Selective and Orthogonal Post-Polymerization Modification using Sulfur(VI) Fluoride Exchange (SuFEx) and Copper-Catalyzed Azide–Alkyne Cycloaddition (CuAAC) Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oakdale, James S.; Kwisnek, Luke; Fokin, Valery V.

2016-06-10

Functional polystyrenes and polyacrylamides, containing combinations of fluorosulfate, aromatic silyl ether, and azide side chains, were used as scaffolds to demonstrate the postpolymerization modification capabilities of sulfur(VI) fluoride exchange (SuFEx) and CuAAC chemistries. Fluorescent dyes bearing appropriate functional groups were sequentially attached to the backbone of the copolymers, quantitatively and selectively addressing their reactive partners. Furthermore, this combined SuFEx and CuAAC approach proved to be robust and versatile, allowing for a rare accomplishment: triple orthogonal functionalization of a copolymer under essentially ambient conditions without protecting groups.

Discovery of anaerobic lithoheterotrophic haloarchaea, ubiquitous in hypersaline habitats

PubMed Central

Sorokin, Dimitry Y; Messina, Enzo; Smedile, Francesco; Roman, Pawel; Damsté, Jaap S Sinninghe; Ciordia, Sergio; Mena, Maria Carmen; Ferrer, Manuel; Golyshin, Peter N; Kublanov, Ilya V; Samarov, Nazar I; Toshchakov, Stepan V; La Cono, Violetta; Yakimov, Michail M

2017-01-01

Hypersaline anoxic habitats harbour numerous novel uncultured archaea whose metabolic and ecological roles remain to be elucidated. Until recently, it was believed that energy generation via dissimilatory reduction of sulfur compounds is not functional at salt saturation conditions. Recent discovery of the strictly anaerobic acetotrophic Halanaeroarchaeum compels to change both this assumption and the traditional view on haloarchaea as aerobic heterotrophs. Here we report on isolation and characterization of a novel group of strictly anaerobic lithoheterotrophic haloarchaea, which we propose to classify as a new genus Halodesulfurarchaeum. Members of this previously unknown physiological group are capable of utilising formate or hydrogen as electron donors and elemental sulfur, thiosulfate or dimethylsulfoxide as electron acceptors. Using genome-wide proteomic analysis we have detected the full set of enzymes required for anaerobic respiration and analysed their substrate-specific expression. Such advanced metabolic plasticity and type of respiration, never seen before in haloarchaea, empower the wide distribution of Halodesulfurarchaeum in hypersaline inland lakes, solar salterns, lagoons and deep submarine anoxic brines. The discovery of this novel functional group of sulfur-respiring haloarchaea strengthens the evidence of their possible role in biogeochemical sulfur cycling linked to the terminal anaerobic carbon mineralisation in so far overlooked hypersaline anoxic habitats. PMID:28106880

Molecular simulation of CO2/CH4 adsorption in brown coal: Effect of oxygen-, nitrogen-, and sulfur-containing functional groups

NASA Astrophysics Data System (ADS)

Dang, Yong; Zhao, Lianming; Lu, Xiaoqing; Xu, Jing; Sang, Pengpeng; Guo, Sheng; Zhu, Houyu; Guo, Wenyue

2017-11-01

The CO2/CH4 adsorption behaviors in brown coal at the temperatures of 298, 313, and 373 K and in the pressure range of 0.005-10 MPa were investigated by molecular dynamics (MD), density functional theory (DFT), and grand canonical Monte Carlo (GCMC) simulations. The absolute adsorption isotherms of single-component CH4 and CO2 exhibit type-I Langmuir adsorption behavior showing a negative influence of temperature. For the binary CO2/CH4 mixture, brown coal shows super high selectivity of CO2 over CH4 at pressures below 0.2 MPa, which then decreases quickly and finally tends to be constant when the pressure increases. The high competitive adsorption of CO2 originates from the effects of (i) the large electrostatic contributions, (ii) the conducive micropore environment with pore sizes below 0.56 nm, and (iii) the stronger adsorption of CO2 with respect to CH4. These effects are strengthened by the high-density oxygen-containing, pyridine, and thiophene functional groups contained in brown coal, which provide abundant and strong adsorption sites for CO2, but show weaker affinity to CH4. Furthermore, the influence of various nitrogen- and sulfur-containing functional groups on the CO2 adsorption capacity was also investigated. The results indicate that the basicity of the oxygen- and nitrogen-containing groups has a large influence on the CO2 adsorption, while for the sulfur functional groups the determining factor is the polarity.

Enhanced Cycling Stability of Sulfur Electrodes through Effective Binding of Pyridine-Functionalized Polymer

DOE PAGES

Tsao, Yuchi; Chen, Zheng; Rondeau-Gagne, Simon; ...

2017-09-20

Porous carbons have previously been widely used as host materials for sulfur (S) electrodes because of their high conductivity and high surface area. However, they generally lack strong chemical affinity to stabilize polysulfide species. Therefore, conducting polymers have been employed to stabilize S electrodes. Integrating conducting polymers with high-surface-area carbons can create a new materials platform and synergize their functions. However, the previously used conducting polymers were often insoluble, and coating them uniformly from solution onto a nonpolar carbon substrate is a challenge. Here, we report that solution-processable isoindigo-based polymers incorporating polar substituents provide critical features: the conjugated backbone providesmore » good conductivity; functional pyridine groups provide high affinity to polysulfide species; and they possess high solubility in organic solvents. Here, these lead to effective coating on various carbonaceous substrates to provide highly stable sulfur electrodes. Importantly, the electrodes exhibit good capacity retention (80% over 300 cycles) at sulfur mass loading of 3.2 mg/cm 2, which significantly surpasses the performance of others reported in polymer-enabled sulfur cathodes.« less

Phylogenetic analysis of proteins associated in the four major energy metabolism systems: photosynthesis, aerobic respiration, denitrification, and sulfur respiration.

PubMed

Tomiki, Takeshi; Saitou, Naruya

2004-08-01

The four electron transfer energy metabolism systems, photosynthesis, aerobic respiration, denitrification, and sulfur respiration, are thought to be evolutionarily related because of the similarity of electron transfer patterns and the existence of some homologous proteins. How these systems have evolved is elusive. We therefore conducted a comprehensive homology search using PSI-BLAST, and phylogenetic analyses were conducted for the three homologous groups (groups 1-3) based on multiple alignments of domains defined in the Pfam database. There are five electron transfer types important for catalytic reaction in group 1, and many proteins bind molybdenum. Deletions of two domains led to loss of the function of binding molybdenum and ferredoxin, and these deletions seem to be critical for the electron transfer pattern changes in group 1. Two types of electron transfer were found in group 2, and all its member proteins bind siroheme and ferredoxin. Insertion of the pyridine nucleotide disulfide oxidoreductase domain seemed to be the critical point for the electron transfer pattern change in this group. The proteins belonging to group 3 are all flavin enzymes, and they bind flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN). Types of electron transfer in this group are divergent, but there are two common characteristics. NAD(P)H works as an electron donor or acceptor, and FAD or FMN transfers electrons from/to NAD(P)H. Electron transfer functions might be added to these common characteristics by the addition of functional domains through the evolution of group 3 proteins. Based on the phylogenetic analyses in this study and previous studies, we inferred the phylogeny of the energy metabolism systems as follows: photosynthesis (and possibly aerobic respiration) and the sulfur/nitrogen assimilation system first diverged, then the sulfur/nitrogen dissimilation system was produced from the latter system.

End-Functionalized Palladium SCS Pincer Polymers via Controlled Radical Polymerizations.

PubMed

Lye, Diane S; Cohen, Aaron E; Wong, Madeleine Z; Weck, Marcus

2017-07-01

A direct and facile route toward semitelechelic polymers, end-functionalized with palladated sulfur-carbon-sulfur pincer (Pd II -pincer) complexes is reported that avoids any post-polymerization step. Key to our methodology is the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization with functionalized chain-transfer agents. This strategy yields Pd end-group-functionalized materials with monomodal molar mass dispersities (Đ) of 1.18-1.44. The RAFT polymerization is investigated using a Pd II -pincer chain-transfer agent for three classes of monomers: styrene, tert-butyl acrylate, and N-isopropylacrylamide. The ensuing Pd II -pincer end-functionalized polymers are analyzed using 1 H NMR spectroscopy, gel-permeation chromatography, and elemental analysis. The RAFT polymerization methodology provides a direct pathway for the fabrication of Pd II -pincer functionalized polymers with complete end-group functionalization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Developing porous carbon with dihydrogen phosphate groups as sulfur host for high performance lithium sulfur batteries

NASA Astrophysics Data System (ADS)

Cui, Yanhui; Zhang, Qi; Wu, Junwei; Liang, Xiao; Baker, Andrew P.; Qu, Deyang; Zhang, Hui; Zhang, Huayu; Zhang, Xinhe

2018-02-01

Carbon matrix (CM) derived from biomass is low cost and easily mass produced, showing great potential as sulfur host for lithium sulfur batteries. In this paper we report on a dihydrogen phosphate modified CM (PCM-650) prepared from luffa sponge (luffa acutangula) by phosphoric acid treatment. The phosphoric acid not only increases the surface area of the PCM-650, but also introduces dihydrogen phosphate onto PCM-650 (2.28 at% P). Sulfur impregnated (63.6 wt%) PCM-650/S, in comparison with samples with less dihydrogen phosphate LPCM-650/S, shows a significant performance improvement. XPS analysis is conducted for sulfur at different stages, including sulfur (undischarged), polysulfides (discharge to 2.1 V) and short chain sulfides (discharge to 1.7 V). The results consistently show chemical shifts for S2p in PCM-650, suggesting an enhanced adsorption effect. Furthermore, density functional theory (DFT) calculations is used to clarify the molecular binding: carbon/sulfur (0.86 eV), carbon/Li2S (0.3 eV), CH3-O-PO3H2/sulfur (1.24 eV), and CH3-O-PO3H2/Li2S (1.81 eV). It shows that dihydrogen phosphate group can significantly enhance the binding with sulfur and sulfide, consistent with XPS results. Consequently a CM functionalised with dihydrogen phosphate shows great potential as the sulfur host in a Li-S battery.

A Novel Polar Copolymer Design as a Multi-Functional Binder for Strong Affinity of Polysulfides in Lithium-Sulfur Batteries

NASA Astrophysics Data System (ADS)

Jiao, Yu; Chen, Wei; Lei, Tianyu; Dai, Liping; Chen, Bo; Wu, Chunyang; Xiong, Jie

2017-03-01

High energy density, low cost and environmental friendliness are the advantages of lithium-sulfur (Li-S) battery which is regarded as a promising device for electrochemical energy storage systems. As one of the important ingredients in Li-S battery, the binder greatly affects the battery performance. However, the conventional binder has some drawbacks such as poor capability of absorbing hydrophilic lithium polysulfides, resulting in severe capacity decay. In this work, we reported a multi-functional polar binder (AHP) by polymerization of hexamethylene diisocyanate (HDI) with ethylenediamine (EDA) bearing a large amount of amino groups, which were successfully used in electrode preparation with commercial sulfur powder cathodes. The abundant amide groups of the binder endow the cathode with multidimensional chemical bonding interaction with sulfur species within the cathode to inhibit the shuttling effect of polysulfides, while the suitable ductility to buffer volume change. Utilizing these advantageous features, composite C/S cathodes based the binder displayed excellent capacity retention at 0.5 C, 1 C, 1.5 C, and 3 C over 200 cycles. Accompany with commercial binder, AHP may act as an alternative feedstock to open a promising approach for sulfur cathodes in rechargeable lithium battery to achieve commercial application.

Selective adsorption for removal of nitrogen compounds from hydrocarbon streams over carbon-based adsorbents

NASA Astrophysics Data System (ADS)

Almarri, Masoud S.

The ultimate goal of this thesis is to develop a fundamental understanding of the role of surface oxygen functional groups on carbon-based adsorbents in the adsorption of nitrogen compounds that are known to be present in liquid fuels. N2 adsorption was used to characterize pore structures. The surface chemical properties of the adsorbents were characterized by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques with a mass spectrometer to identify and quantify the type and concentration of oxygen functional groups on the basis of CO2 and CO evolution profiles. It was found that although surface area and pore size distribution are important for the adsorption process, they are not primary factors in the adsorption of nitrogen compounds. On the other hand, both the type and concentration of surface oxygen-containing functional groups play an important role in determining adsorptive denitrogenation performance. Higher concentrations of the oxygen functional groups on the adsorbents resulted in a higher adsorption capacity for the nitrogen compounds. A fundamental insight was gained into the contributions of different oxygen functional groups by analyzing the changes in the monolayer maximum adsorption capacity, qm, and the adsorption constant, K, for nitrogen compounds on different activated carbons. Acidic functional groups such as carboxylic acids and carboxylic anhydrides appear to contribute more to the adsorption of quinoline, while the basic oxygen functional groups such as carbonyls and quinones enhance the adsorption of indole. Despite the high number of publications on the adsorptive desulfurization of liquid hydrocarbon fuels, these studies did not consider the presence of coexisting nitrogen compounds. It is well-known that, to achieve ultraclean diesel fuel, sulfur must be reduced to a very low level, where the concentrations of nitrogen and sulfur compounds are comparable. The adsorptive denitrogenation and desulfurization of model diesel fuel, which contains equimolar concentrations of nitrogen (i.e., quinoline and indole), sulfur (i.e., dibenzothiophene and 4,6-dimethyldibenzothiophene), and aromatic compounds (naphthalene, 1-methylnaphthalene, and fluorene), was examined. The results revealed that when both nitrogen and sulfur compounds coexist in the fuel, the type and density of oxygen functional groups on the surface of the activated carbon are crucial for selective adsorption of nitrogen compounds but have negligible positive effects for sulfur removal. The adsorption of quinoline and indole is largely governed by specific interactions. There is enough evidence to support the importance of dipole--dipole and acid-base-specific interactions for the adsorption of both quinoline and indole. Modified carbon is a promising material for the efficient removal of the nitrogen compounds from light cycle oil (LCO). Adsorptive denitrogenation of LCO significantly improved the hydrodesulfurization (HDS) performance, especially for the removal of the refractory sulfur compounds such as 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. An essential factor in applying activated carbon for adsorptive denitrogenation and desulfurization of liquid hydrocarbon streams is regeneration after saturation. The regeneration method of the saturated adsorbents consisted of toluene washing followed by heating to remove the remaining toluene. The results show that the spent activated carbon can be regenerated to completely recover the adsorption capacity. The high capacity and selectivity of activated carbon for nitrogen compounds, along with their ability to be regenerated, indicate that activated carbon is a promising adsorbent for the deep denitrogenation of liquid hydrocarbon streams.

Sulfur compounds in therapy: Radiation-protective agents, amphetamines, and mucopolysaccharide sulfation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foye, W.O.

1992-09-01

Sulfur-containing compounds have been used in the search for whole-body radiation-protective compounds, in the design of amphetamine derivatives that retain appetite-suppressive effects but lack most behavioral effects characteristic of amphetamines, and in the search for the cause of kidney stone formation in recurrently stoneforming patients. Organic synthetic procedures were used to prepare radiation-protective compounds having a variety of sulfur-containing functional groups, and to prepare amphetamine derivatives having electron-attracting sulfur functions. In the case of the kidney stone causation research, isolation of urinary mucopolysaccharides (MPS) from recurrently stoneforming patients was carried out and the extent of sulfation of the MPS wasmore » determined by electrophoresis. Whole-body radiation-protective agents with a high degree of protection against lethal doses of gamma-radiation in mice were found in a series of quinolinium and pyridinium bis(methylthio) and methylthio amino derivatives. Mechanism studies showed that the copper complexes of these agents mimicked the beneficial action of superoxide dismutase. Electron-attracting sulfur-containing functions on amphetamine nitrogen, as well as 4'-amino nitrogen provided amphetamine derivatives with good appetite-suppressant effects and few or no adverse behavioral effects. Higher than normal levels of sulfation of the urinary MPS of stone formers suggested a cause for recurrent kidney stone formation. A sulfation inhibitor was found to prevent recurrence of stone formation and inhibit growth of existing stones. The inclusion of various sulfur-containing functions in organic molecules yielded compounds having whole-body radiation protection from lethal doses of gamma-radiation in animals. The presence of electron-attracting sulfur functions in amphetamine gave derivatives that retained appetite-suppressant effects and eliminated most adverse behavioral effects.« less

Improving the capacity of lithium-sulfur batteries by tailoring the polysulfide adsorption efficiency of hierarchical oxygen/nitrogen-functionalized carbon host materials.

PubMed

Schneider, Artur; Janek, Jürgen; Brezesinski, Torsten

2017-03-22

The use of monolithic carbons with structural hierarchy and varying amounts of nitrogen and oxygen functionalities as sulfur host materials in high-loading lithium-sulfur cells is reported. The primary focus is on the strength of the polysulfide/carbon interaction with the goal of assessing the effect of (surface) dopant concentration on cathode performance. The adsorption capacity - which is a measure of the interaction strength between the intermediate lithium polysulfide species and the carbon - was found to scale almost linearly with the nitrogen level. Likewise, the discharge capacity of lithium-sulfur cells increased linearly. This positive correlation can be explained by the favorable effect of nitrogen on both the chemical and electronic properties of the carbon host. The incorporation of additional oxygen-containing surface groups into highly nitrogen-functionalized carbon helped to further enhance the polysulfide adsorption efficiency, and therefore the reversible cell capacity. Overall, the areal capacity could be increased by almost 70% to around 3 mA h cm -2 . We believe that the design parameters described here provide a blueprint for future carbon-based nanocomposites for high-performance lithium-sulfur cells.

Computational screening of functional groups for capture of toxic industrial chemicals in porous materials.

PubMed

Kim, Ki Chul; Fairen-Jimenez, David; Snurr, Randall Q

2017-12-06

A thermodynamic analysis using quantum chemical methods was carried out to identify optimal functional group candidates that can be included in metal-organic frameworks and activated carbons for the selective capture of toxic industrial chemicals (TICs) in humid air. We calculated the binding energies of 14 critical TICs plus water with a series of 10 functional groups attached to a naphthalene ring model. Using vibrational calculations, the free energies of adsorption were calculated in addition to the binding energies. Our results show that, in these systems, the binding energies and free energies follow similar trends. We identified copper(i) carboxylate as the optimal functional group (among those studied) for the selective binding of the majority of the TICs in humid air, and this functional group exhibits especially strong binding for sulfuric acid. Further thermodynamic analysis shows that the presence of water weakens the binding strength of sulfuric acid with the copper carboxylate group. Our calculations predict that functionalization of aromatic rings would be detrimental to selective capture of COCl 2 , CO 2 , and Cl 2 under humid conditions. Finally, we found that forming an ionic complex, H 3 O + HSO 4 - , between H 2 SO 4 and H 2 O via proton transfer is not favorable on copper carboxylate.

Synthesis, characterization of dihydrolipoic acid capped gold nanoparticles, and functionalization by the electroluminescent luminol.

PubMed

Roux, Stéphane; Garcia, Bruno; Bridot, Jean-Luc; Salomé, Murielle; Marquette, Christophe; Lemelle, Laurence; Gillet, Phillipe; Blum, Loïc; Perriat, Pascal; Tillement, Olivier

2005-03-15

The use of gold nanoparticles as biological probes requires the improvement of colloidal stability. Dihydrolipoic acid (DHLA), a dithiol obtained by the reduction of thioctic acid, appears therefore very attractive for the stabilization and the further functionalization of gold nanoparticles because DHLA is characterized by a carboxylic acid group and two thiol functions. The ionizable carboxylic acid groups ensure, for pH > or = 8, the water solubility of DHLA-capped gold (Au@DHLA) nanoparticles, prepared by the Brust protocol, and the stability of the resulting colloid by electrostatic repulsions. Moreover almost all DHLA, adsorbed onto gold, adopts a conformation allowing their immobilization by both sulfur ends. It is proved by sulfur K-edge X-ray absorption near edge structure spectroscopy, which appears as an appropriate tool for determining the chemical form of sulfur atoms present in the organic monolayer. Such a grafting renders the DHLA monolayers more resistant to displacement by dithiothreitol than mercaptoundecanoic acid monolayers. The presence of DHLA on gold particles allows their functionalization by the electroluminescent luminol through amine coupling reactions assisted by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. As a luminol-functionalized particle is nine times as bright as a single luminol molecule, the use of the particles as a biological probe with a lower threshold of detection is envisaged.

The Relative Abundance and Transcriptional Activity of Marine Sponge-Associated Microorganisms Emphasizing Groups Involved in Sulfur Cycle.

PubMed

Jensen, Sigmund; Fortunato, Sofia A V; Hoffmann, Friederike; Hoem, Solveig; Rapp, Hans Tore; Øvreås, Lise; Torsvik, Vigdis L

2017-04-01

During the last decades, our knowledge about the activity of sponge-associated microorganisms and their contribution to biogeochemical cycling has gradually increased. Functional groups involved in carbon and nitrogen metabolism are well documented, whereas knowledge about microorganisms involved in the sulfur cycle is still limited. Both sulfate reduction and sulfide oxidation has been detected in the cold water sponge Geodia barretti from Korsfjord in Norway, and with specimens from this site, the present study aims to identify extant versus active sponge-associated microbiota with focus on sulfur metabolism. Comparative analysis of small subunit ribosomal RNA (16S rRNA) gene (DNA) and transcript (complementary DNA (cDNA)) libraries revealed profound differences. The transcript library was predominated by Chloroflexi despite their low abundance in the gene library. An opposite result was found for Acidobacteria. Proteobacteria were detected in both libraries with representatives of the Alpha- and Gammaproteobacteria related to clades with presumably thiotrophic bacteria from sponges and other marine invertebrates. Sequences that clustered with sponge-associated Deltaproteobacteria were remotely related to cultivated sulfate-reducing bacteria. The microbes involved in sulfur cycling were identified by the functional gene aprA (adenosine-5'-phosphosulfate reductase) and its transcript. Of the aprA sequences (DNA and cDNA), 87 % affiliated with sulfur-oxidizing bacteria. They clustered with Alphaproteobacteria and with clades of deep-branching Gammaproteobacteria. The remaining sequences clustered with sulfate-reducing Archaea of the phylum Euryarchaeota. These results indicate an active role of yet uncharacterized Bacteria and Archaea in the sponge's sulfur cycle.

Diverse Mechanisms of Sulfur Decoration in Bacterial tRNA and Their Cellular Functions

PubMed Central

Zheng, Chenkang; Black, Katherine A.; Dos Santos, Patricia C.

2017-01-01

Sulfur-containing transfer ribonucleic acids (tRNAs) are ubiquitous biomolecules found in all organisms that possess a variety of functions. For decades, their roles in processes such as translation, structural stability, and cellular protection have been elucidated and appreciated. These thionucleosides are found in all types of bacteria; however, their biosynthetic pathways are distinct among different groups of bacteria. Considering that many of the thio-tRNA biosynthetic enzymes are absent in Gram-positive bacteria, recent studies have addressed how sulfur trafficking is regulated in these prokaryotic species. Interestingly, a novel proposal has been given for interplay among thionucleosides and the biosynthesis of other thiocofactors, through participation of shared-enzyme intermediates, the functions of which are impacted by the availability of substrate as well as metabolic demand of thiocofactors. This review describes the occurrence of thio-modifications in bacterial tRNA and current methods for detection of these modifications that have enabled studies on the biosynthesis and functions of S-containing tRNA across bacteria. It provides insight into potential modes of regulation and potential evolutionary events responsible for divergence in sulfur metabolism among prokaryotes. PMID:28327539

Heavy metal absorbing Thioether-functionalized ligands derived from vegetable oils

USDA-ARS?s Scientific Manuscript database

Sulfur-functionalized vegetable oils containing thioether groups have been shown to effectively remove Ag+ from aqueous solution. Interestingly, the absorption capacity differs depending upon the choice of which vegetable oil precursor is functionalized. In this study, we will provide data for oils ...

Conducting Polymers Crosslinked with Sulfur as Cathode Materials for High-Rate, Ultralong-Life Lithium-Sulfur Batteries.

PubMed

Zeng, Shuaibo; Li, Ligui; Xie, Lihong; Zhao, Dengke; Wang, Nan; Chen, Shaowei

2017-09-11

Low electrical conductivity and a lack of chemical confinement are two major factors that limit the rate performances and cycling stabilities of cathode materials in lithium-sulfur (Li-S) batteries. Herein, sulfur is copolymerized with poly(m-aminothiophenol) (PMAT) nanoplates through inverse vulcanization to form the highly crosslinked copolymer cp(S-PMAT) in which approximately 80 wt % of the feed sulfur is bonded chemically to the thiol groups of PMAT. A cp(S-PMAT)/C-based cathode exhibits a high discharge capacity of 1240 mAh g -1 at 0.1 C and remarkable rate capacities of 880 mAh g -1 at 1 C and 600 mAh g -1 at 5 C. Moreover, it can retain a capacity of 495 mAh g -1 after 1000 deep discharge-charge cycles at 2 C; this corresponds to a retention of 66.9 % and a decay rate of only 0.040 % per cycle. Such a remarkable rate performance is attributed to the highly conductive pathways of PMAT nanoplates, and the excellent cycling stability is ascribed mainly to the chemical confinement of sulfur through a large number of stable covalent bonds between sulfur and the thiol groups of PMAT. The results suggest that this strategy is a viable paradigm for the design and engineering of conducting polymers with reactive functional groups as effective electrode materials for high-performance Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Whole-genome sequencing reveals novel insights into sulfur oxidation in the extremophile Acidithiobacillus thiooxidans.

PubMed

Yin, Huaqun; Zhang, Xian; Li, Xiaoqi; He, Zhili; Liang, Yili; Guo, Xue; Hu, Qi; Xiao, Yunhua; Cong, Jing; Ma, Liyuan; Niu, Jiaojiao; Liu, Xueduan

2014-07-04

Acidithiobacillus thiooxidans (A. thiooxidans), a chemolithoautotrophic extremophile, is widely used in the industrial recovery of copper (bioleaching or biomining). The organism grows and survives by autotrophically utilizing energy derived from the oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs). However, the lack of genetic manipulation systems has restricted our exploration of its physiology. With the development of high-throughput sequencing technology, the whole genome sequence analysis of A. thiooxidans has allowed preliminary models to be built for genes/enzymes involved in key energy pathways like sulfur oxidation. The genome of A. thiooxidans A01 was sequenced and annotated. It contains key sulfur oxidation enzymes involved in the oxidation of elemental sulfur and RISCs, such as sulfur dioxygenase (SDO), sulfide quinone reductase (SQR), thiosulfate:quinone oxidoreductase (TQO), tetrathionate hydrolase (TetH), sulfur oxidizing protein (Sox) system and their associated electron transport components. Also, the sulfur oxygenase reductase (SOR) gene was detected in the draft genome sequence of A. thiooxidans A01, and multiple sequence alignment was performed to explore the function of groups of related protein sequences. In addition, another putative pathway was found in the cytoplasm of A. thiooxidans, which catalyzes sulfite to sulfate as the final product by phosphoadenosine phosphosulfate (PAPS) reductase and adenylylsulfate (APS) kinase. This differs from its closest relative Acidithiobacillus caldus, which is performed by sulfate adenylyltransferase (SAT). Furthermore, real-time quantitative PCR analysis showed that most of sulfur oxidation genes were more strongly expressed in the S0 medium than that in the Na2S2O3 medium at the mid-log phase. Sulfur oxidation model of A. thiooxidans A01 has been constructed based on previous studies from other sulfur oxidizing strains and its genome sequence analyses, providing insights into our understanding of its physiology and further analysis of potential functions of key sulfur oxidation genes.

Whole-genome sequencing reveals novel insights into sulfur oxidation in the extremophile Acidithiobacillus thiooxidans

PubMed Central

2014-01-01

Background Acidithiobacillus thiooxidans (A. thiooxidans), a chemolithoautotrophic extremophile, is widely used in the industrial recovery of copper (bioleaching or biomining). The organism grows and survives by autotrophically utilizing energy derived from the oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs). However, the lack of genetic manipulation systems has restricted our exploration of its physiology. With the development of high-throughput sequencing technology, the whole genome sequence analysis of A. thiooxidans has allowed preliminary models to be built for genes/enzymes involved in key energy pathways like sulfur oxidation. Results The genome of A. thiooxidans A01 was sequenced and annotated. It contains key sulfur oxidation enzymes involved in the oxidation of elemental sulfur and RISCs, such as sulfur dioxygenase (SDO), sulfide quinone reductase (SQR), thiosulfate:quinone oxidoreductase (TQO), tetrathionate hydrolase (TetH), sulfur oxidizing protein (Sox) system and their associated electron transport components. Also, the sulfur oxygenase reductase (SOR) gene was detected in the draft genome sequence of A. thiooxidans A01, and multiple sequence alignment was performed to explore the function of groups of related protein sequences. In addition, another putative pathway was found in the cytoplasm of A. thiooxidans, which catalyzes sulfite to sulfate as the final product by phosphoadenosine phosphosulfate (PAPS) reductase and adenylylsulfate (APS) kinase. This differs from its closest relative Acidithiobacillus caldus, which is performed by sulfate adenylyltransferase (SAT). Furthermore, real-time quantitative PCR analysis showed that most of sulfur oxidation genes were more strongly expressed in the S0 medium than that in the Na2S2O3 medium at the mid-log phase. Conclusion Sulfur oxidation model of A. thiooxidans A01 has been constructed based on previous studies from other sulfur oxidizing strains and its genome sequence analyses, providing insights into our understanding of its physiology and further analysis of potential functions of key sulfur oxidation genes. PMID:24993543

Surface characterization studies of walnut-shell biochar catalysts for simultaneously removing of organic sulfur from yellow phosphorus tail gas

NASA Astrophysics Data System (ADS)

Song, Xin; Li, Kai; Ning, Ping; Wang, Chi; Sun, Xin; Tang, Lihong; Ruan, Haotian; Han, Shuang

2017-12-01

The influences of different preparation conditions for surface characteristics on removing organic sulfur were studied. From BET, XRD, FTIR, DRIFTS, TG/DTA, CO2-TPD results, it can be seen that these preparation conditions had great influences on the pore structure, specific surface area, crystal structure and surface functional groups. The micropore volume, amorphous structure and alkalinity site strength played major roles in desulfurization process. H2S was oxidized by oxygen containing functional groups, such as sbnd COO, sbnd Cdbnd O. H2O molecule could be converted into some groups, such as sbnd CH and Csbnd OH groups, and promoted the hydrolysis reaction. The strong alkalinity site was the key factor for chemical adsorption and hydrolysis. H2O molecule, sbnd CH, Csbnd OH groups promoted the hydrolysis reaction and sbnd COO, sbnd Cdbnd O groups promoted the oxidation of H2S on the surface of WSB. Meanwhile, the main desulfurization process over WSB after carbonization was adsorption and it changed to hydrolysis reaction after activation on the surface of WSB. Furthermore, the reaction mechanism was investigated by DRIFTS measurement according to the change of surface functional groups.

A hierarchical architecture S/MWCNT nanomicrosphere with large pores for lithium sulfur batteries.

PubMed

Chen, Jia-jia; Zhang, Qian; Shi, Yi-ning; Qin, Lin-lin; Cao, Yong; Zheng, Ming-sen; Dong, Quan-feng

2012-04-28

A hierarchical S/MWCNT nanomicrosphere for lithium/sulfur batteries with a high power and energy density as well as an excellent cycle life is introduced. Sulfur was uniformly coated on the surface of functional MWCNTs, which serves as a carbon matrix, to form a typical nanoscale core-shell structure with a sulfur layer of thickness 10-20 nm. Then the nanoscale sulfur intermediate composite was ball-milled to form interwoven and porous sphere architecture with large pores (around 1 μm to 5 μm). Different from most sulfur/carbon materials with micropore and mesopore structure, the micrometre scale S/MWCNT nanomicrosphere with a large pore structure could also exhibit high sulfur utilization and cycle retention. It could maintain a reversible capacity of 1000 mA h g(-1) after 100 cycles at 0.3 A g(-1) current density. And it even remained 780 mA h g(-1) after 200 cycles at 0.5 A g(-1) and 650 mA h g(-1) after 200 cycles at 1 A g(-1), showing a significant cyclability enhancement. It is believed that under the collective effect of hierarchical architecture, as well as the existence of carboxyl functional groups, sulfur/carbon materials with large pores could also exhibit an excellent electrochemical performance. The synthesis process introduced here is simple and broadly applicable, which would not only be beneficial to design new materials for lithium sulfur batteries but can also be extended to many different electrode materials for lithium ion batteries. This journal is © the Owner Societies 2012

The effects of inhaled sulfuric acid on pulmonary function in adolescent asthmatics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koenig, J.Q.; Pierson, W.E.; Horike, M.

Ten adolescent subjects with extrinsic asthma and exercise-induced bronchospasm were studied. The subjects were exposed for 30 min at rest followed by 10 min during moderate exercise on a treadmill to either 100 micrograms/m3 sodium chloride (NaCl) or 100 micrograms/m3 sulfuric acid (H/sub 2/SO/sub 4/) droplet aerosols. All exposures were at approximately 75% relative humidity and 22 degrees C. Pulmonary functional measurements were recorded before, during, and after exposure while the subject was seated in a body plethysmograph. Exposure to the NaCl aerosol during exercise produced a small (12%) but significant drop in maximal expiratory flow (V/sub max/75) (p lessmore » than 0.05). However, exposure to the H/sub 2/SO/sub 4/ aerosol produced larger reductions in V/sub max/75 (29%; p less than 0.01) and also significant changes in 3 other parameters of pulmonary function: V/sub max/50, FEV1, and total respiratory resistance (RT). The changes were similar to those reported for exposure to 0.5 ppm of sulfur dioxide in a similar group of adolescents with extrinsic asthma. Our results are the first report of reversible pulmonary functional changes after H/sub 2/SO/sub 4/ exposure in a group of adolescent asthmatic subjects.« less

Nucleophilic substitution between polysulfides and binders unexpectedly stabilizing lithium sulfur battery

DOE PAGES

Ling, Min; Zhang, Liang; Zheng, Tianyue; ...

2017-05-10

Polysulfide shuttling has been the primary cause of failure in lithium-sulfur (Li-S) battery cycling. In this paper, we demonstrate an nucleophilic substitution reaction between polysulfides and binder functional groups can unexpectedly immobilizes the polysulfides. The substitution reaction is verified by UV–visible spectra and X-ray photoelectron spectra. The immobilization of polysulfide is in situ monitored by synchrotron based sulfur K-edge X-ray absorption spectra. The resulting electrodes exhibit initial capacity up to 20.4 mAh/cm 2, corresponding to 1199.1 mAh/g based on a micron-sulfur mass loading of 17.0 mg/cm 2. The micron size sulfur transformed into nano layer coating on the cathode bindermore » during cycling. Directly usage of nano-size sulfur promotes higher capacity of 33.7 mAh/cm 2, which is the highest areal capacity reported in Li-S battery. Finally, this enhance performance is due to the reduced shuttle effect by covalently binding of the polysulfide with the polymer binder.« less

Nucleophilic substitution between polysulfides and binders unexpectedly stabilizing lithium sulfur battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ling, Min; Zhang, Liang; Zheng, Tianyue

Polysulfide shuttling has been the primary cause of failure in lithium-sulfur (Li-S) battery cycling. In this paper, we demonstrate an nucleophilic substitution reaction between polysulfides and binder functional groups can unexpectedly immobilizes the polysulfides. The substitution reaction is verified by UV–visible spectra and X-ray photoelectron spectra. The immobilization of polysulfide is in situ monitored by synchrotron based sulfur K-edge X-ray absorption spectra. The resulting electrodes exhibit initial capacity up to 20.4 mAh/cm 2, corresponding to 1199.1 mAh/g based on a micron-sulfur mass loading of 17.0 mg/cm 2. The micron size sulfur transformed into nano layer coating on the cathode bindermore » during cycling. Directly usage of nano-size sulfur promotes higher capacity of 33.7 mAh/cm 2, which is the highest areal capacity reported in Li-S battery. Finally, this enhance performance is due to the reduced shuttle effect by covalently binding of the polysulfide with the polymer binder.« less

Encapsulation of sulfur with thin-layered nickel-based hydroxides for long-cyclic lithium–sulfur cells

PubMed Central

Jiang, Jian; Zhu, Jianhui; Ai, Wei; Wang, Xiuli; Wang, Yanlong; Zou, Chenji; Huang, Wei; Yu, Ting

2015-01-01

Elemental sulfur cathodes for lithium/sulfur cells are still in the stage of intensive research due to their unsatisfactory capacity retention and cyclability. The undesired capacity degradation upon cycling originates from gradual diffusion of lithium polysulfides out of the cathode region. To prevent losses of certain intermediate soluble species and extend lifespan of cells, the effective encapsulation of sulfur plays a critical role. Here we report an applicable way, by using thin-layered nickel-based hydroxide as a feasible and effective encapsulation material. In addition to being a durable physical barrier, such hydroxide thin films can irreversibly react with lithium to generate protective layers that combine good ionic permeability and abundant functional polar/hydrophilic groups, leading to drastic improvements in cell behaviours (almost 100% coulombic efficiency and negligible capacity decay within total 500 cycles). Our present encapsulation strategy and understanding of hydroxide working mechanisms may advance progress on the development of lithium/sulfur cells for practical use. PMID:26470847

Development of cost-effective noncarbon sorbents for Hg(0) removal from coal-fired power plants.

PubMed

Lee, Joo-Youp; Ju, Yuhong; Keener, Tim C; Varma, Rajender S

2006-04-15

Noncarbonaceous materials or mineral oxides (silica gel, alumina, molecular sieves, zeolites, and montmorillonite) were modified with various functional groups such as amine, amide, thiol, urea, and active additives such as elemental sulfur, sodium sulfide, and sodium polysulfide to examine their potential as sorbents for the removal of elemental mercury (Hg(0)) vapor at coal-fired utility power plants. A number of sorbent candidates such as amine- silica gel, urea- silica gel, thiol- silica gel, amide-silica gel, sulfur-alumina, sulfur-molecular sieve, sulfur-montmorillonite, sodium sulfide-montmorillonite, and sodium polysulfide-montmorillonite, were synthesized and tested in a lab-scale fixed-bed system under an argon flow for screening purposes at 70 degrees C and/or 140 degrees C. Several functionalized silica materials reported in previous studies to effectively control heavy metals in the aqueous phase showed insignificant adsorption capacities for Hg(0) control in the gas phase, suggesting that mercury removal mechanisms in both phases are different. Among elemental sulfur-, sodium sulfide-, and sodium polysulfide-impregnated inorganic samples, sodium polysulfide-impregnated montmorillonite K 10 showed a moderate adsorption capacity at 70 degrees C, which can be used for sorbent injection prior to the wet FGD system.

A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries.

PubMed

Lacey, Matthew J; Österlund, Viking; Bergfelt, Andreas; Jeschull, Fabian; Bowden, Tim; Brandell, Daniel

2017-07-10

We report here a water-based functional binder framework for the lithium-sulfur battery systems, based on the general combination of a polyether and an amide-containing polymer. These binders are applied to positive electrodes optimised towards high-energy electrochemical performance based only on commercially available materials. Electrodes with up to 4 mAh cm -2 capacity and 97-98 % coulombic efficiency are achievable in electrodes with a 65 % total sulfur content and a poly(ethylene oxide):poly(vinylpyrrolidone) (PEO:PVP) binder system. Exchange of either binder component for a different polymer with similar functionality preserves the high capacity and coulombic efficiency. The improvement in coulombic efficiency from the inclusion of the coordinating amide group was also observed in electrodes where pyrrolidone moieties were covalently grafted to the carbon black, indicating the role of this functionality in facilitating polysulfide adsorption to the electrode surface. The mechanical properties of the electrodes appear not to significantly influence sulfur utilisation or coulombic efficiency in the short term but rather determine retention of these properties over extended cycling. These results demonstrate the robustness of this very straightforward approach, as well as the considerable scope for designing binder materials with targeted properties. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Domain Evolution and Functional Diversification of Sulfite Reductases

NASA Astrophysics Data System (ADS)

Dhillon, Ashita; Goswami, Sulip; Riley, Monica; Teske, Andreas; Sogin, Mitchell

2005-02-01

Sulfite reductases are key enzymes of assimilatory and dissimilatory sulfur metabolism, which occur in diverse bacterial and archaeal lineages. They share a highly conserved domain "C-X5-C-n-C-X3-C" for binding siroheme and iron-sulfur clusters that facilitate electron transfer to the substrate. For each sulfite reductase cluster, the siroheme-binding domain is positioned slightly differently at the N-terminus of dsrA and dsrB, while in the assimilatory proteins the siroheme domain is located at the C-terminus. Our sequence and phylogenetic analysis of the siroheme-binding domain shows that sulfite reductase sequences diverged from a common ancestor into four separate clusters (aSir, alSir, dsr, and asrC) that are biochemically distinct; each serves a different assimilatory or dissimilatory role in sulfur metabolism. The phylogenetic distribution and functional grouping in sulfite reductase clusters (dsrA and dsrB vs. aSiR, asrC, and alSir) suggest that their functional diversification during evolution may have preceded the bacterial/archaeal divergence.

In situ S-K XANES study of polymer electrolyte fuel cells: changes in the chemical states of sulfonic groups depending on humidity.

PubMed

Isegawa, Kazuhisa; Nagami, Tetsuo; Jomori, Shinji; Yoshida, Masaaki; Kondoh, Hiroshi

2016-09-14

Changes in the chemical states of sulfonic groups of Nafion in polymer electrolyte fuel cells (PEFCs) under gas-flowing conditions were studied using in situ S-K XANES spectroscopy. The applied potential to the electrodes and the humidity of the cell were changed under flowing H 2 gas in the anode and He gas in the cathode. While the potential shows no significant effect on the S-K XANES spectra, the humidity is found to induce reversible changes in the spectra. Comparison of the spectral changes with simulations based on the density functional theory calculations indicates that the humidity influences the chemical state of the sulfonic group; under wet conditions the sulfonic group is in the form of a sulfonate ion. By drying treatment the sulfonate ion binds to hydrogen and becomes sulfonic acid. Furthermore, a small fraction of the sulfonic acid irreversibly decomposes to atomic sulfur. The peak energy of the atomic sulfur suggests that the generated atomic sulfur is adsorbed on the Pt catalyst surfaces.

The diversity of the effects of sulfur mustard gas inhalation on respiratory system 10 years after a single, heavy exposure: analysis of 197 cases.

PubMed

Emad, A; Rezaian, G R

1997-09-01

To find out the late pulmonary sequelae of sulfur mustard gas inhalation in 197 veterans, 10 years after their exposure. Cross-sectional clinical study. University hospital. One hundred ninety-seven veterans with a single, heavy exposure to sulfur mustard gas in 1986 and 86 nonexposed veterans as their control group. Pulmonary function tests, carbon monoxide diffusion capacity, bronchoscopy, and high-resolution CT of the chest were performed in all patients. Transbronchial lung biopsy was done in 24 suspected cases of pulmonary fibrosis. Asthma was diagnosed in 21 (10.65%), chronic bronchitis in 116 (58.88%), bronchiectasis in 17 (8.62%), airway narrowing due to searing or granulation tissue in 19 (9.64%), and pulmonary fibrosis in 24 (12.18%) cases. None of these were found among the control group except for a single case of chronic bronchitis. Although the respiratory symptoms of an acute sulfur mustard gas inhalation are usually transient and nonspecific, it can lead to the development of a series of chronic destructive pulmonary sequelae in such cases.

Theoretical study of interactions between cysteine and perfluoropropanoic acid in gas and aqueous phase

NASA Astrophysics Data System (ADS)

Holmes, Tiffani M.; Doskocz, Jacek; Wright, Terrance; Hill, Glake A.

The interaction of perfluoropropanoic acid (PFPA) with the amino acid cysteine was investigated using density functional theory. Previous studies suggest that the peroxisome proliferator chemical, perfluorooctanoic acid, is circulated throughout the body by way of sulfur-containing amino acids. We present conformational analysis of the interactions of PFPA, a small model of perfluorooctanoic acid, with the sulfur-containing amino acid which occur by the process of hydrogen bonding, in which the hydrogen of the sulfhydryl group interacts with the carboxyl oxygen, and the amino nitrogen forms a hydrogen bond with the hydrogen of the bond OH group of the fluorinated alkyl. We also show in our structures a recently characterized weak nonbonded interaction between divalent sulfur and a main chain carboxyl oxygen in proteins. B3LYP calculated free energies and interaction energies predict low-energy, high-interaction conformations for complex systems of perfluorinated fatty acid interactions with cysteine.

Functionalized graphene-based cathode for highly reversible lithium-sulfur batteries.

PubMed

Kim, Jin Won; Ocon, Joey D; Park, Dong-Won; Lee, Jaeyoung

2014-05-01

In this article, we highlight the salient issues in the development of lithium-sulfur battery (LSB) cathodes, present different points of view in solving them, and argue, why in the future, functionalized graphene or graphene oxide might be the ultimate solution towards LSB commercialization. As shown by previous studies and also in our recent work, functionalized graphene and graphene oxide enhance the reversibility of the charge-discharge process by trapping polysulfides in the oxygen functional groups on the graphene surface, thus minimizing polysulfide dissolution. This will be helpful for the rational design of new cathode structures based on graphene for LSBs with minimal capacity fading, low extra cost, and without the unnecessary weight increase caused by metal/metal oxide additives. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Grafted functional groups on expanded tetrafluoroethylene (ePTFE) support for fuel cell and water transport membranes

DOEpatents

Fuller, Timothy J.; Jiang, Ruichun

2017-01-24

A method for forming a modified solid polymer includes a step of contacting a solid fluorinated polymer with a sodium sodium-naphthalenide solution to form a treated fluorinated solid polymer. The treated fluorinated solid polymer is contacted with carbon dioxide, sulfur dioxide, or sulfur trioxide to form a solid grafted fluorinated polymer. Characteristically, the grafted fluorinated polymer includes appended CO.sub.2H or SO.sub.2H or SO.sub.3H groups. The solid grafted fluorinated polymer is advantageously incorporated into a fuel cell as part of the ion-conducting membrane or a water transport membrane in a humidifier.

Asymmetric intramolecular Pauson-Khand reaction mediated by a remote sulfenyl or sulfinyl group.

PubMed

García Ruano, José Luis; Torrente, Esther; Parra, Alejandro; Alemán, José; Martín-Castro, Ana M

2012-08-03

In this work, we report the use of the asymmetric intramolecular Pauson-Khand reactions of 4-aryl-4-cyano-1,6-enynes for obtaining enantiomerically enriched bicyclo[3.3.0]octenones, and the influence of both the quaternary stereocenter and the sulfur functions located at ortho-position of the aryl group, on their stereoselectivity and reactivity. The sulfenyl derivatives bearing substituted or unsubstituted triple bonds and mono- and disubstituted alkene moieties afford bicyclo[3.3.0]octenones in high yields with complete diastereocontrol. These results are explained by assuming the association of the lone electron pair at sulfur to the Co-alkyne complexes.

Performance study of magnesium-sulfur battery using a graphene based sulfur composite cathode electrode and a non-nucleophilic Mg electrolyte.

PubMed

Vinayan, B P; Zhao-Karger, Zhirong; Diemant, Thomas; Chakravadhanula, Venkata Sai Kiran; Schwarzburger, Nele I; Cambaz, Musa Ali; Behm, R Jürgen; Kübel, Christian; Fichtner, Maximilian

2016-02-14

Here we report for the first time the development of a Mg rechargeable battery using a graphene-sulfur nanocomposite as the cathode, a Mg-carbon composite as the anode and a non-nucleophilic Mg based complex in tetraglyme solvent as the electrolyte. The graphene-sulfur nanocomposites are prepared through a new pathway by the combination of thermal and chemical precipitation methods. The Mg/S cell delivers a higher reversible capacity (448 mA h g(-1)), a longer cyclability (236 mA h g(-1) at the end of the 50(th) cycle) and a better rate capability than previously described cells. The dissolution of Mg polysulfides to the anode side was studied by X-ray photoelectron spectroscopy. The use of a graphene-sulfur composite cathode electrode, with the properties of a high surface area, a porous morphology, a very good electronic conductivity and the presence of oxygen functional groups, along with a non-nucleophilic Mg electrolyte gives an improved battery performance.

Longitudinal study of children exposed to sulfur oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodge, R.; Solomon, P.; Moyers, J.

1985-05-01

This study is a longitudinal comparison of the health of children exposed to markedly different concentrations of sulfur dioxide and moderately different concentrations of particulate sulfate. The four groups of subjects lived in two areas of one smelter town and in two other towns, one of which was also a smelter town. In the area of highest pollution, children were intermittently exposed to high SO/sub 2/ levels (peak three-hour average concentration exceeded 2,500 micrograms/m3) and moderate particulate SO/sub 4/= levels (average concentration was 10.1 micrograms/m3). When the children were grouped by the four gradients of pollution observed, the prevalence ofmore » cough (measured by questionnaire) correlated significantly with pollution levels (trend chi-square = 5.6, p = 0.02). No significant differences in the incidence of cough or other symptoms occurred among the groups of subjects over three years, and pulmonary function and lung function growth over the study were roughly equal among all the groups. These results suggest that intermittent elevations in SO/sub 2/ concentration, in the presence of moderate particulate SO/sub 4/= concentration, produced evidence of bronchial irritation in the subjects, but no chronic effect on lung function or lung function growth was detected.« less

Impact of Sulfuric Acid Treatment of Halloysite on Physico-Chemic Property Modification.

PubMed

Gaaz, Tayser Sumer; Sulong, Abu Bakar; Kadhum, Abdul Amir H; Nassir, Mohamed H; Al-Amiery, Ahmed A

2016-07-26

Halloysite (HNT) is treated with sulfuric acid and the physico-chemical properties of its morphology, surface activity, physical and chemical properties have been investigated when HNT is exposed to sulfuric acid with treatment periods of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21). The significance of this and similar work lies in the importance of using HNT as a functional material in nanocomposites. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The spectrum demonstrates that the hydroxyl groups were active for grafting modification using sulfuric acid, promoting a promising potential use for halloysite in ceramic applications as filler for novel clay-polymer nanocomposites. From the X-ray diffraction (XRD) spectrum, it can be seen that the sulfuric acid breaks down the HNT crystal structure and alters it into amorphous silica. In addition, the FESEM images reveal that the sulfuric acid treatment dissolves the AlO₆ octahedral layers and induces the disintegration of SiO₄ tetrahedral layers, resulting in porous nanorods. The Bruncher-Emmett-Teller (BET) surface area and total pore volume of HNTs showed an increase. The reaction of the acid with both the outer and inner surfaces of the nanotubes causes the AlO₆ octahedral layers to dissolve, which leads to the breakdown and collapse of the tetrahedral layers of SiO₄. The multi-fold results presented in this paper serve as a guide for further HNT functional treatment for producing new and advanced nanocomposites.

A three-dimensional cathode matrix with bi-confinement effect of polysulfide for lithium-sulfur battery

NASA Astrophysics Data System (ADS)

Song, Ren-Sheng; Wang, Bo; Ruan, Ting-Ting; Wang, Lei; Luo, Hao; Wang, Fei; Gao, Tian-Tian; Wang, Dian-Long

2018-01-01

Soluble polysulfide shuttling is still the main cause of restricting the development of lithium-sulfur (Li-S) battery. Here, we propose a novel three-dimensional reduced graphene oxide@sulfur/nitrogen-doped porous carbon polyhedron/carbon nanotubes (rGO@S/NCP/CNTs) composite with bi-confinement effect of polysulfide as an effective cathode material. In rGO@S/NCP/CNTs, NCP provides physical confinement for sulfur and soluble polysulfide by its abundant micropores and mesopores, while oxygen functional groups of rGO provide strong chemical confinement to soluble polysulfide. Additionally, CNTs with one-dimensional conductivity enable facile transport of electrons. Therefore, the resulting rGO@S/NCP/CNTs composite shows an obvious enhancement in cycling performance for Li-S battery, and reversible capacities up to 738 mAh g-1 and 660 mAh g-1 over 100 and 200 cycles are remained at 0.2 C rate.

Organic Sulfur Associated with Aquatic Humic Substances

NASA Astrophysics Data System (ADS)

Aiken, G.; Vairavamurthy, M. A.; Ravichandran, M.

2003-12-01

This study examines the speciation and reactivity of organic sulfur associated with dissolved organic matter isolated from a variety of freshwater environments and the Pacific Ocean. The isolates, which included aquatic humic substances, were obtained using XAD resins and exhibited a wide range of elemental compositions, aromatic carbon contents, and molecular weights. Organic sulfur contents for the samples ranged from 0.4% to 1.9% of the atomic composition and were strongly dependent on the redox chemistry of the environments whence the samples originated, especially with regard to potential interactions with sulfide in sulfate reducing environments. The speciation of the sulfur associated with these samples was investigated using X-ray adsorption near edge spectroscopy (XANES). The samples, all obtained from oxic environments, contained reduced sulfur moieties. Reduced sulfur content (thiophene, organic sulfides and thiols) ranged from 22-70%. In general, humic acid fractions were found to have the largest percentage of reduced sulfur, followed by the fulvic acid and hydrophobic acid fractions. Hydrophilic fractions of the DOC contained a large percentage of oxidized organic sulfur (sulfonate and sulfate moieties). To assess the significance of reduced S content on interactions with soft metals, an environmentally significant process, the binding strength and binding capacity of Hg with organic matter isolated from the Florida Everglades were determined using equilibrium dialysis ligand exchange. Based on elemental analyses and XANES, the DOM sample from the Everglades used in our binding experiments had a reduced-S content of approximately 1.0%. Very strong interactions (KDOM' = 1023.2+/-0.5 L kg-1) were observed at Hg/DOM ratios below approximately 1 μ g Hg per mg DOM. Only a small fraction (approximately 2%) of the reduced-S groups were involved with the strongest interactions between Hg and DOM, suggesting that the binding of Hg to DOM under natural conditions (very low Hg/DOM ratios ranging from 0.01 to 10 ng of Hg/mg of DOM) is controlled by a small fraction of DOM molecules containing reactive sulfur functional groups.

Hydrogen sulfide in plants: from dissipation of excess sulfur to signaling molecule.

PubMed

Calderwood, Alexander; Kopriva, Stanislav

2014-09-15

Sulfur is essential in all organisms for the synthesis of amino acids cysteine and methionine and as an active component of numerous co-factors and prosthetic groups. However, only plants, algae, fungi, and some prokaryotes are capable of using the abundant inorganic source of sulfur, sulfate. Plants take sulfate up, reduce it, and assimilate into organic compounds with cysteine being the first product of the pathway and a donor of reduced sulfur for synthesis of other S-containing compounds. Cysteine is formed in a reaction between sulfide, derived from reduction of sulfite and an activated amino acid acceptor, O-acetylserine. Sulfide is thus an important intermediate in sulfur metabolism, but numerous other functions in plants has been revealed. Hydrogen sulfide can serve as an alternative source of sulfur for plants, which may be significant in anaerobic conditions of waterlogged soils. On the other hand, emissions of hydrogen sulfide have been detected from many plant species. Since the amount of H2S discharged correlated with sulfate supply to the plants, the emissions were considered a mechanism for dissipation of excess sulfur. Significant hydrogen sulfide emissions were also observed in plants infected with pathogens, particularly with fungi. H2S thus seems to be part of the widely discussed sulfur-induced-resistance/sulfur-enhanced-defense. Recently, however, more evidence has emerged for a role for H2S in regulation and signaling. Sulfide stabilizes the cysteine synthase complex, increasing so the synthesis of its acceptor O-acetylserine. H2S has been implicating in regulation of plant stress response, particularly draught stress. There are more and more examples of processes regulated by H2S in plants being discovered, and hydrogen sulfide is emerging as an important signaling molecule, similar to its role in the animal and human world. How similar the functions, and homeostasis of H2S are in these diverse organisms, however, remains to be elucidated. Copyright © 2014 Elsevier Inc. All rights reserved.

Anthropogenic Sulfur Perturbations on Biogenic Oxidation: SO2 Additions Impact Gas-Phase OH Oxidation Products of α- and β-Pinene.

PubMed

Friedman, Beth; Brophy, Patrick; Brune, William H; Farmer, Delphine K

2016-02-02

In order to probe how anthropogenic pollutants can impact the atmospheric oxidation of biogenic emissions, we investigated how sulfur dioxide (SO2) perturbations impact the oxidation of two monoterpenes, α-and β-pinene. We used chemical ionization mass spectrometry to examine changes in both individual molecules and gas-phase bulk properties of oxidation products as a function of SO2 addition. SO2 perturbations impacted the oxidation systems of α-and β-pinene, leading to an ensemble of products with a lesser degree of oxygenation than unperturbed systems. These changes may be due to shifts in the OH:HO2 ratio from SO2 oxidation and/or to SO3 reacting directly with organic molecules. Van Krevelen diagrams suggest a shift from gas-phase functionalization by alcohol/peroxide groups to functionalization by carboxylic acid or carbonyl groups, consistent with a decreased OH:HO2 ratio. Increasing relative humidity dampens the impact of the perturbation. This decrease in oxygenation may impact secondary organic aerosol formation in regions dominated by biogenic emissions with nearby SO2 sources. We observed sulfur-containing organic compounds following SO2 perturbations of monoterpene oxidation; whether these are the result of photochemistry or an instrumental artifact from ion-molecule clustering remains uncertain. However, our results demonstrate that the two monoterpene isomers produce unique suites of oxidation products.

Relationship between chemical structure and rat repellency

USGS Publications Warehouse

Bellack, E.; DeWitt, J.B.; Treichler, R.

1953-01-01

Repellent activity is defined as the activity of a compound in preventing consumption of, or gnawing attacks upon, foodstuffs or articles containing or treated with the candidate substance. Data are presented on repellency indices of 2700 compounds, and it is shown that repellency is associated with specific functional groups attached to alkyl, aryl, or heterocyclic nuclei. Functional groups containing nitrogen, sulfur or halogens are most active, with amines, imides, thiocyanates and thiocarbamates forming some of the most active classes. Activity of any functional group may be affected by molecular weight, unsaturation, or spatial configuration of the nucleus, or by the presence of additional substituent groups.

Ultra Low Sulfur Home Heating Oil Demonstration Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batey, John E.; McDonald, Roger

2015-09-30

This Ultra Low Sulfur (ULS) Home Heating Oil Demonstration Project was funded by the New York State Energy Research and Development Authority (NYSERDA) and has successfully quantified the environmental and economic benefits of switching to ULS (15 PPM sulfur) heating oil. It advances a prior field study of Low Sulfur (500 ppm sulfur) heating oil funded by NYSERDA and laboratory research conducted by Brookhaven National Laboratory (BNL) and Canadian researchers. The sulfur oxide and particulate matter (PM) emissions are greatly reduced as are boiler cleaning costs through extending cleaning intervals. Both the sulfur oxide and PM emission rates are directlymore » related to the fuel oil sulfur content. The sulfur oxide and PM emission rates approach near-zero levels by switching heating equipment to ULS fuel oil, and these emissions become comparable to heating equipment fired by natural gas. This demonstration project included an in-depth review and analysis of service records for both the ULS and control groups to determine any difference in the service needs for the two groups. The detailed service records for both groups were collected and analyzed and the results were entered into two spreadsheets that enabled a quantitative side-by-side comparison of equipment service for the entire duration of the ULS test project. The service frequency for the ULS and control group were very similar and did indicate increased service frequency for the ULS group. In fact, the service frequency with the ULS group was slightly less (7.5 percent) than the control group. The only exception was that three burner fuel pump required replacement for the ULS group and none were required for the control group.« less

Directing the Lithium-Sulfur Reaction Pathway via Sparingly Solvating Electrolytes for High Energy Density Batteries.

PubMed

Lee, Chang-Wook; Pang, Quan; Ha, Seungbum; Cheng, Lei; Han, Sang-Don; Zavadil, Kevin R; Gallagher, Kevin G; Nazar, Linda F; Balasubramanian, Mahalingam

2017-06-28

The lithium-sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium-sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte. The use of sparingly solvating electrolytes in lithium-sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach. Herein, we demonstrate that sparingly solvating electrolytes based on compact, polar molecules with a 2:1 ratio of a functional group to lithium salt can fundamentally redirect the lithium-sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge. Moreover, operation at intermediate temperatures ca. 50 °C allows for minimal overpotentials and high utilization of sulfur at practical rates. This discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation-dissolution chemistries, lithium-sulfur and beyond.

The origin of luminescence from di[4-(4-diphenylaminophenyl)phenyl]sulfone (DAPSF), a blue light emitter: an X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study.

PubMed

Zhang, Duo; Zhang, Hui; Zhang, Xiaohong; Sham, Tsun-Kong; Hu, Yongfeng; Sun, Xuhui

2016-03-07

The electronic structure and optical properties of di[4-(4-diphenylaminophenyl)phenyl]sulfone (denoted as DAPSF), a highly efficient fluorophor, have been investigated using X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) spectroscopy at excitation energies across the C, N, O K-edges and the sulfur K-edge. The results indicate that the blue luminescence is mainly related to the sulfur functional group.

Elemental composition of human semen is associated with motility and genomic sperm defects among older men

PubMed Central

Schmid, Thomas E.; Grant, Patrick G.; Marchetti, Francesco; Weldon, Rosana H.; Eskenazi, Brenda; Wyrobek, Andrew J.

2013-01-01

BACKGROUND Older men tend to have poorer semen quality and are generally at higher risks for infertility and abnormal reproductive outcomes. METHODS We employed proton-induced X-ray emission (PIXE, 3 MeV proton beam) to investigate the concentrations of zinc, copper, calcium, sulfur, chlorine, potassium, titanium, iron and nickel in washed sperm and seminal plasma from non-smoking groups of 10 older men (65–80 years old) and 10 younger men (22–28 years old) who were concurrently assayed for sperm function and genomicly defective sperm. RESULTS The older group showed elevated zinc, copper and calcium in sperm and elevated sulfur in seminal plasma compared with the younger men. The older group also showed reduced motility as well as increased sperm DNA fragmentation, achondroplasia mutations, DNA strand breaks and chromosomal aberrations. Sperm calcium and copper were positively associated with sperm DNA fragmentation (P < 0.03). Seminal sulfur was positively associated with sperm DNA fragmentation and chromosomal aberrations (P < 0.04), and negatively associated with sperm motility (P < 0.05). Sperm calcium was negatively associated with sperm motility, independent of male age (P = 0.01). CONCLUSIONS We identified major differences in elemental concentrations between sperm and seminal plasma and that higher sperm copper, sulfur and calcium are quantitatively associated with poorer semen quality and increased frequencies of genomic sperm defects. PMID:23042799

Evidence for abiotic sulfurization of marine dissolved organic matter in sulfidic environments

NASA Astrophysics Data System (ADS)

Pohlabeln, A. M.; Niggemann, J.; Dittmar, T.

2016-02-01

Sedimentary organic matter abiotically sulfurizes in sulfidic marine environments. Here we hypothesize that sulfurization also affects dissolved organic matter (DOM), and that sulfidic marine environments are sources of dissolved organic sulfur (DOS) to the ocean. To test these hypotheses we studied solid-phase extractable (SPE) DOS in the Black Sea at various water column depths (oxic and anoxic) and in sediment porewaters from the German Wadden Sea. The concentration and molecular composition of SPE-DOS from these sites and from the oxic water columns of the North Sea (Germany) and of the North Pacific were compared. In support of our hypotheses, SPE-DOS concentrations were elevated in sulfidic waters compared to oxic waters. For a detailed molecular characterization of SPE-DOS, selective wet-chemical alteration experiments targeting different sulfur-containing functional groups were applied prior to Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). These experiments included harsh hydrolysis, selective derivatization of thiols, oxidation, and deoxygenation to test for thioesters, sulfonic acid esters, alkylsulfates, thiols, non-aromatic thioethers, and sulfoxides. Additionally, collision-induced fragmentation experiments were applied to test for sulfonic acids. The tests revealed that the sulfonic acid group was the main structural feature in SPE-DOS, independent of the environmental conditions of the sampling site. Only in Wadden Sea anoxic porewater also non-aromatic thioethers were found which are presumably not stable in oxic waters. The findings from our field studies were confirmed in laboratory experiments, where we abiotically sulfurized marine and algal-derived DOM under conditions similar to that in anoxic marine sediments.

Impact of Sulfuric Acid Treatment of Halloysite on Physico-Chemic Property Modification

PubMed Central

Gaaz, Tayser Sumer; Sulong, Abu Bakar; Kadhum, Abdul Amir H.; Nassir, Mohamed H.; Al-Amiery, Ahmed A.

2016-01-01

Halloysite (HNT) is treated with sulfuric acid and the physico-chemical properties of its morphology, surface activity, physical and chemical properties have been investigated when HNT is exposed to sulfuric acid with treatment periods of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21). The significance of this and similar work lies in the importance of using HNT as a functional material in nanocomposites. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The spectrum demonstrates that the hydroxyl groups were active for grafting modification using sulfuric acid, promoting a promising potential use for halloysite in ceramic applications as filler for novel clay-polymer nanocomposites. From the X-ray diffraction (XRD) spectrum, it can be seen that the sulfuric acid breaks down the HNT crystal structure and alters it into amorphous silica. In addition, the FESEM images reveal that the sulfuric acid treatment dissolves the AlO6 octahedral layers and induces the disintegration of SiO4 tetrahedral layers, resulting in porous nanorods. The Bruncher-Emmett-Teller (BET) surface area and total pore volume of HNTs showed an increase. The reaction of the acid with both the outer and inner surfaces of the nanotubes causes the AlO6 octahedral layers to dissolve, which leads to the breakdown and collapse of the tetrahedral layers of SiO4. The multi-fold results presented in this paper serve as a guide for further HNT functional treatment for producing new and advanced nanocomposites. PMID:28773741

Unification of [FeFe]-hydrogenases into three structural and functional groups.

PubMed

Poudel, Saroj; Tokmina-Lukaszewska, Monika; Colman, Daniel R; Refai, Mohammed; Schut, Gerrit J; King, Paul W; Maness, Pin-Ching; Adams, Michael W W; Peters, John W; Bothner, Brian; Boyd, Eric S

2016-09-01

[FeFe]-hydrogenases (Hyd) are structurally diverse enzymes that catalyze the reversible oxidation of hydrogen (H2). Recent biochemical data demonstrate new functional roles for these enzymes, including those that function in electron bifurcation where an exergonic reaction is coupled with an endergonic reaction to drive the reversible oxidation/production of H2. To identify the structural determinants that underpin differences in enzyme functionality, a total of 714 homologous sequences of the catalytic subunit, HydA, were compiled. Bioinformatics approaches informed by biochemical data were then used to characterize differences in inferred quaternary structure, HydA active site protein environment, accessory iron-sulfur clusters in HydA, and regulatory proteins encoded in HydA gene neighborhoods. HydA homologs were clustered into one of three classification groups, Group 1 (G1), Group 2 (G2), and Group 3 (G3). G1 enzymes were predicted to be monomeric while those in G2 and G3 were predicted to be multimeric and include HydB, HydC (G2/G3) and HydD (G3) subunits. Variation in the HydA active site and accessory iron-sulfur clusters did not vary by group type. Group-specific regulatory genes were identified in the gene neighborhoods of both G2 and G3 Hyd. Analyses of purified G2 and G3 enzymes by mass spectrometry strongly suggest that they are post-translationally modified by phosphorylation. These results suggest that bifurcation capability is dictated primarily by the presence of both HydB and HydC in Hyd complexes, rather than by variation in HydA. This classification scheme provides a framework for future biochemical and mutagenesis studies to elucidate the functional role of Hyd enzymes. Copyright © 2016 Elsevier B.V. All rights reserved.

Properties of Sulfur Concrete.

DTIC Science & Technology

1979-07-06

36 Thermal Contraction . . . . . . . . . . . 37 Summary of Sulfur Concrete (unmodified) . . . 39 Modified Sulfur Concrete............ 40...Compressive strength of PCPD- modified sulfur concrete 47 20 Functional connection between reaction time and temperature in making DCPD- modified sulfur concrete...39 MODIFIED SULFUR CONCRETE In the previous section it was shown that sulfur concrete exhibits several undesirable properties, such as 1 poor

Devices and methods to detect and quantify trace gases

DOEpatents

Allendorf, Mark D.; Robinson, Alex

2016-05-03

Sensing devices based on a surface acoustic wave ("SAW") device coated with an absorbent crystalline or amorphous layer for detecting at least one chemical analyte in a gaseous carrier. Methods for detecting the presence of a chemical analyte in a gaseous carrier using such devices are also disclosed. The sensing devices and methods for their use may be configured for sensing chemical analytes selected from the group consisting of water vapor, carbon dioxide, methanol, ethanol, carbon monoxide, nitric oxide, nitrous oxide, organic amines, organic compounds containing NO.sub.2 groups, halogenated hydrocarbons, acetone, hexane, toluene, isopropanol, alcohols, alkanes, alkenes, benzene, functionalized aromatics, ammonia (NH.sub.3), phosgene (COCl.sub.2), sulfur mustard, nerve agents, sulfur dioxide, tetrahydrofuran (THF) and methyltertbutyl ether (MTBE) and combinations thereof.

The Reactive Sulfur Species Concept: 15 Years On.

PubMed

Giles, Gregory I; Nasim, Muhammad Jawad; Ali, Wesam; Jacob, Claus

2017-05-23

Fifteen years ago, in 2001, the concept of "Reactive Sulfur Species" or RSS was advocated as a working hypothesis. Since then various organic as well as inorganic RSS have attracted considerable interest and stimulated many new and often unexpected avenues in research and product development. During this time, it has become apparent that molecules with sulfur-containing functional groups are not just the passive "victims" of oxidative stress or simple conveyors of signals in cells, but can also be stressors in their own right, with pivotal roles in cellular function and homeostasis. Many "exotic" sulfur-based compounds, often of natural origin, have entered the fray in the context of nutrition, ageing, chemoprevention and therapy. In parallel, the field of inorganic RSS has come to the forefront of research, with short-lived yet metabolically important intermediates, such as various sulfur-nitrogen species and polysulfides (S x 2- ), playing important roles. Between 2003 and 2005 several breath-taking discoveries emerged characterising unusual sulfur redox states in biology, and since then the truly unique role of sulfur-dependent redox systems has become apparent. Following these discoveries, over the last decade a "hunt" and, more recently, mining for such modifications has begun-and still continues-often in conjunction with new, innovative and complex labelling and analytical methods to capture the (entire) sulfur "redoxome". A key distinction for RSS is that, unlike oxygen or nitrogen, sulfur not only forms a plethora of specific reactive species, but sulfur also targets itself, as sulfur containing molecules, i.e., peptides, proteins and enzymes, preferentially react with RSS. Not surprisingly, today this sulfur-centred redox signalling and control inside the living cell is a burning issue, which has moved on from the predominantly thiol/disulfide biochemistry of the past to a complex labyrinth of interacting signalling and control pathways which involve various sulfur oxidation states, sulfur species and reactions. RSS are omnipresent and, in some instances, are even considered as the true bearers of redox control, perhaps being more important than the Reactive Oxygen Species (ROS) or Reactive Nitrogen Species (RNS) which for decades have dominated the redox field. In other(s) words, in 2017, sulfur redox is "on the rise", and the idea of RSS resonates throughout the Life Sciences. Still, the RSS story isn't over yet. Many RSS are at the heart of "mistaken identities" which urgently require clarification and may even provide the foundations for further scientific revolutions in the years to come. In light of these developments, it is therefore the perfect time to revisit the original hypotheses, to select highlights in the field and to question and eventually update our concept of "Reactive Sulfur Species".

The Reactive Sulfur Species Concept: 15 Years On

PubMed Central

Giles, Gregory I.; Nasim, Muhammad Jawad; Ali, Wesam; Jacob, Claus

2017-01-01

Fifteen years ago, in 2001, the concept of “Reactive Sulfur Species” or RSS was advocated as a working hypothesis. Since then various organic as well as inorganic RSS have attracted considerable interest and stimulated many new and often unexpected avenues in research and product development. During this time, it has become apparent that molecules with sulfur-containing functional groups are not just the passive “victims” of oxidative stress or simple conveyors of signals in cells, but can also be stressors in their own right, with pivotal roles in cellular function and homeostasis. Many “exotic” sulfur-based compounds, often of natural origin, have entered the fray in the context of nutrition, ageing, chemoprevention and therapy. In parallel, the field of inorganic RSS has come to the forefront of research, with short-lived yet metabolically important intermediates, such as various sulfur-nitrogen species and polysulfides (Sx2−), playing important roles. Between 2003 and 2005 several breath-taking discoveries emerged characterising unusual sulfur redox states in biology, and since then the truly unique role of sulfur-dependent redox systems has become apparent. Following these discoveries, over the last decade a “hunt” and, more recently, mining for such modifications has begun—and still continues—often in conjunction with new, innovative and complex labelling and analytical methods to capture the (entire) sulfur “redoxome”. A key distinction for RSS is that, unlike oxygen or nitrogen, sulfur not only forms a plethora of specific reactive species, but sulfur also targets itself, as sulfur containing molecules, i.e., peptides, proteins and enzymes, preferentially react with RSS. Not surprisingly, today this sulfur-centred redox signalling and control inside the living cell is a burning issue, which has moved on from the predominantly thiol/disulfide biochemistry of the past to a complex labyrinth of interacting signalling and control pathways which involve various sulfur oxidation states, sulfur species and reactions. RSS are omnipresent and, in some instances, are even considered as the true bearers of redox control, perhaps being more important than the Reactive Oxygen Species (ROS) or Reactive Nitrogen Species (RNS) which for decades have dominated the redox field. In other(s) words, in 2017, sulfur redox is “on the rise”, and the idea of RSS resonates throughout the Life Sciences. Still, the RSS story isn’t over yet. Many RSS are at the heart of “mistaken identities” which urgently require clarification and may even provide the foundations for further scientific revolutions in the years to come. In light of these developments, it is therefore the perfect time to revisit the original hypotheses, to select highlights in the field and to question and eventually update our concept of “Reactive Sulfur Species”. PMID:28545257

An alternative method to remove PEO-PPO-PEO template in organic-inorganic mesoporous nanocomposites by sulfuric acid extraction

NASA Astrophysics Data System (ADS)

Zhuang, Xin; Qian, Xufang; Lv, Jiahui; Wan, Ying

2010-06-01

Sulfuric acid is used as an extraction agent to remove PEO-PPO-PEO templates in the organic-inorganic mesoporous nanocomposites from the triconstituent co-assembly which includes the low-polymerized phenolic resins, TEOS and triblock copolymer F127. The XRD and TEM results show well ordered mesostructure after extraction with sulfuric acid. As followed from the N 2 sorption isotherms the extracted composites possess high surface areas (332-367 m 2/g), large pore volumes (0.66-0.78 cm 3/g), and large pore sizes (about 10.7 nm). The FT-IR analysis reveals almost complete elimination of triblock copolymer F127, and the maintenance of organic groups. This method shows potentials in removing templates from nanocomposites containing functional moieties.

DEVELOPMENT OF NONCARBON SORBENTS FOR HG0 REMOVAL FROM COAL-FIRED POWER PLANTS

EPA Science Inventory

Noncarbon materials or mineral oxides (silica gel, alumina, molecular sieves, zeolites, and montmorillonite) were modified with various functional groups, such as amine, amide, thiol, and urea; and active additives, such as elemental sulfur, sodium sulfide, and sodium polysulfide...

Life detection at an Arctic analog to Europa

NASA Astrophysics Data System (ADS)

Gleeson, D. F.; Pappalardo, R. T.; Anderson, M. S.; Grasby, S. E.; Wright, K.; Templeton, A. S.

2010-12-01

Europa is a high priority for astrobiological investigations. Future missions to the icy surface of this moon will query the arguably sulfur-rich materials for potential indications of the presence of life carried to the surface by mobile ice or partial melt. Cold sulfur-rich environments are rare on the Earth, and the potential for the generation and preservation of biosignatures under these conditions remains largely unconstrained. Here we describe investigations into the biogenicity of analogous sulfur deposits from the surface of an Arctic glacier at Borup Fiord pass, Ellesmere Island. Optical and electron microscopy indicate that the sulfur in field samples is present in the form of clumps of mineral grains and spherical mineral aggregates, in close association with microbial sheaths. The morphologies of these materials are consistent with observations of the sulfur generated by sulfide-oxidizing bacteria cultivated from field samples in previous studies. X-ray diffraction measurements provide some evidence for the presence of rosickyite, a metastable form of sulfur previously recognized to be associated with the presence of life. Infrared spectroscopy reveals the presence of organics at parts per million levels, and organic functional groups diagnostic of proteins and fatty acids are identified. Organic components were below the detection limit for Raman spectra, which were dominated by sulfur peaks. These combined investigations indicate that sulfur minerals have the potential to contain identifiable biosignatures that low-temperature conditions help stabilize and preserve. Borup Fiord Pass represents a useful testing ground for instruments and techniques relevant to future astrobiological exploration at Europa.

