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Sample records for improved sulphide silver

  1. Dynamic protein coronas revealed as a modulator of silver nanoparticle sulphidation in vitro

    NASA Astrophysics Data System (ADS)

    Miclăuş, Teodora; Beer, Christiane; Chevallier, Jacques; Scavenius, Carsten; Bochenkov, Vladimir E.; Enghild, Jan J.; Sutherland, Duncan S.

    2016-06-01

    Proteins adsorbing at nanoparticles have been proposed as critical toxicity mediators and are included in ongoing efforts to develop predictive tools for safety assessment. Strongly attached proteins can be isolated, identified and correlated to changes in nanoparticle state, cellular association or toxicity. Weakly attached, rapidly exchanging proteins are also present at nanoparticles, but are difficult to isolate and have hardly been examined. Here we study rapidly exchanging proteins and show for the first time that they have a strong modulatory effect on the biotransformation of silver nanoparticles. Released silver ions, known for their role in particle toxicity, are found to be trapped as silver sulphide nanocrystals within the protein corona at silver nanoparticles in serum-containing cell culture media. The strongly attached corona acts as a site for sulphidation, while the weakly attached proteins reduce nanocrystal formation in a serum-concentration-dependent manner. Sulphidation results in decreased toxicity of Ag NPs.

  2. Histochemical demonstration of zinc in rat epididymis using a sulphide-silver method.

    PubMed

    Fujimori, O; Tsukise, A; Yamada, K

    1988-01-01

    We studied the histochemical distribution of zinc in rat epididymis using a sulphide-silver method. In the supranuclear cytoplasm of the principal cells that line the epididymis of rats, varying amounts of sulphide-silver-reactive zinc were visualized. In adult mating rats, significant amounts of zinc were found in the proximal portion of the epididymis, whereas in non-mating, mature and immature young rats, this heavy metal was most prominent in the distal portion of this organ. In all of the rats studied, zinc was sparsely distributed in the intermediate portion of the epididymis. From these results, it can be assumed that the zinc present in the epithelial lining of rat epididymis plays an important role in the maturation of spermatozoa. The present results represent a useful contribution to our understanding of the functional morphology of rat epididymis.

  3. Studies on electrodeposited silver sulphide thin films by double exposure holographic interferometry

    NASA Astrophysics Data System (ADS)

    Prabhune, V. B.; Shinde, N. S.; Fulari, V. J.

    2008-12-01

    Silver sulphide (Ag 2S) thin films have been deposited on to stainless steel and fluorine doped tin oxide (FTO) glass substrates by the electrodeposition process, in potentiostatic mode using silver nitrate (AgNO 3), sodium thiosulphate (Na 2S 2O 3) as a precursor sources and Ethylene Diamine Tetra Acetic Acid (EDTA) was used as a complexing agent. The deposition potential of the compound was investigated by cyclic voltammetry. The structural and optical properties of the deposited films have been studied using X-ray diffraction (XRD) and optical absorption techniques, respectively. XRD studies reveal that the films are polycrystalline with monoclinic crystal structure. Optical absorption study shows the presence of direct transition with bandgap energy 1.1 eV. The determination of thickness and stress of the Ag 2S thin films was carried out by Double Exposure Holographic Interferometry (DEHI) technique.

  4. Localized surface plasmon and exciton interaction in silver-coated cadmium sulphide quantum dots

    SciTech Connect

    Ghosh, P.; Rustagi, K. C.; Vasa, P.; Singh, B. P.

    2015-05-15

    Localized surface plasmon and exciton coupling has been investigated on colloidal solutions of silver-coated CdS nanoparticles (NPs), synthesized by gamma irradiation. Two broad photoluminescence (PL) bands (blue/red) corresponding to band to band and defect state transitions have been observed for the bare and coated samples. In case of bare CdS NPs, the intensity of the red PL peak is about ten times higher than the blue PL peak intensity. However, on coating the CdS NPs with silver, the peak intensity of the blue PL band gets enhanced and becomes equal to that of the red PL band. High-resolution transmission electron microscopic (HRTEM) images adequately demonstrate size distribution of these metal/semiconductor nanocomposites. UV-Vis absorption studies show quantum confinement effect in these semiconductor quantum dot (SQD) systems. Absorption spectrum of silver-coated SQDs shows signature of surface plasmon-exciton coupling which has been theoretically verified.

  5. Zeta-potential and particle size studies of silver sulphide nanoparticles

    SciTech Connect

    Sharma, Vikash Tarachand,; Ganesan, V.; Okram, Gunadhor S.

    2016-05-23

    Silver sulfide (Ag{sub 2}S) nanoparticles (NPs) were prepared successfully for the first time using diethylene glycol (DEG) as a surfactant. X-ray diffraction (XRD) data revealed single phase nature of the compound and energy-dispersive X-ray (EDX) confirmed its nominal composition. Their sizes were 43 nm from XRD, 50 nm from atomic force microscopy (AFM) and 19 nm & 213 nm from dynamic light scattering (DLS); their differences have been discussed. Autotitration study of zeta potential of these NPs in deionized water by DLS at different pH values confirmed an isoelectric point at pH = 5.14 and their very unstable nature in deionized water.

  6. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, Jr., Charles Q.

    1981-01-01

    Glass mirrors having improved weathering properties are prepared by an improvement in the process for making the mirrors. The glass surface after it has been cleaned but before it is silvered, is contacted with a solution of lanthanide rare earths in addition to a sensitization solution of tin or palladium. The addition of the rare earths produces a mirror which has increased resistance to delamination of the silver from the glass surface in the presence of water.

  7. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, C.Q. Jr.

    1980-01-28

    Glass mirrors having improved weathering properties are prepared by an improvement in the process for making the mirrors. The glass surface after it has been cleaned but before it is silvered, is contacted with a solution of lanthanide rare earths in addition to a sensitization solution of tin or palladium. The addition of the rare earths produces a mirror which has increased resistance to delamination of the silver from the glass surface in the presence of water.

  8. Distant electric coupling between nitrate reduction and sulphide oxidation investigated by an improved nitrate microscale biosensor

    NASA Astrophysics Data System (ADS)

    Marzocchi, U.; Revsbech, N. P.; Nielsen, L. P.; Risgaard-Petersen, N.

    2012-04-01

    Bacteria are apparently able to transmit electrons to other bacteria (Summers et al. 2010) or to electrodes (Malvankar et al. 2011) by some kind of nanowires (Reguera et al. 2005, Gorbi et al. 2006). Lately it has been shown that such transfer may occur over distances of centimetres in sediments, thereby coupling sulphide oxidation in deeper layers with oxygen reduction near the surface (Nielsen 2011). The finding of these long-distance electrical connections originated from analysis of O2, H2S, and pH profiles measured with microsensors. Nitrate is thermodynamically almost as good an electron acceptor as O2, and we therefore set up an experiment to investigate whether long-distance electron transfer also happens with NO3-. Aquaria were filled with sulphidic marine sediment from Aarhus Bay that was previously used to show long-distance electron transfer to O2. The aquaria were equipped with a lid so that they could be completely filled without a gas phase. Anoxic seawater with 300 μM NO3- was supplied at a constant rate resulting in a steady state concentration in the aquatic phase of 250 μM NO3-. The reservoir with the nitrate-containing water was kept anoxic by bubbling it with a N2/CO2 mixture and was kept at an elevated temperature. The water was cooled on the way to the aquaria to keep the water in the aquaria undersaturated with gasses, so that bubble formation by denitrification in the sediment could be minimised. Profiles of NO3-, H2S, and pH were measured as a function of time (2 months) applying commercial sensors for H2S and pH and an improved microscale NO3- biosensor developed in our laboratory. The penetration of NO3- in the sediment was 4-5 mm after 2 months, whereas sulphide only could be detected below 8-9 mm depth. The electron acceptor and electron donor were thus separated by 4-5 mm, indicating long distance electron transfer. A pH maximum of about 8.6 pH units at the NO3- reduction zone similar to a pH maximum observed in the O2 reduction

  9. Hydrogen sulphide.

    PubMed

    Guidotti, T L

    1996-10-01

    Hydrogen sulphide (H2S) is the primary chemical hazard in natural gas production in 'sour' gas fields. It is also a hazard in sewage treatment and manure-containment operations, construction in wetlands, pelt processing, certain types of pulp and paper production, and any situation in which organic material decays or inorganic sulphides exist under reducing conditions. H2S dissociates into free sulphide in the circulation. Sulphide binds to many macromolecules, among them cytochrome oxidase. Although this is undoubtedly an important mechanism of toxicity due to H2S, there may be others H2S provides little opportunity for escape at high concentrations because of the olfactory paralysis it causes, the steep exposure-response relationships, and the characteristically sudden loss of consciousness it can cause which is colloquially termed 'knockdown.' Other effects may include mucosal irritation, which is associated at lower concentrations with a keratoconjunctivitis called 'gas eye' and at higher concentrations with risk of pulmonary oedema. Chronic central nervous system sequelae may possibly follow repeated knockdowns: this is controversial and the primary effects of H2S may be confounded by anoxia or head trauma. Treatment is currently empirical, with a combination of nitrite and hyperbaric oxygen preferred. The treatment regimen is not ideal and carries some risk.

  10. The amplification of polymerized diaminobenzidine with physical developers: sensitizing effects of transition metal salts and sulphide.

    PubMed

    von Ruhland, C J; Jasani, B

    2010-05-01

    Amplification of metal-complexed polymerized diaminobenzidine by two light-insensitive physical developers was systematically examined in a dot blot model system following either polymerizing diaminobenzidine in the presence of transition metal salts or applying the metal salts post-diaminobenzidine polymerization. The effect of sodium sulphide treatment on subsequent amplification was also investigated. Those metal-diaminobenzidine complexes that facilitated the most powerful amplification were subsequently tested in an immunohistochemical setting. The most dramatic amplification of polymerized diaminobenzidine was observed following its post-polymerization treatment with salts of platinum alone, or gold or vanadium with subsequent sulphide treatment, and allowed previously invisible quantities of polymerized diaminobenzidine to be clearly seen. Three other transition metal salts also improved the amplification of polymerized diaminobenzidine but to a lesser degree, namely nickel alone, and silver or rhodium with subsequent sulphide treatment. Sensitivity was comparable with the colloidal gold-silver amplification system.

  11. Selective determination of thiamine (vitamin B(1)) in pharmaceutical preparations by direct potentiometric argentometric titration with use of the silver-silver sulphide ion-selective electrode.

    PubMed

    Hassan, S S; Elnemma, E

    1989-10-01

    A simple and selective argentometric titration method is described for determination of thiamine (vitamin B(1)), based on direct potentiometric titration in alkaline media (0.5M) in which a chemical transformation takes place, creating two acidic groups, the protons of which are replaceable by silver ions. The acidimetric and argentometric potentiometric titration curves display two consecutive potential breaks specific for thiamine. The second break is reproducible and corresponds to a 2:1 reaction ratio of silver to thiamine. No interference is caused by other vitamins, active ingredients and inactive excipients normally present in multivitamin preparations. The results obtained for determination of thiamine in pure powders, pharmaceutical tablets and ampoules showed an average recovery of 98.2% of the nominal values and a mean standard deviation of 0.5%, and agreed fairly well with data obtained by the British Pharmacopoeia procedure.

  12. Improved processing for silver halide pulse holography

    NASA Astrophysics Data System (ADS)

    Mikhailov, Viktor N.; Son, Jung-Young; Grinevitskaya, Olga V.; Lee, Hyuk-Soo; Choi, Yong-Jin

    1996-04-01

    Using of an improved developer with optical latensification allowed to significantly increase exposure sensitivity of currently in use silver halide materials. Transmission large-scale holograms (30 X 40 cm2) of diffused objects have been recorded under pulse exposure of about 6.5 X 10-6 J/cm2 for VRP and of about 2 X 10-6 J/cm2 for Agfa-Gavaert 8E56HD, in both cases without appreciable contrast deterioration. Results of the first experiments on pulse reflection holography are also discussed.

  13. Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency

    PubMed Central

    Chen, Juan; Wu, Fei-Hua; Shang, Yu-Ting; Wang, Wen-Hua; Hu, Wen-Jun; Simon, Martin; Liu, Xiang; Shangguan, Zhou-Ping; Zheng, Hai-Lei

    2015-01-01

    Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants. PMID:26208645

  14. Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency.

    PubMed

    Chen, Juan; Wu, Fei-Hua; Shang, Yu-Ting; Wang, Wen-Hua; Hu, Wen-Jun; Simon, Martin; Liu, Xiang; Shangguan, Zhou-Ping; Zheng, Hai-Lei

    2015-11-01

    Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  15. Improving the Stability of Fluorescent Silver Nanoclusters

    NASA Astrophysics Data System (ADS)

    Swanson, Nicholas; Stanko, Danielle; Campbell, Ian; Wittmershaus, Bruce

    The quantum mechanical nature of noble metal nanoparticles results in them having optical properties much different from the bulk metal. Silver nanoclusters (AgNC), groups of 4 to 20 atoms, are characterized by strong optical transitions in the visible part of the spectrum giving them an appearance like fluorescent organic dyes. These nanoclusters can also have fluorescence quantum yields over 90%. Following the analysis of published results of DNA templated nanoclusters, we created a procedure for synthesizing AgNC. The AgNC have a high fluorescence quantum yield but degrade with a lifetime of only a few days when in solution at room temperature. Our goal in this study was to increase the stability of the AgNC towards improving their value as a fluorescent material in various applications, such as luminescent solar concentrators. To increase their stability, we've chosen to modify our procedure by removing oxygen from the solution after the sample has reacted. Oxygen removal caused a significant increase in the stability of the clusters over a given period of time. This material is based upon work supported by the National Science Foundation under Grant Number NSF-ECCS-1306157.

  16. Cadmium sulphide solar cell

    SciTech Connect

    Bassett, P.J.; Verheijen, A.W.

    1984-07-31

    The invention relates to the manufacture of cadmium sulphide solar cells. A cell is formed of a glass substrate 10, a front contact 12 made, for example, of tin oxide, a cadmium sulphide layer 14 and a copper sulphide layer 16, the junction between the layers 14 and 16 is photovoltaic. In order to form a rear contact 18 on the copper sulphide layer, the invention proposes vapor depositing a mixed layer of copper and copper oxide onto the sulphide layer. The invention also describes a method of heat treatment following the formation of the rear contact in order to optimise the electrical performance of the cell.

  17. Utilization of fly ash to improve the quality of the acid mine drainage generated by oxidation of a sulphide-rich mining waste: column experiments.

    PubMed

    Pérez-López, Rafael; Nieto, José Miguel; de Almodóvar, Gabriel Ruiz

    2007-04-01

    The production of Acid Mine Drainage (AMD) as a result of the oxidative dissolution of sulphides is one of the main pollution problems affecting natural watercourses in mining environments with sulphide-rich residues. In this work, the generation of AMD was prevented by means of the addition of fly ash to sulphide-rich residues in non-saturated column experiments. A column experiment filled with a pyrite-rich sludge with artificial irrigation leached acid drainages (pH approx. 2) containing high concentrations of sulphate, iron and other metals. However, non-saturated column experiments filled with pyritic-rich sludge and fly ash drained leachates characterized by alkaline pH (pH up to 10), low sulphate concentration, and lack of iron and other metals in solution. The pyrite oxidative dissolution at high pH, as a consequence of the leaching of fly ash, favours the metal precipitation inside the column (mainly iron), the coating of pyrite grains, and the attenuation of the oxidation process, resulting in a great improvement in the quality of the leachates.

  18. Zinc Pyrithione Improves the Antibacterial Activity of Silver Sulfadiazine Ointment.

    PubMed

    Blanchard, Catlyn; Brooks, Lauren; Ebsworth-Mojica, Katherine; Didione, Louis; Wucher, Benjamin; Dewhurst, Stephen; Krysan, Damian; Dunman, Paul M; Wozniak, Rachel A F

    2016-01-01

    Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus are commonly associated with biofilm-associated wound infections that are recalcitrant to conventional antibiotics. As an initial means to identify agents that may have a greater propensity to improve clearance of wound-associated bacterial pathogens, we screened a Food and Drug Administration-approved drug library for members that display bactericidal activity toward 72-h-established P. aeruginosa biofilms using an adenylate kinase reporter assay for bacterial cell death. A total of 34 compounds displayed antibiofilm activity. Among these, zinc pyrithione was also shown to reduce levels of A. baumannii and S. aureus biofilm-associated bacteria and exhibited an additive effect in combination with silver sulfadiazine, a leading topical therapeutic for wound site infections. The improved antimicrobial activity of zinc pyrithione and silver sulfadiazine was maintained in an ointment formulation and led to improved clearance of P. aeruginosa, A. baumannii, and S. aureus in a murine model of wound infection. Taken together, these results suggest that topical zinc pyrithione and silver sulfadiazine combination formulations may mitigate wound-associated bacterial infections and disease progression. IMPORTANCE Topical antimicrobial ointments ostensibly mitigate bacterial wound disease and reliance on systemic antibiotics. Yet studies have called into question the therapeutic benefits of several traditional topical antibacterials, accentuating the need for improved next-generation antimicrobial ointments. Yet the development of such agents consisting of a new chemical entity is a time-consuming and expensive proposition. Considering that drug combinations are a mainstay therapeutic strategy for the treatment of other therapeutic indications, one alternative approach is to improve the performance of conventional antimicrobial ointments by the addition of a well-characterized and FDA

  19. Zinc Pyrithione Improves the Antibacterial Activity of Silver Sulfadiazine Ointment

    PubMed Central

    Blanchard, Catlyn; Brooks, Lauren; Ebsworth-Mojica, Katherine; Didione, Louis; Wucher, Benjamin; Dewhurst, Stephen; Krysan, Damian

    2016-01-01

    ABSTRACT Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus are commonly associated with biofilm-associated wound infections that are recalcitrant to conventional antibiotics. As an initial means to identify agents that may have a greater propensity to improve clearance of wound-associated bacterial pathogens, we screened a Food and Drug Administration-approved drug library for members that display bactericidal activity toward 72-h-established P. aeruginosa biofilms using an adenylate kinase reporter assay for bacterial cell death. A total of 34 compounds displayed antibiofilm activity. Among these, zinc pyrithione was also shown to reduce levels of A. baumannii and S. aureus biofilm-associated bacteria and exhibited an additive effect in combination with silver sulfadiazine, a leading topical therapeutic for wound site infections. The improved antimicrobial activity of zinc pyrithione and silver sulfadiazine was maintained in an ointment formulation and led to improved clearance of P. aeruginosa, A. baumannii, and S. aureus in a murine model of wound infection. Taken together, these results suggest that topical zinc pyrithione and silver sulfadiazine combination formulations may mitigate wound-associated bacterial infections and disease progression. IMPORTANCE Topical antimicrobial ointments ostensibly mitigate bacterial wound disease and reliance on systemic antibiotics. Yet studies have called into question the therapeutic benefits of several traditional topical antibacterials, accentuating the need for improved next-generation antimicrobial ointments. Yet the development of such agents consisting of a new chemical entity is a time-consuming and expensive proposition. Considering that drug combinations are a mainstay therapeutic strategy for the treatment of other therapeutic indications, one alternative approach is to improve the performance of conventional antimicrobial ointments by the addition of a well-characterized and FDA

  20. Improved mass spectrometry compatibility is afforded by ammoniacal silver staining

    PubMed Central

    Chevallet, Mireille; Diemer, Hélène; Luche, Sylvie; van Dorsselaer, Alain; Rabilloud, Thierry; Leize-Wagner, Emmanuelle

    2006-01-01

    Sequence coverage in mass spectrometry analysis of protein digestion-derived peptides is a key issue for detailed characterization of proteins or identification at low quantities. In gel-based proteomics studies, the sequence coverage greatly depends on the protein detection method. It is shown here that ammoniacal silver detection methods offer improved sequence coverage over standard silver nitrate methods, while keeping the high sensitivity of silver staining With the development of 2D-PAGE-based proteomics, another burden is placed on the detection methods used for protein detection on 2D-gels. Besides the classical requirements of linearity, sensitivity and homogeneity from one protein to another, detection methods must now take into account another aspect, namely their compatibility with mass spectrometry. This compatibility is evidenced by two different and complementary aspects, which are i) the absence of adducts and artefactual modifications on the peptides obtained after protease digestion of a protein detected and digested in –gel and ii) the quantitative yield of peptides recovered after digestion and analyzed by the mass spectrometer. While this quantitative yield is not very important per se, it is however a crucial parameter as it strongly influences the signal to noise ratio of the mass spectrum, and thus the number of peptides that can be detected from a given protein input, especially at low protein amounts. This influences in turn the sequence coverage, and thus the detail of the analysis provided by the mass spectrometer. PMID:16548061

  1. Improved mass spectrometry compatibility is afforded by ammoniacal silver staining.

    PubMed

    Chevallet, Mireille; Diemer, Hélène; Luche, Sylvie; van Dorsselaer, Alain; Rabilloud, Thierry; Leize-Wagner, Emmanuelle

    2006-04-01

    Sequence coverage in MS analysis of protein digestion-derived peptides is a key issue for detailed characterization of proteins or identification at low quantities. In gel-based proteomics studies, the sequence coverage greatly depends on the protein detection method. It is shown here that ammoniacal silver detection methods offer improved sequence coverage over standard silver nitrate methods, while keeping the high sensitivity of silver staining. With the development of 2D-PAGE-based proteomics, another burden is placed on the detection methods used for protein detection on 2-D-gels. Besides the classical requirements of linearity, sensitivity, and homogeneity from one protein to another, detection methods must now take into account another aspect, namely their compatibility with MS. This compatibility is evidenced by two different and complementary aspects, which are (i) the absence of adducts and artefactual modifications on the peptides obtained after protease digestion of a protein detected and digested in - gel, and (ii) the quantitative yield of peptides recovered after digestion and analyzed by the mass spectrometer. While this quantitative yield is not very important per se, it is however a crucial parameter as it strongly influences the S/N of the mass spectrum and thus the number of peptides that can be detected from a given protein input, especially at low protein amounts. This influences in turn the sequence coverage and thus the detail of the analysis provided by the mass spectrometer.

  2. Efficient incorporation of silver to improve superconducting fibers

    SciTech Connect

    Gleixner, Richard A.; LaCount, Dale F.; Finnemore, Douglas K.

    1994-04-26

    An improved method for the efficient incorporation of a metal such as silver in a superconducting material includes blending the metal with a high temperature superconductor or precursor powder and consolidating the same into pellets. The pellets are charged directly into a heating assembly where it is melted and heated sufficiently to a uniform temperature prior to fiberization. Droplets of the melted blend fall through a collar into a nozzle where they are subjected to a high velocity gas to break the melted material into ligaments which solidify into improved flexible fibers having the metal homogeneously dis This invention was made with Government support under a contract with the Department of Energy (DOE) and Ames Laboratory, Contract No. SC-91-225, our reference No. CRD-1272. The Government has certain rights in this invention.

  3. Silver

    Integrated Risk Information System (IRIS)

    Silver ; CASRN 7440 - 22 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  4. Effect of silver contents in cellulose nanocrystal/silver nanohybrids on PHBV crystallization and property improvements.

    PubMed

    Zhang, Heng; Yu, Hou-Yong; Wang, Chuang; Yao, Juming

    2017-10-01

    Ternary nanocomposites including cellulose nanocrystals/silver nanohybrids (CNC-Ag) and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were prepared by using solution casting. The effect of different AgNPs contents in the nanohybrids on crystallization ability and properties of PHBV was comprehensively investigated. Compared to binary PHBV/CNC nanocomposite, the ternary nanocomposites with high AgNPs contents showed larger improvements in the thermal stability, mechanical, barrier, overall migration and antibacterial properties. The property transitions at various AgNPs contents were due to transition of the nanohybrids induced PHBV crystallization ability (from single CNC nucleation to synergistic nucleation of CNC and AgNPs), and increased crystallinity without compromising the amounts of hydrogen bonds. Especially, the PHBV/CNC-Ag-1.7 showed the good barrier property and lower migration levels in food simulants, high antibacterial ratio of 99.9% and biocompatibility to human MG-63 cells, suggesting its potential application in food packaging related materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Improved molybdenum disulfide-silver motor brushes have extended life

    NASA Technical Reports Server (NTRS)

    Horton, J. C.; King, H. M.

    1964-01-01

    Motor brushes of proper quantities of molybdenum disulfide and copper or silver are manufactured by sintering techniques. Graphite molds are used. These brushes operate satisfactorily for long periods in normal atmosphere or in a high-vacuum environment.

  6. Silver yoga exercises improved physical fitness of transitional frail elders.

    PubMed

    Chen, Kuei-Min; Fan, Jue-Ting; Wang, Hsiu-Hung; Wu, Shu-Ju; Li, Chun-Huw; Lin, Huey-Shyan

    2010-01-01

    Promoting the health of transitional frail elders (e.g., through therapeutic-based yoga exercises) is essential to reduce healthcare expenditures caused by chronic health problems. The purpose of this study was to determine the efficacy of 24 weeks of the senior-tailored silver yoga (SY) exercise program for transitional frail elders. A convenience sample of 69 elders in assisted living facilities were assigned randomly to the SY group (n = 38) or to the control group (n = 31) on the basis of the facilities where they resided, and 55 of them completed this quasi-experimental pretest and posttest study. Intervention was conducted three times per week, 70 minutes per session, for 24 weeks. Physical fitness (body composition, cardiovascular-respiratory functions, body flexibility, muscle power and endurance, balance, and agility) were examined at baseline, at 12 weeks, and at the end of the 24th week of the study. At the end of the study, the physical fitness indicators of participants in the SY group had improved significantly, and they had better physical fitness than participants in the control group (all p values < .05). It was recommended that the SY exercises be incorporated as an activity program in assisted living facilities to promote the physical fitness of transitional frail elders.

  7. Improving of enzyme immunoassay for detection and quantification of the target molecules using silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Syrvatka, Vasyl J.; Slyvchuk, Yurij I.; Rozgoni, Ivan I.; Gevkan, Ivan I.; Overchuk, Marta O.

    2014-02-01

    Modern routine enzyme immunoassays for detection and quantification of biomolecules have several disadvantages such as high cost, insufficient sensitivity, complexity and long-term execution. The surface plasmon resonance of silver nanoparticles gives reasons of creating new in the basis of simple, highly sensitive and low cost colorimetric assays that can be applied to the detection of small molecules, DNA, proteins and pollutants. The main aim of the study was the improving of enzyme immunoassay for detection and quantification of the target molecules using silver nanoparticles. For this purpose we developed method for synthesis of silver nanoparticles with hyaluronic acid and studied possibility of use these nanoparticles in direct determination of target molecules concentration (in particular proteins) and for improving of enzyme immunoassay. As model we used conventional enzyme immunoassays for determination of progesterone and estradiol concentration. We obtained the possibility to produce silver nanoparticles with hyaluronan homogeneous in size between 10 and 12 nm, soluble and stable in water during long term of storage using modified procedure of silver nanoparticles synthesis. New method allows to obtain silver nanoparticles with strong optical properties at the higher concentrations - 60-90 μg/ml with the peak of absorbance at the wavelength 400 nm. Therefore surface plasmon resonance of silver nanoparticles with hyaluronan and ultraviolet-visible spectroscopy provide an opportunity for rapid determination of target molecules concentration (especial protein). We used silver nanoparticles as enzyme carriers and signal enhancers. Our preliminary data show that silver nanoparticles increased absorbance of samples that allows improving upper limit of determination of estradiol and progesterone concentration.

  8. Contrasted sulphide chemistries in the environment of 13°N EPR vent fauna

    NASA Astrophysics Data System (ADS)

    Le Bris, Nadine; Sarradin, Pierre-Marie; Caprais, Jean-Claude

    2003-06-01

    To improve our understanding of the environmental constraints exerted on vent fauna, we investigated sulphide chemistry in the habitats of Riftia pachyptila and Alvinella pompejana, at the Genesis and Elsa EPR 13°N sites. Temperature, pH and sulphide measurement series were acquired in situ, around the organisms, from the submersible Nautile. Hot fluid samples were also collected to evaluate end-member composition at these sites. Under the assumption of conservative mixing, pH, total sulphide concentration and sulphide speciation gradients in relation to temperature were modelled. From the comparison of measured and calculated concentrations, deviation from conservative behaviour was highlighted for total sulphide versus temperature. While the observed sulphide depletion around tubeworms suggests significant subsurface removal or biological consumption, the apparent sulphide enrichment in the alvinellid environment may reveal either conductive cooling of diffusing fluids or a secondary sulphide source. The calculated sulphide speciation appears to be contrasted at the two sites studied. Because of the low iron content in Genesis fluid, iron sulphide would not constitute a dominant sulphide species and the toxic H 2S form would be predominant in the mixing zone. By contrast, iron is expected to play a dominant role in sulphide speciation at the Elsa site where the end-member is iron rich. With respect to sulphide, the conditions encountered in the different habitats considered in this study are strongly contrasted. A low fluid flux was observed in the R. pachyptila habitat, contrasting with previous ideas, and suggests that sulphide availability could be a major limiting factor. Particularly, the bioavailable HS - form is expected to vary weakly along the mixing gradient. In contrast, sulphide in the A. pompejana environment is shown to be particularly high, about one order of magnitude higher than observed for other Eastern Pacific alvinellids. At Genesis, because

  9. Silver-containing mesoporous bioactive glass with improved antibacterial properties.

    PubMed

    Gargiulo, Nicola; Cusano, Angela Maria; Causa, Filippo; Caputo, Domenico; Netti, Paolo Antonio

    2013-09-01

    The aim of the present work is the study of the bacteriostatic/bactericidal effect of a silver-containing mesoporous bioactive glass obtained by evaporation-induced self-assembly and successive thermal stabilization. Samples of the manufactured mesophase were characterized by means of transmission electron microscopy and N₂ adsorption/desorption at 77 K, revealing structural and textural properties similar to SBA-15 mesoporous silica. Glass samples used for bioactivity experiments were put in contact with a standardized, commercially available cell culture medium instead of lab-produced simulated body fluid, and were then characterized by means of X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. All these analyses confirmed the development of a hydroxyl carbonate apatite layer on glass particles. Moreover, the investigated mesostructure showed a very good antibacterial effect against S. aureus strain, with a strong evidence of bactericidal activity already registered at 0.5 mg/mL of glass concentration. A hypothesis about the mechanism by which Ag affects the bacterial viability, based on the intermediate formation of crystalline AgCl, was also taken into account. With respect to what already reported in the literature, these findings claim a deeper insight into the possible use of silver-containing bioactive glasses as multifunctional ceramic coatings for orthopedic devices.

  10. Improved spatial frequency response in silver halide sensitized gelatin holograms

    NASA Astrophysics Data System (ADS)

    Beléndez, A.; Neipp, C.; Pascual, I.

    1998-10-01

    We report what we believe to be the best results obtained to date with regard to the spatial frequency response of silver halide sensitized gelatin (SHSG) holograms. A very high diffraction efficiency, as high as 91% (after allowing for reflection), and an almost flat spatial frequency response between 800 lines/mm and 2800 lines/mm have been achieved using the new BB-640 plates manufactured by Holographic Recording Technologies. The results are compared with those for gratings recorded in the familiar Agfa 8E75 HD emulsion under the same recording and processing conditions. Theoretical results obtained using Buschmann's weakly scattering model are also compared. Our investigations reveal that high quality SHSG transmission holograms with high spatial frequencies and an almost flat spatial frequency response may be obtained using the new BB-640 plates.

  11. Silver concentrations in Colorado, USA, watersheds using improved methodology.

    PubMed

    Wen, Liang-Saw; Santschi, Peter H; Gill, Gary A; Tang, Degui

    2002-10-01

    River water samples were collected at five sites in the state of Colorado, USA, to assess the impact of municipal and industrial discharges on Ag concentrations and speciation in surface waters. Samples were collected and analyzed for total (unfiltered collections), filtered (0.1 and 0.4 microm), particulate (> or = 0.45 microm), and colloidal Ag (3 kDa-0.1 m) using ultraclean protocols. A series of laboratory experiments were conducted to assess bias from sample storage, digestion, and preconcentration protocols. In general, upstream unfiltered and particulate Ag concentrations fell within a fairly narrow range, 3.1 to 21 ng/L and 0.2 to 1.7 microg/g, respectively. Downstream unfiltered and particulate Ag concentrations showed a more broad range, 2.8 to 1,110 ng/L and 0.5 to 104 microg/g, respectively, and reflected attenuated impacts of Ag-laden discharge effluents. However, Ag concentrations in the 0.1-microm filter-passing fraction 0.8 to 1.2 km downstream from major treatment plant effluents were all below the chronic silver criteria. On average, more than 60% of the 0.1-microm filter-passing Ag was associated with colloidal macromolecular organic matter. Silver concentrations in colloids (microg/g) were, on average, the same as those in suspended particulate matter. The percentage abundance of colloidal Ag was similar to that of dissolved organic carbon, suggesting that strong Ag binding ligands exist in both the colloidal and the particle size fractions, as these macromolecular ligands likely play a major role in Ag speciation.

  12. Metal sulphides from wastewater: assessing the impact of supersaturation control strategies.

    PubMed

    Mokone, T P; van Hille, R P; Lewis, A E

    2012-05-01

    Metal sulphide precipitation forms an important component of acid mine drainage remediation systems based on bacterial sulphate reduction. However, the precipitation reaction is inherently driven by very high levels of supersaturation with the generation of small particles with poor solid-liquid separation characteristics. In this study, the effect of strategies used to manage supersaturation was investigated during copper and zinc sulphide precipitation reactions. Initial batch studies showed the origin of sulphide (biological or chemical) had no significant effect on the efficiency of zinc sulphide precipitation. For copper, low metal removal efficiency was obtained at metal to sulphide molar ratios below 1.6 in the synthetic sulphide system. This was improved in the biogenic sulphide system, due to the presence of residual volatile fatty acids, but the presence or absence of particulate organic matter had no effect on recovery. Subsequent studies, conducted using synthetic sulphide solutions in a seeded fluidised bed reactor with multiple reagent feed points (2FP and 6FP) and different recirculation flow rates (300 and 120 mL min(-1)) showed efficient zinc sulphide precipitation, but limited (<10%) deposition on the seeds. Increasing the number of sulphide feed points (2-6) reduced precipitate loss as fines by approximately 10%. Zinc sulphide fines could be effectively recovered from suspension by settling under quiescent conditions. In the copper system, metal recovery was low (ca 40%) due to the formation of very small copper sulphide particles (mean particle size of ca 0.01 μm). Increasing the number of reagent feed points did not affect supersaturation to the extent of altering particle characteristics. The copper sulphide fines could not be recovered by settling, remaining in a stable colloidal suspension due to their highly charged surfaces (zeta potential -50 mV). The change in recirculation flow rate had a limited effect (ca 5% improvement) on process

  13. A nanofilter composed of carbon nanotube-silver composites for virus removal and antibacterial activity improvement.

    PubMed

    Kim, Jun Pyo; Kim, Jae Ha; Kim, Jieun; Lee, Soo No; Park, Han-Oh

    2016-04-01

    We have developed a new nanofilter using a carbon nanotube-silver composite material that is capable of efficiently removing waterborne viruses and bacteria. The nanofilter was subjected to plasma surface treatment to enhance its flow rate, which was improved by approximately 62%. Nanoscale pores were obtained by fabricating a carbon nanotube network and using nanoparticle fixation technology for the removal of viruses. The pore size of the nanofilter was approximately 38 nm and the measured flow rate ranged from 21.0 to 97.2L/(min·m(2)) under a pressure of 1-6 kgf/cm(2) when the amount of loaded carbon nanotube-silver composite was 1.0 mg/cm(2). The nanofilter was tested against Polio-, Noro-, and Coxsackie viruses using a sensitive real-time polymerase chain reaction assay to detect the presence of viral particles within the outflow. No trace of viruses was found to flow through the nanofilter with carbon nanotube-silver composite loaded above 0.8 mg/cm(2). Moreover, the surface of the filter has antibacterial properties to prevent bacterial clogging due to the presence of 20-nm silver nanoparticles, which were synthesized on the carbon nanotube surface.

  14. Cycle-life improvement study for secondary silver-zinc batteries

    SciTech Connect

    Giltner, L.J.

    1997-12-01

    This paper presents an introductory discussion of the general characteristics and advantages of the silver-zinc, manually activated, rechargeable battery. Cycle-life limitations are discussed and the test results of a cycle-life improvement study, completed in 1995, are provided. The results of this study indicate a significant improvement in cycle-life over the baseline design for certain variations in the separator system. The silver-zinc (Ag-Zn) battery system has been uniquely efficient to satisfy high energy density applications in a very extensive range of commercial, military, aerospace and marine applications. These programs have demonstrated the high reliability and safety of this battery system for over forty years.

  15. Environmental Assessment: Improvements to Silver Flag Training Area at Tyndall Air Force Base, Florida

    DTIC Science & Technology

    2013-01-01

    The Proposed Action involves various improvements to the Silver Flag Training Area at Tyndall AFB. The following seven projects are proposed under... roof and no side walls. The structure would provide covered parking for 16 MRAP vehicles. 2.1.6 Construct Latrine/Shower/Laundry Facility...metal roof . 2.1.7 Convert Spray Field to Bed-Down Training Site This project would involve converting the existing inactive domestic wastewater

  16. Collagen nanofiber containing silver nanoparticles for improved wound-healing applications.

    PubMed

    Rath, Goutam; Hussain, Taqadus; Chauhan, Gaurav; Garg, Tarun; Goyal, Amit Kumar

    2016-01-01

    Electrospun nanofibers showing great promise for fabricating nanostructured materials might help to improve the quality of wound care. The present study aimed to investigate the wound-healing potential of collagen nanofiber mats containing silver nanoparticles. Silver nanoparticles (AgNPs) synthesized by the chemical reduction method were incorporated in collagen nanofibers during the electrospinning process. Characterization of electrospun nanofiber mats revealed a mean fiber diameters in the range of 300-700 nm with a sustained release of silver ions shown to follow pseudo-order kinetics. MIC of AgNPs against Staphylococcus aureus and Pseudomonas aeruginosa were evaluated using micro-dilution assay and further antimicrobial activity of fabricated nanofibers was performed. Finally, in vivo studies were performed to demonstrate the wound-healing efficacy of composite nanofibers. In vitro results confirmed the potential antimicrobial efficacy provided by AgNPs and AgNPs composite nanofibers, essential to provide an aseptic environment at the wound site. In vivo study revealed that the rate of wound healing of the composite nanofiber mats was found to be accelerated compared with plain collagen nanofibers. Histology analysis revealed an accelerated re-epithelization, collagen production, and better wound contraction with AgNPs composite collagen nanofibers.

  17. Sputtered silver films to improve chromium carbide based solid lubricant coatings for use to 900 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Sliney, Harold E.; Deadmore, Daniel L.

    1988-01-01

    Thin silver films, 250 to 3500 A thick, were sputtered onto PS200, a plasma sprayed, chromium carbide based solid lubricant coating, to reduce run-in wear and improve tribological properties. The coating contains bonded chromium carbide as the wear resistant base stock with silver and barium fluoride/calcium fluoride eutectic added as low and high temperature lubricants, respectively. Potential applications for the PS200 coating are cylinder wall/piston ring lubrication for Stirling engines and foil bearing journal lubrication. In this preliminary program, the silver film overlay thickness was optimized based on tests using a pin-on-disk tribometer. The friction and wear studies were performed in a helium atmosphere at temperatures from 25 to 760 C with a sliding velocity of 2.7 m/s under a 4.9 N load. Films between 1000 and 1500 A provide the best lubrication of the counterface material. The films enrich the sliding surface with lubricant and reduce the initial abrasiveness of the as ground, plasma-sprayed coating surface, thus reducing wear.

  18. Sputtered silver films to improve chromium carbide based solid lubricant coatings for use to 900 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Sliney, Harold E.; Deadmore, Daniel L.

    1988-01-01

    Thin silver films, 250 to 3500 A thick, were sputtered onto PS200, a plasma sprayed, chromium carbide based solid lubricant coating, to reduce run-in wear and improve tribological properties. The coating contains bonded chromium carbide as the wear resistant base stock with silver and barium fluoride/calcium fluoride eutectic added as low and high temperature lubricants respectively. Potential applications for the PS200 coating are cylinder wall/piston ring lubrication for Stirling engines and foil bearing journal lubrication. In this preliminary program, the silver film overlay thickness was optimized based on tests using a pin-on-disk tribometer. The friction and wear studies were performed in a helium atmosphere at temperatures from 25 to 760 C with a sliding velocity of 2.7 m/s under a 4.9 N load. Films between 1000 and 1500 A provide the best lubrication of the counterface material. The films enrich the sliding surface with lubricant and reduce the initial abrasiveness of the as ground, plasma-sprayed coating surface, thus reducing wear.

  19. Sputtered silver films to improve chromium carbide based solid lubricant coatings for use to 900 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Sliney, Harold E.; Deadmore, Daniel L.

    1988-01-01

    Thin silver films, 250 to 3500 A thick, were sputtered onto PS200, a plasma sprayed, chromium carbide based solid lubricant coating, to reduce run-in wear and improve tribological properties. The coating contains bonded chromium carbide as the wear resistant base stock with silver and barium fluoride/calcium fluoride eutectic added as low and high temperature lubricants, respectively. Potential applications for the PS200 coating are cylinder wall/piston ring lubrication for Stirling engines and foil bearing journal lubrication. In this preliminary program, the silver film overlay thickness was optimized based on tests using a pin-on-disk tribometer. The friction and wear studies were performed in a helium atmosphere at temperatures from 25 to 760 C with a sliding velocity of 2.7 m/s under a 4.9 N load. Films between 1000 and 1500 A provide the best lubrication of the counterface material. The films enrich the sliding surface with lubricant and reduce the initial abrasiveness of the as ground, plasma-sprayed coating surface, thus reducing wear.

  20. Improving the chemiluminescence-based determination of sulphide in complex environmental samples by using a new, automated multi-syringe flow injection analysis system coupled to a gas diffusion unit.

    PubMed

    Maya, Fernando; Estela, José Manuel; Cerdà, Víctor

    2007-10-03

    A new, completely automated multi-syringe flow injection analysis (MSFIA) system coupled to a gas diffusion unit (GDU) was used for the chemiluminescence (CL)-based determination of sulphide ion in various types of environmental matrices with a high sensitivity and selectivity, and the need for no manual sample pretreatment. Sulphide ions are transferred as H(2)S from the donor channel of the GDU to its acceptor channel (AC) through a hydrophobic membrane inserted between the two streams. The solution held in AC replaces the initial sample matrix, which may contain a wide variety of interferents, with one suitable for the CL determination of the analyte. Once sulphide ions have been isolated from the sample matrix, they are determined by their catalytic action on the luminol/H(2)O(2) chemiluminescent reaction system. The influence of various chemical and hydrodynamic variables is discussed and the performance of the proposed system compared with that of existing flow systems for the same purpose. Under the operating conditions used, the proposed method features a linear working range of 0.02-2 mgL(-1), a limit of detection (3 sigma(blank)) of 0.003 mgL(-1), a throughput of 20 samplesh(-1) and a coefficient of variation of 2.4% (n=10) for a 1 mgL(-1) sulphide concentration. The method was used to determine sulphide in leachates and various types of water samples.

  1. Mercury sulphide dimorphism in glasses

    SciTech Connect

    Kassem, Mohammad; Sokolov, Anton; Cuisset, Arnault; Usuki, Takeshi; Khaoulani, Sohayb; Masselin, Pascal; Le Coq, David; Neuefeind, Joerg C.; Feygenson, Mikhail; Hannon, Alex; Benmore, C. J.; Bychkov, E.

    2016-05-23

    Crystals usually exist in several polymorphic forms in different domains of the P,T-diagram. Glasses and liquids also reveal density- or entropy-driven polyamorphism when e.g. an amorphous molecular solid or liquid transforms into a network polymorph. Using pulsed neutron and high-energy X-ray diffraction, we show that mercury sulphide exists simultaneously in two polymorphic modifications in a glass network forming chain-like and tetrahedral motifs. DFT simulations of 4-fold coordinated mercury species and RMC modelling of high-resolution diffraction data provide additional details on local Hg environment and connectivity implying the (HgS2/2)m oligomeric chains (1 m 6) are acting as a network former while the HgS4/4-related mixed agglomerated units behave as a modifier

  2. Mercury sulphide dimorphism in glasses

    DOE PAGES

    Kassem, Mohammad; Sokolov, Anton; Cuisset, Arnault; ...

    2016-05-23

    Crystals usually exist in several polymorphic forms in different domains of the P,T-diagram. Glasses and liquids also reveal density- or entropy-driven polyamorphism when e.g. an amorphous molecular solid or liquid transforms into a network polymorph. Using pulsed neutron and high-energy X-ray diffraction, we show that mercury sulphide exists simultaneously in two polymorphic modifications in a glass network forming chain-like and tetrahedral motifs. DFT simulations of 4-fold coordinated mercury species and RMC modelling of high-resolution diffraction data provide additional details on local Hg environment and connectivity implying the (HgS2/2)m oligomeric chains (1 m 6) are acting as a network former whilemore » the HgS4/4-related mixed agglomerated units behave as a modifier« less

  3. Lead sulphide nanocrystal photodetector technologies

    NASA Astrophysics Data System (ADS)

    Saran, Rinku; Curry, Richard J.

    2016-02-01

    Light detection is the underlying principle of many optoelectronic systems. For decades, semiconductors including silicon carbide, silicon, indium gallium arsenide and germanium have dominated the photodetector industry. They can show excellent photosensitivity but are limited by one or more aspects, such as high production cost, high-temperature processing, flexible substrate incompatibility, limited spectral range or a requirement for cryogenic cooling for efficient operation. Recently lead sulphide (PbS) nanocrystals have emerged as one of the most promising new materials for photodetector fabrication. They offer several advantages including low-cost manufacturing, solution processability, size-tunable spectral sensitivity and flexible substrate compatibility, and they have achieved figures of merit outperforming conventional photodetectors. We review the underlying concepts, breakthroughs and remaining challenges in photodetector technologies based on PbS nanocrystals.

  4. Mercury sulphide dimorphism in glasses

    SciTech Connect

    Kassem, Mohammad; Sokolov, Anton; Cuisset, Arnault; Usuki, Takeshi; Khaoulani, Sohayb; Masselin, Pascal; Le Coq, David; Neuefeind, Joerg C.; Feygenson, Mikhail; Hannon, Alex; Benmore, C. J.; Bychkov, E.

    2016-05-23

    Crystals usually exist in several polymorphic forms in different domains of the P,T-diagram. Glasses and liquids also reveal density- or entropy-driven polyamorphism when e.g. an amorphous molecular solid or liquid transforms into a network polymorph. Using pulsed neutron and high-energy X-ray diffraction, we show that mercury sulphide exists simultaneously in two polymorphic modifications in a glass network forming chain-like and tetrahedral motifs. DFT simulations of 4-fold coordinated mercury species and RMC modelling of high-resolution diffraction data provide additional details on local Hg environment and connectivity implying the (HgS2/2)m oligomeric chains (1 m 6) are acting as a network former while the HgS4/4-related mixed agglomerated units behave as a modifier

  5. Environmental Assessment Improvements to Silver Flag Training Area at Tyndall Air Force Base, Florida

    DTIC Science & Technology

    2013-08-02

    Installation Compatible Use Zone program, soils , wetlands, smface water, floodplains , vegetation, fish and wildlife, listed species, land use...Pinus elliottii) and   North Source: Tyndall AFB INRMP FIGURE 3-7 100-Year Floodplains at Tyndall AFB EA for Improvements to Silver Flag Training...greater  soil  impacts  than Alternative 1. Appropriate BMPs and erosion/ sedimentation  controls would be implemented during  construction of Alternative 2a

  6. Passive airborne EM and ground IP\\resistivity results over the Romero intermediate sulphidation epithermal gold deposits, Dominican Republic

    NASA Astrophysics Data System (ADS)

    Legault, Jean M.; Niemi, Jeremy; Brett, Jeremy S. Zhao, Shengkai; Han, Zihao; Plastow, Geoffrey C.

    2016-04-01

    The Romero gold-copper-zinc-silver deposits are located in the Province of San Juan, Dominican Republic, ~165 km west-north-west of Santo Domingo. Romero and Romero South orebodies contain stratabound gold mineralisation with copper, silver and zinc of intermediate sulphidation (IS), epithermal style. The gold mineralisation is associated with disseminated to semi-massive sulphides, sulphide veinlets and quartz-sulphide veins within quartz-pyrite, quartz-illite-pyrite and illite-chlorite-pyrite alteration. Ground direct current (DC) resistivity and induced polarisation (IP) supported by ground magnetics remain the preferred geophysical targeting tools for drill follow-up along with geologic mapping and geochemistry. However, Z-axis tipper electromagnetics (ZTEM) passive airborne electromagnetics (AEM) and magnetics have recently also been applied with success for reconnaissance mapping of deep alteration and fault structures regionally. The airborne ZTEM-magnetic surveys, supported by three-dimensional (3D) inversions, show good correlation with the ground IP\\resistivity surveys in the Romero and Romero South gold-copper-zinc-silver IS deposit area. The results have provided targets for ground follow-up and deep targeted drilling, and were successful in identifying a previously unknown deep (>500 m) continuity between the Romero and Romero South deposits.

  7. Ion Implantation of Zinc Sulphide Thin Films,

    DTIC Science & Technology

    The report considers the use of ion implantation as a means of preparing rare earth doped thin films of zinc sulphide, and presents preliminary results on the luminescence of such films doped with Tb and Er166 ions. (Author)

  8. Evaluation of autotrophic and heterotrophic processes in biofilm reactors used for removal of sulphide, nitrate and COD.

    PubMed

    Tang, Kimberley; An, Shijie; Nemati, Mehdi

    2010-11-01

    Microbial cultures originated from an oil reservoir were used in three biofilm reactors and effects of sulphide and nitrate loading rates and molar loading ratio on the removal of sulphide, nitrate and acetate, and composition of end products were investigated. Application of biofilms improved sulphide and nitrate removal rates significantly when compared with freely suspended cells. Maximum sulphide and nitrate removal rates under autotrophic conditions were 30.0 and 24.4 mM h(-1), respectively (residence time: 0.5h). Oxidation of acetate occurred only at nitrate to sulphide molar loading ratios around 0.7 or higher when nitrate was present at levels higher than that required for oxidation of sulphide to sulphur. Conversion of sulphide to sulphate increased from 0% to 66% as nitrate to sulphide molar loading ratio was increased from 0.34 to 3.98. The highest nitrate and acetate removal rates in the bioreactor operated under heterotrophic conditions were 183.2 and 88.0 mM h(-1), respectively (residence time: 0.8h). Copyright 2010 Elsevier Ltd. All rights reserved.

  9. Development of silver-zinc cells of improved cycle life and energy density

    NASA Astrophysics Data System (ADS)

    Serenyi, Roberto; James, Stanley D.

    1994-03-01

    Substantial increases in the cost effectiveness and range of naval underwater vehicles are possible by virtue of advances made, in this program, to silver-zinc, vehicle propulsion batteries. To improve battery cycle life and energy density, electropermeable membranes (EPM's) were used as additives and/or as coatings for the negative electrodes and as coatings for conventional separator materials. Also, bismuth oxide was tested as an additive to the negative electrodes and P2291-40/20, a radiation-grafted polyethylene film, as a separator used in conjunction with silver-treated cellophane. EPM's used as negative electrode additives and also as coatings for Celgard 2500 microporous polypropylene greatly improved cells. Cells with EPM's used as coatings for the negative electrodes failed rapidly because of an error in formulation. Cells with 10 percent bismuth oxide in the negative electrodes exhibited substantially lower capacity than the standard cells and were removed from the test. Cells with radiation-grafted polyethylene separators provided fewer cycles than the standard cells, with 5 percent higher capacity and 6 percent lower utilization of active materials by cycle 60. However, the slightly better capacity of these cells, realized due to the additional space available for active materials, does not compensate for their generally unimpressive performance.

  10. Use of Atomic Layer Deposition to Improve the Stability of Silver Substrates for In-Situ, High Temperature SERS Measurements

    SciTech Connect

    John, Joshy; Mahurin, Shannon Mark; Dai, Sheng; Sepaniak, Michael

    2010-01-01

    A method to stabilize silver surface-enhanced Raman spectroscopy (SERS) substrates for in-situ, high temperature applications is demonstrated. Silver island films grown by thermal evaporation were coated with a thin layer (from 2.5nm to 5nm) of alumina by atomic layer deposition (ALD), which protects and stabilizes the SERS-active substrate without eliminating the Raman enhancement. The temporal stability of the alumina-coated silver island films was examined by measurement of the Raman intensity of rhodamine 6G molecules deposited onto bare and alumina-coated silver substrates over the course of thirty-four days. The coated substrates showed almost no change in SERS enhancement while the uncoated substrates exhibited a significant decrease in Raman intensity. To demonstrate the feasibility of the alumina-coated silver substrate as a probe of adsorbates and reactions at elevated temperatures, an in-situ SERS measurement of calcium nitrate tetrahydrate on bare and alumina-coated silver was performed at temperatures ranging from 25 C to 400 C. ALD deposition of an ultrathin alumina layer significantly improved the thermal stability of the SERS substrate thus enabling in-situ detection of the dehydration of the calcium nitrate tetrahydrate at elevated temperature. Despite some loss of Raman signal, the coated substrate exhibited greater thermal stability compared to the uncoated substrate. These experiments show that ALD can be used to synthesize stable SERS substrates capable of measuring adsorbates and processes at high temperature.

  11. Luminescent CuS nanotubes as silver ion probes.

    PubMed

    Zhang, Xiaojun; Wang, Guangfeng

    2009-06-01

    CuS nanotubes (NTs) made up of nanoparticles were successfully prepared in large quantities in an O/W microemulsion system under low temperature. Based on the characteristics of synchronous fluorescence spectroscopy (SFS), a new method with high sensitivity and selectivity was developed for rapid determination of silver ion with functional copper sulphide (CuS) nanotubes as a fluorescence probe. Under optimal conditions, functional copper sulphide displayed a calibration response for silver ion over a wide concentration range from 1.0x10(-10) to 1.0x10(-8)molL(-1). The limit of detection was 0.5x10(-10)molL(-1) and the relative standard deviation of eight replicate measurements for the highest concentration (1x10(-8)molL(-1)) was 3%. Compared with several fluorescence methods, the proposed method had a wider linear range and improved the sensitivity. Furthermore, the concentration dependence of the synchronous fluorescence intensity is effectively described by a Langmuir-type binding isotherm.

  12. Evidence for iron, copper and zinc complexation as multinuclear sulphide clusters in oxic rivers

    PubMed

    Rozan; Lassman; Ridge; Luther

    2000-08-24

    The availability and toxicity of trace metals in fresh water are known to be regulated by the complexation of free metal ions with dissolved organic matter. The potential role of inorganic sulphides in binding trace metals has been largely ignored because of the reduced persistence of sulphides in these oxic waters. However, nanomolar concentrations of copper and zinc sulphides have been observed in four rivers in Connecticut and Maryland. Here we report dissolved (< 0.2 microm particle diameter) sulphide concentrations ranging up to 600 nM, with more than 90% being complexed by copper, iron and zinc. These complexes account for up to 20% of the total dissolved Fe and Zn and 45% of the total dissolved Cu. Fourier transform mass spectrometry reveals that these complexes are not simple M(HS)+ protonated species but are higher-order unprotonated clusters (M3S3, M4S6, M2S4), similar to those found in laboratory solutions and bio-inorganic molecules. These extended structures have high stability constants and are resistant to oxidation and dissociation, which may help control the toxicity of these and other less abundant, but more toxic, trace metals, such as silver, cadmium and mercury.

  13. Contact resistance improvement using interfacial silver nanoparticles in amorphous indium-zinc-oxide thin film transistors

    SciTech Connect

    Xu, Rui; He, Jian; Song, Yang; Li, Wei; Zaslavsky, A.; Paine, D. C.

    2014-09-01

    We describe an approach to reduce the contact resistance at compositional conducting/semiconducting indium-zinc-oxide (IZO) homojunctions used for contacts in thin film transistors (TFTs). By introducing silver nanoparticles (Ag NPs) at the homojunction interface between the conducting IZO electrodes and the amorphous IZO channel, we reduce the specific contact resistance, obtained by transmission line model measurements, down to ∼10{sup −2 }Ω cm{sup 2}, ∼3 orders of magnitude lower than either NP-free homojunction contacts or solid Ag metal contacts. The resulting back-gated TFTs with Ag NP contacts exhibit good field effect mobility of ∼27 cm{sup 2}/V s and an on/off ratio >10{sup 7}. We attribute the improved contact resistance to electric field concentration by the Ag NPs.

  14. Development of silver-zinc cells of improved cycle life and energy density. Final report

    SciTech Connect

    Serenyi, R.

    1996-04-01

    This document describes a Small Business Innovative Research (SBIR) Phase II program. The research was designed to improve the cycle life and energy density of silver zinc cells, particularly those used in naval propulsion systems, by advancing the state of the art of the negative electrode and the separator, which are responsible for most of the shortcomings of this electrochemical couple. Yardney relied on a new class of materials, known as Electro-Permeable Membranes, which were used as additives and/or coatings for the negative electrodes and also as coatings for conventional separator materials, such as cellophane and Celgard (microporous polypropylene). In addition, the use of bismuth oxide in conjunction with other additives to the negative electrode was shown to have a beneficial effect on cycle life and to reduce the hydrogen gassing of charged cells by up to 70%.

  15. In Situ Generation of Photosensitive Silver Halide for Improving the Conductivity of Electrically Conductive Adhesives.

    PubMed

    Li, Chaowei; Li, Qiulong; Long, Xiaoyang; Li, Taotao; Zhao, Jingxin; Zhang, Kai; E, Songfeng; Zhang, Jun; Li, Zhuo; Yao, Yagang

    2017-08-30

    Electrically conductive adhesives (ECAs) can be regarded as one of the most promising materials to replace tin/lead solder. However, relatively low conductivity seriously restricts their applications. In the present study, we develop an effective method to decrease the bulk electrical resistivity of ECAs. KI or KBr is added to replace the lubricant and silver oxide layers on silver flakes and to form photosensitive silver halide. After exposure to sunlight, silver halide can photodecompose into silver nanoparticles that will sinter and form metallic bonding between/among flakes during the curing process of ECAs, which would remarkably reduce the resistivity. The modified micro silver flakes play a crucial role in decreasing the electrical resistivity of the corresponding ECAs, exhibiting the lowest resistivity of 7.6 × 10(-5) Ω·cm for 70 wt % loaded ECAs. The obtained ECAs can have wide applications in the electronics industry, where high conductance is required.

  16. Gallium Lanthanum Sulphide Fibers for Infrared Transmission

    NASA Astrophysics Data System (ADS)

    West, Y. D.; Schweizer, T.; Brady, D. J.; Hewak, D. W.

    Gallium lanthanum sulphide (GLS) glass and fiber have potential for use in both active and passive infrared applications. In this paper the optical, thermal, and other key properties, which are essential for understanding the applications and crucial in the quest for practical fibres, are discussed. Glass preparation by melt-quenchingand subsequent fibre fabrication is described using both rod-in-tube and extruded preforms. Absorptive and scattering losses are explored as they could represent a fundamental limitation to successful device fabrication. Potential passive and active applications are reported and the prospects for a future generation of sulphide fiber-based devices examined.

  17. Improvement of photocatalytic activity of silver nanoparticles by radio frequency oxygen plasma irradiation

    NASA Astrophysics Data System (ADS)

    Fang, Yingcui; Zhang, Bing; Hong, Liu; Yao, Damao; Xie, Zhiqiang; Jiang, Yang

    2015-07-01

    Photocatalytic activity (PA) of silver nanoparticles (AgNPs) induced by radio frequency (RF) oxygen plasma irradiation (OPI) is investigated in this paper. An improvement in PA by 365% and 181% has been achieved when 15 nm AgNPs irradiated by oxygen plasma for 2 s were used to degrade 10-5 M Rhodamine 6 G (R6G) under ultraviolet (UV) and visible lights, respectively. The PA caused by OPI is better than that induced by the localized surface plasma resonance (LSPR) of AgNPs. The mechanism for the improvement was explored by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectra. The OPI-induced formation of AgO/AgNP and Ag2O/AgNP-heterogeneous photocatalysts and electrophilic oxygen are considered to be responsible for the PA improvement. This investigation deepens our understanding of oxygen-assisted photocatalysis of AgNPs and provides a practical approach using solar light for broad spectra photocatalysis with high efficiency.

  18. Nanoscale silver depositions inhibit microbial colonization and improve biocompatibility of titanium abutments.

    PubMed

    Kheur, Supriya; Singh, Nimisha; Bodas, Dhananjay; Rauch, Jean-Yves; Jambhekar, Shantanu; Kheur, Mohit; Rajwade, Jyutika

    2017-07-29

    Although titanium dental implants are biocompatible, exhibit excellent corrosion resistance and high mechanical resistance, the material fails in providing resistance to infection because it exhibits poor antimicrobial activity. To address these issues, we deposited silver onto titanium abutments (Grade 5 titanium discs) using direct current (DC) sputtering and assessed the antimicrobial activity and biocompatibility of the modified implant material. Atomic absorption spectrometry and X-ray photoelectron spectroscopy were employed to investigate the concentration and elemental composition of the deposited silver. As expected, silver deposited using DC plasma was uniform and good control over the deposition could be achieved by varying the sputtering time. Moderate biocompatible responses (up to 69% viability) were observed in primary human gingival fibroblast cells incubated in the presence of Ti sputtered with Ag for 5min. Silver deposited titanium (Ti-Ag) showed excellent antibacterial effects on Pseudomonas aeruginosa and Streptococcus mutans at a very low concentration (Ag content 1.2 and 2.1μg/mm(2)). However, higher concentration of silver (6μg/mm(2)) was required to achieve a reduction in cell viability of Staphylococcus aureus and Candida albicans. The silver sputtered Ti abutments could maintain a long-term antibacterial activity as evidenced by the release of silver up to 22days in simulated body fluid. Our study illustrates that silver deposited titanium is indeed a promising candidate for soft tissue integration on dental abutments and prevents initial microbial adhesion. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Fatal hydrogen sulphide poisoning in unconfined spaces.

    PubMed

    Nogué, S; Pou, R; Fernández, J; Sanz-Gallén, P

    2011-05-01

    Fatal hydrogen sulphide poisoning usually occurs in confined spaces. We report two fatal accidents in unconfined spaces. The first accident caused the death of three workers who entered an unconfined room in a silo of sludge at the same time that a truck dumped several tons of sludge from water purification stations. The hydrogen sulphide that had accumulated inside the silo spilled out into the interior of the room due to a 'splashing effect' caused by the impact of the dumped sludge. The second accident occurred when the foreman of a wastewater treatment plant entered one of the substations to perform routine checks and suddenly lost consciousness. Although he was rapidly transferred to an intensive care unit, death occurred a few hours later. Hydrogen sulphide production was, in this case, due to an 'embolism effect' produced by the displacement of wastewater when the substation pumps were activated. We suggest ways in which accidents such as these caused by sudden release of hydrogen sulphide can be prevented.

  20. Electrochemically prepared surface-enhanced Raman scattering-active silver substrates with improved stabilities

    NASA Astrophysics Data System (ADS)

    Yang, Kuang-Hsuan; Liu, Yu-Chuan; Yu, Chung-Chin; Chen, Bo-Chuen

    2011-01-01

    In this work, SiO 2 nanoparticles-modified surface-enhanced Raman scattering (SERS)-active silver substrates were prepared by electrochemical oxidation-reduction cycles (ORC) methods in 0.1 N HCl aqueous solutions containing 1 mM SiO 2 nanoparticles to improve their thermal stabilities and anti-aging abilities in SERS performances. Then these SERS-active substrates were further modified with different contents of SiO 2 nanoparticles to improve their corresponding SERS performances. Experimental results indicate that the operation temperature can be significantly raised from 125 to 175 °C based on this modified SERS-active Ag substrate. Also, the aging in SERS intensity is also depressed on this modified Ag substrate due to the contribution of SiO 2 nanoparticles. Moreover, the SERS enhancement capability on this modified Ag substrate is gradually raised from 25 °C to a maximum at 55 °C and monotonically decreased from 55 to 60 °C. This is a 10 °C delay as compared with the similar phenomenon observed on the unmodified Ag substrate.

  1. Improving SERS activity of inositol hexaphosphate capped silver nanoparticles: Fe3+ as a switcher.

    PubMed

    Guo, Xiaoyu; Fu, Yichen; Fu, Shuyue; Wang, Hui; Yang, Tianxi; Wen, Ying; Yang, Haifeng

    2014-07-21

    Inositol hexaphosphate (IP6) capped silver nanoparticles (IP6@AgNPs) were fabricated as surface-enhanced Raman scattering (SERS) active substrates. SERS activity of IP6@AgNPs could be further improved via adding due amounts of Fe(3+) to form Fe(3+)-IP6@AgNPs. The mechanism of Fe(3+)-induced SERS improvement of IP6@AgNPs can be attributed to the strong interaction of IP6 and Fe(3+), which leads to controllable adjustment of the gap among neighboring nanoparticles to produce "hot spots". The above mechanism was confirmed with ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscope (TEM), dynamic light scattering (DLS), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Such Fe(3+)-IP6@AgNPs-based SERS system was used to detect Rhodamine 6G (R6G) down to the trace level of 10(-10) mol L(-1). Besides, New Fuchsin (NF) was also used as a Raman probe to calculate the enhancement factor (EF) of IP6@AgNPs without and with Fe(3+). The SERS activity of IP6@AgNPs happened extreme decrease after one-year storage and could be recovered to great extent aided by the addition of Fe(3+). The Fe(3+) optimized IP6@AgNPs system could be applied to detect thymine at trace level by SERS.

  2. Colloidal silver nanoparticles improve anti-leukemic drug efficacy via amplification of oxidative stress.

    PubMed

    Guo, Dawei; Zhang, Junren; Huang, Zhihai; Jiang, Shanxiang; Gu, Ning

    2015-02-01

    Recently, increased reactive oxygen species (ROS) levels and altered redox status in cancer cells have become a novel therapeutic strategy to improve cancer selectivity over normal cells. It has been known that silver nanoparticles (AgNPs) display anti-leukemic activity via ROS overproduction. Hence, we hypothesized that AgNPs could improve therapeutic efficacy of ROS-generating agents against leukemia cells. In the current study, N-(4-hydroxyphenyl)retinamide (4-HPR), a synthetic retinoid, was used as a drug model of ROS induction to investigate its synergistic effect with AgNPs. The data exhibited that AgNPs with uniform size prepared by an electrochemical method could localize in the lysosomes, mitochondria and cytoplasm of SHI-1 cells. More importantly, AgNPs together with 4-HPR could exhibit more cytotoxicity and apoptosis via overproduction of ROS in comparison with that alone. Taken together, these results reveal that AgNPs combined with ROS-generating drugs could potentially enhance therapeutic efficacy against leukemia cells, thereby providing a novel strategy for AgNPs in leukemia therapy.

  3. Improvement of transmission properties of visible pilot beam for polymer-coated silver hollow fibers with acrylic silicone resin as buffer layer for sturdy structure

    NASA Astrophysics Data System (ADS)

    Iwai, Katsumasa; Takaku, Hiroyuki; Miyagi, Mitsunobu; Shi, Yi-Wei; Zhu, Xiao-Song; Matsuura, Yuji

    2017-02-01

    Flexible hollow fibers with 530-μm-bore size were developed for infrared laser delivery. Sturdy hollow fibers were fabricated by liquid-phase coating techniques. A silica glass capillary is used as the substrate. Acrylic silicone resin is used as a buffer layer and the buffer layer is firstly coated on the inner surface of the capillary to protect the glass tube from chemical damages due to the following silver plating process. A silver layer was inner-plated by using the conventional silver mirror-plating technique. To improve adhesion of catalyst to the buffer layer, a surface conditioner has been introduced in the method of silver mirror-plating technique. We discuss improvement of transmission properties of sturdy polymer-coated silver hollow fibers for the Er:YAG laser and red pilot beam delivery.

  4. A novel 3D sandwich structure of hybrid graphite nanosheets and silver nanowires as fillers for improved thermal conductivity

    NASA Astrophysics Data System (ADS)

    Zhuang, Xiao; Zhou, Yongcun; Liu, Feng

    2017-01-01

    We explored a novel 3D sandwich structure of fillers in the polymer matrix to enhance thermal conductivity. A variety of fillers in the polymer matrix play a significant role in the physical properties of the composite. Fillers containing particle and line structures are popular, and enhance the thermal and electrical conductivities. Therefore, filler-based matrix network improves conductivity. We propose a sandwich structure consisting of hybrid graphite nanosheets (two dimensions), and silver nanowires (AgNWs) (one dimension), to create a 3D sandwich structure of polyimide matrix with improved thermal conductivity. Surface treatment of graphite and silver nanowires were conducted to reduce the dielectric constant of the composite. We designed the filler of 20 wt% resulting in a high thermal conductivity of 3.21 W m-1 K-1 with 15% C@SiO2 and 5% AgNWs@SiO2 filler loading. The novel combination and structure markedly enhanced the thermal conductivity of the composite.

  5. Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach.

    PubMed

    Kou, Pengfei; Yang, Liu; Chang, Cheng; He, Sailing

    2017-02-07

    Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm(2), 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of <20 Ω/sq and transmittance of ~87% at wavelength of 550 nm as well as excellent mechanical flexibility have still been achieved for Ag NW networks after sunlight illumination for 1 hour or longer, which are significant upgrades over those of ITO. Slight plasmonic welding together with the associated self-limiting effect has been investigated by numerical simulations and further verified experimentally through varied solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications.

  6. Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach

    PubMed Central

    Kou, Pengfei; Yang, Liu; Chang, Cheng; He, Sailing

    2017-01-01

    Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm2, 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of <20 Ω/sq and transmittance of ~87% at wavelength of 550 nm as well as excellent mechanical flexibility have still been achieved for Ag NW networks after sunlight illumination for 1 hour or longer, which are significant upgrades over those of ITO. Slight plasmonic welding together with the associated self-limiting effect has been investigated by numerical simulations and further verified experimentally through varied solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications. PMID:28169343

  7. Synthesis and improved SERS performance of silver nanoparticles-decorated surface mesoporous silica microspheres

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Wang, Xiaolong; Zhang, Li; Zhou, Jun; Zhao, Ziqi

    2016-08-01

    This study reported the improved Raman enhancement ability of silver nanoparticles (Ag NPs) decorated on surface mesoporous silica microspheres (MSiO2@Ag) than that of Ag NPs on solid silica microspheres (SSiO2@Ag). These two kinds of hybrid structures were prepared by a facile single-step hydrothermal reaction with polyvinylpyrrolidone (PVP) serves as both a reductant and stabilizer. The as-synthesized MSiO2@Ag microspheres show more significant surface-enhanced Raman scattering (SERS) activity for 4-mercaptobenzoic acid (4MBA) than SSiO2@Ag microspheres with enhancement factors as 9.20 × 106 and 4.39 × 106, respectively. The proposed reason for the higher SERS activity is estimated to be the contribution of more Raman probe molecules at the mesoporous channels where an enhanced electromagnetic field exists. Such a field was identified by theoretical calculation result. The MSiO2@Ag microspheres were eventually demonstrated for the SERS detection of a typical chemical toxin namely methyl parathion with a detection limit as low as 1 × 10-3 ppm, showing its promising potential in biosensor application.

