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

An indirect method for quantitation of cellular zinc content of Timm-stained cerebellar samples by energy dispersive X-ray microanalysis.

PubMed

Farkas, I; Szerdahelyi, P; Kása, P

1988-01-01

The absolute concentration of zinc in the Purkinje cells of the rat cerebellum was determined by means of energy dispersive X-ray microanalysis (EDAX). Gelatine blocks with known zinc concentrations were stained by Timm's sulphide-silver method, and their silver concentrations were measured by EDAX. A linear correlation was found between the zinc and silver concentrations and this linear function was used as a quantitative calibration for evaluation of sulphide-silver staining, after perfusion with sodium-sulphide solution, fixation with glutaraldehyde, cryostat sectioning and staining of cerebellar samples in Timm's reagent.

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.

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

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

PubMed

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

2010-06-01

Hydrogen sulphide (H(2)S) 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 H(2)S in blood and tissues. 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 H(2)S gas inhalation, and levels of available blood sulphide were measured. Levels of dissolved H(2)S/HS(-) were concomitantly measured using an amperometric sensor. 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 microM. Intravenous administration of sodium sulphide solution (2-20 mg x kg(-1) x h(-1)) or inhalation of H(2)S gas (50-400 ppm) elevated reactive sulphide in blood in a dose-dependent manner. Each 1 mg x kg(-1) x h(-1) of sodium sulphide infusion into rats was found to be pharmacokinetically equivalent to approximately 30 ppm of H(2)S gas inhalation. 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 H(2)S gas.

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.

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

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.

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.

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

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.

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.

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

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

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

The study of metal sulphide nanomaterials obtained by chemical bath deposition and hot-injection technique

NASA Astrophysics Data System (ADS)

Maraeva, E. V.; Alexandrova, O. A.; Forostyanaya, N. A.; Levitskiy, V. S.; Mazing, D. S.; Maskaeva, L. N.; Markov, V. Ph; Moshnikov, V. A.; Shupta, A. A.; Spivak, Yu M.; Tulenin, S. S.

2015-11-01

In this study lead sulphide - cadmium sulphide based layers were obtained through chemical deposition of water solutions and cadmium sulphide quantum dots were formed through hot-injection technique. The article discusses the results of surface investigations with the use of atomic force microscopy, Raman spectroscopy and photoluminescence measurements.

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

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

PubMed

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

2014-02-21

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.

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.

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

Osmium mass balance in peridotite and the effects of mantle-derived sulphides on basalt petrogenesis

NASA Astrophysics Data System (ADS)

Harvey, J.; Dale, C. W.; Gannoun, A.; Burton, K. W.

2011-10-01

Analyses of enriched mantle (EM)-basalts, using lithophile element-based isotope systems, have long provided evidence for discrete mantle reservoirs with variable composition. Upon partial melting, the mantle reservoir imparts its isotopic fingerprint upon the partial melt produced. However, it has increasingly been recognised that it may not be simple to delimit these previously well-defined mantle reservoirs; the "mantle zoo" may contain more reservoirs than previously envisaged. Here we demonstrate that a simple model with varying contributions from two populations of compositionally distinct mantle sulphides can readily account for the observed heterogeneities in Os isotope systematics of such basalts without additional mantle reservoirs. Osmium elemental and isotopic analyses of individual sulphide grains separated from spinel lherzolites from Kilbourne Hole, New Mexico, USA demonstrate that two discrete populations of mantle sulphide exist in terms of both Re-Os systematics and textural relationship with co-existing silicates. One population, with a rounded morphology, is preserved in silicate grains and typically possesses high [Os] and low [Re] with unradiogenic, typically sub-chondritic 187Os/ 188Os attributable to long term isolation in a low-Re environment. By contrast, irregular-shaped sulphides, preserved along silicate grain boundaries, possess low [Os], higher [Re] and a wider range of, but generally supra-chondritic 187Os/ 188Os ([Os] typically ⩽ 1-2 ppm, 187Os/ 188Os ⩽ 0.3729; this study). This population is thought to represent metasomatic sulphide. Uncontaminated silicate phases contain negligible Os (<100 ppt) therefore the Os elemental and isotope composition of basalts is dominated by volumetrically insignificant sulphide ([Os] ⩽ 37 ppm; this study). During the early stages of partial melting, supra-chondritic interstitial sulphides are mobilised and incorporated into the melt, adding their radiogenic 187Os/ 188Os signature. Only when

Colored and semitransparent silver nanoparticle layers deposited by spin coating of silver nanoink

NASA Astrophysics Data System (ADS)

Yoon, Hoi Jin; Jo, Yejin; Jeong, Sunho; Lim, Jung Wook; Lee, Seung-Yun

2018-05-01

In this letter, we report on the fabrication and characterization of colored and semitransparent silver nanoparticle layers. A spin coating of silver nanoink is used to deposit silver nanoparticle layers onto substrates. The transmittance and color of the silver nanoparticle layers are significantly dependent on the spin speed and nanoink concentration, owing to variations in the size and distribution of the nanoparticles. Both color variation and efficiency improvement are achieved with the application of silver nanoparticles to semitransparent Si thin-film solar cells, which is associated with the excitation of the dipole or quadruple plasmon modes of the silver nanoparticles.

Lactate has the potential to promote hydrogen sulphide formation in the human colon.

PubMed

Marquet, Perrine; Duncan, Sylvia H; Chassard, Christophe; Bernalier-Donadille, Annick; Flint, Harry J

2009-10-01

High concentrations of sulphide are toxic for the gut epithelium and may contribute to bowel disease. Lactate is a favoured cosubstrate for the sulphate-reducing colonic bacterium Desulfovibrio piger, as shown here by the stimulation of sulphide formation by D. piger DSM749 by lactate in the presence of sulphate. Sulphide formation by D. piger was also stimulated in cocultures with the lactate-producing bacterium Bifidobacterium adolescentis L2-32. Other lactate-utilizing bacteria such as the butyrate-producing species Eubacterium hallii and Anaerostipes caccae are, however, expected to be in competition with the sulphate-reducing bacteria (SRB) for the lactate formed in the human colon. Strains of E. hallii and A. caccae produced 65% and 96% less butyrate from lactate, respectively, in a coculture with D. piger DSM749 than in a pure culture. In triculture experiments involving B. adolescentis L2-32, up to 50% inhibition of butyrate formation by E. hallii and A. caccae was observed in the presence of D. piger DSM749. On the other hand, sulphide formation by D. piger was unaffected by E. hallii or A. caccae in these cocultures and tricultures. These experiments strongly suggest that lactate can stimulate sulphide formation by SRB present in the colon, with possible consequences for conditions such as colitis.

Effect of oxygen dosing point and mixing on the microaerobic removal of hydrogen sulphide in sludge digesters.

PubMed

Díaz, I; Pérez, S I; Ferrero, E M; Fdz-Polanco, M

2011-02-01

Limited oxygen supply to anaerobic sludge digesters to remove hydrogen sulphide from biogas was studied. Micro-oxygenation showed competitive performance to reduce considerably the additional equipment necessary to perform biogas desulphurization. Two pilot-plant digesters with an HRT of ∼ 20 d were micro-oxygenated at a rate of 0.25 NL per L of feed sludge with a removal efficiency higher than 98%. The way of mixing (sludge or biogas recirculation) and the point of oxygen supply (headspace or liquid phase) played an important role on hydrogen sulphide oxidation. While micro-oxygenation with sludge recirculation removed only hydrogen sulphide from the biogas, dissolved sulphide was removed if micro-oxygenation was performed with biogas recirculation. Dosage in the headspace resulted in a more stable operation. The result of the hydrogen sulphide oxidation was mostly elemental sulphur, partially accumulated in the headspace of the digester, where different sulphide-oxidising bacteria were found. Copyright © 2010 Elsevier Ltd. All rights reserved.

Efficient incorporation of silver to improve superconducting fibers

DOEpatents

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.

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

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

Inclusions of Sulphide Immiscible Melts in Primitive Olivine Phenocrysts from Mantle-Derived Magmas; Preliminary Results

NASA Astrophysics Data System (ADS)

Danyushevsky, L.; Ryan, C.; Kamenetsky, V.; Crawford, A.

2001-12-01

Sulphide inclusions have been identified in olivine phenocrysts (and in one case in a spinel phenocryst) in primitive volcanic rocks from mid- ocean ridges, subduction-related island arcs and backarc basins. These inclusions represent droplets of an immiscible sulphide melt and are trapped by olivine crystals growing from silicate melts. Sulphide melt is usually trapped as separate inclusions, however combined inclusions of sulphide and silicate melts have also been observed. Sulphide inclusions have rounded shapes and vary in size from several up to 100 microns in diameter. At room temperature sulphide inclusions consist of several phases. These phases are formed as a result of crystallisation of the sulphide melt after it was trapped. Crystallisation occurs due to decreasing temperature in the magma chamber after trapping and/or when magma ascents from the magma chamber during eruptions. In all studied sulphides three different phases can be identified: a high- Fe, low-Ni, low-Cu phase; a high-Fe, high-Ni, low-Cu phase; and high-Fe, low-Ni, high-Cu phase. Low-Cu phases appear to be monomineralic, whereas the high-Cu phase is usually composed of a fine intergrowth of high- and low-Cu phases, resembling the quench 'spinifex' structure. Fe, Ni and Cu are the major elements in all sulphides studied. The amount of Ni decreases with decreasing forsterite content of the host olivine phenocryst, which is an index of the degree of silicate magma fractionation. Since Ni content of the silicate magma is decreasing during fractionation, this indicates either that the immiscible sulfide melt remains in equilibrium with the silicate melt continuously changing its composition during fractionation, or that the sulfide melt is continuously separated from the silicate melt during fractionation, with later formed droplets having lower Ni content due to the lower Ni content of the evolved, stronger fractionated silicate melt. Trace element contents of the sulfide inclusions have

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.

In-situ XRD and EDS method study on the oxidation behaviour of Ni-Cu sulphide ore.

PubMed

Li, Guangshi; Cheng, Hongwei; Xiong, Xiaolu; Lu, Xionggang; Xu, Cong; Lu, Changyuan; Zou, Xingli; Xu, Qian

2017-06-12

The oxidation mechanism of sulfides is the key issue during the sulphide-metallurgy process. In this study, the phase transformation and element migration were clearly demonstrated by in-situ laboratory-based X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS), respectively. The reaction sequence and a four-step oxidation mechanism were proposed and identified. The elemental distribution demonstrated that at a low temperature, the Fe atoms diffused outward and the Ni/Cu atoms migrated toward the inner core, whereas the opposite diffusion processes were observed at a higher temperature. Importantly, the unique visual presentation of the oxidation behaviour provided by the combination of in-situ XRD and EDS might be useful for optimising the process parameters to improve the Ni/Cu extraction efficiency during Ni-Cu sulphide metallurgy.

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

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.

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.

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

A double Fe-Ti oxide and Fe-sulphide liquid immiscibility in the Itsindro Gabbro Complex, Madagascar

NASA Astrophysics Data System (ADS)

Augé, Thierry; Bailly, Laurent; Roig, Jean-Yves

2017-11-01

The petrology and mineralogy of the Itsindro complex in south-central Madagascar has been investigated through samples obtained from the 320.7 m-deep Lanjanina borehole. The section consists of a 254 m-thick pyroxenite unit with interbedded gabbro layers that overlies a gabbro unit and is itself overlain by a 19 m-thick granite unit. Most of the structures are sub-horizontal. A weak magmatic layering is locally observed but at the scale of the core, the intrusion does not appear to be a layered complex. Pyroxenite and gabbro show a systematic disseminated mineralization consisting of Fe-Ti-P oxides and Fe-(Cu-Ni) sulphides that takes the form of ilmenite-titanomagnetite ± apatite and pyrrhotite ± chalcopyrite ± pentlandite. In the upper zone, from 90 to 72 m, sub-massive centimetre-to decimetre-sized layers of oxides and sulphides comprise a total of 16 m of sub-massive sulphide (the main mineralized zone). In this mineralized zone the oxide/sulphide ratio is close to 1/1. The sulphide is strongly dominated by pyrrhotite, which may locally contain inclusions of molybdenite crystals with the Re sulphide rheniite (ReS2). Oxides are generally euhedral, included in or attached to the Fe-sulphide, and also locally form sub-massive centimetre-sized bands. Apatite as a cumulus phase is ubiquitous. Locally it may account for 30% of the ore-rich samples and some samples consist of apatite-Fe-Ti oxides-Fe-Cu-Ni sulphides with virtually no silicate. Apatite is the main REE carrier but the total REE content remains low (<90 ppm). Mineral compositions and whole rock geochemistry indicate that the rocks are highly differentiated, and in spite of a relatively limited thickness, the differentiation process is observed. Two zones can be distinguished: from the bottom to 162.8 m we see a decrease in the Mg number of olivine and pyroxene, and a drop in TiO2 and Al2O3 for the latter. A reverse trend is then observed within the pyroxenite unit from the 162.8 m level upwards. The

Development and Optimization of Silver Nanoparticle Formulation for Fabrication

DTIC Science & Technology

2015-08-14

Development and Optimization of Silver Nanoparticle Formulation for Fabrication Publication Type: DJournal/ Paper D Book Chapter ~ Tech Report D...leofPublicationorPresentation: Deve l opment and Optimization of Silver Nanoparticle Formulation for Fabrication 3. Author(s): (List authors starting...fabrication process of silver nanoparticl es could improve future silver containing products , which is i mpor tant to l owering toxicity and improving

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.

Distribution Analysis of Sulphide Mineral (Pyrite) Using Induced Polarization Method in Libureng, Bone, South Sulawesi

NASA Astrophysics Data System (ADS)

Altin Massinai, Muhammad; Lantu; Latuconsina, Hidayat; Fawzy Ismullah M, Muhammad

2018-03-01

Sulphide minerals are any member of a group of compounds of sulphur with one or more metals. Some of these sulphide minerals are economically important. This study used induced polarization method to identify distribution and mineralized zone of sulphide mineral (Pyrite), in Libureng, Bone Regency, South Sulawesi. The data processing yielded resistivity value, percent frequency effect (PPE) value, and metal factor (MF) value which were then used to produce 2-D and 3-D section model. Based on the data interpretation, an anomaly linked to pyrite deposits was seen in four trajectories with resistivity value < = 50, PFE = > 3%, and MF > = 150, deposited in hydrothermal alteration zone, sericite zone.

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.

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.

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.

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.

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.

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.

Green synthesis of silver nanoparticles aimed at improving theranostics

NASA Astrophysics Data System (ADS)

Vedelago, José; Gomez, Cesar G.; Valente, Mauro; Mattea, Facundo

2018-05-01

Nowadays, the combination of diagnosis and therapy, known as theranostics, is one of the keys for an optimal treatment for cancer diseases. Theranostics can be significantly improved by incorporating metallic nanoparticles that are specifically delivered and accumulated in cancerous tissue. In this context, precise knowledge about dosimetric effects in nanoparticle-infused tissues as well as the detection and processing of emerging radiation are extremely important issues. In the last years the first studies on theranostic nanomaterials in gel dosimetry have been presented but there is still a broad field of study to explore. Most of gel dosimetric materials are extremely sensible to modifications in their composition, the addition of enhancers, metallic or inorganic charges can alter their stability and dosimetric properties; therefore, thorough studies must be made before the incorporation of any type of modifier. In this work, the synthesis of metallic nanoparticles suitable for gel dosimetry for x-ray applications is presented. A green synthesis process of silver nanoparticles coated with porcine skin gelatin by thermal reduction of silver nitrate is presented. Nanoparticles were obtained and purified for their application in gel dosimetry. Also, nanoparticles size distribution, reaction yield and the preliminar application as theranostic agents were tested in Fricke gel dosimetry in the keV range. The obtained nanoparticles were successfully used in theranostic applications acting as fluorescent agents and dose enhancers in X-ray beam irradiation simultaneously.

New Capabilities With Dry Silver Recording Materials

NASA Astrophysics Data System (ADS)

Morgan, David A.

1987-04-01

Dry Silver technology was discovered at 3M and introduced into various imaging applications in the mid-sixties. In the early 1980's, quality films and papers with extended spectral responses, greater dynamic ranges, and improved sensitivity and edge acuity were introduced into sophisticated imaging systems. These products also have improved shelf life at elevated storage temperatures, and improved print stability. At the present time, 3M is developing a full-color dry silver product. This product has the same rapid-access, easy-to-use characteristics as the black and white dry silver recording materials. It has high resolution, long gray scale, and adequate sensitivity for CRT's and other electronically addressable exposure devices. The product can be processed in the same processors used for the black and white dry silver products.

Surfactant free nickel sulphide nanoparticles for high capacitance supercapacitors

NASA Astrophysics Data System (ADS)

Nandhini, S.; Muralidharan, G.

2018-04-01

The surfactant free nickel sulphide nanoparticles were synthesized via facile hydrothermal method towards supercapacitor applications. The formation of crystalline spherical nanoparticles was confirmed through structural and morphological studies. Electrochemical behaviour of the electrode was analyzed using cyclic voltammetry (CV), galvanostatic charge-discharge studies (GCD) and electrochemical impedance spectroscopy (EIS). The CV studies imply that specific capacitance of the electrode arises from a combination of surface adsorption and Faradic reaction. The NiS electrode delivered a specific capacitance of about 529 F g-1 at a current density of 2 A g-1 (GCD measurements). A profitable charge transfer resistance of 0.5 Ω was obtained from EIS. The 100 % of capacity retention even after 2000 repeated charge-discharge cycles could be observed in 2 M KOH electrolyte at a much larger rate of 30 A g-1. The experimental results suggest that nickel sulphide is a potential candidate for supercapacitor applications.

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.

Silver distribution and release from an antimicrobial denture base resin containing silver colloidal nanoparticles.