Directing the Lithium–Sulfur Reaction Pathway via Sparingly Solvating Electrolytes for High Energy Density Batteries

PubMed Central

2017-01-01

The lithium–sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium–sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte. The use of sparingly solvating electrolytes in lithium–sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach. Herein, we demonstrate that sparingly solvating electrolytes based on compact, polar molecules with a 2:1 ratio of a functional group to lithium salt can fundamentally redirect the lithium–sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge. Moreover, operation at intermediate temperatures ca. 50 °C allows for minimal overpotentials and high utilization of sulfur at practical rates. This discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation–dissolution chemistries, lithium–sulfur and beyond. PMID:28691072

Directing the lithium–sulfur reaction pathway via sparingly solvating electrolytes for high energy density batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Chang -Wook; Pang, Quan; Ha, Seungbum

The lithium–sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium–sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte. The use of sparingly solvating electrolytes in lithium–sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach. Herein, we demonstrate that sparinglymore » solvating electrolytes based on compact, polar molecules with a 2:1 ratio of a functional group to lithium salt can fundamentally redirect the lithium–sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge. Moreover, operation at intermediate temperatures ca. 50 °C allows for minimal overpotentials and high utilization of sulfur at practical rates. Finally, this discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation–dissolution chemistries, lithium–sulfur and beyond.« less

Directing the lithium–sulfur reaction pathway via sparingly solvating electrolytes for high energy density batteries

DOE PAGES

Lee, Chang -Wook; Pang, Quan; Ha, Seungbum; ...

2017-05-25

The lithium–sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium–sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte. The use of sparingly solvating electrolytes in lithium–sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach. Herein, we demonstrate that sparinglymore » solvating electrolytes based on compact, polar molecules with a 2:1 ratio of a functional group to lithium salt can fundamentally redirect the lithium–sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge. Moreover, operation at intermediate temperatures ca. 50 °C allows for minimal overpotentials and high utilization of sulfur at practical rates. Finally, this discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation–dissolution chemistries, lithium–sulfur and beyond.« less

The Microbial Sulfur Cycle at Extremely Haloalkaline Conditions of Soda Lakes

PubMed Central

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

2011-01-01

Soda lakes represent a unique ecosystem with extremely high pH (up to 11) and salinity (up to saturation) due to the presence of high concentrations of sodium carbonate in brines. Despite these double extreme conditions, most of the lakes are highly productive and contain a fully functional microbial system. The microbial sulfur cycle is among the most active in soda lakes. One of the explanations for that is high-energy efficiency of dissimilatory conversions of inorganic sulfur compounds, both oxidative and reductive, sufficient to cope with costly life at double extreme conditions. The oxidative part of the sulfur cycle is driven by chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria (SOB), which are unique for soda lakes. The haloalkaliphilic SOB are present in the surface sediment layer of various soda lakes at high numbers of up to 106 viable cells/cm3. The culturable forms are so far represented by four novel genera within the Gammaproteobacteria, including the genera Thioalkalivibrio, Thioalkalimicrobium, Thioalkalispira, and Thioalkalibacter. The latter two were only found occasionally and each includes a single species, while the former two are widely distributed in various soda lakes over the world. The genus Thioalkalivibrio is the most physiologically diverse and covers the whole spectrum of salt/pH conditions present in soda lakes. Most importantly, the dominant subgroup of this genus is able to grow in saturated soda brines containing 4 M total Na+ – a so far unique property for any known aerobic chemolithoautotroph. Furthermore, some species can use thiocyanate as a sole energy source and three out of nine species can grow anaerobically with nitrogen oxides as electron acceptor. The reductive part of the sulfur cycle is active in the anoxic layers of the sediments of soda lakes. The in situ measurements of sulfate reduction rates and laboratory experiments with sediment slurries using sulfate, thiosulfate, or elemental sulfur as electron acceptors demonstrated relatively high sulfate reduction rates only hampered by salt-saturated conditions. However, the highest rates of sulfidogenesis were observed not with sulfate, but with elemental sulfur followed by thiosulfate. Formate, but not hydrogen, was the most efficient electron donor with all three sulfur electron acceptors, while acetate was only utilized as an electron donor under sulfur-reducing conditions. The native sulfidogenic populations of soda lakes showed a typical obligately alkaliphilic pH response, which corresponded well to the in situ pH conditions. Microbiological analysis indicated a domination of three groups of haloalkaliphilic autotrophic sulfate-reducing bacteria belonging to the order Desulfovibrionales (genera Desulfonatronovibrio, Desulfonatronum, and Desulfonatronospira) with a clear tendency to grow by thiosulfate disproportionation in the absence of external electron donor even at salt-saturating conditions. Few novel representatives of the order Desulfobacterales capable of heterotrophic growth with volatile fatty acids and alcohols at high pH and moderate salinity have also been found, while acetate oxidation was a function of a specialized group of haloalkaliphilic sulfur-reducing bacteria, which belong to the phylum Chrysiogenetes. PMID:21747784

The shadow price of substitutable sulfur in the US electric power plant: a distance function approach.

PubMed

Lee, Myunghun

2005-10-01

Given restrictions on sulfur dioxide emissions, a feasible long-run response could involve either an investment in improving boiler fuel-efficiency or a shift to a production process that is effective in removing sulfur dioxide. To allow for the possibility of substitution between sulfur and productive capital, we measure the shadow price of sulfur dioxide as the opportunity cost of lowering sulfur emissions in terms of forgone capital. The input distance function is estimated with data from 51 coal-fired US power units operating between 1977 and 1986. The indirect Morishima elasticities of substitution indicate that the substitutability of capital for sulfur is relatively high. The overall weighted average estimate of the shadow price of sulfur is -0.076 dollars per pound in constant 1976 dollars.

Adsorption of sulfur dioxide on ammonia-treated activated carbon fibers

USGS Publications Warehouse

Mangun, C.L.; DeBarr, J.A.; Economy, J.

2001-01-01

A series of activated carbon fibers (ACFs) and ammonia-treated ACFs prepared from phenolic fiber precursors have been studied to elucidate the role of pore size, pore volume, and pore surface chemistry on adsorption of sulfur dioxide and its catalytic conversion to sulfuric acid. As expected, the incorporation of basic functional groups into the ACFs was shown as an effective method for increasing adsorption of sulfur dioxide. The adsorption capacity for dry SO2 did not follow specific trends; however the adsorption energies calculated from the DR equation were found to increase linearly with nitrogen content for each series of ACFs. Much higher adsorption capacities were achieved for SO2 in the presence of oxygen and water due to its catalytic conversion to H2SO4. The dominant factor for increasing adsorption of SO2 from simulated flue gas for each series of fibers studied was the weight percent of basic nitrogen groups present. In addition, the adsorption energies calculated for dry SO2 were shown to be linearly related to the adsorption capacity of H2SO4 from this flue gas for all fibers. It was shown that optimization of this parameter along with the pore volume results in higher adsorption capacities for removal of SO2 from flue gases. ?? 2001 Elsevier Science Ltd. All rights reserved.

Thiosulfate Transfer Mediated by DsrE/TusA Homologs from Acidothermophilic Sulfur-oxidizing Archaeon Metallosphaera cuprina*

PubMed Central

Liu, Li-Jun; Stockdreher, Yvonne; Koch, Tobias; Sun, Shu-Tao; Fan, Zheng; Josten, Michaele; Sahl, Hans-Georg; Wang, Qian; Luo, Yuan-Ming; Liu, Shuang-Jiang; Dahl, Christiane; Jiang, Cheng-Ying

2014-01-01

Conserved clusters of genes encoding DsrE and TusA homologs occur in many archaeal and bacterial sulfur oxidizers. TusA has a well documented function as a sulfurtransferase in tRNA modification and molybdenum cofactor biosynthesis in Escherichia coli, and DsrE is an active site subunit of the DsrEFH complex that is essential for sulfur trafficking in the phototrophic sulfur-oxidizing Allochromatium vinosum. In the acidothermophilic sulfur (S0)- and tetrathionate (S4O62−)-oxidizing Metallosphaera cuprina Ar-4, a dsrE3A-dsrE2B-tusA arrangement is situated immediately between genes encoding dihydrolipoamide dehydrogenase and a heterodisulfide reductase-like complex. In this study, the biochemical features and sulfur transferring abilities of the DsrE2B, DsrE3A, and TusA proteins were investigated. DsrE3A and TusA proved to react with tetrathionate but not with NaSH, glutathione persulfide, polysulfide, thiosulfate, or sulfite. The products were identified as protein-Cys-S-thiosulfonates. DsrE3A was also able to cleave the thiosulfate group from TusA-Cys18-S-thiosulfonate. DsrE2B did not react with any of the sulfur compounds tested. DsrE3A and TusA interacted physically with each other and formed a heterocomplex. The cysteine residue (Cys18) of TusA is crucial for this interaction. The single cysteine mutants DsrE3A-C93S and DsrE3A-C101S retained the ability to transfer the thiosulfonate group to TusA. TusA-C18S neither reacted with tetrathionate nor was it loaded with thiosulfate with DsrE3A-Cys-S-thiosulfonate as the donor. The transfer of thiosulfate, mediated by a DsrE-like protein and TusA, is unprecedented not only in M. cuprina but also in other sulfur-oxidizing prokaryotes. The results of this study provide new knowledge on oxidative microbial sulfur metabolism. PMID:25122768

Reaction of hydroxy and carbonyl compounds with sulfur tetrafluoride. XVI. Reactions of vicinal dihydric alcohols with sulfur tetrafluoride (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burmakov, A.I.; Hassanein, S.M.; Kunshenko, B.V.

1986-11-20

During the action of sulfur tetrafluoride on ethanediol, d,l-1,2-propanediol, d,l-3,3,3-trifluoro-1,2-propanediol regioselective substitution of one of the hydroxyl groups by a fluorine atom occurs, depending on the electronic nature of the groups present in the molecule. The second hydroxy group in converted into a fluorosulfite group.

Investigation into the ring-substituted polyanilines and their application for the detection and adsorption of sulfur dioxide

PubMed Central

Tian, Yuhong; Qu, Ke; Zeng, Xiangqun

2017-01-01

It has been demonstrated in this study that the substituents on the monomer aniline benzene ring are able to introduce the significant differences to the resulting polyaniline’s collective properties. We systematically evaluated the structural perturbation effects of two substituents (methyl and methoxy) of aniline monomer through the electrochemical method. Our results showed that the methoxy group induces the less structural perturbation than the methyl counterpart, because of its partial double bond restriction. The morphologies are different for the polyaniline and the ring-substituted polyanilines, in which substituted polyanilines feature the larger porosities with the addition of these side groups. The influential effects of the methoxy side group have been further illustrated and amplified by its superior sensing performance towards the environmentally-significant sulfur dioxide gas, evaluated through the construction of the quartz crystal microbalance (QCM)-based gas sensor with these polyaniline materials. The as-constructed gas sensor’s sensitivity, selectivity and stability in terms of its SO2 responses have been evaluated in details. The methoxy-substituted polyaniline was tested to show the unique gas sensing properties for the sulfur dioxide at the low concentrations (50–250 ppm) and function as the adsorbing material at the high concentrations (500–1250 ppm). Thus it can be used both as sensing material as well as a novel filter and/or storage reservoir for the removal of sulfur dioxide pollutant from the environments. PMID:29033497

[The sources of inorganic sulfur in the process of cluster protein Fnr[4Fe-4S]2+ reconstruction in Escherichia coli cells cultivated with NO-donating agents].

PubMed

Vasil'eva, S V; Strel'tsova, D A; Vlaskina, A V; Mikoian, V D; Vanin, A F

2012-01-01

Dinitrosyl iron complexes (DNICs) with thiol ligands--binuclear and mononuclear--inhibited aidB gene expression in E. coli cells. This process is due to the nitrosylation of the active center in iron-sulfur protein Fnr [4Fe-4S]2+ by low-molecular DNICs. The next step is transformation of the above DNICs into the DNICs with the thiol groups in the apo-form of Fnr protein. These nitrosylated proteins are characterized by the EPR signal with g perpendicular = 2.04 and g parallel 1 = 2,014. An addition of sulfur containing L-Cys or N-A-L-Cys as well as Na2S to the cells lead to the increasing in the aidB gene expression simultaneously with an appearance of the EPR signal with g perpendicular = 2.04 and g parallel = 2.02 as the characteristics of the DNICs with persulfide (R-S-S-) ligands. We suppose that the recovery of the aidB gene activity was due to the accumulation of inorganic sulfur in the cells and reconstruction of the active center in Fnr[4Fe-4S]2+. It appears that the above process is the function of L-cysteine-desulfurase protein which repaired the active center of Fnr[4Fe-4S]2+ protein using the sulfur from L-Cys or N-A-L-Cys after its deacetylation. On the other side the ions of inorganic sulfur being reacted with SH-groups led to the transformation of DNIC with thiol ligands into the persulfides. Na2S was the most potent activator of the aidB gene expression in our experiments.

Unification of [FeFe]-hydrogenases into three structural and functional groups

DOE PAGES

Poudel, Saroj; Tokmina-Lukaszewska, Monika; Colman, Daniel R.; ...

2016-05-27

[FeFe]-hydrogenases (Hyd) are structurally diverse enzymes that catalyze the reversible oxidation of hydrogen (H 2). Recent biochemical data demonstrate new functional roles for these enzymes, including those that function in electron bifurcation where an exergonic reaction is coupled with an endergonic reaction to drive the reversible oxidation/production of H 2. To identify the structural determinants that underpin differences in enzyme functionality, a total of 714 homologous sequences of the catalytic subunit, HydA, were compiled. Bioinformatics approaches informed by biochemical data were then used to characterize differences in inferred quaternary structure, HydA active site protein environment, accessory iron-sulfur clusters in HydA,more » and regulatory proteins encoded in HydA gene neighborhoods. HydA homologs were clustered into one of three classification groups, Group 1 (G1), Group 2 (G2), and Group 3 (G3). G1 enzymes were predicted to be monomeric while those in G2 and G3 were predicted to be multimeric and include HydB, HydC (G2/G3) and HydD (G3) subunits. Variation in the HydA active site and accessory iron-sulfur clusters did not vary by group type. Group-specific regulatory genes were identified in the gene neighborhoods of both G2 and G3 Hyd. Analyses of purified G2 and G3 enzymes by mass spectrometry strongly suggests that they are post-translationally modified by phosphorylation. In conclusion, these results suggest that bifurcation capability is dictated primarily by the presence of both HydB and HydC in Hyd complexes, rather than by variation in HydA.« less

Auxiliary iron-sulfur cofactors in radical SAM enzymes.

PubMed

Lanz, Nicholas D; Booker, Squire J

2015-06-01

A vast number of enzymes are now known to belong to a superfamily known as radical SAM, which all contain a [4Fe-4S] cluster ligated by three cysteine residues. The remaining, unligated, iron ion of the cluster binds in contact with the α-amino and α-carboxylate groups of S-adenosyl-l-methionine (SAM). This binding mode facilitates inner-sphere electron transfer from the reduced form of the cluster into the sulfur atom of SAM, resulting in a reductive cleavage of SAM to methionine and a 5'-deoxyadenosyl radical. The 5'-deoxyadenosyl radical then abstracts a target substrate hydrogen atom, initiating a wide variety of radical-based transformations. A subset of radical SAM enzymes contains one or more additional iron-sulfur clusters that are required for the reactions they catalyze. However, outside of a subset of sulfur insertion reactions, very little is known about the roles of these additional clusters. This review will highlight the most recent advances in the identification and characterization of radical SAM enzymes that harbor auxiliary iron-sulfur clusters. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Nucleophilic substitution by grignard reagents on sulfur mustards.

PubMed

Converso, Antonella; Saaidi, Pierre-Loïc; Sharpless, K Barry; Finn, M G

2004-10-15

With proper activation of the leaving group, sulfur mustards react with Grignard reagents with neighboring group participation of the sulfur atom. 2,6-Dichloro-9-thiabicyclo[3.3.1]nonane is especially useful in this regard, providing clean reactivity with organomagnesium nucleophiles on a topologically constrained scaffold.

Hydroxymethyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals and method of making same

DOEpatents

Katti, Kattesh V.; Karra, Srinivasa Rao; Berning, Douglas E.; Smith, C. Jeffrey; Volkert, Wynn A.; Ketring, Alan R.

1999-01-01

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises at least one functionalized hydroxyalkyl phosphine donor group and one or more sulfur or nitrogen donor and a metal combined with the ligand.

Hydroxymethyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals and method of making same

DOEpatents

Katti, Kattesh V.; Karra, Srinivasa Rao; Berning, Douglas E.; Smith, C. Jeffrey; Volkert, Wynn A.; Ketring, Alan R.

2000-01-01

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises at least one functionalized hydroxyalkyl phosphine donor group and one or more sulfur or nitrogen donor and a metal combined with the ligand.

Fragmentation analysis of water-soluble atmospheric organic matter using ultrahigh-resolution FT-ICR mass spectrometry.

PubMed

Leclair, Jeffrey P; Collett, Jeffrey L; Mazzoleni, Lynn R

2012-04-17

Isolated water-soluble atmospheric organic matter (AOM) analytes extracted from radiation fogwater samples were analyzed using collision induced dissociation with ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Tandem mass analysis was performed on several mass ranges between 100 and 400 Da to characterize the functional groups of AOM species. Compounds containing nitrogen and/or sulfur were targeted because of the high number of oxygen atoms contained in their molecular formulas. Due to the large number of isobaric ions in the precursor isolation ranges, large numbers of product ions resulted from collision induced dissociation. Common neutral losses were assigned by matching the molecular formulas of the expected product ions with the detected product ions within the appropriate mass spectra. Since polar functional groups are expected to affect the hygroscopic properties of aerosols, the losses of H(2)O, CO(2), CH(3)OH, HNO(3), CH(3)NO(3), SO(3), SO(4) and combinations of these were specifically targeted. Among the 421 compounds studied, the most frequently observed neutral losses were CO(2) (54%), H(2)O (43%) and CH(3)OH (40%). HNO(3) losses were observed for 63% of the studied nitrogen containing compounds and 33% of the studied compounds containing both nitrogen and sulfur. SO(3) losses were observed for 85% of the studied sulfur containing compounds and 42% of studied compounds containing both nitrogen and sulfur. A number of molecular formulas matching those of monoterpene ozonolysis SOA were observed; they include organonitrates, organosulfates, and nitroxy-organosulfates. Overall, the results of fragmentation analysis of 400+ individual molecular precursors elucidate the complexity and multifunctional nature of the isolated water-soluble AOM.

Comparative Efficacy of Topical Pertmehrin, Crotamiton and Sulfur Ointment in Treatment of Scabies

PubMed Central

Mila-Kierzenkowska, Celestyna; Woźniak, Alina; Krzyżyńska-Malinowska, Ewa; Kałużna, Lucyna; Wesołowski, Roland; Poćwiardowski, Wojciech; Owcarz, Marcin

2017-01-01

Background: Scabies is an ectoparasitic infection, which occurs because of direct skin-to skin contact. The ideal treatment modality is still unclear and further research on this topic is warranted. The aim of the study was to compare the efficacy and safety of the topical scabicides: permethrin, crotamiton and sulfur ointment. Methods: Fifty four patients with diagnosed scabies were randomly divided into three treatment groups. The first group received 5% permethrin cream twice with one week interval, the patients from the second group were given crotamiton lotion for two days twice with one week interval, while the third group received 10% sulfur ointment for two or three weeks. All patients were followed up at 1, 2 and 4 weeks intervals. Results: At one-week follow up the cure rate was significantly higher at permethrin-treated group when compared to crotamiton group (P< 0.001) and sulfur group (P< 0.001). At the end of two-week interval, the cure rate at permethrin group was 100%, while at crotamiton group, 66.7% and in sulfur group 38.9% (P< 0.001). At 4-week follow up the applied treatment was effective in all studied individuals. Conclusion: The topical application of permethrin, crotamiton and sulfur was equally efficacious at 4-week follow up, however permethrin cream showed faster improvement at first and second follow up. Acquiring permethrin is considered as expensive option and crotamiton lotion seems to be cost-less alternative to this cream. PMID:29018829

Comparative Efficacy of Topical Pertmehrin, Crotamiton and Sulfur Ointment in Treatment of Scabies.

PubMed

Mila-Kierzenkowska, Celestyna; Woźniak, Alina; Krzyżyńska-Malinowska, Ewa; Kałużna, Lucyna; Wesołowski, Roland; Poćwiardowski, Wojciech; Owcarz, Marcin

2017-03-01

Scabies is an ectoparasitic infection, which occurs because of direct skin-to skin contact. The ideal treatment modality is still unclear and further research on this topic is warranted. The aim of the study was to compare the efficacy and safety of the topical scabicides: permethrin, crotamiton and sulfur ointment. Fifty four patients with diagnosed scabies were randomly divided into three treatment groups. The first group received 5% permethrin cream twice with one week interval, the patients from the second group were given crotamiton lotion for two days twice with one week interval, while the third group received 10% sulfur ointment for two or three weeks. All patients were followed up at 1, 2 and 4 weeks intervals. At one-week follow up the cure rate was significantly higher at permethrin-treated group when compared to crotamiton group (P< 0.001) and sulfur group (P< 0.001). At the end of two-week interval, the cure rate at permethrin group was 100%, while at crotamiton group, 66.7% and in sulfur group 38.9% (P< 0.001). At 4-week follow up the applied treatment was effective in all studied individuals. The topical application of permethrin, crotamiton and sulfur was equally efficacious at 4-week follow up, however permethrin cream showed faster improvement at first and second follow up. Acquiring permethrin is considered as expensive option and crotamiton lotion seems to be cost-less alternative to this cream.

Preservation of organic matter on Mars by sulfur

NASA Astrophysics Data System (ADS)

Eigenbrode, J. L.; Steele, A.; Summons, R. E.; McAdam, A.; Sutter, B.; Franz, H. B.; Freissinet, C.; Millan, M.; Glavin, D. P.; Szopa, C.; Conrad, P. G.; Mahaffy, P. R.

2016-12-01

Deltaic-lacustrine mudstones at Pahrump Hills, Gale Crater, Mars yielded a variety of sulfur-containing volatiles upon heating to 500-860°C, as detected by the Sample Analysis at Mars (SAM) instrument onboard the Curiosity rover. The detection of organosulfur compounds comprising thiophenes, dimethylsulfide and thiols by gas chromatography-mass spectrometry and evolved gas analyses, together with aromatic and other hydrocarbon molecules with distributions specific to the sample (i.e., not from the SAM background) indicate that some or all of these organic fragments released at high temperatures are indigenous to the mudstones. The organosulfur compounds are most likely derived from sulfur organics in the sediments. However, there is a possibility that sulfurization of some organic fragments occurred in the oven. On Earth, sulfurization of organic matter is a key process that aids preservation over geological time-scales. This is because it reduces reactive functional groups and adds cross links between small unstable molecules thereby converting them into recalcitrant macromolecules. Sulfurization of organic materials prior to deposition and during early diagenesis may have been a key mechanism responsible for organic matter preservation in the Murray formation mudstones. Sulfur-bearing organics have also been observed in carbonaceous meteorites and there is indication of their presence in the Tissint martian meteorite. A quantitative assessment of organosulfur compounds relative to their non-organic counterparts will be presented for the Murray formation mudstones analyzed by SAM and meteorites analyzed in the laboratory under similar analytical conditions.

Hydroxymethyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals and method of making same

DOEpatents

Katti, K.V.; Karra, S.R.; Berning, D.E.; Smith, C.J.; Volkert, W.A.; Ketring, A.R.

1999-01-05

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises at least one functionalized hydroxyalkyl phosphine donor group and one or more sulfur or nitrogen donor and a metal combined with the ligand. 21 figs.

High reactive sulphide chemically supported on silica surface to prepare functional nanoparticle

NASA Astrophysics Data System (ADS)

Chen, Lijuan; Guo, Xiaohui; Jia, Zhixin; Tang, Yuhan; Wu, Lianghui; Luo, Yuanfang; Jia, Demin

2018-06-01

A solid-phase preparation method was applied to obtain a novel, green and effective functional nanoparticle, silica-supported sulfur monochloride (silica-s-S2Cl2), by the chemical reaction between chlorine atom and silicon hydroxyl on the silica surface. Through this chemical reaction, silica surface supported with high content of sulfur, and the functional nanoparticles can not only vulcanize the rubber instead of sulfur or other vulcanizing agent with high performance, but also improve the filler-rubber interaction as a modifier due to the improved modification effect. 29Si NMR, Raman spectroscopy, Element analysis and TGA confirm that the sulfur monochloride is chemically bonded on the silica surface. Cure properties measurement, morphology of filler dispersion, mechanical properties measurement, immobilized polymer layer and oxidation induction time increment together show that the novel vulcanizing agent silica-s-S2Cl2 instead of sulfur in rubber vulcanization gives rise to significant improvement in the crosslinking density and the interfacial adhesion between silica particles and the rubber matrix, which is on account of the promoted vulcanizing on the functional silica nanoparticles surface with the supported sulfur.

Synergistically Enhanced Interfacial Interaction to Polysulfide via N,O Dual-Doped Highly Porous Carbon Microrods for Advanced Lithium-Sulfur Batteries.

PubMed

Wang, Nana; Xu, Zhongfei; Xu, Xun; Liao, Ting; Tang, Bin; Bai, Zhongchao; Dou, Shixue

2018-04-25

Lithium-sulfur (Li-S) batteries have received tremendous attention because of their extremely high theoretical capacity (1672 mA h g -1 ) and energy density (2600 W h kg -1 ). Nevertheless, the commercialization of Li-S batteries has been blocked by the shuttle effect of lithium polysulfide intermediates, the insulating nature of sulfur, and the volume expansion during cycling. Here, hierarchical porous N,O dual-doped carbon microrods (NOCMs) were developed as sulfur host materials with a large pore volume (1.5 cm 3 g -1 ) and a high surface area (1147 m 2 g -1 ). The highly porous structure of the NOCMs can act as a physical barrier to lithium polysulfides, while N and O functional groups enhance the interfacial interaction to trap lithium polysulfides, permitting a high loading amount of sulfur (79-90 wt % in the composite). Benefiting from the physical and chemical anchoring effect to prevent shuttling of polysulfides, S@NOCMs composites successfully solve the problems of low sulfur utilization and fast capacity fade and exhibit a stable reversible capacity of 1071 mA h g -1 after 160 cycles with nearly 100% Coulombic efficiency at 0.2 C. The N,O dual doping treatment to porous carbon microrods paves a way toward rational design of high-performance Li-S cathodes with high energy density.

Mechanisms of volatile production from non-sulfur amino acids by irradiation

NASA Astrophysics Data System (ADS)

Ahn, Dong Uk; Lee, Eun Joo; Feng, Xi; Zhang, Wangang; Lee, Ji Hwan; Jo, Cheorun; Nam, Kichang

2016-02-01

Non-sulfur amino acid monomers were used to study the mechanisms of volatile production in meat by irradiation. Irradiation not only produced many volatiles but also increased the amounts of volatiles from non-sulfur amino acid monomers. The major reaction mechanisms involved in volatile production from each group of the amino acids by irradiation differ significantly. However, we speculate that the radiolysis of amino acid side chains were the major mechanism. In addition, Strecker degradation, especially the production of aldehydes from aliphatic group amino acids, and deamination, isomerization, decarboxylation, cyclic reaction and dehydrogenation of the initial radiolytic products were also contributed to the production of volatile compounds. Each amino acid monomers produced different odor characteristics, but the intensities of odor from all non-sulfur amino acid groups were very weak. This indicated that the contribution of volatiles produced from non-sulfur amino acids was minor. If the volatile compounds from non-sulfur amino acids, especially aldehydes, interact with other volatiles compounds such as sulfur compounds, however, they can contribute to the off-odor of irradiated meat significantly.

Biodegradation tests of mercaptocarboxylic acids, their esters, related divalent sulfur compounds and mercaptans.

PubMed

Rücker, Christoph; Mahmoud, Waleed M M; Schwartz, Dirk; Kümmerer, Klaus

2018-04-17

Mercaptocarboxylic acids and their esters, a class of difunctional compounds bearing both a mercapto and a carboxylic acid or ester functional group, are industrial chemicals of potential environmental concern. Biodegradation of such compounds was systematically investigated here, both by literature search and by experiments (Closed Bottle Test OECD 301D and Manometric Respirometry Test OECD 301F). These compounds were found either readily biodegradable or at least biodegradable to a significant extent. Some related compounds of divalent sulfur were tested for comparison (mercaptans, sulfides, disulfides). For the two relevant monofunctional compound classes, carboxylic acids/esters and mercaptans, literature data were compiled, and by comparison with structurally similar compounds without these functional groups, the influence of COOH/COOR' and SH groups on biodegradability was evaluated. Thereby, an existing rule of thumb for biodegradation of carboxylic acids/esters was supported by experimental data, and a rule of thumb could be formulated for mercaptans. Concurrent to biodegradation, abiotic processes were observed in the experiments, rapid oxidative formation of disulfides (dimerisation of monomercaptans and cyclisation of dimercaptans) and hydrolysis of esters. Some problems that compromise the reproducibility of biodegradation test results were discussed.

Selenocysteine in thiol/disulfide-like exchange reactions.

PubMed

Hondal, Robert J; Marino, Stefano M; Gladyshev, Vadim N

2013-05-01

Among trace elements used as cofactors in enzymes, selenium is unique in that it is incorporated into proteins co-translationally in the form of an amino acid, selenocysteine (Sec). Sec differs from cysteine (Cys) by only one atom (selenium versus sulfur), yet this switch dramatically influences important aspects of enzyme reactivity. The main focus of this review is an updated and critical discussion on how Sec might be used to accelerate thiol/disulfide-like exchange reactions in natural selenoenzymes, compared with their Cys-containing homologs. We discuss in detail three major aspects associated with thiol/disulfide exchange reactions: (i) nucleophilicity of the attacking thiolate (or selenolate); (ii) electrophilicity of the center sulfur (or selenium) atom; and (iii) stability of the leaving group (sulfur or selenium). In all these cases, we analyze the benefits that selenium might provide in these types of reactions. It is the biological thiol oxidoreductase-like function that benefits from the use of Sec, since Sec functions to chemically accelerate the rate of these reactions. We review various hypotheses that could help explain why Sec is used in enzymes, particularly with regard to competitive chemical advantages provided by the presence of the selenium atom in enzymes. Ultimately, these chemical advantages must be connected to biological functions of Sec.

Theoretical investigation of the interaction between aromatic sulfur compounds and [BMIM](+)[FeCl4](-) ionic liquid in desulfurization: A novel charge transfer mechanism.

PubMed

Li, Hongping; Zhu, Wenshuai; Chang, Yonghui; Jiang, Wei; Zhang, Ming; Yin, Sheng; Xia, Jiexiang; Li, Huaming

2015-06-01

In this work, interaction nature between a group of aromatic sulfur compounds and [BMIM](+)[FeCl4](-) have been investigated by density functional theory (DFT). A coordination structure is found to be critical to the mechanism of extractive desulfurization. Interaction energy and extractive selectivity follow the order: thiophene (TH)

Ultrasonically treated multi-walled carbon nanotubes (MWCNTs) as PtRu catalyst supports for methanol electrooxidation

NASA Astrophysics Data System (ADS)

Yang, Chunwei; Hu, Xinguo; Wang, Dianlong; Dai, Changsong; Zhang, Liang; Jin, Haibo; Agathopoulos, Simeon

In the quest of fabricating supported catalysts, experimental results of transmission electron microscopy, Raman and infrared spectroscopy indicate that ultrasonic treatment effectively functionalizes multi-walled carbon nanotubes (MWCNTs), endowing them with groups that can act as nucleation sites which can favor well-dispersed depositions of PtRu clusters on their surface. Ultrasonic treatment seems to be superior than functionalization via regular refluxing. This is confirmed by the determination of the electrochemistry active surface area (ECA) and the CO-tolerance performance of the PtRu catalysts, measured by adsorbed CO-stripping voltammetry in 0.5 M sulfuric acid solution, and the real surface area of the PtRu catalysts, evaluated by Brunauer-Emmett-Teller (BET) measurements. Finally, the effectiveness for methanol oxidation is assessed by cyclic voltammetry (CV) in a sulfuric acid and methanol electrolyte.

Thiosulfoxide (Sulfane) Sulfur: New Chemistry and New Regulatory Roles in Biology

PubMed Central

Toohey, John I.; Cooper, Arthur J. L.

2014-01-01

The understanding of sulfur bonding is undergoing change. Old theories on hypervalency of sulfur and the nature of the chalcogen-chalcogen bond are now questioned. At the same time, there is a rapidly expanding literature on the effects of sulfur in regulating biological systems. The two fields are inter-related because the new understanding of the thiosulfoxide bond helps to explain the newfound roles of sulfur in biology. This review examines the nature of thiosulfoxide (sulfane, S0) sulfur, the history of its regulatory role, its generation in biological systems, and its functions in cells. The functions include synthesis of cofactors (molybdenum cofactor, iron-sulfur clusters), sulfuration of tRNA, modulation of enzyme activities, and regulating the redox environment by several mechanisms (including the enhancement of the reductive capacity of glutathione). A brief review of the analogous form of selenium suggests that the toxicity of selenium may be due to over-reduction caused by the powerful reductive activity of glutathione perselenide. PMID:25153879

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

USGS Publications Warehouse

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.

Noncompetitive and Competitive Adsorption of Heavy Metals in Sulfur-Functionalized Ordered Mesoporous Carbon.

PubMed

Saha, Dipendu; Barakat, Soukaina; Van Bramer, Scott E; Nelson, Karl A; Hensley, Dale K; Chen, Jihua

2016-12-14

In this work, sulfur-functionalized ordered mesoporous carbons were synthesized by activating the soft-templated mesoporous carbons with sulfur bearing salts that simultaneously enhanced the surface area and introduced sulfur functionalities onto the parent carbon surface. XPS analysis showed that sulfur content within the mesoporous carbons were between 8.2% and 12.9%. The sulfur functionalities include C-S, C═S, -COS, and SO x . SEM images confirmed the ordered mesoporosity within the material. The BET surface areas of the sulfur-functionalized ordered mesoporous carbons range from 837 to 2865 m 2 /g with total pore volume of 0.71-2.3 cm 3 /g. The carbon with highest sulfur functionality was examined for aqueous phase adsorption of mercury (as HgCl 2 ), lead (as Pb(NO 3 ) 2 ), cadmium (as CdCl 2 ), and nickel (as NiCl 2 ) ions in both noncompetitive and competitive mode. Under noncompetitive mode and at a pH greater than 7.0 the affinity of sulfur-functionalized carbons toward heavy metals were in the order of Hg > Pb > Cd > Ni. At lower pH, the adsorbent switched its affinity between Pb and Cd. In the noncompetitive mode, Hg and Pb adsorption showed a strong pH dependency whereas Cd and Ni adsorption did not demonstrate a significant influence of pH. The distribution coefficient for noncompetitive adsorption was in the range of 2448-4000 mL/g for Hg, 290-1990 mL/g for Pb, 550-560 mL/g for Cd, and 115-147 for Ni. The kinetics of adsorption suggested a pseudo-second-order model fits better than other models for all the metals. XPS analysis of metal-adsorption carbons suggested that 7-8% of the adsorbed Hg was converted to HgSO 4 , 14% and 2% of Pb was converted to PbSO 4 and PbS/PbO, respectively, and 5% Cd was converted to CdSO 4 . Ni was below the detection limit for XPS. Overall results suggested these carbon materials might be useful for the separation of heavy metals.

Three-Dimensionally Hierarchical Graphene Based Aerogel Encapsulated Sulfur as Cathode for Lithium/Sulfur Batteries

PubMed Central

Li, Haipeng; Sun, Liancheng; Wang, Zhuo; Zhang, Yongguang; Tan, Taizhe; Wang, Gongkai

2018-01-01

A simple and effective method was developed to obtain the electrode for lithium/sulfur (Li/S) batteries with high specific capacity and cycling durability via adopting an interconnected sulfur/activated carbon/graphene (reduced graphene oxide) aerogel (S/AC/GA) cathode architecture. The AC/GA composite with a well-defined interconnected conductive network was prepared by a reduction-induced self-assembly process, which allows for obtaining compact and porous structures. During this process, reduced graphene oxide (RGO) was formed, and due to the presence of oxygen-containing functional groups on its surface, it not only improves the electronic conductivity of the cathode but also effectively inhibits the polysulfides dissolution and shuttle. The introduced activated carbon allowed for lateral and vertical connection between individual graphene sheets, completing the formation of a stable three-dimensionally (3D) interconnected graphene framework. Moreover, a high specific surface area and 3D interconnected porous structure efficiently hosts a higher amount of active sulfur material, about 65 wt %. The designed S/AC/GA composite electrodes deliver an initial capacity of 1159 mAh g−1 at 0.1 C and can retain a capacity of 765 mAh g−1 after 100 cycles in potential range from 1 V to 3 V. PMID:29373525

X-Ray Absorption Spectroscopy As a Probe of Microbial Sulfur Biochemistry: the Nature of Bacterial Sulfur Globules Revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, G.N.; Gnida, M.; Bazylinski, D.A.

2009-05-18

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 experimentally demonstrate that the use of transmittance detection for sulfur K-edge XAS measurements is highly prone to spectroscopic distortions andmore » that much of the published work on sulfur bacteria is very likely based on distorted data. We also demonstrate that all three detection methods used for X-ray absorption experiments yield essentially identical spectra when the measurements are carried out under conditions where no experimental distortions are expected. Finally, we turn to the original question--the chemical nature of bacterial sulfur. We examine isolated sulfur globules of Allochromatium vinosum and intact cells of a strain of magnetotactic coccus and show that XAS indicates the presence of a chemical form of sulfur resembling S{sub 8}.« less

A study of the natural bitumen of the Mariel deposit (Republic of Cuba)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Platanov, V.V.; Ivleva, L.N.; Kalyavina, O.A.

The bitumen of the Mariel deposit, province of Havana, Republic of Cuba, and the products of its ozonolysis and thermal degradation have been studied by a group of physicochemical and chemical methods. It has been shown that the organic part of the bitumen has an aromatic polycondensed structure with mainly short alkyl substituents and ketone, ester, phenol, and quinoid functional groups together with organic sulfur and nitrogen.

Metagenomic resolution of microbial functions in deep-sea hydrothermal plumes across the Eastern Lau Spreading Center.

PubMed

Anantharaman, Karthik; Breier, John A; Dick, Gregory J

2016-01-01

Microbial processes within deep-sea hydrothermal plumes affect ocean biogeochemistry on global scales. In rising hydrothermal plumes, a combination of microbial metabolism and particle formation processes initiate the transformation of reduced chemicals like hydrogen sulfide, hydrogen, methane, iron, manganese and ammonia that are abundant in hydrothermal vent fluids. Despite the biogeochemical importance of this rising portion of plumes, it is understudied in comparison to neutrally buoyant plumes. Here we use metagenomics and bioenergetic modeling to describe the abundance and genetic potential of microorganisms in relation to available electron donors in five different hydrothermal plumes and three associated background deep-sea waters from the Eastern Lau Spreading Center located in the Western Pacific Ocean. Three hundred and thirty one distinct genomic 'bins' were identified, comprising an estimated 951 genomes of archaea, bacteria, eukarya and viruses. A significant proportion of these genomes is from novel microorganisms and thus reveals insights into the energy metabolism of heretofore unknown microbial groups. Community-wide analyses of genes encoding enzymes that oxidize inorganic energy sources showed that sulfur oxidation was the most abundant and diverse chemolithotrophic microbial metabolism in the community. Genes for sulfur oxidation were commonly present in genomic bins that also contained genes for oxidation of hydrogen and methane, suggesting metabolic versatility in these microbial groups. The relative diversity and abundance of genes encoding hydrogen oxidation was moderate, whereas that of genes for methane and ammonia oxidation was low in comparison to sulfur oxidation. Bioenergetic-thermodynamic modeling supports the metagenomic analyses, showing that oxidation of elemental sulfur with oxygen is the most dominant catabolic reaction in the hydrothermal plumes. We conclude that the energy metabolism of microbial communities inhabiting rising hydrothermal plumes is dictated by the underlying plume chemistry, with a dominant role for sulfur-based chemolithoautotrophy.

Environmental Compliance Assessment Army Reserve (ECAAR)

DTIC Science & Technology

1993-09-01

and water Spent mixed acid Spent caustic Spent sulfuric acid Potential Consequences: Heat generation, violent reaction. Group 2-A Group 2-B Aluminum Any...methane reforming furnaces, pulping liquor recovery furnaces, combustion devices used in the recovery of sulfur values from spent sulfuric acid...Industry and USEPA Hazardous Waste Hazard No. Hazardous Waste Code* Generic FOO1 The spent halogenated solvents used in degreasing: Trichloroethylene, (t

An endogenous microRNA (miRNA1166.1) can regulate photobio-H2 production in eukaryotic green alga Chlamydomonas reinhardtii.

PubMed

Wang, Yuting; Zhuang, Xiaoshan; Chen, Meirong; Zeng, Zhiyong; Cai, Xiaoqi; Li, Hui; Hu, Zhangli

2018-01-01

Hydrogen photoproduction from green microalgae is regarded as a promising alternative solution for energy problems. However, the simultaneous oxygen evolution from microalgae can prevent continuous hydrogen production due to the hypersensitivity of hydrogenases to oxygen. Sulfur deprivation can extend the duration of algal hydrogen production, but it is uneconomical to alternately culture algal cells in sulfur-sufficient and sulfur-deprived media. In this study, we developed a novel way to simulate sulfur-deprivation treatment while constantly maintaining microalgal cells in sulfur-sufficient culture medium by overexpressing an endogenous microRNA (miR1166.1). Based on our previous RNA-seq analysis in the model green alga Chlamydomonas reinhardtii , three endogenous miRNAs responsive to sulfur deprivation (cre-miR1166.1, cre-miR1150.3, and cre-miR1158) were selected. Heat-inducible expression vectors containing the selected miRNAs were constructed and transformed into C. reinhardtii . Comparison of H 2 production following heat induction in the three transgenic strains and untransformed control group identified miR1166.1 as the best candidate for H 2 production regulation. Moreover, enhanced photobio-H 2 production was observed with repeated induction of miR1166.1 expression. This study is the first to identify a physiological function of endogenous miR1166.1 and to show that a natural miRNA can regulate hydrogen photoproduction in the unicellular model organism C. reinhardtii .

Structural and Functional Analyses of the Proteins Involved in the Iron-Sulfur Cluster Biosynthesis

NASA Astrophysics Data System (ADS)

Wada, Kei

The iron-sulfur (Fe-S) clusters are ubiquitous prosthetic groups that are required to maintain such fundamental life processes as respiratory chain, photosynthesis and the regulation of gene expression. Assembly of intracellular Fe-S cluster requires the sophisticated biosynthetic systems called ISC and SUF machineries. To shed light on the molecular mechanism of Fe-S cluster assembly mediated by SUF machinery, several structures of the SUF components and their sub-complex were determined. The structural findings together with biochemical characterization of the core-complex (SufB-SufC-SufD complex) have led me to propose a working model for the cluster biosynthesis in the SUF machinery.

Biotransformation of nitrogen- and sulfur-containing pollutants during coking wastewater treatment: Correspondence of performance to microbial community functional structure.

PubMed

Joshi, Dev Raj; Zhang, Yu; Gao, Yinxin; Liu, Yuan; Yang, Min

2017-09-15

Although coking wastewater is generally considered to contain high concentration of nitrogen- and sulfur-containing pollutants, the biotransformation processes of these compounds have not been well understood. Herein, a high throughput functional gene array (GeoChip 5.0) in combination with Illumina MiSeq sequencing of the 16S rRNA gene were used to identify microbial functional traits and their role in biotransformation of nitrogen- and sulfur-containing compounds in a bench-scale aerobic coking wastewater treatment system operated for 488 days. Biotransformation of nitrogen and sulfur-containing pollutants deteriorated when pH of the bioreactor was increased to >8.0, and the microbial community functional structure was significantly associated with pH (Mantels test, P < 0.05). The release of ammonia nitrogen and sulfate was correlated with both the taxonomic and functional microbial community structure (P < 0.05). Considering the abundance and correlation with the release of ammonia nitrogen and sulfate, aromatic dioxygenases (e.g. xylXY, nagG), nitrilases (e.g. nhh, nitrilase), dibenzothiophene oxidase (DbtAc), and thiocyanate hydrolase (scnABC) were important functional genes for biotransformation of nitrogen- and sulfur-containing pollutants. Functional characterization of taxa and network analysis suggested that Burkholderiales, Actinomycetales, Rhizobiales, Pseudomonadales, and Hydrogenophiliales (Thiobacillus) were key functional taxa. Variance partitioning analysis showed that pH and influent ammonia nitrogen jointly explained 25.9% and 35.5% of variation in organic pollutant degrading genes and microbial community structure, respectively. This study revealed a linkage between microbial community functional structure and the likely biotransformation of nitrogen- and sulfur-containing pollutants, along with a suitable range of pH (7.0-7.5) for stability of the biological system treating coking wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biosignature detection at an Arctic analog to Europa.

PubMed

Gleeson, Damhnait F; Pappalardo, R T; Anderson, M S; Grasby, S E; Mielke, R E; Wright, K E; Templeton, A S

2012-02-01

The compelling evidence for an ocean beneath the ice shell of Europa makes it a high priority for astrobiological investigations. Future missions to the icy surface of this moon will query the plausibly sulfur-rich materials for potential indications of the presence of life carried to the surface by mobile ice or partial melt. However, the potential for generation and preservation of biosignatures under cold, sulfur-rich conditions has not previously been investigated, as there have not been suitable environments on Earth to study. Here, we describe the characterization of a range of biosignatures within potentially analogous sulfur deposits from the surface of an Arctic glacier at Borup Fiord Pass to evaluate whether evidence for microbial activities is produced and preserved within these deposits. Optical and electron microscopy revealed microorganisms and extracellular materials. Elemental sulfur (S⁰), the dominant mineralogy within field samples, is present as rhombic and needle-shaped mineral grains and spherical mineral aggregates, commonly observed in association with extracellular polymeric substances. Orthorhombic α-sulfur represents the stable form of S⁰, whereas the monoclinic (needle-shaped) γ-sulfur form rosickyite is metastable and has previously been associated with sulfide-oxidizing microbial communities. Scanning transmission electron microscopy showed mineral deposition on cellular and extracellular materials in the form of submicron-sized, needle-shaped crystals. X-ray diffraction measurements supply supporting evidence for the presence of a minor component of rosickyite. Infrared spectroscopy revealed parts-per-million level organics in the Borup sulfur deposits and organic functional groups diagnostic of biomolecules such as proteins and fatty acids. Organic components are below the detection limit for Raman spectra, which were dominated by sulfur peaks. These combined investigations indicate that sulfur mineral deposits may contain identifiable biosignatures that can be stabilized and preserved under low-temperature conditions. Borup Fiord Pass represents a useful testing ground for instruments and techniques relevant to future astrobiological exploration at Europa.

Morphology and water resistance of mixed silane films of bis[3-(triethoxysilyl) propyl]tetrasulfide and bis-[trimethoxysilylpropyl]amine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Guirong; Schaefer, Dale W.; van Ooij, Wim J.

2010-12-03

Functional organosilanes are powerful interface-active agents that find applications as adhesion promoters as well as optical, dielectric and protective coatings. Bis-silanes are of particular interest because they are highly crosslinked leading to very robust films. In almost all applications, the water resistance of the films is a critical performance measure. Here we use neutron reflectivity to address the effect of bridging group on the hydrothermal response of bis-silane films prepared using bis[3-(triethoxysilyl) propyl]tetrasulfide and bis-[trimethoxysilylpropyl]amine. Neat and mixed films are examined as-prepared, after exposure to water vapor and then in the re-dried state. The bridging group is the key factormore » that controls the morphology and water resistance of silane films. Although bis-sulfur silane is not as condensed as bis-amino silane, bis-sulfur swells less in water because of the hydrophobic nature of bridging group. The reflectivity of bis-sulfur silane film is reversible after room-temperature water conditioning but not at 80 C, indicating chemical alternation of the film at 80 C. The water resistance of mixed silane is roughly that of both components weighted by their volume fraction. But based on the enhanced shrinkage that occurs following water-vapor conditioning of the mixed film, condensation is accelerated in the mixed silane. Regarding the precursor solution, bis-amino silane may act as a catalyst in the hydrolysis of bis-sulfur silane leading to more silanols in the solution and further condensation in the film. Variation in the structure normal to the substrate is also examined by swelling the film with d-nitrobenzene, a non-reacting swelling agent.« less

Selenocysteine in Thiol/Disulfide-Like Exchange Reactions

PubMed Central

Marino, Stefano M.

2013-01-01

Abstract Significance: Among trace elements used as cofactors in enzymes, selenium is unique in that it is incorporated into proteins co-translationally in the form of an amino acid, selenocysteine (Sec). Sec differs from cysteine (Cys) by only one atom (selenium versus sulfur), yet this switch dramatically influences important aspects of enzyme reactivity. Recent Advances: The main focus of this review is an updated and critical discussion on how Sec might be used to accelerate thiol/disulfide-like exchange reactions in natural selenoenzymes, compared with their Cys-containing homologs. Critical Issues: We discuss in detail three major aspects associated with thiol/disulfide exchange reactions: (i) nucleophilicity of the attacking thiolate (or selenolate); (ii) electrophilicity of the center sulfur (or selenium) atom; and (iii) stability of the leaving group (sulfur or selenium). In all these cases, we analyze the benefits that selenium might provide in these types of reactions. Future Directions: It is the biological thiol oxidoreductase-like function that benefits from the use of Sec, since Sec functions to chemically accelerate the rate of these reactions. We review various hypotheses that could help explain why Sec is used in enzymes, particularly with regard to competitive chemical advantages provided by the presence of the selenium atom in enzymes. Ultimately, these chemical advantages must be connected to biological functions of Sec. Antioxid. Redox Signal. 18, 1675–1689. PMID:23121622

Chemical composition of asphaltenes of crude oil from Baradero field in Cuba

DOE Office of Scientific and Technical Information (OSTI.GOV)

Platonov, V.V.; Proskuryakov, V.A.; Klyavina, O.A.

Asphaltenes of crude oil from Baradero field in Cuba have been studied by physical and physicochemical methods. Dynamics of distribution of nitrogen, sulfur, and oxygen and also various functional groups in asphaltenes has been described. These data can be used for the proper deasphalting of crude oil and further treatment of asphaltenes.

Cu(ii)-catalyzed sulfide construction: both aryl groups utilization of intermolecular and intramolecular diaryliodonium salt.

PubMed

Wang, Ming; Wei, Jianpeng; Fan, Qiaoling; Jiang, Xuefeng

2017-03-07

A sulfur-iodine exchange protocol of diaryliodonium salts with inorganic sulfur salt was developed. Both aryl groups in the diaryliodonium salt were fully exerted in this transformation. Five- to eight-membered sulfur-containing heterocycles were achieved. Note that [1]benzothieno-[3,2-b][1]benzothiophene (BTBT) (an organic field-effect transistor (OFET) material) and Zaltoprofen were efficiently established through this method.

Metal-sulfur type cell having improved positive electrode

DOEpatents

Dejonghe, Lutgard C.; Visco, Steven J.; Mailhe, Catherine C.; Armand, Michel B.

1989-01-01

An novel metal-sulfur type cell operable at a temperature of 200.degree. C. or less with an energy density of 150 Whrs/Kg or better is disclosed characterized by an organo-sulfur cathode formed from an organic-sulfur compound having the general formula, in its charged state, of (R(S).sub.y).sub.n wherein y=1 to 6; n=2 to 20; and R is one or more different aliphatic or aromatic organic moieties having 1 to 20 carbon atoms, which may include one or more oxygen, sulfur, or nitrogen heteroatoms when R comprisises one of more aromatic rings, or one or more oxygen, sulfur, nitrogen, or fluorine atoms associtated with the chain when R comprises an aliphatic chain, wherein the aliphatic group may be linear or branched, saturated or unsaturated, and wherein either the aliphatic chain or the aromatic ring may have substituted groups thereon.

Metal-sulfur type cell having improved positive electrode

DOEpatents

DeJonghe, L.C.; Visco, S.J.; Mailhe, C.C.; Armand, M.B.

1988-03-31

A novel metal-sulfur type cell operable at a temperature of 200/degree/C or less with an energy density of 150 Whrs/Kg or better is disclosed characterized by an organo-sulfur cathode formed from an organic-sulfur compound having the general formula, in its charged state, of (R(S)/sub y/)n wherein y = 1 to 6; n = 2 to 20; and R is one or more different aliphatic or aromatic organic moieties having 1 to 20 carbon atoms, which may include one or more oxygen, sulfur, or nitrogen heteroatoms when R comprises one or more aromatic rings, or one or more oxygen, sulfur, nitrogen, or fluorine atoms associated with the chain when R comprises an aliphatic chain, wherein the aliphatic group may be linear or branched, saturated or unsaturated, and wherein either the aliphatic chain or the aromatic ring may have substituted groups thereon. 4 figs.

Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers

NASA Technical Reports Server (NTRS)

Blankenship, R. E.

1994-01-01

Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.

Preparation of surface-functionalized porous clay heterostructures via carbonization of soft-template and their adsorption performance for toluene

NASA Astrophysics Data System (ADS)

Wang, Yuebo; Su, Xiaoli; Xu, Zhen; Wen, Ke; Zhang, Ping; Zhu, Jianxi; He, Hongping

2016-02-01

A new type of surface-functionalized porous clay heterostructures (SF-PCH) was synthesized via carbonization of the template agents with sulfuric acid. The converted carbons deposited on the porous surface of the SF-PCH samples and changed their surface chemical properties. The composites possessed a maximum carbon content of 5.35%, a large specific surface area of 428 m2/g and micropore volume of approximately 0.2 cm3/g. The layered and porous structure of SF-PCH was retained after carbonization and calcination when sulfuric acid solution with a mild concentration was used. Analysis by XPS confirmed that the carbonaceous matter in the pore channels was functionalized with various organic groups, including carbonaceous, nitrogenous, and sulfated groups. Both the surface chemical property and structural characteristic of adsorbents have effects on the adsorption properties of SF-PCH for toluene. The SF-PCH samples exhibited a stronger adsorption affinity to toluene compared with untreated PCH in the low pressure region, which is more valuable in the practical applications. These results demonstrate that carbonization of soft-template is a feasible process for the surface modification of PCH, enabling the resulting composites to become promising candidates for application in toluene emission control.

Chemical Immobilization Effect on Lithium Polysulfides for Lithium-Sulfur Batteries.

PubMed

Li, Caixia; Xi, Zhucong; Guo, Dexiang; Chen, Xiangju; Yin, Longwei

2018-01-01

Despite great progress in lithium-sulfur batteries (LSBs), great obstacles still exist to achieve high loading content of sulfur and avoid the loss of active materials due to the dissolution of the intermediate polysulfide products in the electrolyte. Relationships between the intrinsic properties of nanostructured hosts and electrochemical performance of LSBs, especially, the chemical interaction effects on immobilizing polysulfides for LSB cathodes, are discussed in this Review. Moreover, the principle of rational microstructure design for LSB cathode materials with strong chemical interaction adsorbent effects on polysulfides, such as metallic compounds, metal particles, organic polymers, and heteroatom-doped carbon, is mainly described. According to the chemical immobilizing mechanism of polysulfide on LSB cathodes, three kinds of chemical immobilizing effects, including the strong chemical affinity between polar host and polar polysulfides, the chemical bonding effect between sulfur and the special function groups/atoms, and the catalytic effect on electrochemical reaction kinetics, are thoroughly reviewed. To improve the electrochemical performance and long cycling life-cycle stability of LSBs, possible solutions and strategies with respect to the rational design of the microstructure of LSB cathodes are comprehensively analyzed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

PubMed Central

Reinelt, Sebastian; Steinke, Daniel

2014-01-01

Summary In this work we report the synthesis of thermo-, oxidation- and cyclodextrin- (CD) responsive end-group-functionalized polymers, based on N,N-diethylacrylamide (DEAAm). In a classical free-radical chain transfer polymerization, using thiol-functionalized 4-alkylphenols, namely 3-(4-(1,1-dimethylethan-1-yl)phenoxy)propane-1-thiol and 3-(4-(2,4,4-trimethylpentan-2-yl)phenoxy)propane-1-thiol, poly(N,N-diethylacrylamide) (PDEAAm) with well-defined hydrophobic end-groups is obtained. These end-group-functionalized polymers show different cloud point values, depending on the degree of polymerization and the presence of randomly methylated β-cyclodextrin (RAMEB-CD). Additionally, the influence of the oxidation of the incorporated thioether linkages on the cloud point is investigated. The resulting hydrophilic sulfoxides show higher cloud point values for the lower critical solution temperature (LCST). A high degree of functionalization is supported by 1H NMR-, SEC-, FTIR- and MALDI–TOF measurements. PMID:24778720

Functional thiols as repair and doping agents of defective MoS2 monolayers

NASA Astrophysics Data System (ADS)

Förster, Anja; Gemming, Sibylle; Seifert, Gotthard

2018-06-01

Recent experimental and theoretical studies indicate that thiols (R-SH) can be used to repair sulfur vacancy defects in MoS2 monolayers (MLs). This density functional theory study investigates how the thiol repair mechanism process can be used to dope MoS2 MLs. Fluorinated thiols as well as amine-containing ones are used to p- and n-dope the MoS2 ML, respectively. It is shown that functional groups are only physisorbed on the repaired MoS2 surface. This explains the reversible doping with fluorinated thiols.

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

PubMed Central

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

N and S co-doped porous carbon spheres prepared using L-cysteine as a dual functional agent for high-performance lithium-sulfur batteries.

PubMed

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

2015-12-28

Nitrogen and sulfur co-doped porous carbon spheres (NS-PCSs) were prepared using L-cysteine to control the structure and functionalization during the hydrothermal reaction of glucose and the subsequent activation process. As the sulfur hosts in Li-S batteries, NS-PCSs combine strong physical confinement and surface chemical interaction to improve the affinity of polysulfides to the carbon matrix.

Toxicology of sulfur in ruminants: review

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 sulfurmore » leads to toxic effects. 53 references, 1 table.« less

Marine bacteria from the Roseobacter clade produce sulfur volatiles via amino acid and dimethylsulfoniopropionate catabolism.

PubMed

Brock, Nelson L; Menke, Markus; Klapschinski, Tim A; Dickschat, Jeroen S

2014-07-07

Dimethylsulfoniopropionate (DMSP) is a versatile sulfur source for the production of sulfur-containing secondary metabolites by marine bacteria from the Roseobacter clade. (34)S-labelled DMSP and cysteine, and several DMSP derivatives with modified S-alkyl groups were synthesised and used in feeding experiments that gave insights into the biosynthesis of sulfur volatiles from these bacteria.

Polymer blend compositions and methods of preparation

DOEpatents

Naskar, Amit K.

2016-09-27

A polymer blend material comprising: (i) a first polymer containing hydrogen bond donating groups having at least one hydrogen atom bound to a heteroatom selected from oxygen, nitrogen, and sulfur, or an anionic version of said first polymer wherein at least a portion of hydrogen atoms bound to a heteroatom is absent and replaced with at least one electron pair; (ii) a second polymer containing hydrogen bond accepting groups selected from nitrile, halogen, and ether functional groups; and (iii) at least one modifying agent selected from carbon particles, ether-containing polymers, and Lewis acid compounds; wherein, if said second polymer contains ether functional groups, then said at least one modifying agent is selected from carbon particles and Lewis acid compounds. Methods for producing the polymer blend, molded forms thereof, and articles thereof, are also described.

Sulfur fumigation reducing systemic exposure of ginsenosides and weakening immunomodulatory activity of ginseng.

PubMed

Ma, Bin; Kan, Winnie Lai Ting; Zhu, He; Li, Song-Lin; Lin, Ge

2017-01-04

Ginseng (Ginseng Radix et Rhizoma) is used worldwide for its miracle tonic effects, especially for its immunomodulatory activities. Sulfur fumigation, a fast and convenient method to prevent pesticidal and bacterial contamination in the food industry, has been recently employed during post-harvest processing of ginseng. Our previous studies demonstrated that sulfur fumigation significantly altered the chemical profile of the bioactive ingredients in ginseng. However, the effects of sulfur fumigation on the pharmacokinetics and bioactivities of ginseng remain unknown. To examine the effects of sulfur fumigation on the pharmacokinetics and immunomodulatory activities of ginseng. For pharmacokinetic studies, male Sprague-Dawley rats exposed to single/multiple dosages of non-fumigated ginseng (NFG) and sulfur fumigated ginseng (SFG) were investigated using HPLC-MS/MS analysis. For bioactivity studies, male ICR mice were used to compare the immunomodulatory effects of NFG or SFG under both normal and cyclophosphamide (CY)-induced immunocompromised conditions using white blood cell counts, serum cytokine levels, and spleen and thymus weight indices. Sulfur fumigation significantly reduced the contents of the bioactive ginsenosides in ginseng, which resulted in drastically low systemic exposure of ginsenosides in SFG-treatment group compared to NFG-treatment group. This observation was consistent with the bioactivities obtained in NFG- and SFG-treatment groups. The bioactivity studies also demonstrated the immunomodulatory effects of NFG but not SFG in the CY-induced immunosuppressed mice. Sulfur fumigation significantly reduced contents of bioactive ginsenosides in ginseng, leading to dramatic decrease in the systemic exposure of these ginsenosides in the body and detrimental reduction of immunomodulatory effects of ginseng. Our results provided scientific evidences and laid a solid foundation for the needs of thorough evaluation of the significant impact of sulfur fumigation on ginseng and other medicinal herbs. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Effect of Dietary Processed Sulfur Supplementation on Texture Quality, Color and Mineral Status of Dry-cured Ham.

PubMed

Kim, Ji-Han; Ju, Min-Gu; Yeon, Su-Jung; Hong, Go-Eun; Park, WooJoon; Lee, Chi-Ho

2015-01-01

This study was performed to investigate the chemical composition, mineral status, oxidative stability, and texture attributes of dry-cured ham from pigs fed processed sulfur (S, 1 g/kg feed), and from those fed a basal diet (CON), during the period from weaning to slaughter (174 d). Total collagen content and soluble collagen of the S group was significantly higher than that of the control group (p<0.05). The pH of the S group was significantly higher than that of the control group, whereas the S group had a lower expressible drip compared to the control group. The S group also showed the lower lightness compared to the control group (p<0.05). In regard to the mineral status, the S group had significantly lower Fe(2+) and Ca(2+) content than the control group (p<0.05), whereas the proteolysis index of the S group was significantly increased compared to the control group (p<0.05). The feeding of processed sulfur to pigs led to increased oxidative stability, related to lipids and pigments, in the dry-cured ham (p<0.05). Compared to the dry-cured ham from the control group, that from the S group exhibited lower springiness and gumminess; these results suggest that feeding processed sulfur to pigs can improve the quality of the texture and enhance the oxidative stability of dry-cured ham.

Selective sulfur dioxide adsorption on crystal defect sites on an isoreticular metal organic framework series

PubMed Central

Rodríguez-Albelo, L. Marleny; López-Maya, Elena; Hamad, Said; Ruiz-Salvador, A. Rabdel; Calero, Sofia; Navarro, Jorge A.R.

2017-01-01

The widespread emissions of toxic gases from fossil fuel combustion represent major welfare risks. Here we report the improvement of the selective sulfur dioxide capture from flue gas emissions of isoreticular nickel pyrazolate metal organic frameworks through the sequential introduction of missing-linker defects and extra-framework barium cations. The results and feasibility of the defect pore engineering carried out are quantified through a combination of dynamic adsorption experiments, X-ray diffraction, electron microscopy and density functional theory calculations. The increased sulfur dioxide adsorption capacities and energies as well as the sulfur dioxide/carbon dioxide partition coefficients values of defective materials compared to original non-defective ones are related to the missing linkers enhanced pore accessibility and to the specificity of sulfur dioxide interactions with crystal defect sites. The selective sulfur dioxide adsorption on defects indicates the potential of fine-tuning the functional properties of metal organic frameworks through the deliberate creation of defects. PMID:28198376

Elemental sulfur in Eddy County, New Mexico

USGS Publications Warehouse

Hinds, Jim S.; Cunningham, Richard R.

1970-01-01

Sulfur has been reported in Eddy County, N. Mex., in rocks ranging from Silurian to Holocene in age at depths of 0-15,020 feet. Targets of present exploration are Permian formations in the Delaware Basin and northwest shelf areas at depths of less than 4,000 feet. Most of the reported sulfur occurrences in the shelf area are in the 'Abo' (as used by some subsurface geologists), Yeso, and San Andres Formations and the Artesia Group. Sulfur deposition in the dense dolomites of the 'Abo,' Yeso, and San Andres Formations is attributed to the reduction of ionic sulfate by hydrogen sulfide in formation waters in zones of preexisting porosity and permeability. A similar origin accounts for most of the sulfur deposits in the formations of the Artesia Group, but some of the sulfur in these formations may have originated in place through the alteration of anhydrite to carbonate and sulfur by the metabolic processes of bacteria in the presence of hydrocarbons. Exploration in the Delaware Basin area is directed primarily toward the Castile Formation. Sulfur deposits in the Castile Formation are found in irregular masses of cavernous brecciated secondary carbonate rock enveloped by impermeable anhydrite. The carbonate masses, or 'castiles,' probably originated as collapse features resulting from subsurface solution and upward stopping. Formation of carbonate rock and sulfur in the castiles is attributed to the reduction of brecciated anhydrite by bacteria and hydrocarbons in the same process ascribed to the formation of carbonate and sulfur in the caprocks of salt domes.

A comparative study between 10 per cent sulfur ointment and 0.3 per cent gamma benzene hexachloride gel in the treatment of scabies in children.

PubMed

Singalavanija, Srisupalak; Limpongsanurak, Wanida; Soponsakunkul, Siritorn

2003-08-01

Scabies is a common contagious skin disease in children. Treatment of scabies in infants and children is the subject of worldwide concern because of risk and benefit of the variety of scabicides. To compare the efficacy of 10 per cent sulfur ointment and 0.3 per cent gamma benzene hexachloride gel for the treatment of scabies in children. A randomized investigator blind study was conducted to compare the efficacy of 10 per cent sulfur ointment and 0.3 per cent gamma benzene hexachloride (GBH) for the treatment of scabies in children at Queen Sirikit National Institute of Child Health from December 1999 to May 2000. Diagnosis was made by the clinical signs of excoriated papules in the classic distribution with nocturnal pruritus and family history of similar symptoms. Diagnosis for all patients was confirmed by positive skin scrapings for eggs, larva, mites or fecal pellets by light microscopy. Patients were followed-up at intervals of 2 and 4 weeks. One hundred children with an age range from 6 months to 13 years were randomized into 2 groups, 10 per cent sulfur group (50 cases) and 0.3 per cent GBH (50 cases). Age, sex, history of contact cases and clinical manifestations were not statistically different between the two groups. After 4 weeks of treatment, there were no statistical differences between the two groups in patients assessed cured (92% vs 94%), clinical cure (92% vs 91%) and parasitic cure (83% vs 84%). The adverse effect of foul odor in the sulfur group was more common than in the GBH group (p < 0.05). 10 per cent sulfur ointment is as safe and efficacious as 0.3 per cent GBH for the treatment of scabies in children.

Microbial life in cold, sulfur-rich environments: Investigations of an Arctic ecosystem and implications for life detection at Europa

NASA Astrophysics Data System (ADS)

Gleeson, Damhnait Fagan

2009-12-01

Exobiological investigations require a detailed understanding of life's interactions with its environment here on Earth before we can confidently recognize signs of these interactions at other worlds such as Europa. Using a cold, sulfur-based ecosystem at Borup Fiord pass in the Canadian High Arctic as a study site, I investigated how the supraglacial non-ice materials are represented across different scales in spectral data, how microbiology is influencing the mineralogy of the site, and whether the products of microbial sulfide oxidation preserve indications of their biogenic origin. A systematic scale-integrated approach was applied to query orbital (Hyperion), field, and laboratory spectra to identify sulfur-rich materials precipitated on a glacier. While sulfur, the main constituent of the deposits, is well represented in Hyperion data, minor constituents such as calcite and gypsum are partially or entirely masked. Absorption features of sulfates, where present, are shifted in wavelength due to the effects of mixing or temperature. Autonomous detection methods were successfully applied to monitor the generation and extent of the deposits, which show spectral similarities to Europa's non-ice materials. Geomicrobiological cultivation of sulfide oxidizing bacteria succeeded in demonstrating that the microbiological community present at the site has the potential to catalyze the generation of sulfur deposits. Sulfur generated in culture is present as biomineralized structures comprised of microbial filaments and sheaths along which sulfur globules are deposited. Consortia producing these structures are dominated by gamma-Proteobacteria closely related to Marinobacter, not previously known to oxidize sulfide. The sulfur structures produced by these consortia are not observed in abiotic controls and have the potential to serve as morphological biosignatures. Investigations into the biogenicity of field deposits reveal mineral assemblages with similar morphologies to those generated in culture. X-ray diffraction analyses show some evidence for rosickyite, a metastable form of biogenic sulfur. Mid-infrared laboratory spectroscopy also indicates the presence of organic functional groups diagnostic of proteins and fatty acids within the sulfur deposits. These combined investigations suggest that sulfur minerals extruded onto Europa's near surface, analogous to those of Borup Fiord pass, have the potential to contain identifiable biosignatures which low-temperature conditions could help stabilize and preserve.

Rhodanese Functions as Sulfur Supplier for Key Enzymes in Sulfur Energy Metabolism

PubMed Central

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

2012-01-01

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

Sulfur in Distillers Grains for Dairy Cattle

USDA-ARS?s Scientific Manuscript database

Sulfur is an essential element needed by animals for many functions. About 0.15% of the body weight is sulfur. It is found in the amino acids methionine, cysteine, cystine, homocysteine, and taurine; in chondroitin sulfate of cartilage; and in the B-vitamins, thiamin and biotin. Methionine, thiam...

New insight of high temperature oxidation on self-exfoliation capability of graphene oxide.

PubMed

Liu, Yuhang; Zeng, Jie; Han, Di; Wu, Kai; Yu, Bowen; Chai, Songgang; Chen, Feng; Fu, Qiang

2018-05-04

The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (step I oxidation) and high temperature oxidation at 98 °C (step II oxidation). However, the effects of these two steps on the exfoliation capability and chemical structure of graphite oxide remain unclear. In this study, both the functional group content of graphite oxide and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes. The prepared graphite oxide can be easily self-exfoliated but contains a lot of organic sulfur. During the first 20 min of step II oxidation, the majority of organic sulfur can be efficiently removed and graphite oxide still remains a good exfoliation capability due to sharp increasing of carboxyl groups. However, with a longer oxidation time at step II oxidation, the decrease of organic sulfur content is slowed down apparently but without any carboxyl groups forming, then graphite oxide finally loses self-exfoliation capability. It is concluded that a short time of step II oxidation can produce purer and ultralarge GO sheets via self-exfoliation. The pure GO is possessed with better thermal stability and liquid crystal behavior. Besides, reduced GO films prepared from step II oxidation show better mechanical and electric properties after reducing compared with that obtained only via step I oxidation.

New insight of high temperature oxidation on self-exfoliation capability of graphene oxide

NASA Astrophysics Data System (ADS)

Liu, Yuhang; Zeng, Jie; Han, Di; Wu, Kai; Yu, Bowen; Chai, Songgang; Chen, Feng; Fu, Qiang

2018-05-01

The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (step I oxidation) and high temperature oxidation at 98 °C (step II oxidation). However, the effects of these two steps on the exfoliation capability and chemical structure of graphite oxide remain unclear. In this study, both the functional group content of graphite oxide and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes. The prepared graphite oxide can be easily self-exfoliated but contains a lot of organic sulfur. During the first 20 min of step II oxidation, the majority of organic sulfur can be efficiently removed and graphite oxide still remains a good exfoliation capability due to sharp increasing of carboxyl groups. However, with a longer oxidation time at step II oxidation, the decrease of organic sulfur content is slowed down apparently but without any carboxyl groups forming, then graphite oxide finally loses self-exfoliation capability. It is concluded that a short time of step II oxidation can produce purer and ultralarge GO sheets via self-exfoliation. The pure GO is possessed with better thermal stability and liquid crystal behavior. Besides, reduced GO films prepared from step II oxidation show better mechanical and electric properties after reducing compared with that obtained only via step I oxidation.

Effect of Acid on Surface Hydroxyl Groups on Kaolinite and Montmorillonite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sihvonen, Sarah K.; Murphy, Kelly A.; Washton, Nancy M.

Mineral dust aerosol participates in heterogeneous chemistry in the atmosphere. In particular, the hydroxyl groups on the surface of aluminosilicate clay minerals are important for heterogeneous atmospheric processes. These functional groups may be altered by acidic processing during atmospheric transport. In this study, we exposed kaolinite (KGa-1b) and montmorillonite (STx-1b) to aqueous sulfuric acid and then rinsed the soluble reactants and products off in order to explore changes to functional groups on the mineral surface. To quantify the changes due to acid treatment of edge hydroxyl groups, we use 19F magic angle spinning nuclear magnetic resonance spectroscopy and a probemore » molecule, 3,3,3-trifluoropropyldimethylchlorosilane. We find that the edge hydroxyl groups (OH) increase in both number and density with acid treatment. Chemical reactions in the atmosphere may be impacted by the increase in OH at the mineral edge.« less

Wound Healing of Cutaneous Sulfur Mustard Injuries

PubMed Central

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 mustard injuries. Current treatment strategy consists of symptomatic management and is designed to relieve symptoms, prevent infections, and promote healing. There are currently no standardized or optimized methods of casualty management that prevent or minimize deficits and provide for speedy wound healing. Several laboratories are actively searching for improved therapies for cutaneous vesicant injury, with the aim of returning damaged skin to optimal appearance and normal function in the shortest time. Improved treatment will result in a better cosmetic and functional outcome for the patient, and will enable the casualty to return to normal activities sooner. This editorial gives brief overviews of sulfur mustard use, its toxicity, concepts for medical countermeasures, current treatments, and strategies for the development of improved therapies. PMID:16921406

Speciation of sulfur from filamentous microbial mats from sulfidic cave springs using X-ray absorption near-edge spectroscopy.

PubMed

Engel, Annette Summers; Lichtenberg, Henning; Prange, Alexander; Hormes, Josef

2007-04-01

Most transformations within the sulfur cycle are controlled by the biosphere, and deciphering the abiotic and biotic nature and turnover of sulfur is critical to understand the geochemical and ecological changes that have occurred throughout the Earth's history. Here, synchrotron radiation-based sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to examine sulfur speciation in natural microbial mats from two aphotic (cave) settings. Habitat geochemistry, microbial community compositions, and sulfur isotope systematics were also evaluated. Microorganisms associated with sulfur metabolism dominated the mats, including members of the Epsilonproteobacteria and Gammaproteobacteria. These groups have not been examined previously by sulfur K-edge XANES. All of the mats consisted of elemental sulfur, with greater contributions of cyclo-octasulfur (S8) compared with polymeric sulfur (Smicro). While this could be a biological fingerprint for some bacteria, the signature may also indicate preferential oxidation of Smicro and S8 accumulation. Higher sulfate content correlated to less S8 in the presence of Epsilonproteobacteria. Sulfur isotope compositions confirmed that sulfur content and sulfur speciation may not correlate to microbial metabolic processes in natural samples, thereby complicating the interpretation of modern and ancient sulfur records.

Functional Differentiation of Three Pores for Effective Sulfur Confinement in Li-S Battery.

PubMed

Wang, Qian; Yang, Minghui; Wang, Zhen-Bo; Li, Chao; Gu, Da-Ming

2018-03-01

Shuttle effect of the dissolved intermediates is regarded as the primary cause that leads to fast capacity degradation of Li-S battery. Herein, a microporous carbon-coated sulfur composite with novel rambutan shape (R-S@MPC) is synthesized from microporous carbon-coated rambutan-like zinc sulfide (R-ZnS@MPC), via an in situ oxidation process. The R-ZnS is employed as both template and sulfur precursor. The carbon frame of R-S@MPC composite possesses three kinds of pores that are distinctly separated from each other in space and are endowed with the exclusive functions. The central macropore serves as buffer pool to accommodate the dissolved lithium polysulfides (LPSs) and volumetric variation during cycling. The marginal straight-through mesoporous, connected with the central macropore, takes the responsibility of sulfur storage. The micropores, evenly distributed in the outer carbon shell of the as-synthesized R-S@MPC, enable the blockage of LPSs. These pores are expected to perform their respective single function, and collaborate synergistically to suppress the sulfur loss. Therefore, it delivers an outstanding cycling stability, decay rate of 0.013% cycle -1 after 500 cycles at 1 C, when the sulfur loading is kept at 4 mg cm -2 . © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sulfuric Acid and Water: Paradoxes of Dilution

ERIC Educational Resources Information Center

Leenson, I. A.

2004-01-01

On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…

Effect of sulfuric acid concentration of bentonite and calcination time of pillared bentonite

NASA Astrophysics Data System (ADS)

Mara, Ady; Wijaya, Karna; Trisunaryati, Wega; Mudasir

2016-04-01

An activation of natural clay has been developed. Activation was applied by refluxing the natural bentonite in variation of the sulfuric acid concentration and calcination time of pillared bentonite (PLC). Calcination was applied using oven in microwave 2,45 GHz. Determination of acidity was applied by measuring the amount of adsorbed ammonia and pyridine. Morphological, functional groups and chrystanility characterizations were analyzed using SEM, TEM, FTIR and XRD. Porosity was analyzed using SSA. The results showed that the greater of the concentration of sulfuric acid and calcination time was, the greater the acidity of bentonite as well as the pore diameter were. FTIR spectra showed no fundamental changes in the structure of the natural bentonite, SEM, and TEM images were showing an increase in space or field due to pillarization while the XRD patterns showed a shift to a lower peak. Optimization was obtained at a concentration of 2 M of sulfuric acid and calcination time of 20 minutes, keggin ion of 2.2 and suspension of 10 mmol, respectively each amounted to 11.7490 mmol/gram of ammonia and 2.4437 mmol/gram of pyridine with 154.6391 m2/gram for surface area, 0.130470 m3/gram of pore volume and 3.37484 nm of pore diameter.