  8. Improved optical sintering efficiency at the contacts of silver nanowires encapsulated by a graphene layer.

    PubMed

    Yang, Seung-Bok; Choi, HongKyw; Lee, Da Som; Choi, Choon-Gi; Choi, Sung-Yool; Kim, Il-Doo

    2015-03-18

    Graphene/silver nanowire (AgNWs) stacked electrodes, i.e., graphene/AgNWs, are fabricated on a glass substrate by air-spray coating of AgNWs followed by subsequent encapsulation via a wet transfer of single-layer graphene (SLG) and multilayer graphene (MLG, reference specimen) sheets. Here, graphene is introduced to improve the optical sintering efficiency of a xenon flash lamp by controlling optical transparency and light absorbing yield in stacked graphene/AgNW electrodes, facilitating the fusion at contacts of AgNWs. Intense pulsed light (IPL) sintering induced ultrafast (<20 ms) welding of AgNW junctions encapsulated by graphene, resulting in approximately a four-fold reduction in the sheet resistance of IPL-treated graphene/AgNWs compared to that of IPL-treated AgNWs. The role of graphene in IPL-treated graphene/AgNWs is further investigated as a passivation layer against thermal oxidation and sulfurization. This work demonstrates that optical sintering is an efficient way to provide fast welding of Ag wire-to-wire junctions in stacked electrodes of graphene/AgNWs, leading to enhanced conductivity as well as superior long-term stability under oxygen and sulfur atmospheres. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach

    NASA Astrophysics Data System (ADS)

    Kou, Pengfei; Yang, Liu; Chang, Cheng; He, Sailing

    2017-02-01

    Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm2, 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of <20 Ω/sq and transmittance of ~87% at wavelength of 550 nm as well as excellent mechanical flexibility have still been achieved for Ag NW networks after sunlight illumination for 1 hour or longer, which are significant upgrades over those of ITO. Slight plasmonic welding together with the associated self-limiting effect has been investigated by numerical simulations and further verified experimentally through varied solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications.

  10. Improving properties of Hanji by coating chitosan-silver nanoparticle solution.

    PubMed

    Jung, Jeyoung; Raghavendra, Gownolla Malegowd; Kim, Dowan; Seo, Jongchul

    2016-12-01

    A chitosan-silver nanoparticle solution (CSNS) was applied as a coating material to Hanji (Korean traditional paper), and the properties of the coated paper were investigated as a function of the dilution ratio. The required CSNS was first prepared from AgNO3 (30mmol) by utilizing chitosan as a reducing and stabilizing agent via ultrasonication. The as-prepared CSNS was diluted to various ratios (undiluted, 1/10, 1/100, and 1/1000) and applied to Hanji by a dip-coating method. The tensile, burst, oil resistance, and antibacterial properties of the coated Hanji against Escherichia coli were evaluated. Among the various dilution ratios, the maximum level of dilution that can positively influence the tensile, burst, oil resistance, and antibacterial properties of Hanji was identified as 1/10, 1/100, 1/10 and 1/1000 of the pure CSNS, respectively. These findings are significant because a specific property of Hanji can be economically improved by changing the dilution ratio. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Improvement of photocatalytic efficiency of rutile titania by silver negative-ion implantation

    NASA Astrophysics Data System (ADS)

    Tsuji, Hiroshi; Sugahara, Hiromitsu; Gotoh, Yasuhito; Ishikawa, Junzo

    2003-05-01

    Optical absorption and photocatalytic properties of metal negative-ion implanted rutile-type titania (TiO 2) were studied to show metal nanoparticle formation in the surface region and improvement of photocatalytic efficiency. Silver negative ions were implanted into titania substrate (rutile crystalline substrate) at 65 keV with a dose of 3 × 10 16-1 × 10 17 ions/cm 2. The Ag-implanted rutile also showed a strong optical absorption near 2.1 eV after annealing above 400 °C, those well agreed with theoretical absorption peaks due to surface plasmon resonance. This means that Ag nanoparticles were formed in the surface layers of the titania. Photocatalytic efficiencies for Ag-implanted titania were evaluated by means of decolorization of methylene blue solution under fluorescent light. Ag-implanted titania (Ag: 65 keV, 5 × 10 16 ions/cm 2, 500 °C annealed) showed the better photocatalytic efficiency higher 2.2 times than that of unimplanted rutile titania. In the evaluation under fluorescent light through UV-cut filter, the Ag-implanted rutile showed 6.7 times better efficiency.

  12. Detection of exhaled hydrogen sulphide gas in rats exposed to intravenous sodium sulphide

    PubMed Central

    Insko, Michael A; Deckwerth, Thomas L; Hill, Paul; Toombs, Christopher F; Szabo, Csaba

    2009-01-01

    Background and purpose: Sodium sulphide (Na2S) disassociates to sodium (Na+) hydrosulphide, anion (HS−) and hydrogen sulphide (H2S) in aqueous solutions. Here we have established and characterized a method to detect H2S gas in the exhaled breath of rats. Experimental approach: Male rats were anaesthetized with ketamine and xylazine, instrumented with intravenous (i.v.) jugular vein catheters, and a tube inserted into the trachea was connected to a pneumotach connected to a H2S gas detector. Sodium sulphide, cysteine or the natural polysulphide compound diallyl disulphide were infused intravenously while the airway was monitored for exhaled H2S real time. Key results: Exhaled sulphide concentration was calculated to be in the range of 0.4–11 ppm in response to i.v. infusion rates ranging between 0.3 and 1.1 mg·kg−1·min−1. When nitric oxide synthesis was inhibited with Nω-nitro-L-arginine methyl ester the amount of H2S exhaled during i.v. infusions of sodium sulphide was significantly increased compared with that obtained with the vehicle control. An increase in circulating nitric oxide using DETA NONOate [3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene] did not alter the levels of exhaled H2S during an i.v. infusion of sodium sulphide. An i.v. bolus of L-cysteine, 1 g·kg−1, and an i.v. infusion of the garlic derived natural compound diallyl disulphide, 1.8 mg·kg−1·min−1, also caused exhalation of H2S gas. Conclusions and implications: This method has shown that significant amounts of H2S are exhaled in rats during sodium sulphide infusions, and the amount exhaled can be modulated by various pharmacological interventions. PMID:19422378

  13. Using a silver-enhanced microarray sandwich structure to improve SERS sensitivity for protein detection.

    PubMed

    Gu, Xuefang; Yan, Yuerong; Jiang, Guoqing; Adkins, Jason; Shi, Jian; Jiang, Guomin; Tian, Shu

    2014-03-01

    A simple and sensitive method, based on surface-enhanced Raman scattering (SERS), for immunoassay and label-free protein detection is reported. A series of bowl-shaped silver cavity arrays were fabricated by electrodeposition using a self-assembled polystyrene spheres template. The reflection spectra of these cavity arrays were recorded as a function of film thickness, and then correlated with SERS enhancement using sodium thiophenolate as the probe molecule. The results reveal that SERS enhancement can be maximized when the frequency of both the incident laser and the Raman scattering approach the frequency of the localized surface plasmon resonance. The optimized array was then used as the bottom layer of a silver nanoparticle-protein-bowl-shaped silver cavity array sandwich. The second layer of silver was introduced by the interactions between the proteins in the middle layer of the sandwich architecture and silver nanoparticles. Human IgG bound to the surface of this microcavity array can retain its recognition function. With the Raman reporter molecules labeled on the antibody, a detection limit down to 0.1 ng mL(-1) for human IgG is easily achieved. Furthermore, the SERS spectra of label-free proteins (catalase, cytochrome C, avidin and lysozyme) from the assembled sandwich have excellent reproducibility and high quality. The results reveal that the proposed approach has potential for use in qualitative and quantitative detection of biomolecules.

  14. Improvement of corrosion resistance of transparent conductive multilayer coating consisting of silver layers and transparent metal oxide layers

    SciTech Connect

    Koike, Katsuhiko; Yamazaki, Fumiharu; Okamura, Tomoyuki; Fukuda, Shin

    2007-05-15

    An optical filter for plasma display panel (PDP) requires an electromagnetic shield with very high ability. The authors investigated a transparent conductive multilayer coating consisting of silver (Ag) layers and transparent metal oxide layers. The durability of the multilayer sputter coating, including the silver layer, is very sensitive to the surrounding atmosphere. For example, after an exposure test they found discolored points on the multilayer sputter coatings, possibly caused by migration of silver atoms in the silver layers. In their investigation, they modified the top surface of the multilayer sputter coatings with transition metals to improve the corrosion resistance of the multilayer coating. Specifically, they deposited transition metals 0.5-2 nm thick on the top surface of the multilayer coatings by sputtering. They chose indium tin oxide (ITO) as the transparent metal oxide. They applied the multilayer sputter coatings of seven layers to a polyethylene terephthalate (PET) film substrate. A cross-sectional structure of the film with the multilayer coatings is PET film/ITO/Ag/ITO/Ag/ITO/Ag/ITO. They evaluated the corrosion resistance of the films by a salt-water immersion test. In the test, they immersed the film with multilayer coatings into salt water, and then evaluated the appearance, transmittance, and electrical resistance of the multilayer coatings. They investigated several transition metals as the modifying material, and found that titanium and tantalum drastically improved the resistance of the multilayer coatings to the salt-water exposure without a significant decline in transmittance. They also investigated the relation between elapsed time after deposition of the modifying materials and resistance to the salt water. Furthermore, they investigated the effects of a heat treatment and an oxide plasma treatment on resistance to the salt water.

  15. Performance improvement in flexible polymer solar cells based on modified silver nanowire electrode

    NASA Astrophysics Data System (ADS)

    Wang, Danbei; Zhou, Weixin; Liu, Huan; Ma, Yanwen; Zhang, Hongmei

    2016-08-01

    In this work, an efficient flexible polymer solar cell was achieved by controlling the UV-ozone treatment time of silver nanowires (Ag NWs) used in the electrode and combined with other modification materials. Through optimizing the time of UV-ozone treatment, it is shown that Ag NWs electrode treated by UV-ozone for 10 s improves the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene)(P3HT): [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) from 0.76% to 1.34%. After treatment by UV-ozone, Ag NWs electrodes exhibit several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. As a consequence, the performance of devices utilizing 10 s UV-ozone-treated Ag NWs with PEDOT:PSS or MoO3 as composite anode showed higher PCEs of 2.77% (2.73%) compared with that for Ag NW electrodes without UV-ozone treatment. In addition, a PCE of 5.97% in flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PBDTTT-EFT):[6, 6]-phenyl C71-butyric acid methyl ester (PC71BM) as a photoactive layer was obtained.

  16. Performance improvement in flexible polymer solar cells based on modified silver nanowire electrode.

    PubMed

    Wang, Danbei; Zhou, Weixin; Liu, Huan; Ma, Yanwen; Zhang, Hongmei

    2016-08-19

    In this work, an efficient flexible polymer solar cell was achieved by controlling the UV-ozone treatment time of silver nanowires (Ag NWs) used in the electrode and combined with other modification materials. Through optimizing the time of UV-ozone treatment, it is shown that Ag NWs electrode treated by UV-ozone for 10 s improves the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene)(P3HT): [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) from 0.76% to 1.34%. After treatment by UV-ozone, Ag NWs electrodes exhibit several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. As a consequence, the performance of devices utilizing 10 s UV-ozone-treated Ag NWs with PSS or MoO3 as composite anode showed higher PCEs of 2.77% (2.73%) compared with that for Ag NW electrodes without UV-ozone treatment. In addition, a PCE of 5.97% in flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PBDTTT-EFT):[6, 6]-phenyl C71-butyric acid methyl ester (PC71BM) as a photoactive layer was obtained.

  17. Silver Chlorobromide Nanocubes with Significantly Improved Uniformity: Synthesis and Assembly into Photonic Crystals

    SciTech Connect

    Li, Zheng; Okasinski, John S.; Gosztola, David J.; Ren, Yang; Sun, Yugang

    2015-01-01

    Silver chlorobromide (AgClxBr1-x, 0 < x < 1) nanocubes with a highly uniform size, morphology, and crystallinity have been successfully synthesized through a co-precipitation of Ag+ ions with both Cl- and Br- ions in ethylene glycol containing polyvinyl pyrrolidone at mild temperatures. Compositions of the synthesized nanocubes can be easily tuned by controlling the molar ratio of Cl- to Br- ions in the reaction solutions. The size of the nanocubes is determined by varying a number of parameters including the molar ratio of Cl- to Br- ions, injection rate of Ag+ ions, and reaction temperature. The real-time formation of colloidal AgClxBr1-x nanocubes has been monitored, for the first time, by in situ highenergy synchrotron X-ray diffraction. The time-resolved results reveal that a fast injection rate of Ag+ ions is critical for the formation of AgClxBr1-x nanocubes with a highly pure face-centered cubic crystalline phase. The improved uniformity of the AgClxBr1-x nanocubes is beneficial for assembling them into order superlattices (e.g., photonic crystals) even by simply applying centrifugation forces. The stop band of the resulting photonic crystals can be easily tuned from the ultraviolet to the infrared region by using AgClxBr1-x nanocubes with different sizes. The variation of the dielectric constant of AgClxBr1-x associated with the change of the relative concentration of halide ions provides an additional knob to tune the optical properties of photonic crystals.

  18. Effects of piezoelectricity on cadmium sulphide-copper sulphide solar cells

    SciTech Connect

    Bennett, M.S.

    1981-01-01

    Theoretical calculations of the effects of applied uniform and non-uniform stresses on copper sulphide-cadmium sulphide solar cells predict that uniform stress will not affect their performance, while non-uniform stress will. Changes in open-circuit voltage and capacitance resulting from piezoelectric effects are predicted to be proportional to the divergence of the piezoelectric polarization. Experiments performed on single crystal cells verified these calculations for uniform stresses, and for a particular non-uniform stress (uniaxial bending). The changes in the latter case were less than 1%. These experiments were extended to determine the growth face of crystallites in polycrystalline cells.

  19. Silver spoons in the rough: can environmental enrichment improve survival of hatchery Atlantic salmon Salmo salar in the wild?

    PubMed

    Roberts, L J; Taylor, J; Gough, P J; Forman, D W; Garcia de Leaniz, C

    2014-12-01

    This study tested the 'silver spoon' hypothesis which posits that individuals that develop under favourable conditions should enjoy a fitness advantage later in life because they are more likely to recognize and settle in high-quality habitats. Atlantic salmon Salmo salar of two age classes (0+ and 1+ years) were reared in environmentally enriched or standard hatchery tanks for a short period (c. 10 weeks), were then released into a natural river and sampled on repeated occasions to test for silver-spoon effects. Compared with controls, enriched fish had a 6.4% higher recapture rate and settled in higher velocity habitats when they were stocked as 0+ year fry, but not when they were stocked as 1+ year parr. The opportunity for selection was generally higher for environmentally enriched fish than for controls, and also higher for 0+ than for 1+ year fish. Selection favoured individuals with high condition factor, extensive fat reserves and longer than average pectoral fins in both age classes but favoured a small body size in 1+ year and a large body size in 0+ year releases. Stomach analysis showed that enriched fish ate more, and adapted quicker to natural prey than controls. These results provide support for silver-spoon effects in fish and indicate that enrichment can improve post-release performance in conservation programmes, but seemingly only if fish are not kept in captivity for too long. © 2014 The Fisheries Society of the British Isles.

  20. Detoxification of sulphidic African shelf waters by blooming chemolithotrophs

    NASA Astrophysics Data System (ADS)

    Lavik, Gaute; Stührmann, Torben; Brüchert, Volker; van der Plas, Anja; Mohrholz, Volker; Lam, Phyllis; Mußmann, Marc; Fuchs, Bernhard M.; Amann, Rudolf; Lass, Ulrich; Kuypers, Marcel M. M.

    2009-01-01

    Coastal waters support ~90 per cent of global fisheries and are therefore an important food reserve for our planet. Eutrophication of these waters, due to human activity, leads to severe oxygen depletion and the episodic occurrence of hydrogen sulphide-toxic to multi-cellular life-with disastrous consequences for coastal ecosytems. Here we show that an area of ~7,000km2 of African shelf, covered by sulphidic water, was detoxified by blooming bacteria that oxidized the biologically harmful sulphide to environmentally harmless colloidal sulphur and sulphate. Combined chemical analyses, stoichiometric modelling, isotopic incubations, comparative 16S ribosomal RNA, functional gene sequence analyses and fluorescence in situ hybridization indicate that the detoxification proceeded by chemolithotrophic oxidation of sulphide with nitrate and was mainly catalysed by two discrete populations of γ- and ɛ-proteobacteria. Chemolithotrophic bacteria, accounting for ~20 per cent of the bacterioplankton in sulphidic waters, created a buffer zone between the toxic sulphidic subsurface waters and the oxic surface waters, where fish and other nekton live. This is the first time that large-scale detoxification of sulphidic waters by chemolithotrophs has been observed in an open-ocean system. The data suggest that sulphide can be completely consumed by bacteria in the subsurface waters and, thus, can be overlooked by remote sensing or monitoring of shallow coastal waters. Consequently, sulphidic bottom waters on continental shelves may be more common than previously believed, and could therefore have an important but as yet neglected effect on benthic communities.

  1. Growth of copper indium sulphide films by thermal evaporation of mixtures of copper sulphide and indium sulphide powders

    SciTech Connect

    Rao, Pritty; Kumar, Sanjiv Sahoo, N.K.

    2013-08-01

    Graphical abstract: - Highlights: • CuInS{sub 2} films are prepared by resistively heating mixtures of CuS and In{sub 2}S{sub 3}. • As deposited films consist of Cu{sub 7}S{sub 4}, InS and In{sub 2}S{sub 3}. • These species react during vacuum annealing to produce CuInS{sub 2} films. • The films bear stoichiometric or Cu-rich composition. • Their electrical and optical features are conducive for photovoltaic applications. - Abstract: The physical evaporation of a 1:1 mixture of copper sulphide (CuS) and indium sulphide (In{sub 2}S{sub 3}) powders by resistive heating followed by the vacuum annealing of the resulting films at 723 K produces copper indium sulphide (CuInS{sub 2}) films with about 95% phase purity. Composed of sub-micron sized grains, the films bear stoichiometric or Cu-rich composition and are endowed with p-type conductivity, a band gap of about 1.5 eV and an absorption coefficient of about 4 × 10{sup 4} cm{sup −1} in visible region. Mechanistically, the formation of CuInS{sub 2} films takes place as a result of solid state reaction among Cu{sub 7}S{sub 4}, InS and In{sub 2}S{sub 3} in the condensed phase. These intermediate species are produced from the decomposition of CuInS{sub 2} formed in the evaporating mixture due to the reaction between CuS and In{sub 2}S{sub 3}, and excess CuS. Process simplicity and the absence of a sulphurisation step make this approach attractive for synthesising CuInS{sub 2} absorber layers for photovoltaic applications.

  2. Efficient intracellular delivery and improved biocompatibility of colloidal silver nanoparticles towards intracellular SERS immuno-sensing.

    PubMed

    Bhardwaj, Vinay; Srinivasan, Supriya; McGoron, Anthony J

    2015-06-21

    High throughput intracellular delivery strategies, electroporation, passive and TATHA2 facilitated diffusion of colloidal silver nanoparticles (AgNPs) are investigated for cellular toxicity and uptake using state-of-art analytical techniques. The TATHA2 facilitated approach efficiently delivered high payload with no toxicity, pre-requisites for intracellular applications of plasmonic metal nanoparticles (PMNPs) in sensing and therapeutics.

  3. Silver in health care: antimicrobial effects and safety in use.

    PubMed

    Lansdown, Alan B G

    2006-01-01

    Silver has a long and intriguing history as an antibiotic in human health care. It has been developed for use in water purification, wound care, bone prostheses, reconstructive orthopaedic surgery, cardiac devices, catheters and surgical appliances. Advancing biotechnology has enabled incorporation of ionizable silver into fabrics for clinical use to reduce the risk of nosocomial infections and for personal hygiene. The antimicrobial action of silver or silver compounds is proportional to the bioactive silver ion (Ag(+)) released and its availability to interact with bacterial or fungal cell membranes. Silver metal and inorganic silver compounds ionize in the presence of water, body fluids or tissue exudates. The silver ion is biologically active and readily interacts with proteins, amino acid residues, free anions and receptors on mammalian and eukaryotic cell membranes. Bacterial (and probably fungal) sensitivity to silver is genetically determined and relates to the levels of intracellular silver uptake and its ability to interact and irreversibly denature key enzyme systems. Silver exhibits low toxicity in the human body, and minimal risk is expected due to clinical exposure by inhalation, ingestion, dermal application or through the urological or haematogenous route. Chronic ingestion or inhalation of silver preparations (especially colloidal silver) can lead to deposition of silver metal/silver sulphide particles in the skin (argyria), eye (argyrosis) and other organs. These are not life-threatening conditions but cosmetically undesirable. Silver is absorbed into the human body and enters the systemic circulation as a protein complex to be eliminated by the liver and kidneys. Silver metabolism is modulated by induction and binding to metallothioneins. This complex mitigates the cellular toxicity of silver and contributes to tissue repair. Silver allergy is a known contra-indication for using silver in medical devices or antibiotic textiles.

  4. Hydrogen sulphide and methane emissions on the central Namibian shelf

    NASA Astrophysics Data System (ADS)

    Brüchert, Volker; Currie, Bronwen; Peard, Kathleen R.

    2009-12-01

    Hydrogen sulphide occurs frequently in the waters of the inner shelf coastal upwelling area off central Namibia. The area affected coincides with hatching grounds of commercially important pelagic fish, whose recruitment may be severely affected by recurring toxic sulphidic episodes. Both episodic biogenic methane gas-driven advective and molecular diffusive flux of hydrogen sulphide have been implicated as transport mechanisms from the underlying organic-matter-rich diatomaceous mud. To test hypotheses on the controls of hydrogen sulphide transport from the sediments on the inner Namibian shelf, water column and sediment data were acquired from four stations between 27 and 72 m water depth over a 3 year long period. On 14 cruises, temperature, salinity, dissolved oxygen, nitrate, methane, and total dissolved sulphide were determined from water column samples, and pore water dissolved methane, total dissolved sulphide, biomass of benthic sulphide-oxidising bacteria Beggiatoa and Thiomargarita, and bacterial sulphate reduction rates were determined from sediment cores. Superimposed on a trend of synchronous changes in water column oxygen and nutrient concentrations controlled by regional hydrographic conditions were asynchronous small-scale variations at the in-shore stations that attest to localized controls on water column chemistry. Small temporal variations in sulphate reduction rates determined with 35S-labeled sulphate do not support the interpretation that variable emissions of sulphide and methane from sediments are driven by temporal changes in the degradation rates of freshly deposited organic matter. The large temporal changes in the concentrations of hydrogen sulphide and the co-occurrence of pore water sulphate and methane support an interpretation of episodic advection of methane and hydrogen sulphide from deeper sediment depths - possibly due to gas bubble transport. Effective fluxes of hydrogen sulphide and methane to the water column, and methane

  5. Improved identification of conjugated linoleic acid isomers using silver-ion HPLC separations.

    PubMed

    Delmonte, Pierluigi; Yurawecz, Martin P; Mossoba, Magdi M; Cruz-Hernandez, Cristina; Kramer, John K G

    2004-01-01

    Silver-ion high-performance liquid chromatography (Ag+-HPLC) has been shown to be effective in the resolution of most of the isomers of conjugated octadecadienoic acids (18:2), also known as conjugated linoleic acid (CLA). The CLA isomers identified in natural fats from ruminants are a mixture of numerous positional and geometric isomers from 7,9- to 12,14-18:2. Ag+-HPLC separates both geometric (trans,trans < cis/trans < cis,cis) and positional CLA isomers using the mobile phase hexane/acetonitrile (99.9:0.1). The elution volumes for the CLA isomers were not only affected by the concentration of acetonitrile (in the prepared mobile phase) but also with successive runs during the day using a prepared mobile phase batch, due to the partial solubility of acetonitrile in hexane. However, this drift does not affect the relative resolution of the CLA isomers. The addition of diethyl ether to the mobile phase partly stabilizes the solvent mixture. In order to facilitate the interpretation of Ag-+HPLC chromatograms, the relative retention volumes (RRV) were calculated for each CLA isomer. Toluene was added to all the test portions and served as an estimator of dead volume, whereas the elution of the ubiquitous 9c,11t-CLA isomer was chosen as unity (1.00). Expressing the elution of all the CLA isomers as their RRV greatly helped to standardize each CLA isomer, resulting in relatively small coefficients of variation (% CV) for the trans,trans (<1.5%) and cis/trans (<0.5%) CLA isomers. The identification of the CLA isomers was further facilitated by synthesis of authentic CLA isomers. All the geometric CLA fatty acid methyl esters (FAME) from positions 6,8- to 13,15-CLA were commercially available or synthesized by a combination of partial hydrazine reduction of known polyunsaturated fatty acids followed by alkali isomerization, isolation of products, and further iodine-catalyzed geometric isomerization. Based on expressing the elution volume as RRV and the availability of

  6. FTIR-PAS investigation on polyphenylene sulphide

    NASA Astrophysics Data System (ADS)

    Zhang, Guizhong; Wang, Qingyue; Yu, Xiaoyan; Su, Dazhao; Li, Zengfa; Zhang, Guangyin

    The paper presents the mid-infrared spectrum of polyphenylene sulphide (PPS) measured by photoacoustic spectroscopy, and the analysis of the spectrum by group theory by treating the chemical unit, C 6H 4S 2, as the characteristic vibrational unit for PPS chains. The correlation between the infrared spectra of PPS and benzene was performed as a further aid to the spectral assignments. A comparison between PPS spectrum with the spectra of p- and para-substituted benzene compounds is made. This work is the basis on which further studies on PPS composites may proceed.

  7. Studies on polycrystalline cadmium sulphide photoanodes

    NASA Astrophysics Data System (ADS)

    Ramprakash, Y.; Subramanian, V.; Krishnakumar, R.; Lakshmanan, A. S.; Venkatesan, V. K.

    The spectral dependence of absolute quantum efficiency for chemically deposited cadmium sulphide thin-film electrodes in 1 M NaOH: 0.1 M Na 2S:0.1 M S, is reported. A peak quantum efficiency of 1.75 × 10 -2 is observed at λ = 560 nm. The diffusion length of minority carriers has been calculated from Gartner's photocurrent equation. The light intensity dependence of the short-circuit current ( Jsc) was linear, whereas the open-circuit voltage ( Voc) showed a [log IL] 2 variation. Reasons for observed low values of Voc and Jsc are discussed.

  8. Improvement of Electrochemical Properties of Lithium–Oxygen Batteries Using a Silver Electrode

    SciTech Connect

    Park, Jin-Bum; Luo, Xiangyi; Lu, Jun; Shin, Chang Dae; Yoon, Chong Seung; Amine, Khalil; Sun, Yang-Kook

    2015-07-09

    Silver (Ag) electrodes are prepared by an electrodeposition method at -0.25 V versus SCE. To evaluate the effect of particle size on Li–air cells, deposition times are 3, 10, 30, and 300 s. When cycled at a current density of 0.032 mA cm–2, the Ag-deposited electrode for 300 s shows very low polarization corresponding to the oxygen evolution reaction potential at 3.6 V. X-ray diffraction studies confirm that the main discharge product is Li2O2, and the results of scanning electron microscopy and transmission electron microscopy of the discharged electrodes show lithium peroxides at different positions due to the limitation of active sites on silver particles.

  9. Inclusion of silver nanoparticles for improving regenerated cellulose membrane performance and reduction of biofouling.

    PubMed

    Benavente, J; García, M E; Urbano, N; López-Romero, J M; Contreras-Cáceres, R C; Casado-Rodríguez, M A; Moscoso, A; Hierrezuelo, J

    2017-10-01

    The preparation of silver nanoparticles (AgNPs) and their incorporation into the structure of a regenerated cellulose membrane by dip coating is presented. Morphological characterization of the AgNPs (average diameter of 20±2nm) was carried out by SEM/TEM, while elastic, electrical and antimicrobial properties of the hybrid membrane were also analyzed. The presence of silver nanoparticles in the membrane seems to increases its rigidity and its chemical stability against oxidation, but it only induces small changes in the transport parameters. As expected, AgNPs provide antimicrobial properties to the membrane and consequently the reduction of biofouling without affecting significantly other characteristic parameters, opening the application of the modified membrane to wastewaters treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Relationship between microstructures and grain-scale trace element distribution in komatiite-hosted magmatic sulphide ores

    NASA Astrophysics Data System (ADS)

    Vukmanovic, Zoja; Reddy, Steven M.; Godel, Bélinda; Barnes, Stephen J.; Fiorentini, Marco L.; Barnes, Sarah-Jane; Kilburn, Matthew R.

    2014-01-01

    Komatiite-hosted nickel sulphides from the Yilgarn Craton (Australia) consist of two main sulphide phases: pyrrhotite (Fe7S8) and pentlandite ((Fe,Ni)9S8); two minor sulphide phases: chalcopyrite (CuFeS2) and pyrite (FeS2) and trace arsenides. Samples of massive sulphides from three deposits with diverse deformation and metamorphic histories (the Silver Swan, Perseverance and Flying Fox deposits) have been studied by electron backscatter diffraction and laser ablation inductively coupled plasma mass spectrometry and nano-scale secondary ion mass spectrometry. These ore bodies were selected to investigate the relationship between microstructures and mineral trace element chemistry in three dominant sulphide species in each deposit. In all three samples, pyrrhotite preserves a strong evidence of crystal plasticity relative to both pentlandite and pyrite. The trace element composition of pyrrhotite shows significant variation in specific elements (Pb, Bi and Ag). This variation correlates spatially with intragrain pyrrhotite microstructures, such as low angle and twin boundaries. Minor signatures of crystal plasticity in pyrite and pentlandite occur in the form of rare low angle boundaries (pentlandite) and mild lattice misorientation (pyrite). Trace element compositions of pentlandite and pyrite show no correlation with microstructures. Variations in pyrrhotite are interpreted as a result of intragrain diffusion during the syn- and post-deformation history of the deposit. Intragrain diffusion can occur either due to bulk diffusion, dislocation-impurity pair diffusion, or by "pipe diffusion", i.e. along fast diffusion pathways at high and low angle, and twin boundaries. This contribution examines three different diffusion models and suggests that dislocation-impurity pair diffusion and pipe diffusion are the most likely processes behind increased trace element concentration along the microstructures in pyrrhotite. The same phenomenon is observed in samples from three

  11. Improved silver mirror coating for ground and space-based astronomy

    NASA Astrophysics Data System (ADS)

    Sheikh, David A.

    2016-07-01

    A durable, UV-enhanced, silver mirror coating has been developed by ZeCoat Corporation. The coating is highly reflective from 350-nm through the long IR, and durable in warm-humid environments on earth, as well as, high radiation environments in space. This paper presents polarized-angular reflectance data, as well as, average reflectance data before and after simulated space radiation exposure.

  12. Improved antibacterial activity of nanofiltration polysulfone membranes modified with silver nanoparticles.

    PubMed

    Andrade, Patricia Fernanda; de Faria, Andreia Fonseca; Oliveira, Silvana Ruella; Arruda, Marco Aurélio Zezzi; Gonçalves, Maria do Carmo

    2015-09-15

    Polysulfone membranes (PSf) containing silver nanoparticles were prepared by the wet phase-inversion process. Silver nanoparticles (AgNP) were dispersed into the polymer matrix using two different methodologies. In the first one, the AgNP were synthesized and further dispersed into the polymer solution (ex situ process). In the second method, the formation of the AgNP was performed in situ. The AgNP crystalline structure in the PSf membranes was confirmed by X-ray diffraction. Field emission scanning electron microscopy images showed that the addition of AgNP in PSf membranes caused no significant changes to the finger-like morphology. When the ex situ methodology was applied, 45 nm average size AgNP were uniformly distributed in the internal pores of the membranes. However, when the AgNP were formed through the in situ process, the AgNP were uniformly and preferentially distributed on the top and bottom surfaces of the membrane. In the last case, the AgNP showed cubic morphology when present in the bottom and top surfaces, however, when inside the membrane their morphology was spherical. The cubic-like nanoparticles displayed a 38 nm average edge length. The silver ion released from the membrane during water filtration was measured using inductively coupled plasma mass spectrometry, which showed a silver leaching of approximately 2 μg L(-1). The nanocomposite membranes prepared by the in situ method exhibited a better antibacterial activity, in comparison to those prepared by ex situ, and also a decrease in 90% Escherichia coli adhered cells compared to the pristine PSf membranes. In conclusion, the in situ procedure can be considered a feasible, simple, and reproducible methodology to prepare anti-biofouling polysulfone membranes containing AgNP.

  13. Oxidation of sulphide in abandoned mine tailings by ferrate.

    PubMed

    Lee, Yong-Hoon; Yu, Mok-Ryun; Chang, Yoon-Young; Kang, Seon-Hong; Yang, Jae-Kyu

    2015-01-01

    In this study, Fe(VI) was applied to treat three mine tailings containing different amounts of sulphides and heavy metals. Oxidation of sulphides by Fe(VI) was studied at pH 9.2 with variation of solid to solution ratio, Fe(VI) concentration and injection number of Fe(VI) solution. The major dissolved products from the treatment of mine tailings with Fe(VI) solution were sulphate and arsenic. Oxidation efficiency of sulphides was evaluated by reduction efficiency of Fe(VI) as well as by measurement of dissolved sulphate concentration. Even though inorganic composition of three mine tailings was different, reduction fraction of Fe(VI) was quite similar. This result can suggest that Fe(VI) was involved in several other reactions in addition to oxidation of sulphides. Oxidation of sulphides in mine tailing was greatly dependent on the total amount of sulphides as well as kinds of sulphides complexed with metals. Over the five consecutive injections of Fe(VI) solution, dissolved sulphate concentration was greatly decreased by each injection and no more dissolved sulphate was observed at the fifth injection. While dissolved arsenic was decreased lineally up to the fifth injection. Sulphate generation was slightly increased for all mine tailings as Fe(VI) concentration was increased; however, enhancement of oxidation efficiency of sulphides was not directly proportional to the initial Fe(VI) concentration.

  14. Hydrogen sulphide removal by activated sludge diffusion.

    PubMed

    Barbosa, V L; Dufol, D; Callan, J L; Sneath, R; Stuetz, R M

    2004-01-01

    Odours from wastewater treatment plants comprise a mixture of various gases, of which hydrogen sulphide (H2S) is the main constituent. Microorganisms commonly found in wastewater can degrade sulphurous compounds. Therefore, the use of activated sludge (AS) for odour control offers an alternative to traditional waste gas treatment processes, such as biofilters, bioscrubbers and biotrickling filters, both in practical terms (use of existing facilities) and economically (minimal capital cost). The performance of AS diffusion as a bioscrubber for removing H2S at concentrations at 25, 75 and 150 ppmv was evaluated. Pilot-scale trials were undertaken using parallel 60-L aeration tanks and 20-L clarifier reactors at the Bedford Sewage Treatment Works, Carington, UK. Olfactometry measurements were also carried out to determine whether there was any increase in odour concentration owing to H2S diffusion. Hydrogen sulphide removal rates of 100% were obtained, with no noticeable increase in odour concentration throughout the trials as measured by olfactometry. Odour concentration was highest at the beginning of the trials and lowest during the high H2S dosing period, with similar values being obtained for test and control. It was concluded that AS diffusion is an effective bioscrubber for the removal of H2S odour.

  15. Silver Sulfadiazine

    MedlinePlus

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  16. Prediction of sulphide build-up in filled sewer pipes.

    PubMed

    Alani, Amir M; Faramarzi, Asaad; Mahmoodian, Mojtaba; Tee, Kong Fah

    2014-08-01

    Millions of dollars are being spent worldwide on the repair and maintenance of sewer networks and wastewater treatment plants. The production and emission of hydrogen sulphide has been identified as a major cause of corrosion and odour problems in sewer networks. Accurate prediction of sulphide build-up in a sewer system helps engineers and asset managers to appropriately formulate strategies for optimal sewer management and reliability analysis. This paper presents a novel methodology to model and predict the sulphide build-up for steady state condition in filled sewer pipes. The proposed model is developed using a novel data-driven technique called evolutionary polynomial regression (EPR) and it involves the most effective parameters in the sulphide build-up problem. EPR is a hybrid technique, combining genetic algorithm and least square. It is shown that the proposed model can provide a better prediction for the sulphide build-up as compared with conventional models.

  17. Internal structures and dating of non-sulphide Zn deposits using rock magnetism: insights from the Moroccan High Atlas

    NASA Astrophysics Data System (ADS)

    Charles, Nicolas; Choulet, Flavien; Sizaret, Stanislas; Chen, Yan; Barbanson, Luc; Ennaciri, Aomar; Badra, Lakhlifi; Branquet, Yannick

    2016-01-01

    The renewal of interest in Zn-Pb non-sulphide ores has been induced by mineral processing improvement and leads to new exploration and mining projects in the world. Although the mineralogy is often precisely known, and despite several studies linking ore deposition to regional tectonics, absolute dating of non-sulphide stages is rare and structure of ore bodies was largely disregarded. Geochronological data from non-sulphide ores are essential to timely constrain alteration episodes and to insert supergene ore genesis in the climate and tectonic evolution of the metallogenic province. The access to internal organization of ore could reveal post-mineralization episodes related to supergene evolution. Thus, a rock magnetism study combining anisotropy of magnetic susceptibility (AMS) and palaeomagnetism was performed on four non-sulphide deposits from the Moroccan High Atlas. AMS generally shows similar horizontal magnetic fabrics for ores and the clayey and carbonaceous internal sediments filling karstic cavities. The palaeomagnetic directions of ores and internal sediments are compatible, and the calculated poles are consistent with the last 30 Ma of the Africa apparent polar wander path, with an upper age at 0.78 Ma. The proposed three-step scenario is placed within the evolution of the Moroccan High Atlas belt. Deposition of primary sulphides is contemporaneous with opening of the Tethyan and Atlantic oceans. During the Tertiary, intracontinental deformation gave rise to the High Atlas fold-and-thrust belt and to regional uplift. Finally, Zn-Pb sulphides hosted in carbonates experienced oxidation under an arid climate to form karst-related Zn-Pb non-sulphide ores. These promising results pave the way for an efficient method to constrain the internal fabrics and age of Zn supergene deposits.

  18. Improving performance and cyclability of zinc-silver oxide batteries by using graphene as a two dimensional conductive additive.

    PubMed

    Ozgit, Dilek; Hiralal, Pritesh; Amaratunga, Gehan A J

    2014-12-10

    In this article, the use of reduced graphene oxide (rGO) as a high-surface-area conductive additive for enhancing zinc-silver oxide (Zn-Ag2O) batteries is reported for the first time. Specific capacity, rate capability and cyclability are all improved with the addition of 5% thermally reduced graphene oxide to the electrode. It is shown that the rGO morphology becomes more beneficial as the active materials tend toward the nanoscale. The combination results in a better utilization of the active material, which in turn improves the specific capacity of the zinc-silver oxide batteries by ca. 50%, as a result of the more intimate contact with the nano (∼50 nm) electrode particles. The resulting rGO network also creates a high-surface-area conducting template for ZnO electrodeposition upon discharge, significantly reducing the overall particle size of the ZnO deposit, thus inhibiting the formation of dendrites, and increasing the number of achievable cycles from 4 to >160 with a basic cellulose separator. The morphology of the electrodes and its electrochemical parameters are studied as a function of cycling.

  19. Electrochemical behavior of silver sulfide

    SciTech Connect

    Drouven, B.U.E.

    1982-01-01

    The electrochemical behavior of silver sulfide in sulfuric acid as well as in nitric acid was studied using electrodes made from synthetic silver sulfide. The primary techniques used were potentiostatic, potentiodynamic, galvanostatic and corrosion cell experiments. The cathodic reaction of silver sulfide produces silver and hydrogen sulfide. This reaction mechanism is a sequential two step charge transfer involving a single electron in each step. Silver ions are produced from silver sulfide upon applying an anodic potential. The dissolution rate of silver sulfide can be so high that the formation of silver sulfate occurs which partially covers the silver sulfide surface and inhibits a further rate increase. The sulfur from the silver sulfide will be oxidized at low overpotentials to elemental sulfur; at high overpotentials, the oxidation to sulfate or bisulfate is observed. The results suggest that the catalysis of chalcopyrite by the addition of silver ions is caused by the formation and subsequent dissolution of silver sulfide leaving a porous layer behind. The understanding of the reaction mechanism of silver sulfide dissolution and its optimization will significantly improve the economic evaluation of industrial processes using the catalyzed leaching of chalcopyrite. The present knowledge of the catalysis indicates that other ions may be substituted for silver ions which would increase the feasibility of hydrometallurgical processes.

  20. Dietary copper supplementation improves pelt characteristics of female silver fox (Vulpes fulva) during the winter fur-growing season.

    PubMed

    Zhong, Wei; Liu, Hanlu; Luo, Guoliang; Chang, Zhongjuan; Liu, Fenghua; Zhao, Jingbo; Li, Danli; Yue, Zhigang; Zhang, Haihua; Li, Guangyu

    2014-07-01

    Copper has an essential role in normal fur pigmentation and fur quality. This study evaluated the effects of cupric citrate (CuCit) supplementation on growth, nutrients metabolism and pelt characteristics of the female silver fox (Vulpes fulva). Fifty age-matched female silver foxes with similar body weights were randomly divided into five dietary groups for 58 days during the winter fur-growing season. The basal diet contained 4.92 mg/kg copper. Groups I-V were supplemented with 6, 30, 60, 90 or 150 mg Cu from CuCit per 1 kg dry matter basal diet. Serum alkaline phosphatase activity was significantly higher (P<0.05) in those fed 90 mg/kg Cu than those fed 150 mg/kg Cu. Pelt total thickness was significantly higher (P<0.05) in those fed 30 mg/kg Cu than foxes fed 6 mg/kg Cu supplemented diet, but were similar to the other groups. Length of guard hair was significantly lower (P<0.05) in those fed 90 mg/kg Cu than fed 6 mg/kg Cu and 30 mg/kg Cu, but were similar to the other groups. Length of underhair was significantly higher (P<0.05) in those fed 6 mg/kg Cu than those fed 90 mg/kg Cu, but was similar to the other groups. Considering decreasing environmental contamination and improving pelt performance, supplementing 30 mg/kg Cu from CuCit (actual copper 35 mg/kg dry matter) is appropriate for female silver fox.

  1. Improved electroless plating method through ultrasonic spray atomization for depositing silver nanoparticles on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Qi; Xie, Ming; Liu, Yichun; Yi, Jianhong

    2017-07-01

    A novel method was developed to deposit nanosized silver particles on multi-walled carbon nanotubes (MWCNTs). The electroless plating of silver on MWCNTs accomplished in small solution drops generated by ultrasonic spray atomization, which inhibited excessive growth of silver particles and led to much more uniform nanometer grain-sized coatings. The results showed that pretreatment was essential for silver particles to deposit on the MWCNTs, and the electrolyte concentration and reaction temperature were important parameters which had a great influence on the morphology and structure of the silver coatings. Possible mechanisms of this method are also discussed in the paper.

  2. Performance improvement in polymeric thin film transistors using chemically modified both silver bottom contacts and dielectric surfaces

    NASA Astrophysics Data System (ADS)

    Xie, Ying-Tao; Ouyang, Shi-Hong; Wang, Dong-Ping; Zhu, Da-Long; Xu, Xin; Tan, Te; Fong, Hon-Hang

    2015-09-01

    An efficient interface modification is introduced to improve the performance of polymeric thin film transistors. This efficient interface modification is first achieved by 4-fluorothiophenol (4-FTP) self-assembled monolayers (SAM) to chemically treat the silver source-drain (S/D) contacts while the silicon oxide (SiO2) dielectric interface is further primed by either hexamethyldisilazane (HMDS) or octyltrichlorosilane (OTS-C8). Results show that contact resistance is the dominant factor that limits the field effect mobility of the PTDPPTFT4 transistors. With proper surface modification applied to both the dielectric surface and the bottom contacts, the field effect mobilities of the bottom-gate bottom-contact PTDPPTFT4 transistors were significantly improved from 0.15 cm2·V-1·s-1 to 0.91 cm2·V-1·s-1. Project supported by the National Basic Research Program of China (Grant No. 2013CB328803).

  3. Biogeochemical controls on microbial diversity in seafloor sulphidic sediments.

    PubMed

    Müller, M; Handley, K M; Lloyd, J; Pancost, R D; Mills, R A

    2010-09-01

    The ultimate fate of hydrothermal sulphides on the seafloor depends on the nature and rate of abiotic and microbially catalysed reactions where sulphide minerals are exposed to oxic seawater. This study combines organic and inorganic geochemical with microbiological measurements across a suboxic transition zone of highly altered sulphidic sediments from the Trans-Atlantic Geotransverse hydrothermal field to characterize the reaction products and microbial communities present. There is distinct biogeochemical zonation apparent within the sediment sequence from oxic surface layers through a suboxic transition zone into the sulphide material. The microbial communities in the sediment differ significantly between the biogeochemical horizons sampled, with the identified microbes inferred to be associated with Fe and S redox cycling. In particular, Marinobacter species, organisms associated with circumneutral Fe oxidation, are dominant in a sulphide lens present in the lower core. The dominance of Marinobacter-related sequences within the relict sulphide lens implies that these organisms play an important role in the alteration of sulphides at the seafloor once active venting has ceased.

  4. Cadmium-induced formation of sulphide and cadmium sulphide particles in the aquatic hyphomycete Heliscus lugdunensis.

    PubMed

    Dobritzsch, Dirk; Ganz, Petra; Rother, Michael; Ehrman, James; Baumbach, Renate; Miersch, Jürgen

    2015-01-01

    Freshwater fungi which can survive under metal exposure receive increasing scientific attention. Enhanced synthesis of sulphide and glutathione but no phytochelatin synthesis in response to cadmium (up to 80 μM Cd(2+) in the medium) was measured in the aquatic hyphomycete Heliscus lugdunensis. Up to 25 μmol g(-1) dry mass the fungus formed sulphide in an exponentially Cd(2+)-concentration-dependent manner. Using light microscopy, precipitates were observed outside of the hyphae which could be determined as amorphous particles by X-ray diffraction (XRD). Energy dispersive X-ray spectroscopy (EDS) analysis indicated that these particles were mainly composed of Cd and S with an atomic ratio of 1:1, but some elements of the culture medium such as P and Cl were also present. Fungal cells exposed to Cd(2+) accumulated 12-28 μmol metal g(-1) dry mass over a period of 7-28 days. The results may indicate that sulphide could sequester excess Cd(2+) under oxygen deprived conditions and thereby reduce its toxicity via an additional avoidance mechanism of this fungus. Copyright © 2015 Elsevier GmbH. All rights reserved.

  5. How does solar ultraviolet-B radiation improve drought tolerance of silver birch (Betula pendula Roth.) seedlings?

    PubMed

    Robson, T Matthew; Hartikainen, Saara M; Aphalo, Pedro J

    2015-05-01

    We hypothesized that solar ultraviolet (UV) radiation would protect silver birch seedlings from the detrimental effects of water stress through a coordinated suite of trait responses, including morphological acclimation, improved control of water loss through gas exchange and hydraulic sufficiency. To better understand how this synergetic interaction works, plants were grown in an experiment under nine treatment combinations attenuating ultraviolet-A and ultraviolet-B (UVB) from solar radiation together with differential watering to create water-deficit conditions. In seedlings under water deficit, UV attenuation reduced height growth, leaf production and leaf length compared with seedlings receiving the full spectrum of solar radiation, whereas the growth and morphology of well-watered seedlings was largely unaffected by UV attenuation. There was an interactive effect of the treatment combination on water relations, which was more apparent as a change in the water potential at which leaves wilted or plants died than through differences in gas exchange. This suggests that changes occur in the cell wall elastic modulus or accumulation of osmolites in cells under UVB. Overall, the strong negative effects of water deficit are partially ameliorated by solar UV radiation, whereas well-watered silver birch seedlings are slightly disadvantaged by the solar UV radiation they receive. © 2014 John Wiley & Sons Ltd.

  6. Gold-coated silver dendrites as SERS substrates with an improved lifetime.

    PubMed

    Gutés, Albert; Maboudian, Roya; Carraro, Carlo

    2012-12-21

    Nanostructured silver is known to yield the highest signal-enhancement factors in surface-enhanced Raman spectroscopy, but its low chemical stability toward oxidation presents a challenge in the realization of Ag-based SERS substrates with long operating lifetimes. Here, a study of the long-term stability of silver dendrites as SERS substrates is reported. SERS spectra of 1,2-benzenedithiol monolayers on Ag dendrites, acquired over a period of time in excess of 1 year, shows appreciable degradation with time. However, no degradation is observed in the spectra of monolayers deposited on Ag dendrites that were coated with a monolayer-thin Au film deposited by an immersion plating process. X-ray photoelectron spectra confirm the oxidation of the uncoated Ag dendrites whereas no chemical changes are detected in the Au-coated ones. These results suggest that the galvanic displacement of Au on preformed Ag nanostructures provides a suitable route to producing SERS-active substrates with long operating and/or shelf lifetimes.

  7. Critical currents in sputtered copper molybdenum sulphide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.; Kammerdiner, L.; Luo, H.-L.

    1977-01-01

    Critical currents in a sputtered Chevrel-phase copper molybdenum sulfide have been measured at 4.2 K as a function of applied magnetic field. Self-field critical-current values up to 10 to the 9th A/sq m were found, decreasing to 10 to the 8th A/sq m at 3 T. Graphs of pinning forces versus field were found to be independent of field direction, and the pinning mechanism is sample independent. Critical-current densities for sputtered lead molybdenum sulphide are estimated to be about 10 to the 8th A/sq m at 26 T based on a scaling law for pinning.

  8. Critical currents in sputtered copper molybdenum sulphide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.; Kammerdiner, L.; Luo, H.-L.

    1977-01-01

    Critical currents in a sputtered Chevrel-phase copper molybdenum sulfide have been measured at 4.2 K as a function of applied magnetic field. Self-field critical-current values up to 10 to the 9th A/sq m were found, decreasing to 10 to the 8th A/sq m at 3 T. Graphs of pinning forces versus field were found to be independent of field direction, and the pinning mechanism is sample independent. Critical-current densities for sputtered lead molybdenum sulphide are estimated to be about 10 to the 8th A/sq m at 26 T based on a scaling law for pinning.

  9. The Anti-Fasciolasis Properties of Silver Nanoparticles Produced by Trichoderma harzianum and Their Improvement of the Anti-Fasciolasis Drug Triclabendazole

    PubMed Central

    Gherbawy, Youssuf A.; Shalaby, Ismail M.; Abd El-sadek, Mahmoud Syed; Elhariry, Hesham M.; Banaja, AbdelElah A.

    2013-01-01

    Recently, new strains of Fasciola demonstrated drug resistance, which increased the need for new drugs or improvement of the present drugs. Nanotechnology is expected to open some new opportunities to fight and prevent diseases using an atomic scale tailoring of materials. The ability to uncover the structure and function of biosystems at the nanoscale, stimulates research leading to improvement in biology, biotechnology, medicine and healthcare. The size of nanomaterials is similar to that of most biological molecules and structures; therefore, nanomaterials can be useful for both in vivo and in vitro biomedical research and applications. Therefore, this work aimed to isolate fungal strains from Taif soil samples, which have the ability to synthesize silver nanoparticles. The fungus Trichoderma harzianum, when challenged with silver nitrate solution, accumulated silver nanoparticles (AgNBs) on the surface of its cell wall in 72 h. These nanoparticles, dislodged by ultrasonication, showed an absorption peak at 420 nm in a UV-visible spectrum, corresponding to the plasmon resonance of silver nanoparticles. The transmission electron micrographs of dislodged nanoparticles in aqueous solution showed the production of reasonably monodisperse silver nanoparticles (average particle size: 4.66 nm) by the fungus. The percentage of non hatching eggs treated with the Triclabendazole drug was 69.67%, while this percentage increased to 89.67% in combination with drug and AgNPs. PMID:24196355

  10. Development and field evaluation of a new diffusive sampler for hydrogen sulphide in the ambient air.

    PubMed

    De Santis, F; Allegrini, I; Bellagotti, R; Vichi, F; Zona, D

    2006-02-01

    A diffusive sampler for the determination of hydrogen sulphide (H2S) based on collection on a paper filter coated with silver nitrate followed by optical densitometric determination of the metal sulphide was developed. Laboratory tests were conducted in controlled atmosphere to evaluate linearity, uptake rate, face velocity effects, sample stability, influence of relative humidity and of interferents, precision and accuracy. The measured uptake rate for H2S was determined in experiments involving sampling at different concentration levels in comparison to a wet standard colorimetric technique. The precision of the measurements for co-located passive samplers was lower than 15%. The accuracy of the data collected is within 20% of the actual value measured by the wet method. The sampler is capable of reliable measurements of H2S at common levels of a polluted atmosphere in urban settings yielding average concentration levels over one month and beyond. Diffusive sampling can be adopted to analyse in detail the temporal and spatial trends of H2S concentration in ambient air and in specific historic buildings or in museums.

  11. Single session of integrated “silver yoga” program improves cardiovascular parameters in senior citizens

    PubMed Central

    Bhavanani, Ananda Balayogi; Ramanathan, Meena; Madanmohan

    2015-01-01

    Aim and Objective: This pilot study was carried out to determine cardiovascular effects of a single session of an integrated “silver yoga” program in senior citizens of Serene Pelican Township, Pondicherry. Materials and Methods: Heart rate (HR) and blood pressure (BP) measurements were recorded in 124 senior citizens (75 female, 49 male) with mean age of 67.19 ± 10.61 year who attended an integrated “Silver Yoga” program at Centre for Yoga Therapy, Education and Research from August to October 2014. Participants practiced the protocol that was specially designed for senior citizens, keeping in mind their health status and physical limitations. This included simple warm-ups (jathis), breath body movement coordination practices (kriyas), static stretching postures (asanas), breathing techniques (pranayamas), relaxation and simple chanting. Non-invasive BP apparatus was used to record the HR, systolic (SP) and diastolic pressure (DP) before and after the 60 min sessions. Pulse pressure (PP), mean pressure (MP), rate-pressure product (RPP) and double product (DoP) indices were derived from the recorded parameters. Student’s paired t-test was used to compare data that passed normality testing by Kolmogorov–Smirnov Test and Wilcoxon matched-pairs signed-ranks test for those that did not. P < 0.05 were accepted as indicating significant differences for pre-post comparisons. Results: All parameters witnessed a reduction following the single session. This was statistically more significant (P < 0. 0001) in HR, RPP and DoP while it was also significant (P < 0.01 and P < 0.05) in SP and PP, respectively. The decrease in MP just missed significance (P = 0.054) while it was not significant in DP. Conclusion: There is a healthy reduction in HR, BP and derived cardiovascular indices following a single yoga session in geriatric subjects. These changes may be attributed to enhanced harmony of cardiac autonomic function as a result of coordinated breath-body work and

  12. An improved cytological silver staining method for the demonstration of neuronal nuclear bodies.

    PubMed

    Lafarga, M; Gonzalez, C; Berciano, M T

    1986-12-01

    A simple cytological method for the selective impregnation of neuronal "nuclear bodies" is described. This procedure involves glutaraldehyde fixation, pretreatment with methanol-acetic acid, impregnation in a 1.5% colloidal solution of silver nitrate containing gelatin, and pyrogallic reduction of whole tissue blocks. After block staining the material was either dehydrated and embedded in araldite for light and electron microscopy studies, or processed for the elaboration of neuronal smear preparations, which were used for the quantitative analysis of nuclear bodies. By light microscopy, nuclear bodies appear as conspicuous, intensely impregnated inclusions, 0.3-0.9 micron in diameter. Both the nucleoli and cytoplasmic Nissl bodies can be counterstained with Toluidine blue. Overimpregnation produces an additional staining of the nucleolar fibrillar component.

  13. Improved thermal oxidation stability of solution-processable silver nanowire transparent electrode by reduced graphene oxide.

    PubMed

    Ahn, Yumi; Jeong, Youngjun; Lee, Youngu

    2012-12-01

    Solution-processable silver nanowire-reduced graphene oxide (AgNW-rGO) hybrid transparent electrode was prepared in order to replace conventional ITO transparent electrode. AgNW-rGO hybrid transparent electrode exhibited high optical transmittance and low sheet resistance, which is comparable to ITO transparent electrode. In addition, it was found that AgNW-rGO hybrid transparent electrode exhibited highly enhanced thermal oxidation and chemical stabilities due to excellent gas-barrier property of rGO passivation layer onto AgNW film. Furthermore, the organic solar cells with AgNW-rGO hybrid transparent electrode showed good photovoltaic behavior as much as solar cells with AgNW transparent electrode. It is expected that AgNW-rGO hybrid transparent electrode can be used as a key component in various optoelectronic application such as display panels, touch screen panels, and solar cells.

  14. Improving efficiency and reliability of environmental DNA analysis for silver carp

    USGS Publications Warehouse

    Amberg, Jon J.; McCalla, S. Grace; Monroe, Emy; Lance, Richard; Baerwaldt, Kelly; Gaikowski, Mark P.

    2015-01-01

    Natural resource agencies have established surveillance programs which use environmental DNA (eDNA) for the early detection of bighead carp Hypophthalmichthys nobilis and silver carp Hypophthalmichthys molitrix before they establish populations within the Great Lakes. This molecular monitoring technique must be highly accurate and precise for confident interpretation and also efficient, both in detection threshold and cost. Therefore, we compared two DNA extraction techniques and compared a new quantitative PCR (qPCR) assay with the conventional PCR (cPCR) assay used by monitoring programs. Both the qPCR and cPCR assays were able to amplify the DNA of silver carp present in environmental samples taken from locations where mixed populations of bigheaded carps existed. However, the qPCR assay had substantially fewer PCR positive samples which were subsequently determined not to contain DNA of bigheaded carps than the cPCR assay. Additionally, the qPCR assay was able to amplify the DNA of bigheaded carps even in the presence of inhibitors that blocked amplification with cPCR. Also, the selection of an appropriate DNA extraction method can significantly alter the efficiency of eDNA surveillance programs by lowering detection limits and by decreasing costs associated with sample processing. The results reported herein are presently being incorporated into eDNA surveillance programs to decrease the costs, increase DNA yield and increase the confidence that assays are amplifying the target DNA. These results are critical to enhancing our ability to accurately and confidently interpret the results reported from monitoring programs using eDNA for early detection of invasive species.

  15. High cycle fatigue life improvement of polycrystalline alpha-iron modified by silver, chromium, aluminium, and yttrium ion implantation

    SciTech Connect

    Wang, H.W.; Yang, D.Z.; Shi, W.D.; Patu, S.

    1995-06-15

    Body-centered cubic (bcc) metals are at least of parallel significance to fcc ones. Work on bcc metal`s fatigue modification by ion implantation is rare. The asymmetry deformation and high SFE characteristics in the microplasticity of bcc metals make the fatigue process more complex. The authors have chosen polycrystalline alpha-iron as the target metal to be implanted with silver, chromium, aluminium, and yttrium ions, which are mutually immiscible, limited soluble without precipitation, and soluble with precipitation in iron, respectively. This work aims at providing a systematic investigation on different mechanisms dominant in fatigue. This brief report is on the high cycle fatigue (HCF) property improvement by these metallic ion implantations, which is part of a series of reports both on HCF and low cycle fatigue (LCF) modifications by each individual ion implantation.

  16. Towards combined electrochemistry and surface-enhanced resonance Raman of heme proteins: Improvement of diffusion electrochemistry of cytochrome c at silver electrodes chemically modified with 4-mercaptopyridine.

    PubMed

    Millo, Diego; Ranieri, Antonio; Koot, Wynanda; Gooijer, Cees; van der Zwan, Gert

    2006-08-01

    To date, a successful combination of surface-enhanced resonance Raman spectroscopy (SERRS) and electrochemistry to study heme proteins is inhibited by the problems raised by the prerequisite to use silver as electrode metal. This paper indicates an approach to overcome these problems. It describes a quick and reproducible procedure to prepare silver electrodes chemically modified with 4-mercaptopyridine suitable to perform diffusion electrochemistry of cytochrome c (cyt c). The method involves the employment of a mechanical and a chemical treatment and avoids the use of alumina slurries and any electrochemical pretreatment. Cyclic voltammetry (CV) was used to test the electrochemical response of cyt c, and the CV signals were found identical with those obtained on gold electrodes under the same experimental conditions. Compared to previous literature, a significant improvement of the CV signal of cyt c at silver electrodes was achieved. Preliminary results show that this treatment can be also successfully employed for the preparation of SERRS-active electrodes.

  17. Thiomethylation of ketones by sulphide-alkaline solutions and formaldehyde

    SciTech Connect

    Ulendeyeva, A.D.; Samigullin, I.I.; Nasteka, V.I.

    1993-12-31

    An investigation has been made of the thiomethylation of ketones by formaldehyde with mercaptides, sodium sulphide and their mixture. It is possible to regenerate 78-100 rel.% of the sulphide-alkaline solutions under mild conditions (20-50{degrees}C, atmospheric pressure) without feeding a catalyst, with the simultaneous production of ketosulphide concentrate - a less toxic product with properties of practical benefit. 7 refs., 2 figs., 2 tabs.

  18. Ecosystem photosynthesis inferred from measurements of carbonyl sulphide flux

    NASA Astrophysics Data System (ADS)

    Asaf, David; Rotenberg, Eyal; Tatarinov, Fyodor; Dicken, Uri; Montzka, Stephen A.; Yakir, Dan

    2013-03-01

    Limited understanding of carbon dioxide sinks and sources on land is often linked to the inability to distinguish between the carbon dioxide taken up by photosynthesis, and that released by respiration. Carbonyl sulphide, a sulphur-containing analogue of carbon dioxide, is also taken up by plants, and could potentially serve as a powerful proxy for photosynthetic carbon dioxide uptake, which cannot be directly measured above the leaf scale. Indeed, variations in atmospheric concentrations of carbonyl sulphide are closely related to those of carbon dioxide at regional, local and leaf scales. Here, we use eddy covariance and laser spectroscopy to estimate the net exchange of carbon dioxide and carbonyl sulphide across three pine forests, a cotton field and a wheat field in Israel. We estimate gross primary productivity--a measure of ecosystem photosynthesis--directly from the carbonyl sulphide fluxes, and indirectly from carbon dioxide fluxes. The two estimates agree within an error of +/-15%. The ratio of carbonyl sulphide to carbon dioxide flux at the ecosystem scale was consistent with the variability in mixing ratios observed on seasonal timescales in the background atmosphere. We suggest that atmospheric measurements of carbonyl sulphide flux could provide an independent constraint on estimates of gross primary productivity, key to projecting the response of the land biosphere to climate change.

  19. Magnetic sorbents biomineralization on the basis of iron sulphides.

    PubMed

    Jencarova, Jana; Luptakova, Alena; Vitkovska, Nikola; Matysek, Dalibor; Jandacka, Petr

    2017-08-30

    Biomineralization means mineral formation under the influence of organisms. Sulphate-reducing bacteria (SRB) constitute an essential role of iron sulphide minerals precipitation. Their composition involves amorphous, non-stoichiometric or crystalline iron sulphides, weakly or strongly magnetic. Variation in environmental conditions can alter the reactive iron species within the mineral, potentially modifying their magnetic properties. Biogenic iron sulphide minerals can be used as heavy metals and toxic ions adsorbents in soil or water remediation. For these reasons, a series of laboratory-scale iron sulphide synthesis experiments with the aim to study the chemical composition, mineralogy and magnetic properties of iron sulphide precipitates were carried out using SRB under various cultivation mode and nutrient medium composition. Energy-dispersive X-ray analysis (EDX) showed formation of iron sulphides in all biogenic samples and iron phosphates in abiotic controls. Results of X-ray diffraction analysis (XRD) in biomineralized samples confirmed nanocrystalline greigite, mackinawite and sulphur alpha. Magnetic measurements showed that sample prepared by static cultivation without addition of fresh nutrient medium was the most magnetic, magnetic hysteresis of sample formed under semicontinuous mode without any nutrient supply was the lowest. Abiotic samples contained only vivianite and they did not prove any significant response to magnetic field.

  20. Simultaneous biodesulphurization and denitrification using an oil reservoir microbial culture: Effects of sulphide loading rate and sulphide to nitrate loading ratio.

    PubMed

    An, Shijie; Tang, Kimberley; Nemati, Mehdi

    2010-03-01

    Biooxidation of sulphide under denitrifying conditions is a key process in control of souring in oil reservoirs and in treatment of gas and liquids contaminated with sulphide and nitrate. In this work, biooxidation of sulphide was studied using a representative culture originated from an oil reservoir. Effects of sulphide concentration, sulphide to nitrate molar ratio, and loading rates of sulphide and nitrate on their removal rates and composition of the end products were investigated. In the batch system sulphide removal rate passed through a maximum as sulphide concentration was increased from 2.1 to 16.3mM, with the highest rate (2.06mMh(-1)) observed with 10.7mM sulphide. Nitrate removal was coupled to sulphide oxidation and the highest removal rate was 1.05mMh(-1). In the continuous bioreactors fed with 10 and 5, 15 and 7.5, and 20 and 10mM sulphide and nitrate, cell wash-out occurred as dilution rate was increased above 0.15, 0.13 and 0.08h(-1), respectively. Prior to cell wash-out linear increases in sulphide and nitrate removal rates were observed as loading rate was increased. The highest sulphide and nitrate removal rates of 2.0 and 0.92mMh(-1) were obtained in the bioreactor fed with 15mM sulphide and 7.5mM nitrate at loading rates of 2.1 and 0.93mMh(-1), respectively. Short residence times and high sulphide to nitrate ratios promoted the formation of sulphur, a desired end product for ex situ treatment of contaminated streams. Combination of long residence times and low sulphide to nitrate ratios, which favours formation of sulphate, is the suitable strategy for in situ removal of H(2)S from oil reservoirs.

  1. Silver nanowire based flexible electrodes with improved properties: High conductivity, transparency, adhesion and low haze

    SciTech Connect

    Kiran Kumar, A.B.V.; Wan Bae, Chang; Piao, Longhai Kim, Sang-Ho

    2013-08-01

    Graphical abstract: This graphical abstract illustrates the schematic representation of the main drawbacks and rectifications for AgNWs based transparent electrodes. - Highlights: • Films exhibited low sheet resistance and optical properties with R{sub s} ≤ 30 Ω/□ and T ≥ 90%. • We decreased haze to 2% by controlling AgNWs length, diameter, and concentration. • We achieved good adhesion for AgNWs on PET film. • There is no significant change in resistance in the bending angle from 0° to 180°, and on twisting. - Abstract: Recent work has been focusing on solution processable transparent electrodes for various applications including solar cells and displays. As well as, the research aims majorly at silver nanowires (AgNWs) to replace ITO. We enhance the transparent electrode performance as a function of optical and mechanical properties with low sheet resistance, by controlling the AgNWs accept ratios, ink composition, and processing conditions. The nanowire network of transparent films agrees with the 2D percolation law. The film transmittance values at 550 nm are coping with a reference ITO film. Sheet resistance and haze values are suitable for flexible electronic applications. We fabricate transparent flexible film using a low-cost processing technique.

  2. Silver nanowire/polyaniline composite transparent electrode with improved surface properties

    SciTech Connect

    Kumar, A.B.V. Kiran; Jiang, Jianwei; Bae, Chang Wan; Seo, Dong Min; Piao, Longhai Kim, Sang-Ho

    2014-09-15

    Highlights: • AgNWs/PANI transparent electrode was prepared by layer-by-layer coating method. • The surface roughness of the electrode reached to 6.5 nm (root mean square). • The electrode had reasonable sheet resistance (25 Ω/□) and transmittance (83.5%). - Abstract: Silver nanowires (AgNWs) are as potential candidates to replace indium tin oxide (ITO) in transparent electrodes because of their preferred conducting and optical properties. However, their rough surface properties are not favorable for the fabrication of optoelectronic devices, such as displays and thin-film solar cells. In the present investigation, AgNWs/polyaniline composite transparent electrodes with better surface properties were successfully prepared. AgNWs were incorporated into polyaniline:polystyrene sulfonate (PANI:PSS) by layer-by-layer coating and mechanical pressing. PANI:PSS decreased the surface roughness of the AgNWs electrode by filling the gap of the random AgNWs network. The transparent composite electrode had decreased surface roughness (root mean square 6.5 nm) with reasonable sheet resistance (25 Ω/□) and transmittance (83.5%)

  3. Improved antifouling potential of polyether sulfone polymeric membrane containing silver nanoparticles: self-cleaning membranes.

    PubMed

    Rana, Sidra; Nazar, Umair; Ali, Jafar; Ali, Qurat Ul Ain; Ahmad, Nasir M; Sarwar, Fiza; Waseem, Hassan; Jamil, Syed Umair Ullah

    2017-05-26

    A new strategy to enhance the antifouling potential of polyether sulfone (PES) membrane is presented. Chemically synthesized silver nanoparticles (AgNPs) were used to prepare a mixed-matrix PES membrane by the phase inversion technique. Primarily, AgNPs synthesis was confirmed by surface plasmon resonance at 410-430 nm using UV-Visible spectroscopy. X-ray diffraction analysis revealed that AgNPs were crystalline with a diameter of 21 ± 2 nm. Furthermore, PES membranes were characterized by energy dispersive X-ray spectroscopy to confirm the incorporation of AgNPs in membranes. Hydrophilicity of the membranes was enhanced, whereas roughness, mechanical strength and biofouling were relatively reduced after embedding the AgNPs. Antibacterial potential of AgNPs was evaluated for E. coli in the disc diffusion and colony-forming unit (CFU) count method. All of the membranes were assessed for antifouling activity by filtering a control dilution (10(6) CFU/ml) of E. coli and by counting CFU. Anti-biofouling activity of the membrane was observed with different concentrations of AgNPs. Maximum reduction (66%) was observed in membrane containing 1.5% of AgNPs. The addition of antibiotic ceftriaxone enhanced the antibacterial effect of AgNPs in PES membranes. Our practicable antifouling strategy may be applied to other polymeric membranes which may pave the new way to achieve sustainable and self-cleaning membrane reactors on large scale.

  4. Carbon Nanotube Networks Reinforced by Silver Nanowires with Improved Optical Transparency and Conductivity

    NASA Astrophysics Data System (ADS)

    Martine, Patricia; Fakhimi, Azin; Lin, Ling; Jurewicz, Izabela; Dalton, Alan; Zakhidov, Anvar A.; Baughman, Ray H.