PubMed

Monteiro, Douglas Roberto; Gorup, Luiz Fernando; Takamiya, Aline Satie; de Camargo, Emerson Rodrigues; Filho, Adhemar Colla Ruvolo; Barbosa, Debora Barros

2012-01-01

The aim of this study was to evaluate a denture base resin containing silver colloidal nanoparticles through morphological analysis to check the distribution and dispersion of these particles in the polymer and by testing the silver release in deionized water at different time periods. A Lucitone 550 denture resin was used, and silver nanoparticles were synthesized by reduction of silver nitrate with sodium citrate. The acrylic resin was prepared in accordance with the manufacturers' instructions, and silver nanoparticle suspension was added to the acrylic resin monomer in different concentrations (0.05, 0.5, and 5 vol% silver colloidal). Controls devoid of silver nanoparticles were included. The specimens were stored in deionized water at 37°C for 7, 15, 30, 60, and 120 days, and each solution was analyzed using atomic absorption spectroscopy. Silver was not detected in deionized water regardless of the silver nanoparticles added to the resin and of the storage period. Micrographs showed that with lower concentrations, the distribution of silver nanoparticles was reduced, whereas their dispersion was improved in the polymer. Moreover, after 120 days of storage, nanoparticles were mainly located on the surface of the nanocomposite specimens. Incorporation of silver nanoparticles in the acrylic resin was evidenced. Moreover, silver was not detected by the detection limit of the atomic absorption spectrophotometer used in this study, even after 120 days of storage in deionized water. Silver nanoparticles are incorporated in the PMMA denture resin to attain an effective antimicrobial material to help control common infections involving oral mucosal tissues in complete denture wearers. © 2011 by the American College of Prosthodontists.

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.

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. Crown Copyright © 2014. Published by Elsevier Ireland Ltd. All rights reserved.

Assessment of Potential Health Hazards During Emission of Hydrogen Sulphide from the Mine Exploiting Copper Ore Deposit - Case Study.

PubMed

Kupczewska-Dobecka, Małgorzata; Czerczak, Sławomir; Gromiec, Jan P; Konieczko, Katarzyna

2015-06-01

The aim of this study was to determine hydrogen sulphide concentration emitted from the mine extracting copper ore, to evaluate potential adverse health effects to the population living in four selected villages surrounding the exhaust shaft. Maximum measured concentration of hydrogen sulphide in the emitter is 286 µg/m³. Maximum emission calculated from the results of determinations of concentrations in the emitter is 0.44 kg/h. In selected villages hydrogen sulphide at concentrations exceeding 4 µg/m³ was not detected in any of the 5-hour air samples. In all locations, the estimated maximum 1-hour concentrations of hydrogen sulphide were below 1 µg/m³, and the estimated mean annual concentrations were below 0.53 µg/m³. Any risk to the health of people in the selected area is not expected. As indicated by the available data on the threshold odour, the estimated concentrations of hydrogen sulphide may be sensed by humans. Copyright© by the National Institute of Public Health, Prague 2015.

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. Copyright © 2016 Elsevier Inc. All rights reserved.

The influence of reaction time on hydrogen sulphide removal from air by means of Fe(III)-EDTA/Fiban catalysts

NASA Astrophysics Data System (ADS)

Wasag, H.; Cel, W.; Chomczynska, M.; Kujawska, J.

2018-05-01

The paper deals with a new method of hydrogen sulphide removal from air by its filtration and selective catalytic oxidation with the use of fibrous carriers of Fe(III)-EDTA complex. The basis of these filtering materials includes fibrous ion exchangers with the complex immobilized on their functional groups. It has been established that the degree of catalytic hydrogen sulphide decomposition depends on the reaction time. Thus, the required degree of hydrogen sulphide removal from air could be easily controlled by applying appropriate thickness of the filtering layer under a given filtering velocity. It allows applying very thin filtering layers of the Fe(III)-EDTA/Fiban AK-22 or Fiban A-6 catalysts. The obtained results of the research confirm the applicability of these materials for deep air purification from hydrogen sulphide.

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.

Optimization of silver-dielectric-silver nanoshell for sensing applications

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

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 sensitivitymore » of silver-dielectric-silver nanoshell.« less

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

Silver-silver sulfate reference electrodes for use in lead-acid batteries

NASA Astrophysics Data System (ADS)

Ruetschi, Paul

Electrochemical properties of silver-silver sulfate reference electrodes for lead-acid batteries are described, and the following possible applications discussed: Determination of individual capacities of positive and negative plates. Monitoring individual electrode behavior during deep discharge and cell reversal. Optimization charge or discharge parameters, by controlling the current such that pre-determined limits of positive or negative half-cell potential are respected. Observation of acid concentration differences, for example due to acid stratification, by measuring diffusion potentials (concentration-cell voltages). Detection of defective cells, and defective plate sets, in a string of cells, at the end of their service life. Silver-silver sulfate reference electrodes, permanently installed in lead-acid cells, may be a means to improve battery management, and therewith to improve reliability and service life. In vented batteries, reference electrodes may be used to limit positive plate polarization during charge, or float-charge. Limiting the positive half-cell potential to an upper, pre-set value would permit to keep anodic corrosion as low as possible. During cycling, discharge could be terminated when the half-cell potential of the positive electrode has dropped to a pre-set limit. This would prevent excessive discharge of the positive electrodes, which could result in an improvement of cycle life. In valve-regulated batteries, reference electrodes may be used to adjust float-charge conditions such as to assure sufficient cathodic polarization of the negative electrodes, in order to avoid sulfation. The use of such reference electrodes could be beneficial particularly in multi-cell batteries, with overall voltages above 12 V, operated in a partial-state-of-charge.

Evaluation on the Presence of Nano Silver Particle in Improving a Conventional Water-based Drilling Fluid

NASA Astrophysics Data System (ADS)

Husin, H.; Ahmad, N.; Jamil, N.; Chyuan, O. H.; Roslan, A.

2018-05-01

Worldwide demand in oil and gas energy consumption has been driving many of oil and gas companies to explore new oil and gas resource field in an ultra-deep water environment. As deeper well is drilled, more problems and challenges are expected. The successful of drilling operation is highly dependent on properties of drilling fluids. As a way to operate drilling in challenging and extreme surroundings, nanotechnology with their unique properties is employed. Due to unique physicochemical, electrical, thermal, hydrodynamic properties and exceptional interaction potential of nanomaterials, nanoparticles are considered to be the most promising material of choice for smart fluid design for oil and gas field application. Throughout this paper, the effect of nano silver particle in improving a conventional water based drilling fluid was evaluated. Results showed that nano silver gave a significant improvement to the conventional water based drilling fluid in terms of its rheological properties and filtration test performance.

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.

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.

Deliberately Designed Atomic-Level Silver-Containing Interface Results in Improved Rate Capability and Utilization of Silver Hollandite for Lithium-Ion Storage

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

Smith, Paul F.; Brady, Alexander B.; Lee, Seung-Yong

α-MnO 2-structured materials are generally classified as semiconductors, thus we present a strategy to increase electrochemical utilization through design of a conductive material interface. Surface treatment of silver hollandite (Ag xMn 8O 16) with Ag + (Ag 2O) provides significant benefit to the resultant electrochemistry, including a decreased charge transfer resistance, and a 2-fold increase in deliverable energy density at high rate. The improved function of this designed interface relative to conventional electrode fabrication strategies is further highlighted.

Deliberately Designed Atomic-Level Silver-Containing Interface Results in Improved Rate Capability and Utilization of Silver Hollandite for Lithium-Ion Storage

DOE PAGES

Smith, Paul F.; Brady, Alexander B.; Lee, Seung-Yong; ...

2017-12-11

α-MnO 2-structured materials are generally classified as semiconductors, thus we present a strategy to increase electrochemical utilization through design of a conductive material interface. Surface treatment of silver hollandite (Ag xMn 8O 16) with Ag + (Ag 2O) provides significant benefit to the resultant electrochemistry, including a decreased charge transfer resistance, and a 2-fold increase in deliverable energy density at high rate. The improved function of this designed interface relative to conventional electrode fabrication strategies is further highlighted.

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.

Lead sulphide: Low cost, abundant thermoelectrics

NASA Astrophysics Data System (ADS)

Ahmad, Sajid; Singh, Ajay; Bhattacharya, Shovit; Basu, Ranita; Bhatt, Ranu; Bohra, Anil; Muthe, K. P.; Gadkari, S. C.

2018-04-01

Lead and sulphur are the most abundant and low cost materials on the earth's crust, lead chalcogenide (S, Se and Te) materials have got best applications in thermoelectric power generations. Among the chalcogenides, selenium and tellurium are costlier and are more toxic material than sulphur. [1][2] Decreasing the thermal conductivity has been proven to be the easiest approach to improve the thermoelectric performance of a material. In the present work, the lead sulphide (PbS) and SrxPb(1-x)S composite materials were synthesized and investigated. Addition of 0.4 and 0.8 moles of Sr atoms into the PbS lattice has appreciably reduced the thermal conductivity from 2.2 W/mK to 0.43 W/mK for Sr0.4Pb0.6S composition. Temperature (T) dependence of thermoelectric (TE) properties PbS and and SrxPb(1-x)S nanocomposite material has been studied with in the temperature range of 300 K to 700 K. It is observed that there is reduction in the thermal conductivity of PbS alloy on addition of Sr that is mainly attributed to the scattering centres of Sr in the PbS matrix also the presence of the Sr also plays a role in the refinement of the PbS matrix.

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%. Copyright © 2015 Elsevier B.V. All rights reserved.

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.…

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.

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.

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.

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.

Influences of Silver and Zinc Contents in the Stannite Ag2ZnSnS4 Photoelectrodes on Their Photoelectrochemical Performances in the Salt-Water Solution.

PubMed

Cheng, Kong-Wei; Hong, Shu-Wei

2018-06-13

The multicomponent metal sulphide (stannite Ag2ZnSnS4) samples were grown onto the conductive metal oxide coated glass substrates by using the sulfurization of co-sputtering silver-zinc-tin precursors. Several [Ag]/[Zn+Sn] and [Zn]/[Sn] ratios were set in the metal precursors to investigate their influences on the crystal phases, microstructures and physical properties of the stannite Ag2ZnSnS4 samples. The results of the crystal phases and compositions of samples showed that the stannite Ag2ZnSnS4 phase can be obtained using the two-step sulfurization process, which maintained the silver-zinc-tin precursors at 160C for 1 hour and then kept them at 450oC for 30 minutes under sulfur/nitrogen atmosphere. N-type stannite Ag2ZnSnS4 samples with the carrier concentrations of 5.54x1012 - 9.11x1012 cm-3 can be obtained. High resistivities of Ag2ZnSnS4 samples were observed due to the low values of carrier concentration. Increasing the silver content in the sample can improve its PEC performance due to the decrease in the sample resistivity. The ratio of [Ag]/[Zn+Sn] kept at 0.8 and ratio of [Zn]/[Sn] set at 0.90 in the stannite Ag2ZnSnS4 sample had the highest photoelectrochemical performance of 0.31 mA.cm-2 with the potential set at 1.23 V vs. relative hydrogen electrode applied on the sample because of it having the lowest charge transfer resistance in electrolyte.

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.

The electrodeposition of silver composites using deep eutectic solvents.

PubMed

Abbott, Andrew P; El Ttaib, Khalid; Frisch, Gero; Ryder, Karl S; Weston, David

2012-02-21

Silver is an important metal for electronic connectors, however, it is extremely soft and wear can be a significant issue. This paper describes how improved wear resistant silver coatings can be obtained from the electrolytic deposition of silver from a solution of AgCl in an ethylene glycol/choline chloride based Deep Eutectic Solvent. An up to 10-fold decrease in the wear volume is observed by the incorporation of SiC or Al(2)O(3) particles. The work also addresses the fundamental aspect of speciation of silver chloride in solution using EXAFS to probe solution structure. The size but not the nature of the composite particles is seen to change the morphology and grain size of the silver deposit. Grain sizes are shown to be consistent with previous nucleation studies. The addition of LiF is found to significantly affect the deposit morphology and improve wear resistance.

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

Status of SAFT silver hydrogen cell development

NASA Technical Reports Server (NTRS)

Goualard, B. J.

1983-01-01

Nickel-hydrogen cells appear to be an improvement over the nickel-cadmium in applications requiring longer lifetime and reduced weight. An even more efficient couple, the silver-hydrogen couple, is also considered. After a theoretical study first performed by the Battelle Institute of Geneva under ESA (European Space Agency) contract, SAFT has undertaken more detailed analyses of the silver-hydrogen degradation mechanisms. ESA and the French Department of Defense contracted with SAFT for a full-development program of the silver-hydrogen technology.

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. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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.

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

2017-05-01

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.

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.

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.

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.…

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.

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

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.

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.

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 Ag_xMnO_y, 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 Ag_xMnO_y 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.

Comparative study on the passivation layers of copper sulphide minerals during bioleaching

NASA Astrophysics Data System (ADS)

Fu, Kai-bin; Lin, Hai; Mo, Xiao-lan; Wang, Han; Wen, Hong-wei; Wen, Zi-long

2012-10-01

The bioleaching of copper sulphide minerals was investigated by using A. ferrooxidans ATF6. The result shows the preferential order of the minerals bioleaching as djurleite>bornite>pyritic chalcopyrite>covellite>porphyry chalcopyrite. The residues were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is indicated that jarosite may not be responsible for hindered dissolution. The elemental sulfur layer on the surface of pyritic chalcopyrite residues is cracked. The compact surface layer of porphyry chalcopyrite may strongly hinder copper extraction. X-ray photoelectron spectroscopy (XPS) further confirms that the passivation layers of covellite, pyritic chalcopyrite, and porphyry chalcopyrite are copper-depleted sulphide Cu4S11, S8, and copper-rich iron-deficient polysulphide Cu4Fe2S9, respectively. The ability of these passivation layers was found as Cu4Fe2S9>Cu4S11>S8>jarosite.

Physical chemistry mechanisms of CDR system in sulphide mineral flotation

NASA Astrophysics Data System (ADS)

Pak, To-Hyon; Sun, Ti-Chang; Kou, Jue; Huang, Chol-Ryong

2012-03-01

The flotation tests, zeta potential measurements, and Fourier transform infrared spectroscopy (FTIR) analysis on galena, sphalerite, and pyrite were studied in a collecting-depressing-reactivating (CDR) system. In this system, sulphide minerals were first collected and activated by the collector, and then depressed strongly by Ca(OH)2 in a strong alkaline solution. Finally, they were reactivated by H2SO4. The flotation tests of pure minerals showed that in the Ca(OH)2 depressing process sulphide minerals had similar flotation characteristics because they had already been influenced by the collector. Hence, the flotability differences between them were reduced. However, in the H2SO4 reactivating process considerable differences in the flotability between galena and sphalerite/pyrite were produced. That is to say, galena was relatively easy to be reactivated by H2SO4, but sphalerite and pyrite were not reactivated at pH > 11. The zeta potentials of sulfide minerals measured by the Zeta Plus presented irreversible characteristics on the change of pH values. The results of the FTIR spectra analysis indicated that the collectors already adsorbed on the mineral surface were removed partially by Ca(OH)2.

Low hydrogen sulphide and chronic kidney disease: a dangerous liaison.

PubMed

Perna, Alessandra F; Ingrosso, Diego

2012-02-01

Hydrogen sulphide, H(2)S, is a gaseous compound involved in a number of biological responses, e.g. blood pressure, vascular function and energy metabolism. In particular, H(2)S is able to lower blood pressure, protect from injury in models of ischaemia-reperfusion and induce a hypometabolic state. In chronic kidney disease (CKD), low plasma hydrogen sulphide levels have been established in humans and in animal models. The enzymes involved in its production are cystathionine β-synthase, cystathionine γ-lyase and 3-mercaptopyruvate sulphurtransferase. The mechanisms for H(2)S decrease in CKD are related to the reduced gene expression (demonstrated in uraemic patient blood cells) and decreased protein levels (in tissues such as liver, kidney, brain in a CKD rat model). In the present Nephrol Dial Transplant issue, in fact, Aminzadeh and Vaziri document that the alterations in this pathway complicate the uraemic state and are linked to CKD progression. They furnish a time frame in CKD and record enzyme tissue distribution. It remains to be established if low H(2)S is causally linked to CKD progression and if interventions aimed to restore the status quo ante are able to modify this picture.

Reinforced silver-embedded silica matrix from the cheap silica source for the controlled release of silver ions

NASA Astrophysics Data System (ADS)

Hilonga, A.; Kim, J. K.; Sarawade, P. B.; Kim, H. T.

2009-07-01

In this study, a reinforced silver-embedded silica matrix was designed by utilizing the interaction between the [AlO 4] - tetrahedral and the Ag + in sol-gel process using sodium silicate as a silica precursor. The Ag + mole ratio in each sample was significantly varied to examine the influence of silver concentration on the properties of the final product. Aluminium ions were added to reinforce and improve the chemical durability of silver-embedded silica. A templated sample at Al/Ag = 1 atomic ratio was also synthesized to attempt a possibility of controlling porosity of the final product. Also, a sample neither embedded with silver nor templated was synthesized and characterized to serve as reference. The material at Al/Ag = 1 was found to have a desirable properties, compared to its counterparts, before and even after calcination up to 1000 °C. The results demonstrate that materials with desirable properties can be obtained by this unprecedented method while utilizing sodium silicate, which is relatively cheap, as a silica precursor. This may significantly boost the industrial production of the silver-embedded silicas for various applications.

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. Copyright © 2013 Elsevier Inc. All rights reserved.

Silver deposition and tissue staining associated with wound dressings containing silver.

PubMed

Walker, Michael; Cochrane, Christine A; Bowler, Philip G; Parsons, David; Bradshaw, Peter

2006-01-01

Argyria is the general term used to denote a clinical condition in which excessive administration and deposition of silver causes a permanent irreversible gray-blue discoloration of the skin or mucous membranes. The amount of discoloration usually depends on the route of silver delivery (ie, oral or topical administration) along with the body's ability to absorb and excrete the administered silver compound. Argyria is accepted as a rare dermatosis but once silver particles are deposited, they remain immobile and may accumulate during the aging process. Topical application of silver salts (eg, silver nitrate solution) may lead to transient skin staining. To investigate their potential to cause skin staining, two silver-containing dressings (Hydrofiber and nanocrystalline) were applied to human skin samples taken from electively amputated lower limbs. The potential for skin discoloration was assayed using atomic absorption spectroscopy. When the dressings were hydrated with water, a significantly higher amount of silver was released from the nanocrystalline dressing compared to the Hydrofiber dressing (P <0.005), which resulted in approximately 30 times more silver deposition. In contrast, when saline was used as the hydration medium, the release rates were low for both dressings and not significantly different (silver deposition was minimal). Controlling the amount of silver released from silver-containing dressings should help reduce excessive deposition of silver into wound tissue and minimize skin staining.