Biosynthesis of Sulfur-Containing tRNA Modifications: A Comparison of Bacterial, Archaeal, and Eukaryotic Pathways

PubMed Central

Čavužić, Mirela; Liu, Yuchen

2017-01-01

Post-translational tRNA modifications have very broad diversity and are present in all domains of life. They are important for proper tRNA functions. In this review, we emphasize the recent advances on the biosynthesis of sulfur-containing tRNA nucleosides including the 2-thiouridine (s2U) derivatives, 4-thiouridine (s4U), 2-thiocytidine (s2C), and 2-methylthioadenosine (ms2A). Their biosynthetic pathways have two major types depending on the requirement of iron–sulfur (Fe–S) clusters. In all cases, the first step in bacteria and eukaryotes is to activate the sulfur atom of free l-cysteine by cysteine desulfurases, generating a persulfide (R-S-SH) group. In some archaea, a cysteine desulfurase is missing. The following steps of the bacterial s2U and s4U formation are Fe–S cluster independent, and the activated sulfur is transferred by persulfide-carrier proteins. By contrast, the biosynthesis of bacterial s2C and ms2A require Fe–S cluster dependent enzymes. A recent study shows that the archaeal s4U synthetase (ThiI) and the eukaryotic cytosolic 2-thiouridine synthetase (Ncs6) are Fe–S enzymes; this expands the role of Fe–S enzymes in tRNA thiolation to the Archaea and Eukarya domains. The detailed reaction mechanisms of Fe–S cluster depend s2U and s4U formation await further investigations. PMID:28287455

Nitrogen and sulfur Co-doped microporous activated carbon macro-spheres for CO2 capture.

PubMed

Sun, Yahui; Li, Kaixi; Zhao, Jianghong; Wang, Jianlong; Tang, Nan; Zhang, Dongdong; Guan, Taotao; Jin, Zuer

2018-04-27

Millimeter-sized nitrogen and sulfur co-doped microporous activated carbon spheres (NSCSs) were first synthesized from poly(styrene-vinylimidazole-divinylbenzene) resin spheres through concentrated H 2 SO 4 sulfonation, carbonization and KOH activation. Styrene (ST) and N-vinylimidazole (VIM) were carbon and nitrogen sources, while the sulfonic acid functional groups introduced by the simple concentrated sulfuric acid sulfonation worked simultaneously as cross-linking agent and sulfur source during the following thermal treatments. It was found that the surface chemistries, textural structures, and CO 2 adsorption performances of the NSCSs were significantly affected by the addition of VIM. The NSCS-4-700 sample with a molar ratio of ST: VIM = 1: 0.75 showed the best CO 2 uptake at different temperatures and pressures. An exhaustive adsorption evaluation indicated that CO 2 sorption at low pressures originated from the synergistic effect of surface chemistry and micropores below 8.04 Å, while at the moderate pressure of 8.0 bar, CO 2 uptake was dominated by the volume of micropores. The thermodynamics suggested the exothermic and orderly nature of the adsorption process, which was dominated by a physisorption mechanism. The high CO 2 adsorption capacity, fast kinetic adsorption rate, and great regeneration stability of the nitrogen and sulfur co-doped activated carbon spheres indicated that the as-prepared carbon adsorbents were good candidates for large-scale CO 2 capture. Copyright © 2018 Elsevier Inc. All rights reserved.

Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

PubMed Central

Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

2015-01-01

We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

Adsorptive separation of CO 2 in sulfur-doped nanoporous carbons: Selectivity and breakthrough simulation

DOE PAGES

Saha, Dipendu; Orkoulas, Gerassimos; Chen, Jihua; ...

2017-03-01

In this research, we have synthesized two sulfur functionalized nanoporous carbons by post-synthesis modifications with sulfur bearing activating agents that simultaneously enhanced the surface area and introduced sulfur functionalities on the carbon surface. The Brunauer–Emmett–Teller (BET) surface areas of these materials were 2865 and 837 m 2/g with total sulfur contents of 8.2 and 12.9 %, respectively. The sulfur-functionalized carbons were characterized with pore textural properties, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and electron microscopy (SEM and TEM). In both the carbons, CO 2 adsorption isotherms and kinetics were measured in three different temperatures of 298, 288 and 278more » K and pressures up to 760 torr. The gravimetric CO 2 uptake followed the trend with BET surface area but the surface area-based uptake was reversed and it followed the trend of sulfur content. The heat of adsorption of CO 2 in low uptake was 60-65 kJ/mol, which is the highest for CO 2 adsorption in porous carbons. In order to investigate the adsorptive separation of CO 2, N 2 and CH 4 adsorption isotherms were also measured at 298 K and 760 torr. The selectivity of separation for CO 2/N 2 and CO 2/CH 4 was calculated based on the Ideal Adsorbed Solution Theory (IAST) and all the results demonstrated the high CO 2 selectivity for the carbon with higher sulfur content. The adsorption isotherms were combined with mass balances to calculate the breakthrough behavior of the binary mixtures of CO 2/N 2 and CO 2/CH 4. The simulation results demonstrated that the dimensionless breakthrough time is a decreasing function of the mole fraction of CO 2 in the feed stream. The overall results suggest that the sulfurfunctionalized carbons can be employed as potential adsorbents for CO 2 separation.« less

Molecular characterization of anaerobic sulfur-oxidizing microbial communities in up-flow anaerobic sludge blanket reactor treating municipal sewage.

PubMed

Aida, Azrina A; Hatamoto, Masashi; Yamamoto, Masamitsu; Ono, Shinya; Nakamura, Akinobu; Takahashi, Masanobu; Yamaguchi, Takashi

2014-11-01

A novel wastewater treatment system consisting of an up-flow anaerobic sludge blanket (UASB) reactor and a down-flow hanging sponge (DHS) reactor with sulfur-redox reaction was developed for treatment of municipal sewage under low-temperature conditions. In the UASB reactor, a novel phenomenon of anaerobic sulfur oxidation occurred in the absence of oxygen, nitrite and nitrate as electron acceptors. The microorganisms involved in anaerobic sulfur oxidation have not been elucidated. Therefore, in this study, we studied the microbial communities existing in the UASB reactor that probably enhanced anaerobic sulfur oxidation. Sludge samples collected from the UASB reactor before and after sulfur oxidation were used for cloning and terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA genes of the bacterial and archaeal domains. The microbial community structures of bacteria and archaea indicated that the genus Smithella and uncultured bacteria within the phylum Caldiserica were the dominant bacteria groups. Methanosaeta spp. was the dominant group of the domain archaea. The T-RFLP analysis, which was consistent with the cloning results, also yielded characteristic fingerprints for bacterial communities, whereas the archaeal community structure yielded stable microbial community. From these results, it can be presumed that these major bacteria groups, genus Smithella and uncultured bacteria within the phylum Caldiserica, probably play an important role in sulfur oxidation in UASB reactors. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

In Vivo Studies in Rhodospirillum rubrum Indicate That Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) Catalyzes Two Obligatorily Required and Physiologically Significant Reactions for Distinct Carbon and Sulfur Metabolic Pathways*♦

PubMed Central

Dey, Swati; North, Justin A.; Sriram, Jaya; Evans, Bradley S.; Tabita, F. Robert

2015-01-01

All organisms possess fundamental metabolic pathways to ensure that needed carbon and sulfur compounds are provided to the cell in the proper chemical form and oxidation state. For most organisms capable of using CO2 as sole source of carbon, ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes primary carbon dioxide assimilation. In addition, sulfur salvage pathways are necessary to ensure that key sulfur-containing compounds are both available and, where necessary, detoxified in the cell. Using knock-out mutations and metabolomics in the bacterium Rhodospirillum rubrum, we show here that Rubisco concurrently catalyzes key and essential reactions for seemingly unrelated but physiologically essential central carbon and sulfur salvage metabolic pathways of the cell. In this study, complementation and mutagenesis studies indicated that representatives of all known extant functional Rubisco forms found in nature are capable of simultaneously catalyzing reactions required for both CO2-dependent growth as well as growth using 5-methylthioadenosine as sole sulfur source under anaerobic photosynthetic conditions. Moreover, specific inactivation of the CO2 fixation reaction did not affect the ability of Rubisco to support anaerobic 5-methylthioadenosine metabolism, suggesting that the active site of Rubisco has evolved to ensure that this enzyme maintains both key functions. Thus, despite the coevolution of both functions, the active site of this protein may be differentially modified to affect only one of its key functions. PMID:26511314

Functional group-dependent anchoring effect of titanium carbide-based MXenes for lithium-sulfur batteries: A computational study

NASA Astrophysics Data System (ADS)

Zhao, Yuming; Zhao, Jingxiang

2017-08-01

The large-scale practical application of lithium-sulfur (Li-S) batteries cannot be relized unless the challenge of dissolving of soluble lithium polysulfides (Li2Sn) species in electrolytes can be solved. Herein, by means of density functional theory (DFT) computations, we systematically exploited the anchoring effects of various titanium carbide-based MXenes for Li-S batteries. Our results revealed that, due to the attraction between Li ions in Li2Sn species and O atoms in Ti2CO2 and Ti3C2O2 monolayer, the two Mxenes can strongly interact with Li2Sn species with remarkable but not too strong binding strength to effectively immobilize the soluble polysulfides. Especially, the intactness of the Li2Sn species can be well saved, although the Lisbnd S bonds are weakened. Therefore, Ti2CO2 and Ti3C2O2 monolayers are quite promising anchoring materials with good cycling performances for Li-S batteries.

The biosynthesis of nitrogen-, sulfur-, and high-carbon chain-containing sugars.

PubMed

Lin, Chia-I; McCarty, Reid M; Liu, Hung-wen

2013-05-21

Carbohydrates serve many structural and functional roles in biology. While the majority of monosaccharides are characterized by the chemical composition (CH2O)n, modifications including deoxygenation, C-alkylation, amination, O- and N-methylation, which are characteristic of many sugar appendages of secondary metabolites, are not uncommon. Interestingly, some sugar molecules are formed via modifications including amine oxidation, sulfur incorporation, and "high-carbon" chain attachment. Most of these unusual sugars have been identified over the past several decades as components of microbially produced natural products, although a few high-carbon sugars are also found in the lipooligosaccharides of the outer cell walls of Gram-negative bacteria. Despite their broad distribution in nature, these sugars are considered "rare" due to their relative scarcity. The biosynthetic steps that underlie their formation continue to perplex researchers to this day and many questions regarding key transformations remain unanswered. This review will focus on our current understanding of the biosynthesis of unusual sugars bearing oxidized amine substituents, thio-functional groups, and high-carbon chains.

Metagenomic resolution of microbial functions in deep-sea hydrothermal plumes across the Eastern Lau Spreading Center

PubMed Central

Anantharaman, Karthik; Breier, John A; Dick, Gregory J

2016-01-01

Microbial processes within deep-sea hydrothermal plumes affect ocean biogeochemistry on global scales. In rising hydrothermal plumes, a combination of microbial metabolism and particle formation processes initiate the transformation of reduced chemicals like hydrogen sulfide, hydrogen, methane, iron, manganese and ammonia that are abundant in hydrothermal vent fluids. Despite the biogeochemical importance of this rising portion of plumes, it is understudied in comparison to neutrally buoyant plumes. Here we use metagenomics and bioenergetic modeling to describe the abundance and genetic potential of microorganisms in relation to available electron donors in five different hydrothermal plumes and three associated background deep-sea waters from the Eastern Lau Spreading Center located in the Western Pacific Ocean. Three hundred and thirty one distinct genomic ‘bins' were identified, comprising an estimated 951 genomes of archaea, bacteria, eukarya and viruses. A significant proportion of these genomes is from novel microorganisms and thus reveals insights into the energy metabolism of heretofore unknown microbial groups. Community-wide analyses of genes encoding enzymes that oxidize inorganic energy sources showed that sulfur oxidation was the most abundant and diverse chemolithotrophic microbial metabolism in the community. Genes for sulfur oxidation were commonly present in genomic bins that also contained genes for oxidation of hydrogen and methane, suggesting metabolic versatility in these microbial groups. The relative diversity and abundance of genes encoding hydrogen oxidation was moderate, whereas that of genes for methane and ammonia oxidation was low in comparison to sulfur oxidation. Bioenergetic-thermodynamic modeling supports the metagenomic analyses, showing that oxidation of elemental sulfur with oxygen is the most dominant catabolic reaction in the hydrothermal plumes. We conclude that the energy metabolism of microbial communities inhabiting rising hydrothermal plumes is dictated by the underlying plume chemistry, with a dominant role for sulfur-based chemolithoautotrophy. PMID:26046257

Interaction of sulfur dioxide and carbon dioxide with clean silver in ultrahigh vacuum.

NASA Technical Reports Server (NTRS)

Lassiter, W. S.

1972-01-01

It is shown that when a clean polycrystalline silver surface is subjected to sulfur dioxide at a pressure of 1 nanotorr, sulfur is chemisorbed to the silver. Heating the contaminated silver leads to an estimation of the minimum heat of desorption of 59 kcal/mol. Sulfur Auger peak height and relative function measurements of the surface during exposure show that adsorption occurs during 6 microtorr/sec exposure at 1 nanotorr.

Matrix effects of calcium on high-precision sulfur isotope measurement by multiple-collector inductively coupled plasma mass spectrometry.

PubMed

Liu, Chenhui; Bian, Xiao-Peng; Yang, Tao; Lin, An-Jun; Jiang, Shao-Yong

2016-05-01

Multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has been successfully applied in the rapid and high-precision measurement for sulfur isotope ratios in recent years. During the measurement, the presence of matrix elements would affect the instrumental mass bias for sulfur and these matrix-induced effects have aroused a lot of researchers' interest. However, these studies have placed more weight on highlighting the necessity for their proposed correction protocols (e.g., chemical purification and matrix-matching) while less attention on the key property of the matrix element gives rise to the matrix effects. In this study, four groups of sulfate solutions, which have different concentrations of sulfur (0.05-0.60mM) but a constant sequence of atomic calcium/sulfur ratios (0.1-50), are investigated under wet (solution) and dry (desolvation) plasma conditions to make a detailed evaluation on the matrix effects from calcium on sulfur isotope measurement. Based on a series of comparative analyses, we indicated that, the matrix effects of calcium on both measured sulfur isotope ratios and detected (32)S signal intensities are dependent mainly on the absolute calcium concentration rather than its relative concentration ratio to sulfur (i.e., atomic calcium/sulfur ratio). Also, for the same group of samples, the matrix effects of calcium under dry plasma condition are much more significant than that of wet plasma. This research affords the opportunity to realize direct and relatively precise sulfur isotope measurement for evaporite gypsum, and further provides some suggestions with regard to sulfur isotope analytical protocols for sedimentary pore water. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of Dietary Processed Sulfur Supplementation on Texture Quality, Color and Mineral Status of Dry-cured Ham

PubMed Central

2015-01-01

This study was performed to investigate the chemical composition, mineral status, oxidative stability, and texture attributes of dry-cured ham from pigs fed processed sulfur (S, 1 g/kg feed), and from those fed a basal diet (CON), during the period from weaning to slaughter (174 d). Total collagen content and soluble collagen of the S group was significantly higher than that of the control group (p<0.05). The pH of the S group was significantly higher than that of the control group, whereas the S group had a lower expressible drip compared to the control group. The S group also showed the lower lightness compared to the control group (p<0.05). In regard to the mineral status, the S group had significantly lower Fe2+ and Ca2+ content than the control group (p<0.05), whereas the proteolysis index of the S group was significantly increased compared to the control group (p<0.05). The feeding of processed sulfur to pigs led to increased oxidative stability, related to lipids and pigments, in the dry-cured ham (p<0.05). Compared to the dry-cured ham from the control group, that from the S group exhibited lower springiness and gumminess; these results suggest that feeding processed sulfur to pigs can improve the quality of the texture and enhance the oxidative stability of dry-cured ham. PMID:26761895

Diagenetic gypsum related to sulfur deposits in evaporites (Libros Gypsum, Miocene, NE Spain)

NASA Astrophysics Data System (ADS)

Ortí, Federico; Rosell, Laura; Anadón, Pere

2010-07-01

The Libros Gypsum is the thickest evaporite unit of the Miocene infill of the Teruel Basin in NE Spain. During the deposition of this unit, intense bacterial sulfate-reducing (BSR) activity in the lake depocenter generated a native sulfur deposit. Diagenetic gypsum resulted from subsequent sulfur oxidation. The different processes involved in these transformations were first investigated by Anadón et al. (1992). The present paper is concerned with this diagenetic gypsum from the stratigraphic, petrographic, isotopic and genetic points of view. Diagenetic gypsum occurs mainly as continuous or discontinuous layers, individual levels or lenses, irregular masses, nodules and micronodules, and veins. Its main textures are coarse-crystalline anhedral and fine-grained (alabastrine), both of which can replace any former lithology (carbonate, gypsum, and sulfur). The following sequence of processes and mineral/textural transformations is deduced: primary gypsum deposition — BSR and biodiagenetic carbonate/H 2S production — growth of native sulfur — growth of diagenetic gypsum — partial recrystallization of the diagenetic gypsum textures. The gypsification of the native sulfur generated two types of banded structures in the diagenetic gypsum: (1) concentric structures of centripetal growth, and (2) expansive, roughly concentric structures. In the first type, the gypsification operated from the outer boundaries towards the inner parts. In the second type, part of the carbonate hosting the sulfur was also gypsified (replaced/cemented). In the diagenetic gypsum, the δ34S values are in agreement with a native sulfur and H 2S provenance. The δ18O sulfate values, however, enable us to differentiate two main groups of values: one with positive values and the other with negative values. In the group of positive values, interstitial (evaporated) solutions participated in the sulfur oxidation; this process presumably occurred in a first oxidation stage during shallow-to-deeper burial of the Libros Gypsum unit. In the group of negative values, however, only meteoric waters participated in the oxidation, which presumably occurred in a second oxidation stage during the final exhumation of the unit. A third group of values is characterized by very high sulfur and oxygen values, suggesting that BSR residual solutions also participated in the oxidation processes locally. During the two oxidation stages, both the textural characteristics and the isotopic composition of the diagenetic gypsum indicate that gypsification operated as a multistadic process.

[Comparison of sulfur fumigation processing and direct hot air heating technology on puerarin contents and efficacy of Puerariae Thomsonii Radix].

PubMed

Yu, Hong-Li; Zhang, Qian; Jin, Yang-Ping; Wang, Kui-Long; Lu, Tu-Lin; Li, Lin

2016-07-01

In order to compare the effect of sulfur fumigation processing and direct hot air heating technology on puerarin contents and efficacy of Puerariae Thomsonii Radix, the fresh roots of Pueraria thomsonii were cut into small pieces and prepared into direct sunshine drying samples, direct hot air drying samples, and sulfur fumigation-hot air drying samples. Moisture contents of the samples were then determined. The puerarin contents of different samples were compared by HPLC method. Moreover, the models of drunkenness mice were established, and then with superoxide dismutase (SOD) content as the index, aqueous decoction extracts of Puerariae Thomsonii Radix samples with sulfur fumigation processing and non-sulfur fumigation processing methods were administrated by ig; the effects of sulfur fumigation on contents of SOD in mice liver and serum were determined, and the sulfur fumigation samples and non-sulfur fumigation samples were investigated for moth and mildew under different packaging and storage conditions. Results showed that the sulfur fumigation samples significantly changed the puerarin content from Puerariae Thomsonii Radix. The content of puerarin was decreased gradually when increasing the times of sulfur fumigation and amount of sulfur. SOD content in drunken mice liver and serum was significantly decreased when increasing the times of sulfur fumigation, showing significant difference with both direct sunshine drying group and direct hot air drying group. Moth and mildew were not found in the sulfur fumigation samples and direct hot air drying samples whose moisture contents were lower than the limit in Pharmacopoeia. Research showed that sulfur fumigation can significantly reduce the content of main active ingredients and reduce the efficacy of Puerariae Thomsonii Radix, indicating that the quality of Puerariae Thomsonii Radix was significantly decreased after sulfur fumigation. However, the contents of the main active ingredients, efficacy and storage results of the direct hot air drying samples were similar to those in direct sunshine drying samples, so the hot air drying process was a nice drying technology which could be promoted for use. Copyright© by the Chinese Pharmaceutical Association.

New insights into sulfur amino acids function in gut health and disease

USDA-ARS?s Scientific Manuscript database

The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acids (SAAs) metabolism in the body. Aside from their role in protein synthesis, methionine and cysteine are involved in many biological functions and diseases. Methionine (MET) is an indispensable amino acid and is...

New insights into sulfur amino acid function in gut health and disease

USDA-ARS?s Scientific Manuscript database

The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acids (SAA) metabolism in the body. Aside from their role in protein synthesis, methionine and cysteine are involved in many biological functions and diseases. Methionine (MET) is an indispensable AA and is transmet...

Effects of hydrogen annealing, sulfur segregation and diffusion on the cyclic oxidation resistance of superalloys: A review

NASA Astrophysics Data System (ADS)

Smialek, J. L.; Jayne, D. T.; Schaeffer, J. C.; Murphy, W. H.

1994-12-01

This review is based on the phenomenon of improved oxide scale adhesion for desulfurized superalloys. The proposed adhesion mechanism involves sulfur interfacial segregation and scale-metal bond weakening. Sulfur surface segregation on superalloys is examined as a function of temperature and sulfur content, and is related to the classical behavior predicted by the McLean isotherm. Effective desulfurization to less than 1 ppmw can be accomplished by hydrogen annealing and is described by sulfur diffusion kinetics in nickel. Hydrogen annealing results in excellent cyclic oxidation resistance for a number of advanced superalloys. The concept of a critical sulfur content is discussed in terms of practical annealing conditions and section thicknesses.

Effects of hydrogen annealing, sulfur segregation and diffusion on the cyclic oxidation resistance of superalloys: A review

NASA Technical Reports Server (NTRS)

Smialek, J. L.; Jayne, D. T.; Schaeffer, J. C.; Murphy, W. H.

1994-01-01

This review is based on the phenomenon of improved oxide scale adhesion for desulfurized superalloys. The proposed adhesion mechanism involves sulfur interfacial segregation and scale-metal bond weakening. Sulfur surface segregation on superalloys is examined as a function of temperature and sulfur content, and is related to the classical behavior predicted by the McLean isotherm. Effective desulfurization to less than 1 ppmw can be accomplished by hydrogen annealing and is described by sulfur diffusion kinetics in nickel. Hydrogen annealing results in excellent cyclic oxidation resistance for a number of advanced superalloys. The concept of a critical sulfur content is discussed in terms of practical annealing conditions and section thicknesses.

Effects of Hydrogen Annealing, Sulfur Segregation and Diffusion on the Cyclic Oxidation Resistance of Superalloys: a Review

NASA Technical Reports Server (NTRS)

Smialek, J. L.; Jayne, D. T.; Schaeffer, J. C.; Murphy, W. H.

1994-01-01

This review is based on the phenomenon of improved oxide scale adhesion for desulfurized superalloys. The proposed adhesion mechanism involves sulfur interfacial segregation and scale-metal bond weakening. Sulfur surface segregation on superalloys is examined as a function of temperature and sulfur content and related to classical behavior predicted by the McLean isotherm. Effective desulfurization to less than 1 ppmw can be accomplished by hydrogen annealing and is governed by sulfur diffusion kinetics in nickel. Hydrogen annealing results in excellent cyclic oxidation resistance for a number of advanced superalloys. The concept of a critical sulfur content is discussed in terms of practical annealing conditions and section thicknesses.

New Dimensions in Microbial Ecology-Functional Genes in Studies to Unravel the Biodiversity and Role of Functional Microbial Groups in the Environment.

PubMed

Imhoff, Johannes F

2016-05-24

During the past decades, tremendous advances have been made in the possibilities to study the diversity of microbial communities in the environment. The development of methods to study these communities on the basis of 16S rRNA gene sequences analysis was a first step into the molecular analysis of environmental communities and the study of biodiversity in natural habitats. A new dimension in this field was reached with the introduction of functional genes of ecological importance and the establishment of genetic tools to study the diversity of functional microbial groups and their responses to environmental factors. Functional gene approaches are excellent tools to study the diversity of a particular function and to demonstrate changes in the composition of prokaryote communities contributing to this function. The phylogeny of many functional genes largely correlates with that of the 16S rRNA gene, and microbial species may be identified on the basis of functional gene sequences. Functional genes are perfectly suited to link culture-based microbiological work with environmental molecular genetic studies. In this review, the development of functional gene studies in environmental microbiology is highlighted with examples of genes relevant for important ecophysiological functions. Examples are presented for bacterial photosynthesis and two types of anoxygenic phototrophic bacteria, with genes of the Fenna-Matthews-Olson-protein (fmoA) as target for the green sulfur bacteria and of two reaction center proteins (pufLM) for the phototrophic purple bacteria, with genes of adenosine-5'phosphosulfate (APS) reductase (aprA), sulfate thioesterase (soxB) and dissimilatory sulfite reductase (dsrAB) for sulfur oxidizing and sulfate reducing bacteria, with genes of ammonia monooxygenase (amoA) for nitrifying/ammonia-oxidizing bacteria, with genes of particulate nitrate reductase and nitrite reductases (narH/G, nirS, nirK) for denitrifying bacteria and with genes of methane monooxygenase (pmoA) for methane oxidizing bacteria.

Gas-phase ion-molecule reactions for the identification of the sulfone functionality in protonated analytes in a linear quadrupole ion trap mass spectrometer.

PubMed

Tang, Weijuan; Sheng, Huaming; Kong, John Y; Yerabolu, Ravikiran; Zhu, Hanyu; Max, Joann; Zhang, Minli; Kenttämaa, Hilkka I

2016-06-30

The oxidation of sulfur atoms is an important biotransformation pathway for many sulfur-containing drugs. In order to rapidly identify the sulfone functionality in drug metabolites, a tandem mass spectrometric method based on ion-molecule reactions was developed. A phosphorus-containing reagent, trimethyl phosphite (TMP), was allowed to react with protonated analytes with various functionalities in a linear quadrupole ion trap mass spectrometer. The reaction products and reaction efficiencies were measured. Only protonated sulfone model compounds were found to react with TMP to form a characteristic [TMP adduct-MeOH] product ion. All other protonated compounds investigated, with functionalities such as sulfoxide, N-oxide, hydroxylamino, keto, carboxylic acid, and aliphatic and aromatic amino, only react with TMP via proton transfer and/or addition. The specificity of the reaction was further demonstrated by using a sulfoxide-containing anti-inflammatory drug, sulindac, as well as its metabolite sulindac sulfone. A method based on functional group-selective ion-molecule reactions in a linear quadrupole ion trap mass spectrometer has been demonstrated for the identification of the sulfone functionality in protonated analytes. A characteristic [TMP adduct-MeOH] product ion was only formed for the protonated sulfone analytes. The applicability of the TMP reagent in identifying sulfone functionalities in drug metabolites was also demonstrated. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Applications of micellar enzymology to clean coal technology. [Laccase from Polyporus versicolor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walsh, C.T.

1990-07-24

This project is designed to develop methods for pre-combustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid. Dibenzothiophen (DBT) and ethylphenylsulfide (EPS) are serving as models of organic sulfur-containing components of coal in initial studies.

DFT and TD-DFT study of the adsorption and detection of sulfur mustard chemical warfare agent by the C24, C12Si12, Al12N12, Al12P12, Be12O12, B12N12 and Mg12O12 nanocages

NASA Astrophysics Data System (ADS)

Jouypazadeh, Hamidreza; Farrokhpour, Hossein

2018-07-01

In the present research, the interaction of sulfur mustard, a chemical warfare agent, with the surface of C24, C12Si12, Al12N12, Al12P12, Be12O12, B12N12 and Mg12O12 nanocages was studied using the dispersion corrected density function theory (DFT-D3) method. The calculated adsorption energies of sulfur mustard on the surface of the nanocages showed that the Al12N12, C12Si12 and Mg12O12 are useful for the adsorption of the sulfur mustard. The quantum theory atom in molecule (QTAIM) analysis was used to study the nature of interactions of sulfur mustard with the surface of the selected nanocages. Based on QTAIM analysis, the majority of interactions of sulfur and chlorine atoms of sulfur mustard with the surface of the considered nanocages are covalent and quasi covalent whereas the interactions of hydrogen atoms of sulfur mustard with the surface of the nanocages are generally non-covalent. The charge transfer between sulfur mustard and the nanocages as well as chemical quantum descriptors of complexes were calculated using natural bond orbital (NBO) method. The most electron charge transfers from the sulfur mustard to B12N12 nanocage where the S atom of sulfur mustard donor a chemical bond to B atom of the nanocage. The ability of the considered nanocages for detecting sulfur mustard was studied using time-dependent density function theory (TD-DFT) and density of state (DOS) diagram. It is found that the C24, Al12P12, Be12O12 and B12N12 nanocages are useful sensors for this chemical agent.

Clues to early diagenetic sulfurization processes from mild chemical cleavage of labile sulfur-rich geomacromolecules

NASA Astrophysics Data System (ADS)

Adam, P.; Schneckenburger, P.; Schaeffer, P.; Albrecht, P.

2000-10-01

Macromolecular fractions, isolated from the solvent extract of sulfur-rich Recent (Siders Pond, USA; Lake Cadagno, Switzerland; Walvis Bay, Namibia) and immature sediments (Gibellina, Messinian of Sicily; Vena del Gesso, Messinian of Italy), were investigated by chemical degradation using sodium ethanethiolate/methyliodide. This mild reagent which cleaves polysulfide bonds to yield methylsulfides has the advantage over other methods of leaving intact other functionalities (like double bonds) and preserving sulfur atoms at their incorporation site. The method is, therefore, well-suited to the molecular level investigation of sulfur-rich macromolecules from Recent sediments containing highly functionalized polysulfide-bound subunits. In Recent anoxic sulfur-rich sediments, the release of various methylthioethers clearly demonstrates that intermolecular sulfurization of organic matter does occur at the earliest stages of diagenesis. Steroids and phytane derivatives are the major sulfurized lipids, a feature also observed in more mature sulfur-rich sediments. Several phytene derivatives, such as cis and trans 1-methylthiophyt-2-enes, as well as methylthiosteroids, including 5α- and 5β-3-(methylthio)-cholest-2-enes, were identified by comparison with synthesized standards. Steroid methylthioenolethers are released from polysulfide-bound steroid enethiols present in the macromolecular fractions. The latter, which correspond to thioketones, can be considered as intermediates in the reductive sulfurization pathway leading from steroid ketones to polysulfide-bound saturated steroid skeletons and are characterized for the first time in the present study. Thus, it could be shown that the major part of the polysulfide-bound lipids occurring in Recent sediments is apparently the result of sulfurization processes affecting carbonyls (aldehydes and ketones). The unsaturated methylthioethers obtained from Recent sediments were not present in more mature evaporitic samples, which suggests that polysulfide-bound unsaturated thiols are intermediates formed during the first sulfurization steps occurring soon after deposition and that they are rapidly transformed by various processes taking place during early diagenesis, notably to yield their saturated counterparts.

In Vivo Studies in Rhodospirillum rubrum Indicate That Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) Catalyzes Two Obligatorily Required and Physiologically Significant Reactions for Distinct Carbon and Sulfur Metabolic Pathways.

PubMed

Dey, Swati; North, Justin A; Sriram, Jaya; Evans, Bradley S; Tabita, F Robert

2015-12-25

All organisms possess fundamental metabolic pathways to ensure that needed carbon and sulfur compounds are provided to the cell in the proper chemical form and oxidation state. For most organisms capable of using CO2 as sole source of carbon, ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes primary carbon dioxide assimilation. In addition, sulfur salvage pathways are necessary to ensure that key sulfur-containing compounds are both available and, where necessary, detoxified in the cell. Using knock-out mutations and metabolomics in the bacterium Rhodospirillum rubrum, we show here that Rubisco concurrently catalyzes key and essential reactions for seemingly unrelated but physiologically essential central carbon and sulfur salvage metabolic pathways of the cell. In this study, complementation and mutagenesis studies indicated that representatives of all known extant functional Rubisco forms found in nature are capable of simultaneously catalyzing reactions required for both CO2-dependent growth as well as growth using 5-methylthioadenosine as sole sulfur source under anaerobic photosynthetic conditions. Moreover, specific inactivation of the CO2 fixation reaction did not affect the ability of Rubisco to support anaerobic 5-methylthioadenosine metabolism, suggesting that the active site of Rubisco has evolved to ensure that this enzyme maintains both key functions. Thus, despite the coevolution of both functions, the active site of this protein may be differentially modified to affect only one of its key functions. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Microbial ecology of soda lakes: investigating sulfur and nitrogen cycling at Mono Lake, CA, USA

NASA Astrophysics Data System (ADS)

Fairbanks, D.; Phillips, A. A.; Wells, M.; Bao, R.; Fullerton, K. M.; Stamps, B. W.; Speth, D. R.; Johnson, H.; Sessions, A. L.

2017-12-01

Soda lakes represent unique ecosystems characterized by extremes of pH, salinity and distinct geochemical cycling. Despite these extreme conditions, soda lakes are important repositories of biological adaptation and have a highly functional microbial system. We investigated the biogeochemical cycling of sulfur and nitrogen compounds in Mono Lake, California, located east of the Sierra Nevada mountains. Mono lake is characterized by hyperalkaline, hypersaline and high sulfate concentrations and can enter prolonged periods of meromixis due to freshwater inflow. Typically, the microbial sulfur cycle is highly active in soda lakes with both oxidation and reduction of sulfur compounds. However, the biological sulfur cycle is connected to many other main elemental cycles such as carbon, nitrogen and metals. Here we investigated the interaction between sulfur and nitrogen cycling in Mono lake using a combination of molecular, isotopic, and geochemical observations to explore the links between microbial phylogenetic composition and functionality. Metagenomic and 16S rRNA gene amplicon sequencing were determined at two locations and five depths in May 2017. 16S rRNA gene amplicon sequencing analysis revealed organisms capable of both sulfur and nitrogen cycling. The relative abundance and distribution of functional genes (dsrA, soxAB, nifH, etc) were also determined. These genetic markers indicate the potential in situ relevance of specific carbon, nitrogen, and sulfur pathways in the water column prior to the transition to meromictic stratification. However, genes for sulfide oxidation, denitrification, and ammonification were present. Genome binning guided by the most abundant dsrA sequences, GC content, and abundance with depth identified a Thioalkalivibrio paradoxus bin containing genes capable of sulfur oxidation, denitrification, and nitrate reduction. The presence of a large number of sulfur and nitrogen cycling genes associated with Thioalkalivibrio paradoxus suggests thiosulfate oxidation may be coupled to nitrate reduction despite the extremely low level of nitrate in Mono Lake. Our results illustrate the centrality of living organisms in both shaping and responding to geochemical cycles, as well as future directions for exploring coupled biogeochemical cycles in Mono Lake.

The vertical distribution of prokaryotes in the surface sediment of Jiaolong cold seep at the northern South China Sea.

PubMed

Wu, Yuzhi; Qiu, Jian-Wen; Qian, Pei-Yuan; Wang, Yong

2018-05-01

In deep-sea cold seeps, microbial communities are shaped by geochemical components in seepage solutions. In the present study, we report the composition of microbial communities and potential metabolic activities in the surface sediment of Jiaolong cold seep at the northern South China Sea. Pyrosequencing of 16S rRNA gene amplicons revealed that a majority of the microbial inhabitants of the surface layers (0-6 cm) were sulfur oxidizer bacteria Sulfurimonas and archaeal methane consumer ANME-1, while sulfate reducer bacteria SEEP-SRB1, ANME-1 and ANME-2 dominated the bottom layers (8-14 cm). The potential ecological roles of the microorganisms were further supported by the presence of functional genes for methane oxidation, sulfur oxidation, sulfur reduction and nitrate reduction in the metagenomes. Metagenomic analysis revealed a significant correlation between coverage of 16S rRNA gene of sulfur oxidizer bacteria, functional genes involved in sulfur oxidation and nitrate reduction in different layers, indicating that sulfur oxidizing may be coupled to nitrate reducing at the surface layers of Jiaolong seeping site. This is probably related to the sulfur oxidizers of Sulfurimonas and Sulfurovum, which may be the capacity of nitrate reduction or associated with unidentified syntrophic nitrate-reducing microbes in the surface of the cold seep.

Comparison on surface properties and desulfurization of MnO2 and pyrolusite blended activated carbon by steam activation.

PubMed

Zhang, Guochen; Zhao, Xin; Ning, Ping; Yang, Danni; Jiang, Xia; Jiang, Wenju

2018-04-18

In this study, MnO 2 and pyrolusite were used as the catalysts to prepare modified activated carbon, i.e., AC-Mn and AC-P, respectively, from coals by blending method and steam activation. The BET results indicated that the AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The relative contents of basic functional groups (i.e. C = O, π-π*) on AC-P were slightly lower than those on AC-Mn, while both contained the same main metal species, i.e. MnO. The desulfurization results showed that with 3 wt% of blending ratio, AC-Mn3 and AC-P3 had higher sulfur capacities at 220 and 205 mg/g, respectively, which were much higher than blank one (149.6 mg/g). Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn, which might be attributed to the existence of other metals in pyrolusite. After desulfurization process, MnO were gradually transferred into MnSO 4 , and the relative contents of basic functional groups decreased evidently for both AC-Mn3 and AC-P3. The results demonstrated that pyrolusite could be one good alternative of MnO 2 to prepare modified activated carbon for desulfurization. Implication statement MnO 2 and pyrolusite were used as the additives to prepare the modified activated carbon from coals by blending method and steam activation, i.e., AC-Mn and AC-P, respectively. The AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The AC-Mn and AC-P had higher sulfur capacities than blank one. Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn. The results demonstrated that pyrolusite could be one good alternative of MnO 2 to prepare modified activated carbon for desulfurization.

Evidence for microbial carbon and sulfur cycling in deeply buried ridge flank basalt

USGS Publications Warehouse

Lever, Mark A.; Rouxel, Olivier; Alt, Jeffrey C.; Shimizu, Nobumichi; Ono, Shuhei; Coggon, Rosalind M.; Shanks, Wayne C.; Lapham, Laura; Elvert, Marcus; Prieto-Mollar, Xavier; Hinrichs, Kai-Uwe; Inagaki, Fumio; Teske, Andreas

2013-01-01

Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge. Depth horizons with functional genes indicative of methane-cycling and sulfate-reducing microorganisms are enriched in solid-phase sulfur and total organic carbon, host δ13C- and δ34S-isotopic values with a biological imprint, and show clear signs of microbial activity when incubated in the laboratory. Downcore changes in carbon and sulfur cycling show discrete geochemical intervals with chemoautotrophic δ13C signatures locally attenuated by heterotrophic metabolism.

Fibrous hybrid of graphene and sulfur nanocrystals for high-performance lithium-sulfur batteries.

PubMed

Zhou, Guangmin; Yin, Li-Chang; Wang, Da-Wei; Li, Lu; Pei, Songfeng; Gentle, Ian Ross; Li, Feng; Cheng, Hui-Ming

2013-06-25

Graphene-sulfur (G-S) hybrid materials with sulfur nanocrystals anchored on interconnected fibrous graphene are obtained by a facile one-pot strategy using a sulfur/carbon disulfide/alcohol mixed solution. The reduction of graphene oxide and the formation/binding of sulfur nanocrystals were integrated. The G-S hybrids exhibit a highly porous network structure constructed by fibrous graphene, many electrically conducting pathways, and easily tunable sulfur content, which can be cut and pressed into pellets to be directly used as lithium-sulfur battery cathodes without using a metal current-collector, binder, and conductive additive. The porous network and sulfur nanocrystals enable rapid ion transport and short Li(+) diffusion distance, the interconnected fibrous graphene provides highly conductive electron transport pathways, and the oxygen-containing (mainly hydroxyl/epoxide) groups show strong binding with polysulfides, preventing their dissolution into the electrolyte based on first-principles calculations. As a result, the G-S hybrids show a high capacity, an excellent high-rate performance, and a long life over 100 cycles. These results demonstrate the great potential of this unique hybrid structure as cathodes for high-performance lithium-sulfur batteries.

Fundamental Studies on Donor-acceptor Conjugated Polymers Containing 'Heavy' Group 14 and Group 16 Elements

NASA Astrophysics Data System (ADS)

Gibson, Gregory Laird

One advantage of conjugated polymers as organic materials is that their properties may be readily tuned through covalent modifications. This thesis presents studies on the structure-property relationships resulting from single- and double-atom substitutions on an alternating donor-acceptor conjugated polymer. Specifically, single selenium and tellurium atoms have been incorporated into the acceptor monomer in place of sulfur; silicon and germanium atoms have been substituted in place of carbon at the donor monomer bridge position. The carbon-donor/ tellurium-acceptor polymer was synthesized by a post-polymerization reaction sequence and demonstrated the utility of heavy group 16 atoms to red shift a polymer absorption spectrum. Density functional theory calculations point to a new explanation for this result invoking the lower heavy atom ionization energy and reduced aromaticity of acceptor monomers containing selenium and tellurium compared to sulfur. Absorption and emission experiments demonstrate that both silicon and germanium substitutions in the donor slightly blue shift the polymer absorption spectrum. Polymers containing sulfur in the acceptor are the strongest light absorbers of all polymers studied here. Molecular weight and phenyl end capping studies show that molecular weight appears to affect polymer absorption to the greatest degree in a medium molecular weight regime and that these effects have a significant aggregation component. Solar cell devices containing either the silicon- or germanium-donor/selenium-acceptor polymer display improved red light harvesting or hole mobility relative to their structural analogues. Overall, these results clarify the effects of single atom substitution on donor-acceptor polymers and aid in the future design of polymers containing heavy atoms.

Simultaneous removal of nitrogen oxides and sulfur oxides from combustion gases

DOEpatents

Clay, David T.; Lynn, Scott

1976-10-19

A process for the simultaneous removal of sulfur oxides and nitrogen oxides from power plant stack gases comprising contacting the stack gases with a supported iron oxide catalyst/absorbent in the presence of sufficient reducing agent selected from the group consisting of carbon monoxide, hydrogen, and mixtures thereof, to provide a net reducing atmosphere in the SO.sub.x /NO.sub.x removal zone. The sulfur oxides are removed by absorption substantially as iron sulfide, and nitrogen oxides are removed by catalytic reduction to nitrogen and ammonia. The spent iron oxide catalyst/absorbent is regenerated by oxidation and is recycled to the contacting zone. Sulfur dioxide is also produced during regeneration and can be utilized in the production of sulfuric acid and/or sulfur.

Inhomogeneous models of the Venus clouds containing sulfur

NASA Technical Reports Server (NTRS)

Smith, S. M.; Pollack, J. B.; Giver, L. P.; Cuzzi, J. N.; Podolak, M.

1979-01-01

Based on the suggestion that elemental sulfur is responsible for the yellow color of Venus, calculations are compared at 3.4 microns of the reflectivity phase function of two sulfur containing inhomogeneous cloud models with that of a homogeneous model. Assuming reflectivity observations with 25% or less total error, comparison of the model calculations leads to a minimum detectable mass of sulfur equal to 7% of the mass of sulfuric acid for the inhomogeneous drop model. For the inhomogeneous cloud model the comparison leads to a minimum detectable mass of sulfur between 17% and 38% of the mass of the acid drops, depending upon the actual size of the large particles. It is concluded that moderately accurate 3.4 microns reflectivity observations are capable of detecting quite small amounts of elemental sulfur at the top of the Venus clouds.

Estimate feedstock processability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amorelli, A.; Amos, Y.D.; Halsig, C.P.

1992-06-01

Currently, one of the major environmental pressures is to further reduce sulfur levels in middle distillate products. This paper reports that the key to this is understanding reactivities of individual sulfur components in the feedstocks to be treated. The major sulfur species in middle distillates is aromatic compounds, predominantly benzothiophenes and dibenzothiophenes. However, in straight run materials, significant quantities of aliphatic sulfur compounds and further higher boiling benzothiophenes are also expected. Simultaneous simulated distillation with a gas chromatograph microwave-induced plasma atomic emission detector (SIMDIS/AED) is used for middle distillate characterization of sulfur distribution as a function of boiling point. Itmore » is able to discriminate between middle distillate feed types such as cracked and straight run gas oils, and has shown that similar feeds, with different total sulfur contents (unevenly distributed throughout a feedstock), have the same normalized sulfur distribution.« less

Spatial dependence of reduced sulfur in Everglades dissolved organic matter controlled by sulfate enrichment

USGS Publications Warehouse

Poulin, Brett A.; Ryan, Joseph N.; Nagy, Kathryn L.; Stubbins, Aron; Dittmar, Thorsten; Orem, William H.; Krabbenhoft, David P.; Aiken, George R.

2017-01-01

Sulfate inputs to the Florida Everglades stimulate sulfidic conditions in freshwater wetland sediments that affect ecological and biogeochemical processes. An unexplored implication of sulfate enrichment is alteration of the content and speciation of sulfur in dissolved organic matter (DOM), which influences the reactivity of DOM with trace metals. Here, we describe the vertical and lateral spatial dependence of sulfur chemistry in the hydrophobic organic acid fraction of DOM from unimpacted and sulfate-impacted Everglades wetlands using X-ray absorption spectroscopy and ultrahigh-resolution mass spectrometry. Spatial variation in DOM sulfur content and speciation reflects the degree of sulfate enrichment and resulting sulfide concentrations in sediment pore waters. Sulfur is incorporated into DOM predominantly as highly reduced species in sulfidic pore waters. Sulfur-enriched DOM in sediment pore waters exchanges with overlying surface waters and the sulfur likely undergoes oxidative transformations in the water column. Across all wetland sites and depths, the total sulfur content of DOM correlated with the relative abundance of highly reduced sulfur functionality. The results identify sulfate input as a primary determinant on DOM sulfur chemistry to be considered in the context of wetland restoration and sulfur and trace metal cycling.

Improvement of Energy Capacity with Vitamin C Treated Dual-Layered Graphene-Sulfur Cathodes in Lithium-Sulfur Batteries.

PubMed

Kim, Jin Won; Ocon, Joey D; Kim, Ho-Sung; Lee, Jaeyoung

2015-09-07

Invited for this month's cover is the groups of Prof. Dr. Jaeyoung Lee at the Gwangju Institute of Science and Technology in South Korea. The image shows that Vitamin C can be used to effectively improve the performance of lithium-sulfur batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Roles of sulfuric acid in elemental mercury removal by activated carbon and sulfur-impregnated activated carbon.

PubMed

Morris, Eric A; Kirk, Donald W; Jia, Charles Q; Morita, Kazuki

2012-07-17

This work addresses the discrepancy in the literature regarding the effects of sulfuric acid (H(2)SO(4)) on elemental Hg uptake by activated carbon (AC). H(2)SO(4) in AC substantially increased Hg uptake by absorption particularly in the presence of oxygen. Hg uptake increased with acid amount and temperature exceeding 500 mg-Hg/g-AC after 3 days at 200 °C with AC treated with 20% H(2)SO(4). In the absence of other strong oxidizers, oxygen was able to oxidize Hg. Upon oxidation, Hg was more readily soluble in the acid, greatly enhancing its uptake by acid-treated AC. Without O(2), S(VI) in H(2)SO(4) was able to oxidize Hg, thus making it soluble in H(2)SO(4). Consequently, the presence of a bulk H(2)SO(4) phase within AC pores resulted in an orders of magnitude increase in Hg uptake capacity. However, the bulk H(2)SO(4) phase lowered the AC pore volume and could block the access to the active surface sites and potentially hinder Hg uptake kinetics. AC treated with SO(2) at 700 °C exhibited a much faster rate of Hg uptake attributed to sulfur functional groups enhancing adsorption kinetics. SO(2)-treated carbon maintained its fast uptake kinetics even after impregnation by 20% H(2)SO(4).

Synthesis, Characterization, and Reactivity of Functionalized Trinuclear Iron–Sulfur Clusters – A New Class of Bioinspired Hydrogenase Models

PubMed Central

Kaiser, Manuel; Knör, Günther

2015-01-01

The air- and moisture-stable iron–sulfur carbonyl clusters Fe3S2(CO)7(dppm) (1) and Fe3S2(CO)7(dppf) (2) carrying the bisphosphine ligands bis(diphenylphosphanyl)methane (dppm) and 1,1′-bis(diphenylphosphanyl)ferrocene (dppf) were prepared and fully characterized. Two alternative synthetic routes based on different thionation reactions of triiron dodecacarbonyl were tested. The molecular structures of the methylene-bridged compound 1 and the ferrocene-functionalized derivative 2 were determined by single-crystal X-ray diffraction. The catalytic reactivity of the trinuclear iron–sulfur cluster core for proton reduction in solution at low overpotential was demonstrated. These deeply colored bisphosphine-bridged sulfur-capped iron carbonyl systems are discussed as promising candidates for the development of new bioinspired model compounds of iron-based hydrogenases. PMID:26512211

Thiaflavan scavenges radicals and inhibits DNA oxidation: a story from the ferrocene modification.

PubMed

Lai, Hai-Wang; Liu, Zai-Qun

2014-06-23

4-Thiaflavan is a sulfur-substituted flavonoid with a benzoxathiin scaffold. The aim of this work is to compare abilities of sulfur and oxygen atom, hydroxyl groups, and ferrocene moiety at different positions of 4-thiaflavan to trap radicals and to inhibit DNA oxidation. It is found that abilities of thiaflavans to trap radicals and to inhibit DNA oxidation are increased in the presence of ferrocene moiety and are further improved by the electron-donating group attaching to thiaflavan skeleton. It can be concluded that the ferrocene moiety plays the major role for thiaflavans to be antioxidants even in the absence of phenolic hydroxyl groups. On the other hand, the antioxidant effectiveness of phenolic hydroxyl groups in thiaflavans can be improved by the electron-donating group. The influences of sulfur and oxygen atoms in thiaflavans on the antioxidant property of para-hydroxyl group exhibit different manners when the thiaflavans are used to trap radicals and to inhibit DNA oxidation. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

[Diversity of culturable sulfur-oxidizing bacteria in deep-sea hydrothermal vent environments of the South Atlantic].

PubMed

Xu, Hongxiu; Jiang, Lijing; Li, Shaoneng; Zhong, Tianhua; Lai, Qiliang; Shao, Zongze

2016-01-04

To investigate the diversity of culturable sulfur-oxidizing bacteria in hydrothermal vent environments of the South Atlantic, and analyze their characteristics of sulfur oxidation. We enriched and isolated sulfur-oxidizing bacteria from hydrothermal vent samples collected from the South Atlantic. The microbial diversity in enrichment cultures was analyzed using the Denatural Gradient Gel Electrophoresis method. Sulfur-oxidizing characteristics of the isolates was further studied by using ion chromatography. A total of 48 isolates were obtained from the deep-sea hydrothermal vent samples, which belonged to 23 genera and mainly grouped into alpha-Proteobacteria (58.3%), Actinobacteria (22.9%) and gama-Proteobacteria (18.8%). Among them, the genus Thalassospira, Martelella and Microbacterium were dominant. About 60% of the isolates exibited sulfur-oxidizing ability and strain L6M1-5 had a higher sulfur oxidation rate by comparison analysis. The diversity of sulfur-oxidizing bacteria in hydrothermal environments of the South Atlantic was reported for the first time based on culture-dependent methods. The result will help understand the biogechemical process of sulfur compounds in the deep-sea hydrothermal environments.

Optimization of biological sulfide removal in a CSTR bioreactor.

PubMed

Roosta, Aliakbar; Jahanmiri, Abdolhossein; Mowla, Dariush; Niazi, Ali; Sotoodeh, Hamidreza

2012-08-01

In this study, biological sulfide removal from natural gas in a continuous bioreactor is investigated for estimation of the optimal operational parameters. According to the carried out reactions, sulfide can be converted to elemental sulfur, sulfate, thiosulfate, and polysulfide, of which elemental sulfur is the desired product. A mathematical model is developed and was used for investigation of the effect of various parameters on elemental sulfur selectivity. The results of the simulation show that elemental sulfur selectivity is a function of dissolved oxygen, sulfide load, pH, and concentration of bacteria. Optimal parameter values are calculated for maximum elemental sulfur selectivity by using genetic algorithm as an adaptive heuristic search. In the optimal conditions, 87.76% of sulfide loaded to the bioreactor is converted to elemental sulfur.

ARSENIC MINERALS AS INDICATORS OF CONDITIONS OF GOLD DEPOSITION IN CARLIN-TYPE GOLD DEPOSITS.

USGS Publications Warehouse

Rytuba, James J.

1984-01-01

Arsenic minerals commonly occurring in Carlin-type gold deposits include orpiment and realgar and, more rarely, native arsenic and arsenopyrite. Other arsenic-bearing phases present include arsenian pyrite and stibnite and a number of thallium and mercury sulfides. Under conditions of constant temperature and pressure, the relative stability of arsenic minerals is a function of sulfur activity. At high sulfur activity, orpiment is the stable phase. As sulfur activity is decreased, more sulfur-deficient arsenic phases become stable with the progressive formation of realgar, native arsenic, arsenopyrite, and finally, loellingite at very low sulfur activity. Three univariant equilibrium assemblages: orpiment plus realgar, realgar plus native arsenic and native arsenic plus arsenopyrite are useful indicators of sulfur activity and commonly occur in the epithermal environment.

Coverage evolution of the unoccupied Density of States in sulfur superstructures on Ru(0001)

NASA Astrophysics Data System (ADS)

Pisarra, M.; Bernardo-Gavito, R.; Navarro, J. J.; Black, A.; Díaz, C.; Calleja, F.; Granados, D.; Miranda, R.; Martín, F.; Vázquez de Parga, A. L.

2018-03-01

Sulfur adsorbed on Ru(0001) presents a large number of ordered structures. This characteristic makes S/Ru(0001) the ideal system to investigate the effect of different periodicities on the electronic properties of interfaces. We have performed scanning tunneling microscopy/spectroscopy experiments and density functional theory calculations showing that a sulfur adlayer generates interface states inside the Γ directional gap of Ru(0001) and that the position of such states varies monotonically with sulfur coverage. This is the result of the interplay between band folding effects arising from the new periodicity of the system and electron localization on the sulfur monolayer. As a consequence, by varying the amount of sulfur in S/Ru(0001) one can control the electronic properties of these interfacial materials.

Recent approaches for the direct use of elemental sulfur in the synthesis and processing of advanced materials.

PubMed

Lim, Jeewoo; Pyun, Jeffrey; Char, Kookheon

2015-03-09

Elemental sulfur is an abundant and inexpensive material obtained as a by-product of natural-gas and petroleum refining operations. Recently, the need for the development of new energy-storage systems brought into light the potential of sulfur as a high-capacity cathode material in secondary batteries. Sulfur-containing materials were also shown to have useful IR optical properties. These developments coupled with growing environmental concerns related to the global production of excess elemental sulfur have led to a keen interest in its utilization as a feedstock in materials applications. This Minireview focuses on the recent developments on physical and chemical methods for directly processing elemental sulfur to produce functional composites and polymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sulfur assimilation and the role of sulfur in plant metabolism: a survey.

PubMed

Droux, Michel

2004-01-01

Sulfur occurs in two major amino-acids, cysteine (Cys) and methionine (Met), essential for the primary and secondary metabolism of the plant. Cys, as the first carbon/nitrogen-reduced sulfur product resulting from the sulfate assimilation pathway, serves as a sulfur donor for Met, glutathione, vitamins, co-factors, and sulfur compounds that play a major role in the growth and development of plant cells. This sulfur imprinting occurs in a myriad of fundamental processes, from photosynthesis to carbon and nitrogen metabolism. Cys and Met occur in proteins, with the former playing a wide range of functions in proteins catalysis. In addition, the sulfur atom in proteins forms part of a redox buffer, as for glutathione, through specific detoxification/protection mechanisms. In this review, a survey of sulfur assimilation from sulfate to Cys, Met and glutathione is presented with highlights on open questions on their respective biosynthetic pathways and regulations that derived from recent findings. These are addressed at the biochemical and molecular levels with respect to the fate of Cys and Met throughout the plant-cell metabolism.

Shared Sulfur Mobilization Routes for tRNA Thiolation and Molybdenum Cofactor Biosynthesis in Prokaryotes and Eukaryotes

PubMed Central

Leimkühler, Silke; Bühning, Martin; Beilschmidt, Lena

2017-01-01

Modifications of transfer RNA (tRNA) have been shown to play critical roles in the biogenesis, metabolism, structural stability and function of RNA molecules, and the specific modifications of nucleobases with sulfur atoms in tRNA are present in pro- and eukaryotes. Here, especially the thiomodifications xm5s2U at the wobble position 34 in tRNAs for Lys, Gln and Glu, were suggested to have an important role during the translation process by ensuring accurate deciphering of the genetic code and by stabilization of the tRNA structure. The trafficking and delivery of sulfur nucleosides is a complex process carried out by sulfur relay systems involving numerous proteins, which not only deliver sulfur to the specific tRNAs but also to other sulfur-containing molecules including iron–sulfur clusters, thiamin, biotin, lipoic acid and molybdopterin (MPT). Among the biosynthesis of these sulfur-containing molecules, the biosynthesis of the molybdenum cofactor (Moco) and the synthesis of thio-modified tRNAs in particular show a surprising link by sharing protein components for sulfur mobilization in pro- and eukaryotes. PMID:28098827

Doxepin cream vs betamethasone cream for treatment of chronic skin lesions due to sulfur mustard.

PubMed

Panahi, Yunes; Davoudi, Seyyed Masoud; Beiraghdar, Fatemeh; Amiri, Mojtaba

2011-01-01

Oral doxepin was shown to reduce chronic pruritus due to sulfur mustard. The present study compared the effects of topical doxepin 5% with betamethasone 1% for the treatment of pruritus in veterans exposed to sulfur mustard. This investigator-blinded, randomized, clinical trial was conducted in an outpatient dermatology clinic. Seventy-five men who were exposed to sulfur mustard 23 to 28 years ago during the Iran-Iraq war who complained of pruritus were randomized to receive doxepin cream 5% (n = 40) or betamethasone cream 0.1% (n = 35) twice a day for 6 weeks. Pruritus severity and Dermatology Life Quality Index (DLQI) were evaluated before and after each treatment. Both groups showed significant improvement regarding pruritus (P < .05), burning sensation, skin dryness (P < .001), and skin scaling (P < 0.05). The lesions of all regions significantly reduced after treatments (P < .05), except those on the head, face, and genitalia. Pruritus, visual analog scores, and DLQI significantly decreased (P < .01, P < .01, and P < .001, respectively) in doxepin- and betamethasone-treated groups, and there was no difference between groups. All DLQI subscores decreased after both type of treatments (P < .01). Equal efficacy of doxepin cream and betamethasone suggest that doxepin is a potential alternative to control pruritus caused by sulfur mustard in exposed veterans.

Novel mixed matrix membranes for sulfur removal and for fuel cell applications

NASA Astrophysics Data System (ADS)

Lin, Ligang; Wang, Andong; Zhang, Longhui; Dong, Meimei; Zhang, Yuzhong

2012-12-01

Sulfur removal is significant for fuels used as hydrogen source for fuel cell applications and to avoid sulfur poisoning of therein used catalysts. Novel mixed matrix membranes (MMMs) with well-defined transport channels are proposed for sulfur removal. MMMs are fabricated using polyimide (PI) as matrix material and Y zeolites as adsorptive functional materials. The influence of architecture conditions on the morphology transition from finger-like to sponge-like structure and the “short circuit” effect are investigated. The adsorption and regeneration behavior of MMMs is discussed, combining the detailed analysis of FT-IR, morphology, XPS, XRD and thermal properties of MMMs, the process-structure-function relationship is obtained. The results show that the functional zeolites are incorporated into three-dimensional network and the adsorption capacity of MMMs comes to 8.6 and 9.5 mg S g-1 for thiophene and dibenzothiophene species, respectively. And the regeneration behavior suggests that the spent membranes can recover about 88% and 96% of the desulfurization capacity by solvent washing and thermal treating regeneration, respectively. The related discussions provide some general suggestions in promoting the novel application of MMMs on the separation of organic-organic mixtures, and a potential alternative for the production of sulfur-free hydrogen source for fuel cell applications.

Using stable isotopes to monitor forms of sulfur during desulfurization processes: A quick screening method

USGS Publications Warehouse

Liu, Chao-Li; Hackley, Keith C.; Coleman, D.D.; Kruse, C.W.

1987-01-01

A method using stable isotope ratio analysis to monitor the reactivity of sulfur forms in coal during thermal and chemical desulfurization processes has been developed at the Illinois State Geological Survey. The method is based upon the fact that a significant difference exists in some coals between the 34S/32S ratios of the pyritic and organic sulfur. A screening method for determining the suitability of coal samples for use in isotope ratio analysis is described. Making these special coals available from coal sample programs would assist research groups in sorting out the complex sulfur chemistry which accompanies thermal and chemical processing of high sulfur coals. ?? 1987.

The respiratory health and lung function of Anglo-American children in a smelter town

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodge, R.

1983-02-01

Cooper smelters are large, usually isolated, sources of air pollution. Arizona has several such plants on the periphery of small communities. The smelters emit predominantly sulfur oxides and particulates, and the residents of these communities intermittently are exposed to high concentrations (24-h sulfur dioxide (SO2) . 250 to 500 micrograms/m3) of smelter smoke but little other pollution. This study compared the respiratory health of Anglo-American school children who lived in one smelter community with children living in another small community in Arizona that was free of smelter air pollution. The prevalence of cough, as determined by questionnaire, was 25.6% inmore » the smelter town children and 14.3% in the nonsmelter town children (p less than 0.05). Pulmonary function at the study onset was equal in the two groups. Over the course of the 4 yr of study, lung function growth (measured as actual forced expiratory volume in one second (FEV1) after 4 yr of study minus predicted FEV1) was also equal in the smelter town and nonsmelter town children. These results suggest that children in smelter communities have slightly more cough when compared with children living in other communities, but no differences in initial lung function or lung function at yearly testing over the period of the study.« less

The Biosynthesis of Nitrogen-, Sulfur-, and High-carbon Chain-containing Sugars†

PubMed Central

Lin, Chia-I; McCarty, Reid M.; Liu, Hung-wen

2013-01-01

Carbohydrates serve many structural and functional roles in biology. While the majority of monosaccharides are characterized by the chemical composition: (CH2O)n, modifications including deoxygenation, C-alkylation, amination, O- and N-methylation, which are characteristic of many sugar appendages of secondary metabolites, are not uncommon. Interestingly, some sugar molecules are formed via modifications including amine oxidation, sulfur incorporation, and “high-carbon” chain attachment. Most of these unusual sugars have been identified over the past several decades as components of microbially produced natural products, although a few high-carbon sugars are also found in the lipooligosaccharides of the outer cell walls of Gram-negative bacteria. Despite their broad distribution in nature, these sugars are considered “rare” due to their relative scarcity. The biosynthetic steps that underlie their formation continue to perplex researchers to this day and many questions regarding key transformations remain unanswered. This review will focus on our current understanding of the biosynthesis of unusual sugars bearing oxidized amine substituents, thio-functional groups, and high-carbon chains. PMID:23348524

Exome sequencing identifies NFS1 deficiency in a novel Fe-S cluster disease, infantile mitochondrial complex II/III deficiency.

PubMed

Farhan, Sali M K; Wang, Jian; Robinson, John F; Lahiry, Piya; Siu, Victoria M; Prasad, Chitra; Kronick, Jonathan B; Ramsay, David A; Rupar, C Anthony; Hegele, Robert A

2014-01-01

Iron-sulfur (Fe-S) clusters are a class of highly conserved and ubiquitous prosthetic groups with unique chemical properties that allow the proteins that contain them, Fe-S proteins, to assist in various key biochemical pathways. Mutations in Fe-S proteins often disrupt Fe-S cluster assembly leading to a spectrum of severe disorders such as Friedreich's ataxia or iron-sulfur cluster assembly enzyme (ISCU) myopathy. Herein, we describe infantile mitochondrial complex II/III deficiency, a novel autosomal recessive mitochondrial disease characterized by lactic acidemia, hypotonia, respiratory chain complex II and III deficiency, multisystem organ failure and abnormal mitochondria. Through autozygosity mapping, exome sequencing, in silico analyses, population studies and functional tests, we identified c.215G>A, p.Arg72Gln in NFS1 as the likely causative mutation. We describe the first disease in man likely caused by deficiency in NFS1, a cysteine desulfurase that is implicated in respiratory chain function and iron maintenance by initiating Fe-S cluster biosynthesis. Our results further demonstrate the importance of sufficient NFS1 expression in human physiology.

Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

NASA Technical Reports Server (NTRS)

Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

1990-01-01

The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

Antioxidative effects of sulfurous mineral water: protection against lipid and protein oxidation.

PubMed

Benedetti, S; Benvenuti, F; Nappi, G; Fortunati, N A; Marino, L; Aureli, T; De Luca, S; Pagliarani, S; Canestrari, F

2009-01-01

To investigate the antioxidative properties of sulfurous drinking water after a standard hydropinic treatment (500 ml day(-1) for 2 weeks). Forty apparently healthy adults, 18 men and 22 women, age 41-55 years old. The antioxidant profile and the oxidative condition were evaluated in healthy subjects supplemented for 2 weeks with (study group) or without (controls) sulfurous mineral water both before (T0) and after (T1) treatment. At T1, a significant decrease (P<0.05) in both lipid and protein oxidation products, namely malondialdehyde, carbonyls and AOPP, was found in plasma samples from subjects drinking sulfurous water with respect to controls. Concomitantly, a significant increment (P<0.05) of the total antioxidant capacity of plasma as well as of total plasmatic thiol levels was evidenced. Tocopherols, carotenoids and retinol remained almost unchanged before and after treatment in both groups. The improved body redox status in healthy volunteers undergoing a cycle of hydropinic therapy suggests major benefits from sulfurous water consumption in reducing biomolecule oxidation, possibly furnishing valid protection against oxidative damage commonly associated with aging and age-related degenerative diseases.

AtSufE is an essential activator of plastidic and mitochondrial desulfurases in Arabidopsis

PubMed Central

Xu, Xiang Ming; Møller, Simon Geir

2006-01-01

Iron–sulfur (Fe–S) clusters are vital prosthetic groups for Fe–S proteins involved in fundamental processes such as electron transfer, metabolism, sensing and signaling. In plants, sulfur (SUF) protein-mediated Fe–S cluster biogenesis involves iron acquisition and sulfur mobilization, processes suggested to be plastidic. Here we have shown that AtSufE in Arabidopsis rescues growth defects in SufE-deficient Escherichia coli. In contrast to other SUF proteins, AtSufE localizes to plastids and mitochondria interacting with the plastidic AtSufS and mitochondrial AtNifS1 cysteine desulfurases. AtSufE activates AtSufS and AtNifS1 cysteine desulfurization, and AtSufE activity restoration in either plastids or mitochondria is not sufficient to rescue embryo lethality in AtSufE loss-of-function mutants. AtSufE overexpression induces AtSufS and AtNifS1 expression, which in turn leads to elevated cysteine desulfurization activity, chlorosis and retarded development. Our data demonstrate that plastidic and mitochondrial Fe–S cluster biogenesis shares a common, essential component, and that AtSufE acts as an activator of plastidic and mitochondrial desulfurases in Arabidopsis. PMID:16437155

Design, fabrication and evaluation of intelligent sulfone-selective polybenzimidazole nanofibers.

PubMed

Ogunlaja, Adeniyi S; du Sautoy, Carol; Torto, Nelson; Tshentu, Zenixole R

2014-08-01

Molecularly imprinted polybenzimidazole nanofibers fabricated for the adsorption of oxidized organosulfur compounds are presented. The imprinted polymers exhibited better selectivity for their target model sulfone-containing compounds with adsorption capacities of 28.5±0.4mg g(-1), 29.8±2.2mg g(-1) and 20.1±1.4mg g(-1) observed for benzothiophene sulfone (BTO2), dibenzothiophene sulfone (DBTO2) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO2) respectively. Molecular modeling based upon the density functional theory (DFT) indicated that hydrogen bond interactions may take place between sulfone oxygen groups with NH groups of the PBI. Further DFT also confirmed the feasibility of π-π interactions between the benzimidazole rings and the aromatic sulfone compounds. The adsorption mode followed the Freundlich (multi-layered) adsorption isotherm which indicated possible sulfone-sulfone interactions. A home-made pressurized hot water extraction (PHWE) system was employed for the extraction/desorption of sulfone compounds within imprinted nanofibers at 1mL min(-1), 150°C and 30 bar. PHWE used a green solvent (water) and achieved better extraction yields compared to the Soxhlet extraction process. The application of molecularly imprinted polybenzimidazole (PBI) nanofibers displayed excellent sulfur removal, with sulfur in fuel after adsorption falling below the determined limit of detection (LOD), which is 2.4mg L(-1)S, and with a sulfur adsorption capacity of 5.3±0.4mg g(-1) observed for application in the fuel matrix. Copyright © 2014 Elsevier B.V. All rights reserved.

Sulfur metabolism in Escherichia coli and related bacteria: facts and fiction.

PubMed

Sekowska, A; Kung, H F; Danchin, A

2000-04-01

Living organisms are composed of macromolecules made of hydrogen, carbon, nitrogen, oxygen, phosphorus and sulfur. Much work has been devoted to the metabolism of the first five elements, but much remains to be understood about sulfur metabolism. We review here the situation in Escherichia coli and related bacteria, where more than one hundred genes involved in sulfur metabolism have already been discovered in this organism. Examination of the genome suggests that many more will be found, especially genes involved in regulation, scavenging of sulfur containing molecules and synthesis of coenzymes or prosthetic groups. Furthermore, the involvement of methionine as the universal start of proteins as well as that of its derivative S-adenosylmethionine in a vast variety of cell processes argue in favour of a major importance of sulfur metabolism in all organisms.

Metal sulfide and rare-earth phosphate nanostructures and methods of making same

DOEpatents

Wong, Stanislaus; Zhang, Fen

2014-05-13

The present invention provides a method of producing a crystalline metal sulfide nanostructure. The metal is a transitional metal or a Group IV metal. In the method, a porous membrane is placed between a metal precursor solution and a sulfur precursor solution. The metal cations of the metal precursor solution and sulfur ions of the sulfur precursor solution react, thereby producing a crystalline metal sulfide nanostructure.

Emergency and Continuous Exposure Limits for Selected Airborne Contaminants. Volume 2

DTIC Science & Technology

1984-10-01

21, fluorocarbon 113, fluorocarbon 114, isopropyl alcohol, phosgene, sodium hydroxide, sulfur dioxide, vinylidene chloride . xylene. b. Identlflers/Open...fluorocarbon 114, isopropyl alcohol, phosgene, sodium hydroxide, sulfur dioxide, vinylidene chloride , xylene. c. COSATI Field/Group 1I. Availability Statement...Hydroxide 87 Sulfur Dioxide 95 Vinylidene Chloride 103 Xylene 113 -" , 0°. •. .. : V.•. ., , • .’’-.’ .’.’ INTRODUCTION The National Research Council’s

Evolution of Fe/S cluster biogenesis in the anaerobic parasite Blastocystis

PubMed Central

Tsaousis, Anastasios D.; Ollagnier de Choudens, Sandrine; Gentekaki, Eleni; Long, Shaojun; Gaston, Daniel; Stechmann, Alexandra; Vinella, Daniel; Py, Béatrice; Fontecave, Marc; Barras, Frédéric; Lukeš, Julius; Roger, Andrew J.

2012-01-01

Iron/sulfur cluster (ISC)-containing proteins are essential components of cells. In most eukaryotes, Fe/S clusters are synthesized by the mitochondrial ISC machinery, the cytosolic iron/sulfur assembly system, and, in photosynthetic species, a plastid sulfur-mobilization (SUF) system. Here we show that the anaerobic human protozoan parasite Blastocystis, in addition to possessing ISC and iron/sulfur assembly systems, expresses a fused version of the SufC and SufB proteins of prokaryotes that it has acquired by lateral transfer from an archaeon related to the Methanomicrobiales, an important lineage represented in the human gastrointestinal tract microbiome. Although components of the Blastocystis ISC system function within its anaerobic mitochondrion-related organelles and can functionally replace homologues in Trypanosoma brucei, its SufCB protein has similar biochemical properties to its prokaryotic homologues, functions within the parasite’s cytosol, and is up-regulated under oxygen stress. Blastocystis is unique among eukaryotic pathogens in having adapted to its parasitic lifestyle by acquiring a SUF system from nonpathogenic Archaea to synthesize Fe/S clusters under oxygen stress. PMID:22699510

Chemical Probes for Molecular Imaging and Detection of Hydrogen Sulfide and Reactive Sulfur Species in Biological Systems

PubMed Central

2014-01-01

Hydrogen sulfide (H2S), a gaseous species produced by both bacteria and higher eukaryotic organisms, including mammalian vertebrates, has attracted attention in recent years for its contributions to human health and disease. H2S has been proposed as a cytoprotectant and gasotransmitter in many tissue types, including mediating vascular tone in blood vessels as well as neuromodulation in the brain. The molecular mechanisms dictating how H2S affects cellular signaling and other physiological events remain insufficiently understood. Furthermore, the involvement of H2S in metal-binding interactions and formation of related RSS such as sulfane sulfur may contribute to other distinct signaling pathways. Owing to its widespread biological roles and unique chemical properties, H2S is an appealing target for chemical biology approaches to elucidate its production, trafficking, and downstream function. In this context, reaction-based fluorescent probes offer a versatile set of screening tools to visualize H2S pools in living systems. Three main strategies used in molecular probe development for H2S detection include azide and nitro group reduction, nucleophilic attack, and CuS precipitation. Each of these approaches exploit the strong nucleophilicity and reducing potency of H2S to achieve selectivity over other biothiols. In addition, a variety of methods have been developed for the detection of other reactive sulfur species (RSS), including sulfite and bisulfite, as well as sulfane sulfur species and related modifications such as S-nitrosothiols. Access to this growing chemical toolbox of new molecular probes for H2S and related RSS sets the stage for applying these developing technologies to probe reactive sulfur biology in living systems. PMID:25474627

The efficacy of oral ivermectin vs. sulfur 10% ointment for the treatment of scabies.

PubMed

Alipour, Human; Goldust, Mohamad

2015-01-01

Human scabies is caused by an infection of the skin by the human itch mite (Sarcoptes scabiei var. hominis). There are different medications for the treatment of scabies. This study aimed at comparing the efficacy and safety of oral ivermectin vs. sulfur 10% ointment for the treatment of scabies. In total, 420 patients with scabies were enrolled, and randomized into two groups: the first group received a single dose of oral ivermectin 200 μg/kg body weight, and the second group received sulfur 10% ointment and were told to apply this for three successive days. Treatment was evaluated at intervals of 2 and 4 weeks, and if there was treatment failure at the 2-week follow-up, treatment was repeated. A single dose of ivermectin provided a cure rate of 61.9% at the 2-week follow-up, which increased to 78.5% at the 4-week follow-up after repeating the treatment. Treatment with single applications of sulfur 10% ointment was effective in 45.2% of patients at the 2-week follow-up, which increased to 59.5% at the 4-week follow-up after this treatment was repeated. A single dose of ivermectin was as effective as single applications of sulfur 10% ointment at the 2-week follow-up. After repeating the treatment, ivermectin was superior to sulfur 10% ointment at the 4-week follow up. The delay in clinical response with ivermectin suggests that it may not be effective against all the stages in the life cycle of the parasite. .

Method of making a current collector for a sodium/sulfur battery

DOEpatents

Tischer, R.P.; Winterbottom, W.L.; Wroblowa, H.S.

1987-03-10

This specification is directed to a method of making a current collector for a sodium/sulfur battery. The current collector so-made is electronically conductive and resistant to corrosive attack by sulfur/polysulfide melts. The method includes the step of forming the current collector for the sodium/sulfur battery from a composite material formed of aluminum filled with electronically conductive fibers selected from the group of fibers consisting essentially of graphite fibers having a diameter up to 10 microns and silicon carbide fibers having a diameter in a range of 500--1,000 angstroms. 2 figs.

Method of making a current collector for a sodium/sulfur battery

DOEpatents

Tischer, Ragnar P.; Winterbottom, Walter L.; Wroblowa, Halina S.

1987-01-01

This specification is directed to a method of making a current collector (14) for a sodium/sulfur battery (10). The current collector so-made is electronically conductive and resistant to corrosive attack by sulfur/polysulfide melts. The method includes the step of forming the current collector for the sodium/sulfur battery from a composite material (16) formed of aluminum filled with electronically conductive fibers selected from the group of fibers consisting essentially of graphite fibers having a diameter up to 10 microns and silicon carbide fibers having a diameter in a range of 500-1000 angstroms.

Optical Absorption and Electric Resistivity of an l-Cysteine Film

NASA Astrophysics Data System (ADS)

Kamada, Masao; Hideshima, Takuya; Azuma, Junpei; Yamamoto, Isamu; Imamura, Masaki; Takahashi, Kazutoshi

2016-12-01

The optical and electric properties of an l-cysteine film have been investigated to understand its applicability to bioelectronics. The fundamental absorption is the allowed transition having the threshold at 5.8 eV and the absorption is due to the charge-transfer type transition from sulfur-3sp to oxygen-2p and/or carbon-2p states, while absorptions more than 9 eV can be explained with intra-atomic transitions in the functional groups. The electric resistivity is 2.0 × 104 Ω m at room temperature and increases as the sample temperature decreases. The results indicate that the l-cysteine film is a p-type semiconductor showing the hole conduction caused by the sulfur-3sp occupied states and unknown impurity or defect states as acceptors. The electron affinity of the l-cysteine film is derived as ≦-0.3 eV.