    2015-03-01

    We have fabricated highly transparent and conductive free-standing nanocomposite thin film electrodes by adding silver nanowires (AgNWs) to dry-spun Multiwall Carbon Nanotube (MWNT) aerogels. This nanocomposite exhibits desirable properties such as high optical transmittance, excellent flexibility and enhanced electrical conductivity. The incorporation of the AgNWs to the MWNT aerogels was accomplished by using a spray coating method. The optical transparency and sheet resistance of the nanocomposite was tuned by adjusting the concentration of AgNWs, back pressure and nozzle distance of the spray gun to the MWNT aerogel during deposition. As the solvent evaporated, the aerogel MWNT bundles densified via surface tension which caused the MWNT bundles to collapse. This adjustable process was responsible in forming well defined apertures that increased the nanocomposite's transmittance up to 90 percent. Via AgNWs percolation and random interconnections between separate MWNT bundles in the aerogel matrix, the sheet resistance decreased from 1 K ohm/sq to less than 100 ohm/sq. Alan G. MacDiarmid NanoTech Institute

  5. Improved UV response of ZnO nanotubes by resonant coupling of anchored plasmonic silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Biswas, Pranab; Cho, Seong Rae; Kim, Jong-Woo; Baek, Sung-Doo; Myoung, Jae-Min

    2017-06-01

    In this study, plasmonic silver (Ag) nanoparticle-(NP) anchored ZnO nanorods (NRs) and nanotube-(NT) based UV photodetectors are demonstrated. Here, Ag NPs are synthesized and anchored by using a room-temperature photochemical method by exposing the precursor solution in UV radiation. In order to achieve a stronger surface plasmon resonance (SPR) and minimum agglomeration, the photochemical method is optimized with a precursor concentration of 5 mmol, a UV intensity of 0.4 mW · cm-2, and an exposure time of 30 min. An asymmetry around 380 nm in the absorption spectra of the NP solution indicates the presence of plasmonic resonance in that region. Upon anchoring the Ag NPs, ZnO NRs show enhanced band edge emission (380-400 nm) and the emission is further significantly increased in Ag NP-anchored ZnO NTs. The on/off ratio and photoresponse properties of the UV photodetectors are enhanced significantly after anchoring Ag NPs on the ZnO nanostructures. It is believed that the near-field coupling of SPR causes an optical enhancement of ZnO, whereas the bridging effect and hot-electron transfer to the conduction band of ZnO by plasmonic Ag NPs, anchored in close proximity, gives rise to a faster response of the photodetectors.

  6. Preparation of silver-activated zinc sulfide thin films

    NASA Technical Reports Server (NTRS)

    Feldman, C.; Swindells, F. E.

    1968-01-01

    Silver improves luminescence and reduces contamination of zinc sulfide phosphors. The silver is added after the zinc sulfide phosphors are deposited in thin films by vapor evaporation, but before calcining, by immersion in a solution of silver salt.

  7. Towards high quality triangular silver nanoprisms: improved synthesis, six-tip based hot spots and ultra-high local surface plasmon resonance sensitivity

    NASA Astrophysics Data System (ADS)

    Xue, Bin; Wang, Dan; Zuo, Jing; Kong, Xianggui; Zhang, Youlin; Liu, Xiaomin; Tu, Langping; Chang, Yulei; Li, Cuixia; Wu, Fei; Zeng, Qinghui; Zhao, Haifeng; Zhao, Huiying; Zhang, Hong

    2015-04-01

    The great application potential of triangular silver nanoprisms (TSNPRs, also referred to as triangular silver nanoplates) is hampered by the lack of methods to produce well-defined tips with high monodispersity, with easily removable ligands. In this work, a simple one-step plasmon-mediated method was developed to prepare monodisperse high-quality TSNPRs. In this approach, the sole surface capping agent was the easily removable trisodium citrate. Differing from common strategies using complex polymers, OH- ions were used to improve the monodispersity of silver seeds, as well as to control the growth process through inhibiting the oxidation of silver nanoparticles. Using these monodisperse high-quality TSNPRs as building blocks, self-assembled TSNPRs consisting of six-tip based ``hot spots'' were realized for the first time as demonstrated in a high enhancement (~107) of surface-enhanced Raman scattering (SERS). From the plasmon band shift versus the refractive index, ultra-high local surface plasmon resonance sensitivity (413 nm RIU-1 or 1.24 eV RIU-1, figure of merit (FOM) = 4.59) was reached at ~630 nm, making these materials promising for chemical/biological sensing applications.The great application potential of triangular silver nanoprisms (TSNPRs, also referred to as triangular silver nanoplates) is hampered by the lack of methods to produce well-defined tips with high monodispersity, with easily removable ligands. In this work, a simple one-step plasmon-mediated method was developed to prepare monodisperse high-quality TSNPRs. In this approach, the sole surface capping agent was the easily removable trisodium citrate. Differing from common strategies using complex polymers, OH- ions were used to improve the monodispersity of silver seeds, as well as to control the growth process through inhibiting the oxidation of silver nanoparticles. Using these monodisperse high-quality TSNPRs as building blocks, self-assembled TSNPRs consisting of six-tip based ``hot

  8. Polarization effects of unconsolidated sulphide-sand-mixtures

    NASA Astrophysics Data System (ADS)

    Hupfer, Sarah; Martin, Tina; Weller, Andreas; Günther, Thomas; Kuhn, Kerstin; Djotsa Nguimeya Ngninjio, Victorien; Noell, Ursula

    2016-12-01

    ore mineral content, grain radius and fluid conductivity can be derived from laboratory SIP measurements. The method seems to be suitable to identify sulphide minerals in sandy mixtures but a differentiation between the different types of ore minerals remains a challenging task. Nevertheless, more investigations are required to improve the reliability of these findings towards a field scale application.

  9. Effects of hydrogen sulphide in smooth muscle.

    PubMed

    Dunn, William R; Alexander, Stephen P H; Ralevic, Vera; Roberts, Richard E

    2016-02-01

    In recent years, it has become apparent that the gaseous pollutant, hydrogen sulphide (H2S) can be synthesised in the body and has a multitude of biological actions. This review summarizes some of the actions of this 'gasotransmitter' in influencing the smooth muscle that is responsible for controlling muscular activity of hollow organs. In the vasculature, while H2S can cause vasoconstriction by complex interactions with other biologically important gases, such as nitric oxide, the prevailing response is vasorelaxation. While most vasorelaxation responses occur by a direct action of H2S on smooth muscle cells, it has recently been proposed to be an endothelium-derived hyperpolarizing factor. H2S also promotes relaxation in other smooth muscle preparations including bronchioles, the bladder, gastrointestinal tract and myometrium, opening up the opportunity of exploiting the pharmacology of H2S in the treatment of conditions where smooth muscle tone is excessive. The original concept, that H2S caused smooth muscle relaxation by activating ATP-sensitive K(+) channels, has been supplemented with observations that H2S can also modify the activity of other potassium channels, intracellular pH, phosphodiesterase activity and transient receptor potential channels on sensory nerves. While the enzymes responsible for generating endogenous H2S are widely expressed in smooth muscle preparations, it is much less clear what the physiological role of H2S is in determining smooth muscle contractility. Clarification of this requires the development of potent and selective inhibitors of H2S-generating enzymes. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Antimicrobial effect of diallyl sulphide on Campylobacter jejuni biofilms

    PubMed Central

    Lu, Xiaonan; Samuelson, Derrick R.; Rasco, Barbara A.; Konkel, Michael E.

    2012-01-01

    Objectives Bacterial biofilms pose significant food safety risks because of their attachment to fomites and food surfaces, including fresh produce surfaces. The purpose of this study was to systematically investigate the activity of selected antimicrobials on Campylobacter jejuni biofilms. Methods C. jejuni biofilms and planktonic cells were treated with ciprofloxacin, erythromycin and diallyl sulphide and examined using infrared and Raman spectroscopies coupled with imaging analysis. Results Diallyl sulphide eliminated planktonic cells and sessile cells in biofilms at a concentration that was at least 100-fold less than used for either ciprofloxacin or erythromycin on the basis of molarity. Distinct cell lysis was observed in diallyl sulphide-treated planktonic cells using immunoblot analysis and was confirmed by a rapid decrease in cellular ATP. Two phases of C. jejuni biofilm recalcitrance modes against ciprofloxacin and erythromycin were validated using vibrational spectroscopies: (i) an initial hindered adsorption into biofilm extracellular polymeric substance (EPS) and delivery of antibiotics to sessile cells within biofilms; and (ii) a different interaction between sessile cells in a biofilm compared with their planktonic counterparts. Diallyl sulphide destroyed the EPS structure of the C. jejuni biofilm, after which the sessile cells were killed in a similar manner as planktonic cells. Spectroscopic models can predict the survival of sessile cells within biofilms. Conclusions Diallyl sulphide elicits strong antimicrobial activity against planktonic and sessile C. jejuni and may have applications for reducing the prevalence of this microbe in foods, biofilm reduction and, potentially, as an alternative chemotherapeutic agent for multidrug-resistant bacterial strains. PMID:22550133

  11. Towards high quality triangular silver nanoprisms: improved synthesis, six-tip based hot spots and ultra-high local surface plasmon resonance sensitivity.

    PubMed

    Xue, Bin; Wang, Dan; Zuo, Jing; Kong, Xianggui; Zhang, Youlin; Liu, Xiaomin; Tu, Langping; Chang, Yulei; Li, Cuixia; Wu, Fei; Zeng, Qinghui; Zhao, Haifeng; Zhao, Huiying; Zhang, Hong

    2015-05-07

    The great application potential of triangular silver nanoprisms (TSNPRs, also referred to as triangular silver nanoplates) is hampered by the lack of methods to produce well-defined tips with high monodispersity, with easily removable ligands. In this work, a simple one-step plasmon-mediated method was developed to prepare monodisperse high-quality TSNPRs. In this approach, the sole surface capping agent was the easily removable trisodium citrate. Differing from common strategies using complex polymers, OH(-) ions were used to improve the monodispersity of silver seeds, as well as to control the growth process through inhibiting the oxidation of silver nanoparticles. Using these monodisperse high-quality TSNPRs as building blocks, self-assembled TSNPRs consisting of six-tip based "hot spots" were realized for the first time as demonstrated in a high enhancement (∼10(7)) of surface-enhanced Raman scattering (SERS). From the plasmon band shift versus the refractive index, ultra-high local surface plasmon resonance sensitivity (413 nm RIU(-1) or 1.24 eV RIU(-1), figure of merit (FOM) = 4.59) was reached at ∼630 nm, making these materials promising for chemical/biological sensing applications.

  12. High-performance cadmium sulphide-based planar perovskite solar cell and the cadmium sulphide/perovskite interfaces

    NASA Astrophysics Data System (ADS)

    Peng, Haitao; Sun, Weihai; Li, Yunlong; Yan, Weibo; Yu, Pingrong; Zhou, Huanping; Bian, Zuqiang; Huang, Chunhui

    2016-04-01

    Planar heterojunction perovskite solar cell is one of the most competitive photovoltaic technologies, while charge transport materials play a crucial role. We successfully demonstrated an effective electron transport material, namely chemical bath deposited cadmium sulphide (CdS) film under low temperature, in perovskite-based solar cells. Power conversion efficiency of 16.1% has been achieved, which is comparable to that of devices based on TiO2 film prepared via low-temperature processes. Electronic impedance spectra reveal that the CdS-based device presents a higher recombination resistance than TiO2-based devices, which reduces carrier recombination and increases the open circuit voltage. The interface between CdS and perovskite was characterized with improved characteristics when compared to TiO2, e.g., efficient carrier extraction and reduced surface defect-associated degradation in the devices, which help to alleviate anomalous hysteresis and long-term instability. Furthermore, the entire device was fabricated via solution process with a processing temperature below 100°C, suggesting a promising method of further development of perovskite solar cells and commercial manufacturing.

  13. Determination of sulphide by anion-exchange with lead iodate.

    PubMed

    Verma, K K; Gupta, D; Sanghi, S K; Jain, A

    1988-11-01

    A quick anion-exchange reaction, suitable for the determination of sulphide, has been found to occur on stirring a suspension of lead iodate (solubility product, K(s0) = 1.2 x 10(-13)) with sulphide solution at pH 5-8. After removal of the precipitates of lead iodate and lead sulphide (K(s0) = 3.4 x 10(-28)), the iodate released can be determined by its reaction with acidified iodide to give tri-iodide which is either titrated with thiosulphate or measured spectrophotometrically as its blue complex with starch. Chloride, bromide, iodide, fluoride, oxalate, sulphate, thiocyanate and phosphate do not interfere. Thiosulphate, sulphite, nitrite and thiols do not give an anion-exchange reaction but do interfere in the redox reaction of iodate with acidified iodide. However, this is avoided if they are first oxidized with bromine (the liberated iodate remains unaffected before iodometry.

  14. Structural and optical properties of copper zinc tin sulphide (CZTS) material synthesized using binary sulphide precursors

    NASA Astrophysics Data System (ADS)

    Patel, K. K.; Shah, D. V.; Kheraj, Vipul

    2013-02-01

    Copper Zinc Tin Sulphide (CZTS) is one of the most promising materials for absorber layer in thin film solar cells. However, the synthesis of CZTS requires careful optimization as it is a quaternary material with a high probability of formation of secondary phases during the synthesis. Here we report the synthesis of CZTS from its binary constituents i.e. CuS, SnS and ZnS at 1030 K in laboratory. The effects of excess sulphur in starting precursors on the chemical compositions of the compound are investigated. Structural and optical properties of synthesized compound are studied in context of its application as absorber material in thin film solar cells.

  15. Silver Nanowire Embedded Colorless Polyimide Heater for Wearable Chemical Sensors: Improved Reversible Reaction Kinetics of Optically Reduced Graphene Oxide.

    PubMed

    Choi, Seon-Jin; Kim, Sang-Joon; Jang, Ji-Soo; Lee, Ji-Hyun; Kim, Il-Doo

    2016-09-14

    Optically reduced graphene oxide (ORGO) sheets are successfully integrated on silver nanowire (Ag NW)-embedded transparent and flexible substrate. As a heating element, Ag NWs are embedded in a colorless polyimide (CPI) film by covering Ag NW networks using polyamic acid and subsequent imidization. Graphene oxide dispersed aqueous solution is drop-coated on the Ag NW-embedded CPI (Ag NW-CPI) film and directly irradiated by intense pulsed light to obtain ORGO sheets. The heat generation property of Ag NW-CPI film is investigated by applying DC voltage, which demonstrates unprecedentedly reliable and stable characteristics even in dynamic bending condition. To demonstrate the potential application in wearable chemical sensors, NO2 sensing characteristic of ORGO is investigated with respect to the different heating temperature (22.7-71.7 °C) of Ag NW-CPI film. The result reveals that the ORGO sheets exhibit high sensitivity of 2.69% with reversible response/recovery sensing properties and minimal deviation of baseline resistance of around 1% toward NO2 molecules when the temperature of Ag NW-CPI film is 71.7 °C. This work first demonstrates the improved reversible NO2 sensing properties of ORGO sheets on flexible and transparent Ag NW-CPI film assisted by Ag NW heating networks. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Fabrication of flexible silver nanowire conductive films and transmittance improvement based on moth-eye nanostructure array

    NASA Astrophysics Data System (ADS)

    Zhang, Chengpeng; Zhu, Yuwen; Yi, Peiyun; Peng, Linfa; Lai, Xinmin

    2017-07-01

    Transparent conductive electrodes (TCEs) are widely used in optoelectronic devices, such as touch screens, liquid-crystal displays and light-emitting diodes. To date, the material of the most commonly used TCEs was indium-tin oxide (ITO), which had several intrinsic drawbacks that limited its applications in the long term, including relatively high material cost and brittleness. Silver nanowire (AgNW), as one of the alternative materials for ITO TCEs, has already gained much attention all over the world. In this paper, we reported a facile method to greatly enhance the transmittance of the AgNW TCEs without reducing the electrical conductivity based on moth-eye nanostructures, and the moth-eye nanostructures were fabricated by using a roll-to-roll ultraviolet nanoimprint lithography process. Besides, the effects of mechanical pressure and bending on the moth-eye nanostructure layer were also investigated. In the research, the optical transmittance of the flexible AgNW TCEs was enhanced from 81.3% to 86.0% by attaching moth-eye nanostructures onto the other side of the flexible polyethylene terephthalate substrate while the electrical conductivity of the AgNW TCEs was not sacrificed. This research can provide a direction for the cost-effective fabrication of moth-eye nanostructures and the transmittance improvement of the flexible transparent electrodes.

  17. Improved Performance by SiO2 Hollow Nanospheres for Silver Nanowire-Based Flexible Transparent Conductive Films.

    PubMed

    Zhang, Liwen; Zhang, Longjiang; Qiu, Yejun; Ji, Yang; Liu, Ya; Liu, Hong; Li, Guangji; Guo, Qiuquan

    2016-10-12

    Flexible transparent conductive films (TCFs) have attracted tremendous interest thanks to the rapid development of portable/flexible/wearable electronics. TCFs on the basis of silver nanowires (AgNWs) with excellent performance are becoming an efficient alternative to replace the brittle transparent metal oxide. In this study, a promising method was developed by introducing SiO2 hollow nanospheres (SiO2-HNSs) into the film to significantly improve the performance of AgNW-based TCFs. Since SiO2-HNSs have opposite charges to AgNWs, the strong attraction had promoted a uniform distribution of AgNWs and made the distance between AgNWs closer, which could decrease the contact resistance greatly. The introduction of SiO2 layer remarkably enhanced the transmission of visible light and the conductivity. In addition, the TCFs constructed by AgNWs and SiO2-HNSs showed much higher thermal stability and adhesive force than those by only AgNWs. As an example, the transmission of AgNW/SiO2-HNS-coated poly(ethylene terephthalate) (PET) could increase about 14.3% in comparison to AgNW-coated PET. Typically, a AgNW/SiO2-HNS-based TCF with a sheet resistance of about 33 Ω/sq and transmittance of about 98.0% (excluding substrate) could be obtained with excellent flexibility, adhesion, and thermal stability. At last some devices were fabricated.

  18. Silver nanoparticles in combination with acetic acid and zinc oxide quantum dots for antibacterial activities improvement-A comparative study

    NASA Astrophysics Data System (ADS)

    Sedira, Sofiane; Ayachi, Ahmed Abdelhakim; Lakehal, Sihem; Fateh, Merouane; Achour, Slimane

    2014-08-01

    Due to their remarkable antibacterial/antivirus properties, silver nanoparticles (Ag NPs) and zinc oxide quantum dots (ZnO Qds) have been widely used in the antimicrobial field. The mechanism of action of Ag NPs on bacteria was recently studied and it has been proven that Ag NPs exerts their antibacterial activities mainly by the released Ag+. In this work, Ag NPs and ZnO Qds were synthesized using polyol and hydrothermal method, respectively. It was demonstrated that Ag NPs can be oxidized easily in aqueous solution and the addition of acetic acid can increase the Ag+ release which improves the antibacterial activity of Ag NPs. A comparative study between bactericidal effect of Ag NPs/acetic acid and Ag NPs/ZnO Qds on Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus was undertaken using agar diffusion method. The obtained colloids were characterized using UV-vis spectroscopy, Raman spectrometry, X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM).

  19. Oxygen solubility and speciation in sulphide-rich mattes

    NASA Astrophysics Data System (ADS)

    Fonseca, Raúl O. C.; Campbell, Ian H.; O'Neill, Hugh St. C.; Fitzgerald, John D.

    2008-06-01

    Sulphide-rich liquids are common in magmatic environments forming over a wide range of temperature, pressure, fO 2 and fS 2. They are economically important because they sequester valuable metals such as Cu, Ni, Au and Pt from silicate melts. The presence of accessory amounts of primary oxides associated with sulphide mineralisations is often ignored or unexplained. Experimental work has shown that large amounts of oxygen can dissolve into mattes at fO 2 typical of terrestrial environments. At the quartz-fayalite-magnetite fO 2 buffer, the molar fraction of O in the matte exceeds that of S, placing the composition of the matte to the magnetite side of the mss (monosulphide solid solution)-magnetite join in the Fe-S-O system. However, sulphides crystallise before magnetite in most sulphide mineralisations and are much more abundant. Moreover, the speciation of O in a matte is not well known. Here we report the results of an experimental study of the solubility of O in mattes as a function of fS 2, fO 2, temperature, and composition. We confirm previous observations that Ni and Cu have a negative effect on the solubility of O in mattes. We show evidence for the existence of FeSO as a structural constituent of mattes in the Fe-S-O system. We present a simple parameterisation of the amount of O dissolved in mattes under relevant geological conditions, and use this parameterisation to discuss mechanisms for the crystallisation of primary spinels associated with sulphides in the Kambalda massive sulphide deposit (Western Australia) and the Sudbury Igneous Complex (Ontario, Canada).

  20. Trace and minor elements in sphalerite from metamorphosed sulphide deposits

    NASA Astrophysics Data System (ADS)

    Lockington, Julian A.; Cook, Nigel J.; Ciobanu, Cristiana L.

    2014-12-01

    Sphalerite is a common sulphide and is the dominant ore mineral in Zn-Pb sulphide deposits. Precise determination of minor and trace element concentrations in sulphides, including sphalerite, by Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry (LA-ICP-MS) is a potentially valuable petrogenetic tool. In this study, LA-ICP-MS is used to analyse 19 sphalerite samples from metamorphosed, sphalerite-bearing volcanic-associated and sedimentary exhalative massive sulphide deposits in Norway and Australia. The distributions of Mn, Fe, Co, Cu, Ga, Se, Ag, Cd, In, Sn, Sb, Hg, Tl, Pb and Bi are addressed with emphasis on how concentrations of these elements vary with metamorphic grade of the deposit and the extent of sulphide recrystallization. Results show that the concentrations of a group of trace elements which are believed to be present in sphalerite as micro- to nano-scale inclusions (Pb, Bi, and to some degree Cu and Ag) diminish with increasing metamorphic grade. This is interpreted as due to release of these elements during sphalerite recrystallization and subsequent remobilization to form discrete minerals elsewhere. The concentrations of lattice-bound elements (Mn, Fe, Cd, In and Hg) show no correlation with metamorphic grade. Primary metal sources, physico-chemical conditions during initial deposition, and element partitioning between sphalerite and co-existing sulphides are dominant in defining the concentrations of these elements and they appear to be readily re-incorporated into recrystallized sphalerite, offering potential insights into ore genesis. Given that sphalerite accommodates a variety of trace elements that can be precisely determined by contemporary microanalytical techniques, the mineral has considerable potential as a geothermometer, providing that element partitioning between sphalerite and coexisting minerals (galena, chalcopyrite etc.) can be quantified in samples for which the crystallization temperature can be independently

  1. Recovery of Cu and Zn from Complex Sulphide Ore

    NASA Astrophysics Data System (ADS)

    Talapaneni, Trinath; Sarkar, S.; Yedla, N.; Reddy, P. L. N., Dr

    2015-02-01

    Complex Sulphide Ores are often found to be a close mutual association with each other and with the nonmetallic gangue. The beneficiation experiments showed that it would be very difficult to recover Cu and Zn from the lean complex Sulphide ores using traditional ore beneficiation methods. In the present work, leaching of complex sulfide ores in sulfuric acid was investigated by the Electro hydrometallurgy process. The lab-scale experiments were conducted to investigate the influences of pulp-density, electrolyte concentration, particle size, current density and time on recovery of Cu and Zn. The leach liquor obtained after electrolysis was subjected to Atomic Absorption Spectroscopy analysis for the recovery of minerals.

  2. Silver and Co-Ni sulphoarsenides from the Kongsberg silver deposit, Norway

    NASA Astrophysics Data System (ADS)

    Kullerud, Kåre; Kotková, Jana; Škoda, Radek

    2015-04-01

    The historical silver mines at Kongsberg, Norway, are world-famous for spectacular samples of thread silver exhibited at numerous mineralogical museums. More than 100 minerals have been reported from the deposit, including native elements (Ag, Au, As, Cu, S, C), sulphides, sulphosalts, selenides, arsenides, carbonates, sulphates, arsenates and halides, in addition to a range of silicate minerals (Neumann, 1944; Johnsen, 1986, 1987; Bancroft et al., 2001). However, documentation of the minerals using state-of-the-art methods such as electron microprobe, with implications for the genesis of the deposit, is largely missing. In our contribution, we present new data on the compositional variations of silver and sulphoarsenides from the silver deposit. Most of the ore minerals studied here occur in calcite veins in the hosting gneiss. For some samples, however, fluorite is the dominating vein mineral associated with the ore minerals. Mineral textures show that native silver formed during at least two separate stages. The earliest generation of native silver is typically represented by euhedral to subhedral crystals, up to 1 mm long. These crystals frequently contain rounded inclusions of acanthite, chalcopyrite and polybasite, and they are commonly rimmed by a zone consisting of Co-Ni-Fe bearing sulphoarsenides. The later generation of native silver occurs as fracture fillings, often enclosing the earlier Ag generation with its rim of sulphoarsenides. Native silver shows significant variations in Hg, Au and Sb contents. Concentrations of up to 20 wt% Hg and up to 2.7 wt% Sb in silver have been measured during the present study. Dyscrasite and allargentum have also been observed in association with native silver. Neumann (1944) reported auriferous silver with up to 50 % Au. The sulphoarsenides rimming the crystals of the first silver generation vary in composition along the cobaltite-gersdorffite series with approximate limiting compositions Ni0.8Fe0.2AsS and Co0.51Ni0

  3. Improved, low cost inorganic-organic separators for rechargeable silver-zinc batteries

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.

    1979-01-01

    Several flexible, low-cost inorganic-organic separators with performance characteristics and cycle life equal to, or better than, the Lewis Research Center Astropower separator were developed. These new separators can be made on continuous-production equipment at about one-fourth the cost of the Astropower separator produced the same way. In test cells, these new separators demonstrate cycle life improvement, acceptable operating characteristics, and uniform current density. The various separator formulas, test cell construction, and data analysis are described.

  4. Fe-Ni exchange between olivine and sulphide liquid: implications for oxygen barometry in sulphide-saturated magmas

    NASA Astrophysics Data System (ADS)

    Brenan, J. M.; Caciagli, N. C.

    2000-01-01

    In order to better understand the behaviour of nickel in magmatic processes, we have measured the apparent equilibrium constant ( KD) for the exchange of Fe and Ni between coexisting olivine and sulphide liquid at controlled oxygen and sulphur fugacities ( fO 2 = 10 -8-10 -10 and fS 2 = 10 -2-10 -4) over the temperature range 1200 to 1400°C and with 5 to 50 wt.% nickel in the sulphide liquid. Measured values of KD are independent of temperature and sulphur fugacity, but increase linearly with the nickel content of the sulphide liquid, and follow a power-law increase with oxygen fugacity; behaviour that is consistent with previous measurements of KD under controlled conditions of fO 2 and fS 2. The variation of KD with melt nickel content and fO 2 is most likely the result of nonideal mixing in the sulphide liquid, which results in a decrease in γ NiS/γ FeS with melt metal/sulphur ratio. As a consequence of the systematic dependence of KD on fO 2, a new oxygen barometer is proposed for estimating oxygen fugacity in igneous rocks that were cosaturated in olivine and sulphide liquid. Application of the experimental results to natural samples shows that the relatively large variations that exist in KD values from different olivine + sulphide-saturated rock suites can be interpreted as arising from variations in fO 2 and/or the nickel content of the sulphide liquid. Oxygen fugacities calculated for oceanic basalt samples using the proposed Fe-Ni exchange oxybarometer are found to be relatively high (10 -8.5-10 -10.4) which is in accord with the range of values determined using glass ferric/ferrous ratios. Moreover, the very low fO 2 (˜10 -14) calculated for the mafic dike from Disko Island is consistent with the presence of native iron in these samples and is in quantitative agreement with indicators of fO 2 based on chromite- and olivine-melt partitioning of vanadium. Consideration of the fO 2 exhibited by olivine + sulphide-saturated intrusive suites reveals a

  5. Improve the fluorescence quenching efficiency of gold nanorod by silver coating

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Zhu, Jian; Li, Jian-Jun; Zhao, Jun-Wu

    2013-11-01

    The interactions of bovine serum albumins (BSA) with Au-Ag core-shell nanorods have been studied using fluorescence spectroscopic techniques. It was observed that Ag coated Au nanorods exhibit higher fluorescence quenching efficiency compared with bare Au nanorods. The fluorescence quenching efficiency could be further improved by increasing the aspect ratio or Ag shell thickness of the Au nanorods. Furthermore, the quenching efficiency to BSA is increased as the concentration of BSA is decreased. The physical origin has been illustrated by calculating the dielectric environment dependent fluorescence quenching based on quasi-static theory and fluorescence energy transfer of dipole-dipole coupling.

  6. Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Khaydarov, R. R.; Khaydarov, R. A.; Estrin, Y.; Evgrafova, S.; Scheper, T.; Endres, C.; Cho, S. Y.

    The bactericidal effect of silver nanoparticles obtained by a novel electrochemical method on Escherichia coli, Staphylococcus aureus, Aspergillus niger and Penicillium phoeniceum cultures has been studied. The tests conducted have demonstrated that synthesized silver nanoparticles — when added to water paints or cotton fabrics — show a pronounced antibacterial/antifungal effect. It was shown that smaller silver nanoparticles have a greater antibacterial/antifungal efficacy. The paper also provides a review of scientific literature with regard to recent developments in the field of toxicity of silver nanoparticles and its effect on environment and human health.

  7. Production of hydrogen sulphide containing gas from underground formations

    SciTech Connect

    Delude, S.G.; Luinstra, E.A.

    1988-12-06

    This patent describes a process for the production of at least a gaseous product containing a substantial amount of hydrogen sulphide via a bore-hole from an underground formation containing besides the hydrogen sulphide at least elemental sulphur, comprising (a) injection of a liquid substantially consisting of hydrocarbons into the bore-hole or into the underground formation near to the end of the bore-hole; (b) producing a gaseous and a liquid fraction from the underground formation; (c) separating the gaseous fraction from the liquid fraction (d) if necessary, separating an aqueous fraction of the produced liquid fraction from the hydrocarbons-containing fraction; (e) heating the hydrocarbons-containing fraction in order to remove elemental sulphur by conversion to hydrogen sulphide in the presence of a catalyst comprising sulphides of one of more metals from Group VIB and/or Group VIII of the Periodic Table of Elements deposited on a support of alumina, silica or silica alumina; and (f) reinjection of at least a part of the thus treated hydrocarbons-containing fraction into the bore-hole or into the underground formation near to the end of the bore-hole as described hereinbefore.

  8. COLORIMETRIC DETERMINATION OF HYDROGEN SULPHIDE AND METHANETHIOL IN INDUSTRIAL EFFLUENTS,

    DTIC Science & Technology

    designed for this purpose. The possibilities of determining methanethiol on the same sample have been investigated. The precision and accuracy were found...to be satisfactory for the hydrogen sulphide determination whereas results for methanethiol were less precise owing to certain interferences. (Author)

  9. Improved electric energy production of solar cell using small silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, X. Y.; Li, H. F.; Shi, S.; Wang, J. L.

    2017-03-01

    The influence of small Ag nanoparticles (NPs) on the all-day electric energy production of solar cells has been investigated. The small Ag NPs were deposited on the cell surface by the magnetron sputtering system. The cell without NPs is used as a reference cell. The external quantum efficiency (EQE) curves indicate that the performance of cell with 8% nanoparticle coverage is better than that of other cells in the long wavelength band. The maximum power-angle curves indicate that the small Ag NPs can effectively improve the all-day electric energy production of solar cell. Comparing with the values of reference cell, the half peak height of maximum power for cell optimized increases by 65%, and the half peak breadth of maximum power for cell optimized broadens by 3%. The enhancements of optimum operating current and optimum operating voltage lead directly to the enhancement of maximum power.

  10. Gold-silver-tellurium mineral assemblages in different ore styles of the Southern Urals VHMS deposits

    NASA Astrophysics Data System (ADS)

    Maslennikov, V. V.; Zaykov, V. V.; Maslennikova, S. P.; Tesalina, S. G.; Herrington, R. J.; Buschmann, B.; Becker, K.; Petersen, S.; Orgeval, J. J.; Leistel, M.

    2003-04-01

    VMS deposits of the South Urals generally show a continuum in degradation and reworking ranging from pristine steep-sided hydrothermal sulphide mounds to deposits dominated by layered strata of clastic sulphides. Four different deposits with varying degrees of degradation in order of increased reworking: (Yaman-Kasy longrightarrow Molodezhnoe longrightarrow Alexandrinskoe longrightarrow Balta-Tau) have been ranged. The influence of sulphide mound destruction and of sea-floor alteration on mineral assemblages was investigated In the pristine Yaman-Kasy sulphide mound gold and silver occur as altaite+tellurium+hessite-stuetzite+sylvanite and later galena+native gold+pyrite assemblages in chalcopyrite+isocubanite-rich linings of former chimney conduits. Chalcopyrite-dominated conduit fragments in clastic ore facies contain native tellurium+gold intergrowths. In the weakly reworked Molodezhnoe deposit gold-silver assemblages only occur in sea-floor altered clastic sulphides on the slope of massive sulphide mounds in bornite- and tennantite-rich ores in association with Cu-Ag sulfides such as jalpaite, mckinstryite, and stromeyerite and rare Au-Ag-tellurides (petzite). The Alexandrinskoe deposit is dominated by clastic ores and here native gold and rare hessite occur together with galena in tennantite-sphalerite-dominated veins of the footwall as well as in drusy sphalerite forming conduits of vent chimneys. An assemblage of electrum+galena+tennantite was observed in secondary chalcopyrite in the outer walls of chimneys. Native gold+stromeyerite are common in bornite-rich clastic sulphides while an assemblage of Ag-sulphosalts+electrum is common in barite-rich ores. In the reworked Balta-Tau deposit Ag-sulphosalts+electrum-kustelite occur often together with tennantite+galena+barite banded ores. Gold-silver-telluride mineralisation in these VMS deposits changes with degree of reworking from Au-tellurides, and native gold+galena+pyrite in pristine sulphide mounds to

  11. EPAs $2.48 million grant will support efforts to improve air quality, protect people, in Idahos West Silver Valley

    EPA Pesticide Factsheets

    (Seattle, WA - October 22, 2015) The Idaho Department of Environmental Quality has received a $2.48 million EPA grant to reduce pollution and protect air quality in northern Idaho's West Silver Valley. The grant is part of EPA's 2015 Targeted Air Shed Gran

  12. Monte Carlo simulation optimisation of zinc sulphide based fast-neutron detector for radiography using a 252Cf source

    NASA Astrophysics Data System (ADS)

    Meshkian, Mohsen

    2016-02-01

    Neutron radiography is rapidly extending as one of the methods for non-destructive screening of materials. There are various parameters to be studied for optimising imaging screens and image quality for different fast-neutron radiography systems. Herein, a Geant4 Monte Carlo simulation is employed to evaluate the response of a fast-neutron radiography system using a 252Cf neutron source. The neutron radiography system is comprised of a moderator as the neutron-to-proton converter with suspended silver-activated zinc sulphide (ZnS(Ag)) as the phosphor material. The neutron-induced protons deposit energy in the phosphor which consequently emits scintillation light. Further, radiographs are obtained by simulating the overall radiography system including source and sample. Two different standard samples are used to evaluate the quality of the radiographs.

  13. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  14. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  15. Production of activated carbon and its catalytic application for oxidation of hydrogen sulphide

    NASA Astrophysics Data System (ADS)

    Azargohar, Ramin

    Hydrogen sulphide is an environmentally hazardous gas which is present in many gas streams associated with oil and gas industry. Oxidation of H 2S to sulphur in air produces no bulky or waste material and requires no further purification. Activated carbon is known as a catalyst for this reaction. In this research, a coal-based precursor (luscar char) and a biomass-based precursor (biochar) were used for production of activated carbons by two common methods of activation: physical and chemical activation in which steam and potassium hydroxide (KOH), respectively, were used. Experiments were designed by the statistical central composite design method. Two models were developed for the BET surface area and reaction yield of each activation process. These models showed the effects of operating conditions, such as activation temperature, mass ratio of activating agent to precursor, activation time, and nitrogen flowrate on the BET surface area and reaction yield for each activation method for each precursor. The optimum operating conditions were calculated using these models to produce activated carbons with relatively large BET surface area (> 500 m2/g) and high reaction yield (> 50 wt %). The BET surface area and reaction yield for activated carbons produced at optimum operating conditions showed maximum 7 and 7.4% difference, respectively, comparing to the values predicted by models. The activated carbons produced at optimum operating conditions were used as the base catalysts for the direct oxidation of 1 mol % hydrogen sulphide in nitrogen to sulphur at the temperature range of 160-205°C and pressure of 700 kPa. Originally activated carbons showed a good potential for oxidation of hydrogen sulphide by their selectivity for sulphur product and low amount of sulphur dioxide production. To improve the performance of steam-activated carbons, the catalysts were modified by acid-treatment followed by thermal desorption. This method increased the break-through times for

  16. Glass frits coated with silver nanoparticles for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-01

    Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  17. Ni, Cu, Au, and platinum-group element contents of sulphides associated with intraplate magmatism: A synthesis

    USGS Publications Warehouse

    Barnes, S.-J.; Zientek, M.L.; Severson, M.J.

    1997-01-01

    The tectonic setting of intraplate magmas, typically a plume intersecting a rift, is ideal for the development of Ni - Cu - platinum-group element-bearing sulphides. The plume transports metal-rich magmas close to the mantle - crust boundary. The interaction of the rift and plume permits rapid transport of the magma into the crust, thus ensuring that no sulphides are lost from the magma en route to the crust. The rift may contain sediments which could provide the sulphur necessary to bring about sulphide saturation in the magmas. The plume provides large volumes of mafic magma; thus any sulphides that form can collect metals from a large volume of magma and consequently the sulphides will be metal rich. The large volume of magma provides sufficient heat to release large quantities of S from the crust, thus providing sufficient S to form a large sulphide deposit. The composition of the sulphides varies on a number of scales: (i) there is a variation between geographic areas, in which sulphides from the Noril'sk - Talnakh area are the richest in metals and those from the Muskox intrusion are poorest in metals; (ii) there is a variation between textural types of sulphides, in which disseminated sulphides are generally richer in metals than the associated massive and matrix sulphides; and (iii) the massive and matrix sulphides show a much wider range of compositions than the disseminated sulphides, and on the basis of their Ni/Cu ratio the massive and matrix sulphides can be divided into Cu rich and Fe rich. The Cu-rich sulphides are also enriched in Pt, Pd, and Au; in contrast, the Fe-rich sulphides are enriched in Fe, Os, Ir, Ru, and Rh. Nickel concentrations are similar in both. Differences in the composition between the sulphides from different areas may be attributed to a combination of differences in composition of the silicate magma from which the sulphides segregated and differences in the ratio of silicate to sulphide liquid (R factors). The higher metal

  18. A Pharmacological and Toxicological Profile of Silver as an Antimicrobial Agent in Medical Devices

    PubMed Central

    Lansdown, Alan B. G.

    2010-01-01

    Silver is used widely in wound dressings and medical devices as a broad-spectrum antibiotic. Metallic silver and most inorganic silver compounds ionise in moisture, body fluids, and secretions to release biologically active Ag+. The ion is absorbed into the systemic circulation from the diet and drinking water, by inhalation and through intraparenteral administration. Percutaneous absorption of Ag+ through intact or damaged skin is low. Ag+ binds strongly to metallothionein, albumins, and macroglobulins and is metabolised to all tissues other than the brain and the central nervous system. Silver sulphide or silver selenide precipitates, bound lysosomally in soft tissues, are inert and not associated with an irreversible toxic change. Argyria and argyrosis are the principle effects associated with heavy deposition of insoluble silver precipitates in the dermis and cornea/conjunctiva. Whilst these changes may be profoundly disfiguring and persistent, they are not associated with pathological damage in any tissue. The present paper discusses the mechanisms of absorption and metabolism of silver in the human body, presumed mechanisms of argyria and argyrosis, and the elimination of silver-protein complexes in the bile and urine. Minimum blood silver levels consistent with early signs of argyria or argyrosis are not known. Silver allergy does occur but the extent of the problem is not known. Reference values for silver exposure are discussed. PMID:21188244

  19. An investigation of iron sulphide dust minimum ignition temperatures.

    PubMed

    Amyotte, Paul R; Soundararajan, Ranganathan; Pegg, Michael J

    2003-02-28

    An investigation of the ignition behaviour of iron sulphide dusts has been undertaken. Commercial samples of FeS and FeS(2) and mine samples of pyrrhotite and pyrite were tested for minimum ignition temperature (MIT) using a device known as the BAM oven. The mine samples were found to undergo a decrease in MIT as the mass mean particle diameter became smaller. Using available theoretical treatments, this experimental observation was interpreted as providing further evidence of the importance of heterogeneous combustion in the ignition of iron sulphide dusts. A dense cloud state was proven for the experimental apparatus used, and an alternate criterion for the boundary between a dilute and a dense dust cloud was proposed in terms of the number of dust particles present in the cloud.

  20. Geological and geophysical characteristics of massive sulphide deposits: A case study of the Lirhanda massive sulphide deposit of Western Kenya

    NASA Astrophysics Data System (ADS)

    Dindi, E.; Maneno, J. B. J.

    2016-08-01

    An integrated geophysical ground survey was conducted on an airborne electromagnetic (EM) anomaly located in Kakamega forest of Western Kenya. The purpose of the study was to establish the existence of massive sulphides and identify suitable optimal geophysical method(s) for the investigation of similar anomalies. The study was also expected to provide information on the geological and geophysical characteristics of the deposit. Field work involved electromagnetic methods: Vertical Loop (VLEM), Horizontal Loop (HLEM), TURAM EM and potential field methods: gravity and magnetics. Geochemical sampling was carried out concurrently with the geophysical survey. All the geophysical methods used yielded good responses. Several conductors conforming to the strike of the geology were identified. TURAM EM provided a higher resolution of the conductors compared to VLEM and HLEM. The conductors were found to be associated with positive gravity anomalies supporting the presence of bodies of higher density than the horst rock. Only the western section (west of 625W) of the grid is associated with strong magnetic anomalies. East of 625W strong EM and gravity anomalies persist but magnetic anomalies are weak. This may reflect variation in the mineral composition of the conductors from magnetic to non-magnetic. Geochemical data indicates strong copper anomalies (upto 300 ppm) over sections of the grid and relatively strong zinc (upto 200 ppm) and lead (upto 100 ppm) anomalies. There is a positive correlation between the location of the conductors as predicted by TURAM EM and the copper and zinc anomalies. A test drill hole proposed on the basis of the geophysical results of this study struck massive sulphides at a depth of 30m still within the weathered rock zone. Unfortunately, the drilling was stopped before the sulphides could be penetrated. The drill core revealed massive sulphide rich in pyrite and pyrrhotite. An attempt has been made to compare characteristics of the Lirhanda

  1. A monobromobimane-based assay to measure the pharmacokinetic profile of reactive sulphide species in blood

    PubMed Central

    Wintner, Edward A; Deckwerth, Thomas L; Langston, William; Bengtsson, Asa; Leviten, Dina; Hill, Paul; Insko, Michael A; Dumpit, Ronald; VandenEkart, Emily; Toombs, Christopher F; Szabo, Csaba

    2010-01-01

    Background and purpose: Hydrogen sulphide (H2S) is a labile, endogenous metabolite of cysteine, with multiple biological roles. The development of sulphide-based therapies for human diseases will benefit from a reliable method of quantifying H2S in blood and tissues. Experimental approach: Concentrations of reactive sulphide in saline and freshly drawn whole blood were quantified by reaction with the thio-specific derivatization agent monobromobimane, followed by reversed-phase fluorescence HPLC and/or mass spectrometry. In pharmacokinetic studies, male rats were exposed either to intravenous infusions of sodium sulphide or to H2S gas inhalation, and levels of available blood sulphide were measured. Levels of dissolved H2S/HS- were concomitantly measured using an amperometric sensor. Key results: Monobromobimane was found to rapidly and quantitatively derivatize sulphide in saline or whole blood to yield the stable small molecule sulphide dibimane. Extraction and quantification of this bis-bimane derivative were validated via reversed-phase HPLC separation coupled to fluorescence detection, and also by mass spectrometry. Baseline levels of sulphide in blood were in the range of 0.4–0.9 µM. Intravenous administration of sodium sulphide solution (2–20 mg·kg−1·h−1) or inhalation of H2S gas (50–400 ppm) elevated reactive sulphide in blood in a dose-dependent manner. Each 1 mg·kg−1·h−1 of sodium sulphide infusion into rats was found to be pharmacokinetically equivalent to approximately 30 ppm of H2S gas inhalation. Conclusions and implications: The monobromobimane derivatization method is a sensitive and reliable means to measure reactive sulphide species in whole blood. Using this method, we have established a bioequivalence between infused sodium sulphide and inhaled H2S gas. PMID:20590590

  2. Sulphidation of the oceanic lithosphere: an experimental approach

    NASA Astrophysics Data System (ADS)

    Los, Catharina; Hansen, Christian; Bach, Wolfgang

    2017-04-01

    Newly formed oceanic lithosphere close to spreading centers can be influenced by fluids that feed hydrothermal vents. These fluids often carry high amounts of dissolved gases such as H2S, which can trigger precipitation of sulphide minerals in the interacting rock during percolation. This process occurs equally in exposed mantle rock, serpentinised mantle rock, troctolite or gabbro and basalt, the lithology depending on the spreading rate at the ridge where hydrothermal activity is present. These later-stage fluid-rock interactions can develop different types of sulphide mineralization in the lithosphere. In order to better understand these sulphidation reactions, we have conducted several batch experiments that placed different oceanic lithologies in contact with an H2S saturated, iron-free solution. The mixture was heated to 250°C at 400 bars and kept under these conditions for 2-8 weeks. In situ fluid and gas sampling was used to monitor reaction progress. REM-analysis of the solid products has shown the growth of euhedral pyrite and magnetite crystals as well as dissolution textures in feldspar and olivine. The presence of pyrite (gabbro experiment) and magnetite (troctolite and serpentinite) is in agreement with the measured H2- and H2S-content in the analysed fluids. These Fe-bearing minerals grew although no iron was added to the fluid, showing the replacive nature of the reaction. Geochemical modeling can be used to extend the application of these observations to different PT-conditions. Using this technique, we can start tackling the problem of replacive sulphide formation within hydrothermal discharge zones in oceanic basement of variable composition.

  3. Russell-Silver syndrome

    MedlinePlus

    Silver-Russell syndrome; Silver syndrome; RSS; Russell-Silver syndrome ... Organization for Rare Disorders -- rarediseases.org/rare-diseases/russell-silver-syndrome NIH/NLM Genetics Home Reference -- ghr. ...

  4. Semiconducting properties of layered cadmium sulphide-based hybrid nanocomposites

    PubMed Central

    2011-01-01

    A series of hybrid cadmium salt/cationic surfactant layered nanocomposites containing different concentrations of cadmium sulphide was prepared by exchanging chloride by sulphide ions in the layered precursor CdXx(OH)y(CnTA)z in a solid phase/gas reaction, resulting in a series of layered species exhibiting stoichiometries corresponding to CdSvXx(OH)y(CnTA)z, constituted by two-dimensional CdCl2/CdS ultra-thin sheets sandwiched between two self-assembled surfactant layers. The electronic structure of CdS in the nanocomposite is similar to that of bulk, but showing the expected features of two-dimensional confinement of the semiconductor. The nanocomposite band gap is found to depend in a non-linear manner on both the length of the hydrocarbon chain of the surfactant and the concentration of the sulphide in the inorganic sheet. The products show photocatalytic activity at least similar and usually better than that of "bulk" CdS in a factor of two. PMID:21896162

  5. Semiconducting properties of layered cadmium sulphide-based hybrid nanocomposites

    NASA Astrophysics Data System (ADS)

    López-Cabaña, Zoraya; Marfa Sotomayor Torres, Clivia; González, Guillermo

    2011-09-01

    A series of hybrid cadmium salt/cationic surfactant layered nanocomposites containing different concentrations of cadmium sulphide was prepared by exchanging chloride by sulphide ions in the layered precursor CdX x (OH) y (CnTA) z in a solid phase/gas reaction, resulting in a series of layered species exhibiting stoichiometries corresponding to CdS v X x (OH) y (CnTA) z , constituted by two-dimensional CdCl2/CdS ultra-thin sheets sandwiched between two self-assembled surfactant layers. The electronic structure of CdS in the nanocomposite is similar to that of bulk, but showing the expected features of two-dimensional confinement of the semiconductor. The nanocomposite band gap is found to depend in a non-linear manner on both the length of the hydrocarbon chain of the surfactant and the concentration of the sulphide in the inorganic sheet. The products show photocatalytic activity at least similar and usually better than that of "bulk" CdS in a factor of two.

  6. Improvements in the realization of the ITS-90 over the temperature range from the melting point of gallium to the freezing point of silver at NIM

    SciTech Connect

    Sun, J.; Zhang, J. T.; Ping, Q.

    2013-09-11

    The temperature primary standard over the range from the melting point of gallium to the freezing point of silver in National institute of Metrology (NIM), China, was established in the early 1990s. The performance of all of fixed-point furnaces degraded and needs to be updated due to many years of use. Nowadays, the satisfactory fixed point materials can be available with the development of the modern purification techniques. NIM plans to use a group of three cells for each defining fixed point temperature. In this way the eventual drift of individual cells can be evidenced by periodic intercomparison and this will increase the reliability in disseminating the ITS-90 in China. This article describes the recent improvements in realization of ITS-90 over temperature range from the melting point of gallium to the freezing point of silver at NIM. Taking advantages of the technological advances in the design and manufacture of furnaces, the new three-zone furnaces and the open-type fixed points were developed from the freezing point of indium to the freezing point of silver, and a furnace with the three-zone semiconductor cooling was designed to automatically realize the melting point of gallium. The reproducibility of the new melting point of gallium and the new open-type freezing points of In, Sn, Zn. Al and Ag is improved, especially the freezing points of Al and Ag with the reproducibility of 0.2mK and 0.5mK respectively. The expanded uncertainty in the realization of these defining fixed point temperatures is 0.34mK, 0.44mK, 0.54mK, 0.60mK, 1.30mK and 1.88mK respectively.

  7. Improvements in the realization of the ITS-90 over the temperature range from the melting point of gallium to the freezing point of silver at NIM

    NASA Astrophysics Data System (ADS)

    Sun, J.; Zhang, J. T.; Ping, Q.

    2013-09-01

    The temperature primary standard over the range from the melting point of gallium to the freezing point of silver in National institute of Metrology (NIM), China, was established in the early 1990s. The performance of all of fixed-point furnaces degraded and needs to be updated due to many years of use. Nowadays, the satisfactory fixed point materials can be available with the development of the modern purification techniques. NIM plans to use a group of three cells for each defining fixed point temperature. In this way the eventual drift of individual cells can be evidenced by periodic intercomparison and this will increase the reliability in disseminating the ITS-90 in China. This article describes the recent improvements in realization of ITS-90 over temperature range from the melting point of gallium to the freezing point of silver at NIM. Taking advantages of the technological advances in the design and manufacture of furnaces, the new three-zone furnaces and the open-type fixed points were developed from the freezing point of indium to the freezing point of silver, and a furnace with the three-zone semiconductor cooling was designed to automatically realize the melting point of gallium. The reproducibility of the new melting point of gallium and the new open-type freezing points of In, Sn, Zn. Al and Ag is improved, especially the freezing points of Al and Ag with the reproducibility of 0.2mK and 0.5mK respectively. The expanded uncertainty in the realization of these defining fixed point temperatures is 0.34mK, 0.44mK, 0.54mK, 0.60mK, 1.30mK and 1.88mK respectively.

  8. Effects of sulphate addition and sulphide inhibition on microbial fuel cells.

    PubMed

    Ieropoulos, I; Gálvez, A; Greenman, J

    2013-01-10

    The effects of adding sulphate in: (i) standard activated sludge microbial fuel cells (MFCs) and (ii) larger-scale leachate-treating columns - both as individual units and as a system connected in cascade - are reported. S-replete power output was ∼2-fold higher than that of the S-deplete MFC. Furthermore, the effects of evolved sulphide (S(2-)) inhibition were investigated. The overall decrease in power output from the sulphide inhibitor (Na(2)MoO(4)) additions was 83% for the S-replete and 90% for the S-deplete. The second phase with the leachate treating units shows an improvement of 32-86% (depended on leachate strength) in current output as a result of adding sulphate. When leachate column MFCs were connected fluidically in series, the amount of Na(2)SO(4) made available downstream was decreasing (increase in power was 99%, 40% and 12% for columns in cascade). Results demonstrated the beneficial effects of added sulphur sources to both activated sludge and leachate-treating MFCs. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Flavour sulphides are produced from methionine by two different pathways by Geotrichum candidum.

    PubMed

    Demarigny, Y; Berger, C; Desmasures, N; Gueguen, M; Spinnler, H E

    2000-08-01

    We have investigated the capacities of Geotrichum candidum strains to produce sulphides from methionine. This attribute is very important in cheese technology because of the flavouring potential of sulphur compounds. A spectrophotometric procedure using 5,5'-dithiobis(2-nitrobenzoic acid) to determine sulphides was tested on a collection of G. candidum strains, and confirmed by gas chromatography-mass spectrometry. The strains were distinguished on the basis of their ability to produce methanethiol. Gas chromatography-mass spectrometry also made it possible to identify other sulphides, such as dimethyl disulphide, dimethyl trisulphide and dimethyl sulphide. Using sonicated cells, the specific production of these four sulphides was studied in presence of L-[S-methyl-2H]methionine. Both methanethiol and dimethyl sulphide were produced from methionine, but two different pathways were used by G. candidum.

  10. Hydrogen sulphide removal from corroding concrete: comparison between surface removal rates and biomass activity.

    PubMed

    Jensen, H S; Nielsen, A H; Lens, P N L; Hvitved-Jacobsen, T; Vollertsen, J

    2009-11-01

    Corrosion of concrete sewer pipes caused by hydrogen sulphide is a problem in many sewer networks. The mechanisms of production and fate of hydrogen sulphide in the sewer biofilms and wastewater as well as its release to the sewer atmosphere are largely understood. In contrast, the mechanisms of the uptake of hydrogen sulphide on the concrete surfaces and subsequent concrete corrosion are basically unknown. To shed light on these mechanisms, the uptake of hydrogen sulphide from a sewer gas phase was compared to the biological hydrogen sulphide removal potential of the concrete corrosion products. The results showed that both microbial degradation at and sorption to the concrete surfaces were important for the uptake of hydrogen sulphide on the concrete surfaces.

  11. Native fungi as metal remediators: Silver myco-accumulation from metal contaminated waste-rock dumps (Libiola Mine, Italy).

    PubMed

    Cecchi, Grazia; Marescotti, Pietro; Di Piazza, Simone; Zotti, Mirca

    2017-03-04

    Metal contamination constitutes a major source of pollution globally. Many recent studies emphasized the need to develop cheap and green technologies for the remediation or reclamation of environmental matrices contaminated by heavy metals. In this context, fungi are versatile organisms that can be exploited for bioremediation activities. In our work, we tested silver (Ag) bioaccumulation capabilities of three microfungal strains (Aspergillus alliaceus Thom & Church, Trichoderma harzianum Rifai, Clonostachys rosea (Link) Schroers, Samuels, Seifert & W. Gams) isolated from a silver polluted site. The aim was to select silver tolerant native strains and test their potential silver uptake. Among the three species tested, T. harzianum was the most efficient strain to tolerate and accumulate silver, showing an uptake capability of 153 mg L(-1) taken at the Ag concentration of 330 mg L(-1). Our study highlights the potential use of native microfungi spontaneously growing in sulphide-rich waste rock dumps, for silver bioaccumulation and bioremediation.

  12. Production of hydrogen sulphide in milkfat-coated microcapsules containing Brevibacterium linens and cysteine.

    PubMed

    Kim, S C; Olson, N F

    1989-01-01

    Milkfat-coated microcapsules containing Brevibacterium linens and cysteine were used to produce hydrogen sulphide, one of Cheddar cheese flavour compounds. Hydrogen sulphide production was substantially reduced and delayed in the encapsulated system as compared with that of the unencapsulated system. Hydrogen sulphide was not produced aerobically whereas substantial amounts of hydrogen sulphide were produced in a nitrogen purged system. The inhibitory effect of the initial aerobic condition disappeared after 8 days of incubation. In spite of the lag in hydrogen sulphide production under aerobic conditions almost the same amount of hydrogen sulphide was produced in oxygen purged samples as in the nitrogen purged samples after 10 days of incubation. Moderate heat treatment (2 min at 58 degrees C) of cell suspension-milkfat-emulsion increased subsequent hydrogen sulphide production. The optimum pH and temperature for hydrogen sulphide production from cysteine by Brevibacterium linens were 6 degrees C and 32 degrees C, respectively. Antioxidants BHT, BHA and ascorbic acid had negligible effects on production of hydrogen sulphide in the encapsulated system.

  13. Effect of nano silver and silver nitrate on seed yield of (Ocimum basilicum L.)

    PubMed Central

    2014-01-01

    Background The aim of this study was to evaluate the effect of nano silver and silver nitrate on yield of seed in basil plant. The study was carried out in a randomized block design with three replications. Results Four levels of either silver nitrate (0, 100, 200 and 300 ppm) or nano silver (0, 20, 40, and 60 ppm) were sprayed on basil plant at seed growth stage. The results showed that there was no significant difference between 100 ppm of silver nitrate and 60 ppm concentration of nano silver on the shoot silver concentration. However, increasing the concentration of silver nitrate from 100 to 300 ppm caused a decrease in seed yield. In contrast, a raise in the concentration of nano silver from 20 to 60 ppm has led to an improvement in the seed yield. Additionally, the lowest amount of seed yield was found with control plants. Conclusions Finally, with increasing level of silver nitrate, the polyphenol compound content was raised but the enhancing level of nano silver resulting in the reduction of these components. In conclusion, nano silver can be used instead of other compounds of silver. PMID:25383311

  14. Antibacterial Silver

    PubMed Central

    Clement, Julia L.; Jarrett, Penelope S.

    1994-01-01

    The antibacterial activity of silver has long been known and has found a variety of applications because its toxicity to human cells is considerably lower than to bacteria. The most widely documented uses are prophylactic treatment of burns and water disinfection. However, the mechanisms by which silver kills cells are not known. Information on resistance mechanisms is apparently contradictory and even the chemistry of Ag+ in such systems is poorly understood. Silver binds to many cellular components, with membrane components probably being more important than nucleic acids. It is difficult to know whether strong binding reflects toxicity or detoxification: some sensitive bacterial strains have been reported as accumulating more silver than the corresponding resistant strain, in others the reverse apparently occurs. In several cases resistance has been shown to be plasmid mediated. The plasmids are reported as difficult to transfer, and can also be difficult to maintain, as we too have found. Attempts to find biochemical differences between resistant and sensitive strains have met with limited success: differences are subtle, such as increased cell surface hydrophobicity in a resistant Escherichia coli. Some of the problems are due to defining conditions in which resistance can be observed. Silver(I) has been shown to bind to components of cell culture media, and the presence of chloride is necessary to demonstrate resistance. The form of silver used must also be considered. This is usually water soluble AgNO3, which readily precipitates as AgCl. The clinically preferred compound is the highly insoluble silver sulfadiazine, which does not cause hypochloraemia in burns. It has been suggested that resistant bacteria are those unable to bind Ag+ more tightly than does chloride. It may be that certain forms of insoluble silver are taken up by cells, as has been found for nickel. Under our experimental conditions, silver complexed by certain ligands is more cytotoxic

  15. Antibacterial silver.

    PubMed

    Clement, J L; Jarrett, P S

    1994-01-01

    The antibacterial activity of silver has long been known and has found a variety of applications because its toxicity to human cells is considerably lower than to bacteria. The most widely documented uses are prophylactic treatment of burns and water disinfection. However, the mechanisms by which silver kills cells are not known. Information on resistance mechanisms is apparently contradictory and even the chemistry of Ag(+) in such systems is poorly understood.Silver binds to many cellular components, with membrane components probably being more important than nucleic acids. It is difficult to know whether strong binding reflects toxicity or detoxification: some sensitive bacterial strains have been reported as accumulating more silver than the corresponding resistant strain, in others the reverse apparently occurs. In several cases resistance has been shown to be plasmid mediated. The plasmids are reported as difficult to transfer, and can also be difficult to maintain, as we too have found. Attempts to find biochemical differences between resistant and sensitive strains have met with limited success: differences are subtle, such as increased cell surface hydrophobicity in a resistant Escherichia coli.Some of the problems are due to defining conditions in which resistance can be observed. Silver(I) has been shown to bind to components of cell culture media, and the presence of chloride is necessary to demonstrate resistance. The form of silver used must also be considered. This is usually water soluble AgNO(3), which readily precipitates as AgCl. The clinically preferred compound is the highly insoluble silver sulfadiazine, which does not cause hypochloraemia in burns. It has been suggested that resistant bacteria are those unable to bind Ag(+) more tightly than does chloride. It may be that certain forms of insoluble silver are taken up by cells, as has been found for nickel. Under our experimental conditions, silver complexed by certain ligands is more

  16. Adsorption studies of Cr(III) and Cr(VI) on lead sulphide, copper sulphide and zinc sulphide - determination Cr(III) in the presence of Cr(VI)

    SciTech Connect

    Sarwar, M.; Masood, M.K.; Farooq, S. )

    1990-01-01

    The adsorption studies of Cr(VI) in presence of Cr(III) on the sulphide of Lead, Zinc and Copper has been studied. It has been found that in case of lead sulphide 100% adsorption of Cr(VI) took place at pH 4.0 and of Cr(III) at pH 7.0. While in case of zinc sulphide and 100% adsorption of Cr(VI) took place at pH 4.5 and of Cr(III) at pH 6.5. In case of copper sulphide 100% adsorption of Cr(VI) took place at pH 5.0 and of Cr(III) at pH 7.0. This difference in adsorption at different pH values forms the basis for the determination of these ions. The method is accurate.

  17. Fusion bonding of carbon fabric reinforced polyphenylene sulphide

    NASA Astrophysics Data System (ADS)

    de Baere, I.; van Paepegem, W.; Degrieck, J.

    2010-06-01

    In recent years, there is a growing interest in joining techniques for thermoplastic composites as an alternative to adhesive bonding. In this manuscript, a fusion bonding process called hot-tool welding is investigated for this purpose and the used material is a carbon fabric reinforced polyphenylene sulphide. The quality of the welds is experimentally assessed using a short three-point bending setup, which has an interesting distribution of interlaminar shear stresses. It can be concluded that although the hot-tool welding process shows high short-beam strengths, it has some drawbacks. Therefore, a design of an infrared welding setup is presented.

  18. Raghunathpura: An early crystallised IIAB iron with sulphide micro nodules

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Ray, D.; Murty, S. V. S.

    2016-11-01

    We present a set of new data on microtextures, mineral composition, bulk composition and microhardness (Hv) of kamacite, phosphide and sulphide in Raghunathpura IIAB iron (structurally hexahedrite). Based on textural studies, we find Raghunathpura comprises of a single kamacite grain studded with exsolved inclusions of tiny schreibersites and trapped melt inclusions of troilite often superposed with numerous sets of Neumann lines. Compositional data further suggest that Raghunathpura is an early crystallised IIAB iron with low Ni, low P, low S and high Ir. Metallographic cooling rate of 7 °C/Ma has been estimated from phosphide composition-size relationship of this rare group of iron.

  19. Ternary cadmium zinc sulphide films with high charge mobilities

    NASA Astrophysics Data System (ADS)

    Ampong, Francis K.; Awudza, Johannes A. M.; Nkum, R. K.; Boakye, F.; Thomas, P. John; O'Brien, Paul

    2015-02-01

    Cadmium zinc sulphide thin films with high charge mobilities are obtained from acidic chemical baths employing the corresponding metal chlorides, urea and thioacetamide. The films are characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, inductively coupled plasma mass spectrometry, absorption spectroscopy and charge transport measurements. The compositional control afforded by the technique and the resultant changes in the structural, optical and electronic properties of the films are critically examined. We find good correlation between structure and properties at extremes of the composition range.

  20. New calibration standard for LA-ICPMS analysis of sulphides

    NASA Astrophysics Data System (ADS)

    Belousov, I.; Danyushevsky, L. V.; Olin, P. H.; Gilbert, S.; Thompson, J. M.

    2014-12-01

    Currently available calibration standards for LA-ICPMS analysis for a wide range of trace elements in sulphide minerals include hydrothermally-precipitated Fe-Cu-Zn-S powder doped with trace metals MASS-1 [1] and Li borate glass STDGL-2 [2]. Both of them are not ideal due to a limited range of elements they contain and/or non-homogenous distribution and low concentrations of elements. MASS-1 suffers from a limited range of elements and poor homogeneity, whereas STDGL-2 has low and/or unevenly distributed volatile elements and precious metals (e.g. Se, Te, Tl, Pt, Au). In order to produce a better calibration standard, we have experimented with fusing sulphide mineral mixes in a variety of borate-based fluxes. A range of flux compositions, heating and cooling regimes and times at high temperatures have been tested in order to produce a homogeneous glass disk with an appropriate proportion of sulphide, while retaining volatile elements. Best results were achieved with using Li tetraborate as a flux with Na nitrate as an oxidizing agent by fusing with an LPG fluxer (M4 by Claisse). Selenium, tellurium and tin were added in the elemental form, whereas thallium was added as carbonate (Tl2CO3). A range of elements was added to provide capability for detecting known common interferences on chalcophile and siderophile elements (e.g. Gd, Hf, Ta, W, Zr, Sr). New standard glass STDGL-3 contains homogeneously distributed volatile elements (Se, Te, Tl, Sn) and precious metals (Au, Pt). A larger proportion of volatile elements was retained (100% Ge, 80% Re, 70% Te, 60% Sn, 20% Tl, 20% Se). Most problematic elements turned out to be Se and Tl, which volatilize together through a network of narrow zones, and Pt and Au, which form micro inclusions. Suitability of the new standard for LA-ICPMS analysis of sulphide minerals for trace element concentrations and Pb isotopes will be demonstrated. [1] Wilson et al., 2002. JAAS, v.17, pp.406-409[2] Danyushevsky et al., 2011. GEEA,. v.11

  1. Structural and optical properties of Tin sulphide thin films

    SciTech Connect

    Akkari, A.; Ben Nasr, T.; Kamoun, N.

    2007-09-19

    Tin sulphide SnS thin films were deposited on glass substrates using the chemical bath deposition technique (CBD). By investigating the influence of triethanolamine (TEA) concentration on the properties of deposited films, we obtained the optimum deposition parameter. These films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) analysis and spectrophotometric measurements. The obtained thin films exhibit the orthorhombic structure and the direct band gap energy is found to be about 1.65 eV, for films prepared at TEA concentration films equal to 13.5 M.

  2. Synthesis and characterization of copper antimony tin sulphide thin films for solar cell applications

    NASA Astrophysics Data System (ADS)

    Ali, N.; Hussain, A.; Ahmed, R.; Wan Shamsuri, W. N.; Fu, Y. Q.

    2016-12-01

    Low price thin film modules based on Copper antimony tin sulphide (CATS) are introduced for solar harvesting to compete for the already developed compound semiconductors. Here, CATS thin films were deposited on soda lime glass by thermal evaporation technique followed by a rapid thermal annealing in an argon atmosphere. From Our XRD analysis, it was revealed that the annealed samples were poly-crystalline and their crystallinity was improved with increasing annealing temperature. The constituent elements and their corresponding chemical states were identified using X-ray photoelectron spectroscopy. The obtained optical band gap of 1.4 eV for CATS thin film is found nearly equal to GaAs - one of the highly efficient thin film material for solar cell technology. Furthermore, our observed good optical absorbance and low transmittance for the annealed CATS thin films in the visible region of light spectrum assured the aptness of the CATS thin films for solar cell applications.

  3. A colorimetric and ratiometric fluorescent probe for the imaging of endogenous hydrogen sulphide in living cells and sulphide determination in mouse hippocampus.

    PubMed

    Zhang, Ling; Li, Sai; Hong, Mei; Xu, Yuqing; Wang, Shuaishuai; Liu, Yi; Qian, Yong; Zhao, Jing

    2014-07-28

    A naphthalimide-azide based colorimetric and ratiometric fluorescent probe, NAP-1, has been developed for the selective and sensitive detection of hydrogen sulphide. Advantages of the probe NAP-1 include a low detection limit (110 nM), good selectivity, high sensitivity and excellent photostability. A linear relationship between the emission intensity ratios and sulphide concentrations was observed in PBS buffer and bovine serum, respectively. Our probe facilitates ratiometric determination and imaging of endogenous H2S in living cells. Furthermore, this probe was successfully applied to the measurement of endogenous sulphide in human plasma and mouse hippocampus. A significant reduction in sulphide levels and CBS mRNA expression was observed in the hippocampus of mouse models of lipopolysaccharide-induced neuroinflammation-related diseases, suggesting that decreased levels of endogenous H2S might be involved in the pathogenesis of neuroinflammation-related neurodegenerative diseases.

  4. Silver cyanide

    Integrated Risk Information System (IRIS)

    Silver cyanide ; CASRN 506 - 64 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  5. Precipitation of dissolved sulphide in pulp and paper mill wastewater by electrocoagulation.

    PubMed

    Vepsäläinen, Mikko; Selin, Jukka; Rantala, Pekka; Pulliainen, Martti; Särkkä, Heikki; Kuhmonen, Kaisa; Bhatnagar, Amit; Sillanpää, Mika

    2011-01-01

    The precipitation of dissolved sulphide ions by electrocoagulation was studied at laboratory scale using pulp and paper mill wastewaters. Concentrations of dissolved organic carbon and phosphorus were analysed before and after the electrocoagulation process to examine the suitability of the process for treatment of sulphide odour from pulp and paper mill wastewater. The electrochemical cell used in this study was constructed from monopolar dissolving iron electrodes. The dissolved iron concentration was directly proportional to the applied electric charge (C/L) at the tested current densities. Electrochemically produced ferrous iron (Fe2+) precipitated dissolved sulphide ions efficiently. Electricity consumption of the treatment was 4-8 C/mg S(2-) while iron consumption was 1.1-2.2 mg/mg S(2-) during the initial phase of the sulphide precipitation when the applied electric charge was 10-60 C/L. When 60 C/L was applied, 88% of dissolved sulphides and 40% of phosphorus was precipitated. The reduction in DOC was low during the sulphide precipitation. According to these results, electrocoagulation can precipitate dissolved sulphides effectively and thereby reduce sulphide odours of pulp and paper mill wastewaters.

  6. Hydrogen sulphide in cardiovascular system: A cascade from interaction between sulphur atoms and signalling molecules.

    PubMed

    Wang, Ming-Jie; Cai, Wen-Jie; Zhu, Yi-Chun

    2016-05-15

    As a gasotransmitter, hydrogen sulphide exerts its extensive physiological and pathophysiological effects in mammals. The interaction between sulphur atoms and signalling molecules forms a cascade that modulates cellular functions and homeostasis. In this review, we focus on the signalling mechanism underlying the effect of hydrogen sulphide in the cardiovascular system and metabolism as well as the biological relevance to human diseases.

