; de Kok, Luit J.

    2014-01-01

    Brassica juncea seedlings contained a twofold higher glucosinolate content than B. rapa and these secondary sulfur compounds accounted for up to 30% of the organic sulfur fraction. The glucosinolate content was not affected by H2S and SO2 exposure, demonstrating that these sulfur compounds did not form a sink for excessive atmospheric supplied sulfur. Upon sulfate deprivation, the foliarly absorbed H2S and SO2 replaced sulfate as the sulfur source for growth of B. juncea and B. rapa seedlings...

  11. Ionization fraction and the enhanced sulfur chemistry in Barnard 1

    Science.gov (United States)

    Fuente, A.; Cernicharo, J.; Roueff, E.; Gerin, M.; Pety, J.; Marcelino, N.; Bachiller, R.; Lefloch, B.; Roncero, O.; Aguado, A.

    2016-01-01

    Context Barnard B1b has revealed as one of the most interesting globules from the chemical and dynamical point of view. It presents a rich molecular chemistry characterized by large abundances of deuterated and complex molecules. Furthermore, it hosts an extremely young Class 0 object and one candidate to First Hydrostatic Core (FHSC) proving the youth of this star forming region. Aims Our aim is to determine the cosmic ray ionization rate, ζH2, and the depletion factors in this extremely young star forming region. These parameteres determine the dynamical evolution of the core. Methods We carried out a spectral survey towards Barnard 1b as part of the IRAM Large program ASAI using the IRAM 30-m telescope at Pico Veleta (Spain). This provided a very complete inventory of neutral and ionic C-, N- and S- bearing species with, up to our knowledge, the first secure detections of the deuterated ions DCS+ and DOCO+. We use a state-of-the-art pseudo-time-dependent gas-phase chemical model that includes the ortho and para forms of H2,H2+,D2+,H3+,H2D+,D2H+,D2 and D3+ to determine the local value of the cosmic ray ionization rate and the depletion factors. Results Our model assumes n(H2)=105 cm−3 and Tk=12 K, as derived from our previous works. The observational data are well fitted with ζH2 between 3×10−17 s−1 and 10−16 s−1, and the following elemental abundances: O/H=3 10−5, N/H=6.4−8 10−5, C/H=1.7 10−5 and S/H between 6.0 10−7 and 1.0 10−6. The large number of neutral/protonated species detected, allows us to derive the elemental abundances and cosmic ray ionization rate simultaneously. Elemental depletions are estimated to be ~10 for C and O, ~1 for N and ~25 for S. Conclusions Barnard B1b presents similar depletions of C and O than those measured in pre-stellar cores. The depletion of sulfur is higher than that of C and O but not as extreme as in cold cores. In fact, it is similar to the values found in some bipolar outflows, hot cores and

  12. Study of a bacterial leaching program for uranium ores by Thiobacillus ferroxidans

    International Nuclear Information System (INIS)

    The development of a bacterial leaching program for uranium ores is studied. Three basic points are presented: isolation and purification of Thiobacillus ferroxidans, as well Thiobacillus thio oxidans; physiological studies of growth and respiratory metabolism of T. ferroxidans; uranium leaching from two types of ore by T. ferroxidans action, on laboratory, semi pilot and pilot scales. The bacterial leaching studies were carried out in shake flasks, percolation columns (laboratory and semi pilot) and in heap leaching (pilot). The potential of the ores studied in relation to bacterial action, was first showed in shake flask experiments. The production of H2 S O4 and Fe3+ was a result of the bacterial activity on both ore samples containing pyrite (Fe S2). These two bacterial products resulted in a high uranium and molybdenum extraction and a lower sulfuric acid consumption compared to the sterilized treatments. Similar results were obtained in percolation column at the same scale (lab). (author)

  13. Bacterial Wound Culture

    Science.gov (United States)

    ... Home Visit Global Sites Search Help? Bacterial Wound Culture Share this page: Was this page helpful? Also known as: Aerobic Wound Culture; Anaerobic Wound Culture Formal name: Culture, wound Related ...

  14. Bacterial surface adaptation

    Science.gov (United States)

    Utada, Andrew

    2014-03-01

    Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

  15. Bacterial intermediate filaments

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Cabeen, M.; Jacobs-Wagner, C.

    2009-01-01

    Crescentin, which is the founding member of a rapidly growing family of bacterial cytoskeletal proteins, was previously proposed to resemble eukaryotic intermediate filament (IF) proteins based on structural prediction and in vitro polymerization properties. Here, we demonstrate that crescentin...

  16. Bacterial Meningitis in Infants

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-04-01

    Full Text Available A retrospective study of 80 infantile patients (ages 30-365 days; 47 male, 33 female with culture-proven bacterial meningitis seen over a 16 year period (1986-2001 is reported from Taiwan.

  17. Graphene-Wrapped Sulfur Particles as a Rechargeable Lithium-Sulfur-Battery Cathode Material with High Capacity and Cycling Stability

    OpenAIRE

    Wang, Hailiang; Yang, Yuan; Liang, Yongye; Robinson, Joshua Tucker; Li, Yanguang; Jackson, Ariel; Cui, Yi; Dai, Hongjie

    2011-01-01

    We report the synthesis of a graphene-sulfur composite material by wrapping polyethyleneglycol (PEG) coated submicron sulfur particles with mildly oxidized graphene oxide sheets decorated by carbon black nanoparticles. The PEG and graphene coating layers are important to accommodating volume expansion of the coated sulfur particles during discharge, trapping soluble polysulfide intermediates and rendering the sulfur particles electrically conducting. The resulting graphene-sulfur composite sh...

  18. 40 CFR 50.4 - National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    Science.gov (United States)

    2010-07-01

    ... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS § 50.4 National primary ambient air quality standards for sulfur oxides (sulfur dioxide). Link to an... applicable to all areas notwithstanding the promulgation of SO2 national ambient air quality standards...

  19. Paleoarchean sulfur cycling : Multiple sulfur isotope constraints from the Barberton Greenstone Belt, South Africa

    NARCIS (Netherlands)

    Montinaro, Alice; Strauss, Harald; Mason, Paul R D; Roerdink, Desiree; Münker, Carsten; Schwarz-Schampera, Ulrich; Arndt, Nicholas T.; Farquhar, James; Beukes, Nicolas J.; Gutzmer, Jens; Peters, Marc

    2015-01-01

    Mass-dependent and mass-independent sulfur isotope fractionation archived in volcanic and sedimentary rocks from the Barberton Greenstone Belt (3550-3215. Ma), South Africa, provide constraints for sulfur cycling on the early Earth. Four different sample suites were studied: komatiites and tholeiite

  20. Genomic Insights into the Sulfur Metabolism of Phototrophic Green Sulfur Bacteria

    DEFF Research Database (Denmark)

    Frigaard, Niels-Ulrik; Bryant, Donald A.

    2008-01-01

    Green sulfur bacteria (GSB) utilize various combinations of sulfide, elemental sulfur, thiosulfate, ferrous iron, and hydrogen for anaerobic photoautotrophic growth. Genome sequence data is currently available for 12 strains of GSB. We present here a genome-based survey of the distribution and...... phylogenies of genes involved in oxidation of sulfur compounds in these strains. Sulfide:quinone reductase, encoded by sqr, is the only known sulfur-oxidizing enzyme found in all strains. All sulfide-utilizing strains contain the dissimilatory sulfite reductase dsrABCEFHLNMKJOPT genes, which appear to be...... involved in elemental sulfur utilization. All thiosulfate-utilizing strains have an identical sox gene cluster (soxJXYZAKBW). The soxCD genes found in certain other thiosulfate-utilizing organisms like Paracoccus pantotrophus are absent from GSB. Genes encoding flavocytochrome c (fccAB), adenosine-5...

  1. Electrostatic self-assembly of graphene oxide wrapped sulfur particles for lithium–sulfur batteries

    International Nuclear Information System (INIS)

    Highlights: • Researched graphene oxide wrapped sulfur particles for lithium–sulfur batteries. • New approach for core–shell GO/S composites by electrostatic self-assembly method. • Both core–shell structure and the GO support help to retard the diffusion of polysulfides during the electrochemical cycling process of GO/S cathode. - Abstract: A novel graphene oxide (GO)/sulfur (S) composite is developed by electrostatic self-assembly method. Remarkably, the core–shell structure of the composite and the GO support helps to retard the diffusion of polysulfides during the electrochemical cycling process. The GO/sulfur cathode presents enhanced cycling ability. Specific discharge capacities up to 494.7 mAh g−1 over 200 cycles at 0.1 C is achieved with enhanced columbic efficiency around 95%, representing a good cathode material for lithium–sulfur batteries

  2. Effect of sulfur content in a sulfur-activated carbon composite on the electrochemical properties of a lithium/sulfur battery

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin-Woo; Kim, Changhyeon; Ryu, Ho-Suk; Cho, Gyu-Bong; Cho, Kwon-Koo; Kim, Ki-Won [School of Materials Science and Engineering, Gyeongsang National University, Jinju (Korea, Republic of); Ahn, Jou-Hyeon [Department of Chemical & Biological Engineering, Gyeongsang National University, Jinju (Korea, Republic of); Wang, Guoxiu [School of Chemistry and Forensic Science, University of Technology Sydney, Sydney, NSW 2007 (Australia); Ahn, Jae-Pyeung [Advanced Analysis Center, Research Planning & Coordination Division, KIST, Seoul (Korea, Republic of); Ahn, Hyo-Jun, E-mail: ahj@gnu.ac.kr [School of Materials Science and Engineering, Gyeongsang National University, Jinju (Korea, Republic of)

    2015-09-15

    Highlights: • The content of sulfur in activated carbon was controlled by solution process. • The sulfur electrode with low sulfur content shows the best performance. • The Li/S battery has capacity of 1360 mAh/g at 1 C and 702 mAh/g at 10 C. - Abstract: The content of sulfur in sulfur/activated carbon composite is controlled from 32.37 wt.% to 55.33 wt.% by a one-step solution-based process. When the sulfur content is limited to 41.21 wt.%, it can be loaded into the pores of an activated carbon matrix in a highly dispersed state. On the contrary, when the sulfur content is 55.33 wt.%, crystalline sulfur can be detected on the surface of the activated carbon matrix. The best electrochemical performance can be obtained for a sulfur electrode with the lowest sulfur content. The sulfur/activated carbon composite with 32.37 wt.% sulfur afforded the highest first discharge capacity of 1360 mAh g{sup −1} at 1 C rate and a large reversible capacity of 702 mAh g{sup −1} at 10 C (16.75 A/g)

  3. The effective synthesis of Insoluble sulfur using electron beam

    International Nuclear Information System (INIS)

    Vulcanization is process that formed crosslinking by Insoluble sulfur between linear structure of rubber polymer. Recently, Synthesis of Insoluble sulfur is used Thermal polymerization using about 250 ∼ 300 .deg. C and extraction process is used carbon disulfide(CS2) for separation between soluble sulfur and insoluble sulfur. But this process isn't environmental, economical and safety. This research was focus on developing of insoluble sulfur synthesis process using electron beam. This new process is using under the 140 .deg. C. Because of that, explosion risk is decrease, environmental and economical factor is increased. The sulfur can be melt by increase temperature or made solution using carbon disulfide. And electron beam is irradiated melting sulfur or sulfur solution. After irradiation, The high purity insoluble sulfur can be obtained by separation with carbon disulfide

  4. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Science.gov (United States)

    Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

    2012-01-01

    To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4)) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4) was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4) concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

  5. Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

    Directory of Open Access Journals (Sweden)

    Yao Zhang

    Full Text Available To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4 concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4 was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4 concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

  6. Succession of sulfur-oxidizing bacteria in the microbial community on corroding concrete in sewer systems.

    Science.gov (United States)

    Okabe, Satoshi; Odagiri, Mitsunori; Ito, Tsukasa; Satoh, Hisashi

    2007-02-01

    Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular techniques. Results revealed that at least six phylotypes of SOB species were involved in the MICC process, and the predominant SOB species shifted in the following order: Thiothrix sp., Thiobacillus plumbophilus, Thiomonas intermedia, Halothiobacillus neapolitanus, Acidiphilium acidophilum, and Acidithiobacillus thiooxidans. A. thiooxidans, a hyperacidophilic SOB, was the most dominant (accounting for 70% of EUB338-mixed probe-hybridized cells) in the heavily corroded concrete after 1 year. This succession of SOB species could be dependent on the pH of the concrete surface as well as on trophic properties (e.g., autotrophic or mixotrophic) and on the ability of the SOB to utilize different sulfur compounds (e.g., H2S, S0, and S2O3(2-)). In addition, diverse heterotrophic bacterial species (e.g., halo-tolerant, neutrophilic, and acidophilic bacteria) were associated with these SOB. The microbial succession of these microorganisms was involved in the colonization of the concrete and the production of sulfuric acid. Furthermore, the vertical distribution of microbial community members revealed that A. thiooxidans was the most dominant throughout the heavily corroded concrete (gypsum) layer and that A. thiooxidans was most abundant at the highest surface (1.5-mm) layer and decreased logarithmically with depth because of oxygen and H2S transport limitations. This suggested that the production of sulfuric acid by A. thiooxidans occurred mainly on the concrete surface and the

  7. Metabolic Reactions among Organic Sulfur Compounds

    Science.gov (United States)

    Schulte, M.; Rogers, K.

    2005-01-01

    Sulfur is central to the metabolisms of many organisms that inhabit extreme environments. Numerous authors have addressed the energy available from a variety of inorganic sulfur redox pairs. Less attention has been paid, however, to the energy required or gained from metabolic reactions among organic sulfur compounds. Work in this area has focused on the oxidation of alkyl sulfide or disulfide to thiol and formaldehyde, e.g. (CH3)2S + H2O yields CH3SH + HCHO + H2, eventually resulting in the formation of CO2 and SO4(-2). It is also found that reactions among thiols and disulfides may help control redox disequilibria between the cytoplasm and the periplasm. Building on our earlier efforts for thiols, we have compiled and estimated thermodynamic properties for alkyl sulfides. We are investigating metabolic reactions among various sulfur compounds in a variety of extreme environments, ranging from sea floor hydrothermal systems to organic-rich sludge. Using thermodynamic data and the revised HKF equation of state, along with constraints imposed by the geochemical environments sulfur-metabolizing organisms inhabit, we are able to calculate the amount of energy available to these organisms.

  8. Sulfur 'Concrete' for Lunar Applications - Environmental Considerations

    Science.gov (United States)

    Grugel, R. N.

    2008-01-01

    Commercial use of sulfur concrete on Earth is well established, particularly in corrosive, e.g., acid and salt, environments. Having found troilite (FeS) on the Moon raises the question of using extracted sulfur as a lunar construction material, an attractive alternative to conventional concrete as it does not require water. For the purpose of this Technical Memorandum, it is assumed that lunar ore is mined, refined, and the raw sulfur processed with appropriate lunar regolith to form, for example, bricks. With this stipulation, it is then noted that the viability of sulfur concrete in a lunar environment, which is characterized by lack of an atmosphere and extreme temperatures, is not well understood. The work presented here evaluates two sets of small sulfur concrete samples that have been prepared using JSC-1 lunar simulant as an aggregate addition. One set was subjected to extended periods in high vacuum to evaluate sublimation issues, and the other was cycled between room and liquid nitrogen temperatures to investigate their subsequent mechanical integrity. Results are presented from both investigations, discussed, and put into the context of the lunar environment.

  9. Bacterial community in sediment from the Western Pacific "Warm Pool" and its relationship to environment

    Institute of Scientific and Technical Information of China (English)

    ZENG Runying; ZHAO Jing; ZHANG Rui; LIN Nianwei

    2005-01-01

    Total DNAs were extracted from different sections of deep sea sediment core sample collected from the Western Pacific "Warm Pool". The bacterial 16S ribosomal DNA (rDNA) clone libraries were constructed and analyzed by PCR-restriction fragment length polymorphism (RFLP) and DNA sequencing. The bacterial communities in these samples and their relationship to environment were analyzed consequently. The results indicated that among eight main bacterial groups found in these sediments, members of the γ-Proteobacteria were most abundant in each section of sediment core sample and the genus Colwellia belonging to γ-Proteobacteria was dominant in this area. Members of the α-Proteobacteria were found commonly existing in these samples, while members belonging to β-Proteobacteria were seldom detected. The diversity of bacterial communities from different sections of sediment core sample was δ- and ε-Proteo- bacteria and the bacterial group including genera Cytopahga, Flexibacteria and Bacteroides (CFB group). These bacteria all were inversely proportional to the depth of sediment. Phylogenetic analysis showed that there were 18%-30% and 15%-25% of total bacterial communities related to methane and sulfur metabolism respectively in each section of core sample, implicating that the metabolism of sulfur and methane played an important role in the substance and energy cycles of the Western Pacific "Warm Pool".

  10. The temperature-dependent physical state of polar lipids and their miscibility impact the topography and mechanical properties of bilayer models of the milk fat globule membrane.

    Science.gov (United States)

    Murthy, Appala Venkata Ramana; Guyomarc'h, Fanny; Lopez, Christelle

    2016-09-01

    The polar lipid assembly and biophysical properties of the biological membrane enveloping the milk fat globules (the MFGM) are yet poorly known, especially in connection with the temperature history that milk can experience after its secretion. However, bioactive mechanisms depend on biological structure, which itself highly depend on temperature. The objectives of this study were to investigate polar lipid packing in hydrated bilayers, models of the MFGM, and to follow at intermolecular level temperature-induced changes in the range 60-6°C, using the combination of differential scanning calorimetry, X-ray diffraction, atomic force microscopy (AFM) imaging and force spectroscopy. MFGM polar lipids, especially sphingomyelin, contain long chain saturated fatty acids with high phase transition temperatures. On cooling, the liquid disordered ld to solid ordered so (gel) phase transition of MFGM polar lipids started at about 40°C, leading to phase separation and formation of so phase domains protruding by about 1nm from the ld phase. Indentation measurements using AFM revealed that the resistance of the so phase domains to rupture was significantly higher than that of the ld phase and that it increased for both the domain and fluid phases with decreasing temperature. However, packing and stability of the bilayers were adversely affected by fast cooling to 6°C or by cooling-rewarming cycle. This study showed that MFGM polar lipid bilayers are dynamic systems. Heterogeneity in the structure and mechanical properties of the membrane was induced by temperature-dependent so/ld phase immiscibility of the lipid components. This could have consequences on the MFGM technological and biological functions (e.g. immunity and milk lipid digestion). PMID:27349732

  11. Genetic polymorphism in milk fat globule-EGF factor 8 (MFG-E8) is associated with systemic lupus erythematosus in human.

    Science.gov (United States)

    Hu, C Y; Wu, C S; Tsai, H F; Chang, S K; Tsai, W I; Hsu, P N

    2009-07-01

    Milk fat globule-EGF factor 8 (MFG-E8) is a molecule implicated in phagocytic clearance of apoptotic cells by bridging between macrophages and apoptotic cells. Defects in MFG-E8 cause lupus-like disease in murine models. The aim of our study is to determine whether genetic variation in MFG-E8 predisposes human to systemic lupus erythematosus (SLE). A case-control study of MFG-E8 genetic polymorphism was performed on 147 SLE patients and 146 non-lupus control subjects. Single nucleotide polymorphisms (SNPs) in the coding sequence of human MFG-E8 gene were investigated. SNPs on MFG-E8 residues 3 (3(Arg or Ser)) and 76 (76(Leu or Met)) did not show genetic linkage. Genetic polymorphism on MFG-E8 residue 76 correlated significantly to SLE. The MFG-E8-76(Met) allele predisposed subjects to SLE in a recessive mode (odds ratio: 2.1, P = 0.020), while carriage of MFG-E8-76(Leu) were negatively associated with SLE. The MFG-E8 genotypic combinations with 3(Ser) and 76(Leu) showed the most pronounced protective effect on SLE when compared to the most predisposing genotype 3(Arg/Arg)-76(Met/Met) (OR: 0.29, P = 0.007). According to our result, MFG-E8 is associated with SLE predisposition in Taiwanese. Our study implicates that the impairment of phagocytic clearance of apoptotic cells through phosphotidylserine-dependent MFG-E8 system may lead to the development of human SLE. PMID:19502262

  12. Milk fat globule membrane coating of large lipid droplets in the diet of young mice prevents body fat accumulation in adulthood.

    Science.gov (United States)

    Baars, Annemarie; Oosting, Annemarie; Engels, Eefje; Kegler, Diane; Kodde, Andrea; Schipper, Lidewij; Verkade, Henkjan J; van der Beek, Eline M

    2016-06-01

    Epidemiological studies have demonstrated protective effects of breast-feeding on childhood obesity. Differences between human milk and infant milk formula (IMF) in dietary lipid structure may contribute to this effect. In our mouse model, feeding a diet containing large lipid droplets coated with phospholipids (PL) (Nuturis®; PL of milk fat globule membrane (MFGM) fraction origin) in early life protected against excessive body fat accumulation following a diet challenge in adult life. We now set out to determine the relevance of increased droplet size and/or MFGM lipid droplet coating to the observed anti-obesogenic effects in adult life. From day 16 to 42, male mouse pups were exposed to diets with small (S) or large (L) lipid droplets (0·3 v. 2·9 µm average mode diameter, respectively), either without MFGM or with MFGM coating around the lipid droplet, resulting in four groups: S (control diet), L, Scoating and Lcoating (Nuturis® IMF diet). Mice were subsequently challenged with a Western-style diet until dissection at postnatal day 98. A non-challenged group served as reference (REF). We repeatedly determined body composition between postnatal day 42 and 98. At day 98 plasma and gene expression measurements were performed. Only the Nuturis® IMF diet (Lcoating) in early life containing MFGM-coated large lipid droplets reduced body fat mass to a level comparable with the REF group. These data support the notion that the structural aspects of lipids in human milk, for example, both lipid droplet size as well as the MFGM coating, may contribute to its reported protective effect against obesity in later life.

  13. The bacterial lipocalins.

    Science.gov (United States)

    Bishop, R E

    2000-10-18

    The lipocalins were once regarded as a eukaryotic protein family, but new members have been recently discovered in bacteria. The first bacterial lipocalin (Blc) was identified in Escherichia coli as an outer membrane lipoprotein expressed under conditions of environmental stress. Blc is distinguished from most lipocalins by the absence of intramolecular disulfide bonds, but the presence of a membrane anchor is shared with two of its closest homologues, apolipoprotein D and lazarillo. Several common features of the membrane-anchored lipocalins suggest that each may play an important role in membrane biogenesis and repair. Additionally, Blc proteins are implicated in the dissemination of antibiotic resistance genes and in the activation of immunity. Recent genome sequencing efforts reveal the existence of at least 20 bacterial lipocalins. The lipocalins appear to have originated in Gram-negative bacteria and were probably transferred horizontally to eukaryotes from the endosymbiotic alpha-proteobacterial ancestor of the mitochondrion. The genome sequences also reveal that some bacterial lipocalins exhibit disulfide bonds and alternative modes of subcellular localization, which include targeting to the periplasmic space, the cytoplasmic membrane, and the cytosol. The relationships between bacterial lipocalin structure and function further illuminate the common biochemistry of bacterial and eukaryotic cells.

  14. PENGARUH KOMPOSOSI LAPISAN PADA PERMUKAAN GLOBULA MINYAK EMULSI SEBELUM PENGERINGAN SEMPROT TERHADAP SIFAT-SIFAT MIKROKAMSUL TRIGLISERIDA KAYA ASAM LEMAK W-3 [The Effect of the Composition of Adsorbed Layer at Globule Interface of -3 Fatty Acids Enriched Triglyceride Prior to Spray Drying on its Microcapsule Properties

    Directory of Open Access Journals (Sweden)

    Moch Adnan2

    2005-04-01

    Full Text Available Emulsification is the critical factor in microencapsulation by spray drying method. Sodium caseinate is a protein with good emulsifying properties. The properties could be improved by phospholipids addition in the emulsification. Phospholipids addition which stabilized oil globule might change the composition of adsorbed layer.This research was conducted to analyze the changes in composition at oil globule interface by analyzing emulsion systems of triglyceride enriched by -3 fatty acids at 5% (w/v stabilized by sodium caseinate (10% w/v and addition of phospholipids at 0; 0,5; 1,0; 1,5; 2,0; and 2,5% (w/v. The changes in composition of adsorbed layer could be determined from the changes in phospholipids and adsorbed protein concentrations at oil globule interface. Analyses were done to measure the possibility of casein-phospholipids complex, phospholipids and protein adsorption concentration at interface, and adsorbed protein.The increase of phospholipids concentration in the emulsions stabilized by sodium caseinate changed the composition of adsorbed layer at interface. There was phospholipids increase and adsorbed protein decrease at oil globule interface. These changes were caused by casein-phospholipids complex which that decreased surface activity and displacement protein by phospholipids that was adsorbed at oil globule interface.Changes of composition of casein-phospholipids at oil globule prior to microcapsulation process caused changes in the properties of microcapsule produced. The increasing phospholipids and decreasing casein concentrations at oil globule interface decreased the quality of the microcapsule, including decreasing in microencapsulation efficiency, in oxidative stability, and decreasing in EPA+DHA content.

  15. 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.

  16. Anthropogenic sulfur dioxide emissions: 1850–2005

    Directory of Open Access Journals (Sweden)

    S. J. Smith

    2011-02-01

    Full Text Available Sulfur aerosols impact human health, ecosystems, agriculture, and global and regional climate. A new annual estimate of anthropogenic global and regional sulfur dioxide emissions has been constructed spanning the period 1850–2005 using a bottom-up mass balance method, calibrated to country-level inventory data. Global emissions peaked in the early 1970s and decreased until 2000, with an increase in recent years due to increased emissions in China, international shipping, and developing countries in general. An uncertainty analysis was conducted including both random and systemic uncertainties. The overall global uncertainty in sulfur dioxide emissions is relatively small, but regional uncertainties ranged up to 30%. The largest contributors to uncertainty at present are emissions from China and international shipping. Emissions were distributed on a 0.5° grid by sector for use in coordinated climate model experiments.