Catalytic, Enantioselective Sulfenofunctionalisation of Alkenes: Mechanistic, Crystallographic, and Computational Studies

PubMed Central

Denmark, Scott E.; Hartmann, Eduard; Kornfilt, David J. P.; Wang, Hao

2015-01-01

The stereocontrolled introduction of vicinal heteroatomic substituents into organic molecules is one of the most powerful ways of adding value and function. Whereas many methods exist for the introduction of oxygen- and nitrogen-containing substituents, the number stereocontrolled methods for the introduction of sulfur-containing substituents pales by comparison. Previous reports from these laboratories have described the sulfenofunctionalization of alkenes that construct vicinal carbon-sulfur and carbon-oxygen, carbon-nitrogen as well as carbon-carbon bonds with high levels of diastereospecificity and enantioselectivity. This process is enabled by the concept of Lewis base activation of Lewis acids that provides activation of Group 16 electrophiles. To provide a foundation for expansion of substrate scope and improved selectivities, we have undertaken a comprehensive study of the catalytically active species. Insights gleaned from kinetic, crystallographic and computational methods have led to the introduction of a new family of sulfenylating agents that provide significantly enhanced selectivities. PMID:25411883

Synthesis of three-dimensionally interconnected sulfur-rich polymers for cathode materials of high-rate lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Kim, Hoon; Lee, Joungphil; Ahn, Hyungmin; Kim, Onnuri; Park, Moon Jeong

2015-06-01

Elemental sulfur is one of the most attractive cathode active materials in lithium batteries because of its high theoretical specific capacity. Despite the positive aspect, lithium-sulfur batteries have suffered from severe capacity fading and limited rate capability. Here we report facile large-scale synthesis of a class of organosulfur compounds that could open a new chapter in designing cathode materials to advance lithium-sulfur battery technologies. Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases. Our lithium-sulfur cells display discharge capacity of 945 mAh g-1 after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles. Particularly, the organized amine groups in the crystals increase Li+-ion transfer rate, affording a rate performance of 1210, mAh g-1 at 0.1 C and 730 mAh g-1 at 5 C.

Synthesis of three-dimensionally interconnected sulfur-rich polymers for cathode materials of high-rate lithium–sulfur batteries

PubMed Central

Kim, Hoon; Lee, Joungphil; Ahn, Hyungmin; Kim, Onnuri; Park, Moon Jeong

2015-01-01

Elemental sulfur is one of the most attractive cathode active materials in lithium batteries because of its high theoretical specific capacity. Despite the positive aspect, lithium–sulfur batteries have suffered from severe capacity fading and limited rate capability. Here we report facile large-scale synthesis of a class of organosulfur compounds that could open a new chapter in designing cathode materials to advance lithium–sulfur battery technologies. Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases. Our lithium–sulfur cells display discharge capacity of 945 mAh g−1 after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles. Particularly, the organized amine groups in the crystals increase Li+-ion transfer rate, affording a rate performance of 1210, mAh g−1 at 0.1 C and 730 mAh g−1 at 5 C. PMID:26065407

[Quality assessment of sulfur-fumigated paeoniae alba radix].

PubMed

Wang, Zhao; Chen, Yu-Wu; Wang, Qiong; Sun, Lei; Xu, Wei-Yi; Jin, Hong-Yu; Ma, Shuang-Cheng

2014-08-01

The samples of sulfur-fumigated Paeoniae Alba Radix acquired both by random spot check from domestic market and self-production by the research group in the laboratory were used to evaluate the effects of sulphur fumigation on the quality of Paeoniae Alba Radix by comparing sulfur-fumigated degree and character, the content of paeoniflorin and paeoniflorin sulfurous acid ester, and changes of the fingerprint. We used methods in Chinese Pharmacopeia to evaluate the character of sulfur-fumigated Paeoniae Alba Radix and determinate the content of aulfur-fumigated paeoniflorin. LC-MS method was used to analyze paeoniflorin-converted products. HPLC fingerprint methods were established to evaluate the differences on quality by similarity. Results showed that fumigated Paeoniae Alba Radix became white and its unique fragrance disappeared, along with the production of pungent sour gas. It also had a significant effect on paeoniflorin content. As sulfur smoked degree aggravated, paeoniflorin content decreased subsequently, some of which turned into paeoniflorin sulfurous acid ester, and this change was not reversible. Fingerprint also showed obvious changes. Obviously, sulfur fumigation had severe influence on the quality of Paeoniae Alba Radix, but we can control the quality of the Paeoniae Alba Radix by testing the paeoniflorin sulfurous acid ester content.

Efficient sulfur host based on NiCo2O4 hollow microtubes for advanced Li-S batteries

NASA Astrophysics Data System (ADS)

Iqbal, Azhar; Ali Ghazi, Zahid; Muqsit Khattak, Abdul; Ahmad, Aziz

2017-12-01

High energy density and cost effectiveness make lithium-sulfur battery a promising candidate for next-generation electrochemical energy storage technology. Here, we have synthesized a highly efficient sulfur host namely NiCo2O4 hollow microtubes/sulfur composite (NiCo2O4/S). The hollow interior cavity providing structural integrity while sufficient self-functionalized surfaces of NiCo2O4 chemically bind polysulfides to prevent their dissolution in the organic electrolyte. When used in lithium-sulfur batteries, the synthesized NiCo2O4/S cathode delivers high specific capacity (1274 mAh g-1 at 0.2 C), long cycling performance at 0.5 C, and good rate capability at high current rates.

Chemisorption of polysulfides through redox reactions with organic molecules for lithium-sulfur batteries.

PubMed

Li, Ge; Wang, Xiaolei; Seo, Min Ho; Li, Matthew; Ma, Lu; Yuan, Yifei; Wu, Tianpin; Yu, Aiping; Wang, Shun; Lu, Jun; Chen, Zhongwei

2018-02-16

Lithium-sulfur battery possesses high energy density but suffers from severe capacity fading due to the dissolution of lithium polysulfides. Novel design and mechanisms to encapsulate lithium polysulfides are greatly desired by high-performance lithium-sulfur batteries towards practical applications. Herein, we report a strategy of utilizing anthraquinone, a natural abundant organic molecule, to suppress dissolution and diffusion of polysulfides species through redox reactions during cycling. The keto groups of anthraquinone play a critical role in forming strong Lewis acid-based chemical bonding. This mechanism leads to a long cycling stability of sulfur-based electrodes. With a high sulfur content of ~73%, a low capacity decay of 0.019% per cycle for 300 cycles and retention of 81.7% over 500 cycles at 0.5 C rate can be achieved. This finding and understanding paves an alternative avenue for the future design of sulfur-based cathodes toward the practical application of lithium-sulfur batteries.

Effect of sulfur removal on Al2O3 scale adhesion

NASA Astrophysics Data System (ADS)

Smialek, James L.

1991-03-01

If the role of reactive element dopants in producing A12O3 scale adhesion on NiCrAl alloys is to getter sulfur and prevent interfacial segregation, then eliminating sulfur from undoped alloys should also produce adherence. Four experiments successfully produced scale adhesion by sulfur removal alone. (1) Repeated oxidation and polishing of a pure NiCrAl alloy lowered the sulfur content from 10 to 2 parts per million by weight (ppmw), presumably by removing the segregated interfacial layer after each cycle. Total scale spallation changed to total retention after 13 such cycles, with no changes in the scale or interfacial morphology. (2) Thinner samples became adherent after fewer oxidation polishing cycles because of a more limited supply of sulfur. (3) Spalling in subsequent cyclic oxidation tests of samples from experiment (1) was a direct function of the initial sulfur content. (4) Desulfurization to 0.1 ppmw levels was accomplished by annealing melt-spun foil in 1 arm H2. These foils produced oxidation weight change curves for 500 1-hour cycles at 1100 °C similar to those for Y- or Zr-doped NiCrAl. The transition between adherent and nonadherent behavior was modeled in terms of sulfur flux, sulfur content, and sulfur segregation.

Liquid Sulfur Impregnation of Microporous Carbon Accelerated by Nanoscale Interfacial Effects

DOE PAGES

Pascal, Tod A.; Villaluenga, Irune; Wujcik, Kevin H.; ...

2017-03-14

Impregnation of porous carbon matrices with liquid sulfur has been exploited to fabricate composite cathodes for lithium-sulfur batteries, aimed at confining soluble sulfur species near conducting carbon to prevent both loss of active material into the electrolyte and parasitic reactions at the lithium metal anode. Here, through extensive computer simulations, we uncover the strongly favorable interfacial free energy between liquid sulfur and graphitic surfaces that underlies this phenomenon. Previously unexplored curvature-dependent enhancements are shown to favor the filling of smaller pores first and effect a quasi-liquid sulfur phase in microporous domains (diameters <2 nm) that persists ~30° below the expectedmore » freezing point. Evidence of interfacial sulfur on carbon is shown to be a 0.3 eV red shift in the simulated and measured interfacial X-ray absorption spectra. Our results elucidate the critical morphology and thermodynamic properties necessary for future cathode design and highlight the importance of molecular-scale details in defining emergent properties of functional nanoscale interfaces.« less

Liquid Sulfur Impregnation of Microporous Carbon Accelerated by Nanoscale Interfacial Effects.

PubMed

Pascal, Tod A; Villaluenga, Irune; Wujcik, Kevin H; Devaux, Didier; Jiang, Xi; Wang, Dunyang Rita; Balsara, Nitash; Prendergast, David

2017-04-12

Impregnation of porous carbon matrices with liquid sulfur has been exploited to fabricate composite cathodes for lithium-sulfur batteries, aimed at confining soluble sulfur species near conducting carbon to prevent both loss of active material into the electrolyte and parasitic reactions at the lithium metal anode. Here, through extensive computer simulations, we uncover the strongly favorable interfacial free energy between liquid sulfur and graphitic surfaces that underlies this phenomenon. Previously unexplored curvature-dependent enhancements are shown to favor the filling of smaller pores first and effect a quasi-liquid sulfur phase in microporous domains (diameters <2 nm) that persists ∼30° below the expected freezing point. Evidence of interfacial sulfur on carbon is shown to be a 0.3 eV red shift in the simulated and measured interfacial X-ray absorption spectra. Our results elucidate the critical morphology and thermodynamic properties necessary for future cathode design and highlight the importance of molecular-scale details in defining emergent properties of functional nanoscale interfaces.

Origin of electrolyte-dopant dependent sulfur poisoning of SOFC anodes.

PubMed

Zeng, ZhenHua; Björketun, Mårten E; Ebbesen, Sune; Mogensen, Mogens B; Rossmeisl, Jan

2013-05-14

The mechanisms governing the sulfur poisoning of the triple phase boundary (TPB) of Ni-XSZ (X2O3 stabilized zirconia) anodes have been investigated using density functional theory. The calculated sulfur adsorption energies reveal a clear correlation between the size of the cation dopant X(3+) and the sulfur tolerance of the Ni-XSZ anode; the smaller the ionic radius, the higher the sulfur tolerance. The mechanistic study shows that the size of X(3+) strongly influences XSZ's surface energy, which in turn determines the adhesion of Ni to XSZ. The Ni-XSZ interaction has a direct impact on the Ni-S interaction and on the relative stability of reconstructed and pristine Ni(100) facets at the TPB. Together, these two effects control the sulfur adsorption on the Ni atoms at the TPB. The established relationships explain experimentally observed dopant-dependent anode performances and provide a blueprint for the future search for and preparation of highly sulfur tolerant anodes.

Development and testing of a PEM SO 2-depolarized electrolyzer and an operating method that prevents sulfur accumulation

DOE PAGES

Steimke, John L.; Steeper, Timothy J.; Colon-Mercado, Hector R.; ...

2015-09-02

The hybrid sulfur (HyS) cycle is being developed as a technology to generate hydrogen by splitting water, using heat and electrical power from a nuclear or solar power plant. A key component is the SO 2-depolarized electrolysis (SDE) cell, which reacts SO 2 and water to form hydrogen and sulfuric acid. SDE could also be used in once-through operation to consume SO 2 and generate hydrogen and sulfuric acid for sale. A proton exchange membrane (PEM) SDE cell based on a PEM fuel cell design was fabricated and tested. Measured cell potential as a function of anolyte pressure and flowmore » rate, sulfuric acid concentration, and cell temperature are presented for this cell. Sulfur accumulation was observed inside the cell, which could have been a serious impediment to further development. A method to prevent sulfur formation was subsequently developed. As a result, this was made possible by a testing facility that allowed unattended operation for extended periods.« less

Development and testing of a PEM SO 2-depolarized electrolyzer and an operating method that prevents sulfur accumulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steimke, John L.; Steeper, Timothy J.; Colon-Mercado, Hector R.

The hybrid sulfur (HyS) cycle is being developed as a technology to generate hydrogen by splitting water, using heat and electrical power from a nuclear or solar power plant. A key component is the SO 2-depolarized electrolysis (SDE) cell, which reacts SO 2 and water to form hydrogen and sulfuric acid. SDE could also be used in once-through operation to consume SO 2 and generate hydrogen and sulfuric acid for sale. A proton exchange membrane (PEM) SDE cell based on a PEM fuel cell design was fabricated and tested. Measured cell potential as a function of anolyte pressure and flowmore » rate, sulfuric acid concentration, and cell temperature are presented for this cell. Sulfur accumulation was observed inside the cell, which could have been a serious impediment to further development. A method to prevent sulfur formation was subsequently developed. As a result, this was made possible by a testing facility that allowed unattended operation for extended periods.« less

Microbial community functional structure in response to micro-aerobic conditions in sulfate-reducing sulfur-producing bioreactor.

PubMed

Yu, Hao; Chen, Chuan; Ma, Jincai; Xu, Xijun; Fan, Ronggui; Wang, Aijie

2014-05-01

Limited oxygen supply to anaerobic wastewater treatment systems had been demonstrated as an effective strategy to improve elemental sulfur (S(0)) recovery, coupling sulfate reduction and sulfide oxidation. However, little is known about the impact of dissolved oxygen (DO) on the microbial functional structures in these systems. We used a high throughput tool (GeoChip) to evaluate the microbial community structures in a biological desulfurization reactor under micro-aerobic conditions (DO: 0.02-0.33 mg/L). The results indicated that the microbial community functional compositions and structures were dramatically altered with elevated DO levels. The abundances of dsrA/B genes involved in sulfate reduction processes significantly decreased (p < 0.05, LSD test) at relatively high DO concentration (DO: 0.33 mg/L). The abundances of sox and fccA/B genes involved in sulfur/sulfide oxidation processes significantly increased (p < 0.05, LSD test) in low DO concentration conditions (DO: 0.09 mg/L) and then gradually decreased with continuously elevated DO levels. Their abundances coincided with the change of sulfate removal efficiencies and elemental sulfur (S(0)) conversion efficiencies in the bioreactor. In addition, the abundance of carbon degradation genes increased with the raising of DO levels, showing that the heterotrophic microorganisms (e.g., fermentative microorganisms) were thriving under micro-aerobic condition. This study provides new insights into the impacts of micro-aerobic conditions on the microbial functional structure of sulfate-reducing sulfur-producing bioreactors, and revealed the potential linkage between functional microbial communities and reactor performance. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Removal of SO2 from O2-containing flue gas by activated carbon fiber (ACF) impregnated with NH3.

PubMed

Xu, Lüsi; Guo, Jia; Jin, Feng; Zeng, Hancai

2006-02-01

Adsorption of SO(2) from the O(2)-containing flue gas by granular activated carbons (GACs) and activated carbon fibers (ACFs) impregnated with NH(3) was studied in this technical note. Experimental results showed that the ACFs were high-quality adsorbents due to their unique textural properties. In the presence of moisture, the desulphurization efficiency for the ACFs was improved significantly due to the formation of sulfuric acid. After NH(3) impregnation of ACF samples, nitrogen-containing functional groups (pyridyl C(5)H(4)N- and pyrrolyl C(4)H(4)N-) were detected on the sample surface by using an X-ray photoelectron spectrometer. These functional groups accounted for the enhanced SO(2) adsorption via chemisorption and/or catalytic oxidization.

Experiments on δ34S mixing between organic and inorganic sulfur species during thermal maturation

USGS Publications Warehouse

Amrani, Alon; Said-Ahamed, Ward; Lewan, Michael D.; Aizenshtat, Zeev

2006-01-01

Reduced sulfur species were studied to constrain isotopic exchange-mixing with synthetic polysulfide cross-linked macromolecules (PCLM), model sulfur containing molecules and natural sulfur-rich kerogen, asphalt and oil of the Dead Sea area. PCLM represents protokerogens that are rich in sulfur and thermally unstable. Mixing rates of PCLM with HS-(aq) (added as (NH4)2S(aq)) at low to moderate temperatures (50–200 °C) are rapid. Elemental sulfur and H2S(gas) fully mix isotopes with PCLM during pyrolysis conditions at 200 °C. During these reactions significant structural changes of the PCLM occur to form polysulfide dimers, thiolanes and thiophenes. As pyrolysis temperatures or reaction times increase, the PCLM thermal products are transformed to more aromatic sulfur compounds. Isotopic mixing rates increase with increasing pyrolysis temperature and time. Polysulfide bonds (S–S) in the PCLM are responsible for most of these structural and isotopic changes because of their low stability. Conversely, sulfur isotope mixing does not occur between dibenzothiophene (aromatic S) or hexadecanthiol (C–SH) and HS-(aq) at 200 °C after 48 h. This shows that rates of sulfur isotope mixing are strongly dependent on the functionality of the sulfur in the organic matter. The order of isotopic mixing rates for organic matter is kerogen > asphalt > oil, which is inverse to their sulfur thermal stability. Asphalt and oil with more refractory sulfur show significantly lower isotopes mixing rates than the kerogen with more labile sulfur. Based on the findings of the present study we suggest that sulfur isotopes mixing can occur from early diagenesis into catagenesis and result in isotopic homogenization of the inorganic and organic reduced sulfur pools.

Proteomic Insights into Sulfur Metabolism in the Hydrogen-Producing Hyperthermophilic Archaeon Thermococcus onnurineus NA1

PubMed Central

Moon, Yoon-Jung; Kwon, Joseph; Yun, Sung-Ho; Lim, Hye Li; Kim, Jonghyun; Kim, Soo Jung; Kang, Sung Gyun; Lee, Jung-Hyun; Kim, Seung Il; Chung, Young-Ho

2015-01-01

The hyperthermophilic archaeon Thermococcus onnurineus NA1 has been shown to produce H2 when using CO, formate, or starch as a growth substrate. This strain can also utilize elemental sulfur as a terminal electron acceptor for heterotrophic growth. To gain insight into sulfur metabolism, the proteome of T. onnurineus NA1 cells grown under sulfur culture conditions was quantified and compared with those grown under H2-evolving substrate culture conditions. Using label-free nano-UPLC-MSE-based comparative proteomic analysis, approximately 38.4% of the total identified proteome (589 proteins) was found to be significantly up-regulated (≥1.5-fold) under sulfur culture conditions. Many of these proteins were functionally associated with carbon fixation, Fe–S cluster biogenesis, ATP synthesis, sulfur reduction, protein glycosylation, protein translocation, and formate oxidation. Based on the abundances of the identified proteins in this and other genomic studies, the pathways associated with reductive sulfur metabolism, H2-metabolism, and oxidative stress defense were proposed. The results also revealed markedly lower expression levels of enzymes involved in the sulfur assimilation pathway, as well as cysteine desulfurase, under sulfur culture condition. The present results provide the first global atlas of proteome changes triggered by sulfur, and may facilitate an understanding of how hyperthermophilic archaea adapt to sulfur-rich, extreme environments. PMID:25915030

Flash pyrolysis of coal, coal maceral, and coal-derived pyrite with on-line characterization of volatile sulfur compounds

USGS Publications Warehouse

Chou, I.-Ming; Lake, M.A.; Griffin, R.A.

1988-01-01

A Pyroprobe flash pyrolysis-gas chromatograph equipped with a flame photometric detector was used to study volatile sulfur compounds produced during the thermal decomposition of Illinois coal, coal macerals and coal-derived pyrite. Maximum evolution of volatile organic sulfur compounds from all coal samples occurred at a temperature of approximately 700??C. At this temperature, the evolution of thiophene, its alkyl isomers, and short-chain dialkyl sulfide compounds relative to the evolution of benzothiophene and dibenzothiophene compounds was greater from coal high in organic sulfur than from coal low in organic sulfur. The variation in the evolution of sulfur compounds observed for three separate coal macerals (exinite, vitrinite, and inertinite) was similar to that observed for whole coal samples. However, the variation trend for the macerals was much more pronounced. Decomposition of coal-derived pyrite with the evolution of elemental sulfur was detected at a temperature greater than 700??C. The results of this study indicated that the gas chromotographic profile of the volatile sulfur compounds produced during flash pyrolysis of coals and coal macerals varied as a function of the amount of organic sulfur that occurred in the samples. Characterization of these volatile sulfur compounds provides a better understanding of the behavior of sulfur in coal during the thermolysis process, which could be incorporated in the design for coal cleaning using flash pyrolysis techniques. ?? 1988.

Defining the physiologically normal coating and pathological deposit: an analysis of sulfur-containing moieties and pellicle thickness on hydrogel contact lenses.

PubMed

Hart, D E; Plociniak, M P; Grimes, G W

1998-04-01

Historically, biochemical studies of the interaction between tears and hydrogel contact lenses have not been coordinated with the study of the morphological ultrastructure of the phenomena. Moreover, terms that have distinct and different meanings--pellicle, coating, deposit, and biofilm--have been used interchangeably and often incorrectly when applied within the context of the general field of contact lens biotechnology to describe the tear-polymer interaction. We describe our elucidation of morphological and elemental characteristics of the normal pellicle that forms on the lens surface and urge standard use of the word "pellicle" to specify this entity. Fourteen worn hydrogel lenses (8 Group 1 and 6 Group 4 lenses according to the FDA classification) were rinsed, quartered, and fixed or dried, depending on the analysis to be performed. Scanning electron microscopy (SEM) was used to examine the morphology of the pellicle and quantify its thickness. X-ray analysis was used to detect elements associated with the anterior, central, and posterior portions of the lenses and their relative distribution. A distinctive morphological pellicle ranging from 0.1 to 8.6 microns was present on 12 of the 14 lenses. The pellicle was thicker on the Group 4 lenses than on the Group 1 lenses (P < 0.003). However, the pellicle on Group 1 lenses became thicker with increasing lens age (P < 0.02), but not as thick as on Group 4 lenses. Morphologically distinct lipid or jelly bump deposits were observed at the surface of both lenses from a single patient wearing 2 week old Group 4 lenses. Eleven lenses had sulfur-bearing tear components on the anterior zone. Sulfur was deposited within the matrix of nine lenses. The sulfur containing moieties were more prevalent on Group 4 lenses (P < 0.002). More sulfur was assayed on older lenses (P < 0.004). The anterior lens zone had more sulfur-bearing tear components than did the posterior or center zones (P < 0.05). The physiologically normal pellicle is a distinct morphological entity covering the anterior lens surface. Abnormal deposits such as the discrete microgel region, known as jelly bumps, are not part of the physiologically normal pellicle at the anterior lens surface and have the potential to induce pathology. Sulfur-containing moieties within the matrix may represent the breakdown of large proteins and mucoproteins or intact proteins, as well as contaminants such as cosmetics and environmental pollutants. It is also possible that entire small proteins, such as lysozyme, impregnate the matrix. The moieties that become entrapped within the matrix or rigidly adhere to the matrix should be considered true deposits.

Synthesis and characterization of sulfur functionalized graphene oxide nanosheets as efficient sorbent for removal of Pb2+, Cd2+, Ni2+ and Zn2+ ions from aqueous solution: A combined thermodynamic and kinetic studies

NASA Astrophysics Data System (ADS)

Pirveysian, Mahtab; Ghiaci, Mehran

2018-01-01

A very simple, one pot method was used for preparation of sulfur functionalized graphene oxide (GO-SOxR) with sodium sulfide and water in reflux condition. The elemental analysis data showed high sulfur content up to 15%. EDS and XPS analysis also proved introduction of sulfur element. To make the sorbent more efficient operationally, the GO-SOxR was coated with a mesoporous shell of TiO2 or SiO2. The prepared sorbents were characterized by SEM, TEM, TGA, XPS, XRD, IR and EDS. GO-SOxR@TiO2 and GO-SOxR@SiO2 composites were tested for removal of Pb(II), Cd(II), Ni(II) and Zn(II) as heavy metal ions from aqueous solution in batch method. Adsorption of the heavy metal ions was studied kinetically, and the adsorption capacities of GO-SOxR, GO-SOxR@TiO2, and GO-SOxR@SiO2 were evaluated using equilibrium adsorption isotherms, and compared to other adsorbents used for removal of these heavy metals. Kinetic studies showed that the experimental data was fitted with pseudo second order model. The adsorption capacity of GO was significantly improved by sulfur functionalization and TiO2 coating.

Use of Elemental Sulfur or Selenium in a Novel One-Pot Copper-Catalyzed Tandem Cyclization of Functionalized Ynamides Leading to Benzosultams.

PubMed

Siva Reddy, Alla; Kumara Swamy, K C

2015-06-19

A novel and efficient [Cu]-catalyzed one-pot regio- and stereospecific synthesis of benzo[1,4,2]dithiazine 1,1-dioxides and benzo[1,4,2]thiaselenazine 1,1-dioxides by cyclization of functionalized ynamides with elemental sulfur/selenium has been developed. Its generality is elegantly illustrated by extension to benzodithiazepines and benzothiaselenazepines. Involvement of water in the reaction is demonstrated by the incorporation of (2)D at the olefinic site by using D2O in place of water. Selective oxidation at sulfur in benzo[1,4,2]dithiazine 1,1-dioxide by using mCPBA as the oxidizing agent is also described.

Confined Sulfur in 3 D MXene/Reduced Graphene Oxide Hybrid Nanosheets for Lithium-Sulfur Battery.

PubMed

Bao, Weizhai; Xie, Xiuqiang; Xu, Jing; Guo, Xin; Song, Jianjun; Wu, Wenjian; Su, Dawei; Wang, Guoxiu

2017-09-12

Three-dimensional metal carbide MXene/reduced graphene oxide hybrid nanosheets are prepared and applied as a cathode host material for lithium-sulfur batteries. The composite cathodes are obtained through a facile and effective two-step liquid-phase impregnation method. Owing to the unique 3 D layer structure and functional 2 D surfaces of MXene and reduced graphene oxide nanosheets for effective trapping of sulfur and lithium polysulfides, the MXene/reduced graphene oxide/sulfur composite cathodes deliver a high initial capacity of 1144.2 mAh g -1 at 0.5 C and a high level of capacity retention of 878.4 mAh g -1 after 300 cycles. It is demonstrated that hybrid metal carbide MXene/reduced graphene oxide nanosheets could be a promising cathode host material for lithium-sulfur batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sardasht-Iran cohort study of chemical warfare victims: design and methods.

PubMed

Ghazanfari, Tooba; Faghihzadeh, Soghrat; Aragizadeh, Hassan; Soroush, Mohammad-Reza; Yaraee, Roya; Mohammad Hassan, Zuhair; Foroutan, Abbas; Vaez-Mahdavi, Mohammad-Reza; Javadi, Mohammad-Ali; Moaiedmohseni, Sakine; Azizi, Fereidoun; Panahi, Yunes; Mostafaie, Ali; Ghasemi, Hassan; Shams, Jalaleddin; Pourfarzam, Shahryar; Jalali-Nadoushan, Mohammad-Reza; Fallahi, Faramarz; Ebtekar, Massoumeh; Davoudi, Seyyed-Masoud; Ghazanfari, Zeinab; Ardestani, Sussan K; Shariat-Panahi, Shamsa; Moin, Athar; Rezaei, Abbas; Kariminia, Amina; Ajdary, Soheila; Mahmoudi, Mahmoud; Roshan, Rasoul; Ghaderi, Sulayman; Babai, Mahmoud; Naghizadeh, Mohammad-Mehdi; Ghanei, Mohammad-Mostafa

2009-01-01

Insights into long-term clinical consequences of sulfur mustard have emerged from some investigations but less is known about the basic and molecular mechanisms of these complications. Sardasht-Iran Cohort Study is a comprehensive historical cohort study on Sardasht chemical victims' population which was designed to find out the long-term complications of sulfur mustard exposure and the basic mechanisms underlying clinical manifestations. This paper describes the design and methodology of Sardasht-Iran Cohort Study. In Sardasht-Iran Cohort Study, 500 individuals including 372 subjects from Sardasht, as the exposed group, and 128 subjects from Rabat, as the unexposed age-matched control group were evaluated. The exposed group was divided into two groups based on the severity of clinical complications at the time of exposure. Different samples including blood, sputum, saliva, tear, urine, and semen were collected for immunologic, hematologic, biochemical, and other laboratory analysis. Data were gathered from medical records, clinical examinations, laboratory tests, and questionnaires for psychological and lifestyle situations. The important distinctions setting this study apart from the previous ones are discussed. The Sardasht-Iran Cohort Study provides important information on various aspects of long-term consequences of sulfur mustard exposure. This database will provide a better position to suggest guidelines for the diagnosis, treatment, and prevention of delayed complications in the patients exposed to sulfur mustard.

Reaction of (carbonylimido)sulfur(IV) derivatives with TAS-fluoride, (Me2N)3S+Me3SiF2-.

PubMed

Lork, E; Viets, D; Mews, R; Oberhammer, H

2000-10-16

In the reaction of TAS-fluoride, (Me2N)3S+Me3SiF2-, with carbonyl sulfur difluoride imides RC(O)NSF2 (R = F, CF3), C-N bond, cleavage is observed, and TAS+RC(O)F2- and NSF are the final products. From TASF and RC(O)NS(CF3)F, the salts TAS+RC(O)NS(CF3)F2- (R = F (14), CF3 (15)), with psi-pentacoordinate sulfur centers in the anions, are formed. An X-ray structure investigation of 14 shows that the fluorine atoms occupy axial positions and CF3, NC(O)F, and the sulfur lone pair occupy equatorial positions of the trigonal bipyramid. The -C(O)F group lies in the equatorial plane with the CO bond synperiplanar to the SN bond. According to B3LYP calculations, this structure corresponds to a global minimum and the expected axial orientation of the -C(O)F group represents a transition state. Calculations for the unstable FC(O)NSF3- anion show a different geometry. The -C(O)F group deviates 40 degrees from axial orientation, and the equatorially bonded fluorine is, in contrast to the -CF3 group in 14, syn positioned.

Variation in Sulfur and Selenium Accumulation Is Controlled by Naturally Occurring Isoforms of the Key Sulfur Assimilation Enzyme ADENOSINE 5′-PHOSPHOSULFATE REDUCTASE2 across the Arabidopsis Species Range1[W][OPEN

PubMed Central

Chao, Dai-Yin; Baraniecka, Patrycja; Danku, John; Koprivova, Anna; Lahner, Brett; Luo, Hongbing; Yakubova, Elena; Dilkes, Brian; Kopriva, Stanislav; Salt, David E.

2014-01-01

Natural variation allows the investigation of both the fundamental functions of genes and their role in local adaptation. As one of the essential macronutrients, sulfur is vital for plant growth and development and also for crop yield and quality. Selenium and sulfur are assimilated by the same process, and although plants do not require selenium, plant-based selenium is an important source of this essential element for animals. Here, we report the use of linkage mapping in synthetic F2 populations and complementation to investigate the genetic architecture of variation in total leaf sulfur and selenium concentrations in a diverse set of Arabidopsis (Arabidopsis thaliana) accessions. We identify in accessions collected from Sweden and the Czech Republic two variants of the enzyme ADENOSINE 5′-PHOSPHOSULFATE REDUCTASE2 (APR2) with strongly diminished catalytic capacity. APR2 is a key enzyme in both sulfate and selenate reduction, and its reduced activity in the loss-of-function allele apr2-1 and the two Arabidopsis accessions Hodonín and Shahdara leads to a lowering of sulfur flux from sulfate into the reduced sulfur compounds, cysteine and glutathione, and into proteins, concomitant with an increase in the accumulation of sulfate in leaves. We conclude from our observation, and the previously identified weak allele of APR2 from the Shahdara accession collected in Tadjikistan, that the catalytic capacity of APR2 varies by 4 orders of magnitude across the Arabidopsis species range, driving significant differences in sulfur and selenium metabolism. The selective benefit, if any, of this large variation remains to be explored. PMID:25245030

Long-term effects of sulfur mustard on civilians' mental health 20 years after exposure (The Sardasht-Iran Cohort Study).

PubMed

Roshan, Rasoul; Rahnama, Parvin; Ghazanfari, Zeinab; Montazeri, Ali; Soroush, Mohammad Reza; Naghizadeh, Mohammad Mehdi; Melyani, Mahdiyeh; Tavoli, Azadeh; Ghazanfari, Tooba

2013-04-24

Sulfur mustard (SM) is an alkylating agent that induces short and long term toxicity on various organs. The aim of this study was to assess the long-term psychological symptoms among samples of exposed to sulfur mustard gas compared with unexposed civilians 20 years after exposure. This historical cohort study was conducted on 495 civilians of Sardasht and Rabat in two age matched groups, including 367 sulfur mustard exposed participants from Sardasht and 128 unexposed subjects from Rabat. Psychological symptoms was assessed using the Symptom Check List-90 Revised (SCL-90-R) including measures of somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism providing three global distress indices namely: Global Severity Index (GSI), Positive Symptom Total (PST) and Positive Symptom Distress Index (PSDI). Comparison was made between exposed and unexposed civilians. There were significant differences in somatization (P = 0.002), obsessive-compulsive (P = 0.031), depression (P = 0.007), anxiety (P = 0.042), and hostility (P = 0.002), between the exposed and unexposed groups. In addition there were significant differences between two groups concerning the GSI (P = 0.045) and the PSDI (P < 0.001). The differences between two groups in other subscales were not significant. The findings from this study showed that civilians who exposed to sulfur mustard gas were suffering from a number of psychological symptoms even 20 years after exposure. Providing mental health services and more resource allocation for this community are highly recommended.

Sulfur Speciation in Peat: a Time-zero Signature for the " Spruce and Peatland Responses Under Climate and Environmental Change" Experiment

NASA Astrophysics Data System (ADS)

Furman, O.; Toner, B. M.; Sebestyen, S. D.; Kolka, R. K.; Nater, E. A.

2014-12-01

As part of the "Spruce and Peatland Responses Under Climate and Environmental Change" (SPRUCE) experiment, we made initial measurements of sulfur speciation in peat. These observations represent a "time-zero" relative to the intended soil warming experiment which begins in 2015. Total sulfur and sulfur speciation were measured in peat cores (solid phase) from nine plots (hollows and hummocks) to a depth of 2 m. Peat samples were packed under nitrogen and frozen in the field immediately after collection. All subsequent sample storage, handling, and processing were conducted under inert gas. Sulfur speciation was measured using bulk sulfur 1s X-ray absorption near edge structure (XANES) spectroscopy at the SXRMB instrument at the Canadian Light Source, Saskatoon, SK, Canada and at the 9-BM instrument, Advanced Photon Source, Argonne National Laboratory, IL, USA. Total sulfur concentrations ranged from 968 to 4077 mg sulfur / kg dry peat. Sulfur content increased with depth from 2 g sulfur / m2 in the 0-10 cm increment to a maximum value of 38 g sulfur / m2 in the 50-60 cm increment. These sulfur loadings produced high quality XANES spectra. The nine cores exhibited reproducible trends with depth in both total sulfur and specific sulfur species; however, variability in sulfur speciation was greatest in the top 40 cm. All sulfur detected within the peat solids was in an organic form. The most abundant sulfur species group was composed of organic mono-sulfide and thiol forms, representing approximately half of the total sulfur at all depths. Sulfonate and ester-sulfate species were 10-15 mol% of sulfur and exhibited low variability with depth. A subsurface maximum in organic di-sulfide was observed in the 20-30 cm depth increment, which is the transition zone between transiently oxidized acrotelm and permanently saturated anaerobic catotelm. Quantification of major sulfur pools is important for the SPRUCE experiment as they are likely to be indicators of changes in the oxidation-reduction (redox) status, and mercury methylation potential, of the peat in response to warming and enhanced carbon dioxide.

Genome-Wide Transcriptional Profiling of the Purple Sulfur Bacterium Allochromatium vinosum DSM 180T during Growth on Different Reduced Sulfur Compounds

PubMed Central

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

2013-01-01

The purple sulfur bacterium Allochromatium vinosum DSM 180T 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

Volatile Organic Sulfur Compounds of Environmental Interest: Dimethyl Sulfide and Methanethiol

ERIC Educational Resources Information Center

Chasteen, Thomas G.; Bentley, Ronald

2004-01-01

Volatile organic sulfur compounds (VOSCs) have been assigned environmental roles in global warming, acid precipitation, and cloud formation where two important members dimethyl sulfide (CH3)2 S, DMS, and methanethiol, CH3SH, MT, of VOSC group are involved.

Trace sulfate in mid-Proterozoic carbonates and the sulfur isotope record of biospheric evolution

NASA Astrophysics Data System (ADS)

Gellatly, Anne M.; Lyons, Timothy W.

2005-08-01

Concentrations of oceanic and atmospheric oxygen have varied over geologic time as a function of sulfur and carbon cycling at or near the Earth's surface. This balance is expressed in the sulfur isotope composition of seawater sulfate. Given the near absence of gypsum in pre-Phanerozoic sediments, trace amounts of carbonate-associated sulfate (CAS) within limestones or dolostones provide the best available constraints on the isotopic composition of sulfate in Precambrian seawater. Although absolute CAS concentrations, which range from those below detection to ˜120 ppm sulfate in this study, may be compromised by diagenesis, the sulfur isotope compositions can be buffered sufficiently to retain primary values. Stratigraphically controlled δ 34S measurements for CAS from three mid-Proterozoic carbonate successions (˜1.2 Ga Mescal Limestone, Apache Group, Arizona, USA; ˜1.45-1.47 Ga Helena and Newland formations, Belt Supergroup, Montana, USA; and ˜1.65 Ga Paradise Creek Formation, McNamara Group, NW Queensland, Australia) show large isotopic variability (+9.1‰ to +18.9‰, -1.1‰ to +27.3‰, and +14.1‰ to +37.3‰, respectively) over stratigraphic intervals of ˜50 to 450 m. This rapid variability, ranging from scattered to highly systematic, and overall low CAS abundances can be linked to sulfate concentrations in the mid-Proterozoic ocean that were substantially lower than those of the Phanerozoic but higher than values inferred for the Archean. Results from the Belt Supergroup specifically corroborate previous arguments for seawater contributions to the basin. Limited sulfate availability that tracks the oxygenation history of the early atmosphere is also consistent with the possibility of extensive deep-ocean sulfate reduction, the scarcity of bedded gypsum, and the stratigraphic δ 34S trends and 34S enrichments commonly observed for iron sulfides of mid-Proterozoic age.

3D Nitrogen, Sulfur-Codoped Carbon Nanomaterial-Supported Cobalt Oxides with Polyhedron-Like Particles Grafted onto Graphene Layers as Highly Active Bicatalysts for Oxygen-Evolving Reactions.

PubMed

Huang, Xiaobo; Wang, Jianqiang; Bao, Hongliang; Zhang, Xiangkun; Huang, Yongmin

2018-02-28

The extensive research and developments of highly efficient oxygen electrode electrocatalysts to get rid of the kinetic barriers for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are very important in energy conversion and storage devices. Especially, exploring nonprecious metal alternatives to replace traditional noble metal catalysts with high cost and poor durability is the paramount mission. In this paper, we utilize property-flexible ZIF-67 and sulfur-functionalized graphene oxide to obtain a cobalt, nitrogen, and sulfur codoped nanomaterial with 3D hierarchical porous structures, owing to their rich dopant species and good conductivity. The crosslinked structures of polyhedron particles throughout the whole carbon framework speeds up the mass transportation and charge-delivery processes during oxygen-evolving reactions. Also, by exploring the location and coordination type of sulfur dopants, we emphasize the effects of sulfone and sulfide functional groups anchored into the graphitic structure on enhancing the catalytic abilities for ORR and OER. To note, compared to the noble metal electrocatalysts, the best-performing CoO@Co 3 O 4 /NSG-650 (0.79 V) is 40 mV less active than the commercial Pt/C catalyst (0.83 V) for ORR and merely 10 mV behind IrO 2 (1.68 V) for OER. Besides, the metric between ORR and OER difference for CoO@Co 3 O 4 /NSG-650 to evaluate its overall electrocatalytic activity is 0.90 V, surpassing 290 and 430 mV over Pt/C (1.19 V) and IrO 2 (1.33 V). Comprehensively, the as-prepared CoO@Co 3 O 4 /NSG-650 indicates excellent bifunctional catalytic activities for ORR and OER, which shows great potential for replacing noble metal catalysts in the application of fuel cells and metal-air batteries.

Synthesis and Late-Stage Functionalization of Complex Molecules through C–H Fluorination and Nucleophilic Aromatic Substitution

PubMed Central

2015-01-01

We report the late-stage functionalization of multisubstituted pyridines and diazines at the position α to nitrogen. By this process, a series of functional groups and substituents bound to the ring through nitrogen, oxygen, sulfur, or carbon are installed. This functionalization is accomplished by a combination of fluorination and nucleophilic aromatic substitution of the installed fluoride. A diverse array of functionalities can be installed because of the mild reaction conditions revealed for nucleophilic aromatic substitutions (SNAr) of the 2-fluoroheteroarenes. An evaluation of the rates for substitution versus the rates for competitive processes provides a framework for planning this functionalization sequence. This process is illustrated by the modification of a series of medicinally important compounds, as well as the increase in efficiency of synthesis of several existing pharmaceuticals. PMID:24918484

Density functional theory study for the enhanced sulfur tolerance of Ni catalysts by surface alloying

NASA Astrophysics Data System (ADS)

Hwang, Bohyun; Kwon, Hyunguk; Ko, Jeonghyun; Kim, Byung-Kook; Han, Jeong Woo

2018-01-01

Sulfur compounds in fuels deactivate the surface of anode materials in solid oxide fuel cells (SOFCs), which adversely affect the long-term durability. To solve this issue, it is important to design new SOFC anode materials with high sulfur tolerance. Unfortunately, it is difficult to completely replace the traditional Ni anode owing to its outstanding reactivity with low cost. As an alternative, alloying Ni with transition metals is a practical strategy to enhance the sulfur resistance while taking advantage of Ni metal. Therefore, in this study, we examined the effects of transition metal (Cu, Rh, Pd, Ag, Pt, and Au) doping into a Ni catalyst on not only the adsorption of H2S, HS, S, and H but also H2S decomposition using density functional theory (DFT) calculations. The dopant metals were selected rationally by considering the stability of the Ni-based binary alloys. The interactions between sulfur atoms produced by H2S dissociation and the surface are weakened by the dopant metals at the topmost layer. In addition, the findings show that H2S dissociation can be suppressed by doping transition metals. It turns out that these effects are maximized in the Au-doped Ni catalyst. Our DFT results will provide useful insights into the design of sulfur-tolerant SOFC anode materials.

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

PubMed

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

2016-07-01

Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of l-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate, the sulfhydryl group from l-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light-limiting conditions. Characterization of a double mutant produced from Arabidopsis thaliana T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence. © 2016 Scandinavian Plant Physiology Society.

Quadruple sulfur isotope constraints on the origin and cycling of volatile organic sulfur compounds in a stratified sulfidic lake

NASA Astrophysics Data System (ADS)

Oduro, Harry; Kamyshny, Alexey; Zerkle, Aubrey L.; Li, Yue; Farquhar, James

2013-11-01

We have quantified the major forms of volatile organic sulfur compounds (VOSCs) distributed in the water column of stratified freshwater Fayetteville Green Lake (FGL), to evaluate the biogeochemical pathways involved in their production. The lake's anoxic deep waters contain high concentrations of sulfate (12-16 mmol L-1) and sulfide (0.12 μmol L-1 to 1.5 mmol L-1) with relatively low VOSC concentrations, ranging from 0.1 nmol L-1 to 2.8 μmol L-1. Sulfur isotope measurements of combined volatile organic sulfur compounds demonstrate that VOSC species are formed primarily from reduced sulfur (H2S/HS-) and zero-valent sulfur (ZVS), with little input from sulfate. Thedata support a role of a combination of biological and abiotic processes in formation of carbon-sulfur bonds between reactive sulfur species and methyl groups of lignin components. These processes are responsible for very fast turnover of VOSC species, maintaining their low levels in FGL. No dimethylsulfoniopropionate (DMSP) was detected by Electrospray Ionization Mass Spectrometry (ESI-MS) in the lake water column or in planktonic extracts. These observations indicate a pathway distinct from oceanic and coastal marine environments, where dimethylsulfide (DMS) and other VOSC species are principally produced via the breakdown of DMSP by plankton species.

Towards Next Generation Lithium-Sulfur Batteries: Non-Conventional Carbon Compartments/Sulfur Electrodes and Multi-Scale Analysis

DOE PAGES

Dysart, Arthur D.; Burgos, Juan C.; Mistry, Aashutosh; ...

2016-02-09

In this work, a novel heterofunctional, bimodal-porous carbon morphology, termed the carbon compartment (CC), is utilized as a sulfur host as a lithium-sulfur battery cathode. A multi-scale model explores the physics and chemistry of the lithium-sulfur battery cathode. The CCs are synthesized by a rapid, low cost process to improve electrode-electrolyte interfacial contact and accommodate volumetric expansion associated with sulfide formation. The CCs demonstrate high sulfur loading (47 %-wt. S) and ca. 700 mAh g -1 reversible capacity with high coulombic efficiency due to their unique structures. Density functional theory and ab initio Molecular Dynamics characterize the interface between themore » C/S composite and electrolyte during the sulfur reduction mechanism. Stochastic realizations of 3D electrode microstructures are reconstructed based on representative SEM images to study the influence of solid sulfur loading and lithium sulfide precipitation on microstructural and electrochemical properties. A macroscale electrochemical performance model is developed to analyze the performance of lithium-sulfur batteries. The combined multi-scale simulation studies explain key fundamentals of sulfur reduction and its relation to the polysulfide shuttle mechanism: how the process is affected due to the presence of carbon substrate, thermodynamics of lithium sulfide formation and deposition on carbon, and microstructural effects on the overall cell performance.« less

The Ancient Wood of the Acqualadrone Rostrum: A Materials History Through GC-MS and Sulfur X-ray Absorption Spectroscopy

PubMed Central

Frank, Patrick; Caruso, Francesco; Caponetti, Eugenio

2012-01-01

In 2008 the rostrum from an ancient warship was recovered from the Mediterranean near Acqualadrone, Sicily. To establish its provenance and condition, samples of black and brown rostrum wood were examined using sulfur K-edge x-ray absorption spectroscopy (XAS) and GC-MS. GC-MS of pyrolytic volatiles yielded only guaiacyl derivatives, indicating construction from pinewood. A derivatized extract of black wood yielded forms of abietic acid and sandaracopimaric acid consistent with pine pitch waterproofing. Numerical fits to the sulfur K-edge XAS spectra showed that about 65% of the endogenous sulfur consisted of thiols and disulfides. Elemental sulfur was about 2% and 7% in black and brown wood, respectively, while pyritic sulfur was about 12% and 6%. About 2% of the sulfur in both wood types was modeled as trimethylsulfonium, possibly reflecting biogenic dimethylsulfonio-propionate. High valent sulfur was exclusively represented by sulfate esters, consistent with bacterial sulfotransferase activity. Traces of chloride were detected, but no free sulfate ion. In summary, the rostrum was manufactured of pine wood and subsequently waterproofed with pine pitch. The subsequent 2300 years included battle, foundering, and marine burial followed by anoxia, bacterial colonization, sulfate reduction, and mobilization of transition metals, which produced pyrite and copious appended sulfur functionality. PMID:22545724

A sulfur segregation study of PWA 1480, NiCrAl, and NiAl alloys

NASA Technical Reports Server (NTRS)

Jayne, D. T.; Smialek, J. L.

1993-01-01

Some nickel based superalloys show reduced oxidation resistance from the lack of an adherent oxide layer during high temperature cyclic oxidation. The segregation of sulfur to the oxide-metal interface is believed to effect oxide adhesion, since low sulfur alloys exhibit enhanced adhesion. X ray Photoelectron Spectroscopy (XPS) was combined with an in situ sample heater to measure sulfur segregation in NiCrAl, PWA 1480, and NiAl alloys. The polished samples with a 1.5 to 2.5 nm (native) oxide were heated from 650 to 1100 C with hold times up to 6 hr. The sulfur concentration was plotted as a function of temperature versus time at temperature. One NiCrAl sulfur study was performed on the same casting used by Browning to establish a base line between previous Auger Electron Spectroscopy (AES) results and the XPS results of this study. Sulfur surface segregation was similar for PWA 1480 and NiCrAl and reached a maximum of 30 at% at 800 to 850 C. Above 900 C the sulfur surface concentration decreased to about 3 at% at 1100 C. These results are contrasted to the minimal segregation observed for low sulfur hydrogen annealed materials which exhibit improved scale adhesion.

Structural Dependence of the Sulfur Reduction Mechanism in Carbon-Based Cathodes for Lithium–Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burgos, Juan C.; Balbuena, Perla B.; Montoya, Javier A.

We report lithium-sulfur batteries are promising non-conventional sources of energy due to their high theoretical capacity and energy density. However, the successful implementation of this technology has been hindered due to the low cycling life of the battery, caused by long chain polysulfide shuttling between electrodes during charge/discharge, among other issues. Quantum chemical calculations are used to study the reactivity of sulfur in the porous cathode of lithium-sulfur batteries, and the retention capabilities of porous carbon materials to avoid long chain polysulfide diffusion. Ab initio molecular dynamics (AIMD) simulations are initially employed to evaluate sulfur reduction mechanisms and kinetics, andmore » to identify main reduction products. A porous cathode architecture is modeled through parallel graphene layers with elemental sulfur rings in the interlayer, and filled with 1,3-dioxolane (DOL) organic solvent and lithium ions. AIMD simulations showed fast reduction of elemental sulfur and formation of short chain polysulfide. Furthermore, the effect of dangling carbon bonds of graphene on the reactivity of the cathode was confirmed. Adsorption calculations through density functional theory (DFT) proved the capacity of small pores to retain long polysulfide chains. An analysis of the effect of the specific current on the chemical behavior of sulfur reveals an influence of current on the amount of sulfur utilization and practical specific capacity of the battery. In conclusion, this work illustrates the physical-chemical behavior of the sulfur/polysulfide in the porous cathode system at atomistic level.« less

Structural Dependence of the Sulfur Reduction Mechanism in Carbon-Based Cathodes for Lithium–Sulfur Batteries

DOE PAGES

Burgos, Juan C.; Balbuena, Perla B.; Montoya, Javier A.

2017-08-17

We report lithium-sulfur batteries are promising non-conventional sources of energy due to their high theoretical capacity and energy density. However, the successful implementation of this technology has been hindered due to the low cycling life of the battery, caused by long chain polysulfide shuttling between electrodes during charge/discharge, among other issues. Quantum chemical calculations are used to study the reactivity of sulfur in the porous cathode of lithium-sulfur batteries, and the retention capabilities of porous carbon materials to avoid long chain polysulfide diffusion. Ab initio molecular dynamics (AIMD) simulations are initially employed to evaluate sulfur reduction mechanisms and kinetics, andmore » to identify main reduction products. A porous cathode architecture is modeled through parallel graphene layers with elemental sulfur rings in the interlayer, and filled with 1,3-dioxolane (DOL) organic solvent and lithium ions. AIMD simulations showed fast reduction of elemental sulfur and formation of short chain polysulfide. Furthermore, the effect of dangling carbon bonds of graphene on the reactivity of the cathode was confirmed. Adsorption calculations through density functional theory (DFT) proved the capacity of small pores to retain long polysulfide chains. An analysis of the effect of the specific current on the chemical behavior of sulfur reveals an influence of current on the amount of sulfur utilization and practical specific capacity of the battery. In conclusion, this work illustrates the physical-chemical behavior of the sulfur/polysulfide in the porous cathode system at atomistic level.« less

Novel Functions of an Iron-Sulfur Flavoprotein from Trichomonas vaginalis Hydrogenosomes

PubMed Central

Smutná, Tamara; Pilarová, Katerina; Tarábek, Ján; Tachezy, Jan

2014-01-01

Iron-sulfur flavoproteins (Isf) are flavin mononucleotide (FMN)- and FeS cluster-containing proteins commonly encountered in anaerobic prokaryotes. However, with the exception of Isf from Methanosarcina thermophila, which participates in oxidative stress management by removing oxygen and hydrogen peroxide, none of these proteins has been characterized in terms of function. Trichomonas vaginalis, a sexually transmitted eukaryotic parasite of humans, was found to express several iron-sulfur flavoprotein (TvIsf) homologs in its hydrogenosomes. We show here that in addition to having oxygen-reducing activity, the recombinant TvIsf also functions as a detoxifying reductase of metronidazole and chloramphenicol, both of which are antibiotics effective against a variety of anaerobic microbes. TvIsf can utilize both NADH and reduced ferredoxin as electron donors. Given the prevalence of Isf in anaerobic prokaryotes, we propose that these proteins are central to a novel defense mechanism against xenobiotics. PMID:24663020

A Systematic Presentation of Organic Phosphorus and Sulfur Compounds.

ERIC Educational Resources Information Center

Hendrickson, James B.

1985-01-01

Because the names, interrelations, and oxidation levels of the organic compounds of phosphorus and sulfur tend to confuse students, a simple way to organize these compounds has been developed. The system consists of grouping them by oxidation state and extent of carbon substitution. (JN)

Sulfur status in long distance runners

NASA Astrophysics Data System (ADS)

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.

Appearance of Membrane-bound Iron-Sulfur Centers and the Photosystem I Reaction Center during Greening of Barley Leaves 1

PubMed Central

Baltimore, Barbara G.; Malkin, Richard

1977-01-01

Dark-grown barley (Hordeum vulgare) etioplasts were examined for their content of membrane-bound iron-sulfur centers by electron paramagnetic resonance spectroscopy at 15K. They were found to contain the high potential iron-sulfur center characterized (in the reduced state) by an electron paramagnetic resonance g value of 1.89 (the “Rieske” center) but did not contain any low potential iron-sulfur centers. Per mole of cytochrome f, dark-grown etioplasts and fully developed chloroplasts had the same content of the Rieske center. During greening of etioplasts under continuous light, low potential bound iron-sulfur centers appear. In addition, the photosystem I reaction center, as measured by the photooxidation of P700 at 15K, also became functional; during greening the appearance of a photoreducible low potential iron-sulfur center paralleled the appearance of P700 photoactivity. These findings indicate the close association of the low potential iron-sulfur centers with the photosystem I reaction center; they also support the concept that the development of stable charge separation in the photosystem I reaction center requires, in addition to P700, a low potential iron-sulfur center. PMID:16660048

Effect of Sulfuric Acid on the Uptake of Sulfur Dioxide on Soot

NASA Astrophysics Data System (ADS)

Slowik, J. G.; Koehler, B. G.

2001-05-01

The uptake of SO2 on soot may lead to the formation of sulfuric acid on the soot. The sulfuric acid then can affect the further uptake of SO2 on the soot. We are interested in the effect of submonolayer H2SO4 on the uptake of SO2. We measured the uptake of SO2 on n-hexane soot as a function SO2 pressure (10-7 to 10-4 Torr) and sulfuric acid coverage between -140\\deg and -120\\deg C. We generate sulfuric acid by adsorbing varying amounts of SO3 on soot, covering the SO3 with a thick layer of condensed H2O, and heating to 193 K to react the SO3 and H2O and to remove the excess H2O. The sulfuric acid coverage is in the range of monolayer or sub-monolayer. Adsorption of SO2 on soot with and without the sulfuric acid shows that the acid reduces the SO2 uptake by a factor of two or more. Varying the amount of acid has little effect on uptake. However, increasing the thickness of the soot substrate causes a significant increase in SO2 uptake.

Effect of lubricant extreme-pressure additives on surface fatigue life of AISI 9310 spur gears

NASA Technical Reports Server (NTRS)

Scibbe, H. W.; Townsend, D. P.; Aron, P. R.

1984-01-01

Surface fatigue tests were conducted with AISI 9310 spur gears using a formulated synthetic tetraester oil (conforming to MIL-L-23699 specifications) as the lubricant containing either sulfur or phosphorus as the EP additive. Four groups of gears were tested. One group of gears tested without an additive in the lubricant acted as the reference oil. In the other three groups either a 0.1 wt % sulfur or phosphorus additive was added to the tetraester oil to enhance gear surface fatigue life. Test conditions included a gear temperature of 334 K (160 F), a maximum Hertz stress of 1.71 GPa (248 000 psi), and a speed of 10,000 rpm. The gears tested with a 0.1 wt % phosphorus additive showed pitting fatigue life 2.6 times the life of gears tested with the reference tetraester based oil. Although fatigue lives of two groups of gears tested with the sulfur additive in the oil showed improvement over the control group gear life, the results, unlike those obtained with the phosphorus oil, were not considered to be statistically significant.

Density functional theory calculations for armchair stanene nanoribbons with fluorine and sulfur functionalization

NASA Astrophysics Data System (ADS)

Zhang, J.; Lang, X. Y.; Jiang, Q.

2018-07-01

A systematic density functional theory calculation has been carried out to study the effect of edge terminating of F and S elements with different edge natures on the structure and electronic properties of armchair stanene nanoribbons (ASnNRs). Moreover, the corresponding size (ribbon width Na) dependence on these properties is also considered. The energy gap was found to be oscillated as a function of Na and could be classified into three distinct groups of 3m, 3m + 1 and 3m + 2. In addition, the energy gaps of ASnNRs saturated by S atoms differ from that did by F and H atoms in vibration trends as well VBM and CBM changes, where the energy gap is a direct energy gap with a moderate size.

The sulfur budget of the troposphere

NASA Technical Reports Server (NTRS)

Tiwari, S. N.; Augustsson, T. R.

1981-01-01

A one dimensional photochemical tropospheric model was used to calculate the vertical profiles of tropospheric species. Particular attention is focused on the recent inclusion of the chemistry of the sulfur group, which consists of 13 species involving a total of 45 chemical reactions. It is found that the chemistry of the sulfur species, because it is largely anthropogenic, plays an increasingly important role in the distribution of tropospheric gases. The calculated vertical profiles were compared to available measurements and generally found to be in good agreement.

Complexation of cadmium to sulfur and oxygen functional groups in an organic soil

NASA Astrophysics Data System (ADS)

Karlsson, Torbjörn; Elgh-Dalgren, Kristin; Björn, Erik; Skyllberg, Ulf

2007-02-01

Cadmium (Cd) is a toxic trace element and due to human activities soils and waters are contaminated by Cd both on a local and global scale. It is widely accepted that chemical interactions with functional groups of natural organic matter (NOM) is vital for the bioavailability and mobility of trace elements. In this study the binding strength of cadmium (Cd) to soil organic matter (SOM) was determined in an organic (49% organic C) soil as a function of reaction time, pH and Cd concentration. In experiments conducted at native Cd concentrations in soil (0.23 μg g -1 dry soil), halides (Cl, Br) were used as competing ligands to functional groups in SOM. The concentration of Cd in the aqueous phase was determined by isotope-dilution (ID) inductively-coupled-plasma-mass-spectrometry (ICP-MS), and the activity of Cd 2+ was calculated from the well-established Cd-halide constants. At higher Cd loading (500-54,000 μg g -1), the Cd 2+ activity was directly determined by an ion-selective electrode (ISE). On the basis of results from extended X-ray absorption fine structure (EXAFS) spectroscopy, a model with one thiolate group (RS -) was used to describe the complexation (Cd 2+ + RS - ⇆ CdSR +; log KCdSR) at native Cd concentrations. The concentration of thiols (RSH; 0.047 mol kg -1 C) was independently determined by X-ray absorption near-edge structure (XANES) spectroscopy. Log KCdSR values of 11.2-11.6 (p Ka for RSH = 9.96), determined in the pH range 3.1-4.6, compare favorably with stability constants for the association between Cd and well-defined thiolates like glutathione. In the concentration range 500-54,000 μg Cd g -1, a model consisting of one thiolate and one carboxylate (RCOO -) gave the best fit to data, indicating an increasing role for RCOOH groups as RSH groups become saturated. The determined log KCdOOCR of 3.2 (Cd 2+ + RCOO - ⇆ CdOOCR +; log KCdOOCR; p Ka for RCOOH = 4.5) is in accordance with stability constants determined for the association between Cd and well-defined carboxylates. Given a concentration of reduced sulfur groups of 0.2% or higher in NOM, we conclude that the complexation to organic RSH groups may control the speciation of Cd in soils, and most likely also in surface waters, with a total concentration less than 5 mg Cd g -1 organic C.

Effect of sulfur doping on thermoelectric properties of Sodium Tantalate - A first principles study

NASA Astrophysics Data System (ADS)

Chowdary, Bharadwaj; Jayaraman, Kaushik; Molli, Muralikrishna

2018-05-01

In this work, we report the thermoelectric (TE) transport properties of perovskite-like Sodium Tantalate and studied the effect of Sulfur doping on TE properties of Sodium Tantalate. The band structures are calculated in the purview of density functional theory using the mBJ exchange correlation potential. The transport properties are evaluated using the Boltzmann transport theory in the constant relaxation time approximation. Our results suggest that Sulfur doped Sodium Tantalate is better n-type thermoelectric compared to Sodium Tantalate.

The effect of exposure to SO2 on the respiratory system of power-station workers.

PubMed

Froom, P; Sackstein, G; Cohen, C; Lerman, Y; Kristal-Boneh, E; Ribak, J

1998-01-01

Sulfur dioxide (SO2) is generally recognized as a respiratory irritant, but its effects if any at low levels of exposure are uncertain. We studied 38 power station technicians exposed to 0.8 ppm (parts per million) 8-h weighted levels of sulfur dioxide, and compared them to workers performing similar tasks without such exposure. Those exposed complained 5.8 times more frequently of cough (95% CI =1.8-20.6, P < 0.001), and also had significantly more sputum production. There was also a trend for increasing prevalence of dyspnea. On the other hand there was no decrease in pulmonary function test values. In the eight exposed subjects who complained of dyspnea, there was a significant decrease in pulmonary flow values. We conclude that power station workers exposed to low levels of SO2 have increased respiratory symptoms, and deserve compensation if their symptoms become chronic. The pulmonary function tests were not different from the control subjects, but there may be a small group who are prone to long-term morbidity. Additional studies are warranted to confirm our findings, and to define immediate and long-term morbidity due to low exposure to SO2.

Sulfur Doping of InAs

DTIC Science & Technology

2015-06-04

dopant in III-V molecular beam epitaxial (MBE) growth, due to the high vapor pressure. This is a significant concern as high vapor pressure species...results were also observed with co-implantation of gallium with selenium, which sits on the group-V site [10]. Consequently, the sulfur dose was

VARIATION OF ELEMENT SPECIATION IN COAL COMBUSTION AEROSOLS WITH PARTICLE SIZE

EPA Science Inventory

The speciation of sulfur, iron and key trace elements (Cr, As, Se, Zn) in combustion ash aerosols has been examined as a function of size from experimental combustion units burning Utah and Illinois bituminous coals. Although predominantly present as sulfate, sulfur was also pre...

Sulfur amino acids are necessary for normal intestinal mucosal growth in neonatal piglets

USDA-ARS?s Scientific Manuscript database

Sulfur amino acids (SAAs) methionine and cysteine play important metabolic and functional role in human health and disease. Gastrointestinal tract is an important site of transmethylation and transsulfuration of methionine and metabolizes approx. 20% of the dietary methionine intake (Riedijk et al. ...

Frataxin Depletion in Yeast Triggers Up-regulation of Iron Transport Systems before Affecting Iron-Sulfur Enzyme Activities*

PubMed Central

Moreno-Cermeño, Armando; Obis, Èlia; Bellí, Gemma; Cabiscol, Elisa; Ros, Joaquim; Tamarit, Jordi

2010-01-01

The primary function of frataxin, a mitochondrial protein involved in iron homeostasis, remains controversial. Using a yeast model of conditional expression of the frataxin homologue YFH1, we analyzed the primary effects of YFH1 depletion. The main conclusion unambiguously points to the up-regulation of iron transport systems as a primary effect of YFH1 down-regulation. We observed that inactivation of aconitase, an iron-sulfur enzyme, occurs long after the iron uptake system has been activated. Decreased aconitase activity should be considered part of a group of secondary events promoted by iron overloading, which includes decreased superoxide dismutase activity and increased protein carbonyl formation. Impaired manganese uptake, which contributes to superoxide dismutase deficiency, has also been observed in YFH1-deficient cells. This low manganese content can be attributed to the down-regulation of the metal ion transporter Smf2. Low Smf2 levels were not observed in AFT1/YFH1 double mutants, indicating that high iron levels could be responsible for the Smf2 decline. In summary, the results presented here indicate that decreased iron-sulfur enzyme activities in YFH1-deficient cells are the consequence of the oxidative stress conditions suffered by these cells. PMID:20956517

Facile preparation of nitrogen and sulfur co-doped graphene-based aerogel for simultaneous removal of Cd2+ and organic dyes.

PubMed

Kong, Qiaoping; Wei, Chaohai; Preis, Sergei; Hu, Yun; Wang, Feng

2018-05-17

The need in simultaneous removal of heavy metals and organic compounds dictates the development of synthetic adsorbents with tailor-made properties. A nitrogen (N) and sulfur (S) co-doped graphene-based aerogel (GBA) modified with 2,5-dithiobisurea was synthesized hydrothermally for simultaneous adsorption of Cd 2+ and organic dyes-safranin-O (SO), crystal violet (CV), and methylene blue (MB). 2,5-Dithiobisurea was used as nitrogen and sulfur sources to introduce N and S-containing functional group onto graphene oxide. The adsorption mechanism of GBA towards Cd 2+ and organic dyes was studied by Dumwald-Wagner models and the results showed that surface and intraparticle diffusion was the key factor in controlling the rate of adsorption. The maximum adsorption capacities of GBA towards Cd 2+ , SO, CV, and MB comprised 1.755, 0.949, 0.538, and 0.389 mmol/g in monocomponent system, respectively. Adsorption synergism was observed with respect to Cd 2+ in presence of the dyes. The performance of GBA with respect to Cd 2+ removal from binary solutions, Cd 2+ -SO, Cd 2+ -CV, and Cd 2+ -MB, was enhanced by the presence of the dyes significantly, while the adsorption capacities towards the dyes were not affected by the presence of Cd 2+ .

Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chunshan, Song; Kirby, S.; Schmidt, E.

1995-12-31

The objective of this project is to explore bimetallic dispersed catalysts for more efficient coal liquefaction. Coal liquefaction involves cleavage of methylene, dimethylene and ether bridges connecting various aromatic units and the reactions of various oxygen functional groups. This paper describes recent results on (1) hydrodeoxygenation of O-containing polycyclic model compounds using novel organometallic catalyst precursors; and (2) activity and selectivity of dispersed Fe catalysts from organometallic and inorganic precursors for hydrocracking of 4-(1-naphthylmethyl) bibenzyl. The results showed that some iron containing catalysts have higher activity in the sulfur-free form, contrary to conventional wisdom. Adding sulfur to Fe precursors withmore » Cp-ligands decreased the activity of the resulting catalyst. This is in distinct contrast to the cases with iron pentacarbonyl and superfine Fe{sub 2}O{sub 3}, where S addition increased their catalytic activity substantially. A positive correlation between sulfur addition and increased activity can be seen, but a reversed trend between Fe cluster size and hydrocracking conversion could be observed, for carbonyl-type Fe precursors. It is apparent that the activity and selectivity of Fe catalysts for NMBB conversion depends strongly on both the type of ligand environment, the oxidation state and the number of intermetal bonds in the molecular precursor.« less

Two Fe-S clusters catalyse sulfur insertion by Radical-SAM methylthiotransferases

PubMed Central

Forouhar, Farhad; Arragain, Simon; Atta, Mohamed; Gambarelli, Serge; Mouesca, Jean-Marie; Hussain, Munif; Xiao, Rong; Kieffer-Jaquinod, Sylvie; Seetharaman, Jayaraman; Acton, Thomas B.; Montelione, Gaetano T.

2014-01-01

How living organisms create carbon-sulfur bonds during biosynthesis of critical sulphur-containing compounds is still poorly understood. The methylthiotransferases MiaB and RimO catalyze sulfur insertion into tRNAs and ribosomal protein S12, respectively. Both belong to a sub-group of Radical-SAM enzymes that bear two [4Fe-4S] clusters. One cluster binds S-Adenosylmethionine and generates an Ado• radical via a well- established mechanism. However, the precise role of the second cluster is unclear. For some sulfur-inserting Radical-SAM enzymes, this cluster has been proposed to act as a sacrificial source of sulfur for the reaction. In this paper, we report parallel enzymological, spectroscopic and crystallographic investigations of RimO and MiaB, which provide the first evidence that these enzymes are true catalysts and support a new sulfation mechanism involving activation of an exogenous sulfur co-substrate at an exchangeable coordination site on the second cluster, which remains intact during the reaction. PMID:23542644

77 FR 75868 - Regulation of Fuels and Fuel Additives: Modifications to the Transmix Provisions Under the Diesel...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-26

...EPA is amending the requirements under EPA's diesel sulfur program related to the sulfur content of locomotive and marine (LM) diesel fuel produced by transmix processors and pipeline facilities. These amendments will reinstate the ability of locomotive and marine diesel fuel produced from transmix by transmix processors and pipeline operators to meet a maximum 500 parts per million (ppm) sulfur standard outside of the Northeast Mid-Atlantic Area and Alaska and expand this ability to within the Northeast Mid-Atlantic Area provided that: the fuel is used in older technology locomotive and marine engines that do not require 15 ppm sulfur diesel fuel, and the fuel is kept segregated from other fuel. These amendments will provide significant regulatory relief for transmix processors and pipeline operators to allow the petroleum distribution system to function efficiently while continuing to transition the market to virtually all ultra-low sulfur diesel fuel (ULSD, i.e. 15 ppm sulfur diesel fuel) and the environmental benefits it provides.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pascal, Tod A.; Villaluenga, Irune; Wujcik, Kevin H.

Impregnation of porous carbon matrices with liquid sulfur has been exploited to fabricate composite cathodes for lithium-sulfur batteries, aimed at confining soluble sulfur species near conducting carbon to prevent both loss of active material into the electrolyte and parasitic reactions at the lithium metal anode. Here, through extensive computer simulations, we uncover the strongly favorable interfacial free energy between liquid sulfur and graphitic surfaces that underlies this phenomenon. Previously unexplored curvature-dependent enhancements are shown to favor the filling of smaller pores first and effect a quasi-liquid sulfur phase in microporous domains (diameters <2 nm) that persists ~30° below the expectedmore » freezing point. Evidence of interfacial sulfur on carbon is shown to be a 0.3 eV red shift in the simulated and measured interfacial X-ray absorption spectra. Our results elucidate the critical morphology and thermodynamic properties necessary for future cathode design and highlight the importance of molecular-scale details in defining emergent properties of functional nanoscale interfaces.« less

First-principles studies of the v7×v7R19.1° structure of sulfur on the Pd(1 1 1) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alfonso, D.R.

2007-11-01

Density functional theory is used to investigate the v7×v7R19.1° structure of sulfur on the Pd(111) surface. Among the different models that were considered, the densely packed mixed sulfur-metal overlayer structure proposed by Liu et al. [W. Liu, K.A.R. Mitchell, W. Berndt, Surf. Sci. 393 (1997) L119] was found to be the most energetically favorable. This model consists of arrangement of Pd triangles and pentagons on top of Pd(111) with the sulfur atoms at 3/7 monolayer coverage. The dominant mechanism for sulfur interaction with Pd in the overlayer region is the rehybridization of sulfur 3p and metal 4d bands. Simulated scanningmore » tunneling microscopy image for this structure shows some similarity with that obtained from experiment. Our study confirms that surface sulfide with no structural resemblance to its bulk counterparts can form on Pd(111).« less

High resistance to sulfur poisoning of Ni with copper skin under electric field

NASA Astrophysics Data System (ADS)

Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

2017-02-01

The effects of sulfur poisoning on the (1 0 0), (1 1 0) and (1 1 1) surfaces of pure Ni and Cu/Ni alloy are studied in consideration of the effect of electric field. The effects of Cu dopants on the S poisoning characteristics are analyzed by the means of the density functional theory results in combination with thermodynamics data using the ab initio atomistic thermodynamic method. When the Cu concentration increases to 50% on the surface layer of the Cu/Ni alloy, the (1 1 0) surface becomes the most vulnerable to the sulfur poisoning. Ni with a copper skin can mostly decrease the sulfur poisoning effect. Especially under the electric field of 1.0 V/Å, the sulfur adsorption and phase transition temperature can be further reduced. We therefore propose that Ni surfaces with copper skin can be very effective to improve the resistance to sulfur poisoning of the Ni anode under high electric field.

Electronic structure of transition metal-cysteine complexes from X-ray absorption spectroscopy.

PubMed

Leung, Bonnie O; Jalilehvand, Farideh; Szilagyi, Robert K

2008-04-17

The electronic structures of HgII, NiII, CrIII, and MoV complexes with cysteine were investigated by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and density functional theory. The covalency in the metal-sulfur bond was determined by analyzing the intensities of the electric-dipole allowed pre-edge features appearing in the XANES spectra below the ionization threshold. Because of the well-defined structures of the selected cysteine complexes, the current work provides a reference set for further sulfur K-edge XAS studies of bioinorganic active sites with transition metal-sulfur bonds from cysteine residues as well as more complex coordination compounds with thiolate ligands.

Adsorption and diffusion of atomic oxygen and sulfur at pristine and doped Ni surfaces with implications for stress corrosion cracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexandrov, Vitaly; Sushko, Maria L.; Schreiber, Daniel K.

A density-functional-theory modeling study of atomic oxygen/sulfur adsorption and diffusion at pristine and doped Ni(111) and (110) surfaces is presented. We find that oxygen and sulfur feature comparable adsorption energies over the same surface sites, however, the surface diffusion of sulfur is characterized by an activation barrier about one half that of oxygen. Calculations with different alloying elements at Ni surfaces show that Cr strongly enhances surface binding of both species in comparison to Al. These results in combination with previous modeling studies help explain the observed differences in selective grain boundary oxidation mechanisms of Ni-Cr and Ni-Al alloys.

Effect of Sulfuric and Triflic Acids on the Hydration of Vanadium Cations: An ab Initio Study.

PubMed

Sepehr, Fatemeh; Paddison, Stephen J

2015-06-04

Vanadium redox flow batteries (VRFBs) may be a promising solution for large-scale energy storage applications, but the crossover of any of the redox active species V(2+), V(3+), VO(2+), and VO2(+) through the ion exchange membrane will result in self-discharge of the battery. Hence, a molecular level understanding of the states of vanadium cations in the highly acidic environment of a VRFB is needed. We examine the effects of sulfuric and triflic (CF3SO3H) acids on the hydration of vanadium species as they mimic the electrolyte and functional group of perfluorosulfonic acid (PFSA) membranes. Hybrid density functional theory in conjunction with a continuum solvation model was utilized to obtain the local structures of the hydrated vanadium cations in proximity to H2SO4, CF3SO3H, and their conjugate anions. The results indicate that none of these species covalently bond to the vanadium cations. The hydration structure of V(3+) is more distorted than that of V(2+) in an acidic medium. The oxo-group of VO2(+) is protonated by either acid, in contrast to VO(2+) which is not protonated. The atomic partial charge of the four oxidation states of vanadium varies from +1.7 to +2.0. These results provide the local solvation structures of vanadium cations in the VRFBs environment that are directly related to the electrolytes stability and diffusion of vanadium ions into the membrane.

Sulfur Dioxide Pollution Monitor.

ERIC Educational Resources Information Center

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…

Sulfur in human nutrition and applications in medicine.

PubMed

Parcell, Stephen

2002-02-01

Because the role of elemental sulfur in human nutrition has not been studied extensively, it is the purpose of this article to emphasize the importance of this element in humans and discuss the therapeutic applications of sulfur compounds in medicine. Sulfur is the sixth most abundant macromineral in breast milk and the third most abundant mineral based on percentage of total body weight. The sulfur-containing amino acids (SAAs) are methionine, cysteine, cystine, homocysteine, homocystine, and taurine. Dietary SAA analysis and protein supplementation may be indicated for vegan athletes, children, or patients with HIV, because of an increased risk for SAA deficiency in these groups. Methylsulfonylmethane (MSM), a volatile component in the sulfur cycle, is another source of sulfur found in the human diet. Increases in serum sulfate may explain some of the therapeutic effects of MSM, DMSO, and glucosamine sulfate. Organic sulfur, as SAAs, can be used to increase synthesis of S-adenosylmethionine (SAMe), glutathione (GSH), taurine, and N-acetylcysteine (NAC). MSM may be effective for the treatment of allergy, pain syndromes, athletic injuries, and bladder disorders. Other sulfur compounds such as SAMe, dimethylsulfoxide (DMSO), taurine, glucosamine or chondroitin sulfate, and reduced glutathione may also have clinical applications in the treatment of a number of conditions such as depression, fibromyalgia, arthritis, interstitial cystitis, athletic injuries, congestive heart failure, diabetes, cancer, and AIDS. Dosages, mechanisms of action, and rationales for use are discussed. The low toxicological profiles of these sulfur compounds, combined with promising therapeutic effects, warrant continued human clinical trails.

Microbial community structure and sulfur biogeochemistry in mildly-acidic sulfidic geothermal springs in Yellowstone National Park.