  7. Global warming enhances sulphide stress in a key seagrass species (NW Mediterranean).

    PubMed

    García, Rosa; Holmer, Marianne; Duarte, Carlos M; Marbà, Núria

    2013-12-01

    The build-up of sulphide concentrations in sediments, resulting from high inputs of organic matter and the mineralization through sulphate reduction, can be lethal to the benthos. Sulphate reduction is temperature dependent, thus global warming may contribute to even higher sulphide concentrations and benthos mortality. The seagrass Posidonia oceanica is very sensitive to sulphide stress. Hence, if concentrations build up with global warming, this key Mediterranean species could be seriously endangered. An 8-year monitoring of daily seawater temperature, the sulphur isotopic signatures of water (δ(34)S(water)), sediment (δ(34)SCRS ) and P. oceanica leaf tissue (δ(34)S(leaves)), along with total sulphur in leaves (TS(leaves)) and annual net population growth along the coast of the Balearic archipelago (Western Mediterranean) allowed us to determine if warming triggers P. oceanica sulphide stress and constrains seagrass survival. From the isotopic S signatures, we estimated sulphide intrusion into the leaves (F(sulphide)) and sulphur incorporation into the leaves from sedimentary sulphides (SS(leaves)). We observed lower δ(34)S(leaves), higher F(sulphide) and SS(leaves) coinciding with a 6-year period when two heat waves were recorded. Warming triggered sulphide stress as evidenced by the negative temperature dependence of δ(34)S(leaves) and the positive one of F(sulphide), TS(leaves) and SS(leaves). Lower P. oceanica net population growth rates were directly related to higher contents of TS(leaves). At equivalent annual maximum sea surface water temperature (SST(max)), deep meadows were less affected by sulphide intrusion than shallow ones. Thus, water depth acts as a protecting mechanism against sulphide intrusion. However, water depth would be insufficient to buffer seagrass sulphide stress triggered by Mediterranean seawater summer temperatures projected for the end of the 21st century even under scenarios of moderate greenhouse gas emissions, A1B

  8. Chalcophile element partitioning into magmatic sulphides: the effect of silicate melt composition

    NASA Astrophysics Data System (ADS)

    Kiseeva, Kate; Wood, Bernard

    2016-04-01

    Partitioning of many elements between sulphide and silicate melts is a function of the FeO content of the silicate liquid (Kiseeva and Wood, 2013). The theoretical relationship is a linear one between LogDM (DM=[M]sulph/[M]sil) and -log[FeO] with a slope of n/2, where n is the valency of trace element M. In practice we find that the slope deviates from the theoretical one because of the presence of oxygen in the sulphide. In our recent study we investigated the effects of sulphide composition and temperature on chalcophile element partitioning between sulphide and silicate liquids (Kiseeva and Wood, 2015). We have concluded that partitioning of most chalcophile elements is a strong function of the oxygen (or FeO) content of the sulphide. As expected, lithophile elements partition more strongly into sulphide as its oxygen content increases, while chalcophile elements enter sulphide less readily with increasing oxygen. The effect of Ni and Cu content of sulphide is significantly smaller than the effect of oxygen, while the effects of temperature are large only for a number of elements (such as Ni, Cu, Ag). In this study we show that in addition to the effect of sulphide composition, for certain elements the effect of silicate melt composition on sulphide/silicate partitioning can be quite large. For instance, within the range of NBO/T between 0.5 and 2 the DTlsulph/sil changes in order of magnitude. For the elements, like Pb, partition coefficient does not seem to change much with the silicate melt composition, while for Sb the effect of the silicate melt composition on D is a factor of 3. Partitioning of chalcophile elements into more evolved, alkali-rich and felsic magmas is estimated to be very different from the partitioning into basaltic melts, mainly due to the strong effects of temperature and alkali components. Although it is highly likely that sulphide is in solid form at liquidus temperatures for dacite and rhyolite and thus the partitioning of chalcophile

  9. Porous silicon-based direct hydrogen sulphide fuel cells.

    PubMed

    Dzhafarov, T D; Yuksel, S Aydin

    2011-10-01

    In this paper, the use of Au/porous silicon/Silicon Schottky type structure, as a direct hydrogen sulphide fuel cell is demonstrated. The porous silicon filled with hydrochlorid acid was developed as a proton conduction membrane. The Au/Porous Silicon/Silicon cells were fabricated by first creating the porous silicon layer in single-crystalline Si using the anodic etching under illumination and then deposition Au catalyst layer onto the porous silicon. Using 80 mM H2S solution as fuel the open circuit voltage of 0.4 V was obtained and maximum power density of 30 W/m2 at room temperature was achieved. These results demonstrate that the Au/Porous Silicon/Silicon direct hydrogen sulphide fuel cell which uses H2S:dH2O solution as fuel and operates at room temperature can be considered as the most promising type of low cost fuel cell for small power-supply units.

  10. Antimony sulphide, an absorber layer for solar cell application

    NASA Astrophysics Data System (ADS)

    Ali, N.; Hussain, Arshad; Ahmed, R.; Shamsuri, W. N. Wan; Shaari, A.; Ahmad, N.; Abbas, S. M.

    2016-01-01

    Replacement of the toxic, expensive and scarce materials with nontoxic, cheap and earth-abundant one, in solar cell absorber layer, is immensely needed to realize the vision of green and sustainable energy. Two-micrometre-thin antimony sulphide film is considered to be adequate as an absorbing layer in solar cell applications. In this paper, we synthesize antimony sulphide thin films on glass substrate by physical vapour deposition technique, and the obtained films were then annealed at different temperatures (150-250 °C). The as-deposited and annealed samples were investigated for structural and optoelectronic properties using different characterization techniques. The X-ray diffraction analysis showed that the annealed samples were polycrystalline with Sb2S3 phase, while the as-deposited sample was amorphous in nature. The optical properties are measured via optical ellipsometric techniques. The measured absorbance of the film is adequately high, and every photon is found to be absorbed in visible and NIR range. The conductivity type of the films measured by hot-point probe technique is determined to be p-type. The optical band gap of the resulted samples was in the range (2.4-1.3 eV) for the as-deposited and annealed films.

  11. Direct molecular hydrogen sulphide scrubbing with hollowfibre membranes.

    PubMed

    Boucif, N; Jefferson, B; Parsons-, S A; Judd, S J; Stuetz, R M

    2001-01-01

    The emission of hydrogen sulphide is a major problem associated with anaerobic treatment of sulphate and sulphite containing wastewaters. Conventional absorbing processes, such as packed towers, spray towers or bubble columns, are all constrained by factors such as flooding and foaming. Membrane systems, on the other hand, enable independent control of the liquid and gas flow rate and a step change order of magnitude increase in the specific surface area of the contact process. The membrane acts as a gas absorber with a design similar to a shell and tube heat exchanger. On the other hand, they are limited by facets of the membrane such as its resistance to mass transfer and permselectivity, as well as its cost. The work presented in this paper refers to an absorption process based on a non-wetted hollow fibre membrane for the scrubbing of hydrogen sulphide from air, with water as the contact solvent. Results presented describe the performance of the unit in terms of overall transfer and outlet liquid concentration as a function of circulation regime, gas flow rate, liquid flow rate and specific surface area. In particular, results are presented using traditional plots of Sherwood number (Sh) against Graetz (Gr) number for the liquid flowing in the lumens, such that experimental and available empirical descriptions of the process performance are directly compared. Results suggest that, as expected, very efficient mass transfer is obtained. However, the mass transfer was found to reach a maximum value against Gr, contrary to available empirical models.

  12. Acid volatile sulphide as an indicator for sediment toxicity?

    SciTech Connect

    Goyvaerts, M.P.; Brucker, N. De; Geuzens, P.

    1995-12-31

    The ratio SEM (Simultaneously Extracted Metals) to AVS (Acid Volatile Sulfide) is considered to be a measure for heavy metal bioavailability for benthic species. When the SEM/AVS ratio exceeds 1 heavy metal toxicity for the benthic organisms is expected. The correlation between the SEM/AVS and the toxicity for the bioluminescent bacterium Photobacterium phosphoreum is investigated. Freshwater sediments originating from different locations with high and low heavy metal contamination are tested. The toxicity test is performed according to the Solid Phase Microtox test (SPT). Unexpectedly, negative correlation between SEM/AVS and SPT toxicity was found (r = {minus}0.82, n = 44). However, sediments with a high sulphide content show a correlation between AVS and toxicity determined by SPT (r = 0.90, n = 18). Comparison with literature data and possible hypothesis for the discrepancies with the data will be presented. Additionally, a validation study concerning the AVS determination has been performed. Some of the aspects involved are: the sampling technique preserving the anoxic conditions of the sediment, the influence of the storage time and storage conditions on the AVS content of the standard conditions and the recovery of the metal sulphides used for the SEM calculation.

  13. Cysteine and hydrogen sulphide in the regulation of metabolism: insights from genetics and pharmacology.

    PubMed

    Carter, Roderick N; Morton, Nicholas M

    2016-01-01

    Obesity and diabetes represent a significant and escalating worldwide health burden. These conditions are characterized by abnormal nutrient homeostasis. One such perturbation is altered metabolism of the sulphur-containing amino acid cysteine. Obesity is associated with elevated plasma cysteine, whereas diabetes is associated with reduced cysteine levels. One mechanism by which cysteine may act is through its enzymatic breakdown to produce hydrogen sulphide (H2S), a gasotransmitter that regulates glucose and lipid homeostasis. Here we review evidence from both pharmacological studies and transgenic models suggesting that cysteine and hydrogen sulphide play a role in the metabolic dysregulation underpinning obesity and diabetes. We then outline the growing evidence that regulation of hydrogen sulphide levels through its catabolism can impact metabolic health. By integrating hydrogen sulphide production and breakdown pathways, we re-assess current hypothetical models of cysteine and hydrogen sulphide metabolism, offering new insight into their roles in the pathogenesis of obesity and diabetes.

  14. Encapsulation of zinc-rifampicin complex into transferrin-conjugated silver quantum-dots improves its antimycobacterial activity and stability and facilitates drug delivery into macrophages

    PubMed Central

    Pati, Rashmirekha; Sahu, Rojalin; Panda, Jagannath; Sonawane, Avinash

    2016-01-01

    In order to improve the chemotherapy of tuberculosis, there is an urgent need to enhance the efficacy of existing agents and also to develop more efficient drug delivery systems. Here, we synthesized a novel anti-TB drug complex consisting of zinc and rifampicin (Zn-RIF), and encapsulated it into transferrin-conjugated silver quantum-dots (Zn-RIF-Tf-QD) to improve delivery in macrophages. Successful synthesis of Zn-RIF and Zn-RIF-Tf-QD was confirmed by UV/Vis-spectroscopy, TEM, FTIR, photoluminescence, XRD, XPS, and NMR. The sizes of silver QDs and transferrin-conjugated QDs were found to be in the range of 5–20 nm. Activity assays showed that Zn-RIF-Tf-QD exhibited 10-fold higher antibacterial activity against Mycobacterium smegmatis and Mycobacterium bovis-BCG as compared to Zn-RIF, RIF and Zn. Immunofluorescence studies showed that Zn-RIF-Tf-QD-conjugates were actively endocytosed by macrophages and dendritic cells, but not by lung epithelial cells. Treatment with Zn-RIF-Tf-QD efficiently killed mycobacteria residing inside macrophages without exhibiting cytotoxicity and genotoxicity. Moreover, the conjugates remained stable for upto 48 h, were taken up into the late endosomal compartment of macrophages, and released the drug in a sustainable manner. Our data demonstrate that Zn-RIF-Tf-QDs have a great potential as anti-TB drugs. In addition, transferrin-conjugated QDs may constitute an effective drug delivery system for tuberculosis therapy. PMID:27113139

  15. CHARACTERIZATION OF SULPHIDE SILT PE-LOIDS IN SOME LAKES WITHIN ADJARA REGION AND DETERMINATION OF THE BIOLOGICALLY ACTIVE COMPOUNDS CONTENT.

    PubMed

    Masiukovichi, T; Jokhadze, M; Murtazashvili, T; Bakuridze, A

    2017-09-01

    Medicinal muds, so called Peloids in the last decade attract attention in many countries as effective means for the treatment- preventive, and perfumery-cosmetic purposes. It has been established that the possibilities of this formation of nature are not limited to the many-year experience of the mankind. In terms of further improvement of the human social sphere, nowadays peloids are referred to as XXI century material. The aim of the research was to study the physical-chemical characteristics, such as: humidity, pH, ash content, bulk (volumetric) density and organoleptic properties of sulphide silt peloids of some Adjara region lakes, as well as to determine the content of mineral and organic compounds (humic and organic acids). The objects of the study were the sulphide silt peloids of some Adjara region lakes: Mtsvane, Gasaliani, Shratiani, Nurigeli, Ardagani and Niphi. The main good quality indicators of the sulphide silt peloids have been determined according to the methods described in the State Pharmacopoeia XI. The mineral and organic compounds in the research objects have been determined using the modern instrumental methods of analysis described in the literature. Based on the performed studies, the main physical-chemical characteristics of sulphide silt peloids of some Adjara region lakes (Mtsvane, Gasaliani, Shratiani, Nurigeli, Ardagani and Niphi) have been studied and their mineral contents (Ca-Na Feldspar, K Feldspar, Ca- Montmorillonite, Hematite, Quartz, Magnetite, Chlorite) determined. By the spectrophotometric and gravimetric methods of analysis there is established, that the sulphide silt peloids of the lakes Ardagani (1,22%), Niphi (1,72%) and Gasaliani (1,33%) are distinguished by relatively higher content of humic acids. By the Gas Chromatography-Mass Spectrometry - method of analysis, in the study objects there is established the content of complex ethers of the following organic acids: Stearic, Palmitic, Caprylic, Myristic, Valeric, Lauric

  16. Highly sensitive plasmonic silver nanorods.

    PubMed

    Jakab, Arpad; Rosman, Christina; Khalavka, Yuriy; Becker, Jan; Trügler, Andreas; Hohenester, Ulrich; Sönnichsen, Carsten

    2011-09-27

    We compare the single-particle plasmonic sensitivity of silver and gold nanorods with similar resonance wavelengths by monitoring the plasmon resonance shift upon changing the environment from water to 12.5% sucrose solution. We find that silver nanoparticles have 1.2 to 2 times higher sensitivity than gold, in good agreement with simulations based on the boundary-elements-method (BEM). To exclude the effect of particle volume on sensitivity, we test gold rods with increasing particle width at a given resonance wavelength. Using the Drude-model of optical properties of metals together with the quasi-static approximation (QSA) for localized surface plasmons, we show that the dominant contribution to higher sensitivity of silver is the lower background polarizability of the d-band electrons and provide a simple formula for the sensitivity. We improve the reversibility of the silver nanorod sensors upon repeated cycles of environmental changes by blocking the high energy parts of the illumination light.

  17. Improving cytotoxicity against cancer cells by chemo-photodynamic combined modalities using silver-graphene quantum dots nanocomposites.

    PubMed

    Habiba, Khaled; Encarnacion-Rosado, Joel; Garcia-Pabon, Kenny; Villalobos-Santos, Juan C; Makarov, Vladimir I; Avalos, Javier A; Weiner, Brad R; Morell, Gerardo

    2016-01-01

    The combination of chemotherapy and photodynamic therapy has emerged as a promising strategy for cancer therapy due to its synergistic effects. In this work, PEGylated silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) were tested as a platform to deliver a chemotherapy drug and a photosensitizer, simultaneously, in chemo-photodynamic therapy against HeLa and DU145 cancer cells in vitro. Ag-GQDs have displayed high efficiency in delivering doxorubicin as a model chemotherapy drug to both cancer cells. The Ag-GQDs exhibited a strong antitumor activity by inducing apoptosis in cancer cells without affecting the viability of normal cells. Moreover, the Ag-GQDs exhibited a cytotoxic effect due to the generation of the reactive singlet oxygen upon 425 nm irradiation, indicating their applicability in photodynamic therapy. In comparison with chemo or photodynamic treatment alone, the combined treatment of Ag-GQDs conjugated with doxorubicin under irradiation with a 425 nm lamp significantly increased the death in DU145 and HeLa. This study suggests Ag-GQDs as a multifunctional and efficient therapeutic system for chemo-photodynamic modalities in cancer therapy.

  18. Improving cytotoxicity against cancer cells by chemo-photodynamic combined modalities using silver-graphene quantum dots nanocomposites

    PubMed Central

    Habiba, Khaled; Encarnacion-Rosado, Joel; Garcia-Pabon, Kenny; Villalobos-Santos, Juan C; Makarov, Vladimir I; Avalos, Javier A; Weiner, Brad R; Morell, Gerardo

    2016-01-01

    The combination of chemotherapy and photodynamic therapy has emerged as a promising strategy for cancer therapy due to its synergistic effects. In this work, PEGylated silver nanoparticles decorated with graphene quantum dots (Ag-GQDs) were tested as a platform to deliver a chemotherapy drug and a photosensitizer, simultaneously, in chemo-photodynamic therapy against HeLa and DU145 cancer cells in vitro. Ag-GQDs have displayed high efficiency in delivering doxorubicin as a model chemotherapy drug to both cancer cells. The Ag-GQDs exhibited a strong antitumor activity by inducing apoptosis in cancer cells without affecting the viability of normal cells. Moreover, the Ag-GQDs exhibited a cytotoxic effect due to the generation of the reactive singlet oxygen upon 425 nm irradiation, indicating their applicability in photodynamic therapy. In comparison with chemo or photodynamic treatment alone, the combined treatment of Ag-GQDs conjugated with doxorubicin under irradiation with a 425 nm lamp significantly increased the death in DU145 and HeLa. This study suggests Ag-GQDs as a multifunctional and efficient therapeutic system for chemo-photodynamic modalities in cancer therapy. PMID:26766909

  19. Properties of polypropylene nanocomposites containing silver nanoparticles.

    PubMed

    Jang, Myung Wook; Kim, Ju-Young; Ihn, Kyo Jin

    2007-11-01

    Silver/polypropylene (PP) nanocomposites containing silver nanoparticles smaller than 10 nm were prepared using a new synthetic method. AgNO3 crystals were dissolved into hydrophilic domain of polyoxyethylene maleate-based surfactant (PEOM), which gives self-assembly nano-structures. The AgNO3 in the nano-domains of PEOM was reduced by NaBH4 to form nanoparticles. The colloidal solutions with silver nanoparticles were diluted with ethanol and were mixed with PP pellets. Silver nanocomposites were prepared by extrusion compounding process after drying the pellets. Contents of silver nanoparticles dispersed within PP resin were changed from 100 to 1000 ppm. Formation of silver nanoparticles within PP was confirmed by UV-Vis spectroscopy and TEM. Size and distribution of dispersed silver nanoparticles were also measured by TEM. Silver/PP nanocomposites films showed not only improved thermal stability but also increased mechanical properties compared to neat PP film. Tensile properties of PP nanocomposites were largely improved compared with neat PP resin, and elongation increased also by 175% for the nanocomposites containing 1000 ppm silver nanoparticles.

  20. Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

    PubMed Central

    Watling, Helen R.; Shiers, Denis W.; Collinson, David M.

    2015-01-01

    In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II) and/or reduced inorganic sulphur compounds (RISC), such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As) to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity. PMID:27682094

  1. Removal of mercury (II), elemental mercury and arsenic from simulated flue gas by ammonium sulphide.

    PubMed

    Ning, Ping; Guo, Xiaolong; Wang, Xueqian; Wang, Ping; Ma, Yixing; Lan, Yi

    2015-01-01

    A tubular resistance furnace was used as a reactor to simulate mercury and arsenic in smelter flue gases by heating mercury and arsenic compounds. The flue gas containing Hg(2+), Hg(0) and As was treated with ammonium sulphide. The experiment was conducted to investigate the effects of varying the concentration of ammonium sulphide, the pH value of ammonium sulphide, the temperature of ammonium sulphide, the presence of SO2 and the presence of sulphite ion on removal efficiency. The prepared adsorption products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results showed that the optimal concentration of ammonium sulphide was 0.8 mol/L. The optimal pH value of ammonium sulphide was 10, and the optimal temperature of ammonium sulphide was 20°C.Under the optimum conditions, the removal efficiency of Hg(2+), Hg(0) and As could reach 99%, 88.8%, 98%, respectively. In addition, SO2 and sulphite ion could reduce the removal efficiency of mercury and arsenic from simulated flue gas.

  2. What's that smell? Hydrogen sulphide transport from Bardarbunga to Scandinavia

    NASA Astrophysics Data System (ADS)

    Grahn, Håkan; von Schoenberg, Pontus; Brännström, Niklas

    2015-09-01

    On Sep 9 2014 several incidences of foul smell (rotten eggs) were reported on the coast of Norway (in particular in the vicinity of Molde) and then on Sep 10 in the interior parts of county Västerbotten, Sweden. One of the theories that were put forward was that the foul smell was due to degassing of the Bardarbunga volcano on Iceland. Using satellite images (GOME-1,-2) of the sulphur dioxide, SO2, contents in the atmosphere surrounding Iceland to estimate flux of SO2 from the volcano and an atmospheric transport model, PELLO, we vindicate this theory: we argue that the cause for the foul smell was hydrogen sulphide originating from Bardarbunga. The model concentrations are also compared to SO2 concentration measurements from Muonio, Finland.

  3. Synthesis of indium sulphide quantum dots in perfluoronated ionomer membrane

    SciTech Connect

    Sumi, R.; Warrier, Anita R.; Vijayan, C.

    2014-01-28

    In this paper, we demonstrate a simple and efficient method for synthesis of β-indium sulphide (In{sub 2}S{sub 3}) nanoparticles embedded in an ionomer matrix (nafion membrane). The influence of reaction temperature on structural, compositional and optical properties of these films were analysed using X-Ray Diffraction, EDAX, UV-Vis absorption spectroscopy and photoluminescence studies. Average particle diameter was estimated using modified effective mass approximation method. Absorption spectra of In{sub 2}S{sub 3} nanoparticles show blue shift compared to bulk In{sub 2}S{sub 3}, indicating strong quantum size confinement effects. PL emission in the wavelength range 530–600 nm was recorded using a 488 nm line from an Ar{sup +} laser as the excitation source.

  4. Effect of aluminum and yttrium doping on zinc sulphide nanoparticles

    SciTech Connect

    Sharma, Swati Kashyap, Jyoti; Kapoor, A.; Gupta, Shubhra; Natasha

    2016-05-06

    In this work, pristine and doped Zinc Sulphide (ZnS) nanoparticles have been synthesized via chemical co-precipitation method. ZnS nanoparticles have been doped with Aluminium (Al) and Yttrium (Y) with doping concentration of 5wt% each. The structural and optical properties of the as prepared nanoparticles have been studied using X-Ray diffraction (XRD) technique and Photoluminescence spectroscopy. Average grain size of 2-3nm is observed through the XRD analysis. Effect of doping on stress, strain and lattice constant of the nanoparticles has also been analyzed. Photoluminescence spectra of the as prepared nanoparticles is enhanced due to Al doping and quenched due to Y doping. EDAX studies confirm the relative doping percentage to be 3.47 % and 3.94% by wt. for Al and Y doped nanoparticles respectively. Morphology of the nanoparticles studied using TEM and SEM indicates uniform distribution of spherical nanoparticles.

  5. First principle study of manganese doped cadmium sulphide sheet

    SciTech Connect

    Kumar, Sanjeev; Kumar, Ashok; Ahluwalia, P. K.

    2014-04-24

    First-principle electronic structure calculations for cadmium sulphide (CdS) sheet in hexagonal phase, with Manganese substitution and addition, as well as including the Cd defects, are investigated. The lattice constants calculated for CdS sheet agrees fairly well with results reported for thin films experimentally. The calculations of total spin density of states and partial density of states in different cases shows substantial magnetic dipole moments acquired by the sheet. A magnetic dipole moment 5.00612 μ{sub B} and band gap of the order 1 eV are found when cadmium atom is replaced by Manganese. The magnetism acquired by the sheet makes it functionally important candidate in many applications.

  6. Synthesis of indium sulphide quantum dots in perfluoronated ionomer membrane

    NASA Astrophysics Data System (ADS)

    Sumi, R.; Warrier, Anita R.; Vijayan, C.

    2014-01-01

    In this paper, we demonstrate a simple and efficient method for synthesis of β-indium sulphide (In2S3) nanoparticles embedded in an ionomer matrix (nafion membrane). The influence of reaction temperature on structural, compositional and optical properties of these films were analysed using X-Ray Diffraction, EDAX, UV-Vis absorption spectroscopy and photoluminescence studies. Average particle diameter was estimated using modified effective mass approximation method. Absorption spectra of In2S3 nanoparticles show blue shift compared to bulk In2S3, indicating strong quantum size confinement effects. PL emission in the wavelength range 530-600 nm was recorded using a 488 nm line from an Ar+ laser as the excitation source.

  7. First principle study of manganese doped cadmium sulphide sheet

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Kumar, Ashok; Ahluwalia, P. K.

    2014-04-01

    First-principle electronic structure calculations for cadmium sulphide (CdS) sheet in hexagonal phase, with Manganese substitution and addition, as well as including the Cd defects, are investigated. The lattice constants calculated for CdS sheet agrees fairly well with results reported for thin films experimentally. The calculations of total spin density of states and partial density of states in different cases shows substantial magnetic dipole moments acquired by the sheet. A magnetic dipole moment 5.00612 μB and band gap of the order 1 eV are found when cadmium atom is replaced by Manganese. The magnetism acquired by the sheet makes it functionally important candidate in many applications.

  8. Concentration-time interactions in hydrogen sulphide toxicity in rats.

    PubMed Central

    Prior, M G; Sharma, A K; Yong, S; Lopez, A

    1988-01-01

    Concentration-time interactions were investigated in young male and female Sprague-Dawley, Long Evans and Fischer-344 rats exposed to hydrogen sulphide for two, four or six hours. Higher concentrations caused more deaths, with no significant difference for duration of exposure. A significant sex effect was noted with 30% mortality in males and 20% in females, with no significant difference among strains. Changes in weight were significant: increasing with concentration, higher in males than in females, different among strains (Fischer-344 less than Sprague Dawley less than Long Evans), and affected by duration of exposure. Lethal concentration values (LC50 and LC10) were estimated, for the pooled data set (n = 456); the probit equation was Y = -5.74749 + 3.8259X where X is log10 dose of hydrogen sulphide in parts per million. The LC50/LC10 values were 644/298 parts per million (902/417 mg m-3) respectively. Individual probit analyses were also performed for strain, hours of exposure and sex. The LC50 and LC10 values for male, female and strain were not different. Significant differences were observed among LC50/LC10 values for hours of exposure (2 h = 587/549 parts per million, 822/769 mg m-3; 4 h = 501/422 parts per million, 701/591 mg m-3; 6 h = 335/299 parts per million, 469/491 mg m-3). There was no effect of spatial position in the exposure chamber on the distribution of mortality. All rats of all strains dying had severe pulmonary edema. PMID:3167719

  9. Non-chondritic distribution of the highly siderophile elements in mantle sulphides

    NASA Astrophysics Data System (ADS)

    Alard, Olivier; Griffin, William L.; Lorand, Jean Pierre; Jackson, Simon E.; O'Reilly, Suzanne Y.

    2000-10-01

    The abundances of highly siderophile (iron-loving) elements (HSEs) in the Earth's mantle provide important constraints on models of the Earth's early evolution. It has long been assumed that the relative abundances of HSEs should reflect the composition of chondritic meteorites-which are thought to represent the primordial material from which the Earth was formed. But the non-chondritic abundance ratios recently found in several types of rock derived from the Earth's mantle have been difficult to reconcile with standard models of the Earth's accretion, and have been interpreted as having arisen from the addition to the primitive mantle of either non-chondritic extraterrestrial material or differentiated material from the Earth's core. Here we report in situ laser-ablation analyses of sulphides in mantle-derived rocks which show that these sulphides do not have chondritic HSE patterns, but that different generations of sulphide within single samples show extreme variability in the relative abundances of HSEs. Sulphides enclosed in silicate phases have high osmium and iridium abundances but low Pd/Ir ratios, whereas pentlandite-dominated interstitial sulphides show low osmium and iridium abundances and high Pd/Ir ratios. We interpret the silicate-enclosed sulphides as the residues of melting processes and interstitial sulphides as the crystallization products of sulphide-bearing (metasomatic) fluids. We suggest that non-chondritic HSE patterns directly reflect processes occurring in the upper mantle-that is, melting and sulphide addition via metasomatism-and are not evidence for the addition of core material or of `exotic' meteoritic components.

  10. End-Permian ozone shield unaffected by oceanic hydrogen sulphide and methane releases

    NASA Astrophysics Data System (ADS)

    Harfoot, Michael B.; Pyle, John A.; Beerling, David J.

    2008-04-01

    Earth experienced repeated episodes of widespread surface and deep-ocean anoxia with a significant accumulation of sulphide-rich waters over the past two billion years. The resulting massive releases of hydrogen sulphide from the oceans, together with methane from the geosphere, have been suggested as a cause for mass extinctions through destruction of the ozone shield and a lethal accumulation of hydrogen sulphide at the surface. Here, we use a two-dimensional atmospheric chemistry-transport model with representative climate and atmospheric composition to simulate the effect of large hydrogen sulphide and methane releases at the time of the end-Permian mass extinction ~251 million years ago. In our simulations, the integrity of the stratospheric ozone shield is maintained for oceanic hydrogen sulphide releases up to 15,000TgSyr-1, a limit far exceeding the threshold for ozone collapse identified previously (2,000-4,000TgSyr-1). Scenarios of simultaneous hydrogen sulphide and methane injections also failed to significantly deplete the Earth's ozone shield, and generated non-lethal hydrogen sulphide concentrations (1-2p.p.m.) at the surface. In our two-dimensional model simulations, the high photolysis environment in the tropics maintains the oxidizing capacity of the tropical troposphere, with high local hydroxyl radical concentrations, and greatly diminishes hydrogen sulphide entry into the stratosphere. We suggest that given current constraints on possible hydrogen sulphide and methane releases from anoxic oceans, and the geosphere, over the past 0.5 billion years, these gases seem unlikely to be the cause of coincident terrestrial biotic mass extinctions.

  11. Magmatic Controls on the Genesis of Ni-Cu-PGE Sulphide Mineralisation on Mars

    NASA Astrophysics Data System (ADS)

    Baumgartner, R. J.; Fiorentini, M.; Baratoux, D.; Micklethwaite, S.; Sener, K.; McCuaig, C.

    2014-12-01

    Widespread igneous activity, which shows striking mineralogical, petrographical and chemical similarities with terrestrial komatiites and ferropicrites, intensely affected, reshaped and buried the primordial Martian crust. This study evaluates for the first time whether the broad igneous activity on Mars may have led to the formation of orthomagmatic Ni-Cu-PGE sulphide mineralisation similar to that associated with terrestrial komatiites and ferropicrites. Particular focus is laid on two different components of the Martian Ni-Cu-PGE sulphide mineral system: 1) the potential metal and sulphur fertility of source regions, and 2) the physical/chemical processes that enable sulphide supersaturation and metal concentration into an immiscible sulphide liquid. We show that potentially metal-rich Martian mantle melts likely reach sulphide saturation within 20-35 wt% of simple silicate fractionation; a value that is comparable to that of the terrestrial equivalents (i.e. ferropicrites and komatiites). However, the majority of terrestrial world-class Ni-Cu-PGE sulphide deposits originated by the assimilation of crustal sulphur-rich country rocks, allowing the attainment of sulphide supersaturation and liquid segregation during early stages of magma evolution. The high sulphur content in Martian crustal lithologies, ranging from sulphide bearing magmatic rocks to sulphate-rich regoliths and sedimentary deposits, imply that mantle melts potentially assimilated significant amounts of crustal sulphur during their ascent and emplacement. As a main outcome we show that channelled and fluid lava flows, which potentially emplaced and incised into these sulphur-rich crustal lithologies, are the most promising systems that may have led to the formation of Ni-Cu-PGE sulphide mineralisation on Mars.

  12. A facile solvent mediated self-assembly silver nanoparticle mirror substrate for quantitatively improved surface enhanced Raman scattering.

    PubMed

    Qu, Yanqi; Tan, Chen; Zhang, Zhiyun; He, Lili

    2017-09-22

    Herein, a facile solvent mediated silver nanoparticle (AgNP) mirror was introduced as a reproducible and sensitive surface-enhanced Raman scattering (SERS) substrate. The AgNP mirror was fabricated based on commercially available citrate coated AgNPs via a facile and unique water-solvent interface assembly method without using any electrical equipment. By adding 0.2 mg ml(-1) citrate coated AgNPs dropwise into a mediating solvent, self-assembled AgNP mirrors were formed instantly and gradually settled down at the bottom. The mediating solvent is the key for this fabrication, which should contain a mixture of a non-polar (e.g. hexane, cyclohexane, and iso-octane) and a polar (e.g., acetonitrile, acetone, methanol, and ethanol) organic solvents that have a lower density than water. The fabricated AgNP mirror showed a uniform monolayer arrangement which produced highly reproducible and sensitive signals. The coefficient of variance (i.e., percentage relative standard deviation) for AgNP mirrors was 7.3% compared to 33.0% for AgNP aggregates. A lower limit of detection (0.008 ppm) and a higher coefficient of determination (0.9981) for the detection of the fonofos pesticide were also obtained from the AgNP mirror compared to that from the AgNP aggregates. The practical application of this nanoscale AgNP mirror sensing substrate was also confirmed by its accurate quantification of 0.5 ppm fonofos in apple juice and green tea (i.e., 105.06% and 106.16% recovery value, respectively).

  13. The Math Emporium: Higher Education's Silver Bullet

    ERIC Educational Resources Information Center

    Twigg, Carol A.

    2011-01-01

    Throughout the 1990's, many people saw information technology as a silver bullet that could solve many of higher education's problems, among them the need to improve learning outcomes and control the ever-upward trajectory of higher education costs. The term "silver bullet" connotes a direct and effortless solution to a problem.…

  14. The Math Emporium: Higher Education's Silver Bullet

    ERIC Educational Resources Information Center

    Twigg, Carol A.

    2011-01-01

    Throughout the 1990's, many people saw information technology as a silver bullet that could solve many of higher education's problems, among them the need to improve learning outcomes and control the ever-upward trajectory of higher education costs. The term "silver bullet" connotes a direct and effortless solution to a problem.…

  15. The effects of composition and temperature on chalcophile and lithophile element partitioning into magmatic sulphides

    NASA Astrophysics Data System (ADS)

    Kiseeva, Ekaterina S.; Wood, Bernard J.

    2015-08-01

    We develop a comprehensive model to describe trace and minor element partitioning between sulphide liquids and anhydrous silicate liquids of approximately basaltic composition. We are able thereby to account completely for the effects of temperature and sulphide composition on the partitioning of Ag, Cd, Co, Cr, Cu, Ga, Ge, In, Mn, Ni, Pb, Sb, Ti, Tl, V and Zn. The model was developed from partitioning experiments performed in a piston-cylinder apparatus at 1.5 GPa and 1300 to 1700 °C with sulphide compositions covering the quaternary FeSsbnd NiSsbnd CuS0.5sbnd FeO. Partitioning of most elements is a strong function of the oxygen (or FeO) content of the sulphide. This increases linearly with the FeO content of the silicate melt and decreases with Ni content of the sulphide. As expected, lithophile elements partition more strongly into sulphide as its oxygen content increases, while chalcophile elements enter sulphide less readily with increasing oxygen. We parameterised the effects by using the ε-model of non-ideal interactions in metallic liquids. The resulting equation for partition coefficient of an element M between sulphide and silicate liquids can be expressed as We used our model to calculate the amount of sulphide liquid precipitated along the liquid line of descent of MORB melts and find that 70% of silicate crystallisation is accompanied by ∼0.23% of sulphide precipitation. The latter is sufficient to control the melt concentrations of chalcophile elements such as Cu, Ag and Pb. Our partition coefficients and observed chalcophile element concentrations in MORB glasses were used to estimate sulphur solubility in MORB liquids. We obtained between ∼800 ppm (for primitive MORB) and ∼2000 ppm (for evolved MORB), values in reasonable agreement with experimentally-derived models. The experimental data also enable us to reconsider Ce/Pb and Nd/Pb ratios in MORB. We find that constant Ce/Pb and Nd/Pb ratios of 25 and 20, respectively, can be achieved

  16. Some studies on successive ionic layer adsorption and reaction (SILAR) grown indium sulphide thin films

    SciTech Connect

    Pathan, H.M.; Lokhande, C.D. . E-mail: l_chandrakant@yahoo.com; Kulkarni, S.S.; Amalnerkar, D.P.; Seth, T.; Han, Sung-Hwan . E-mail: shhan@hanyang.ac.kr

    2005-06-15

    Indium sulphide (In{sub 2}S{sub 3}) thin films were grown on amorphous glass substrate by the successive ionic layer adsorption and reaction (SILAR) method. X-ray diffraction, optical absorption, scanning electron microscopy (SEM) and Rutherford back scattering (RBS) were applied to study the structural, optical, surface morphological and compositional properties of the indium sulphide thin films. Utilization of triethanolamine and hydrazine hydrate complexed indium sulphate and sodium sulphide as precursors resulted in nanocrystalline In{sub 2}S{sub 3} thin film. The optical band gap was found to be 2.7 eV. The film appeared to be smooth and homogeneous from SEM study.

  17. Selective growth and integration of silver nanoparticles on silver nanowires at room conditions for transparent nano-network electrode.

    PubMed

    Lu, Haifei; Zhang, Di; Ren, Xingang; Liu, Jian; Choy, Wallace C H

    2014-10-28

    Recently, metal nanowires have received great research interests due to their potential as next-generation flexible transparent electrodes. While great efforts have been devoted to develop enabling nanowire electrodes, reduced contact resistance of the metal nanowires and improved electrical stability under continuous bias operation are key issues for practical applications. Here, we propose and demonstrate an approach through a low-cost, robust, room temperature and room atmosphere process to fabricate a conductive silver nano-network comprising silver nanowires and silver nanoparticles. To be more specific, silver nanoparticles are selectively grown and chemically integrated in situ at the junction where silver nanowires meet. The site-selective growth of silver nanoparticles is achieved by a plasmon-induced chemical reaction using a simple light source at very low optical power density. Compared to silver nanowire electrodes without chemical treatment, we observe tremendous conductivity improvement in our silver nano-networks, while the loss in optical transmission is negligible. Furthermore, the silver nano-networks exhibit superior electrical stability under continuous bias operation compared to silver nanowire electrodes formed by thermal annealing. Interestingly, our silver nano-network is readily peeled off in water, which can be easily transferred to other substrates and devices for versatile applications. We demonstrate the feasibly transferrable silver conductive nano-network as the top electrode in organic solar cells. Consequently, the transparent and conductive silver nano-networks formed by our approach would be an excellent candidate for various applications in optoelectronics and electronics.

  18. Column tests to enhance sulphide precipitation with liquid organic electron donators to remediate AMD-influenced groundwater

    NASA Astrophysics Data System (ADS)

    Bilek, Felix

    2006-03-01

    Dump groundwaters in the former East-German lignite-mining district are characterized by high amounts of ferrous iron and sulphate. Both the pyrite weathering products endanger the surface water quality when discharged into lakes. Only the precipitation of both contaminants in the subsurface can prevent the further contamination of surface waters. The two-step process of microbial catalyzed sulphate reduction and iron sulphide precipitation is limited by the low availability of natural organic substances as electron donators. Therefore, a new remediation technique is developed based on the injection of a liquid organic electron donator (methanol) into the contaminated aquifer. The saturated aquifer is used as a bioreactor, where iron monosulphides are precipitated in the groundwater-filled pore space. Column experiments were performed under natural pressure and temperature conditions with natural anoxic groundwater and original sediments to test the remediation technology. The test showed that a complete iron removal (4 mmol/l), even under rather acid conditions (pH 3.8), is possible after having established an active sulphate reducer population. The turnover of the added organic substance with sulphate is complete and the amount of the resulting sulphide controls the effluent pH. In addition, intensified microbial activity triggers the turnover of natural organic substances. Also, natural Fe(III) hydroxides react with the sulphide produced. Considering the long natural retention times (decades), artificially enhanced FeS precipitation is spontaneous, although it shows kinetic behaviour in the range of days. In light of the promising results, the development of a field scale application of this technique is considered to be necessary. It will have to focus on the improved precipitation control of the FeS in the subsurface.

  19. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber.

    PubMed

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.

  20. Site-Selective Controlled Dealloying Process of Gold-Silver Nanowire Array: a Simple Approach towards Long-Term Stability and Sensitivity Improvement of SERS Substrate

    PubMed Central

    Wiriyakun, Natta; Pankhlueab, Karuna; Boonrungsiman, Suwimon; Laocharoensuk, Rawiwan

    2016-01-01

    Limitations of achieving highly sensitive and stable surface-enhanced Raman scattering (SERS) substrate greatly concern the suitable method for fabrication of large-area plasmonic nanostructures. Herein we report a simple approach using template-based synthesis to create a highly ordered two-dimensional array of gold-silver alloy nanowires, followed by the controlled dealloying process. This particular step of mild acid etching (15%v/v nitric acid for 5 min) allowed the formation of Raman hot spots on the nanowire tips while maintaining the integrity of highly active alloy composition and rigid nanowire array structure. Full consideration of SERS substrate performance was accomplished using 4-mercaptobenzoic acid (4-MBA) as a probe molecule. Exceedingly higher SERS signal (150-fold) can be achieved with respect to typical gold film substrate. Moreover, an excellent stability of SERS substrate was also determined for over 3 months storage time. In contrast to the previous studies which stability improvement was accomplished at a cost of sensitivity reduction, the simultaneous improvement of sensitivity and stability makes the controlled dealloying process an excellent choice of SERS substrate fabrication. In addition, uniformity and reproducibility studies indicated satisfactory results with the acceptable values of relative standard deviation. PMID:27958367

  1. Site-Selective Controlled Dealloying Process of Gold-Silver Nanowire Array: a Simple Approach towards Long-Term Stability and Sensitivity Improvement of SERS Substrate

    NASA Astrophysics Data System (ADS)

    Wiriyakun, Natta; Pankhlueab, Karuna; Boonrungsiman, Suwimon; Laocharoensuk, Rawiwan

    2016-12-01

    Limitations of achieving highly sensitive and stable surface-enhanced Raman scattering (SERS) substrate greatly concern the suitable method for fabrication of large-area plasmonic nanostructures. Herein we report a simple approach using template-based synthesis to create a highly ordered two-dimensional array of gold-silver alloy nanowires, followed by the controlled dealloying process. This particular step of mild acid etching (15%v/v nitric acid for 5 min) allowed the formation of Raman hot spots on the nanowire tips while maintaining the integrity of highly active alloy composition and rigid nanowire array structure. Full consideration of SERS substrate performance was accomplished using 4-mercaptobenzoic acid (4-MBA) as a probe molecule. Exceedingly higher SERS signal (150-fold) can be achieved with respect to typical gold film substrate. Moreover, an excellent stability of SERS substrate was also determined for over 3 months storage time. In contrast to the previous studies which stability improvement was accomplished at a cost of sensitivity reduction, the simultaneous improvement of sensitivity and stability makes the controlled dealloying process an excellent choice of SERS substrate fabrication. In addition, uniformity and reproducibility studies indicated satisfactory results with the acceptable values of relative standard deviation.

  2. Site-Selective Controlled Dealloying Process of Gold-Silver Nanowire Array: a Simple Approach towards Long-Term Stability and Sensitivity Improvement of SERS Substrate.

    PubMed

    Wiriyakun, Natta; Pankhlueab, Karuna; Boonrungsiman, Suwimon; Laocharoensuk, Rawiwan

    2016-12-13

    Limitations of achieving highly sensitive and stable surface-enhanced Raman scattering (SERS) substrate greatly concern the suitable method for fabrication of large-area plasmonic nanostructures. Herein we report a simple approach using template-based synthesis to create a highly ordered two-dimensional array of gold-silver alloy nanowires, followed by the controlled dealloying process. This particular step of mild acid etching (15%v/v nitric acid for 5 min) allowed the formation of Raman hot spots on the nanowire tips while maintaining the integrity of highly active alloy composition and rigid nanowire array structure. Full consideration of SERS substrate performance was accomplished using 4-mercaptobenzoic acid (4-MBA) as a probe molecule. Exceedingly higher SERS signal (150-fold) can be achieved with respect to typical gold film substrate. Moreover, an excellent stability of SERS substrate was also determined for over 3 months storage time. In contrast to the previous studies which stability improvement was accomplished at a cost of sensitivity reduction, the simultaneous improvement of sensitivity and stability makes the controlled dealloying process an excellent choice of SERS substrate fabrication. In addition, uniformity and reproducibility studies indicated satisfactory results with the acceptable values of relative standard deviation.

  3. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    PubMed Central

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte. PMID:25411566

  4. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    NASA Astrophysics Data System (ADS)

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-11-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.

  5. The Ioko-Dovyren layered massif (Southern Siberia, Russia): 2. Melt vs sulphide percolation process and modeling sulphide saturation in the parental magmas and original cumulates

    NASA Astrophysics Data System (ADS)

    Ariskin, Alexey; Danyushevsky, Leonid

    2013-04-01

    An important feature of the Dovyren intrusive complex [1] is its fertility due to the presence of massive sulphide ores near the bottom of the Ioko-Dovyren massif (YDM, SW and NE margins), as well as PGE-reefs in anorthosites from the Ol-gabbronorite zone in the centre [2]. These observations argue for the importance of downward percolation of sulphides through the porous space of cumulates and probable link of this process with upward migration of intercumulus melts at a post-cumulus stage. Indirectly, this is supported by the basic conclusion on the open-system behavior of the magma chamber [1]. A key aspect of these speculations is the onset of sulphide immiscibility in YDM parental magmas and the original cumulates. To reconstruct the sulphide saturation history, we applied a newly developed sulphide version of COMAGMAT (ver. 5.2 [3]) to the rocks from the chilled zone of YDM and underlying ultramafic sills, by simulating the course of their crystallization coupled with the SCSS calculations. Modeled crystallization trajectories evidence for under-saturated nature of the most primitive parental magmas (1310oC, Fo88) from which the chilled rocks were crystallized, whereas more evolved rocks from the sills demonstrate sulphide saturation starting from their initial temperature (1190oC, Fo85), see [1]. This correlates with the absence of sulphide ores in the central parts of the pluton and their occurrence in underlying ultramafics and YDM border series containing olivine Fo~85. Another set of calculations was carried out to demonstrate the effect of bulk Ni contents in Ol cumulate piles on the evolution of SCSS during their post-cumulus crystallization [3]. To achieve the goal, two calculations by the COMAGMAT-5.2 model were carried out. The first one involved modelling equilibrium crystallization for an initial mixture of Ol (Fo88) and intercumulus melt (~1320oC), with the starting composition corresponding to that of a bottom Pl-dunite (2315 ppm NiO, 0.030 wt

  6. Utilization of hydroxypropyl carboxymethyl cellulose in synthesis of silver nanoparticles.

    PubMed

    Abdel-Halim, E S; Alanazi, Humaid H; Al-Deyab, Salem S

    2015-04-01

    Hydroxypropyl carboxymethyl cellulose samples having varying degrees of substitution and varying degrees of polymerization were used to reduce silver nitrate to silver nanoparticles. UV spectral analysis of silver nanoparticles colloidal solution reveal that increasing the pH of the reduction solution leads to improvement in the intensity of the absorption band for silver nanoparticles, to be maximum at pH 11. The absorption peak intensity also enhanced upon prolonging the reaction duration up to 60 min. The conversion of silver ions to metallic silver nanoparticles was found to be temperature-dependent and maximum transformation occurs at 60 °C. The reduction efficiency of hydroxypropyl carboxymethyl cellulose was found to be affected by its degree of polymerization. Colloidal solutions of silver nanoparticles having concentration up to 1000 ppm can be prepared upon fixing the ratio between silver nitrate and hydroxypropyl carboxymethyl cellulose at 0.017-0.3g per each 100ml of the reduction solution.

  7. Trace Element Composition of Metal and Sulphides in Iron Meteorites Determined Using ICP-MS

    NASA Astrophysics Data System (ADS)

    Giscard, M. D.; Hammond, S. J.; Bland, P. A.; Benedix, G. K.; Rogers, N. W.; Russell, S. S.; Genge, M. J.; Rehkamper, M.

    2012-09-01

    We measured trace element concentrations in Nantan, Toluca, Cape York, Carthage, Gibeon and Dronino. Poikiloblastic daubreelite in Gibeon indicates shock metamorphism. There is a volatile depletion in metal and sulphides.

  8. Luminescent characteristics of sol-gel produced zinc sulphide display structures

    NASA Astrophysics Data System (ADS)

    Kavanagh, Yvonne M.; Cameron, David C.; Ryan, Brendan; Tobin, Ger

    2003-03-01

    Thin film electroluminescent (TFEL) display structures have been produced by sol-gel technology, with the active layer comprising doped zinc sulphide films produced by the sulphidation of sol-gel deposited zinc oxide thin films. The luminescent properties of display structures using manganese-doped zinc sulphide, which has a strong orange emission due to the Mn2+4 T1(4G) 6A1(6S) transitions have been investigated using photoluminescence (PL), cathodoluminescence (CL), and electroluminescence (EL) and the correlation between the luminescence produced by the various methods has been studied. A comparison of the spectra using PL, CL and EL has shown how these excitation methods can be used to quantify the electroluminescence produced by the zinc sulphide. The effects of the interaction between the insulating layer and the emission layer have also been studied.

  9. Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain.

    PubMed

    Bañares-España, Elena; del Mar Fernández-Arjona, María; García-Sánchez, María Jesús; Hernández-López, Miguel; Reul, Andreas; Mariné, Mariona Hernández; Flores-Moya, Antonio

    2016-05-01

    The cyanobacterium Microcystis aeruginosa is a mesophilic freshwater organism, which cannot tolerate sulphide. However, it was possible to isolate a sulphide-resistant (S(r)) mutant strain that was able to survive in a normally lethal medium sulphide. In order to evaluate the cost of the mutation conferring sulphide resistance in the S(r) strain of M. aeruginosa, the morphology and the photosynthetic performance were compared to that found in the wild-type, sulphide-sensitive (S(s)) strain. An increase in size and a disrupted morphology was observed in S(r) cells in comparison to the S(s) counterpart. Phycoerythrin and phycocyanin levels were higher in the S(r) than in the S(s) cells, whereas a higher carotenoid content, per unit volume, was found in the S(s) strain. The irradiance-saturated photosynthetic oxygen-production rate (GPR max) and the photosynthetic efficiency (measured both by oxygen production and fluorescence, α(GPR) and α(ETR)) were lower in the S(r) strain than in the wild-type. These results appear to be the result of package effect. On the other hand, the S(r) strain showed higher quantum yield of non-photochemical quenching, especially those regulated mechanisms (estimated throughout qN and Y(NPQ)) and a significantly lower slope in the maximum quantum yield of light-adapted samples (Fv'/Fm') compared to the S(s) strain. These findings point to a change in the regulation of the quenching of the transition states (qT) in the S(r) strain which may be generated by a change in the distribution of thylakoidal membranes, which somehow could protect metalloenzymes of the electron transport chain from the lethal effect of sulphide.

  10. The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials

    NASA Astrophysics Data System (ADS)

    Dunne, Peter W.; Starkey, Chris L.; Gimeno-Fabra, Miquel; Lester, Edward H.

    2014-01-01

    Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control. Electronic supplementary information (ESI) available: Experimental details, refinement procedure, fluorescence spectra of ZnS samples. See DOI: 10.1039/c3nr05749f

  11. Self-reduction and size controlled synthesis of silver nanoparticles on carbon nanospheres by grafting triazine-based molecular layer for conductivity improvement

    NASA Astrophysics Data System (ADS)

    Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

    2016-02-01

    A facile, self-reduction and size controlled synthesis method has been explored to fabricate silver nanoparticles (Ag NPs) on carbon nanosphere (CNs) under mild conditions. Without using predeposition of seed metals and reducing agent, a uniform and complete layer of Ag NPs was formed through grafting a molecular layer on CNs surfaces under UV irradiation. The size and thickness of Ag NPs were effectively tuned by adjusting the UV irradiation time. This direct formation of Ag NPs was attributed to self seed in aqueous Ag(NH3)2+ complex solution through a triazine-based silane coupling agent molecular layer, even at 25 °C. Scanning electron microscopy (SEM), Transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the Ag NPs' properties. A substantial conductivity improvement of prepared Ag NPs on carbon nanosphere was demonstrated. The presented method is simple and environmentally friendly and thus should be of significant value for the industrial fabrication of Ag NPs on carbon nanosphere in conduct electricity paint and coating applications.

  12. Hydrogen sulphide protects against NSAID-enteropathy through modulation of bile and the microbiota

    PubMed Central

    Blackler, Rory W; Motta, Jean-Paul; Manko, Anna; Workentine, Matthew; Bercik, Premysl; Surette, Michael G; Wallace, John L

    2015-01-01

    Background and Purpose Hydrogen sulphide is an important mediator of gastrointestinal mucosal defence. The use of non-steroidal anti-inflammatory drugs (NSAIDs) is significantly limited by their toxicity in the gastrointestinal tract. Particularly concerning is the lack of effective preventative or curative treatments for NSAID-induced intestinal damage and bleeding. We evaluated the ability of a hydrogen sulphide donor to protect against NSAID-induced enteropathy. Experimental Approach Intestinal ulceration and bleeding were induced in Wistar rats by oral administration of naproxen. The effects of suppression of endogenous hydrogen sulphide synthesis or administration of a hydrogen sulphide donor (diallyl disulphide) on naproxen-induced enteropathy was examined. Effects of diallyl disulphide on small intestinal inflammation and intestinal microbiota were also assessed. Bile collected after in vivo naproxen and diallyl disulphide administration was evaluated for cytotoxicity in vitro using cultured intestinal epithelial cells. Key Results Suppression of endogenous hydrogen sulphide synthesis by β-cyano-L-alanine exacerbated naproxen-induced enteropathy. Diallyl disulphide co-administration dose-dependently reduced the severity of naproxen-induced small intestinal damage, inflammation and bleeding. Diallyl disulphide administration attenuated naproxen-induced increases in the cytotoxicity of bile on cultured enterocytes, and prevented or reversed naproxen-induced changes in the intestinal microbiota. Conclusions and Implications Hydrogen sulphide protects against NSAID-enteropathy in rats, in part reducing the cytotoxicity of bile and preventing NSAID-induced dysbiosis. PMID:25297699

  13. Human exposure to hydrogen sulphide concentrations near wastewater treatment plants.

    PubMed

    Godoi, Ana Flavia Locateli; Grasel, Anderson Marlon; Polezer, Gabriela; Brown, Andrew; Potgieter-Vermaak, Sanja; Scremim, Débora Camargo; Yamamoto, Carlos I; Godoi, Ricardo Henrique Moreton

    2017-08-17

    The hydrogen sulphide (H2S) levels from wastewater treatment plants (WWTPs) in Curitiba, Brazil have been quantified for the first time. H2S generated by anaerobic decomposition of organic matter in WWTPs is a cause for concern because it is an air pollutant, which can cause eye and respiratory irritation, headaches, and nausea. Considering the requirement for WWTPs in all communities, it is necessary to assess the concentrations and effects of gases such as H2S on populations living and/or working near WWTPs. The primary objective of this study was to evaluate the indoor and outdoor concentration of H2S in the neighbourhood of two WWTPs located in Curitiba, as well as its human health impacts. Between August 2013 and March 2014 eight sampling campaigns were performed using passive samplers and the analyses were carried out by spectrophotometry, presenting mean concentrations ranging from 0.14 to 32μgm(-3). Eleven points at WWTP-A reported H2S average concentrations above the WHO recommendation of 10μgm(-3), and 15 points above the US EPA guideline of 2μgm(-3). At WWTP-B the H2S concentration was above US EPA guideline at all the sampling points. The I/O ratio on the different sampling sites showed accumulation of indoor H2S in some instances and result in exacerbating the exposure of the residents. The highest H2S concentrations were recorded during the summer in houses located closest to the sewage treatment stations, and towards the main wind direction, showing the importance of these factors when planning a WWTP. Lifetime risk assessments of hydrogen sulphide exposure showed a significant non-carcinogenic adverse health risk for local residents and workers, especially those close to anaerobic WWTPs. The data indicated that WWTPs operated under these conditions should be recognized as a significant air pollution source, putting local populations at risk. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. A photochemical approach designed to improve the coating of nanoscale silver films onto food plastic wrappings intended to control bacterial hazards

    NASA Astrophysics Data System (ADS)

    Mustatea, Gabriel; Vidal, Loïc; Calinescu, Ioan; Dobre, Alina; Ionescu, Mariana; Balan, Lavinia

    2015-01-01

    Plasmonic silver film was directly generated on a variety of substrates through a facile and environmentally friendly method, which involves a UV-photoreduction process without any reducing or stabilizing agent and requiring no thermal step. Top-coated films of unprotected silver nanoparticles (3-11 nm) were generated from hydroalcoholic AgNO3 solution and directly on glass substrates or food packaging plastic wraps, low density polyethylene film, and polyvinyl chloride. The natural antibacterial activity of the material was evaluated. The correlation between silver migration and antimicrobial activity of silver-functionalized substrates against pure strains of gram-negative bacteria ( Escherichia coli) and gram-positive bacteria ( Staphylococcus aureus) was demonstrated. By way of illustration, food plastic wraps top-coated in this way exhibited a high antibacterial activity. The metal nanoparticle film obtained in this way was characterized and the influence of several parameters (fluence, exposure, silver nitrate concentration, and nature of the free radicals generator) on their formation was studied. Moreover, by shaping the actinic beam with an appropriate device, it is very easy to pattern the brown yellow silver nanofilm or to print messages in plain text.

  15. Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

    NASA Astrophysics Data System (ADS)

    Pal, Hemant; Sharma, Vimal

    2014-11-01

    The mechanical, electrical, and thermal expansion properties of carbon nanotube (CNT)-based silver and silver-palladium (10:1, w/w) alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver-palladium nanocomposite with CNT resulted in increases in the hardness and Young's modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion (CTE). The hardness and Young's modulus of the nanocomposites were increased by 30%-40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver-palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.

  16. Sulphide mineralization and wall-rock alteration in ophiolites and modern oceanic spreading centres

    USGS Publications Warehouse

    Koski, R.A.

    1983-01-01

    Massive and stockwork Fe-Cu-Zn (Cyprus type) sulphide deposits in the upper parts of ophiolite complexes represent hydrothermal mineralization at ancient accretionary plate boundaries. These deposits are probable metallogenic analogues of the polymetallic sulphide deposits recently discovered along modern oceanic spreading centres. Genetic models for these deposits suggest that mineralization results from large-scale circulation of sea-water through basaltic basement along the tectonically active axis of spreading, a zone of high heat flow. The high geothermal gradient above 1 to 2 km deep magma chambers emplaced below the ridge axis drives the convective circulation cell. Cold oxidizing sea-water penetrating the crust on the ridge flanks becomes heated and evolves into a highly reduced somewhat acidic hydrothermal solvent during interaction with basaltic wall-rock. Depending on the temperature and water/rock ratio, this fluid is capable of leaching and transporting iron, manganese, and base metals; dissolved sea-water sulphate is reduced to sulphide. At the ridge axis, the buoyant hydrothermal fluid rises through permeable wall-rocks, and fluid flow may be focussed along deep-seated fractures related to extensional tectonic processes. Metal sulphides are precipitated along channelways as the ascending fluid undergoes adiabatic expansion and then further cooling during mixing with ambient sub-sea-floor water. Vigorous fluid flow results in venting of reduced fluid at the sea-floor/sea-water interface and deposition of massive sulphide. A comparison of sulphide mineralization and wall-rock alteration in ancient and modern spreading centre environments supports this genetic concept. Massive sulphide deposits in ophiolites generally occur in clusters of closely spaced (< 1-5 km) deposits. Individual deposits are a composite of syngenetic massive sulphide and underlying epigenetic stockwork-vein mineralization. The massive sulphide occurs as concordant tabular

  17. The truth about silver.

    PubMed

    Ovington, Liza G

    2004-09-01

    Interest in silver as a topical agent in wound healing is undergoing a renaissance. Having basic information regarding silver's chemical properties and potential actions in the wound bed is important to its appropriate clinical use. Such information is also relevant to the interpretation of silver's in vitro antimicrobial (antiseptic) effects, which in turn relate to issues involved in the evaluation of the clinical effects of silver in vivo. Gaining an understanding of the basic science of silver products and the different challenges inherent to in vitro versus in vivo antimicrobial evaluations will allow clinicians to address several key questions inherent when considering the use of silver as a topical antimicrobial: 1) Are there different forms of silver? 2) How does the amount of silver released into the wound environment correlate with clinical benefit? 3) How does the rate of silver release correlate with clinical benefit?

  18. Utilization of water-reducing admixtures in cemented paste backfill of sulphide-rich mill tailings.

    PubMed

    Ercikdi, Bayram; Cihangir, Ferdi; Kesimal, Ayhan; Deveci, Haci; Alp, Ibrahim

    2010-07-15

    This study presents the effect of three different water-reducing admixtures (WRAs) on the rheological and mechanical properties of cemented paste backfill (CPB) samples. A 28-day strength of > or = 0.7 MPa and the maintenance of the stability (i.e. > or = 0.7 MPa) over 360 days of curing were desired as the design criteria. Ordinary Portland cement (OPC) and Portland composite cement (PCC) were used as binders at 5 wt.% dose. WRAs were initially tested to determine the dosage of a WRA for a required consistency of 7'' for CPB mixtures. A total of 192 CPB samples were then prepared using WRAs. The utilization of WRAs enhanced the flow characteristics of the CPB mixture and allowed to achieve the same consistency at a lower water-to-cement ratio. For OPC, the addition of WRAs appeared to improve the both short- and long-term performance of CPB samples. However, only polycarboxylate-based superplasticiser produced the desired 28-day strength of > or = 0.7 MPa when PCC was used as the binder. These findings suggest that WRAs can be suitably exploited for CPB of sulphide-rich tailings to improve the strength and stability in short and long terms allowing to reduce binder costs in a CPB plant.

  19. Inorganic Nanoparticle-Modified Poly(Phenylene Sulphide)/Carbon Fiber Laminates: Thermomechanical Behaviour

    PubMed Central

    Díez-Pascual, Ana M.; Naffakh, Mohammed

    2013-01-01

    Carbon fiber (CF)-reinforced high-temperature thermoplastics such as poly(phenylene sulphide) (PPS) are widely used in structural composites for aerospace and automotive applications. The porosity of CF-reinforced polymers is a very important topic for practical applications since there is a direct correlation between void content and mechanical properties. In this study, inorganic fullerene-like tungsten disulphide (IF-WS2) lubricant nanoparticles were used to manufacture PPS/IF-WS2/CF laminates via melt-blending and hot-press processing, and the effect of IF-WS2 loading on the quality, thermal and mechanical behaviour of the hybrid composites was investigated. The addition of IF-WS2 improved fiber impregnation, resulting in lower degree of porosity and increased delamination resistance, compression and flexural properties; their reinforcement effect was greater at temperatures above the glass transition (Tg). IF-WS2 contents higher than 0.5 wt % increased Tg and the heat deflection temperature while reduced the coefficient of thermal expansion. The multiscale laminates exhibited higher ignition point and notably reduced peak heat release rate compared to PPS/CF. The coexistence of micro- and nano-scale fillers resulted in synergistic effects that enhanced the stiffness, strength, thermal conductivity and flame retardancy of the matrix. The results presented herein demonstrate that the IF-WS2 are very promising nanofillers to improve the thermomechanical properties of conventional thermoplastic/CF composites. PMID:28811429

  20. Inorganic Nanoparticle-Modified Poly(Phenylene Sulphide)/ Carbon Fiber Laminates: Thermomechanical Behaviour.

    PubMed

    Díez-Pascual, Ana M; Naffakh, Mohammed

    2013-07-26

    Carbon fiber (CF)-reinforced high-temperature thermoplastics such as poly(phenylene sulphide) (PPS) are widely used in structural composites for aerospace and automotive applications. The porosity of CF-reinforced polymers is a very important topic for practical applications since there is a direct correlation between void content and mechanical properties. In this study, inorganic fullerene-like tungsten disulphide (IF-WS₂) lubricant nanoparticles were used to manufacture PPS/IF-WS₂/CF laminates via melt-blending and hot-press processing, and the effect of IF-WS₂ loading on the quality, thermal and mechanical behaviour of the hybrid composites was investigated. The addition of IF-WS₂ improved fiber impregnation, resulting in lower degree of porosity and increased delamination resistance, compression and flexural properties; their reinforcement effect was greater at temperatures above the glass transition (Tg). IF-WS₂ contents higher than 0.5 wt % increased Tg and the heat deflection temperature while reduced the coefficient of thermal expansion. The multiscale laminates exhibited higher ignition point and notably reduced peak heat release rate compared to PPS/CF. The coexistence of micro- and nano-scale fillers resulted in synergistic effects that enhanced the stiffness, strength, thermal conductivity and flame retardancy of the matrix. The results presented herein demonstrate that the IF-WS₂ are very promising nanofillers to improve the thermomechanical properties of conventional thermoplastic/CF composites.

  1. Solid Carbonyl Sulphide (OCS) in W33A

    NASA Technical Reports Server (NTRS)

    Palumbo, M. E.; Tielens, A. G. G. M.; Tokunaga, A. T.

    1995-01-01

    We present ground-based observations of the 2041 cm(exp -1) (4.9 mm) absorption feature toward the deeply embedded protostar W33A. We attribute this interstellar feature to solid carbonyl sulphide (OCS) embedded in icy grain mantles along the line of sight. We have made an extensive laboratory study of the infrared characteristics of OCS in various ice mixtures. Studies of the 2041 cm(exp -1) band of solid OCS and solid mixtures containing OCS show that its shape and peak position are sensitive to the molecular environment of the OCS molecule. Mie scattering calculations show that the peak position and profile of the OCS band depend on the shape and size of the absorbing grain when the OCS concentration is larger than 0.05. For lower OCS concentrations, laboratory-measured bulk spectra agree very well with the absorption spectra of small grains. We have compared the observed feature with laboratory and theoretical spectra of astrophysically relevant mixtures. The best agreement is obtained for mixtures with traces of OCS in a methanol-rich matrix. This would suggest the presence of independent grain components and in particular of a minor fraction of methanol-rich icy grain mantles in which OCS is embedded. From the strength of the absorption feature we deduce a OCS/H2O ratio, along the line of sight, of 4 x 10(exp -4).

  2. High olfactory sensitivity for dimethyl sulphide in harbour seals

    PubMed Central

    Kowalewsky, Sylvia; Dambach, Martin; Mauck, Björn; Dehnhardt, Guido

    2005-01-01

    Productive areas are patchily distributed at sea and represent important feeding grounds for many marine organisms. Although pinnipeds are known to travel on direct routes and return regularly to particular feeding sites, the environmental information seals use to perform this navigation is as yet unknown. As atmospheric dimethyl sulphide (DMS) has been demonstrated to be a reliable indicator for profitable foraging areas, we tested seals for their ability to smell DMS at concentrations typical for the marine environment. Using a go/no-go response paradigm we determined the DMS detection threshold in two harbour seals (Phoca vitulina vitulina). DMS stimuli from 8.05×108 to 8 pmol (DMS) m−3(air) were tested against a control stimulus using a custom-made olfactometer. DMS-thresholds determined for both seals (20 and 13 pmol m−3) indicate that seals can detect ambient concentrations associated with high primary productivity, e.g. in the North Atlantic. Thus, seals possess an extraordinarily high olfactory sensitivity for DMS, which could provide a sensory basis for identifying or orienting to profitable foraging grounds. PMID:17148339

  3. Biological removal of dimethyl sulphide from sea water

    NASA Astrophysics Data System (ADS)

    Kiene, Ronald P.; Bates, Timothy S.

    1990-06-01

    DIMETHYL sulphide (DMS) is an important sulphur-containing trace gas in the atmosphere. It is present in oceanic surface waters at concentrations sufficient to sustain a considerable net flux of DMS from the oceans to the atmosphere, estimated to comprise nearly half of the global biogenic input of sulphur to the atmosphere1. DMS emitted from the oceans may be a precursor of tropospheric aerosols and of cloud condensation nuclei in the remote marine atmosphere, thereby affecting the Earth's radiative balance and thus its climate2-4. Relatively little is known, however, about the biogeochemical and physical processes that control the concentration of DMS in sea water. Here we present data from incubation experiments, carried out at sea, which show that DMS is removed by microbial activity. In the eastern, tropical Pacific Ocean, DMS turnover is dominated by biological processes, with turnover times for biological DMS removal generally more than ten (3-430) times faster than turnover by ventilation to the atmosphere. Thus biological consumption of DMS seems to be a more important factor than atmospheric exchange in controlling DMS concentrations in the ocean, and hence its flux to the atmosphere. These results have significant implications for climate feedback models involving DMS emissions3, and highlight the importance of the microbial food web in oceanic DMS cycling.

  4. Penguins are attracted to dimethyl sulphide at sea.

    PubMed

    Wright, Kyran L B; Pichegru, Lorien; Ryan, Peter G

    2011-08-01

    Breeding Spheniscus penguins are central place foragers that feed primarily on schooling pelagic fish. They are visual hunters, but it is unclear how they locate prey patches on a coarse scale. Many petrels and storm petrels (Procellariiformes), the penguins' closest relatives, use olfactory cues to locate prey concentrations at sea, but this has not been demonstrated for penguins. Procellariiforms are attracted to a variety of olfactory cues, including dimethyl sulphide (DMS), an organosulphur compound released when phytoplankton is grazed, as well as fish odorants such as cod liver oil. A recent study found that African penguins Spheniscus demersus react to DMS on land. We confirm this result and show that African penguins are also attracted by DMS at sea. DMS-scented oil slicks attracted 2-3 times more penguins than control slicks, whereas penguins showed no response to slicks containing cod liver oil. The number of penguins attracted to DMS increased for at least 30 min, suggesting penguins could travel up to 2 km to reach scent cues. Repeats of land-based trials confirmed previous results showing DMS sensitivity of penguins on land. Our results also support the hypothesis that African penguins use DMS as an olfactory cue to locate prey patches at sea from a distance, which is particularly important given their slow commuting speed relative to that of flying seabirds.

  5. Synthesis of copper sulphide nanoparticles in carboxylic acids as solvent.

    PubMed

    Armelao, Lidia; Camozzo, Daniele; Gross, Silvia; Tondello, Eugenio

    2006-02-01

    A novel method for the preparation of CuS nanoparticles based on the fast nucleation of the sulphide has been developed. The particles have been synthesized by reaction of thioacetic acid with water and copper carboxylates (acetate, propionate) in the corresponding carboxylic acid (acetic, propionic) as a solvent. The use of carboxylic acids presents several advantages: (i) the hydrolysis of the C-S bond is favoured thus producing a fast CuS supersaturation and a high nucleation rate; (ii) the mobility of the precursor molecules is limited so that nucleation events are favoured with respect to particle growth; (iii) the low dielectric constant of the medium stabilises the nanoparticles dispersion by reducing the critical coagulation concentration. The prepared nanoparticles were investigated by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and dynamic light scattering. The nanoparticle suspensions are clear and characterized by a blue-shifted adsorption edge with respect to bulk CuS. Light scattering measurements performed on acetic acid suspensions evidence the formation of monodispersed nanoparticles with an average diameter of about 5 nm.