Cobalt and precious metals in sulphides of peridotite xenoliths and inferences concerning their distribution according to geodynamic environment: A case study from the Scottish lithospheric mantle

NASA Astrophysics Data System (ADS)

Hughes, Hannah S. R.; McDonald, Iain; Faithfull, John W.; Upton, Brian G. J.; Loocke, Matthew

2016-01-01

Abundances of precious metals and cobalt in the lithospheric mantle are typically obtained by bulk geochemical analyses of mantle xenoliths. These elements are strongly chalcophile and the mineralogy, texture and trace element composition of sulphide phases in such samples must be considered. In this study we assess the mineralogy, textures and trace element compositions of sulphides in spinel lherzolites from four Scottish lithospheric terranes, which provide an ideal testing ground to examine the variability of sulphides and their precious metal endowments according to terrane age and geodynamic environment. Specifically we test differences in sulphide composition from Archaean-Palaeoproterozoic cratonic sub-continental lithospheric mantle (SCLM) in northern terranes vs. Palaeozoic lithospheric mantle in southern terranes, as divided by the Great Glen Fault (GGF). Cobalt is consistently elevated in sulphides from Palaeozoic terranes (south of the GGF) with Co concentrations > 2.9 wt.% and Co/Ni ratios > 0.048 (chondrite). In contrast, sulphides from Archaean cratonic terranes (north of the GGF) have low abundances of Co (< 3600 ppm) and low Co/Ni ratios (< 0.030). The causes for Co enrichment remain unclear, but we highlight that globally significant Co mineralisation is associated with ophiolites (e.g., Bou Azzer, Morocco and Outokumpu, Finland) or in oceanic peridotite-floored settings at slow-spreading ridges. Thus we suggest an oceanic affinity for the Co enrichment in the southern terranes of Scotland, likely directly related to the subduction of Co-enriched oceanic crust during the Caledonian Orogeny. Further, we identify a distinction between Pt/Pd ratio across the GGF, such that sulphides in the cratonic SCLM have Pt/Pd ≥ chondrite whilst Palaeozoic sulphides have Pt/Pd < chondrite. We observe that Pt-rich sulphides with discrete Pt-minerals (e.g., PtS) are associated with carbonate and phosphates in two xenolith suites north of the GGF. This three

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.

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. Copyright © 2015 Elsevier B.V. All rights reserved.

New sulphiding method for steel and cast iron parts

NASA Astrophysics Data System (ADS)

Tarelnyk, V.; Martsynkovskyy, V.; Gaponova, O.; Konoplianchenko, Ie; Dovzyk, M.; Tarelnyk, N.; Gorovoy, S.

2017-08-01

A new method for sulphiding steel and cast iron part surfaces by electroerosion alloying (EEA) with the use of a special electrode is proposed, which method is characterized in that while manufacturing the electrode, on its surface, in any known manner (punching, threading, pulling, etc.), there is formed at least a recess to be filled with sulfur as a consistent material, and then there is produced EEA by the obtained electrode without waiting for the consistent material to become dried.

An improved silver staining procedure for schizodeme analysis in polyacrylamide gradient gels.

PubMed

Gonçalves, A M; Nehme, N S; Morel, C M

1990-01-01

A simple protocol is described for the silver staining of polyacrylamide gradient gels used for the separation of restriction fragments of kinetoplast DNA [schizodeme analysis of trypanosomatids (Morel et al., 1980)]. The method overcomes the problems of non-uniform staining and strong background color which are frequently encountered when conventional protocols for silver staining of linear gels are applied to gradient gels. The method described has proven to be of general applicability for DNA, RNA and protein separations in gradient gels.

Quantitative examination of carbide and sulphide precipitates in chemically complex steels processed by direct strip casting

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

Dorin, Thomas, E-mail: thomas.dorin@deakin.edu.au; Wood, Kathleen; Taylor, Adam

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 SANSmore » 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.« less

Catalytic combustion of methane over commercial catalysts in presence of ammonia and hydrogen sulphide.

PubMed

Hurtado, Paloma; Ordóñez, Salvador; Vega, Aurelio; Díez, Fernando V

2004-05-01

The performance of different commercially available catalysts (supported Pd, Pt, Rh, bimetallic Pd-Pt, and Cr-Cu-Ti oxide catalyst) for the oxidation of methane, alone and in presence of ammonia and hydrogen sulphide is studied in this work. Catalysts performance was evaluated both in terms of activity and resistance to poisoning. The main conclusions are that supported Pd and Rh, present the highest activities for methane oxidation, both alone and in presence of ammonia, whereas they are severely poisoned in presence of H2S. Pt and Cr-Cu-Ti are less active but more sulphur resistant, but their activity is lower than the residual activity of sulphur-deactivated Pd and Rh catalysts. The Pd-Pt catalyst exhibits low activity and it is quickly deactivated in presence of hydrogen sulphide.

Silver nanoparticles as optical clearing agent enhancers to improve caries diagnostic by optical coherence tomography

NASA Astrophysics Data System (ADS)

Carneiro, Vanda S. M.; Mota, Cláudia C. B. O.; Souza, Alex F.; da Silva, Evair J.; da Silva, Andrea F.; Gerbi, Marleny E. M. M.; Gomes, Anderson S. L.

2018-02-01

The use of silver nanoparticles as optical clearing agent (OCA) enhancers to improve caries diagnostic by optical coherence tomography (OCT) is demonstrated here. Five molars with no evident cavitation were selected. The OCAs were based on aqueous solution of silver nanoparticles (AgNP, 1.18x 1014 particles/mL, ø ≈ 10nm) and its dilution at 10% in glycerol. Teeth were placed on a platform with a micrometric screw, and after applying the OCAs, they were scanned with a Callisto SD-OCT system operating ate 930nm central wavelength. The occlusal surfaces were scanned by OCT, capturing crosssectional images with 8 mm transversal scanning, generating numerical matrices (2000x512). The OCT images had their transverse dimension preserved. AgNP-OCAs promoted image stretching due to the modification in the light optical path caused by AgNP-OCAs refractive indices close to that of the enamel. AgNP-OCAs evidenced the enamel birefringence and highlighted initial demineralization areas, that presented defined margins with higher contrast between sound and demineralized regions, with higher OCT signal intensity in those areas.

Exposure-related health effects of silver and silver compounds: a review.

PubMed

Drake, Pamela L; Hazelwood, Kyle J

2005-10-01

A critical review of studies examining exposures to the various forms of silver was conducted to determine if some silver species are more toxic than others. The impetus behind conducting this review is that several occupational exposure limits and guidelines exist for silver, but the values for each depend on the form of silver as well as the individual agency making the recommendations. For instance, the American Conference of Governmental Industrial Hygienists has established separate threshold limit values for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). On the other hand, the permissible exposure limit (PEL) recommended by the Occupational Safety and Health Administration and the Mine Safety and Health Administration and the recommended exposure limit set by the National Institute for Occupational Safety and Health is 0.01 mg/m3 for all forms of silver. The adverse effects of chronic exposure to silver are a permanent bluish-gray discoloration of the skin (argyria) or eyes (argyrosis). Most studies discuss cases of argyria and argyrosis that have resulted primarily from exposure to the soluble forms of silver. Besides argyria and argyrosis, exposure to soluble silver compounds may produce other toxic effects, including liver and kidney damage, irritation of the eyes, skin, respiratory, and intestinal tract, and changes in blood cells. Metallic silver appears to pose minimal risk to health. The current occupational exposure limits do not reflect the apparent difference in toxicities between soluble and metallic silver; thus, many researchers have recommended that separate PELs be established.

Fabrication and testing of silver-hydrogen cells

NASA Technical Reports Server (NTRS)

Debicarri, D. J.; Charkey, A.

1978-01-01

Silver electrodes containing various additives were fabricated and tested in single electrode cells in order to improve the electrochemical utilization of sintered silver cathodes in Ag-H2 aerospace batteries. A standard stack arrangement was used which featured a NASA-developed organic-inorganic separator. All cells were cycled in a regime designed to remove 75% of the cells nominal capacity based on 3.3 gms/AHr Ag utilization. In cases where performance degradation was observed, the main feature mode appeared to be corrosion of either the expanded silver current collector or the connection between the silver electrode and the electrode tab. Promising silver electrodes from single electrode studies were used in the construction of 35 AHr Ag-H2 cells. Two such cells were constructed and installed in heavy walled pressure vessels for testing. Based on the data obtained from all cells tested during the program, four lightweight 35 AHr cells were fabricated. During acceptance testing these cells yielded an average gravimetric energy density of 30 WHr/1b.

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.

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.

Engineered Escherichia coli Silver-Binding Periplasmic Protein That Promotes Silver Tolerance

PubMed Central

Hall Sedlak, Ruth; Hnilova, Marketa; Grosh, Carolynn; Fong, Hanson; Baneyx, Francois; Schwartz, Dan; Sarikaya, Mehmet; Tamerler, Candan

2012-01-01

Silver toxicity is a problem that microorganisms face in medical and environmental settings. Through exposure to silver compounds, some bacteria have adapted to growth in high concentrations of silver ions. Such adapted microbes may be dangerous as pathogens but, alternatively, could be potentially useful in nanomaterial-manufacturing applications. While naturally adapted isolates typically utilize efflux pumps to achieve metal resistance, we have engineered a silver-tolerant Escherichia coli strain by the use of a simple silver-binding peptide motif. A silver-binding peptide, AgBP2, was identified from a combinatorial display library and fused to the C terminus of the E. coli maltose-binding protein (MBP) to yield a silver-binding protein exhibiting nanomolar affinity for the metal. Growth experiments performed in the presence of silver nitrate showed that cells secreting MBP-AgBP2 into the periplasm exhibited silver tolerance in a batch culture, while those expressing a cytoplasmic version of the fusion protein or MBP alone did not. Transmission electron microscopy analysis of silver-tolerant cells revealed the presence of electron-dense silver nanoparticles. This is the first report of a specifically engineered metal-binding peptide exhibiting a strong in vivo phenotype, pointing toward a novel ability to manipulate bacterial interactions with heavy metals by the use of short and simple peptide motifs. Engineered metal-ion-tolerant microorganisms such as this E. coli strain could potentially be used in applications ranging from remediation to interrogation of biomolecule-metal interactions in vivo. PMID:22286990

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.

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.

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.

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.

Towards a volcanic-structural balance: relative importance of volcanism, folding, and remobilisation of nickel sulphides at the Perseverance Ni-Cu-(PGE) deposit, Western Australia

NASA Astrophysics Data System (ADS)

Duuring, Paul; Bleeker, Wouter; Beresford, Steve W.; Hayward, Nicholas

2010-03-01

Perseverance is a world-class, komatiite-hosted nickel sulphide deposit situated in the well-endowed Leinster nickel camp of the Agnew-Wiluna greenstone belt, Western Australia. The mine stratigraphy at Perseverance trends north-northwest (NNW), dips steeply to the west, and is overturned. Stratigraphic footwall units lie along the western margin of the Perseverance Ultramafic Complex (PUC). The PUC comprises a basal nickel sulphide-bearing orthocumulate- to mesocumulate-textured komatiite that is overlain by a thicker, nickel sulphide-poor, dunite lens. Hanging wall rocks include rhyodacite that is texturally and compositionally similar to footwall volcanic rocks. These rocks separate the PUC from a second sequence of nickeliferous, E-facing, spinifex-textured komatiite units (i.e. the East Perseverance komatiite). Past workers argue for a conformable stratigraphic contact between the PUC and the East Perseverance komatiite and conclude that the PUC is extrusive. This study, however, clearly demonstrates that these komatiite sequences are discordant, implying that the PUC may have intruded rhyodacite country rock as a sill with subsequent structural juxtaposition against the East Perseverance komatiite. Early N-S shortening associated with the regional DI deformation event (corresponding to the local DP1 to DP3 events at Perseverance) resulted in the heterogeneous partitioning of strain along the margins of the competent dunite. A mylonite developed in the more ductile footwall rocks along the footwall margin of the PUC, while isoclinal F3 folds, such as the Hanging wall limb and Felsic Nose folds, formed in low-mean stress domains along the fringes of the elongated dunite lens. Strata-bound massive and disseminated nickel sulphides were passively fold thickened in hinge areas of isoclinal folds, whereas basal massive sulphides lubricated fold limbs and promoted thrust movement along shallowly dipping lithological contacts. Massive sulphides were physically

Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate

PubMed Central

2011-01-01

Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP). The AgNPs remained stable throughout the duration of the 28-day oral toxicity study in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of AgNPs. Besides the intestinal system, the largest silver concentrations were detected in the liver and kidneys. Silver was also found in the lungs and brain. Autometallographic (AMG) staining revealed a similar cellular localization of silver in ileum, liver, and kidney tissue in rats exposed to AgNPs or AgAc. Using transmission electron microscopy (TEM), nanosized granules were detected in the ileum of animals exposed to AgNPs or AgAc and were mainly located in the basal lamina of the ileal epithelium and in lysosomes of macrophages within the lamina propria. Using energy dispersive x-ray spectroscopy it was shown that the granules in lysosomes consisted of silver, selenium, and sulfur for both AgNP and AgAc exposed rats. The diameter of the deposited granules was in the same size range as that of the administered AgNPs. No silver granules were detected by TEM in the liver. Conclusions The results of the present study demonstrate that the organ distribution of silver was similar when AgNPs or AgAc were administered orally to rats. The presence of silver granules containing

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…

Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.

PubMed

Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

2013-05-31

Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 Ω sq⁻¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology.

Electrically Conductive Silver Paste Obtained by Use of Silver Neodecanoate as Precursor

NASA Astrophysics Data System (ADS)

Shen, Longguang; Liu, Jianguo; Zeng, Xiaoyan; Ren, Zhao

2015-02-01

An electrically conductive silver paste has been prepared from an organometallic compound, silver neodecanoate, as silver precursor. The precursor was highly soluble in organic solvents and decomposed into metallic silver at low sintering temperatures (<200°C). Thermogravimetric analysis showed the silver content of the paste was approximately 25 wt.%. Viscosity studies indicated the paste was a pseudoplastic liquid with viscosity in the range 6.5-9 Pa s. The paste was compatible with the micro-pen direct-writing process, enabling production of silver lines on a substrate. The electrical resistivity of the silver lines was 9 × 10-6 Ω cm after sintering at 115°C for 60 min, 5.8 × 10-6 Ω cm when sintered at 150°C for 60 min, and 3 × 10-6 Ω cm when sintered above 300°C, values which are similar to those of bulk silver. Hence, the prepared paste can be successfully used on flexible substrates such as polymers.

Silver nanowire-based transparent, flexible, and conductive thin film

PubMed Central

2011-01-01

The fabrication of transparent, conductive, and uniform silver nanowire films using the scalable rod-coating technique is described in this study. Properties of the transparent conductive thin films are investigated, as well as the approaches to improve the performance of transparent silver nanowire electrodes. It is found that silver nanowires are oxidized during the coating process. Incubation in hydrogen chloride (HCl) vapor can eliminate oxidized surface, and consequently, reduce largely the resistivity of silver nanowire thin films. After HCl treatment, 175 Ω/sq and approximately 75% transmittance are achieved. The sheet resistivity drops remarkably with the rise of the film thickness or with the decrease of transparency. The thin film electrodes also demonstrated excellent flexible stability, showing < 2% resistance change after over 100 bending cycles. PMID:21711602

PVP-coated silver nanoparticles showing antifungal improved activity against dermatophytes

NASA Astrophysics Data System (ADS)

Silva, Edgar; Saraiva, Sofia M.; Miguel, Sónia P.; Correia, Ilídio J.

2014-11-01

Fungal infections affecting human beings have increased during the last years and the currently available treatments, when administered for long periods, trigger microbial resistance. Such demands the development of new viable therapeutic alternatives. Silver is known since the antiquity by its antimicrobial properties and, herein, it was used to produce two types of nanoparticles (NPs), uncoated and coated with polyvinylpyrrolidone (PVP), which were aimed to be used in fungal infection treatment. NPs properties were characterized by Transmission electron microscopy, X-ray diffraction, UV-Vis, Dynamic light scattering, Fourier transform infrared, and Energy-dispersive X-ray spectroscopy. Furthermore, in vitro studies were also performed to evaluate NPs cytotoxic profile and antifungal activity. The results obtained revealed that the produced nanoparticles are biocompatible and have a good potential for being used in the treatment of common skin infections caused by Trichophyton rubrum and Trichophyton mentagrophytes, being PVP-coated silver NPs the most suitable ones.

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.

Silver enhancement of nanogold and undecagold

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

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, frequentlymore » 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.« less

In vitro percutaneous penetration and characterization of silver from silver-containing textiles

PubMed Central

Bianco, Carlotta; Kezic, Sanja; Crosera, Matteo; Svetličić, Vesna; Šegota, Suzana; Maina, Giovanni; Romano, Canzio; Larese, Francesca; Adami, Gianpiero

2015-01-01

The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS) and by inductively coupled plasma mass spectrometer (ICP-MS). The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX). Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM). On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration) ranged from 0.7 to 4.7 μg/mL (0.6–4.0 μg/cm2), fitting the bactericidal range. Silver and silver chloride aggregates at sizes of up to 1 μm were identified both in the epidermis and dermis. The large size of these particles suggests that the aggregation occurred in the skin. The formation of these aggregates likely slowed down the systemic absorption of silver. Conversely, these aggregates may form a reservoir enabling prolonged release of silver ions, which might lead to local effects. PMID:25792824

Photochemical Study of Silver Nanoparticles Formed from the Reduction of Silver Ions by Humic Acid

NASA Astrophysics Data System (ADS)

Leslie, Renee M.