  17. The Properties of Sulfur Rubber Concrete (SRC)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The mix designs and specimen preparation for the dry process and wet process of sulfur rubber concrete (SRC) were investigated.The compressive strength, corrosion-resistance and toughness were studied and discussed.The results show that SRC is corrosion-resistanct.Although the compressive strength of SRC decreases with increasing rubber content, the toughness increases instead.Adding micro-filler will improve the compressive strength of SRC. There is a threshold value for the sulfur content, at which the compressive strength and the work ability of SRC reach an optimum balanc e.The bond between rubber particles and surrounding sulfur is strong due to the vulcanization process that generates cross-links through S-C bonds.

  18. Sulfur isotope homogeneity of lunar mare basalts

    Science.gov (United States)

    Wing, Boswell A.; Farquhar, James

    2015-12-01

    We present a new set of high precision measurements of relative 33S/32S, 34S/32S, and 36S/32S values in lunar mare basalts. The measurements are referenced to the Vienna-Canyon Diablo Troilite (V-CDT) scale, on which the international reference material, IAEA-S-1, is characterized by δ33S = -0.061‰, δ34S ≡ -0.3‰ and δ36S = -1.27‰. The present dataset confirms that lunar mare basalts are characterized by a remarkable degree of sulfur isotopic homogeneity, with most new and published SF6-based sulfur isotope measurements consistent with a single mass-dependent mean isotopic composition of δ34S = 0.58 ± 0.05‰, Δ33S = 0.008 ± 0.006‰, and Δ36S = 0.2 ± 0.2‰, relative to V-CDT, where the uncertainties are quoted as 99% confidence intervals on the mean. This homogeneity allows identification of a single sample (12022, 281) with an apparent 33S enrichment, possibly reflecting cosmic-ray-induced spallation reactions. It also reveals that some mare basalts have slightly lower δ34S values than the population mean, which is consistent with sulfur loss from a reduced basaltic melt prior to eruption at the lunar surface. Both the sulfur isotope homogeneity of the lunar mare basalts and the predicted sensitivity of sulfur isotopes to vaporization-driven fractionation suggest that less than ≈1-10% of lunar sulfur was lost after a potential moon-forming impact event.

  19. Production of Lunar Concrete Using Molten Sulfur

    Science.gov (United States)

    Omar, Husam A.

    1993-01-01

    The United States has made a commitment to go back to the moon to stay in the early part of the next century. In order to achieve this objective it became evident to NASA that a Lunar Outpost will be needed to house scientists and astronauts who will be living on the moon for extended periods of time. A study has been undertaken by the authors and supported by NASA to study the feasibility of using lunar regolith with different binders such as molten sulfur, epoxy or hydraulic cement as a construction material for different lunar structures. The basic premise of this study is that it will be more logical and cost effective to manufacture lunar construction materials utilizing indigenous resources rather than transporting needed materials from earth. Lunar concrete (made from Hydraulic Cement and lunar soil) has been studied and suggested as the construction material of choice for some of the lunar projects. Unfortunately, its hydration requires water which is going to be a precious commodity on the moon. Therefore this study explores the feasibility of using binders other than hydraulic cement such as sulfur or epoxy with lunar regolith as a construction material. This report describes findings of this study which deals specifically with using molten sulfur as a binder for Lunar concrete. It describes laboratory experiments in which the sulfur to lunar soil simulant ratios by weight were varied to study the minimum amount of sulfur required to produce a particular strength. The compressive and tensile strengths of these mixes were evaluated. Metal and fiber glass fibers were added to some of the mixes to study their effects on the compressive and tensile strengths. This report also describes experiments where the sulfur is melted and mixed with the lunar regolith in a specially designed vacuum chamber. The properties of the produced concrete were compared to those of concrete produced under normal pressure.

  20. Conductive framework of inverse opal structure for sulfur cathode in lithium-sulfur batteries

    Science.gov (United States)

    Jin, Lu; Huang, Xiaopeng; Zeng, Guobo; Wu, Hua; Morbidelli, Massimo

    2016-01-01

    As a promising cathode inheritor for lithium-ion batteries, the sulfur cathode exhibits very high theoretical volumetric capacity and energy density. In its practical applications, one has to solve the insulating properties of sulfur and the shuttle effect that deteriorates cycling stability. The state-of-the-art approaches are to confine sulfur in a conductive matrix. In this work, we utilize monodisperse polystyrene nanoparticles as sacrificial templates to build polypyrrole (PPy) framework of an inverse opal structure to accommodate (encapsulate) sulfur through a combined in situ polymerization and melting infiltration approach. In the design, the interconnected conductive PPy provides open channels for sulfur infiltration, improves electrical and ionic conductivity of the embedded sulfur, and reduces polysulfide dissolution in the electrolyte through physical and chemical adsorption. The flexibility of PPy and partial filling of the inverse opal structure endure possible expansion and deformation during long-term cycling. It is found that the long cycling stability of the cells using the prepared material as the cathode can be substantially improved. The result demonstrates the possibility of constructing a pure conductive polymer framework to accommodate insulate sulfur in ion battery applications. PMID:27600885

  1. Nickel fibers/sulfur composites cathode with enhanced electrochemical performance for rechargeable lithium-sulfur batteries

    International Nuclear Information System (INIS)

    Highlights: • A novel Nickel fibers was developed as additive for sulfur cathode. • Composite cathode containing 3% nickel fibers has remarkable cycling stability and great rate capability. • Electrochemical analysis shows nickel fibers can absorb polysulfides, improve electronic conductivity, and facilitate the redox reactions in sulfur cathode. - Abstract: The commercialization of lithium sulfur batteries have so far hindered by the low electrochemical utilization and rapid capacity fading of sulfur cathode, which is induced by low electron conductivity and high dissolution of intermediate polysulfides. Recent studies have shown that the metal (Pt, Au, Ni) as electrocatalyst of lithium polysulfides and its metallic porous nanostructure can suppress the shuttle effect. In this work, we use the porous nanostructure of nickel fibers/sulfur as-designed composite cathode material for lithium sulfur batteries. The initial discharge capacity of the cathode with the added 3(%) nickel fibers was 805 mAh g−1, and the remaining capacity was 440 mAh g−1 after 50 cycles at 0.766 mA cm−2. Even at a high current density of 1.532 mA cm−2, it also kept a high discharge capacity of 310 mAh g−1. Compared with pure sulfur electrodes, the electrodes containing nickel fibers showed an obviously improved cycle and rate performances, confirming that metallic porous nanostructure of nickel can not only contribute to reducing the dissolution of polysulfides into electrolytes, but also has a catalytic effect on the redox reactions during charge-discharge process

  2. Conductive framework of inverse opal structure for sulfur cathode in lithium-sulfur batteries.

    Science.gov (United States)

    Jin, Lu; Huang, Xiaopeng; Zeng, Guobo; Wu, Hua; Morbidelli, Massimo

    2016-01-01

    As a promising cathode inheritor for lithium-ion batteries, the sulfur cathode exhibits very high theoretical volumetric capacity and energy density. In its practical applications, one has to solve the insulating properties of sulfur and the shuttle effect that deteriorates cycling stability. The state-of-the-art approaches are to confine sulfur in a conductive matrix. In this work, we utilize monodisperse polystyrene nanoparticles as sacrificial templates to build polypyrrole (PPy) framework of an inverse opal structure to accommodate (encapsulate) sulfur through a combined in situ polymerization and melting infiltration approach. In the design, the interconnected conductive PPy provides open channels for sulfur infiltration, improves electrical and ionic conductivity of the embedded sulfur, and reduces polysulfide dissolution in the electrolyte through physical and chemical adsorption. The flexibility of PPy and partial filling of the inverse opal structure endure possible expansion and deformation during long-term cycling. It is found that the long cycling stability of the cells using the prepared material as the cathode can be substantially improved. The result demonstrates the possibility of constructing a pure conductive polymer framework to accommodate insulate sulfur in ion battery applications. PMID:27600885

  3. Sulfur contents and sulfur-isotope compositions of thiotrophic symbioses in bivalve molluscs and vestimentiferan worms

    Science.gov (United States)

    Vetter, R.D.; Fry, B.

    1998-01-01

    Total sulfur (S(TOT)), elemental sulfur (S??) and sulfur-isotope compositions (??34S) of marine animals were analyzed to determine whether these chemical characteristics could help distinguish animals with a sulfur-based, thiotrophic nutrition from animals whose nutrition is based on methanotrophy or on more normal consumption of phytoplankton-derived organic matter. The presence of S??was almost entirely confined to the symbiont-containing tissues of thiotrophs, but was sometimes undetectable in thiotrophic species where sulfide availability was probably low. When S??contents were subtracted, the remaining tissue-sulfur concentrations were similar for all nutritional groups. ??34S values were typically lower for thiotrophs than for other groups, although there was overlap in methanotroph and thiotroph values at some sites. Field evidence supported the existence of small to moderate (1 to 10???)34S fractionations in the uptake of sulfides and metabolism of thiosulfate. In general, a total sulfur content of >3% dry weight, the presence of elemental sulfur, and ??34S values less than + 5??? can be used to infer a thiotrophic mode of nutrition.

  4. Conductive framework of inverse opal structure for sulfur cathode in lithium-sulfur batteries.

    Science.gov (United States)

    Jin, Lu; Huang, Xiaopeng; Zeng, Guobo; Wu, Hua; Morbidelli, Massimo

    2016-09-07

    As a promising cathode inheritor for lithium-ion batteries, the sulfur cathode exhibits very high theoretical volumetric capacity and energy density. In its practical applications, one has to solve the insulating properties of sulfur and the shuttle effect that deteriorates cycling stability. The state-of-the-art approaches are to confine sulfur in a conductive matrix. In this work, we utilize monodisperse polystyrene nanoparticles as sacrificial templates to build polypyrrole (PPy) framework of an inverse opal structure to accommodate (encapsulate) sulfur through a combined in situ polymerization and melting infiltration approach. In the design, the interconnected conductive PPy provides open channels for sulfur infiltration, improves electrical and ionic conductivity of the embedded sulfur, and reduces polysulfide dissolution in the electrolyte through physical and chemical adsorption. The flexibility of PPy and partial filling of the inverse opal structure endure possible expansion and deformation during long-term cycling. It is found that the long cycling stability of the cells using the prepared material as the cathode can be substantially improved. The result demonstrates the possibility of constructing a pure conductive polymer framework to accommodate insulate sulfur in ion battery applications.

  5. Confine sulfur in mesoporous metal–organic framework @ reduced graphene oxide for lithium sulfur battery

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Weizhai [School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083 (China); Zhang, Zhian, E-mail: zza75@163.com [School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083 (China); Engineering Research Center of High Performance Battery Materials and Devices, Research Institute of Central South University in Shenzhen, Shenzhen 518057 (China); Qu, Yaohui; Zhou, Chengkun; Wang, Xiwen [School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083 (China); Li, Jie [School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083 (China); Engineering Research Center of High Performance Battery Materials and Devices, Research Institute of Central South University in Shenzhen, Shenzhen 518057 (China)

    2014-01-05

    Highlights: • Metal organic framework @ reduced graphene oxide was applied for sulfur cathode. • MIL-101(Cr)@rGO/S composites are synthesized by a facile two-step liquid method. • Cycling stability of MIL-101(Cr)@rGO/S sulfur cathode was improved. -- Abstract: Mesoporous metal organic framework @ reduced graphene oxide (MIL-101(Cr)@rGO) materials have been used as a host material to prepare the multi-composite sulfur cathode through a facile and effective two-step liquid phase method successfully, which is different from the simple MIL-101(Cr)/S mixed preparation method. The successful reduced graphene oxide coating in the MIL-101(Cr)@rGO improve the electronic conductivity of meso-MOFs effectively. The discharge capacity and capacity retention rate of MIL-101(Cr)@rGO/S composite sulfur cathode are as high as 650 mAh g{sup −1} and 66.6% at the 50th cycle at the current density of 335 mA g{sup −1}. While the discharge capacity and capacity retention rate of MIL-101(Cr)/S mixed sulfur cathode is 458 mAh g{sup −1} and 37.3%. Test results indicate that the MIL-101(Cr)@rGO is a promising host material for the sulfur cathode in the lithium–sulfur battery applications.

  6. Multi-isotope biogeochemistry of sulfur in the water column and surface sediments of the Baltic Sea

    Science.gov (United States)

    Böttcher, M. E.; Kamyshny, A.; Dellwig, O.; Farquhar, J.

    2012-04-01

    -reducing bacteria at low cellular activities using simple organic substrates. Sulfur isotope partitioning in the water column is close to results found in the (post-)modern surface sediments, but increases with sediment depth. Combined delta34S and delta-cap33S results give no evidence for a substantial contribution from the bacterial disproportionation of sulfur intermediates on sulfur cycling. Acknowledgements: Research was supported by Leibniz IOW and German Science Foundation, DFG (research cruises of RV Merian)

  7. Biosynthesis of Iron-Sulfur Clusters

    OpenAIRE

    Yuvaniyama, Pramvadee

    1999-01-01

    It is not known whether biosynthesis of [Fe-S] clusters occurs through a spontaneous self-assembly process or an enzymatic process. However, in the Azotobacter vinelandii nitrogenase system, it has been proposed that NifS and NifU are involved in the mobilization of sulfur and iron necessary for nitrogenase-specific [Fe-S] cluster assembly. The NifS protein has been shown to have cysteine desulfurase activity and can be used to supply sulfur for the in vitro catalytic formation of [Fe-S] cl...

  8. Diagnosis of bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Đukić Slobodanka

    2013-01-01

    Full Text Available Bacterial vaginosis is a common, complex clinical syndrome characterized by alterations in the normal vaginal flora. When symptomatic, it is associated with a malodorous vaginal discharge and on occasion vaginal burning or itching. Under normal conditions, lactobacilli constitute 95% of the bacteria in the vagina. Bacterial vaginosis is associated with severe reduction or absence of the normal H2O2­producing lactobacilli and overgrowth of anaerobic bacteria and Gardnerella vaginalis, Atopobium vaginae, Mycoplasma hominis and Mobiluncus species. Most types of infectious disease are diagnosed by culture, by isolating an antigen or RNA/DNA from the microbe, or by serodiagnosis to determine the presence of antibodies to the microbe. Therefore, demonstration of the presence of an infectious agent is often a necessary criterion for the diagnosis of the disease. This is not the case for bacterial vaginosis, since the ultimate cause of the disease is not yet known. There are a variety of methods for the diagnosis of bacterial vaginosis but no method can at present be regarded as the best. Diagnosing bacterial vaginosis has long been based on the clinical criteria of Amsel, whereby three of four defined criteria must be satisfied. Nugent’s scoring system has been further developed and includes validation of the categories of observable bacteria structures. Up­to­date molecular tests are introduced, and better understanding of vaginal microbiome, a clear definition for bacterial vaginosis, and short­term and long­term fluctuations in vaginal microflora will help to better define molecular tests within the broader clinical context.

  9. Bacterial glycosyltransferase toxins.

    Science.gov (United States)

    Jank, Thomas; Belyi, Yury; Aktories, Klaus

    2015-12-01

    Mono-glycosylation of host proteins is a common mechanism by which bacterial protein toxins manipulate cellular functions of eukaryotic target host cells. Prototypic for this group of glycosyltransferase toxins are Clostridium difficile toxins A and B, which modify guanine nucleotide-binding proteins of the Rho family. However, toxin-induced glycosylation is not restricted to the Clostridia. Various types of bacterial pathogens including Escherichia coli, Yersinia, Photorhabdus and Legionella species produce glycosyltransferase toxins. Recent studies discovered novel unexpected variations in host protein targets and amino acid acceptors of toxin-catalysed glycosylation. These findings open new perspectives in toxin as well as in carbohydrate research.

  10. A new study of an old sink of sulfur in hot molecular cores: the sulfur residue

    OpenAIRE

    Woods, Paul M.; Occhiogrosso, Angela; Viti, Serena; Kanuchova, Z.; Palumbo, Maria Elisabetta; Price, Stephen D.

    2015-01-01

    Sulfur appears to be depleted by an order of magnitude or more from its elemental abundance in star-forming regions. In the last few years, numerous observations and experiments have been performed in order to to understand the reasons behind this depletion without providing a satisfactory explanation of the sulfur chemistry towards high-mass star-forming cores. Several sulfur-bearing molecules have been observed in these regions, and yet none are abundant enough to make up the gas-phase defi...

  11. Interaction of sulfur-loaded 3A zeolite with ethylene

    OpenAIRE

    Munter, H.J.

    2006-01-01

    The sulfur-loaded 3A clay-bond molecular sieve exposed to ethylene at temperatures higher than 190°C loses its sulfur. Mainly hydrogen sulfide is formed. This behavior restricts its use as a cracking catalyst.

  12. Total Sulfur Deposition (wet+dry) from the Atmosphere

    Data.gov (United States)

    U.S. Environmental Protection Agency — Sulfur Dioxide (SO2) is emitted primarily as a by-product of coal combustion from power plants. Sulfur Dioxide reacts in the atmosphere to form other chemical such...

  13. The Low-temperature Ion Sulfurizing Technology and its Applications

    Science.gov (United States)

    Ma, G. Z.; Xu, B. S.; Wang, H. D.; Li, G. L.; Zhang, S.

    A solid lubrication film mainly consists of FeS, which has excellent tribology properties, can be formed on the sulfurized iron or steel surface. The sulfurizing technology has aroused intense attention from the day it appeared. However, the widespread industrial application of sulfurizing technology was promoted by the low-temperature ion sulfurizing (LTIS) process. This paper summarized the phylogeny and sorts of sulfurizing technology firstly; then, the process flow of LTIS technology, the forming mechanism, microstructure and tribological properties of ion sulfurized layer were introduced detailedly; and then, the technological, economic and environmental merits of LTIS technology were generalized; finally, the industrial applications of LTIS technology in various typical rolling, sliding and heavy duty parts were reviewed briefly. LTIS technology, with the advantages of high sulfurizing speed, good performance of sulfurized layer and without sideeffect, has played an important role in the tribology modification of ferrous parts, and the LTIS process will become more green, simple and efficient in the future.

  14. 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.

  15. Redox control of sulfur degassing in silicic magmas

    OpenAIRE

    Scaillet, Bruno; Clémente, Béatrice; Evans, Bernard W.; Pichavant, Michel

    1998-01-01

    International audience Explosive eruptions involve mainly silicic magmas in which sulfur solubility and diffusivity are low. This inhibits sulfur exsolution during magma uprise as compared to more mafic magmas such as basalts. Silicic magmas can nevertheless liberate large quantities of sulfur as shown by the monitoring of SO2 in recent explosive silicic eruptions in arc settings, which invariably have displayed an excess of sulfur relative to that calculated from melt degassing. If this e...

  16. Biological and Abiological Sulfur Reduction at High Temperatures †

    OpenAIRE

    Belkin, Shimshon; Wirsen, Carl O.; Jannasch, Holger W.

    1985-01-01

    Reduction of elemental sulfur was studied in the presence and absencè of thermophilic sulfur-reducing bacteria, at temperatures ranging from 65 to 110°C, in anoxic artificial seawater media. Above 80°C, significant amounts of sulfide were produced abiologically at linear rates, presumably by the disproportionation of sulfur. These rates increased with increasing temperature and pH and were enhanced by yeast extract. In the same medium, the sulfur respiration of two recent thermophilic isolate...

  17. Sulfur-containing compounds in \\kur{Ferula} species

    OpenAIRE

    TICHÁ, Iveta

    2012-01-01

    The theoretical part of the Bachelor thesis is focused on Ferula genus plants, their significance, occurrence and usage. The thesis also deals with their sulfur-containing compounds and the formation pathways of the sulfur compounds occurring in the Allium genus. In the experimental part, the most important Ferula volatile sulfur compounds and their possible precursor are investigated. The precursor was suggested on the basis of the principle of similar sulfur compounds in Ferula genus plants...

  18. Electrochemical Lithiation of Covalently Bonded Sulfur in Vulcanized Polyisoprene

    OpenAIRE

    Fu, Chengyin; Li, Guanghui; Zhang, Jian; Cornejo, Benjamin; Piao, Sophie S.; Krassimir N. Bozhilov; Haddon, Robert C.; Guo, Juchen

    2016-01-01

    We report the synthesis of vulcanized polyisoprene (SPIP) nanowires and an investigation of the electrochemical lithiation mechanism of the covalently bonded sulfur bridges in SPIP. Electrochemical analysis demonstrates that the sulfur chains in SPIP have distinct electrochemical signatures from those that are characteristic of bulk elemental sulfur. The cyclic voltammetry and galvanostatic cycling data show a distinct multistep charge-transfer process and solid-state lithium–sulfur reaction ...

  19. Oxidation of inorganic sulfur compounds in acidophilic prokaryotes

    Energy Technology Data Exchange (ETDEWEB)

    Rohwerder, T.; Sand, W. [Universitaet Duisburg-Essen, Biofilm Centre, Aquatic Biotechnology, Duisburg (Germany)

    2007-07-15

    The oxidation of reduced inorganic sulfur compounds to sulfuric acid is of great importance for biohydrometallurgical technologies as well as the formation of acidic (below pH 3) and often heavy metal-contaminated environments. The use of elemental sulfur as an electron donor is the predominant energy-yielding process in acidic natural sulfur-rich biotopes but also at mining sites containing sulfidic ores. Contrary to its significant role in the global sulfur cycle and its biotechnological importance, the microbial fundamentals of acidophilic sulfur oxidation are only incompletely understood. Besides giving an overview of sulfur-oxidizing acidophiles, this review describes the so far known enzymatic reactions related to elemental sulfur oxidation in acidophilic bacteria and archaea. Although generally similar reactions are employed in both prokaryotic groups, the stoichiometry of the key enzymes is different. Bacteria oxidize elemental sulfur by a sulfur dioxygenase to sulfite whereas in archaea, a sulfur oxygenase reductase is used forming equal amounts of sulfide and sulfite. In both cases, the activation mechanism of elemental sulfur is not known but highly reactive linear sulfur forms are assumed to be the actual substrate. Inhibition as well as promotion of these biochemical steps is highly relevant in bioleaching operations. An efficient oxidation can prevent the formation of passivating sulfur layers. In other cases, a specific inhibition of sulfur biooxidation may be beneficial for reducing cooling and neutralization costs. In conclusion, the demand for a better knowledge of the biochemistry of sulfur-oxidizing acidophiles is underlined. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  20. Field environmental evaluation plan for sulfur use in pavements

    Science.gov (United States)

    Saylak, D.; Deuel, L. E.; Izatt, J. O.; Jacobs, C.; Zahray, R.; Ham, S.

    1982-07-01

    The use of sulfur in highway paving mixtures is discussed. The evaluation procedures deal with the safety and environmental aspects of storage and handling, formulation, construction, operation and maintenance of highway pavements containing sulfur, including the possible generation of noxious and abnoxious fumes, dust and gases. Methods and equipment for monitoring potential emissions and pollutants are recommended and safety practices for the handling of sulfur and sulfur-modified asphalt mixtures and pavements are discussed.

  1. Seizures Complicating Bacterial Meningitis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-09-01

    Full Text Available The clinical data of 116 patients, 1 month to <5 years of age, admitted for bacterial meningitis, and grouped according to those with and without seizures during hospitalization, were compared in a study at Buddhist Dalin Tzu Chi General Hospital, Chang Gung Memorial Hospital and other centers in Taiwan.

  2. Bacterial extracellular lignin peroxidase

    Science.gov (United States)

    Crawford, Donald L.; Ramachandra, Muralidhara

    1993-01-01

    A newly discovered lignin peroxidase enzyme is provided. The enzyme is obtained from a bacterial source and is capable of degrading the lignin portion of lignocellulose in the presence of hydrogen peroxide. The enzyme is extracellular, oxidative, inducible by lignin, larch wood xylan, or related substrates and capable of attacking certain lignin substructure chemical bonds that are not degradable by fungal lignin peroxidases.

  3. Bacterial Skin Infections

    Science.gov (United States)

    ... or scraped, the injury should be washed with soap and water and covered with a sterile bandage. Petrolatum may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. Doctors recommend that people do not use ...

  4. Vimentin in Bacterial Infections

    DEFF Research Database (Denmark)

    Mak, Tim N; Brüggemann, Holger

    2016-01-01

    filaments (IFs). IFs have not only roles in maintaining the structural integrity of the cell, but they are also involved in many cellular processes including cell adhesion, immune signaling, and autophagy, processes that are important in the context of bacterial infections. Here, we summarize the knowledge...

  5. Bacterial microflora of nectarines

    Science.gov (United States)

    Microflora of fruit surfaces has been the best source of antagonists against fungi causing postharvest decays of fruit. However, there is little information on microflora colonizing surfaces of fruits other than grapes, apples, and citrus fruit. We characterized bacterial microflora on nectarine f...

  6. Modeling intraocular bacterial infections.

    Science.gov (United States)

    Astley, Roger A; Coburn, Phillip S; Parkunan, Salai Madhumathi; Callegan, Michelle C

    2016-09-01

    Bacterial endophthalmitis is an infection and inflammation of the posterior segment of the eye which can result in significant loss of visual acuity. Even with prompt antibiotic, anti-inflammatory and surgical intervention, vision and even the eye itself may be lost. For the past century, experimental animal models have been used to examine various aspects of the pathogenesis and pathophysiology of bacterial endophthalmitis, to further the development of anti-inflammatory treatment strategies, and to evaluate the pharmacokinetics and efficacies of antibiotics. Experimental models allow independent control of many parameters of infection and facilitate systematic examination of infection outcomes. While no single animal model perfectly reproduces the human pathology of bacterial endophthalmitis, investigators have successfully used these models to understand the infectious process and the host response, and have provided new information regarding therapeutic options for the treatment of bacterial endophthalmitis. This review highlights experimental animal models of endophthalmitis and correlates this information with the clinical setting. The goal is to identify knowledge gaps that may be addressed in future experimental and clinical studies focused on improvements in the therapeutic preservation of vision during and after this disease. PMID:27154427

  7. Sulfur Dioxide Emission Control, Blockade and Drainage

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper presents the present status of sulfur dioxide emission from thermal plants in China, tells the main problems existing in its emission control and finally gives out suggestions to the problems, that is, to constitute complete standards and regulations and enhancesupervision accordingly.

  8. Helium and Sulfur Hexafluoride in Musical Instruments

    Science.gov (United States)

    Forinash, Kyle; Dixon, Cory L.