PubMed

Macur, R E; Jay, Z J; Taylor, W P; Kozubal, M A; Kocar, B D; Inskeep, W P

2013-01-01

Geothermal and hydrothermal waters often contain high concentrations of dissolved sulfide, which reacts with oxygen (abiotically or biotically) to yield elemental sulfur and other sulfur species that may support microbial metabolism. The primary goal of this study was to elucidate predominant biogeochemical processes important in sulfur biogeochemistry by identifying predominant sulfur species and describing microbial community structure within high-temperature, hypoxic, sulfur sediments ranging in pH from 4.2 to 6.1. Detailed analysis of aqueous species and solid phases present in hypoxic sulfur sediments revealed unique habitats containing high concentrations of dissolved sulfide, thiosulfate, and arsenite, as well as rhombohedral and spherical elemental sulfur and/or sulfide phases such as orpiment, stibnite, and pyrite, as well as alunite and quartz. Results from 16S rRNA gene sequencing show that these sediments are dominated by Crenarchaeota of the orders Desulfurococcales and Thermoproteales. Numerous cultivated representatives of these lineages, as well as the Thermoproteales strain (WP30) isolated in this study, require complex sources of carbon and respire elemental sulfur. We describe a new archaeal isolate (strain WP30) belonging to the order Thermoproteales (phylum Crenarchaeota, 98% identity to Pyrobaculum/Thermoproteus spp. 16S rRNA genes), which was obtained from sulfur sediments using in situ geochemical composition to design cultivation medium. This isolate produces sulfide during growth, which further promotes the formation of sulfide phases including orpiment, stibnite, or pyrite, depending on solution conditions. Geochemical, molecular, and physiological data were integrated to suggest primary factors controlling microbial community structure and function in high-temperature sulfur sediments. © 2012 Blackwell Publishing Ltd.

Fossilization of melanosomes via sulfurization.

PubMed

McNamara, Maria E; van Dongen, Bart E; Lockyer, Nick P; Bull, Ian D; Orr, Patrick J

2016-05-01

Fossil melanin granules (melanosomes) are an important resource for inferring the evolutionary history of colour and its functions in animals. The taphonomy of melanin and melanosomes, however, is incompletely understood. In particular, the chemical processes responsible for melanosome preservation have not been investigated. As a result, the origins of sulfur-bearing compounds in fossil melanosomes are difficult to resolve. This has implications for interpretations of original colour in fossils based on potential sulfur-rich phaeomelanosomes. Here we use pyrolysis gas chromatography mass spectrometry (Py-GCMS), fourier transform infrared spectroscopy (FTIR) and time of flight secondary ion mass spectrometry (ToF-SIMS) to assess the mode of preservation of fossil microstructures, confirmed as melanosomes based on the presence of melanin, preserved in frogs from the Late Miocene Libros biota (NE Spain). Our results reveal a high abundance of organosulfur compounds and non-sulfurized fatty acid methyl esters in both the fossil tissues and host sediment; chemical signatures in the fossil tissues are inconsistent with preservation of phaeomelanin. Our results reflect preservation via the diagenetic incorporation of sulfur, i.e. sulfurization (natural vulcanization), and other polymerization processes. Organosulfur compounds and/or elevated concentrations of sulfur have been reported from melanosomes preserved in various invertebrate and vertebrate fossils and depositional settings, suggesting that preservation through sulfurization is likely to be widespread. Future studies of sulfur-rich fossil melanosomes require that the geochemistry of the host sediment is tested for evidence of sulfurization in order to constrain interpretations of potential phaeomelanosomes and thus of original integumentary colour in fossils.

The Effect of Hydrogen Annealing and Sulfur Content on the Oxidation Resistance of PWA 1480

NASA Technical Reports Server (NTRS)

Smialek, James L.

1997-01-01

For many decades the dramatic effect of trace amounts of reactive elements on alumina and chromia scale adhesion has been recognized and widely studied. Although various theories have been used to account for such behavior, the connection between scale adhesion and sulfur segregation was initially reported by Smeggil et al. This study found strong surface segregation of sulfur from very low levels in the bulk which could then be curtailed by the addition of reactive elements. It was assumed that the reactive elements, which are strong sulfide formers, acted by getting sulfur in the bulk thus precluding sulfur segregation and weakening of the oxide-metal bond. Subsequent studies confirmed that adhesion could be produced by reducing the sulfur impurity level, without reactive elements. The understanding of this phenomenon has been applied to modern single crystal superalloys, where the addition of Y, although very effective, is problematic. Also problematic is definition of the level of sulfur that is acceptable and below which no further adhesion benefit is reached. Published works have indicated a broad transition defined by various materials and oxidation tests. The present study describes the oxidation behavior of one superalloy (PWA 1480) as a function of various sulfur contents produced by hydrogen annealing for various temperatures, times, and sample thicknesses. The purpose is to define more precisely a criterion for adhesion based on total sulfur reservoir and segregation potential.

Peatland Acidobacteria with a dissimilatory sulfur metabolism.

PubMed

Hausmann, Bela; Pelikan, Claus; Herbold, Craig W; Köstlbacher, Stephan; Albertsen, Mads; Eichorst, Stephanie A; Glavina Del Rio, Tijana; Huemer, Martin; Nielsen, Per H; Rattei, Thomas; Stingl, Ulrich; Tringe, Susannah G; Trojan, Daniela; Wentrup, Cecilia; Woebken, Dagmar; Pester, Michael; Loy, Alexander

2018-02-23

Sulfur-cycling microorganisms impact organic matter decomposition in wetlands and consequently greenhouse gas emissions from these globally relevant environments. However, their identities and physiological properties are largely unknown. By applying a functional metagenomics approach to an acidic peatland, we recovered draft genomes of seven novel Acidobacteria species with the potential for dissimilatory sulfite (dsrAB, dsrC, dsrD, dsrN, dsrT, dsrMKJOP) or sulfate respiration (sat, aprBA, qmoABC plus dsr genes). Surprisingly, the genomes also encoded DsrL, which so far was only found in sulfur-oxidizing microorganisms. Metatranscriptome analysis demonstrated expression of acidobacterial sulfur-metabolism genes in native peat soil and their upregulation in diverse anoxic microcosms. This indicated an active sulfate respiration pathway, which, however, might also operate in reverse for dissimilatory sulfur oxidation or disproportionation as proposed for the sulfur-oxidizing Desulfurivibrio alkaliphilus. Acidobacteria that only harbored genes for sulfite reduction additionally encoded enzymes that liberate sulfite from organosulfonates, which suggested organic sulfur compounds as complementary energy sources. Further metabolic potentials included polysaccharide hydrolysis and sugar utilization, aerobic respiration, several fermentative capabilities, and hydrogen oxidation. Our findings extend both, the known physiological and genetic properties of Acidobacteria and the known taxonomic diversity of microorganisms with a DsrAB-based sulfur metabolism, and highlight new fundamental niches for facultative anaerobic Acidobacteria in wetlands based on exploitation of inorganic and organic sulfur molecules for energy conservation.

Controllably Designed "Vice-Electrode" Interlayers Harvesting High Performance Lithium Sulfur Batteries.

PubMed

Hao, Youchen; Xiong, Dongbin; Liu, Wen; Fan, Linlin; Li, Dejun; Li, Xifei

2017-11-22

An interlayer has been regarded as a promising mediator to prolong the life span of lithium sulfur batteries because its excellent absorbability to soluble polysulfide efficiently hinders the shuttle effect. Herein, we designed various interlayers and understand the working mechanism of an interlayer for lithium sulfur batteries in detail. It was found that the electrochemical performance of a S electrode for an interlayer located in cathode side is superior to the pristine one without interlayers. Surprisingly, the performance of the S electrode for an interlayer located in anode side is poorer than that of pristine one. For comparison, glass fibers were also studied as a nonconductive interlayer for lithium sulfur batteries. Unlike the two interlayers above, these nonconductive interlayer did displays significant capacity fading because polysulfides were adsorbed onto insulated interlayer. Thus, the nonconductive interlayer function as a "dead zone" upon cycling. Based on our findings, it was for the first time proposed that a controllably optimized interlayer, with electrical conductivity as well as the absorbability of polysulfides, may function as a "vice-electrode" of the anode or cathode upon cycling. Therefore, the cathodic conductive interlayer can enhance lithium sulfur battery performance, and the anodic conductive interlayer may be helpful for the rational design of 3D networks for the protection of lithium metal.

Sulfoquinovose in the biosphere: occurrence, metabolism and functions.

PubMed

Goddard-Borger, Ethan D; Williams, Spencer J

2017-02-20

The sulfonated carbohydrate sulfoquinovose (SQ) is produced in quantities estimated at some 10 billion tonnes annually and is thus a major participant in the global sulfur biocycle. SQ is produced by most photosynthetic organisms and incorporated into the sulfolipid sulfoquinovosyl diacylglycerol (SQDG), as well as within some archaea for incorporation into glycoprotein N-glycans. SQDG is found mainly within the thylakoid membranes of the chloroplast, where it appears to be important for membrane structure and function and for optimal activity of photosynthetic protein complexes. SQDG metabolism within the sulfur cycle involves complex biosynthetic and catabolic processes. SQDG biosynthesis is largely conserved within plants, algae and bacteria. On the other hand, two major sulfoglycolytic pathways have been discovered for SQDG degradation, the sulfo-Embden-Meyerhof-Parnas (sulfo-EMP) and sulfo-Entner-Doudoroff (sulfo-ED) pathways, which mirror the major steps in the glycolytic EMP and ED pathways. Sulfoglycolysis produces C3-sulfonates, which undergo biomineralization to inorganic sulfur species, completing the sulfur cycle. This review discusses the discovery and structural elucidation of SQDG and archaeal N-glycans, the occurrence, distribution, and speciation of SQDG, and metabolic pathways leading to the biosynthesis of SQDG and its catabolism through sulfoglycolytic and biomineralization pathways to inorganic sulfur. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

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

PubMed Central

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

Chain Breakage in the Supercooled Liquid - Liquid Transition and Re-entry of the λ-transition in Sulfur.

PubMed

Zhang, Linji; Ren, Yang; Liu, Xiuru; Han, Fei; Evans-Lutterodt, Kenneth; Wang, Hongyan; He, Yali; Wang, Junlong; Zhao, Yong; Yang, Wenge

2018-03-14

Amorphous sulfur was prepared by rapid compression of liquid sulfur at temperatures above the λ-transition for to preserve the high-temperature liquid structure. We conducted synchrotron high-energy X-ray diffraction and Raman spectroscopy to diagnose the structural evolution of amorphous sulfur from room temperature to post-λ-transition temperature. Discontinuous changes of the first and second peaks in atomic pair-distribution-function, g(r), were observed during the transition from amorphous to liquid sulfur. The average first-neighbor coordination numbers showed an abrupt drop from 1.92 to 1.81. The evolution of the chain length clearly shows that the transition was accompanied by polymeric chains breaking. Furthermore, a re-entry of the λ-transition structure was involved in the heating process. The amorphous sulfur, which inherits the post-λ-transition structure from its parent melts, transformed to the pre-λ-transition liquid structure at around 391 K. Upon further heating, the pre-λ-transition liquid transformed to a post-λ-transition structure through the well-known λ-transition process. This discovery offers a new perspective on amorphous sulfur's structural inheritance from its parent liquid and has implications for understanding the structure, evolution and properties of amorphous sulfur and its liquids.

Sodium sulfur battery flight experiment definition study

NASA Technical Reports Server (NTRS)

Chang, Rebecca R.; Minck, Robert

1989-01-01

Sodium-sulfur batteries were identified as the most likely successor to nickel-hydrogen batteries for space applications. One advantage of the Na/S battery system is that the usable specific energy is two to three times that of nickel-hydrogen batteries. This represents a significant launch cost savings or increased payload mass capabilities. Sodium-sulfur batteries support NASA OAST's proposed Civil Space Technology Initiative goal of a factor of two improvement in spacecraft power system performance, as well as the proposed Spacecraft 2000 initiative. The sodium-sulfur battery operates at between 300 and 400 C, using liquid sodium and sulfur/polysulfide electrodes and solid ceramic electrolyte. The transport of the electrode materials to the surface of the electrolyte is through wicking/capillary forces. These critical transport functions must be demonstrated under actual microgravity conditions before sodium-sulfur batteries can be confidently utilized in space. Ford Aerospace Corporation, under contract to NASA Lewis Research Center, is currently working on the sodium-sulfur battery space flight experiment definition study. The objective is to design the experiment that will demonstrate operation of the sodium-sulfur battery/cell in the space environment with particular emphasis on evaluation of microgravity effects. Experimental payload definitions were completed and preliminary designs of the experiment were defined.

Sulfite-oxido-reductase is involved in the oxidation of sulfite in Desulfocapsa sulfoexigens during disproportionation of thiosulfate and elemental sulfur.

PubMed

Frederiksen, Trine-Maria; Finster, Kai

2003-06-01

The enzymatic pathways of elemental sulfur and thiosulfate disproportionation were investigated using cell-free extract of Desulfocapsa sulfoexigens. Sulfite was observed to be an intermediate in the metabolism of both compounds. Two distinct pathways for the oxidation of sulfite have been identified. One pathway involves APS reductase and ATP sulfurylase and can be described as the reversion of the initial steps of the dissimilatory sulfate reduction pathway. The second pathway is the direct oxidation of sulfite to sulfate by sulfite oxidoreductase. This enzyme has not been reported from sulfate reducers before. Thiosulfate reductase, which cleaves thiosulfate into sulfite and sulfide, was only present in cell-free extract from thiosulfate disproportionating cultures. We propose that this enzyme catalyzes the first step in thiosulfate disproportionation. The initial step in sulfur disproportionation was not identified. Dissimilatory sulfite reductase was present in sulfur and thiosulfate disproportionating cultures. The metabolic function of this enzyme in relation to elemental sulfur or thiosulfate disproportionation was not identified. The presence of the uncouplers HQNO and CCCP in growing cultures had negative effects on both thiosulfate and sulfur disproportionation. CCCP totally inhibited sulfur disproportionation and reduced thiosulfate disproportionation by 80% compared to an unamended control. HQNO reduced thiosulfate disproportionation by 80% and sulfur disproportionation by 90%.

Using X-ray absorption to probe sulfur oxidation states in complex molecules

NASA Astrophysics Data System (ADS)

Vairavamurthy, A.

1998-10-01

X-ray absorption near-edge structure (XANES) spectroscopy offers an important non-destructive tool for determining oxidation states and for characterizing chemical speciation. The technique was used to experimentally verify the oxidation states of sulfur in different types of complex molecules because there are irregularities and uncertainties in assigning the values traditionally. The usual practice of determining oxidation states involves using a set of conventional rules. The oxidation state is an important control in the chemical speciation of sulfur, ranging from -2 to +6 in its different compounds. Experimental oxidation-state values for various types of sulfur compounds, using their XANES peak-energy positions, were assigned from a scale in which elemental sulfur and sulfate are designated as 0 and +6, respectively. Because these XANES-based values differed considerably from conventionally determined oxidation states for most sulfur compounds, a new term 'oxidation index' was coined to describe them. The experimental values were closer to those conventional values obtained by assigning shared electrons to the more electronegative atoms than to those based on other customary rules for assigning them. Because the oxidation index is distinct and characteristic for each different type of sulfur functionality, it becomes an important parameter for characterizing sulfur species, and for experimentally verifying uncertain oxidation states.

Functional bacteria and process metabolism of the Denitrifying Sulfur conversion-associated Enhanced Biological Phosphorus Removal (DS-EBPR) system: An investigation by operating the system from deterioration to restoration.

PubMed

Guo, Gang; Wu, Di; Hao, Tianwei; Mackey, Hamish Robert; Wei, Li; Wang, Haiguang; Chen, Guanghao

2016-05-15

A sulfur conversion-associated Enhanced Biological Phosphorus (P) Removal (EBPR) system is being developed to cater for the increasing needs to treat saline/brackish wastewater resulting from seawater intrusion into groundwater and sewers and frequent use of sulfate coagulants during drinking water treatment, as well as to meet the demand for eutrophication control in warm climate regions. However, the major functional bacteria and metabolism in this emerging biological nutrient removal system are still poorly understood. This study was thus designed to explore the functional microbes and metabolism in this new EBPR system by manipulating the deterioration, failure and restoration of a lab-scale system. This was achieved by changing the mixed liquor suspended solids (MLSS) concentration to monitor and evaluate the relationships among sulfur conversion (including sulfate reduction and sulfate production), P removal, variation in microbial community structures, and stoichiometric parameters. The results show that the stable Denitrifying Sulfur conversion-associated EBPR (DS-EBPR) system was enriched by sulfate-reducing bacteria (SRB) and sulfide-oxidizing bacteria (SOB). These bacteria synergistically participated in this new EBPR process, thereby inducing an appropriate level of sulfur conversion crucial for achieving a stable DS-EBPR performance, i.e. maintaining sulfur conversion intensity at 15-40 mg S/L, corresponding to an optimal sludge concentration of 6.5 g/L. This range of sulfur conversion favors microbial community competition and various energy flows from internal polymers (i.e. polysulfide or elemental sulfur (poly-S(2-)/S(0)) and poly-β-hydroxyalkanoates (PHA)) for P removal. If this range was exceeded, the system might deteriorate or even fail due to enrichment of glycogen-accumulating organisms (GAOs). Four methods of restoring the failed system were investigated: increasing the sludge concentration, lowering the salinity or doubling the COD loading, non of which restored SRB and SOB activities for DS-EBPR; only the final novel approach of adding 25 ± 5 mg S/L of external sulfide into the reactor at the beginning of the anoxic phase could efficiently restore the DS-EBPR system from failure. The present study represents a step towards understanding the DS-EBPR metabolism and provides an effective remedial measure for recovering a deteriorating or failed DS-EBPR system. Copyright © 2016 Elsevier Ltd. All rights reserved.

The studying of washing of arsenic and sulfur from coals having different ranges of arsenic contents

USGS Publications Warehouse

Wang, M.; Song, D.; Zheng, B.; Finkelman, R.B.; ,

2008-01-01

To study the effectiveness of washing in removal of arsenic and sulfur from coals with different ranges of arsenic concentration, coal was divided into three groups on the basis of arsenic content: 0-5.5 mg/kg, 5.5 mg/kg-8.00 mg/kg, and over 8.00 mg/kg. The result shows that the arsenic in coals with higher arsenic content occurs mainly in an inorganic state and can be relatively easily removed. Arsenic removal is very difficult and less complete when the arsenic content is lower than 5.5 mg/kg because most of this arsenic is in an organic state. There is no relationship between washing rate of total sulfur and arsenic content, but the relationship between the washing rate of total sulfur and percent of organic sulfur is very strong. ?? 2008 New York Academy of Sciences.

Subchronic toxicity evaluation of sulfur mustard in rats.

PubMed

Sasser, L B; Miller, R A; Kalkwarf, D R; Cushing, J A; Dacre, J C

1996-01-01

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

On-line sulfur isotope analysis of organic material by direct combustion: Preliminary results and potential applications

USGS Publications Warehouse

Kester, C.L.; Rye, R.O.; Johnson, C.A.; Schwartz, C.H.; Holmes, C.H.

2001-01-01

Sulfur isotopes have received little attention in ecology studies because plant and animal materials typically have low sulfur concentrations (< 1 wt.%) necessitating labor-intensive chemical extraction prior to analysis. To address the potential of direct combustion of organic material in an elemental analyzer coupled with a mass spectrometer, we compared results obtained by direct combustion to results obtained by sulfur extraction with Eschka's mixture. Direct combustion of peat and animal tissue gave reproducibility of better than 0.5??? and on average, values are 0.8??? higher than values obtained by Eschka extraction. Successful direct combustion of organic material appears to be a function of sample matrix and sulfur concentration. Initial results indicate that direct combustion provides fast, reliable results with minimal preparation. Pilot studies underway include defining bear diets and examining fluctuations between freshwater and brackish water in coastal environments.

Probing Titanium Disulfide-Sulfur Composite Materials for Li-S Batteries via In Situ X-ray Diffraction (XRD)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Q.; Bock, D.; Takeuchi, K. J.

Development of Li-S batteries is hindered by sluggish kinetics resulting from the intrinsic poor conductivity of sulfur and capacity degradation due to solubility of intermediate lithium polysulfides (LiPS). A strategy for overcoming these issues is to use TiS 2, which is a good electrical conductor and LiPS absorbant, as an additive to sulfur electrodes. Furthemore, from a structural perspective, we probed TiS 2-S composite materials during electrochemical discharge and charge reactions in propylene-oxide based glyme (DPGDME) electrolyte using in-situ XRD, revealing the synergistic effects of TiS 2 and S in the composites. TiS 2 was found to function effectively asmore » a conductive additive and improve the utilization of sulfur. Intercalation of Li + into TiS 2 takes place simultaneously with the sulfur-lithium reaction, and contributes favorably to the total realized capacity.« less

Acid–base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer

PubMed Central

Chen, Modi; Titcombe, Mari; Jiang, Jingkun; Jen, Coty; Kuang, Chongai; Fischer, Marc L.; Eisele, Fred L.; Siepmann, J. Ilja; Hanson, David R.; Zhao, Jun; McMurry, Peter H.

2012-01-01

Climate models show that particles formed by nucleation can affect cloud cover and, therefore, the earth's radiation budget. Measurements worldwide show that nucleation rates in the atmospheric boundary layer are positively correlated with concentrations of sulfuric acid vapor. However, current nucleation theories do not correctly predict either the observed nucleation rates or their functional dependence on sulfuric acid concentrations. This paper develops an alternative approach for modeling nucleation rates, based on a sequence of acid–base reactions. The model uses empirical estimates of sulfuric acid evaporation rates obtained from new measurements of neutral molecular clusters. The model predicts that nucleation rates equal the sulfuric acid vapor collision rate times a prefactor that is less than unity and that depends on the concentrations of basic gaseous compounds and preexisting particles. Predicted nucleation rates and their dependence on sulfuric acid vapor concentrations are in reasonable agreement with measurements from Mexico City and Atlanta. PMID:23091030

Probing Titanium Disulfide-Sulfur Composite Materials for Li-S Batteries via In Situ X-ray Diffraction (XRD)

DOE PAGES

Zhang, Q.; Bock, D.; Takeuchi, K. J.; ...

2017-03-01

Development of Li-S batteries is hindered by sluggish kinetics resulting from the intrinsic poor conductivity of sulfur and capacity degradation due to solubility of intermediate lithium polysulfides (LiPS). A strategy for overcoming these issues is to use TiS 2, which is a good electrical conductor and LiPS absorbant, as an additive to sulfur electrodes. Furthemore, from a structural perspective, we probed TiS 2-S composite materials during electrochemical discharge and charge reactions in propylene-oxide based glyme (DPGDME) electrolyte using in-situ XRD, revealing the synergistic effects of TiS 2 and S in the composites. TiS 2 was found to function effectively asmore » a conductive additive and improve the utilization of sulfur. Intercalation of Li + into TiS 2 takes place simultaneously with the sulfur-lithium reaction, and contributes favorably to the total realized capacity.« less

Acid-base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer.

PubMed

Chen, Modi; Titcombe, Mari; Jiang, Jingkun; Jen, Coty; Kuang, Chongai; Fischer, Marc L; Eisele, Fred L; Siepmann, J Ilja; Hanson, David R; Zhao, Jun; McMurry, Peter H

2012-11-13

Climate models show that particles formed by nucleation can affect cloud cover and, therefore, the earth's radiation budget. Measurements worldwide show that nucleation rates in the atmospheric boundary layer are positively correlated with concentrations of sulfuric acid vapor. However, current nucleation theories do not correctly predict either the observed nucleation rates or their functional dependence on sulfuric acid concentrations. This paper develops an alternative approach for modeling nucleation rates, based on a sequence of acid-base reactions. The model uses empirical estimates of sulfuric acid evaporation rates obtained from new measurements of neutral molecular clusters. The model predicts that nucleation rates equal the sulfuric acid vapor collision rate times a prefactor that is less than unity and that depends on the concentrations of basic gaseous compounds and preexisting particles. Predicted nucleation rates and their dependence on sulfuric acid vapor concentrations are in reasonable agreement with measurements from Mexico City and Atlanta.

Structural and Functional Insights from the Metagenome of an Acidic Hot Spring Microbial Planktonic Community in the Colombian Andes

PubMed Central

Jiménez, Diego Javier; Andreote, Fernando Dini; Chaves, Diego; Montaña, José Salvador; Osorio-Forero, Cesar; Junca, Howard; Zambrano, María Mercedes; Baena, Sandra

2012-01-01

A taxonomic and annotated functional description of microbial life was deduced from 53 Mb of metagenomic sequence retrieved from a planktonic fraction of the Neotropical high Andean (3,973 meters above sea level) acidic hot spring El Coquito (EC). A classification of unassembled metagenomic reads using different databases showed a high proportion of Gammaproteobacteria and Alphaproteobacteria (in total read affiliation), and through taxonomic affiliation of 16S rRNA gene fragments we observed the presence of Proteobacteria, micro-algae chloroplast and Firmicutes. Reads mapped against the genomes Acidiphilium cryptum JF-5, Legionella pneumophila str. Corby and Acidithiobacillus caldus revealed the presence of transposase-like sequences, potentially involved in horizontal gene transfer. Functional annotation and hierarchical comparison with different datasets obtained by pyrosequencing in different ecosystems showed that the microbial community also contained extensive DNA repair systems, possibly to cope with ultraviolet radiation at such high altitudes. Analysis of genes involved in the nitrogen cycle indicated the presence of dissimilatory nitrate reduction to N2 (narGHI, nirS, norBCDQ and nosZ), associated with Proteobacteria-like sequences. Genes involved in the sulfur cycle (cysDN, cysNC and aprA) indicated adenylsulfate and sulfite production that were affiliated to several bacterial species. In summary, metagenomic sequence data provided insight regarding the structure and possible functions of this hot spring microbial community, describing some groups potentially involved in the nitrogen and sulfur cycling in this environment. PMID:23251687

Influence of Wastewater Discharge on the Metabolic Potential of the Microbial Community in River Sediments.

PubMed

Li, Dong; Sharp, Jonathan O; Drewes, Jörg E

2016-01-01

To reveal the variation of microbial community functions during water filtration process in river sediments, which has been utilized widely in natural water treatment systems, this study investigates the influence of municipal wastewater discharge to streams on the phylotype and metabolic potential of the microbiome in upstream and particularly various depths of downstream river sediments. Cluster analyses based on both microbial phylogenetic and functional data collectively revealed that shallow upstream sediments grouped with those from deeper subsurface downstream regions. These sediment samples were distinct from those found in shallow downstream sediments. Functional genes associated with carbohydrate, xenobiotic, and certain amino acid metabolisms were overrepresented in upstream and deep downstream samples. In contrast, the more immediate contact with wastewater discharge in shallow downstream samples resulted in an increase in the relative abundance of genes associated with nitrogen, sulfur, purine and pyrimidine metabolisms, as well as restriction-modification systems. More diverse bacterial phyla were associated with upstream and deep downstream sediments, mainly including Actinobacteria, Planctomycetes, and Firmicutes. In contrast, in shallow downstream sediments, genera affiliated with Betaproteobacteria and Gammaproteobacteria were enriched with putative functions that included ammonia and sulfur oxidation, polyphosphate accumulation, and methylotrophic bacteria. Collectively, these results highlight the enhanced capabilities of microbial communities residing in deeper stream sediments for the transformation of water contaminants and thus provide a foundation for better design of natural water treatment systems to further improve the removal of contaminants.

Bifluoride-catalysed sulfur(VI) fluoride exchange reaction for the synthesis of polysulfates and polysulfonates

NASA Astrophysics Data System (ADS)

Gao, Bing; Zhang, Linda; Zheng, Qinheng; Zhou, Feng; Klivansky, Liana M.; Lu, Jianmei; Liu, Yi; Dong, Jiajia; Wu, Peng; Sharpless, K. Barry

2017-11-01

Polysulfates and polysulfonates possess exceptional mechanical properties making them potentially valuable engineering polymers. However, they have been little explored due to a lack of reliable synthetic access. Here we report bifluoride salts (Q+[FHF]-, where Q+ represents a wide range of cations) as powerful catalysts for the sulfur(VI) fluoride exchange (SuFEx) reaction between aryl silyl ethers and aryl fluorosulfates (or alkyl sulfonyl fluorides). The bifluoride salts are significantly more active in catalysing the SuFEx reaction compared to organosuperbases, therefore enabling much lower catalyst-loading (down to 0.05 mol%). Using this chemistry, we are able to prepare polysulfates and polysulfonates with high molecular weight, narrow polydispersity and excellent functional group tolerance. The process is practical with regard to the reduced cost of catalyst, polymer purification and by-product recycling. We have also observed that the process is not sensitive to scale-up, which is essential for its future translation from laboratory research to industrial applications.

Controlled exposure of volunteers with chronic obstructive pulmonary disease to sulfur dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linn, W.S.; Fischer, D.A.; Shamoo, D.A.

1985-08-01

Twenty-four volunteers with chronic obstructive pulmonary disease (COPD) were exposed to sulfur dioxide (SO/sub 2/) at 0, 0.4, and 0.8 ppm in an environmental control chamber. Exposures lasted 1 hr and included two 15-min exercise periods (mean exercise ventilation rate 18 liter/min). Pulmonary mechanical function was evaluated before exposures, after initial exercise, and at the end of exposure. Blood oxygenation was measured by ear oximetry before exposure and during the second exercise period. Symptoms were recorded throughout exposure periods and for 1 week afterward. No statistically significant changes in physiology or symptoms could be attributed to SO/sub 2/ exposure. Oldermore » adults with COPD seem less reactive to a given concentration of SO/sub 2/ than heavily exercising young adult asthmatics. This may be due to lower ventilation rates (i.e., lower SO/sub 2/ dose rates) and/or to lower airway reactivity in the COPD group.« less

Jumping, Rotating, and Flapping: The Atomic-Scale Motion of Thiophene on Cu(111).

PubMed

Lechner, Barbara A J; Sacchi, Marco; Jardine, Andrew P; Hedgeland, Holly; Allison, William; Ellis, John; Jenkins, Stephen J; Dastoor, Paul C; Hinch, B J

2013-06-06

Self-assembled monolayers of sulfur-containing heterocycles and linear oligomers containing thiophene groups have been widely employed in organic electronic applications. Here, we investigate the dynamics of isolated thiophene molecules on Cu(111) by combining helium spin-echo (HeSE) spectroscopy with density functional theory calculations. We show that the thiophene/Cu(111) system displays a rich array of aperiodic dynamical phenomena that include jump diffusion between adjacent atop sites over a 59-62 meV barrier and activated rotation around a sulfur-copper anchor, two processes that have been observed previously for related systems. In addition, we present experimental evidence for a new, weakly activated process, the flapping of the molecular ring. Repulsive inter-adsorbate interactions and an exceptionally high friction coefficient of 5 ± 2 ps(-1) are also observed. These experiments demonstrate the versatility of the HeSE technique, and the quantitative information extracted in a detailed analysis provides an ideal benchmark for state-of-the-art theoretical techniques including nonlocal adsorbate-substrate interactions.

AB INITIO Simulations of Desorption and Reactivity of Glycine at a Water-Pyrite Interface at ``Iron-Sulfur World'' Prebiotic Conditions

NASA Astrophysics Data System (ADS)

Pollet, Rodolphe; Boehme, Christian; Marx, Dominik

2006-08-01

Glycine at the interface of a pyrite surface (001) FeS2, and bulk water at high pressure and temperature conditions relevant to the “iron-sulfur world” scenario of the origin of life is investigated by theoretical means. Car-Parrinello molecular dynamics is used in order to study the desorption process of the zwitterionic form of this amino acid using two different adsorption modes, where either only one or both oxygens of the carboxylate group are anchored to surface iron atoms. It is found that the formation of stabilizing hydrogen bonds plays a key role in the detachment process, leading to longer retention times for the bidentate adsorption mode. In addition, the chemical reactivity of this heterogeneous system is probed by calculating the Fukui functions as site-specific reactivity indices. The most prominent targets for both nucleophilic and electrophilic reactions to occur are surface atoms, whereas the reactivity of glycine is only slightly affected upon anchoring.

Anaerobic Copper Toxicity and Iron-Sulfur Cluster Biogenesis in Escherichia coli.

PubMed

Tan, Guoqiang; Yang, Jing; Li, Tang; Zhao, Jin; Sun, Shujuan; Li, Xiaokang; Lin, Chuxian; Li, Jianghui; Zhou, Huaibin; Lyu, Jianxin; Ding, Huangen

2017-08-15

While copper is an essential trace element in biology, pollution of groundwater from copper has become a threat to all living organisms. Cellular mechanisms underlying copper toxicity, however, are still not fully understood. Previous studies have shown that iron-sulfur proteins are among the primary targets of copper toxicity in Escherichia coli under aerobic conditions. Here, we report that, under anaerobic conditions, iron-sulfur proteins in E. coli cells are even more susceptible to copper in medium. Whereas addition of 0.2 mM copper(II) chloride to LB (Luria-Bertani) medium has very little or no effect on iron-sulfur proteins in wild-type E. coli cells under aerobic conditions, the same copper treatment largely inactivates iron-sulfur proteins by blocking iron-sulfur cluster biogenesis in the cells under anaerobic conditions. Importantly, proteins that do not have iron-sulfur clusters (e.g., fumarase C and cysteine desulfurase) in E. coli cells are not significantly affected by copper treatment under aerobic or anaerobic conditions, indicating that copper may specifically target iron-sulfur proteins in cells. Additional studies revealed that E. coli cells accumulate more intracellular copper under anaerobic conditions than under aerobic conditions and that the elevated copper content binds to the iron-sulfur cluster assembly proteins IscU and IscA, which effectively inhibits iron-sulfur cluster biogenesis. The results suggest that the copper-mediated inhibition of iron-sulfur proteins does not require oxygen and that iron-sulfur cluster biogenesis is the primary target of anaerobic copper toxicity in cells. IMPORTANCE Copper contamination in groundwater has become a threat to all living organisms. However, cellular mechanisms underlying copper toxicity have not been fully understood up to now. The work described here reveals that iron-sulfur proteins in Escherichia coli cells are much more susceptible to copper in medium under anaerobic conditions than they are under aerobic conditions. Under anaerobic conditions, E. coli cells accumulate excess intracellular copper, which specifically targets iron-sulfur proteins by blocking iron-sulfur cluster biogenesis. Since iron-sulfur proteins are involved in diverse and vital physiological processes, inhibition of iron-sulfur cluster biogenesis by copper disrupts multiple cellular functions and ultimately inhibits cell growth. The results from this study illustrate a new interplay between intracellular copper toxicity and iron-sulfur cluster biogenesis in bacterial cells under anaerobic conditions. Copyright © 2017 American Society for Microbiology.

Anaerobic Copper Toxicity and Iron-Sulfur Cluster Biogenesis in Escherichia coli

PubMed Central

Tan, Guoqiang; Yang, Jing; Li, Tang; Zhao, Jin; Sun, Shujuan; Li, Xiaokang; Lin, Chuxian; Li, Jianghui; Zhou, Huaibin

2017-01-01

ABSTRACT While copper is an essential trace element in biology, pollution of groundwater from copper has become a threat to all living organisms. Cellular mechanisms underlying copper toxicity, however, are still not fully understood. Previous studies have shown that iron-sulfur proteins are among the primary targets of copper toxicity in Escherichia coli under aerobic conditions. Here, we report that, under anaerobic conditions, iron-sulfur proteins in E. coli cells are even more susceptible to copper in medium. Whereas addition of 0.2 mM copper(II) chloride to LB (Luria-Bertani) medium has very little or no effect on iron-sulfur proteins in wild-type E. coli cells under aerobic conditions, the same copper treatment largely inactivates iron-sulfur proteins by blocking iron-sulfur cluster biogenesis in the cells under anaerobic conditions. Importantly, proteins that do not have iron-sulfur clusters (e.g., fumarase C and cysteine desulfurase) in E. coli cells are not significantly affected by copper treatment under aerobic or anaerobic conditions, indicating that copper may specifically target iron-sulfur proteins in cells. Additional studies revealed that E. coli cells accumulate more intracellular copper under anaerobic conditions than under aerobic conditions and that the elevated copper content binds to the iron-sulfur cluster assembly proteins IscU and IscA, which effectively inhibits iron-sulfur cluster biogenesis. The results suggest that the copper-mediated inhibition of iron-sulfur proteins does not require oxygen and that iron-sulfur cluster biogenesis is the primary target of anaerobic copper toxicity in cells. IMPORTANCE Copper contamination in groundwater has become a threat to all living organisms. However, cellular mechanisms underlying copper toxicity have not been fully understood up to now. The work described here reveals that iron-sulfur proteins in Escherichia coli cells are much more susceptible to copper in medium under anaerobic conditions than they are under aerobic conditions. Under anaerobic conditions, E. coli cells accumulate excess intracellular copper, which specifically targets iron-sulfur proteins by blocking iron-sulfur cluster biogenesis. Since iron-sulfur proteins are involved in diverse and vital physiological processes, inhibition of iron-sulfur cluster biogenesis by copper disrupts multiple cellular functions and ultimately inhibits cell growth. The results from this study illustrate a new interplay between intracellular copper toxicity and iron-sulfur cluster biogenesis in bacterial cells under anaerobic conditions. PMID:28576762

Bacterial Iron–Sulfur Regulatory Proteins As Biological Sensor-Switches

PubMed Central

Crack, Jason C.; Green, Jeffrey; Hutchings, Matthew I.; Thomson, Andrew J.

2012-01-01

Abstract Significance: In recent years, bacterial iron–sulfur cluster proteins that function as regulators of gene transcription have emerged as a major new group. In all cases, the cluster acts as a sensor of the environment and enables the organism to adapt to the prevailing conditions. This can range from mounting a response to oxidative or nitrosative stress to switching between anaerobic and aerobic respiratory pathways. The sensitivity of these ancient cofactors to small molecule reactive oxygen and nitrogen species, in particular, makes them ideally suited to function as sensors. Recent Advances: An important challenge is to obtain mechanistic and structural information about how these regulators function and, in particular, how the chemistry occurring at the cluster drives the subsequent regulatory response. For several regulators, including FNR, SoxR, NsrR, IscR, and Wbl proteins, major advances in understanding have been gained recently and these are reviewed here. Critical Issues: A common theme emerging from these studies is that the sensitivity and specificity of the cluster of each regulatory protein must be exquisitely controlled by the protein environment of the cluster. Future Directions: A major future challenge is to determine, for a range of regulators, the key factors for achieving control of sensitivity/specificity. Such information will lead, eventually, to a system understanding of stress response, which often involves more than one regulator. Antioxid. Redox Signal. 17, 1215–1231. PMID:22239203

Microbial and functional diversity of a subterrestrial high pH groundwater associated to serpentinization.

PubMed

Tiago, Igor; Veríssimo, António

2013-06-01

Microbial and functional diversity were assessed, from a serpentinization-driven subterrestrial alkaline aquifer - Cabeço de Vide Aquifer (CVA) in Portugal. DGGE analyses revealed the presence of a stable microbial community. By 16S rRNA gene libraries and pyrosequencing analyses, a diverse bacterial composition was determined, contrasting with low archaeal diversity. Within Bacteria the majority of the populations were related to organisms or sequences affiliated to class Clostridia, but members of classes Acidobacteria, Actinobacteria, Alphaproteobacteria, Betaproteobacteria, Deinococci, Gammaproteobacteria and of the phyla Bacteroidetes, Chloroflexi and Nitrospira were also detected. Domain Archaea encompassed mainly sequences affiliated to Euryarchaeota. Only form I RuBisCO - cbbL was detected. Autotrophic carbon fixation via the rTCA, 3-HP and 3-HP/4H-B cycles could not be confirmed. The detected APS reductase alpha subunit - aprA sequences were phylogenetically related to sequences of sulfate-reducing bacteria belonging to Clostridia, and also to sequences of chemolithoautothrophic sulfur-oxidizing bacteria belonging to Betaproteobacteria. Sequences of methyl coenzyme M reductase - mcrA were phylogenetically affiliated to sequences belonging to Anaerobic Methanotroph group 1 (ANME-1). The populations found and the functional key markers detected in CVA suggest that metabolisms related to H2 , methane and/or sulfur may be the major driving forces in this environment. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Effect of acidification conditions on the properties of carbon nanotube fibers

NASA Astrophysics Data System (ADS)

Wang, Kun; Li, Min; Liu, Ya-Nan; Gu, Yizhuo; Li, Qingwen; Zhang, Zuoguang

2014-02-01

Carbon nanotube (CNT) fibers prepared by dry-spun method were functionalized by mixture of nitric and sulfuric acids. The effects of acidification conditions on the electrical conductivity and tensile properties of CNT fibers were investigated. A strong, high conductive CNT fiber was obtained under the optimal mixture ratio and processing time, with a electrical conductivity and tensile strength up to 3.2 × 104 S/m and 1103 MPa, respectively. It showed that the acids densified the surface of the CNT fiber and introduced functional groups onto the tubes, both of which contributed to the conductivity improvement of the CNT fiber. The infrared spectroscopy, Raman and fracture analysis indicated that acidification process resulted in two competitive effects on the tensile properties of CNT fibers, one was the positive contribution by the enhancement of interactions between CNTs through the densification and functional groups, and the other was the negative effect due to the structural destruction of the tubes.

An effective 2-band eg model of sulfur hydride H3S for high-Tc superconductivity

NASA Astrophysics Data System (ADS)

Nishiguchi, Kazutaka; Teranishi, Shingo; Miyao, Satoaki; Matsushita, Goh; Kusakabe, Koichi

To understand high transition temperature (Tc) superconductivity in sulfur hydride H3S, we propose an effective 2-band model having the eg symmetry as the minimal model for H3S. Two eg orbitals centered on a sulfur S atom are chosen for the smallest representation of relevant bands with the van-Hove singularity around the Fermi levels except for the Γ-centered small hole pockets by the sulfur 3 p orbitals. By using the maximally localized Wannier functions, we derive the minimal effective model preserving the body-centered cubic (bcc) crystal symmetry of the H3S phase having the highest Tc ( 203 K under pressures) among the other polymorphs of H3S.

Elemental composition of particulate matter and the association with lung function.

PubMed

Eeftens, Marloes; Hoek, Gerard; Gruzieva, Olena; Mölter, Anna; Agius, Raymond; Beelen, Rob; Brunekreef, Bert; Custovic, Adnan; Cyrys, Josef; Fuertes, Elaine; Heinrich, Joachim; Hoffmann, Barbara; de Hoogh, Kees; Jedynska, Aleksandra; Keuken, Menno; Klümper, Claudia; Kooter, Ingeborg; Krämer, Ursula; Korek, Michal; Koppelman, Gerard H; Kuhlbusch, Thomas A J; Simpson, Angela; Smit, Henriëtte A; Tsai, Ming-Yi; Wang, Meng; Wolf, Kathrin; Pershagen, Göran; Gehring, Ulrike

2014-09-01

Negative effects of long-term exposure to particulate matter (PM) on lung function have been shown repeatedly. Spatial differences in the composition and toxicity of PM may explain differences in observed effect sizes between studies. We conducted a multicenter study in 5 European birth cohorts-BAMSE (Sweden), GINIplus and LISAplus (Germany), MAAS (United Kingdom), and PIAMA (The Netherlands)-for which lung function measurements were available for study subjects at the age of 6 or 8 years. Individual annual average residential exposure to copper, iron, potassium, nickel, sulfur, silicon, vanadium, and zinc within PM smaller than 2.5 μm (PM2.5) and smaller than 10 μm (PM10) was estimated using land-use regression models. Associations between air pollution and lung function were analyzed by linear regression within cohorts, adjusting for potential confounders, and then combined by random effects meta-analysis. We observed small reductions in forced expiratory volume in the first second, forced vital capacity, and peak expiratory flow related to exposure to most elemental pollutants, with the most substantial negative associations found for nickel and sulfur. PM10 nickel and PM10 sulfur were associated with decreases in forced expiratory volume in the first second of 1.6% (95% confidence interval = 0.4% to 2.7%) and 2.3% (-0.1% to 4.6%) per increase in exposure of 2 and 200 ng/m, respectively. Associations remained after adjusting for PM mass. However, associations with these elements were not evident in all cohorts, and heterogeneity of associations with exposure to various components was larger than for exposure to PM mass. Although we detected small adverse effects on lung function associated with annual average levels of some of the evaluated elements (particularly nickel and sulfur), lower lung function was more consistently associated with increased PM mass.

Expanding the Capabilities of the JPL Electronic Nose for an International Space Station Technology Demonstration

NASA Technical Reports Server (NTRS)

Ryan, Margaret A.; Shevade, A. V.; Taylor, C. J.; Homer, M. L.; Jewell, A. D.; Kisor, A.; Manatt, K. S .; Yen, S. P. S.; Blanco, M.; Goddard, W. A., III

2006-01-01

An array-based sensing system based on polymer/carbon composite conductometric sensors is under development at JPL for use as an environmental monitor in the International Space Station. Sulfur dioxide has been added to the analyte set for this phase of development. Using molecular modeling techniques, the interaction energy between SO2 and polymer functional groups has been calculated, and polymers selected as potential SO2 sensors. Experiment has validated the model and two selected polymers have been shown to be promising materials for SO2 detection.

Metagenome-scale analysis yields insights into the structure and function of microbial communities in a copper bioleaching heap.

PubMed

Zhang, Xian; Niu, Jiaojiao; Liang, Yili; Liu, Xueduan; Yin, Huaqun

2016-01-19

Metagenomics allows us to acquire the potential resources from both cultivatable and uncultivable microorganisms in the environment. Here, shotgun metagenome sequencing was used to investigate microbial communities from the surface layer of low grade copper tailings that were industrially bioleached at the Dexing Copper Mine, China. A bioinformatics analysis was further performed to elucidate structural and functional properties of the microbial communities in a copper bioleaching heap. Taxonomic analysis revealed unexpectedly high microbial biodiversity of this extremely acidic environment, as most sequences were phylogenetically assigned to Proteobacteria, while Euryarchaeota-related sequences occupied little proportion in this system, assuming that Archaea probably played little role in the bioleaching systems. At the genus level, the microbial community in mineral surface-layer was dominated by the sulfur- and iron-oxidizing acidophiles such as Acidithiobacillus-like populations, most of which were A. ferrivorans-like and A. ferrooxidans-like groups. In addition, Caudovirales were the dominant viral type observed in this extremely environment. Functional analysis illustrated that the principal participants related to the key metabolic pathways (carbon fixation, nitrogen metabolism, Fe(II) oxidation and sulfur metabolism) were mainly identified to be Acidithiobacillus-like, Thiobacillus-like and Leptospirillum-like microorganisms, indicating their vital roles. Also, microbial community harbored certain adaptive mechanisms (heavy metal resistance, low pH adaption, organic solvents tolerance and detoxification of hydroxyl radicals) as they performed their functions in the bioleaching system. Our study provides several valuable datasets for understanding the microbial community composition and function in the surface-layer of copper bioleaching heap.

Estimating historical anthropogenic global sulfur emission patterns for the period 1850-1990

NASA Astrophysics Data System (ADS)

Lefohn, Allen S.; Husar, Janja D.; Husar, Rudolf B.

It is important to establish a reliable regional emission inventory of sulfur as a function of time when assessing the possible effects of global change and acid rain. This study developed a database of annual estimates of national sulfur emissions from 1850 to 1990. A common methodology was applied across all years and countries allowing for global totals to be produced by adding estimates from all countries. The consistent approach facilitates the modification of the database and the observation of changes at national, regional, or global levels. The emission estimates were based on net production (i.e., production plus imports minus exports), sulfur content, and sulfur retention for each country's production activities. Because the emission estimates were based on the above considerations, our database offers an opportunity to independently compare our results with those estimates based on individual country estimates. Fine temporal resolution clearly shows emission changes associated with specific historical events (e.g., wars, depressions, etc.) on a regional, national, or global basis. The spatial pattern of emissions shows that the US, the USSR, and China were the main sulfur emitters (i.e., approximately 50% of the total) in the world in 1990. The USSR and the US appear to have stabilized their sulfur emissions over the past 20 yr, and the recent increases in global sulfur emissions are linked to the rapid increases in emissions from China. Sulfur emissions have been reduced in some cases by switching from high- to low-sulfur coals. Flue gas desulfurization (FGD) has apparently made important contributions to emission reductions in only a few countries, such as Germany.

Ab initio simulations of bond breaking in sulfur crosslinked isoprene oligomer units

NASA Astrophysics Data System (ADS)

Gehrke, Sascha; Alznauer, Hans Tobias; Karimi-Varzaneh, Hossein Ali; Becker, Jörg August

2017-12-01

Sulfur crosslinked polyisoprene (rubber) is used in important material components for a number of technical tasks (e.g., in tires and sealings). If mechanical stress, like tension or shear, is applied on these material components, the sulfur crosslinks suffer from homolytic bond breaking. In this work, we have simulated the bond breaking mechanism of sulfur crosslinks between polyisoprene chains using Car-Parrinello molecular dynamic simulations and investigated the maximum forces which can be resisted by the crosslinks. Small model systems with crosslinks formed by chains of N = 1 to N = 6 sulfur atoms have been simulated with the slow growth-technique, known from the literature. The maximum force can be thereby determined from the calculated energies as a function of strain (elongation). The stability of the crosslink under strain is quantified in terms of the maximum force that can be resisted by the system before the crosslink breaks. As shown by our simulations, this maximum force decreases with the sulfur crosslink length N in a step like manner. Our findings indicate that in bridges with N = 1, 2, and 3 sulfur atoms predominantly, carbon-sulfur bonds break, while in crosslinks with N > 3, the breaking of a sulfur-sulfur bond is the dominant failure mechanism. The results are explained within a simple chemical bond model, which describes how the delocalization of the electrons in the generated radicals can lower their electronic energy and decrease the activation barriers. It is described which of the double bonds in the isoprene units are involved in the mechanochemistry of crosslinked rubber.

Sulfur Species as Redox Partners and Electron Shuttles for Ferrihydrite Reduction by Sulfurospirillum deleyianum

PubMed Central

Lohmayer, Regina; Kappler, Andreas; Lösekann-Behrens, Tina

2014-01-01

Iron(III) (oxyhydr)oxides can represent the dominant microbial electron acceptors under anoxic conditions in many aquatic environments, which makes understanding the mechanisms and processes regulating their dissolution and transformation particularly important. In a previous laboratory-based study, it has been shown that 0.05 mM thiosulfate can reduce 6 mM ferrihydrite indirectly via enzymatic reduction of thiosulfate to sulfide by the sulfur-reducing bacterium Sulfurospirillum deleyianum, followed by abiotic reduction of ferrihydrite coupled to reoxidation of sulfide. Thiosulfate, elemental sulfur, and polysulfides were proposed as reoxidized sulfur species functioning as electron shuttles. However, the exact electron transfer pathway remained unknown. Here, we present a detailed analysis of the sulfur species involved. Apart from thiosulfate, substoichiometric amounts of sulfite, tetrathionate, sulfide, or polysulfides also initiated ferrihydrite reduction. The portion of thiosulfate produced during abiotic ferrihydrite-dependent reoxidation of sulfide was about 10% of the total sulfur at maximum. The main abiotic oxidation product was elemental sulfur attached to the iron mineral surface, which indicates that direct contact between microorganisms and ferrihydrite is necessary to maintain the iron reduction process. Polysulfides were not detected in the liquid phase. Minor amounts were found associated either with microorganisms or the mineral phase. The abiotic oxidation of sulfide in the reaction with ferrihydrite was identified as rate determining. Cysteine, added as a sulfur source and a reducing agent, also led to abiotic ferrihydrite reduction and therefore should be eliminated when sulfur redox reactions are investigated. Overall, we could demonstrate the large impact of intermediate sulfur species on biogeochemical iron transformations. PMID:24632263

Sulfur deposition simulations over China, Japan, and Korea: a model intercomparison study for abating sulfur emission.

PubMed

Kim, Cheol-Hee; Chang, Lim-Seok; Meng, Fan; Kajino, Mizuo; Ueda, Hiromasa; Zhang, Yuanhang; Son, Hye-Young; Lee, Jong-Jae; He, Youjiang; Xu, Jun; Sato, Keiichi; Sakurai, Tatsuya; Han, Zhiwei; Duan, Lei; Kim, Jeong-Soo; Lee, Suk-Jo; Song, Chang-Keun; Ban, Soo-Jin; Shim, Shang-Gyoo; Sunwoo, Young; Lee, Tae-Young

2012-11-01

In response to increasing trends in sulfur deposition in Northeast Asia, three countries in the region (China, Japan, and Korea) agreed to devise abatement strategies. The concepts of critical loads and source-receptor (S-R) relationships provide guidance for formulating such strategies. Based on the Long-range Transboundary Air Pollutants in Northeast Asia (LTP) project, this study analyzes sulfur deposition data in order to optimize acidic loads over the three countries. The three groups involved in this study carried out a full year (2002) of sulfur deposition modeling over the geographic region spanning the three countries, using three air quality models: MM5-CMAQ, MM5-RAQM, and RAMS-CADM, employed by Chinese, Japanese, and Korean modeling groups, respectively. Each model employed its own meteorological numerical model and model parameters. Only the emission rates for SO(2) and NO(x) obtained from the LTP project were the common parameter used in the three models. Three models revealed some bias from dry to wet deposition, particularly the latter because of the bias in annual precipitation. This finding points to the need for further sensitivity tests of the wet removal rates in association with underlying cloud-precipitation physics and parameterizations. Despite this bias, the annual total (dry plus wet) sulfur deposition predicted by the models were surprisingly very similar. The ensemble average annual total deposition was 7,203.6 ± 370 kt S with a minimal mean fractional error (MFE) of 8.95 ± 5.24 % and a pattern correlation (PC) of 0.89-0.93 between the models. This exercise revealed that despite rather poor error scores in comparison with observations, these consistent total deposition values across the three models, based on LTP group's input data assumptions, suggest a plausible S-R relationship that can be applied to the next task of designing cost-effective emission abatement strategies.

Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 1. Minor structures

USGS Publications Warehouse

Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

1995-01-01

An investigation of the strong-acid characteristics (pKa 3.0 or less) of fulvic acid from the Suwannee River, Georgia, was conducted. Quantitative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structures, keto acid structures, and aromatic carboxyl-group structures. These determinations were made by using a variety of spectrometric (13C-nuclear magnetic resonance, infrared, and ultraviolet spectrometry) and titrimetric characterizations on fulvic acid or fulvic acid samples that were chemically derivatized to indicate certain functional groups. Only keto acid and aromatic carboxyl-group structures contributed significantly to the strong-acid characteristics of the fulvic acid; these structures accounted for 43% of the strong-acid acidity. The remaining 57% of the strong acids are aliphatic carboxyl groups in unusual and/or complex configurations for which limited model compound data are available.

[The dose response decrease of lung function associated with the urinary polycyclic aromatic hydrocarbons metabolites in coke oven workers].

PubMed

Hu, Die; Deng, Qi-fei; Huang, Su-li; He, Yun-feng; Guo, Huan; Wu, Tang-chun

2012-12-01

To analyze the relationship between metabolites of polycyclic aromatic hydrocarbons (PAHs) and lung function in coke oven workers, and to provide scientific basis for further exploring the potential mechanism and developing the preventing strategies of the workers' early lung damage. We measured carbon monoxide, sulfur dioxide, benzene soluble matter, particulate matters, and PAHs at different workplaces of a coke oven plant. Detailed information on demography and occupational health condition of 912 workers were collected. We divided these workers into control group and coke oven group according to their workplaces and the different concentrations of COEs in the environment. We detected 10 urinary PAH metabolites and lung function using gas chromatography-mass spectrometry and spirometric tests, respectively. FEV(1.0) (91.12 ± 13.31) and FEV(1.0)/FVC (108.61 ± 20.37) of the coke oven group is significantly lower than the control group (94.16 ± 15.57, 113.45 ± 19.70). In the coke oven group, the hydroxyphenanthrene and 1-hydroxypyrene are negatively correlated with FEV(1.0)/FVC (β = -0.136, β = -0.100), Ptrend < 0.05 for all. The dose response decrease of lung function is associated with the urinary PAH metabolites in coke oven workers. Indicated that the long exposure to PAHs may cause the early lung damage in coke oven workers, phenanthrene and pyrene may be the main factors.

Application of a sodium sulfur cell with dynamic sulfur electrode to a battery system

NASA Astrophysics Data System (ADS)

Tokoi, H.; Takahashi, K.; Shimoyashiki, S.

1992-01-01

The construction and performance of a sodium sulfur battery system with dynamic sulfur electrodes are described. Three cells were first connected in parallel, then two such groups were connected in series. Each cell included a liquid sodium-filled beta-double-prime-alumina tube and a system to feed liquid sulfur into the annular cathode. Low-resistance graphite felt was tightly packed around the beta-double-prime-alumina tube. Sodium pentasulfide was removed from the sulfur electrode. The battery was operated automatically and stably charged and discharged in the two-phase region. The discharged energy was 4372 Wh (capacity 1170 Ah) during a continuous operation of 19.5 h. The discharge/charge energy efficiency of the battery was 82 percent at an averaged current density of 100 mA/sq cm and operating temperature of 350 C. The deviation of the cell current in a parallel chain was less than 7 percent, and this was induced by the difference in internal resistance. In the daily charge/discharge cycle, cell capacity with the dynamic sulfur electrode was 1.5 times higher than that with the static sulfur electrode using the same active surface of beta-double-prime-alumina, because the internal resistance of the former cell was constant regardless of cell capacity. This battery system with a dynamic sulfur electrode can be applied to energy storage systems,such as large scale load leveling systems, electric vehicle batteries, and solar energy systems.

The Role of SufS Is Restricted to Fe-S Cluster Biosynthesis in Escherichia coli.

PubMed

Bühning, Martin; Valleriani, Angelo; Leimkühler, Silke

2017-04-11

In Escherichia coli, two different systems that are important for the coordinate formation of Fe-S clusters have been identified, namely, the ISC and SUF systems. The ISC system is the housekeeping Fe-S machinery, which provides Fe-S clusters for numerous cellular proteins. The IscS protein of this system was additionally revealed to be the primary sulfur donor for several sulfur-containing molecules with important biological functions, among which are the molybdenum cofactor (Moco) and thiolated nucleosides in tRNA. Here, we show that deletion of central components of the ISC system in addition to IscS leads to an overall decrease in Fe-S cluster enzyme and molybdoenzyme activity in addition to a decrease in the number of Fe-S-dependent thiomodifications of tRNA, based on the fact that some proteins involved in Moco biosynthesis and tRNA thiolation are Fe-S-dependent. Complementation of the ISC deficient strains with the suf operon restored the activity of Fe-S-containing proteins, including the MoaA protein, which is involved in the conversion of 5'GTP to cyclic pyranopterin monophosphate in the fist step of Moco biosynthesis. While both systems share a high degree of similarity, we show that the function of their respective l-cysteine desulfurase IscS or SufS is specific for each cellular pathway. It is revealed that SufS cannot play the role of IscS in sulfur transfer for the formation of 2-thiouridine, 4-thiouridine, or the dithiolene group of molybdopterin, being unable to interact with TusA or ThiI. The results demonstrate that the role of the SUF system is exclusively restricted to Fe-S cluster assembly in the cell.

Structure of human Fe-S assembly subcomplex reveals unexpected cysteine desulfurase architecture and acyl-ACP-ISD11 interactions.

PubMed

Cory, Seth A; Van Vranken, Jonathan G; Brignole, Edward J; Patra, Shachin; Winge, Dennis R; Drennan, Catherine L; Rutter, Jared; Barondeau, David P

2017-07-03

In eukaryotes, sulfur is mobilized for incorporation into multiple biosynthetic pathways by a cysteine desulfurase complex that consists of a catalytic subunit (NFS1), LYR protein (ISD11), and acyl carrier protein (ACP). This NFS1-ISD11-ACP (SDA) complex forms the core of the iron-sulfur (Fe-S) assembly complex and associates with assembly proteins ISCU2, frataxin (FXN), and ferredoxin to synthesize Fe-S clusters. Here we present crystallographic and electron microscopic structures of the SDA complex coupled to enzyme kinetic and cell-based studies to provide structure-function properties of a mitochondrial cysteine desulfurase. Unlike prokaryotic cysteine desulfurases, the SDA structure adopts an unexpected architecture in which a pair of ISD11 subunits form the dimeric core of the SDA complex, which clarifies the critical role of ISD11 in eukaryotic assemblies. The different quaternary structure results in an incompletely formed substrate channel and solvent-exposed pyridoxal 5'-phosphate cofactor and provides a rationale for the allosteric activator function of FXN in eukaryotic systems. The structure also reveals the 4'-phosphopantetheine-conjugated acyl-group of ACP occupies the hydrophobic core of ISD11, explaining the basis of ACP stabilization. The unexpected architecture for the SDA complex provides a framework for understanding interactions with acceptor proteins for sulfur-containing biosynthetic pathways, elucidating mechanistic details of eukaryotic Fe-S cluster biosynthesis, and clarifying how defects in Fe-S cluster assembly lead to diseases such as Friedreich's ataxia. Moreover, our results support a lock-and-key model in which LYR proteins associate with acyl-ACP as a mechanism for fatty acid biosynthesis to coordinate the expression, Fe-S cofactor maturation, and activity of the respiratory complexes.

Fabrication of Self-Ordered Nanoporous Alumina with 69-115 nm Interpore Distances in Sulfuric/Oxalic Acid Mixtures by Hard Anodization

NASA Astrophysics Data System (ADS)

Almasi Kashi, Mohammad; Ramazani, Abdolali; Mayamai, Yashar; Noormohammadi, Mohammad

2010-01-01

Well-ordered nanoporous arrays have been obtained using hard anodization of aluminium in oxalic/sulfuric mixture. Various ordered nanoporous alumina films with pore intervals from 69 to 115 nm were fabricated on aluminum by high current anodization approach with various sulfuric concentrations in the oxalic/sulfuric mixture electrolyte under 36-60 V. The sulfuric acid concentration was changed from 0.06 to 0.2 M. Different configurations of the current-time curve are seen to influence the self-ordering of the nanohole arrays. A current density-time curve with exponential oscillating decay configuration is seen to damage the self-ordered array of the nanopores while those with exponential decay under certain conditions cause ordered nanopore arrays. For each electrolyte mixture, the interpore distance was dependent upon the anodization voltages with proportionality constants of almost 2 nm V-1. The porosity of the samples (about 3.5%) follows the porosity rule of HA. Final anodization and increasing voltage rate (rin) as a function of sulfuric acid concentration are the main sources to influence the self-ordering of the samples.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Daniel P.; Nicora, Carrie D.; Carini, Paul

The alphaproteobacterium “CandidatusPelagibacter ubique” strain HTCC1062 and most other members of the SAR11 clade lack genes for assimilatory sulfate reduction, making them dependent on organosulfur compounds that occur naturally in seawater. To investigate how these cells adapt to sulfur limitation, batch cultures were grown in defined medium containing either limiting or nonlimiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured before, during, and after the transition from exponential growth to stationary phase. Two distinct responses were observed, one as DMSP became exhausted and another as the cells acclimated to a sulfur-limited environment. Themore » first response was characterized by increased transcription and translation of all “Ca. Pelagibacter ubique” genes downstream from the previously confirmedS-adenosyl methionine (SAM) riboswitchesbhmT,mmuM, andmetY. The proteins encoded by these genes were up to 33 times more abundant as DMSP became limiting. Their predicted function is to shunt all available sulfur to methionine. The secondary response, observed during sulfur-limited stationary phase, was a 6- to 10-fold increase in the transcription of the hemecshuttle-encoding geneccmCand two small genes of unknown function (SAR11_1163andSAR11_1164). This bacterium’s strategy for coping with sulfur stress appears to be intracellular redistribution to support methionine biosynthesis rather than increasing organosulfur import. Many of the genes and SAM riboswitches involved in this response are located in a hypervariable genome region (HVR). One of these HVR genes,ordL, is located downstream from a conserved motif that evidence suggests is a novel riboswitch. IMPORTANCE“Ca. Pelagibacter ubique” is a key driver of marine biogeochemistry cycles and a model for understanding how minimal genomes evolved in free-living anucleate organisms. This study explores the unusual sulfur acquisition strategy that has evolved in these cells, which lack assimilatory sulfate reduction and instead rely on reduced sulfur compounds found in oxic marine environments to meet their cellular quotas. Our findings demonstrate that the sulfur acquisition systems are constitutively expressed but the enzymatic steps leading to the essential sulfur-containing amino acid methionine are regulated by a unique array of riboswitches and genes, many of which are encoded in a rapidly evolving genome region. These findings support mounting evidence that streamlined cells have evolved regulatory mechanisms that minimize transcriptional switching and, unexpectedly, localize essential sulfur acquisition genes in a genome region normally associated with adaption to environmental variation.« less

Pro-inflammatory cytokines among individuals with skin findings long-term after sulfur mustard exposure: Sardasht-Iran Cohort Study.

PubMed

Moin, Athar; Khamesipour, Ali; Hassan, Zuhair Mohammad; Ebtekar, Massoumeh; Davoudi, Seyyed-Masoud; Vaez-Mahdavi, Mohammad-Reza; Soroush, Mohammad-Reza; Faghihzadeh, Soghrat; Naghizadeh, Mohammad-Mehdi; Ghazanfari, Tooba

2013-11-01

Sulfur mustard (SM) is a potent alkylating vesicant warfare chemical agent which causes severe damages to the interface organs, skin, lungs and eyes. The most common chronic skin lesions are mustard scars, xerosis, eczema, seborrheic dermatitis, cherry angioma and hyperpigmentation. This study is part of Sardasht-Iran Cohort Study (SICS) which was performed to compare the serum levels of inflammatory cytokines in SM-exposed individuals (n=372) with long-term relevant skin findings versus unexposed controls (n=128). Serum levels of pro-inflammatory cytokines including IL-1α, IL-1β, IL-1Ra, IL-6, and TNF (tumor necrosis factor) were titrated using ELISA method, 79.9% (n=290) of the exposed group and 60.5% (n=98) of the control group showed skin findings. In the exposed group, 52.1% (n=189) had only skin findings (OSFE) and in the control group, 32% (n=41) had no problem (NC, normal). Median serum levels of cytokines IL-1α, IL-1β, IL-1Ra, IL-6 and TNF-α in the OSFE group were: 1.077, 1.745, 25.640, 0.602 and 12.768 pg/ml, respectively. These values in normal controls were 1.889, 1.896, 32.190, 1.022 and 23.786 pg/ml, respectively which are higher than the corresponding values in the OSFE group, the differences were statistically significant only for IL-1α and TNF-α. This may be due to a damage incurred upon precursors of cytokine producing cells or failure of their functions, increase in suppressive mediators or other mechanisms which are not well known. More studies are needed in molecular dimensions of the immune and cytokine responses in the SM-exposed patients. Copyright © 2013 Elsevier B.V. All rights reserved.

Single-Cell Genome and Group-Specific dsrAB Sequencing Implicate Marine Members of the Class Dehalococcoidia (Phylum Chloroflexi) in Sulfur Cycling

PubMed Central

Cooper, Myriel; Schreiber, Lars; Lloyd, Karen G.; Baker, Brett J.; Petersen, Dorthe G.; Jørgensen, Bo Barker; Stepanauskas, Ramunas; Reinhardt, Richard; Schramm, Andreas; Loy, Alexander; Adrian, Lorenz

2016-01-01

ABSTRACT The marine subsurface sediment biosphere is widely inhabited by bacteria affiliated with the class Dehalococcoidia (DEH), phylum Chloroflexi, and yet little is known regarding their metabolisms. In this report, genomic content from a single DEH cell (DEH-C11) with a 16S rRNA gene that was affiliated with a diverse cluster of 16S rRNA gene sequences prevalent in marine sediments was obtained from sediments of Aarhus Bay, Denmark. The distinctive gene content of this cell suggests metabolic characteristics that differ from those of known DEH and Chloroflexi. The presence of genes encoding dissimilatory sulfite reductase (Dsr) suggests that DEH could respire oxidized sulfur compounds, although Chloroflexi have never been implicated in this mode of sulfur cycling. Using long-range PCR assays targeting DEH dsr loci, dsrAB genes were amplified and sequenced from various marine sediments. Many of the amplified dsrAB sequences were affiliated with the DEH Dsr clade, which we propose equates to a family-level clade. This provides supporting evidence for the potential for sulfite reduction by diverse DEH species. DEH-C11 also harbored genes encoding reductases for arsenate, dimethyl sulfoxide, and halogenated organics. The reductive dehalogenase homolog (RdhA) forms a monophyletic clade along with RdhA sequences from various DEH-derived contigs retrieved from available metagenomes. Multiple facts indicate that this RdhA may not be a terminal reductase. The presence of other genes indicated that nutrients and energy may be derived from the oxidation of substituted homocyclic and heterocyclic aromatic compounds. Together, these results suggest that marine DEH play a previously unrecognized role in sulfur cycling and reveal the potential for expanded catabolic and respiratory functions among subsurface DEH. PMID:27143384

Paracatenula, an ancient symbiosis between thiotrophic Alphaproteobacteria and catenulid flatworms

PubMed Central

Gruber-Vodicka, Harald Ronald; Dirks, Ulrich; Leisch, Nikolaus; Stoecker, Kilian; Bulgheresi, Silvia; Heindl, Niels Robert; Horn, Matthias; Lott, Christian; Loy, Alexander; Wagner, Michael; Ott, Jörg

2011-01-01

Harnessing chemosynthetic symbionts is a recurring evolutionary strategy. Eukaryotes from six phyla as well as one archaeon have acquired chemoautotrophic sulfur-oxidizing bacteria. In contrast to this broad host diversity, known bacterial partners apparently belong to two classes of bacteria—the Gamma- and Epsilonproteobacteria. Here, we characterize the intracellular endosymbionts of the mouthless catenulid flatworm genus Paracatenula as chemoautotrophic sulfur-oxidizing Alphaproteobacteria. The symbionts of Paracatenula galateia are provisionally classified as “Candidatus Riegeria galateiae” based on 16S ribosomal RNA sequencing confirmed by fluorescence in situ hybridization together with functional gene and sulfur metabolite evidence. 16S rRNA gene phylogenetic analysis shows that all 16 Paracatenula species examined harbor host species-specific intracellular Candidatus Riegeria bacteria that form a monophyletic group within the order Rhodospirillales. Comparing host and symbiont phylogenies reveals strict cocladogenesis and points to vertical transmission of the symbionts. Between 33% and 50% of the body volume of the various worm species is composed of bacterial symbionts, by far the highest proportion among all known endosymbiotic associations between bacteria and metazoans. This symbiosis, which likely originated more than 500 Mya during the early evolution of flatworms, is the oldest known animal–chemoautotrophic bacteria association. The distant phylogenetic position of the symbionts compared with other mutualistic or parasitic Alphaproteobacteria promises to illuminate the common genetic predispositions that have allowed several members of this class to successfully colonize eukaryote cells. PMID:21709249

Uptake of Small Organic Compounds by Sulfuric Acid Aerosols: Dissolution and Reaction

NASA Technical Reports Server (NTRS)

Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Staton, S. J. R.

2003-01-01

To assess the role of oxygenated volatile organic compounds in the upper troposphere and lower stratosphere, the interactions of a series of small organic compounds with low-temperature aqueous sulfuric acid will be evaluated. The total amount of organic material which may be taken up from the gas phase by dissolution, surface layer formation, and reaction during the particle lifetime will be quantified. Our current results for acetaldehyde uptake on 40 - 80 wt% sulfuric acid solutions will be compared to those of methanol, formaldehyde, and acetone to investigate the relationships between chemical functionality and heterogeneous activity. Where possible, equilibrium uptake will be ascribed to component pathways (hydration, protonation, etc.) to facilitate evaluation of other species not yet studied in low temperature aqueous sulfuric acid.

Major study reveals EEC gas oil desulfurization costs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waller, G.J.; Conrad, M.C.; Cremer, G.

1985-01-21

The interest of the European Economic Community (EEC) Commission in the issue of acid rain has prompted a Concawe working group to make an independent study of the cost of achieving a reduction of average sulfur levels for gas oils consumed in the EEC. The need for desulfurization of gas oils should be seen in the context of their overall contribution to SO/sub 2/ emissions. The removal of sulfur from gas oil is apparently one of the most costly ways to reduce SO/sub 2/ emissions. The overall effect is apparently the smallest. A reduction of 0.1% sulfur for all gasmore » oil produced in the EEC would result in a reduction of only about 140,000 tons/year of sulfur, corresponding to less than 2% of the present total SO/sub 2/ emissions. The cost of the incremental ton of sulfur removed from the gas oil pool increases significantly for lower sulfur specifications. The overall conclusion is that sulfur reduction between 0.43% and 0.2% is comparable in cost to other methods of reducing SO/sub 2/ emissions. For a reduction below 0.2%, excessive costs can be expected and it would be more economical in most cases to consider another means.« less

Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans.

PubMed

Lara, René H; García-Meza, J Viridiana; Cruz, Roel; Valdez-Pérez, Donato; González, Ignacio

2012-08-01

Massive pyrite (FeS₂) electrodes were potentiostatically modified by means of variable oxidation pulse to induce formation of diverse surface sulfur species (S(n)²⁻, S⁰). The evolution of reactivity of the resulting surfaces considers transition from passive (e.g., Fe(1-x )S₂) to active sulfur species (e.g., Fe(1-x )S(2-y ), S⁰). Selected modified pyrite surfaces were incubated with cells of sulfur-oxidizing Acidithiobacillus thiooxidans for 24 h in a specific culture medium (pH 2). Abiotic control experiments were also performed to compare chemical and biological oxidation. After incubation, the attached cells density and their exopolysaccharides were analyzed by confocal laser scanning microscopy (CLMS) and atomic force microscopy (AFM) on bio-oxidized surfaces; additionally, S(n)²⁻/S⁰ speciation was carried out on bio-oxidized and abiotic pyrite surfaces using Raman spectroscopy. Our results indicate an important correlation between the evolution of S(n)²⁻/S⁰ surface species ratio and biofilm formation. Hence, pyrite surfaces with mainly passive-sulfur species were less colonized by A. thiooxidans as compared to surfaces with active sulfur species. These results provide knowledge that may contribute to establishing interfacial conditions that enhance or delay metal sulfide (MS) dissolution, as a function of the biofilm formed by sulfur-oxidizing bacteria.

Optimized synthesis of phosphorothioate oligodeoxyribonucleotides substituted with a 5′-protected thiol function and a 3′-amino group

PubMed Central

Aubert, Yves; Bourgerie, Sylvain; Meunier, Laurent; Mayer, Roger; Roche, Annie-Claude; Monsigny, Michel; Thuong, Nguyen T.; Asseline, Ulysse

2000-01-01

A new deprotection procedure enables a medium scale preparation of phosphodiester and phosphorothioate oligonucleotides substituted with a protected thiol function at their 5′-ends and an amino group at their 3′-ends in good yield (up to 72 OD units/µmol for a 19mer phosphorothioate). Syntheses of 3′-amino-substituted oligonucleotides were carried out on a modified support. A linker containing the thioacetyl moiety was manually coupled in two steps by first adding its phosphoramidite derivative in the presence of tetrazole followed by either oxidation or sulfurization to afford the bis-derivatized oligonucleotide bound to the support. Deprotection was achieved by treating the fully protected oligonucleotide with a mixture of 2,2′-dithiodipyridine and concentrated aqueous ammonia in the presence of phenol and methanol. This procedure enables (i) cleavage of the oligonucleotide from the support, releasing the oligonucleotide with a free amino group at its 3′-end, (ii) deprotection of the phosphate groups and the amino functions of the nucleic bases, as well as (iii) transformation of the 5′-terminal S-acetyl function into a dithiopyridyl group. The bis-derivatized phosphorothioate oligomer was further substituted through a two-step procedure: first, the 3′-amino group was reacted with fluorescein isothiocyanate to yield a fluoresceinylated oligonucleotide; the 5′-dithiopyridyl group was then quantitatively reduced to give a free thiol group which was then substituted by reaction with an Nα-bromoacetyl derivative of a signal peptide containing a KDEL sequence to afford a fluoresceinylated peptide–oligonucleotide conjugate. PMID:10637335

Meteoritic Sulfur Isotopic Analysis

NASA Technical Reports Server (NTRS)

Thiemens, Mark H.

1996-01-01

Funds were requested to continue our program in meteoritic sulfur isotopic analysis. We have recently detected a potential nucleosynthetic sulfur isotopic anomaly. We will search for potential carriers. The documentation of bulk systematics and the possible relation to nebular chemistry and oxygen isotopes will be explored. Analytical techniques for delta(sup 33), delta(sup 34)S, delta(sup 36)S isotopic analysis were improved. Analysis of sub milligram samples is now possible. A possible relation between sulfur isotopes and oxygen was detected, with similar group systematics noted, particularly in the case of aubrites, ureilites and entstatite chondrites. A possible nucleosynthetic excess S-33 has been noted in bulk ureilites and an oldhamite separate from Norton County. High energy proton (approximately 1 GeV) bombardments of iron foils were done to experimentally determine S-33, S-36 spallogenic yields for quantitation of isotopic measurements in iron meteorites. Techniques for measurement of mineral separates were perfected and an analysis program initiated. The systematic behavior of bulk sulfur isotopes will continue to be explored.

The bond rupture force for sulfur chains calculated from quantum chemistry simulations and its relevance to the tensile strength of vulcanized rubber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, David Edward; Barber, John L.