  6. Multi-level assemblies of lead sulphide nanorods.

    PubMed

    Lu, Qingyi; Gao, Feng; Komarneni, Sridhar

    2006-05-28

    A new concept of multi-level assemblies of nanorod-based structures has been proposed, which could give new insight into the construction of nanorod-based complex structures from the bottom up. Multi-level architectures of complex lead sulphide (PbS) nanorod-based structures have been realized by a simple and general amino acid-mediated approach. First-level structure (multi-arm horn-like structure), second-level structure (bi-pyramid structure formed by several horn-like structures), and third-level structure (multi-pyramid structure formed by several pyramid-like structures) can be synthesized with the assistance of different amino acids: aspartic acid, serine, and histidine, respectively. The amino acids have several functional groups, such as -NH(2) and -COOH, which have strong abilities for coordination with the metal ions, and might provide reaction sites by coordinating with metal ions to initiate and then confine the assemblies of the PbS nanorods. This amino acid-mediated method provides a possibility of studying the formation and assembly mechanisms from the bottom up and might open a door to constructing complex nanorod-based structures at different levels.

  7. Dolomite limits acidification of a biofilter degrading dimethyl sulphide

    PubMed

    Smet; Van Langenhove H; Philips

    1999-01-01

    The applicability of dolomite particles to control acidification in a Hyphomicrobium MS3 inoculated biofilter removing dimethyl sulphide (Me2S) was studied. While direct inoculation of the dolomite particles with the liquid microbial culture was not successful, start-up of Me2S-degradation in the biofilter was observed when the dolomite particles were mixed with 33% (wt/wt) of Hyphomicrobium MS3-inoculated compost or wood bark material. Under optimal conditions, an elimination capacity (EC) of 1680 g Me2S m(-3) d(-1) was obtained for the compost/dolomite biofilter. Contrary to a wood bark or compost biofilter, no reduction in activity due to acidification was observed in these biofilters over a 235 day period because of the micro environment neutralisation of the microbial metabolite H2SO4 with the carbonate in the dolomite material. However, performance of the biofilter decreased when the moisture content of the mixed compost/dolomite material dropped below 15%. Next to this, nutrient limitation resulted in a gradual decrease of the EC and supplementation of a nitrogen source was a prerequisite to obtain a long-term high EC (> 250 g Me2S m(-3) d(-1)) for Me2S. In relation to this nitrogen supplementation, it was observed that stable ECs for Me2S were obtained when this nutrient was dosed to the biofilter at a Me2S-C/NH4Cl-N ratio of about 10.

  8. Controlling fires in silver/zinc batteries

    NASA Technical Reports Server (NTRS)

    Boshers, W. A.; Britz, W. A.

    1977-01-01

    Silver/zinc storage battery fires are often difficult to extinguish. Improved technique employs manifold connected to central evacuation chamber to rapidly vent combustion-supporting gases generated by battery plate oxides.

  9. Silver manganese oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2006-05-09

    This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

  10. Durable silver coating for mirrors

    DOEpatents

    Wolfe, Jesse D.; Thomas, Norman L.

    2000-01-01

    A durable multilayer mirror includes reflective layers of aluminum and silver and has high reflectance over a broad spectral range from ultraviolet to visible to infrared. An adhesion layer of a nickel and/or chromium alloy or nitride is deposited on an aluminum surface, and a thin layer of silver is then deposited on the adhesion layer. The silver layer is protected by a passivation layer of a nickel and/or chromium alloy or nitride and by one or more durability layers made of metal oxides and typically a first layer of metal nitride. The durability layers may include a composite silicon aluminum nitride and an oxinitride transition layer to improve bonding between nitride and oxide layers.

  11. Silver Dissolution and Release from Ceramic Water Filters.

    PubMed

    Mittelman, Anjuliee M; Lantagne, Daniele S; Rayner, Justine; Pennell, Kurt D

    2015-07-21

    Application of silver nanoparticles (nAg) or silver nitrate (AgNO3) has been shown to improve the microbiological efficacy of ceramic water filters used for household water treatment. Silver release, however, can lead to undesirable health effects and reduced filter effectiveness over time. The objectives of this study were to evaluate the contribution of nanoparticle detachment, dissolution, and cation exchange to silver elution, and to estimate silver retention under different influent water chemistries. Dissolved silver (Ag(+)) and nAg release from filter disks painted with 0.03 mg/g casein-coated nAg or AgNO3 were measured as a function of pH (5-9), ionic strength (1-50 mM), and cation species (Na(+), Ca(2+), Mg(2+)). Silver elution was controlled by dissolution as Ag(+) and subsequent cation exchange reactions regardless of the applied silver form. Effluent silver levels fell below the drinking water standard (0.1 mg/L) after flushing with 30-42 pore volumes of pH 7, 10 mM NaNO3 at pH 7. When the influent water was at pH 5, contained divalent cations or 50 mM NaNO3, silver concentrations were 5-10 times above the standard. Our findings support regular filter replacement and indicate that saline, hard, or acidic waters should be avoided to minimize effluent silver concentrations and preserve silver treatment integrity.

  12. Mineral sulphide-lime reactions and effect of CaO/C mole ratio during carbothermic reduction of complex mineral sulphides

    NASA Astrophysics Data System (ADS)

    Hara, Yotamu Stephen Rainford

    2014-01-01

    Mineral sulphide (MS)-lime (CaO) ion exchange reactions (MS + CaO = MO + CaS) and the effect of CaO/C mole ratio during carbothermic reduction (MS + CaO + C = M + CaS + CO(g)) were investigated for complex froth flotation mineral sulphide concentrates. Phases in the partially and fully reacted samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The primary phases during mineral sulphide-lime ion exchange reactions are Fe3O4, CaSO4 Cu2S, and CaS. A complex liquid phase of Ca2CuFeO3S forms during mineral sulphide-lime exchange reactions above 1173 K. The formation mechanisms of Ca2CuFeO3S liquid phase are determined by characterising the partially reacted samples. The reduction rate and extent of mineral sulphides in the presence of CaO and C increase with the increase in CaO/C ratio. The metallic phases are surrounded by the CaS rich phase at CaO/C > 1, but the metallic phases and CaS are found as separate phases at CaO/C < 1. Experimental results show that the stoichiometric ratio of carbon should be slightly higher than that of CaO. The reactions between CaO and gangue minerals (SiO2 and Al2O3) are only observed at CaO/C > 1 and the reacted samples are excessively sintered.

  13. Improvement on electrical properties of screen-printed silicon solar cells by light-induced electroplating of silver

    NASA Astrophysics Data System (ADS)

    Li, Tao; Wang, Wenjing

    2016-10-01

    The total power losses are analyzed based on two-layer electrode of light-induced electroplating after screen printing. By the introduction of scale factor in the calculation, optical losses are closer to the actual condition. Optimized two-layer contact of front side could diminish power losses distinctly and improve the current-voltage (I-V) characteristic of crystalline silicon solar cells. The relative increments of I-V parameters as a function of electroplating time are measured. The quantitative comparison of analytical results between half-ellipse shape model and half-circled shape model is performed. The numerical simulation results and experimental data show good agreement. Due to the successful verification, the simulation results could be used to optimize the two-layer electrode structure and light-induced electroplating process.

  14. The Silver Halides

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1977-01-01

    Illustrates the type of fractional bonding for solid silver halides. Treats the silver halides as electron excess compounds, and develops a model of a localized bonding unit that may be iterated in three dimensions to describe the bulk phase. (MLH)

  15. Colloidal Silver Products

    MedlinePlus

    ... can be dangerous to your health. What the Science Says About the Safety and Side Effects of ... homemade and commercial colloidal silver products. What the Science Says About the Effectiveness of Colloidal Silver Scientific ...

  16. From lithotroph- to organotroph-dominant: directional shift of microbial community in sulphidic tailings during phytostabilization

    PubMed Central

    Li, Xiaofang; Bond, Philip L.; Van Nostrand, Joy D.; Zhou, Jizhong; Huang, Longbin

    2015-01-01

    Engineering microbial diversity to enhance soil functions may improve the success of direct revegetation in sulphidic mine tailings. Therefore, it is essential to explore how remediation and initial plant establishment can alter microbial communities, and, which edaphic factors control these changes under field conditions. A long-term revegetation trial was established at a Pb-Zn-Cu tailings impoundment in northwest Queensland. The control and amended and/or revegetated treatments were sampled from the 3-year-old trial. In total, 24 samples were examined using pyrosequencing of 16S rRNA genes and various chemical properties. The results showed that the microbial diversity was positively controlled by soil soluble Si and negatively controlled by soluble S, total Fe and total As, implying that pyrite weathering posed a substantial stress on microbial development in the tailings. All treatments were dominated by typical extremophiles and lithotrophs, typically Truepera, Thiobacillus, Rubrobacter; significant increases in microbial diversity, biomass and frequency of organotrophic genera (typically Nocardioides and Altererythrobacter) were detected in the revegetated and amended treatment. We concluded that appropriate phytostabilization options have the potential to drive the microbial diversity and community structure in the tailings toward those of natural soils, however, inherent environmental stressors may limit such changes. PMID:26268667

  17. Interface and properties of inorganic fullerene tungsten sulphide nanoparticle reinforced poly (ether ether ketone) nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Nannan; Yang, Zhuxian; Wang, Yuan; Thummavichai, Kunyapat; Xia, Yongde; Ghita, Oana; Zhu, Yanqiu

    We report a simple and effective method to fabricate PEEK (poly ether ether ketone)/IF-WS2 (Inorganic Fullerene Tungsten Sulphide) nanocomposites with IF-WS2 content up to 8 wt%. We have used electron microscopies to characterise the morphology and structural features of the nancomposites, and FTIR and XPS to show that some chemical interface bondings were formed between the PEEK and IF-WS2. We demonstrate that the resulting PEEK/IF-WS2 nanocomposites showed an extraordinary 190% increase in thermal conductivity, 50 °C higher in degradation temperature, and mild improvements in strength and hardness. The increased degradation activation energy from 64 to 76 kJ/mol for neat PEEK and PEEK/IF-WS2 nanocomposites, respectively, is attributed to the synergistic interface between the PEEK matrix and IF-WS2 nanoparticles. The enhancements in both the mechanical and thermal properties will significantly expand the capacities of PEEK-based nanocomposites towards applications where thermal conductivity and stability are important.

  18. From lithotroph- to organotroph-dominant: directional shift of microbial community in sulphidic tailings during phytostabilization

    NASA Astrophysics Data System (ADS)

    Li, Xiaofang; Bond, Philip L.; van Nostrand, Joy D.; Zhou, Jizhong; Huang, Longbin

    2015-08-01

    Engineering microbial diversity to enhance soil functions may improve the success of direct revegetation in sulphidic mine tailings. Therefore, it is essential to explore how remediation and initial plant establishment can alter microbial communities, and, which edaphic factors control these changes under field conditions. A long-term revegetation trial was established at a Pb-Zn-Cu tailings impoundment in northwest Queensland. The control and amended and/or revegetated treatments were sampled from the 3-year-old trial. In total, 24 samples were examined using pyrosequencing of 16S rRNA genes and various chemical properties. The results showed that the microbial diversity was positively controlled by soil soluble Si and negatively controlled by soluble S, total Fe and total As, implying that pyrite weathering posed a substantial stress on microbial development in the tailings. All treatments were dominated by typical extremophiles and lithotrophs, typically Truepera, Thiobacillus, Rubrobacter; significant increases in microbial diversity, biomass and frequency of organotrophic genera (typically Nocardioides and Altererythrobacter) were detected in the revegetated and amended treatment. We concluded that appropriate phytostabilization options have the potential to drive the microbial diversity and community structure in the tailings toward those of natural soils, however, inherent environmental stressors may limit such changes.

  19. Performance of activated sludge diffusion for biological treatment of hydrogen sulphide gas emissions.

    PubMed

    Barbosa, Vera L; Stuetz, Richard M

    2013-01-01

    Odours from wastewater treatment plants are comprised of a mixture of various gases with hydrogen sulphide (H(2)S) often being the dominant constituent. Activated sludge diffusion (ASD) as a biotreatment system for odour abatement has been conducted for over 30 years but has limited broad application due to disagreement in the literature regarding the effect that ASD may have on wastewater treatment performance. The effects of continuous H(2)S diffusion at 25 ppmv, with weekly peaks of approximately 100 ppmv, on H(2)S removal efficiency and wastewater treatment performance was evaluated over a 2-month period using an activated sludge pilot plant. H(2)S removal averaged 100% during diffusion at 25 ppmv, and 98.9% during the 100 ppmv peak periods. A significant increase in mixed liquor volatile suspended solids concentration (P < 0.01) was observed during H(2)S diffusion, which may be due to an increase in H(2)S-degrading microorganisms. There was no adverse effect of H(2)S on nitrification throughout the ASD trials. Ammonia (NH(3)) removal was slightly better in the test receiving H(2)S diffusion (87.6%) than in the control (85.4%). H(2)S diffusion appeared to improve robustness of the AS biomass to operational upsets.

  20. Silver-plated carbon nanotubes for silver/conducting polymer composites.

    PubMed

    Oh, Youngseok; Suh, Daewoo; Kim, Youngjin; Lee, Eungsuek; Mok, Jee Soo; Choi, Jaeboong; Baik, Seunghyun

    2008-12-10

    Carbon nanotubes (CNTs) have advantages as conductive fillers due to their large aspect ratio and excellent conductivity. In this study, a novel silver/conducting polymer composite was developed by the incorporation of silver-plated CNTs. It is important to achieve a homogeneous dispersion of nanotubes and to improve the interfacial bonding to utilize the excellent properties of reinforcements in the matrix material. The homogeneous dispersion of nanotubes was achieved by an acid treatment process, and the interfacial contact was improved by electroless silver plating around nanotubes. The resistivity of the silver/conducting polymer composite was decreased by 83% by the addition of silver-plated single-walled carbon nanotubes. Conductive bumps were also screen-printed to demonstrate the capability of the composite as electrical interconnects for multi-layer printed circuit boards.

  1. Silver-plated carbon nanotubes for silver/conducting polymer composites

    NASA Astrophysics Data System (ADS)

    Oh, Youngseok; Suh, Daewoo; Kim, Youngjin; Lee, Eungsuek; Mok, Jee Soo; Choi, Jaeboong; Baik, Seunghyun

    2008-12-01

    Carbon nanotubes (CNTs) have advantages as conductive fillers due to their large aspect ratio and excellent conductivity. In this study, a novel silver/conducting polymer composite was developed by the incorporation of silver-plated CNTs. It is important to achieve a homogeneous dispersion of nanotubes and to improve the interfacial bonding to utilize the excellent properties of reinforcements in the matrix material. The homogeneous dispersion of nanotubes was achieved by an acid treatment process, and the interfacial contact was improved by electroless silver plating around nanotubes. The resistivity of the silver/conducting polymer composite was decreased by 83% by the addition of silver-plated single-walled carbon nanotubes. Conductive bumps were also screen-printed to demonstrate the capability of the composite as electrical interconnects for multi-layer printed circuit boards.

  2. Improving the antibacterial property of porcine small intestinal submucosa by nano-silver supplementation: a promising biological material to address the need for contaminated defect repair.

    PubMed

    Zhou, Hai Yang; Zhang, Jian; Yan, Rong Lin; Wang, Qiang; Fan, Lie Ying; Zhang, Qi; Wang, Wei Jun; Hu, Zhi Qian

    2011-05-01

    We hypothesize that introduction of nano-silver particles to porcine-derived small intestinal submucosa (NS-PSIS) would lead to significant enhancement in antibacterial property in repairing contaminated abdominal defect. Porcine-derived small intestinal submucosa (PSIS) is an acellular and xenogenic biological material intensively used in repairing and regenerating wounded and dysfunctional tissues. Surgical site infection (SSI) remains so far a serious problem and major challenge, particularly in contaminated tissue-deficient repairing. Self-assembly was used to fabricate NS-PSIS. The antibacterial property was evaluated in vitro and in vivo by means of repairing full-thickness contaminated abdominal defect in rats. The native PSIS and polypropylene-oxidized regenerated cellulose were served as controls. In addition, changes in biomechanical resistance, morphology and immunohistochemistry for inflammatory reaction and neovasculation in the repaired abdominal wall were analyzed. Biosafety was investigated by pyrogen test, skin irritation test and silver measurement in vivo. NS-PSIS exhibited strong antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa on agar diffusion, with mean diameters of inhibition zone ranging from 11.9 to 23.5 mm. There were significantly lower SSI incidence and a tendency of better abdominal wall resistance in the NS-PSIS group as compared with the PSIS or polypropylene-oxidized regenerated cellulose group after repairing contaminated abdominal defect in rats. Nano-silver modified PSIS did not change the native PSIS property in the tissue recolonization, remodeling and neovascularization. NS-PSIS was not pyrogenic or skin irritated, without silver residual in vivo after repairing contaminated abdominal defect. Nano-silver particles to PSIS lead to significant enhancements in antibacterial property in vitro and in vivo without decreasing its biomechanical resistance

  3. Polyimides Containing Silver Trifluoroacetylacetonate

    NASA Technical Reports Server (NTRS)

    Stoakley, Diane M.; St. Clair, Anne K.; Rancourt, James D.; Taylor, Larry T.; Caplan, Maggie L.

    1994-01-01

    Mechanically strong, flexible, thermally stable, electrically conductive films and coatings suitable for use in electronics industry made by incorporating silver trifluoroacetylacetonate into linear aromatic condensation polyimides. In experimental films, most successful combinations of flexibility and conductivity obtained by use of 1:1, 1:1.74, and 1:2 mole ratios of silver trifluoroacetylacetonate per polyimide repeat unit. Other concentrations of silver trifluoroacetylacetonate used with different heat-treatment schedules to obtain conductive silver-impregnated films.

  4. Plasmonic light trapping in thin-film silicon solar cells with improved self-assembled silver nanoparticles.

    PubMed

    Tan, Hairen; Santbergen, Rudi; Smets, Arno H M; Zeman, Miro

    2012-08-08

    Plasmonic metal nanoparticles are of great interest for light trapping in thin-film silicon solar cells. In this Letter, we demonstrate experimentally that a back reflector with plasmonic Ag nanoparticles can provide light-trapping performance comparable to state-of-the-art random textures in n-i-p amorphous silicon solar cells. This conclusion is based on the comparison to high performance n-i-p solar cell and state-of-the-art efficiency p-i-n solar cells deposited on the Asahi VU-type glass. With the plasmonic back reflector a gain of 2 mA/cm(2) in short-circuit current density was obtained without any deterioration of open circuit voltage or fill factor compared to the solar cell on a flat back reflector. The excellent light trapping is a result of strong light scattering and low parasitic absorption of self-assembled Ag nanoparticles embedded in the back reflector. The plasmonic back reflector provides a high degree of light trapping with a haze in reflection greater than 80% throughout the wavelength range 520-1100 nm. The high performance of plasmonic back reflector is attributed to improvements in the self-assembly technique, which result in a lower surface coverage and fewer small and irregular nanoparticles.

  5. Sulphide effects on the physiology of Candidatus Accumulibacter phosphatis type I.

    PubMed

    Rubio-Rincón, F J; Lopez-Vazquez, C M; Welles, L; van Loosdrecht, M C M; Brdjanovic, D

    2017-02-01

    Sulphate-rich wastewaters can be generated due to (i) use of saline water as secondary-quality water for sanitation in urban environments (e.g. toilet flushing), (ii) discharge of industrial effluents, (iii) sea and brackish water infiltration into the sewage and (iv) use of chemicals, which contain sulphate, in drinking water production. In the presence of an electron donor and absence of oxygen or nitrate, sulphate can be reduced to sulphide. Sulphide can inhibit microbial processes in biological wastewater treatment systems. The objective of the present study was to assess the effects of sulphide concentration on the anaerobic and aerobic physiology of polyphosphate-accumulating organisms (PAOs). For this purpose, a PAO culture, dominated by Candidatus Accumulibacter phosphatis clade I (PAO I), was enriched in a sequencing batch reactor (SBR) fed with acetate and propionate. To assess the direct inhibition effects and their reversibility, a series of batch activity tests were conducted during and after the exposure of a PAO I culture to different sulphide concentrations. Sulphide affected each physiological process of PAO I in a different manner. At 189 mg TS-S/L, volatile fatty acid uptake was 55% slower and the phosphate release due to anaerobic maintenance increased from 8 to 18 mg PO4-P/g VSS/h. Up to 8 mg H2S-S/L, the decrease in aerobic phosphorus uptake rate was reversible (Ic60). At higher concentrations of sulphide, potassium (>16 mg H2S-S/L) and phosphate (>36 mg H2S-S/L) were released under aerobic conditions. Ammonia uptake, an indicator of microbial growth, was not observed at any sulphide concentration. This study provides new insights into the potential failure of enhanced biological phosphorus removal sewage plants receiving sulphate- or sulphide-rich wastewaters when sulphide concentrations exceed 8 mg H2S-S/L, as PAO I could be potentially inhibited.

  6. Laboratory assessment of bioproducts for sulphide and methane control in sewer systems.

    PubMed

    Sudarjanto, Gatut; Gutierrez, Oriol; Ren, Guo; Yuan, Zhiguo

    2013-01-15

    The effectiveness of three bioproducts (also known as biomaterials) for liquid-phase biological treatment (LPBT) of sewer biofilms to control detrimental build-up of sulphide (H(2)S) and methane (CH(4)) in sewers was tested in a laboratory system mimicking a rising/force main sewer pipe. Bioproduct A claims to disrupt cell-to-cell communication of sewer anaerobic biofilms while Bioproducts B and C claim to enhance sulphidotrophic (sulphide-oxidising) capacity of the sewer biofilm, to avoid sulphide accumulation. The results demonstrated that all three bioproducts tested had no or negligible impact on sulphide or methane control, as opposed to traditional sulphide-controlling chemicals widely used by the wastewater industry such as oxygen, nitrate, iron salts and magnesium hydroxide. Those had previously been demonstrated to be effective using the same laboratory system with the same testing protocol. The implications of the findings are discussed. It is concluded that field application/trials of these three bioproducts are not warranted. It is recommended that other bioproducts should be subject to similar rigorous tests prior to being taken up by the water industry for field trials/application.

  7. Minimising hydrogen sulphide generation during steam assisted production of heavy oil

    PubMed Central

    Montgomery, Wren; Sephton, Mark A.; Watson, Jonathan S.; Zeng, Huang; Rees, Andrew C.

    2015-01-01

    The majority of global petroleum is in the form of highly viscous heavy oil. Traditionally heavy oil in sands at shallow depths is accessed by large scale mining activities. Recently steam has been used to allow heavy oil extraction with greatly reduced surface disturbance. However, in situ thermal recovery processes can generate hydrogen sulphide, high levels of which are toxic to humans and corrosive to equipment. Avoiding hydrogen sulphide production is the best possible mitigation strategy. Here we use laboratory aquathermolysis to reproduce conditions that may be experienced during thermal extraction. The results indicate that hydrogen sulphide generation occurs within a specific temperature and pressure window and corresponds to chemical and physical changes in the oil. Asphaltenes are identified as the major source of sulphur. Our findings reveal that for high sulphur heavy oils, the generation of hydrogen sulphide during steam assisted thermal recovery is minimal if temperature and pressure are maintained within specific criteria. This strict pressure and temperature dependence of hydrogen sulphide release can allow access to the world's most voluminous oil deposits without generating excessive amounts of this unwanted gas product. PMID:25670085

  8. Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae).

    PubMed

    Lebata, M J

    2001-11-01

    Oxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured. Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each. Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final). Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each. Ammonia, NO2 and P04 were measured at days 0 (initial) 3, 6, 9 and 12 (final). Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001). A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments. A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3.

  9. Minimising hydrogen sulphide generation during steam assisted production of heavy oil

    NASA Astrophysics Data System (ADS)

    Montgomery, Wren; Sephton, Mark A.; Watson, Jonathan S.; Zeng, Huang; Rees, Andrew C.

    2015-02-01

    The majority of global petroleum is in the form of highly viscous heavy oil. Traditionally heavy oil in sands at shallow depths is accessed by large scale mining activities. Recently steam has been used to allow heavy oil extraction with greatly reduced surface disturbance. However, in situ thermal recovery processes can generate hydrogen sulphide, high levels of which are toxic to humans and corrosive to equipment. Avoiding hydrogen sulphide production is the best possible mitigation strategy. Here we use laboratory aquathermolysis to reproduce conditions that may be experienced during thermal extraction. The results indicate that hydrogen sulphide generation occurs within a specific temperature and pressure window and corresponds to chemical and physical changes in the oil. Asphaltenes are identified as the major source of sulphur. Our findings reveal that for high sulphur heavy oils, the generation of hydrogen sulphide during steam assisted thermal recovery is minimal if temperature and pressure are maintained within specific criteria. This strict pressure and temperature dependence of hydrogen sulphide release can allow access to the world's most voluminous oil deposits without generating excessive amounts of this unwanted gas product.

  10. Minimising hydrogen sulphide generation during steam assisted production of heavy oil.

    PubMed

    Montgomery, Wren; Sephton, Mark A; Watson, Jonathan S; Zeng, Huang; Rees, Andrew C

    2015-02-11

    The majority of global petroleum is in the form of highly viscous heavy oil. Traditionally heavy oil in sands at shallow depths is accessed by large scale mining activities. Recently steam has been used to allow heavy oil extraction with greatly reduced surface disturbance. However, in situ thermal recovery processes can generate hydrogen sulphide, high levels of which are toxic to humans and corrosive to equipment. Avoiding hydrogen sulphide production is the best possible mitigation strategy. Here we use laboratory aquathermolysis to reproduce conditions that may be experienced during thermal extraction. The results indicate that hydrogen sulphide generation occurs within a specific temperature and pressure window and corresponds to chemical and physical changes in the oil. Asphaltenes are identified as the major source of sulphur. Our findings reveal that for high sulphur heavy oils, the generation of hydrogen sulphide during steam assisted thermal recovery is minimal if temperature and pressure are maintained within specific criteria. This strict pressure and temperature dependence of hydrogen sulphide release can allow access to the world's most voluminous oil deposits without generating excessive amounts of this unwanted gas product.

  11. Investigation of hydrogen sulphide eruptions along the Namibian coastline using different remote sensing systems

    NASA Astrophysics Data System (ADS)

    Ohde, Thomas

    2009-09-01

    Hydrogen sulphide eruptions with their typical turquoise discolorations at the water surface are a unique phenomenon along the Namibian coastline. The remote sensing techniques of ocean colour sensors and microwave scatterometers were used for the investigation of such events. The studies with ocean colour sensors showed that the turquoise discolorations near the Namibian coast were neither linked to dust deposition into the water column by desert storms nor to the reflection of bright material in shallow water areas. In addition, other coloured marine events like algae blooms and river outflows were differentiable from the hydrogen sulphide eruptions by their special optical properties. Quasi-true colour images and spectral identification methods were utilised to monitor and investigate the spatial and temporal distribution of sulphide events. In the past years, they were sometimes and locally limited discovered. Newest remote sensing observations including our own investigations have established that the occurrence of sulphide events is more frequent and longer lasting. The north-westerly direction of propagation and their velocity between 12 cm s-1 and 15 cm s1 were derived from an event on 14 April 2004. Lastly, the microwave scatterometer remote sensing was applied to investigate the relation of sulphide events to oceanographic conditions. The events from May 2004 were clearly related to strong coastal upwelling.

  12. Transport of metals and sulphur in magmas by flotation of sulphide melt on vapour bubbles

    NASA Astrophysics Data System (ADS)

    Mungall, J. E.; Brenan, J. M.; Godel, B.; Barnes, S. J.; Gaillard, F.

    2015-03-01

    Emissions of sulphur and metals from magmas in Earth’s shallow crust can have global impacts on human society. Sulphur-bearing gases emitted into the atmosphere during volcanic eruptions affect climate, and metals and sulphur can accumulate in the crust above a magma reservoir to form giant copper and gold ore deposits, as well as massive sulphur anomalies. The volumes of sulphur and metals that accumulate in the crust over time exceed the amounts that could have been derived from an isolated magma reservoir. They are instead thought to come from injections of multiple new batches of vapour- and sulphide-saturated magmas into the existing reservoirs. However, the mechanism for the selective upward transfer of sulphur and metals is poorly understood because their main carrier phase, sulphide melt, is dense and is assumed to settle to the bottoms of magma reservoirs. Here we use laboratory experiments as well as gas-speciation and mass-balance models to show that droplets of sulphide melt can attach to vapour bubbles to form compound drops that float. We demonstrate the feasibility of this mechanism for the upward mobility of sulphide liquids to the shallow crust. Our work provides a mechanism for the atmospheric release of large amounts of sulphur, and contradicts the widely held assumption that dense sulphide liquids rich in sulphur, copper and gold will remain sequestered in the deep crust.

  13. Investigation of hydrogen sulphide eruptions along the Namibian coastline using different remote sensing systems

    NASA Astrophysics Data System (ADS)

    Ohde, Thomas

    2009-09-01

    Hydrogen sulphide eruptions with their typical turquoise discolorations at the water surface are a unique phenomenon along the Namibian coastline. The remote sensing techniques of ocean colour sensors and microwave scatterometers were used for the investigation of such events. The studies with ocean colour sensors showed that the turquoise discolorations near the Namibian coast were neither linked to dust deposition into the water column by desert storms nor to the reflection of bright material in shallow water areas. In addition, other coloured marine events like algae blooms and river outflows were differentiable from the hydrogen sulphide eruptions by their special optical properties. Quasi-true colour images and spectral identification methods were utilised to monitor and investigate the spatial and temporal distribution of sulphide events. In the past years, they were sometimes and locally limited discovered. Newest remote sensing observations including our own investigations have established that the occurrence of sulphide events is more frequent and longer lasting. The north-westerly direction of propagation and their velocity between 12 cm s-1 and 15 cm s1 were derived from an event on 14 April 2004. Lastly, the microwave scatterometer remote sensing was applied to investigate the relation of sulphide events to oceanographic conditions. The events from May 2004 were clearly related to strong coastal upwelling.

  14. Improvement in the photocurrent collection due to enhanced absorption of light by synthesizing staggered layers of silver nanoclusters in silicon

    SciTech Connect

    Dhoubhadel, Mangal S.; Lakshantha, Wickramaarachchige J.; Rout, Bibhudutta; McDaniel, Floyd D.; Lightbourne, Sherard; D’Souza, Francis

    2015-07-23

    The quest for increased efficiency of solar cells has driven the research in synthesizing photovoltaic cells involving Si based materials. The efficiency of solar cells involving crystalline Si is stalled around 25% for the last decade. Recently Shi et al. had shown that light trapping can be enhanced by fabricating double layers of Ag nanoparticles in silicon based materials. The light trapping is critically important in a photo devices such as solar cells in order to increase light absorption and efficiency. In the present work, we report enhancement in the absorption of light in Ag ion implanted Si substrates. Multiple low energies Ag ions, ranging from ∼80 keV to ∼30 keV, with different fluences ranging from ∼1 × 10{sup 16} to ∼1 × 10{sup 17} atoms/cm{sup 2} were sequentially implanted into commercially available Si (100) substrates followed by post-thermal annealing to create different sizes of Ag nanoclusters (NC) at different depths in the top 100 nm of the Si. The absorbance of light is increased in Ag implanted Si with a significant increase in the current collection in I-V (current-voltage) photo switching measurements. The experimental photovoltaic cells fabricated with the Ag-implanted Si samples were optically characterized under AM (air mass) 1.5 solar radiation conditions (∼1.0 kW/m{sup 2}). An enhancement in the charge collection were measured in the annealed samples, where prominent Ag NCs were formed in the Si matrix compared to the as-implanted samples with amorphous layers. We believe the enhancement of the photo-current density from the samples with Ag NC is due to the improvement of efficiency of charge collection of e{sup −}-h{sup +} pairs produced by the incident light.

  15. Antimicrobial silver: uses, toxicity and potential for resistance.

    PubMed

    Mijnendonckx, Kristel; Leys, Natalie; Mahillon, Jacques; Silver, Simon; Van Houdt, Rob

    2013-08-01

    This review gives a comprehensive overview of the widespread use and toxicity of silver compounds in many biological applications. Moreover, the bacterial silver resistance mechanisms and their spread in the environment are discussed. This study shows that it is important to understand in detail how silver and silver nanoparticles exert their toxicity and to understand how bacteria acquire silver resistance. Silver ions have shown to possess strong antimicrobial properties but cause no immediate and serious risk for human health, which led to an extensive use of silver-based products in many applications. However, the risk of silver nanoparticles is not yet clarified and their widespread use could increase silver release in the environment, which can have negative impacts on ecosystems. Moreover, it is shown that silver resistance determinants are widely spread among environmental and clinically relevant bacteria. These resistance determinants are often located on mobile genetic elements, facilitating their spread. Therefore, detailed knowledge of the silver toxicity and resistance mechanisms can improve its applications and lead to a better understanding of the impact on human health and ecosystems.

  16. Optimization of silver-dielectric-silver nanoshell for sensing applications

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  17. Optimization of silver-dielectric-silver nanoshell for sensing applications

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-01

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  18. Passivation effects of polyphenylene sulphide on the surface of GaAs

    NASA Astrophysics Data System (ADS)

    Bhide, R. S.; Bhoraskar, S. V.; Rao, V. J.

    1992-08-01

    Vacuum-evaporated thin films of polyphenylene sulphide have been used as an insulating overlayer on n-GaAs(110). Sulphur present in the polymer is seen to passivate the dangling bonds of GaAs. The interface of n-GaAs/polyphenylene sulphide was studied using grazing-angle x-ray diffraction at various angles for different annealing temperatures. The electronic properties of the interface are studied using electron-beam-induced-current measurements for determining the minority-carrier diffusion length and surface recombination velocity. The x-ray-diffraction analysis indicates the formation of arsenic sulphide at the interface and is expected to reduce the dangling bond density. The treated surface shows an increase in diffusion length and reduction in the surface recombination velocity. The polymer-semiconductor interface shows stability against annealing up to a temperature of 300 °C.

  19. Potential Field, Geoelectrical and Reflection Seismic Investigations for Massive Sulphide Exploration in the Skellefte Mining District, Northern Sweden

    NASA Astrophysics Data System (ADS)

    Tavakoli, Saman; Dehghannejad, Mahdieh; García Juanatey, María de los Ángeles; Bauer, Tobias E.; Weihed, Pär; Elming, Sten-Åke

    2016-12-01

    Multi-scale geophysical studies were conducted in the central Skellefte district (CSD) in order to delineate the geometry of the upper crust (down to maximum 4.5 km depth) for prospecting volcanic massive sulphide (VMS) mineralization. These geophysical investigations include potential field, resistivity/induced polarization (IP), reflection seismic and magnetotelluric (MT) data which were collected between 2009 and 2010. The interpretations were divided in two scales: (i) shallow ( 1.5 km) and (ii) deep ( 4.5 km). Physical properties of the rocks, including density, magnetic susceptibility, resistivity and chargeability, were also used to improve interpretations. The study result delineates the geometry of the upper crust in the CSD and new models were suggested based on new and joint geophysical interpretation which can benefit VMS prospecting in the area. The result also indicates that a strongly conductive zone detected by resistivity/IP data may have been missed using other geophysical data.

  20. Retiring the Silver Bullet

    SciTech Connect

    Lasure, Linda L.

    2006-01-01

    Over the past few decades, advances in biology and electronics have resulted in an enormous increase in the screening rate of new compounds and in the capacity to synthesize vast numbers of new compounds. The understanding of disease has greatly improved. At the same time, the number of targets (or diseases) for the silver bullets has also increased. Yet, the belief that we have to screen enormous numbers of compounds to find the next new drug continues. Today, disease is understood to be a complex interaction of many systems. This ought to cause us to change our paradigm, but it has not. The fundamental reason for the apparent failure of our drug discovery and development research is that we are operating under the constraints of an out-of-date paradigm. The silver-bullet paradigm has always been a myth. Now is the time to debunk the myth and change the paradigm. Our other option is to continue on as we are and accept that the United States will become obsolete on the playing field of drug discovery.

  1. Diffusive Transport of Sulphide through an Engineering Barrier System in a Deep Geological Repository

    NASA Astrophysics Data System (ADS)

    Briggs, S. A.; Sleep, B. E.; McKelvie, J. R. M.; Krol, M.

    2015-12-01

    Bentonite is a naturally occurring clay-rich sediment containing montmorillonite, a smectitic clay mineral that has a high cation exchange capacity and swells upon contact with water. Owing to these characteristics, highly compacted bentonite (HCB) is an often included component of engineered barrier systems (EBS) designed to protect used fuel containers (UFCs) in deep geological repositories (DGR) for high-level nuclear waste. The low water activity and high swelling pressure of HCB suppresses microbial activity and the related production of sulphide that could cause microbiologically influenced corrosion (MIC) of UFCs The Canadian Nuclear Waste Management Organization (NWMO) has chosen a UFC that consists of an inner steel core and outer copper coating which is resistant to corrosion. However, under anaerobic conditions, MIC can still contribute to UFC corrosion if sulphides are present in the groundwater. Therefore the EBS consisting of bentonite blocks and pellets has been designed to impede the movement of sulphides to the UFC. In order to examine the effectiveness of the EBS, a 3D numerical model was developed capable of simulating the diffusive transport of sulphide within the NWMO EBS. The model was developed using COMSOL Multiphysics, a finite element software package and is parametric which allows the impact of different repository layouts to be assessed. The developed model was of the entire NWMO placement room, as well as, a stand-alone UFC and included conservative assumptions such as a fully saturated system and a constant concentration boundary condition. The results showed that the highest sulphide flux occurred at the semi-spherical end caps of the UFC. Further studies examined the effect of sulphide hotspots and fractures, representing possible EBS failure mechanisms. The model results highlight that even with conservative assumptions the chosen EBS will effectively protect the UFC from microbiologically influenced corrosion.

  2. Niphargus-Thiothrix associations may be widespread in sulphidic groundwater ecosystems: evidence from southeastern Romania.

    PubMed

    Flot, Jean-François; Bauermeister, Jan; Brad, Traian; Hillebrand-Voiculescu, Alexandra; Sarbu, Serban M; Dattagupta, Sharmishtha

    2014-03-01

    Niphargus is a speciose amphipod genus found in groundwater habitats across Europe. Three Niphargus species living in the sulphidic Frasassi caves in Italy harbour sulphur-oxidizing Thiothrix bacterial ectosymbionts. These three species are distantly related, implying that the ability to form ectosymbioses with Thiothrix may be common among Niphargus. Therefore, Niphargus-Thiothrix associations may also be found in sulphidic aquifers other than Frasassi. In this study, we examined this possibility by analysing niphargids of the genera Niphargus and Pontoniphargus collected from the partly sulphidic aquifers of the Southern Dobrogea region of Romania, which are accessible through springs, wells and Movile Cave. Molecular and morphological analyses revealed seven niphargid species in this region. Five of these species occurred occasionally or exclusively in sulphidic locations, whereas the remaining two were restricted to nonsulphidic areas. Thiothrix were detected by PCR on all seven Dobrogean niphargid species and observed using microscopy to be predominantly attached to their hosts' appendages. 16S rRNA gene sequences of the Thiothrix epibionts fell into two main clades, one of which (herein named T4) occurred solely on niphargids collected in sulphidic locations. The other Thiothrix clade was present on niphargids from both sulphidic and nonsulphidic areas and indistinguishable from the T3 ectosymbiont clade previously identified on Frasassi-dwelling Niphargus. Although niphargids from Frasassi and Southern Dobrogea are not closely related, the patterns of their association with Thiothrix are remarkably alike. The finding of similar Niphargus-Thiothrix associations in aquifers located 1200 km apart suggests that they may be widespread in European groundwater ecosystems. © 2013 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  3. Experimental observation of zinc dialkyl dithiophosphate (ZDDP)-induced iron sulphide formation

    NASA Astrophysics Data System (ADS)

    Soltanahmadi, Siavash; Morina, Ardian; van Eijk, Marcel C. P.; Nedelcu, Ileana; Neville, Anne

    2017-08-01

    Zinc dialkyl dithiophosphate (ZDDP) as a well-known anti-wear additive enhances the performance of the lubricant beyond its wear-protection action, through its anti-oxidant and Extreme Pressure (EP) functionality. In spite of over thirty years of research attempting to reveal the mechanism of action of ZDDP, there are still some uncertainties around the exact mechanisms of its action. This is especially the case with the role of sulphide layer formed in the tribofilm and its impact on surface fatigue. Although iron sulphide on the substrate is hypothesised in literature to form as a separate layer, there has been no concrete experimental observation on the distribution of the iron sulphide as a dispersed precipitate, distinct layer at the steel substrate or both. It remains to be clarified whether the iron sulphide layer homogeneously covers the surface or locally forms at the surface. In the current study a cross section of the specimen after experiment was prepared and has been investigated with Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray (EDX) elemental analysis. A 5-10 nm iron sulphide layer is visualised on the interface as a separate layer underneath the phosphate layer with an altered distribution of tribofilm elements near the crack site. The iron sulphide interface layer is more visible near the crack site where the concentration of the sulphur is enhanced. Also, ZDDP elements were clearly detected inside the crack with a varied relative concentration from the crack-mouth to the crack-tip. Sulphur is present inside the crack to a higher extent than in the bulk of the tribofilm.

  4. Treating landfill gas hydrogen sulphide with mineral wool waste (MWW) and rod mill waste (RMW).

    PubMed

    Bergersen, Ove; Haarstad, Ketil

    2014-01-01

    Hydrogen sulphide (H2S) gas is a major odorant at municipal landfills. The gas can be generated from different waste fractions, for example demolition waste containing gypsum based plaster board. The removal of H2S from landfill gas was investigated by filtering it through mineral wool waste products. The flow of gas varied from 0.3 l/min to 3.0 l/min. The gas was typical for landfill gas with a mean H2S concentration of ca. 4500 ppm. The results show that the sulphide gas can effectively be removed by mineral wool waste products. The ratios of the estimated potential for sulphide precipitation were 19:1 for rod mill waste (RMW) and mineral wool waste (MWW). A filter consisting of a mixture of MWW and RMW, with a vertical perforated gas tube through the center of filter material and with a downward gas flow, removed 98% of the sulfide gas over a period of 80 days. A downward gas flow was more efficient in contacting the filter materials. Mineral wool waste products are effective in removing hydrogen sulphide from landfill gas given an adequate contact time and water content in the filter material. Based on the estimated sulphide removal potential of mineral wool and rod mill waste of 14 g/kg and 261 g/kg, and assuming an average sulphide gas concentration of 4500 ppm, the removal capacity in the filter materials has been estimated to last between 11 and 308 days. At the studied location the experimental gas flow was 100 times less than the actual gas flow. We believe that the system described here can be upscaled in order to treat this gas flow. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Effect of silver nanoparticles on concentration of silver heavy element and growth indexes in cucumber ( Cucumis sativus L . negeen)

    NASA Astrophysics Data System (ADS)

    Shams, Gholamabbas; Ranjbar, Morteza; Amiri, Aliasghar

    2013-05-01

    The tremendous progress on nanoparticle research area has been made significant effects on the economy, society, and the environment. Silver nanoparticle is one of the most important particles in these categories. Silver nanoparticles can be converted to the heavy silver metal in water by oxidation. Moreover, in the high amounts of silver concentration, they will be accumulated in different parts of the plant. However, by changing the morphology of the plant, the production will be harmful for human consumptions. In this study, nano-powders with average 50 nm silver particles are mixed with deionized distilled water in a completely randomized design. Seven treatments with various concentrations of suspension silver nanoparticles were prepared and repeated in four different parts of the plant in a regular program of spraying. Samples were analyzed to study the growth indexes and concentration of silver in different parts of the plant. It was observed that with increasing concentration of silver nanoparticles on cucumber, the growth indexes (except pH fruit), and the concentration of silver heavy metal are increased significantly. The incremental concentration had the linear relationship with correlation coefficient 0.95 and an average of 0.617 PPM by increasing of each unit in one thousand concentration of nanosilver. Although, by increasing concentration of silver nanoparticles as spraying form, the plant morphological characteristics were improved, the concentration of silver heavy metal in various plant organs was increased. These results open a new pathway to consider the effect of nanoparticles on plant's productions for human consumptions.

  6. Microbial control of silver mineralization at a sea-floor hydrothermal site on the northern Gorda Ridge

    USGS Publications Warehouse

    Zierenberg, R.A.; Schiffman, P.

    1990-01-01

    THE Sea Cliff hydrothermal field, on the northern Gorda Ridge, contains mounds and chimneys of hydrothermally precipitated sulphide and sulphate minerals typical of sea-floor hydrothermal vent sites1. In addition, large areas of the sea floor are covered by subhorizontal hydrothermal crusts. Samples of the crust recovered by submersible are composed of intensely altered fragments of basalt and basaltic hyaloclastite cemented by amorphous silica and chalcedony with less abundant barite, and minor amounts of base-metal sulphide minerals2. Some surfaces of the crust were formerly colonized by bacterial mats, which are locally preserved by replacement and overgrowth of the bacterial filaments by metal sulphide minerals and amorphous silica. The bacterial filaments are selectively replaced by prousite (Ag3AsS3), pearceite3 (Ag14.7-XCu1.3+xAs2S11), chalcopyrite (CuFeS2) and rarely by galena (PbS). Our observations suggest that bacterially mediated processes selectively precipitate silver, arsenic and copper, and that biological processes may contribute to precious-metal enrichment in some sea-floor hydrothermal base-metal sulphide deposits.

  7. Utilization of industrial waste products as pozzolanic material in cemented paste backfill of high sulphide mill tailings.

    PubMed

    Ercikdi, Bayram; Cihangir, Ferdi; Kesimal, Ayhan; Deveci, Haci; Alp, Ibrahim

    2009-09-15

    In this study, the potential use of the industrial waste products including waste glass (WG), fly ash (FA), granulated blast furnace slag (GBFS) and silica fume (SF) as pozzolanic additive for the partial replacement of ordinary Portland cement (OPC) in cemented paste backfill (CPB) of sulphide-rich mill tailings was investigated. The influence of these industrial waste products on the short- and long-term mechanical performance of CPB was demonstrated. The rate of development of strength of CPB samples tended to slow down when the pozzolanic wastes were incorporated or increased in dosage in the binder phase. Severe losses (by 26%) in the strength of CPB samples produced from exclusively OPC occurred after an initial curing period of 56 days. The addition of WG (10-30 wt%) as a partial replacement of OPC was observed to aggravate further the strength losses of CPB samples. GBFS, FA and SF appeared to improve the long-term performance of CPB samples; albeit, only GBFS and SF could be incorporated into the binder phase only at certain levels i.e. up to 20 wt% GBFS and 15wt% SF in order to maintain a threshold strength level of 0.7MPa over 360 days. SEM studies have provided further insight into the microstucture of CPB and confirmed the formation of deleterious gypsum as the expansive phase. These findings have demonstrated that the industrial waste products including GBFS and SF can be suitably used as mineral additives to improve the long-term mechanical performance of CPB produced from sulphide-rich tailings as well as to reduce the binder costs in a CPB plant.

  8. Inkjet-printed disposable metal complexing indicator-displacement assay for sulphide determination in water.

    PubMed

    Ariza-Avidad, M; Agudo-Acemel, M; Salinas-Castillo, A; Capitán-Vallvey, L F

    2015-05-04

    A sulphide selective colorimetric metal complexing indicator-displacement assay has been developed using an immobilized copper(II) complex of the azo dye 1-(2-pyridylazo)-2-naphthol printed by inkjetting on a nylon support. The change in colour measured from the image of the disposable membrane acquired by a digital camera using the H coordinate of the HSV colour space as the analytical parameter is able to sense sulphide in aqueous solution at pH 7.4 with a dynamic range up to 145 μM, a detection limit of 0.10 μM and a precision between 2 and 11%.

  9. Massive deep-sea sulphide ore deposits discovered on the East Pacific Rise

    USGS Publications Warehouse

    Francheteau, Jean; Needham, H.D.; Choukroune, P.; Juteau, Tierre; Seguret, M.; Ballard, Richard D.; Fox, P.J.; Normark, William; Carranza, A.; Cordoba, D.; Guerrero, J.; Rangin, C.; Bougault, H.; Cambon, P.; Hekinian, R.

    1979-01-01

    Massive ore-grade zinc, copper and iron sulphide deposits have been found at the axis of the East Pacific Rise. Although their presence on the deep ocean-floor had been predicted there was no supporting observational evidence. The East Pacific Rise deposits represent a modern analogue of Cyprus-type sulphide ores associated with ophiolitic rocks on land. They contain at least 29% zinc metal and 6% metallic copper. Their discovery will provide a new focus for deep-sea exploration, leading to new assessments of the concentration of metals in the upper layers of the oceanic crust. ?? 1979 Nature Publishing Group.

  10. Evaluation of sulcular sulphide level monitoring using a portable sensor system.

    PubMed

    Gleissner, C; Springborn, I; Willershausen, B

    2002-11-25

    Volatile sulphur compounds (VSC) such as hydrogen sulphide and methyl mercaptan are toxic bacterial metabolites considered to contribute to the progression of periodontitis. However, the quantitative determination of sulcular VSC concentration requires costly time-consuming laboratory methods limiting its evaluation in large clinical trials. Recently, a portable monitor with a sulphide microsensor has been developed to measure sulcular VSC levels (SU). This cross-sectional study evaluated 1) the clinical usage of the sulphide sensor system, 2) the reproducibility of SU-measurements, 3) the distribution of SU-values in periodontal health and disease and 4) the relationship between SU and clinical parameters documenting periodontal disease severity. The specificity, the measuring range and the reproducibility of the sensor system were tested with reference solutions in vitro. 10 probands with healthy gingiva, 23 patients with gingivitis and 30 patients with chronic periodontitis were examined recording periodontal parameters (clinical attachment loss, CAL, probing depth, PD, bleeding on probing intensity BI, plaque and gingival index PI, GI) and sulcular sulphide level (SU) measured by the portable monitor as a digital score ranging from 0.0 (< 10 superset -6 M of S2-) to 5.0 (10 superset -2 M of S superset 2-) in increments of 0.5. The in vitro testing confirmed the sensor s specificity for sulphide ions. The intraexaminer agreement (Pearson correlation coefficient) was 0.91 between two measurements (p < 0.05). However, positive SU-values decreased with measurement repetition due to the volatility of the sulphur compounds. SU and the percentage of positive SU-values per patient were correlated with disease severity. There were no positive SU-values in healthy probands, a mean SU of 0.11 +/- 0.08 in gingivitis and of 0.22 +/- 0.15 in periodontitis (p <0.001). SU was significantly correlated with PD in gingivitis, PD and CAL in periodontitis and the bleeding index in

  11. Silver-Teflon coating improvement

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1976-01-01

    Approximately forty adhesives were subjected to laboratory screening. Seven candidate adhesives were selected from the screening tests and evaluated in a thermal vacuum test on radiator panels similar to the anticipated flight hardware configuration. Several classes of adhesives based on epoxide, polyester, silicone, and urethane resin systems were tested. These included contact adhesives, heat cured adhesives, heat and pressure cured adhesives, pressure sensitive adhesives, and two part paint-on or spray-on adhesives. The panels were tested in a space environmental simulation laboratory chamber during the July 9-20, 1973 time span.

  12. Silver Recovery and Power Generation from Ammonia Chelated Silver Solution in a Bio-Electrochemical Reactor

    NASA Astrophysics Data System (ADS)

    Ho, N. A. D.; Babel, S.

    2017-06-01

    Silver has valuable features and limited availability, and thus recovery from wastewater or aqueous solutions plays an important role in environmental protection and economic profits. In this study, silver recovery along with power generation and COD removal were investigated in a bio-electrochemical system (BES). The BES comprised of an anode and a cathode chamber which were separated by a cation exchange membrane to prevent the cross-over of electrolytes. During the biological oxidation of acetate as an electron donor in the anode chamber, the reduction of ammonia chelated silver ions as electron acceptors in the cathode side occurred spontaneously. Results showed that a silver recovery of 99% and COD removal efficiency of 60% were achieved at the initial silver concentration of 1,000 mg/L after 48 hours of operation. The power generation improved 4.66%, from 3,618 to 3,795 mW/m3, by adding NaNO3 of 850 mg/L to the catholyte containing 2,000 mg/L of silver ions. Deposits on the cathode surface were characterized using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Metallic silver with dendritic structures and high purity were detected. This study demonstrated that BES technology can be employed to recover silver from complex chelating solution, produce electricity, and treat wastewater.

  13. Improved method for the determination of nonpurgeable suspended organic carbon in natural water by silver filter filtration, wet chemical oxidation, and infrared spectrometry

    USGS Publications Warehouse

    Burkhardt, M.R.; Brenton, R.W.; Kammer, J.A.; Jha, V.K.; O'Mara-Lopez, P. G.; Woodworth, M.T.

    1999-01-01

    Precision and accuracy are reported for the first time for the analysis of nonpurgeable suspended organic carbon by silver membrane filtration followed by wet chemical oxidation. A water sample is pressure filtered through a 0.45-??m-pore-size, 47-mm-diameter silver membrane filter. The silver membrane filter then is cut into ribbons and placed in a flame-sealable glass ampule. The organic material trapped on the membrane filter strips is acidified, purged with oxygen to remove inorganic carbonates and volatile organic compounds, and oxidized to carbon dioxide (CO2) using phosphoric acid and potassium persulfate in the sealed glass ampule. The resulting CO2 is measured by a nondispersive infrared CO2 detector. The amount of CO2 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the environmental water sample. The quantitation and method detection limit for routine analysis is 0.2 mg/L. The average percent recovery in five representative matrices was 97 ?? 11%. The errors associated with sampling and sample preparation of nonpurgeable suspended organic carbon are also described.Precision and accuracy are reported for the first time for the analysis of nonpurgeable suspended organic carbon by silver membrane filtration followed by wet chemical oxidation. A water sample is pressure filtered through a 0.45-??m-pore-size, 47-mm-diameter silver membrane filter. The silver membrane filter then is cut into ribbons and placed in a flame-sealable glass ampule. The organic material trapped on the membrane filter strips is acidified, purged with oxygen to remove inorganic carbonates and volatile organic compounds, and oxidized to carbon dioxide (CO2) using phosphoric acid and potassium persulfate in the sealed glass ampule. The resulting CO2 is measured by a nondispersive infrared CO2 detector. The amount of CO2 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the environmental water sample

  14. Glycine-coated photoluminescent silver nanoclusters

    NASA Astrophysics Data System (ADS)

    Kravets, Vira V.; Culhane, Kyle; Dmitruk, Igor M.; Pinchuk, Anatoliy O.

    2012-03-01

    We present experimental results on the multicolor (blue and green) photoluminescence from glycine-coated silver nanoclusters and small nanoparticles which can be used as novel probes for bio-imaging. Glycine-coated silver nanoclusters and nanoparticles were synthesized using thermal reduction of silver nitrate in a glycine matrix, according to a modified procedure described in literature. The size characterization with mass spectrometry, scanning electron microscopy and dynamic light scattering showed that the diameters of luminescent silver nanoclusters and small nanoparticles vary from 0.5 nm to 17 nm. Extinction spectroscopy revealed that the absorption band of the luminescent nanoclusters and nanoparticles was blue-shifted as compared to the nonluminescent larger silver nanoparticles. This effect indicated the well-known size dependence of the surface plasmon resonance in silver. The most pronounced photoluminescence peak was observed around 410 nm (characteristic SPR wavelength for silver) which strongly suggests the enhancement of the photoluminescence from silver nanoparticles by the SPR. The relative quantum yield of the photoluminescence of silver nanoclusters and nanoparticles was evaluated to be 0.09. In terms of their small size, brightness and photostability, noble metal nanoclusters and nanoparticles hold the most promise as candidates for biological cell imaging, competing with commonly used semiconductor quantum dots, fluorescent proteins and organic dyes. When applied to the problem of intracellular imaging, metal nanoclusters and small nanoparticles offer advantages over their much larger sized semiconductor counterparts in terms of ease of biological delivery. In addition, noble metal nanoparticles and nanoclusters are photostable. The high quantum yield (QY) of the photoluminescence emission signal enables the isolation of their photoluminescence from the cellular autofluorescence in cell imaging, improving the image contrast.

  15. Improved performance of poly(3,4-ethylenedioxythiophene):poly(stylene sulfonate)/n-Si hybrid solar cell by incorporating silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Khatri, Ishwor; Liu, Qiming; Ueno, Keiji; Shirai, Hajime

    2014-11-01

    We report an enhancement in the efficiency of poly(3,4-ethylenedioxythiophene):poly(stylene sulfonate) (PEDOT:PSS)/n-Si hybrid solar cell by incorporating silver nanoparticles (AgNPs) with PEDOT:PSS. AgNPs were prepared by reducing silver nitrate in green-tea solution, which showed characteristic absorption peak due to the surface plasmonic resonance effect. AgNPs incorporated PEDOT:PSS/n-Si hybrid device shows power conversion efficiency (η) of 10.21%, which is comparatively higher to the performance of pristine device without AgNPs. Here, we noticed that incorporation of AgNPs decreases sheet resistance and enlarged surface roughness of PEDOT:PSS film for the efficient collection of charges, rather than plasmonic effect.

  16. Realistic Silver Optical Constants for Plasmonics

    NASA Astrophysics Data System (ADS)

    Jiang, Yajie; Pillai, Supriya; Green, Martin A.

    2016-07-01

    Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik’s 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative properties of pristine silver, due to tarnishing on air exposure. We demonstrate techniques, including use of silicon-nitride membranes, to access the full capabilities of multiple-angle, spectrometric-ellipsometry to generate an improved data set, representative of overlayer-protected, freshly-deposited silver films on silicon-nitride and glass.

  17. Realistic Silver Optical Constants for Plasmonics.

    PubMed

    Jiang, Yajie; Pillai, Supriya; Green, Martin A

    2016-07-29

    Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik's 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative properties of pristine silver, due to tarnishing on air exposure. We demonstrate techniques, including use of silicon-nitride membranes, to access the full capabilities of multiple-angle, spectrometric-ellipsometry to generate an improved data set, representative of overlayer-protected, freshly-deposited silver films on silicon-nitride and glass.

  18. Realistic Silver Optical Constants for Plasmonics

    PubMed Central

    Jiang, Yajie; Pillai, Supriya; Green, Martin A.

    2016-01-01

    Silver remains the preferred conductor for optical and near-infrared plasmonics. Many high-profile studies focus exclusively on performance simulation in such applications. Almost invariably, these use silver optical data either from Palik’s 1985 handbook or, more frequently, an earlier Johnson and Christy (J&C) tabulation. These data are inconsistent, making it difficult to ascertain the reliability of the simulations. The inconsistency stems from challenges in measuring representative properties of pristine silver, due to tarnishing on air exposure. We demonstrate techniques, including use of silicon-nitride membranes, to access the full capabilities of multiple-angle, spectrometric-ellipsometry to generate an improved data set, representative of overlayer-protected, freshly-deposited silver films on silicon-nitride and glass. PMID:27470307

  19. Superconducting silver brazing alloy (silver solder).

    PubMed

    Thompson, J R; Thomson, J O

    1978-10-01

    A superconducting transition has been observed in a type BAg-3 silver brazing alloy (silver solder) with T(c)=96.(6) mK and H(c)=4.7 Oe. The associated diamagnetism indicates that approximately 1/3 of the sample volume displays the Meissner effect. This property dictates caution in its use at very low temperatures, particularly near sensitive magnetic devices such as ac and SQUID magnetometers.

  20. Determination of metallic iron in a mixture of lime, calcium sulphide and pyrrhotite.

    PubMed

    Sastri, V S

    A method is described for the determination of metallic iron in a complex matrix consisting of calcium oxide, calcium sulphide, carbon and pyrrhotite. The procedure consists of leaching the sample with 5% ammonium chloride solution (10% sucrose solution in some cases) followed by treatment with mercury(II) chloride solution and titration with dichromate solution.

  1. Late Jurassic ocean anoxic event: evidence from voluminous sulphide deposition and preservation in the Panthalassa

    PubMed Central

    Nozaki, Tatsuo; Kato, Yasuhiro; Suzuki, Katsuhiko

    2013-01-01

    The historically productive copper-bearing Besshi-type sulphide deposits in the Japanese accretionary complex were formed as volcanogenic massive sulphide deposits on the deep-sea floor of the Panthalassa Ocean. Here we report that eleven typical Besshi-type deposits yielded Re-Os isochron ages around 150 Ma (148.4 ± 1.4 Ma from the composite isochron) in Late Jurassic time. This date coincides with the lowest marine 87Sr/86Sr ratio and highest atmospheric CO2 concentration of the past 300 million years. We infer that intense mid-ocean ridge hydrothermal and volcanic activity in the Late Jurassic produced huge sulphide deposits and large emissions of CO2 gas, leading to global warming and a stratified Panthalassa Ocean with anoxic deep seas that favored preservation of sulphides in the pelagic environment. The emergence of ocean anoxia triggered by seafloor volcanism is also consistent with a positive δ13C excursion and widespread deposition of petroleum source rocks and black shales. PMID:23712471

  2. Laboratory far-infrared spectroscopy of terrestrial sulphides to support analysis of cosmic dust spectra

    NASA Astrophysics Data System (ADS)

    Brusentsova, T.; Peale, R. E.; Maukonen, D.; Figueiredo, P.; Harlow, G. E.; Ebel, D. S.; Nissinboim, A.; Sherman, K.; Lisse, C. M.

    2012-03-01

    As an aid in interpreting data from space far-infrared (far-IR) missions, such as the Herschel Space Observatory with its Photodetector Array Camera and Spectrometer, this paper presents spectroscopic studies of selected naturally occurring terrestrial sulphide minerals in the wavelength range 15-250 μm. The data can also be used to support the return from other, both past and planned, IR space missions, such as the Infrared Space Observatory, Spitzer, SOFIA, SPiCA and Millimetron. In this study, we present far-IR spectra for 11 natural sulphide minerals in the form of dispersed powders of micron particle dimensions. Samples of various sulphides from the American Museum of Natural History mineral collection were selected based on criteria of diversity and potential astrophysical relevancy, based on their identification in Stardust, in stratospheric interplanetary dust particle samples, or in meteorites. Mineral species include digenite, galena, alabandite, sphalerite, wurtzite, covellite, pyrrhotite, pyrite, marcasite, chalcopyrite and stibnite. Most of the sulphides examined possess prominent and characteristic features in the far-IR range. Spectra obtained are compared to those available from previous studies. Far-IR peak frequencies and mass absorption coefficient values are tabulated. Effects of particle size distribution, low temperature, and provenance on IR spectra are demonstrated for selected samples.

  3. Study of linear optical parameters of sodium sulphide nano-particles added ADP crystals

    NASA Astrophysics Data System (ADS)

    Kochuparampil, A. P.; Joshi, J. H.; Dixit, K. P.; Jethva, H. O.; Joshi, M. J.

    2017-05-01

    Ammonium Dihydrogen Phosphate (ADP) is one of the nonlinear optical crystals. It is having various applications like optical mixing, electro-optical modulator, harmonic generators, etc. Chalcogenide compounds are poorly soluble in water and difficult to add in the water soluble ADP crystals. The solubility of Chalcogenide compounds can be increased by synthesizing the nano-structured samples with suitable capping agent. In the present study sodium sulphide was added in to ADP to modify its linear optical parameters. Sodium sulphide nano particles were synthesized by co-precipitation technique using Ethylene diamine as capping agent followed by microwave irradiation. The powder XRD confirmed the nano-structured nature of sodium sulphide nano particles. The solubility of nanoparticles of sodium sulphide increased significantly in water compared to the bulk. Pure and Na2S added ADP crystals were grown by slow solvent evaporation method at room temperature. The presence of sodium in ADP was confirmed by AAS. The UV-Vis spectra were recorded for all crystals. Various optical parameters like, transmittance, energy band gap, extinction coefficient, refractive index, optical conductivity, etc. were evaluated. The electronic polarizibility of pure and doped crystals calculated from energy band gap. The effect of doping concentration was found on various parameters.

  4. Late Jurassic ocean anoxic event: evidence from voluminous sulphide deposition and preservation in the Panthalassa.

    PubMed

    Nozaki, Tatsuo; Kato, Yasuhiro; Suzuki, Katsuhiko

    2013-01-01

    The historically productive copper-bearing Besshi-type sulphide deposits in the Japanese accretionary complex were formed as volcanogenic massive sulphide deposits on the deep-sea floor of the Panthalassa Ocean. Here we report that eleven typical Besshi-type deposits yielded Re-Os isochron ages around 150 Ma (148.4 ± 1.4 Ma from the composite isochron) in Late Jurassic time. This date coincides with the lowest marine (87)Sr/(86)Sr ratio and highest atmospheric CO2 concentration of the past 300 million years. We infer that intense mid-ocean ridge hydrothermal and volcanic activity in the Late Jurassic produced huge sulphide deposits and large emissions of CO2 gas, leading to global warming and a stratified Panthalassa Ocean with anoxic deep seas that favored preservation of sulphides in the pelagic environment. The emergence of ocean anoxia triggered by seafloor volcanism is also consistent with a positive δ(13)C excursion and widespread deposition of petroleum source rocks and black shales.

  5. Biogenic catalysis in sulphide minerals' weathering processes and acid mine drainage genesis.

    PubMed

    Kušnierová, Mária; Praščáková, Mária; Nowak, Anna K; Gorazda, Katarzyna; Wzorek, Zbigniew

    2014-01-01

    Bioleaching and biogenesis are the main outputs from a large group of environmental processes participating in the natural material cycle, used in raw materials processing. Bio-oxidation reactions are the main basis for bioleaching procedures, often participating in parallel leaching processes. During the leaching processes of polycomponent sulphide substrates, the factor of process selection also plays an important role, being in direct relation to the electric properties and galvanic effect occurring between the individual components of the leaching substrate. This work gives a summary of the results of a research focused on the possibilities of using biotechnological procedures for treatment of Slovak sulphide ores. The object of the research is extraction of valuable metals, undesirable admixtures and degradation of crystal lattice of sulphides for subsequent chemical leaching processing of precious metals. The results of experiments on the existence of biogenic processes in situ on waste dumps from exploitation containing residual sulphides are also presented. The processes result in acid mine drainage water generation. These waters are strongly mineralised (over 48 g/L) and of low pH; that is why they are very caustic. The arsenic content (2.558 mg/L) in outflowing waters from old mines is high and over the limits set by the law.

  6. Dosimetry using silver salts

    DOEpatents

    Warner, Benjamin P.

    2003-06-24

    The present invention provides a method for detecting ionizing radiation. Exposure of silver salt AgX to ionizing radiation results in the partial reduction of the salt to a mixture of silver salt and silver metal. The mixture is further reduced by a reducing agent, which causes the production of acid (HX) and the oxidized form of the reducing agent (R). Detection of HX indicates that the silver salt has been exposed to ionizing radiation. The oxidized form of the reducing agent (R) may also be detected. The invention also includes dosimeters employing the above method for detecting ionizing radiation.

  7. Generalized chemical route to develop fatty acid capped highly dispersed semiconducting metal sulphide nanocrystals

    SciTech Connect

    Patel, Jayesh D.; Mighri, Frej; Ajji, Abdellah

    2012-08-15

    Highlights: ► Chemical route for the synthesis of OA-capped CdS, ZnS and PbS at low temperature. ► Synthesized nanocrystals via thermolysis of their metal–oleate complexes. ► Size quantized nanocrystals were highly dispersed and stable at room temperature. -- Abstract: This work deals with the synthesis of highly dispersed semiconducting nanocrystals (NCs) of cadmium sulphide (CdS), zinc sulphide (ZnS) and lead sulphide (PbS) through a simple and generalized process using oleic acid (OA) as surfactant. To synthesize these NCs, metal–oleate (M–O) complexes were obtained from the reaction at 140 °C between metal acetates and OA in hexanes media. Subsequently, M–O complexes were sulphurized using thioacetamide at the same temperature. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) characterizations show that the synthesized products are of nanoscale-size with highly crystalline cubic phase. The optical absorption of OA-capped metal sulphide NCs confirms that their size quantization induced a large shift towards visible region. Photoluminescence (PL) spectrum of CdS NCs shows a broad band-edge emission with shallow and deep-trap emissions, while PL spectrum of ZnS NCs reveals a broad emission due to defects states on the surface. The thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy indicate that fatty acid monolayers were bound strongly on the nanocrystal surface as a carboxylate and the two oxygen atoms of the carboxylate were coordinated symmetrically to the surface of the NCs. The strong binding between the fatty acid and the NCs surface enhances the stability of NCs colloids. In general, this generalized route has a great potential in developing nanoscale metal sulphides for opto-electronic devices.

  8. Silver nanoparticles-coated glass frits for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Li, Biyuan

    2016-04-01

    Silver nanoparticles-coated glass frit composite powders for silicon solar cells were prepared by electroless plating. Silver colloids were used as the activating agent of glass frits. The products were characterized by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The characterization results indicated that silver nanoparticles with the melting temperature of 838 °C were uniformly deposited on glass frit surface. The particle size of silver nanoparticles could be controlled by adjusting the [Ag(NH3)2]NO3 concentration. The as-prepared composite powders were applied in the front side metallization of silicon solar cells. Compared with those based on pure glass frits, the solar cells containing the composite powders had the denser silver electrodes and the better silver-silicon ohmic contacts. Furthermore, the photovoltaic performances of solar cells were improved after the electroless plating.

  9. Using the essential oil of Aloysia triphylla (L'Her.) Britton to sedate silver catfish (Rhamdia quelen) during transport improved the chemical and sensory qualities of the fish during storage in ice.

    PubMed

    Daniel, Ana Paula; Veeck, Ana Paula L; Klein, Bruna; Ferreira, Lauren F; da Cunha, Mauro A; Parodi, Thaylise V; Zeppenfeld, Carla C; Schmidt, Denise; Caron, Braulio O; Heinzmann, Berta M; Baldisserotto, Bernardo; Emanuelli, Tatiana

    2014-06-01

    Exposure of silver catfish to 40 μL/L of the essential oil of Aloysia triphylla (AT) during in vivo transport delayed the onset and resolution of rigor mortis as well as the degradation of IMP into HxR compared to the control. The fish that were treated with 30 or 40 μL/L of AT received lower sensory demerit scores after 10 d of storage in ice compared to the control, and the fish that were treated with 40 μL/L of AT had a longer sensory shelf life than did the control. These results indicated that using AT as a sedative in the water in which the silver catfish were transported extended their freshness and increased their shelf life during refrigerated storage. Interest in natural anesthetics, such as Aloysia triphylla, has increased in the field of commercial aquaculture because they reduce the number of fish lesions acquired during capture, handling, and transportation. Fish sedated with the essential oil of A. triphylla at 40 μL/L during transport before slaughter exhibited a delay in the loss of freshness and an increased shelf life in ice. In addition to improving animal welfare before slaughter, the essential oil appears to be a promising product for improving fish conservation in the food industry. © 2014 Institute of Food Technologists®

  10. The silver ions contribution into the cytotoxic activity of silver and silver halides nanoparticles

    NASA Astrophysics Data System (ADS)

    Klimov, A. I.; Zherebin, P. M.; Gusev, A. A.; Kudrinskiy, A. A.; Krutyakov, Y. A.