This study focuses on the ability of silver ions and humic acid to form silver nanoparticles in the presence of UV and visible light. Silver nanoparticles have a number of industrial applications due primarily to their antimicrobial properties, but these properties pose an environmental threat. Silver nanoparticles can directly disrupt sensitive ecosystems by harming bacteria. Consumption of silver nanoparticles results in silver ions and silver nanoparticles entering waterways; the presence of silver ions raises the question of whether nanoparticles can reform in environmental waters. As our data show, silver nanoparticles can form from the reduction of silver ions by humic acid after irradiation with UV and visible light. In order to better understand the mechanism of these naturally synthesized silver nanoparticles, we investigated the effects of reactant concentration, experimental conditions and presence of ions/reactive species. We monitored silver nanoparticle growth with UV-visible spectroscopy. The evolution in time of nanoparticle size was monitored by dynamic light scattering (DLS).

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.

A modified technique for the preparation of SO2 from sulphates and sulphides for sulphur isotope analyses.

PubMed

Han, L; Tanweer, A; Szaran, J; Halas, S

2002-09-01

A modified technique for the conversion of sulphates and sulphides to SO2 with the mixture of V2O5-SiO2 for sulphur isotopic analyses is described. This technique is more suitable for routine analysis of large number of samples. Modification of the reaction vessel and using manifold inlet system allows to analyse up to 24 samples every day. The modified technique assures the complete yield of SO2, consistent oxygen isotope composition of the SO2 gas and reproducibility of delta34S measurements being within 0.10 per thousand. It is observed, however, oxygen in SO2 produced from sulphides differs in delta18O with respect to that produced from sulphates.

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

Laser-induced dewetting of silver-doped chalcogenide glasses

NASA Astrophysics Data System (ADS)

Douaud, Alexandre; Messaddeq, Sandra Helena; Boily, Olivier; Messaddeq, Younès

2018-07-01

We report the observation of laser-induced dewetting responsible for the formation of periodic relief structures in silver-based chalcogenide thin-films. By varying the concentration of silver in the Agx(As20S80)100-x system (with x = 0, 4, 9 and 36), different surface relief structures are formed. The evolution of the surface changes as a function of laser parameters (power density, duration of exposure, and polarisation) as well as film thickness and silver concentration has been investigated. The scanning electron microscopy and atomic force microscopy images of irradiated spots show periodic ripples aligned perpendicularly to the electric field of incident light. Our results show that addition of silver into sulphur-rich chalcogenide thin-films improves the dewetting when compared to pure As20S80 thin-films. The changes in surface morphology were attributable to photo-induced chemical modifications and a laser-driven molecular rearrangement.

Long-Term Planning for Open Pits for Mining Sulphide-Oxide Ores in Order to Achieve Maximum Profit

NASA Astrophysics Data System (ADS)

Kržanović, Daniel; Conić, Vesna; Stevanović, Dejan; Kolonja, Božo; Vaduvesković, Jovan

2017-12-01

Profitable exploitation of mineralised material from the earth's crust is a complex and difficult task that depends on a comprehensive planning process. Answering the question of how to plan production depends on the geometry of the deposit, as well as the concentration, distribution, and type of minerals in it. The complex nature of mineral deposits largely determines the method of exploitation and profitability of mining operations. In addition to unit operating costs and metal prices, the optimal recovery of and achievement of maximum profit from deposits of sulphide-oxide ores also depend, to a significant extent, on the level of technological recovery achieved in the ore processing procedure. Therefore, in defining a long-term development strategy for open pits, special attention must be paid to the selection of an optimal procedure for ore processing in order to achieve the main objective: maximising the Net Present Value (NPV). The effect of using two different processes, flotation processing and hydrometallurgical methods (bioleaching acid leaching), on determining the ultimate pit is shown in the case of the Kraku Bugaresku-Cementacija sulphide-oxide ore deposit in eastern Serbia. Analysis shows that the application of hydrometallurgical methods of processing sulphide-oxide ore achieved an increase in NPV of 20.42%.

Silver Flakes and Silver Dendrites for Hybrid Electrically Conductive Adhesives with Enhanced Conductivity

NASA Astrophysics Data System (ADS)

Ma, Hongru; Li, Zhuo; Tian, Xun; Yan, Shaocun; Li, Zhe; Guo, Xuhong; Ma, Yanqing; Ma, Lei

2018-03-01

Silver dendrites were prepared by a facile replacement reaction between silver nitrate and zinc microparticles of 20 μm in size. The influence of reactant molar ratio, reaction solution volume, silver nitrate concentration, and reaction time on the morphology of dendrites was investigated systematically. It was found that uniform tree-like silver structures are synthesized under the optimal conditions. Their structure can be described as a trunk, symmetrical branches, and leaves, which length scales of 5-10, 1-2 μm, and 100-300 nm, respectively. All features were systematically characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and x-ray powder diffraction. A hybrid fillers system using silver flakes and dendrites as electrically conductive adhesives (ECAs) exhibited excellent overall performance. This good conductivity can be attributed mainly to the synergy between the silver microflakes (5-20 μm sized irregular sheet structures) and dendrites, allowing more conductive pathways to be formed between the fillers. In order to further optimize the overall electrical conductivity, various mixtures of silver microflakes and silver dendrites were tested in ECAs, with results indicating that the highest conductivity was shown when the amounts of silver microflakes, silver dendrites and the polymer matrix were 69.4 wt.% (20.82 vol.%), 0.6 wt.% (0.18 vol.%), and 30.0 wt.% (79.00 vol.%), respectively. The corresponding mass ratio of silver flakes to silver dendrites was 347:3. The resistivity of ECAs reached as low as 1.7 × 10-4 Ω cm.

Silver-loaded seaweed-based cellulosic fiber improves epidermal skin physiology in atopic dermatitis: safety assessment, mode of action and controlled, randomized single-blinded exploratory in vivo study.

PubMed

Fluhr, Joachim W; Breternitz, Maria; Kowatzki, Doreen; Bauer, Andrea; Bossert, Joerg; Elsner, Peter; Hipler, Uta-Christina

2010-08-01

reduction in Staphylococcus aureus colonization was detectable for the silver T-shirts compared with cotton T-shirts without any changes in non-pathogenic surface bacteria colonization. Furthermore, a more pronounced improvement in barrier function (transepidermal water loss) was observed in mildly involved eczema areas during the first 4 weeks of the study. Stratum corneum hydration and surface pH improved in both treatment groups over time. The tested silver-loaded seaweed fibre can be regarded as safe and seams to be suited for application in bio-active textiles in atopic dermatitis based on its positive in vivo activity.

Use of ESI-MS to determine reaction pathway for hydrogen sulphide scavenging with 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine.

PubMed

Madsen, Henrik T; Søgaard, Erik G

2012-01-01

To study the reaction between hydrogen sulphide and 1,3,5-tri-(2-hydroxyethyl)-hexahydro-s-triazine, which is an often used hydrogen sulphide scavenger, electro spray ionisation mass spectrometry (ESI-MS) was used. The investigation was carried out in positive mode, and tandem mass spectrometry was used to investigate the nature of unknown peaks in the mass spectra. The reaction was found to proceed as expected from theory with the triazine reacting with hydrogen sulphide to form the corresponding thiadiazine. This species subsequently reacted with a second hydrogen sulphide molecule to form the dithiazine species, hereby confirming previously obtained results and showing the ability of the ESI-MS method for studying the scavenging reaction. The final theoretical product s-trithiane was not detected. Furthermore, fragmentation products of thiadiazine and dithiazine were detected in the solution, and possible pathways and structures were suggested to describe the observed fragments. In these, thiadiazine fragmented to 2-(methylidene amino)-ethanol and 2-(1,3-thiazetidin-3-yl)-ethanol and N-(2-hydroxyethyl)-N-(sulfanylmethyl)-ethaniminium, which underwent a further fragmentation to N-methyl-N-(2-oxoethyl)-methaniminium. Dithiazine fragmented to N-methyl-N-(2-oxoethyl)-methaniminium as well. The by-product from this reaction is methanedithiol, which was not detected due to its low polarity.

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.

Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution

NASA Astrophysics Data System (ADS)

Stevenson, Amadeus PZ; Blanco Bea, Duani; Civit, Sergi; Antoranz Contera, Sonia; Iglesias Cerveto, Alberto; Trigueros, Sonia

2012-02-01

Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd.

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

NASA Astrophysics Data System (ADS)

Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

2017-03-01

A comparative study of amine and silver carboxylate adducts [R1COOAg-2(R2NH2)] (R1 = 1, 7, 11; R2 = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies (1H and 13C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors.

PubMed

Uznanski, Pawel; Zakrzewska, Joanna; Favier, Frederic; Kazmierski, Slawomir; Bryszewska, Ewa

2017-01-01

A comparative study of amine and silver carboxylate adducts [R 1 COOAg-2(R 2 NH 2 )] (R 1  = 1, 7, 11; R 2  = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, 13 C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ( 1 H and 13 C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism. Graphical abstractThe synthesis of a series (bis)alkylamine silver(I) carboxylate complexes in nonpolar solvents were carried out and fully characterized both in the solid and solution. Carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of

Similarities and Differences between Silver Ions and Silver in Nanoforms as Antibacterial Agents

PubMed Central

Kędziora, Anna; Speruda, Mateusz; Rybka, Jacek; Łukowiak, Anna; Bugla-Płoskońska, Gabriela

2018-01-01

Silver is considered as antibacterial agent with well-known mode of action and bacterial resistance against it is well described. The development of nanotechnology provided different methods for the modification of the chemical and physical structure of silver, which may increase its antibacterial potential. The physico-chemical properties of silver nanoparticles and their interaction with living cells differs substantially from those of silver ions. Moreover, the variety of the forms and characteristics of various silver nanoparticles are also responsible for differences in their antibacterial mode of action and probably bacterial mechanism of resistance. The paper discusses in details the aforementioned aspects of silver activity. PMID:29393866

Hyaluronan/Tween 80-assisted synthesis of silver nanoparticles for biological application

NASA Astrophysics Data System (ADS)

Li, Hui-Jun; Zhang, An-Qi; Sui, Li; Qian, Dong-Jin; Chen, Meng

2015-02-01

Water-soluble and well-stabilized silver nanoparticles (NPs) of small size have been synthesized using hyaluronan (HA) and Tween 80 as reducing and stabilizing agents. The effect of reaction conditions on the formation process of silver NPs was studied, and an aggregative growth mechanism of the silver NPs dominated in HA/Tween 80 system at pH 12 has been proposed. The obtained Ag NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. Moreover, the stability of the HA-Tween 80-silver NPs in normal saline was also studied, and a flexible blend membrane containing chitosan, gelatin, and the HA-Tween 80-silver NPs was prepared for further biological applications. Due to the high specific surface area and improved stability of silver NPs, the chitosan-gelatin-silver membrane has shown high antibacterial activity for strains of Escherichia coli. The cell viability tests indicate that the polymer membrane is non-cytotoxic to HepG2 cells, which might be attributed to its good biocompatibility.

Ultra-low temperature curable nano-silver conductive adhesive for piezoelectric composite material

NASA Astrophysics Data System (ADS)

Yan, Chao; Liao, Qingwei; Zhou, Xingli; Wang, Likun; Zhong, Chao; Zhang, Di

2018-01-01

Limited by the low thermal resistance of composite material, ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conduction treatment of piezoelectric composite material. An ultra-low temperature curable nano-silver conductive adhesive with high adhesion strength for the applications of piezoelectric composite material was investigated. The crystal structure of cured adhesive, SEM/EDS analysis, thermal analysis, adhesive properties and conductive properties of different content of nano-silver filler or micron-silver doping samples were studied. The results show that with 60 wt.% nano-silver filler the ultra-low temperature curable conductive silver adhesive had the relatively good conductivity as volume resistivity of 2.37 × 10-4 Ω cm, and good adhesion strength of 5.13 MPa. Minor micron-doping (below 15 wt.%) could improve conductivity, but would decrease other properties. The ultra-low temperature curable nano-silver conductive adhesive could successfully applied to piezoelectric composite material.

Diamond growth beneath Letlhakane established by Re-Os and Sm-Nd systematics of individual eclogitic sulphide, garnet and clinopyroxene inclusions

NASA Astrophysics Data System (ADS)

Gress, Michael U.; Pearson, D. Graham; Timmerman, Suzette; Chinn, Ingrid L.; Koornneef, Janne M.; Davies, Gareth R.

2017-04-01

The diamondiferous Letlhakane kimberlites are part of the Orapa kimberlite cluster (˜ 93.1 Ma) in north-eastern Botswana, located on the edge of the Zimbabwe Craton, close to the Proterozoic Magondi Mobile Belt. Here we report the first Re-Os ages of six individual eclogitic sulphide inclusions (3.0 to 35.7μg) from Letlhakane diamonds along with their rhenium, osmium, iridium and platinum concentrations, and carbon isotope, nitrogen content and N-aggregation data from the corresponding growth zones of the host diamonds. For the first time, Re-Os data will be compared to Sm-Nd ages of individual eclogitic silicate inclusions recovered from the same diamonds using a Triton Plus equipped with four 1013Ω amplifiers. The analysed inclusion set currently encompasses pairs of individual sulphides from two diamonds (LK040 sf4 & 5, LK113 sf1 & 2) and two sulphide inclusions from separate diamonds (LK048, LK362). Ongoing work will determine the Sm-Nd ages and element composition of multiple individual eclogitic garnets (LK113/LK362, n=4) and an eclogitic clinopyroxene (LK040) inclusion. TMA ages of the six sulphides range from 1.06 to 2.38 Ga (± 0.1 to 0.54 Ga) with Re and Os contents between 7 and 68 ppb and 0.03 and 0.3 ppb, respectively. The host diamond growth zones have low nitrogen abundances (21 to 43 ppm N) and high N-aggregation (53 to 90% IaB). Carbon isotope data suggests the involvement of crustal carbon (δ13C between -19.3 to -22.7 ± 0.2 per mill) during diamond precipitation. Cathodoluminescence imaging of central plates from LK040 and LK113 displays homogenous internal structure with no distinct zonation. The two sulphide inclusions from LK040 define an 'isochron' of 0.92 ± 0.23 Ga (2SD) with initial 187Os/188Os = 1.31 ± 0.24. Sulphides from LK113 have clear imposed diamond morphology and indicate diamond formation at 0.93 ± 0.36 Ga (2SD) with initial 187Os/188Os = 0.69 ± 0.44. The variation in the initial 187Os/188Os does not justify including these

Silver Film Surface Modification by Ion Bombardment Decreases Surface Plasmon Resonance Absorption.

PubMed

Fryauf, David M; Diaz Leon, Juan J; Phillips, Andrew C; Kobayashi, Nobuhiko P

2017-05-10

Silver thin films covered with dielectric films serving as protective coatings are desired for telescope mirrors, but durable coatings have proved elusive. As part of an effort to develop long-lived protected-silver mirrors, silver thin films were deposited by electron beam evaporation using a physical vapor deposition system at the University of California Observatories Astronomical Coatings Lab. The silver films were later covered with a stack of dielectric films utilizing silicon nitride and titanium dioxide deposited by ion-assisted electron beam evaporation to fabricate protected mirrors. In-situ argon ion bombardment was introduced after silver deposition and prior to the deposition of dielectric films to assess its effects on the performance of the mirrors. We found that ion bombardment of the silver influenced surface morphology and reflectivity, and these effects correlated with time between silver deposition and ion bombardment. The overall reflectivity at wavelengths in the range of 350-800 nm was found to improve due to ion bombardment, which was qualitatively interpreted as a result of decreased surface plasmon resonance coupling. We suggest that the observed decrease in coupling is caused by silver grain boundary pinning due to ion bombardment suppressing silver surface diffusion, forming smoother silver-dielectric interfaces.

Reagents and fractions impact on sulphide ore heap bioleaching at Smolnik mine

NASA Astrophysics Data System (ADS)

Oros, L. M.; Zavada, J.

2017-10-01

Mine Smolnik is one of the oldest sulphide ore mines in Europe and it is also an important part of bioleaching development. This paper follows previous attempts to extract residual metals from nearby heaps via variations in bioleaching reagents with regard to recent findings and needs in the related industry. Furthermore, economic and process relations between reagents and chosen heap fractions were also investigated in this case study.

Colloidal silver: a novel treatment for Staphylococcus aureus biofilms?

PubMed

Goggin, Rachel; Jardeleza, Camille; Wormald, Peter-John; Vreugde, Sarah

2014-03-01

Colloidal silver is an alternative medicine consisting of silver particles suspended in water. After using this solution as a nasal spray, the symptoms of a previously recalcitrant Staphylococcus aureus (S. aureus)-infected chronic rhinosinusitis patient were observed to have improved markedly. The aim of this study was to determine whether colloidal silver has any direct bactericidal effects on these biofilms in vitro. S. aureus biofilms were grown from the ATCC 25923 reference strain on Minimum Biofilm Eradication Concentration (MBEC) device pegs, and treated with colloidal silver. Concentrations tested ranged from 10 to 150 μL colloidal silver diluted to 200 μL with sterile water in 50 μL cerebrospinal fluid (CSF) broth. Control pegs were exposed to equivalent volumes of CSF broth and sterile water. The sample size was 4 biomass values per treatment or control group. Confocal scanning laser microscopy and COMSTAT software were used to quantify biofilms 24 hours after treatment. Significant differences from control were found for all concentrations tested bar the lowest of 10 μL colloidal silver in 200 μL. At 20 μL colloidal silver, the reduction in biomass was 98.9% (mean difference between control and treatment = -4.0317 μm(3) /μm(2) , p < 0.0001). A maximum biomass reduction of 99.8% was reached at both 100 and 150 μL colloidal silver (mean differences = -4.0681 and -4.0675μm(3) /μm(2) , respectively, p < 0.0001). Colloidal silver directly attenuates in vitro S. aureus biofilms. © 2014 ARS-AAOA, LLC.

Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

NASA Astrophysics Data System (ADS)

Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li, Zi-An; Farle, Michael; Köller, Manfred; Epple, Matthias

2012-10-01

Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly( N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 μg mL-1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

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 (T g ). IF-WS₂ contents higher than 0.5 wt % increased T g 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.