From quantum chemistry simulations using density functional theory, we obtain the total electronic energy of an eight-atom sulfur chain as its end-to-end distance is extended until S–S bond rupture occurs. We find that a sulfur chain can be extended by about 40% beyond its nominally straight conformation, where it experiences rupture at an end-to-end tension of about 1.5 nN. Using this rupture force as the chain failure limit in an explicit polymer network simulation model (EPnet), we predict the tensile failure stress for sulfur crosslinked (vulcanized) natural rubber. Furthermore, quantitative agreement with published experimental data for the failure stress ismore » obtained in these simulations if we assume that only about 30% of the sulfur chains produce viable network crosslinks. Surprisingly, we also find that the failure stress of a rubber network does not scale linearly with the chain failure force limit.« less

Biological iron-sulfur storage in a thioferrate-protein nanoparticle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaccaro, Brian J.; Clarkson, Sonya M.; Holden, James F.

Iron–sulfur clusters are ubiquitous in biology and function in electron transfer and catalysis. We assembled them from iron and cysteine sulfur on protein scaffolds. Iron is typically stored as iron oxyhydroxide, ferrihydrite, encapsulated in 12 nm shells of ferritin, which buffers cellular iron availability. We have characterized IssA, a protein that stores iron and sulfur as thioferrate, an inorganic anionic polymer previously unknown in biology. IssA forms nanoparticles reaching 300 nm in diameter and is the largest natural metalloprotein complex known. It is a member of a widely distributed protein family that includes nitrogenase maturation factors, NifB and NifX. IssAmore » nanoparticles are visible by electron microscopy as electron-dense bodies in the cytoplasm. Purified nanoparticles appear to be generated from 20 nm units containing B 6,400 Fe atoms and B 170 IssA monomers. In support of roles in both iron–sulfur storage and cluster biosynthesis, IssA reconstitutes the [4Fe-4S] cluster in ferredoxin in vitro.« less

Biological iron-sulfur storage in a thioferrate-protein nanoparticle

DOE PAGES

Vaccaro, Brian J.; Clarkson, Sonya M.; Holden, James F.; ...

2017-07-20

Iron–sulfur clusters are ubiquitous in biology and function in electron transfer and catalysis. We assembled them from iron and cysteine sulfur on protein scaffolds. Iron is typically stored as iron oxyhydroxide, ferrihydrite, encapsulated in 12 nm shells of ferritin, which buffers cellular iron availability. We have characterized IssA, a protein that stores iron and sulfur as thioferrate, an inorganic anionic polymer previously unknown in biology. IssA forms nanoparticles reaching 300 nm in diameter and is the largest natural metalloprotein complex known. It is a member of a widely distributed protein family that includes nitrogenase maturation factors, NifB and NifX. IssAmore » nanoparticles are visible by electron microscopy as electron-dense bodies in the cytoplasm. Purified nanoparticles appear to be generated from 20 nm units containing B 6,400 Fe atoms and B 170 IssA monomers. In support of roles in both iron–sulfur storage and cluster biosynthesis, IssA reconstitutes the [4Fe-4S] cluster in ferredoxin in vitro.« less

Archaea S-layer nanotube from a "black smoker" in complex with cyclo-octasulfur (S8 ) rings.

PubMed

McDougall, Matthew; Francisco, Olga; Harder-Viddal, Candice; Roshko, Roy; Meier, Markus; Stetefeld, Jörg

2017-12-01

Elemental sulfur exists primarily as an S80 ring and serves as terminal electron acceptor for a variety of sulfur-fermenting bacteria. Hyperthermophilic archaea from black smoker vents are an exciting research tool to advance our knowledge of sulfur respiration under extreme conditions. Here, we use a hybrid method approach to demonstrate that the proteinaceous cavities of the S-layer nanotube of the hyperthermophilic archaeon Staphylothermus marinus act as a storage reservoir for cyclo-octasulfur S8. Fully atomistic molecular dynamics (MD) simulations were performed and the method of multiconfigurational thermodynamic integration was employed to compute the absolute free energy for transferring a ring of elemental sulfur S8 from an aqueous bath into the largest hydrophobic cavity of a fragment of archaeal tetrabrachion. Comparisons with earlier MD studies of the free energy of hydration as a function of water occupancy in the same cavity of archaeal tetrabrachion show that the sulfur ring is energetically favored over water. © 2017 Wiley Periodicals, Inc.

Thermal stress analysis of sulfur deactivated solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zeng, Shumao; Parbey, Joseph; Yu, Guangsen; Xu, Min; Li, Tingshuai; Andersson, Martin

2018-03-01

Hydrogen sulfide in fuels can deactivate catalyst for solid oxide fuel cells, which has become one of the most critical challenges to stability. The reactions between sulfur and catalyst will cause phase changes, leading to increase in cell polarization and mechanical mismatch. A three-dimensional computational fluid dynamics (CFD) approach based on the finite element method (FEM) is thus used to investigate the polarization, temperature and thermal stress in a sulfur deactivated SOFC by coupling equations for gas-phase species, heat, momentum, ion and electron transport. The results indicate that sulfur in fuels can strongly affect the cell polarization and thermal stresses, which shows a sharp decrease in the vicinity of electrolyte when 10% nickel in the functional layer is poisoned, but they remain almost unchanged even when the poisoned Ni content was increased to 90%. This investigation is helpful to deeply understand the sulfur poisoning effects and also benefit the material design and optimization of electrode structure to enhance cell performance and lifetimes in various hydrocarbon fuels containing impurities.

The bond rupture force for sulfur chains calculated from quantum chemistry simulations and its relevance to the tensile strength of vulcanized rubber

DOE PAGES

Hanson, David Edward; Barber, John L.

2017-11-20

From quantum chemistry simulations using density functional theory, we obtain the total electronic energy of an eight-atom sulfur chain as its end-to-end distance is extended until S–S bond rupture occurs. We find that a sulfur chain can be extended by about 40% beyond its nominally straight conformation, where it experiences rupture at an end-to-end tension of about 1.5 nN. Using this rupture force as the chain failure limit in an explicit polymer network simulation model (EPnet), we predict the tensile failure stress for sulfur crosslinked (vulcanized) natural rubber. Furthermore, quantitative agreement with published experimental data for the failure stress ismore » obtained in these simulations if we assume that only about 30% of the sulfur chains produce viable network crosslinks. Surprisingly, we also find that the failure stress of a rubber network does not scale linearly with the chain failure force limit.« less

Application of Atmospheric Pressure Photoionization H/D-exchange Mass Spectrometry for Speciation of Sulfur-containing Compounds.

PubMed

Acter, Thamina; Kim, Donghwi; Ahmed, Arif; Ha, Ji-Hyoung; Kim, Sunghwan

2017-08-01

Herein we report the observation of atmospheric pressure in-source hydrogen-deuterium exchange (HDX) of thiol group for the first time. The HDX for thiol group was optimized for positive atmospheric pressure photoionization (APPI) mass spectrometry (MS). The optimized HDX-MS was applied for 31 model compounds (thiols, thiophenes, and sulfides) to demonstrate that exchanged peaks were observed only for thiols. The optimized method has been successfully applied to the isolated fractions of sulfur-rich oil samples. The exchange of one and two thiol hydrogens with deuterium was observed in the thiol fraction; no HDX was observed in the other fractions. Thus, the results presented in this study demonstrate that the HDX-MS method using APPI ionization source can be effective for speciation of sulfur compounds. This method has the potential to be used to access corrosion problems caused by thiol-containing compounds. Graphical Abstract ᅟ.

Multi-functional sorbents for the simultaneous removal of sulfur and lead compounds from hot flue gases.

PubMed

Zhao, Yi; Lin, Wen-Chiang

2003-10-01

A multi-functional sorbent is developed for the simultaneous removal of PbCl(2) vapor and sulfur dioxide from the combustion gases. The sorbent is tested in a bench-scale reactor at the temperature of 700 degrees C, using simulated flue gas (SFG) containing controlled amounts of PbCl(2) and SO(2) compounds. The removal characteristics of PbCl(2) and SO(2), individually and in combination, are investigated. The results show that the mechanism of capture by the sorbent is not a simple physical adsorption process but seems to involve a chemical reaction between the Ca-based sorbent and the contaminants from the simulated flue gas. The porous product layer in the case of individual SO(2) sorption is in a molten state at the reaction temperature. In contrast, the combined sorption of lead and sulfur compounds generates a flower-shaped polycrystalline product layer.

Characterization of aromatic organosulfur model compounds relevant to fossil fuels by using atmospheric pressure chemical ionization with CS2 and high-resolution tandem mass spectrometry.

PubMed

Tang, Weijuan; Sheng, Huaming; Jin, Chunfen; Riedeman, James S; Kenttämaa, Hilkka I

2016-04-15

The chemistry of desulfurization involved in processing crude oil is greatly dependent on the forms of sulfur in the oil. Sulfur exists in different chemical bonding environments in fossil fuels, including those in thiophenes and benzothiophenes, thiols, sulfides, and disulfides. In this study, the fragmentation behavior of the molecular ions of 17 aromatic organosulfur compounds with various functionalities was systematically investigated by using high-resolution tandem mass spectrometry. Multiple-stage tandem mass spectrometric experiments were carried out using a linear quadrupole ion trap (LQIT) equipped with an atmospheric pressure chemical ionization (APCI) source. (+)APCI/CS2 was used to generate stable dominant molecular ions for all the compounds studied except for three sulfides that also showed abundant fragment ions. The LQIT coupled with an orbitrap mass spectrometer was used for elemental composition analysis, which facilitated the identification of the neutral molecules lost during fragmentation. The characteristic fragment ions generated in MS(2) and MS(3) experiments provide clues for the chemical bonding environment of sulfur atoms in the examined compounds. Upon collision-induced dissociation (CID), the molecular ions can lose the sulfur atom in a variety of ways, including as S (32 Da), HS(•) (33 Da), H2 S (34 Da), CS (44 Da), (•) CHS (45 Da) and CH2 S (46 Da). These neutral fragments are not only indicative of the presence of sulfur, but also of the type of sulfur present in the compound. Generally, losses of HS(•) and H2 S were found to be associated with compounds containing saturated sulfur functionalities, while losses of S, CS and (•) CHS were more common for heteroaromatic sulfur compounds. High-resolution tandem mass spectrometry with APCI/CS2 ionization is a viable approach to determining the types of organosulfur compounds. It can potentially be applied to analysis of complex mixtures, which is beneficial to improving the desulfurization process of fossil fuels. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Metagenomic evidence for sulfur lithotrophy by Epsilonproteobacteria as the major energy source for primary productivity in a sub-aerial arctic glacial deposit, Borup Fiord Pass.

PubMed

Wright, Katherine E; Williamson, Charles; Grasby, Stephen E; Spear, John R; Templeton, Alexis S

2013-01-01

We combined free enenergy calculations and metagenomic analyses of an elemental sulfur (S(0)) deposit on the surface of Borup Fiord Pass Glacier in the Canadian High Arctic to investigate whether the energy available from different redox reactions in an environment predicts microbial metabolism. Many S, C, Fe, As, Mn, and [Formula: see text] oxidation reactions were predicted to be energetically feasible in the deposit, and aerobic oxidation of S(0) was the most abundant chemical energy source. Small subunit ribosomal RNA (SSU rRNA) gene sequence data showed that the dominant phylotypes were Sulfurovum and Sulfuricurvum, both Epsilonproteobacteria known to be capable of sulfur lithotrophy. Sulfur redox genes were abundant in the metagenome, but sox genes were significantly more abundant than reverse dsr (dissimilatory sulfite reductase)genes. Interestingly, there appeared to be habitable niches that were unoccupied at the depth of genome coverage obtained. Photosynthesis and [Formula: see text] oxidation should both be energetically favorable, but we found few or no functional genes for oxygenic or anoxygenic photosynthesis, or for [Formula: see text] oxidation by either oxygen (nitrification) or nitrite (anammox). The free energy, SSU rRNA gene and quantitative functional gene data are all consistent with the hypothesis that sulfur-based chemolithoautotrophy by Epsilonproteobacteria (Sulfurovum and Sulfuricurvum) is the main form of primary productivity at this site, instead of photosynthesis. This is despite the presence of 24-h sunlight, and the fact that photosynthesis is not known to be inhibited by any of the environmental conditions present. This is the first time that Sulfurovum and Sulfuricurvum have been shown to dominate a sub-aerial environment, rather than anoxic or sulfidic settings. We also found that Flavobacteria dominate the surface of the sulfur deposits. We hypothesize that this aerobic heterotroph uses enough oxygen to create a microoxic environment in the sulfur below, where the Epsilonproteobacteria can flourish.

Metal-Assisted Oxo Atom Addition to an Fe(III) Thiolate.

PubMed

Villar-Acevedo, Gloria; Lugo-Mas, Priscilla; Blakely, Maike N; Rees, Julian A; Ganas, Abbie S; Hanada, Erin M; Kaminsky, Werner; Kovacs, Julie A

2017-01-11

Cysteinate oxygenation is intimately tied to the function of both cysteine dioxygenases (CDOs) and nitrile hydratases (NHases), and yet the mechanisms by which sulfurs are oxidized by these enzymes are unknown, in part because intermediates have yet to be observed. Herein, we report a five-coordinate bis-thiolate ligated Fe(III) complex, [Fe III (S 2 Me2 N 3 (Pr,Pr))] + (2), that reacts with oxo atom donors (PhIO, IBX-ester, and H 2 O 2 ) to afford a rare example of a singly oxygenated sulfenate, [Fe III (η 2 -S Me2 O)(S Me2 )N 3 (Pr,Pr)] + (5), resembling both a proposed intermediate in the CDO catalytic cycle and the essential NHase Fe-S(O) Cys114 proposed to be intimately involved in nitrile hydrolysis. Comparison of the reactivity of 2 with that of a more electron-rich, crystallographically characterized derivative, [Fe III S 2 Me2 N Me N 2 amide (Pr,Pr)] - (8), shows that oxo atom donor reactivity correlates with the metal ion's ability to bind exogenous ligands. Density functional theory calculations suggest that the mechanism of S-oxygenation does not proceed via direct attack at the thiolate sulfurs; the average spin-density on the thiolate sulfurs is approximately the same for 2 and 8, and Mulliken charges on the sulfurs of 8 are roughly twice those of 2, implying that 8 should be more susceptible to sulfur oxidation. Carboxamide-ligated 8 is shown to be unreactive towards oxo atom donors, in contrast to imine-ligated 2. Azide (N 3 - ) is shown to inhibit sulfur oxidation with 2, and a green intermediate is observed, which then slowly converts to sulfenate-ligated 5. This suggests that the mechanism of sulfur oxidation involves initial coordination of the oxo atom donor to the metal ion. Whether the green intermediate is an oxo atom donor adduct, Fe-O═I-Ph, or an Fe(V)═O remains to be determined.

Metagenomic evidence for sulfur lithotrophy by Epsilonproteobacteria as the major energy source for primary productivity in a sub-aerial arctic glacial deposit, Borup Fiord Pass

PubMed Central

Wright, Katherine E.; Williamson, Charles; Grasby, Stephen E.; Spear, John R.; Templeton, Alexis S.

2013-01-01

We combined free enenergy calculations and metagenomic analyses of an elemental sulfur (S0) deposit on the surface of Borup Fiord Pass Glacier in the Canadian High Arctic to investigate whether the energy available from different redox reactions in an environment predicts microbial metabolism. Many S, C, Fe, As, Mn, and NH4+ oxidation reactions were predicted to be energetically feasible in the deposit, and aerobic oxidation of S0 was the most abundant chemical energy source. Small subunit ribosomal RNA (SSU rRNA) gene sequence data showed that the dominant phylotypes were Sulfurovum and Sulfuricurvum, both Epsilonproteobacteria known to be capable of sulfur lithotrophy. Sulfur redox genes were abundant in the metagenome, but sox genes were significantly more abundant than reverse dsr (dissimilatory sulfite reductase)genes. Interestingly, there appeared to be habitable niches that were unoccupied at the depth of genome coverage obtained. Photosynthesis and NH4+ oxidation should both be energetically favorable, but we found few or no functional genes for oxygenic or anoxygenic photosynthesis, or for NH4+ oxidation by either oxygen (nitrification) or nitrite (anammox). The free energy, SSU rRNA gene and quantitative functional gene data are all consistent with the hypothesis that sulfur-based chemolithoautotrophy by Epsilonproteobacteria (Sulfurovum and Sulfuricurvum) is the main form of primary productivity at this site, instead of photosynthesis. This is despite the presence of 24-h sunlight, and the fact that photosynthesis is not known to be inhibited by any of the environmental conditions present. This is the first time that Sulfurovum and Sulfuricurvum have been shown to dominate a sub-aerial environment, rather than anoxic or sulfidic settings. We also found that Flavobacteria dominate the surface of the sulfur deposits. We hypothesize that this aerobic heterotroph uses enough oxygen to create a microoxic environment in the sulfur below, where the Epsilonproteobacteria can flourish. PMID:23626586

Development of the 2007 Chemical Decontaminant Source Document

DTIC Science & Technology

2009-03-01

Chemical Agent Simulant Specific DEM diethyl malonate MeS methyl salicylate PEG200 Polyethylene glycol 200 TEP triethyl phosphate Group 6...simulants • H-agent simulants o Methyl salicylate (MeS) o Chloroethyl phenyl sulfide (CEPS) o Chloroethyl ethyl sulfide (CEES) • VX simulants... Methyl bromide Ethyl phosphonothioic dichloride Sulfur dioxide Methyl chloroformate Ethyl phosphonic dichloride Sulfuric acid Methyl chlorosilane

Normal-phase liquid chromatography retention behavior of polycyclic aromatic sulfur heterocycles and alkyl-substituted polycyclic aromatic sulfur heterocycle isomers on an aminopropyl stationary phase.

PubMed

Wilson, Walter B; Hayes, Hugh V; Sander, Lane C; Campiglia, Andres D; Wise, Stephen A

2018-02-01

Retention indices for 67 polycyclic aromatic sulfur heterocycles (PASHs) and 80 alkyl-substituted PASHs were determined using normal-phase liquid chromatography (NPLC) on an aminopropyl (NH 2 ) stationary phase. The retention behavior of PASH on the NH 2 phase is correlated with the number of aromatic carbon atoms and two structural characteristics have a significant influence on their retention: non-planarity (thickness, T) and the position of the sulfur atom in the bay-region of the structure. Correlations between solute retention on the NH 2 phase and T of PASHs were investigated for three cata-condensed (cata-) PASH isomer groups: (a) 13 four-ring molecular mass (MM) 234 Da cata-PASHs, (b) 20 five-ring MM 284 Da cata-PASHs, and (c) 12 six-ring MM 334 Da cata-PASHs. Correlation coefficients ranged from r = -0.49 (MM 234 Da) to r = -0.65 (MM 334 Da), which were significantly lower than structurally similar PAH isomer groups (r = -0.70 to r = -0.99). The NPLC retention behavior of the PASHs are compared to similar results for PAHs.

Proteomic Analysis of Stationary Phase in the Marine Bacterium "Candidatus Pelagibacter ubique"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowell, S. M.; Norbeck, A. D.; Lipton, M. S.

2008-05-09

The α-proteobacterium ‘Candidatus Pelagibacter ubique’ str. HTCC1062, and most other members of the SAR11 clade, lack genes for assimilatory sulfate reduction, making them dependent on organosulfur compounds that occur naturally in seawater. To investigate how these cells adapt to sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP became exhausted, and another as cells acclimated to a sulfur-limited environment.more » The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. Proteins encoded by these genes were up to 33 times more abundant as DMSP became limiting. Their predicted function is to shunt all available sulfur to methionine. The secondary response, observed during sulfur-depleted stationary phase, was a 6-10 fold increase in transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164). This bacterium's strategy for coping with sulfur stress appears to be intracellular redistribution to support methionine biosynthesis, rather than increasing organosulfur import. Many of the genes and SAM riboswitches involved in this response are located in a hypervariable genome region (HVR). One of these HVR genes, ordL, is located downstream of a conserved motif that evidence suggests is a novel riboswitch.« less

Ultrathin dendrimer-graphene oxide composite film for stable cycling lithium-sulfur batteries.

PubMed

Liu, Wen; Jiang, Jianbing; Yang, Ke R; Mi, Yingying; Kumaravadivel, Piranavan; Zhong, Yiren; Fan, Qi; Weng, Zhe; Wu, Zishan; Cha, Judy J; Zhou, Henghui; Batista, Victor S; Brudvig, Gary W; Wang, Hailiang

2017-04-04

Lithium-sulfur batteries (Li-S batteries) have attracted intense interest because of their high specific capacity and low cost, although they are still hindered by severe capacity loss upon cycling caused by the soluble lithium polysulfide intermediates. Although many structure innovations at the material and device levels have been explored for the ultimate goal of realizing long cycle life of Li-S batteries, it remains a major challenge to achieve stable cycling while avoiding energy and power density compromises caused by the introduction of significant dead weight/volume and increased electrochemical resistance. Here we introduce an ultrathin composite film consisting of naphthalimide-functionalized poly(amidoamine) dendrimers and graphene oxide nanosheets as a cycling stabilizer. Combining the dendrimer structure that can confine polysulfide intermediates chemically and physically together with the graphene oxide that renders the film robust and thin (<1% of the thickness of the active sulfur layer), the composite film is designed to enable stable cycling of sulfur cathodes without compromising the energy and power densities. Our sulfur electrodes coated with the composite film exhibit very good cycling stability, together with high sulfur content, large areal capacity, and improved power rate.

Sulfur Modifications of the Wobble U34 in tRNAs and their Intracellular Localization in Eukaryotic Cells

PubMed Central

Nakai, Yumi; Nakai, Masato; Yano, Takato

2017-01-01

The wobble uridine (U34) of transfer RNAs (tRNAs) for two-box codon recognition, i.e., tRNALysUUU, tRNAGluUUC, and tRNAGlnUUG, harbor a sulfur- (thio-) and a methyl-derivative structure at the second and fifth positions of U34, respectively. Both modifications are necessary to construct the proper anticodon loop structure and to enable them to exert their functions in translation. Thio-modification of U34 (s2U34) is found in both cytosolic tRNAs (cy-tRNAs) and mitochondrial tRNAs (mt-tRNAs). Although l-cysteine desulfurase is required in both cases, subsequent sulfur transfer pathways to cy-tRNAs and mt-tRNAs are different due to their distinct intracellular locations. The s2U34 formation in cy-tRNAs involves a sulfur delivery system required for the biosynthesis of iron-sulfur (Fe/S) clusters and certain resultant Fe/S proteins. This review addresses presumed sulfur delivery pathways for the s2U34 formation in distinct intracellular locations, especially that for cy-tRNAs in comparison with that for mt-tRNAs. PMID:28218716

Sulfur Modifications of the Wobble U34 in tRNAs and their Intracellular Localization in Eukaryotic Cells.

PubMed

Nakai, Yumi; Nakai, Masato; Yano, Takato

2017-02-18

The wobble uridine (U 34 ) of transfer RNAs (tRNAs) for two-box codon recognition, i.e., tRNA Lys UUU , tRNA Glu UUC , and tRNA Gln UUG , harbor a sulfur- (thio-) and a methyl-derivative structure at the second and fifth positions of U 34 , respectively. Both modifications are necessary to construct the proper anticodon loop structure and to enable them to exert their functions in translation. Thio-modification of U 34 (s²U 34 ) is found in both cytosolic tRNAs (cy-tRNAs) and mitochondrial tRNAs (mt-tRNAs). Although l-cysteine desulfurase is required in both cases, subsequent sulfur transfer pathways to cy-tRNAs and mt-tRNAs are different due to their distinct intracellular locations. The s²U 34 formation in cy-tRNAs involves a sulfur delivery system required for the biosynthesis of iron-sulfur (Fe/S) clusters and certain resultant Fe/S proteins. This review addresses presumed sulfur delivery pathways for the s²U 34 formation in distinct intracellular locations, especially that for cy-tRNAs in comparison with that for mt-tRNAs.

In-situ surface science studies of the interaction between sulfur dioxide and two-dimensional palladium loaded-cerium/zirconium mixed metal oxide model catalysts

NASA Astrophysics Data System (ADS)

Romano, Esteban Javier

2005-07-01

Cerium and zirconium oxides are important materials in industrial catalysis. Particularly, the great advances attained in the past 30 years in controlling levels of gaseous pollutants released from internal combustion engines can be attributed to the development of catalysts employing these materials. Unfortunately, oxides of sulfur are known threats to the longevity of many catalytic systems by irreversibly interacting with catalytic materials. In this work, polycrystalline cerium-zirconium mixed-metal-oxide (MMO) solid solutions were synthesized. High resolution x-ray photoelectron spectroscopy (XPS) spectral data was collected and examined for revelation of the surface species that form on these metal oxides after in-situ exposures to sulfur dioxide. The model catalysts were exposed to sulfur dioxide using a custom modified in-situ reaction cell and platen heater. The results of this study demonstrate the formation of sulfate and sulfite surface sulfur species. Temperature and compositional dependencies were displayed, with higher temperatures and ceria molar ratios displaying a larger propensity for forming surface sulfur species. In addition to analysis of sulfur photoemission, the photoemission regions of oxygen, zirconium, and cerium were examined for the materials used in this study before and after the aforementioned treatments with sulfur dioxide. The presence of surface hydroxyl groups was observed and metal oxidation state changes were probed to further enhance the understanding of sulfur dioxide adsorption on the synthesized materials. Palladium loaded mixed-metal oxides were synthesized using a unique solid-state methodology to probe the effect of palladium addition on sulfur dioxide adsorption. The addition of palladium to this model system is shown to have a strong effect on the magnitude of adsorption for sulfur dioxide on some material/exposure condition combinations. Ceria/zirconia sulfite and sulfate species are identified on the palladium-loaded MMO materials with adsorption sites located on the exposed oxide sites.

Sulfur transfer in the distillate fractions of Arabian crude oils under gamma-irradiation

NASA Astrophysics Data System (ADS)

Basfar, Ahmed A.; Soliman, Yasser S.; Alkhuraiji, Turki S.

2017-05-01

Desulfurization of light distillation fractions including gasoline, kerosene and diesel obtained from the four Arabian crude oils (heavy, medium, light and extra light) upon γ-rays irradiation to different doses was investigated. In addition, yields vol%, FTIR analysis, kinematic viscosity and density of all distillation fractions of irradiated crude oils were evaluated. Limited radiation-induced desulfurization of those fractions was observed up to an irradiation dose of 200 kGy. FTIR analysis of those fractions indicates the absence of oxidized sulfur compounds, represented by S=O of sulfone group, indicating that γ-irradiation of the Arabian crude oils at normal conditions does not induce an oxidative desulfurization in those distillation fractions. Radiation-induced sulfur transfer decreases by 28.56% and increases in total sulfur by 16.8% in Arabian extra light oil and Arabian medium crude oil respectively.

Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics

PubMed Central

Llorens-Marès, Tomàs; Yooseph, Shibu; Goll, Johannes; Hoffman, Jeff; Vila-Costa, Maria; Borrego, Carles M; Dupont, Chris L; Casamayor, Emilio O

2015-01-01

Stratified sulfurous lakes are appropriate environments for studying the links between composition and functionality in microbial communities and are potentially modern analogs of anoxic conditions prevailing in the ancient ocean. We explored these aspects in the Lake Banyoles karstic area (NE Spain) through metagenomics and in silico reconstruction of carbon, nitrogen and sulfur metabolic pathways that were tightly coupled through a few bacterial groups. The potential for nitrogen fixation and denitrification was detected in both autotrophs and heterotrophs, with a major role for nitrogen and carbon fixations in Chlorobiaceae. Campylobacterales accounted for a large percentage of denitrification genes, while Gallionellales were putatively involved in denitrification, iron oxidation and carbon fixation and may have a major role in the biogeochemistry of the iron cycle. Bacteroidales were also abundant and showed potential for dissimilatory nitrate reduction to ammonium. The very low abundance of genes for nitrification, the minor presence of anammox genes, the high potential for nitrogen fixation and mineralization and the potential for chemotrophic CO2 fixation and CO oxidation all provide potential clues on the anoxic zones functioning. We observed higher gene abundance of ammonia-oxidizing bacteria than ammonia-oxidizing archaea that may have a geochemical and evolutionary link related to the dominance of Fe in these environments. Overall, these results offer a more detailed perspective on the microbial ecology of anoxic environments and may help to develop new geochemical proxies to infer biology and chemistry interactions in ancient ecosystems. PMID:25575307

Harmful impact on presynaptic glutamate and GABA transport by carbon dots synthesized from sulfur-containing carbohydrate precursor.

PubMed

Borisova, Tatiana; Dekaliuk, Mariia; Pozdnyakova, Natalia; Pastukhov, Artem; Dudarenko, Marina; Borysov, Arsenii; Vari, Sandor G; Demchenko, Alexander P

2017-07-01

Carbon nanoparticles that may be potent air pollutants with adverse effects on human health often contain heteroatoms including sulfur. In order to study in detail their effects on different physiological and biochemical processes, artificially produced carbon dots (CDs) with well-controlled composition that allows fluorescence detection may be of great use. Having been prepared from different types of organic precursors, CDs expose different atoms at their surface suggesting a broad variation of functional groups. Recently, we demonstrated neurotoxic properties of CDs synthesized from the amino acid β-alanine, and it is of importance to analyze whether CDs obtained from different precursors and particularly those exposing sulfur atoms induce similar neurotoxic effects. This study focused on synthesis of CDs from the sulfur-containing precursor thiourea-CDs (TU-CDs) with a size less than 10 nm, their characterization, and neuroactivity assessment. Neuroactive properties of TU-CDs were analyzed based on their effects on the key characteristics of glutamatergic and γ-aminobutyric acid (GABA) neurotransmission in isolated rat brain nerve terminals. It was observed that TU-CDs (0.5-1.0 mg/ml) attenuated the initial velocity of Na + -dependent transporter-mediated uptake and accumulation of L-[ 14 C]glutamate and [ 3 H]GABA by nerve terminals in a dose-dependent manner and increased the ambient level of the neurotransmitters. Starting from the concentration of 0.2 mg/ml, TU-CDs evoked a gradual dose-dependent depolarization of the plasma membrane of nerve terminals measured with the cationic potentiometric dye rhodamine 6G. Within the concentration range of 0.1-0.5 mg/ml, TU-CDs caused an "unphysiological" step-like increase in fluorescence intensity of the рН-sensitive fluorescent dye acridine orange accumulated by synaptic vesicles. Therefore, despite different surface properties and fluorescent features of CDs prepared from different starting materials (thiourea and β-alanine), their principal neurotoxic effects are analogous but displayed at a different level of efficiency. Sulfur-containing TU-CDs exhibit lower effects (by ~30%) on glutamate and GABA transport in the nerve terminals in comparison with sulfur-free β-alanine CDs. Our results suggest considering that an uncontrolled presence of carbon-containing particulate matter in the human environment may pose a toxicity risk for the central nervous system.

Proceedings of a Workshop on Navy Long-Range Deep Ocean Technology: An Assessment of Current Development, Forecasts, and Research Thrusts Held at Washington, DC on September 23-24, 1982,

DTIC Science & Technology

1983-01-01

the Navy. These technologies ini- tially were reviewed in five groups; the technologies were assessed later during the workshop in four sets, two of...sulfur dioxide (LiSO2 ). The latter two systems present safety hazards after discharge.1- 7 Also these systems are already being developed exten- sively...Control The K02 life support system will supply oxygen and, at the same time, remove CO2. One chemical performs the two essential functions of the

Design rules of heteroatom-doped graphene to achieve high performance lithium-sulfur batteries: Both strong anchoring and catalysing based on first principles calculation.

PubMed

Zhang, Lin; Liang, Pei; Shu, Hai B; Man, Xiao L; Du, Xiao Q; Chao, Dong L; Liu, Zu G; Sun, Yu P; Wan, Hou Z; Wang, Hao

2018-06-18

A number of observations have been reported on chemical capture and catalysis of anchoring materials for lithium-sulfur batteries. Here, we propose the design principles for the chemical functioned graphene as an anchor material to realize both strong chemical trapping and catalysis. Through the first principle, the periodic law is calculated from the theory. Seven different co-doping series were investigated, e.g. MN 4 @graphene (M = V, Cr, Mn, Fe, Co, Ni, and Cu). From binding energy, partial density of state, and charge density difference analysis, the FeN 4 and CrN 4 co-doped graphene show good performance for the lithium-sulfur battery from both strong anchoring and catalytic effects. For the most kinds of Li 2 S x (x = 1, 2, 4, 6, 8) absorption, two combinations can be achieved, including S-bonding and Li-bonding. The competition between the MS and the NLi shows the main difference of the co-doped configurations. Moreover, the S-bonding systems have better performance for both moderate chemical trapping and strong catalysis. The binding energies of Li 2 S x and Li decomposed properties considered as the key descriptors for the rational design of lithium-sulfur battery. Lastly, we offer design rules for high performance lithium-sulfur batteries based on the chemical functional graphene materials. Copyright © 2018 Elsevier Inc. All rights reserved.

Sulfur-vacancy-dependent geometric and electronic structure of bismuth adsorbed on Mo S2

NASA Astrophysics Data System (ADS)

Park, Youngsin; Li, Nannan; Lee, Geunsik; Kim, Kwang S.; Kim, Ki-Jeong; Hong, Soon Cheol; Han, Sang Wook

2018-03-01

Through Bi deposition on the single-crystalline Mo S2 surface, we find that the density of the sulfur vacancy is a critical parameter for the growth of the crystalline Bi overlayer or cluster at room temperature. Also, the Mo S2 band structure is significantly modified near Γ due to the orbital hybridization with an adsorbed Bi monolayer. Our experimental observations and analysis in combination with density functional theory calculation suggest the importance of controlling the sulfur vacancy concentration in realizing an exotic quantum phase based on the van der Waals interface of Bi and Mo S2 .

Determination of sulfur in human hair using high resolution continuum source graphite furnace molecular absorption spectrometry and its correlation with total protein and albumin

NASA Astrophysics Data System (ADS)

Ozbek, Nil; Baysal, Asli

2017-04-01

Human hair is a valuable contributor for biological monitoring. It is an information storage point to assess the effects of environmental, nutritional or occupational sources on the body. Human proteins, amino acids or other compounds are among the key components to find the sources of different effects or disorders in the human body. Sulfur is a significant one of these compounds, and it has great affinity to some metals and compounds. This property of the sulfur affects the human health positively or negatively. In this manuscript, sulfur was determined in hair samples of autistic and age-match control group children via molecular absorption of CS using a high-resolution continuum source graphite furnace atomic absorption spectrometer. For this purpose, hair samples were appropriately washed and dried at 75 °C. Then samples were dissolved in microwave digestion using HNO3 for sulfur determination. Extraction was performed with HCl hydrolysation by incubation for 24 h at 110 °C for total protein and albumin determination. The validity of the method for the sulfur determination was tested using hair standard reference materials. The results were in the uncertainty limits of the certified values at 95% confidence level. Finally correlation of sulfur levels of autistic children's hair with their total protein and albumin levels were done.

Transnitrosation of alicyclic N-nitrosamines containing a sulfur atom.

PubMed

Inami, Keiko; Kondo, Sonoe; Ono, Yuta; Saso, Chiharu; Mochizuki, Masataka

2013-12-15

Aromatic and aliphatic nitrosamines are known to transfer a nitrosonium ion to another amine. The transnitrosation of alicyclic N-nitroso compounds generates S-nitrosothiols, which are potential nitric oxide donors in vivo. In this study, certain alicyclic N-nitroso compounds based on non-mutagenic N-nitrosoproline or N-nitrosothioproline were synthesised, and the formation of S-nitrosoglutathione (GSNO) was quantified under acidic conditions. We then investigated the effect of a sulfur atom as the substituent and as a ring component on the GSNO formation. In the presence of thiourea under acidic conditions, GSNO was formed from N-nitrosoproline and glutathione, and an N-nitroso compound containing a sulfur atom and glutathione produced GSNO without thiourea. The quantity of GSNO derived from the reaction of the N-nitrosamines containing a sulfur atom and glutathione was higher than that from the N-nitrosoproline and glutathione plus thiourea. Among the analogues that contained a sulfur atom either in the ring or as a substituent, the thiazolidines produced a slightly higher quantity of GSNO than the analogue with a thioamide group. A compound containing sulfur atoms both in the ring and as a substituent exhibited the highest activity for GSNO formation among the alicyclic N-nitrosamines tested. The results indicate that the intramolecular sulfur atom plays an important role in the transnitrosation via alicyclic N-nitroso compounds to form GSNO. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Sulfur Atoms Adsorbed on Cu(100) at Low Coverage: Characterization and Stability against Complexation

DOE PAGES

Walen, Holly; Liu, Da-Jiang; Oh, Junepyo; ...

2017-08-22

By using scanning tunneling microscopy, we characterize the size and bias-dependent shape of sulfur atoms on Cu(100) at low coverage (below 0.1 monolayers) and low temperature (quenched from 300 to 5 K). Sulfur atoms populate the Cu(100) terraces more heavily than steps at low coverage, but as coverage approaches 0.1 monolayers, close-packed step edges become fully populated, with sulfur atoms occupying sites on top of the step. Density functional theory (DFT) corroborates the preferential population of terraces at low coverage as well as the step adsorption site. In experiment, small regions with p(2 × 2)-like atomic arrangements emerge on themore » terraces as sulfur coverage approaches 0.1 monolayer. Using DFT, a lattice gas model has been developed, and Monte Carlo simulations based on this model have been compared with the observed terrace configurations. A model containing eight pairwise interaction energies, all repulsive, gives qualitative agreement. Experiment shows that atomic adsorbed sulfur is the only species on Cu(100) up to a coverage of 0.09 monolayers. There are no Cu–S complexes. Conversely, prior work has shown that a Cu 2S 3 complex forms on Cu(111) under comparable conditions. On the basis of DFT, this difference can be attributed mainly to stronger adsorption of sulfur on Cu(100) as compared with Cu(111).« less

Interaction of CuS and sulfur in Li-S battery system

DOE PAGES

Sun, Ke; Su, Dong; Zhang, Qing; ...

2015-10-27

Lithium-Sulfur (Li-S) battery has been a subject of intensive research in recent years due to its potential to provide much higher energy density and lower cost than the current state of the art lithiumion battery technology. In this work, we have investigated Cupric Sulfide (CuS) as a capacitycontributing conductive additive to the sulfur electrode in a Li-S battery. Galvanostatic charge/discharge cycling has been used to compare the performance of both sulfur electrodes and S:CuS hybrid electrodes with various ratios. We found that the conductive CuS additive enhanced the utilization of the sulfur cathode under a 1C rate discharge. However, undermore » a C/10 discharge rate, S:CuS hybrid electrodes exhibited lower sulfur utilization in the first discharge and faster capacity decay in later cycles than a pure sulfur electrode due to the dissolution of CuS. The CuS dissolution is found to be the result of strong interaction between the soluble low order polysulfide Li 2S 3 and CuS. As a result, we identified the presence of conductive copper-containing sulfides at the cycled lithium anode surface, which may degrade the effectiveness of the passivation function of the solid-electrolyte-interphase (SEI) layer, accounting for the poor cycling performance of the S:CuS hybrid cells at low rate.« less

Sulfur Atoms Adsorbed on Cu(100) at Low Coverage: Characterization and Stability against Complexation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walen, Holly; Liu, Da-Jiang; Oh, Junepyo

By using scanning tunneling microscopy, we characterize the size and bias-dependent shape of sulfur atoms on Cu(100) at low coverage (below 0.1 monolayers) and low temperature (quenched from 300 to 5 K). Sulfur atoms populate the Cu(100) terraces more heavily than steps at low coverage, but as coverage approaches 0.1 monolayers, close-packed step edges become fully populated, with sulfur atoms occupying sites on top of the step. Density functional theory (DFT) corroborates the preferential population of terraces at low coverage as well as the step adsorption site. In experiment, small regions with p(2 × 2)-like atomic arrangements emerge on themore » terraces as sulfur coverage approaches 0.1 monolayer. Using DFT, a lattice gas model has been developed, and Monte Carlo simulations based on this model have been compared with the observed terrace configurations. A model containing eight pairwise interaction energies, all repulsive, gives qualitative agreement. Experiment shows that atomic adsorbed sulfur is the only species on Cu(100) up to a coverage of 0.09 monolayers. There are no Cu–S complexes. Conversely, prior work has shown that a Cu 2S 3 complex forms on Cu(111) under comparable conditions. On the basis of DFT, this difference can be attributed mainly to stronger adsorption of sulfur on Cu(100) as compared with Cu(111).« less

Sulfur poisoning of Ni/Gadolinium-doped ceria anodes: A long-term study outlining stable solid oxide fuel cell operation

NASA Astrophysics Data System (ADS)

Riegraf, Matthias; Zekri, Atef; Knipper, Martin; Costa, Rémi; Schiller, Günter; Friedrich, K. Andreas

2018-03-01

This work presents an analysis of the long-term behavior of nickel/gadolinium-doped ceria (CGO) anode-based solid oxide fuel cells (SOFC) under sulfur poisoning conditions. A parameter study of sulfur-induced irreversible long-term degradation of commercial, high-performance single cells was carried out at 900 °C for different H2/N2/H2S fuel gas atmospheres, current densities and Ni/CGO anodes. The poisoning periods of the cells varied from 200 to 1500 h. The possibility of stable long-term Ni/CGO anode operation under sulfur exposure is established and the critical operating regime is outlined. Depending on the operating conditions, two degradation phenomena can be observed. Small degradation of the ohmic resistance was witnessed for sulfur exposure times of approximately 1000 h. Moreover, degradation of the anode charge transfer resistance was observed to be triggered by the combination of a small anodic potential step and high sulfur coverage on Ni. The microstructural evolution of altered Ni/CGO anodes was examined post-mortem by means of SEM and FIB/SEM, and is correlated to the anode performance degradation under critical operating conditions, establishing Ni depletion, porosity increase and a tripe phase boundary density decrease in the anode functional layer. It is shown that short-term sulfur poisoning behavior can be used to assess long-term stability.

Refined Sulfur Nanoparticles Immobilized in Metal-Organic Polyhedron as Stable Cathodes for Li-S Battery.

PubMed

Bai, Linyi; Chao, Dongliang; Xing, Pengyao; Tou, Li Juan; Chen, Zhen; Jana, Avijit; Shen, Ze Xiang; Zhao, Yanli

2016-06-15

The lithium-sulfur (Li-S) battery presents a promising rechargeable energy storage technology for the increasing energy demand in a worldwide range. However, current main challenges in Li-S battery are structural degradation and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling, resulting in the corrosion and loss of active materials. Herein, we developed novel hybrids by employing metal-organic polyhedron (MOP) encapsulated PVP-functionalized sulfur nanoparticles (S@MOP), where the active sulfur component was efficiently encapsulated within the core of MOP and PVP as a surfactant was helpful to stabilize the sulfur nanoparticles and control the size and shape of corresponding hybrids during their syntheses. The amount of sulfur embedded into MOP could be controlled according to requirements. By using the S@MOP hybrids as cathodes, an obvious enhancement in the performance of Li-S battery was achieved, including high specific capacity with good cycling stability. The MOP encapsulation could enhance the utilization efficiency of sulfur. Importantly, the structure of the S@MOP hybrids was very stable, and they could last for almost 1000 cycles as cathodes in Li-S battery. Such high performance has rarely been obtained using metal-organic framework systems. The present approach opens up a promising route for further applications of MOP as host materials in electrochemical and energy storage fields.

Calculated and Experimental Vibrational Properties of P700 and the Iron Sulfur Cluster in Photosystem I

NASA Astrophysics Data System (ADS)

Lamichhane, Hari; Hastings, Gary

2009-11-01

Density functional theory (DFT) based vibrational frequency calculations of Fe4S4(SR)4^n- clusters show that the intense iron-sulfur stretching modes lie in the frequency region between 300-400 cm-1. Among them the iron-sulfur ligand (Fe-S^t) stretching modes are more intense and ˜ 30 cm-1 lower in frequency than the iron-sulfur body (Fe-S^b) stretching modes. Calculations in tetrahydrofuran (THF) show that all these iron-sulfur stretching modes of vibration downshift by ˜ 20 cm-1 upon reduction of the molecule. On the other hand, we have not observed any intense bands from chlorophyll a in the frequency region 400 to 320 cm-1 from the calculations. In an attempt to detect modes associated with iron sulfur clusters in PS I we have obtained light induced (P700^+ - P700) FTIR difference spectra for PSI particles from S. 6803 in the far infrared region. We observe difference bands at many frequencies in the 600-300 cm-1 region. Based on our calculations and literature values we claim that the negative bands at 388 cm-1 and 353 cm-1 in the (P700^+ - P700) FTIR difference spectra be assigned to Fe-S^b and Fe-S^t stretching modes of the ground state of the iron-sulfur cluster FB.

Sulfur isotopic constraints from a single enzyme on the cellular to global sulfur cycles

NASA Astrophysics Data System (ADS)

Sim, M. S.; Adkins, J. F.; Sessions, A. L.; Orphan, V. J.; McGlynn, S.

2017-12-01

Since first reported more than a half century ago, sulfur isotope fractionation between sulfate and sulfide has been used as a diagnostic indicator of microbial sulfate reduction, giving added dimensions to the microbial ecological and geochemical studies of the sulfur cycle. A wide range of fractionation has attracted particular attention because it may serve as a potential indicator of environmental or physiological variables such as substrate concentrations or specific respiration rates. In theory, the magnitude of isotope fractionation depends upon the sulfur isotope effect imparted by the involved enzymes and the relative rate of each enzymatic reaction. The former defines the possible range of fractionation quantitatively, while the latter responds to environmental stimuli, providing an underlying rationale for the varying fractionations. The experimental efforts so far have concentrated largely on the latter, the factors affecting the size of fractionation. Recently, however, the direct assessment of intracellular processes emerges as a promising means for the quantitative analysis of microbial sulfur isotope fractionation as a function of environmental or physiological variables. Here, we experimentally determined for the first time the sulfur isotope fractionation during APS reduction, the first reductive step in the dissimilatory sulfate reduction pathway, using the enzyme purified from Desulfovibrio vulgaris Miyazaki. APS reductase carried out the one-step, two-electron reduction of APS to sulfite, without the production of other metabolic intermediates. Nearly identical isotope effects were obtained at two different temperatures, while the rate of APS reduction more than quadrupled with a temperature increase from 20 to 32°C. When placed in context of the linear network model for microbial sulfur isotope fractionation, our finding could provide a new, semi-quantitative constraint on the sulfur cycle at levels from cellular to global.

Gene identification and substrate regulation provide insights into sulfur accumulation during bioleaching with the psychrotolerant acidophile Acidithiobacillus ferrivorans.

PubMed

Liljeqvist, Maria; Rzhepishevska, Olena I; Dopson, Mark

2013-02-01

The psychrotolerant acidophile Acidithiobacillus ferrivorans has been identified from cold environments and has been shown to use ferrous iron and inorganic sulfur compounds as its energy sources. A bioinformatic evaluation presented in this study suggested that Acidithiobacillus ferrivorans utilized a ferrous iron oxidation pathway similar to that of the related species Acidithiobacillus ferrooxidans. However, the inorganic sulfur oxidation pathway was less clear, since the Acidithiobacillus ferrivorans genome contained genes from both Acidithiobacillus ferrooxidans and Acidithiobacillus caldus encoding enzymes whose assigned functions are redundant. Transcriptional analysis revealed that the petA1 and petB1 genes (implicated in ferrous iron oxidation) were downregulated upon growth on the inorganic sulfur compound tetrathionate but were on average 10.5-fold upregulated in the presence of ferrous iron. In contrast, expression of cyoB1 (involved in inorganic sulfur compound oxidation) was decreased 6.6-fold upon growth on ferrous iron alone. Competition assays between ferrous iron and tetrathionate with Acidithiobacillus ferrivorans SS3 precultured on chalcopyrite mineral showed a preference for ferrous iron oxidation over tetrathionate oxidation. Also, pure and mixed cultures of psychrotolerant acidophiles were utilized for the bioleaching of metal sulfide minerals in stirred tank reactors at 5 and 25°C in order to investigate the fate of ferrous iron and inorganic sulfur compounds. Solid sulfur accumulated in bioleaching cultures growing on a chalcopyrite concentrate. Sulfur accumulation halted mineral solubilization, but sulfur was oxidized after metal release had ceased. The data indicated that ferrous iron was preferentially oxidized during growth on chalcopyrite, a finding with important implications for biomining in cold environments.

Gene Identification and Substrate Regulation Provide Insights into Sulfur Accumulation during Bioleaching with the Psychrotolerant Acidophile Acidithiobacillus ferrivorans

PubMed Central

Liljeqvist, Maria; Rzhepishevska, Olena I.

2013-01-01

The psychrotolerant acidophile Acidithiobacillus ferrivorans has been identified from cold environments and has been shown to use ferrous iron and inorganic sulfur compounds as its energy sources. A bioinformatic evaluation presented in this study suggested that Acidithiobacillus ferrivorans utilized a ferrous iron oxidation pathway similar to that of the related species Acidithiobacillus ferrooxidans. However, the inorganic sulfur oxidation pathway was less clear, since the Acidithiobacillus ferrivorans genome contained genes from both Acidithiobacillus ferrooxidans and Acidithiobacillus caldus encoding enzymes whose assigned functions are redundant. Transcriptional analysis revealed that the petA1 and petB1 genes (implicated in ferrous iron oxidation) were downregulated upon growth on the inorganic sulfur compound tetrathionate but were on average 10.5-fold upregulated in the presence of ferrous iron. In contrast, expression of cyoB1 (involved in inorganic sulfur compound oxidation) was decreased 6.6-fold upon growth on ferrous iron alone. Competition assays between ferrous iron and tetrathionate with Acidithiobacillus ferrivorans SS3 precultured on chalcopyrite mineral showed a preference for ferrous iron oxidation over tetrathionate oxidation. Also, pure and mixed cultures of psychrotolerant acidophiles were utilized for the bioleaching of metal sulfide minerals in stirred tank reactors at 5 and 25°C in order to investigate the fate of ferrous iron and inorganic sulfur compounds. Solid sulfur accumulated in bioleaching cultures growing on a chalcopyrite concentrate. Sulfur accumulation halted mineral solubilization, but sulfur was oxidized after metal release had ceased. The data indicated that ferrous iron was preferentially oxidized during growth on chalcopyrite, a finding with important implications for biomining in cold environments. PMID:23183980

Sulfation of ceria-zirconia model automotive emissions control catalysts

NASA Astrophysics Data System (ADS)

Nelson, Alan Edwin

Cerium-zirconium mixed metal oxides are used in automotive emissions control catalysts to regulate the partial pressure of oxygen near the catalyst surface. The near surface oxygen partial pressure is regulated through transfer of atomic oxygen from the ceria-zirconia solid matrix to the platinum group metals to form metal oxides capable of oxidizing carbon monoxide and unburned hydrocarbons. Although the addition of zirconium in the cubic lattice of ceria increases the oxygen storage capacity and thermal stability of the ceria matrix, the cerium-zirconium oxide system remains particularly susceptible to deactivation from sulfur compounds. While the overall effect of sulfur on these systems is understood (partially irreversible deactivation), the fundamental and molecular interaction of sulfur with ceria-zirconia remains a challenging problem. Ceria-zirconia metal oxide solid solutions have been prepared through co-precipitation with nitrate precursors. The prepared powders were calcined and subsequently formed into planer wafers and characterized for chemical and physical attributes. The prepared samples were subsequently exposed to a sulfur dioxide based environment and characterized with spectroscopic techniques to characterize the extent of sulfation and the nature of surface sulfur species. The extent of sulfation of the model ceria-zirconia systems was characterized with Auger electron spectroscopy (AES) prior to and after treatment in a microreactor. Strong dependencies were observed between the atomic ratio of ceria to zirconia and the extent of sulfation. In addition, the partial pressure of sulfur dioxide during treatments also correlated to the extent of sulfation, while temperature only slightly effected the extent of sulfation. The AES data suggests the gas phase sulfur dioxide preferentially chemisorbs on surface ceria atoms and the extent of sulfation is heavily dependent on sulfur dioxide concentrations and only slightly dependent on catalyst temperatures, as confirmed by thermal programmed desorption (TPD). While hydrogen exposure indicated slight sulfur removal, exposure to a redox environment or atmosphere nearly eliminated the quantity of chemisorbed surface sulfur. The nature of sulfur removal is attributed to the inherent redox properties of ceria-zirconia systems. The complete analysis provides mechanistic insight into sulfation dependencies and fundamental information regarding sulfur adsorption on ceria-zirconia model automotive emissions control systems.

Evolution of sulfur speciation in bitumen through hydrous pyrolysis induced thermal maturation of Jordanian Ghareb Formation oil shale

USGS Publications Warehouse

Birdwell, Justin E.; Lewan, Michael; Bake, Kyle D.; Bolin, Trudy B.; Craddock, Paul R.; Forsythe, Julia C.; Pomerantz, Andrew E.

2018-01-01

Previous studies on the distribution of bulk sulfur species in bitumen before and after artificial thermal maturation using various pyrolysis methods have indicated that the quantities of reactive (sulfide, sulfoxide) and thermally stable (thiophene) sulfur moieties change following consistent trends under increasing thermal stress. These trends show that sulfur distributions change during maturation in ways that are similar to those of carbon, most clearly illustrated by the increase in aromatic sulfur (thiophenic) as a function of thermal maturity. In this study, we have examined the sulfur moiety distributions of retained bitumen from a set of pre- and post-pyrolysis rock samples in an organic sulfur-rich, calcareous oil shale from the Upper Cretaceous Ghareb Formation. Samples collected from outcrop in Jordan were subjected to hydrous pyrolysis (HP). Sulfur speciation in extracted bitumens was examined using K-edge X-ray absorption near-edge structure (XANES) spectroscopy. The most substantial changes in sulfur distribution occurred at temperatures up to the point of maximum bitumen generation (∼300 °C) as determined from comparison of the total organic carbon content for samples before and after extraction. Organic sulfide in bitumen decreased with increasing temperature at relatively low thermal stress (200–300 °C) and was not detected in extracts from rocks subjected to HP at temperatures above around 300 °C. Sulfoxide content increased between 200 and 280 °C, but decreased at higher temperatures. The concentration of thiophenic sulfur increased up to 300 °C, and remained essentially stable under increasing thermal stress (mg-S/g-bitumen basis). The ratio of stable-to-reactive+stable sulfur moieties ([thiophene/(sulfide+sulfoxide+thiophene)], T/SST) followed a sigmoidal trend with HP temperature, increasing slightly up to 240 °C, followed by a substantial increase between 240 and 320 °C, and approaching a constant value (∼0.95) at temperatures above 320 °C. This sulfur moiety ratio appears to provide complementary thermal maturity information to geochemical parameters derived from other analyses of extracted source rocks.

Molecular evidence for biodegradation of geomacromolecules

NASA Astrophysics Data System (ADS)

Jenisch-Anton, A.; Adam, P.; Michaelis, W.; Connan, J.; Herrmann, D.; Rohmer, M.; Albrecht, P.

2000-10-01

The biodegradability of macromolecular organic structures of geological origin was investigated by performing in vitro studies. Cultures of the common Nocardioides simplex were grown, first, on a high molecular weight, asymmetric thioether (1-(phytanylsulfanyl)-octadecane 1) and then on macromolecular fractions isolated from a sulfur-rich oil. Gross data indicate that bacteria convert macromolecular substances to material of higher polarity by oxidizing the abundant thioethers to sulfones and sulfoxides and by introducing new functionalities, such as carboxylic acid, keto or hydroxyl groups. Furthermore, bacteria remineralize the macromolecular structures. Bacterially induced alterations were also studied on a molecular level after chemical desulfurization of the macromolecular structure. Thus, it could be established that the amounts of linear hydrocarbons in the macromolecular structure are decreased relative to branched and cyclic structures due to a preferential bacterial attack of the linear moieties bound to the macromolecules. This is further supported by the detection of S-bound fatty acids resulting from the bacterial oxidation of S-bound n-alkanes. Moreover, N. simplex also degraded sulfur-bound steranes by oxidation of the steroid side-chain leading to S-bound steroid acids.

Insights into the single cell draft genome of "Candidatus Achromatium palustre".

PubMed

Salman, Verena; Berben, Tom; Bowers, Robert M; Woyke, Tanja; Teske, Andreas; Angert, Esther R

2016-01-01

"Candidatus Achromatium palustre" was recently described as the first marine representative of the Achromatium spp. in the Thiotrichaceae - a sister lineage to the Chromatiaceae in the Gammaproteobacteria. Achromatium spp. belong to the group of large sulfur bacteria as they can grow to nearly 100 μm in size and store elemental sulfur (S(0)) intracellularly. As a unique feature, Achromatium spp. can accumulate colloidal calcite (CaCO3) inclusions in great amounts. Currently, both process and function of calcite accumulation in bacteria is unknown, and all Achromatium spp. are uncultured. Recently, three single-cell draft genomes of Achromatium spp. from a brackish mineral spring were published, and here we present the first draft genome of a single "Candidatus Achromatium palustre" cell collected in the sediments of the Sippewissett Salt Marsh, Cape Cod, MA. Our draft dataset consists of 3.6 Mbp, has a G + C content of 38.1 % and is nearly complete (83 %). The next closest relative to the Achromatium spp. genomes is Thiorhodovibrio sp. 907 of the family Chromatiaceae, containing phototrophic sulfide-oxidizing bacteria.

Insights into the single cell draft genome of “ Candidatus Achromatium palustre”

DOE PAGES

Salman, Verena; Berben, Tom; Bowers, Robert M.; ...

2016-03-23

" Candidatus Achromatium palustre" was recently described as the first marine representative of the Achromatium spp. in the Thiotrichaceae - a sister lineage to the Chromatiaceae in the Gammaproteobacteria. Achromatium spp. belong to the group of large sulfur bacteria as they can grow to nearly 100 mu m in size and store elemental sulfur (S-0) intracellularly. As a unique feature, Achromatium spp. can accumulate colloidal calcite (CaCO 3) inclusions in great amounts. Currently, both process and function of calcite accumulation in bacteria is unknown, and all Achromatium spp. are uncultured. Recently, three single-cell draft genomes of Achromatium spp. from amore » brackish mineral spring were published, and here we present the first draft genome of a single " Candidatus Achromatium palustre" cell collected in the sediments of the Sippewissett Salt Marsh, Cape Cod, MA. Our draft dataset consists of 3.6 Mbp, has a G + C content of 38.1 % and is nearly complete (83 %). In conclusion, the next closest relative to the Achromatium spp. genomes is Thiorhodovibrio sp. 907 of the family Chromatiaceae, containing phototrophic sulfide-oxidizing bacteria.« less

Sulfate-Dependent Repression of Genes That Function in Organosulfur Metabolism in Bacillus subtilis Requires Spx

PubMed Central

Erwin, Kyle N.; Nakano, Shunji; Zuber, Peter

2005-01-01

Oxidative stress in Bacillus subtilis results in the accumulation of Spx protein, which exerts both positive and negative transcriptional control over a genome-wide scale through its interaction with the RNA polymerase α subunit. Previous microarray transcriptome studies uncovered a unique class of genes that are controlled by Spx-RNA polymerase interaction under normal growth conditions that do not promote Spx overproduction. These genes were repressed by Spx when sulfate was present as a sole sulfur source. The genes include those of the ytmI, yxeI, and ssu operons, which encode products resembling proteins that function in the uptake and desulfurization of organic sulfur compounds. Primer extension and analysis of operon-lacZ fusion expression revealed that the operons are repressed by sulfate and cysteine; however, Spx functioned only in sulfate-dependent repression. Both the ytmI operon and the divergently transcribed ytlI, encoding a LysR-type regulator that positively controls ytmI operon transcription, are repressed by Spx in sulfate-containing media. The CXXC motif of Spx, which is necessary for redox sensitive control of Spx activity in response to oxidative stress, is not required for sulfate-dependent repression. The yxeL-lacZ and ssu-lacZ fusions were also repressed in an Spx-dependent manner in media containing sulfate as the sole sulfur source. This work uncovers a new role for Spx in the control of sulfur metabolism in a gram-positive bacterium under nonstressful growth conditions. PMID:15937167

Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

NASA Astrophysics Data System (ADS)

Shi, Qihua; Zhang, Yimin; Liu, Tao; Huang, Jing

2018-01-01

Fluorides are widely used to improve vanadium extraction from shale in China. Sulfuric acid baking-leaching (SABL) was investigated as a means of recovering vanadium which does not require the use of fluorides and avoids the productions of harmful fluoride-containing wastewater. Various effective factors were systematically studied and the experimental results showed that 90.1% vanadium could be leached from the shale. On the basis of phase transformations and structural changes after baking the shale, a mechanism of vanadium extraction from shale via SABL was proposed. The mechanism can be described as: (1) sulfuric acid diffusion into particles; (2) the formation of concentrated sulfuric acid media in the particles after water evaporation; (3) hydroxyl groups in the muscovite were removed and transient state [SO4 2-] was generated; and (4) the metals in the muscovite were sulfated by active [SO4 2-] and the vanadium was released. Thermodynamics modeling confirmed this mechanism.

Experimental Determination of Sulfur Partition Ratio in the CaO-Al2O3-SiO2-CaF2-MgO Slag and Liquid Iron

NASA Astrophysics Data System (ADS)

Jinzhu, Z.; Yunsheng, Y.; Wei, F.; Jialiang, Z.; Yi, Z.

2017-09-01

The external desulphurization of molten iron has become an important step in the production of steel and iron. The desulfurization degree of the high calcium slag, which was mainly taken from Shougang Shuicheng Iron and Steel (Group) Co. Limited, was investigated on basis of the fundamental theory of slag metal equilibrium reaction. The initial content of sulfur in the slag was adjusted to 2.60% mass perdent by adding analytical reagent CaS. The results show that the desulfurization degree of the high calcium slag increases obviously with the increase of temperature in the range 1593-1743K, and so the sulfur partition ratio. When the holding time of the hot metal and slag at controlled temperature was extended from 120 min to 180 min in the furnace, both the sulfur partition ratio and the desulfurization degree increased markedly.

Facile Formation of Acetic Sulfuric Anhydride in a Supersonic Jet: Characterization by Microwave Spectroscopy and Computational Chemistry

NASA Astrophysics Data System (ADS)

Huff, Anna; Smith, CJ; Mackenzie, Becca; Leopold, Ken

2017-06-01

Sulfur trioxide and acetic acid are shown to react under supersonic jet conditions to form acetic sulfuric anhydride, CH_{3}COOSO_{2}OH. Rotational spectra of the parent, ^{34}S, methyl ^{13}C, and fully deuterated isotopologues have been observed by chirped-pulse and conventional cavity microwave spectroscopy. A and E internal rotation states have been observed for each isotopologue studied and the methyl group internal rotation barriers have been determined (241.043(65) \\wn for the parent species). The reaction is analogous to that of our previous report on the reaction of sulfur trioxide and formic acid. DFT and CCSD calculations are also presented which indicate that the reaction proceeds via a π_{2} + π_{2} + σ_{2} cycloaddition reaction. These results support our previous conjecture that the reaction of SO_{3} with carboxylic acids is both facile and general. Possible implications for atmospheric aerosol formation are discussed.

Coaxial Carbon/MnO2 Hollow Nanofibers as Sulfur Hosts for High-Performance Lithium-Sulfur Batteries.

PubMed

Ni, Lubin; Zhao, Gangjin; Wang, Yanting; Wu, Zhen; Wang, Wei; Liao, Yunyun; Yang, Guang; Diao, Guowang

2017-12-14

Lithium-sulfur (Li-S) batteries have recently attracted a large amount of attention as promising candidates for next-generation high-power energy storage devices because of their high theoretical capacity and energy density. However, the shuttle effect of polysulfides and poor conductivity of sulfur are still vital issues that constrain their specific capacity and cyclic stability. Here, we design coaxial MnO 2 -graphitic carbon hollow nanofibers as sulfur hosts for high-performance lithium-sulfur batteries. The hollow C/MnO 2 coaxial nanofibers are synthesized via electrospinning and carbonization of the carbon nanofibers (CNFs), followed by an in situ redox reaction to grow MnO 2 nanosheets on the surface of CNFs. The inner graphitic carbon layer not only maintains intimate contact with sulfur and outer MnO 2 shell to significantly increase the overall electrical conductivity but also acts as a protective layer to prevent dissolution of polysulfides. The outer MnO 2 nanosheets restrain the shuttle effect greatly through chemisorption and redox reaction. Therefore, the robust S@C/MnO 2 nanofiber cathode delivers an extraordinary rate capability and excellent cycling stability with a capacity decay rate of 0.044 and 0.051 % per cycle after 1000 cycles at 1.0 C and 2.0 C, respectively. Our present work brings forward a new facile and efficient strategy for the functionalization of inorganic metal oxide on graphitic carbons as sulfur hosts for high performance Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High capacity of lithium-sulfur batteries at low electrolyte/sulfur ratio enabled by an organosulfide containing electrolyte

DOE PAGES

Chen, Shuru; Gao, Yue; Yu, Zhaoxin; ...

2016-11-30

We present that lithium-sulfur (Li-S) battery is a promising energy storage technology to replace lithium ion batteries for higher energy density and lower cost. Dissolution of lithium polysulfide intermediates in conventional Li-S electrolytes is known as one of the key technical barriers to the development of Li-S, because it promotes redistribution and irreversible deposition of Li 2S, and also forces large amounts of electrolyte to be used, shortening cycling life and driving down cell energy density. Recently, dimethyl disulfide as a functional co-solvent has been demonstrated to show an alternate electrochemical reaction pathway for sulfur cathodes by the formation ofmore » dimethyl polysulfides and lithium organosulfides as intermediates and reduction products. In this work, comprehensive studies show that this new pathway not only provides high capacity but also enables excellent capacity retention through a built-in automatic discharge shutoff mechanism by tuning carbon/sulfur ratio in sulfur cathodes to reduce unfavorable Li 2S formation. Furthermore, this new electrolyte system is also found to enable high capacity of high-sulfur-loading cathodes with low electrolyte/sulfur (E/S) ratios, such as a stable specific capacity of around 1000 mAh g -1 using a low electrolyte amount (i.e, E/S ratio of 5 mL g -1) and highsulfur-loading (4 mg cm -2) cathodes. This electrolyte system almost doubles the capacity obtained with conventional electrolytes under the same harsh conditions. In conclusion, these results highlight the practical potential of this electrolyte system to enable high-energy-density Li-S batteries.« less

Chemical species of sulfur in prostate cancer cells studied by XANES spectroscopy

NASA Astrophysics Data System (ADS)

Czapla, Joanna; Kwiatek, Wojciech M.; Lekki, Janusz; Dulińska-Litewka, Joanna; Steininger, Ralph; Göttlicher, Jörg

2013-12-01

The role of sulfur in prostate cancer progression may be significant for understanding the process of carcinogenesis. This work, based on X-ray Absorption Near Edge Structure (XANES) spectroscopy, is focused on determination of sulfur chemical species occurring in prostate cancer cell lines. The experimental material consisted of four commercially available cell lines: three from metastasized prostate cancer (PC3, LNCaP, and DU145) and one, used as a control, from the non-tumourigenic peripheral zone of the prostate (PZ-HPV-7). The experiment was performed at the SUL-X beamline of the synchrotron radiation source ANKA, Karlsruhe (Germany). The K-edge XANES spectra of sulfur were analyzed by deconvolution in order to establish sulfur species that occur in prostate cancer cells and to find out whether there are any differences in their content between various cell lines. Experimental spectra were fitted in two ways: with two Gaussian peaks and one arctangent step function, and additionally by a Linear Combination Fit with spectra of reference compounds in order to obtain quantitative chemical information. All fitting procedures were performed with the Athena code (Ravel and Newville, 2005) and the results of deconvolution were used to determine the fraction of each sulfur form. The results of data analysis showed that cell lines from different metastasis had different ratio of reduced to oxidized sulfur species. The LCF analysis demonstrated that the highest content of GSH, one of the most important sulfur-bearing compounds in cells, was observed in DU145 cells. These findings may confirm the hypothesis of changes in redox balance in case of cancer initiation and progression.

High capacity of lithium-sulfur batteries at low electrolyte/sulfur ratio enabled by an organosulfide containing electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shuru; Gao, Yue; Yu, Zhaoxin

We present that lithium-sulfur (Li-S) battery is a promising energy storage technology to replace lithium ion batteries for higher energy density and lower cost. Dissolution of lithium polysulfide intermediates in conventional Li-S electrolytes is known as one of the key technical barriers to the development of Li-S, because it promotes redistribution and irreversible deposition of Li 2S, and also forces large amounts of electrolyte to be used, shortening cycling life and driving down cell energy density. Recently, dimethyl disulfide as a functional co-solvent has been demonstrated to show an alternate electrochemical reaction pathway for sulfur cathodes by the formation ofmore » dimethyl polysulfides and lithium organosulfides as intermediates and reduction products. In this work, comprehensive studies show that this new pathway not only provides high capacity but also enables excellent capacity retention through a built-in automatic discharge shutoff mechanism by tuning carbon/sulfur ratio in sulfur cathodes to reduce unfavorable Li 2S formation. Furthermore, this new electrolyte system is also found to enable high capacity of high-sulfur-loading cathodes with low electrolyte/sulfur (E/S) ratios, such as a stable specific capacity of around 1000 mAh g -1 using a low electrolyte amount (i.e, E/S ratio of 5 mL g -1) and highsulfur-loading (4 mg cm -2) cathodes. This electrolyte system almost doubles the capacity obtained with conventional electrolytes under the same harsh conditions. In conclusion, these results highlight the practical potential of this electrolyte system to enable high-energy-density Li-S batteries.« less

Decomposition mechanism of chromite in sulfuric acid-dichromic acid solution

NASA Astrophysics Data System (ADS)

Zhao, Qing; Liu, Cheng-jun; Li, Bao-kuan; Jiang, Mao-fa

2017-12-01

The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly understood. In this work, binary spinels of Mg-Al, Mg-Fe, and Mg-Cr in the powdered and lump states were synthesized and used as raw materials to investigate the decomposition mechanism of chromite in sulfuric acid-dichromic acid solution. The leaching yields of metallic elements and the changes in morphology of the spinel were studied. The experimental results showed that the three spinels were stable in sulfuric acid solution and that dichromic acid had little influence on the decomposition behavior of the Mg-Al spinel and Mg-Fe spinel because Mg2+, Al3+, and Fe3+ in spinels cannot be oxidized by Cr6+. However, in the case of the Mg-Cr spinel, dichromic acid substantially promoted the decomposition efficiency and functioned as a catalyst. The decomposition mechanism of chromite in sulfuric acid-dichromic acid solution was illustrated on the basis of the findings of this study.

A natural carbonized leaf as polysulfide diffusion inhibitor for high-performance lithium-sulfur battery cells.

PubMed

Chung, Sheng-Heng; Manthiram, Arumugam

2014-06-01

Attracted by the unique tissue and functions of leaves, a natural carbonized leaf (CL) is presented as a polysulfide diffusion inhibitor in lithium-sulfur (Li-S) batteries. The CL that is covered on the pure sulfur cathode effectively suppresses the polysulfide shuttling mechanism and enables the use of pure sulfur as the cathode. A low charge resistance and a high discharge capacity of 1320 mA h g(-1) arise from the improved cell conductivity due to the innately integral conductive carbon network of the CL. The unique microstructure of CL leads to a high discharge/charge efficiency of >98 %, low capacity fade of 0.18 % per cycle, and good long-term cyclability over 150 cycles. The structural gradient and the micro/mesoporous adsorption sites of CL effectively intercept/trap the migrating polysulfides and facilitate their reutilization. The green CL polysulfide diffusion inhibitor thus offers a viable approach for developing high-performance lithium-sulfur batteries. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metaproteomics reveals differential modes of metabolic coupling among ubiquitous oxygen minimum zone microbes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawley, Alyse K.; Brewer, Heather M.; Norbeck, Angela D.

2014-08-05

Oxygen minimum zones (OMZs) are intrinsic water column features arising from respiratory oxygen demand during organic matter degradation in stratified marine waters. Currently OMZs are expanding due to global climate change. This expansion alters marine ecosystem function and the productivity of fisheries due to habitat compression and changes in biogeochemical cycling leading to fixed nitrogen loss and greenhouse gas production. Here we use metaproteomics to chart spatial and temporal patterns of gene expression along defined redox gradients in a seasonally anoxic fjord, Saanich Inlet to better understand microbial community responses to OMZ expansion. The expression of metabolic pathway components formore » nitrification, anaerobic ammonium oxidation (anammox), denitrification and inorganic carbon fixation predominantly co-varied with abundance and distribution patterns of Thaumarchaeota, Nitrospira, Planctomycetes and SUP05/ARCTIC96BD-19 Gammaproteobacteria. Within these groups, pathways mediating inorganic carbon fixation and nitrogen and sulfur transformations were differentially expressed across the redoxcline. Nitrification and inorganic carbon fixation pathways affiliated with Thaumarchaeota dominated dysoxic waters and denitrification, sulfur-oxidation and inorganic carbon fixation pathways affiliated with SUP05 dominated suboxic and anoxic waters. Nitrite-oxidation and anammox pathways affiliated with Nitrospina and Planctomycetes respectively, also exhibited redox partitioning between dysoxic and suboxic waters. The differential expression of these pathways under changing water column redox conditions has quantitative implications for coupled biogeochemical cycling linking different modes of inorganic carbon fixation with distributed nitrogen and sulfur-based energy metabolism extensible to coastal and open ocean OMZs.« less

Tangled web of interactions among proteins involved in iron–sulfur cluster assembly as unraveled by NMR, SAXS, chemical crosslinking, and functional studies☆

PubMed Central

Kim, Jin Hae; Bothe, Jameson R.; Alderson, T. Reid; Markley, John L.

2014-01-01

Proteins containing iron–sulfur (Fe–S) clusters arose early in evolution and are essential to life. Organisms have evolved machinery consisting of specialized proteins that operate together to assemble Fe–S clusters efficiently so as to minimize cellular exposure to their toxic constituents: iron and sulfide ions. To date, the best studied system is the iron sulfur cluster (isc) operon of Escherichia coli, and the eight ISC proteins it encodes. Our investigations over the past five years have identified two functional conformational states for the scaffold protein (IscU) and have shown that the other ISC proteins that interact with IscU prefer to bind one conformational state or the other. From analyses of the NMR spectroscopy-derived network of interactions of ISC proteins and small-angle X-ray scattering (SAXS), chemical crosslinking experiments, and functional assays, we have constructed working models for Fe–S cluster assembly and delivery. Future work is needed to validate and refine what has been learned about the E. coli system and to extend these findings to the homologous Fe–S cluster biosynthetic machinery of yeast and human mitochondria. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases. PMID:25450980

Effects of exposure to sulfur mustard on speech aerodynamics.

PubMed

Heydari, Fatemeh; Ghanei, Mostafa

2011-01-01

Sulfur mustard is an alkylating agent with highly cytotoxic properties even at low exposure. It was used widely against both military and civilian population by Iraqi forces in the Iraq-Iran war (1983-1988). Although various aspects of mustard gas effects on patients with chemical injury have been relatively well characterized, its effects on speech are still evolving. We evaluated aerodynamics of speech in male patients following sulfur mustard inhalation. In a case-control study patients with chemical injuries (n=19) along with age and sex-matched healthy control group (n=20) were selected. Aerodynamic analyses were performed by using the Glasgow Airflow Measurement System (known as ST1 dysphonia). Results indicated that except mean flow rate, there were statistically significant differences in vital capacity, phonation time, phonation volume, vocal velocity index, total expired volume and phonation quotient of patients between experimental and control groups (P<0.05). This study demonstrated mustard gas can impair different parameters of speech aerodynamics. As a result of this activity, the reader will be able to describe: (1) the evaluation of air flow in relation to speech system dysfunction and efficiency; (2) the effect of sulfur mustard known as mustard gas on respiratory physiology. Copyright © 2011 Elsevier Inc. All rights reserved.

Comparison of topical capsaicin and betamethasone in the treatment of chronic skin lesions due to sulfur mustard exposure.

PubMed

Panahi, Yunes; Davoudi, Seyyed Masoud; Moharamzad, Yashar; Beiraghdar, Fatemeh; Naghizadeh, Mohammad Mehdi

2008-01-01

Chronic pruritic skin lesions are considered to be one of the late complications of sulfur mustard exposure. The purpose of this study was to compare the efficacy of topical capsaicin with that of betamethasone in the treatment of these lesions. In this investigator-blinded, randomized clinical trial, patients applied capsaicin cream 0.025% (n=32) or betamethasone cream 0.1% (n=32) 2 times a day for 6 weeks. Efficacy was based on a dermatologist assessment. The severity of the pruritus was assessed by pruritic score questionnaire and a visual analog scale before and after treatment. All patients complained of pruritus. Both groups showed a significant decrease in pruritus, scaling, and skin dryness (p<0.05), but burning sensation was not improved significantly in the capsaicin group. The mean (+/- standard deviation [SD]) baseline pruritic scores in the capsaicin and betamethasone groups were 29.4 (13.1) and 33.6 (7.2), respectively (p=0.1). The mean (SD) pruritus score change from baseline to after the treatment was significantly higher (p<0.001) in the betamethasone group than in the capsaicin group, 12.7 (6.4) vs. 6.9 (5.6). Fourteen (35%) patients in the capsaicin group reported a burning sensation and intolerable odor, but these effects were not serious enough to necessitate discontinuing the treatment. Topical capsaicin cream 0.025% was much less well tolerated than betamethasone and inferior to betamethasone in reducing chronic skin lesions and symptoms from sulfur mustard exposure.