    2015-11-01

    The biocidal action of silver nanoparticles capped with sodium citrate and silver halides nanoparticles capped with non-ionic surfactant polyoxyethylene(20)sorbitan monooleate (Tween 80®) against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells. The cytotoxicity of the obtained colloids was strongly correlated with silver ion content in the dispersions. The results clearly indicated that silver and silver halides nanoparticles destroyed yeast cells through the intermediate producing of silver ions either by dissolving of salts or by oxidation of silver.

  11. Matrix modification with silver for the electrothermal atomization of arsenic and selenium

    USGS Publications Warehouse

    Sanzolone, R.F.; Chao, T.T.

    1981-01-01

    Silver as a matrix modifier is shown to improve the carbon-rod atomization of both arsenic and selenium for atomic absorption spectrometry. Compared to nickel, the efficiency of silver is greater for arsenic and about the same for selenium. Silver fulfils two functions in its reaction, namely stabilization during the ashing stage and enhancement of absorbance in the final atomization. ?? 1981.

  12. Interfacial Design of Ternary Mixed Matrix Membranes Containing Pebax 1657/Silver-Nanopowder/[BMIM][BF4] for Improved CO2 Separation Performance.

    PubMed

    Ghasemi Estahbanati, Ehsan; Omidkhah, Mohammadreza; Ebadi Amooghin, Abtin

    2017-03-08

    In this research, Pebax1657 as an organic phase and silver nanoparticles as an inorganic phase were used for preparation of binary mixed matrix membranes (MMMs). Silver nanoparticles as a filler could enter the polymer chains and enhance the gas permeability by increasing the fractional free volume of membranes. Afterward, ternary MMMs were fabricated by addition of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid, in order to have better polymer/filler adhesion and eliminate interfacial defects and nonselective voids. In addition, positively polarized silver nanoparticles in the presence of the IL could interact with PEO segment of the polymer and increase the CO2 affinity of membranes, which results in increasing the CO2/light gases permselectivity of MMMs. Gas permeation properties of MMMs were studied at a temperature of 35 °C and operating pressures from 2 to 10 bar. Moreover, fabricated membranes were characterized by fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). The analysis revealed that there is a proper adhesion between positively charged surface of nanoparticles and the polymer, and both filler and IL decrease the crystallinity of the membranes, which could enhance the polar gas transport properties. Gas permeation results showed significant enhancement in CO2 permeability (325 Barrer) for binary membrane (Pebax 1657/1%Ag) at 35 °C and 10 bar. Moreover, ternary MMM (Pebax 1657/0.5%Ag/50%IL) encountered significant increase in both permeability and selectivity in comparison with neat membrane. Indeed, the CO2 permeability increased from 110 Barrer to 180 (about 64%). Moreover, the related CO2/CH4 and CO2/N2 selectivities were increased from 20.8 to 61.0 (more than 193%) and from 78.6 to 187.5 (about 139%), respectively.

  13. Improved method of detecting the ERG gene rearrangement in prostate cancer using combined dual-color chromogenic and silver in situ hybridization.

    PubMed

    Braun, Martin; Stomper, Julia; Boehm, Diana; Vogel, Wenzel; Scheble, Veit J; Wernert, Nicolas; Shaikhibrahim, Zaki; Fend, Falko; Kristiansen, Glen; Perner, Sven

    2012-07-01

    The recently detected TMPRSS2-ERG fusion gene was revealed as a recurrent and prevalent prostate cancer (PCa)-specific event, potentially qualifying it for clinical use. To detect this alteration, fluorescence in situ hybridization (FISH) is the method of choice. However, FISH has some disadvantages for widespread adoption in clinical practice. Subsequently, chromogenic in situ hybridization, which uses organic chromogens, and enzymatic metallography silver in situ hybridization have emerged as promising bright-field alternatives. Compared with chromogenic in situ hybridization, silver in situ hybridization signals are very distinct and superior with regard to signal clarity and resolution, but the method excludes multicolor protocols. Based on the ERG break-apart FISH assay, we established a dual-color ERG break-apart assay using combined chromogenic in situ hybridization and silver in situ hybridization (CS-ISH) and compared these results with those obtained by FISH. We assessed 178 PCa and 10 benign specimens for their ERG rearrangement status by applying dual-color FISH and CS-ISH ERG break-apart assays to consecutive sections. We observed a highly significant concordance (97.7%) between FISH- and CS-ISH-based results (Pearson's correlation coefficient = 0.955, P < 0.001). Our findings demonstrate that the ERG rearrangement status can reliably be assessed by CS-ISH. Further, the CS-ISH technique combines the accuracy and precision of FISH with the ease of bright-field microscopy. This tool allows a much broader spectrum of applications in which to study the biological role and clinical use of ERG rearrangements in PCa.

  14. Utilisation of X-Ray computed microtomography for evaluation of iron sulphide distribution in roofing slate

    NASA Astrophysics Data System (ADS)

    Souček, Kamil; Daněk, Tomáš; Vavro, Martin; Botula, Jiří

    2016-04-01

    Roofing slate represents a traditional natural stone used for centuries for roofing and other construction applications in various types of buildings. Quality roofing slate must be primarily splittable into large, thin and waterproof tiles. In addition, it must be stable in colour and resistant against weathering. The abundance of mineral phases that weather easily or minerals that are long-term unstable has the effect of reducing the durability of slates in exterior conditions. One of the most problematic rock components, which are in a larger or smaller extent present in almost all slates, are iron sulphides, such as pyrite, marcasite or pyrrhotite. Under common atmospheric conditions, these minerals tend to oxidise, which leads to the formation of limonite and sulphuric acid. As a consequence of the origin of red-brown Fe oxyhydroxides, the undesirable colour changes of the slate may occur. But the most serious problem which occurs during this process is the changes in volume. This can cause disintegration of slate depending on the form of the iron sulphide occurrence. The content and size distribution of iron sulphides in roofing slate is normally determined using the microscopic analysis in transmitted light, combined with the observation in reflected light. For quantitative determination of iron sulphides in slate, the X-Ray powder diffraction is also often used. The results of the microscopic and X-Ray analyses need to be mutually compared and should not differ fundamentally. This paper is focused on the assessing the possibility of application of the X-Ray computed microtomography (CT) as a new complementary technique enabling the analysis of content and size (volume) distribution of iron sulphides in roofing slate. The X-Ray CT study was conducted using an XT H 225 ST industrial micro-tomographic system made by Nikon Metrology NV. Studied samples were reconstructed using the CT Pro 3D software (Nikon Metrology NV). The visualisation and analysis software

  15. The Silver Bullet Syndrome.

    ERIC Educational Resources Information Center

    Dehne, George C.

    1995-01-01

    Many colleges address complex problems with a single "silver bullet" strategy. Because value shifts according to the consumer's situation or goal, private colleges should become more aware of their "situational value" and exploit it. This requires an understanding of how students choose colleges. In contrast, popular silver bullets target…

  16. Silver alloy compositions

    SciTech Connect

    Berhard, M.; Sivertsen, J.T.

    1990-11-27

    This patent describes a silver alloy composition. It comprises essentially all of the following parts by weight: about 89-93.5% silver, about 0.01-2% silicon, about 0.001-2% boron, about 0.5-5% zinc, about 0.5-6% copper, about 0.25-2% tin, and about 0.01-1.25% indium.

  17. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, George A.

    1986-01-01

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  18. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, G.A.

    1985-03-05

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  19. Determination of the reaction rate coefficient of sulphide mine tailings deposited under water.

    PubMed

    Awoh, Akué Sylvette; Mbonimpa, Mamert; Bussière, Bruno

    2013-10-15

    The efficiency of a water cover to limit dissolved oxygen (DO) availability to underlying acid-generating mine tailings can be assessed by calculating the DO flux at the tailings-water interface. Fick's equations, which are generally used to calculate this flux, require knowing the effective DO diffusion coefficient (Dw) and the reaction (consumption) rate coefficient (Kr) of the tailings, or the DO concentration profile. Whereas Dw can be accurately estimated, few studies have measured the parameter Kr for submerged sulphide tailings. The objective of this study was to determine Kr for underwater sulphide tailings in a laboratory experiment. Samples of sulphide mine tailings (an approximately 6 cm layer) were placed in a cell under a water cover (approximately 2 cm) maintained at constant DO concentration. Two tailings were studied: TA1 with high sulphide content (83% pyrite) and TA2 with low sulphide content (2.8% pyrite). DO concentration was measured with a microelectrode at various depths above and below the tailings-water interface at 1 mm intervals. Results indicate that steady-state condition was rapidly attained. As expected, a diffusive boundary layer (DBL) was observed in all cases. An iterative back-calculation process using the numerical code POLLUTEv6 and taking the DBL into account provided the Kr values used to match calculated and experimental concentration profiles. Kr obtained for tailings TA1 and TA2 was about 80 d(-1) and 6.5 d(-1), respectively. For comparison purposes, Kr obtained from cell tests on tailings TA1 was lower than Kr calculated from the sulphate production rate obtained from shake-flask tests. Steady-state DO flux at the water-tailings interface was then calculated with POLLUTEv6 using tailings characteristics Dw and Kr. For the tested conditions, DO flux ranged from 608 to 758 mg O2/m(2)/d for tailings TA1 and from 177 to 221 mg O2/m(2)/d for tailings TA2. The impact of placing a protective layer of inert material over

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

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

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

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

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

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

  2. Development of Technology for Enrichment of Silver Containing Ores

    NASA Astrophysics Data System (ADS)

    Shekiladze, Asmati; Kavtelashvili, Otari; Bagnashvili, Mamuka

    2016-10-01

    The progress of Georgian economics is substantially associated with a development of new deposits of mineral resources. Among them is the David-Gareji deposit where at present the intensive searching geological works are performed. The work goal involves the elaboration of the technology for processing of silver-containing quartz-barite ores. Without its development the mining of more valuable gold-polymetallic ores is impossible. Because of ore complexity silver and barite are considered in a common technological aspect. The investigations were carried out on the representative samples of quartz-barite ores containing 78-88 g/ton of silver and 27-29 % of silver is a nugget in the form of the simple sulphides and chlorides. The ore is characterized by fine coalescence of barite and ore-generating minerals. Non-ferrous metals haven't any industrial value because of their very low content. Therefore, for the processing of the ores under study the direct selective scheme of flotation enrichment was chosen and the formula of optimal reagent regime was elaborated. Potassium xanthogenate is used as a collector for flotation of silver minerals and pine oil- as a foaming agent. The effect of the pulp - pH and medium temperature on silver flotation was studied. It was established that the silver is actively floats in neutral medium. For barite flotation the various collectors were tested: sulfidezid cotton oil-soap stock, soaps of fatty acids and alkyl sulphates of C12 - C16 row, among the “Baritol” is the most efficient one. Depression of the barren rock was carried out by liquid glass in alkaline medium. The effect of pulp pH on barite flotation has been investigated. The best results were obtained at pH=8.5. The increase of the pulp alkalinity has no essential effect on the indexes of the barite enrichment. Conditional concentrate of the barite is obtained by two fold purification of the main flotation concentrate by the addition of the liquid glass to the re

  3. Mineral commodity profiles: Silver

    USGS Publications Warehouse

    Butterman, W.C.; Hilliard, Henry E.

    2005-01-01

    Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

  4. Multilevel modeling of retention and disinfection efficacy of silver nanoparticles on ceramic water filters.

    PubMed

    Mikelonis, Anne M; Lawler, Desmond F; Passalacqua, Paola

    2016-10-01

    This research examined how variations in synthesis methods of silver nanoparticles affect both the release of silver from ceramic water filters (CWFs) and disinfection efficacy. The silver nanoparticles used were stabilized by four different molecules: citrate, polyvinylpyrrolidone, branched polyethylenimine, and casein. A multilevel statistical model was built to quantify if there was a significant difference in: a) extent of silver lost, b) initial amount of silver lost, c) silver lost for water of different quality, and d) total coliform removal. Experiments were performed on location at Pure Home Water, a CWF factory in Tamale, Ghana using stored rainwater and dugout water (a local surface water). The results indicated that using dugout vs. rainwater significantly affects the initial (p-value 0.0015) and sustained (p-value 0.0124) loss of silver, but that silver type does not have a significant effect. On average, dugout water removed 37.5μg/L more initial silver and had 1.1μg/L more silver in the filtrate than rainwater. Initially, filters achieved 1.9 log reduction values (LRVs) on average, but among different silver and water types this varied by as much as 2.5 LRV units. Overall, bacterial removal effectiveness was more challenging to evaluate, but some data suggest that the branched polyethylenimine silver nanoparticles provided improved initial bacterial removal over filters which were not painted with silver nanoparticles (p-value 0.038).

  5. Effects of protein sources on concentrations of hydrogen sulphide in the rumen headspace gas of dairy cows.

    PubMed

    Fonseca, A J M; Cabrita, A R J; Pinho, L A O; Kim, E J; Dewhurst, R J

    2013-01-01

    Two Latin square design experiments investigated the relationship between hydrogen sulphide concentration in the rumen headspace gas of dairy cows and the early stages of protein degradation in the rumen. In Expt 1, three protein sources differing in rumen N (nitrogen) degradability (maize gluten feed (MGF); sunflower meal (SFM); and soyabean meal (SBM)) were used, whereas in Expt 2 four different batches of the same feed (MGF) differing in colour (CIE L*, a*, b* (CIELAB) scale) were used. After allowing the concentration of hydrogen sulphide in rumen gas to decline close to zero, a fixed amount of protein sources was offered to cows and the concentrations of hydrogen sulphide were recorded in rumen headspace gas at 30-min intervals. In Expt 1, the concentration of hydrogen sulphide showed considerable variation between protein sources, with MGF having the highest concentration followed by SFM and SBM resulting in very low concentrations. The N wash losses (zero time measurements with nylon bags) ranked the feeds in the same way, from MGF (highest; 61%) to SBM (lowest; 26%). There were marked differences in the degradation of cystine and methionine between protein sources, although the degradation of cystine was always higher than for methionine. MGF (Expt 2) led to increased concentrations of hydrogen sulphide, with peak concentrations achieved between 1 and 2 h after feeding. The concentrations of hydrogen sulphide were higher for MGF1, intermediate for MGF2 and lower for MGF3 and MGF4, agreeing with colour scale. Differences in the early stages of dietary sulphur degradation corresponded with differences in hydrogen sulphide concentrations in rumen gas. The results suggest that hydrogen sulphide concentrations in the rumen headspace gas could be useful to evaluate nutritional parameters not measured by the in sacco technique, contributing to a better understanding of the response of dairy cows to different protein supplements.

  6. Tourmaline in Appalachian - Caledonian massive sulphide deposits and its exploration significance.

    USGS Publications Warehouse

    Slack, J.F.

    1982-01-01

    Tourmaline is a common gangue mineral in several types of stratabound mineral deposits, including some massive base-metal sulphide ores of the Appalachian - Caledonian orogen. It is most abundant (sometimes forming massive foliated tourmalinite) in sediment-hosted deposits, such as those at the Elizabeth Cu mine and the Ore Knob Cu mine (North Carolina, USA). Trace amounts of tourmaline occur associated with volcanic-hosted deposits in the Piedmont and New England and also in the Trondheim district. Tourmaline associated with the massive sulphide deposits are Mg- rich dravites with major- and trace-element compositions significantly different from schorl. It is suggested that the necessary B was produced by submarine exhalative processes as a part of the same hydrothermal system that deposited the ores. An abundance of dravite in non-evaporitic terrains is believed to indicate proximity to former subaqueous fumarolic centres.-R.A.H.

  7. Influence of zinc precursor concentration on properties zinc sulphide thin films using spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Veena, E.; Bangera, Kasturi V.; Shivakumar, G. K.

    2017-07-01

    Stoichiometric high transparent n-zinc sulphide thin films were prepared using chemical spray pyrolysis technique. The concentration of the cationic precursor played a major role to obtain stoichiometry, regardless of various deposition parameters. Zinc sulphide films deposited at 450˚C for the ratio 0.33:1 (Zn:S) resulted in well oriented, stoichiometric polycrystalline cubic structure. The variation in crystallite size associated with the cationic precursor concentration provides significant control over the structural, optical and electrical properties of the films. The optical band gap and activation energy of stoichiometric ZnS films were found to be 3.54 ± 0.02eV and 0.82 ± 0.05eV, respectively. The absorption coefficient of the films was found to be 102 cm-1.

  8. Application of ZnO Nanoparticle as Sulphide Gas Sensor Using UV/VIS/NIR-Spectrophotometer

    NASA Astrophysics Data System (ADS)

    Juliasih, N.; Buchari; Noviandri, I.

    2017-04-01

    The nanoparticle of metal oxides has great unique characteristics that applicable to the wide industrial as sensors and catalysts for reducing environmental pollution. Sulphide gas monitors and detectors are required for assessing safety aspects, due to its toxicity level. A thin film of ZnO as the sulphide gas sensor was synthesised by the simple method of chemical liquid deposition with variation of annealing temperature from 200 ºC to 500 ºC, and characterised by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and UV/VIS/NIR-Spectrophotometer. Characterization studies showed nanoparticle size from the range 62 - 92 nm of diameters. The application this ZnO thin film to sulfide gas, detected by UV/VIS/NIR Spectrophotometer with diffuse reflectance, showed specific chemical reaction by the shifting of maximum % Reflectance peak. The gas sensing using this method is applicable at room.

  9. Silver as a disinfectant.

    PubMed

    Silvestry-Rodriguez, Nadia; Sicairos-Ruelas, Enue E; Gerba, Charles P; Bright, Kelly R

    2007-01-01

    Silver has been used as an antimicrobial for thousands of years. Over the past several decades, it has been introduced into numerous new venues such as in the treatment of water, in dietary supplements, in medical applications, and to produce antimicrobial coatings and products. Silver is often used as an alternative disinfectant in applications in which the use of traditional disinfectants such as chlorine may result in the formation of toxic by-products or cause corrosion of surfaces. Silver has also been demonstrated to produce a synergistic effect in combination with several other disinfectants. Many mechanisms of the antibacterial effect of silver have been described, but its antiviral and antiprotozoal mechanisms are not well understood. Both microbial tolerance and resistance to silver have been reported; however, the effect of silver has been observed against a wide variety of microorganisms over a period of years. Further research is needed to determine the antimicrobial efficacy of silver in these new applications and the effects of its long-term usage.

  10. Effect of Silver Flakes in Silver Paste on the Joining Process and Properties of Sandwich Power Modules (IGBTs Chip/Silver Paste/Bare Cu)

    NASA Astrophysics Data System (ADS)

    Zhao, Su-Yan; Li, Xin; Mei, Yun-Hui; Lu, Guo-Quan

    2016-11-01

    In this study, a silver paste has been introduced for attaching chips onto bare Cu substrates (without coating) without applying pressure. Small nano-thickness Ag flakes, measuring 1 μm-5 μm length, were embedded uniformly in Ag nanoparticles for improving the density of the material. The presence of silver flakes in the silver paste affected the joining process and its microstructure. Microstructure characterization revealed that densification of the silver layer was affected by the presence of silver flakes as the flakes coarsened and formed reactive in situ nanoparticles, which facilitated the sintering between the flakes and the incorporated nanoparticles. Coarsening of silver flakes depended on the sintering temperature, time, and the atmosphere, which affected the decomposition and burning out of organics presented on the surface of the flakes. A high-density silver layer was obtained due to the presence of compact silver flakes. With an increase in the microstructure density, a higher bonding strength and a lower thermal impedance of the sintered joints were achieved. On performing pressureless sintering at 270°C for 30 min under 99.99% N2 or 4% H2/N2, the bonding strength and thermal impedance for 11 × 11 mm2 chips were excellent, measuring approximately 21.9 MPa and 0.077°C/W, respectively.

  11. Problems Caused by Microbes and Treatment Strategies Health and Safety Issues from the Production of Hydrogen Sulphide

    NASA Astrophysics Data System (ADS)

    Williamson, Nicole

    Hydrogen sulphide (H2S) is a colourless, transparent gas that is heavier than air (SG = 1.18). It is extremely flammable and is explosive across a very wide range of concentrations 4.3-46% by volume in air (in comparison, methane is explosive at 5-15% volume in air). The boiling point of hydrogen sulphide is -60°C and so it exists as a gas at standard conditions; it burns with a blue flame to produce water and sulphur dioxide, which is also a very toxic gas. At low concentrations hydrogen sulphide has a very pungent smell, typically described as 'rotten eggs'; at higher concentrations it can become sickly sweet. Hydrogen sulphide can be easily identified by its smell at very low concentrations, detectable down to 0.0047 ppm (HSE, 2009). However, smell alone cannot be relied upon to detect the continued presence of hydrogen sulphide. At high concentrations, or after sustained exposure to lower concentrations, hydrogen sulphide becomes undetectable by smell as it rapidly paralyses the olfactory nerve.

  12. New insights into the Re-Os systematics of sub-continental lithospheric mantle from in situ analysis of sulphides

    NASA Astrophysics Data System (ADS)

    Alard, Olivier; Griffin, William L.; Pearson, Norman J.; Lorand, Jean-Pierre; O'Reilly, Suzanne Y.

    2002-10-01

    The Os isotopic compositions of mantle rocks generally are considered to be established during melt-depletion events and to be robust to subsequent disturbances (e.g. metasomatism). Consequently, Os isotopes are used to date the main melting event that a mantle section has undergone, i.e. transformation of fertile asthenospheric material into a depleted, buoyant lithosphere. However, Os resides almost entirely in Fe-Ni-Cu sulphides, which can be very mobile under mantle conditions. In situ laser ablation multi-collector ICP-MS measurement of Re/Os isotopic ratios in sulphides from spinel peridotite xenoliths demonstrates that whole-rock Os-isotope signatures record the mixing of multiple sulphide populations. Sulphides residual after melting events have unradiogenic Os isotopic compositions reflecting ancient melt depletion; those introduced by later metasomatism events contain more radiogenic Os. Therefore, the whole-rock Os isotopic signature can be strongly altered by metasomatic processes, and studies of mantle-derived xenoliths show that such disturbance is quite common in the lithospheric mantle. Because melt-depletion ages estimated from individual sulphide inclusions are systematically older than those obtained from whole-rock analysis, caution is essential in the interpretation of the Os model ages derived from whole-rock analysis, and their use and abuse in geodynamic models. This work suggests that sulphide could become a key phase in unravelling the formation and evolution of the lithosphere.

  13. Disseminated sulphides in basalts from the northern Central Indian Ridge: implications on late-stage hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Banerjee, Ranadip; Ray, Dwijesh

    2015-04-01

    This study examined the mineralogy and mineral chemistry of disseminated sulphides (mainly chalcopyrite-pyrite) in partly altered basalts from the northern Central Indian Ridge, Indian Ocean in order to understand the role of hydrothermal alterations and infer possible sulphide formation history. Pyrite and chalcopyrite are dominant sulphide minerals and generally associated with the oxide phases including magnetite and often ilmenite. Close association of sulphide and oxide minerals suggests that they are paragenetically related. Sulphides also occur as late impregnated veins cutting through the basaltic hosts. The chemical compositions of pyrite (avg. Fe 46.3 wt%, S 53.7 wt%) and chalcopyrite (avg. Cu 34.4 wt%, Fe 30.7 wt%, S 34.7 wt%) are almost uniform, while the secondary ilmenite often shows MnO enrichment (up to 3.0-3.4 wt%). The associated altered minerals typically resemble the greenschist facies mineral assemblages—e.g. chlorite±epidote. Evidence of albitisation and silicification suggests low-temperature hydrothermal alteration processes. This is supported by the bulk Au content (up to 60 ppb) of host-altered basalts with pyrite mineralisation. Au is usually associated with late-stage pyrites and thus related with low-temperature hydrothermal activity. Close to the dredge location, tectonic activity around the Vityaz megamullion might have promoted hydrothermal circulation and subsequent alteration of the mineral constituents in basalts, eventually inducing the formation of late-stage disseminated sulphide minerals in these rocks.

  14. Three-phase solvent bar micro-extraction as an approach to silver ultra-traces speciation in estuarine water samples.

    PubMed

    López-López, José Antonio; Herce-Sesa, Belén; Moreno, Carlos

    2015-01-01

    Silver ion inputs into the environment due to human activities have been increased in the last years because it has been used as a bactericide with application in medical, homecare and self-care products. In addition, it is toxic at low concentration for aquatic organisms. In estuarine waters, salinity and dissolved organic matter (DOM) regulate Ag(+) concentration by the formation of complexes as AgCln((n-1)-) and Ag-DOM. Difficulties of Ag(+) analysis in estuaries are associated to its low concentration level and interferences of sample matrix. Liquid and solid phase extraction methods have been used for speciation of silver in waters; however, miniaturized methods that offer a better environmental profile are desirable. Hollow fiber liquid phase micro-extraction (HFLPME) allows obtaining higher pre-concentration factors with a reduction of waste generation. Notwithstanding, some operational improvements are needed to permit their use as a routine method that can be afforded using a configuration of three-phase solvent bar micro-extraction (3PSBME). In this work, tri-isobutylphosphine sulphide (TIBPS) has been used as an extractant for Ag(+) pre-concentration in estuarine waters by 3PSBME. Under optimized conditions, Ag(+) has been pre-concentrated 60 times and the method presents a limit of detection of 1.53 ng L(-1). To evaluate which Ag species is transported by TIBPS, Cl(-) and DOM have been added to synthetic samples. As a result, a decrease in Ag pre-concentration efficiency after additions has been observed and quantified. Results showed that Ag(+) is selectively transported by TIBPS from estuarine water samples after comparison of the results with those obtained by the reference method of liquid extraction with APDC/DDDC. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Biotic conversion of sulphate to sulphide and abiotic conversion of sulphide to sulphur in a microbial fuel cell using cobalt oxide octahedrons as cathode catalyst.

    PubMed

    Chatterjee, Pritha; Ghangrekar, M M; Rao, Surampalli; Kumar, Senthil

    2017-02-08

    Varying chemical oxygen demand (COD) and sulphate concentrations in substrate were used to determine reaction kinetics and mass balance of organic matter and sulphate transformation in a microbial fuel cell (MFC). MFC with anodic chamber volume of 1 L, fed with wastewater having COD of 500 mg/L and sulphate of 200 mg/L, could harvest power of 54.4 mW/m(2), at a Coulombic efficiency of 14%, with respective COD and sulphate removals of 90 and 95%. Sulphide concentration, even up to 1500 mg/L, did not inhibit anodic biochemical reactions, due to instantaneous abiotic oxidation to sulphur, at high inlet sulphate. Experiments on abiotic oxidation of sulphide to sulphur revealed maximum oxidation taking place at an anodic potential of -200 mV. More than 99% sulphate removal could be achieved in a MFC with inlet COD/sulphate of 0.75, giving around 1.33 kg/m(3) day COD removal. Bioelectrochemical conversion of sulphate facilitating sulphur recovery in a MFC makes it an interesting pollution abatement technique.

  16. The transition to a sulphidic ocean approximately 1.84 billion years ago.

    PubMed

    Poulton, Simon W; Fralick, Philip W; Canfield, Donald E

    2004-09-09

    The Proterozoic aeon (2.5 to 0.54 billion years (Gyr) ago) marks the time between the largely anoxic world of the Archean (> 2.5 Gyr ago) and the dominantly oxic world of the Phanerozoic (< 0.54 Gyr ago). The course of ocean chemistry through the Proterozoic has traditionally been explained by progressive oxygenation of the deep ocean in response to an increase in atmospheric oxygen around 2.3 Gyr ago. This postulated rise in the oxygen content of the ocean is in turn thought to have led to the oxidation of dissolved iron, Fe(II), thus ending the deposition of banded iron formations (BIF) around 1.8 Gyr ago. An alternative interpretation suggests that the increasing atmospheric oxygen levels enhanced sulphide weathering on land and the flux of sulphate to the oceans. This increased rates of sulphate reduction, resulting in Fe(II) removal in the form of pyrite as the oceans became sulphidic. Here we investigate sediments from the approximately 1.8-Gyr-old Animikie group, Canada, which were deposited during the final stages of the main global period of BIF deposition. This allows us to evaluate the two competing hypotheses for the termination of BIF deposition. We use iron-sulphur-carbon (Fe-S-C) systematics to demonstrate continued ocean anoxia after the final global deposition of BIF and show that a transition to sulphidic bottom waters was ultimately responsible for the termination of BIF deposition. Sulphidic conditions may have persisted until a second major rise in oxygen between 0.8 to 0.58 Gyr ago, possibly reducing global rates of primary production and arresting the pace of algal evolution.

  17. The transition to a sulphidic ocean ~ 1.84 billion years ago

    NASA Astrophysics Data System (ADS)

    Poulton, Simon W.; Fralick, Philip W.; Canfield, Donald E.

    2004-09-01

    The Proterozoic aeon (2.5 to 0.54 billion years (Gyr) ago) marks the time between the largely anoxic world of the Archean (> 2.5Gyr ago) and the dominantly oxic world of the Phanerozoic (< 0.54Gyr ago). The course of ocean chemistry through the Proterozoic has traditionally been explained by progressive oxygenation of the deep ocean in response to an increase in atmospheric oxygen around 2.3Gyr ago. This postulated rise in the oxygen content of the ocean is in turn thought to have led to the oxidation of dissolved iron, Fe(II), thus ending the deposition of banded iron formations (BIF) around 1.8Gyr ago. An alternative interpretation suggests that the increasing atmospheric oxygen levels enhanced sulphide weathering on land and the flux of sulphate to the oceans. This increased rates of sulphate reduction, resulting in Fe(II) removal in the form of pyrite as the oceans became sulphidic. Here we investigate sediments from the ~1.8-Gyr-old Animikie group, Canada, which were deposited during the final stages of the main global period of BIF deposition. This allows us to evaluate the two competing hypotheses for the termination of BIF deposition. We use iron-sulphur-carbon (Fe-S-C) systematics to demonstrate continued ocean anoxia after the final global deposition of BIF and show that a transition to sulphidic bottom waters was ultimately responsible for the termination of BIF deposition. Sulphidic conditions may have persisted until a second major rise in oxygen between 0.8 to 0.58Gyr ago, possibly reducing global rates of primary production and arresting the pace of algal evolution.

  18. Surface Passivation for 3-5 Semiconductor Processing: Stable Gallium Sulphide Films by MOCVD

    NASA Technical Reports Server (NTRS)

    Macinnes, Andrew N.; Jenkins, Phillip P.; Power, Michael B.; Kang, Soon; Barron, Andrew R.; Hepp, Aloysius F.; Tabib-Azar, Massood

    1994-01-01

    Gallium sulphide (GaS) has been deposited on GaAs to form stable, insulating, passivating layers. Spectrally resolved photoluminescence and surface recombination velocity measurements indicate that the GaS itself can contribute a significant fraction of the photoluminescence in GaS/GaAs structures. Determination of surface recombination velocity by photoluminescence is therefore difficult. By using C-V analysis of metal-insulator-semiconductor structures, passivation of the GaAs with GaS films is quantified.

  19. Photothermal theragnosis synergistic therapy based on bimetal sulphide nanocrystals rather than nanocomposites.

    PubMed

    Li, Bo; Ye, Kaichuang; Zhang, Yuxin; Qin, Jinbao; Zou, Rujia; Xu, Kaibing; Huang, Xiaojuan; Xiao, Zhiyin; Zhang, Wenjun; Lu, Xinwu; Hu, Junqing

    2015-02-25

    A new generation of photothermal theranostic agents is developed based on Cu3BiS3 nanocrystals. A computed tomography imaging response and photothermal effect, as well as near-infrared fluorescence emission, can be simultaneously achieved through Cu3BiS3 nanocrystals rather than frequently used nanocomposites. These results provide some insight into the synergistic effect from bimetal sulphide semiconductor compounds for photothermal theragnosis therapy.

  20. Quantitative examination of carbide and sulphide precipitates in chemically complex steels processed by direct strip casting

    SciTech Connect

    Dorin, Thomas; Wood, Kathleen; Taylor, Adam; Hodgson, Peter; Stanford, Nicole

    2016-02-15

    A high strength low alloy steel composition has been melted and processed by two different routes: simulated direct strip casting and slow cooled ingot casting. The microstructures were examined with scanning and transmission electron microscopy, atom probe tomography and small angle neutron scattering (SANS). The formation of cementite (Fe{sub 3}C), manganese sulphides (MnS) and niobium carbo-nitrides (Nb(C,N)) was investigated in both casting conditions. The sulphides were found to be significantly refined by the higher cooling rate, and developed an average diameter of only 100 nm for the fast cooled sample, and a diameter too large to be measured with SANS in the slow cooled condition (> 1.1 μm). Slow cooling resulted in the development of classical Nb(C,N) precipitation, with an average diameter of 7.2 nm. However, after rapid cooling both the SANS and atom probe tomography data indicated that the Nb was retained in the matrix as a random solid solution. There was also some evidence that O, N and S are also retained in solid solution in levels not found during conventional processing. - Highlights: • The influence of cooling rate on microstructure is investigated in a HSLA steel. • SANS, TEM and APT are used to characterise the sulphides and Nb(C,N) precipitates. • The slow cooling rate result in the formation of Nb(C,N) precipitates. • The fast cooling rate results in a microstructure supersaturated in Nb, C and N. • The sulphides are 100 nm in the fast cooled sample and > 1 μm in the slow cooled one.

  1. Case studies of hydrogen sulphide occupational exposure incidents in the UK.

    PubMed

    Jones, Kate

    2014-12-15

    The UK Health and Safety Executive has investigated several incidents of workplace accidents involving hydrogen sulphide exposure in recent years. Biological monitoring has been used in some incidents to determine the cause of unconsciousness resulting from these incidents and as a supporting evidence in regulatory enforcement. This paper reports on three case incidents and discusses the use of biological monitoring in such cases. Biological monitoring has a role in identifying hydrogen sulphide exposure in incidents, whether these are occupational or in the wider environment. Sample type, time of collection and sample storage are important factors in the applicability of this technique. For non-fatal incidents, multiple urine samples are recommended at two or more time points between the incident and 15 h post-exposure. For routine occupational monitoring, post-shift samples should be adequate. Due to endogenous levels of urinary thiosulphate, it is likely that exposures in excess of 12 ppm for 30 min (or 360 ppm/min equivalent) would be detectable using biological monitoring. This is within the Acute Exposure Guideline Level 2 (the level of the chemical in air at or above which there may be irreversible or other serious long-lasting effects or impaired ability to escape) for hydrogen sulphide.

  2. Dynamic character of the hydrothermal vent habitat and the nature of sulphide chimney fauna

    NASA Astrophysics Data System (ADS)

    Tunnicliffe, Verena; Kim Juniper, S.

    A major substratum for vent organisms on Juan de Fuca and Explorer Ridges of the northeast Pacific is the polymetallic sulphide chimney. The deposition processes and subsequent growth of such chimneys provide a dynamic and extreme habitat that changes rapidly. During initial venting stages, colonization must await stabilization of the chimney structure. As the porous anhydrite shell accumulates sulphide minerals, protection from direct hot water contact increases for organisms colonizing the outer walls while sufficient vent water still diffuses for the support of chemosynthesis. Vestimentiferan worms are found on small sulphide mounds but the active growth and collapse of anhydrite spires is a major source of disruption and mortality. High temperature venting and spire growth appear to attract alvinellid polychaetes which may be implicated in the process of strengthening and sealing the anhydrite spires. Fauna on the growing chimney is subject to changes in fluid flow patterns that can make the structure uninhabitable. Large chimneys are inhabited by more species indicating that a diversification of habitat results from variations in mineralization and fluid availability. Chimney fauna has become specialized in exploiting an unpredictable and unstable habitat in an extreme example of the control of biotic development by the physical environment.

  3. Cleaner processing: a sulphide-free approach for depilation of skins.

    PubMed

    Ranjithkumar, Ammasi; Durga, Jayanthi; Ramesh, Ramakrishnan; Rose, Chellan; Muralidharan, Chellappa

    2017-01-01

    The conventional unhairing process in leather making utilises large amount of lime and sodium sulphide which is hazardous and poses serious waste disposal concerns. Under acidic conditions, sodium sulphide liberates significant quantities of hydrogen sulphide which causes frequent fatal accidents. Further, the conventional unhairing process involves destruction of the hair leading to increased levels of biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS) and total suspended solids (TSS) in the effluent. A safe approach is needed to overcome such environmental and health problems through an eco-benign process. The present study deals with a clean technology in which the keratinous body is detached from the dermis using enzymes produced from Bacillus crolab MTCC 5468 by solid state fermentation (SSF) as an alternative to noxious chemicals. Complete unhairing of skin could be achieved with an enzyme concentration of 1.2 % (w/w). The bio-chemical parameters of the spent liquor of the enzymatic process were environmentally favourable when compared with conventional method. The study indicates that the enzymatic unhairing is a safe process which could be used effectively in leather processing to alleviate pollution and health problems.

  4. Sulphide production and corrosion in seawaters during exposure to FAME diesel.

    PubMed

    Lee, Jason S; Ray, Richard I; Little, Brenda J; Duncan, Kathleen E; Oldham, Athenia L; Davidova, Irene A; Suflita, Joseph M

    2012-01-01

    Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60 day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.

  5. Determination of dimethyl selenide and dimethyl sulphide compounds causing off-flavours in bottled mineral waters.

    PubMed

    Guadayol, Marta; Cortina, Montserrat; Guadayol, Josep M; Caixach, Josep

    2016-04-01

    Sales of bottled drinking water have shown a large growth during the last two decades due to the general belief that this kind of water is healthier, its flavour is better and its consumption risk is lower than that of tap water. Due to the previous points, consumers are more demanding with bottled mineral water, especially when dealing with its organoleptic properties, like taste and odour. This work studies the compounds that can generate obnoxious smells, and that consumers have described like swampy, rotten eggs, sulphurous, cooked vegetable or cabbage. Closed loop stripping analysis (CLSA) has been used as a pre-concentration method for the analysis of off-flavour compounds in water followed by identification and quantification by means of GC-MS. Several bottled water with the aforementioned smells showed the presence of volatile dimethyl selenides and dimethyl sulphides, whose concentrations ranged, respectively, from 4 to 20 ng/L and from 1 to 63 ng/L. The low odour threshold concentrations (OTCs) of both organic selenide and sulphide derivatives prove that several objectionable odours in bottled waters arise from them. Microbial loads inherent to water sources, along with some critical conditions in water processing, could contribute to the formation of these compounds. There are few studies about volatile organic compounds in bottled drinking water and, at the best of our knowledge, this is the first study reporting the presence of dimethyl selenides and dimethyl sulphides causing odour problems in bottled waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Effects of Sulphate-Sulphide Mineral Water “Mlječanica” in Patients with Hypertension

    PubMed Central

    Erceg-Rukavina, Tatjana; Stefanovski, Mihajlo

    2014-01-01

    Introduction: Arterial hypertension is the main independent risk factor for cardiovascular (CV) disease and death. It affects development and course of cerebrovascular insult (CVI) and chronic kidney disease (CKD). Balneotherapy with sulphide baths was administered to patients having stage I hypertension (BP values 140-159/90-99), with no arrhythmia or pronounced coronary disease. Baths also had advantage in patients having hypertension joined with obesity, diabetes, microangiopathy, and atherosclerosis of peripheral arteries. Goal: Determine the effects of sulphate-sulphide mineral baths on stage I hypertension after 10 days therapy. Materials and methods: Patients having stage I hypertension were sent to “Mlječanica” Institute for rehabilitation. All subjects were treated with kinesitherapy and electrotherapy, while experimental group (n=30) was also treated with 20 minute baths, daily, for period of 10 days. Results: In experimental group BP level lowered in average 10 mmHg after 10-day therapy, and change was evident even after only 5 days. Conclusion: Sulphate-sulphide mineral water “Mlječanica” caused significant (p<0.05) lowering of arterial BP level after 10 days of therapy in patients who had stage I hypertension. PMID:25685078

  7. In situ fluctuations of oxygen and sulphide in marine microbial sediment ecosystems

    NASA Astrophysics Data System (ADS)

    De Wit, Rutger; Jonkers, Henk M.; Van Den Ende, Frank P.; Van Gemerden, Hans

    Laminated microbial ecosystems (microbial mats) on the island of Schiermonnikoog (The Netherlands) were studied with respect to variation in oxygen and sulphide profiles, depth distributions of photopigments and viable number and cell volume of purple sulphur bacteria. Cyanobacteria occurred in the top 2 mm, the dominant species being Microcoleus chthonoplastes. The blooming of purple sulphur bacteria below the cyanobacterial layer was observed in autumn, the dominant species being the immotile Thiocapsa roseopersicina. Cell volume of this species is indicative of its growth rate. In situ measurements showed strong diel fluctuations in oxygen and sulphide profiles. Frequently, cyanobacteria and purple sulphur bacteria were exposed to oxygen during the day, and to anoxic conditions at night. Sulphide sometimes reached the layer of the cyanobacteria. The cyanobacteria and the purple sulphur bacteria both are very well adapted to these diel fluctuations. In addition, strong seasonal variations were observed, whereas short-term fluctuations of oxygen occurred due to changing light-climate and rainfall. Attention was paid to the unusual occurrence of microbial mats on the North Sea beach during the autumn of 1987.

  8. Sulphide mineral evolution and metal mobility during alteration of the oceanic crust: Insights from ODP Hole 1256D

    NASA Astrophysics Data System (ADS)

    Patten, C. G. C.; Pitcairn, I. K.; Teagle, D. A. H.; Harris, M.

    2016-11-01

    Fluxes of metals during the hydrothermal alteration of the oceanic crust have far reaching effects including buffering of the compositions of the ocean and lithosphere, supporting microbial life and the formation of sulphide ore deposits. The mechanisms responsible for metal mobilisation during the evolution of the oceanic crust are complex and are neither fully constrained nor quantified. Investigations into the mineral reactions that release metals, such as sulphide leaching, would generate better understanding of the controls on metal mobility in the oceanic crust. We investigate the sulphide and oxide mineral paragenesis and the extent to which these minerals control the metal budget in samples from Ocean Drilling Program (ODP) Hole 1256D. The ODP Hole 1256D drill core provides a unique sample suite representative of a complete section of a fast-spreading oceanic crust from the volcanic section down to the plutonic complex. The sulphide population at Hole 1256D is divided into five groups based on mineralogical assemblage, lithological location and texture: the magmatic, metasomatised, high temperature hydrothermal, low temperature and patchy sulphides. The initiation of hydrothermal alteration by downward flow of moderate temperature (250-350 °C) hydrothermal fluids under oxidising conditions leads to metasomatism of the magmatic sulphides in the sheeted dyke and plutonic complexes. Subsequent increase in the degree of hydrothermal alteration at temperatures >350 °C under reducing conditions then leads to the leaching of the metasomatised sulphides by rising hydrothermal fluids. Mass balance calculations show that the mobility of Cu, Se and Au occurs through sulphide leaching during high temperature hydrothermal alteration and that the mobility of Zn, As, Sb and Pb is controlled by silicate rather than sulphide alteration. Sulphide leaching is not complete at Hole 1256D and more advanced alteration would mobilise greater masses of metals. Alteration of oxide

  9. Sintering Behavior and Effect of Silver Nanowires on the Electrical Conductivity of Electrically Conductive Adhesives.

    PubMed

    Xie, H; Xiong, N N; Wang, Y H; Zhao, Y Z; Li, J Z

    2016-01-01

    In this paper, two kinds of silver nanowires with a 160 nm average diameter ranging from 30 to 90 µm length and a 450 nm average diameter up to 100 µm length were successfully synthesized by a polyol process with FeCl3 and Na₂S as reaction inhibitor, respectively. The experimental results indicate that the morphologies and sintering behaviors of both of silver nanowires are impacted by glutaric acid and sintering temperature. The isotropically conductive adhesives (ICAs) filled with micro-sized silver flakes and silver nanowires as hybrid fillers were fabricated and the electrical properties were investigated based on the fraction of the silver nanowires of the total of silver fillers and the curing temperature, etc. The in situ monitoring the variation in electrical resistance of the ICAs explores that silver nanowires have influence on the curing behavior of the ICAs. Silver nanowires synthesized with Na2S as reaction inhibitor and treated with glutaric acid can significantly improve the electrical conductivity of the ICAs in the case of the low loading of silver fillers in the appropriate proportion range of the weight ratio of micro-sized silver flakes and silver nanowires, primarily as a result of connecting effect. When the loading of silver fillers in the ICAs is high, the electrical conductivity is also enhanced slightly in the case of the proper fraction of silver nanowires of the total of silver fillers. The effect of the curing temperature on the electrical conductivity relates to the fraction of silver nanowires and the total loading of silver fillers. The electrical conductivity of the ICAs filled with micro-sized silver flakes and silver nanowires synthesized with FeCl₃ as reaction inhibitor is greatly damaged, indicating that the size of silver nanowires also is one of main factor to impact the electrical conductivity of the ICAs doped with silver nanowires. The electrical property of the ICAs filled with micro-sized silver flakes and silver

  10. A field measurement perspective on the current and future use of carbonyl sulphide as a carbon cycle tracer

    NASA Astrophysics Data System (ADS)

    Maseyk, Kadmiel; Sun, Wu; Lett, Celine; Juarez, Sabrina; Seibt, Ulli

    2015-04-01

    Carbonyl sulphide (COS) is gaining increasing traction as a tracer to constrain gross terrestrial biosphere-atmosphere CO2 fluxes, due to the close coupling between photosynthesis and COS uptake by plants. Results from laboratory, field and atmospheric measurements, combined with modeling analyses, have all confirmed the potential of COS, but as with any new approach, many details still remain to be resolved. Drawing on results from our field campaigns that include component (branch and soil) and ecosystem COS flux measurements in a range of environments, I will provide a view on what we have learned about using COS as a carbon cycle tracer. These measurements support the view that ecosystem COS fluxes are typically dominated by canopy uptake, and have provided insight into carbon cycle processes not available from CO2 measurements alone. They have also provided some interesting surprises that suggest COS data may also provide information on other biogeochemical and plant processes such as phenology. Our results support the addition of COS to our measurement arsenal to improve our understanding and monitoring of the terrestrial biosphere, but moving forward will require addressing some key uncertainties. These include the role of the soil and the variation in the leaf-level COS to CO2 uptake ratio in different environments. Combining COS with stable isotope tracers, particularly CO2, can provide a powerful way with which to both improve our understanding of COS biogeochemistry and constrain our estimates of terrestrial CO2 fluxes.

  11. Give silver a shine.

    PubMed

    Fromm, Katharina M

    2011-02-01

    Katharina M. Fromm explains how, as well as catalysis and jewellery, silver serves a myriad of medicinal applications--some of which are even behind poetic traditions such as throwing coins in wishing wells.

  12. Give silver a shine

    NASA Astrophysics Data System (ADS)

    Fromm, Katharina M.

    2011-02-01

    Katharina M. Fromm explains how, as well as catalysis and jewellery, silver serves a myriad of medicinal applications - some of which are even behind poetic traditions such as throwing coins in wishing wells.

  13. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  14. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    PubMed Central

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nano-silver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nano-silver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over four orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by pre-oxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and release inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through bacterial inhibition zone assay carried out on selected formulations of controlled release nano-silver. PMID:20968290

  15. Silver superlens using antisymmetric surface plasmon modes.

    PubMed

    Lee, Wook-Jae; Kim, Jae-Eun; Park, Hae Yong; Lee, Myung-Hyun

    2010-03-15

    Silver lenses having super-resolution are analyzed in terms of antisymmetric modes of surface plasmon which have the ability to amplify evanescent waves in UV region. Antisymmetric surface plasmon modes excited by subwavelength grating enhances the resolution and contrast of silver superlens. By using a 20 nm-thick silver superlens, the half-pitch resolution of approximately lambda(0)/8 can be achieved with good contrast at a free space wavelength of 435 nm. The resolution of silver superlens can also be improved using shorter illumination wavelength. We show that the thinner the lens, the better the imaging ability of the silver superlens due to the excitation of antisymmetric surface plasmon modes of higher propagation wave vectors. The thickness of lens is varied from 20 to 40 nm in a three layer system, SiO(2)-Ag-SiO(2). Obtained results illustrate that practical application for patterning periodic structures with good contrast and penetration depth can be achieved by using antisymmetric surface plasmon modes.

  16. Silver nanoparticles decorated lipase-sensitive polyurethane micelles for on-demand release of silver nanoparticles.

    PubMed

    Su, Yuling; Zhao, Lili; Meng, Fancui; Wang, Quanxin; Yao, Yongchao; Luo, Jianbin

    2017-04-01

    In order to improve the antibacterial activities while decrease the cytotoxity of silver nanoparticles, we prepared a novel nanocomposites composed of silver nanoparticles decorated lipase-sensitive polyurethane micelles (PUM-Ag) with MPEG brush on the surface. The nanocomposite was characterized by UV-vis, TEM and DLS. UV-vis and TEM demonstrated the formation of silver nanoparticles on PU micelles and the nanoassembly remained intact without the presence of lipase. The silver nanoparticles were protected by the polymer matrix and PEG brush which show good cytocompatibility to HUVEC cells and low hemolysis. Moreover, at the presence of lipase, the polymer matrix of nanocomposites is subject to degradation and the small silver nanoparticles were released as is shown by DLS and TEM. The MIC and MBC studies showed an enhanced toxicity of the nanocomposites to both gram negative and gram positive bacteria, i.e. E. coli and S. aureus, as the result of the degradation of polymer matrix by bacterial lipase. Therefore, the nanocomposites are biocompatible to mammalian cells cells which can also lead to activated smaller silver nanoparticles release at the presence of bacteria and subsequently enhanced inhibition of bacteria growth. The satisfactory selectivity for bacteria compared to HUVEC and RBCs make PUM-Ag a promising antibacterial nanomedicine in biomedical field.

  17. Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Campillo Gloria, E.; Ederley, Vélez; Gladis, Morales; César, Hincapié; Jaime, Osorio; Oscar, Arnache; Uribe José, Ignacio; Franklin, Jaramillo

    2017-06-01

    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ~ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated.

  18. Modifications to the silver physical developer.

    PubMed

    Burow, David; Seifert, Donald; Cantu, Antonio A

    2003-09-01

    The silver physical developer is currently the most successful reagent used for visualizing the water-insoluble components (e.g., lipids) of latent prints on porous surfaces. It is normally used after the amino acid visualizing reagents (e.g., ninhydrin and DFO) are used. This work found that the performance of the current formulation of silver physical developer is strongly reduced when the water used is changed from the usual distilled water to the more purified reverse osmosis/deionized (RO/DI) water. Based on numerous experiments involving the systematic variation of the component concentrations, the performance was restored and even improved by reducing the concentration of all the components (except that of the ferric salt) and by including malic acid in the formulation. These modifications resulted in a new silver physical developer formulation that performs as well as or better than the current formulation and is less expensive to make.

  19. Using surface plasmon resonances to test the durability of silver-copper films.

    PubMed

    Bussjager, R J; Macleod, H A

    1996-09-01

    Silver has high reflectivity in the visible and infrared but cannot be used fully because of its distressing lack of durability. A technique that uses the surface plasmon resonance phenomenon offers a sensitive method for studying the corrosion of silver and assessing improvements. It has been used in the investigation of the effects of flashing a thin layer, approximately 1 nm thick, of copper over silver in an attempt at cathodic protection. Tests include exposing silver and silver-copper films to air, 94% relative humidity, water, and hydrogen sulfide.

  20. Granulite sulphides as tracers of lower crustal origin and evolution: An example from the Slave craton, Canada

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Krauss, Cristen; Creaser, Robert A.; Stachel, Thomas; Heaman, Larry M.; Matveev, Sergei; Chacko, Thomas

    2010-09-01

    We carried out a detailed study of sulphide minerals, a ubiquitous mineral group in lower crustal mafic to peraluminous granulite xenoliths from the Diavik kimberlites, to assess their use in constraining the origin and tectonothermal evolution of the deep crust, and to obtain additional data on the composition of lower crust beneath ancient continents. Sulphides are overwhelmingly pyrrhotite with minor Ni (0.7-3.9 at.%), Co (0.1-0.7 at.%), and Cu contents (0.4-3.9 at.%). Sulphide modes in mafic granulites range from 0.14 to 0.55 vol%, translating into bulk rock S contents from ˜600 to 2000 ppm, similar to S contents in other mafic igneous rocks and indicating preservation of primary igneous S contents. In mafic granulites, Re and Os abundances in sulphides range from 42.5 to 726 ppb and 3.2 to 180 ppb, respectively, whereas those in peraluminous granulites are distinctly lower (36.1-282 ppb and 1.8-7.2 ppb, respectively), suggestive of Re and Os loss to fractionating sulphides in the more evolved precursors of these rocks. The significant within-sample variability of 187Os/ 188Os and correlation with 187Re/ 188Os indicates the preservation of primary Re-Os isotope systematics and time-integrated decay of the measured 187Re. Within the large uncertainties inherent in the nature of the samples and technique, sulphides in some granulites may record major tectonothermal events in the central Slave craton spanning several billion years of evolution. Multiple generations of sulphide can occur in a single sample. These data attest to the heterogeneous composition and complex history of the Slave craton lower crust.

  1. Recent development in deciphering the structure of luminescent silver nanodots

    NASA Astrophysics Data System (ADS)

    Choi, Sungmoon; Yu, Junhua

    2017-05-01

    Matrix-stabilized silver clusters and stable luminescent few-atom silver clusters, referred to as silver nanodots, show notable difference in their photophysical properties. We present recent research on deciphering the nature of silver clusters and nanodots and understanding the factors that lead to variations in luminescent mechanisms. Due to their relatively simple structure, the matrix-stabilized clusters have been well studied. However, the single-stranded DNA (ssDNA)-stabilized silver nanodots that show the most diverse emission wavelengths and the best photophysical properties remain mysterious species. It is clear that their photophysical properties highly depend on their protection scaffolds. Analyses from combinations of high-performance liquid chromatography, inductively coupled plasma-atomic emission spectroscopy, electrophoresis, and mass spectrometry indicate that about 10 to 20 silver atoms form emissive complexes with ssDNA. However, it is possible that not all of the silver atoms in the complex form effective emission centers. Investigation of the nanodot structure will help us understand why luminescent silver nanodots are stable in aqueous solution and how to further improve their chemical and photophysical properties.

  2. Improved nonlinear optical and optical limiting properties in non-covalent functionalized reduced graphene oxide/silver nanoparticle (NF-RGO/Ag-NPs) hybrid

    NASA Astrophysics Data System (ADS)

    Sakho, El hadji Mamour; Oluwafemi, Oluwatobi S.; Sreekanth, P.; Philip, Reji; Thomas, Sabu; Kalarikkal, Nandakumar

    2016-08-01

    Nonlinear optical (NLO) response under near infrared (800 nm) and visible (532 nm) laser excitations, of 100 fs (fs) and 5 ns (ns) pulse durations respectively, of reduced graphene oxide (RGO), non-covalent functionalized reduced graphene oxide (NF-RGO) and NF-RGO decorated with various concentration of silver nanoparticles (NF-RGO/Ag-NPs) have been investigated using the Open-aperture Z-Scan technique. For both femtosecond and nanosecond laser excitations, the studied graphene-based materials exhibit good nonlinear optical power limiting properties (OL), with NF-RGO/Ag-NPs sample prepared with 0.1 M AgNO3 showing the best nonlinear optical properties. For the ns regime, the optical limiting threshold decreased from 8.3 J/cm2 in NF-RGO to 4.3 J/cm2 in NF-RGO/Ag-NPs, while at fs regime, the nonlinear absorption coefficient (β) was found to increase with decrease in concentration of Ag-NPs in the hybrid. Two-photon absorption (2 PA) in combination with saturable absorption (SA) in femtosecond regime, and reverse saturable absorption (RSA) along with saturable absorption (SA) in the nanosecond regime, are responsible for the observed nonlinear optical absorption (NLA) behavior in these materials. These findings show that the as-synthesized NF-RGO/Ag-NPs hybrid is a relatively better material for nonlinear optical limiting applications.

  3. DNA/RNA chimera templates improve the emission intensity and target the accessibility of silver nanocluster-based sensors for human microRNA detection.

    PubMed

    Shah, Pratik; Choi, Suk Won; Kim, Ho-jin; Cho, Seok Keun; Thulstrup, Peter Waaben; Bjerrum, Morten Jannik; Bhang, Yong-Joo; Ahn, Jong Cheol; Yang, Seong Wook

    2015-05-21

    In recent years microRNAs (miRNAs) have been established as important biomarkers in a variety of diseases including cancer, diabetes, cardiovascular disease, aging, Alzheimer's disease, asthma, autoimmune disease and liver diseases. As a consequence, a variety of monitoring methods for miRNAs have been developed, including a fast and simple method for miRNA detection by exploitation of the unique photoluminescence of DNA-templated silver nanoclusters (DNA/AgNCs). To increase the versatility of the AgNC-based method, we have adopted DNA/RNA chimera templates for AgNC-based probes, allowing response from several human miRNAs which are hardly detectable with DNA-based probes. Here, we demonstrate in detail the power of DNA/RNA chimera/AgNC probes in detecting two human miRNAs, let-7a and miR-200c. The DNA/RNA chimera-based probes are highly efficient to determine the level of miRNAs in several human cell lines.

  4. 3D inversion of total magnetic intensity data for time-domain EM at the Lalor massive sulphide deposit

    NASA Astrophysics Data System (ADS)

    Yang, Dikun; Oldenburg, Douglas W.

    2017-01-01

    The Lalor deposit is a massive sulphide that is characterised as a stack of conductive ore lenses buried more than 600 m deep. We invert helicopter sub-audio magnetics (HeliSAM) data from Lalor collected using a ground large transmitter loop and an airborne total magnetic intensity (TMI) magnetometer measuring the time-domain electromagnetic (EM) responses. The TMI data are modelled as a projection of the anomalous field onto the earth's magnetic field. Inversion of these data is considered a significant case study because of two challenges. First, the early-time data are contaminated by the infrastructure on the surface. Second, inverting the data with a uniform half-space as the initial model results in a mathematically acceptable, but non-geologic, model. We create workflows to overcome these difficulties. For the contaminated data, we use a locally refined mesh and a constrained inversion to recover highly conductive cells near the surface that effectively represent the infrastructure. This allows us to safely extract geologic information from the early time data. The non-uniqueness in the inversion is reduced by warm-starting the voxel 3D inversion with a more reasonable initial guess, for example, a block model from geometric inversions. Those procedures greatly improve the inversion image from the surface to the bottom of the target at Lalor, and they can easily be incorporated into the industrial production workflows.

  5. Electrochemical reclamation of silver from silver-plating wastewater using static cylinder electrodes and a pulsed electric field.

    PubMed

    Su, Yuan-Bo; Li, Qing-Biao; Wang, Yuan-Peng; Wang, Hai-Tao; Huang, Jia-le; Yang, Xin

    2009-10-30

    Silver was reclaimed from silver-plating wastewater by using a pulsed electric field (PEF) combined with static cylinder electrodes (SCE). The conditions that produced the maximal silver recovery rate (RR(Ag)) (99%) were as follows: average retention time of 10 min, interelectrode gap of 50mm, solution pH of 9.0, temperature of 45 degrees C, initial Ag(I) concentration of 1000 mg L(-1), PEF pulse frequency of 1200 Hz, current density of 5.0 A m(-2) and a pulse duty cycle of 60%. Compared with the conventional direct current (DC) technology, the PEF process exhibited improvements in the silver recovery rate (RR(Ag)), total energy consumption (TEC) and physical properties of the silver deposits, especially for low Ag(I) concentrations, for example, from 500 to 1000 mg L(-1). For an initial Ag(I) concentration of 500 mg L(-1), the PEF process produced an RR(Ag) of up to 99%, and the TEC was 4.56 kWh (kg Ag)(-1). In comparison, the RR(Ag) and TEC were 90% and 5.66 kWh (kg Ag)(-1), respectively, in the DC process. The results of SEM observation and XRD analysis indicated that the silver deposits formed by the PEF process were smaller, denser, and of a higher purity than those produced by the DC process. Therefore, the presented method was effective for reclaiming silver from silver-plating wastewater.

  6. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  7. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  8. The Influence of Pre-oxidation on the Corrosion of Copper Nuclear Waste Canisters in Aqueous Anoxic Sulphide Solutions

    SciTech Connect

    Smith, J.M.; Qin, Z.; Wren, J.C.; Shoesmith, D.W.

    2007-07-01

    Scandinavian/Canadian high-level nuclear waste repository conditions are expected to evolve from initially warm and oxic to eventually cool and anoxic. During the warm, oxic period corrosion products will accumulate on the container surface. These deposits could impede the reaction of Cu with aqueous sulphide, the only reaction that could lead to the significant accumulation of additional corrosion damage under the long-term anoxic conditions. The kinetics of the reaction of Cu with aqueous sulphide solutions have been studied using electrochemical and surface analytical techniques. Corrosion potential measurements were used to follow the evolution of the surface as oxides/hydroxides were converted to sulphides in the sulphide concentration range 10{sup -5} to 10{sup -3} mol/L. Changes in composition were followed by in-situ Raman spectroscopy. Of critical importance is whether or not a period of pre-oxidation of a Cu container surface can prevent subsequent reaction of the surface with remotely produced sulphide. (authors)

  9. Thidiazuron-enhanced biosynthesis and antimicrobial efficacy of silver nanoparticles via improving phytochemical reducing potential in callus culture of Linum usitatissimum L.

    PubMed Central

    Anjum, Sumaira; Abbasi, Bilal Haider

    2016-01-01

    Green synthesis of silver nanoparticles (AgNPs) by using plants is an emerging class of nanobiotechnology. It revolutionizes all domains of medical sciences by synthesizing chemical-free AgNPs for various biomedical applications. In this report, AgNPs were successfully synthesized by using whole plant extract (WPE) and thidiazuron-induced callus extract (CE) of Linum usitatissimum. The phytochemical analysis revealed that the total phenolic and flavonoid contents were higher in CE than that in WPE. Ultraviolet-visible spectroscopy of synthesized AgNPs showed a characteristic surface plasmon band in the range of 410–426 nm. Bioreduction of CE-mediated AgNPs was completed in a shorter time than that of WPE-mediated AgNPs. Scanning electron microscopy showed that both types of synthesized AgNPs were spherical in shape, but CE-mediated AgNPs were smaller in size (19–24 nm) and more scattered in distribution than that of WPE-mediated AgNPs (49–54 nm). X-ray diffraction analysis confirmed crystalline nature (face-centered cubic) of both types of AgNPs. Fourier-transform infrared spectroscopy revealed that the polyphenols and flavonoids were mainly responsible for reduction and capping of synthesized AgNPs. Energy dispersive X-ray analysis further confirmed the successful synthesis of AgNPs. Moreover, the synthesized AgNPs were found to be stable over months with no change in the surface plasmon bands. More importantly, CE-mediated AgNPs displayed significantly higher bactericidal activity against multiple drug-resistant human pathogens than WPE-mediated AgNPs. The present work highlighted the potent role of thidiazuron in in vitro-derived cultures for enhanced biosynthesis of chemical-free AgNPs, which can be used as nanomedicines in many biomedical applications. PMID:26955271

  10. Preparation and SERS Study of Silver Microstructures with Dendritic Shape.

    PubMed

    Zhang, Xiao-tong; Zhao, Chun-liu; Zhou, Yu-meng; Dong, Qian-min; Lang, Ting-ting; Jin, Shang-zhong

    2015-10-01

    In the surface ehanced Raman scattering (SERS) technology, not only to improve the making process of SERS substrates, to be fast and easily, but also to enhance the SERS enhance factor, an easy replacement reaction between zinc and silver nitrate solution has been adopted to prepare silver micro-structures SERS-active substrate. The silver micro-substrates have many advantages. These substrates have good stability, well preservation, an easy making method and a fast making process. The surface profile of the silver microparticles is investigated by scanning electron microscope (SEM). The silver microstructures are dendritic shape in a symmetrical fashion with symmetrical distribution. When the time of the replace reaction is 40, 50 and 60 s, respectively, the average lengths of "trunks" in the silver dendritic microsubstractes are about 3, 5 and 10 μm, and the lengths of the "branches" are about 700 nm, 2 μm and 3 μm, respectively. The result shows that the longer time the replacement reaction takes, the longer lengths of the "trunks" and "branches" in the silver dendritic microsubstractes become. With the time of replace reaction increasing, the "trunk" and "branch" in the silver dendritic microsubstractes grow longer and a large amount of nano-level "leaves" grow out from the "branches" of the silver dendritic microsubstractes, so the silver micro size dendrates have nano level structure on surface. In order to investigate the SERS-active substrates application in SERS, a Fourier transform Raman spectrograph with a 1 064 nm laser wavelength is used to measure the SERS spectra. And good SERS spectra have been obtained by using dendritic silver microsubstrates on the silicon chip as a SERS substract, and Rhodamine 6G (R6G) as a molecule probe. It is found that the silver micro-substrates have good Raman characteristics. And comparing these SERS spectra, it gets the conclution that the spectra with best SERS enhance effect are obtained when R6G is obsorbed on the

  11. Markedly reduced toxicity of a hydrogen sulphide-releasing derivative of naproxen (ATB-346)

    PubMed Central

    Wallace, John L; Caliendo, Giuseppe; Santagada, Vincenzo; Cirino, Giuseppe

    2010-01-01

    Background and purpose: Hydrogen sulphide is an important mediator of gastric mucosal defence. The use of non-steroidal anti-inflammatory drugs continues to be limited by their toxicity, particularly in the upper gastrointestinal tract. We evaluated the gastrointestinal safety and anti-inflammatory efficacy of a novel hydrogen sulphide-releasing derivative of naproxen, ATB-346 [2-(6-methoxy-napthalen-2-yl)-propionic acid 4-thiocarbamoyl-phenyl ester]. Experimental approach: The ability of ATB-346 versus naproxen to cause gastric damage was evaluated in healthy rats and in rats with compromised gastric mucosal defence. Effects on the small intestine and on the healing of ulcers were also assessed. The ability of ATB-346 to inhibit cyclooxygenase-1 and 2 and to reduce inflammation in vivo was also evaluated. Key results: ATB-346 suppressed gastric prostaglandin E2 synthesis as effectively as naproxen, but produced negligible damage in the stomach and intestine. In situations in which the gastric mucosa was rendered significantly more susceptible to naproxen-induced damage (e.g. ablation of sensory afferent nerves, inhibition of endogenous nitric oxide or hydrogen sulphide synthesis, co-administration with aspirin, antagonism of KIR6.x channels), ATB-346 did not cause significant damage. Unlike naproxen and celecoxib, ATB-346 accelerated healing of pre-existing gastric ulcers. In a mouse airpouch model, ATB-346 suppressed cyclooxygenase-2 activity and inhibited leukocyte infiltration more effectively than naproxen. ATB-346 was as effective as naproxen in adjuvant-induced arthritis in rats, with a more rapid onset of activity. Unlike naproxen, ATB-346 did not elevate blood pressure in hypertensive rats. Conclusions and implications: ATB-346 exhibits anti-inflammatory properties similar to naproxen, but with substantially reduced gastrointestinal toxicity. PMID:20128814

  12. Temperature evolution of nickel sulphide phases from thiourea complex and their exchange bias effect

    SciTech Connect

    Kumar, Nitesh; Raman, N.; Sundaresan, A.

    2013-12-15

    Considering the very complex phase diagram of nickel sulphide, it is quite challenging to stabilize pure phases from a single precursor. Here, we obtain nanoparticles of various phases of nickel sulphide by decomposing nickel–thiourea complex at different temperatures. The first phase in the evolution is the one with the maximum sulphur content, namely, NiS{sub 2} nanoparticles obtained at 400 °C. As the temperature is increased, nanoparticles of phases with lesser sulphur content, NiS (600 °C) and Ni{sub 3}S{sub 2} (800 °C) are formed. NiS{sub 2} nanoparticles exhibit weak ferromagnetic transition at 30 K and show a large exchange bias at 2 K. NiS nanoparticles are antiferromagnetic and show relatively smaller exchange bias effect. On the other hand, Ni{sub 3}S{sub 2} nanoparticles exhibit very weak temperature dependent magnetization. Electrical measurements show that both NiS{sub 2} and NiS are semiconductors whereas Ni{sub 3}S{sub 2} is a metal. - Graphical abstract: Pure phases of NiS{sub 2}, NiS and Ni{sub 3}S{sub 2} have been obtained by thermal decomposition of nickel–thiourea complex wherein, NiS{sub 2} nanoparticles exhibit remarkable exchange bias effect at 2 K. - Highlights: • NiS{sub 2}, NiS and Ni{sub 3}S{sub 2} nanoparticles are obtained by thermal decomposition of nickel–thiourea complex at different temperatures. • As the temperature is increased, nickel sulphide phase with lesser sulphur content is obtained. • NiS{sub 2} nanoparticles show good exchange bias property which can be explained by antiferromagnetic core and ferromagnetic shell model. • NiS{sub 2} and NiS are semiconducting while Ni{sub 3}S{sub 2} shows metallic behavior.

  13. Printing Silver Nanogrids on Glass

    ERIC Educational Resources Information Center

    Sanders, Wesley C.; Valcarce, Ron; Iles, Peter; Smith, James S.; Glass, Gabe; Gomez, Jesus; Johnson, Glen; Johnston, Dan; Morham, Maclaine; Befus, Elliot; Oz, Aimee; Tomaraei, Mohammad

    2017-01-01

    This manuscript describes a laboratory experiment that provides students with an opportunity to create conductive silver nanogrids using polymeric templates. A microcontact-printed polyvinylpyrrolidone grid directs the citrate-induced reduction of silver ions for the fabrication of silver nanogrids on glass substrates. In addition to…

  14. Absorbent silver (I) antimicrobial fabrics

    USDA-ARS?s Scientific Manuscript database

    In recent years, silver in form of silver ions, has been gaining importance in the wound management as an effective broad-spectrum antimicrobial agent. Silver has a long history as an antimicrobial agent, especially in the treatment of wounds. Alginates and carboxymethyl (CM) cotton contain carboxyl...

  15. Fabrication, Conductive Properties and Photocatalytic Application of Silver Nanorods

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Hsun; Liu, Pai-Chung; Lin, C. B.