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

Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

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

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

Melanin-templated rapid synthesis of silver nanostructures

PubMed Central

2014-01-01

Background As a potent antimicrobial agent, silver nanostructures have been used in nanosensors and nanomaterial-based assays for the detection of food relevant analytes such as organic molecules, aroma, chemical contaminants, gases and food borne pathogens. In addition silver based nanocomposites act as an antimicrobial for food packaging materials. In this prospective, the food grade melanin pigment extracted from sponge associated actinobacterium Nocardiopsis alba MSA10 and melanin mediated synthesis of silver nanostructures were studied. Based on the present findings, antimicrobial nanostructures can be developed against food pathogens for food industrial applications. Results Briefly, the sponge associated actinobacterium N. alba MSA10 was screened and fermentation conditions were optimized for the production of melanin pigment. The Plackett-Burman design followed by a Box-Behnken design was developed to optimize the concentration of most significant factors for improved melanin yield. The antioxidant potential, reductive capabilities and physiochemical properties of Nocardiopsis melanin was characterized. The optimum production of melanin was attained with pH 7.5, temperature 35°C, salinity 2.5%, sucrose 25 g/L and tyrosine 12.5 g/L under submerged fermentation conditions. A highest melanin production of 3.4 mg/ml was reached with the optimization using Box-Behnken design. The purified melanin showed rapid reduction and stabilization of silver nanostructures. The melanin mediated process produced uniform and stable silver nanostructures with broad spectrum antimicrobial activity against food pathogens. Conclusions The melanin pigment produced by N. alba MSA10 can be used for environmentally benign synthesis of silver nanostructures and can be useful for food packaging materials. The characteristics of broad spectrum of activity against food pathogens of silver nanostructures gives an insight for their potential applicability in incorporation of food

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. Copyright © 2015. Published by Elsevier B.V.

Use of Silver in the Prevention and Treatment of Infections: Silver Review

PubMed Central

Campbell, Kristin T.; Rosenberger, Laura H.; Sawyer, Robert G.

2013-01-01

Abstract Background The use of silver for the treatment of various maladies or to prevent the transmission of infection dates back to at least 4000 b.c.e. Medical applications are documented in the literature throughout the 17th and 18th centuries. The bactericidal activity of silver is well established. Silver nitrate was used topically throughout the 1800s for the treatment of burns, ulcerations, and infected wounds, and although its use declined after World War II and the advent of antibiotics, Fox revitalized its use in the form of silver sulfadiazine in 1968. Method Review of the pertinent English-language literature. Results Since Fox's work, the use of topical silver to reduce bacterial burden and promote healing has been investigated in the setting of chronic wounds and ulcers, post-operative incision dressings, blood and urinary catheter designs, endotracheal tubes, orthopedic devices, vascular prostheses, and the sewing ring of prosthetic heart valves. The beneficial effects of silver in reducing or preventing infection have been seen in the topical treatment of burns and chronic wounds and in its use as a coating for many medical devices. However, silver has been unsuccessful in certain applications, such as the Silzone heart valve. In other settings, such as orthopedic hardware coatings, its benefit remains unproved. Conclusion Silver remains a reasonable addition to the armamentarium against infection and has relatively few side effects. However, one should weigh the benefits of silver-containing products against the known side effects and the other options available for the intended purpose when selecting the most appropriate therapy. PMID:23448590

High purity silver microcrystals recovered from silver wastes by eco-friendly process using hydrogen peroxide.

PubMed

Gatemala, Harnchana; Ekgasit, Sanong; Wongravee, Kanet

2017-07-01

A simple, rapid, and environmentally friendly process using hydrogen peroxide, was developed for recovering high purity silver directly from industry and laboratory wastes. Silver ammine complex, [Ag(NH 3 ) 2 ] + Cl - , derived from AgCl were generated and then directly reduced using H 2 O 2 to reliably turn into high purity microcrystalline silver (99.99%) examined by EDS and XRD. Morphology of the recovered silver microcrystals could be selectively tuned by an addition of poly(vinyl pyrrolidone). The main parameters in the recovering process including pH, concentration of Ag + and the mole ratio of H 2 O 2 :Ag + were carefully optimized though the central composite design (CCD). The optimized condition was employed for a trial recovery of 50 L silver ammine complex prepared from a collection of silver-wastes during 3-year research on industrial nanoparticle production. The recovered silver microcrystals >700 g could be recovered with 91.27%. The remaining solution after filtering of the recovered silver microcrystals can be used repeatedly (at least 8 cycles) without losing recovery efficiency. Matrix interferences including Pb 2+ and Cl - play a minimal role in our silver recovery process. Furthermore, the direct usage of the recovered silver microcrystals was demonstrated by using as a raw material of silver clay for creating a set of wearable silver jewelries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rapid deposition of triangular silver nanoplates on planar surfaces: application to metal-enhanced fluorescence.

PubMed

Aslan, Kadir; Lakowicz, Joseph R; Geddes, Chris D

2005-04-07

A simple and rapid wet-chemical technique for the deposition of silver triangles on conventional glass substrates, which alleviates the need for lithography, has been developed. The technique is based on the seed-mediated cetyltrimethylammonium-bromide-directed growth of silver triangles on glass surfaces, where smaller spherical silver seeds that were attached to the surface were subsequently converted and grown into silver triangles in the presence of a cationic surfactant and silver ions. The size of the silver triangles was controlled by sequential immersion of silver seed-coated glass substrates into a growth solution and by the duration time of immersion. Atomic force microscopy studies revealed that the size of the silver triangles ranged between 100 and 500 nm. Interestingly, these new surfaces are a significant improvement over traditional silver island films for applications in metal-enhanced fluorescence. A routine 16-fold enhancement in emission intensity was typically observed, for protein-immobilized indocyanine green, with a relatively very low loading density of silver triangles on the glass surface.

Leaching of S, Cu, and Fe from disseminated Ni-(Fe)-(Cu) sulphide ore during serpentinization of dunite host rocks at Mount Keith, Agnew-Wiluna belt, Western Australia

NASA Astrophysics Data System (ADS)

Gole, Martin J.

2014-10-01

Komatiite-hosted disseminated Ni sulphide deposits in the Agnew-Wiluna greenstone belt occur both above and below the olivine isograd that was imposed on the greenstone sequence during the M2 metamorphic/deformation event. Deposits in the northern and central part of the belt and that are located below the isograd (Mount Keith, Honeymoon Well and West Jordan) have complex sulphide mineralogy and strongly zoned sulphide assemblages. These range from least-altered assemblages of pentlandite-pyrrhotite-chalcopyrite±pyrite to altered assemblages of pentlandite±chalcopyrite, pentlandite-heazlewoodite (or millerite), heazlewoodite (or millerite), and rarely to heazlewoodite-native Ni. Deposits to the south and that are above of the olivine isograd (Six Mile, Goliath North) are dominated by less complex magmatic assemblages with a lower proportion of weakly altered pentlandite±chalcopyrite assemblages. More altered assemblages are uncommon in these deposits and occur as isolated patches around the periphery of the deposits. The sulphide zonation is reflected by whole-rock reductions in S, Cu, Fe and Zn, whereas Ni, Pt and Pd and, with some exceptions, Co are conservative. The leaching of S, Cu, Fe and Zn from sulphide assemblages and the whole rock was initiated by highly reduced conditions that were produced during low fluid/rock ratio serpentinization. Consumption of H2O resulted in Cl, a component of the fluid, being concentrated sufficiently to stabilise iowaite as part of lizardite-rich assemblages. Once the rate of olivine hydration reactions declined and during and after expansion and associated fracturing of the ultramafic sequence allowed higher fluid access, a more fluid-dominated environment formed and new carbonate-bearing fluid gained access to varying extents to the ultramafic rock sequence. This drove Cl from iowaite (to form pyroaurite) and caused the sulphide assemblages to be altered from the original magmatic assemblages and compositions to those

Typology of mafic-ultramafic complexes in Hoggar, Algeria: Implications for PGE, chromite and base-metal sulphide mineralisation

NASA Astrophysics Data System (ADS)

Augé, Thierry; Joubert, Marc; Bailly, Laurent

2012-02-01

With the aims to bring new information about the typology and mineral potential of mafic-ultramafic complexes of the Hoggar, detailed petrological and chemical characterisation were performed on serpentinite bands and layered intrusions. The serpentinite bands locally contain pods, layers and disseminations of chromite showing all the characteristics (mode of occurrence, composition, nature and composition of silicate inclusions, etc.) of an "ophiolite" chromite. Some chromite concentrations in the serpentinite bands also contain inclusions of platinum-group minerals (described for the first time in the Hoggar) such as ruarsite (RuAsS), an Os, Ru, Ir alloy, and complex Os, Ir, Ru sulfarsenides and arsenides. The serpentinite probably corresponds to remnants of oceanic lithosphere—more specifically from the upper part of the mantle sequence, generally where chromitite pods are most abundant, and the basal part of the cumulate series with stratiform chromite concentrations—and marks suture zones; the rest of the oceanic crust has not been preserved. Considering the typology of the serpentinites bands, their potential for precious- and base-metals is suspected to be low. Of the two layered mafic-ultramafic intrusions that were studied, the In Tedeini intrusion has a wehrlite core intruded by olivine gabbronorite and surrounded by an olivine gabbro aureole; three orthocumulate units, containing disseminated magmatic base-metal sulphides and with a plagioclase composition varying around An 58.1 and An 63.3, that could have been derived from a single magma. The East Laouni intrusion has a basal unit of olivine gabbronorite with specific silicate oxide intergrowths, and an upper unit of more differentiated gabbro, both units containing disseminated magmatic Ni-Cu sulphides indicative of early sulphide immiscibility; the mineral composition of these two cumulate units indicates that they also could have been derived from a single magmatic episode. The characteristic of

Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

NASA Astrophysics Data System (ADS)

Liu, Suwen; Wehmschulte, Rudolf J.; Lian, Guoda; Burba, Christopher M.

2006-03-01

Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD).

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.

Fractionation of silver isotopes in native silver explained by redox reactions

NASA Astrophysics Data System (ADS)

Mathur, Ryan; Arribas, Antonio; Megaw, Peter; Wilson, Marc; Stroup, Steven; Meyer-Arrivillaga, Danilo; Arribas, Isabel

2018-03-01

Scant data exist on the silver isotope composition of native silver specimens because of the relative newness of the technique. This study increases the published dataset by an order of magnitude and presents 80 silver new isotope analyses from native silver originating from a diverse set of worldwide deposits (8 deposit types, 33 mining districts in five continents). The measured isotopic range (defined as δ109Ag/107Ag in per mil units compared to NIST 978 Ag isotope standard) is +2.1 to -0.86‰ (2σ errors less than 0.015); with no apparent systematic correlations to date with deposit type or even within districts. Importantly, the data centering on 0‰ all come from high temperature hypogene/primary deposits whereas flanking and overlapping data represent secondary supergene deposits. To investigate the causes for the more fractionated values, several laboratory experiments involving oxidation of silver from natural specimens of Ag-rich sulfides and precipitation and adsorption of silver onto reagent grade MnO2 and FeOOH were conducted. Simple leach experiments demonstrate little Ag isotope fractionation occurred through oxidation of Ag from native Ag (Δsolution-native109Ag = 0.12‰). In contrast, significant fractionation occurred through precipitation of native Ag onto MnO2 (up to Δsolution-MnO2109Ag = 0.68‰, or 0.3amu). Adsorption of silver onto the MnO2 and FeOOH did not produce as large fractionation as precipitation (mean value of Δsolution-MnO2109Ag = 0.10‰). The most likely cause for the isotopic variations seen relates to redox effects such as the reduction of silver from Ag (I) to Ag° that occurs during precipitation onto the mineral surface. Since many Ag deposits have halos dominated by MnO2 and FeOOH phases, potential may exist for the silver isotope composition of ores and surrounding geochemical haloes to be used to better understand ore genesis and potential exploration applications. Aside from the Mn oxides, surface fluid silver

Studying microfungi-mineral interactions in sulphide-bearing waste-rock dumps: a 7 years survey in the Libiola mine, North-Eastern Italy

NASA Astrophysics Data System (ADS)

Marescotti, P.; Cecchi, G.; Di Piazza, S.; Lucchetti, G.; Zotti, M.

2015-12-01

Sulphide-bearing waste-rock dumps represent complex geological systems characterised by high percentages of low-grade mineralisations and non-valuable sulphides (such as pyrite and pyrrhotite). The sulphide oxidation triggers acid mine drainage (AMD) processes and the release of several metals of environmental concern. The severe physicochemical properties of these metal-contaminated environments tend to inhibit soil forming processes and represent an important stress factor for the biotic communities by exerting a strong selective pressure. Some macro- and micro-fungi are pioneer and extremophile organisms, which may survive and tolerate high concentrations of toxic metals in contaminated environments. Many studies show the fungal capability to bioaccumulate, biosorb, and store in their cells a high concentration of ecotoxic metals. A 7 years multidisciplinary survey was carried out in the Libiola sulphide mine. The results evidenced that the waste rock dumps of the area are characterized by an extremely poor flora and a specific mycobiota, due to the soil acidity, high concentration of trace metals, and unavailability or paucity of nutrients and organic matter. Our studies allowed the complete mineralogical, geochemical, and mycological characterization of one of the biggest dumps of the mine. 30 microfungal vital strains were isolated in pure cultures and studied with molecular and morphological approach, for their identification. The results allowed the isolation of some rare and important extremophilic species. Penicillium was the most recurrent genus, together with Trichoderma and Cladosporium. In particular, Penicillium glandicola is a rare species previously isolated from cave or arid environments, whereas P. brevicompactum is one of the most important fungi for metal corrosion. Hence, some bioaccumulation tests allowed to select a Trichoderma harzianum strain efficient to uptake Cu and Ag from pyrite-bearing soils, highlighting its central role in fungal

In-situ Pb isotope analysis of Fe-Ni-Cu sulphides by laser ablation multi-collector ICPMS: New insights into ore formation in the Sudbury impact melt sheet

NASA Astrophysics Data System (ADS)

Darling, J. R.; Storey, C. D.; Hawkesworth, C. J.; Lightfoot, P. C.

2012-12-01

Laser-ablation (LA) multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) is ideally suited to in situ determination of isotope ratios in sulphide minerals. Using samples of magmatic sulphide ore from the Sudbury impact structure, we test LA-MC-ICPMS analytical protocols that aim to meet a range of analytical challenges in the analysis of Pb isotopes. These include: potential matrix sensitive isotopic fractionation; interferences on Pb isotopes; low melting points of many sulphide minerals; the availability of standards. Magmatic sulphides of wide ranging mineralogy (pyrrhotite, pentlandite, chalcopyrite, pyrite and sphalerite) were analysed for Pb isotopic composition, using the silicate glass NIST SRM 610 as an external standard to correct for instrumental mass-fractionation. Despite matrix sensitive melting and re-deposition around ablation pits, several lines of evidence indicate that all analyses are accurate, within typical analytical uncertainties of 0.003-2% (2σ), and that the defined approach is insensitive to compositional diversity in sample matrix: (a) laser ablation and dissolution based measurements of sulphide powders are in agreement; (b) analyses from each sample define isochron ages within uncertainty of the known crystallization age (1850 Ma); (c) the results of sulphide measurements by laser ablation are consistent with age-corrected feldspar analyses from the same samples. The results have important implications for ore formation in Sudbury. The Pb isotope data regressions are consistent with age corrected feldspar analyses from each respective sample, which together with time integrated Th/U ratios that match whole rock values (3.1, 4.0 and 6.1 for the Worthington, Copper Cliff and Parkin Offset Dykes, respectively) indicate chemical equilibrium between the silicate and sulphide systems during ore formation. The sulphides within each respective sample have indistinguishable model initial Pb isotope ratios (207Pb/204Pbm

Silver film on nanocrystalline TiO{sub 2} support: Photocatalytic and antimicrobial ability

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

Vukoje, Ivana D., E-mail: ivanav@vinca.rs; Tomašević-Ilić, Tijana D., E-mail: tommashev@gmail.com; Zarubica, Aleksandra R., E-mail: zarubica2000@yahoo.com

Highlights: • Simple photocatalytic rout for deposition of Ag on nanocrystalline TiO{sub 2} films. • High antibactericidal efficiency of deposited Ag on TiO{sub 2} support. • Improved photocatalytic performance of TiO{sub 2} films in the presence of deposited Ag. - Abstract: Nanocrystalline TiO{sub 2} films were prepared on glass slides by the dip coating technique using colloidal solutions consisting of 4.5 nm particles as a precursor. Photoirradiation of nanocrystalline TiO{sub 2} film modified with alanine that covalently binds to the surface of TiO{sub 2} and at the same time chelate silver ions induced formation of metallic silver film. Optical andmore » morphological properties of thin silver films on nanocrystalline TiO{sub 2} support were studied by absorption spectroscopy and atomic force microscopy. Improvement of photocatalytic performance of nanocrystalline TiO{sub 2} films after deposition of silver was observed in degradation reaction of crystal violet. Antimicrobial ability of deposited silver films on nanocrystalline TiO{sub 2} support was tested in dark as a function of time against Escherichia coli, Staphylococcus aureus, and Candida albicans. The silver films ensured maximum cells reduction of both bacteria, while the fungi reduction reached satisfactory 98.45% after 24 h of contact.« less

Paradoxical co-existing base metal sulphides in the mantle: The multi-event record preserved in Loch Roag peridotite xenoliths, North Atlantic Craton

NASA Astrophysics Data System (ADS)

Hughes, Hannah S. R.; McDonald, Iain; Loocke, Matthew; Butler, Ian B.; Upton, Brian G. J.; Faithfull, John W.