Density functional theory with van der waals corrections study of the adsorption of alkyl, alkylthiol, alkoxyl, and amino-alkyl chains on the H:Si(111) surface.

PubMed

Arefi, Hadi H; Nolan, Michael; Fagas, Giorgos

2014-11-11

Surface modification of silicon with organic monolayers tethered to the surface by different linkers is an important process in realizing future miniaturized electronic and sensor devices. Understanding the roles played by the nature of the linking group and the chain length on the adsorption structures and stabilities of these assemblies is vital to advance this technology. This paper presents a density functional theory (DFT) study of the hydrogen passivated Si(111) surface modified with alkyl chains of the general formula H:Si-(CH2)n-CH2 and H:Si-X-(CH2)n-CH3, where X = NH, O, S and n = (0, 1, 3, 5, 7, 9, 11), at half coverage. For (X)-hexane and (X)-dodecane functionalization, we also examined various coverages up to full monolayer grafting in order to validate the result of half covered surface and the linker effect on the coverage. We find that it is necessary to take into account the van der Waals interaction between the alkyl chains. The strongest binding is for the oxygen linker, followed by S, N, and C, irrespective of chain length. The result revealed that the sequence of the stability is independent of coverage; however, linkers other than carbon can shift the optimum coverage considerably and allow further packing density. For all linkers apart from sulfur, structural properties, in particular, surface-linker-chain angles, saturate to a single value once n > 3. For sulfur, we identify three regimes, namely, n = 0-3, n = 5-7, and n = 9-11, each with its own characteristic adsorption structures. Where possible, our computational results are shown to be consistent with the available experimental data and show how the fundamental structural properties of modified Si surfaces can be controlled by the choice of linking group and chain length.

High covalence in CuSO4 and the radicalization of sulfate: an X-ray absorption and density functional study.

PubMed

Szilagyi, Robert K; Frank, Patrick; DeBeer George, Serena; Hedman, Britt; Hodgson, Keith O

2004-12-27

Sulfur K-edge X-ray absorption spectroscopy (XAS) of anhydrous CuSO(4) reveals a well-resolved preedge transition feature at 2478.8 eV that has no counterpart in the XAS spectra of anhydrous ZnSO(4) or copper sulfate pentahydrate. Similar but weaker preedge features occur in the sulfur K-edge XAS spectra of [Cu(itao)SO(4)] (2478.4 eV) and [Cu[(CH(3))(6)tren]SO(4)] (2477.7 eV). Preedge features in the XAS spectra of transition metal ligands are generally attributed to covalent delocalization of a metal d-orbital hole into a ligand-based orbital. Copper L-edge XAS of CuSO(4) revealed that 56% of the Cu(II) 3d hole is delocalized onto the sulfate ligand. Hybrid density functional calculations on the two most realistic models of the covalent delocalization pathways in CuSO(4) indicate about 50% electron delocalization onto the sulfate oxygen-based 2p orbitals; however, at most 14% of that can be found on sulfate sulfur. Both experimental and computational results indicated that the high covalence of anhydrous CuSO(4) has made sulfate more like the radical monoanion, inducing an extensive mixing and redistribution of sulfur 3p-based unoccupied orbitals to lower energy in comparison to sulfate in ZnSO(4). It is this redistribution, rather than a direct covalent interaction between Cu(II) and sulfur, that is the origin of the observed sulfur XAS preedge feature. From pseudo-Voigt fits to the CuSO(4) sulfur K-edge XAS spectrum, a ground-state 3p character of 6% was quantified for the orbital contributing to the preedge transition, in reasonable agreement with the DFT calculation. Similar XAS fits indicated 2% sulfur 3p character for the preedge transition orbitals in [Cu(itao)SO(4)] and [Cu[(CH(3))(6)tren]SO(4)]. The covalent radicalization of ligands similar to sulfate, with consequent energy redistribution of the virtual orbitals, represents a new mechanism for the induction of ligand preedge XAS features. The high covalence of the Cu sites in CuSO(4) was found to be similar to that of Cu sites in oxidized cupredoxins, including its anistropic nature, and can serve as the simplest inorganic examples of intramolecular electron-transfer processes.

Investigations of the electron field emission properties and microstructure correlation in sulfur-incorporated nanocrystalline carbon thin films

NASA Astrophysics Data System (ADS)

Gupta, S.; Weiner, B. R.; Morell, G.

2002-06-01

Results are reported on the electron field emission properties of sulfur (S)-incorporated nanocrystalline carbon (n-C:S) thin films grown on molybdenum (Mo) substrates by hot-filament chemical vapor deposition (HFCVD) technique. In addition to the conventionally used methane (CH4) as carbon precursor with high hydrogen (H2) dilution, hydrogen sulfide-hydrogen (H2)S/H2 premix gas was used for sulfur incorporation. The field emission properties for the S-incorporated films were investigated systematically as a function of substrate temperature (TS) and sulfur concentration. Lowest turn-on field achieved was observed at around 4.0 V/mum for the n-C:S sample grown at TS of 900 degC with 500 ppm of H2S. These results are compared with those films grown without sulfur (n-C) at a particular TS. The turn-on field was found to be almost half for the S-assisted film thus demonstrating the effect of sulfur addition to the chemical vapor deposition process. An inverse relation between turn-on field (EC), growth temperature and sulfur concentration was found. The S incorporation also causes significant microstructural changes, as characterized with non-destructive complementary ex situ techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy (RS). S-assisted films show relatively smoother and finer-grained surfaces than those grown without it. These findings are discussed in terms of the dual role of sulfur in enhancing the field emission properties by controlling the sp2 C cluster size and introducing substantial structural defects through its incorporation. The in-plane correlation length (La) of sp2 C cluster was determined from the intensity ratio of the D- and G-bands I(D)/I(G) in the visible RS as a function of deposition temperature and sulfur concentration using a phenomenological model. The turn-on field was found to decrease with increasing sp2 C cluster size in general ranging from 0.8 to 1.4 nm. The films having sp2 C clusters of around 1.4 nm had the lowest turn-on field and steep rising emission currents, providing an estimate of optimum size for La for the material grown hereby. These findings are assessed in terms of a reduced field emission barrier brought about by the sulfur addition and the need for relatively longer conductive paths capable of withstanding the relatively large emission currents. It is because the sp2 C cluster size predominate the chemical environment, chemical order, sp3 content or local conductivity. Besides, although most of the S is expected to be electrically inactive, under the high doping conditions (larger S/C) hereby employed, there may be some amount of S in donor states, an indication of the availability of conduction electrons. These results also suggest that the behaviors of sulfur-incorporated nanocrystalline carbon thin films are closer to that grown with phosphorus (P) and Nitrogen (N) elements.

Adaptability as the key to success for the ubiquitous marine nitrite oxidizer Nitrococcus

PubMed Central

Füssel, Jessika; Lücker, Sebastian; Yilmaz, Pelin; Nowka, Boris; van Kessel, Maartje A. H. J.; Bourceau, Patric; Hach, Philipp F.; Littmann, Sten; Berg, Jasmine; Spieck, Eva; Daims, Holger; Kuypers, Marcel M. M.; Lam, Phyllis

2017-01-01

Nitrite-oxidizing bacteria (NOB) have conventionally been regarded as a highly specialized functional group responsible for the production of nitrate in the environment. However, recent culture-based studies suggest that they have the capacity to lead alternative lifestyles, but direct environmental evidence for the contribution of marine nitrite oxidizers to other processes has been lacking to date. We report on the alternative biogeochemical functions, worldwide distribution, and sometimes high abundance of the marine NOB Nitrococcus. These largely overlooked bacteria are capable of not only oxidizing nitrite but also reducing nitrate and producing nitrous oxide, an ozone-depleting agent and greenhouse gas. Furthermore, Nitrococcus can aerobically oxidize sulfide, thereby also engaging in the sulfur cycle. In the currently fast-changing global oceans, these findings highlight the potential functional switches these ubiquitous bacteria can perform in various biogeochemical cycles, each with distinct or even contrasting consequences. PMID:29109973

Fluorine and sulfur simultaneously co-doped suspended graphene

NASA Astrophysics Data System (ADS)

Struzzi, C.; Sezen, H.; Amati, M.; Gregoratti, L.; Reckinger, N.; Colomer, J.-F.; Snyders, R.; Bittencourt, C.; Scardamaglia, M.

2017-11-01

Suspended graphene flakes are exposed simultaneously to fluorine and sulfur ions produced by the μ-wave plasma discharge of the SF6 precursor gas. The microscopic and spectroscopic analyses, performed by Raman spectroscopy, scanning electron microscopy and photoelectron spectromicroscopy, show the homogeneity in functionalization yield over the graphene flakes with F and S atoms covalently bonded to the carbon lattice. This promising surface shows potential for several applications ranging from biomolecule immobilization to lithium battery and hydrogen storage devices. The present co-doping process is an optimal strategy to engineer the graphene surface with a concurrent hydrophobic character, thanks to the fluorine atoms, and a high affinity with metal nanoparticles due to the presence of sulfur atoms.

Sulfur as a Signaling Nutrient Through Hydrogen Sulfide

PubMed Central

Kabil, Omer; Vitvitsky, Victor; Banerjee, Ruma

2015-01-01

Hydrogen sulfide (H2S) has emerged as an important signaling molecule with beneficial effects on various cellular processes affecting, for example, cardiovascular and neurological functions. The physiological importance of H2S is motivating efforts to develop strategies for modulating its levels. However, advancement in the field of H2S-based therapeutics is hampered by fundamental gaps in our knowledge of how H2S is regulated, its mechanism of action, and its molecular targets. This review provides an overview of sulfur metabolism; describes recent progress that has shed light on the mechanism of H2S as a signaling molecule; and examines nutritional regulation of sulfur metabolism, which pertains to health and disease. PMID:25033061

Full potential calculations on the electron bandstructures of Sphalerite, Pyrite and Chalcopyrite

NASA Astrophysics Data System (ADS)

Edelbro, R.; Sandström, Å.; Paul, J.

2003-02-01

The bulk electronic structures of Sphalerite, Pyrite and Chalcopyrite have been calculated within an ab initio, full potential, density functional approach. The exchange term was approximated with the Dirac exchange functional, the Vosko-Wilk-Nusair parameterization of the Cepler-Alder free electron gas was used for correlation and linear combinations of Gaussian type orbitals were used as basis functions. The Sphalerite (zinc blende) band gap was calculated to be direct with a width of 2.23 eV. The Sphalerite valence band was 5.2 eV wide and composed of a mixture of sulfur and zinc orbitals. The band below the valence band located around -6.2 eV was mainly composed of Zn 3d orbitals. The S 3s orbitals gave rise to a band located around -12.3 eV. Pyrite was calculated to be a semiconductor with an indirect band gap of 0.51 eV, and a direct gap of 0.55 eV. The valence band was 1.25 eV wide and mainly composed of non-bonding Fe 3d orbitals. The band below the valence band was 4.9 eV wide and composed of a mixture of sulfur and iron orbitals. Due to the short inter-atomic distance between the sulfur dumbbells, the S 3s orbitals in Pyrite were split into a bonding and an anti-bonding range. Chalcopyrite was predicted to be a conductor, with no band-crossings at the Fermi level. The bands at -13.2 eV originate from the sulfur 3s orbitals and were quite similar to the sulfur 3s bands in Sphalerite, though somewhat shifted to lower energy. The top of the valence band consisted of a mixture of orbitals from all the atoms. The lower part of the same band showed metal character. Computational modeling as a tool for illuminating the flotation and leaching processes of Pyrite and Chalcopyrite, in connection with surface science experiments, is discussed.

Probing Ligand Effects on the Redox Energies of [4Fe-4S] Clusters Using Broken-Symmetry Density Functional Theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Shuqiang; Ichiye, Toshiko

A central issue in understanding redox properties of iron-sulfur proteins is determining the factors that tune the reduction potentials of the Fe-S clusters. Recently, Solomon and coworkers have shown that the Fe-S bond covalency of protein analogs measured by %L, the percent ligand character of the Fe 3d orbitals, from ligand K-edge X-ray absorption spectroscopy (XAS) correlates with the electrochemical redox potentials. Also, Wang and coworkers have measured electron detachment energies for iron-sulfur clusters without environmental perturbations by gas-phase photoelectron spectroscopy (PES). Here the correlations of the ligand character with redox energy and %L character are examined in [Fe₄S₄L₄]2⁻ clustersmore » with different ligands by broken symmetry density functional theory (BS-DFT) calculations using the B3LYP functional together with PES and XAS experimental results. These gas-phase studies assess ligand effects independently of environmental perturbations and thus provide essential information for computational studies of iron-sulfur proteins. The B3LYP oxidation energies agree well with PES data, and the %L character obtained from natural bond orbital analysis correlates with XAS values, although it systematically underestimates them because of basis set effects. The results show that stronger electron-donating terminal ligands increase %Lt, the percent ligand character from terminal ligands, but decrease %Sb, the percent ligand character from the bridging sulfurs. Because the oxidized orbital has significant Fe-Lt antibonding character, the oxidation energy correlates well with %Lt. However, because the reduced orbital has varying contributions of both Fe-Lt and Fe-Sb antibonding character, the reduction energy does not correlate with either %Lt or %Sb. Overall, BSDFT calculations together with XAS and PES experiments can unravel the complex underlying factors in the redox energy and chemical bonding of the [4Fe-4S] clusters in iron-sulfur proteins.« less

Bias-dependent oscillatory electron transport of monatomic sulfur chains

NASA Astrophysics Data System (ADS)

Yu, Jing-Xin; Cheng, Yan; Sanvito, Stefano; Chen, Xiang-Rong

2012-03-01

The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green's function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients.

Soft Cysteine Signaling Network: The Functional Significance of Cysteine in Protein Function and the Soft Acids/Bases Thiol Chemistry That Facilitates Cysteine Modification.

PubMed

Wible, Ryan S; Sutter, Thomas R

2017-03-20

The unique biophysical and electronic properties of cysteine make this molecule one of the most biologically critical amino acids in the proteome. The defining sulfur atom in cysteine is much larger than the oxygen and nitrogen atoms more commonly found in the other amino acids. As a result of its size, the valence electrons of sulfur are highly polarizable. Unique protein microenvironments favor the polarization of sulfur, thus increasing the overt reactivity of cysteine. Here, we provide a brief overview of the endogenous generation of reactive oxygen and electrophilic species and specific examples of enzymes and transcription factors in which the oxidation or covalent modification of cysteine in those proteins modulates their function. The perspective concludes with a discussion of cysteine chemistry and biophysics, the hard and soft acids and bases model, and the proposal of the Soft Cysteine Signaling Network: a hypothesis proposing the existence of a complex signaling network governed by layered chemical reactivity and cross-talk in which the chemical modification of reactive cysteine in biological networks triggers the reorganization of intracellular biochemistry to mitigate spikes in endogenous or exogenous oxidative or electrophilic stress.

Preparation of redox polymer cathodes for thin film rechargeable batteries

DOEpatents

Skotheim, T.A.; Lee, H.S.; Okamoto, Yoshiyuki.

1994-11-08

The present invention relates to the manufacture of thin film solid state electrochemical devices using composite cathodes comprising a redox polymer capable of undergoing oxidation and reduction, a polymer solid electrolyte and conducting carbon. The polymeric cathode material is formed as a composite of radiation crosslinked polymer electrolytes and radiation crosslinked redox polymers based on polysiloxane backbones with attached organosulfur side groups capable of forming sulfur-sulfur bonds during electrochemical oxidation.

Reduced activities of thiamine-dependent and cytochrome c oxidase enzymes in cerebral cortex of cattle affected by sulfur-induced polioencephalomalacia

PubMed Central

Amat, Samat; Hendrick, Steve; Moshynskyy, Igor; Simko, Elemir

2017-01-01

Sulfur-induced polioencephalomalacia (PEM) is an important disease affecting cattle in certain geographical regions. However, the pathogenesis of brain damage is not completely understood. We previously observed that excess dietary sulfur may influence thiamine status and altered thiamine metabolism may be involved in the pathogenesis of sulfur-induced PEM in cattle. In this study, we evaluated the activities of thiamine-dependent enzymes [α-ketogluterate dehydrogenase (α-KGDH) and pyruvate dehydrogenase (PDH)] and cytochrome c oxidase (COX) in the cerebral cortex of sulfur-induced PEM-affected cattle (n = 9) and clinically normal cattle (n = 8, each group) exposed to low or high dietary sulfur [LS = 0.30% versus HS = 0.67% sulfur on a dry matter (DM) basis]. Enzyme activities in PEM brains were measured from the brain tissue regions and examined using ultraviolent (UV) light illumination to show fluorescence or non-fluorescence regions. No gross changes under regular or UV light, or histopathological changes indicative of PEM were detected in the brains of cattle exposed to LS or HS diets. The PDH, α-KGDH, and COX activities did not differ between LS and HS brains, but all enzymes showed significantly lower (P < 0.05) activities in UV-positive region of PEM brains compared with LS and HS brains. The UV-negative regions of PEM brain had similar PDH activities to LS and HS brains, but the activities of α-KGDH and COX were significantly lower than in LS and HS brains. The results of this study suggest that reduced enzyme activities of brain PHD, α-KGDH, and COX are associated with the pathogenesis of sulfur-induced PEM. PMID:29081580

Inversion of chalcogen defect levels in silicon - An MNDO study. [modified neglect of diatomic overlap

NASA Technical Reports Server (NTRS)

Singh, R. K.; Sahu, S. N.; Singh, V. A.; Corbett, J. W.

1985-01-01

MNDO (modified neglect of diatomic overlap) calculations have been carried out for substitutional oxygen and sulfur impurities in silicon. The calculations of the gap levels reveal a reversal of trend with atomic ionization energies in agreement with self-consistent Green function results, and analysis of the MNDO charge distribution supports the view that the electronegativity difference between oxygen and sulfur gives rise to this shallower energy level.

Imaging of irradiated liver with Tc-99m-sulfur colloid and Tc-99m-IDA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gelfand, M.J.; Saha, S.; Aron, B.S.

1981-09-01

In three cases, irradiated regions of liver failed to concentrate Tc-99m-sulfur colloid. In two of these three, imaging with Tc-99m-acetanilide iminodiacetic acid (IDA) agents within five days showed near normal hepatic uptake of this hepatobiliary imaging agent. The hepatic parenchymal cells may be imaged with Tc-99m-IDA in some irradiated regions of liver, despite loss of reticuloendothelial cell function.

[Acute poisoning by chemical warfare agent: sulfur mustard].

PubMed

Mérat, S; Perez, J P; Rüttimann, M; Bordier, E; Lienhard, A; Lenoir, B; Pats, B

2003-02-01

To review story, mechanism of action, clinical and therapeutic bases of a sulfur mustard poisoning, by accidental, terrorism or war exposure. References were obtained from computerised bibliographic research (Medline), from personnel data (academic memoir, documents under approbation of the National Defense Office) and from the Library of Military Medical Service. Sulfur mustard is a chemical warfare agent with peace time results: leak, accidental handling, acts of terrorism. Sulfur mustard is a vesicant agent, an organochlorine agent, who alkylate DNA. Under liquid or gas form its main target are skin and lungs. Clinical effects are like burns with loss of immunity, with respiratory failure, ophthalmic, gastrointestinal and haematological signs. The last studies have improved knowledge about the mechanism of action, detection, protection and treatment. Methods for determination of sulfur mustard are based on gas chromatographic method and mass spectrometry. During sulfur mustard contamination the first priorities of treatment are to remove victims from the contaminated place and to initiate decontamination. Emergency workers and materials must take protection to avoid secondary contamination of emergency unit. With treatment of vital functions and respiratory failure, the new ways of treatment are about N-acetyl cysteine for lung injury, poly (ADP-ribose) polymerase inhibitors, calmodulin antagonists and Ca(++) chelators. Interactions between sulfur mustard and anaesthetic agents are not well known and are based on clinical observations. Emergency care unit can be confronted with sulfur mustard during accidental contamination or acts of terrorism. First and most efficacy priorities of treatment are to remove and to decontaminate victims. New means of detection and treatment are studied since several years but are not still appropriate to human victims or mass treatment.

Human frataxin activates Fe-S cluster biosynthesis by facilitating sulfur transfer chemistry.

PubMed

Bridwell-Rabb, Jennifer; Fox, Nicholas G; Tsai, Chi-Lin; Winn, Andrew M; Barondeau, David P

2014-08-05

Iron-sulfur clusters are ubiquitous protein cofactors with critical cellular functions. The mitochondrial Fe-S assembly complex, which consists of the cysteine desulfurase NFS1 and its accessory protein (ISD11), the Fe-S assembly protein (ISCU2), and frataxin (FXN), converts substrates l-cysteine, ferrous iron, and electrons into Fe-S clusters. The physiological function of FXN has received a tremendous amount of attention since the discovery that its loss is directly linked to the neurodegenerative disease Friedreich's ataxia. Previous in vitro results revealed a role for human FXN in activating the cysteine desulfurase and Fe-S cluster biosynthesis activities of the Fe-S assembly complex. Here we present radiolabeling experiments that indicate FXN accelerates the accumulation of sulfur on ISCU2 and that the resulting persulfide species is viable in the subsequent synthesis of Fe-S clusters. Additional mutagenesis, enzyme kinetic, UV-visible, and circular dichroism spectroscopic studies suggest conserved ISCU2 residue C104 is critical for FXN activation, whereas C35, C61, and C104 are all essential for Fe-S cluster formation on the assembly complex. These results cannot be fully explained by the hypothesis that FXN functions as an iron donor for Fe-S cluster biosynthesis, and further support an allosteric regulator role for FXN. Together, these results lead to an activation model in which FXN accelerates persulfide formation on NFS1 and favors a helix-to-coil interconversion on ISCU2 that facilitates the transfer of sulfur from NFS1 to ISCU2 as an initial step in Fe-S cluster biosynthesis.

Human Frataxin Activates Fe–S Cluster Biosynthesis by Facilitating Sulfur Transfer Chemistry

PubMed Central

2015-01-01

Iron–sulfur clusters are ubiquitous protein cofactors with critical cellular functions. The mitochondrial Fe–S assembly complex, which consists of the cysteine desulfurase NFS1 and its accessory protein (ISD11), the Fe–S assembly protein (ISCU2), and frataxin (FXN), converts substrates l-cysteine, ferrous iron, and electrons into Fe–S clusters. The physiological function of FXN has received a tremendous amount of attention since the discovery that its loss is directly linked to the neurodegenerative disease Friedreich’s ataxia. Previous in vitro results revealed a role for human FXN in activating the cysteine desulfurase and Fe–S cluster biosynthesis activities of the Fe–S assembly complex. Here we present radiolabeling experiments that indicate FXN accelerates the accumulation of sulfur on ISCU2 and that the resulting persulfide species is viable in the subsequent synthesis of Fe–S clusters. Additional mutagenesis, enzyme kinetic, UV–visible, and circular dichroism spectroscopic studies suggest conserved ISCU2 residue C104 is critical for FXN activation, whereas C35, C61, and C104 are all essential for Fe–S cluster formation on the assembly complex. These results cannot be fully explained by the hypothesis that FXN functions as an iron donor for Fe–S cluster biosynthesis, and further support an allosteric regulator role for FXN. Together, these results lead to an activation model in which FXN accelerates persulfide formation on NFS1 and favors a helix-to-coil interconversion on ISCU2 that facilitates the transfer of sulfur from NFS1 to ISCU2 as an initial step in Fe–S cluster biosynthesis. PMID:24971490

Epidermal hydration and skin surface lipids in patients with long-term complications of sulfur mustard poisoning.

PubMed

Layegh, Pouran; Maleki, Masoud; Mousavi, Seyed Reza; Yousefzadeh, Hadis; Momenzadeh, Akram; Golmohammadzadeh, Shiva; Balali-Mood, Mahdi

2015-07-01

Despite almost the three decades passed since the chemical attacks of Iraqi's army against the Iranian troops, some veterans are still suffering from long-term complications of sulfur mustard (SM) poisoning, including certain skin complaints specially dryness, burning, and pruritus. We thus aimed to evaluate the skin's water and lipid content in patients with a disability of >25% due to complications of SM poisoning and compare them with a matched control group. Sixty-nine male participants were included in this study; 43 SM-exposed patients, and 26 normal controls from their close relatives. The water and lipid content was measured in four different locations: Extensor and flexor sides of forearms and lateral and medial sides of legs by the Corneometer CM 820/Sebumeter SM 810. Collected data was analyzed and P ≤ 0.05 was considered as statistically significant. The mean age of the patients and controls was 49.53 ± 11.34 (ranges: 40-71) and 29.08 ± 8.836 (ranges: 15-49 years), respectively. In the veterans group, the main cutaneous complaint was itching and skin dryness. Cherry angioma, dry skin, and pruritus were significantly more common in the SM-exposed cases than in the controls. (P = 0.01, 0.05, and 0.04, respectively). The moisture and lipid content of all areas were lower in the SM-exposed group, but it was only significant in skin sebum of lateral sides of legs (P = 0.02). Exposure to SM could decrease the function of stratum corneum and lipid production as a barrier, even after several years of its exposure.

C-glycosylation reactions of sulfur-substituted glycosyl donors: evidence against the role of neighboring-group participation.

PubMed

Beaver, Matthew G; Billings, Susan B; Woerpel, K A

2008-02-13

Nucleophilic substitution reactions of C-4 sulfur-substituted tetrahydropyran acetals revealed that neighboring-group participation does not control product formation. Spectroscopic evidence for the formation of an intermediate sulfonium ion is provided, as are data from nucleophilic substitution reactions demonstrating that products are formed from oxocarbenium ion intermediates. The selectivity was not sensitive to solvent or to which Lewis acid was employed. The identity of the heteroatom at the C-4 position also did not significantly impact diastereoselectivity. Consequently, neighboring-group participation was not responsible for the formation of either the major or the minor products. These studies implicate a Curtin-Hammett kinetic scenario in which the formation of a low-energy intermediate does not necessitate its involvement in the product-forming pathway.

Computational study on the effects of substituent and heteroatom on physical properties and solar cell performance in donor-acceptor conjugated polymers based on benzodithiophene.

PubMed

Zhang, Lvyong; Shen, Wei; He, Rongxing; Liu, Xiaorui; Fu, Zhiyong; Li, Ming

2014-11-01

Computationally driven material design has attracted increasing interest to accelerate the search for optimal conjugated donor materials in bulk heterojunction organic solar cells. A series of novel copolymers containing benzo[1,2-b:4,5-b']dithiophene (BDT) and thieno[3,4-c]pyrrole-4,6-dione (TPD) derivatives were simulated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). We performed a systematic study on the influences on molecular geometry parameters, electronic properties, optical properties, photovoltaic performances, and intermolecular stacking as well as hole mobility when different chalcogenophenes in TPD derivatives were used and functional groups with different electron-withdrawing abilities such as alkyl, fluorine, sufonyl, and cyano were introduced to the nitrogen positions in electron-deficient units. The substitution position of electron-withdrawing groups may cause little steric hindrance to the neighboring donor units, especially fluorine and cyano group. It was found that the incorporation of these new electron-deficient substituents and sulfur-selenium exchange can be applicable to further modify and optimize existing molecular structures. Our findings will provide valuable guidance and chemical methodologies for a judicious material design of conjugated polymers for solar cell applications with desirable photovoltaic characteristics.

Bidirectional binding property of high glycine-tyrosine keratin-associated protein contributes to the mechanical strength and shape of hair.

PubMed

Matsunaga, Ryo; Abe, Ryota; Ishii, Daisuke; Watanabe, Shun-Ichi; Kiyoshi, Masato; Nöcker, Bernd; Tsuchiya, Masaru; Tsumoto, Kouhei

2013-09-01

Since their first finding in wool 50years ago, keratin-associated proteins (KAPs), which are classified into three groups; high sulfur (HS) KAPs, ultra high sulfur (UHS) KAPs, and high glycine-tyrosine (HGT) KAPs, have been the target of curiosity for scientists due to their characteristic amino acid sequences. While HS and UHS KAPs are known to function in disulfide bond crosslinking, the function of HGT KAPs remains unknown. To clarify the function as well as the binding partners of HGT KAPs, we prepared KAP8.1 and other KAP family proteins, the trichocyte intermediate filament proteins (IFP) K85 and K35, the head domain of K85, and the C subdomain of desmoplakin C-terminus (DPCT-C) and investigated the interactions between them in vitro. Western blot analysis and isothermal titration calorimetry (ITC) indicate that KAP8.1 binds to the head domain of K85, which is helically aligned around the axis of the intermediate filament (IF). From these results and transmission electron microscopy (TEM) observations of bundled filament complex in vitro, we propose that the helical arrangement of IFs found in the orthocortex, which is uniquely distributed on the convex fiber side of the hair, is regulated by KAP8.1. Structure-dependent binding of DPCT-C to trichocyte IFP was confirmed by Western blotting, ITC, and circular dichroism. Moreover, DPCT-C also binds to some HGT KAPs. It is probable that such bidirectional binding property of HGT KAPs contribute to the mechanical robustness of hair. Copyright © 2013 Elsevier Inc. All rights reserved.

Modification of conductive polyaniline with carbon nanomaterials

NASA Astrophysics Data System (ADS)

Sedaghat, Sajjad; Alavijeh, Mahdi Soleimani

2014-08-01

The synthesis of polyaniline/single-wall nanotube, polyaniline/multi-wall nanotube and polyaniline/single-wall nanotube/graphen nanosheets nanocomposites by in situ polymerization are reported in this study. The substrates were treated with a mixture of concentrated sulfuric acid and concentrated nitric acid before usage to functionalize with carboxylic and hydroxyl groups. Aniline monomers are adsorbed and polymerized on the surface of these fillers. Structural analysis using scanning electron microscopy showed that nanomaterials dispersed into polymer matrix and made tubular structures with diameters several tens to hundreds nanometers depending on the polyaniline content. These nanocomposites can be used for production of excellent electrode materials applications in high-performance supercapacitors.

One-step oxidation preparation of unfolded and good soluble graphene nanoribbons by longitudinal unzipping of carbon nanotubes

NASA Astrophysics Data System (ADS)

Hu, Xiaolin; Hu, Yizhen; Huang, Jindan; Zhou, Ning; Liu, Yuhan; Wei, Lin; Chen, Xin; Zhuang, Naifeng

2018-04-01

A simple one-step method to prepare graphene nanoribbon (GNR) is reported in this paper. Compared with water steam etching, the oxidation and co-etching of dilute sulfuric acid can result in the more complete longitudinal unzipping of carbon nanotube, although there is no other strong oxidant. As-prepared GNRs are more flat and have more oxygenated functional groups along the edge. Moreover, they can steadily disperse in a water system. These make them suitable as a carrier for supporting palladium (Pd) nanoparticles. The Pd/GNR composite exhibits a superior electrocatalytic activity for ethanol oxidation.

Optimization of esterification of dicarboxylic acids and 2-ethyl-1-hexanol

NASA Astrophysics Data System (ADS)

Jafri, Nur Hafifah Nahdirah; Othman, Nor Hamidah Abu; Salimon, Jumat

2018-04-01

Dicarboxylate ester has the potential alternative as plasticizer which environmentally friendly in polymeric formulation especially for poly (vinyl chloride) (PVC). Dicarboxylate ester compounds were synthesized via esterification between dicarboxylic acid and 2-ethyl-1-hexanol by using sulfuric acid as catalyst. The effects of reaction parameters were studied by optimizing temperature, mole ratio of reactants, amount of catalyst and reaction to obtain highest ester conversion. The optimum results showed dicarboxylic acid successfully converted to the dicarboxylate ester at parameters; 4 hours; 120 °C; catalyst amount: 2% w/w of diacid; and mole ratio: 1:2.5. Functional group analysis was conducted by using ATR-FTIR spectroscopy.

Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide.

PubMed

Crack, Jason C; Green, Jeffrey; Thomson, Andrew J; Le Brun, Nick E

2014-10-21

Iron-sulfur cluster proteins exhibit a range of physicochemical properties that underpin their functional diversity in biology, which includes roles in electron transfer, catalysis, and gene regulation. Transcriptional regulators that utilize iron-sulfur clusters are a growing group that exploit the redox and coordination properties of the clusters to act as sensors of environmental conditions including O2, oxidative and nitrosative stress, and metabolic nutritional status. To understand the mechanism by which a cluster detects such analytes and then generates modulation of DNA-binding affinity, we have undertaken a combined strategy of in vivo and in vitro studies of a range of regulators. In vitro studies of iron-sulfur cluster proteins are particularly challenging because of the inherent reactivity and fragility of the cluster, often necessitating strict anaerobic conditions for all manipulations. Nevertheless, and as discussed in this Account, significant progress has been made over the past decade in studies of O2-sensing by the fumarate and nitrate reduction (FNR) regulator and, more recently, nitric oxide (NO)-sensing by WhiB-like (Wbl) and FNR proteins. Escherichia coli FNR binds a [4Fe-4S] cluster under anaerobic conditions leading to a DNA-binding dimeric form. Exposure to O2 converts the cluster to a [2Fe-2S] form, leading to protein monomerization and hence loss of DNA binding ability. Spectroscopic and kinetic studies have shown that the conversion proceeds via at least two steps and involves a [3Fe-4S](1+) intermediate. The second step involves the release of two bridging sulfide ions from the cluster that, unusually, are not released into solution but rather undergo oxidation to sulfane (S(0)) subsequently forming cysteine persulfides that then coordinate the [2Fe-2S] cluster. Studies of other [4Fe-4S] cluster proteins that undergo oxidative cluster conversion indicate that persulfide formation and coordination may be more common than previously recognized. This remarkable feature suggested that the original [4Fe-4S] cluster can be restored using persulfide as the source of sulfide ion. We have demonstrated that only iron and a source of electrons are required to promote efficient conversion back from the [2Fe-2S] to the [4Fe-4S] form. We propose this as a novel in vivo repair mechanism that does not require the intervention of an iron-sulfur cluster biogenesis pathway. A number of iron-sulfur regulators have evolved to function as sensors of NO. Although it has long been known that the iron-sulfur clusters of many phylogenetically unrelated proteins are vulnerable to attack by NO, our recent studies of Wbl proteins and FNR have provided new insights into the mechanism of cluster nitrosylation, which overturn the commonly accepted view that the product is solely a mononuclear iron dinitrosyl complex (known as a DNIC). The major reaction is a rapid, multiphase process involving stepwise addition of up to eight NO molecules per [4Fe-4S] cluster. The major iron nitrosyl product is EPR silent and has optical characteristics similar to Roussin's red ester, [Fe2(NO)4(RS)2] (RRE), although a species similar to Roussin's black salt, [Fe4(NO)7(S)3](-) (RBS) cannot be ruled out. A major future challenge will be to clarify the nature of these species.

Capture of trace sulfur gases from binary mixtures by single-walled carbon nanotube arrays: a molecular simulation study.

PubMed

Wang, Wenjuan; Peng, Xuan; Cao, Dapeng

2011-06-01

Adsorption of H(2)S and SO(2) pure gases and their selective capture from the H(2)S-CH(4), H(2)S-CO(2), SO(2)-N(2), and SO(2)-CO(2) binary mixtures by the single-walled carbon nanotubes (SWNT) are investigated via using the grand canonical Monte Carlo (GCMC) method. It is found that the (20, 20) SWNT with larger diameter shows larger capacity for H(2)S and SO(2) pure gases at T = 303 K, in which the uptakes reach 16.31 and 16.03 mmol/g, respectively. However, the (6,6) SWNT with small diameter exhibits the largest selectivity for binary mixtures containing trace sulfur gases at T = 303 K and P = 100 kPa. By investigating the effect of pore size on the separation of gas mixtures, we found that the optimized pore size is 0.81 nm for separation of H(2)S-CH(4), H(2)S-CO(2), and SO(2)-N(2) binary mixtures, while it is 1.09 nm for the SO(2)-CO(2) mixture. The effects of concentration and temperature on the selectivity of sulfide are also studied at the optimal pore size. It is found that the concentration (ppm) of sulfur components has little effect on selectivity of SWNTs for these binary mixtures. However, the selectivity decreases obviously with the increase of temperature. To improve the adsorption capacities, we further modify the surface of SWNTs with the functional groups. The selectivities of H(2)S-CO(2) and SO(2)-CO(2) mixtures are basically uninfluenced by the site density, while the increase of site density can improve the selectivity of H(2)S-CH(4) mixture doubly. It is expected that this work could provide useful information for sulfur gas capture.

Synthesis of oxazolines and oxazines

DOEpatents

Benicewicz, Brian C.; Mitchell, Michael A.

1995-01-01

A process of preparing an oxazoline or oxazine compound of the formula ##STR1## wherein X is an atom selected from the group of oxygen and sulfur, R is selected from the group consisting of C.sub.1-10 alkyl, C.sub.1-10 fluoroalkyl, aryl and substituted-aryl, and n is 2 or 3 comprising ring-closing a compound of the formula ##STR2## wherein X is an atom selected from the group of oxygen and sulfur, R is selected from the group consisting of C.sub.1-10 alkyl, C.sub.1-10 fluoroalkyl, aryl, and substituted aryl, n is 2 or 3, and Y is a bromine or chlorine atom in the presence of a basic reagent consisting essentially of a fluoride salt supported on an inorganic solid substrate is disclosed together with the compounds, 5-bromomethyl-2-phenyl-1,3-oxazoline, 5-methylene-2-phenyl-1,3-oxazine and 4,4-dimethyl-2-vinyl-1,3-oxazoline.

Formation rates, stability and reactivity of sulfuric acid - amine clusters predicted by computational chemistry

NASA Astrophysics Data System (ADS)

Kurtén, Theo; Ortega, Ismael; Kupiainen, Oona; Olenius, Tinja; Loukonen, Ville; Reiman, Heidi; McGrath, Matthew; Vehkamäki, Hanna

2013-04-01

Despite the importance of atmospheric particle formation for both climate and air quality, both experiments and non-empirical models using e.g. sulfuric acid, ammonia and water as condensing vapors have so far been unable to reproduce atmospheric observations using realistic trace gas concentrations. Recent experimental and theoretical evidence has shown that this mystery is likely resolved by amines. Combining first-principles evaporation rates for sulfuric acid - dimethylamine clusters with cluster kinetic modeling, we show that even sub-ppt concentrations of amines, together with atmospherically realistic concentrations of sulfuric acid, result in formation rates close to those observed in the atmosphere. Our simulated cluster formation rates are also close to, though somewhat larger than, those measured at the CLOUD experiment in CERN for both sulfuric acid - ammonia and sulfuric acid - dimethylamine systems. A sensitivity analysis indicates that the remaining discrepancy for the sulfuric acid - amine particle formation rates is likely caused by steric hindrances to cluster formation (due to alkyl groups of the amine molecules) rather than by significant errors in the evaporation rates. First-principles molecular dynamic and reaction kinetic modeling shed further light on the microscopic physics and chemistry of sulfuric acid - amine clusters. For example, while the number and type of hydrogen bonds in the clusters typically reach their equilibrium values on a picosecond timescale, and the overall bonding patterns predicted by traditional "static" quantum chemical calculations seem to be stable, the individual atoms participating in the hydrogen bonds continuously change at atmospherically realistic temperatures. From a chemical reactivity perspective, we have also discovered a surprising phenomenon: clustering with sulfuric acid molecules slightly increases the activation energy required for the abstraction of alkyl hydrogens from amine molecules. This implies that the oxidation rate of amines by OH and possibly other oxidants may be decreased by clustering, thus prolonging the chemical lifetime of amines in the air.

Nano-functionalization of protein microspheres

NASA Astrophysics Data System (ADS)

Yoon, Sungkwon; Nichols, William T.

2014-08-01

Protein microspheres are promising building blocks for the assembly of complex functional materials. Here we demonstrate a set of three techniques that add functionality to the surface of protein microspheres. In the first technique, a positive surface charge on the protein spheres is deposited by electrostatic adsorption. Negatively charged silica and gold nanoparticle colloids can then electrostatically bind reversibly to the microsphere surface. In the second technique, nanoparticles are covalently anchored to the protein shell using a simple one-pot process. The strong covalent bond between sulfur groups in cysteine in the protein shell irreversibly binds to the gold nanoparticles. In the third technique, surface morphology of the protein microsphere is tuned through hydrodynamic instability at the water-oil interface. This is accomplished through the degree of solubility of the oil phase in water. Taken together these three techniques form a platform to create nano-functionalized protein microspheres, which can then be used as building blocks for the assembly of more complex macroscopic materials.

Heavy metal ion removal by thiol functionalized aluminum oxide hydroxide nanowhiskers

NASA Astrophysics Data System (ADS)

Xia, Zhiyong; Baird, Lance; Zimmerman, Natasha; Yeager, Matthew

2017-09-01

In this study, we developed a cost effective method of using thiol functionalized γ-aluminum oxide hydroxide (γ-AlOOH) filters for removing three key heavy metals from water: mercury, lead, and cadmium under non-concomitant conditions. Compared to non-thiol treated γ-AlOOH filters, the introduction of thiol functional groups greatly improved the heavy metal removal efficiency under both static and dynamic filtration conditions. The adsorption kinetics of thiol functionalized γ-AlOOH were investigated using the Lagergren first order and pseudo-second order kinetics models; whereas the isothermal adsorption behavior of these membranes was revealed through the Langmuir and Freundlich models. Heavy metal concentration was quantified by Inductively Coupled Plasma-Mass Spectroscopy, and the thiol level on γ-AlOOH surface was measured by a colorimetric assay using Ellman's reagent. X-ray photoelectron spectroscopy was used to further address the surface sulfur state on the membranes after heavy metal exposure. Mechanisms for heavy metal adsorption were also discussed.

The effect of vitamin E on tracheal responsiveness and lung inflammation in sulfur mustard exposed guinea pigs.

PubMed

Boskabady, Mohammad Hossein; Amery, Sediqa; Vahedi, Nassim; Khakzad, Mohammad Reza

2011-02-01

Pulmonary complications of sulfur mustard (SM) range from mild respiratory symptoms to even severe bronchial stenosis. In the present study, the protective effect of vitamin E on tracheal responsiveness (TR) and lung inflammation of SM-exposed guinea pigs were examined. Guinea pigs were exposed to ethanol (control group), 40 mg/m(3) inhaled SM and ethanol vehicle (sulfur mustard exposed (SME) group), SME treated with vitamin E (SME + E), SME with dexamethasone (SME + D) and both drugs (SME + E + D), (n = 8 for each group). TR to methacholine, total and differential white blood cell (WBC) count of lung lavage and serum cytokines were evaluated 14 days post-exposure. TR, WBC, interleukin 4 (IL-4), interferon gamma (INF-γ), eosinophil, and monocyte levels in SME guinea pigs were significantly higher, but lymphocyte was lower than those of controls (P < 0.05 to P < 0.001). TR, IL-4, and eosinophil levels in SME + E, SME + D and SME + E + D, INF-γ in SME + E and SME + E + D and WBC in SME + E were significantly decreased compared to that of the SME group (P < 0.01 to P < 0.001). In addition, the TR of SME + D + E was significantly higher than that of SME + E (P < 0.01) and SME + D (P < 0.05) groups. The results showed a preventive effect of vitamin E, dexamethasone and their combination on TR and lung inflammation in SME guinea pigs.

Preparation of sulfonic acid-containing rubbers from natural rubber vulcanizates

NASA Astrophysics Data System (ADS)

Poonsawat, Worapong; Poompradub, Sirilux; Ngamcharussrivichai, Chawalit

2014-06-01

In this work, a series of sulfonic acid-containing rubbers were prepared by aqueous phase oxidation of natural rubber vulcanizates in the presence of hydrogen peroxide (H2O2) and formic acid (HCOOH). The starting vulcanizates were neatly prepared via an efficient vulcanization (EV) system by varying mass ratio of N-cyclohexyl-2-benzothiazole sulfonamide (CBS), as an accelerator, to sulfur. The oxidation conditions were controlled at the molar ratio of H2O2: HCOOH = 1:1, the concentration of H2O2 = 15 wt.%, the temperature = 50 °C, and the reaction time = 3 h. The rubber materials before and after the oxidation were characterized for their physicochemical properties by using Fourier transform infrared spectroscopy, bomb calorimetry, acid-base titration and swelling measurements. The results indicated the presence of sulfonic acid group in the oxidized rubbers, generated by the oxidative cleaves of sulfide crosslinks in the rubber vulcanizates. The oxidation decreased the sulfur content of the rubber in which the level of sulfur loss was determined by the CBS/sulfur ratio. Moreover, the acidity of the oxidized products was correlated with the amount of sulfur remaining.

The effect of vitamin E on lung pathology in sulfur mustard-exposed guinea pigs.

PubMed

Gholamnezhad, Zahra; Boskabady, Mohammad Hossein; Amery, Sediqa; Vahedi, Nassim; Tabatabaei, Abass; Boskabady, Morteza; Shahriary, Alireza

2016-12-01

Pulmonary complications of exposure to sulfur mustard (SM) gas range from no effect or mild symptoms to severe bronchial stenosis. In the present study, the protective effect of vitamin E on the lung inflammation of SM-exposed guinea pigs was examined. Guinea pigs (n = 5 for each group) were exposed to ethanol (control group), 40 mg/m 3 inhaled SM (SME group), SME treated with vitamin E (SME + E), SME treated with dexamethasone (SME + D), and SME treated with both treatments (SME + E + D). Pathological evaluation of the lung was done 14 days postexposure. The epithelial desquamation of trachea and other pathologic changes in the lung of the SME group were significantly higher than those in the control group. Furthermore, the pathological changes of trachea and lung in the SME + E and SME + E + D groups were significantly improved compared with those of SME group. In addition, the pathological changes of trachea and lung of SME + E and SME + E + D animals were significantly less than those of SME + D group. © The Author(s) 2015.

Insights from the metagenome of an acid salt lake: the role of biology in an extreme depositional environment.

PubMed

Johnson, Sarah Stewart; Chevrette, Marc Gerard; Ehlmann, Bethany L; Benison, Kathleen Counter

2015-01-01

The extremely acidic brine lakes of the Yilgarn Craton of Western Australia are home to some of the most biologically challenging waters on Earth. In this study, we employed metagenomic shotgun sequencing to generate a microbial profile of the depositional environment associated with the sulfur-rich sediments of one such lake. Of the 1.5 M high-quality reads generated, 0.25 M were mapped to protein features, which in turn provide new insights into the metabolic function of this community. In particular, 45 diverse genes associated with sulfur metabolism were identified, the majority of which were linked to either the conversion of sulfate to adenylylsulfate and the subsequent production of sulfide from sulfite or the oxidation of sulfide, elemental sulfur, and thiosulfate via the sulfur oxidation (Sox) system. This is the first metagenomic study of an acidic, hypersaline depositional environment, and we present evidence for a surprisingly high level of microbial diversity. Our findings also illuminate the possibility that we may be meaningfully underestimating the effects of biology on the chemistry of these sulfur-rich sediments, thereby influencing our understanding of past geobiological conditions that may have been present on Earth as well as early Mars.

Hibiscus chlorotic ringspot virus coat protein upregulates sulfur metabolism genes for enhanced pathogen defense.

PubMed

Gao, Ruimin; Ng, Florence Kai Lin; Liu, Peng; Wong, Sek-Man

2012-12-01

In both Hibiscus chlorotic ringspot virus (HCRSV)-infected and HCRSV coat protein (CP) agroinfiltrated plant leaves, we showed that sulfur metabolism pathway related genes-namely, sulfite oxidase (SO), sulfite reductase, and adenosine 5'-phosphosulfate kinase-were upregulated. It led us to examine a plausible relationship between sulfur-enhanced resistance (SED) and HCRSV infection. We broadened an established method to include different concentrations of sulfur (0S, 1S, 2S, and 3S) to correlate them to symptom development of HCRSV-infected plants. We treated plants with glutathione and its inhibitor to verify the SED effect. Disease resistance was induced through elevated glutathione contents during HCRSV infection. The upregulation of SO was related to suppression of symptom development induced by sulfur treatment. In this study, we established that HCRSV-CP interacts with SO which, in turn, triggers SED and leads to enhanced plant resistance. Thus, we have discovered a new function of SO in the SED pathway. This is the first report to demonstrate that the interaction of a viral protein and host protein trigger SED in plants. It will be interesting if such interaction applies generally to other host-pathogen interactions that will lead to enhanced pathogen defense.

Sulfur deficiency changes mycosporine-like amino acid (MAA) composition of Anabaena variabilis PCC 7937: a possible role of sulfur in MAA bioconversion.

PubMed

Singh, Shailendra P; Klisch, Manfred; Sinha, Rajeshwar P; Häder, Donat-Peter

2010-01-01

In the present investigation we show for the first time that bioconversion of a primary mycosporine-like amino acid (MAA) into a secondary MAA is regulated by sulfur deficiency in the cyanobacterium Anabaena variabilis PCC 7937. This cyanobacterium synthesizes the primary MAA shinorine (RT = 2.2 min, lambda(max) = 334 nm) under normal conditions (PAR + UV-A + UV-B); however, under sulfur deficiency, a secondary MAA palythine-serine (RT = 3.9 min, lambda(max) = 320 nm) appears. Addition of methionine to sulfur-deficient cultures resulted in the disappearance of palythine-serine, suggesting the role of primary MAAs under sulfur deficiency in recycling of methionine by donating the methyl group from the glycine subunit of shinorine to tetrahydrofolate to regenerate the methionine from homocysteine. This is also the first report for the synthesis of palythine-serine by cyanobacteria which has so far been reported only from corals. Addition of methionine also affected the conversion of mycosporine-glycine into shinorine, consequently, resulted in the appearance of mycosporine-glycine (RT = 3.6 min, lambda(max) = 310 nm). Our results also suggest that palythine-serine is synthesized from shinorine. Based on these results we propose that glycine decarboxylase is the potential enzyme that catalyzes the bioconversion of shinorine to palythine-serine by decarboxylation and demethylation of the glycine unit of shinorine.

Stabilizing the Performance of High-Capacity Sulfur Composite Electrodes by a New Gel Polymer Electrolyte Configuration.

PubMed

Agostini, Marco; Lim, Du Hyun; Sadd, Matthew; Fasciani, Chiara; Navarra, Maria Assunta; Panero, Stefania; Brutti, Sergio; Matic, Aleksandar; Scrosati, Bruno

2017-09-11

Increased pollution and the resulting increase in global warming are drawing attention to boosting the use of renewable energy sources such as solar or wind. However, the production of energy from most renewable sources is intermittent and thus relies on the availability of electrical energy-storage systems with high capacity and at competitive cost. Lithium-sulfur batteries are among the most promising technologies in this respect due to a very high theoretical energy density (1675 mAh g -1 ) and that the active material, sulfur, is abundant and inexpensive. However, a so far limited practical energy density, life time, and the scaleup of materials and production processes prevent their introduction into commercial applications. In this work, we report on a simple strategy to address these issues by using a new gel polymer electrolyte (GPE) that enables stable performance close to the theoretical capacity of a low cost sulfur-carbon composite with high loading of active material, that is, 70 % sulfur. We show that the GPE prevents sulfur dissolution and reduces migration of polysulfide species to the anode. This functional mechanism of the GPE membranes is revealed by investigating both its morphology and the Li-anode/GPE interface at various states of discharge/charge using Raman spectroscopy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ice Nucleation of Bare and Sulfuric Acid-coated Mineral Dust Particles and Implication for Cloud Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulkarni, Gourihar R.; Sanders, Cassandra N.; Zhang, Kai

2014-08-27

Ice nucleation properties of different dust species coated with soluble material are not well understood. We determined the ice nucleation ability of bare and sulfuric acid coated mineral dust particles as a function of temperature (-25 to -35 deg C) and relative humidity with respect to water (RHw). Five different mineral dust species: Arizona test dust (ATD), illite, montmorillonite, quartz and kaolinite were dry dispersed and size-selected at 150 nm and exposed to sulfuric acid vapors in the coating apparatus. The condensed sulfuric acid soluble mass fraction per particle was estimated from the cloud condensation nuclei activated fraction measurements. Themore » fraction of dust particles nucleating ice at various temperatures and RHw was determined using a compact ice chamber. In water-subsaturated conditions, compared to bare dust particles, we found that only coated ATD particles showed suppression of ice nucleation ability while other four dust species did not showed the effect of coating on the fraction of particles nucleating ice. The results suggest that interactions between the dust surface and sulfuric acid vapor are important, such that interactions may or may not modify the surface via chemical reactions with sulfuric acid. At water-supersaturated conditions we did not observed the effect of coating, i.e. the bare and coated dust particles had similar ice nucleation behavior.« less

First-principles study for the enhanced sulfur tolerance of Ni(1 1 1) surface alloyed with Pb

NASA Astrophysics Data System (ADS)

Zhang, Yanxing; Yang, Zongxian

2018-04-01

The adsorption of H2S, HS, S, H and the dissociation of H2S on the Ni2Pb/Ni (1 1 1) are systematically studied using the first-principles method based on density functional theory. It is found that H2S dissociation barriers are greatly increased by alloying with Pb atoms in the Ni(1 1 1) surface, while the barrier for H2S formation is greatly reduced. In addition, the adsorption of sulfur atom is weakened a lot. The results indicate that alloying with Pb may be a good way to increase the sulfur tolerance of Ni based anode catalysts of solid oxide fuel cells.

Spectroscopic characteristics of carbon dots (C-dots) derived from carbon fibers and conversion to sulfur-bridged C-dots nanosheets.

PubMed

Vinci, John C; Ferrer, Ivonne M; Guterry, Nathan W; Colón, Verónica M; Destino, Joel F; Bright, Frank V; Colón, Luis A

2015-09-01

We synthesized sub-10 nm carbon nanoparticles (CNPs) consistent with photoluminescent carbon dots (C-dots) from carbon fiber starting material. The production of different C-dots fractions was monitored over seven days. During the course of the reaction, one fraction of C-dots species with relatively high photoluminescence was short-lived, emerging during the first hour of reaction but disappearing after one day of reaction. Isolation of this species during the first hour of the reaction was crucial to obtaining higher-luminescent C-dots species. When the reaction proceeded for one week, the appearance of larger nanostructures was observed over time, with lateral dimensions approaching 200 nm. The experimental evidence suggests that these larger species are formed from small C-dot nanoparticles bridged together by sulfur-based moieties between the C-dot edge groups, as if the C-dots polymerized by cross-linking the edge groups through sulfur bridges. Their size can be tailored by controlling the reaction time. Our results highlight the variety of CNP products, from sub-10 nm C-dots to ~200 nm sulfur-containing carbon nanostructures, that can be produced over time during the oxidation reaction of the graphenic starting material. Our work provides a clear understanding of when to stop the oxidation reaction during the top-down production of C-dots to obtain highly photoluminescent species or a target average particle size.

Monitoring, exposure and risk assessment of sulfur dioxide residues in fresh or dried fruits and vegetables in China.

PubMed

Lou, Tiantian; Huang, Weisu; Wu, Xiaodan; Wang, Mengmeng; Zhou, Liying; Lu, Baiyi; Zheng, Lufei; Hu, Yinzhou

2017-06-01

Sulfur dioxide residues in 20 kinds of products collected from 23 provinces of China (Jilin, Beijing, Shanxi, Shandong, Henan, Hebei, Jiangsu, Anhui, Shanghai, Zhejiang, Fujian, Guangdong, Guangxi, Yunnan, Guizhou, Hunan, Hubei, Chongqing, Sichuan, Gansu, Neimenggu, Xinjiang and Hainan) were analysed, and a health risk assessment was performed. The detection rates of sulfur dioxide residues in fresh vegetables, fresh fruits, dried vegetables and dried fruits were 11.1-95.9%, 12.6-92.3%, 70.3-80.0% and 26.0-100.0%, respectively; the mean concentrations of residues were 2.7-120.8, 3.8-35.7, 26.9-99.1 and 12.0-1120.4 mg kg -1 , respectively. The results indicated that fresh vegetables and dried products are critical products; the daily intakes (EDIs) for children were higher than others; the hazard indexes (HI) for four groups were 0.019-0.033, 0.001-0.005, 0.007-0.016 and 0.002-0.005 at P50, respectively. But the HI was more than 1 at P99 by intake dried fruits and vegetables. Although the risk for consumers was acceptable on the whole, children were the most vulnerable group. Uncertainty and sensitivity analyses indicated that the level of sulfur dioxide residues was the most influential variable in this model. Thus, continuous monitoring and stricter regulation of sulfites using are recommended in China.

Functionalization and characterization of pyrolyzed polymer based carbon microstructures for bionanoelectronics platforms

NASA Astrophysics Data System (ADS)

Hirabayashi, Mieko; Mehta, Beejal; Vahidi, Nasim W.; Khosla, Ajit; Kassegne, Sam

2013-11-01

In this study, the investigation of surface-treatment of chemically inert graphitic carbon microelectrodes (derived from pyrolyzed photoresist polymer) for improving their attachment chemistry with DNA molecular wires and ropes as part of a bionanoelectronics platform is reported. Polymer microelectrodes were fabricated on a silicon wafer using standard negative lithography procedures with negative-tone photoresist. These microelectrode structures were then pyrolyzed and converted to a form of conductive carbon that is referred to as PP (pyrolyzed polymer) carbon throughout this paper. Functionalization of the resulting pyrolyzed structures was done using nitric, sulfuric, 4-amino benzoic acids (4-ABA), and oxygen plasma etching and the surface modifications confirmed with Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and electron dispersion x-ray spectroscopy (EDS). Post surface-treatment analysis of microelectrodes with FTIR and Raman spectroscopy showed signature peaks characteristics of carboxyl functional groups while EDS showed an increase in oxygen content in the surface-treatment procedures (except 4-ABA) indicating an increase in carboxyl functional group. These functional groups form the basis for peptide bond with aminated oligonucleotides that in turn could be used as molecular wires and interconnects in a bionanoelectronics platform. Post-pyrolysis analysis using EDS showed relatively higher oxygen concentrations at the edges and location of defects compared to other locations on these microelectrodes. In addition, electrochemical impedance measurements showed metal-like behavior of PP carbon with high conductivity (|Z| <1 KΩ) and no detectable detrimental effect of oxygen plasma surface-treatment on electrical characteristic. In general, characterization results—taken together—indicated that oxygen plasma surface-treatment produced more reliable, less damaging, and consistently repeatable generation of carboxyl functional groups than diazonium salt and strong acid treatments.

Cat cracking technology with reduced discharge of harmful substances to the atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elshin, A.I.; Aliev, R.R.; Solyar, B.Z.

1995-11-01

The operation of cat crackers creates a number of ecological problems involving pollution of the atmosphere. In the regeneration of coked catalyst, up to 10 tonnes/day of sulfur oxides are discharged to the atmosphere, along with catalyst dust in amounts up to 2 tonnes/day and carbon monoxide up to 120 tonnes/day. With increasingly severe requirements for environmental protection, the problem of reducing harmful discharges to the atmosphere has become more acute, necessitating either preliminary hydrotreating of the feed or scrubber cleanup of the stack gas to remove sulfur oxides. The high cost of these processes has provided the impetus formore » proposing various types of bifunctional cracking catalysts and effective catalyst additives to bind sulfur oxides directly in the regenerator. Basic oxides (of aluminum, magnesium, calcium, etc.) react with sulfur oxides to form stable sulfates that are then reduced to hydrogen sulfide in the reactor, while re-forming the basic oxide. Binding sulfur oxides in the regenerator is favored by the presence of an oxidizing agent or by the introduction of a promoter for afterburning carbon monoxide to dioxide. Compositions consisting mainly of aluminum oxide ({>=}90% by weight) have been patented as catalyst additives for binding sulfur oxides; other compositions that have been patented consist of Group II metal oxides and other oxides that have oxidizing properties. The additives are introduced into the catalyst charge in amounts of 5-10% by weight. On the basis of research, an aluminium oxide additive, PS-17, has been developed for binding sulfur oxides in the course of cracking.« less

Redox State of the Neoarchean Earth Environment

NASA Technical Reports Server (NTRS)

Zerkle, Aubrey L.; Claire, Mark W.; Domagal-Goldman, Shawn; Farquhar, James; Poulton, Simon W.

2011-01-01

A Titan-like organic haze has been hypothesized for Earth's atmosphere prior to widespread surface oxygenation approx.2.45 billion years ago (Ga). We present a high-resolution record of quadruple sulfur isotopes, carbon isotopes, and Fe speciation from the approx.2.65-2.5 Ga Ghaap Group, South Africa, which suggest a linkage between organic haze and the biogeochemical cycling of carbon, sulfur, oxygen, and iron on the Archean Earth. These sediments provide evidence for oxygen production in microbial mats and localized oxygenation of surface waters. However, this oxygen production occurred under a reduced atmosphere which existed in multiple distinct redox states that correlate to changes in carbon and sulfur isotopes. The data are corroborated by photochemical model results that suggest bi-stable transitions between organic haze and haze-free atmospheric conditions in the Archean. These geochemical correlations also extend to other datasets, indicating that variations in the character of anomalous sulfur fractionation could provide insight into the role of carbon-bearing species in the reducing Archean atmosphere.

The physiology of dimethylsulfoniopropionate (DMSP) production in phytoplankton

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, M.D.; Bellows, W.K.

1990-06-01

Dimethylsulfoniopropionate (DMSP) is the precursor of dimethyl sulfide (DMS), the primary volatile organic sulfur compound released from the world's oceans. DMS flux from the oceans is estimated currently at {approximately}1.2 Tmol S.y{sup {minus}1}, or about half the amount of sulfur resulting from anthroprogenic activities, and has been implicated in important global atmospheric processes. Significant production of DMSP is confined to a few classes of marine phytoplankton, primarily the Dinophyceae and Prymnesiophyceae. In these groups, DMSP can account for up to 80% of total organic sulfur. DMSP remains intracellular and fairly constant over the growth cycle until late stationary phase whenmore » extracellular levels begin to rise, suggesting leakage. We have examined the effects of a number of environmental variables on DMSP production and release in several marine phytoplankton. In particular the effects of perturbations in light, temperature and nutrient status have been determined. These results will be discussed in relation to marine sulfur chemistry, with ancillary comments on freshwater phytoplankton.« less

Transformation of chlorpyrifos and chlorpyrifos-methyl in prairie pothole pore waters.

PubMed

Adams, Rachel M; McAdams, Brandon C; Arnold, William A; Chin, Yu-Ping

2016-11-09

Non-point source pesticide pollution is a concern for wetlands in the prairie pothole region (PPR). Recent studies have demonstrated that reduced sulfur species (e.g., bisulfide and polysulfides) in PPR wetland pore waters directly undergo reactions with chloroacetanilide and dinitroaniline compounds. In this paper, the abiotic transformation of two organophosphate compounds, chlorpyrifos and chlorpyrifos-methyl, was studied in PPR wetland pore waters. Chlorpyrifos-methyl reacted significantly faster (up to 4 times) in pore water with reduced sulfur species relative to hydrolysis. No rate enhancement was observed in the transformation of chlorpyrifos in pore water with reduced sulfur species. The lack of reactivity was most likely caused by steric hindrance from the ethyl groups and partitioning to dissolved organic matter (DOM), thereby shielding chlorpyrifos from nucleophilic attack. Significant decreases in reaction rates were observed for chlorpyrifos in pore water with high concentrations of DOM. Rate enhancement due to other reactive species (e.g., organo-sulfur compounds) in pore water was minor for both compounds relative to the influence of bisulfide and DOM.

Macrolide Antibiotics Improve Phagocytic Capacity and Reduce Inflammation In Sulfur Mustard-Exposed Monocytes

DTIC Science & Technology

2008-12-01

phagocytotic function and on inflammatory cytokines/mediators production in vitro using SM-exposed monocyte THP - 1 cells. Using flow cytometry we found...in vitro using SM-exposed monocyte THP - 1 cells. 2. MATERIALS AND METHODS 2.1 Reagents Sulfur mustard (2,2’-dichlorodiethyl sulfide; 4 mM) was...monocyte THP - 1 cells were obtained from ATCC (Manassas, VA). Cells were grown as suspension in the optimized media as formulated by the manufacturer and

A highly efficient polysulfide mediator for lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Liang, Xiao; Hart, Connor; Pang, Quan; Garsuch, Arnd; Weiss, Thomas; Nazar, Linda F.

2015-01-01

The lithium-sulfur battery is receiving intense interest because its theoretical energy density exceeds that of lithium-ion batteries at much lower cost, but practical applications are still hindered by capacity decay caused by the polysulfide shuttle. Here we report a strategy to entrap polysulfides in the cathode that relies on a chemical process, whereby a host—manganese dioxide nanosheets serve as the prototype—reacts with initially formed lithium polysulfides to form surface-bound intermediates. These function as a redox shuttle to catenate and bind ‘higher’ polysulfides, and convert them on reduction to insoluble lithium sulfide via disproportionation. The sulfur/manganese dioxide nanosheet composite with 75 wt% sulfur exhibits a reversible capacity of 1,300 mA h g-1 at moderate rates and a fade rate over 2,000 cycles of 0.036%/cycle, among the best reported to date. We furthermore show that this mechanism extends to graphene oxide and suggest it can be employed more widely.

Advances in the study on endogenous sulfur dioxide in the cardiovascular system.

PubMed

Tian, Hong

2014-01-01

This review summarized the current advances in understanding the role of the novel gasotransmitter, sulfur dioxide (SO2), in the cardiovascular system. Articles on the advances in the study of the role of endogenous sulfur dioxide in the cardiovascular system were accessed from PubMed and CNKI from 2003 to 2013, using keywords such as "endogenous sulfur dioxide" and "cardiovascular system". Articles with regard to the role of SO2 in the regulation of cardiovascular system were selected. Recently, scientists discovered that an endogenous SO2 pathway is present in the cardiovascular system and exerts physiologically significant effects, such as regulation of the cardiac function and the pathogenesis of various cardiopulmonary diseases such as hypoxic pulmonary hypertension, hypertension, coronary atherosclerosis, and cardiac ischemia-reperfusion (I/R) injury, in the cardiovascular system. Endogenous SO2 is a novel member of the gasotransmitter family in addition to the nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S). Studies indicated that it has a role in regulating the cardiovascular disease.

DFT Insights into the Competitive Adsorption of Sulfur- and Nitrogen-Containing Compounds and Hydrocarbons on Co-Promoted Molybdenum Sulfide Catalysts

DOE PAGES

Rangarajan, Srinivas; Mavrikakis, Manos

2016-04-07

The adsorption of 20 nitrogen-/sulfur-containing and hydrocarbon compounds on the sulfur edge of cobalt-promoted molybdenum sulfide (CoMoS) catalyst was studied using density functional theory, accounting for van der Waals interactions, to elicit comparative structure–property trends across different classes of molecules relevant to hydrotreating. Unhindered organosulfur compounds preferentially adsorb on a “CUS-like” site formed by the dimerization of two neighboring sulfur atoms on the edge to create a vacancy. Nitrogen-containing compounds and 4,6-dimethyldibenzothiophene, however, prefer the brim sites. Binding energy trends indicate that nitrogen-containing compounds will inhibit hydrodesulfurization on the brim sites and, relatively weakly, on the CUS-like sites. Edge vacanciesmore » are,thus, likely to be essential for hydrodesulfurization of unhindered organosulfur compounds. Furthermore, van der Waals forces contribute significantly to the binding energy of compounds (up to 1.0 eV for large compounds such as alkyl-substituted acridines) on CoMoS.« less

The Rieske Iron-Sulfur Protein: Import and Assembly into the Cytochrome bc(1) Complex of Yeast Mitochondria.

PubMed

Conte, Laura; Zara, Vincenzo

2011-01-01

The Rieske iron-sulfur protein, one of the catalytic subunits of the cytochrome bc(1) complex, is involved in electron transfer at the level of the inner membrane of yeast mitochondria. The Rieske iron-sulfur protein is encoded by nuclear DNA and, after being synthesized in the cytosol, is imported into mitochondria with the help of a cleavable N-terminal presequence. The imported protein, besides incorporating the 2Fe-2S cluster, also interacts with other catalytic and non-catalytic subunits of the cytochrome bc(1) complex, thereby assembling into the mature and functional respiratory complex. In this paper, we summarize the most recent findings on the import and assembly of the Rieske iron-sulfur protein into Saccharomyces cerevisiae mitochondria, also discussing a possible role of this protein both in the dimerization of the cytochrome bc(1) complex and in the interaction of this homodimer with other complexes of the mitochondrial respiratory chain.

The Rieske Iron-Sulfur Protein: Import and Assembly into the Cytochrome bc 1 Complex of Yeast Mitochondria

PubMed Central

Conte, Laura; Zara, Vincenzo

2011-01-01

The Rieske iron-sulfur protein, one of the catalytic subunits of the cytochrome bc 1 complex, is involved in electron transfer at the level of the inner membrane of yeast mitochondria. The Rieske iron-sulfur protein is encoded by nuclear DNA and, after being synthesized in the cytosol, is imported into mitochondria with the help of a cleavable N-terminal presequence. The imported protein, besides incorporating the 2Fe-2S cluster, also interacts with other catalytic and non-catalytic subunits of the cytochrome bc 1 complex, thereby assembling into the mature and functional respiratory complex. In this paper, we summarize the most recent findings on the import and assembly of the Rieske iron-sulfur protein into Saccharomyces cerevisiae mitochondria, also discussing a possible role of this protein both in the dimerization of the cytochrome bc 1 complex and in the interaction of this homodimer with other complexes of the mitochondrial respiratory chain. PMID:21716720

MicroRNA-210 regulates mitochondrial free radical response to hypoxia and krebs cycle in cancer cells by targeting iron sulfur cluster protein ISCU.

PubMed

Favaro, Elena; Ramachandran, Anassuya; McCormick, Robert; Gee, Harriet; Blancher, Christine; Crosby, Meredith; Devlin, Cecilia; Blick, Christopher; Buffa, Francesca; Li, Ji-Liang; Vojnovic, Borivoj; Pires das Neves, Ricardo; Glazer, Peter; Iborra, Francisco; Ivan, Mircea; Ragoussis, Jiannis; Harris, Adrian L

2010-04-26

Hypoxia in cancers results in the upregulation of hypoxia inducible factor 1 (HIF-1) and a microRNA, hsa-miR-210 (miR-210) which is associated with a poor prognosis. In human cancer cell lines and tumours, we found that miR-210 targets the mitochondrial iron sulfur scaffold protein ISCU, required for assembly of iron-sulfur clusters, cofactors for key enzymes involved in the Krebs cycle, electron transport, and iron metabolism. Down regulation of ISCU was the major cause of induction of reactive oxygen species (ROS) in hypoxia. ISCU suppression reduced mitochondrial complex 1 activity and aconitase activity, caused a shift to glycolysis in normoxia and enhanced cell survival. Cancers with low ISCU had a worse prognosis. Induction of these major hallmarks of cancer show that a single microRNA, miR-210, mediates a new mechanism of adaptation to hypoxia, by regulating mitochondrial function via iron-sulfur cluster metabolism and free radical generation.

Greatly Suppressed Shuttle Effect for Improved Lithium Sulfur Battery Performance through Short Chain Intermediates.

PubMed

Xu, Na; Qian, Tao; Liu, Xuejun; Liu, Jie; Chen, Yu; Yan, Chenglin

2017-01-11

The high solubility of long-chain lithium polysulfides and their infamous shuttle effect in lithium sulfur battery lead to rapid capacity fading along with low Coulombic efficiency. To address above issues, we propose a new strategy to suppress the shuttle effect for greatly enhanced lithium sulfur battery performance mainly through the formation of short-chain intermediates during discharging, which allows significant improvements including high capacity retention of 1022 mAh/g with 87% retention for 450 cycles. Without LiNO 3 -containing electrolytes, the excellent Coulombic efficiency of ∼99.5% for more than 500 cycles is obtained, suggesting the greatly suppressed shuttle effect. In situ UV/vis analysis of electrolyte during cycling reveals that the short-chain Li 2 S 2 and Li 2 S 3 polysulfides are detected as main intermediates, which are theoretically verified by density functional theory (DFT) calculations. Our strategy may open up a new avenue for practical application of lithium sulfur battery.

Synthesis of l-cysteine derivatives containing stable sulfur isotopes and application of this synthesis to reactive sulfur metabolome.

PubMed

Ono, Katsuhiko; Jung, Minkyung; Zhang, Tianli; Tsutsuki, Hiroyasu; Sezaki, Hiroshi; Ihara, Hideshi; Wei, Fan-Yan; Tomizawa, Kazuhito; Akaike, Takaaki; Sawa, Tomohiro

2017-05-01

Cysteine persulfide is an L-cysteine derivative having one additional sulfur atom bound to a cysteinyl thiol group, and it serves as a reactive sulfur species that regulates redox homeostasis in cells. Here, we describe a rapid and efficient method of synthesis of L-cysteine derivatives containing isotopic sulfur atoms and application of this method to a reactive sulfur metabolome. We used bacterial cysteine syntheses to incorporate isotopic sulfur atoms into the sulfhydryl moiety of L-cysteine. We cloned three cysteine synthases-CysE, CysK, and CysM-from the Gram-negative bacterium Salmonella enterica serovar Typhimurium LT2, and we generated their recombinant enzymes. We synthesized 34 S-labeled L-cysteine from O-acetyl-L-serine and 34 S-labeled sodium sulfide as substrates for the CysK or CysM reactions. Isotopic labeling of L-cysteine at both sulfur ( 34 S) and nitrogen ( 15 N) atoms was also achieved by performing enzyme reactions with 15 N-labeled L-serine, acetyl-CoA, and 34 S-labeled sodium sulfide in the presence of CysE and CysK. The present enzyme systems can be applied to syntheses of a series of L-cysteine derivatives including L-cystine, L-cystine persulfide, S-sulfo-L-cysteine, L-cysteine sulfonate, and L-selenocystine. We also prepared 34 S-labeled N-acetyl-L-cysteine (NAC) by incubating 34 S-labeled L-cysteine with acetyl coenzyme A in test tubes. Tandem mass spectrometric identification of low-molecular-weight thiols after monobromobimane derivatization revealed the endogenous occurrence of NAC in the cultured mammalian cells such as HeLa cells and J774.1 cells. Furthermore, we successfully demonstrated, by using 34 S-labeled NAC, metabolic conversion of NAC to glutathione and its persulfide, via intermediate formation of L-cysteine, in the cells. The approach using isotopic sulfur labeling combined with mass spectrometry may thus contribute to greater understanding of reactive sulfur metabolome and redox biology. Copyright © 2017 Elsevier Inc. All rights reserved.

Stevia, cyclamate and saccharin - natural and artificial sweeteners - exert no effect on sulfane levels in tissues.

PubMed

Wilinski, Bogdan; Opoka, Wlodzimierz; Somogyi, Eugeniusz; Piotrowska, Joanna; Wilinski, Jerzy

The interactions among natural and artificial sweeteners and endogenous sulfur metabolism have never been investigated. CBA strain mice were administered orally stevia, cyclamate or saccharin in doses of 5 mg/kg of body weight in water solutions each. The measurements of the free and acid-labile sulfane (H2S) tissue concentrations in brain, heart, liver and kidney were performed with Siegel spectrophotometric modified method. No differences in comparisons between hydrogen sulfide concentrations in the control group and each sweetener group within every tissue type were noted. In conclusion, stevia, cyclamate and saccharine do not change the endogenous sulfur metabolism to the extent of causing sulfane tissue levels alterations.

The Presence of Multiple Cellular Defects Associated with a Novel G50E Iron-Sulfur Cluster Scaffold Protein (ISCU) Mutation Leads to Development of Mitochondrial Myopathy*

PubMed Central

Saha, Prasenjit Prasad; Kumar, S. K. Praveen; Srivastava, Shubhi; Sinha, Devanjan; Pareek, Gautam; D'Silva, Patrick

2014-01-01

Iron-sulfur (Fe-S) clusters are versatile cofactors involved in regulating multiple physiological activities, including energy generation through cellular respiration. Initially, the Fe-S clusters are assembled on a conserved scaffold protein, iron-sulfur cluster scaffold protein (ISCU), in coordination with iron and sulfur donor proteins in human mitochondria. Loss of ISCU function leads to myopathy, characterized by muscle wasting and cardiac hypertrophy. In addition to the homozygous ISCU mutation (g.7044G→C), compound heterozygous patients with severe myopathy have been identified to carry the c.149G→A missense mutation converting the glycine 50 residue to glutamate. However, the physiological defects and molecular mechanism associated with G50E mutation have not been elucidated. In this report, we uncover mechanistic insights concerning how the G50E ISCU mutation in humans leads to the development of severe ISCU myopathy, using a human cell line and yeast as the model systems. The biochemical results highlight that the G50E mutation results in compromised interaction with the sulfur donor NFS1 and the J-protein HSCB, thus impairing the rate of Fe-S cluster synthesis. As a result, electron transport chain complexes show significant reduction in their redox properties, leading to loss of cellular respiration. Furthermore, the G50E mutant mitochondria display enhancement in iron level and reactive oxygen species, thereby causing oxidative stress leading to impairment in the mitochondrial functions. Thus, our findings provide compelling evidence that the respiration defect due to impaired biogenesis of Fe-S clusters in myopathy patients leads to manifestation of complex clinical symptoms. PMID:24573684

Biogenesis and functions of mammalian iron-sulfur proteins in the regulation of iron homeostasis and pivotal metabolic pathways.

PubMed

Rouault, Tracey A; Maio, Nunziata

2017-08-04

Fe-S cofactors are composed of iron and inorganic sulfur in various stoichiometries. A complex assembly pathway conducts their initial synthesis and subsequent binding to recipient proteins. In this minireview, we discuss how discovery of the role of the mammalian cytosolic aconitase, known as iron regulatory protein 1 (IRP1), led to the characterization of the function of its Fe-S cluster in sensing and regulating cellular iron homeostasis. Moreover, we present an overview of recent studies that have provided insights into the mechanism of Fe-S cluster transfer to recipient Fe-S proteins. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Comprehensive phylogenetic analysis of bacterial reverse transcriptases.