    2017-07-01

    This study proposes a process for fabricating silver nanorods used in conductive circuits and photocatalytic applications. In this process, UV-irradiated silver chloride nanoparticles are added to ethylene glycol solution containing polyvinyl pyrrolidone (PVP) and silver nitrate at 120 °C. With the seed crystal synthesis method, this process yielded a solution containing silver nanowires with an aspect ratio (AR) of approximately 1055 after 12 h. Aluminum foam was then placed in this solution, and the solution was stirred using a magnetic stirrer at 400 rpm. After 4 days, this process yielded a solution of silver nanorods with an AR of approximately 130. After completely washing away any PVP on the surface of the silver nanorods, a conductive ethanol ink containing 25 wt.% silver nanorods was prepared, and a conductive layer approximately 3 μm thick was applied on a glass slide. Measurements obtained using a four-point probe indicated that this layer had a sheet resistance of approximately 0.012 Ω/sq. Furthermore, a conductive ethanol ink containing 26 wt.% silver nanorods was used in a pen to draw conductive circuits on Bristol board and matte paper; the resulting sheet resistances were 132 and 0.018 Ω/sq, respectively. Finally, a visible-light-responsive photocatalyst consisting of silver nanorods dispersed over the Ag@AgCl film (Ag@AgCl/Ag nanorods; AR = 25) was synthesized through heterogeneous precipitation. The photocatalytic activity of the Ag@AgCl film can be further improved by the addition of silver nanorods.

  16. Characterization of recycled rubber media for hydrogen sulphide (H2S) control.

    PubMed

    Wang, Ning; Park, Jaeyoung; Evans, Eric A; Ellis, Timothy G

    2014-01-01

    Hydrogen sulphide (H2S) adsorption capacities on recycled rubber media, tyre-derived rubber particle (TDRP), and other rubber material (ORM) have been evaluated. As part of the research, densities, moisture contents, and surface properties of TDRP and ORM have been determined. The research team findings show that TDRP and ORM are more particulate in nature and not highly porous-like activated carbon. The characteristics of surface area, pore size, and moisture content support chemisorption on the macrosurface rather than physical adsorption in micropores. For example, moisture content is essential for H2S adsorption on ORM, and an increase in moisture content results in an increase in adsorption capacity.

  17. Evaporite encrustations and sulphide oxidation products from the southern Antarctic peninsula.

    USGS Publications Warehouse

    Vennum, W.R.

    1980-01-01

    White evaporite encrustations collected from 66 sites scattered over 30 000km2 of S.Antarctic Peninsula are dominantly gypsum and calcite, and subordinate aragonite and thenardite. Natrojarosite occurs as locally developed yellow surface stains on c30% of the white encrustations examined. Water, which forms by the melting of snow blown into cracks in highly fractured rocks by ground blizzards, dissolves soluble ions from minerals in these rocks as it percolates into them. The white encrustations appear to be deposited when this water later rises to the surface by capillary action and evaporates.-from Author Antarctica chemical weathering evaporites sulphide oxidation.

  18. Re-evaluation of literature values of silver optical constants.

    PubMed

    Jiang, Yajie; Pillai, Supriya; Green, Martin A

    2015-02-09

    Silver has unique optical properties for topical applications such as plasmonics. The two most widely used silver optical data sets are the Palik handbook compilation and that determined by Johnson and Christy. Unfortunately these are inconsistent making realistic modelling of the likely performance of silver in optical applications difficult, with modelling producing either highly optimistic or very pessimistic results, depending on application. By critical examination and duplication of the original experiments leading to the widely accepted literature values, we show that both data sets have drawbacks and conclude that there is a need for an improved data set for realistic simulation of experimentally obtainable properties.

  19. Ternary Silver Halide Nanocrystals.

    PubMed

    Abeyweera, Sasitha C; Rasamani, Kowsalya D; Sun, Yugang

    2017-07-18

    Nanocrystalline silver halides (AgX) such as AgCl, AgBr, and AgI, a class of semiconductor materials with characteristics of both direct and indirect band gaps, represent the most crucial components in traditional photographic processing. The nanocrystal surfaces provide sensitivity specks that can turn into metallic silver, forming an invisible latent image, upon exposure to light. The photographic processing implies that the AgX nanoparticles possess unique properties. First, pristine AgX nanoparticles absorb light only at low efficiency to convert surface AgX into tiny clusters of silver atoms. Second, AgX nanoparticles represent an excellent class of materials to capture electrons efficiently. Third, small metallic silver clusters can catalyze the reduction of AgX nanoparticles to Ag nanoparticles in the presence of mild reducing reagents, known as self-catalytic reduction. These properties indicate that AgX nanoparticles can be partially converted to metallic silver with high precision, leading to the formation of hybrid AgX/Ag nanoparticles. The nanosized metallic Ag usually exhibit intense absorption bands in the visible spectral region due to their strong surface plasmon resonances, which make the AgX/Ag nanoparticles a class of promising visible-light-driven photocatalysts for environmental remediation and CO2 reduction. Despite the less attention paid to their ability of capturing electrons, AgX nanoparticles might be a class of ideal electron shuttle materials to bridge light absorbers and catalysts on which electrons can drive chemical transformations. In this Account, we focus on ternary silver halide alloy (TSHA) nanoparticles, containing two types of halide ions, which increase the composition complexity of the silver halide nanoparticles. Interdiffusion of halide ions between two types of AgX at elevated temperatures has been developed for fabricating ternary silver halide alloy crystals, such as silver chlorobromide optical fibers for infrared

  20. Tunable optical properties of silver-dielectric-silver nanoshell

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2014-05-01

    Tunable optical properties of silver-dielectric-silver nanoshell including surface plasmon resonance (SPR) and resonance light scattering (RLS) based on quasi-static theory are investigated. When the silver core radius increases, the longer resonance wavelength red shifts and light scattering cross-section decreases whereas the shorter resonance wavelength blue shifts and the light scattering cross-section increases. The effect of middle dielectric thickness on the light scattering cross-section of nanoshell is different from those of the silver core radius changes. As middle dielectric radius increases, the longer resonance wavelength first blue shifts and then red shifts and the light scattering cross-section increases whereas the shorter resonance wavelength always red shifts and the light scattering cross-section decreases. The sensitivity of RLS to the refractive index of embedding medium is also reported. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness leads to increase the sensitivity of silver-dielectric-silver nanoshell. Tunable optical properties of silver-dielectric-silver nanoshell verify the biosensing potential of this nanostructure.

  1. Effect of Manganese Sulphide Size on the Precipitation of Tin Heterogeneous Nucleation in as-Cast Steel

    NASA Astrophysics Data System (ADS)

    Sun, Guilin; Song, Bo; Tao, Sufen; Cai, Zeyun

    2015-05-01

    Tramp elements in steels such as tin have been thought harmful because of the hot brittleness at grain boundaries and will be enriched in new steels because of difficulty of removal. It has been an important and difficult matter for metallurgist to use these elements. In the present paper, the as-cast steel containing high concentration of tin is prepared in laboratory and tin precipitates at the manganese sulphide inclusions have been found. A theoretical model is established to calculate the size of manganese sulphide inclusions acted as the heterogeneous nucleation site of tin precipitation. The results show that the inclusions with the smaller contact angle between tin precipitate is more advantageous to be the nucleus of tin heterogeneous nucleation. In this experiment, the manganese sulphide inclusions whose size is 2~4 μm in diameter can act as the nuclei of the nucleation of tin precipitation.

  2. Biological oxidation of sulphides by microorganisms present in the scum layer of UASB reactors treating domestic wastewater.

    PubMed

    Garcia, G P; Souza, C L; Glória, R M; Silva, S Q; Chernicharo, C A L

    2012-01-01

    This study aimed at the identification of microorganisms present in the scum layer of the settler compartment of upflow anaerobic sludge blanket (UASB) reactors, and to evaluate their role in the biological oxidation of sulphides. The experiments were conducted using scum samples taken from two pilot-scale UASB reactors, both treating domestic wastewater. Microorganisms similar to Beggiatoa sp., Thiotrix sp. and species of cyanobacteria were identified based on their morphology, and most of them have been shown to be capable of carrying out sulphur oxidation. Tests of biological oxidation of sulphides using scum and cultures of the cyanobacteria Phormidium and Pseudoanabaena showed a significant decrease in the concentrations of the sulphides, suggesting that the microorganisms present in the scum layer can play a role in the minimization of odour emissions.

  3. Adhesives, silver amalgam.

    PubMed

    1995-09-01

    The most recent advancement in silver amalgam is use of resin formulations to bond metal to tooth both chemically &/or physically, Since, historically, amalgam has been used successfully without adhesion to tooth, obvious clinical question is: Why is bonding now desirable? Two major clinical reasons to bond are: (1) Adhesive can increase fracture resistance of amalgam restored teeth & decrease cusp fractures; & (2) Seal provided by adhesive can greatly decrease, & often eliminate post-operative sensitivity. Following report summarizes CRA laboratory study of shear bond strength & sealing capability of 23 commercial adhesives used to bond 2 types of silver amalgam to tooth structure.

  4. The effects of silver dressings on chronic and burns wound healing.

    PubMed

    Elliott, Chris

    Silver (Ag) has been thought to improve wound healing and reduce instances of associated infections for many years. There are centuries-old records of silver being used in wound treatment, but the past two decades in particular have seen an increasing clinical application of silver-impregnated wound dressings and as such, have seen the number of research articles similarly increase. The majority of these articles focus on the positives and potential negatives (e.g. the toxicity of silver as a heavy metal) of using silver-impregnated dressings in the clinical management of wounds. This article examines the potential advantages and disadvantages of using silver in the management of chronic and burn wounds, and provides a physiological understanding of the body's response to silver absorption. The author also attempts to critically appraise the opposing literature related to the clinical relevance of microbial kill-time and the volume of silver contained in dressings, while investigating the efficacy of silver-impregnated dressings in the management of burns and chronic wounds. In order to collect literature relevant to this review, the author searched CINAHL, Medline, BMJ, Medscape, Journal of Advanced Nursing, the Electronic Medicines Compendium (EMC), and the Cochrane Library, using the terms silver, silver sulfadiazine, impregnated, wound, burn, dressing, review, quantative, efficacy, in vitro, in vivo, nanocrystalline, toxicity, infection, microbial kill-time, and comparison.

  5. Synthesis and characterization of dextran-capped silver nanoparticles with enhanced antibacterial activity.

    PubMed

    Yang, Guili; Lin, Qiuxia; Wang, Chunren; Li, Junjie; Wang, Jian; Zhou, Jin; Wang, Yan; Wang, Changyong

    2012-05-01

    Dextran-capped silver nanoparticles were synthesized by reducing silver nitrate with NaBH4 in the presence of dextran as capping agent. The characters of silver nanoparticles were investigated using UV-Vis spectrophotometer, nano-grainsize analyzer, X-ray diffraction, and transmission electron microscopy. Results showed that the silver nanoparticles capped with dextran were in uniform shape and narrow size distribution. Moreover, compared with polyvinylpyrrolidone (PVP)-capped silver nanoparticles, the dextran-capped ones possessed better stability. Antibacterial tests of these silver nanoparticles were carried out for Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Results suggested that the dextran-capped silver nanoparticles had high antibacterial activity against both Gram-positive and Gram-negative bacteria. In addition, the cytotoxicity in vitro of the dextran-capped silver nanoparticles was investigated using mouse fibrosarcoma cells (L929). The toxicity was evaluated by the changes of cell morphology and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Results indicated that these silver nanoparticles had slight effect on the survival and proliferation of L-929 cells at their minimal inhibitory concentration (MIC). After modified by dextran, the physiochemical properties of the silver nanoparticles had been improved. We anticipated that these dextran-capped silver nanoparticles could be integrated into systems for biological and pharmaceutical applications.

  6. Analytical applications of condensed phosphoric acid-IV Iodometric determination of sulphur in sulphate and sulphide ores and minerals and other compounds after reduction with sodium hypophosphite and tin metal in condensed phosphoric acid.

    PubMed

    Mizoguchi, T; Ishii, H

    1980-06-01

    Sulphate in sulphate ores, e.g., alunite, anglesite, barytes, chalcanthite, gypsum, manganese sulphate ore, is reduced to hydrogen sulphide by the hypophosphite-tin metal-CPA method, if a slight modification is made. Sulphide ores, e.g., galena, sphalerite, are quantitatively decomposed with CPA alone to give hydrogen sulphide. Suitable reducing agents must be used for the quantitative recovery of hydrogen sulphide from pyrite, nickel sulphide, cobalt sulphide and cadmium sulphide, or elemental sulphur is liberated. Iodide must be used in the decomposition of chalcopyrite; the copper sulphide is too stable to be decomposed by CPA alone. Molybdenite is not decomposed in CPA even if reducing agents are added. The pretreatment methods for the determination of sulphur in sulphur oxyacids and elemental sulphur have also been investigated.

  7. Silver nanoparticles reduce brain inflammation and related neurotoxicity through induction of H2S-synthesizing enzymes.

    PubMed

    Gonzalez-Carter, Daniel A; Leo, Bey Fen; Ruenraroengsak, Pakatip; Chen, Shu; Goode, Angela E; Theodorou, Ioannis G; Chung, Kian Fan; Carzaniga, Raffaella; Shaffer, Milo S P; Dexter, David T; Ryan, Mary P; Porter, Alexandra E

    2017-03-02

    Silver nanoparticles (AgNP) are known to penetrate into the brain and cause neuronal death. However, there is a paucity in studies examining the effect of AgNP on the resident immune cells of the brain, microglia. Given microglia are implicated in neurodegenerative disorders such as Parkinson's disease (PD), it is important to examine how AgNPs affect microglial inflammation to fully assess AgNP neurotoxicity. In addition, understanding AgNP processing by microglia will allow better prediction of their long term bioreactivity. In the present study, the in vitro uptake and intracellular transformation of citrate-capped AgNPs by microglia, as well as their effects on microglial inflammation and related neurotoxicity were examined. Analytical microscopy demonstrated internalization and dissolution of AgNPs within microglia and formation of non-reactive silver sulphide (Ag2S) on the surface of AgNPs. Furthermore, AgNP-treatment up-regulated microglial expression of the hydrogen sulphide (H2S)-synthesizing enzyme cystathionine-γ-lyase (CSE). In addition, AgNPs showed significant anti-inflammatory effects, reducing lipopolysaccharide (LPS)-stimulated ROS, nitric oxide and TNFα production, which translated into reduced microglial toxicity towards dopaminergic neurons. Hence, the present results indicate that intracellular Ag2S formation, resulting from CSE-mediated H2S production in microglia, sequesters Ag(+) ions released from AgNPs, significantly limiting their toxicity, concomitantly reducing microglial inflammation and related neurotoxicity.

  8. Silver nanoparticles reduce brain inflammation and related neurotoxicity through induction of H2S-synthesizing enzymes

    PubMed Central

    Gonzalez-Carter, Daniel A.; Leo, Bey Fen; Ruenraroengsak, Pakatip; Chen, Shu; Goode, Angela E.; Theodorou, Ioannis G.; Chung, Kian Fan; Carzaniga, Raffaella; Shaffer, Milo S. P.; Dexter, David T.; Ryan, Mary P.; Porter, Alexandra E.

    2017-01-01

    Silver nanoparticles (AgNP) are known to penetrate into the brain and cause neuronal death. However, there is a paucity in studies examining the effect of AgNP on the resident immune cells of the brain, microglia. Given microglia are implicated in neurodegenerative disorders such as Parkinson’s disease (PD), it is important to examine how AgNPs affect microglial inflammation to fully assess AgNP neurotoxicity. In addition, understanding AgNP processing by microglia will allow better prediction of their long term bioreactivity. In the present study, the in vitro uptake and intracellular transformation of citrate-capped AgNPs by microglia, as well as their effects on microglial inflammation and related neurotoxicity were examined. Analytical microscopy demonstrated internalization and dissolution of AgNPs within microglia and formation of non-reactive silver sulphide (Ag2S) on the surface of AgNPs. Furthermore, AgNP-treatment up-regulated microglial expression of the hydrogen sulphide (H2S)-synthesizing enzyme cystathionine-γ-lyase (CSE). In addition, AgNPs showed significant anti-inflammatory effects, reducing lipopolysaccharide (LPS)-stimulated ROS, nitric oxide and TNFα production, which translated into reduced microglial toxicity towards dopaminergic neurons. Hence, the present results indicate that intracellular Ag2S formation, resulting from CSE-mediated H2S production in microglia, sequesters Ag+ ions released from AgNPs, significantly limiting their toxicity, concomitantly reducing microglial inflammation and related neurotoxicity. PMID:28251989

  9. Silver nanoparticles reduce brain inflammation and related neurotoxicity through induction of H2S-synthesizing enzymes

    NASA Astrophysics Data System (ADS)

    Gonzalez-Carter, Daniel A.; Leo, Bey Fen; Ruenraroengsak, Pakatip; Chen, Shu; Goode, Angela E.; Theodorou, Ioannis G.; Chung, Kian Fan; Carzaniga, Raffaella; Shaffer, Milo S. P.; Dexter, David T.; Ryan, Mary P.; Porter, Alexandra E.

    2017-03-01

    Silver nanoparticles (AgNP) are known to penetrate into the brain and cause neuronal death. However, there is a paucity in studies examining the effect of AgNP on the resident immune cells of the brain, microglia. Given microglia are implicated in neurodegenerative disorders such as Parkinson’s disease (PD), it is important to examine how AgNPs affect microglial inflammation to fully assess AgNP neurotoxicity. In addition, understanding AgNP processing by microglia will allow better prediction of their long term bioreactivity. In the present study, the in vitro uptake and intracellular transformation of citrate-capped AgNPs by microglia, as well as their effects on microglial inflammation and related neurotoxicity were examined. Analytical microscopy demonstrated internalization and dissolution of AgNPs within microglia and formation of non-reactive silver sulphide (Ag2S) on the surface of AgNPs. Furthermore, AgNP-treatment up-regulated microglial expression of the hydrogen sulphide (H2S)-synthesizing enzyme cystathionine-γ-lyase (CSE). In addition, AgNPs showed significant anti-inflammatory effects, reducing lipopolysaccharide (LPS)-stimulated ROS, nitric oxide and TNFα production, which translated into reduced microglial toxicity towards dopaminergic neurons. Hence, the present results indicate that intracellular Ag2S formation, resulting from CSE-mediated H2S production in microglia, sequesters Ag+ ions released from AgNPs, significantly limiting their toxicity, concomitantly reducing microglial inflammation and related neurotoxicity.

  10. Multiple sulphur and lead sources recorded in hydrothermal exhalites associated with the Lemarchant volcanogenic massive sulphide deposit, central Newfoundland, Canada

    NASA Astrophysics Data System (ADS)

    Lode, Stefanie; Piercey, Stephen J.; Layne, Graham D.; Piercey, Glenn; Cloutier, Jonathan

    2017-01-01

    Metalliferous sedimentary rocks (mudstones, exhalites) associated with the Cambrian precious metal-bearing Lemarchant Zn-Pb-Cu-Au-Ag-Ba volcanogenic massive sulphide (VMS) deposit, Tally Pond volcanic belt, precipitated both before and after VMS mineralization. Sulphur and Pb isotopic studies of sulphides within the Lemarchant exhalites provide insight into the sources of S and Pb in the exhalites as a function of paragenesis and evolution of the deposit and subsequent post-depositional modification. In situ S isotope microanalyses of polymetallic sulphides (euhedral and framboidal pyrite, anhedral chalcopyrite, pyrrhotite, galena and euhedral arsenopyrite) by secondary ion mass spectrometry (SIMS) yielded δ34S values ranging from -38.8 to +14.4 ‰, with an average of ˜ -12.8 ‰. The δ34S systematics indicate sulphur was predominantly biogenically derived via microbial/biogenic sulphate reduction of seawater sulphate, microbial sulphide oxidation and microbial disproportionation of intermediate S compounds. These biogenic processes are coupled and occur within layers of microbial mats consisting of different bacterial/archaeal species, i.e., sulphate reducers, sulphide oxidizers and those that disproportionate sulphur compounds. Inorganic processes or sources (i.e., thermochemical sulphate reduction of seawater sulphate, leached or direct igneous sulphur) also contributed to the S budget in the hydrothermal exhalites and are more pronounced in exhalites that are immediately associated with massive sulphides. Galena Pb isotopic compositions by SIMS microanalysis suggest derivation of Pb from underlying crustal basement (felsic volcanic rocks of Sandy Brook Group), whereas less radiogenic Pb derived from juvenile sources leached from mafic volcanic rocks of the Sandy Brook Group and/or Tally Pond group. This requires that the hydrothermal fluids interacted with juvenile and evolved crust during hydrothermal circulation, which is consistent with the existing

  11. Effect of precursor concentration and bath temperature on the growth of chemical bath deposited tin sulphide thin films

    NASA Astrophysics Data System (ADS)

    Jayasree, Y.; Chalapathi, U.; Uday Bhaskar, P.; Sundara Raja, V.

    2012-01-01

    SnS is a promising candidate for a low-cost, non-toxic solar cell absorber layer. Tin sulphide thin films have been deposited by chemical bath deposition technique from a solution containing stannous chloride, thioacetamide, ammonia and triethanolamine (TEA). The effects of concentration of tin salt, triethanolamine and bath temperature on the growth of tin sulphide films have been investigated in order to optimize the growth conditions to obtain tin monosulphide (SnS) films. SnS films obtained under optimized conditions were found to be polycrystalline in nature with orthorhombic structure. The optical band gap of these films was found to be 1.5 eV.

  12. Towards colloidal spintronics through Rashba spin-orbit interaction in lead sulphide nanosheets

    NASA Astrophysics Data System (ADS)

    Ramin Moayed, Mohammad Mehdi; Bielewicz, Thomas; Zöllner, Martin Sebastian; Herrmann, Carmen; Klinke, Christian

    2017-06-01

    Employing the spin degree of freedom of charge carriers offers the possibility to extend the functionality of conventional electronic devices, while colloidal chemistry can be used to synthesize inexpensive and tunable nanomaterials. Here, in order to benefit from both concepts, we investigate Rashba spin-orbit interaction in colloidal lead sulphide nanosheets by electrical measurements on the circular photo-galvanic effect. Lead sulphide nanosheets possess rock salt crystal structure, which is centrosymmetric. The symmetry can be broken by quantum confinement, asymmetric vertical interfaces and a gate electric field leading to Rashba-type band splitting in momentum space at the M points, which results in an unconventional selection mechanism for the excitation of the carriers. The effect, which is supported by simulations of the band structure using density functional theory, can be tuned by the gate electric field and by the thickness of the sheets. Spin-related electrical transport phenomena in colloidal materials open a promising pathway towards future inexpensive spintronic devices.

  13. Controllable Phase Transformation in Extracting Valuable Metals from Chinese Low-Grade Nickel Sulphide Ore

    NASA Astrophysics Data System (ADS)

    Cui, Fuhui; Mu, Wenning; Wang, Shuai; Xu, Qian; Zhai, Yuchun; Luo, Shaohua

    2017-10-01

    In this work, a two-stage sulphuric acid roasting and water leaching system was chosen to extract valuable metals from Chinese low-grade nickel sulphide ore. By optimizing the two-stage roasting process, first roasting temperature at 295°C with particle size of 80-91 μm with an acid-ore ratio of 1.1:1 for 2 h, and second roasting temperature at 620°C for 2 h, it was found that more than 98% of the nickel and 99% of the copper but less than 14.38% of Fe were leached into the water. Attempts were made via x-ray diffraction analysis, scanning electron microscopy, chemical phase analysis, and differential thermal and thermogravimetric analysis to reveal the phase transformations for Ni, Cu, and Mg, which could be expressed as mineral phases → sulphates hydrate → sulphates and for iron as mineral phases → hydrated ferrous sulphate → ferric sulphates and ferric oxide → oxide. The results of this work suggest that a controllable phase transformation by using a two-stage sulphuric acid roasting process is a feasible method for efficiently extracting valuable metals from Chinese nickel sulphide ore.

  14. Analysis of SnO2|WO3 Heterocontact Properties during the Detection of Hydrogen Sulphide

    PubMed Central

    Suchorska-Woźniak, Patrycja; Rac, Olga; Fiedot, Marta; Teterycz, Helena

    2014-01-01

    The main objective of the paper was the analysis of the properties of SnO2|WO3 heterocontact as well as the determination of its response to 50 ppm of hydrogen sulphide. It was noticed that the sensitivity of the sensor being tested to hydrogen sulphide depended significantly on the polarization direction. When its parameters were compared with those of sensors the gas-sensitive layer of which was made only from one type of metal oxide, a high impact of the heterocontact on the electric charge transport was noticed. The value of the activation energy of the electric conductivity is clearly dependent on the polarization direction. A mechanism of physicochemical processes occurring in a planar sensor with a heterocontact was suggested, and three areas differing in the width of depleted layer, where the inter-phase boundary of SnO2|WO3 had the most essential impact on the parameters of the sensor being tested, were distinguished and described. PMID:25360578

  15. Half-cell potentials of semiconductive simple binary sulphides in aqueous solution

    USGS Publications Warehouse

    Sato, M.

    1966-01-01

    Theoretical consideration of the charge-transfer mechanism operative in cells with an electrode of a semiconductive binary compound leads to the conclusion that the half-cell potential of such a compound is not only a function of ionic activities in the electrolytic solution, but also a function of the activities of the component elements in the compound phase. The most general form of the electrode equation derived for such a compound with a formula MiXj which dissociates into Mj+ and Xi- ions in aqueous solution is. EMiXj = EMiXj0 + R T 2 ij ln [ (sua Mj+)aqi ?? (suaX)jMiXj/ (suaXi-)aqj ?? (suaM)iMiXj],. where. EMiXj0 = 1 2(EM,Mj+0 + EXi-,X). The equation can be modified to other forms. When applied to semiconductive simple binary sulphides, these equations appear to give better descriptions of the observed electrode potentials of such sulphides than any other proposed equations. ?? 1966.

  16. Gold/Copper Sulphide core/shell nanoparticles for Photothermal Therapy

    NASA Astrophysics Data System (ADS)

    Bala Lakshmanan, Santana; Zou, Xiaoju; Chen, Wei

    2011-10-01

    One of the biggest successes in photothermal therapy (PTT) is the use of gold (Au) nanoparticles. But its disadvantage is that it is too expensive and in addition the NIR absorption in gold nanostructures is from surface plasmon resonance which is dependent on the dielectric constant of the surrounding matrix. Thus the plasmon absorption maxima would shift for in-vivo observations compared to in-vitro. Alternatively, Copper sulphide (CuS) nanoparticles, developed recently, have also been used for PTT. Their advantage over gold nanostructures is that they have NIR absorption around 1100 nm which originates from the d-d transition of Cu2+ ions unlike surface plasmon resonance in gold nanostructures. Therefore, in this paper, we combined the above two nanoparticle systems and developed a new type of agent -Gold/Copper Sulphide (Au/CuS) core/shell nanostructure that has better photothermal conversion efficiency and also overcomes the limitations of the existing nanoparticle systems for PTT. The TEM results confirmed the core/shell structure of Au/CuS nanostructures. From UV-Vis-NIR spectrometer we obtained that these core/shell nanostructures have maximum absorbance at 1100 nm and absorption intensity much higher than only Au and only CuS nanoparticles systems. This, in turn attributed to the relatively high photothermal conversion efficiency of Au/CuS nanostructures.

  17. Endosymbiotic sulphate-reducing and sulphide-oxidizing bacteria in an oligochaete worm.

    PubMed

    Dubilier, N; Mülders, C; Ferdelman, T; de Beer, D; Pernthaler, A; Klein, M; Wagner, M; Erséus, C; Thiermann, F; Krieger, J; Giere, O; Amann, R

    2001-05-17

    Stable associations of more than one species of symbiont within a single host cell or tissue are assumed to be rare in metazoans because competition for space and resources between symbionts can be detrimental to the host. In animals with multiple endosymbionts, such as mussels from deep-sea hydrothermal vents and reef-building corals, the costs of competition between the symbionts are outweighed by the ecological and physiological flexibility gained by the hosts. A further option for the coexistence of multiple symbionts within a host is if these benefit directly from one another, but such symbioses have not been previously described. Here we show that in the gutless marine oligochaete Olavius algarvensis, endosymbiotic sulphate-reducing bacteria produce sulphide that can serve as an energy source for sulphide-oxidizing symbionts of the host. Thus, these symbionts do not compete for resources but rather share a mutalistic relationship with each other in an endosymbiotic sulphur cycle, in addition to their symbiotic relationship with the oligochaete host.

  18. Sulphate production by Paracoccus pantotrophus ATCC 35512 from different sulphur substrates: sodium thiosulphate, sulphite and sulphide.

    PubMed

    Meyer, Daniel Derrossi; Andrino, Felipe Gabriel; Possedente de Lira, Simone; Fornaro, Adalgiza; Corção, Gertrudes; Brandelli, Adriano

    2016-01-01

    One of the problems in waste water treatment plants (WWTPs) is the increase in emissions of hydrogen sulphide (H2S), which can cause damage to the health of human populations and ecosystems. To control emissions of this gas, sulphur-oxidizing bacteria can be used to convert H2S to sulphate. In this work, sulphate detection was performed by spectrophotometry, ion chromatography and atomic absorption spectrometry, using Paracoccus pantotrophus ATCC 35512 as a reference strain growing in an inorganic broth supplemented with sodium thiosulphate (Na2S2O3·5H2O), sodium sulphide (Na2S) or sodium sulphite (Na2SO3), separately. The strain was metabolically competent in sulphate production. However, it was only possible to observe significant differences in sulphate production compared to abiotic control when the inorganic medium was supplemented with sodium thiosulphate. The three methods for sulphate detection showed similar patterns, although the chromatographic method was the most sensitive for this study. This strain can be used as a reference for sulphate production in studies with sulphur-oxidizing bacteria originating from environmental samples of WWTPs.

  19. Hydrogen sulphide poisoning of shallow seas following the end-Triassic extinction

    NASA Astrophysics Data System (ADS)

    Richoz, Sylvain; van de Schootbrugge, Bas; Pross, Jörg; Püttmann, Wilhelm; Quan, Tracy M.; Lindström, Sofie; Heunisch, Carmen; Fiebig, Jens; Maquil, Robert; Schouten, Stefan; Hauzenberger, Christoph A.; Wignall, Paul B.

    2012-09-01

    The evolution of complex life over the past 600 million years was disrupted by at least five mass extinctions, one of which occurred at the close of the Triassic period. The end-Triassic extinction corresponds to a period of high atmospheric-CO2 concentrations caused by massive volcanism and biomass burning; most extinction scenarios invoke the resulting environmental perturbations in accounting for the loss of marine and terrestrial biodiversity. Here we reconstruct changes in Tethyan shallow marine ecosystems and ocean redox chemistry from earliest Jurassic (Hettangian)-aged black shales from Germany and Luxemburg. The shales contain increased concentrations of the biomarker isorenieratane, a fossilized pigment from green sulphur bacteria. The abundance of green sulphur bacteria suggests that the photic zone underwent prolonged periods of high concentrations of hydrogen sulphide. This interval is also marked by the proliferation of green algae, an indicator of anoxia. We conclude that the redox changes in the entire water column reflect sluggish circulation in marginal regions of the Tethys Ocean. We suggest that the resultant repeated poisoning of shallow epicontinental seas--hotspots of Mesozoic biodiversity--with hydrogen sulphide may have slowed the recovery of marine ecosystems during the Early Jurassic.

  20. Temperature dependent rate coefficients for the reactions of Criegee biradicals with selected alcohols and sulphides

    NASA Astrophysics Data System (ADS)

    McGillen, Max; McMahon, Laura; Curchod, Basile; Shallcross, Dudley; Orr-Ewing, Andrew

    2017-04-01

    The reactions of Criegee biradicals have received much attention in recent years, yet few reactive systems have undergone direct experimental measurement, and fewer still have been measured as a function of temperature. In this study, absolute temperature-dependent rate coefficients for the gas-phase reactions of a suite of alcohols and sulphides with both formaldehyde oxide (CH2OO) and acetone oxide ((CH3)2COO) are determined experimentally between 254 and 328 K using cavity ringdown spectroscopy for detecting Criegee biradicals. Major differences in reactivity and temperature dependence are observed both in terms of the functionality (between alcohols and sulphides) and also the degree of alkyl substitution about the Criegee biradical. This diverse behaviour represents a uniquely challenging problem for atmospheric chemistry since the atmosphere contains a large variety of both functionalized compounds and Criegee biradicals, leading to a formidable parameter space which may be impossible to cover experimentally. Notwithstanding, new experimental data such as these are vital for understanding the general behaviour of Criegee biradicals in the atmosphere.

  1. The role of hydrogen sulphide in the control of breathing in hypoxic zebrafish (Danio rerio)

    PubMed Central

    Porteus, Cosima S; Abdallah, Sara J; Pollack, Jacob; Kumai, Yusuke; Kwong, Raymond W M; Yew, Hong M; Milsom, William K; Perry, Steve F

    2014-01-01

    The current study investigated the role of hydrogen sulphide (H2S) in oxygen sensing, intracellular signalling and promotion of ventilatory responses to hypoxia in adult and larval zebrafish (Danio rerio). Both larval and adult zebrafish exhibited a dose-dependent increase in ventilation to sodium sulphide (Na2S), an H2S donor. In vertebrates, cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) are enzymes that catalyse the endogenous production of H2S. In adult zebrafish, inhibition of both CBS and CSE with aminooxyacetate (AOA) and propargyl glycine (PPG) blunted or abolished the hypoxic hyperventilation, and the addition of Na2S to the water partially rescued the effects of inhibiting endogenous H2S production. In zebrafish larvae (4 days post-fertilization), gene knockdown of either CBS or CSE using morpholinos attenuated the hypoxic ventilatory response. Furthermore, the intracellular calcium concentration of isolated neuroepithelial cells (NECs), which are putative oxygen chemoreceptors, increased significantly when these cells were exposed to 50 μm Na2S, supporting a role for H2S in Ca2+-evoked neurotransmitter release in these cells. Finally, immunohistochemical labelling showed that NECs dissociated from adult gill contained CBS and CSE, whereas cutaneous NECs in larval zebrafish expressed only CSE. Taken together, these data show that H2S can be produced in the putative oxygen-sensing cells of zebrafish, the NECs, in which it appears to play a pivotal role in promoting the hypoxic ventilatory response. PMID:24756639

  2. Heavy metal leaching from hydroxide, sulphide and silicate stabilized/solidified wastes

    SciTech Connect

    Cheeseman, C.R.; Butcher, E.J.; Sollars, C.J.; Perry, R. . Centre for Environmental Control and Waste Management)

    1993-01-01

    A synthetic, mixed-metal solution has been stabilized by treatment with sodium hydroxide, sodium sulphide, and sodium silicate, respectively. The three stabilized filter cakes have subsequently been solidified using additions of ordinary Portland cement and pulverized fuel ash (PFA) which are typically used in UK solidification operations. Both the stabilized filter cakes and the solidified wastes have been subjected to an equilibrium extraction test, a modified TCLP test, and a series of single-extraction, batch leach tests using an increasingly acidic leachant. Metal release was found to be primarily dependent on the pH of the leachate. Under mildly acidic conditions, the percentages leached from the stabilized and the stabilized/solidified wastes were comparable for most metals. A high-volume fraction of these solidified wastes is occupied by the stabilized filter cake. When they are broken up and tested in single-extraction leach tests, the primary effect of the cementitious additives is to increase the pH of the leachate so that most heavy metals remain insoluble. When tested under acidic leachate conditions, copper, lead, and mercury were found to be particularly well retained within sodium sulphide stabilized wastes. Under similar tests conditions, cadmium was leached at very low levels from the sodium silicate stabilized waste.

  3. Controllable Phase Transformation in Extracting Valuable Metals from Chinese Low-Grade Nickel Sulphide Ore

    NASA Astrophysics Data System (ADS)

    Cui, Fuhui; Mu, Wenning; Wang, Shuai; Xu, Qian; Zhai, Yuchun; Luo, Shaohua

    2017-06-01

    In this work, a two-stage sulphuric acid roasting and water leaching system was chosen to extract valuable metals from Chinese low-grade nickel sulphide ore. By optimizing the two-stage roasting process, first roasting temperature at 295°C with particle size of 80-91 μm with an acid-ore ratio of 1.1:1 for 2 h, and second roasting temperature at 620°C for 2 h, it was found that more than 98% of the nickel and 99% of the copper but less than 14.38% of Fe were leached into the water. Attempts were made via x-ray diffraction analysis, scanning electron microscopy, chemical phase analysis, and differential thermal and thermogravimetric analysis to reveal the phase transformations for Ni, Cu, and Mg, which could be expressed as mineral phases → sulphates hydrate → sulphates and for iron as mineral phases → hydrated ferrous sulphate → ferric sulphates and ferric oxide → oxide. The results of this work suggest that a controllable phase transformation by using a two-stage sulphuric acid roasting process is a feasible method for efficiently extracting valuable metals from Chinese nickel sulphide ore.

  4. Hydrogen sulphide release to surface waters at the Precambrian/Cambrian boundary.

    PubMed

    Wille, Martin; Nägler, Thomas F; Lehmann, Bernd; Schröder, Stefan; Kramers, Jan D

    2008-06-05

    Animal-like multicellular fossils appeared towards the end of the Precambrian, followed by a rapid increase in the abundance and diversity of fossils during the Early Cambrian period, an event also known as the 'Cambrian explosion'. Changes in the environmental conditions at the Precambrian/Cambrian transition (about 542 Myr ago) have been suggested as a possible explanation for this event, but are still a matter of debate. Here we report molybdenum isotope signatures of black shales from two stratigraphically correlated sample sets with a depositional age of around 542 Myr. We find a transient molybdenum isotope signal immediately after the Precambrian/Cambrian transition. Using a box model of the oceanic molybdenum cycle, we find that intense upwelling of hydrogen sulphide-rich deep ocean water best explains the observed Early Cambrian molybdenum isotope signal. Our findings suggest that the Early Cambrian animal radiation may have been triggered by a major change in ocean circulation, terminating a long period during which the Proterozoic ocean was stratified, with sulphidic deep water.

  5. Temperature evolution of nickel sulphide phases from thiourea complex and their exchange bias effect

    NASA Astrophysics Data System (ADS)

    Kumar, Nitesh; Raman, N.; Sundaresan, A.

    2013-12-01

    Considering the very complex phase diagram of nickel sulphide, it is quite challenging to stabilize pure phases from a single precursor. Here, we obtain nanoparticles of various phases of nickel sulphide by decomposing nickel-thiourea complex at different temperatures. The first phase in the evolution is the one with the maximum sulphur content, namely, NiS2 nanoparticles obtained at 400 °C. As the temperature is increased, nanoparticles of phases with lesser sulphur content, NiS (600 °C) and Ni3S2 (800 °C) are formed. NiS2 nanoparticles exhibit weak ferromagnetic transition at 30 K and show a large exchange bias at 2 K. NiS nanoparticles are antiferromagnetic and show relatively smaller exchange bias effect. On the other hand, Ni3S2 nanoparticles exhibit very weak temperature dependent magnetization. Electrical measurements show that both NiS2 and NiS are semiconductors whereas Ni3S2 is a metal.

  6. Preparation of silver tips for scanning tunneling microscopy imaging

    NASA Astrophysics Data System (ADS)

    Iwami, M.; Uehara, Y.; Ushioda, S.

    1998-11-01

    A simple reliable preparation method of silver tips for scanning tunneling microscopy imaging with atomic resolution is presented. The procedure is based on two-step electrochemical processing; ac electropolishing and subsequent dc electroetching. The quality of the tip is improved by applying high bias voltage pulses while the tip is within tunneling range. This indicates that the end of the tips are sharpened by field evaporation of silver ions.

  7. Re-Os dating of sulphide inclusions zonally distributed in single Yakutian diamonds: Evidence for multiple episodes of Proterozoic formation and protracted timescales of diamond growth

    NASA Astrophysics Data System (ADS)

    Wiggers de Vries, D. F.; Pearson, D. G.; Bulanova, G. P.; Smelov, A. P.; Pavlushin, A. D.; Davies, G. R.

    2013-11-01

    The timing of diamond formation in the Siberian lithospheric mantle was investigated by Re-Os isotope dating of sulphide inclusions from eclogitic and lherzolitic diamonds from the Mir, 23rd Party Congress and Udachnaya kimberlite pipes in Yakutia. The diamonds contained multiple sulphide inclusions distributed over their core-to-rim zones. Cathodoluminescence, carbon isotope and nitrogen aggregation studies demonstrate that the diamonds are zoned and that the distinct zones are associated with different diamond growth episodes. There are coherent relationships between carbon isotope composition, nitrogen concentration and aggregation state of the diamond hosts, and major and trace element compositions, Re-Os compositions and initial Os isotope ratios of the included sulphides. This suggests that the different diamond and sulphide populations formed at different times from fluids/melts with different chemical compositions. Based on the Re-Os isochron ages and the nitrogen aggregation states we conclude that the sulphides are co-genetic with their diamond hosts.

  8. Silver nanoparticle protein corona and toxicity: a mini-review.

    PubMed

    Durán, Nelson; Silveira, Camila P; Durán, Marcela; Martinez, Diego Stéfani T

    2015-09-04

    Silver nanoparticles are one of the most important materials in the nanotechnology industry. Additionally, the protein corona is emerging as a key entity at the nanobiointerface; thus, a comprehensive understanding of the interactions between proteins and silver nanoparticles is imperative. Therefore, literature reporting studies involving both single molecule protein coronas (i.e., bovine and human serum albumin, tubulin, ubiquitin and hyaluronic-binding protein) and complex protein coronas (i.e., fetal bovine serum and yeast extract proteins) were selected to demonstrate the effects of protein coronas on silver nanoparticle cytotoxicity and antimicrobial activity. There is evidence that distinct and differential protein components may yield a "protein corona signature" that is related to the size and/or surface curvature of the silver nanoparticles. Therefore, the formation of silver nanoparticle protein coronas together with the biological response to these coronas (i.e., oxidative stress, inflammation and cytotoxicity) as well as other cellular biophysicochemical mechanisms (i.e., endocytosis, biotransformation and biodistribution) will be important for nanomedicine and nanotoxicology. Researchers may benefit from the information contained herein to improve biotechnological applications of silver nanoparticles and to address related safety concerns. In summary, the main aim of this mini-review is to highlight the relationship between the formation of silver nanoparticle protein coronas and toxicity.

  9. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    NASA Astrophysics Data System (ADS)

    Kvitek, L.; Panacek, A.; Prucek, R.; Soukupova, J.; Vanickova, M.; Kolar, M.; Zboril, R.

    2011-07-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  10. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are…

  11. Potassium silver cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for potassium silver cyanide is inclu

  12. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are…

  13. Polyurethane biocompatible silver bionanocomposites for biomedical applications

    NASA Astrophysics Data System (ADS)

    Filip, D.; Macocinschi, D.; Paslaru, E.; Munteanu, B. S.; Dumitriu, R. P.; Lungu, M.; Vasile, C.

    2014-11-01

    Bionanocomposite membranes based on polyurethane (PU), extracellular matrix (EM), and silver nanoparticles (AgNPs) were prepared by applying both solvent casting method and electrospinning/electrospraying method. PU-EM-Ag compositions were electrospun/electrosprayed onto PU membrane to realize improved biocompatible biomaterials. Surface morphological characteristics and wettability properties were investigated by SEM and AFM techniques and water contact angle measurements. Water contact angle depends on surface chemistry and the two methods employed for preparation of biomembranes as well as roughness of the membrane surfaces. Rheological study brings information on electrospinability of the polymer solutions/dispersions. Silver nanoparticles greatly influence the electrospinability of the polymer dispersions because of the increase in dynamic viscosity with the increasing silver content. Native PU and PU incorporated with low contents of AgNPs less than 0.3 % show high cell proliferation and good biocompatibility. The electrospun PU-EM-Ag nanobiocomposite membranes bring the advantage of using of low amounts of bioactive and biocidal components. The obtained silver nanobiocomposite membranes possess good bioactivity and non-cytotoxicity necessary for biomedical device applications. The obtained nanobiocomposite membranes are expected to find application for medical devices such as urinary catheters, wound dressings, etc.

  14. Photochemical Synthesis of Silver Nanodecahedrons and Related Nanostructures for Plasmonic Field Enhancement Applications

    NASA Astrophysics Data System (ADS)

    Lu, Haifei

    excitation. These silver NDs acting as seeds can be re-grown into larger silver NDs with LSPR ranging from 490 nm to 590 nm, upon receiving LED irradiation with emission close to the LSPR of silver ND seeds, which are suspended in a precursor solution containing small silver nanoparticles. With the aid of centrifugation, silver NDs with high purity can be obtained. Furthermore, silver ND with a broad tuning range (LSPR 490 ~ 660 nm) can be synthesized from these seeds using irradiation from a 500 nm LED. Second, the optical properties of silver NDs and their SERS application for sensitive molecular detection are presented. Raman signal obtained from silver NDs show remarkable advantage over noble nanoparticles of other shaped, thus revealing their strong localized field enhancement. Experimental results demonstrate that average enhancement factor from individual silver ND may be as high as 106. In order to explore their application for biosensing and bioimaging, stable silica coated SERS tags based on silver ND producing high Raman intensity have been studied. Our experiment results indicate that 10-8 M 4-MBA in solution can be detected by silver NDs modified silicon chip through SERS. Simulation result on the geometry of silver ND/silica spacer/gold film/substrate shows that the Raman sensitivity of the NDs modified chip can be further improved with the insertion of a dielectric/conductor film between them. Finally, we present a photochemical method for the preparation of silver nanostructures preparation with the use of 633 nm laser. Silver nanostructures composed of silver nanoplates could be grown from small silver nanoparticles deposited on a glass substrate. The periodicity of the silver nanostructures is several micrometers, revealing that this photochemical method has the potential for "writing" silver pattern on a solid substrate. Raman spectroscopy has also been explored for real-time monitoring of silver nanostructure growth and SERS hotspots formation.

  15. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  16. [Advances in the research of antibacterial function of silver nanoparticle and its application in burn treatment].

    PubMed

    Liu, M Z; Liu, M X; Wang, X L; Guo, G H

    2017-02-20

    Silver has received much attention for its great anti-infection effect in wound. With the development of nanotechnology, the advantages of silver nanoparticles have gradually arisen in scientific practice and clinical application due to their large specific surface area etc. In this article, we conclude the antibacterial mechanisms of silver nanoparticles, the factors influencing their antibacterial effects, the methods of improving their performance and safety, and their application in burn treatment.

  17. Performance evaluation of oxygen, air and nitrate for the microaerobic removal of hydrogen sulphide in biogas from sludge digestion.

    PubMed

    Díaz, I; Lopes, A C; Pérez, S I; Fdz-Polanco, M

    2010-10-01

    The removal performance of hydrogen sulphide in severely polluted biogas produced during the anaerobic digestion of sludge was studied by employing pure oxygen, air and nitrate as oxidant reactives supplied to the biodigester. Research was performed in a 200-L digester with an hydraulic retention time (HRT) of ∼20 days under mesophilic conditions. The oxygen supply (0.25 N m³/m³ feed) to the bioreactor successfully reduced the hydrogen sulphide content from 15,811 mg/N m³ to less than 400 mg/N m³. The introduction of air (1.27 N m³/m³ feed) removed more than 99% of the hydrogen sulphide content, with a final concentration of ∼55 mg/N m³. COD removal, VS reduction and methane yield were not affected under microaerobic conditions; however, methane concentration in the biogas decreased when air was employed as a result of nitrogen dilution. The nitrate addition was not effective for hydrogen sulphide removal in the biogas.

  18. Geothermal power plants at Mt. Amiata (Tuscany-Italy): mercury and hydrogen sulphide deposition revealed by vegetation.

    PubMed

    Bacci, E; Gaggi, C; Lanzillotti, E; Ferrozzi, S; Valli, L

    2000-04-01

    At Mt. Amiata (Italy) geothermal energy is used, since 1969, to generate electricity in five plants with a nominal capacity of 88 MW. Anomalous levels of mercury characterise geothermal fluids of Mt. Amiata, an area renowned for its vast cinnabar deposits and for the mercury production carried out in the past. Mercury emission rates range from 300 to 400 g/h, or 3-4 g/h per MW electrical installed capacity. These emissions are coupled with a release of 7-8 kg/(h MW) of hydrogen sulphide (H2S). Mercury is discharged as Hg0 gaseous species and reaches the atmosphere with the non-condensable gas fraction. In this fraction, CO, is the major component (94-98%), H2S is around 1% and mercury concentration is as high as 1-10 mg/Nm3. Leaves of a spontaneous grass (Avena sterilis), at the end of the vegetative cycle, were used as mercury bioconcentrators to map deposition near geothermal power plants and to calculate the corresponding average levels of Hg0 in the air. Direct measurements of mercury and hydrogen sulphide vapours in the air reached by power plant emissions showed a ratio of about 1-2000. This ratio was applied to calculate average levels of hydrogen sulphide starting from mercury deposition mapping: typical concentrations of mercury and hydrogen sulphide were of the order of 10-20 ng/m3 and 20-40 microg/m3, respectively.

  19. Geochemical, metagenomic and metaproteomic insights into trace metal utilization by methane-oxidizing microbial consortia in sulphidic marine sediments.

    PubMed

    Glass, Jennifer B; Yu, Hang; Steele, Joshua A; Dawson, Katherine S; Sun, Shulei; Chourey, Karuna; Pan, Chongle; Hettich, Robert L; Orphan, Victoria J

    2014-06-01

    Microbes have obligate requirements for trace metals in metalloenzymes that catalyse important biogeochemical reactions. In anoxic methane- and sulphide-rich environments, microbes may have unique adaptations for metal acquisition and utilization because of decreased bioavailability as a result of metal sulphide precipitation. However, micronutrient cycling is largely unexplored in cold (≤ 10°C) and sulphidic (> 1 mM ΣH(2)S) deep-sea methane seep ecosystems. We investigated trace metal geochemistry and microbial metal utilization in methane seeps offshore Oregon and California, USA, and report dissolved concentrations of nickel (0.5-270 nM), cobalt (0.5-6 nM), molybdenum (10-5600 nM) and tungsten (0.3-8 nM) in Hydrate Ridge sediment porewaters. Despite low levels of cobalt and tungsten, metagenomic and metaproteomic data suggest that microbial consortia catalysing anaerobic oxidation of methane (AOM) utilize both scarce micronutrients in addition to nickel and molybdenum. Genetic machinery for cobalt-containing vitamin B12 biosynthesis was present in both anaerobic methanotrophic archaea (ANME) and sulphate-reducing bacteria. Proteins affiliated with the tungsten-containing form of formylmethanofuran dehydrogenase were expressed in ANME from two seep ecosystems, the first evidence for expression of a tungstoenzyme in psychrophilic microorganisms. Overall, our data suggest that AOM consortia use specialized biochemical strategies to overcome the challenges of metal availability in sulphidic environments. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  20. Selenium determination in biscuits and pasta: development of chronopotentiometric stripping determination by using a sulphide as an internal standard.

    PubMed

    Svarc-Gajić, Jaroslava; Stojanović, Zorica

    2013-10-15

    Being common in chromatographic techniques internal standard method is rarely applied in electrochemical stripping determinations. One of the reasons for such rare use of this elegant quantification method is because optimal conditions of accumulation at the electrode for individual compounds producing a reproducible signal may vary significantly. These criteria are much stricter when selenium is in question due to very complex mechanism of its accumulation at mercury electrodes which implies simultaneous cathodic mercury dissolution and chemical reaction. Elements that are in the analytical step stripped cathodically from mercury electrodes are rare, further limiting the application of the internal standard method when electrochemical selenium determination is in question. In this work the possibility of using sulphide for selenium quantification by chronopotentiometric stripping analysis was investigated. Optimal experimental parameters were defined in two-component systems. Dimensionless factors defining the ratio of proportionality constants of the two elements were calculated for different selenium concentration ranges at different sulphide contents. Sulphide content that was chosen as adequate for selenium concentrations reasonably to be expected in food samples was 500 µg/dm(3). Determined detection limit of chronopotentiometric stripping determination of selenium by using a sulphide as an internal standard was 0.04 µg/dm(3) (RSD=7.6%; n=5). Defined quantification method was confirmed by analysing spiked standard solutions and standard reference material. The method was used for selenium determination in biscuit and pasta samples. Calculated contents were statistically compared with those obtained by using graphite furnace atomic absorption spectrometry.

  1. Effect of desliming of sulphide-rich mill tailings on the long-term strength of cemented paste backfill.

    PubMed

    Ercikdi, Bayram; Baki, Hakan; İzki, Muhammet

    2013-01-30

    This paper presents the effect of desliming on the short- and long-term strength, stability and rheological properties of cemented paste backfill (CPB) produced from two different mill tailings. A 28-day unconfined compressive strength (UCS) of ≥1.0 MPa and the maintenance of stability over 224 days of curing were selected as the design criteria for the evaluation of paste backfill performance. Desliming induced some changes in the physical, chemical, mineralogical and rheological properties of the tailings. CPB mixture of the deslimed tailings achieved the required consistency at a lower water to cement ratio. The short-term UCSs of CPB samples of the deslimed tailings were found to be 30-100% higher than those samples of the reference tailings at all the binder dosages and curing times. CPB samples of the deslimed tailings achieved the long-term stability at relatively low binder dosages (e.g. 5 wt% c.f. ≥6.1% for the reference tailings). It was also estimated that desliming could allow a 13.4-23.1% reduction in the binder consumption depending apparently on the inherent characteristics of the tailings. Over the curing period, generation of sulphate and acid by the oxidation of pyrite present in the tailings was also monitored to correlate with the strength losses observed in the long term. Scanning electron microscope (SEM) and Mercury Intrusion Porosimetry (MIP) analyses provided an insight into the microstructure of CPB and the formation of secondary mineral phases (i.e. gypsum) confirming the beneficial effect of desliming. These findings suggest that desliming can be suitably exploited for CPB of sulphide-rich mill tailings to improve the strength and stability particularly in the long term and to reduce binder consumption.

  2. Facts About Invasive Bighead and Silver Carps

    USGS Publications Warehouse

    Chapman, Duane C.

    2010-01-01

    The U.S. Geological Survey (USGS) scientists at the Columbia Environmental Research Center (CERC), Columbia, Missouri, carry out basic and applied research on the ecology of invasive fishes in the Missouri and Mississippi river basins. Emphasis is placed on improving understanding of the life cycles of bighead and silver carp to provide information needed to manage these aggressively invasive species. USGS scientists collaborate with Federal and State management agencies and universities, nationally and internationally, to fill critical science information gaps.

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

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P.

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

  4. Silver ion release from antimicrobial polyamide/silver composites.

    PubMed

    Kumar, Radhesh; Münstedt, Helmut

    2005-05-01

    Silver ion (Ag(+)) the versatile antimicrobial species was released in a steady and prolonged manner from a silver-filled polyamide composite system. Metallic silver powder having varying specific surface area (SSA) has been used as a resource of biocide in polyamide. Strong evidences are found showing the release of the antimicrobial species from the resulting composite upon soaking it in water due to the interaction of the diffused water molecules with the dispersed silver powder within the matrix. The Ag(+) release was observed as increasing with time and concentration of the silver powder and is found to be influenced by the SSA of the silver powder, changes in the physical state of the composite specimen as a result of the water diffusion and the composite morphology. It is observed that the Ag(+) release increases initially which is followed by a marginal increase between day 4 and 6. Composites containing higher amounts of silver (4 and 8 wt%) exhibit a further rise in Ag(+) release from the sixth day of storage in water. Composite containing silver particles with the lowest specific surface area (0.78 m(2)/g) showed highest Ag(+) release. SEM shows a finer dispersion of the silver powder (4 wt%) having lowest SSA. However particles with higher (1.16 and 2.5 m(2)/g) SSA possess an agglomerated morphology leading to lower Ag(+) release. The composites are found to release Ag(+) at a concentration level capable of rendering an antimicrobial efficacy.

  5. Nucleic acid nanomaterials: Silver-wired DNA

    NASA Astrophysics Data System (ADS)

    Auffinger, Pascal; Ennifar, Eric

    2017-10-01

    DNA double helical structures are supramolecular assemblies that are typically held together by classical Watson-Crick pairing. Now, nucleotide chelation of silver ions supports an extended silver-DNA hybrid duplex featuring an uninterrupted silver array.

  6. Ultralight Conductive Silver Nanowire Aerogels.

    PubMed

    Qian, Fang; Lan, Pui Ching; Freyman, Megan C; Chen, Wen; Kou, Tianyi; Olson, Tammy Y; Zhu, Cheng; Worsley, Marcus A; Duoss, Eric B; Spadaccini, Christopher M; Baumann, Ted; Han, T Yong-Jin

    2017-09-13

    Low-density metal foams have many potential applications in electronics, energy storage, catalytic supports, fuel cells, sensors, and medical devices. Here, we report a new method for fabricating ultralight, conductive silver aerogel monoliths with predictable densities using silver nanowires. Silver nanowire building blocks were prepared by polyol synthesis and purified by selective precipitation. Silver aerogels were produced by freeze-casting nanowire aqueous suspensions followed by thermal sintering to weld the nanowire junctions. As-prepared silver aerogels have unique anisotropic microporous structures, with density precisely controlled by the nanowire concentration, down to 4.8 mg/cm(3) and an electrical conductivity up to 51 000 S/m. Mechanical studies show that silver nanowire aerogels exhibit "elastic stiffening" behavior with a Young's modulus up to 16 800 Pa.

  7. Ultralight Conductive Silver Nanowire Aerogels

    DOE PAGES

    Qian, Fang; Lan, Pui Ching; Freyman, Megan C.; ...

    2017-09-05

    Low-density metal foams have many potential applications in electronics, energy storage, catalytic supports, fuel cells, sensors, and medical devices. Here in this work, we report a new method for fabricating ultralight, conductive silver aerogel monoliths with predictable densities using silver nanowires. Silver nanowire building blocks were prepared by polyol synthesis and purified by selective precipitation. Silver aerogels were produced by freeze-casting nanowire aqueous suspensions followed by thermal sintering to weld the nanowire junctions. As-prepared silver aerogels have unique anisotropic microporous structures, with density precisely controlled by the nanowire concentration, down to 4.8 mg/cm3 and an electrical conductivity up to 51more » 000 S/m. Lastly, mechanical studies show that silver nanowire aerogels exhibit “elastic stiffening” behavior with a Young’s modulus up to 16 800 Pa.« less

  8. Silver enhancement of nanogold and undecagold

    SciTech Connect

    Hainfield, J.F.; Furuya, F.R.

    1995-07-01

    A recent advance in immunogold technology has been the use of molecular gold instead of colloidal gold. A number of advantages are realized by this approach, such as stable covalent, site-specific attachment, small probe size and absence of aggregates for improved penetration. Silver enhancement has led to improved and unique results for electron and light microscopy, as well as their use with blots and gels. Most previous work with immunogold silver staining has been done with colloidal gold particles. More recently, large gold compounds (``clusters``) having a definite number of gold atoms and defined organic shell, have been used, frequently with improved results. These gold dusters, large compared to simple compounds, are, however, at the small end of the colloidal gold scale in size; undecagold is 0.8 nm and Nanogold is 1.4 nm. They may be used in practically all applications where colloidal gold is used (Light and electron microscopy, dot blots, etc.) and in some unique applications, where at least the larger colloidal golds don`t work, such as running gold labeled proteins on gels (which are later detected by silver enhancement). The main differences between gold clusters and colloidal golds are the small size of the dusters and their covalent attachment to antibodies or other molecules.

  9. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  10. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  11. Chalcophile and siderophile elements in sulphide inclusions in eclogitic diamonds and metal cycling in a Paleoproterozoic subduction zone

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Stachel, Thomas; Seitz, Hans-Michael; Brey, Gerhard P.

    2012-09-01

    In the central Slave craton, eclogitic diamonds are suggested to have formed during Paleoproterozoic subduction in a meta-gabbroic substrate representing former lower oceanic crust that interacted with serpentinite-derived fluids at high fluid-rock ratios. In order to assess the behaviour of chalcophile and siderophile elements (CSE) during this process, we measured trace-element concentrations of sulphide inclusions in diamonds from the Diavik mine by laser ablation ICPMS. The nitrogen systematics of the diamonds (average N concentration of ˜600 ppm and aggregation state 4% N as B-aggregates) indicate average mantle residence temperatures of ˜1050 °C for a 1.85 Ga formation age, corresponding ˜170 km depth. Based on the available evidence from natural samples and experiments, we suggest that the highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pd, Pt, Re) except Au behaved largely conservatively during fluid-induced metamorphism, which may point to a reducing and Cl-poor nature of the fluid. The abundances of the moderately siderophile and chalcophile elements Cr, Co, Ni, Cu, Ag, Sn, Mo and W may also have changed little, whereas As, Sb, Tl, Pb and Bi may have been mobilised from the subducting lower oceanic crust. The partitioning of CSE in eclogite and geochemical behaviour during oceanic crust formation was assessed for inferred conservative elements. Assuming an average sulphide mode of 0.3 wt.% for the oceanic crust, its abundances of HSE, Cu, Mo, Se and Te can mostly be accounted for by sulphide minerals alone. Lithophile behaviour of W, Cd, In and Sn and enrichment in residual melts may explain their lower abundances in the gabbroic eclogitic sulphide inclusions compared to MORB sulphide. These elements, as well as Cr, Co, Ni, Zn and Ga require additional host phases both in eclogite, where rutile partitions significant amounts of Cr, Zn, W, Ga and Sn, and in the oceanic crust.

  12. In vivo measurements of the internal pH of Hediste (Nereis) diversicolor (Annelida, Polychaeta) exposed to ambient sulphidic conditions using pH microelectrodes

    NASA Astrophysics Data System (ADS)

    Sommer, Stefan; Jahn, Andreas; Funke, Friederike; Brenke, Nils

    The effect of different ambient sulphide concentrations on the internal pH regime of Hediste (Nereis) diversicolor was studied under in vivo conditions using liquid membrane pH microelectrodes, a method which is new to marine sciences. As a case study, the hypothesis was tested whether organisms exposed to ambient sulphidic conditions are able to lower their internal pH which, in effect, would reduce sulphide influx into the animals and thus could represent an effective detoxification mechanism. It was shown that a significant lowering of the internal pH occurred within only 20min after adding sulphide. This pH lowering appeared to be dependent on the external sulphide concentration of the ambient medium and showed a saturation beyond a threshold level of about 130μM. It is discussed whether this sulphide-induced pH drop is an active regulatory mechanism and acts as an effective protection mechanism against sulphide during short-term exposures.

  13. Photoluminescence studies of chemically bath deposited nanocrystalline lead sulphide (PbS) thin films

    NASA Astrophysics Data System (ADS)

    Singh, L. Rajen; Singh, S. Bobby; London, R. K.; Sharma, H. B.; Rahman, A.

    2012-07-01

    Nanocrystalline lead sulphide (PbS) films have been deposited on glass substrates by chemical bath deposition (CBD) method. Lead acetate [Pb(CH3COOH)2] and thiourea [(NH2)2CS] were used as starting materials for deposition of PbS thin films. The as-deposited thin films were found to be crystalline having cubic phase structure with the strongest diffraction intensity along (200) plane. The grain sizes calculated from XRD spectra were found to decrease from 17 to 15 nm with the decrease in molar concentration of the precursor solutions. The structural, optical and photoluminescence properties of the PbS nanocrystalline thin film with different molar concentration were studied.

  14. Preparation and characterization of zinc sulphide nanocomposites based on acrylonitrile butadiene rubber

    NASA Astrophysics Data System (ADS)

    Ramesan, M. T.; Nihmath, A.; Francis, Joseph

    2013-06-01

    Rubber composite based on acrylonitrile butadiene rubber (NBR) reinforced with nano zinc sulphide (ZnS) have been prepared via vulcanization process and characterized by several techniques. Processing characteristics such as scorch time, optimum cure time decreases with increase in concentration of nano filler in acrylonitrile butadiene rubber. Mechanical properties such as tensile and tear strength increases with increase in concentration of nano filler up to 7 phr of loading thereafter the value decreases, whereas hardness, and flame resistance increases with the dosage of fillers. These enhanced properties are due to the homogenous dispersion of nano fillers in NBR matrix, which is evidenced from the structure that evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  15. Evidence for a functional vasodilatatory role for hydrogen sulphide in the human cutaneous microvasculature

    PubMed Central

    Kutz, Jessica L; Greaney, Jody L; Santhanam, Lakshmi; Alexander, Lacy M

    2015-01-01

    Abstract The present study aimed to identify the presence of cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulphurtransferase (3-MST), which endogenously produce hydrogen sulphide (H2S), and to functionally examine the mechanisms of H2S-induced vasodilatation in the human cutaneous microcirculation. CSE and 3-MST were quantified in forearm skin samples from 5 healthy adults (24 ± 3 years) using western blot analysis. For functional studies, microdialysis fibres were placed in the forearm skin of 12 healthy adults (25 ± 3 years) for graded infusions (0.01–100 mm) of sodium sulphide (Na2S) and sodium hydrogen sulphide (NaHS). To define the mechanisms mediating H2S-induced vasodilatation, microdialysis fibres were perfused with Ringer solution (control), a ATP-sensitive potassium channel (KATP) inhibitor, an intermediate calcium-dependent potassium channel (KCa) inhibitor, a non-specific KCa channel inhibitor or triple blockade. To determine the interaction of H2S-mediated vasodilatation with nitric oxide (NO) and cyclo-oxygenase (COX) signalling pathways, microdialysis fibres were perfused with Ringer solution (control), a non-specific NO synthase inhibitor, a non-selective COX inhibitor or combined inhibition during perfusion of increasing doses of Na2S. CSE and 3-MST were expressed in all skin samples. Na2S and NaHS elicited dose-dependent vasodilatation. Non-specific KCa channel inhibition and triple blockade blunted Na2S-induced vasodilatation (P < 0.05), whereas KATP and intermediate KCa channel inhibition had no effect (P > 0.05). Separate and combined inhibition of NO and COX attenuated H2S-induced vasodilatation (all P < 0.05). CSE and 3-MST are expressed in the human microvasculature. Exogenous H2S elicits cutaneous vasodilatation mediated by KCa channels and has a functional interaction with both NO and COX vasodilatatory signalling pathways. Key points Hydrogen sulphide (H2S) is vasoprotective, attenuates inflammation and modulates

  16. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide

    PubMed Central

    Nagarkar, Sanjog S.; Saha, Tanmoy; Desai, Aamod V.; Talukdar, Pinaki; Ghosh, Sujit K.

    2014-01-01

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions. PMID:25394493

  17. Algae mediated synthesis of cadmium sulphide nanoparticles and their application in bioremediation

    NASA Astrophysics Data System (ADS)

    Prasad Mandal, Ranju; Sekh, Sanoyaz; Sarkar, Neera Sen; Chattopadhyay, Dipankar; De, Swati

    2016-05-01

    The present work is a study on the biological synthesis of cadmium sulphide (CdS) nanoparticles using blue-green algae that is popularly used as a food supplement. This synthesis is unique in the sense that no external sulphur precursor is required, the CdS nanoparticles are synthesized in situ in the algal medium. The CdS nanoparticles thus synthesized are photoluminescent and can act as highly efficient photocatalysts for degradation of the dye pollutant malachite green. Thus the CdS nanoparticles synthesized in situ in the algae conform to the desired criteria of waste water treatment i.e. biosorption of the pollutant and its subsequent degradation. The novelty of this work also lies in its potential for use in bioremediation by conversion of the toxic Cd(II) ion to less toxic CdS nanoparticles within the algal framework.

  18. Experimental Oxidation of Iron Sulphides from Intertidal Surface Sediments: Stable Isotope Effects (S, O, C)

    NASA Astrophysics Data System (ADS)

    Ebersbach, F.; Böttcher, M. E.; Al-Raei, A. M.; Segl, M.

    2009-04-01

    Top intertidal sediments show a pronounced zone of activities of sulphate-reducing bacteria. Iron sulfides may be formed, but a substantial part is reoxidized to sulfate. Microbial or chemical reoxidation can be further enhanced by a resuspension of surface sediments by tidal currents or storms. The rates of the different processes depend on the site-secific sedimentological properties (e.g., grain size, iron and sulphur contents etc.). In the present study 3 different areas of the German Wadden Sea were studied: a mud flat in the Jade Bay, and sandy sediments in the intertidals of Spiekeroog and Sylt islands. The latter site is part of an in-situ lugworm-exclusion experiment. The goal was the experimental and field investigation of the fate of iron sulfides and the formation of sulphate upon resuspension of intertidal surface sediments in oxygenated seawater. All sites were geochemically analyzed for dissolved and solid phase iron, manganese, sulphur and carbon phases/species, and sulphate reduction rates were measured using radiotracers. Dissolved chloride and grain sizes analysis where additionally carried out. TOC, S and metal phase contents were higher in mud compared to sandy sediments. Field results demonstrate gross but only minor net sulphide production and a downcore increases in FeS contents, due to intense sulphide oxidation at the surface. Pyrite, on the other hand, was abundant through the sediments due to continuous sediment reworking. The fate of iron-sulphides and accumulation of sulphate as a function of time was followed in batch experiments using dark suspensions of surface sediments in site-bottom waters at room temperature. During the experiments, each sample was shaken continuously under exposition to oxygen, and sub-samples were taken at the beginning and after discrete time intervalls. A very fast oxidation rate of AVS led to a complete exhaustion within a day, whereas Cr(II)-reducible sulfur was inititially built up and then decreased

  19. Noble metal nanoclusters and nanoparticles precede mineral formation in magmatic sulphide melts

    PubMed Central

    Helmy, Hassan M.; Ballhaus, Chris; Fonseca, Raúl O.C.; Wirth, Richard; Nagel, Thorsten; Tredoux, Marian

    2013-01-01

    In low temperature aqueous solutions, it has long been recognized by in situ experiments that many minerals are preceded by crystalline nanometre-sized particles and non-crystalline nanophases. For magmatic systems, nanometre-sized precursors have not yet been demonstrated to exist, although the suggestion has been around for some time. Here we demonstrate by high temperature quench experiments that platinum and arsenic self-organize to nanoparticles, well before the melt has reached a Pt–As concentration at which discrete Pt arsenide minerals become stable phases. If all highly siderophile elements associate to nanophases in undersaturated melts, the distribution of the noble metals between silicate, sulphide and metal melts will be controlled by the surface properties of nano-associations, more so than by the chemical properties of the elements. PMID:24008992

  20. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide.

    PubMed

    Nagarkar, Sanjog S; Saha, Tanmoy; Desai, Aamod V; Talukdar, Pinaki; Ghosh, Sujit K

    2014-11-14

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions.

  1. ESR dating of barite in sulphide deposits formed by the sea-floor hydrothermal activities.

    PubMed

    Toyoda, Shin; Fujiwara, Taisei; Uchida, Ai; Ishibashi, Jun-ichiro; Nakai, Shun'ichi; Takamasa, Asako

    2014-06-01

    Barite is a mineral newly found to be practically useful for electron spin resonance (ESR) dating of sulphide deposits formed by the sea-floor hydrothermal activities. The recent studies for the properties of the ESR dating signal in barite are summarised in the present paper as well as the formulas for corrections for accurate dose-rate estimation are developed including the dose-rate conversion factors, shape correction for gamma-ray dose and decay of (226)Ra. Although development of the techniques for ESR dating of barite has been completed, further comparative studies with other dating techniques such as U-Th and (226)Ra-(210)Pb dating are necessary for the technique to be widely used.