2017-04-01

The role of the subcontinental lithospheric mantle as a source of precious metals for mafic magmas is contentious and, given the chalcophile (and siderophile) character of metals such as the platinum-group elements (PGE), Se, Te, Re, Cu and Au, the mobility of these metals is intimately linked with that of sulphur. Hence the nature of the host phase(s), and their age and stability in the subcontinental lithospheric mantle may be of critical importance. We investigate the sulphide mineralogy and sulphide in situ trace element compositions in base metal sulphides (BMS) in a suite of spinel lherzolite mantle xenoliths from northwest Scotland (Loch Roag, Isle of Lewis). This area is situated on the margin of the North Atlantic Craton which has been overprinted by a Palaeoproterozoic orogenic belt, and occurs in a region which has undergone magmatic events from the Palaeoproterozoic to the Eocene. We identify two populations of co-existing BMS within a single spinel lherzolite xenolith (LR80) and which can also be recognised in the peridotite xenolith suite as a whole. Both populations consist of a mixture of Fe-Ni-Cu sulphide minerals, and we distinguished between these according to BMS texture, petrographic setting (i.e., location within the xenolith in terms of 'interstitial' or within feldspar-spinel symplectites, as demonstrated by X-ray Computed Microtomography) and in situ trace element composition. Group A BMS are coarse, metasomatic, have low concentrations of total PGE (< 40 ppm) and high (Re/Os)N (ranging 1 to 400). Group B BMS strictly occur within symplectites of spinel and feldspar, are finer-grained rounded droplets, with micron-scale PtS (cooperite), high overall total PGE concentrations (15-800 ppm) and low (Re/Os)N ranging 0.04 to 2. Group B BMS sometimes coexist with apatite, and both the Group B BMS and apatite can preserve rounded micron-scale Ca-carbonate inclusions indicative of sulphide-carbonate-phosphate immiscibility. This carbonate

Production of silver ions from colloidal silver by nanoparticle iontophoresis system.

PubMed

Tseng, Kuo-Hsiung; Liao, Chih-Yu

2011-03-01

Metal ions, especially the silver ion, were used to treat infection before the initiation of antibiotic therapy. Unfortunately, there is a lack of research on the metallic nanoparticle suspension as a reservoir for metal ion release application. For medical purposes, conversion of colloidal silver into an ionic form is necessary, but not using silver salts (e.g., AgNO3, Ag2SO4), due to the fact that the counter-ion of silver salts may cause problems to the body as the silver ion (Ag+) is consumed. The goal of this research is to develop a silver nanoparticle iontophoresis system (NIS) which can provide a relatively safe bactericidal silver ion solution with a controllable electric field. In this study, ion-selective electrodes were used to identify and observe details of the system's activity. Both qualitative and quantitative data analyses were performed. The experimental results show that the ion releasing peak time (R(PT)) has an inversely proportional relationship with the applied current and voltage. The ion releasing maximum level (R(ML)) and dosage (R(D)) are proportional to the current density and inversely proportional to the voltage, respectively. These results reveal that the nanoparticle iontophoresis system (NIS) is an alternative method for the controlled release of a metal ion and the ion's concentration profile, by controlling the magnitude of current density (1 microA/cm2 equal to 1 ppm/hour) and applied voltage.

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.

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.

Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

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

Liu Suwen; Wehmschulte, Rudolf J.; Lian Guoda

2006-03-15

Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 {mu}m, some even more than 100 {mu}m, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silvermore » nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD)« less

The use of the core-shell structure of zero-valent iron nanoparticles (NZVI) for long-term removal of sulphide in sludge during anaerobic digestion.

PubMed

Su, Lianghu; Zhen, Guangyin; Zhang, Longjiang; Zhao, Youcai; Niu, Dongjie; Chai, Xiaoli

2015-12-01

A core-shell structure results in zero-valent iron nanoparticles (NZVI) with manifold functional properties. In this study, the long-term effects of NZVI on hydrogen sulphide removal in an anaerobic sludge digester were investigated. Within 20 days, the average hydrogen sulphide content in the biogas was successfully reduced from 300 (or 3620 of sulphate-rich sludge) mg Nm(-3) to 6.1 (121), 0.9 (3.3) and 0.5 (1.3) mg Nm(-3) in the presence of 0.05, 0.10 and 0.20% (wt) NZVI, respectively. Methane yield was enhanced at the low NZVI dose (0.05-0.10%) but decreased at the elevated dose (0.20%). Methane production and volatile solid degradation analyses implied that doses of 0.5-0.10% NZVI could accelerate sludge stabilization during anaerobic digestion. The phosphorus fractionation profile suggested that methane production could be inhibited at the elevated NZVI dose, partly due to the limited availability of soluble phosphorus due to the immobilization of bioavailable-P through the formation of vivianite. An analysis of the reducible inorganic sulphur species revealed that the elimination of hydrogen sulphide occurred via the reaction between hydrogen sulphide and the oxide shell of NZVI, which mainly formed FeS and some FeS2 and S(0).

New Guar Biopolymer Silver Nanocomposites for Wound Healing Applications

PubMed Central

Abdullah, Md Farooque; Das, Suvadra; Roy, Partha; Datta, Sriparna; Mukherjee, Arup

2013-01-01

Wound healing is an innate physiological response that helps restore cellular and anatomic continuity of a tissue. Selective biodegradable and biocompatible polymer materials have provided useful scaffolds for wound healing and assisted cellular messaging. In the present study, guar gum, a polymeric galactomannan, was intrinsically modified to a new cationic biopolymer guar gum alkylamine (GGAA) for wound healing applications. Biologically synthesized silver nanoparticles (Agnp) were further impregnated in GGAA for extended evaluations in punch wound models in rodents. SEM studies showed silver nanoparticles well dispersed in the new guar matrix with a particle size of ~18 nm. In wound healing experiments, faster healing and improved cosmetic appearance were observed in the new nanobiomaterial treated group compared to commercially available silver alginate cream. The total protein, DNA, and hydroxyproline contents of the wound tissues were also significantly higher in the treated group as compared with the silver alginate cream (P < 0.05). Silver nanoparticles exerted positive effects because of their antimicrobial properties. The nanobiomaterial was observed to promote wound closure by inducing proliferation and migration of the keratinocytes at the wound site. The derivatized guar gum matrix additionally provided a hydrated surface necessary for cell proliferation. PMID:24175306

New guar biopolymer silver nanocomposites for wound healing applications.

PubMed

Ghosh Auddy, Runa; Abdullah, Md Farooque; Das, Suvadra; Roy, Partha; Datta, Sriparna; Mukherjee, Arup

2013-01-01

Wound healing is an innate physiological response that helps restore cellular and anatomic continuity of a tissue. Selective biodegradable and biocompatible polymer materials have provided useful scaffolds for wound healing and assisted cellular messaging. In the present study, guar gum, a polymeric galactomannan, was intrinsically modified to a new cationic biopolymer guar gum alkylamine (GGAA) for wound healing applications. Biologically synthesized silver nanoparticles (Agnp) were further impregnated in GGAA for extended evaluations in punch wound models in rodents. SEM studies showed silver nanoparticles well dispersed in the new guar matrix with a particle size of ~18 nm. In wound healing experiments, faster healing and improved cosmetic appearance were observed in the new nanobiomaterial treated group compared to commercially available silver alginate cream. The total protein, DNA, and hydroxyproline contents of the wound tissues were also significantly higher in the treated group as compared with the silver alginate cream (P < 0.05). Silver nanoparticles exerted positive effects because of their antimicrobial properties. The nanobiomaterial was observed to promote wound closure by inducing proliferation and migration of the keratinocytes at the wound site. The derivatized guar gum matrix additionally provided a hydrated surface necessary for cell proliferation.

Cytotoxicity testing of silver-containing burn treatments using primary and immortal skin cells.

PubMed

Boonkaew, Benjawan; Kempf, Margit; Kimble, Roy; Cuttle, Leila

2014-12-01

A novel burn wound hydrogel dressing has been previously developed which is composed of 2-acrylamido-2-methylpropane sulfonic acid sodium salt with silver nanoparticles (silver AMPS). This study compared the cytotoxicity of this dressing to the commercially available silver products; Acticoat™, PolyMem Silver(®) and Flamazine™ cream. Human keratinocytes (HaCaT and primary HEK) and normal human fibroblasts (NHF) were exposed to dressings incubated on Nunc™ polycarbonate inserts for 24, 48 and 72h. Four different cytotoxicity assays were performed including; Trypan Blue cell count, MTT, Celltiter-Blue™ and Toluidine Blue surface area assays. The results were expressed as relative cell viability compared to an untreated control. The cytotoxic effects of Acticoat™ and Flamazine™ cream were dependent on exposure time and cell type. After 24h exposure, Acticoat™ and Flamazine™ cream were toxic to all tested cell lines. Surprisingly, HaCaTs treated with Acticoat™ and Flamazine™ had an improved ability to survive at 48 and 72h while HEKs and NHFs had no improvement in survival with any treatment. The novel silver hydrogel and PolyMem Silver(®) showed low cytotoxicity to all tested cell lines at every time interval and these results support the possibility of using the novel silver hydrogel as a burn wound dressing. Researchers who rely on HaCaT cells as an accurate keratinocyte model should be aware that they can respond differently to primary skin cells. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

A physiologically based pharmacokinetic model for ionic silver and silver nanoparticles

PubMed Central

Bachler, Gerald; von Goetz, Natalie; Hungerbühler, Konrad

2013-01-01

Silver is a strong antibiotic that is increasingly incorporated into consumer products as a bulk, salt, or nanosilver, thus potentially causing side-effects related to human exposure. However, the fate and behavior of (nano)silver in the human body is presently not well understood. In order to aggregate the existing experimental information, a physiologically based pharmacokinetic model (PBPK) was developed in this study for ionic silver and nanosilver. The structure of the model was established on the basis of toxicokinetic data from intravenous studies. The number of calibrated parameters was minimized in order to enhance the predictive capability of the model. We validated the model structure for both silver forms by reproducing exposure conditions (dermal, oral, and inhalation) of in vivo experiments and comparing simulated and experimentally assessed organ concentrations. Therefore, the percutaneous, intestinal, or pulmonary absorption fraction was estimated based on the blood silver concentration of the respective experimental data set. In all of the cases examined, the model could successfully predict the biodistribution of ionic silver and 15–150 nm silver nanoparticles, which were not coated with substances designed to prolong the circulatory time (eg, polyethylene glycol). Furthermore, the results of our model indicate that: (1) within the application domain of our model, the particle size and coating had a minor influence on the biodistribution; (2) in vivo, it is more likely that silver nanoparticles are directly stored as insoluble salt particles than dissolve into Ag+; and (3) compartments of the mononuclear phagocytic system play a minor role in exposure levels that are relevant for human consumers. We also give an example of how the model can be used in exposure and risk assessments based on five different exposure scenarios, namely dietary intake, use of three separate consumer products, and occupational exposure. PMID:24039420

Cantilever testing of sintered-silver interconnects

DOE PAGES

Wereszczak, Andrew A.; Chen, Branndon R.; Jadaan, Osama M.; ...

2017-10-19

Cantilever testing is an underutilized test method from which results and interpretations promote greater understanding of the tensile and shear failure responses of interconnects, metallizations, or bonded joints. The use and analysis of this method were pursued through the mechanical testing of sintered-silver interconnects that joined Ni/Au-plated copper pillars or Ti/Ni/Ag-plated silicon pillars to Ag-plated direct bonded copper substrates. Sintered-silver was chosen as the interconnect test medium because of its high electrical and thermal conductivities and high-temperature capability—attractive characteristics for a candidate interconnect in power electronic components and other devices. Deep beam theory was used to improve upon the estimationsmore » of the tensile and shear stresses calculated from classical beam theory. The failure stresses of the sintered-silver interconnects were observed to be dependent on test-condition and test-material-system. In conclusion, the experimental simplicity of cantilever testing, and the ability to analytically calculate tensile and shear stresses at failure, result in it being an attractive mechanical test method to evaluate the failure response of interconnects.« less

Cantilever testing of sintered-silver interconnects

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

Wereszczak, Andrew A.; Chen, Branndon R.; Jadaan, Osama M.

Cantilever testing is an underutilized test method from which results and interpretations promote greater understanding of the tensile and shear failure responses of interconnects, metallizations, or bonded joints. The use and analysis of this method were pursued through the mechanical testing of sintered-silver interconnects that joined Ni/Au-plated copper pillars or Ti/Ni/Ag-plated silicon pillars to Ag-plated direct bonded copper substrates. Sintered-silver was chosen as the interconnect test medium because of its high electrical and thermal conductivities and high-temperature capability—attractive characteristics for a candidate interconnect in power electronic components and other devices. Deep beam theory was used to improve upon the estimationsmore » of the tensile and shear stresses calculated from classical beam theory. The failure stresses of the sintered-silver interconnects were observed to be dependent on test-condition and test-material-system. In conclusion, the experimental simplicity of cantilever testing, and the ability to analytically calculate tensile and shear stresses at failure, result in it being an attractive mechanical test method to evaluate the failure response of interconnects.« less

Geochemical, metagenomic and metaproteomic insights into trace metal utilization by methane-oxidizing microbial consortia in sulphidic marine sediments

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

Glass, DR. Jennifer; Yu, DR. Hang; Steele, Joshua

2013-01-01

Microbes have obligate requirements for trace metals in metalloenzymes that catalyse important biogeochemical reactions. In anoxic methane- and sulphiderich 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 H2S) 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 8more » 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.« less

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).

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.

Fabrication and testing of silver-hydrogen cells

NASA Technical Reports Server (NTRS)

Klein, M. G.

1978-01-01

The development and life testing of single electrode and multi electrode stacks to optimize the individual components and characterize the performance of a silver hydrogen battery system are described. A NASA-developed inorganic separator material was used as the main separator within the cells. Single electrode test cells were cycled at 75% of nominal capacity out through approximately 1,000 cycles in a number of cases where deterioration in performance was observed. This deterioration appears to be a decay in usable capacity of the silver electrode; but the exact mechanism is still unidentified. Twenty ampere-hour boilerplate test cells consisting of a stack of ten silver electrodes and twenty hydrogen electrodes were cycled also at 75% depth of discharge. The oldest stack achieved 522 stable cycles to the end of the program. Weight analysis of light-weight cells showed that 50 ampere-hour cells with improved components could be capable of as much as 40 watt hours per pound.

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.

Laundering durable antibacterial cotton fabrics grafted with pomegranate-shaped polymer wrapped in silver nanoparticle aggregations

NASA Astrophysics Data System (ADS)

Liu, Hanzhou; Lv, Ming; Deng, Bo; Li, Jingye; Yu, Ming; Huang, Qing; Fan, Chunhai

2014-08-01

To improve the laundering durability of the silver functionalized antibacterial cotton fabrics, a radiation-induced coincident reduction and graft polymerization is reported herein where a pomegranate-shaped silver nanoparticle aggregations up to 500 nm can be formed due to the coordination forces between amino group and silver and the wrapping procedure originated from the coincident growth of the silver nanoparticles and polymer graft chains. This pomegranate-shaped silver NPAs functionalized cotton fabric exhibits outstanding antibacterial activities and also excellent laundering durability, where it can inactivate higher than 90% of both E. coli and S. aureus even after 50 accelerated laundering cycles, which is equivalent to 250 commercial or domestic laundering cycles.

Improved conductivity and antibacterial activity of poly(2-aminothiophenol)-silver nanocomposite against human pathogens.

PubMed

Boomi, P; Anandha Raj, J; Palaniappan, S P; Poorani, G; Selvam, S; Gurumallesh Prabu, H; Manisankar, P; Jeyakanthan, J; Langeswaran, V K

2018-01-01

A rapid and simple chemical synthesis of poly(2-aminothiophenol)‑silver (P2ATP-Ag) nanocomposite using conductive and electroactive silver nanoparticles (AgNPs) is reported. The AgNPs was synthesized by chemical reduction method using tri‑sodium citrate as reducing agent and poly(N-vinyl-2-pyrrolidone) (PVP) as stabilizing agent. P2ATP-Ag nanocomposite was synthesized by using potassium peroxodisulphate as oxidant and the samples were characterized. The presence of AgNPs in the composite was confirmed from UV-Vis, FTIR and X-ray diffraction studies. Morphology of the P2ATP and its composite were investigated by SEM. HR-TEM images show spherical, trigonal and rod like morphologies with sizes of Ag nanoparticles and its composite. Thermal analysis revealed that the thermal stability of the P2ATP-Ag nanocomposite is improved when compared with pure P2ATP. The synthesized AgNPs, pure P2ATP and P2ATP-Ag nanocomposite were screened for antibacterial activity test against human pathogen such as Gram positive (Bacillus subtilis, ATCC-6051) and Gram negative (Vibrio cholerae, ATCC-14035), carried out by agar-well diffusion method at micro molar concentration. The result shows that P2ATP-Ag nanocomposite has excellent antibacterial activity due to the presence of Ag nanoparticles. The electrical conductivity of the P2ATP-Ag nanocomposite is better than that of pure P2ATP. The reported nanocomposite will be a potential material for electrocatalysis, sensors and biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

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). Copyright © 2016 Elsevier B.V. All rights reserved.

Preparing high-adhesion silver coating on APTMS modified polyethylene with excellent anti-bacterial performance

NASA Astrophysics Data System (ADS)

Li, Wenfei; Chen, Yunxiang; Wu, Song; Zhang, Jian; Wang, Hao; Zeng, Dawen; Xie, Changsheng

2018-04-01

Silver coating as a broad-spectrum antimicrobial agent was considered to alleviate the inflammation caused by intrauterine device (IUD) in endometrium. In this work, to avoid the damage of silver coating and ensure its antibacterial properties, 3-aminopropyltrimethoxysilane (APTMS) was introduced to modify the polyethylene (PE) substrate for the purpose of improving the adhesion of the silver coating. From the 90° peel test, it could be found that the adhesive strength of silver coating on the APTMS modified PE substrate was nearly 23 times stronger than the silver coating on substrate without surface modification. The dramatically enhanced adhesive strength could be attributed to the formation of continuous chemical bonds between the silver coatings and substrates after surface modification, which had been confirmed by the XPS. Moreover, the standard antibacterial test revealed that the silver coated samples against Staphylococcus aureus (S. aureus) exhibit excellent antibacterial efficacy. Considering the largely enhanced adhesion and the effective antibacterial property, it is reasonable to believe that the silver coating could be considered as a potential candidate for the antibacterial agent in IUD.

A perspective on the hemolytic activity of chemical and green-synthesized silver and silver oxide nanoparticles

NASA Astrophysics Data System (ADS)

Ashokraja, C.; Sakar, M.; Balakumar, S.