    2014-01-01

    The effects of inhaled helium on the human voice were investigated in a recent article in "The Physics Teacher." As mentioned in that article, demonstrations of the effect are a popular classroom activity. If the number of YouTube videos is any indication, the effects of sulfur hexafluoride on the human voice are equally popular.…

  9. Sulfur Upwelling off the African Coast

    Science.gov (United States)

    2002-01-01

    Though these aquamarine clouds in the waters off the coast of northern Namibia may look like algae blooms, they are in fact clouds of sulfur produced by anaerobic bacteria on the ocean's floor. This image of the sulfur-filled water was taken on April 24, 2002, by the Sea-viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the Orbview-2 satellite. The anaerobic bacteria (bacteria that can live without oxygen) feed upon algae carcasses that exist in abundance on the ocean's floor off of Namibia. As the bacteria ingest the algae husks, they produce hydrogen sulfide, which slowly builds up in the sea-floor sediments. Eventually, the hydrogen sulfide reaches the point where the sediment can no longer contain it, and it bubbles forth. When this poisonous chemical reaches the surface, it combines with the oxygen in the upper layers of the ocean to create clouds of pure sulfur. The sulfur causes the Namibian coast to smell like rotten eggs, and the hydrogen sulfide will often kill fish and drive lobsters away. For more information, read: A Bloom By Any Other Name A high-resolution (250 meters per pixel) image earlier on the 24th taken from the Moderate-Resolution Imaging Spectroradiometer (MODIS) shows additional detail in the plumes. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE. MODIS image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  10. Sulfur and selenium isotope separation by distillation

    International Nuclear Information System (INIS)

    Sulfur and selenium isotopes are used for labeled compounds and as precursors for radioisotope production; however, both limited availability and high costs are problems. A new method is needed for large-scale separation of these isotopes. Experimental distillation columns were used to measure isotopic separations for sulfur and selenium compounds. The maximum total isotope separation of 32S vs. 34S were 1.127 for H2S, 1.048 for COS, 0.838 for SF4, and 1.058 for CH3SH. Relative volatilities of 32S vs. 34S are 1.0006 for COS and 0.9976 for SF4. There is a reverse isotope effect for carbon in COS. No isotopic separation was observed for dimethyl selenide. The lower mass selenium isotopes in H2Se are more volatile. Distillation is a promising method for separating sulfur isotopes on a production scale. Existing distillation technology produced separated isotopes with an effect similar to that found for sulfur in SF4. 8 refs., 2 tabs

  11. Development of enhanced sulfur rejection processes

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, R.H.; Luttrell, G.H.; Adel, G.T.; Richardson, P.E.

    1996-03-01

    Research at Virginia Tech led to the development of two complementary concepts for improving the removal of inorganic sulfur from many eastern U.S. coals. These concepts are referred to as Electrochemically Enhanced Sulfur Rejection (EESR) and Polymer Enhanced Sulfur Rejection (PESR) processes. The EESR process uses electrochemical techniques to suppress the formation of hydrophobic oxidation products believed to be responsible for the floatability of coal pyrite. The PESR process uses polymeric reagents that react with pyrite and convert floatable middlings, i.e., composite particles composed of pyrite with coal inclusions, into hydrophilic particles. These new pyritic-sulfur rejection processes do not require significant modifications to existing coal preparation facilities, thereby enhancing their adoptability by the coal industry. It is believed that these processes can be used simultaneously to maximize the rejection of both well-liberated pyrite and composite coal-pyrite particles. The project was initiated on October 1, 1992 and all technical work has been completed. This report is based on the research carried out under Tasks 2-7 described in the project proposal. These tasks include Characterization, Electrochemical Studies, In Situ Monitoring of Reagent Adsorption on Pyrite, Bench Scale Testing of the EESR Process, Bench Scale Testing of the PESR Process, and Modeling and Simulation.

  12. RETENTION OF SULFUR DIOXIDE BY NYLON FILTERS

    Science.gov (United States)

    Based on laboratory studies, recovery efficiencies of sulfur dioxide (SO2) were determined for nylon filters. The nylon filters used in these experiments were found to retain SO2. A relatively uniform amount (1.7%) was recoverable from each nylon filter, independent of relative...

  13. 21 CFR 582.3862 - Sulfur dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sulfur dioxide. 582.3862 Section 582.3862 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives §...

  14. 21 CFR 182.3862 - Sulfur dioxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sulfur dioxide. 182.3862 Section 182.3862 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 182.3862...

  15. Phase transformations and the spectral reflectance of solid sulfur - Can metastable sulfur allotropes exist on Io?

    Science.gov (United States)

    Moses, Julianne I.; Nash, Douglas B.

    1991-01-01

    Laboratory investigations have been conducted on the effects of variations in sulfur sample histories on their solid-state transformation rate and the corresponding spectral variation of freshly frozen sulfur. The temporal variations in question may be due to differences in the amount and type of metastable allotropes present in the sulfur after solidification, as well as to the physics of the phase-transformation process itself. The results obtained are pertinent to the physical behavior and spectral variation of such freshly solidified sulfur as may exist on the Jupiter moon Io; this would initially solidify into a glassy solid or monoclinic crystalline lattice, then approach ambient dayside temperatures. Laboratory results imply that the monoclinic or polymeric allotropes can in these circumstances be maintained, and will take years to convert to the stable orthorhombic crystalline form.

  16. Sulfur isotopes in coal constrain the evolution of the Phanerozoic sulfur cycle

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene

    2013-01-01

    reaction of sulfide with iron produces pyrite whose burial in sediments is an important oxygen source to the atmosphere. The concentrations of seawater sulfate and the operation of sulfur cycle have experienced dynamic changes through Earth’s history, and our understanding of this history is based mainly...... of the isotope record and in the absence of better information, one assumes that the isotopic composition of the input sulfate to the oceans has remained constant through time. It is argued here that this assumption has a constraint over the last 390 Ma from the isotopic composition of sulfur in coal. Indeed......, these compositions do not deviate substantially from the modern surface-water input to the oceans. When applied to mass balance models, these results support previous interpretations of sulfur cycle operation and counter recent suggestions that sulfate has been a minor player in sulfur cycling through...

  17. X-ray microspectroscopy of sulfur in basaltic glass inclusions. Inference on the volcanic sulfur emissions

    Science.gov (United States)

    Métrich, N.; Susini, J.; Galoisy, L.; Calas, G.; Bonnin-Mosbah, M.; Menez, B.

    2003-03-01

    It is commonly accepted that sulfur is carried out as sulfide (S^{II-}) or/and sulfate (S^{VI}) by Earth mantlederived melts, before being released as SO2 and/or H2S in volcanic emissions. By analyzing reference compounds and a selection of minute glass inclusions in olivine crystals using μXANES (X-ray Near Edge Structure) spectroscopy at the sulfur K-edge, we demonstrated the ubiquitous presence of sulfite (S^{IV}) in addition to sulfate (S^{VI}) in these rare inclusions representative of oxidized and water rich-basaltic magmas, prior to loss of sulfur and water. The sulfide (S^{II-}) when exists is minor. We proposed that sulfite (S^{IV}) acts as an intermediate, metastable species which results in partitioning of sulfur into the volcanic gas emissions.

  18. Entraînement de globules d'huile par un tensio-actif. Etude de la formation du banc Mobilization of Oil Ganglia by a Surfactant Analysis of Bank Formation

    Directory of Open Access Journals (Sweden)

    Moulu J. C.

    2006-11-01

    Full Text Available Lors de l'injection d'une solution de tensio-actif dans un gisement déjà balayé par de l'eau, l'huile résiduelle, piégée sous la forme de globules discontinus, est remise en mouvement et se regroupe éventuellement sous la forme d'un banc d'huile. Le but de la présente étude est d'expliquer la formation de ce banc au cours d'un tel déplacement. Les résultats d'expériences réalisées en micromodèles de billes de verre permettent de constater que : - la récupération globale est corrélable avec le nombre capillaire Nc= uVdf/O, u et Vdf étant la viscosité et la vitesse de Darcy du fluide injecté, O la tension interfaciale avec l'huile en place ; - la vitesse des globules varie différemment avec u, Vdf, O et tend vers la même limite plus grande que la vitesse du fluide injecté pour de grandes valeurs du nombre capillaire Nc ; - le banc d'huile ne se forme que dans le cas où la vitesse des globules atteint celle du fluide injecté. L'huile déplacée reste alors groupée avec une saturation importante au niveau du front de tensio-actif. When a surfactant solution is injected into a reservoir previously waterflooded, the residual oil trapped as discontinuous ganglia is mobilized and eventually bunched together forming an oil bank. The aim of this study is to explain the formation of this bank during such a drive. The results of experiments performed in micromodels of glass beads show that: a Overall recovery can be correlated with the capillary number, Nc = uVfd/O, in which u and Vfd are the viscosity a and Darcy velocity of the injected fluid and O is the interfacial tension with the oil in place. b Ganglia velocity varies differently with u, Vfd and O, and it tends towards the same limit faster than the velocity of the injected fluid for high values of the capillary number Nc. c The oil bank is formed only in the case where globule velocity attaints that of injected fluid. the dispaced oil then remains bunched, with high

  19. Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment

    OpenAIRE

    Koh, Eunmi; Surh, Jeonghee

    2016-01-01

    Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing ...

  20. Rnf Genes in Purple Sulfur Bacterium Allochromatium vinosum

    OpenAIRE

    DİNÇTÜRK, H. Benan; DEMİR, Volkan

    2006-01-01

    Allochromatium vinosum is a photosynthetic, diazotrophic purple sulfur bacterium that oxidizes reduced sulfur compounds hydrogen sulfide, elemental sulfur and thiosulfide. In this article, we report the presence of rnf genes in Allochromatium vinosum, some of which have been reported to take part in nitrogen fixation in some species.

  1. 46 CFR 153.545 - Special requirements for liquid sulfur.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Special requirements for liquid sulfur. 153.545 Section... Equipment Special Requirements § 153.545 Special requirements for liquid sulfur. (a) A containment system carrying liquid sulfur must have: (1) A cargo tank ventilation system that: (i) Maintains the H2S...

  2. The role of bacteria and mycorrhiza in plant sulfur supply

    Science.gov (United States)

    Gahan, Jacinta; Schmalenberger, Achim

    2014-01-01

    Plant growth is highly dependent on bacteria, saprophytic, and mycorrhizal fungi which facilitate the cycling and mobilization of nutrients. Over 95% of the sulfur (S) in soil is present in an organic form. Sulfate-esters and sulfonates, the major forms of organo-S in soils, arise through deposition of biological material and are transformed through subsequent humification. Fungi and bacteria release S from sulfate-esters using sulfatases, however, release of S from sulfonates is catalyzed by a bacterial multi-component mono-oxygenase system. The asfA gene is used as a key marker in this desulfonation process to study sulfonatase activity in soil bacteria identified as Variovorax, Polaromonas, Acidovorax, and Rhodococcus. The rhizosphere is regarded as a hot spot for microbial activity and recent studies indicate that this is also the case for the mycorrhizosphere where bacteria may attach to the fungal hyphae capable of mobilizing organo-S. While current evidence is not showing sulfatase and sulfonatase activity in arbuscular mycorrhiza, their effect on the expression of plant host sulfate transporters is documented. A revision of the role of bacteria, fungi and the interactions between soil bacteria and mycorrhiza in plant S supply was conducted. PMID:25566295

  3. The role of bacteria and mycorrhiza in plant sulfur supply

    Directory of Open Access Journals (Sweden)

    Jacinta Mariea Gahan

    2014-12-01

    Full Text Available Plant growth is highly dependent on bacteria, saprophytic and mycorrhizal fungi which facilitate the cycling and mobilization of nutrients. Over 95% of the sulfur (S in soil is present in an organic form. Sulfate-esters and sulfonates, the major forms of organo-S in soils, arise through deposition of biological material and are transformed through subsequent humification. Fungi and bacteria release S from sulfate-esters using sulfatases, however, release of S from sulfonates is catalyzed by a bacterial multi-component mono-oxygenase system. The asfA gene is used as a key marker in this desulfonation process to study sulfonatase activity in soil bacteria identified as Variovorax, Polaromonas, Acidovorax and Rhodococcus. The rhizosphere is regarded as a hot spot for microbial activity and recent studies indicate that this is also the case for the mycorrhizosphere where bacteria may attach to the fungal hyphae capable of mobilizing organo-S. While current evidence is not showing sulfatase and sulfonatase activity in arbuscular mycorrhiza, their effect on the expression of plant host sulfate transporters is documented. A revision of the role of bacteria, fungi and the interactions between soil bacteria and mycorrhiza in plant S supply was conducted.

  4. Regulation of dissimilatory sulfur oxidation in the purple sulfur bacterium Allochromatium vinosum

    OpenAIRE

    Frauke eGrimm; Bettina eFranz; Christiane eDahl

    2011-01-01

    In the purple sulfur bacterium Allochromatium vinosum, thiosulfate oxidation is strictly dependent on the presence of three periplasmic Sox proteins encoded by the soxBXAK and soxYZ genes. It is also well documented that proteins encoded in the dissimilatory sulfite reductase (dsr) operon, dsrABEFHCMKLJOPNRS, are essential for the oxidation of sulfur that is stored intracellularly as an obligatory intermediate during the oxidation of thiosulfate and sulfide. Until recently, detailed knowledge...

  5. Effects of sulfur oxides on eicosanoids

    International Nuclear Information System (INIS)

    Ultrafine metal oxides and SO2 react during coal combustion or smelting operations to form primary emissions coated with an acidic SOx layer. Ongoing work in this laboratory has examined the effects of sulfur oxides on pulmonary functions of guinea pigs. We have previously reported that 20 micrograms/m3 acidic sulfur oxide as a surface layer on ultrafine ZnO particles decreases lung volumes, decreases carbon monoxide diffusing capacity, and causes lung inflammation in guinea pigs after 4 daily 3-h exposures. It also produces bronchial hypersensitivity following a single 1-h exposure. The importance of this surface layer is demonstrated by our observation that 200 micrograms/m3 of sulfuric acid droplets of equivalent size are needed to produce the same degree of hypersensitivity. This study characterized the concentration-dependent effects of in vivo exposures to sulfur oxides on arachidonic acid metabolism in the guinea pig lung, and investigated the time course and the relation between eicosanoid composition and pulmonary functions. We focused specifically on four cyclooxygenase metabolites of arachidonic acid, that is, prostaglandins (PG) E1, F2 alpha, 6-keto prostaglandin F1 alpha, and thromboxane (Tx) B2, and two groups of sulfidopeptide leukotrienes (C4, D4, E4, and F4). Guinea pigs were exposed to ultrafine ZnO aerosol (count median diameter = 0.05 microns, sigma g = 1.80) with a layer of acidic sulfur oxide on the surface of the particles. Lung lavage was collected after exposures, and the levels of arachidonic acid metabolites were determined using radioimmunoassay (RIA). Concentration-dependent promotion of PGF2 alpha and concentration-dependent suppression of LtB4 were observed. The increased PGF2 alpha was associated with depressed vital capacity and diffusing capacity of the lungs measured in guinea pigs exposed to the same atmosphere described in a previous study

  6. Biosorption and biodegradation of a sulfur dye in high-strength dyeing wastewater by Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Nguyen, Thai Anh; Fu, Chun-Chieh; Juang, Ruey-Shin

    2016-11-01

    The ability of the bacterial strain Acidithiobacillus thiooxidans to remove sulfur blue 15 (SB15) dye from water samples was examined. This bacterium could not only oxidize sulfur compounds to sulfuric acid but also promote the attachment of the cells to the surface of sulfidic particles, therefore serving as an efficient biosorbent. The biosorption isotherms were better described by the Langmuir equation than by the Freundlich or Dubinin-Radushkevich equation. Also, the biosorption process followed the pseudo-second-order kinetics. At pH 8.3 and SB15 concentrations up to 2000 mg L(-1) in the biomass/mineral salt solution, the dye removal and decolorization were 87.5% and 91.4%, respectively, following the biosorption process. Biodegradation was proposed as a subsequent process for the remaining dye (250-350 mg L(-1)). A central composite design was used to analyze independent variables in the response surface methodology study. Under the optimal conditions (i.e., initial dye concentration of 300 mg L(-1), initial biomass concentration of 1.0 g L(-1), initial pH of 11.7, and yeast extract dose of 60 mg L(-1)), up to 50% of SB15 was removed after 4 days of biodegradation.

  7. Evaluation of physicochemical properties, and antimicrobial efficacy of monoclinic sulfur-nanocolloid

    Energy Technology Data Exchange (ETDEWEB)

    Roy Choudhury, Samrat, E-mail: samratroychoudhury@gmail.com [Indian Statistical Institute, Biological Sciences Division (India); Mandal, Amrita; Chakravorty, Dipankar [Indian Association for the Cultivation of Science (India); Gopal, Madhuban [Indian Agricultural Research Institute, Divisions of Agricultural Chemicals (India); Goswami, Arunava [Indian Statistical Institute, Biological Sciences Division (India)

    2013-04-15

    Stable nanocolloids of monoclinic sulfur ({beta}-SNPs) were prepared through 'water-in-oil microemulsion technique' at room temperature after suitable modifications of the surface. The morphology (rod shaped; {approx}50 nm in diameter) and allotropic nature (monoclinic) of the SNPs were investigated with Transmission Electron Microscopy and X-ray Diffraction technique. The surface modification, colloidal stability, and surface topology of {beta}-SNPs were evaluated with Fourier Transform Infrared Spectroscopy, zeta potential analysis, and Atomic Force Microscopy. Thermal decomposition pattern of these nanosized particles was determined by Thermo Gravimetric Analysis (TGA). {beta}-SNPs-colloids expressed excellent antimicrobial activities against a series of fungal and bacterial isolates with prominent deformities at their surface. In contrast, insignificant cytotoxicity was achieved against the human derived hepatoma (HepG2) cell line upon treatment with {beta}-SNPs. A simultaneous study was performed to determine the stock concentration of {beta}-SNP-colloids using a novel high phase liquid chromatographic method. Cumulative results of this study hence, elucidate the stabilization of nanosized monoclinic sulfur at room temperature and their potential antimicrobial efficacy over micron-sized sulfur.

  8. Sulfur use efficiency ofradish as affected by sulfur source and rate in typic ustifluvent soil

    Directory of Open Access Journals (Sweden)

    M.V. Sriramachandrasekharan

    2012-10-01

    Full Text Available Radish is one of the most popular root crops inthe tropical and temperate regions. Sulfurdeficiency is common in coarse textured soildue to leachingloss. Rootyieldof radishis reportedtoincreasewith sulfur application.Fieldexperiments was conducted in two seasons to study theeffect of sulfur(S rate and sourceon radish (Raphanus sativus L. nutrition, an experimentwas conducted in aPadugai sandy clay loam(TypicUstifluvents deficient in available sulfur. The treatmentsconsisted of four levels of S viz., 0, 25, 50and 100kg ha-1applied through four sources viz., ammonium sulfate,super phosphate, gypsum andpotassiumsulfateDatawererecordedonradishrootyield, Suptake, available S,Suptake efficiency (SUPE,S utilization efficiency (SUTE,S use efficiency (SUE,fertilizer Suptake efficiency (FSUPE,fertilizer Sutilization efficiency (FSUTE and fertilizer Suse efficiency (FSUE. The results revealed that addition of graded rate of S significantlyincreasedroot yield, S uptakeand available Sover the control. Application ofS at 100kg ha-1gave highest root yield of 33.5t ha-1 (season-I and 36.8t ha -1 (season-II and also sulfur uptake and available sulfur. AmongtheSsources, gypsumwas better thanthe other sources. IncreasedS-application increased SUPE and SUE. The SUTE was highest in control plants and decreasedwith Slevel.OntheotherhandFSUPEandFSUEwerehighest ata rateof50kgSha-1and FSUTE was highest at 25 kgS ha-1. Among S sources, gypsum had higherS use efficiency and its components compared to theother Ssources.

  9. Effects of Sulfurization Temperature on Properties of CZTS Films by Vacuum Evaporation and Sulfurization Method

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2013-01-01

    Full Text Available Copper zinc tin sulfur (CZTS thin films have been extensively studied in recent years for their advantages of low cost, high absorption coefficient (≥104 cm−1, appropriate band gap (~1.5 eV, and nontoxicity. CZTS thin films are promising materials of solar cells like copper indium gallium selenide (CIGS. In this work, CZTS thin films were prepared on glass substrates by vacuum evaporation and sulfurization method. Sn/Cu/ZnS (CZT precursors were deposited by thermal evaporation and then sulfurized in N2 + H2S atmosphere at temperatures of 360–560°C to produce polycrystalline CZTS thin films. It is found that there are some impurity phases in the thin films with the sulfurization temperature less than 500°C, and the crystallite size of CZTS is quite small. With the further increase of the sulfurization temperature, the obtained thin films exhibit preferred (112 orientation with larger crystallite size and higher density. When the sulfurization temperature is 500°C, the band gap energy, resistivity, carrier concentration, and mobility of the CZTS thin films are 1.49 eV, 9.37 Ω · cm, 1.714×1017 cm−3, and 3.89 cm2/(V · s, respectively. Therefore, the prepared CZTS thin films are suitable for absorbers of solar cells.

  10. Preparation and electrochemical performance of sulfur-alumina cathode material for lithium-sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Kang [Faculty of Material Science and Chemistry, China University of Geosciences, 388 Lumo Road, 430074 Wuhan (China); Wang, Shengping, E-mail: spwang@cug.edu.cn [Faculty of Material Science and Chemistry, China University of Geosciences, 388 Lumo Road, 430074 Wuhan (China); Zhang, Hanyu; Wu, Jinping [Faculty of Material Science and Chemistry, China University of Geosciences, 388 Lumo Road, 430074 Wuhan (China)

    2013-06-01

    Highlights: ► Micron-sized alumina was synthesized as adsorbent for lithium-sulfur batteries. ► Sulfur-alumina material was synthesized via crystallizing nucleation. ► The Al{sub 2}O{sub 3} can provide surface area for the deposition of Li{sub 2}S and Li{sub 2}S{sub 2}. ► The discharge capacity of the battery is improved during the first several cycles. - Abstract: Nano-sized sulfur particles exhibiting good adhesion with conducting acetylene black and alumina composite materials were synthesized by means of an evaporated solvent and a concentrated crystallization method for use as the cathodes of lithium-sulfur batteries. The composites were characterized and examined by X-ray diffraction, environmental scanning electron microscopy and electrochemical methods, such as cyclic voltammetry, electrical impedance spectroscopy and charge–discharge tests. Micron-sized flaky alumina was employed as an adsorbent for the cathode material. The initial discharge capacity of the cathode with the added alumina was 1171 mAh g{sup −1}, and the remaining capacity was 585 mAh g{sup −1} after 50 cycles at 0.25 mA cm{sup −2}. Compared with bare sulfur electrodes, the electrodes containing alumina showed an obviously superior cycle performance, confirming that alumina can contribute to reducing the dissolution of polysulfides into electrolytes during the sulfur charge–discharge process.

  11. A new study of an old sink of sulfur in hot molecular cores: the sulfur residue

    CERN Document Server

    Woods, Paul M; Viti, Serena; Kanuchova, Z; Palumbo, Maria Elisabetta; Price, Stephen D

    2015-01-01

    Sulfur appears to be depleted by an order of magnitude or more from its elemental abundance in star-forming regions. In the last few years, numerous observations and experiments have been performed in order to to understand the reasons behind this depletion without providing a satisfactory explanation of the sulfur chemistry towards high-mass star-forming cores. Several sulfur-bearing molecules have been observed in these regions, and yet none are abundant enough to make up the gas-phase deficit. Where, then, does this hidden sulfur reside? This paper represents a step forward in our understanding of the interactions among the various S-bearing species. We have incorporated recent experimental and theoretical data into a chemical model of a hot molecular core in order to see whether they give any indication of the identity of the sulfur sink in these dense regions. Despite our model producing reasonable agreement with both solid-phase and gas-phase abundances of many sulfur-bearing species, we find that the s...

  12. Porous spherical polyacrylonitrile-carbon nanocomposite with high loading of sulfur for lithium-sulfur batteries

    Science.gov (United States)

    Sohn, Hiesang; Gordin, Mikhail L.; Regula, Michael; Kim, Dong Hyeon; Jung, Yoon Seok; Song, Jiangxuan; Wang, Donghai

    2016-01-01

    Pyrolyzed porous spherical composites of polyacrylonitrile-Ketjenblack carbon and sulfur (pPAN-KB/S) with a high sulfur content (ca. 72%) and enhanced conductivity and porosity (pore volume: 1.42 cm3/g; BET surface area: 727 m2/g) were prepared by an aerosol-assisted process and applied as cathode for lithium-sulfur batteries. Electrochemical tests showed that the pPAN-KB/S composite exhibited a high capacity of 866 mAh/g (based on sulfur) after 100 cycles at 0.5C (1C = 1.68 A/g) and a good rate performance at high current density (431 mAh/g at 5C). In addition, a pPAN-KB/S composite electrode with high sulfur loading (ca. 4.4 mg-S/cm2) exhibited impressive electrochemical performance with a reversible capacity of 513 mAh/g and 576 mAh/cm3 (based on sulfur) and a coulombic efficiency >99% after 100 cycles at 0.5C.

  13. Oxygen and sulfur isotope fractionation during sulfide oxidation by anoxygenic phototrophic bacteria

    Science.gov (United States)

    Brabec, Michelle Y.; Lyons, Timothy W.; Mandernack, Kevin W.