PubMed

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

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.

Comprehensive Phylogenetic Analysis of Bacterial Reverse Transcriptases

PubMed Central

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

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. PMID:25423096

Intracellular Localization of Arabidopsis Sulfurtransferases1

PubMed Central

Bauer, Michael; Dietrich, Christof; Nowak, Katharina; Sierralta, Walter D.; Papenbrock, Jutta

2004-01-01

Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. In all organisms analyzed to date, small gene families encoding Str proteins have been identified. The gene products were localized to different compartments of the cells. Our interest concerns the localization of Str proteins encoded in the nuclear genome of Arabidopsis. Computer-based prediction methods revealed localization in different compartments of the cell for six putative AtStrs. Several methods were used to determine the localization of the AtStr proteins experimentally. For AtStr1, a mitochondrial localization was demonstrated by immunodetection in the proteome of isolated mitochondria resolved by one- and two-dimensional gel electrophoresis and subsequent blotting. The respective mature AtStr1 protein was identified by mass spectrometry sequencing. The same result was obtained by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts, whereas AtStr2 was exclusively localized to the cytoplasm by this method. Three members of the single-domain AtStr were localized in the chloroplasts as demonstrated by transient expression of green fluorescent protein fusions in protoplasts and stomata, whereas the single-domain AtStr18 was shown to be cytoplasmic. The remarkable subcellular distribution of AtStr15 was additionally analyzed by transmission electron immunomicroscopy using a monospecific antibody against green fluorescent protein, indicating an attachment to the thylakoid membrane. The knowledge of the intracellular localization of the members of this multiprotein family will help elucidate their specific functions in the organism. PMID:15181206

Intracellular localization of Arabidopsis sulfurtransferases.

PubMed

Bauer, Michael; Dietrich, Christof; Nowak, Katharina; Sierralta, Walter D; Papenbrock, Jutta

2004-06-01

Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. In all organisms analyzed to date, small gene families encoding Str proteins have been identified. The gene products were localized to different compartments of the cells. Our interest concerns the localization of Str proteins encoded in the nuclear genome of Arabidopsis. Computer-based prediction methods revealed localization in different compartments of the cell for six putative AtStrs. Several methods were used to determine the localization of the AtStr proteins experimentally. For AtStr1, a mitochondrial localization was demonstrated by immunodetection in the proteome of isolated mitochondria resolved by one- and two-dimensional gel electrophoresis and subsequent blotting. The respective mature AtStr1 protein was identified by mass spectrometry sequencing. The same result was obtained by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts, whereas AtStr2 was exclusively localized to the cytoplasm by this method. Three members of the single-domain AtStr were localized in the chloroplasts as demonstrated by transient expression of green fluorescent protein fusions in protoplasts and stomata, whereas the single-domain AtStr18 was shown to be cytoplasmic. The remarkable subcellular distribution of AtStr15 was additionally analyzed by transmission electron immunomicroscopy using a monospecific antibody against green fluorescent protein, indicating an attachment to the thylakoid membrane. The knowledge of the intracellular localization of the members of this multiprotein family will help elucidate their specific functions in the organism.

Synthesis and structures of cadmium carboxylate and thiocarboxylate compounds with a sulfur-rich coordination environment: Carboxylate exchange kinetics involving tris(2-mercapto-1- t-butylimidazolyl)hydroborato cadmium complexes, [Tm But]Cd(O 2CR)

DOE PAGES

Kreider-Mueller, Ava; Quinlivan, Patrick J.; Owen, Jonathan S.; ...

2015-03-31

Here, a series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2- tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm But]CdO 2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm But]CdMe with RCO 2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, and have therefore been employed to model relevant ligand exchange processes. Significantly, both 1H and 19F NMR spectroscopy demonstrate that the exchange of carboxylate groups between [Tm But]Cd(κ 2-O 2CR) and the carboxylic acid RCO 2H is facile on the NMR time scale, even at lowmore » temperature. Analysis of the rate of exchange as a function of concentration of RCO 2H indicates that reaction occurs via an associative rather than dissociative pathway. In addition to carboxylate compounds, the thiocarboxylate derivative [Tm But]Cd[κ 1-SC(O)Ph] has also been synthesized via the reaction of [Tm But]CdMe with thiobenzoic acid. The molecular structure of [Tm But]Cd[κ 1-SC(O)Ph] has been determined by X-ray diffraction, and an interesting feature is that, in contrast to the carboxylate derivatives [Tm But]Cd(κ 2-O 2CR), the thiocarboxylate ligand binds in a κ 1 manner via only the sulfur atom.« less

Synthesis and structures of cadmium carboxylate and thiocarboxylate compounds with a sulfur-rich coordination environment: Carboxylate exchange kinetics involving tris(2-mercapto-1- t-butylimidazolyl)hydroborato cadmium complexes, [Tm But]Cd(O 2CR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreider-Mueller, Ava; Quinlivan, Patrick J.; Owen, Jonathan S.

Here, a series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2- tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm But]CdO 2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm But]CdMe with RCO 2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, and have therefore been employed to model relevant ligand exchange processes. Significantly, both 1H and 19F NMR spectroscopy demonstrate that the exchange of carboxylate groups between [Tm But]Cd(κ 2-O 2CR) and the carboxylic acid RCO 2H is facile on the NMR time scale, even at lowmore » temperature. Analysis of the rate of exchange as a function of concentration of RCO 2H indicates that reaction occurs via an associative rather than dissociative pathway. In addition to carboxylate compounds, the thiocarboxylate derivative [Tm But]Cd[κ 1-SC(O)Ph] has also been synthesized via the reaction of [Tm But]CdMe with thiobenzoic acid. The molecular structure of [Tm But]Cd[κ 1-SC(O)Ph] has been determined by X-ray diffraction, and an interesting feature is that, in contrast to the carboxylate derivatives [Tm But]Cd(κ 2-O 2CR), the thiocarboxylate ligand binds in a κ 1 manner via only the sulfur atom.« less

Synthesis of Functionalized Pyrazoles via 1,3-Dipolar Cycloaddition of α-Diazo-β-ketophosphonates, Sufones and Esters with Electron-Deficient Alkenes.

PubMed

Baiju, T V; Namboothiri, Irishi N N

2017-10-01

1,3-Dipolar cycloaddition of diazo compounds with olefinic substrates is a promising atom-economic strategy for the construction of functionalized pyrazoles. Over the last few years, our group has been engaged in the synthesis of phosphonyl/sulfonylpyrazoles and pyrazole esters by employing Bestmann-Ohira Reagent (BOR) and its sulfur and ester analogs as 1,3-dipole precursors with various dipolarophiles. This account describes the novel synthetic methods developed in our laboratory, in the perspective of closely related work by others, for the synthesis of phosphonyl/sulfonylpyrazoles, pyrazole esters and the total synthesis of Withasomnine, a natural product, by using 1,3-dipolar cycloaddition as the key step. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Allostery in the ferredoxin protein motif does not involve a conformational switch.

PubMed

Nechushtai, Rachel; Lammert, Heiko; Michaeli, Dorit; Eisenberg-Domovich, Yael; Zuris, John A; Luca, Maria A; Capraro, Dominique T; Fish, Alex; Shimshon, Odelia; Roy, Melinda; Schug, Alexander; Whitford, Paul C; Livnah, Oded; Onuchic, José N; Jennings, Patricia A

2011-02-08

Regulation of protein function via cracking, or local unfolding and refolding of substructures, is becoming a widely recognized mechanism of functional control. Oftentimes, cracking events are localized to secondary and tertiary structure interactions between domains that control the optimal position for catalysis and/or the formation of protein complexes. Small changes in free energy associated with ligand binding, phosphorylation, etc., can tip the balance and provide a regulatory functional switch. However, understanding the factors controlling function in single-domain proteins is still a significant challenge to structural biologists. We investigated the functional landscape of a single-domain plant-type ferredoxin protein and the effect of a distal loop on the electron-transfer center. We find the global stability and structure are minimally perturbed with mutation, whereas the functional properties are altered. Specifically, truncating the L1,2 loop does not lead to large-scale changes in the structure, determined via X-ray crystallography. Further, the overall thermal stability of the protein is only marginally perturbed by the mutation. However, even though the mutation is distal to the iron-sulfur cluster (∼20 Å), it leads to a significant change in the redox potential of the iron-sulfur cluster (57 mV). Structure-based all-atom simulations indicate correlated dynamical changes between the surface-exposed loop and the iron-sulfur cluster-binding region. Our results suggest intrinsic communication channels within the ferredoxin fold, composed of many short-range interactions, lead to the propagation of long-range signals. Accordingly, protein interface interactions that involve L1,2 could potentially signal functional changes in distal regions, similar to what is observed in other allosteric systems.

Solvents of pus-medicines with physical-chemical aggressive action

NASA Astrophysics Data System (ADS)

Urakov, A.; Urakova, N.; Reshetnikov, A.; Kopylov, M.; Chernova, L.

2017-01-01

In laboratory and clinical conditions was studied rheology of pus and sulfuric tubes after their interaction with aqueous solutions of drugs from different pharmacological groups. It is shown that solutions of almost all medicines can influence or not influence on their rheology, because local action is determined not by the name, dose or route of administration of medicines. It is established that only physical-chemical properties of fluids and physical-chemical factors of their interaction with dense pus can give them the ability to dissolve or thickening pus. We found that deliberate change physical-chemical properties of medicines solutions from various pharmacological groups, namely, raising the temperature to +42°C, increasing the alkalinity above pH 8.1 and aeration as for example by introducing carbon dioxide under pressure of 0.2 ATM, or by introducing hydrogen peroxide in 0.5 - 3%, turning them into solvents of pus, ear wax and sulfuric tubes. Discovered that solutions of drugs with such physical-chemical activity may turn thick pus and solid sulfur tube in a homogeneous liquid after a few minutes after injecting them into these biological mass.

Health effects of sulfur-related environmental air pollution. V. Lung structure.

PubMed

Takenaka, S; Godleski, J J; Heini, A; Karg, E; Kreyling, W G; Ritter, B; Schulz, H; Ziesenis, A; Heyder, J

1999-05-01

The lungs of 8 male beagle dogs were examined morphologically and morphometrically after exposure for 13 mo to a respirable sulfur(IV) aerosol at a mass concentration of 1.53 mg m(-3) (16.5 h/day), and to an acidic sulfate aerosol carrying 15.2 micromol m(-3) hydrogen ions into the lungs (6 h/day). An additional eight dogs served as unexposed controls. Standard morphometric analyses of both the surface epithelia of the conducting airways and the alveolar region were performed. These analyses showed no difference between the exposure group and control group. However, there was a tendency to an increase in the volume density of bronchial glands in the exposure group. Five of eight exposed animals showed thickened ridges (knob-like structures) at the entrance to alveoli in the alveolar duct and alveolar sac. Transmission electron microscopy revealed that the thickening was mainly due to type II cell proliferation. As the previous experiment using sulfite aerosol only showed no alterations in the proximal alveolar regions, the changes observed may be considered as effects of acidic sulfate aerosol alone or in combination with sulfite. These findings suggest that sulfur aerosols have the potential to induce epithelial alterations in the proximal alveolar region, which is a primary target for air pollutants.

Ionic Modification Turns Commercial Rubber into a Self-Healing Material.

PubMed

Das, Amit; Sallat, Aladdin; Böhme, Frank; Suckow, Marcus; Basu, Debdipta; Wiessner, Sven; Stöckelhuber, Klaus Werner; Voit, Brigitte; Heinrich, Gert

2015-09-23

Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mechanical properties, such as the elastic modulus, tensile strength, ductility, and hysteresis loss, were found to be superior to those of conventionally sulfur-cured BIIR. This simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors.

Chemistry and Pharmacology of Thioflavones.

PubMed

Dong, Jinyun; Zhang, Qijing; Meng, Qingqing; Wang, Zengtao; Li, Shaoshun; Cui, Jiahua

2018-05-15

Thioflavone derivatives are the thio analogs of the core constituent of the natural product class of flavones. Based on the position and oxidation level of sulfur, they can be divided into three major categories: 4-thioflavones, 1-thioflavones and 1-thioflavones 1,1-dioxide. In recent years, great efforts have been made to develop an approach to thioflavones, especially 1-thioflavones with high functional group compatibility, high yields, low toxicity as well as proceeding under a mild condition, and a variety of synthetic protocols have been developed, the method of choice being dependent on the nature of substrates. As isosteric analogs of biologically active flavones, likewise thioflavones exhibit various pharmaceutical properties, such as antimicrobial, anticancer and neuroprotective activities. Replacement of the oxygen atom on flavone skeleton by a sulfur atom resulted in modified biological effects due in most part to the change of structural properties. However, these varying effects depend on the substituents present and the test species. To provide a comprehensive vision of this class of compounds, this review primarily focuses on the structure, synthetic methods, biological properties as well as structure-activity relationships of thioflavones. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Enzymatic Synthesis of Amino Acids Endcapped Polycaprolactone: A Green Route Towards Functional Polyesters.

PubMed

Duchiron, Stéphane W; Pollet, Eric; Givry, Sébastien; Avérous, Luc

2018-01-30

ε-caprolactone (CL) has been enzymatically polymerized using α-amino acids based on sulfur (methionine and cysteine) as (co-)initiators and immobilized lipase B of Candida antarctica (CALB) as biocatalyst. In-depth characterizations allowed determining the corresponding involved mechanisms and the polymers thermal properties. Two synthetic strategies were tested, a first one with direct polymerization of CL with the native amino acids and a second one involving the use of an amino acid with protected functional groups. The first route showed that mainly polycaprolactone (PCL) homopolymer could be obtained and highlighted the lack of reactivity of the unmodified amino acids due to poor solubility and affinity with the lipase active site. The second strategy based on protected cysteine showed higher monomer conversion, with the amino acids acting as (co-)initiators, but their insertion along the PCL chains remained limited to chain endcapping. These results thus showed the possibility to synthesize enzymatically polycaprolactone-based chains bearing amino acids units. Such cysteine endcapped PCL materials could then find application in the biomedical field. Indeed, subsequent functionalization of these polyesters with drugs or bioactive molecules can be obtained, by derivatization of the amino acids, after removal of the protecting group.

Investigation of metal-dithiolate fold angle effects: implications for molybdenum and tungsten enzymes.

PubMed

Joshi, Hemant K; Cooney, J Jon A; Inscore, Frank E; Gruhn, Nadine E; Lichtenberger, Dennis L; Enemark, John H

2003-04-01

Gas-phase photoelectron spectroscopy and density functional theory have been used to investigate the interactions between the sulfur pi-orbitals of arene dithiolates and high-valent transition metals as minimum molecular models of the active site features of pyranopterin MoW enzymes. The compounds (Tp*)MoO(bdt) (compound 1), Cp(2)Mo(bdt) (compound 2), and Cp(2)Ti(bdt) (compound 3) [where Tp* is hydrotris(3,5-dimethyl-1-pyrazolyl)borate, bdt is 1,2-benzenedithiolate, and Cp is eta(5)- cyclopentadienyl] provide access to three different electronic configurations of the metal, formally d(1), d(2), and d(0), respectively. The gas-phase photoelectron spectra show that ionizations from occupied metal and sulfur based valence orbitals are more clearly observed in compounds 2 and 3 than in compound 1. The observed ionization energies and characters compare very well with those calculated by density functional theory. A "dithiolate-folding-effect" involving an interaction of the metal in-plane and sulfur-pi orbitals is proposed to be a factor in the electron transfer reactions that regenerate the active sites of molybdenum and tungsten enzymes.

Replacing Nitrogen by Sulfur: From Structurally Disordered Eumelanins to Regioregular Thiomelanin Polymers

PubMed Central

Iacomino, Mariagrazia; Mancebo-Aracil, Juan; Guardingo, Mireia; Martín, Raquel; Perfetti, Marco; Manini, Paola; Crescenzi, Orlando; Busqué, Félix; Sedó, Josep; Ruiz-Molina, Daniel

2017-01-01

The oxidative polymerization of 5,6-dihydroxybenzothiophene (DHBT), the sulfur analog of the key eumelanin building block 5,6-dihydroxyindole (DHI), was investigated to probe the role of nitrogen in eumelanin build-up and properties. Unlike DHI, which gives a typical black insoluble eumelanin polymer on oxidation, DHBT is converted to a grayish amorphous solid (referred to as thiomelanin) with visible absorption and electron paramagnetic resonance properties different from those of DHI melanin. Mass spectrometry experiments revealed gradational mixtures of oligomers up to the decamer level. Quite unexpectedly, nuclear magnetic resonance (NMR) analysis of the early oligomer fractions indicated linear, 4-, and 7-linked structures in marked contrast with DHI, which gives highly complex mixtures of partially degraded oligomers. Density functional theory (DFT) calculations supported the tendency of DHBT to couple via the 4- and 7-positions. These results uncover the role of nitrogen as a major determinant of the structural diversity generated by the polymerization of DHI, and point to replacement by sulfur as a viable entry to regioregular eumelanin-type materials for potential applications for surface functionalization by dip coating. PMID:29039817

Evidence for hydrogen oxidation and metabolic plasticity in widespread deep-sea sulfur-oxidizing bacteria.

PubMed

Anantharaman, Karthik; Breier, John A; Sheik, Cody S; Dick, Gregory J

2013-01-02

Hydrothermal vents are a well-known source of energy that powers chemosynthesis in the deep sea. Recent work suggests that microbial chemosynthesis is also surprisingly pervasive throughout the dark oceans, serving as a significant CO(2) sink even at sites far removed from vents. Ammonia and sulfur have been identified as potential electron donors for this chemosynthesis, but they do not fully account for measured rates of dark primary production in the pelagic water column. Here we use metagenomic and metatranscriptomic analyses to show that deep-sea populations of the SUP05 group of uncultured sulfur-oxidizing Gammaproteobacteria, which are abundant in widespread and diverse marine environments, contain and highly express genes encoding group 1 Ni, Fe hydrogenase enzymes for H(2) oxidation. Reconstruction of near-complete genomes of two cooccurring SUP05 populations in hydrothermal plumes and deep waters of the Gulf of California enabled detailed population-specific metatranscriptomic analyses, revealing dynamic patterns of gene content and transcript abundance. SUP05 transcripts for genes involved in H(2) and sulfur oxidation are most abundant in hydrothermal plumes where these electron donors are enriched. In contrast, a second hydrogenase has more abundant transcripts in background deep-sea samples. Coupled with results from a bioenergetic model that suggest that H(2) oxidation can contribute significantly to the SUP05 energy budget, these findings reveal the potential importance of H(2) as a key energy source in the deep ocean. This study also highlights the genomic plasticity of SUP05, which enables this widely distributed group to optimize its energy metabolism (electron donor and acceptor) to local geochemical conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nancy Ryan Gray

Iron-sulfur (FeS) centers are essential for biology and inspirational in chemistry. These protein cofactors are broadly defined as active sites in which Fe is coordinated by S-donor ligands, often in combination with extra non-protein components, for example, additional metal atoms such as Mo and Ni, and soft ligands such as CN{sup -} and CO. Iron-sulfur centers are inherently air sensitive: they are found in essentially all organisms and it is possible that they were integral components of the earliest forms of life, well before oxygen (O{sub 2}) appeared. Proteins containing FeS cofactors perform a variety of biological functions ranging acrossmore » electron transfer, acid-base catalysis, and sensing where they are agents for cell regulation through transcription (DNA) or translation (RNA). They are redox catalysts for radical-based reactions and the activation of H{sub 2}, N{sub 2} and CO{sub 2}, processes that offer scientific and economic challenges for industry. Iron-sulfur centers provide the focus for fundamental investigations of chemical bonding, spectroscopy and paramagnetism, and their functions have numerous implications for health and medicine and applications for technology, including renewable energy. The 2010 Iron-Sulfur Enzymes GRC will bring together researchers from different disciplines for in-depth discussions and presentations of the latest developments. There will be sessions on structural and functional analogues of FeS centers, advances in physical methods, roles of FeS centers in energy and technology, catalysis (including radical-based rearrangements and the activation of nitrogen, hydrogen and carbon), long-range electron transfer, FeS centers in health and disease, cellular regulation, cofactor assembly, their relevance in industry, and experiments and hypotheses relating to the origins of life.« less

Proteomic Analysis Reveals a Novel Function of the Kinase Sat4p in Saccharomyces cerevisiae Mitochondria

PubMed Central

Gey, Uta; Czupalla, Cornelia; Hoflack, Bernard; Krause, Udo; Rödel, Gerhard

2014-01-01

The Saccharomyces cerevisiae kinase Sat4p has been originally identified as a protein involved in salt tolerance and stabilization of plasma membrane transporters, implicating a cytoplasmic localization. Our study revealed an additional mitochondrial (mt) localization, suggesting a dual function for Sat4p. While no mt related phenotype was observed in the absence of Sat4p, its overexpression resulted in significant changes of a specific mitochondrial subproteome. As shown by a comparative two dimensional difference gel electrophoresis (2D-DIGE) approach combined with mass spectrometry, particularly two groups of proteins were affected: the iron-sulfur containing aconitase-type proteins (Aco1p, Lys4p) and the lipoamide-containing subproteome (Lat1p, Kgd2p and Gcv3p). The lipoylation sites of all three proteins could be assigned by nanoLC-MS/MS to Lys75 (Lat1p), Lys114 (Kgd2p) and Lys102 (Gcv3p), respectively. Sat4p overexpression resulted in accumulation of the delipoylated protein variants and in reduced levels of aconitase-type proteins, accompanied by a decrease in the activities of the respective enzyme complexes. We propose a regulatory role of Sat4p in the late steps of the maturation of a specific subset of mitochondrial iron-sulfur cluster proteins, including Aco1p and lipoate synthase Lip5p. Impairment of the latter enzyme may account for the observed lipoylation defects. PMID:25117470

Density functional theory investigation of opto-electronic properties of thieno[3,4-b]thiophene and benzodithiophene polymer and derivatives and their applications in solar cell

NASA Astrophysics Data System (ADS)

Khoshkholgh, Mehri Javan; Marsusi, Farah; Abolhassani, Mohammad Reza

2015-02-01

PTBs polymers with thieno[3,4-b]thiophene [TT] and benzodithiophene [BDT] units have particular properties, which demonstrate it as one of the best group of donor materials in organic solar cells. In the present work, density functional theory (DFT) is applied to investigate the optimized structure, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), band gap and dihedral angle of PTB7 at B3LYP/6-31G(d). Two different approaches are applied to carry out these investigations: Oligomer extrapolation technique and periodic boundary condition (PBC) method. The results obtained from PBC-DFT method are in fair agreement with experiments. Based on these reliable outcomes; the investigations continued to perform some derivatives of PTB7. In this study, sulfur is substituted by nitrogen, oxygen, silicon, phosphor or selenium atoms in pristine PTB7. Due to the shift of HOMO and LUMO levels, smaller band gaps are predicted to appear in some derivatives in comparison with PTB7. Maximum theoretical efficiencies, η, of the mentioned derivatives as well as local difference of dipole moments between the ground and excited states (Δμge) are computed. The results indicate that substitution of sulfur by nitrogen or oxygen in BDT unit, and silicon or phosphor in TT unit of pristine PTB7 leads to a higher η as well as Δμge.

Density functional theory investigation of opto-electronic properties of thieno[3,4-b]thiophene and benzodithiophene polymer and derivatives and their applications in solar cell.

PubMed

Khoshkholgh, Mehri Javan; Marsusi, Farah; Abolhassani, Mohammad Reza

2015-02-05

PTBs polymers with thieno[3,4-b]thiophene [TT] and benzodithiophene [BDT] units have particular properties, which demonstrate it as one of the best group of donor materials in organic solar cells. In the present work, density functional theory (DFT) is applied to investigate the optimized structure, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), band gap and dihedral angle of PTB7 at B3LYP/6-31G(d). Two different approaches are applied to carry out these investigations: Oligomer extrapolation technique and periodic boundary condition (PBC) method. The results obtained from PBC-DFT method are in fair agreement with experiments. Based on these reliable outcomes; the investigations continued to perform some derivatives of PTB7. In this study, sulfur is substituted by nitrogen, oxygen, silicon, phosphor or selenium atoms in pristine PTB7. Due to the shift of HOMO and LUMO levels, smaller band gaps are predicted to appear in some derivatives in comparison with PTB7. Maximum theoretical efficiencies, η, of the mentioned derivatives as well as local difference of dipole moments between the ground and excited states (Δμge) are computed. The results indicate that substitution of sulfur by nitrogen or oxygen in BDT unit, and silicon or phosphor in TT unit of pristine PTB7 leads to a higher η as well as Δμge. Copyright © 2014 Elsevier B.V. All rights reserved.

NMR- and GC/MS-based metabolomics of sulfur mustard exposed individuals: a pilot study.

PubMed

Nobakht, B Fatemeh; Aliannejad, Rasoul; Rezaei-Tavirani, Mostafa; Arefi Oskouie, Afsaneh; Naseri, Mohammad Taghi; Parastar, Hadi; Aliakbarzadeh, Ghazaleh; Fathi, Fariba; Taheri, Salman

2016-09-01

Sulfur mustard (SM) is a potent alkylating agent and its effects on cells and tissues are varied and complex. Due to limitations in the diagnostics of sulfur mustard exposed individuals (SMEIs) by noninvasive approaches, there is a great necessity to develop novel techniques and biomarkers for this condition. We present here the first nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC/MS) metabolic profiling of serum from and healthy controls to identify novel biomarkers in blood serum for better diagnostics. Of note, SMEIs were exposed to SM 30 years ago and that differences between two groups could still be found. Pathways in which differences between SMEIs and healthy controls are observed are related to lipid metabolism, ketogenesis, tricarboxylic acid (TCA) cycle and amino acid metabolism.

Preparation of Nickel Cobalt Sulfide Hollow Nanocolloids with Enhanced Electrochemical Property for Supercapacitors Application

PubMed Central

Chen, Zhenhua; Wan, Zhanghui; Yang, Tiezhu; Zhao, Mengen; Lv, Xinyan; Wang, Hao; Ren, Xiuli; Mei, Xifan

2016-01-01

Nanostructured functional materials with hollow interiors are considered to be good candidates for a variety of advanced applications. However, synthesis of uniform hollow nanocolloids with porous texture via wet chemistry method is still challenging. In this work, nickel cobalt precursors (NCP) in sub-micron sized spheres have been synthesized by a facile solvothermal method. The subsequent sulfurization process in hydrothermal system has changed the NCP to nickel cobalt sulfide (NCS) with porous texture. Importantly, the hollow interiors can be tuned through the sulfurization process by employing different dosage of sulfur source. The derived NCS products have been fabricated into supercapacitor electrodes and their electrochemical performances are measured and compared, where promising results were found for the next-generation high-performance electrochemical capacitors. PMID:27114165

Seebeck and figure of merit enhancement in nanostructured antimony telluride by antisite defect suppression through sulfur doping.

PubMed

Mehta, Rutvik J; Zhang, Yanliang; Zhu, Hong; Parker, David S; Belley, Matthew; Singh, David J; Ramprasad, Ramamurthy; Borca-Tasciuc, Theodorian; Ramanath, Ganpati

2012-09-12

Antimony telluride has a low thermoelectric figure of merit (ZT < ∼0.3) because of a low Seebeck coefficient α arising from high degenerate hole concentrations generated by antimony antisite defects. Here, we mitigate this key problem by suppressing antisite defect formation using subatomic percent sulfur doping. The resultant 10-25% higher α in bulk nanocrystalline antimony telluride leads to ZT ∼ 0.95 at 423 K, which is superior to the best non-nanostructured antimony telluride alloys. Density functional theory calculations indicate that sulfur increases the antisite formation activation energy and presage further improvements leading to ZT ∼ 2 through optimized doping. Our findings are promising for designing novel thermoelectric materials for refrigeration, waste heat recovery, and solar thermal applications.

Sulfur K-edge XAS of WV=O vs. MoV=O Bis(dithiolene) Complexes: Contributions of Relativistic Effects to Electronic Structure and Reactivity of Tungsten Enzymes†

PubMed Central

Tenderholt, Adam L.; Szilagyi, Robert K.; Holm, Richard H.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.

2009-01-01

Molybdenum- or tungsten-containing enzymes catalyze oxygen atom transfer reactions involved in carbon, sulfur, or nitrogen metabolism. It has been observed that reduction potentials and oxygen atom transfer rates are different for W relative to Mo enzymes and the isostructural Mo/W complexes. Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations on [MoVO(bdt)2]− and [WVO(bdt)2]−, where bdt = benzene-1,2-dithiolate(2−), have been used to determine that the energies of the half-filled redox-active orbital, and thus the reduction potentials and M=O bond strengths, are different for these complexes due to relativistic effects in the W sites. PMID:17720249

X-ray crystallographic analysis of the sulfur carrier protein SoxY from Chlorobium limicola f. thiosulfatophilum reveals a tetrameric structure

PubMed Central

Stout, Jan; Van Driessche, Gonzalez; Savvides, Savvas N.; Van Beeumen, Jozef

2007-01-01

Dissimilatory oxidation of thiosulfate in the green sulfur bacterium Chlorobium limicola f. thiosulfatophilum is carried out by the ubiquitous sulfur-oxidizing (Sox) multi-enzyme system. In this system, SoxY plays a key role, functioning as the sulfur substrate-binding protein that offers its sulfur substrate, which is covalently bound to a conserved C-terminal cysteine, to another oxidizing Sox enzyme. Here, we report the crystal structures of a stand-alone SoxY protein of C. limicola f. thiosulfatophilum, solved at 2.15 Å and 2.40 Å resolution using X-ray diffraction data collected at 100 K and room temperature, respectively. The structure reveals a monomeric Ig-like protein, with an N-terminal α-helix, that oligomerizes into a tetramer via conserved contact regions between the monomers. The tetramer can be described as a dimer of dimers that exhibits one large hydrophobic contact region in each dimer and two small hydrophilic interface patches in the tetramer. At the tetramer interface patch, two conserved redox-active C-terminal cysteines form an intersubunit disulfide bridge. Intriguingly, SoxY exhibits a dimer/tetramer equilibrium that is dependent on the redox state of the cysteines and on the type of sulfur substrate component bound to them. Taken together, the dimer/tetramer equilibrium, the specific interactions between the subunits in the tetramer, and the significant conservation level of the interfaces strongly indicate that these SoxY oligomers are biologically relevant. PMID:17327392

Iron-Sulfur Cluster Engineering Provides Insight into the Evolution of Substrate Specificity among Sulfonucleotide Reductases

PubMed Central

Bhave, Devayani P.; Hong, Jiyoung A.; Keller, Rebecca L.; Krebs, Carsten; Carroll, Kate S.

2011-01-01

Assimilatory sulfate reduction supplies prototrophic organisms with reduced sulfur that is required for the biosynthesis of all sulfur-containing metabolites, including cysteine and methionine. The reduction of sulfate requires its activation via an ATP-dependent activation to form adenosine-5′-phosphosulfate (APS). Depending on the species, APS can be reduced directly to sulfite by APS reductase (APR) or undergo a second phosphorylation to yield 3′-phosphoadenosine-5′-phosphosulfate (PAPS), the substrate for PAPS reductase (PAPR). These essential enzymes have no human homolog, rendering them attractive targets for the development of novel antibacterial drugs. APR and PAPR share sequence and structure homology as well as a common catalytic mechanism, but the enzymes are distinguished by two features, namely, the amino acid sequence of the phosphate-binding loop (P-loop) and an iron-sulfur cofactor in APRs. Based on the crystal structures of APR and PAPR, two P-loop residues are proposed to determine substrate specificity; however, this hypothesis has not been tested. In contrast to this prevailing view, we report here that the P-loop motif has a modest effect on substrate discrimination. Instead, by means of metalloprotein engineering, spectroscopic and kinetic analyses, we demonstrate that the iron-sulfur cluster cofactor enhances APS reduction by nearly 1000-fold, thereby playing a pivotal role in substrate specificity and catalysis. These findings offer new insights into the evolution of this enzyme family, and extend the known functions of protein-bound iron-sulfur clusters. PMID:22023093

Pyrobaculum yellowstonensis Strain WP30 Respires on Elemental Sulfur and/or Arsenate in Circumneutral Sulfidic Geothermal Sediments of Yellowstone National Park

PubMed Central

Jay, Z. J.; Beam, J. P.; Dohnalkova, A.; Lohmayer, R.; Bodle, B.; Planer-Friedrich, B.; Romine, M.

2015-01-01

Thermoproteales (phylum Crenarchaeota) populations are abundant in high-temperature (>70°C) environments of Yellowstone National Park (YNP) and are important in mediating the biogeochemical cycles of sulfur, arsenic, and carbon. The objectives of this study were to determine the specific physiological attributes of the isolate Pyrobaculum yellowstonensis strain WP30, which was obtained from an elemental sulfur sediment (Joseph's Coat Hot Spring [JCHS], 80°C, pH 6.1, 135 μM As) and relate this organism to geochemical processes occurring in situ. Strain WP30 is a chemoorganoheterotroph and requires elemental sulfur and/or arsenate as an electron acceptor. Growth in the presence of elemental sulfur and arsenate resulted in the formation of thioarsenates and polysulfides. The complete genome of this organism was sequenced (1.99 Mb, 58% G+C content), revealing numerous metabolic pathways for the degradation of carbohydrates, amino acids, and lipids. Multiple dimethyl sulfoxide-molybdopterin (DMSO-MPT) oxidoreductase genes, which are implicated in the reduction of sulfur and arsenic, were identified. Pathways for the de novo synthesis of nearly all required cofactors and metabolites were identified. The comparative genomics of P. yellowstonensis and the assembled metagenome sequence from JCHS showed that this organism is highly related (∼95% average nucleotide sequence identity) to in situ populations. The physiological attributes and metabolic capabilities of P. yellowstonensis provide an important foundation for developing an understanding of the distribution and function of these populations in YNP. PMID:26092468

Pyrobaculum Yellowstonensis Strain WP30 Respires On Elemental Sulfur And/or Arsenate in Circumneutral Sulfidic Sediments of Yellowstone National Park

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jay, Z.; Beam, Jake; Dohnalkova, Alice

Thermoproteales populations (phylum Crenarchaeota) are abundant in high-25 temperature (>70° C) environments of Yellowstone National Park (YNP) and are important in mediating biogeochemical cycles of sulfur, arsenic and carbon. The objectives of this study were to determine specific physiological attributes of the isolate Pyrobaculum yellowstonensis strain WP30, which was obtained from an elemental sulfur sediment (Joseph’s Coat Hot Spring [JCHS]; 80 °C; pH 6.1), and relate this organism to geochemical processes occurring in situ. Strain WP30 is a chemoheterotroph that utilizes organic carbon as a source of carbon and electrons and requires elemental sulfur and/or arsenic as electron acceptors. Growthmore » in the presence of elemental sulfur and arsenate resulted in the production of thioarsenates and polysulfides relative to sterile controls. The complete genome of this organism was sequenced (1.99 Mb, 58 % G+C) and revealed numerous metabolic pathways for the degradation of carbohydrates, amino acids and lipids, multiple dimethylsulfoxide molybdopterin (DMSO-MPT) oxidoreductase genes, which are implicated in the reduction of sulfur and arsenic, and pathways for the de novo synthesis of nearly all required cofactors and metabolites. Comparative genomics of P. yellowstonensis versus assembled metagenome sequence from JCHS showed that this organisms is highly-related (~95% average nucleotide identity) to in situ populations. The physiological attributes and metabolic capabilities of P. yellowstonensis provide importanat information towards understanding the distribution and function of these populations in YNP.« less

Variable sulfur isotope composition of sulfides provide evidence for multiple sources of contamination in the Rustenburg Layered Suite, Bushveld Complex

NASA Astrophysics Data System (ADS)

Magalhães, Nivea; Penniston-Dorland, Sarah; Farquhar, James; Mathez, Edmond A.

2018-06-01

The Rustenburg Layered Suite (RLS) of the Bushveld Complex (BC) is famous for its platinum group element (PGE) ore, which is hosted in sulfides. The source of sulfur necessary to generate this type of mineralization is inferred to be the host rock of the intrusion. The RLS has a sulfur isotopic signature that indicates the presence of Archean surface-derived material (Δ33 S ≠ 0) in the magma. This signature, with an average value of Δ33 S = 0.112 ± 0.024 ‰, deviates from the expected Δ33 S value of the mantle of 0 ± 0.008 ‰. Previous work suggested that this signature is uniform throughout the RLS, which contrasts with radiogenic isotopes which vary throughout the igneous stratigraphy of the RLS. In this study, samples from key intervals within the igneous stratigraphy were analyzed, showing that Δ33 S values vary in the same stratigraphic levels as Sr and Nd isotopes. However, the variation is not consistent; in some levels there is a positive correlation and in others a negative correlation. This observation suggests that in some cases distinct magma pulses contained assimilated sulfur from different sources. Textural analysis shows no evidence for late addition of sulfur. These results also suggest that it is unlikely that large-scale assimilation and/or efficient mixing of host rock material in a single magma chamber occurred during emplacement. The data do not uniquely identify the source of sulfur in the different layers of the RLS, but the variation in sulfur isotope composition and its relationship to radiogenic isotope data calls for a reevaluation of the models for the formation and evolution of the RLS, which has the potential to impact the knowledge of how PGE deposits form.

A fuel-cell-assisted iron redox process for simultaneous sulfur recovery and electricity production from synthetic sulfide wastewater.

PubMed

Zhai, Lin-Feng; Song, Wei; Tong, Zhong-Hua; Sun, Min

2012-12-01

Sulfide present in wastewaters and waste gases should be removed due to its toxicity, corrosivity, and malodorous property. Development of effective, stable, and feasible methods for sulfur recovery from sulfide attains a double objective of waste minimization and resource recovery. Here we report a novel fuel-cell-assisted iron redox (FC-IR) process for simultaneously recovering sulfur and electricity from synthetic sulfide wastewater. The FC-IR system consists of an oxidizing reactor where sulfide is oxidized to elemental sulfur by Fe(III), and a fuel cell where Fe(III) is regenerated from Fe(II) concomitantly with electricity producing. The oxidation of sulfide by Fe(III) is significantly dependent on solution pH. Increasing the pH from 0.88 to 1.96 accelerates the oxidation of sulfide, however, lowers the purity of the produced elemental sulfur. The performance of fuel cell is also a strong function of solution pH. Fe(II) is completely oxidized to Fe(III) when the fuel cell is operated at a pH above 6.0, whereas only partially oxidized below pH 6.0. At pH 6.0, the highest columbic efficiency of 75.7% is achieved and electricity production maintains for the longest time of 106 h. Coupling operation of the FC-IR system obtains sulfide removal efficiency of 99.90%, sulfur recovery efficiency of 78.6 ± 8.3%, and columbic efficiency of 58.6 ± 1.6%, respectively. These results suggest that the FC-IR process is a promising tool to recover sulfur and energy from sulfide. Copyright © 2012 Elsevier B.V. All rights reserved.

Atomic Sulfur Anchored on Silicene, Phosphorene, and Borophene for Excellent Cycle Performance of Li-S Batteries.

PubMed

Li, Fen; Zhao, Jijun

2017-12-13

Dissolution of intermediate lithium polysulfides (LiPS) is an inevitable obstacle for the solid sulfur-based cathode in Li-S batteries. For the first time, herein, atomic sulfur is incorporated into silicene, phosphorene, and borophene to intrinsically eliminate the dissolution of LiPS. The small molecular sulfur species are anchored on the silicene surface with stronger Si-S interaction than the P-S and B-S ones. Meanwhile, a high atomic sulfur coverage (63.1 wt %) is achieved in silicene and concomitantly stabilizes the silicene layer. For the S 3 -covered silicene, a high theoretical capacity of 857 mA h g -1 is achieved with slight dissolution of LiPS originated from the loss of interior S atoms that are not directly bound with silicene surface. By realizing the elemental S 2 coverage on silicene with large surface area, the Li + ions can react fast with the S 2 species, leading to a high theoretical capacity of 891 mA h g -1 without dissolution and migration of the intermediate LiPS. Most interestingly, the discharge products of atomic layer of lithium sulfides on silicene surface exhibit completely different behaviors from the traditional discharge products of solid Li 2 S, which can function as effective adsorption and activation sites for the conversion of LiPS from long chain to short chain by accelerated redox reaction. The present study gains some key insights into how the atomic sulfur contributes to the intrinsic shuttle inhibition and offers a feasible way to design the atomic sulfur-based cathode materials of Li-S batteries with better electrochemical performance.

Sandwich-Type Nitrogen and Sulfur Codoped Graphene-Backboned Porous Carbon Coated Separator for High Performance Lithium-Sulfur Batteries.

PubMed

Chen, Feng; Ma, Lulu; Ren, Jiangang; Luo, Xinyu; Liu, Bibo; Zhou, Xiangyang

2018-03-26

Lithium-sulfur (Li-S) batteries have been identified as the greatest potential next- generation energy-storage systems because of the large theoretical energy density of 2600 Wh kg -1 . However, its practical application on a massive scale is impeded by severe capacity loss resulted from the notorious polysulfides shuttle. Here, we first present a novel technique to synthesize sandwich-type nitrogen and sulfur codoped graphene-backboned porous carbon (NSGPC) to modify the commercial polypropylene separator in Li-S batteries. The as-synthesized NSGPC exhibits a unique micro/mesoporous carbon framework, large specific surface area (2439.0 m² g -1 ), high pore volume (1.78 cm³ g -1 ), good conductivity, and in situ nitrogen (1.86 at %) and sulfur (5.26 at %) co-doping. Benefiting from the particular physical properties and chemical components of NSGPC, the resultant NSGPC-coated separator not only can facilitate rapid Li⁺ ions and electrons transfer, but also can restrict the dissolution of polysulfides to alleviate the shuttle effect by combining the physical absorption and strong chemical adsorption. As a result, Li-S batteries with NSGPC-coated separator exhibit high initial reversible capacity (1208.6 mAh g -1 at 0.2 C), excellent rate capability (596.6 mAh g -1 at 5 C), and superior cycling stability (over 500 cycles at 2 C with 0.074% capacity decay each cycle). Propelling our easy-designed pure sulfur cathode to a extremely increased mass loading of 3.4 mg cm -2 (70 wt. % sulfur), the Li-S batteries with this functional composite separator exhibit a superior high initial capacity of 1171.7 mAh g -1 , which is quite beneficial to commercialized applications.

Sandwich-Type Nitrogen and Sulfur Codoped Graphene-Backboned Porous Carbon Coated Separator for High Performance Lithium-Sulfur Batteries

PubMed Central

Chen, Feng; Ma, Lulu; Ren, Jiangang; Luo, Xinyu; Liu, Bibo; Zhou, Xiangyang

2018-01-01

Lithium-sulfur (Li-S) batteries have been identified as the greatest potential next- generation energy-storage systems because of the large theoretical energy density of 2600 Wh kg−1. However, its practical application on a massive scale is impeded by severe capacity loss resulted from the notorious polysulfides shuttle. Here, we first present a novel technique to synthesize sandwich-type nitrogen and sulfur codoped graphene-backboned porous carbon (NSGPC) to modify the commercial polypropylene separator in Li-S batteries. The as-synthesized NSGPC exhibits a unique micro/mesoporous carbon framework, large specific surface area (2439.0 m2 g−1), high pore volume (1.78 cm3 g−1), good conductivity, and in situ nitrogen (1.86 at %) and sulfur (5.26 at %) co-doping. Benefiting from the particular physical properties and chemical components of NSGPC, the resultant NSGPC-coated separator not only can facilitate rapid Li+ ions and electrons transfer, but also can restrict the dissolution of polysulfides to alleviate the shuttle effect by combining the physical absorption and strong chemical adsorption. As a result, Li-S batteries with NSGPC-coated separator exhibit high initial reversible capacity (1208.6 mAh g−1 at 0.2 C), excellent rate capability (596.6 mAh g−1 at 5 C), and superior cycling stability (over 500 cycles at 2 C with 0.074% capacity decay each cycle). Propelling our easy-designed pure sulfur cathode to a extremely increased mass loading of 3.4 mg cm−2 (70 wt. % sulfur), the Li-S batteries with this functional composite separator exhibit a superior high initial capacity of 1171.7 mAh g−1, which is quite beneficial to commercialized applications. PMID:29587467

Dealing with methionine/homocysteine sulfur: cysteine metabolism to taurine and inorganic sulfur

PubMed Central

Ueki, Iori

2010-01-01

Synthesis of cysteine as a product of the transsulfuration pathway can be viewed as part of methionine or homocysteine degradation, with cysteine being the vehicle for sulfur conversion to end products (sulfate, taurine) that can be excreted in the urine. Transsulfuration is regulated by stimulation of cystathionine β-synthase and inhibition of methylene tetrahydrofolate reductase in response to changes in the level of S-adenosylmethionine, and this promotes homocysteine degradation when methionine availability is high. Cysteine is catabolized by several desulfuration reactions that release sulfur in a reduced oxidation state, generating sulfane sulfur or hydrogen sulfide (H2S), which can be further oxidized to sulfate. Cysteine desulfuration is accomplished by alternate reactions catalyzed by cystathionine β-synthase and cystathionine γ-lyase. Cysteine is also catabolized by pathways that require the initial oxidation of the cysteine thiol by cysteine dioxygenase to form cysteinesulfinate. The oxidative pathway leads to production of taurine and sulfate in a ratio of approximately 2:1. Relative metabolism of cysteine by desulfuration versus oxidative pathways is influenced by cysteine dioxygenase activity, which is low in animals fed low-protein diets and high in animals fed excess sulfur amino acids. Thus, desulfuration reactions dominate when cysteine is deficient, whereas oxidative catabolism dominates when cysteine is in excess. In rats consuming a diet with an adequate level of sulfur amino acids, about two thirds of cysteine catabolism occurs by oxidative pathways and one third by desulfuration pathways. Cysteine dioxygenase is robustly regulated in response to cysteine availability and may function to provide a pathway to siphon cysteine to less toxic metabolites than those produced by cysteine desulfuration reactions. PMID:20162368

J-pouch versus Roux-en-Y reconstruction after gastrectomy: functional assessment and quality of life (randomized trial).

PubMed

Zonča, Pavel; Malý, Tomáš; Ihnát, Peter; Peteja, Matus; Kraft, Otakar; Kuca, Kamil

2017-01-01

The aim of this study was to evaluate the quality of life and functional emptying of J-pouch versus Roux-en-Y reconstruction after total gastrectomy for malignancy. This study was designed as a prospective, nonblinded, randomized, parallel clinical trial (Trial Number: MN Ostrava, 200604). With informed consent, patients undergoing gastrectomy for malignancy were randomized to J-pouch or Roux-en-Y reconstruction. The time taken for a test semisolid meal labeled with 99m Tc-sulfur colloid to exit the reconstructed parts was measured by dynamic scintigraphy 1 year after resection. Quality of life was measured using the Eypasch questionnaire at the same time as functional emptying assessment. This trial was investigator-initiated. In all, 72 patients were included into the study. The time taken for the test meal to exit the postgastrectomy reconstruction was 16.5±10.0 minutes (mean ± standard deviation) in the Roux-en-Y group and 89.4±37.8 minutes in the "J-pouch" group; the difference was statistically significant ( P <0.001). Emptying of the J-pouch appeared to be a linear decreasing function compared to the exponential pattern seen in the Roux-en-Y group. The quality of life measurement showed scores of 106±18.8 points (mean ± standard deviation) in the Roux-en-Y group compared to 122±22.5 points in the J-pouch group; the difference was statistically significant ( P =0.0016). There were no important adverse events. After total gastrectomy, a J-pouch reconstruction empties more slowly and is associated with higher quality of life compared to Roux-en-Y reconstruction. Whether these two observations have a direct causative link remains unanswered.

Cu-Fe-S Nanocrystals Exhibiting Tunable Localized Surface Plasmon Resonance in the Visible to NIR Spectral Ranges.

PubMed

Gabka, Grzegorz; Bujak, Piotr; Ostrowski, Andrzej; Tomaszewski, Waldemar; Lisowski, Wojciech; Sobczak, Janusz W; Pron, Adam

2016-07-05

Cu-Fe-S nanocrystals exhibiting a strong localized surface plasmon resonance (LSPR) effect were synthesized for the first time. The elaborated reproducible preparation procedure involved copper(II) oleate, iron(III) stearate, and sulfur powder dissolved in oleylamine (OLA) as precursors. The wavelength of the plasmonic resonance maximum could be tuned by changing the Cu/Fe ratio in the resulting nanocrystals, being the most energetic for the 1:1 ratio (486 nm) and undergoing a bathochromic shift to ca. 1200 nm with an increase to 6:1. LSPR could also be observed in nanocrystals prepared from the same metal precursors and sulfur powder dissolved in 1-octadecene (ODE), provided that the sulfur precursor was taken in excess. Detailed analysis of the reaction mixture by chromatographic techniques, supplemented by mass spectrometry and (1)H NMR spectroscopy enabled the identification of the true chemical nature of the sulfur precursor in S/OLA, namely, (C18H35NH3(+))(C18H35NH-S8(-)), a reactive product of the reduction of elemental sulfur by the amine groups of OLA. In the case of the S/ODE precursor, the true precursors are much less reactive primary or secondary thioethers and dialkyl polysulfides.

A MASS-SPECTROMETRIC INVESTIGATION OF SULFUR VAPOR AS A FUNCTION OF TEMPERATURE (thesis)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zietz, M.C.

1960-06-15

A mass-spectrometric investigation was performed on sulfur vapor in equilibrium with the condensed phase at 120 to 210 gas-cooled C. It was found that, in this temperature range, equilibrium sulfur vapor contains appreciable quantities of S/sub 8/, S/sub 7/, S/sub 6/, and S/sub 5/ only. The sulfur vapor emanated as a small well-collimated molecular beam from a specially constructed source into an ionization chamber which was designed to exclude from analysis any sulfur vapor that had impinged on the walls or the hot electron filament. Essential identical ionization potentials were determined for S/sub 8/ , S/sub 7/, S/sub 6/, andmore » S/sub 5/ of 9.8 0.4 ev. The heat of vaporizati on of S/sub 7/ was calculated to be approximately 2.5 kcal greater than that of S/ sub 8/. Upper limits for S/sub 8/ and S/sub 7/ composition in S vapor at 120 gas- cooled C were determined to be 86% and 14%, respectively. It is proposed thst S/sub 8/ is the vaporizing species, that S/sub 7/, S/sub 6/, and S/sub 5/ result from dissociation of S/sub 8/. and that all four molecules have a ring configuration. (auth)« less

Cysteine and cystine adsorption on FeS2(100)

NASA Astrophysics Data System (ADS)

Suzuki, Teppei; Yano, Taka-aki; Hara, Masahiko; Ebisuzaki, Toshikazu

2018-08-01

Iron pyrite (FeS2) is the most abundant metal sulfide on Earth. Owing to its reactivity and catalytic activity, pyrite has been studied in various research fields such as surface science, geochemistry, and prebiotic chemistry. Importantly, native iron-sulfur clusters are typically coordinated by cysteinyl ligands of iron-sulfur proteins. In the present paper, we study the adsorption of L-cysteine and its oxidized dimer, L-cystine, on the FeS2 surface, using electronic structure calculations based density functional theory and Raman spectroscopy measurements. Our calculations suggest that sulfur-deficient surfaces play an important role in the adsorption of cysteine and cystine. In the thiol headgroup adsorption on the sulfur-vacancy site, dissociative adsorption is found to be energetically favorable compared with molecular adsorption. In addition, the calculations indicate that, in the cystine adsorption on the defective surface under vacuum conditions, the formation of the S-Fe bond is energetically favorable compared with molecular adsorption. Raman spectroscopic measurements suggest the formation of cystine molecules through the S-S bond on the pyrite surface in aqueous solution. Our results might have implications for chemical evolution at mineral surfaces on the early Earth and the origin of iron-sulfur proteins, which are believed to be one of the most ancient families of proteins.

Insights from the Metagenome of an Acid Salt Lake: The Role of Biology in an Extreme Depositional Environment

PubMed Central

Johnson, Sarah Stewart; Chevrette, Marc Gerard; Ehlmann, Bethany L.; Benison, Kathleen Counter

2015-01-01

The extremely acidic brine lakes of the Yilgarn Craton of Western Australia are home to some of the most biologically challenging waters on Earth. In this study, we employed metagenomic shotgun sequencing to generate a microbial profile of the depositional environment associated with the sulfur-rich sediments of one such lake. Of the 1.5 M high-quality reads generated, 0.25 M were mapped to protein features, which in turn provide new insights into the metabolic function of this community. In particular, 45 diverse genes associated with sulfur metabolism were identified, the majority of which were linked to either the conversion of sulfate to adenylylsulfate and the subsequent production of sulfide from sulfite or the oxidation of sulfide, elemental sulfur, and thiosulfate via the sulfur oxidation (Sox) system. This is the first metagenomic study of an acidic, hypersaline depositional environment, and we present evidence for a surprisingly high level of microbial diversity. Our findings also illuminate the possibility that we may be meaningfully underestimating the effects of biology on the chemistry of these sulfur-rich sediments, thereby influencing our understanding of past geobiological conditions that may have been present on Earth as well as early Mars. PMID:25923206

Direct measurement of polysulfide shuttle current: A window into understanding the performance of lithium-sulfur cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moy, Derek; Manivannan, A.; Narayanan, S. R.

2014-11-04

The shuttling of polysulfide ions between the electrodes in a lithium-sulfur battery is a major technical issue limiting the self-discharge and cycle life of this high-energy rechargeable battery. Although there have been attempts to suppress the shuttling process, there has not been a direct measurement of the rate of shuttling. We report here a simple and direct measurement of the rate of the shuttling (that we term “shuttle current”), applicable to the study of any type of lithium-sulfur cell. We demonstrate the effectiveness of this measurement technique using cells with and without lithium nitrate (a widely-used shuttle suppressor additive). Wemore » present a phenomenological analysis of the shuttling process and simulate the shuttle currents as a function of the state-of-charge of a cell. We also demonstrate how the rate of decay of the shuttle current can be used to predict the capacity fade in a lithium-sulfur cell due to the shuttle process. As a result, we expect that this new ability to directly measure shuttle currents will provide greater insight into the performance differences observed with various additives and electrode modifications that are aimed at suppressing the rate of shuttling of polysulfide ions and increasing the cycle life of lithium-sulfur cells.« less

Developing clean fuels: Novel techniques for desulfurization

NASA Astrophysics Data System (ADS)

Nehlsen, James P.

The removal of sulfur compounds from petroleum is crucial to producing clean burning fuels. Sulfur compounds poison emission control catalysts and are the source of acid rain. New federal regulations require the removal of sulfur in both gasoline and diesel to very low levels, forcing existing technologies to be pushed into inefficient operating regimes. New technology is required to efficiently produce low sulfur fuels. Two processes for the removal of sulfur compounds from petroleum have been developed: the removal of alkanethiols by heterogeneous reaction with metal oxides; and oxidative desulfurization of sulfides and thiophene by reaction with sulfuric acid. Alkanethiols, common in hydrotreated gasoline, can be selectively removed and recovered from a hydrocarbon stream by heterogeneous reaction with oxides of Pb, Hg(II), and Ba. The choice of reactive metal oxides may be predicted from simple thermodynamic considerations. The reaction is found to be autocatalytic, first order in water, and zero order in thiol in the presence of excess oxide. The thiols are recovered by reactive extraction with dilute oxidizing acid. The potential for using polymer membrane hydrogenation reactors (PEMHRs) to perform hydrogenation reactions such as hydrodesulfurization is explored by hydrogenating ketones and olefins over Pt and Au group metals. The dependence of reaction rate on current density suggests that the first hydrogen addition to the olefin is the rate limiting step, rather than the adsorption of hydrogen, for all of the metals tested. PEMHRs proved unsuccessful in hydrogenating sulfur compounds to perform HDS. For the removal of sulfides, a two-phase reactor is used in which concentrated sulfuric acid oxidizes aromatic and aliphatic sulfides present in a hydrocarbon solvent, generating sulfoxides and other sulfonated species. The polar oxidized species are extracted into the acid phase, effectively desulfurizing the hydrocarbon. A reaction scheme is proposed for this system and is justified with a thermodynamic analysis and an experimental determination of the reaction rate law.

Stable isotope phenotyping via cluster analysis of NanoSIMS data as a method for characterizing distinct microbial ecophysiologies and sulfur-cycling in the environment

NASA Astrophysics Data System (ADS)

Dawson, K.; Scheller, S.; Dillon, J. G.; Orphan, V. J.

2016-12-01

Stable isotope probing (SIP) is a valuable tool for gaining insights into ecophysiology and biogeochemical cycling of environmental microbial communities by tracking isotopically labeled compounds into cellular macromolecules as well as into byproducts of respiration. SIP, in conjunction with nanoscale secondary ion mass spectrometry (NanoSIMS), allows for the visualization of isotope incorporation at the single cell level. In this manner, both active cells within a diverse population as well as heterogeneity in metabolism within a homogeneous population can be observed. The ecophysiological implications of these single cell stable isotope measurements are often limited to the taxonomic resolution of paired fluorescence in situ hybridization (FISH) microscopy. Here we introduce a taxonomy-independent method using multi-isotope SIP and NanoSIMS for identifying and grouping phenotypically similar microbial cells by their chemical and isotopic fingerprint. This method was applied to SIP experiments in a sulfur-cycling biofilm collected from sulfidic intertidal vents amended with 13C-acetate, 15N-ammonium, and 33S-sulfate. Using a cluster analysis technique based on fuzzy c-means to group cells according to their isotope (13C/12C, 15N/14N, and 33S/32S) and elemental ratio (C/CN and S/CN) profiles, our analysis partitioned 2200 cellular regions of interest (ROIs) into 5 distinct groups. These isotope phenotype groupings are reflective of the variation in labeled substrate uptake by cells in a multispecies metabolic network dominated by Gamma- and Deltaproteobacteria. Populations independently grouped by isotope phenotype were subsequently compared with paired FISH data, demonstrating a single coherent deltaproteobacterial cluster and multiple gammaproteobacterial groups, highlighting the distinct ecophysiologies of spatially-associated microbes within the sulfur-cycling biofilm from White Point Beach, CA.

Stable Isotope Phenotyping via Cluster Analysis of NanoSIMS Data As a Method for Characterizing Distinct Microbial Ecophysiologies and Sulfur-Cycling in the Environment

PubMed Central

Dawson, Katherine S.; Scheller, Silvan; Dillon, Jesse G.; Orphan, Victoria J.

2016-01-01

Stable isotope probing (SIP) is a valuable tool for gaining insights into ecophysiology and biogeochemical cycling of environmental microbial communities by tracking isotopically labeled compounds into cellular macromolecules as well as into byproducts of respiration. SIP, in conjunction with nanoscale secondary ion mass spectrometry (NanoSIMS), allows for the visualization of isotope incorporation at the single cell level. In this manner, both active cells within a diverse population as well as heterogeneity in metabolism within a homogeneous population can be observed. The ecophysiological implications of these single cell stable isotope measurements are often limited to the taxonomic resolution of paired fluorescence in situ hybridization (FISH) microscopy. Here we introduce a taxonomy-independent method using multi-isotope SIP and NanoSIMS for identifying and grouping phenotypically similar microbial cells by their chemical and isotopic fingerprint. This method was applied to SIP experiments in a sulfur-cycling biofilm collected from sulfidic intertidal vents amended with 13C-acetate, 15N-ammonium, and 33S-sulfate. Using a cluster analysis technique based on fuzzy c-means to group cells according to their isotope (13C/12C, 15N/14N, and 33S/32S) and elemental ratio (C/CN and S/CN) profiles, our analysis partitioned ~2200 cellular regions of interest (ROIs) into five distinct groups. These isotope phenotype groupings are reflective of the variation in labeled substrate uptake by cells in a multispecies metabolic network dominated by Gamma- and Deltaproteobacteria. Populations independently grouped by isotope phenotype were subsequently compared with paired FISH data, demonstrating a single coherent deltaproteobacterial cluster and multiple gammaproteobacterial groups, highlighting the distinct ecophysiologies of spatially-associated microbes within the sulfur-cycling biofilm from White Point Beach, CA. PMID:27303371

Density functional theory fragment descriptors to quantify the reactivity of a molecular family: application to amino acids.

PubMed

Senet, P; Aparicio, F

2007-04-14

By using the exact density functional theory, one demonstrates that the value of the local electronic softness of a molecular fragment is directly related to the polarization charge (Coulomb hole) induced by a test electron removed (or added) from (at) the fragment. Our finding generalizes to a chemical group a formal relation between these molecular descriptors recently obtained for an atom in a molecule using an approximate atomistic model [P. Senet and M. Yang, J. Chem. Sci. 117, 411 (2005)]. In addition, a practical ab initio computational scheme of the Coulomb hole and related local descriptors of reactivity of a molecular family having in common a similar fragment is presented. As a blind test, the method is applied to the lateral chains of the 20 isolated amino acids. One demonstrates that the local softness of the lateral chain is a quantitative measure of the similarity of the amino acids. It predicts the separation of amino acids in different biochemical groups (aliphatic, basic, acidic, sulfur contained, and aromatic). The present approach may find applications in quantitative structure activity relationship methodology.

Identification of phosphates involved in catalysis by the ribozyme RNase P RNA.

PubMed Central

Harris, M E; Pace, N R

1995-01-01

The RNA subunit of ribonuclease P (RNase P RNA) is a catalytic RNA that cleaves precursor tRNAs to generate mature tRNA 5' ends. Little is known concerning the identity and arrangement of functional groups that constitute the active site of this ribozyme. We have used an RNase P RNA-substrate conjugate that undergoes rapid, accurate, and efficient self-cleavage in vitro to probe, by phosphorothioate modification-interference, functional groups required for catalysis. We identify four phosphate oxygens where substitution by sulfur significantly reduces the catalytic rate (50-200-fold). Interference at one site was partially rescued in the presence of manganese, suggesting a direct involvement in binding divalent metal ion cofactors required for catalysis. All sites are located in conserved sequence and secondary structure, and positioned adjacent to the substrate phosphate in a tertiary structure model of the ribozyme-substrate complex. The spatial arrangement of phosphorothioate-sensitive sites in RNase P RNA was found to resemble the distribution of analogous positions in the secondary and potential tertiary structures of other large catalytic RNAs. PMID:7585250

Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations.

PubMed

Liu, Jing-yong; Huang, Shu-jie; Sun, Shui-yu; Ning, Xun-an; He, Rui-zhe; Li, Xiao-ming; Chen, Tao; Luo, Guang-qian; Xie, Wu-ming; Wang, Yu-Jie; Zhuo, Zhong-xu; Fu, Jie-wen

2015-04-01

Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na2S and Na2SO4) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na2SO4 and Na2S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO4(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO2, CaO, TiO2, and Al2O3 containing materials function as condensed phase solids in the temperature range of 800-1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the concentration of Si, Ca and Al-containing compounds in the sludge. These findings provide useful information for understanding the partitioning behavior of Pb, facilitating the development of strategies to control the volatilization of Pb during sludge incineration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of variable hydrothermal conditions on sulfur speciation and isotopic compositions mediated by two Thiomicrospira strains

NASA Astrophysics Data System (ADS)

Houghton, J.; Wills, E.; Fike, D. A.

2012-12-01

Microbially mediated reactions involving elemental sulfur in low temperature hydrothermal environments are a critical component of the net hydrothermal flux of sulfur to the global oceans. We assess here the physiological impact on sulfur speciation and isotopic composition of two microbial strains at a range of pH conditions consistent with the sharp gradients found in seafloor hydrothermal environments. Thiomicrospira thermophila and T. crunogena, both isolated from hydrothermal vents at East Pacific Rise, were grown with thiosulfate as the electron donor under aerobic, closed system conditions at controlled pH and optimal temperature (35°C). T. thermophila at pH 8 produced sulfate at a 1:1 ratio with thiosulfate consumption during exponential growth, with the ratio decreasing as pH decreases. This stoichiometric ratio decreases more steeply as a function of pH during metabolism by T. crunogena. Sulfate:thiosulfate ratios less than one indicate the production of alternative oxidized sulfur compounds such as polythionates. The rate of sulfate production is comparable in both strains and is dependent on pH, decreasing from 0.8mM/hr at pH 8 to 0.2mM/hr at pH 5.6. Fractionation of 34S expressed as Δ34S between reactant and product range from 0‰ to 3‰ for both sulfate and elemental sulfur produced, with no difference between products in pH buffered experiments (pH 5.6 and 8.0). However, in unbuffered experiments during which growth causes pH to decrease from 7 to below 4.5, Δ34S(S2O3-SO4) is consistently larger than Δ34S(S2O3-S) in both strains by a factor of 2. The metabolic activity of these (and similar) strains indicate that complex and cryptic sulfur cycling may be occurring in the subsurface, associated with only minimal variation in the δ34S isotopic composition of sulfate and elemental sulfur.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuura, Yukihito, E-mail: matsuura@chem.nara-k.ac.jp

The tunneling magnetoresistance (TMR) of a silicon chain sandwiched between nickel electrodes was examined by using first-principles density functional theory. The relative orientation of the magnetization in a parallel-alignment (PA) configuration of two nickel electrodes enhanced the current with a bias less than 0.4 V compared with that in an antiparallel-alignment configuration. Consequently, the silicon chain-nickel electrodes yielded good TMR characteristics. In addition, there was polarized spin current in the PA configuration. The spin polarization of sulfur atoms functioning as a linking bridge between the chain and nickel electrode played an important role in the magnetic effects of the electric current.more » Moreover, the hybridization of the sulfur 3p orbital and σ-conjugated silicon 3p orbital contributed to increasing the total current.« less

Geomicrobiology of sublacustrine thermal vents in Yellowstone Lake: geochemical controls on microbial community structure and function

PubMed Central

Inskeep, William P.; Jay, Zackary J.; Macur, Richard E.; Clingenpeel, Scott; Tenney, Aaron; Lovalvo, David; Beam, Jacob P.; Kozubal, Mark A.; Shanks, W. C.; Morgan, Lisa A.; Kan, Jinjun; Gorby, Yuri; Yooseph, Shibu; Nealson, Kenneth

2015-01-01

Yellowstone Lake (Yellowstone National Park, WY, USA) is a large high-altitude (2200 m), fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal activity. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal vent communities in Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of vent waters influence the distribution of specific microorganisms and their metabolic potential. Thermal vent waters and associated microbial biomass were sampled during two field seasons (2007–2008) using a remotely operated vehicle (ROV). Sublacustrine thermal vent waters (circa 50–90°C) contained elevated concentrations of numerous constituents associated with geothermal activity including dissolved hydrogen, sulfide, methane and carbon dioxide. Microorganisms associated with sulfur-rich filamentous “streamer” communities of Inflated Plain and West Thumb (pH range 5–6) were dominated by bacteria from the Aquificales, but also contained thermophilic archaea from the Crenarchaeota and Euryarchaeota. Novel groups of methanogens and members of the Korarchaeota were observed in vents from West Thumb and Elliot's Crater (pH 5–6). Conversely, metagenome sequence from Mary Bay vent sediments did not yield large assemblies, and contained diverse thermophilic and nonthermophilic bacterial relatives. Analysis of functional genes associated with the major vent populations indicated a direct linkage to high concentrations of carbon dioxide, reduced sulfur (sulfide and/or elemental S), hydrogen and methane in the deep thermal ecosystems. Our observations show that sublacustrine thermal vents in Yellowstone Lake support novel thermophilic communities, which contain microorganisms with functional attributes not found to date in terrestrial geothermal systems of YNP. PMID:26579074

Effects of inhalation of acidic compounds on pulmonary function in allergic adolescent subjects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koenig, J.Q.; Covert, D.S.; Pierson, W.E.

There is concern about the human health effects of inhalation of acid compounds found in urban air pollution. It was the purpose of this study to investigate three of these acid compounds, sulfur dioxide (SO/sub 2/), sulfuric acid (H/sub 2/SO/sub 4/), and nitric acid (HNO/sub 3/) in a group of allergic adolescent subjects. Subjects were exposed during rest and moderate exercise to 0.7 mumole/m/sup 3/ (68 micrograms/m/sup 3/) H/sub 2/SO/sub 4/, 4.0 mumole/m/sup 3/ (0.1 ppm) SO/sub 2/, or 2.0 mumole/m/sup 3/ (0.05 ppm) HNO/sub 3/. Pulmonary functions (FEV1, total respiratory resistance, and maximal flow) were measured before and aftermore » exposure. Preliminary analysis based on nine subjects indicates that exposure to 0.7 mumole/m/sup 3/ H/sub 2/SO/sub 4/ alone and in combination with SO/sub 2/ caused significant changes in pulmonary function, whereas exposure to air or SO/sub 2/ alone did not. FEV1 decreased an average of 6% after exposure to H/sub 2/SO/sub 4/ alone and 4% when the aerosol was combined with SO/sub 2/. The FEV1 decrease was 2% after both air and SO/sub 2/ exposures. Total respiratory resistance (RT) increased 15% after the combined H/sub 2/SO/sub 4/ exposures, 12% after H/sub 2/SO/sub 4/ alone, and 7% after exposure to air. After exposures to HNO3 alone, FEV1 decreased by 4%, and RT increased by 23%. These results are preliminary; final conclusions must wait for completion of the study.« less

Analysis of NFU-1 metallocofactor binding-site substitutions-impacts on iron-sulfur cluster coordination and protein structure and function.

PubMed

Wesley, Nathaniel A; Wachnowsky, Christine; Fidai, Insiya; Cowan, J A

2017-11-01

Iron-sulfur (Fe/S) clusters are ancient prosthetic groups found in numerous metalloproteins and are conserved across all kingdoms of life due to their diverse, yet essential functional roles. Genetic mutations to a specific subset of mitochondrial Fe/S cluster delivery proteins are broadly categorized as disease-related under multiple mitochondrial dysfunction syndrome (MMDS), with symptoms indicative of a general failure of the metabolic system. Multiple mitochondrial dysfunction syndrome 1 (MMDS1) arises as a result of the missense mutation in NFU1, an Fe/S cluster scaffold protein, which substitutes a glycine near the Fe/S cluster-binding pocket to a cysteine (p.Gly208Cys). This substitution has been shown to promote protein dimerization such that cluster delivery to NFU1 is blocked, preventing downstream cluster trafficking. However, the possibility of this additional cysteine, located adjacent to the cluster-binding site, serving as an Fe/S cluster ligand has not yet been explored. To fully understand the consequences of this Gly208Cys replacement, complementary substitutions at the Fe/S cluster-binding pocket for native and Gly208Cys NFU1 were made, along with six other variants. Herein, we report the results of an investigation on the effect of these substitutions on both cluster coordination and NFU1 structure and function. The data suggest that the G208C substitution does not contribute to cluster binding. Rather, replacement of the glycine at position 208 changes the oligomerization state as a result of global structural alterations that result in the downstream effects manifest as MMDS1, but does not perturb the coordination chemistry of the Fe-S cluster. © 2017 Federation of European Biochemical Societies.

Endogenous sulfur dioxide aggravates myocardial injury in isolated rat heart with ischemia and reperfusion.

PubMed

Zhang, Suqing; Du, Junbao; Jin, Hongfang; Li, Wei; Liang, Yinfang; Geng, Bin; Li, Shukui; Zhang, Chunyu; Tang, Chaoshu

2009-02-27

Ischemia-reperfusion (I/R) injury is an important clinical problem. This article investigated the role of sulfur dioxide (SO2) in the regulation of cardiac function and in the pathogenesis of cardiac I/R injury in isolated rat heart. Rat hearts isolated on a Langendorff apparatus were divided into control, I/R, I/R+SO2, and I/R+hydroxamate groups. Hydroxamate is an inhibitor of SO2 synthetase. I/R treatment was ischemia for 2 hr in hypothermic solution (4 degrees C), then reperfusion/rewarming (37 degrees C) for 60 min. Cardiac function was monitored by MacLab analog to a digital converter. Determination of sulfite content involved reverse-phase high performance liquid chromatography with fluorescence detection. Myoglobin content of coronary perfusate was determined at 410 nm. Myocardial malondialdehyde (MDA) was determined by thiobarbituric acid method, and conjugated diene (CD) was extracted by chloroform. 5,50-Dithiobis-2-nitrobenzoic acid was used to determine glutathione (GSH). The results showed that I/R treatment obviously increased myocardial sulfite content, and sulfite content of myocardium was negatively correlated with the recovery rate of left-ventricle developed pressure and positively correlated with the leakage of myoglobin. In postreperfusion, myocardial function recovery was decreased by SO2. During reperfusion, myocardium-released enzymes, MDA and CD level were increased but myocardial GSH content was depressed with the treatment of SO2 donor. Incubation of myocardial tissue with SO2 significantly increased MDA and CD generation. Endogenous SO2 might be involved in the pathogenesis of myocardial I/R injury, and its mechanism might be associated with an increase in lipid peroxide level and a decrease in GSH generation.

Tether mutations that restore function and suppress pleiotropic phenotypes of the C. elegans isp-1(qm150) Rieske iron–sulfur protein

PubMed Central

Jafari, Gholamali; Wasko, Brian M.; Tonge, Ashley; Schurman, Nathan; Dong, Cindy; Li, Zhongyu; Peters, Rebecca; Kayser, Ernst-Bernhard; Pitt, Jason N.; Morgan, Phil G.; Sedensky, Margaret M.; Crofts, Antony R.; Kaeberlein, Matt

2015-01-01

Mitochondria play an important role in numerous diseases as well as normative aging. Severe reduction in mitochondrial function contributes to childhood disorders such as Leigh Syndrome, whereas mild disruption can extend the lifespan of model organisms. The Caenorhabditis elegans isp-1 gene encodes the Rieske iron–sulfur protein subunit of cytochrome c oxidoreductase (complex III of the electron transport chain). The partial loss of function allele, isp-1(qm150), leads to several pleiotropic phenotypes. To better understand the molecular mechanisms of ISP-1 function, we sought to identify genetic suppressors of the delayed development of isp-1(qm150) animals. Here we report a series of intragenic suppressors, all located within a highly conserved six amino acid tether region of ISP-1. These intragenic mutations suppress all of the evaluated isp-1(qm150) phenotypes, including developmental rate, pharyngeal pumping rate, brood size, body movement, activation of the mitochondrial unfolded protein response reporter, CO2 production, mitochondrial oxidative phosphorylation, and lifespan extension. Furthermore, analogous mutations show a similar effect when engineered into the budding yeast Rieske iron–sulfur protein Rip1, revealing remarkable conservation of the structure–function relationship of these residues across highly divergent species. The focus on a single subunit as causal both in generation and in suppression of diverse pleiotropic phenotypes points to a common underlying molecular mechanism, for which we propose a “spring-loaded” model. These observations provide insights into how gating and control processes influence the function of ISP-1 in mediating pleiotropic phenotypes including developmental rate, movement, sensitivity to stress, and longevity. PMID:26504246

Enantioselective construction of C-chiral allylic sulfilimines via the iridium-catalyzed allylic amination with S,S-diphenylsulfilimine: asymmetric synthesis of primary allylic amines† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c4sc01317d Click here for additional data file.

PubMed Central

Grange, Rebecca L.; Clizbe, Elizabeth A.; Counsell, Emma J.

2015-01-01

We have devised a highly regio- and enantioselective iridium-catalyzed allylic amination reaction with the sulfur-stabilized aza-ylide, S,S-diphenylsulfilimine. This process provides a robust and scalable method for the construction of aryl-, alkyl- and alkenyl-substituted C-chiral allylic sulfilimines, which are important functional groups for organic synthesis. Additionally, the combination of the allylic amination with an in situ deprotection of the sulfilimine constitutes a convenient one-pot protocol for the construction of chiral nonracemic primary allylic amines. PMID:28936319

Rodent repellents: Preparation and properties of thiouronium compounds and cyclic imides

USGS Publications Warehouse

Bellack, E.; DeWitt, J.B.

1954-01-01

Syntheses and bioassays of cyclic imides and thiouronium compounds were carried out as part of a search for materials capable of preventing rodent damage to packaged commodities. Previous studies had shown that repellent activity was associated with functional groups containing nitrogen and sulfur, and was enhanced by the presence of ionic linkages. Twenty-seven thiouronium compounds and 40 imides, including 1 0 compounds not described previously, were prepared for these tests. Ten imides and 26 thiouronium compounds were repellent under the conditions of test. Information obtained in these studies will be utilized in the development and selection of more effective materials for prevention of rodent damage to foods and other commodities.

A preliminary study on the synthesis of monosaccharide palmitate

NASA Astrophysics Data System (ADS)

Othman, Nor Hamidah Abu; Jafri, Nur Hafifah Nahdirah; Salimon, Jumat

2018-04-01

The esterification reaction between palmitic acid and different monosaccharides using 1.5% sulfuric acid as the catalyst to produce monosachharide palmitate was studied. The highest percentage yield obtained was 20% from tripalmitate (TAG01) whereas the lowest percentage formed was 0.8% from glucose pentapalmitate (GPP01). Functional group analysis was conducted using ATR-FTIR spectroscopy. Infrared spectroscopy showed C=O ester stretching at 1735, 1697, 1732 and 1729 cm-1, C-O ester stretching at 1265, 1269, 1284 and 1265 while C-H sp3 stretching was observed at 2847-2914 cm-1 for tripalmitate (TAG), glucose pentapalmitate (GPP), xylitol pentapalmitate (XPP) and sorbitol hexapalmitate (SHP) with no observed -OH stretch after esterification to produce monosaccharide palmitate.