2017-10-01

We report the hemolysis properties of silver and silver oxide nanoparticles (NPs) prepared by chemical and green-synthesis methods. The prepared silver and silver oxide NPs were analyzed using UV-vis spectroscopy to confirm their formation by characterizing their surface plasmon resonance (SPR) and absorption band peaks respectively. The Fourier transmission infrared (FTIR) spectra of the materials showed the characteristic functional groups corresponding to the molecules present in leaf extracts, which is proposed to be acted as reducing and capping agents that are also found on the surface of silver and silver oxide nanoparticles that synthesized via green-synthesis method. Zeta potential analysis revealed the surface charge and stability of the prepared NPs. HRTEM images showed almost spherical shape nanoparticles with an average size of 15.2 and 31.5 nm for wet chemical synthesized silver and silver oxide nanoparticles respectively. In the case of green synthesized silver and silver oxide nanoparticles, it was observed to be 19.4 and 30.4 nm respectively. The order of hemolysis efficacy of the materials is found to be as follows: chemically synthesized Ag2O>  chemically synthesized Ag NPs followed by green-synthesized Ag2O and green-synthesized Ag NPs which showed almost similar hemolysis with respect to concentration. The relatively stable nature of the silver NPs could be attributed to their lower hemolysis efficacy, while the increased lysis properties of silver oxide could be attributed due to reductive/oxidative processes that give rise to the hemolysis through interfacial charge interactions with RBCs.

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.

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.

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.

Impact of chlorination on silver elution from ceramic water filters.

PubMed

Lyon-Marion, Bonnie A; Mittelman, Anjuliee M; Rayner, Justine; Lantagne, Daniele S; Pennell, Kurt D

2018-06-05

Applying silver nanoparticles (nAg) or silver nitrate (AgNO 3 ) to ceramic water filters improves microbiological efficacy, reduces biofilm formation, and protects stored water from recontamination. A challenge in ceramic filter production is adding sufficient silver to achieve these goals without exceeding the maximum recommended silver concentration in drinking water. Silver release is affected by silver type, application method, and influent water chemistry. Despite a lack of data, there is an assumption that chlorinated water should not be used as influent water because it may increase silver elution. Thus, the objective of this work was to systematically evaluate the impact of chlorinated water (0-4 mg/L free chlorine residual, FCR) on silver release from ceramic filter disks painted with casein-coated nAg, painted with AgNO 3 , or containing fired-in nAg over a range of ionic strength (IS = 0-10 mM as NaNO 3 ) in the presence or absence of natural organic matter (NOM). Influent deionized water containing chlorine increased silver release 2-5-fold compared to controls. However, this effect of chlorine was mitigated at higher IS (≥1 mM) or in the presence of NOM (3 mg C/L). For filter disks painted with nAg or AgNO 3 , silver release increased with increasing IS (with or without chlorine), and effluent concentrations remained above the World Health Organization (WHO) guideline of 0.1 mg/L even after 30 h (80 pore volumes, PVs) of flow with a background solution of 10 mM NaNO 3 . Silver speciation (nAg vs. Ag + ) was monitored in effluent samples from painted or fired-in nAg filter disks. Results indicated that in general, greater than 90% of the eluted silver was due to Ag + dissolution rather than nAg release. Additionally, a filter disk prepared with fired-in nAg exhibited a lower % released in the nanoparticle form (nAg = 5% of total Ag in effluent) compared to painted on nAg (nAg = 14% of total Ag in effluent). The findings of

Effect of preconditioning on silver leaching and bromide removal properties of silver-impregnated activated carbon (SIAC).

PubMed

Rajaeian, Babak; Allard, Sébastien; Joll, Cynthia; Heitz, Anna

2018-07-01

Silver impregnated activated carbon (SIAC) has been found to be effective in mitigating the formation of brominated-disinfection by products during drinking water treatment. However, there are still uncertainties regarding its silver leaching properties, and strategies for the prevention of silver leaching have remained elusive. This study focused on the evaluation of one type of commercially available SIAC for its ability to remove bromide while minimising silver leaching from the material. Both synthetic and real water matrices were tested. Depending on solution pH, it was found that changing the surface charge properties of SIAC, as measured by the point of zero charge pH, can result in additional bromide removal while minimising the extent of silver leaching. To better understand the mechanism of silver leaching from the SIAC, eight preconditioning environments, i.e. variable pH and ionic strength were tested for a fixed amount of SIAC and two preconditioning environments were selected for a more detailed investigation. Experiments carried out in synthetic water showed that preconditioning at pH 10.4 did not deteriorate the capacity of SIAC to remove bromide, but significantly decreased the release of silver in the form of ionic silver (Ag + ), silver bromide (AgBr) and silver chloride (AgCl) from 40% for the pristine to 3% for the treated SIAC. This was confirmed using a groundwater sample. These results suggest that preconditioned SIAC has the potential to be an effective method for bromide removal with minimised silver leaching in a long-term field application for drinking water production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ultralight Conductive Silver Nanowire Aerogels

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

Qian, Fang; Lan, Pui Ching; Freyman, Megan C.

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/cm 3 and an electrical conductivity up tomore » 51 000 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

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/cm 3 and an electrical conductivity up tomore » 51 000 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

One-Pot Silver Nanoring Synthesis

NASA Astrophysics Data System (ADS)

Drogat, Nicolas; Granet, Robert; Sol, Vincent; Krausz, Pierre

2010-03-01

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV-vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.

One-pot silver nanoring synthesis.

PubMed

Drogat, Nicolas; Granet, Robert; Sol, Vincent; Krausz, Pierre

2009-12-16

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV-vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.

One-Pot Silver Nanoring Synthesis

PubMed Central

2010-01-01

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation. PMID:20672109

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

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.

Subsurface deposition of Cu-rich massive sulphide underneath a Palaeoproterozoic seafloor hydrothermal system—the Red Bore prospect, Western Australia

NASA Astrophysics Data System (ADS)

Agangi, Andrea; Reddy, S. M.; Plavsa, D.; Vieru, C.; Selvaraja, V.; LaFlamme, C.; Jeon, H.; Martin, L.; Nozaki, T.; Takaya, Y.; Suzuki, K.

2018-02-01

The Proterozoic Bryah and Yerrida basins of Western Australia contain important base and precious metal deposits. Here we present microtextural data, trace element and S isotope analyses of massive sulphide mineralisation hosted in Palaeoproterozoic subvolcanic rocks (dolerite) recently discovered at Red Bore. The small-scale high-grade mineralisation, which extends from the sub-surface to at least 95 m down-hole, is dominated by massive chalcopyrite and contains minor pyrite and Bi-Te-(Se) phases. Massive sulphide mineralisation is surrounded by discontinuous brecciated massive magnetite, and a narrow (< 2 m) alteration halo, which suggests very focussed fluid flow. Laser ablation ICP-MS analyses indicate that chalcopyrite contains up to 10 ppm Au and in excess of 100 ppm Ag. Sulphur isotope analyses of pyrite and chalcopyrite indicate a narrow range of δ34SVCD (- 0.2 to + 4.6 ‰), and no significant mass-independent fractionation (- 0.1 < Δ33S < + 0.05 ‰). Re-Os isotope analyses yield scattered values, which suggests secondary remobilisation. Despite the geographical proximity and the common Cu-Au-Ag association, the mineralisation at Red Bore has significant differences with massive sulphide mineralisation at neighbouring DeGrussa, as well as other massive sulphide deposits around the world. These differences include the geometry, sub-volcanic host rocks, extreme Cu enrichment and narrow δ34S ranges. Although a possible explanation for some of these characteristics is leaching of S and metals from the surrounding volcanic rocks, we favour formation as a result of the release of a magmatic fluid phase along very focussed pathways, and we propose that mixing of this fluid with circulating sea water contributed to sea floor mineralisation similar to neighbouring VHMS deposits. Our data are permissive of a genetic association of Red Bore mineralisation with VHMS deposits nearby, thus suggesting a direct connection between magmatism and mineralising fluids

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.

Silver deposition on stainless steel container surfaces in contact with disinfectant silver aqueous solutions

NASA Astrophysics Data System (ADS)

Petala, M.; Tsiridis, V.; Mintsouli, I.; Pliatsikas, N.; Spanos, Th.; Rebeyre, P.; Darakas, E.; Patsalas, P.; Vourlias, G.; Kostoglou, M.; Sotiropoulos, S.; Karapantsios, Th.

2017-02-01

Silver is the preservative used on the Russian segment of the International Space Station (ISS) to prevent microbial proliferation within potable water supplies. Yet, in the frame of the European Automated Transfer Vehicle (ATV) missions to ISS, silver depletion from water has been detected during ground transportation of this water to launch site, thereby indicating a degradation of water quality. This study investigates the silver loss from water when in contact with stainless steel surfaces. Experiments are conducted with several types of stainless steel surfaces being exposed to water containing 10 or 0.5 mg/L silver ions. Results show that silver deposits on stainless steel surfaces even when a passivation layer protects the metallic surface. The highest protection to silver deposition is offered by acid passivated and electropolished SS 316L. SEM and XPS experiments were carried out at several locations of the sample area that was in contact with the Ag solution and found similar morphological (SEM) and compositional (sputter-etch XPS) results. The results reveal that silver deposits uniformly across the wetted surface to a thickness larger than 3 nm. Moreover, evidence is provided that silver deposits in its metallic form on all stainless steel surfaces, in line with a galvanic deposition mechanism. Combination of ICP-MS and XPS results suggests a mechanism for Ag deposition/reduction with simultaneous substrate oxidation resulting in oxide growth at the exposed stainless steel surface.

Synthesis, Characterization, and In Vivo Efficacy of Shell Cross-Linked Nanoparticle Formulations Carrying Silver Antimicrobials as Aerosolized Therapeutics

PubMed Central

2014-01-01

The use of nebulizable, nanoparticle-based antimicrobial delivery systems can improve efficacy and reduce toxicity for treatment of multi-drug-resistant bacteria in the chronically infected lungs of cystic fibrosis patients. Nanoparticle vehicles are particularly useful for applying broad-spectrum silver-based antimicrobials, for instance, to improve the residence time of small-molecule silver carbene complexes (SCCs) within the lung. Therefore, we have synthesized multifunctional, shell cross-linked knedel-like polymeric nanoparticles (SCK NPs) and capitalized on the ability to independently load the shell and core with silver-based antimicrobial agents. We formulated three silver-loaded variants of SCK NPs: shell-loaded with silver cations, core-loaded with SCC10, and combined loading of shell silver cations and core SCC10. All three formulations provided a sustained delivery of silver over the course of at least 2–4 days. The two SCK NP formulations with SCC10 loaded in the core each exhibited excellent antimicrobial activity and efficacy in vivo in a mouse model of Pseudomonas aeruginosa pneumonia. SCK NPs with shell silver cation-load only, while efficacious in vitro, failed to demonstrate efficacy in vivo. However, a single dose of core SCC10-loaded SCK NPs (0.74 ± 0.16 mg Ag) provided a 28% survival advantage over sham treatment, and administration of two doses (0.88 mg Ag) improved survival to 60%. In contrast, a total of 14.5 mg of Ag+ delivered over 5 doses at 12 h intervals was necessary to achieve a 60% survival advantage with a free-drug (SCC1) formulation. Thus, SCK NPs show promise for clinical impact by greatly reducing antimicrobial dosage and dosing frequency, which could minimize toxicity and improve patient adherence. PMID:23718195

Role of manganese dioxide in the recovery of oxide-sulphide zinc ore.

PubMed

Yang, Kun; Zhang, Libo; Zhu, Xingcai; Peng, Jinhui; Li, Shiwei; Ma, Aiyuan; Li, Haoyu; Zhu, Fei

2018-02-05

In this article, the role of MnO 2 in the recovery of oxide-sulphide zinc ore discussed. Through adopting various modern analysis techniques (such as X-ray diffraction pattern, X-ray photoelectron spectroscopy, scanning electron microscope, energy dispersive X-ray analysis, and fourier transform infrared spectroscopy), the function and mechanism of MnO 2 during the phase transformation process is found out. Thermodynamic mechanisms involved in the phase transformation process with or without addition of manganese dioxide investigated by exploiting the Equilib module of FactSage. What's more, XRD patterns, XPS spectra and SEM-EDAX analyses of zinc calcines verify well the calculations of FactSage. Results reveal that the addition of MnO 2 will produce an aggregation of ZnMn 2 O 4 , a valuable energy material, while roasting on its own, results in generating undesirable Zn 2 SiO 4 , the oxidation degree being relatively low. Moreover, XRD pattern of zinc calcine and FT-IR spectrum of yellow product collected in the calcination process prove that the sulphur-fixing value of the additive MnO 2 , which can promote transforming to the elemental sulphur. The volatile S can be collected through a simple guiding device. In this process, the emission of SO 2 effectively avoids, thus MnO 2 deems as a potential additive in the recovery of oxide-sulphide zinc ore. Copyright © 2017. Published by Elsevier B.V.

Reflective Silvered Polyimide Films Via In Situ Thermal Reduction Silver (I) Complexes

NASA Technical Reports Server (NTRS)

Southward, Robin E. (Inventor); Thompson, David W. (Inventor); St.Clair, Anne K. (Inventor); Stoakley, Diane M. (Inventor)

2000-01-01

Self-metallizing. flexible polyimide films with highly reflective surfaces are prepared by an in situ self-metallization procedure involving thermally initiated reduction of polymer-soluble silver(I) complexes. Polyamic acid solutions are doped with silver(I) acetate and solubilizing agents. Thermally curing the silver(I) doped resins leads to flexible. metallized films which have reflectivities as high as 100%. abrasion-resistant surfaces. thermal stability and, in some cases, electrical conductivity, rendering them useful for space applications.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measurements of the optical properties of thin films of silver and silver oxide

NASA Technical Reports Server (NTRS)

Peters, Palmer N.; Sisk, Robert C.; Brown, Yolanda; Gregory, John C.; Nag, Pallob K.; Christl, Ligia

1995-01-01

The optical properties of silver films and their oxides are measured to better characterize such films for use as sensors for atomic oxygen. Good agreement between properties of measured pure silver films and reported optical constants is observed. Similar comparisons for silver oxide have not been possible because of a lack of reported constants, but self-consistencies and discrepancies in our measured results are described.

Quantification of metal loading to Silver Creek through the Silver Maple Claims area, Park City, Utah, May 2002

USGS Publications Warehouse

Kimball, Briant A.; Johnson, Kevin K.; Runkel, Robert L.; Steiger, Judy I.

2004-01-01

The Silver Maple Claims area along Silver Creek, near Park City, Utah, is administered by the Bureau of Land Management. To quantify possible sources of elevated zinc concentrations in Silver Creek that exceed water-quality standards, the U.S. Geological Survey conducted a mass-loading study in May 2002 along a 1,400-meter reach of Silver Creek that included the Silver Maple Claims area. Additional samples were collected upstream and downstream from the injection reach to investigate other possible sources of zinc and other metals to the stream. Many metals were investigated in the study, but zinc is of particular concern for water-quality standards. The total loading of zinc along the study reach from Park City to Wanship, Utah, was about 49 kilograms per day. The Silver Maple Claims area contributed about 38 percent of this load. The Silver Creek tailings discharge pipe, which empties just inside the Silver Maple Claims area, contributed more than half the load of the Silver Maple Claims area. Substantial zinc loads also were added to Silver Creek downstream from the Silver Maple Claims area. Ground-water discharge upstream from the waste-water treatment plant contributed 20 percent of the total zinc load, and another 17 percent was contributed near the waste-water treatment plant. By identifying the specific areas where zinc and other metal loads are contributed to Silver Creek, it is possible to assess the needs of a remediation plan. For example, removing the tailings from the Silver Maple Claims area could contribute to lowering the zinc concentration in Silver Creek, but without also addressing the loading from the Silver Creek tailings discharge pipe and the ground-water discharge farther downstream, the zinc concentration could not be lowered enough to meet water-quality standards. Additional existing sources of zinc loading downstream from the Silver Maple Claims area could complicate the process of lowering zinc concentration to meet water

Percutaneous penetration of silver from a silver containing garment in healthy volunteers and patients with atopic dermatitis.

PubMed

Pluut, Olivier A; Bianco, Carlotta; Jakasa, Ivone; Visser, Maaike J; Krystek, Petra; Larese-Filon, Francesca; Rustemeyer, Thomas; Kezic, Sanja

2015-06-01

Human data on dermal absorption of silver under "in use" scenario are scarce which hampers health risk assessment. The main objective of the present study was to determine percutaneous penetration of silver after dermal exposure to silver containing garment in healthy individuals and atopic dermatitis (AD) patients. Next to assess pro-inflammatory effect of silver in the skin. Healthy subjects (n=15) and patients with AD (n=15) wore a sleeve containing 3.6% (w/w) silver on their lower arms for 8h during 5 consecutive days. The percutaneous penetration parameters were deduced from the silver concentration-depth profiles in the stratum corneum (SC) collected by adhesive tapes. Furthermore, silver was measured in urine samples collected before and after exposure. Inflammatory response was assessed by measuring IL-1α and IL-1RA in the exposed and non-exposed skin sites. Dermal flux of silver in healthy subjects and AD patients was respectively 0.23 and 0.20 ng/cm(2)/h. The urine silver concentrations showed no increase after exposure. Furthermore, exposure to silver did not lead to the changes in the profiles of IL-1α and IL-1RA. Dermal absorption of silver under "real life scenario" was lower than the current reference dose. Furthermore, dermal exposure did not lead to altered expression of inflammatory IL-1 cytokines in the skin. Copyright © 2015. Published by Elsevier Ireland Ltd.

Green synthesis of colloid silver nanoparticles and resulting biodegradable starch/silver nanocomposites.

PubMed

Cheviron, Perrine; Gouanvé, Fabrice; Espuche, Eliane

2014-08-08

Environmentally friendly silver nanocomposite films were prepared by an ex situ method consisting firstly in the preparation of colloidal silver dispersions and secondly in the dispersion of the as-prepared nanoparticles in a potato starch/glycerol matrix, keeping a green chemistry process all along the synthesis steps. In the first step concerned with the preparation of the colloidal silver dispersions, water, glucose and soluble starch were used as solvent, reducing agent and stabilizing agent, respectively. The influences of the glucose amount and reaction time were investigated on the size and size distribution of the silver nanoparticles. Two distinct silver nanoparticle populations in size (diameter around 5 nm size for the first one and from 20 to 50 nm for the second one) were distinguished and still highlighted in the potato starch/glycerol based nanocomposite films. It was remarkable that lower nanoparticle mean sizes were evidenced by both TEM and UV-vis analyses in the nanocomposites in comparison to the respective colloidal silver dispersions. A dispersion mechanism based on the potential interactions developed between the nanoparticles and the polymer matrix and on the polymer chain lengths was proposed to explain this morphology. These nanocomposite film series can be viewed as a promising candidate for many applications in antimicrobial packaging, biomedicines and sensors. Copyright © 2014 Elsevier Ltd. All rights reserved.