    2012-04-01

    Sulfide-mediated anoxygenic photosynthesis (SMAP) carried out by anaerobic phototrophic bacteria may have played an important role in sulfur cycling, formation of sulfate, and, perhaps, primary production in the Earth’s early oceans. Determination of ε34SSO4-Sulfide- and ε18OSO4-H2O values for bacterial sulfide oxidation will permit more refined interpretation of the δ34S and δ18OSO4 values measured in modern anoxic environments, such as meromictic lakes where sulfide commonly extends into the photic zone, and in the ancient rock record, particularly during periods of the Precambrian when anoxic and sulfidic (euxinic) conditions were believed to be more pervasive than today. Laboratory experiments with anaerobic purple and green sulfur phototrophs, Allochromatium vinosum and Chlorobaculum tepidum, respectively, were conducted to determine the sulfur and oxygen isotope fractionation during the oxidation of sulfide to sulfate. Replicate experiments were conducted at 25 °C for A. vinosum and 45 °C for C. tepidum, and in duplicate at three different starting oxygen isotope values for water to determine sulfate-water oxygen isotope fractionations accurately (ε18OSO4-H2O). ε18OSO4-H2O values of 5.6 ± 0.2‰ and 5.4 ± 0.1‰ were obtained for A. vinosum and C. tepidum, respectively. Temperature had no apparent effect on the ε18OSO4-H2O values. By combining all data from both cultures, an average ε18OSO4-H2O value of 5.6 ± 0.3‰ was obtained for SMAP. This value falls between those previously reported for bacterial oxidation of sphalerite and elemental sulfur (7-9‰) and abiotic and biotic oxidation of pyrite and chalcopyrite (2-4‰). Sulfur isotope fractionation between sulfide and sulfate formed by A.vinosum was negligible (0.1 ± 0.2‰) during all experiments. For C. tepidum an apparent fractionation of -2.3 ± 0.5‰ was observed during the earlier stages of oxidation based on bulk δ34S measurements of sulfate and sulfide and became smaller (-0.7

  14. Imaging of non-small cell lung cancers with a monoclonal antibody, KC-4G3, which recognizes a human milk fat globule antigen

    Energy Technology Data Exchange (ETDEWEB)

    Dienhart, D.G.; Schmelter, R.F.; Lear, J.L.; Miller, G.J.; Glenn, S.D.; Bloedow, D.C.; Kasliwal, R.; Moran, P.; Seligman, P.; Murphy, J.R. (Univ. of Colorado Cancer Center, Denver (USA))

    1990-11-01

    To determine the role of lung cancer tumor imaging with monoclonal antibodies directed against high molecular weight human milk fat globule antigens, we administered i.v. 111In-KC-4G3 to 24 patients with advanced non-small cell lung cancer. One mg of 111In-KC-4G3 was mixed with 0, 9, 49, 99, or 499 mg of unlabeled KC-4G3 and infused i.v. over 1 to 5 h. The mean 111In-KC-4G3 radiochemical purity was greater than 97% and the resultant immunoreactivity averaged 62%. Successful imaging of cancer sites was accomplished in 92% of 24 patients, and 57% of 91 total lesions were visualized. Successful localization of tumor sites related to size (P less than 0.001), with 81% of lesions greater than 3.0 cm in diameter, 50% of lesions 1.5 to 3 cm, and 6% of lesions less than 1.5 cm successfully imaging, and to location (P less than 0.05), with 69% of pulmonary lesions, 80% of soft tissue lesions, and only 32% of bone metastases being visualized. Nonspecific reticulo-endothelial uptake of radioactivity was a major problem. Approximately 35% of 111In was chelated to serum transferrin by 24 and 48 h after infusion. The mean t 1/2 beta for plasma radioisotope and immunoreactive KC-4G3 was 29 and 27 h, respectively. There was no correlation between total infused antibody dose and imaging success or between total dose and effect on 111In and KC-4G3 kinetics. Circulating free KC-4 antigen was measurable in all but one patient before study. Tumor biopsy following infusion could demonstrate antibody presence but not saturable antigen binding. We conclude that (a) 111In-KC-4G3 demonstrates successful tumor localization in non-small cell lung cancers bearing generally high expression of its antigen and (b) further investigations to diminish nonspecific radioactivity for imaging and utilization of high dose radiolabeled antibody for therapeutic intent are warranted.

  15. Heme uptake in bacterial pathogens

    OpenAIRE

    Contreras, Heidi; Chim, Nicholas; Credali, Alfredo; Goulding, Celia W.

    2014-01-01

    Iron is an essential nutrient for the survival of organisms. Bacterial pathogens possess specialized pathways to acquire heme from their human hosts. In this review, we present recent structural and biochemical data that provide mechanistic insights into several bacterial heme uptake pathways, encompassing the sequestration of heme from human hemoproteins to secreted or membrane-associated bacterial proteins, the transport of heme across bacterial membranes, and the degradation of heme within...

  16. Potential for biogeochemical cycling of sulfur, iron and carbon within massive sulfide deposits below the seafloor.

    Science.gov (United States)

    Kato, Shingo; Ikehata, Kei; Shibuya, Takazo; Urabe, Tetsuro; Ohkuma, Moriya; Yamagishi, Akihiko

    2015-05-01

    Seafloor massive sulfides are a potential energy source for the support of chemosynthetic ecosystems in dark, deep-sea environments; however, little is known about microbial communities in these ecosystems, especially below the seafloor. In the present study, we performed culture-independent molecular analyses of sub-seafloor sulfide samples collected in the Southern Mariana Trough by drilling. The depth for the samples ranged from 0.52 m to 2.67 m below the seafloor. A combination of 16S rRNA and functional gene analyses suggested the presence of chemoautotrophs, sulfur-oxidizers, sulfate-reducers, iron-oxidizers and iron-reducers. In addition, mineralogical and thermodynamic analyses are consistent with chemosynthetic microbial communities sustained by sulfide minerals below the seafloor. Although distinct bacterial community compositions were found among the sub-seafloor sulfide samples and hydrothermally inactive sulfide chimneys on the seafloor collected from various areas, we also found common bacterial members at species level including the sulfur-oxidizers and sulfate-reducers, suggesting that the common members are widely distributed within massive sulfide deposits on and below the seafloor and play a key role in the ecosystem function.

  17. Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions

    Science.gov (United States)

    Hosono, Takahiro; Alvarez, Kelly; Lin, In-Tian; Shimada, Jun

    2015-12-01

    In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ15NNO3), carbon in dissolved inorganic carbon (δ13CDIC), and sulfur in sulfate (δ34SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ13CDIC (from - 7.7‰ to - 12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was - 4.7‰), suggesting the contribution of C of trisodium citrate (δ13C = - 12.4‰). No SO42 - and δ34SSO4 changes were observed. In the AD experiment, clear fractionation of δ13CDIC during DIC consumption (εC = - 7.8‰) and δ34SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN = - 12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.

  18. The Fate of Sulfur in Late-Stage Magmatic Processes: Insights From Quadruple Sulfur Isotopes

    Science.gov (United States)

    Keller, N. S.; Ono, S.; Shaw, A. M.

    2009-05-01

    Multiple sulfur isotopes (32S, 33S, 34S and 36S) have recently been shown to be useful tracers of fluid-rock interaction in seafloor hydrothermal systems [1]. Here we present the application of multiple sulfur isotopes to subaerial volcanoes with the aim of unraveling the various processes fractionating sulfur in the upper volcanic system. We take advantage of the fact that the ascent of volcanic gases through a hydrothermal system causes complex isotopic fractionation between the quaduple sulfur isotopes. δ34S is thought to trace the source of sulfur as well as magma degassing; at equilibrium, δ33S follows a mass-dependent fractionation relationship such that two phases in equilibrium with each other have equal Δ33S values (Δ33S ≡ ln(δ33S+1) - 0.515×ln(δ34S+1)). Disequilibrium Δ33S values can indicate isotope mixing and other fluid-rock interactions. The ultimate aim of this study is to assess the use of quadruple sulfur isotopes to obtain quantitative information on the sulfur cycle at convergent plate margins. The sulfur mass balance at convergent margins is poorly constrained, partly because late-stage processes are challenging to quantify and lead to large uncertainties in the global output fluxes. Quadruple sulfur isotopes provide a powerful tool to untangle the convoluted history of volcanic systems. Here we report the first quadruple sulfur isotopic values for H2S, SO2 and native sulfur from arc volcanoes. Fumarolic gases (˜100°C) and sulfur sublimates were collected from Poas and Turrialba, two actively degassing volcanoes in Costa Rica. The gases were bubbled in situ through chemical traps to separate H2S from SO2: H2S was reacted to form ZnS, and SO2 to form BaSO4. Sulfur was chemically extracted from the solid phases and precipitated as Ag2S, which was fluorinated to SF6 and analysed by IRMS. Poas and Turrialba have H2S/SO2 ˜1 and 0.01, respectively. δ34SH2S and δ34SSO2 are similar to gases measured at other arcs [2], - 7.9‰ and 0.6

  19. Sulfur dimers adsorbed on Au(111) as building blocks for sulfur octomers formation: A density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Tamargo, Carlos E.; Montero-Alejo, Ana Lilian [Laboratory of Computational and Theoretical Chemistry (LQCT), Faculty of Chemistry, Havana University, Havana 10400 (Cuba); Pujals, Daniel Codorniu [Higher Institute of Technologies and Applied Sciences (InSTEC), Havana 10400 (Cuba); Mikosch, Hans [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/E164-EC, 1060 Vienna (Austria); Hernández, Mayra P., E-mail: mayrap@imre.oc.uh.cu [Instituto de Ciencias y Tecnologías de Materiales (IMRE), Havana 10400 (Cuba)

    2014-07-28

    Experimental scanning tunneling microscopy (STM) studies have shown for more than two decades rectangular formations when sulfur atoms are deposited on Au(111) surfaces. The precursors have ranged from simple molecules or ions, such as SO{sub 2} gas or sulfide anions, to more complex organosulfur compounds. We investigated, within the framework of the Density Functional Theory, the structure of these rectangular patterns assuming them entirely composed of sulfur atoms as the experimental evidence suggests. The sulfur coverage at which the simulations were carried out (0.67 ML or higher) provoked that the sulfur-sulfur association had to be taken into account for achieving a good agreement between the sets of simulated and experimental STM images. A combination of four sulfur dimers per rectangular formation properly explained the trends obtained by the experimental STM analysis which were related with the rectangles' size and shape fluctuations together with sulfur-sulfur distances within these rectangles. Finally, a projected density of states analysis showed that the dimers were capable of altering the Au(5d) electronic states at the same level as atomic sulfur adsorbed at low coverage. Besides, sulfur dimers states were perfectly distinguished, whose presence near and above the Fermi level can explain both: sulfur-sulfur bond elongation and dimers stability when they stayed adsorbed on the surface at high coverage.

  20. Transient Studies of a Sodium Sulfur Cell

    Science.gov (United States)

    Caprio, Sarah

    Modern grids will include input from fossil-fueled power generation facilities as well as renewable energy sources, and these are expected to work together actively. One major problem with this integrated power production is that most renewable energy sources are intermittent and variable, and thus introduce a very challenging situation with regard to grid stability and reliability. Also, fossil-fueled power generation facilities have load cycles based on expected usage. A non-reliable power source cannot feasibly be used to supply the grid with proper amounts of energy needed in peak times. A solution to this dilemma is power storage. The sodium-sulfur battery has high potential for electrical storage at the grid level due to its high energy density, low cost of the reactants, and high open-circuit voltage. However, the use of sodium-sulfur batteries at the grid level requires high current density operation that can cause cell deterioration, leading to lower sulfur utilization and lower energy efficiency. In addition, it can result in undesired thermal runaway leading to potentially hazardous situations. A rigorous, dynamic model of a sodium-sulfur battery can be used to study these phenomena, design the battery for optimal transient performance, and develop mitigation strategies. Most literature on sodium-sulfur batteries is concerned the dynamics of the sulfur electrode (a sodium-polysulfide melt). There is limited data in the open literature for dynamics of an entire cell. With this motivation, a first-principles dynamic model of a sodium-sulfur cell (with beta"-alumina electrolyte) has been developed. The state of discharge (SOD) of a sodium-sulfur cell significantly affects the heat generation rate, rates of electrochemical reactions, and internal resistance. To capture these phenomena correctly, a fully coupled thermal-electrochemical model has been developed. The thermal model considers heat generation due to Ohmic loss, Peltier heat, and heat due to the

  1. Dimethylsulfoniopropionate in corals and its interrelations with bacterial assemblages in coral surface mucus

    OpenAIRE

    Frade, P.R.; Schwaninger, V.; Glasl, B.; Sintes, E.; Hill, R. W.; Simó, R.; Herndl, G.

    2016-01-01

    Corals produce copious amounts of dimethylsulfoniopropionate (DMSP), a sulfur compound thought toplay a role in structuring coral-associated bacterial communities. We tested the hypothesis that a linkage exists betweenDMSP availability in coral tissues and the community dynamics of bacteria in coral surface mucus. We determinedDMSP concentrations in three coral species (Meandrina meandrites, Porites astreoides and Siderastrea siderea) at twosampling depths (5 and 25 m) and times of day (dawn ...

  2. The significance of glucosinolates for sulfur storage in Brassicaceae seedlings

    OpenAIRE

    Luit J. eDe Kok

    2014-01-01

    Brassica juncea seedlings contained a two-fold higher glucosinolate content than Brassica rapa and these secondary sulfur compounds accounted for up to 30 % of the organic sulfur fraction. The glucosinolate content was not affected by H2S and SO2 exposure, demonstrating that these sulfur compounds did not form a sink for excessive atmospheric supplied sulfur. Upon sulfate deprivation, the foliarly absorbed H2S and SO2 replaced sulfate as the sulfur source for growth of B. juncea and B. rapa s...

  3. Method to prevent sulfur accumulation in membrane electrode assembly

    Science.gov (United States)

    Steimke, John L; Steeper, Timothy J; Herman, David T

    2014-04-29

    A method of operating a hybrid sulfur electrolyzer to generate hydrogen is provided that includes the steps of providing an anolyte with a concentration of sulfur dioxide, and applying a current. During steady state generation of hydrogen a plot of applied current density versus concentration of sulfur dioxide is below a boundary line. The boundary line may be linear and extend through the origin of the graph with a slope of 0.001 in which the current density is measured in mA/cm2 and the concentration of sulfur dioxide is measured in moles of sulfur dioxide per liter of anolyte.

  4. Experiments on contrail formation from fuels with different sulfur content

    Energy Technology Data Exchange (ETDEWEB)

    Busen, R.; Kuhn, M.; Petzold, A.; Schroeder, F.; Schumann, U. [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany); Baumgardner, D. [National Center for Atmospheric Research, Boulder, CO (United States); Borrmann, S. [Mainz Univ. (Germany); Hagen, D.; Whitefield, Ph. [Missouri Univ., Rolla, MO (United States). Bureau of Mines; Stroem, J. [Stockholm Univ. (Sweden)

    1997-12-31

    A series of both flight tests and ground experiments has been performed to evaluate the role of the sulfur contained in kerosene in condensation trail (contrail) formation processes. The results of the first experiments are compiled briefly. The last SULFUR 4 experiment dealing with the influence of the fuel sulfur content and different appertaining conditions is described in detail. Different sulfur mass fractions lead to different particle size spectra. The number of ice particles in the contrail increases by about a factor of 2 for 3000 ppm instead of 6 ppm sulfur fuel content. (author) 10 refs.

  5. Bacterial chemoreceptors and chemoeffectors.

    Science.gov (United States)

    Bi, Shuangyu; Lai, Luhua

    2015-02-01

    Bacteria use chemotaxis signaling pathways to sense environmental changes. Escherichia coli chemotaxis system represents an ideal model that illustrates fundamental principles of biological signaling processes. Chemoreceptors are crucial signaling proteins that mediate taxis toward a wide range of chemoeffectors. Recently, in deep study of the biochemical and structural features of chemoreceptors, the organization of higher-order clusters in native cells, and the signal transduction mechanisms related to the on-off signal output provides us with general insights to understand how chemotaxis performs high sensitivity, precise adaptation, signal amplification, and wide dynamic range. Along with the increasing knowledge, bacterial chemoreceptors can be engineered to sense novel chemoeffectors, which has extensive applications in therapeutics and industry. Here we mainly review recent advances in the E. coli chemotaxis system involving structure and organization of chemoreceptors, discovery, design, and characterization of chemoeffectors, and signal recognition and transduction mechanisms. Possible strategies for changing the specificity of bacterial chemoreceptors to sense novel chemoeffectors are also discussed.

  6. Bacterial Colony Optimization

    Directory of Open Access Journals (Sweden)

    Ben Niu

    2012-01-01

    Full Text Available This paper investigates the behaviors at different developmental stages in Escherichia coli (E. coli lifecycle and developing a new biologically inspired optimization algorithm named bacterial colony optimization (BCO. BCO is based on a lifecycle model that simulates some typical behaviors of E. coli bacteria during their whole lifecycle, including chemotaxis, communication, elimination, reproduction, and migration. A newly created chemotaxis strategy combined with communication mechanism is developed to simplify the bacterial optimization, which is spread over the whole optimization process. However, the other behaviors such as elimination, reproduction, and migration are implemented only when the given conditions are satisfied. Two types of interactive communication schemas: individuals exchange schema and group exchange schema are designed to improve the optimization efficiency. In the simulation studies, a set of 12 benchmark functions belonging to three classes (unimodal, multimodal, and rotated problems are performed, and the performances of the proposed algorithms are compared with five recent evolutionary algorithms to demonstrate the superiority of BCO.

  7. [Bacterial diseases of rape].

    Science.gov (United States)

    Zakharova, O M; Mel'nychuk, M D; Dankevych, L A; Patyka, V P

    2012-01-01

    Bacterial destruction of the culture was described and its agents identified in the spring and winter rape crops. Typical symptoms are the following: browning of stem tissue and its mucilagization, chlorosis of leaves, yellowing and beginning of soft rot in the place of leaf stalks affixion to stems, loss of pigmentation (violet). Pathogenic properties of the collection strains and morphological, cultural, physiological, and biochemical properties of the agents of rape's bacterial diseases isolated by the authors have been investigated. It was found that all the isolates selected by the authors are highly or moderately aggressive towards different varieties of rape. According to the complex of phenotypic properties 44% of the total number of isolates selected by the authors are related to representatives of the genus Pseudomonas, 37% - to Xanthomonas and 19% - to Pectobacterium. PMID:23293826

  8. A lithium-sulfur cathode with high sulfur loading and high capacity per area: a binder-free carbon fiber cloth-sulfur material.

    Science.gov (United States)

    Miao, Lixiao; Wang, Weikun; Yuan, Keguo; Yang, Yusheng; Wang, Anbang

    2014-11-11

    A sulfur cathode with high capacity per area (>7 mA h cm(-2)) and high sulfur loading (6.7 mg cm(-2)) was fabricated by synthesizing a carbon fiber cloth-sulfur composite via a simple method. It is worth noting that an ingenious method is adopted which can improve the performance of Li-S batteries by forming in situ polysulfide ions.

  9. Analyzing Sulfur Dioxide Emissions of Nyamuragira Volcano

    Science.gov (United States)

    Guth, A. L.; Bluth, G. J.; Carn, S. A.

    2002-05-01

    Nyamuragira volcano, located in the Democratic Republic of Congo, is Africa's most active volcano, having erupted 13 times (every 1-3 years) since 1980. The eruption frequency, and the large amounts of sulfur dioxide emitted by this rift volcano, may produce a significant impact on the global sulfur budget. In this project we are attempting to quantify the sulfur dioxide emissions from this volcano over the past 20+ years using satellite data. Since 1978, satellites carrying NASA's Total Ozone Mapping Spectrometer (TOMS) instruments have been orbiting the earth collecting atmospheric data. These instruments use six wavelength bands located within the ultraviolet spectrum to measure solar irradiance and the energy reflected and backscattered by the Earth's surface and atmosphere. Sunlit planetary coverage is provided once per day by TOMS data. The spatial resolution of these satellites varies from 24 km (Earth Probe, 1996-1997, but raised to 39 km from 1997 to present) to 62 km (Meteor-3, 1991-1994). Nimbus-7, the satellite operating for the longest span of time (1978-1993), had a nadir footprint of 50 km. The (instantaneous) mass retrievals of sulfur dioxide cloud masses are derived using several different image processing schemes and net tonnages are calculated using a background correction. Volcanic activity associated with this volcano typically consists of long term (weeks to months), and often continuous, effusive emissions. Work to date has discovered over 120 days in which sulfur dioxide plumes were observed from the 13 eruptions (ranging from a minimum of one day to a maximum of 32 days). Most (82%) of the sulfur dioxide clouds measured are relatively low-level, below 100 kilotonnes (kt); 16% of the emissions are between 100 and 1000 kt, and 1.5% were measured to have more than 1000 kt. Current work is focusing on deriving net emission fluxes, integrating the TOMS instantaneous measurements of relatively continuous emission activity. The eruptive activity

  10. The fate of sulfur during rapid pyrolysis of scrap tires.

    Science.gov (United States)

    Hu, Hongyun; Fang, Yuan; Liu, Huan; Yu, Ren; Luo, Guangqian; Liu, Wenqiang; Li, Aijun; Yao, Hong

    2014-02-01

    The fate of sulfur during rapid pyrolysis of scrap tires at temperatures from 673 to 1073K was investigated. Sulfur was predominant in the forms of thiophenic and inorganic sulfides in raw scrap tires. In the pyrolysis process, sulfur in organic forms was unstable and decomposed, leading to the sulfur release into tar and gases. At 673 and 773K, a considerable amount of sulfur was distributed in tar. Temperature increasing from 773 to 973K promoted tar decomposition and facilitated sulfur release into gases. At 1073K, the interactions between volatiles and char stimulated the formation of high-molecular-weight sulfur-containing compounds. After pyrolysis, almost half of the total content of sulfur in raw scrap tires still remained in the char and was mostly in the form of sulfides. Moreover, at temperatures higher than 873K, part of sulfur in the char was immobilized in the sulfates. In the pyrolysis gases, H2S was the main sulfur-containing gas. Increasing temperature stimulated the decomposition of organic polymers in scrap tires and more H2S was formed. Besides H2S, other sulfur-containing gases such as CH3SH, COS and SO2 were produced during the rapid pyrolysis of scrap tires.

  11. The fate of sulfur during rapid pyrolysis of scrap tires.

    Science.gov (United States)

    Hu, Hongyun; Fang, Yuan; Liu, Huan; Yu, Ren; Luo, Guangqian; Liu, Wenqiang; Li, Aijun; Yao, Hong

    2014-02-01

    The fate of sulfur during rapid pyrolysis of scrap tires at temperatures from 673 to 1073K was investigated. Sulfur was predominant in the forms of thiophenic and inorganic sulfides in raw scrap tires. In the pyrolysis process, sulfur in organic forms was unstable and decomposed, leading to the sulfur release into tar and gases. At 673 and 773K, a considerable amount of sulfur was distributed in tar. Temperature increasing from 773 to 973K promoted tar decomposition and facilitated sulfur release into gases. At 1073K, the interactions between volatiles and char stimulated the formation of high-molecular-weight sulfur-containing compounds. After pyrolysis, almost half of the total content of sulfur in raw scrap tires still remained in the char and was mostly in the form of sulfides. Moreover, at temperatures higher than 873K, part of sulfur in the char was immobilized in the sulfates. In the pyrolysis gases, H2S was the main sulfur-containing gas. Increasing temperature stimulated the decomposition of organic polymers in scrap tires and more H2S was formed. Besides H2S, other sulfur-containing gases such as CH3SH, COS and SO2 were produced during the rapid pyrolysis of scrap tires. PMID:24238304

  12. Bacterial transformation of terpenoids

    International Nuclear Information System (INIS)

    Data on the bacterial transformation of terpenoids published in the literature in the past decade are analyzed. Possible pathways for chemo-, regio- and stereoselective modifications of terpenoids are discussed. Considerable attention is given to new technological approaches to the synthesis of terpenoid derivatives suitable for the use in the perfume and food industry and promising as drugs and chiral intermediates for fine organic synthesis. The bibliography includes 246 references

  13. Supramolecular bacterial systems

    OpenAIRE

    Sankaran, Shrikrishnan

    2015-01-01

    For nearly over a decade, a wide variety of dynamic and responsive supramolecular architectures have been investigated and developed to address biological systems. Since the non-covalent interactions between individual molecular components in such architectures are similar to the interactions found in living systems, it was possible to integrate chemically-synthesized and naturally-occurring components to create platforms with interesting bioactive properties. Bacterial cells and recombinant ...

  14. Bacterial Colony Optimization

    OpenAIRE

    Ben Niu; Hong Wang

    2012-01-01

    This paper investigates the behaviors at different developmental stages in Escherichia coli (E. coli) lifecycle and developing a new biologically inspired optimization algorithm named bacterial colony optimization (BCO). BCO is based on a lifecycle model that simulates some typical behaviors of E. coli bacteria during their whole lifecycle, including chemotaxis, communication, elimination, reproduction, and migration. A newly created chemotaxis strategy combined with communication mechanism i...

  15. Study on Effect of Compounding Sulfurized Isobutylene with Thioester

    Institute of Scientific and Technical Information of China (English)

    Li Hongjun; Qiu Yansheng

    2002-01-01

    Oxygen is introduced into the sulfurized isobutylene by compounding the sulfurized isobutylene with thioester. This paper studies the synergistic effect of commingling the sulfurized isobutylene with thioester during testing in the four-ball machine and the high-speed Timken machine. Tests in the four-ball machine and the high-speed Timken machine have revealed an improvement in EP performance of sulfurized isobutylene in admixture with thioester. The interfacial tension test and electrochemical analysis of anodic polarization have discovered increase of adsorptive force of the additive package on metal surface following compounding sulfurized isobutylene with thioester. The XPS and AES analyses indicate to the formation of FeS, Fe203 and FeSO4 on the metal surface. The sulfurized film formed by the additive package on the metal surface is thicker than that formed by simple sulfurized isobutylene.