  2. Bacterial consortium for copper extraction from sulphide ore consisting mainly of chalcopyrite

    PubMed Central

    Romo, E.; Weinacker, D.F.; Zepeda, A.B.; Figueroa, C.A.; Chavez-Crooker, P.; Farias, J.G.

    2013-01-01

    The mining industry is looking forward for bacterial consortia for economic extraction of copper from low-grade ores. The main objective was to determine an optimal bacterial consortium from several bacterial strains to obtain copper from the leach of chalcopyrite. The major native bacterial species involved in the bioleaching of sulphide ore (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Leptospirillum ferriphilum) were isolated and the assays were performed with individual bacteria and in combination with At. thiooxidans. In conclusion, it was found that the consortium integrated by At. ferrooxidans and At. thiooxidans removed 70% of copper in 35 days from the selected ore, showing significant differences with the other consortia, which removed only 35% of copper in 35 days. To validate the assays was done an escalation in columns, where the bacterial consortium achieved a higher percentage of copper extraction regarding to control. PMID:24294251

  3. Influence of sulphide precursor on crystal phase of ternary I-III-VI2 semiconductors

    NASA Astrophysics Data System (ADS)

    Beloš, Milica V.; Abazović, Nadica D.; Jakovljević, Jadranka Kuljanin; Janković, Ivana; Ahrenkiel, Scott P.; Mitrić, Miodrag; Čomor, Mirjana I.

    2013-12-01

    Samples of AgInS2 and CuInS2 nanoparticles were synthesized by hot-injection method at 270 °C using 1-dodecanethiol (DT) and elemental sulphur (S) as sulphide precursors, and oleylamine as reaction medium and surfactant. Composition, crystal structure, and particle size of obtained materials were tracked by XRD and TEM/HRTEM measurements. It was shown that, due to its dual role as sulphur source and surfactant, DT drastically slows formation of desired material. Samples obtained with DT even after 4 h of reaction have traces of intermediary compound (β-In2S3), whereas in samples synthesized with elemental S these traces are less pronounced. The growth mechanism and influence of each reaction step are discussed in detail.

  4. Interaction between serum albumins and sonochemically synthesized cadmium sulphide nanoparticles: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Naveenraj, Selvaraj; Asiri, Abdullah M.; Anandan, Sambandam

    2013-05-01

    Cadmium Sulphide nanoparticles approximately 5-10 nm in size range were synthesized by sonochemical technique, which follows acoustic cavitation phenomenon and generates nanoparticles with a smaller size range and higher surface area. The in vitro binding interaction of these sonochemically synthesized CdS nanoparticles with serum albumins (SA) were investigated using UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques since CdS nanoparticles has biological applications such as cellular labelling and deep-tissue imaging. UV-Vis absorption and fluorescence studies confirm that CdS nanoparticles bind with SA through ground state complex formation (static quenching mechanism). The results suggest that sonochemically synthesized CdS nanoparticles interact with HSA more than that of BSA and these nanoparticles can be easily transported and rapidly released to the targets by serum albumins. CD studies confirmed the conformational change of serum albumins on the interaction of CdS nanoparticles.

  5. Bacterial consortium for copper extraction from sulphide ore consisting mainly of chalcopyrite.

    PubMed

    Romo, E; Weinacker, D F; Zepeda, A B; Figueroa, C A; Chavez-Crooker, P; Farias, J G

    2013-01-01

    The mining industry is looking forward for bacterial consortia for economic extraction of copper from low-grade ores. The main objective was to determine an optimal bacterial consortium from several bacterial strains to obtain copper from the leach of chalcopyrite. The major native bacterial species involved in the bioleaching of sulphide ore (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Leptospirillum ferriphilum) were isolated and the assays were performed with individual bacteria and in combination with At. thiooxidans. In conclusion, it was found that the consortium integrated by At. ferrooxidans and At. thiooxidans removed 70% of copper in 35 days from the selected ore, showing significant differences with the other consortia, which removed only 35% of copper in 35 days. To validate the assays was done an escalation in columns, where the bacterial consortium achieved a higher percentage of copper extraction regarding to control.

  6. E-chondrites - Significance of the partition of elements between 'silicate' and 'sulphide'

    NASA Astrophysics Data System (ADS)

    Easton, A. J.

    1985-03-01

    Bulk chemical analyses of six E-type chondrites are given. The chondrites include Daniel's kuil, Khairpur, Kota Kota, and Sain Sauveur, together with South Oman, and St. Mark's chondrites. The distribution of lithophile elements between silicate and sulfide mineral groups was measured using selective attack by dry chlorine on magnetically separated fractions. Subdivision of the E-chondrites into types I and II is shown using chemical data for the St. Mark's and Saint Sauveur chondrites. It is found that the Sulphides contributed the largest proportion of elements to the bulk composition; the proportion of Ti contributed to the bulk composition by the sulfides in both chondrite types increased in relation to the intensity of the thermal metamorphic effect. A complete list of the chemical abundances in the chondrites is provided.

  7. Synthesis of zinc sulphide nanoparticles and its photodegradation ability towards organic pollutants

    NASA Astrophysics Data System (ADS)

    Giribabu, K.; Suresh, R.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2014-01-01

    Zinc sulphide (ZnS) nanoparticles were synthesized by thermal decomposition of zinc n-propyl dithiocarbonate (Xanthate). ZnS nanoparticles were characterized by XRD and FE-SEM. XRD peaks match well with the standard ZnS reflections (JCPDS No. 36-1450). It revealed that the synthesized ZnS has a hexagonal structure. The lattice constants are found to be a = 3.08 and c = 6.20 were nanostructures. From FE-SEM image plate like and agglomerated particles was observed. However particles are uniformly distributed in the image. The photodegradation ability of the ZnS nanoparticles was investigated using methylene blue as the model compound.

  8. Metal-organic framework based highly selective fluorescence turn-on probe for hydrogen sulphide

    NASA Astrophysics Data System (ADS)

    Nagarkar, Sanjog S.; Saha, Tanmoy; Desai, Aamod V.; Talukdar, Pinaki; Ghosh, Sujit K.

    2014-11-01

    Hydrogen sulphide (H2S) is known to play a vital role in human physiology and pathology which stimulated interest in understanding complex behaviour of H2S. Discerning the pathways of H2S production and its mode of action is still a challenge owing to its volatile and reactive nature. Herein we report azide functionalized metal-organic framework (MOF) as a selective turn-on fluorescent probe for H2S detection. The MOF shows highly selective and fast response towards H2S even in presence of other relevant biomolecules. Low cytotoxicity and H2S detection in live cells, demonstrate the potential of MOF towards monitoring H2S chemistry in biological system. To the best of our knowledge this is the first example of MOF that exhibit fast and highly selective fluorescence turn-on response towards H2S under physiological conditions.

  9. Long-term effects on the olfactory system of exposure to hydrogen sulphide

    PubMed Central

    Hirsch, A. R.; Zavala, G.

    1999-01-01

    OBJECTIVE: To study chronic effects of hydrogen sulphide (H2S) on cranial nerve I (nervi olfactorii), which have been only minimally described. METHODS: Chemosensations (smell and taste) were evaluated in eight men who complained of continuing dysfunction 2-3 years after the start of occupational exposure to H2S. Various bilateral (both nostrils) and unilateral (one nostril at a time) odour threshold tests with standard odorants as well as the Chicago smell test, a three odour detection and identification test and the University of Pennsylvania smell identification test, a series of 40 scratch and sniff odour identification tests were administered. RESULTS: Six of the eight patients showed deficits of various degrees. Two had normal scores on objective tests, but thought that they continued to have problems. H2S apparently can cause continuing, sometimes unrecognised olfactory deficits. CONCLUSION: Further exploration into the extent of such problems among workers exposed to H2S is warranted.   PMID:10450248

  10. Experimental and theoretical insights into the oxodiperoxomolybdenum-catalysed sulphide oxidation using hydrogen peroxide in ionic liquids.

    PubMed

    Carrasco, Carlos J; Montilla, Francisco; Alvarez, Eleuterio; Mealli, Carlo; Manca, Gabriele; Galindo, Agustín

    2014-09-28

    The oxidation of organic sulphides with aqueous hydrogen peroxide in ionic liquids (ILs) catalysed by oxodiperoxomolybdenum complexes was investigated. The selective formation of several sulfones was achieved using the 1 : 3 ratio of sulphide : H2O2 in [C4mim][PF6] (C4mim = 1-butyl-3-methylimidazolium) in a reaction catalysed by the [Mo(O)(O2)2(H2O)n] complex. Conversely, sulfoxides were produced with good selectivities using a 1 : 1 ratio in the same solvent in a 1 h reaction with [Mo(O)(O2)2(Mepz)2] (Mepz = methylpyrazol). The use of [C4mim][PF6] as the solvent was advantageous for two reasons: (i) the improved performance of the H2O2-IL combination; (ii) recycling of the catalyst/IL mixture without a significant diminution of conversion or selectivity. A DFT analysis using the [Mo(O)(O2)2(L)] catalysts (L = Mepz, a; 3,5-dimethylpyrazole, dmpz, b; and H2O, c) indicated that a Sharpless-type outer-sphere mechanism is more probable than a Thiel-type one. The highest barrier of the catalytic profile was the oxo-transfer step, in which the nucleophilic attack of sulphide onto the peroxide ligand occurred with formation of dioxoperoxo species. In order to yield the sulfoxide and the starting catalyst, the oxidation of the resulting dioxoperoxo species with H2O2 was found to be the most favourable pathway. Subsequently, the sulfoxide to sulfone oxidation was performed through a similar mechanism involving the [Mo(O)(O2)2(L)] catalyst. The comparable energies found for the successive two oxo-transfer steps were in agreement with the experimental formation of sulfone in both the reaction with an excess of the oxidant and the stoichiometric reaction in the absence of the oxidant. In the latter case, diphenylsulfone was isolated as the major product in the 1 : 1 combination of diphenylsulphide and [Mo(O)(O2)2(Mepz)2] in the ionic liquid [C4mim][PF6]. Also, the compounds [HMepz]4[Mo8O26(Mepz)2]·2H2O, 1, [Hdmpz]4[Mo8O26(dmpz)2]·2dmpz, , and [Hpz]4[Mo8O22(O2

  11. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1984-01-01

    The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

  12. Silver-halide gelatin holograms

    NASA Astrophysics Data System (ADS)

    Chang, B. J.; Winick, K.

    1980-05-01

    The use of a silver-halide gelatin for volume phase holograms having a wide spectral response and lower exposure requirements than alternatives and using commercially available silver salts, is proposed. The main difference between the dichromated gelatin and silver-halide processes is the creation of a hologram latent image, which is given in the form of a hardness differential between exposed and unexposed regions in the silver halide hologram; the differential is in turn created by the reaction products of either tanning development or tanning bleach, which harden the gelatin with link-bonds between molecules.

  13. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  14. Orthodontic silver brazing alloys.

    PubMed

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy.

  15. Optimization of metal sulphide precipitation in fluidized-bed treatment of acidic wastewater.

    PubMed

    Kaksonen, A H; Riekkola-Vanhanen, M L; Puhakka, J A

    2003-01-01

    Sulphate-reducing biofilm and suspension processes were studied for treatment of synthetic wastewater containing sulphate, zinc and iron. With lactate supplemented wastewater with 170-230mg/l Zn and 58mg/l Fe, the following precipitation rates were obtained: 250 and 350mg/l d for Zn in fluidized-bed (FBR) and upflow anaerobic sludge blanket reactors, respectively, and 80mg/l d for Fe in both reactors with hydraulic retention time of 16h. The effluent Zn and Fe concentrations remained at less than 0.1 mg/l. The alkalinity produced in lactate oxidation increased the initial pH of 2.5-3, resulting in effluent pH of 7.5-8.5. The highest sulphate reduction rate was over 2000 mg/l d. In terms of sulphate reduction, hydrogen sulphide production and effluent alkalinity, the start-up of the FBR with the 10% fluidization rate was superior to the FBRs with 20-30% fluidization rates. With increased loading rates, high recycling rate became an advantage. After process failure caused by intentional overloading, the sulphate reduction partially recovered within 2 weeks. Metal precipitates in the reactors were predominantly FeS2, ZnS and FeS. The metal mass balance was as follows: 73-86% of Zn and Fe accumulated into the reactors and water level adjustors, 14-23% of the metals were washed out as precipitates and 0.05-0.15% remained as soluble metals. Biomass yield in the sulphate-reducing processes was 0.039-0.054g dry biomass (VS or VSS) per g of lactate oxidized or 0.035-0.074g dry biomass per g of sulphate reduced. The results of this work demonstrate that the lactate supplemented sulphate-reducing processes precipitated the metals as sulphides and neutralized the acidity of the synthetic wastewater.

  16. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation.

    PubMed

    Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd; Vegliò, Francesco

    2013-11-01

    This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2(2) full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3M of sulphuric acid, 10% v/v of H2O2 concentrated solution at 30% v/v, 10% w/w pulp density, 70°C and 3h of reaction. Two series of precipitation tests for zinc are carried out: a 2(2) full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2-2.5% and 10-12%v/v of Na2S concentrated solution at 10%w/v. In these conditions the coprecipitation of yttrium is of 15-20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75-80%.

  17. Hydrogen sulphide induces mouse paw oedema through activation of phospholipase A2

    PubMed Central

    di Villa Bianca, Roberta d'Emmanuele; Coletta, Ciro; Mitidieri, Emma; De Dominicis, Gianfranco; Rossi, Antonietta; Sautebin, Lidia; Cirino, Giuseppe; Bucci, Mariarosaria; Sorrentino, Raffaella

    2010-01-01

    BACKGROUND AND PURPOSE Hydrogen sulphide (H2S), considered as a novel gas transmitter, is produced endogenously in mammalian tissue from L-cysteine by two enzymes, cystathionine β-synthase and cystathionine γ-lyase. Recently, it has been reported that H2S contributes to the local and systemic inflammation in several experimental animal models. We conducted this study to investigate on the signalling involved in H2S-induced inflammation. EXPERIMENTAL APPROACH L-cysteine or sodium hydrogen sulphide (NaHS) was injected into the mouse hind paw and oedema formation was evaluated for 60 min. In order to investigate H2S-induced oedema formation, we used 5-HT and histamine receptor antagonists, and inhibitors of KATP channels or arachidonic acid cascade. Prostaglandin levels were determined in hind paw exudates by radioimmunoassay. Paws injected with L-cysteine or NaHS were examined by histological methods. KEY RESULTS Both NaHS and L-cysteine caused oedema characterized by a fast onset which peaked at 30 min. This oedematogenic action was not associated with histamine or 5-HT release or KATP channel activation. However, oedema formation was significantly inhibited by the inhibition of cyclooxygenases and selective inhibition of phospholipase A2. Prostaglandin levels were significantly increased in exudates of hind paw injected with NaHS or L-cysteine. The histological examination clearly showed an inflammatory state with a loss of tissue organization following NaHS or L-cysteine injection. CONCLUSIONS AND IMPLICATIONS Phospholipase A2 and prostaglandin production are involved in pro-inflammatory effects of H2S in mouse hind paws. The present study contributes to the understanding of the role of L-cysteine/H2S pathway in inflammatory disease. PMID:20825409

  18. Chloride channels mediate sodium sulphide-induced relaxation in rat uteri.

    PubMed

    Mijušković, Ana; Kokić, Aleksandra Nikolić; Dušić, Zorana Oreščanin; Slavić, Marija; Spasić, Mihajlo B; Blagojević, Duško

    2015-07-01

    Hydrogen sulphide reduces uterine contractility and is of potential interest as a treatment for uterine disorders. The aim of this study was to explore the mechanism of sodium sulphide (Na2 S)-induced relaxation of rat uterus, investigate the importance of redox effects and ion channel-mediated mechanisms, and any interactions between these two mechanisms. Organ bath studies were employed to assess the pharmacological effects of Na2 S in uterine strips by exposing them to Na2 S with or without Cl(-) channel blockers (DIDS, NFA, IAA-94, T16Ainh-A01, TA), raised KCl (15 and 75 mM), K(+) channel inhibitors (glibenclamide, TEA, 4-AP), L-type Ca(2+) channel activator (S-Bay K 8644), propranolol and methylene blue. The activities of antioxidant enzymes were measured in homogenates of treated uteri. The expression of bestrophin channel 1 (BEST-1) was determined by Western blotting and RT-PCR. Na2 S caused concentration-dependent reversible relaxation of spontaneously active and calcium-treated uteri, affecting both amplitude and frequency of contractions. Uteri exposed to 75 mM KCl were less sensitive to Na2 S compared with uteri in 15 mM KCl. Na2 S-induced relaxations were abolished by DIDS, but unaffected by other modulators or by the absence of extracellular HCO3 (-) , suggesting the involvement of chloride ion channels. Na2 S in combination with different modulators provoked specific changes in the anti-oxidant profiles of uteri. The expression of BEST-1, both mRNA and protein, was demonstrated in rat uteri. The relaxant effects of Na2 S in rat uteri are mediated mainly via a DIDS-sensitive Cl(-) -pathway. Components of the relaxation are redox- and Ca(2+) -dependent. © 2015 The British Pharmacological Society.

  19. Ferric citrate decreases ruminal hydrogen sulphide concentrations in feedlot cattle fed diets high in sulphate.

    PubMed

    Drewnoski, Mary E; Doane, Perry; Hansen, Stephanie L

    2014-01-28

    Dissimilatory reduction of sulphate by sulphate-reducing bacteria in the rumen produces sulphide, which can lead to a build-up of the toxic gas hydrogen sulphide (H2S) in the rumen when increased concentrations of sulphate are consumed by ruminants. We hypothesised that adding ferric Fe would competitively inhibit ruminal sulphate reduction. The effects of five concentrations and two sources (ferric citrate or ferric ammonium citrate) of ferric Fe were examined in vitro (n 6 per treatment). Rumen fluid was collected from a steer that was adapted to a high-concentrate, high-sulphate diet (0·51 % S). The addition of either source of ferric Fe decreased (P< 0·01) H2S concentrations without affecting gas production (P= 0·38), fluid pH (P= 0·80) or in vitro DM digestibility (P= 0·38) after a 24 h incubation. An in vivo experiment was conducted using eight ruminally fistulated steers (543 (sem 12) kg) in a replicated Latin square with four periods and four treatments. The treatments included a high-concentrate, high-sulphate control diet (0·46 % S) or the control diet plus ferric ammonium citrate at concentrations of 200, 300 or 400 mg Fe/kg diet DM. The inclusion of ferric Fe did not affect DM intake (P= 0·21). There was a linear (P< 0·01) decrease in the concentration of ruminal H2S as the addition of ferric Fe concentrations increased. Ferric citrate appears to be an effective way to decrease ruminal H2S concentrations, which could allow producers to safely increase the inclusion of ethanol co-products.

  20. Influence of methanethiol on biological sulphide oxidation in gas treatment system.

    PubMed

    Roman, Pawel; Bijmans, Martijn F M; Janssen, Albert J H

    2016-01-01

    Inorganic and organic sulphur compounds such as hydrogen sulphide (H2S) and thiols (RSH) are unwanted components in sour gas streams (e.g. biogas and refinery gases) because of their toxicity, corrosivity and bad smell. Biological treatment processes are often used to remove H2S at small and medium scales (<50 tons per day of H2S). Preliminarily research by our group focused on achieving maximum sulphur production from biological H2S oxidation in the presence of methanethiol. In this paper the underlying principles have been further studied by assessing the effect of methanethiol on the biological conversion of H2S under a wide range of redox conditions covering not only sulphur but also sulphate-producing conditions. Furthermore, our experiments were performed in an integrated system consisting of a gas absorber and a bioreactor in order to assess the effect of methanethiol on the overall gas treatment efficiency. This study shows that methanethiol inhibits the biological oxidation of H2S to sulphate by way of direct suppression of the cytochrome c oxidase activity in biomass, whereas the oxidation of H2S to sulphur was hardly affected. We estimated the kinetic parameters of biological H2S oxidation that can be used to develop a mathematical model to quantitatively describe the biodesulphurization process. Finally, it was found that methanethiol acts as a competitive inhibitor; therefore, its negative effect can be minimized by increasing the enzyme (biomass) concentration and the substrate (sulphide) concentration, which in practice means operating the biodesulphurization systems under low redox conditions.

  1. Chloride channels mediate sodium sulphide-induced relaxation in rat uteri

    PubMed Central

    Mijušković, Ana; Kokić, Aleksandra Nikolić; Dušić, Zorana Oreščanin; Slavić, Marija; Spasić, Mihajlo B; Blagojević, Duško

    2015-01-01

    Background and Purpose Hydrogen sulphide reduces uterine contractility and is of potential interest as a treatment for uterine disorders. The aim of this study was to explore the mechanism of sodium sulphide (Na2S)-induced relaxation of rat uterus, investigate the importance of redox effects and ion channel-mediated mechanisms, and any interactions between these two mechanisms. Experimental Approach Organ bath studies were employed to assess the pharmacological effects of Na2S in uterine strips by exposing them to Na2S with or without Cl− channel blockers (DIDS, NFA, IAA-94, T16Ainh-A01, TA), raised KCl (15 and 75 mM), K+ channel inhibitors (glibenclamide, TEA, 4-AP), L-type Ca2+ channel activator (S-Bay K 8644), propranolol and methylene blue. The activities of antioxidant enzymes were measured in homogenates of treated uteri. The expression of bestrophin channel 1 (BEST-1) was determined by Western blotting and RT-PCR. Key Results Na2S caused concentration-dependent reversible relaxation of spontaneously active and calcium-treated uteri, affecting both amplitude and frequency of contractions. Uteri exposed to 75 mM KCl were less sensitive to Na2S compared with uteri in 15 mM KCl. Na2S-induced relaxations were abolished by DIDS, but unaffected by other modulators or by the absence of extracellular HCO3−, suggesting the involvement of chloride ion channels. Na2S in combination with different modulators provoked specific changes in the anti-oxidant profiles of uteri. The expression of BEST-1, both mRNA and protein, was demonstrated in rat uteri. Conclusions and Implications The relaxant effects of Na2S in rat uteri are mediated mainly via a DIDS-sensitive Cl−-pathway. Components of the relaxation are redox- and Ca2+-dependent. PMID:25857480

  2. Optimization of Cu-Zn Massive Sulphide Flotation by Selective Reagents

    NASA Astrophysics Data System (ADS)

    Soltani, F.; Koleini, S. M. J.; Abdollahy, M.

    2014-10-01

    Selective floatation of base metal sulphide minerals can be achieved by using selective reagents. Sequential floatation of chalcopyrite-sphalerite from Taknar (Iran) massive sulphide ore with 3.5 % Zn and 1.26 % Cu was studied. D-optimal design of response surface methodology was used. Four mixed collector types (Aer238 + SIPX, Aero3477 + SIPX, TC1000 + SIPX and X231 + SIPX), two depressant systems (CuCN-ZnSO4 and dextrin-ZnSO4), pH and ZnSO4 dosage were considered as operational factors in the first stage of flotation. Different conditions of pH, CuSO4 dosage and SIPX dosage were studied for sphalerite flotation from first stage tailings. Aero238 + SIPX induced better selectivity for chalcopyrite against pyrite and sphalerite. Dextrin-ZnSO4 was as effective as CuCN-ZnSO4 in sphalerite-pyrite depression. Under optimum conditions, Cu recovery, Zn recovery and pyrite content in Cu concentrate were 88.99, 33.49 and 1.34 % by using Aero238 + SIPX as mixed collector, CuCN-ZnSO4 as depressant system, at ZnSO4 dosage of 200 g/t and pH 10.54. When CuCN was used at the first stage, CuSO4 consumption increased and Zn recovery decreased during the second stage. Maximum Zn recovery was 72.19 % by using 343.66 g/t of CuSO4, 22.22 g/t of SIPX and pH 9.99 at the second stage.

  3. Dimethyl sulphide and methanethiol formation in microbial mats: potential pathways for biogenic signatures.

    PubMed

    Visscher, Pieter T; Baumgartner, Laura K; Buckley, Daniel H; Rogers, Daniel R; Hogan, Mary E; Raleigh, Christopher D; Turk, Kendra A; Des Marais, David J

    2003-04-01

    Mechanisms of dimethyl sulphide (DMS) and methanethiol (MT) production and consumption were determined in moderately hypersaline mats, Guerrero Negro, Mexico. Biological pathways regulated the net flux of DMS and MT as revealed by increases in flux resulting from decreased salinity, increased temperature and the removal of oxygen. Dimethylsulphoniopropionate (DMSP) was not present in these microbial mats and DMS and MT are probably formed by the reaction of photosynthetically produced low-molecular weight organic carbon and biogenic hydrogen sulphide derived from sulphate reduction. These observations provide an alternative to the notion that DMSP or S-containing amino acids are the dominant precursors of DMS in intertidal sediment systems. The major sink for DMS in the microbial mats was biological consumption, whereas photochemical oxidation to dimethylsulphoxide was the major sink for DMS in the overlying water column. Diel flux measurements demonstrated that significantly more DMS is released from the system during the night than during the day. The major consumers of DMS in the presence of oxygen were monooxygenase-utilizing bacteria, whereas under anoxic conditions, DMS was predominantly consumed by sulphate-reducing bacteria and methanethiol was consumed by methanogenic bacteria. Aerobic and anaerobic consumption rates of DMS were nearly identical. Mass balance estimates suggest that the consumption in the water column is likely to be smaller than net the flux from the mats. Volatile organic sulphur compounds are thus indicators of high rates of carbon fixation and sulphate reduction in these laminated sediment ecosystems, and atmospheric sulphur can be generated as a biogenic signature of the microbial mat community.

  4. Synthesis of surface bound silver nanoparticles on cellulose fibers using lignin as multi-functional agent.

    PubMed

    Hu, Sixiao; Hsieh, You-Lo

    2015-10-20

    Lignin has proven to be highly effective "green" multi-functional binding, complexing and reducing agents for silver cations as well as capping agents for the synthesis of silver nanoparticles on ultra-fine cellulose fibrous membranes. Silver nanoparticles could be synthesized in 10min to be densely distributed and stably bound on the cellulose fiber surfaces at up to 2.9% in mass. Silver nanoparticle increased in sizes from 5 to 100nm and became more polydispersed in size distribution on larger fibers and with longer synthesis time. These cellulose fiber bound silver nanoparticles did not agglomerate under elevated temperatures and showed improved thermal stability. The presence of alkali lignin conferred moderate UV absorbing ability in both UV-B and UV-C regions whereas the bound silver nanoparticles exhibited excellent antibacterial activities toward Escherichia coli.

  5. Soft-Etching Copper and Silver Electrodes for Significant Device Performance Improvement toward Facile, Cost-Effective, Bottom-Contacted, Organic Field-Effect Transistors.

    PubMed

    Wang, Zongrui; Dong, Huanli; Zou, Ye; Zhao, Qiang; Tan, Jiahui; Liu, Jie; Lu, Xiuqiang; Xiao, Jinchong; Zhang, Qichun; Hu, Wenping

    2016-03-01

    Poor charge injection and transport at the electrode/semiconductor contacts has been so far a severe performance hurdle for bottom-contact bottom-gate (BCBG) organic field-effect transistors (OFETs). Here, we have developed a simple, economic, and effective method to improve the carrier injection efficiency and obtained high-performance devices with low cost and widely used source/drain (S/D) electrodes (Ag/Cu). Through the simple electrode etching process, the work function of the electrodes is more aligned with the semiconductors, which reduces the energy barrier and facilitates the charge injection. Besides, the formation of the thinned electrode edge with desirable micro/nanostructures not only leads to the enlarged contact side area beneficial for the carrier injection but also is in favor of the molecular self-organization for continuous crystal growth at the contact/active channel interface, which is better for the charge injection and transport. These effects give rise to the great reduction of contact resistance and the amazing improvement of the low-cost bottom-contact configuration OFETs performance.

  6. Improved bipolar resistive switching memory characteristics in Ge0.5Se0.5 solid electrolyte by using dispersed silver nanocrystals on bottom electrode.

    PubMed

    Kim, Jang-Han; Nam, Ki-Hyun; Hwang, Inchan; Cho, Won-Ju; Park, Byoungchoo; Chung, Hong-Bay

    2014-12-01

    Resistive switching random-access memory (ReRAM) devices based on chalcogenide solid electrolytes have recently become a promising candidate for future low-power nanoscale nonvolatile memory application. The resistive switching mechanism of ReRAM is based on the formation and rupture of conductive filament (CF) in the chalcogenide solid electrolyte layers. However, the random diffusion of metal ions makes it hard to control the CF formation, which is one of the major obstacles to improving device performance of ReRAM devices. We demonstrate the spin-coated metal nanocrystals (NCs) enhance the bipolar resistive switching (BRS) memory characteristics. Compared to the Ag/Ge0.5Se0.5/Pt structure, excellent resistive switching memory characteristics were obtained from the Ag/Ge0.5Se0.5/Ag NCs/Pt structure. Ag NCs improve the uniformity of resistance values and reduce the reset voltage and current. A stable DC endurance (> 100 cycles) and a high data retention (> 10(4) sec) were achieved by spin coating the Ag NCs on the Pt bottom electrode for ReRAMs.

  7. Architecture and emplacement of the Nebo-Babel gabbronorite-hosted magmatic Ni-Cu-PGE sulphide deposit, West Musgrave, Western Australia

    NASA Astrophysics Data System (ADS)

    Seat, Zoran; Beresford, Stephen W.; Grguric, Benjamin A.; Waugh, Rob S.; Hronsky, Jon M. A.; Gee, M. A. Mary; Groves, David I.; Mathison, Charter I.

    2007-08-01

    The Nebo-Babel Ni-Cu-platinum-group element (PGE) sulphide deposit in the West Musgrave Block, Western Australia, is the largest nickel sulphide discovery in the last 10 years. The deposit is hosted within a concentrically zoned, olivine-free, tube-like (chonolithic), gabbronorite intrusion associated with the, approximately, 1,078-Ma Giles Complex-layered intrusions in the Warakurna large igneous province. Emplaced into sulphide-free amphibolite facies orthogneiss, the fault-offset Nebo-Babel chonolith extends for 5 km and has a cross-section of 1 × 0.5 km. Igneous mineralogy, fabrics, and textures are well preserved. The lithostratigraphy includes variably textured leucogabbronorites (VLGN) that form an outer shell around mineralised gabbronorite (MGN), with barren gabbronorite (BGN) and oxide-apatite gabbronorite (OAGN) in the middle and lower parts of the chonolith. Mineral and whole-rock geochemistry indicate that the units become progressively evolved in the order: VLGN, MGN, BGN, and OAGN, and that incompatible trace-element concentrations increase downwards within the MGN and BGN. The mineralisation, which is confined to the early, more primitive units (VLGN and MGN), occurs as massive sulphide breccias and stringers and as disseminated gabbronorite-hosted sulphides. The massive sulphides were emplaced late in the intrusive sequence, have different PGE chemistry and Cu tenor to the disseminated sulphides, and have undergone sulphide fractionation. The distribution of disseminated sulphides, which are primary magmatic in origin, is related to chonolith geometry and magma flow regimes, rather than to gravitational settling. Sulfur-bearing country rocks are absent in the Nebo-Babel deposit area, and thus, local crustal S addition was unlikely to have been the major mechanism in achieving sulphide immiscibility. The Nebo-Babel intrusion is part of an originally continuous magma chonolith with multiple and related magma pulses. The parental magma was medium- to

  8. The double effects of silver nanoparticles on the PVDF membrane: Surface hydrophilicity and antifouling performance

    NASA Astrophysics Data System (ADS)

    Li, Jian-Hua; Shao, Xi-Sheng; Zhou, Qing; Li, Mi-Zi; Zhang, Qi-Qing

    2013-01-01

    In this study, silver nanoparticles were used to endow poly(vinylidene fluoride) (PVDF) membrane with excellent surface hydrophilicity and outstanding antifouling performance. Silver nanoparticles were successfully immobilized onto PVDF membrane surface under the presence of poly(acrylic acid) (PAA). The double effects of silver nanoparticles on PVDF membrane, i.e., surface hydrophilicity and anti-fouling performance, were systematically investigated. Judging from result of water static contact measurement, silver nanoparticles had provided a significant improvement in PVDF membrane surface hydrophilicity. And the possible explanation on the improvement of PVDF membrane surface hydrophilicity with silver nanoparticles was firstly proposed in this study. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membrane. Flux recovery ratio (FRR) increased about 40% after the presence of silver nanoparticles on the PVDF membrane surface, elucidating the anti-organic fouling performance of PVDF membrane was elevated by silver nanoparticles. Simultaneously, anti-bacterial test confirmed that PVDF membrane showed superior anti-biofouling activity because of silver nanoparticles. The above-mentioned results clarified that silver nanoparticles can endow PVDF membrane with both excellent surface hydrophilicity and outstanding antifouling performance in this study.

  9. Nanoparticle release from nano-silver antimicrobial food containers.

    PubMed

    Echegoyen, Yolanda; Nerín, Cristina

    2013-12-01

    Polymer nanocomposites incorporating metal or metal oxide nanoparticles have been developed to improve their characteristics (flexibility, gas barrier properties, antimicrobial or antioxidant properties, etc.). Among them silver nanoparticles are used because of their antimicrobial effect in many daily life materials, i.e. food packaging. However, there is not any reference to the migration of nanoparticles to the food. In this paper the results of migration studies (with different simulant solutions and times) in three commercial nanosilver plastic food containers are shown. Migration solutions were evaluated by ICP-MS and SEM-EDX analysis and silver in dissolved form and silver as nanoparticles were analyzed, a key aspect for the toxicity. Silver migration was observed for all samples studied, with the total silver migration values ranging between 1.66 and 31.46 ng/cm(2) (lower than the permissible limits). Size and morphology of the silver nanoparticles changed for the different samples (ranging between 10 and 60 nm) and migration of other nanosized materials was also confirmed.

  10. Preparation and characterization of size controllable spherical silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Yang, Ai-ling; Li, Shun-pin; Wang, Yu-jin; Bao, Xi-chang; Yang, Ren-qiang

    2014-05-01

    By adjusting pH values of reactant system, the mass ratio of stabilizer/water and aging temperature, size controllable spherical silver nanoparticles (NPs) were synthesized. The properties of silver NPs are characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet visible (UV-VIS) absorption spectra. Within the pH values of 7.0-11.0, the aging temperature of 80 °C is better to improve silver NPs in shape to nearly sphere, concentrate size distribution and reduce aggregation than the aging temperature of 25 °C. The shape and dispersibility of silver NPs are the best when the pH of the reactant system is within 7.0-8.0. With pH of 7.5, aging at 80 °C, and stabilizer/water mass ratio of 1%, the spherical silver NPs with sizes of 50-70 nm were synthesized. The results are promising to be used to synthesize core/shell NPs when silver NPs are as core.

  11. PMAA`s Silver/Gold National Certification Program - update

    SciTech Connect

    Boltz, R.

    1996-07-01

    The Petroleum Marketers Association of America`s (PMAA) Silver/Gold National Certification Program is discussed. The oil heat technician certification is a process whose time has come. The information age has put us in an era of improved technology as well as improved equipment. The advantages of the oil heat certification program for oil heat dealers, technicians, and customers are listed.

  12. Toxicity of silver nanoparticles - nanoparticle or silver ion?

    PubMed

    Beer, Christiane; Foldbjerg, Rasmus; Hayashi, Yuya; Sutherland, Duncan S; Autrup, Herman

    2012-02-05

    The toxicity of silver nanoparticles (AgNPs) has been shown in many publications. Here we investigated to which degree the silver ion fraction of AgNP suspensions, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensions were more toxic when the initial silver ion fraction was higher. At 1.5μg/ml total silver, A549 cells exposed to an AgNP suspension containing 39% silver ion fraction showed a cell viability of 92%, whereas cells exposed to an AgNP suspension containing 69% silver ion fraction had a cell viability of 54% as measured by the MTT assay. In addition, at initial silver ion fractions of 5.5% and above, AgNP-free supernatant had the same toxicity as AgNP suspensions. Flow-cytometric analyses of cell cycle and apoptosis confirmed that there is no significant difference between the treatment with AgNP suspension and AgNP supernatant. Only AgNP suspensions with silver ion fraction of 2.6% or less were significantly more toxic than their supernatant as measured by MTT assays. From our data we conclude that at high silver ion fractions (≥5.5%) the AgNPs did not add measurable additional toxicity to the AgNP suspension, whereas at low silver ion fractions (≤2.6%) AgNP suspensions are more toxic than their supernatant. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Silver-coated LiVPO4F composite with improved electrochemical performance as cathode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Yang, Lin

    2015-12-01

    Nano-structured LiVPO4F/Ag composite cathode material has been successfully synthesized via a sol-gel route. The structural and physical properties, as well as the electrochemical performance of the material are compared with those of the pristine LiVPO4F. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that Ag particles are uniformly dispersed on the surface of LiVPO4F without destroying the crystal structure of the bulk material. An analysis of the electrochemical measurements show that the Ag-modified LiVPO4F material exhibits high discharge capacity, good cycle performance (108.5 mAh g-1 after 50th cycles at 0.1 C, 93% of initial discharge capacity) and excellent rate behavior (81.8 mAh g-1 for initial discharge capacity at 5 C). The electrochemical impedance spectroscopy (EIS) results reveal that the adding of Ag decreases the charge-transfer resistance (Rct) of LiVPO4F cathode. This study demonstrates that Ag-coating is a promising way to improve the electrochemical performance of the pristine LiVPO4F for lithium-ion batteries cathode material.

  14. Laser-Direct Writing of Silver Metal Electrodes on Transparent Flexible Substrates with High-Bonding Strength.

    PubMed

    Zhou, Weiping; Bai, Shi; Ma, Ying; Ma, Delong; Hou, Tingxiu; Shi, Xiaomin; Hu, Anming

    2016-09-21

    We demonstrate a novel approach to rapidly fabricate conductive silver electrodes on transparent flexible substrates with high-bonding strength by laser-direct writing. A new type of silver ink composed of silver nitrate, sodium citrate, and polyvinylpyrrolidone (PVP) was prepared in this work. The role of PVP was elucidated for improving the quality of silver electrodes. Silver nanoparticles and sintered microstructures were simultaneously synthesized and patterned on a substrate using a focused 405 nm continuous wave laser. The writing was completed through the transparent flexible substrate with a programmed 2D scanning sample stage. Silver electrodes fabricated by this approach exhibit a remarkable bonding strength, which can withstand an adhesive tape test at least 50 times. After a 1500 time bending test, the resistance only increased 5.2%. With laser-induced in-situ synthesis, sintering, and simultaneous patterning of silver nanoparticles, this technology is promising for the facile fabrication of conducting electronic devices on flexible substrates.

  15. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  16. Silver stain for electron microscopy

    NASA Technical Reports Server (NTRS)

    Corbett, R. L.

    1972-01-01

    Ammoniacal silver stain used for light microscopy was adapted advantageously for use with very thin biological sections required for electron microscopy. Silver stain can be performed in short time, has more contrast, and is especially useful for low power electron microscopy.

  17. Geochemical Controls on the Mobility of Lead and Silver in Tropical Floodplain Sediments.

    NASA Astrophysics Data System (ADS)

    Watson, E. A.; Apte, S. C.; Dietrich, W. E.; Taylor, M. P.

    2005-12-01

    The Strickland River, Papua New Guinea, which is the dominant drainage to the Fly River delta, receives inputs of mine tailings and waste rock from the Porgera gold mine, which is situated at an elevation of 2,500 meters in the upper catchment of the river system. While the contribution to the overall sediment load of the river is small, the mine derived sediments contain elevated concentrations of particulate silver and lead. The vertical core profiles of these elements were used as part of collaborative investigation among an NSF sponsored Margins Source to Sink research group, University of Papua New Guinea researchers, Porgera Joint Venture (PNG), CSIRO (Australia) and Macquarie University (Australia), to map the extent and rate of overbank deposition along the Strickland River. A key question is what proportion of the rivers sediment load is deposited on the lowland floodplain before the river joins the Fly River. An important property of any suitable particulate tracer is its low mobility following deposition. The aim of this study was to investigate the geochemical factors that may affect post-depositional mobility of lead and silver in floodplain sediments. Laboratory modelling studies were conducted to examine the effects of key parameters such as pH, dissolved organic carbon and redox changes resulting from wet/dry cycling of sediments during flooding and drying events. The solid phase speciation of silver and lead in floodplain sediments was also assessed by measurement of acid volatile sulphide concentrations and application of acid leaching procedures. A conceptual model of the geochemical processes affecting particulate silver and lead cycling in floodplain sediments will be presented.

  18. Lewis Ponds, a hybrid carbonate and volcanic-hosted polymetallic massive sulphide deposit, New South Wales, Australia

    NASA Astrophysics Data System (ADS)

    Agnew, Michael W.; Large, Ross R.; Bull, Stuart W.

    2005-03-01

    The Lewis Ponds Zn Pb Cu Ag Au deposit, located in the eastern Lachlan Fold Belt, central western New South Wales, exhibits the characteristics of both volcanic-hosted massive sulphide and carbonate-hosted replacement deposits. Two stratabound massive to disseminated sulphide zones, Main and Toms, occur in a tightly folded Upper Silurian sequence of marine felsic volcanic and sedimentary rocks. They have a combined indicated resource of 5.7 Mt grading 3.5% Zn, 2.0% Pb, 0.19% Cu, 97 g/t Ag and 1.9 g/t Au. Main Zone is hosted by a thick unit of poorly sorted mixed provenance breccia, limestone-clast breccia and quartz crystal-rich sandstone, whereas Toms Zone occurs in the overlying siltstone. Pretectonic carbonate chalcopyrite pyrite and quartz pyrite stringer veins occur in the footwall porphyritic dacite, south of Toms Zone. Strongly sheared dolomite chalcopyrite pyrrhotite veins directly underlie the Toms massive sulphide lens. The mineralized zones consist predominantly of pyrite, sphalerite and galena. Paragenetically early framboidal, dendritic and botryoidal pyrite aggregates and tabular pyrrhotite pseudomorphs of sulphate occur throughout the breccia and sandstone beds that host Main Zone, but are rarely preserved in the annealed massive sulphide in Toms Zone. Main and Toms zones are associated with a semi-conformable hydrothermal alteration envelope, characterized by texturally destructive chlorite-, dolomite- and quartz-rich assemblages. Dolomite, chlorite, quartz, calcite and sulphides have selectively replaced breccia and sandstone beds in the Main Zone host sequence, whereas the underlying porphyritic dacite is weakly sericite altered. Vuggy and botryoidal textures resulted from partial dissolution of the dolomite-altered sedimentary rocks and unimpeded growth of base metal sulphides, carbonate and quartz into open cavities. The intense chlorite-rich alteration assemblage, underlying Toms Zone, grades outward into a weak pervasive sericite quartz

  19. Formation mechanism of silver nanoparticle 1D microstructures and their hierarchical assembly into 3D superstructures

    NASA Astrophysics Data System (ADS)

    Suber, Lorenza; Plunkett, William. R.

    2010-01-01

    Flower-like silver nanoparticle superstructures are prepared by the reaction of silver nitrate and ascorbic acid in an acidic aqueous solution of a polynaphthalene system. The three-dimensional flower-like structure has a purely hierarchic arrangement, wherein each petal is composed of bundles of silver particle chains, each enclosed in a polymer sheath. The ordering arises from strong adsorption of silver ions onto the polymer and by the interplay of the redox properties of nitric and ascorbic acid. As a result, linear silver cyanide, formed on the polymer, probably due to intrinsic electric dipole fields, organizes the silver particle chains in dumbbell-like structures, resembling buds and flower-like structures. By dilution and heating of the mother liquors, it is also possible to obtain single petals, i.e. micrometer sized bundles of linearly aggregated silver nanoparticle chains, each enclosed in a polymer sheath. The comprehension of the hierarchic assembly of silver nanoparticles, paves the way to a facile general method to prepare polymer-metal nanoparticle chains and flower-like superstructures. The results of this study improve both the understanding of the formation mechanism of hierarchic structures at mild temperatures and our ability to tailor them to sizes and shapes appropriate for technological purposes.Flower-like silver nanoparticle superstructures are prepared by the reaction of silver nitrate and ascorbic acid in an acidic aqueous solution of a polynaphthalene system. The three-dimensional flower-like structure has a purely hierarchic arrangement, wherein each petal is composed of bundles of silver particle chains, each enclosed in a polymer sheath. The ordering arises from strong adsorption of silver ions onto the polymer and by the interplay of the redox properties of nitric and ascorbic acid. As a result, linear silver cyanide, formed on the polymer, probably due to intrinsic electric dipole fields, organizes the silver particle chains in

  20. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  1. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  2. Silver clusters and chemistry in zeolites

    SciTech Connect

    Sun, T.; Seff, K. . Dept. of Chemistry)

    1994-06-01

    The spectroscopic work done on silver clusters trapped in solid noble gas matrices at low temperature has been extensively reviewed by Ozin, and Henglein has done the same for photochemical studies of colloidal silver particles in solution. This article will review the chemistry of silver in zeolite hosts, including the synthesis and structures of silver clusters. 127 refs.

  3. Effect of silver incorporation in phase formation and band gap tuning of tungsten oxide thin films

    SciTech Connect

    Jolly Bose, R.; Kumar, R. Vinod; Sudheer, S. K.; Mahadevan Pillai, V. P.; Reddy, V. R.; Ganesan, V.

    2012-12-01

    Silver incorporated tungsten oxide thin films are prepared by RF magnetron sputtering technique. The effect of silver incorporation in micro structure evolution, phase enhancement, band gap tuning and other optical properties are investigated using techniques such as x-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and UV-Visible spectroscopy. Effect of silver addition in phase formation and band gap tuning of tungsten oxide thin films are investigated. It is found that the texturing and phase formation improves with enhancement in silver content. It is also found that as the silver incorporation enhances the thickness of the films increases at the same time the strain in the film decreases. Even without annealing the desired phase can be achieved by doping with silver. A broad band centered at the wavelength 437 nm is observed in the absorption spectra of tungsten oxide films of higher silver incorporation and this can be attributed to surface plasmon resonance of silver atoms present in the tungsten oxide matrix. The transmittance of the films is decreased with increase in silver content which can be due to increase in film thickness, enhancement of scattering, and absorption of light caused by the increase of grain size, surface roughness and porosity of films and enhanced absorption due to surface plasmon resonance of silver. It is found that silver can act as the seed for the growth of tungsten oxide grains and found that the grain size increases with silver content which in turn decreases the band gap of tungsten oxide from 3.14 eV to 2.70 eV.

  4. Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens

    NASA Astrophysics Data System (ADS)

    Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Vanaja, Mahendran; Annadurai, Gurusamy

    2016-07-01

    The present investigation shows the biosynthesis of eco-friendly silver nanoparticles using culture supernatant of Enterococcus sp. and study the effect of enhanced antimicrobial activity, anticancer activity against pathogenic bacteria, fungi and cancer cell lines. Silver nanoparticles was synthesized by adding 1 mM silver nitrate into the 100 ml of 24 h freshly prepared culture supernatant of Enterococcus sp. and were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Selected Area Diffraction X-Ray (SAED), Energy Dispersive X Ray (EDX) and Fourier Transform Infra red Spectroscopy (FT-IR). The synthesized silver nanoparticles were impregnated with commercial antibiotics for evaluation of enhanced antimicrobial activity. Further these synthesized silver nanoparticles were assessed for its anticancer activity against cancer cell lines. In this study crystalline structured nanoparticles with spherical in the size ranges from 10 to 80 nm and it shows excellent enhanced antimicrobial activity than the commercial antibiotics. The in vitro assay of silver nanoparticles on anticancer have great potential to inhibit the cell viability. Amide linkages and carboxylate groups of proteins from Enterococcus sp. may bind with silver ions and convert into nanoparticles. The activities of commercial antibiotics were enhanced by coating silver nanoparticles shows significant improved antimicrobial activity. Silver nanoparticles have the great potential to inhibit the cell viability of liver cancer cells lines (HepG2) and lung cancer cell lines (A549).

  5. Microwave-assisted deposition of silver nanoparticles on bamboo pulp fabric through dopamine functionalization

    NASA Astrophysics Data System (ADS)

    Peng, Linghui; Guo, Ronghui; Lan, Jianwu; Jiang, Shouxiang; Lin, Shaojian

    2016-11-01

    Silver nanoparticles were synthesized on bamboo pulp fabric with dopamine as the adhesive and reducing agent under microwave radiation. The silver nanoparticle coated bamboo pulp fabrics were characterized by X-ray photoelectron spectroscopy, scanning electron microscope and X-ray diffraction. Ultraviolet (UV) protection, color and water contact angles of the silver nanoparticle coated bamboo pulp fabrics were evaluated. In addition, the influences of concentrations of dopamine and treatment time on color strength (K/S values) of the silver nanoparticle coated fabric were investigated. Fastness to washing was employed to evaluate the adhesive strength between the silver coating and the bamboo pulp fabric modified with dopamine. The results show that the dopamine modified bamboo pulp fabric is evenly covered with silver nanoparticles. The silver nanoparticle coated bamboo pulp fabric modified with dopamine shows the excellent UV protection with an ultraviolet protection factor of 157.75 and the hydrophobicity with a water contact angle of 132.4°. In addition, the adhesive strength between the silver nanoparticles and bamboo pulp fabric is significantly improved. Silver nanoparticles coating on bamboo pulp fabric modified with dopamine is environmentally friendly, easy to carry out and highly efficient.

  6. 187Re- 187Os Nuclear Geochronometry: Dating Peridotitic Diamond Sulphide Inclusions

    NASA Astrophysics Data System (ADS)

    Roller, Goetz

    2015-04-01

    Nuclear geochronometry [1-2] is a new dating method which combines principles of geochronology with nuclear astrophysics. It is embedded in other scientific fields like cosmochemistry, cosmology and nuclear theory, which pose tight constraints for nuclear geochronometry. It is based upon identified Re/Os element ratios ˜ 1, interpreted as the nuclear production ratio, and ultra-subchondritic initial 187Os/188Os ratios within terrestrial rocks, suggesting that Earth's core still contains element ratios and isotopic signatures of at least two rapid (r) neutron-capture process [3] events. The 13.78 Ga old component, represented by the isotopic signature of a komatiitic basalt [5085 BasKom] [4] from the Barberton Greenstone Belt (Onverwacht Group, South Africa), is assigned to the Earth's inner core. The other isotopic signatures identified so far within pyroxenites / komatiites are assigned to its outer core due to at least one gravitational collapse of the old component, commencing ˜ 3.48 Ga [2] and resulting in one or more additional r-process event(s). Here I show that 187Re-187Os nuclear geochronometry can also be successfully applied for dating peridotitic diamond sulphide inclusions by means of two-point-isochrones (TPI), using a so-called nuclear geochronometer always as the second data point in a TPI diagram. It turns out that the method may have a huge potential to constrain the chemical evolution of the SCLM. For example, TPI ages for Ellendale (Australia) peridotitic diamond sulphide inclusions EL50, EL23, EL54-1, EL54-3, EL55-1 and EL65 reported in the literature [5] reveal at least two main fractionation events. The age cluster between 1.4 Ga and 1.5 Ga is consistent with a previously reported isochrone age [5]. The event ˜ 2.3 ± 0.3 Ga overlaps the Great Oxidation Event (GOE) between 2.22 Ga and 2.46 Ga. While the ˜ 1.4 Ga to 1.5 Ga events lead to fractionation of the 187Re/188Os ratios towards values typical for mantle peridotite, the latter caused

  7. Imaging Seafloor Massive Sulphides at the TAG hydrothermal fields, from the Blue Mining seismic project

    NASA Astrophysics Data System (ADS)

    Gil de la Iglesia, Alba; Vardy, Mark; Bialas, Jörg; Dannowski, Anke; Schröder, Henning; Minshull, Tim; Chidlow, Kasia; Murton, Bramly

    2017-04-01

    The Trans-Atlantic Geotraverse (TAG) hydrothermal field, located at the Mid-Atlantic Ridge (26°N), is known for the existence of Seafloor Massive Sulphides (SMS) discovered by the Trans-Atlantic Geotraverse cruise (Rona et al., 1986). The TAG comprises a low-temperature alteration zone, five inactive, high-temperature hydrothermal deposits, and the hydrothermal active TAG mound. TAG is also known for being one of the eight known SMS with a size larger than 2M tones (Hannington et al., 2011). The known SMS deposits do not have the same dimensions as the Massive Sulphides (MS) found on land, covering areas from 10s-100s m2 and their accessibility is more complicated, being located at 800-6000 m water depth. Although they do not seem to be economically exploitable at present, those deep-sea mineral resources could be important targets in the near future. One of the aims of the European-funded Blue Mining project is to identify the SMS deposit dimensions for the future environmentally sustainable and clean deep-sea mining. The Blue Mining project is focused on the extinct Seafloor Massive Sulphides (eSMS) in the TAG hydrothermal field, in particular Shinkai, Southern and Shimmering mounds. In May/June 2016 the German RV METEOR carried out a seismic refraction/reflection wide-angle (WA) experiment acquiring thirty multichannel seismic (MCS) profiles crossing the TAG hydrothermal field. GEOMAR's 2-unit air-gun array with a total volume of 760 cubic-inches was used, triggering seismic pulses every 12 s along the MCS profiles. Reflected and refracted events from the shallow-towed sources were recorded by 20 Ocean Bottom Seismometers (OBS) and 5 Ocean Bottom Hydrophones (OBH). To obtain the internal velocities and gross geometries of these deposits, 10 of 20 OBS were located on top of the eSMS, Shinaki and Southern mounds, while the other 10 instruments were located in extension of the profiles, covering Shimmering mounds and regional targets. In this presentation, we

  8. Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review.

    PubMed

    Hadrup, Niels; Lam, Henrik R

    2014-02-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached.

  9. Hydrogen sulphide and phosphine interactions with human skin in vitro: Application to hazardous material incident decision making for skin decontamination.

    PubMed

    Gaskin, Sharyn; Heath, Linda; Pisaniello, Dino; Evans, Richard; Edwards, John W; Logan, Michael; Baxter, Christina

    2016-03-03

    Accidental or intentional releases of toxic gases can have significant public health consequences and emergency resource demands. Management of exposed individuals during hazardous material incidents should be risk and evidence based, but there are knowledge gaps in relation to dermal absorption of gases and management advice for potentially exposed individuals. Using a modified Organization for Economic Co-operation and Development (OECD) in vitro toxicology protocol with human donor skin, this article reports on two common and odorous chemicals, hydrogen sulphide and phosphine. Results show that undamaged human skin provides a good barrier to hydrogen sulphide (up to 800 ppm) and phosphine (up to 1000 ppm) penetration for up to 30 min exposures, with little variability in the presence of clothing or in elevated temperature and humidity conditions. A practical guideline template for skin decontamination has been developed, and implications of the research for first responders are outlined.

  10. Multiple hydrothermal and metamorphic events in the Kidd Creek volcanogenic massive sulphide deposit, Timmins, Ontario: evidence from tourmalines and chlorites

    USGS Publications Warehouse

    Slack, J.F.; Coad, P.R.

    1989-01-01

    The tourmalines and chlorites record a series of multiple hydrothermal and metamorphic events. Paragenetic studies suggest that tourmaline was deposited during several discrete stages of mineralization, as evidence by brecciation and cross-cutting relationships. Most of the tourmalines have two concentric growth zones defined by different colours (green, brown, blue, yellow). Some tourmalines also display pale discordant rims that cross-cut and embay the inner growth zones and polycrystalline, multiple-extinction domains. Late sulphide veinlets (chalcopyrite, pyrrhotite) transect the inner growth zones and pale discordant rims of many crystals. The concentric growth zones are interpreted as primary features developed by the main ore-forming hydrothermal system, whereas the discordant rims, polycrystalline domains, and cross-cutting sulphide veinlets reflect post-ore metamorphic processes. Variations in mineral proportions and mineral chemistry within the deposit mainly depend on fluctuations in temperature, pH, water/rock ratios, and amounts of entrained seawater. -from Authors

  11. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  12. Silver nanoparticles with tunable work functions

    SciTech Connect

    Wang, Pangpang; Tanaka, Daisuke; Ryuzaki, Sou; Araki, Shohei; Okamoto, Koichi; Tamada, Kaoru

    2015-10-12

    To improve the efficiencies of electronic devices, materials with variable work functions are required to decrease the energy level differences at the interfaces between working layers. Here, we report a method to obtain silver nanoparticles with tunable work functions, which have the same silver core of 5 nm in diameter and are capped by myristates and 1-octanethoilates self-assembled monolayers, respectively. The silver nanoparticles capped by organic molecules can form a uniform two-dimensional sheet at air-water interface, and the sheet can be transferred on various hydrophobic substrates. The surface potential of the two-dimensional nanoparticle sheet was measured in terms of Kelvin probe force microscopy, and the work function of the sheet was then calculated from the surface potential value by comparing with a reference material. The exchange of the capping molecules results in a work function change of approximately 150–250 meV without affecting their hydrophobicity. We systematically discussed the origin of the work function difference and found it should come mainly from the anchor groups of the ligand molecules. The organic molecule capped nanoparticles with tunable work functions have a potential for the applications in organic electronic devices.

  13. Influence of silver content on rifampicin adsorptivity for magnetite/Ag/rifampicin nanoparticles

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Olena; Coy, Emerson; Peplinska, Barbara; Jarek, Marcin; Lewandowski, Mikołaj; Załęski, Karol; Warowicka, Alicja; Wozniak, Anna; Babutina, Tatiana; Jurga-Stopa, Justyna; Dolinsek, Janez; Jurga, Stefan

    2017-02-01

    Magnetite nanoparticles (NPs) decorated with silver (magnetite/Ag) are intensively investigated due to their application in the biomedical field. We demonstrate that the increase of silver content on the surface of nanoparticles improves the adsorptivity of antibiotic rifampicin as well as antibacterial properties. The use of ginger extract allowed to improve the silver nucleation on the magnetite surface that resulted in an increase of silver content. Physicochemical and functional characterization of magnetite/Ag NPs was performed. Our results show that 5%-10% of silver content in magnetite/Ag NPs is already sufficient for antimicrobial properties against Streptococcus salivarius and Staphylococcus aureus. The rifampicin molecules on the magnetite/Ag NPs surface made the spectrum of antimicrobial activity wider. Cytotoxicity evaluation of the magnetite/Ag/rifampicin NPs showed no harmful action towards normal human fibroblasts, whereas the effect on human embryonic kidney cell viability was time and dose dependent.

  14. Microstructure and Joint Properties of Nano-Silver Paste by Ultrasonic-Assisted Pressureless Sintering

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Jing, Hongyang; Han, Yongdian; Xu, Lianyong; Lu, Guoquan

    2016-06-01

    In recent years, sintering nano-silver paste has become a popular worldwide technology. This paper presents the effect of ultrasonic vibration on the microstructure and mechanical properties of pressureless sintered nano-silver joints. Ultrasonic waves have been introduced prior to sintering using a new type of nano-silver paste in order to improve bonding of large-area chips (≥10 × 10 mm2). The results show that ultrasonic vibration can not only reduce black pores, increase the size and the density of sintered silver, but also transfer the fracture mode of joints to cohesive failure. With increasing ultrasonic power or time, the shear strength of joints gradually increases linearly. The surface of the sintered silver, the fracture surface, and the cross section of joints were examined, and the microstructure has a transition zone at the edge of the joints that is insufficiently sintered. Ultrasonic vibration can reduce the transition zone and thus improve the reliability of joints.

  15. A record of reversed polarity carries by the iron sulphide greigite in British early Pleistocene sediments

    NASA Astrophysics Data System (ADS)

    Hallam, D. F.; Maher, B. A.

    1994-01-01

    Palaeomagnetic measurements were made on samples extracted from a short sequence of early Pleistocene estuarine clays, now exposed in a sea cliff near Sheringham on the north Norfolk coast, UK. On the basis of earlier palynological work, these clays had been ascribed a Pastonian (late Tiglian) age. The clays show marked changes in colour, from reddish-brown at the top of the unit, to blue-grey in the middle, and grey-brown at the base. The palaeomagnetic data vary in close association with these colour changes. The top and basal brown clays show scattered normal directions of low intensity, while the middle blue clays show strongly clustered reversed directions, of much higher intensities. Some samples taken from the boundary between the middle blue clays and upper red clays show upon demagnetisation a normal overprint on a stable reversed polarity. Using high-gradient magnetic extraction, magnetic concentrates have been obtained from the strongly magnetic middle blue clays. The presence of iron sulphide minerals in these concentrates was identified using energy-dispersive X-ray analysis during scanning electron microscopy. More specifically, X-ray diffraction identifies greigite as the only detectable ferrimagnetic mineral in the magnetic concentrates. Rock magnetic measurements show clear qualitative differences in the magnetic mineralogies of the three clay subunits, but absolute identification of the magnetic mineralogy of the weakly magnetic upper and basal brown clays has not yet been possible. We interpret the sequence as a primary reversed polarity record. This record is carried by the iron sulphide greigate as a chemical remanence acquired during `syn'-depositional reduction of iron via the decomposition of organic material in these anoxic tidal clays. Subsequently, the upper and basl subunits of the clay have been oxidised by permeation of groundwater from the adjacent coarse-grained sediments. Most of the griegite in the oxidised margins of the clay has

  16. Recovery of yttrium from fluorescent powder of cathode ray tube, CRT: Zn removal by sulphide precipitation

    SciTech Connect

    Innocenzi, Valentina; De Michelis, Ida; Ferella, Francesco; Beolchini, Francesca; Kopacek, Bernd

    2013-11-15

    Highlights: • Treatment of fluorescent powder of CRT waste. • Factorial experimental designs to study acid leaching of fluorescent powder and the purification of leach liquors. • Recover of yttrium by precipitation using oxalic acid. • Suitable flowsheet to recover yttrium from fluorescent powder. - Abstract: This work is focused on the recovery of yttrium and zinc from fluorescent powder of cathode ray tube (CRT). Metals are extracted by sulphuric acid in the presence of hydrogen peroxide. Leaching tests are carried out according to a 2{sup 2} full factorial plan and the highest extraction yields for yttrium and zinc equal to 100% are observed under the following conditions: 3 M of sulphuric acid, 10% v/v of H{sub 2}O{sub 2} concentrated solution at 30% v/v, 10% w/w pulp density, 70 °C and 3 h of reaction. Two series of precipitation tests for zinc are carried out: a 2{sup 2} full factorial design and a completely randomized factorial design. In these series the factors investigated are pH of solution during the precipitation and the amount of sodium sulphide added to precipitate zinc sulphide. The data of these tests are used to describe two empirical mathematical models for zinc and yttrium precipitation yields by regression analysis. The highest precipitation yields for zinc are obtained under the following conditions: pH equal to 2–2.5% and 10–12% v/v of Na{sub 2}S concentrated solution at 10% w/v. In these conditions the coprecipitation of yttrium is of 15–20%. Finally further yttrium precipitation experiments by oxalic acid on the residual solutions, after removing of zinc, show that yttrium could be recovered and calcined to obtain the final product as yttrium oxide. The achieved results allow to propose a CRT recycling process based on leaching of fluorescent powder from cathode ray tube and recovery of yttrium oxide after removing of zinc by precipitation. The final recovery of yttrium is 75–80%.

  17. Enhanced protection of PDMS-embedded palladium catalysts by co-embedding of sulphide-scavengers.

    PubMed

    Comandella, Daniele; Ahn, Min Hyung; Kim, Hojeong; Mackenzie, Katrin

    2017-12-01

    For Pd-containing hydrodechlorination catalysts, coating with poly(dimethyl siloxane) (PDMS) was proposed earlier as promising protection scheme against poisoning. The PDMS coating can effectively repel non-permeating poisons (such as SO3(2-)) retaining the hydrodechlorination Pd activity. In the present study, the previously achieved protection efficiency was enhanced by incorporation of sulphide scavengers into the polymer. The embedded scavengers were able to bind permeating non-ionic poisons (such as H2S) during their passage through PDMS prior to Pd contact which ensured an extended catalyst lifetime. Three scavenger types forming non-permeable sulphur species from H2S - alkaline, oxidative or iron-based compounds - were either incorporated into single-layer coats around individual Pd/Al2O3 particles or into a second layer above Pd-containing PDMS films (Pd-PDMS). Hydrodechlorination and hydrogenation were chosen as model reactions, carried out in batch and continuous-flow reactors. Batch tests with all scavenger-containing catalysts showed extended Pd protection compared to scavenger-free catalysts. Solid alkaline compounds (Ca(OH)2, NaOH, CaO) and MnO2 showed the highest instantaneous scavenger efficiencies (retained Pd activity=30-60%), while iron-based catalysts, such as nano zero-valent iron (nZVI) or ferrocene (FeCp2), proved less efficient (1-10%). When stepwise poisoning was applied, the protection efficiency of iron-based and oxidizing compounds was higher in the long term than that of alkaline solids. Long-term experiments in mixed-flow reactors were performed with selected scavengers, revealing the following trend of protection efficiency: CaO2>Ca(OH)2>FeCp2. Under field-simulating conditions using a fixed-bed reactor, the combination of sulphide pre-oxidation in the water phase by H2O2 and local scavenger-enhanced Pd protection was successful. The oxidizing agent H2O2 does not disturb the Pd-catalysed reduction, while the PDMS

  18. 3D stochastic inversion of gravity data of Lalor volcanogenic massive sulphide, Manitoba, Canada

    NASA Astrophysics Data System (ADS)

    Tirdad, Shiva; Bouchedda, Abderrezak; Gloaguen, Erwan; Dupuis, Christian

    2017-04-01

    3D stochastic inversion of gravity data of Lalor volcanogenic massive sulphide The objective of this study is to present an algorithm for 3D stochastic inversion of gravity data, which takes into account the geological model. The obtained model is expected to permit the application of Bayesian SGS approach for metal grade estimation and compare the results with those retrieved using conventional least-squared regularized inversion. The proposed approach includes sets of geological models adjusted to the actual data without any matrix inversion as usually done in conventional approaches. The stochastic inversion seeks the conditional probability density parameters of the measured data and the known constraints of the model, unlike the conventional inversion where a single optimal model is sought. In this study, we propose a stochastic inversion method in which, the geological model of the study area is used as a training image to generate multiple scenarios by implementing multiple point simulation. In an optimization process to obtain a satisfactory match to sets of observed data, different stochastic realizations with the same overall statistical properties are iteratively linearly combined through gradual deformation. Then, we perform forward modeling on these constrained combined models to obtain measured gravity data, assuming the physical properties of each unit in our models are constant. The results are compared by the observed data to have the minimum misfit possible between the measured and observed data in order to validate the initial geological model The methodology is applied to Lalor volcanogenic massive sulphide (VMS) deposit, which is located near Snow Lake, Manitoba, Canada. The deposit is one of the largest metal deposits within Flin Flon Greenstone Belt having 25Mt reserves. There are three mineralization zones in the deposit including zinc zones, gold zones and a gold-copper zone. An analysis of physical rock properties was conducted to

  19. ``Background'' δ34S values of Kupferschiefer sulphides in Poland: pyrite-marcasite nodules

    NASA Astrophysics Data System (ADS)

    Jowett, E. C.; Roth, T.; Rydzewski, A.; Oszczepalski, S.

    1991-04-01

    Regional “background” δ 34S values of pyrite-(marcasite) nodules throughout the Zechstein basin in Poland have been measured to help estimate the proportion of externally derived sulphur in the Kupferschiefer Cu-Ag ores. The δ 34S values of the 17 FeS2 nodules measured range widely, from -25.2 to -51.9%., similar to the previously published -28 to -43%. range in disseminated pyrite in the Kupferschiefer. The wide variation cannot be attributed to pyrite versus marcasite mineralogy, amount of contained chalcopyrite or sphalerite, carbonate versus shale host rock, early versus late formation, percent of included calcite, or to size, shape, or texture. There is also no relation with proximity to the centres of copper mineralization in southwestern Poland where sulphides are typically isotopically heavier. The δ 34S values do, however, vary directly with percent of host-rock fragments included in the nodules. Repeat samples that were washed with acid or hot water show the same wide variation, indicating that contamination by sulphate sulphur in the host rock is not a factor. Neither is organic sulphur because of its small volume. Instead, the sulphur composition may be fundamentally controlled by the formation mechanism of the nodule, whereby 34S-rich sulphide is preferentially concentrated, possibly replacing anhydrite lenses. Alternatively, a network of host rock inclusions might act as a more accessible conduit for later, 34S-rich fluids to infiltrate the nodule and add to earlier, 34S-poor pyrite. In the ore deposits, higher δ 34S values of ore nodules suggest less indigenous sulphur in limestone than shale lithologies. An isotopic temperature of 61 °C from a chalcopyrite-galena pair agrees with other estimates of <105°C. Higher values in ore nodules/veinlets than in adjacent disseminations, and the calculated δ 34Spy value from a pyrite-bornite mixture support the idea that metal-bearing 34S-rich fluids penetrated the Kupfer-schiefer through a network

  20. Long-term effects of sulphide on the enhanced biological removal of phosphorus: The symbiotic role of Thiothrix caldifontis.

    PubMed

    Rubio-Rincón, F J; Welles, L; Lopez-Vazquez, C M; Nierychlo, M; Abbas, B; Geleijnse, M; Nielsen, P H; van Loosdrecht, M C M; Brdjanovic, D

    2017-06-01

    Thiothrix caldifontis was the dominant microorganism (with an estimated bio-volume of 65 ± 3%) in a lab-scale enhanced biological phosphorus removal (EBPR) system containing 100 mg of sulphide per litre in the influent. After a gradual exposure to the presence of sulphide, the EBPR system initially dominated by Candidatus Accumulibacter phosphatis Clade I (98 ± 3% bio-volume) (a known polyphosphate accumulating organism, PAO) became enriched with T. caldifontis. Throughout the different operating conditions studied, practically 100% phosphate removal was always achieved. The gradual increase of the sulphide content in the medium (added to the anaerobic stage of the alternating anaerobic-aerobic sequencing batch reactor) and the adjustment of the aerobic hydraulic retention time played a major role in the enrichment of T. caldifontis. T. caldifontis exhibited a mixotrophic metabolism by storing carbon anaerobically as poly-β-hydroxy-alkanoates (PHA) and generating the required energy through the hydrolysis of polyphosphate. PHA was used in the aerobic period as carbon and energy source for growth, polyphosphate, and glycogen formation. Apparently, extra energy was obtained by the initial accumulation of sulphide as an intracellular sulphur, followed by its gradual oxidation to sulphate. The culture enriched with T. caldifontis was able to store approximately 100 mg P/g VSS. This research suggests that T. caldifontis could behave like PAO with a mixotrophic metabolism for phosphorus removal using an intracellular sulphur pool as energy source. These findings can be of major interest for the biological removal of phosphorus from wastewaters with low organic carbon concentrations containing reduced S-compounds like those (pre-)treated in anaerobic systems or from anaerobic sewers. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.