  16. Plant sulfur nutrition: From Sachs to Big Data.

    Science.gov (United States)

    Kopriva, Stanislav

    2015-01-01

    Together with water and carbon dioxide plants require 14 essential mineral nutrients to finish their life cycle. The research in plant nutrition can be traced back to Julius Sachs, who was the first to experimentally prove the essentiality of mineral nutrients for plants. Among those elements Sachs showed to be essential is sulfur. Plant sulfur nutrition has been not as extensively studied as the nutrition of nitrogen and phosphate, probably because sulfur was not limiting for agriculture. However, with the reduction of atmospheric sulfur dioxide emissions sulfur deficiency has become common. The research in sulfur nutrition has changed over the years from using yeast and algae as experimental material to adopting Arabidopsis as the plant model as well as from simple biochemical measurements of individual parameters to system biology. Here the evolution of sulfur research from the times of Sachs to the current Big Data is outlined. PMID:26305261

  17. Plant sulfur nutrition: From Sachs to Big Data

    Science.gov (United States)

    Kopriva, Stanislav

    2015-01-01

    Together with water and carbon dioxide plants require 14 essential mineral nutrients to finish their life cycle. The research in plant nutrition can be traced back to Julius Sachs, who was the first to experimentally prove the essentiality of mineral nutrients for plants. Among those elements Sachs showed to be essential is sulfur. Plant sulfur nutrition has been not as extensively studied as the nutrition of nitrogen and phosphate, probably because sulfur was not limiting for agriculture. However, with the reduction of atmospheric sulfur dioxide emissions sulfur deficiency has become common. The research in sulfur nutrition has changed over the years from using yeast and algae as experimental material to adopting Arabidopsis as the plant model as well as from simple biochemical measurements of individual parameters to system biology. Here the evolution of sulfur research from the times of Sachs to the current Big Data is outlined. PMID:26305261

  18. Sulfur systematics in model glass compositions from West Valley

    International Nuclear Information System (INIS)

    Sulfur is incorporated into model glass melts, representative of West Valley compositions for the vitrification of high level nuclear waste, as the sulfate ion under oxidizing conditions and as the sulfide ion under reducing conditions. A narrow range of oxygen fugacities, around 10-8.8 atm at 1150 degrees C, under which the two redox forms of sulfur coexist is also the minimum in the sulfur solubility. Under the redox conditions prescribed for waste processing, sulfur dissolves as the sulfate ion. The capacity to dissolve sulfur as sulfate is about 1 to 2.5 wt% sulfur; an immiscible sulfate layer floats on the glass melt if waste loading introduces sulfur contents greater than this under oxidizing conditions. If the waste/melt system is exposed to sufficiently reducing conditions, the first phase to separate from the melt is likely nickel sulfide. The presence of the immiscible sulfate or sulfide layer buffers the iron redox ratio of the resulting glass

  19. Microbial diversity in Los Azufres geothermal field (Michoacán, Mexico) and isolation of representative sulfate and sulfur reducers.

    Science.gov (United States)

    Brito, Elcia M S; Villegas-Negrete, Norberto; Sotelo-González, Irene A; Caretta, César A; Goñi-Urriza, Marisol; Gassie, Claire; Hakil, Florence; Colin, Yannick; Duran, Robert; Gutiérrez-Corona, Felix; Piñón-Castillo, Hilda A; Cuevas-Rodríguez, Germán; Malm, Olaf; Torres, João P M; Fahy, Anne; Reyna-López, Georgina E; Guyoneaud, Rémy

    2014-03-01

    Los Azufres spa consists of a hydrothermal spring system in the Mexican Volcanic Axis. Five samples (two microbial mats, two mud pools and one cenote water), characterized by high acidity (pH between 1 and 3) and temperatures varying from 27 to 87 °C, were investigated for their microbial diversity by Terminal-Restriction Fragment Length Polymorphism (T-RFLP) and 16S rRNA gene library analyses. These data are the first to describe microbial diversity from Los Azufres geothermal belt. The data obtained from both approaches suggested a low bacterial diversity in all five samples. Despite their proximity, the sampling points differed by their physico-chemical conditions (mainly temperature and matrix type) and thus exhibited different dominant bacterial populations: anoxygenic phototrophs related to the genus Rhodobacter in the biomats, colorless sulfur oxidizers Acidithiobacillus sp. in the warm mud and water samples, and Lyzobacter sp.-related populations in the hot mud sample (87 °C). Molecular data also allowed the detection of sulfate and sulfur reducers related to Thermodesulfobium and Desulfurella genera. Several strains affiliated to both genera were enriched or isolated from the mesophilic mud sample. A feature common to all samples was the dominance of bacteria involved in sulfur and iron biogeochemical cycles (Rhodobacter, Acidithiobacillus, Thiomonas, Desulfurella and Thermodesulfobium genera).

  20. Entrainment in solution of an oscillating NADH oxidase activity from the bovine milk fat globule membrane with a temperature-compensated period length suggestive of an ultradian time-keeping (clock) function

    Science.gov (United States)

    Morre, D. James; Lawler, Juliana; Wang, Sui; Keenan, Thomas W.; Morre, Dorothy M.

    2002-01-01

    Entrainment in solution of an oscillating activity with a temperature compensated period of 24 min is described for a NADH oxidase (NOX) activity of the bovine milk fat globule membrane, a derivative of the mammary epithelial cell plasma membrane. The period of 24 min remained unchanged at 17 degrees C, 27 degrees C and 37 degrees C whereas the amplitude approximately doubled with each 10 degree C rise in temperature (Q(10)congruent with 2). The periodicity was observed with both intact milk fat globule membranes and with detergent-solubilized membranes, demonstrating that the oscillations did not require an association with membranes. The periodicity was not the result of instrument variation or of chemical interactions among reactants in solution. Preparations with different periodicities entrained (autosynchronized) when mixed. Upon mixing, the preparations exhibited two oscillatory patterns but eventually a single pattern representing the mean of the farthest separated maxima of the two preparations analyzed separately emerged. The cell surface NOX protein is the first reported example of an entrainable biochemical entity with a temperature-compensated periodicity potentially capable of functioning as an ultradian or circadian clock driver.

  1. Three-dimensional porous carbon composites containing high sulfur nanoparticle content for high-performance lithium–sulfur batteries

    OpenAIRE

    Li, Guoxing; Sun, Jinhua; Hou, Wenpeng; Jiang, Shidong; Huang, Yong; Geng, Jianxin

    2016-01-01

    Sulfur is a promising cathode material for lithium–sulfur batteries because of its high theoretical capacity (1,675 mA h g−1); however, its low electrical conductivity and the instability of sulfur-based electrodes limit its practical application. Here we report a facile in situ method for preparing three-dimensional porous graphitic carbon composites containing sulfur nanoparticles (3D S@PGC). With this strategy, the sulfur content of the composites can be tuned to a high level (up to 90 wt%...

  2. Are we getting enough sulfur in our diet?

    Directory of Open Access Journals (Sweden)

    Han Bo

    2007-11-01

    Full Text Available Abstract Sulfur, after calcium and phosphorus, is the most abundant mineral element found in our body. It is available to us in our diets, derived almost exclusively from proteins, and yet only 2 of the 20 amino acids normally present in proteins contains sulfur. One of these amino acids, methionine, cannot be synthesized by our bodies and therefore has to be supplied by the diet. Cysteine, another sulfur containing amino acid, and a large number of key metabolic intermediates essential for life, are synthesized by us, but the process requires a steady supply of sulfur. Proteins contain between 3 and 6% of sulfur amino acids. A very small percentage of sulfur comes in the form of inorganic sulfates and other forms of organic sulfur present in foods such as garlic, onion, broccoli, etc. The minimal requirements (RDA for all the essential amino acids have always been estimated in terms of their ability to maintain a nitrogen balance. This method asses amino acid requirements for protein synthesis, only one of the pathways that methionine follows after ingestion. To adequately evaluate the RDA for methionine, one should perform, together with a nitrogen balance a sulfur balance, something never done, neither in humans nor animals. With this in mind we decided to evaluate the dietary intake of sulfur (as sulfur amino acids in a random population and perform sulfur balance studies in a limited number of human volunteers. Initially this was done to try and gain some information on the possible mode of action of a variety of sulfur containing compounds (chondroitin sulfate, glucosamine sulfate, and others, used as dietary supplements to treat diseases of the joints. Out of this study came information that suggested that a significant proportion of the population that included disproportionally the aged, may not be receiving sufficient sulfur and that these dietary supplements, were very likely exhibiting their pharmacological actions by supplying

  3. A Foldable Lithium-Sulfur Battery.

    Science.gov (United States)

    Li, Lu; Wu, Zi Ping; Sun, Hao; Chen, Deming; Gao, Jian; Suresh, Shravan; Chow, Philippe; Singh, Chandra Veer; Koratkar, Nikhil

    2015-11-24

    The next generation of deformable and shape-conformable electronics devices will need to be powered by batteries that are not only flexible but also foldable. Here we report a foldable lithium-sulfur (Li-S) rechargeable battery, with the highest areal capacity (∼3 mAh cm(-2)) reported to date among all types of foldable energy-storage devices. The key to this result lies in the use of fully foldable and superelastic carbon nanotube current-collector films and impregnation of the active materials (S and Li) into the current-collectors in a checkerboard pattern, enabling the battery to be folded along two mutually orthogonal directions. The carbon nanotube films also serve as the sulfur entrapment layer in the Li-S battery. The foldable battery showed computers, surgical tools, and implantable biomedical devices. PMID:26412399

  4. Sulfur isotope fractionation during bacterial sulfate reduction in organic-rich sediments

    DEFF Research Database (Denmark)

    Habicht, K S; Canfield, D E

    1997-01-01

    Isotope fractionation during sulfate reduction by natural populations of sulfate-reducing bacteria was investigated in the cyanobacterial microbial mats of Solar Lake, Sinai and the sediments of Logten Lagoon sulfuretum, Denmark. Fractionation was measured at different sediment depths, sulfate...

  5. Bacterial disproportionation of elemental sulfur coupled to chemical reduction of iron or manganese

    DEFF Research Database (Denmark)

    Thamdrup, Bo; Finster, Kai; Hansen, Jens Würgler;

    1993-01-01

    the formed sulfide and the added FeOOH led to the observed precipitation of iron sulfides. Sulfate and iron sulfides were also produced when FeOOH was replaced by FeCO(3). Further enrichment with manganese oxide, MnO(2), instead of FeOOH yielded stable cultures which formed sulfate during concomitant...... significantly in the presence of sulfide-scavenging agents such as iron and manganese compounds. The population density of bacteria capable of S disproportionation in the presence of FeOOH or MnO(2) was high, > 10 cm in coastal sediments. The metabolism offers an explanation for recent observations of anaerobic...... sulfide oxidation to sulfate in anoxic sediments....

  6. Distribution of Sulfur in Carbon/Sulfur Nanocomposites Analyzed by Small-Angle X-ray Scattering.

    Science.gov (United States)

    Petzold, Albrecht; Juhl, Anika; Scholz, Jonas; Ufer, Boris; Goerigk, Günter; Fröba, Michael; Ballauff, Matthias; Mascotto, Simone

    2016-03-22

    The analysis of sulfur distribution in porous carbon/sulfur nanocomposites using small-angle X-ray scattering (SAXS) is presented. Ordered porous CMK-8 carbon was used as the host matrix and gradually filled with sulfur (20-50 wt %) via melt impregnation. Owing to the almost complete match between the electron densities of carbon and sulfur, the porous nanocomposites present in essence a two-phase system and the filling of the host material can be precisely followed by this method. The absolute scattering intensities normalized per unit of mass were corrected accounting for the scattering contribution of the turbostratic microstructure of carbon and amorphous sulfur. The analysis using the Porod parameter and the chord-length distribution (CLD) approach determined the specific surface areas and filling mechanism of the nanocomposite materials, respectively. Thus, SAXS provides comprehensive characterization of the sulfur distribution in porous carbon and valuable information for a deeper understanding of cathode materials of lithium-sulfur batteries.

  7. Sulfur Mustard Toxicity Following Dermal Exposure

    OpenAIRE

    Paromov, Victor; Suntres, Zacharias; Smith, Milton; Stone, William L

    2007-01-01

    Objective: Sulfur mustard (bis-2-(chloroethyl) sulfide) is a chemical warfare agent (military code: HD) causing extensive skin injury. The mechanisms underlying HD-induced skin damage are not fully elucidated. This review will critically evaluate the evidence showing that oxidative stress is an important factor in HD skin toxicity. Oxidative stress results when the production of reactive oxygen (ROS) and/or reactive nitrogen oxide species (RNOS) exceeds the capacity of antioxidant defense mec...

  8. Sulfur hexafluoride - A powerful new atmospheric tracer

    OpenAIRE

    Maiss, Manfred; Steele, Paul; Francey, Roger; Fraser, Paul; Langenfelds, Ray; Trivett, Neil; Levin, Ingeborg

    1996-01-01

    Long-term observations of the atmospheric trace gas sulfur hexafluoride (SF6) at four background monitoring stations, Neumayer, Antarctica (1986-1994), Cape Grim, Tasmania (1978-1994), Izana, Canary Islands (1991-1994) and Alert, Canada (1993-1994) are presented. These data sets are supplemented by two meridional profiles collected over the Atlantic Ocean (1990 and 1993) and occasional observations at the regional site Fraserdale, Canada (1994). The analytical system and the method of SF6 cal...

  9. Differential utilization and transformation of sulfur allotropes, μ-S and α-S8, by moderate thermoacidophile Sulfobacillus thermosulfidooxidans.

    Science.gov (United States)

    Nie, Zhen-yuan; Liu, Hong-chang; Xia, Jin-lan; Zhu, Hong-rui; Ma, Chen-yan; Zheng, Lei; Zhao, Yi-dong; Qiu, Guan-zhou

    2014-10-01

    The utilization of amorphous μ-S and orthorhombic α-S8 by thermoacidophile Sulfobacillus thermosulfidooxidans was firstly investigated in terms of cell growth and sulfur oxidation behavior. The morphology and surface sulfur speciation transformation were evaluated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the strain grown on μ-S entered slower (about 1 day later) into the exponential phase, while grew faster in exponential phase and attained higher maximal cell density and lower pH than on α-S8. After bio-corrosion, both sulfur samples were evidently eroded, but only μ-S surface presented much porosity, while α-S8 maintained glabrous. μ-S began to be gradually converted into α-S8 from day 2 when the bacterial cells entered the exponential phase, with a final composition of 62.3% μ-S and 37.7% α-S8 on day 4 at the stationary phase. α-S8 was not found to transform into other species in the experiments with or without bacteria. These data indicated S. thermosulfidooxidans oxidized amorphous μ-S faster than orthorhombic α-S8, but the chain-like μ-S was transformed into cyclic α-S8 by S. thermosulfidooxidans.

  10. Multiple sulfur and carbon isotope composition of sediments from the Belingwe Greenstone Belt (Zimbabwe): A biogenic methane regulation on mass independent fractionation of sulfur during the Neoarchean?

    Science.gov (United States)

    Thomazo, Christophe; Nisbet, Euan G.; Grassineau, Nathalie V.; Peters, Marc; Strauss, Harald

    2013-11-01

    Formation), respectively. This differs from the Archean reference line (i.e. -0.9). The sulfur and carbon isotopic signatures recorded here likely reflect different environmental conditions and/or ecosystems within the sampled Cheshire and Manjeri formations paleofacies. The differences in carbon isotopes in different sedimentological facies are interpreted as recording different metabolic pathways, including photosynthesis, methanogenesis and methanotrophy. Low δ13Corg values in the Cheshire Formation black shales suggest a strong influence of methanotrophy (likely preceded by bacterial methanogenesis), while the large range of Manjeri Formation δ34S may record bacterial sulfate reduction. The C and multiple S isotopic variations recorded here may imply different patterns of C and S fractionation, perhaps dependent on variations in the biogenic egress of methane to the atmosphere.

  11. Biological effects data: Fluoride and sulfur dioxide

    Energy Technology Data Exchange (ETDEWEB)

    McMechan, K.J. (ed.); Holton, R.L.; Ulbricht, R.J.; Morgan , J.B.

    1975-04-01

    The Alumax Pacific Aluminum Corporation has proposed construction of an aluminum reduction facility near Youngs Bay at Warrenton, Oregon. This report comprises one part of the final report to Alumax on a research project entitled, Physical, Chemical and Biological Studies of Youngs Bay.'' It presents data pertaining to the potential biological effects of fluoride and sulfur dioxide, two potentially hazardous plant-stack emissions, on selected aquatic species of the area. Companion volumes provide a description of the physical characteristics the geochemistry, and the aquatic animals present in Youngs Bay and adjacent ecosystems. An introductory volume provides general information and maps of the area, and summarizes the conclusions of all four studies. The data from the two phases of the experimental program are included in this report: lethal studies on the effects of selected levels of fluoride and sulfur dioxide on the survival rate of eleven Youngs Bay faunal species from four phyla, and sublethal studies on the effects of fluoride and sulfur dioxide on the rate of primary production of phytoplankton. 44 refs., 18 figs., 38 tabs.

  12. Sulfur status in long distance runners

    Science.gov (United States)

    Kovacs, L.; Zamboni, C.; Lourenço, T.; Macedo, D.

    2015-07-01

    In sports medicine, sulfur plays an important role and its deficiency can cause muscle injury affecting the performance of the athletes. However, its evaluation is unusual in conventional clinical practice. In this study the sulfur levels were determined in Brazilian amateur athlete's blood using Neutron Activation Analyses (NAA) technique. Twenty six male amateur runners, age 18 to 36 years, participated of this study. The athletes had a balanced diet, without multivitamin/mineral supplements. The blood collection was performed at LABEX (Laboratoriode Bioquimica do Exercicio, UNICAMP-SP) and the samples were irradiated for 300 seconds in a pneumatic station in the nuclear reactor (IEA-R1, 3-4.5MW, pool type) at IPEN/CNEN-SP. The results were compared with the control group (subjects of same age but not involved with physical activities) and showed that the sulfur concentration was 44% higher in amateurs athletes than control group. These data can be considered for preparation of balanced diet, as well as contributing for proposing new protocols of clinical evaluation.

  13. Global sulfur emissions from 1850 to 2000.

    Science.gov (United States)

    Stern, David I

    2005-01-01

    The ASL database provides continuous time-series of sulfur emissions for most countries in the World from 1850 to 1990, but academic and official estimates for the 1990s either do not cover all years or countries. This paper develops continuous time series of sulfur emissions by country for the period 1850-2000 with a particular focus on developments in the 1990s. Global estimates for 1996-2000 are the first that are based on actual observed data. Raw estimates are obtained in two ways. For countries and years with existing published data I compile and integrate that data. Previously published data covers the majority of emissions and almost all countries have published emissions for at least 1995. For the remaining countries and for missing years for countries with some published data, I interpolate or extrapolate estimates using either an econometric emissions frontier model, an environmental Kuznets curve model, or a simple extrapolation, depending on the availability of data. Finally, I discuss the main movements in global and regional emissions in the 1990s and earlier decades and compare the results to other studies. Global emissions peaked in 1989 and declined rapidly thereafter. The locus of emissions shifted towards East and South Asia, but even this region peaked in 1996. My estimates for the 1990s show a much more rapid decline than other global studies, reflecting the view that technological progress in reducing sulfur based pollution has been rapid and is beginning to diffuse worldwide.

  14. Sulfur aerosol in the clouds of Venus

    Science.gov (United States)

    Krasnopolsky, Vladimir A.

    2016-08-01

    The photochemical model for the middle atmosphere of Venus (Krasnopolsky, V.A. [2012] Icarus, 218, 230-246) predicts sulfur aerosol as a product of the OCS photolysis at 55-60 km. The calculated mass loading is much smaller than that of the mode 1 particles in the upper cloud layer. The chemical kinetic model for the lower atmosphere (Krasnopolsky, V.A. [2013], Icarus, 225, 570-580) results in a constant mixing ratio of 20 ppm for OCS + XSX. This means the S8 mixing ratio of 2.5 ppm near the model upper boundary at 47 km. Using this abundance, the calculated profile of the sulfur aerosol has a bottom that coincides with the lower boundary of modes 2 and 3 and constitutes ∼10% of the total mass loading in the lower cloud layer. Sulfur aerosol cannot be the near UV absorber because its abundance is too low at the cloud tops and disagrees with the profile of the absorber observed by Venera 14.

  15. Sulfur biogeochemistry of oil sands composite tailings

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Lesley; Stephenson, Kate [Earth Sciences, McMaster University (Canada)], email: warrenl@mcmaster.ca; Penner, Tara [Syncrude Environmental Research (Canada)

    2011-07-01

    This paper discusses the sulfur biogeochemistry of oil sands composite tailings (CT). The Government of Alberta is accelerating reclamation activities on composite tailings. As a CT pilot reclamation operation, Syncrude is currently constructing the first freshwater fen. Minor unpredicted incidents with H2S gas released from the dewatering process associated with these reclamations have been reported. The objective of this study is to ascertain the connection between microbial activity and H2S generation within CT and to assess the sulfur biogeochemistry of untreated and treated (fen) CT over seasonal and annual timescales. The microbial geochemical interactions taking place are shown using a flow chart. CT is composed of gypsum, sand, clay and organics like naphthenic acids and bitumen. Sulfur and Fe cycling in mining systems and their microbial activities are presented. The chemistry and the processes involved within CT are also given along with the results. It can be said that the diverse Fe and S metabolizing microorganisms confirm the ecology involved in H2S dynamics.

  16. Minimal sulfur requirement for growth and sulfur-dependent metabolism of the hyperthermophilic archaeon Staphylothermus marinus

    Directory of Open Access Journals (Sweden)

    Xiaolei Hao

    2003-01-01

    Full Text Available Staphylothermus marinus is an anaerobic hyperthermophilic archaeon that uses peptides as carbon and energy sources. Elemental sulfur (S° is obligately required for its growth and is reduced to H2S. The metabolic functions and mechanisms of S° reduction were explored by examining S°-dependent growth and activities of key enzymes present in this organism. All three forms of S° tested—sublimed S°, colloidal S° and polysulfide—were used by S. marinus, and no other sulfur-containing compounds could replace S°. Elemental sulfur did not serve as physical support but appeared to function as an electron acceptor. The minimal S° concentration required for optimal growth was 0.05% (w/v. At this concentration, there appeared to be a metabolic transition from H2 production to S° reduction. Some enzymatic activities related to S°-dependent metabolism, including sulfur reductase, hydrogenase, glutamate dehydrogenase and electron transfer activities, were detected in cell-free extracts of S. marinus. These results indicate that S° plays an essential role in the heterotrophic metabolism of S. marinus. Reducing equivalents generated by the oxidation of amino acids from peptidolysis may be transferred to sulfur reductase and hydrogenase, which then catalyze the production of H2S and H2, respectively.

  17. Formation of CuxS Layers on Polypropylene Sulfurized by Molten Sulfur

    Directory of Open Access Journals (Sweden)

    Rasa ALABURDAITĖ

    2011-11-01

    Full Text Available The processes of formation of electrically conductive layers of copper sulfides CuxS by the sorption-diffusion method on polypropylene (PP using molten sulfur as sulfurizing agent was investigated. The amount of sorbed sulfur increased with the increase of the duration of treatment. Copper sulfide layers were formed on the surface of polypropylene after the treatment of sulfurized polymer with Cu(II/I salt solution. The amount of copper sulfide in layer increased with the increase of treatment duration in copper salt solution. XRD spectra of PP films treated for 3 min with molten sulfur and then with Cu(II/I salt solution for the different time showed that the copper sulfide phases, mostly digenite, Cu2-xS and a-chalcocite, Cu2S were formed in the layers. Electromotive force measurement results confirmed the composition of formed CuxS layers on PP. The phase composition of layers also changed after the annealing. The value of electrical resistance of copper sulfide layers on PP varied from 20 W/cm2 to 80 W/cm2 and after annealing at 80 °C - in the interval of 10 W/cm2 - 60 W/cm2.http://dx.doi.org/10.5755/j01.ms.17.4.776

  18. Biomimetic Ant-Nest Electrode Structures for High Sulfur Ratio Lithium-Sulfur Batteries.

    Science.gov (United States)

    Ai, Guo; Dai, Yiling; Mao, Wenfeng; Zhao, Hui; Fu, Yanbao; Song, Xiangyun; En, Yunfei; Battaglia, Vincent S; Srinivasan, Venkat; Liu, Gao

    2016-09-14

    The lithium-sulfur (Li-S) rechargeable battery has the benefit of high gravimetric energy density and low cost. Significant research currently focuses on increasing the sulfur loading and sulfur/inactive-materials ratio, to improve life and capacity. Inspired by nature's ant-nest structure, this research results in a novel Li-S electrode that is designed to meet both goals. With only three simple manufacturing-friendly steps, which include slurry ball-milling, doctor-blade-based laminate casting, and the use of the sacrificial method with water to dissolve away table salt, the ant-nest design has been successfully recreated in an Li-S electrode. The efficient capabilities of the ant-nest structure are adopted to facilitate fast ion transportation, sustain polysulfide dissolution, and assist efficient precipitation. High cycling stability in the Li-S batteries, for practical applications, has been achieved with up to 3 mg·cm(-2) sulfur loading. Li-S electrodes with up to a 85% sulfur ratio have also been achieved for the efficient design of this novel ant-nest structure. PMID:27501313

  19. Improved Cyclability of Liquid Electrolyte Lithium/Sulfur Batteries by Optimizing Electrolyte/Sulfur Ratio

    Directory of Open Access Journals (Sweden)

    Sheng S. Zhang

    2012-12-01

    Full Text Available A liquid electrolyte lithium/sulfur (Li/S cell is a liquid electrochemical system. In discharge, sulfur is first reduced to highly soluble Li2S8, which dissolves into the organic electrolyte and serves as the liquid cathode. In solution, lithium polysulfide (PS undergoes a series of complicated disproportionations, whose chemical equilibriums vary with the PS concentration and affect the cell’s performance. Since the PS concentration relates to a certain electrolyte/sulfur (E/S ratio, there is an optimized E/S ratio for the cyclability of each Li/S cell system. In this work, we study the optimized E/S ratio by measuring the cycling performance of Li/S cells, and propose an empirical method for determination of the optimized E/S ratio. By employing an electrolyte of 0.25 m LiSO3CF3-0.25 m LiNO3 dissolved in a 1:1 (wt:wt mixture of dimethyl ether (DME and 1,3-dioxolane (DOL in an optimized E/S ratio, we show that the Li/S cell with a cathode containing 72% sulfur and 2 mg cm−2 sulfur loading is able to retain a specific capacity of 780 mAh g−1 after 100 cycles at 0.5 mA cm−2 between 1.7 V and 2.8 V.

  20. Geochemistry of sulfur in the Florida Everglades; 1994 through 1999

    Science.gov (United States)

    Bates, Anne L.; Orem, W.H.; Harvey, J.W.; Spiker, E. C.

    2000-01-01

    In this report, we present data on the geochemistry of sulfur in sediments and in surface water, groundwater, and rainwater in the Everglades region in south Florida. The results presented here are part of a larger study intended to determine the roles played by the cycling of carbon, nitrogen, phosphorus, and sulfur in the ecology of the south Florida wetlands. The geochemistry of sulfur in the region is particularly important because of its link to the production of toxic methylmercury through processes mediated by sulfate reducing bacteria. Sediment cores were collected from the Everglades Agricultural Area (EAA), Water Conservation Areas (WCAs) 1A and 2A, from Lake Okeechobee, and from Taylor Slough in the southern Everglades. Water collection was more widespread and includes surface water from WCAs 1A, 2A, 3A, 2B, the EAA, Taylor Slough, Lake Okeechobee, and the Kissimmee River. Groundwater was collected from The Everglades Nutrient Removal Area (ENR) and from WCA 2A. Rainwater was collected at two month intervals over a period of one year from the ENR and from WCA 2A. Water was analyzed for sulfate concentration and sulfate sulfur stable isotopic ratio (34S/32S). Sediment cores were analyzed for total sulfur concentration and/or for concentrations of sulfur species (sulfate, organic sulfur, disulfides, and acid volatile sulfides (AVS)) and for their stable sulfur isotopic ratio. Results show a decrease in total sulfur content (1.57 to 0.61 percent dry weight) with depth in two sediment cores collected in WCA 2A, indicating that there has been an increase in total sulfur content in recent times. A sediment core from the center of Lake Okeechobee shows a decrease in total sulfur content with depth (0.28 to 0.08 percent dry weight). A core from the periphery of the lake (South Bay) likewise shows a decrease in total sulfur content with depth (1.00 to 0.69 percent dry weight), however, the overall sulfur content is greater than that near the center at all depths

  1. Nutrition Research Progress of Sulfur in Ruminant%硫在反刍动物中的营养研究进展

    Institute of Scientific and Technical Information of China (English)

    郑帅; 刘大森

    2011-01-01

    Sulfur is one of the mineral essential elements for the ruminant animal and also the essential element for bacterial protein synthesis. This paper reviewed the distribution and metabolism of sulfur in ruminant animals, the relationship between the sulfur and other nutrients and requirements in the production.%硫是反刍动物必需矿物元素之一,也是合成菌体蛋白的必需元素。文章就硫在反刍动物体内的分布、代谢、和其他营养成分的关系及在生产中的需要量等方面进行了综述。

  2. Sulfur-induced structural motifs on copper and gold surfaces

    Science.gov (United States)

    Walen, Holly

    The interaction of sulfur with copper and gold surfaces plays a fundamental role in important phenomena that include coarsening of surface nanostructures, and self-assembly of alkanethiols. Here, we identify and analyze unique sulfur-induced structural motifs observed on the low-index surfaces of these two metals. We seek out these structures in an effort to better understand the fundamental interactions between these metals and sulfur that lends to the stability and favorability of metal-sulfur complexes vs. chemisorbed atomic sulfur. We choose very specific conditions: very low temperature (5 K), and very low sulfur coverage (≤ 0.1 monolayer). In this region of temperature-coverage space, which has not been examined previously for these adsorbate-metal systems, the effects of individual interactions between metals and sulfur are most apparent and can be assessed extensively with the aid of theory and modeling. Furthermore, at this temperature diffusion is minimal and relatively-mobile species can be isolated, and at low coverage the structures observed are not consumed by an extended reconstruction. The primary experimental technique is scanning tunneling microscopy (STM). The experimental observations presented here---made under identical conditions---together with extensive DFT analyses, allow comparisons and insights into factors that favor the existence of metal-sulfur complexes, vs. chemisorbed atomic sulfur, on metal terraces. We believe this data will be instrumental in better understanding the complex phenomena occurring between the surfaces of coinage metals and sulfur.

  3. The analysis of thermoplastic characteristics of special polymer sulfur composite

    Science.gov (United States)

    Książek, Mariusz

    2016-07-01

    Specific chemical environments step out in the industry objects. Portland cement composites (concrete and mortar) were impregnated by using the special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot was applied as the industrial waste. Portland cement composites were made of the same aggregate, cement and water. The process of special polymer sulfur composite applied as the industrial waste is a thermal treatment process in the temperature of about 150-155°C. The result of such treatment is special polymer sulfur composite in a liquid state. This paper presents the plastic constants and coefficients of thermal expansion of special polymer sulfur composites, with isotropic porous matrix, reinforced by disoriented ellipsoidal inclusions with orthotropic symmetry of the thermoplastic properties. The investigations are based on the stochastic differential equations of solid mechanics. A model and algorithm for calculating the effective characteristics of special polymer sulfur composites are suggested. The effective thermoplastic characteristics of special polymer sulfur composites, with disoriented ellipsoidal inclusions, are calculated in two stages: First, the properties of materials with oriented inclusions are determined, and then effective constants of a composite with disoriented inclusions are determined on the basis of the Voigt or Rice scheme. A brief summary of new products related to special polymer sulfur composites is given as follows: Impregnation, repair, overlays and precast polymer concrete will be presented. Special polymer sulfur as polymer coating impregnation, which has received little attention in recent years, currently has some very interesting applications.

  4. Biosynthesis and functions of sulfur modifications in tRNA

    Directory of Open Access Journals (Sweden)

    Naoki eShigi

    2014-04-01

    Full Text Available Sulfur is an essential element for a variety of cellular constituents in all living organisms. In tRNA molecules, there are many sulfur-containing nucleosides, such as the derivatives of 2‑thiouridine (s2U, 4-thiouridine (s4U, 2-thiocytidine (s2C, and 2-methylthioadenosine (ms2A. Earlier studies established the functions of these modifications for accurate and efficient translation, including proper recognition of the codons in mRNA or stabilization of tRNA structure. In many cases, the biosynthesis of these sulfur modifications starts with cysteine desulfurases, which catalyze the generation of persulfide (an activated form of sulfur from cysteine. Many sulfur-carrier proteins are responsible for delivering this activated sulfur to each biosynthesis pathway. Finally, specific modification enzymes activate target tRNAs and then incorporate sulfur atoms. Intriguingly, the biosynthesis of 2-thiouridine in all domains of life is functionally and evolutionarily related to the ubiquitin-like post-translational modification system of cellular proteins in eukaryotes. This review summarizes the recent characterization of the biosynthesis of sulfur modifications in tRNA and the novel roles of this modification in cellular functions in various model organisms, with a special emphasis on 2-thiouridine derivatives. Each biosynthesis pathway of sulfur-containing molecules is mutually modulated via sulfur trafficking, and 2-thiouridine and codon usage bias have been proposed to control the translation of specific genes.

  5. The significance of glucosinolates for sulfur storage in Brassicaceae seedlings

    Directory of Open Access Journals (Sweden)

    Luit J. eDe Kok

    2014-12-01

    Full Text Available Brassica juncea seedlings contained a two-fold higher glucosinolate content than Brassica rapa and these secondary sulfur compounds accounted for up to 30 % of the organic sulfur fraction. The glucosinolate content was not affected by H2S and SO2 exposure, demonstrating that these sulfur compounds did not form a sink for excessive atmospheric supplied sulfur. Upon sulfate deprivation, the foliarly absorbed H2S and SO2 replaced sulfate as the sulfur source for growth of B. juncea and B. rapa seedlings. The glucosinolate content was decreased in sulfate-deprived plants, though its proportion of organic sulfur fraction was higher than that of sulfate-sufficient plants, both in absence and presence of H2S and SO2. The significance of myrosinase in the in situ turnover in these secondary sulfur compounds needs to be questioned, since there was no direct co-regulation between the content of glucosinolates and the transcript level and activity of myrosinase. Evidently, glucosinolates cannot be considered as sulfur storage compounds upon exposure to excessive atmospheric sulfur and are unlikely to be involved in the re-distribution of sulfur in B. juncea and B. rapa seedlings upon sulfate deprivation.

  6. Comparative Aspects of Sulfur Mineralization in Sediments of a Eutrophic Lake Basin †

    OpenAIRE

    Gary M King; Klug, M. J.

    1982-01-01

    The net mineralization of organic sulfur compounds in surface sediments of Wintergreen Lake was estimated from a mass-balance budget of sulfur inputs and sediment sulfur concentrations. The net mineralization of organic sulfur inputs is 80% of total sulfur) in sediment. Although sediment sulfur is predominantly organic, sulfate reduction is the most significant process in terms of the quantities of sulfur transformed in surface sediments. Rates of sulfate reduction in these sediments average ...

  7. Sulfur isotope ratios and the origins of the aerosols and cloud droplets in California stratus

    OpenAIRE

    Ludwig, F. L.

    2011-01-01

    Marine aerosols often have sulfur-to-chloride ratios greater than that found in seawater. Sulfur isotope ratios (34S/32S) were measured in aerosol and cloud droplet samples collected in the San Francisco Bay Area in an attempt to understand the processes that produce the observed sulfur-to-chloride ratios. Seawater sulfur usually has very high sulfur isotope ratios; fossil fuel sulfur tends to have smaller isotope ratios and sulfur of bacteriogenic origin still smaller. Samples collected in u...

  8. Multiwalled carbon nanotubes-sulfur composites with enhanced electrochemical performance for lithium/sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xin Zhou; Jin, Bo, E-mail: jinbo@jlu.edu.cn; Xin, Pei Ming; Wang, Huan Huan

    2014-07-01

    Multiwalled carbon nanotubes-sulfur (MWCNTs-S) composites were synthesized by chemical activation of MWCNTs and capillarity between sulfur and MWCNTs. The MWCNTs activated by potassium hydroxide (denoted as K-MWCNTs) were used as conductive additive. The as-prepared K-MWCNTs-S composites can display excellent cycle stability and rate capability with the initial discharge capacity of 741 mAh g⁻¹ and capacity retention of 80% after 50 cycles compared to pure S. The improvement in the electrochemical performance for K-MWCNTs-S composites is attributed to the interstitial structure of the MWCNTs resulted from the strong chemical etching, which can facilitate the insertion and extraction of Li ions and more better percolation of the electrolyte, and also ascribed to enhanced electronic conductivity of K-MWCNTs-S composites. It is indicated that the K-MWCNTs-S composites can be used as the cathode materials for lithium–sulfur batteries.

  9. Mesoporous carbon materials prepared from litchi shell as sulfur encapsulator for lithium-sulfur battery application

    Science.gov (United States)

    Sun, Zhenjie; Wang, Shuanjin; Yan, Longlong; Xiao, Min; Han, Dongmei; Meng, Yuezhong

    2016-08-01

    Novel mesoporous carbon materials (MCMs) with excellent electron conductivity and high surface area are successfully synthesized from waste litchi shells. The as-prepared MCMs possess a narrow pore size distribution (0.5-2.0 nm) and exhibit similar electron conductivities to conductive carbon black (Super P, Timcal). Because of the unique properties of MCMs, they are used as host matrixes to encapsulate sulfur for lithium-sulfur cathodes. The obtained MCMs-sulfur (MCMs-S) composite cathodes deliver a high initial specific capacity of 1667 mAh g-1. Moreover, 300 °C treated MCMs-S composite cathode shows a more stable discharge capacity than the untreated MCMs-S composite cathode, it remains 612 mAh g-1 after 200 cycles at a high current density of 0.5 C.

  10. Carbon/sulfur composite cathodes for flexible lithium/sulfur batteries: status and prospects

    Directory of Open Access Journals (Sweden)

    Yan eZhao

    2015-02-01

    Full Text Available High specific energy and low cost flexible lithium/sulfur batteries have attracted significant attention as a promising power source to enable future flexible and wearable electronic devices. Here, we review recent progress in the development of free-standing sulfur composite cathodes, with special emphasis on electrode material selectivity and battery structural design. The mini-review is organized based on the dimensionality of different scaffold materials, namely one dimensional carbon nanotube, two dimensional graphene and three dimensional carbon nanotube/graphene composite, respectively. Finally, the opportunities and perspectives of the future research directions are discussed.

  11. Effects of Sulfurization Temperature on Properties of CZTS Films by Vacuum Evaporation and Sulfurization Method

    OpenAIRE

    Jie Zhang; Bo Long; Shuying Cheng; Weibo Zhang

    2013-01-01

    Copper zinc tin sulfur (CZTS) thin films have been extensively studied in recent years for their advantages of low cost, high absorption coefficient (≥104 cm−1), appropriate band gap (~1.5 eV), and nontoxicity. CZTS thin films are promising materials of solar cells like copper indium gallium selenide (CIGS). In this work, CZTS thin films were prepared on glass substrates by vacuum evaporation and sulfurization method. Sn/Cu/ZnS (CZT) precursors were deposited by thermal evaporation and then s...

  12. Nitrogen--sulfur--carbon nanocomposites and their application as cathode materials in lithium--sulfur batteries

    Science.gov (United States)

    Dai, Sheng; Sun, Xiao-Guang; Guo, Bingkun; Wang, Xiqing; Mayes, Richard T.; Ben, Teng; Qiu, Shilun

    2016-09-27

    The invention is directed in a first aspect to electron-conducting porous compositions comprising an organic polymer matrix doped with nitrogen atoms and having elemental sulfur dispersed therein, particularly such compositions having an ordered framework structure. The invention is also directed to composites of such S/N-doped electron-conducting porous aromatic framework (PAF) compositions, or composites of an S/N-doped mesoporous carbon composition, which includes the S/N-doped composition in admixture with a binder, and optionally, conductive carbon. The invention is further directed to cathodes for a lithium-sulfur battery in which such composites are incorporated.

  13. Core-shell meso/microporous carbon host for sulfur loading toward applications in lithium-sulfur batteries

    Institute of Scientific and Technical Information of China (English)

    Juan Zhang; Huan Ye; Yaxia Yin; Yuguo Guo

    2014-01-01

    Lithium-sulfur (Li-S) batteries belong to one of the promising technologies for high-energy-density rechargeable batteries. However, sulfur cathodes suffer from inherent problems of its poor electronic conductivity and the shuttling of highly dissoluble lithium polysulfides generated during the cycles. Loading sulfur into porous carbons has been proved to be an effective approach to alleviate these issues. Mesoporous and microporous carbons have been widely used for sulfur accommodation, but mesoporous carbons have poor sulfur confinement, whereas microporous carbons are impeded by low sulfur loading rates. Here, a core-shell carbon, combining both the merits of mesoporous carbon with large pore volume and microporous carbon with effective sulfur confinement, was prepared by coating the mesoporous CMK-3 with a microporous carbon (MPC) shell and served as the carbon host (CMK-3@MPC) to accommodate sulfur. After sulfur infusion, the as-obtained S/(CMK-3@MPC) cathode delivered a high initial capacity of up to 1422 mAh·g-1 and sustained 654 mAh·g-1 reversible specific capacity after 36 cycles at 0.1 C. The good performance is ascribed to the unique core-shell structure of the CMK-3@MPC matrix, in which sulfur can be effectively confined within the meso/microporous carbon host, thus achieving simultaneously high electrochemical utilization.

  14. Sulfur speciation and bioaccumulation in camphor tree leaves as atmospheric sulfur indicator analyzed by synchrotron radiation XRF and XANES.

    Science.gov (United States)

    Zeng, Jianrong; Zhang, Guilin; Bao, Liangman; Long, Shilei; Tan, Mingguang; Li, Yan; Ma, Chenyan; Zhao, Yidong

    2013-03-01

    Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology. A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves (CTLs), which were sampled from 5 local fields in Shanghai, China. Annual SO2 concentration, SO4(2-) concentration in atmospheric particulate, SO4(2-) and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs. Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg. The mainly detected sulfur states and their corresponding compounds were +6 (sulfate, include inorganic sulfate and organic sulfate), +5.2 (sulfonate), +2.2 (suloxides), +0.6 (thiols and thiothers), +0.2 (organic sulfides). Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977, which suggested that sulfur accumulated in CTLs as sulfate form. Reduced sulfur compounds (organic sulfides, thiols, thioethers, sulfoxide and sulfonate) assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg. The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination. From urban to suburb place, sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced, but a dramatic increase presented near the seashore, where the marine sulfate emission and maritime activity pollution were significant. The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment. PMID:23923435

  15. Spontaneous bacterial peritonitis

    Institute of Scientific and Technical Information of China (English)

    Anastasios Koulaouzidis; Shivaram Bhat; Athar A Saeed

    2009-01-01

    Since its initial description in 1964, research has transformed spontaneous bacterial peritonitis (SBP) from a feared disease (with reported mortality of 90%) to a treatable complication of decompensated cirrhosis,albeit with steady prevalence and a high recurrence rate. Bacterial translocation, the key mechanism in the pathogenesis of SBP, is only possible because of the concurrent failure of defensive mechanisms in cirrhosis.Variants of SBP should be treated. Leucocyte esterase reagent strips have managed to shorten the 'tap-toshot' time, while future studies should look into their combined use with ascitic fluid pH. Third generation cephalosporins are the antibiotic of choice because they have a number of advantages. Renal dysfunction has been shown to be an independent predictor of mortality in patients with SBP. Albumin is felt to reduce the risk of renal impairment by improving effective intravascular volume, and by helping to bind proinflammatory molecules. Following a single episode of SBP, patients should have long-term antibiotic prophylaxis and be considered for liver transplantation.

  16. Antimicrobials for bacterial bioterrorism agents.

    Science.gov (United States)

    Sarkar-Tyson, Mitali; Atkins, Helen S

    2011-06-01

    The limitations of current antimicrobials for highly virulent pathogens considered as potential bioterrorism agents drives the requirement for new antimicrobials that are suitable for use in populations in the event of a deliberate release. Strategies targeting bacterial virulence offer the potential for new countermeasures to combat bacterial bioterrorism agents, including those active against a broad spectrum of pathogens. Although early in the development of antivirulence approaches, inhibitors of bacterial type III secretion systems and cell division mechanisms show promise for the future.

  17. Microbial Diversity and Population Structure of Extremely Acidic Sulfur-Oxidizing Biofilms From Sulfidic Caves

    Science.gov (United States)

    Jones, D.; Stoffer, T.; Lyon, E. H.; Macalady, J. L.

    2005-12-01

    Extremely acidic (pH 0-1) microbial biofilms called snottites form on the walls of sulfidic caves where gypsum replacement crusts isolate sulfur-oxidizing microorganisms from the buffering action of limestone host rock. We investigated the phylogeny and population structure of snottites from sulfidic caves in central Italy using full cycle rRNA methods. A small subunit rRNA bacterial clone library from a Frasassi cave complex snottite sample contained a single sequence group (>60 clones) similar to Acidithiobacillus thiooxidans. Bacterial and universal rRNA clone libraries from other Frasassi snottites were only slightly more diverse, containing a maximum of 4 bacterial species and probably 2 archaeal species. Fluorescence in situ hybridization (FISH) of snottites from Frasassi and from the much warmer Rio Garrafo cave complex revealed that all of the communities are simple (low-diversity) and dominated by Acidithiobacillus and/or Ferroplasma species, with smaller populations of an Acidimicrobium species, filamentous fungi, and protists. Our results suggest that sulfidic cave snottites will be excellent model microbial ecosystems suited for ecological and metagenomic studies aimed at elucidating geochemical and ecological controls on microbial diversity, and at mapping the spatial history of microbial evolutionary events such as adaptations, recombinations and gene transfers.

  18. Accidental Sulfur Poisoning in a Group of Holstein Heifers

    OpenAIRE

    Gunn, Moira F.; Baird, John D.; Wilkie, Judith S. Nimmo

    1987-01-01

    Fourteen animals died or were euthanized after toxic levels of elemental sulfur were accidentally fed to a group of 120 Holstein heifers. Dehydration, rumen stasis, tachycardia, and diarrhea were seen along with metabolic acidosis, hypokalemia, and hypochloremia. The majority of deaths occurred from 3 to 10 days after the sulfur was fed to the heifers. Postmortem examination showed rumenitis, acute alveolitis, and renal tubular necrosis. The toxicity of ingested sulfur was attributed to the c...

  19. World sulfur production: Petroleum derived as of January 1, 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    Data are presented on world sulfur production by company within each country. The table lists the source of the sulfur (refinery gases, natural gas, acid gas, sour gas, oil sands, associated gas, or resid asphalt), the type of process used to recovery the sulfur, plant design capacity, and production. Processes include Claus, chlorination, Scot, Sulfinol, Sulfreen, modified Claus, bed absorption, MDEA-LoCat, Selectox, Parsons, SNEA, Comprimo, Uhde, Stretford, and Wellman-Lord.

  20. Measuring global sulfur dioxide emissions with satellite sensors

    Science.gov (United States)

    Schultz, Colin

    2013-11-01

    Atmospheric sulfur dioxide affects the weather by enhancing cloud formation, and long-term shifts in emissions can change the climate by increasing the amount of solar radiation scattered back into space. Sulfur dioxide emissions are the basis for acid rain, and the gas itself can cause respiratory problems. Despite the compound's importance to climate, the difficulties associated with accurately measuring sulfur dioxide mean that rates of emissions are generally not well understood.

  1. Plant sulfur nutrition: From Sachs to Big Data

    OpenAIRE

    Kopriva, Stanislav

    2015-01-01

    Together with water and carbon dioxide plants require 14 essential mineral nutrients to finish their life cycle. The research in plant nutrition can be traced back to Julius Sachs, who was the first to experimentally prove the essentiality of mineral nutrients for plants. Among those elements Sachs showed to be essential is sulfur. Plant sulfur nutrition has been not as extensively studied as the nutrition of nitrogen and phosphate, probably because sulfur was not limiting for agriculture. Ho...

  2. 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.

  3. Sulfur dioxide contributions to the atmosphere by volcanoes.

    Science.gov (United States)

    Stoiber, R E; Jepsen, A

    1973-11-01

    The first extensive measurements by remote-sensing correlation spectrometry of the sulfur dioxide emitted by volcanic plumes indicate that on the order of 10(3) metric tons of sulfur dioxide gas enter the atmosphere daily from Central American volcanoes. Extrapolation gives a minimum estimate of the annual amount of sulfur dioxide emitted from the world's volcanoes of about 10(7) metric tons.

  4. Current toxicological information as the basis for sulfur oxide standards.

    OpenAIRE

    Mehlman, M A

    1983-01-01

    The ambient air quality standard established in 1973 is 0.03 ppm annual average for sulfur dioxide and 0.075 mg/m3 for particulates. It is now generally believed that the toxicity of sulfur oxides in ambient air is significantly influenced by the coincident presence of particulates. Inhalation of 1 ppm of sulfur dioxide for 2 hr may produce alterations in pulmonary ventilatory function, both in normal and asthmatic subjects. Effects obtained at 0.5 ppm of sulfur dioxide are controversial and ...

  5. Fractal desulfurization kinetics of high-sulfur coal

    Institute of Scientific and Technical Information of China (English)

    Xu Longjun; Peng Tiefeng; Zhang Dingyue; Zhang Fukai

    2012-01-01

    The pore structure characteristics of high-sulfur coal from Wansheng in Chongqing have been studied by a nitrogen adsorption method (BET).The effects of grinding and pre-treating with nitric acid on the inorganic sulfur content of coal have been investigated.Organic sulfur in coal pretreated with nitric acid was desulfurized by using propylene-glycol-KOH (PG-KOH).Fractal kinetic properties of these two desulfurization procedures were investigated by using fractal geometric theory.The results show that both the specific surface area and pore volume increased with the decrease in particle diameter.The microspore surface of coal had fractal characteristics; the fractal dimension was 2.48.The sulfur content decreased with the decrease in particle diameter by grinding.After pretreatment with nitric acid,the desulfurization ratio (DFR) of inorganic sulfur increased to over 99% and the DFR of total sulfur to over 70%.The desulfurization procedure of inorganic sulfur had fractal kinetic characteristics; its reactive fractal dimension was 2.94.The organic sulfur desulfurization procedure by PG-KOH was also tallied with fractal kinetic properties; the reactive fractal dimension was 2.57.The effect of temperature on the desulfurization ratio of organic sulfur can be described with an Arrhenius empirical equation.The rate constant,pre-exponential factor and the activation energy of the reaction increased with the decrease in particle diameter.

  6. Mercury adsorption properties of sulfur-impregnated adsorbents

    Science.gov (United States)

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  7. The triple point of sulfur hexafluoride

    Science.gov (United States)

    Rourke, P. M. C.

    2016-04-01

    A cryogenic fixed point cell has been filled with high purity (99.999%) sulfur hexafluoride (SF6) and measured in an adiabatic closed-cycle cryostat system. Temperature measurements of the SF6 melting curve were performed using a capsule-type standard platinum resistance thermometer (CSPRT) calibrated over the International Temperature Scale of 1990 (ITS-90) subrange from the triple point of equilibrium hydrogen to the triple point of water. The measured temperatures were corrected by 0.37 mK for the effects of thermometer self-heating, and the liquidus-point temperature estimated by extrapolation to melted fraction F  =  1 of a simple linear regression versus melted fraction F in the range F  =  0.53 to 0.84. Based on this measurement, the temperature of the triple point of sulfur hexafluoride is shown to be 223.555 23(49) K (k  =  1) on the ITS-90. This value is in excellent agreement with the best prior measurements reported in the literature, but with considerably smaller uncertainty. An analysis of the detailed uncertainty budget of this measurement suggests that if the triple point of sulfur hexafluoride were to be included as a defining fixed point of the next revision of the International Temperature Scale, it could do so with a total realization uncertainty of approximately 0.43 mK, slightly larger than the realization uncertainties of the defining fixed points of the ITS-90. Since the combined standard uncertainty of this SF6 triple point temperature determination is dominated by chemical impurity effects, further research exploring gas purification techniques and the influence of specific impurity species on the SF6 triple point temperature may bring the realization uncertainty of SF6 as a fixed point material into the range of the defining fixed points of the ITS-90.

  8. Bioinspired catalysis metal-sulfur complexes

    CERN Document Server

    Weigand, Wolfgang

    2014-01-01

    The growing interest in green chemistry calls for new, efficient and cheap catalysts. Living organisms contain a wide range of remarkably powerful enzymes, which can be imitated by chemists in the search for new catalysts. In bioinspired catalysis, chemists use the basic principles of biological enzymes when creating new catalyst analogues. In this book, an international group of experts cover the topic from theoretical aspects to applications by including a wide variety of examples of different systems. This valuable overview of bioinspired metal-sulfur catalysis is a must-have for all sci

  9. 40 CFR 52.1881 - Control strategy: Sulfur oxides (sulfur dioxide).

    Science.gov (United States)

    2010-07-01

    ... 40 CFR 52.1870: (i) Rules as effective in Ohio on December 28, 1979: OAC 3745-18-04(A), (B), (C), (D... citations affecting § 52.1881, see the List of CFR Sections Affected, which appears in the Finding Aids... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Sulfur oxides...

  10. Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur.

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    More than 170 wet scrubber systems applied, to 72,000 MW of U.S., coal-fired, utility boilers are in operation or under construction. In these systems, the sulfur dioxide removed from the boiler flue gas is permanently bound to a sorbent material, such as lime or limestone. The sulfated sorbent must be disposed of as a waste product or, in some cases, sold as a byproduct (e.g. gypsum). Due to the abundance and low cost of naturally occurring gypsum, and the costs associated with producing an industrial quality product, less than 7% of these scrubbers are configured to produce usable gypsum (and only 1% of all units actually sell the byproduct). The disposal of solid waste from each of these scrubbers requires a landfill area of approximately 200 to 400 acres. In the U.S., a total of 19 million tons of disposable FGD byproduct are produced, transported and disposed of in landfills annually. The use of regenerable sorbent technologies has the potential to reduce or eliminate solid waste production, transportation and disposal. In a regenerable sorbent system, the sulfur dioxide in the boiler flue gas is removed by the sorbent in an adsorber. The S0{sub 2}s subsequently released, in higher concentration, in a regenerator. All regenerable systems produce an off-gas stream from the regenerator that must be processed further in order to obtain a salable byproduct, such as elemental sulfur, sulfuric acid or liquid S0{sub 2}.

  11. SYNTHESIS OF SULFUR-BASED WATER TREATMENT AGENT FROM SULFUR DIOXIDE WASTE STREAMS

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Brown; Maohong Fan

    2001-12-01

    We propose a process that uses sulfur dioxide from coal combustion as a raw material to synthesize polymeric ferric sulfate (PFS), a water treatment agent. The process uses sodium chlorate as an oxidant and ferrous sulfate as an absorbent. The major chemical mechanisms in this reaction system include oxidation, hydrolysis, and polymerization. Oxidation determines sulfur conversion efficiency while hydrolysis and polymerization control the quality of product. Many factors, including SO{sub 2} inlet concentration, flow rate of simulated flue gas, reaction temperature, addition rate of oxidant and stirring rate, may affect the efficiencies of SO{sub 2} removal. Currently, the effects of SO{sub 2} inlet concentration, the flow rate of simulated flue gas and addition rate of flue gas on removal efficiencies of SO{sub 2}, are being investigated. Experiments shown in this report have demonstrated that the conversion efficiencies of sulfur dioxide with ferrous sulfate as an absorbent are in the range of 60-80% under the adopted process conditions. However, the conversion efficiency of sulfur dioxide may be improved by optimizing reaction conditions to be investigated. Partial quality indices of the synthesized products, including Fe{sup 2+} concentration and total iron concentration, have been evaluated.

  12. Graphene/sulfur hybrid nanosheets from a space-confined "sauna" reaction for high-performance lithium-sulfur batteries.

    Science.gov (United States)

    Fei, Linfeng; Li, Xiaogang; Bi, Wentuan; Zhuo, Zhiwen; Wei, Wenfei; Sun, Li; Lu, Wei; Wu, Xiaojun; Xie, Keyu; Wu, Changzheng; Chan, Helen L W; Wang, Yu

    2015-10-21

    A space-confined "sauna" reaction system is introduced for the simultaneous reduction and functionalization of graphene oxide to unique graphene-sulfur hybrid nanosheets, in which thin layers of amorphous sulfur are tightly anchored on the graphene sheet via strong chemical bonding. Upon being used as the cathode material in lithium-sulfur batteries, the as-synthesized composite shows an excellent electrochemical performance.

  13. [Small intestine bacterial overgrowth].

    Science.gov (United States)

    Leung Ki, E L; Roduit, J; Delarive, J; Guyot, J; Michetti, P; Dorta, G

    2010-01-27

    Small intestine bacterial overgrowth (SIBO) is a condition characterised by nutrient malabsorption and excessive bacteria in the small intestine. It typically presents with diarrhea, flatulence and a syndrome of malabsorption (steatorrhea, macrocytic anemia). However, it may be asymptomatic in the eldery. A high index of suspicion is necessary in order to differentiate SIBO from other similar presenting disorders such as coeliac disease, lactose intolerance or the irritable bowel syndrome. A search for predisposing factor is thus necessary. These factors may be anatomical (stenosis, blind loop), or functional (intestinal hypomotility, achlorydria). The hydrogen breath test is the most frequently used diagnostic test although it lacks standardisation. The treatment of SIBO consists of eliminating predisposing factors and broad-spectrum antibiotic therapy. PMID:20214190

  14. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...... the approaches used to study these complex communities. This review focuses on the establishment of multispecies biofilms in vitro, interspecies interactions in microhabitats, and how to select communities for evaluation. Studies have used different experimental approaches; here we evaluate the benefits...... and drawbacks of varying the degree of complexity. This review aims to facilitate multispecies biofilm research in order to expand the current limited knowledge on interspecies interactions. Recent technological advances have enabled total diversity analysis of highly complex and diverse microbial communities...

  15. Bacterial proteases and virulence

    DEFF Research Database (Denmark)

    Frees, Dorte; Brøndsted, Lone; Ingmer, Hanne

    2013-01-01

    Bacterial pathogens rely on proteolysis for variety of purposes during the infection process. In the cytosol, the main proteolytic players are the conserved Clp and Lon proteases that directly contribute to virulence through the timely degradation of virulence regulators and indirectly by providing...... tolerance to adverse conditions such as those experienced in the host. In the membrane, HtrA performs similar functions whereas the extracellular proteases, in close contact with host components, pave the way for spreading infections by degrading host matrix components or interfering with host cell...... signalling to short-circuit host cell processes. Common to both intra- and extracellular proteases is the tight control of their proteolytic activities. In general, substrate recognition by the intracellular proteases is highly selective which is, in part, attributed to the chaperone activity associated...

  16. Aspergillus flavus Conidia-derived Carbon/Sulfur Composite as a Cathode Material for High Performance Lithium–Sulfur Battery

    OpenAIRE

    Maowen Xu; Min Jia; Cuiping Mao; Sangui Liu; Shujuan Bao; Jian Jiang; Yang Liu; Zhisong Lu

    2016-01-01

    A novel approach was developed to prepare porous carbon materials with an extremely high surface area of 2459.6 m2g−1 by using Aspergillus flavus conidia as precursors. The porous carbon serves as a superior cathode material to anchor sulfur due to its uniform and tortuous morphology, enabling high capacity and good cycle lifetime in lithium sulfur-batteries. Under a current rate of 0.2 C, the carbon-sulfur composites with 56.7 wt% sulfur loading deliver an initial capacity of 1625 mAh g−1, w...

  17. Sustainable Sulfur-rich Copolymer/Graphene Composite as Lithium-Sulfur Battery Cathode with Excellent Electrochemical Performance

    OpenAIRE

    Arnab Ghosh; Swapnil Shukla; Gaganpreet Singh Khosla; Bimlesh Lochab; Sagar Mitra

    2016-01-01

    A sulfur-rich copolymer, poly(S-r-C-a) has been synthesized via a sustainable route, showing the utility of two major industrial wastes- elemental sulfur (petroleum waste) and cardanol (agro waste), to explore its potential as cathode material for Li-S batteries. The sulfur-rich copolymer exhibited a reduction in the active material dissolution into the electrolyte and a low self-discharge rate behavior during the rest time compared to an elemental sulfur cathode, indicating the chemical conf...

  18. Enhanced electrochemical performance of a crosslinked polyaniline-coated graphene oxide-sulfur composite for rechargeable lithium-sulfur batteries

    Science.gov (United States)

    Moon, San; Jung, Young Hwa; Kim, Do Kyung

    2015-10-01

    Due to the extraordinarily high theoretical capacity of sulfur (1675 mAh g-1), the lithium-sulfur (Li-S) battery has been considered a promising candidate for future high-energy battery applications. Li-S batteries, however, have suffered from limited cycle lives, mainly due to the formation of soluble polysulfides, which prevent the practical application of this attractive technology. The encapsulation of sulfur with various conductive materials has addressed this issue to some extent. Nevertheless, most approaches still present partial encapsulation of sulfur and moreover require a large quantity of conductive material (typically, >30 wt%), making the use of sulfur less desirable from the viewpoint of capacity. Here, we address these chronic issues of Li-S cells by developing a graphene oxide-sulfur composite with a thin crosslinked polyaniline (PANI) layer. Graphene oxide nanosheets with large surface area, high conductivity and a uniform conductive PANI layer, which are synthesized by a layer-by-layer method, have a synergetic interaction with a large portion of the sulfur in the active material. Furthermore, a simple crosslinking process efficiently prevents polysulfide dissolution, resulting in unprecedented electrochemical performance, even with a high sulfur content (∼75%): a high capacity retention of ∼80% is observed, in addition to 97.53% of the average Coulombic efficiency being retained after 500 cycles. The performance we demonstrate represents an advance in the field of lithium-sulfur batteries for applications such as power tools.

  19. Three-dimensional porous carbon composites containing high sulfur nanoparticle content for high-performance lithium–sulfur batteries

    Science.gov (United States)

    Li, Guoxing; Sun, Jinhua; Hou, Wenpeng; Jiang, Shidong; Huang, Yong; Geng, Jianxin

    2016-01-01

    Sulfur is a promising cathode material for lithium–sulfur batteries because of its high theoretical capacity (1,675 mA h g−1); however, its low electrical conductivity and the instability of sulfur-based electrodes limit its practical application. Here we report a facile in situ method for preparing three-dimensional porous graphitic carbon composites containing sulfur nanoparticles (3D S@PGC). With this strategy, the sulfur content of the composites can be tuned to a high level (up to 90 wt%). Because of the high sulfur content, the nanoscale distribution of the sulfur particles, and the covalent bonding between the sulfur and the PGC, the developed 3D S@PGC cathodes exhibit excellent performance, with a high sulfur utilization, high specific capacity (1,382, 1,242 and 1,115 mA h g−1 at 0.5, 1 and 2 C, respectively), long cycling life (small capacity decay of 0.039% per cycle over 1,000 cycles at 2 C) and excellent rate capability at a high charge/discharge current. PMID:26830732

  20. 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.

  1. Thermo Scientific Sulfur Dioxide Analyzer Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Springston, S. R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-03-01

    The Sulfur Dioxide Analyzer measures sulfur dioxide based on absorbance of UV light at one wavelength by SO2 molecules which then decay to a lower energy state by emitting UV light at a longer wavelength. Specifically, SO2 + hυ1 →SO2 *→SO2 + hυ2 The emitted light is proportional to the concentration of SO2 in the optical cell. External communication with the analyzer is available through an Ethernet port configured through the instrument network of the AOS systems. The Model 43i-TLE is part of the i-series of Thermo Scientific instruments. The i-series instruments are designed to interface with external computers through the proprietary Thermo Scientific iPort Software. However, this software is somewhat cumbersome and inflexible. BNL has written an interface program in National Instruments LabView that both controls the Model 43i-TLE Analyzer AND queries the unit for all measurement and housekeeping data. The LabView vi (the software program written by BNL) ingests all raw data from the instrument and outputs raw data files in a uniform data format similar to other instruments in the AOS and described more fully in Section 6.0 below.

  2. Sulfur chemistry in a copper smelter plume

    Energy Technology Data Exchange (ETDEWEB)

    Eatough, D.J.; Christensen, J.J.; Hill, M.W.; Major, T.D.; Mangelson, N.F.; Post, M.E.; Ryder, J.F.; Hansen, L.D.

    Sulfur transformation chemistry was studied in the plume of the Utah smelter of Kennecott Copper Corporation from April to October 1977. Samples were taken at up to four locations from 4 to 60 km from the stacks. Data collected at each station included: SO/sub 2/ concentration, low-volume collected total particulate matter, high-volume collected size fractionated particulate matter, wind velocity and direction, temperature, and relative humidity.The SO/sub 2/(g)-sulfate conversion process in the plume is described by a mechanism which is first order in SO/sub 2/(g). Equations are derived describing sulfur chemistry when both S(IV) and sulfate formation occur in a plume. The formation of sulfate results primarily in the formation of <0.5 ..mu..m particulates. The formation process is not correlated with plume expansion, particulate acidity, metal content, or S(IV) species. Due to meteorological restrictions on sampling, data were collected only during periods of maximum insolation. The formation of sulfate from SO/sub 2/(g) in the plume during periods of high insolation is temperature dependent with an apparent activation energy of 16.6 +/- 1.4 kcal mol/sup -1/ and k/sub 1/ value of 0.039 h/sup -1/ at 25/sup 0/C.

  3. Magnetic effects in sulfur-decorated graphene

    Science.gov (United States)

    Hwang, Choongyu; Cybart, Shane A.; Shin, S. J.; Kim, Sooran; Kim, Kyoo; Rappoport, T. G.; Wu, S. M.; Jozwiak, C.; Fedorov, A. V.; Mo, S.-K.; Lee, D.-H.; Min, B. I.; Haller, E. E.; Dynes, R. C.; Castro Neto, A. H.; Lanzara, Alessandra

    2016-02-01

    The interaction between two different materials can present novel phenomena that are quite different from the physical properties observed when each material stands alone. Strong electronic correlations, such as magnetism and superconductivity, can be produced as the result of enhanced Coulomb interactions between electrons. Two-dimensional materials are powerful candidates to search for the novel phenomena because of the easiness of arranging them and modifying their properties accordingly. In this work, we report magnetic effects in graphene, a prototypical non-magnetic two-dimensional semi-metal, in the proximity with sulfur, a diamagnetic insulator. In contrast to the well-defined metallic behaviour of clean graphene, an energy gap develops at the Fermi energy for the graphene/sulfur compound with decreasing temperature. This is accompanied by a steep increase of the resistance, a sign change of the slope in the magneto-resistance between high and low fields, and magnetic hysteresis. A possible origin of the observed electronic and magnetic responses is discussed in terms of the onset of low-temperature magnetic ordering. These results provide intriguing insights on the search for novel quantum phases in graphene-based compounds.

  4. Bacterial Protein-Tyrosine Kinases

    DEFF Research Database (Denmark)

    Shi, Lei; Kobir, Ahasanul; Jers, Carsten;

    2010-01-01

    in exopolysaccharide production, virulence, DNA metabolism, stress response and other key functions of the bacterial cell. BY-kinases act through autophosphorylation (mainly in exopolysaccharide production) and phosphorylation of other proteins, which have in most cases been shown to be activated by tyrosine......Bacteria and Eukarya share essentially the same family of protein-serine/threonine kinases, also known as the Hanks-type kinases. However, when it comes to protein-tyrosine phosphorylation, bacteria seem to have gone their own way. Bacterial protein-tyrosine kinases (BY-kinases) are bacterial...... and highlighted their importance in bacterial physiology. Having no orthologues in Eukarya, BY-kinases are receiving a growing attention from the biomedical field, since they represent a particularly promising target for anti-bacterial drug design....

  5. Molecular approaches for bacterial azoreductases

    Directory of Open Access Journals (Sweden)

    Montira Leelakriangsak

    2013-12-01

    Full Text Available Azo dyes are the dominant types of synthetic dyes, widely used in textiles, foods, leather, printing, tattooing, cosmetics, and pharmaceutical industries. Many microorganisms are able to decolorize azo dyes, and there is increasing interest in biological waste treatment methods. Bacterial azoreductases can cleave azo linkages (-N=N- in azo dyes, forming aromatic amines. This review mainly focuses on employing molecular approaches, including gene manipulation and recombinant strains, to study bacterial azoreductases. The construction of the recombinant protein by cloning and the overexpression of azoreductase is described. The mechanisms and function of bacterial azoreductases can be studied by other molecular techniques discussed in this review, such as RT-PCR, southern blot analysis, western blot analysis, zymography, and muta-genesis in order to understand bacterial azoreductase properties, function and application. In addition, understanding the regulation of azoreductase gene expression will lead to the systematic use of gene manipulation in bacterial strains for new strategies in future waste remediation technologies.

  6. Extreme variation of sulfur isotopic compositions in pyrite from the Qiuling sediment-hosted gold deposit, West Qinling orogen, central China: an in situ SIMS study with implications for the source of sulfur

    Science.gov (United States)

    Chen, Lei; Li, Xian-hua; Li, Jian-wei; Hofstra, Albert H.; Liu, Yu; Koenig, Alan E.

    2015-08-01

    High spatial resolution textural (scanning electron microscope (SEM)), chemical (electron microprobe (EMP)) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)), and sulfur isotopic (secondary ion mass spectrometry (SIMS)) analyses of pyrite from the Qiuling sediment-hosted gold deposit (232 ± 4 Ma) in the West Qinling orogen, central China were conducted to distinguish pyrite types and gain insights into the source and evolution of sulfur in hydrothermal fluids. The results reveal an enormous variation (-27.1 to +69.6 ‰) in sulfur isotopic composition of pyrite deposited during three paragenetic stages. Pre-ore framboidal pyrite, which is characterized by low concentrations of As, Au, Cu, Co, and Ni, has negative δ34S values of -27.1 to -7.6 ‰ that are interpreted in terms of bacterial reduction of marine sulfate during sedimentation and diagenesis of the Paleozoic carbonate and clastic sequences, the predominant lithologies in the deposit area, and the most important hosts of many sediment-hosted gold deposits throughout the West Qinling orogen. The ore-stage hydrothermal pyrite contains high concentrations of Au, As, Cu, Sb, Tl, and Bi and has a relatively narrow range of positive δ34S values ranging from +8.1 to +15.2 ‰. The sulfur isotope data are comparable to those of ore pyrite from many Triassic orogenic gold deposits and Paleozoic sedimentary exhalative (SEDEX) Pb-Zn deposits in the West Qinling orogen, both being hosted mainly in the Devonian sequence. This similarity indicates that sulfur, responsible for the auriferous pyrite at Qiuling, was largely derived from the metamorphic devolatization of Paleozoic marine sedimentary rocks. Post-ore-stage pyrite, which is significantly enriched in Co and Ni but depleted in Au and As, has unusually high δ34S values ranging from +37.4 to +69.6 ‰, that are interpreted to result from thermochemical reduction of evaporite sulfates in underlying Cambrian sedimentary rocks with very

  7. 40 CFR Appendix T to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur...

    Science.gov (United States)

    2010-07-01

    ... Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) T Appendix T to Part 50 Protection of... AIR QUALITY STANDARDS Pt. 50, App. T Appendix T to Part 50—Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide) 1. General (a) This appendix...

  8. Bacterial chemoautotrophy in coastal sediments

    NARCIS (Netherlands)

    Vasquez Cardenas, D.

    2016-01-01

    Chemoautotrophy is the process by which micro-organisms fix CO2 by obtainingenergy from the oxidation of reduced compounds such sulfide and ammonium (e.g.sulfur oxidation and nitrification). This metabolism is widespread in nature and isvastly studied in extreme environments such as hydrothermal ven

  9. Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment.

    Science.gov (United States)

    Koh, Eunmi; Surh, Jeonghee

    2016-06-01

    Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing capacity of the juices increased at higher thermal processing temperatures; however, it was also lower in the Sulfur-4 onion juice. This suggests that the heat treatment of onions enhanced their antioxidant activity, but the effect was offset in the Sulfur-4 onion juice presumably due to higher sulfur content. This study indicates that sulfur, a core element for the functionality of onions, can decrease the antioxidant activity of thermally processed onions because of its potential as a Maillard reaction inhibitor. PMID:27390734

  10. Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment

    Science.gov (United States)

    Koh, Eunmi; Surh, Jeonghee

    2016-01-01

    Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing capacity of the juices increased at higher thermal processing temperatures; however, it was also lower in the Sulfur-4 onion juice. This suggests that the heat treatment of onions enhanced their antioxidant activity, but the effect was offset in the Sulfur-4 onion juice presumably due to higher sulfur content. This study indicates that sulfur, a core element for the functionality of onions, can decrease the antioxidant activity of thermally processed onions because of its potential as a Maillard reaction inhibitor. PMID:27390734

  11. Use of sulfur-oxidizing bacteria as recognition elements in hydrogen sulfide biosensing system.

    Science.gov (United States)

    Janfada, Behdokht; Yazdian, Fatemeh; Amoabediny, Ghassem; Rahaie, Mahdi

    2015-01-01

    Four sulfur-oxidizing bacteria (Thiobacillus thioparus, Acidithiobacillus thiooxidans PTCC1717, Acidithiobacillus ferrooxidans PTCC1646, and Acidithiobacillus ferrooxidans PTCC1647) were used as biorecognition elements in a hydrogen sulfide biosensing system. All the experiments were performed in 0.1 M phosphate buffer solution containing 1-20 ppm H2S with optimum pH and temperature for each species. Although H2 S was applied to the biosensing system, the dissolved O2 content decreased. Dissolved O2 consumed by cells in both free and immobilized forms was measured using a dissolved oxygen sensor. Free bacterial cells exhibit fast response (thiooxidans retained more than 50% of activity after 30 days of immobilization. According to the data, A. thiooxidans and A. ferrooxidans are appropriate species for hydrogen sulfide biosensor.

  12. Archaeal and bacterial diversity in acidic to circumneutral hot springs in the Philippines.

    Science.gov (United States)

    Huang, Qiuyuan; Jiang, Hongchen; Briggs, Brandon R; Wang, Shang; Hou, Weiguo; Li, Gaoyuan; Wu, Geng; Solis, Ramonito; Arcilla, Carlo A; Abrajano, Teofilo; Dong, Hailiang

    2013-09-01

    The microbial diversity was investigated in sediments of six acidic to circumneutral hot springs (Temperature: 60-92 °C, pH 3.72-6.58) in the Philippines using an integrated approach that included geochemistry and 16S rRNA gene pyrosequencing. Both bacterial and archaeal abundances were lower in high-temperature springs than in moderate-temperature ones. Overall, the archaeal community consisted of sequence reads that exhibited a high similarity (nucleotide identity > 92%) to phyla Crenarchaeota, Euryarchaeota, and unclassified Archaea. The bacterial community was composed of sequence reads moderately related (nucleotide identity > 90%) to 17 phyla, with Aquificae and Firmicutes being dominant. These phylogenetic groups were correlated with environmental conditions such as temperature, dissolved sulfate and calcium concentrations in spring water, and sediment properties including total nitrogen, pyrite, and elemental sulfur. Based on the phylogenetic inference, sulfur metabolisms appear to be key physiological functions in these hot springs. Sulfobacillus (within phylum Firmicutes) along with members within Sulfolobales were abundant in two high-temperature springs (> 76 °C), and they were hypothesized to play an important role in regulating the sulfur cycling under high-temperature conditions. The results of this study improve our understanding of microbial diversity and community composition in acidic to circumneutral terrestrial hot springs and their relationships with geochemical conditions.

  13. Bacterial Community Associated with Organs of Shallow Hydrothermal Vent Crab Xenograpsus testudinatus near Kuishan Island, Taiwan.

    Science.gov (United States)

    Yang, Shan-Hua; Chiang, Pei-Wen; Hsu, Tin-Chang; Kao, Shuh-Ji; Tang, Sen-Lin

    2016-01-01

    Shallow-water hydrothermal vents off Kueishan Island (northeastern Taiwan) provide a unique, sulfur-rich, highly acidic (pH 1.75-4.6) and variable-temperature environment. In this species-poor habitat, the crab Xenograpsus testudinatus is dominant, as it mainly feeds on zooplankton killed by sulfurous plumes. In this study, 16S ribosomal RNA gene amplicon pyrosequencing was used to investigate diversity and composition of bacteria residing in digestive gland, gill, stomach, heart, and mid-gut of X. testudinatus, as well as in surrounding seawater. Dominant bacteria were Gamma- and Epsilonproteobacteria that might be capable of autotrophic growth by oxidizing reduced sulfur compounds and are usually resident in deep-sea hydrothermal systems. Dominant bacterial OTUs in X. testudinatus had both host and potential organ specificities, consistent with a potential trophic symbiotic relationship (nutrient transfer between host and bacteria). We inferred that versatile ways to obtain nutrients may provide an adaptive advantage for X. testudinatus in this demanding environment. To our knowledge, this is the first study of bacterial communities in various organs/tissues of a crustacean in a shallow-water hydrothermal system, and as such, may be a convenient animal model for studying these systems. PMID:26934591

  14. Bacterial Community Associated with Organs of Shallow Hydrothermal Vent Crab Xenograpsus testudinatus near Kuishan Island, Taiwan.

    Science.gov (United States)

    Yang, Shan-Hua; Chiang, Pei-Wen; Hsu, Tin-Chang; Kao, Shuh-Ji; Tang, Sen-Lin

    2016-01-01

    Shallow-water hydrothermal vents off Kueishan Island (northeastern Taiwan) provide a unique, sulfur-rich, highly acidic (pH 1.75-4.6) and variable-temperature environment. In this species-poor habitat, the crab Xenograpsus testudinatus is dominant, as it mainly feeds on zooplankton killed by sulfurous plumes. In this study, 16S ribosomal RNA gene amplicon pyrosequencing was used to investigate diversity and composition of bacteria residing in digestive gland, gill, stomach, heart, and mid-gut of X. testudinatus, as well as in surrounding seawater. Dominant bacteria were Gamma- and Epsilonproteobacteria that might be capable of autotrophic growth by oxidizing reduced sulfur compounds and are usually resident in deep-sea hydrothermal systems. Dominant bacterial OTUs in X. testudinatus had both host and potential organ specificities, consistent with a potential trophic symbiotic relationship (nutrient transfer between host and bacteria). We inferred that versatile ways to obtain nutrients may provide an adaptive advantage for X. testudinatus in this demanding environment. To our knowledge, this is the first study of bacterial communities in various organs/tissues of a crustacean in a shallow-water hydrothermal system, and as such, may be a convenient animal model for studying these systems.

  15. Ferredoxin Competes with Bacterial Frataxin in Binding to the Desulfurase IscS*

    Science.gov (United States)

    Yan, Robert; Konarev, Petr V.; Iannuzzi, Clara; Adinolfi, Salvatore; Roche, Béatrice; Kelly, Geoff; Simon, Léa; Martin, Stephen R.; Py, Béatrice; Barras, Frédéric; Svergun, Dmitri I.; Pastore, Annalisa

    2013-01-01

    The bacterial iron-sulfur cluster (isc) operon is an essential machine that is highly conserved from bacteria to primates and responsible for iron-sulfur cluster biogenesis. Among its components are the genes for the desulfurase IscS that provides sulfur for cluster formation, and a specialized ferredoxin (Fdx) whose role is still unknown. Preliminary evidence suggests that IscS and Fdx interact but nothing is known about the binding site and the role of the interaction. Here, we have characterized the interaction using a combination of biophysical tools and mutagenesis. By modeling the Fdx·IscS complex based on experimental restraints we show that Fdx competes for the binding site of CyaY, the bacterial ortholog of frataxin and sits in a cavity close to the enzyme active site. By in vivo mutagenesis in bacteria we prove the importance of the surface of interaction for cluster formation. Our data provide the first structural insights into the role of Fdx in cluster assembly. PMID:23839945

  16. 40 CFR 52.724 - Control strategy: Sulfur dioxide.

    Science.gov (United States)

    2010-07-01

    ... Board necessary to insure attainment and maintenance of the sulfur dioxide standard, and the... federally Enforceable State Operating Permit controlling sulfur dioxide emissions from the boilers and... request and maintenance plan for Peoria and Hollis Townships in Peoria County and Groveland Township...

  17. Sulfur content of gasoline and diesel fuels in northern China

    International Nuclear Information System (INIS)

    In order to investigate vehicle fuel quality in northern China, the sulfur content of fuels purchased from the market has been studied. 235 samples from urban areas and highway service stations were collected and tested with energy dispersive X-ray fluorescence spectrometry. 88% of the gasoline samples contained sulfur below 500 ppm, the limit then in effect, and 92.5% of the diesel fuel samples were below 2000 ppm, the required limit. China's Ministry of Environmental Protection recommend lower sulfur to assure that the vehicles using the fuels comply with the China III emission standards-those limits are 150 ppm sulfur for gasoline and 350 ppm for diesel fuel. The recommended limits were not often met: in Jinan, Shanghai, Changchun and Xi'an, 0%, 11%, 46% and 60% of the gasoline sampled were below 150 ppm sulfur. For samples from highway stations, only 14-58% of gasoline was under the 150 ppm sulfur and only 0-67% of diesel samples below 350 ppm in different regions. This mismatch, between fuel sulfur levels that would enable vehicle emission controls to operate effectively, and the actual fuel sulfur levels at service stations, results in unnecessarily high pollution from potentially cleaner vehicles.

  18. Atmospheric deposition of nitrogen and sulfur in Louisiana

    Science.gov (United States)

    Zhang, H.; Guo, H.

    2015-12-01

    Wet deposition and dry deposition reduce their concentrations of sulfur and nitrogen contained air pollutants in atmosphere, but lead to increase of sulfur and nitrogen fluxes to the surface. Atmospheric deposition of sulfur and nitrogen can lead to acidification of surface water bodies (lakes, rivers, and coasts) and subsequent damage to aquatic ecosystems as well as damage to forests and vegetation. Louisiana has abundant water resources with approximately 11% of the total surface area composed of water bodies. It is important to protect water resources from excessive atmospheric deposition of sulfur and nitrogen. However, the information obtained from the observation systems for understanding the deposition of sulfur and nitrogen and the adverse effects in Louisiana is limited. This study uses a source-oriented CMAQ model to simulate emission, formation, transport, and deposition of sulfur and nitrogen species in Louisiana. WRF is used to generate the meteorological inputs and SMOKE is used to generate the emissions based on national emission inventory (NEI). The forms and quantities of sulfur and nitrogen deposition from wet and dry processes in Louisiana will be discovered. The spatial and temporal variations of sulfur and nitrogen fluxes will be quantified and contributions of major source sectors or source regions will be quantified.

  19. Sulfur Flow Analysis for New Generation Steel Manufacturing Process

    Institute of Scientific and Technical Information of China (English)

    HU Chang-qing; ZHANG Chun-xia; HAN Xiao-wei; YIN Rui-yu

    2008-01-01

    Sulfur flow for new generation steel manufacturing process is analyzed by the method of material flow analysis,and measures for SO2 emission reduction are put forward as assessment and target intervention of the results.The results of sulfur flow analysis indicate that 90% of sulfur comes from fuels.Sulfur finally discharges from the steel manufacturing route in various steps,and the main point is BF and BOF slag desulfurization.In sintering process,the sulfur is removed by gasification,and sintering process is the main source of SO2 emission.The sulfur content of coke oven gas (COG) is an important factor affecting SO2 emission.Therefore,SO2 emission reduction should be started from the optimization and integration of steel manufacturing route,sulfur burden should be reduced through energy saving and consumption reduction,and the sulfur content of fuel should be controlled.At the same time,BF and BOF slag desulfurization should be optimized further and coke oven gas and sintering exhausted gas desulfurization should be adopted for SO2 emission reduction and reuse of resource,to achieve harmonic coordination of economic,social,and environmental effects for sustainable development.

  20. Sulfur in human nutrition - effects beyond protein synthesis

    NARCIS (Netherlands)

    Schaafsma, Gertjan

    2008-01-01

    That sulfur is essential to humans is based on the requirement of S-animo acids for normal growth and maintenance of nitrogen balance and not on the optimization of metabolic proccesses involving the synthesis of non-protein sulphur containing compounds. This paper reviews the significance of sulfur

  1. Two-step rapid sulfur capture. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-04-01

    The primary goal of this program was to test the technical and economic feasibility of a novel dry sorbent injection process called the Two-Step Rapid Sulfur Capture process for several advanced coal utilization systems. The Two-Step Rapid Sulfur Capture process consists of limestone activation in a high temperature auxiliary burner for short times followed by sorbent quenching in a lower temperature sulfur containing coal combustion gas. The Two-Step Rapid Sulfur Capture process is based on the Non-Equilibrium Sulfur Capture process developed by the Energy Technology Office of Textron Defense Systems (ETO/TDS). Based on the Non-Equilibrium Sulfur Capture studies the range of conditions for optimum sorbent activation were thought to be: activation temperature > 2,200 K for activation times in the range of 10--30 ms. Therefore, the aim of the Two-Step process is to create a very active sorbent (under conditions similar to the bomb reactor) and complete the sulfur reaction under thermodynamically favorable conditions. A flow facility was designed and assembled to simulate the temperature, time, stoichiometry, and sulfur gas concentration prevalent in the advanced coal utilization systems such as gasifiers, fluidized bed combustors, mixed-metal oxide desulfurization systems, diesel engines, and gas turbines.

  2. EMISSIONS OF SULFUR TRIOXIDE FROM COAL-FIRED POWER PLANTS

    Science.gov (United States)

    Emissions of sulfur trioxide (SO3) are a key component of plume opacity and acid deposition. Consequently, these emissions need to be low enough not to cause opacity violations and acid deposition. Generally, a small fraction of sulfur in coal is converted to SO3 in coal-fired co...

  3. Sulfur K-edge absorption spectroscopy on selected biological systems

    International Nuclear Information System (INIS)

    Sulfur is an essential element in organisms. In this thesis investigations of sulfur compounds in selected biological systems by XANES (X-ray Absorption Near Edge Structure) spectroscopy are reported. XANES spectroscopy at the sulfur K-edge provides an excellent tool to gain information about the local environments of sulfur atoms in intact biological samples - no extraction processes are required. Spatially resolved measurements using a Kirkpatrick-Baez mirror focusing system were carried out to investigate the infection of wheat leaves by rust fungi. The results give information about changes in the sulfur metabolism of the host induced by the parasite and about the extension of the infection into visibly uninfected plant tissue. Furthermore, XANES spectra of microbial mats from sulfidic caves were measured. These mats are dominated by microbial groups involved in cycling sulfur. Additionally, the influence of sulfate deprivation and H2S exposure on sulfur compounds in onion was investigated. To gain an insight into the thermal degradation of organic material the influence of roasting of sulfur compounds in coffee beans was studied. (orig.)

  4. THE EFFECT OF ATRAZINE ON DIMETHYL SULFUR IN MARINE PHYTOPLANKTON

    Science.gov (United States)

    It is anticipated that under stress, the cellular DMSP concentration should drop, as sulfur is transferred from the DMSP pool to DMS. Sulfur in the DMS pool will be transferred to the DMSO pool as radicals are scavenged. Enzyme activities such as DMSP lyase, which converts D...

  5. Sulfur speciation and bioaccumulation in camphor tree leaves as atmospheric sulfur indicator analyzed by synchrotron radiation XRF and XANES

    Institute of Scientific and Technical Information of China (English)

    Jianrong Zeng; Guilin Zhang; Liangman Bao; Shilei Long; Mingguang Tan; Yan Li; Chenyan Ma

    2013-01-01

    Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmentalbiology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy wasestablished to analyze the sulfur concentration and speciation in mature camphor tree leaves (CTLs),which were sampled from 5 localfields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentrationin soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Totalsulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their correspondingcompounds were +6 (sulfate,include inorganic sulfate and organic sulfate),+5.2 (sulfonate),+2.2 (suloxides),+0.6 (thiols andthiothers),+0.2 (organic sulfides).Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlationcoefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds (organic sulfides,thiols,thioethers,sulfoxide and sulfonate) assimilation was sufficed to meet the nutrient requirement for growth at a balanced levelaround 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulateinstead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmosphericsulfur pollution in local environment.

  6. Extractive de-sulfurization and de-ashing of high sulfur coals by oxidation with ionic liquids

    International Nuclear Information System (INIS)

    Highlights: • Extractive de-sulfurization and de-ashing process for cleaning high sulfur coals. • The process removes inorganic as well as organic sulfur components from high sulfur coals. • The process has less risk to chemists and other surroundings. - Abstract: The environmental consequences of energy production from coals are well known, and are driving the development of desulfurization technologies. In this investigation, ionic liquids were examined for extractive desulfurization and de-ashing in industrially important high sulfur sub-bituminous Indian coals. The ionic liquids, namely, 1-n-butyl-3-methylimidazolium tetrafluoroborate (IL1) and 1-n-butyl 3-methylimidazolium chloride (IL2) were employed for desulfurization of a few Indian coal samples in presence of HCOOH/H2O2 and V2O5. Results show the maximum removal of 50.20% of the total sulfur, 48.00% of the organic sulfur, and 70.37 wt% of the ash in this process. The ionic liquids were recovered and subsequently used for further desulfurization. FT-IR spectra reveal the transformation of organic sulfur functionalities into the sulfoxides (S=O) and sulfones (-SO2) due to the oxidative reactions. The sulfate, pyrite and sulfides (aryls) signals in the near edge X-ray absorption fine structure (NEXAFS) of the oxidized coal samples showed sulfur transformation during the desulfurization process. The study demonstrates the removal of significant amount of inorganic as well as organic sulfur (aryls) components from the original high sulfur coal samples to make them cleaner

  7. The contribution of aircraft emissions to the atmospheric sulfur budget

    Energy Technology Data Exchange (ETDEWEB)

    Kjellstroem, E. [Stockholm Univ. (Sweden). Dept. of Meteorology; Feichter, J. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Sausen, R.; Hein, R. [Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

    1998-01-01

    An atmospheric general circulation model including the atmospheric sulfur cycle has been used to investigate the impact of aircraft sulfur emissions on the global sulfur budget of the atmosphere. The relative contribution from aircraft sulfur to the atmospheric sulfate burden is larger than the ratio between aircraft emissions and surface emissions due to the calculated long turn-over time of aircraft sulfate (about 12 days). However, in terms of the sulfate mass balance, aircraft emissions are small, contributing about 1% of the total sulfate mass north of 40 deg C where the aircraft emissions are largest. Despite this small contribution to sulfate mass, the aircraft emissions could potentially significantly enhance the background number concentration of aerosol particles. Based on the model calculations the increased stratospheric background aerosol mass observed during the last decades can not be explained by increased aircraft sulfur emissions 50 refs, 9 figs, 4 tabs

  8. Geochemical evidence for cryptic sulfur cycling in salt marsh sediments

    DEFF Research Database (Denmark)

    Mills, Jennifer V.; Antler, Gilad; Turchyn, Alexandra V.

    2016-01-01

    to represent the salt marsh sediments suggests that the uptake rate of sulfate during this cryptic sulfur cycling is similar to the uptake rate of sulfate during the fastest microbial sulfate reduction that has been measured in the natural environment. The difference is that during cryptic sulfur cycling, all...... investigate sulfur cycling in salt marsh sediments from Norfolk, England where we observe high ferrous iron concentrations with no depletion of sulfate or change in the sulfur isotope ratio of that sulfate, but a 5‰ increase in the oxygen isotope ratio in sulfate, indicating that sulfate has been through...... a reductive cycle replacing its oxygen atoms. This cryptic sulfur cycle was replicated in laboratory incubations using 18O-enriched water, demonstrating that the field results do not solely result from mixing processes in the natural environment. Numerical modeling of the laboratory incubations scaled...

  9. Extraction of mercury(II) with sulfurized jojoba oil

    Energy Technology Data Exchange (ETDEWEB)

    Wisniak, J.; Schorr, G.; Zacovsky, D.; Belfer, S. (Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Chemical Engineering)

    1990-09-01

    Sulfurized jojoba oil containing 12% by weight S has been tested as an extractant for Hg(II) from aqueous solutions. This paper reports on experiments performed with the extractant dissolved in a solvent (liquid--liquid extraction) or adsorbed in an appropriate resin matrix (solid--liquid extraction). The extraction characteristics of both systems have been measured and show that sulfurized jojoba oil exhibits very good possibilities as an extractant. The performance of several resins treated with sulfurized jojoba oil for adsorbing mercury(II) was studied. The morphology of the different resins was examined by using scanning electron microscopy. The sulfurized oil is attached to the resin sites through the sulfur atoms; it is estimated that there are about 2 mol of S active sites per kilogram of resin.

  10. Influence of sulfur physical properties in Claus unit operation

    Energy Technology Data Exchange (ETDEWEB)

    Larraz Mora, R.; Arvelo Alvarez, R. [Chemical Engineering Dept., Univ. of la Laguna, Tenerife (Spain)

    2002-09-01

    The Claus process is an efficient way of removing H{sub 2}S from acid gas streams and it has been widely practiced in industries such as natural gas processing, oil refining and metal smelting. Increasingly strict pollution control regulations require maximum sulfur recovery and high stream factor from the Claus units in order to minimize sulfur-containing effluents. As has been widely reported Claus unit's damages mainly occur during start up and shutdown. These operations involve scheduled warm-up and cool-down of the unit, usually burning refinery fuel-gas, which if not properly made can produce severe pipe and equipment plugging as well as catalyst deactivation. Sulfur products remaining in the unit during a shutdown period can produce dramatic unit corrosion episodes diminishing sulfur recovery unit stream factor. In the present paper some guidelines are given based on sulfur physical properties singularities which help to improve start-up/shut-down procedures. (orig.)

  11. Low cost pavement marking materials based on plasticized sulfur

    Science.gov (United States)

    Dale, J. M.

    1982-04-01

    Pavement marking was made more cost effective by reducing the cost of the marking materials. A low cost marking material based on sulfur was developed. Elemental sulfur is a hard, brittle, crystalline material which, on heating, melts to a thin liquid that can be spray applied. If molten elemental sulfur is spray applied to the road as markings, it will on application solidify, crack and adhere poorly to the road. The first ten high speed trucks that ride over the markings will remove them. To make a useful sulfur based pavement marking material it was necessary to chemically modify (plasticize) the sulfur and mix it with fillers and pigments such that it had all of the characteristics desired of a pavement marking material. Yellow and white formulations were developed. For identification they were given the names YS-EIGHT and WS-EIGHT for the yellow and white formulations.

  12. Biodesulfurization of refractory organic sulfur compounds in fossil fuels.

    Science.gov (United States)

    Soleimani, Mehran; Bassi, Amarjeet; Margaritis, Argyrios

    2007-01-01

    The stringent new regulations to lower sulfur content in fossil fuels require new economic and efficient methods for desulfurization of recalcitrant organic sulfur. Hydrodesulfurization of such compounds is very costly and requires high operating temperature and pressure. Biodesulfurization is a non-invasive approach that can specifically remove sulfur from refractory hydrocarbons under mild conditions and it can be potentially used in industrial desulfurization. Intensive research has been conducted in microbiology and molecular biology of the competent strains to increase their desulfurization activity; however, even the highest activity obtained is still insufficient to fulfill the industrial requirements. To improve the biodesulfurization efficiency, more work is needed in areas such as increasing specific desulfurization activity, hydrocarbon phase tolerance, sulfur removal at higher temperature, and isolating new strains for desulfurizing a broader range of sulfur compounds. This article comprehensively reviews and discusses key issues, advances and challenges for a competitive biodesulfurization process.

  13. Biogeochemistry of the sulfur oxidizer Thiomicrospira thermophila

    Science.gov (United States)

    Houghton, J.; Fike, D. A.; Wills, E.; Foustoukos, D.

    2013-12-01

    Near-seafloor hydrothermal environments such as diffuse flow venting or subsurface mixing are characterized by rapidly changing conditions and steep chemical and thermal gradients. Microorganisms living in these environments can take advantage of these changes by switching among metabolic pathways rather than specializing. We present reaction stoichiometry and rates for T. thermophila grown in a closed system both at ambient and elevated pressure (50 bars) that demonstrate substantial metabolic flexibility, shifting between up to 5 different sulfur cycling reactions over a 24 hour period. Based on the stoichiometry between S2O3 consumed and SO4 produced, three reactions are sulfur oxidation and two are disproportionation, which has not previously been demonstrated for Thiomicrospira strains. Reactants include S2O3, elemental S (both polymeric S chains and S8 rings), HS-, and O2, while products include polymeric elemental S, SO4, HS-, and polysulfides. The presence of μmolal concentrations of HS- has been confirmed during the time series only when stoichiometry predicts disproportionation. Production of HS- in the presence of elemental S results in abiotic conversion to polysulfides, keeping the sulfide concentrations low in solution. The transition from oxidation to disproportionation appears to be triggered by a depletion in dissolved oxygen and the rate of reaction is a second order function of S2O3 and O2 concentrations. Growth was tested at conditions spanning their pH tolerance (5.0 - 8.0) using a citrate buffer (pH 5.0), unbuffered media (initial pH 7.0), and Tris buffer (pH 8.0). The highest rates are observed at pH 8.0 with rates decreasing as a function of pH. The lowest rate occurs at pH 5.0 and exhibits pseudo-first order behavior over a 24 hour period, likely due to a long lag and very slow growth. Repeat injections after the culture is acclimated to the experimental conditions result in very high pseudo-first order rates due to rapid consumption of

  14. Amine reactivity with charged sulfuric acid clusters

    Directory of Open Access Journals (Sweden)

    B. R. Bzdek

    2011-08-01

    Full Text Available The distribution of charged species produced by electrospray of an ammonium sulfate solution in both positive and negative polarities is examined using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS. Positively-charged ammonium bisulfate cluster composition differs significantly from negatively-charged cluster composition. For positively-charged clusters all sulfuric acid is neutralized to bisulfate, whereas for negatively-charged clusters the degree of sulfuric acid neutralization is cluster size-dependent. With increasing cluster size (and, therefore, a decreasing role of charge, both positively- and negatively-charged cluster compositions converge toward ammonium bisulfate. The reactivity of negatively-charged sulfuric acid-ammonia clusters with dimethylamine and ammonia is also investigated by FTICR-MS. Two series of negatively-charged clusters are investigated: [(HSO4(H2SO4x] and [(NH4x(HSO4x+1(H2SO43]. Dimethylamine substitution for ammonia in [(NH4 x(HSO4 x+1(H2SO43] clusters is nearly collision-limited, and subsequent addition of dimethylamine to neutralize H2SO4 to bisulfate is within one order of magnitude of the substitution rate. Dimethylamine addition to [(HSO4 (H2SO4 x] clusters is either not observed or very slow. The results of this study indicate that amine chemistry will be evident and important only in large ambient negative ions (>m/z 400, whereas amine chemistry may be evident in small ambient positive ions. Addition of ammonia to unneutralized clusters occurs at a rate that is ~2–3 orders of magnitude slower than incorporation of dimethylamine either by substitution or addition

  15. Sulfur cathodes with hydrogen reduced titanium dioxide inverse opal structure.

    Science.gov (United States)

    Liang, Zheng; Zheng, Guangyuan; Li, Weiyang; Seh, Zhi Wei; Yao, Hongbin; Yan, Kai; Kong, Desheng; Cui, Yi

    2014-05-27

    Sulfur is a cathode material for lithium-ion batteries with a high specific capacity of 1675 mAh/g. The rapid capacity fading, however, presents a significant challenge for the practical application of sulfur cathodes. Two major approaches that have been developed to improve the sulfur cathode performance include (a) fabricating nanostructured conductive matrix to physically encapsulate sulfur and (b) engineering chemical modification to enhance binding with polysulfides and, thus, to reduce their dissolution. Here, we report a three-dimensional (3D) electrode structure to achieve both sulfur physical encapsulation and polysulfides binding simultaneously. The electrode is based on hydrogen reduced TiO2 with an inverse opal structure that is highly conductive and robust toward electrochemical cycling. The relatively enclosed 3D structure provides an ideal architecture for sulfur and polysulfides confinement. The openings at the top surface allow sulfur infusion into the inverse opal structure. In addition, chemical tuning of the TiO2 composition through hydrogen reduction was shown to enhance the specific capacity and cyclability of the cathode. With such TiO2 encapsulated sulfur structure, the sulfur cathode could deliver a high specific capacity of ∼1100 mAh/g in the beginning, with a reversible capacity of ∼890 mAh/g after 200 cycles of charge/discharge at a C/5 rate. The Coulombic efficiency was also maintained at around 99.5% during cycling. The results showed that inverse opal structure of hydrogen reduced TiO2 represents an effective strategy in improving lithium sulfur batteries performance.

  16. Positioning of bacterial chemoreceptors.

    Science.gov (United States)

    Jones, Christopher W; Armitage, Judith P

    2015-05-01

    For optimum growth, bacteria must adapt to their environment, and one way that many species do this is by moving towards favourable conditions. To do so requires mechanisms to both physically drive movement and provide directionality to this movement. The pathways that control this directionality comprise chemoreceptors, which, along with an adaptor protein (CheW) and kinase (CheA), form large hexagonal arrays. These arrays can be formed around transmembrane receptors, resulting in arrays embedded in the inner membrane, or they can comprise soluble receptors, forming arrays in the cytoplasm. Across bacterial species, chemoreceptor arrays (both transmembrane and soluble) are localised to a variety of positions within the cell; some species with multiple arrays demonstrate this variety within individual cells. In many cases, the positioning pattern of the arrays is linked to the need for segregation of arrays between daughter cells on division, ensuring the production of chemotactically competent progeny. Multiple mechanisms have evolved to drive this segregation, including stochastic self-assembly, cellular landmarks, and the utilisation of ParA homologues. The variety of mechanisms highlights the importance of chemotaxis to motile species.

  17. Evolution of Bacterial Suicide

    Science.gov (United States)

    Tchernookov, Martin; Nemenman, Ilya

    2013-03-01

    While active, controlled cellular suicide (autolysis) in bacteria is commonly observed, it has been hard to argue that autolysis can be beneficial to an individual who commits it. We propose a theoretical model that predicts that bacterial autolysis is evolutionarily advantageous to an individualand would fixate in physically structured environments for stationary phase colonies. We perform spatially resolved agent-based simulations of the model, which predict that lower mixing in the environment results in fixation of a higher autolysis rate from a single mutated cell, regardless of the colony's genetic diversity. We argue that quorum sensing will fixate as well, even if initially rare, if it is coupled to controlling the autolysis rate. The model does not predict a strong additional competitive advantage for cells where autolysis is controlled by quorum sensing systems that distinguish self from nonself. These predictions are broadly supported by recent experimental results in B. subtilisand S. pneumoniae. Research partially supported by the James S McDonnell Foundation grant No. 220020321 and by HFSP grant No. RGY0084/2011.

  18. Electromagnetism of Bacterial Growth

    Science.gov (United States)

    Ainiwaer, Ailiyasi

    2011-10-01

    There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

  19. MATHEMATICAL SIMULATION OF THE INTERACTIONS AMONG CYANOBACTERIA, PURPLE SULFUR BACTERIA AND CHEMOTROPIC SULFUR BACTERIA IN MICROBIAL MAT COMMUNITIES

    NARCIS (Netherlands)

    DEWIT, R; VANDENENDE, FP; VANGEMERDEN, H

    1995-01-01

    A deterministic one-dimensional reaction diffusion model was constructed to simulate benthic stratification patterns and population dynamics of cyanobacteria, purple and colorless sulfur bacteria as found in marine microbial mats. The model involves the major biogeochemical processes of the sulfur c

  20. Enhanced cyclability of sulfur cathodes in lithium-sulfur batteries with Na-alginate as a binder

    Institute of Scientific and Technical Information of China (English)

    Weizhai; Bao; Zhian; Zhang; Yongqing; Gan; Xiwen; Wang; Jie; Lia

    2013-01-01

    Na-alginate as a binder in an aqueous solvent has been applied in the preparation of sulfur cathodes for lithium-sulfur batteries.Their electrochemical performances have been investigated by a charge-discharge cycle test and electrochemical impedance spectroscopy (EIS).The EIS tests indicated that the alginate sulfur cathode had lower resistance and better kinetic characteristics than those of the poly (vinylidene fluoride) (PVDF) sulfur cathode using PVDF as a binder in a N-methy-2-pyrrolidone (NMP) solvent.The charge-discharge tests showed that the discharge capacity and the capacity retention rate of Na-alginate sulfur cathode were 508 mAh·g-1and 65.4% at the 50th cycle with a current density of 335 mA·g-1.Compared with PVDF sulfur cathode,the alginate sulfur cathode showed a remarkably better cycle performance.These results show that the alginate binder has promising potential for lithium-sulfur battery applications.