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…

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.

Potent antimicrobial and antibiofilm activities of bacteriogenically synthesized gold-silver nanoparticles against pathogenic bacteria and their physiochemical characterizations.

PubMed

Ramasamy, Mohankandhasamy; Lee, Jin-Hyung; Lee, Jintae

2016-09-01

The objective of this study was to develop a bimetallic nanoparticle with enhanced antibacterial activity that would improve the therapeutic efficacy against bacterial biofilms. Bimetallic gold-silver nanoparticles were bacteriogenically synthesized using γ-proteobacterium, Shewanella oneidensis MR-1. The antibacterial activities of gold-silver nanoparticles were assessed on the planktonic and biofilm phases of individual and mixed multi-cultures of pathogenic Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive bacteria (Enterococcus faecalis and Staphylococcus aureus), respectively. The minimum inhibitory concentration of gold-silver nanoparticles was 30-50 µM than that of other nanoparticles (>100 µM) for the tested bacteria. Interestingly, gold-silver nanoparticles were more effective in inhibiting bacterial biofilm formation at 10 µM concentration. Both scanning and transmission electron microscopy results further accounted the impact of gold-silver nanoparticles on biocompatibility and bactericidal effect that the small size and bio-organic materials covering on gold-silver nanoparticles improves the internalization and thus caused bacterial inactivation. Thus, bacteriogenically synthesized gold-silver nanoparticles appear to be a promising nanoantibiotic for overcoming the bacterial resistance in the established bacterial biofilms. © The Author(s) 2016.

21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

Code of Federal Regulations, 2011 CFR

2011-04-01

... ingredients or silver salts offered over-the-counter (OTC) for the treatment and/or prevention of disease. 310...) for the treatment and/or prevention of disease. (a) Colloidal silver ingredients and silver salts have... disease conditions. There are serious and complicating aspects to many of the diseases these silver...

21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

Code of Federal Regulations, 2010 CFR

2010-04-01

... ingredients or silver salts offered over-the-counter (OTC) for the treatment and/or prevention of disease. 310...) for the treatment and/or prevention of disease. (a) Colloidal silver ingredients and silver salts have... disease conditions. There are serious and complicating aspects to many of the diseases these silver...

21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

Code of Federal Regulations, 2013 CFR

2013-04-01

... ingredients or silver salts offered over-the-counter (OTC) for the treatment and/or prevention of disease. 310...) for the treatment and/or prevention of disease. (a) Colloidal silver ingredients and silver salts have... disease conditions. There are serious and complicating aspects to many of the diseases these silver...

21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

Code of Federal Regulations, 2012 CFR

2012-04-01

... ingredients or silver salts offered over-the-counter (OTC) for the treatment and/or prevention of disease. 310...) for the treatment and/or prevention of disease. (a) Colloidal silver ingredients and silver salts have... disease conditions. There are serious and complicating aspects to many of the diseases these silver...

21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

Code of Federal Regulations, 2014 CFR

2014-04-01

... ingredients or silver salts offered over-the-counter (OTC) for the treatment and/or prevention of disease. 310...) for the treatment and/or prevention of disease. (a) Colloidal silver ingredients and silver salts have... disease conditions. There are serious and complicating aspects to many of the diseases these silver...

Sponge-like silver obtained by decomposition of silver nitrate hexamethylenetetramine complex

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

Afanasiev, Pavel, E-mail: pavel.afanasiev@ircelyon.univ-lyon.fr

2016-07-15

Silver nitrate hexamethylenetetramine [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] coordination compound has been prepared via aqueous route and characterized by chemical analysis, XRD and electron microscopy. Decomposition of [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] under hydrogen and under inert has been studied by thermal analysis and mass spectrometry. Thermal decomposition of [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] proceeds in the range 200–250 °C as a self-propagating rapid redox process accompanied with the release of multiple gases. The decomposition leads to formation of sponge-like silver having hierarchical open pore system with pore size spanning from 10 µm to 10 nm. The as-obtained silver spongesmore » exhibited favorable activity toward H{sub 2}O{sub 2} electrochemical reduction, making them potentially interesting as non-enzyme hydrogen peroxide sensors. - Graphical abstract: Thermal decomposition of silver nitrate hexamethylenetetramine coordination compound [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] leads to sponge like silver that possesses open porous structure and demonstrates interesting properties as an electrochemical hydrogen peroxide sensor. Display Omitted - Highlights: • [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] orthorhombic phase prepared and characterized. • Decomposition of [Ag(NO{sub 3})·N{sub 4}(CH{sub 2}){sub 6}] leads to metallic silver sponge with opened porosity. • Ag sponge showed promising properties as a material for hydrogen peroxide sensors.« less

Novel silver-based nanoclay as an antimicrobial in polylactic acid food packaging coatings.

PubMed

Busolo, Maria A; Fernandez, Patricia; Ocio, Maria J; Lagaron, Jose M

2010-11-01

This paper presents a comprehensive performance study of polylactic acid (PLA) biocomposites, obtained by solvent casting, containing a novel silver-based antimicrobial layered silicate additive for use in active food packaging applications. The silver-based nanoclay showed strong antimicrobial activity against Gram-negative Salmonella spp. Despite the fact that no exfoliation of the silver-based nanoclay in PLA was observed, as suggested by transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) experiments, the additive dispersed nicely throughout the PLA matrix to a nanoscale, yielding nanobiocomposites. The films were highly transparent with enhanced water barrier and strong biocidal properties. Silver migration from the films to a slightly acidified water medium, considered an aggressive food simulant, was measured by stripping voltammetry. Silver migration accelerated after 6 days of exposure. Nevertheless, the study suggests that migration levels of silver, within the specific migration levels referenced by the European Food Safety Agency (EFSA), exhibit antimicrobial activity, supporting the potential application of this biocidal additive in active food-packaging applications to improve food quality and safety.

Selective recovery of silver from waste low-temperature co-fired ceramic and valorization through silver nanoparticle synthesis.

PubMed

Swain, Basudev; Shin, Dongyoon; Joo, So Yeong; Ahn, Nak Kyoon; Lee, Chan Gi; Yoon, Jin-Ho

2017-11-01

Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of hybrid nanocomposites polymethylolacrylamide/silver

NASA Astrophysics Data System (ADS)

Kolzunova, L. G.; Shchitovskaya, E. V.; Rodzik, I. G.

2018-05-01

In this study, polymethylolacrylamide/silver composites have been formed by incorporating silver nanoparticles into the pre-electrosynthesized polymer film. The composites were formed in a two-step process involving the sorption of silver nitrate by a polymer matrix followed by chemical reduction of Ag-ions. The presence of crystalline silver phase in the polymer was confirmed by X-ray phase analysis (XRD), plasmon resonance and scanning electron microscopy (SEM). The small-angle X-ray scattering (SAXS) method has obtained the distribution functions of silver particles over radii. It is established that the content of silver in composites without chitosan is 10-15 times higher than with its additive. The dependences of cyclic voltammetry in pure phosphate buffer (pH 6.86) and in the presence of hydrogen peroxide were obtained. It has been shown that polymer/silver composites exhibit selectivity to hydrogen peroxide.

Sulphide-sulphate stability and melting in subducted sediment and its role in arc mantle redox and chalcophile cycling in space and time

NASA Astrophysics Data System (ADS)

Canil, Dante; Fellows, Steven A.

2017-07-01

The redox budget during subduction is tied to the evolution of oxygen and biogeochemical cycles on Earth's surface over time. The sulphide-sulphate couple in subducted crust has significant potential for redox and control on extraction of chalcophile metals from the arc mantle. We derive oxygen buffers for sulphide-sulphate stability ('SSO buffers') using mineral assemblages in subducted crust within the eclogite facies, and examine their disposition relative to the fO2 in the arc mantle along various P-T trajectories for subduction. The fO2 required for sulphide stability in subducted crust passing beneath an arc is shifted by variations in the bulk Ca/(Ca + Mg + Fe) of the subducting crust alone. Hotter slabs and more Fe-rich sediments stabilize sulphide and favour chalcophile sequestration deep into the mantle, whereas colder slabs and calcic sediment will stabilize anhydrite, in some cases at depths of melt generation in the arc mantle (<130 km). The released sulphate on melting potentially increases the fO2 of the arc mantle. We performed melting experiments on three subducted sediment compositions varying in bulk Ca/(Ca + Mg + Fe) from 0.3 to 0.6 at 2.5 GPa and 900-1100 °C to confirm how anhydrite stability can change by orders of magnitude the S, Cu, As, Zn, Mo, Pb, and Sb contents of sediment melts, and their subsequent liberation to the arc mantle. Using Cu/Sc as a proxy for the behaviour of S, the effect of variable subducted sediment composition on sulphide-sulphate stability and release of chalcophiles to the arc mantle is recognizable in volcanic suites from several subduction zones in space and time. The fO2 of the SSO buffers in subducted sediment relative to the arc mantle may have changed with time by shifts in the nature of pelagic sedimentation in the oceans over earth history. Oxidation of arc mantle and the proliferation of porphyry Cu deposits may be latter-day advents in earth history partly due to the rise of planktic calcifiers in the

A novel approach to imaging extinct seafloor massive sulphides (eSMS) by using ocean bottom seismometer data from the Blue Mining project

NASA Astrophysics Data System (ADS)

Gil, A.; Chidlow, K. L.; Vardy, M. E.; Bialas, J.; Schroeder, H.; Stobbs, I. J.; Gehrmann, R. A. S.; North, L. J.; Minshull, T. A.; Petersen, S.; Murton, B. J.

2017-12-01

Seafloor massive sulphide (SMS) deposits have generated great interest regarding their formation and composition, since their discovery in 1977. SMS deposits form through hydrothermal circulation and are therefore commonly found near hydrothermal vent sites. The high base (Cu, Zn) and precious metal (Au, Ag) content has interested mining companies, due to their potentially high economic value. Currently, the possibility of mining extinct seafloor massive sulphides (eSMS) deposits has opened a debate about their environmentally and economically sustainable exploitation. A major goal is the rapid exploration and assessment of deposit structure and volume. This is challenging due to their small dimensions (100s m diameter) and typically great water depths (> 3000 mbsl). Here we present a novel approach combining seismic reflection/refraction forward modelling to data acquired from the TAG hydrothermal field (26ºN, Mid-Atlantic Ridge, 3500mbsl) to image deep-water eSMS deposits. In May 2016, the RV METEOR shot 30, short (<10km) MSC profiles across the TAG area. The data were recorded on a dense cluster (<75 m apart) of ocean bottom seismometers (OBS) and were able to image the subsurface of several 300m diameter eSMS deposits. The results show that the eSMS deposits present high velocities (5.4-6.6 km/s) to depths 200m below the seafloor where they are hosted in a 500m thick low-velocity (3.0-3.7 km/s) layer of altered basalt. In contrast to active hydrothermal systems, we see no evidence in the eSMS of a low-velocity anhydrite layer. The velocity-depth models obtained from this innovative method have been combined with other methods to study these eSMS deposits, such as electromagnetics, rocks physics and drilling technics, and the results are shown to concur, yielding information about deposit structure at depth. For example, the high-velocity layer extends deeper than the conductive layer, indicating a deep stock work of low-connectivity sulphides beneath a main

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...

The silver lining: towards the responsible and limited usage of silver.

PubMed

Naik, K; Kowshik, M

2017-11-01

Silver has attracted a lot of attention as a powerful, broad spectrum and natural antimicrobial agent since the ancient times because of its nontoxic nature to the human body at low concentrations. It has been used in treatment of various infections and ulcers, storage of water and prevention of bacterial growth on the surfaces and within materials. However, there are numerous medical and health benefits of colloidal or nanosilver apart from its microbicidal ability which as yet has not been fully embraced by the medical community. These include antiplatelet activity, antioxidant effect, anticancer activity, wound healing and bone regeneration, enhancement of immunity, and increase in antibiotic efficiency. Additionally silver also provides protection against alcohol toxicity, upper respiratory tract infections and stomach ailments. Although nanosilver has been proposed for various topical applications, its usage by ingestion and inhalation remains controversial due to the lack of detailed and precise toxicity information. These beneficial properties of silver can be utilized by using silver at very low concentrations which are not harmful to the human body and environment. The following review discusses the diverse medical applications of silver and further recommends human clinical studies for its in vivo usage. #x00A9; 2017 The Society for Applied Microbiology.

Antimicrobial activity of biogenic silver nanoparticles, and silver chloride nanoparticles: an overview and comments.

PubMed

Durán, Nelson; Nakazato, Gerson; Seabra, Amedea B

2016-08-01

The antimicrobial impact of biogenic-synthesized silver-based nanoparticles has been the focus of increasing interest. As the antimicrobial activity of nanoparticles is highly dependent on their size and surface, the complete and adequate characterization of the nanoparticle is important. This review discusses the characterization and antimicrobial activity of biogenic synthesized silver nanoparticles and silver chloride nanoparticles. By revising the literature, there is confusion in the characterization of these two silver-based nanoparticles, which consequently affects the conclusion regarding to their antimicrobial activities. This review critically analyzes recent publications on the synthesis of biogenic silver nanoparticles and silver chloride nanoparticles by attempting to correlate the characterization of the nanoparticles with their antimicrobial activity. It was difficult to correlate the size of biogenic nanoparticles with their antimicrobial activity, since different techniques are employed for the characterization. Biogenic synthesized silver-based nanoparticles are not completely characterized, particularly the nature of capped proteins covering the nanomaterials. Moreover, the antimicrobial activity of theses nanoparticles is assayed by using different protocols and strains, which difficult the comparison among the published papers. It is important to select some bacteria as standards, by following international foundations (Pharmaceutical Microbiology Manual) and use the minimal inhibitory concentration by broth microdilution assays from Clinical and Laboratory Standards Institute, which is the most common assay used in antibiotic ones. Therefore, we conclude that to have relevant results on antimicrobial effects of biogenic silver-based nanoparticles, it is necessary to have a complete and adequate characterization of these nanostructures, followed by standard methodology in microbiology protocols.

Application of Cavity Enhanced Absorption Spectroscopy to the Detection of Nitric Oxide, Carbonyl Sulphide, and Ethane--Breath Biomarkers of Serious Diseases.

PubMed

Wojtas, Jacek

2015-06-17

The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with some biomarkers showed that detection of pathogenic changes at the molecular level is possible using this technique. Thanks to cavity enhanced spectroscopy application, detection limits at the ppb-level and short measurements time (<3 s) were achieved. Absorption lines of reference samples of the selected volatile biomarkers were probed using a distributed feedback quantum cascade laser and a tunable laser system consisting of an optical parametric oscillator and difference frequency generator. Setup using the first source provided a detection limit of 30 ppb for nitric oxide and 250 ppb for carbonyl sulphide. During experiments employing a second laser, detection limits of 0.9 ppb and 0.3 ppb were obtained for carbonyl sulphide and ethane, respectively. The conducted experiments show that this type of diagnosis would significantly increase chances for effective therapy of some diseases. Additionally, it offers non-invasive and real time measurements, high sensitivity and selectivity as well as minimizing discomfort for patients. For that reason, such sensors can be used in screening for early detection of serious diseases.

21 CFR 73.2500 - Silver.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver...

21 CFR 73.2500 - Silver.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver...

21 CFR 73.2500 - Silver.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver...

21 CFR 73.2500 - Silver.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver...

21 CFR 73.2500 - Silver.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver...

Mineral resource of the month: silver

USGS Publications Warehouse

Brooks, William E.

2007-01-01

Silver has been used for thousands of years as ornaments and utensils, for trade and as the basis of many monetary systems. The metal has played an important part in world history. Silver from the mines at Laurion, Greece, for example, financed the Greek victory over the Persians in 480 B.C. Silver from Potosi, Bolivia, helped Spain become a world power in the 16th and 17th centuries. And silver from the gold-silver ores at the Comstock Lode in Virginia City, Nev., helped keep the Union solvent during the Civil War.

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.

Characterization of silver nanoparticle-infused tissue adhesive for ophthalmic use.

PubMed

Yee, William; Selvaduray, Guna; Hawkins, Benjamin

2015-03-01

In this work, we demonstrate the successful enhancement of breaking strength, adhesive strength, and antibacterial efficacy of ophthalmic tissue adhesive (2-octyl cyanoacrylate) by doping with silver nanoparticles, and investigate the effects of nanoparticle size and concentration. Recent work has shown that silver nanoparticles are a viable antibacterial additive to many compounds, but their efficacy in tissue adhesives was heretofore untested. Our results indicate that doping the adhesive with silver nanoparticles reduced bacterial growth by an order of magnitude or more; nanoparticle size and concentration had minimal influence in the range tested. Tensile breaking strength of polymerized adhesive samples and adhesive strength between a T-shaped support and excised porcine sclera were measured using a universal testing machine according to ASTM (formerly American Society for Testing and Materials) standard techniques. Both tests showed significant improvement with the addition of silver nanoparticles. The enhanced mechanical strength and antibacterial efficacy of the doped adhesive supports the use of tissue adhesives as a viable supplement or alternative to sutures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Silver nanoparticle-embedded polymersome nanocarriers for the treatment of antibiotic-resistant infections

NASA Astrophysics Data System (ADS)

Geilich, Benjamin M.; van de Ven, Anne L.; Singleton, Gloria L.; Sepúlveda, Liuda J.; Sridhar, Srinivas; Webster, Thomas J.

2015-02-01

The rapidly diminishing number of effective antibiotics that can be used to treat infectious diseases and associated complications in a physician's arsenal is having a drastic impact on human health today. This study explored the development and optimization of a polymersome nanocarrier formed from a biodegradable diblock copolymer to overcome bacterial antibiotic resistance. Here, polymersomes were synthesized containing silver nanoparticles embedded in the hydrophobic compartment, and ampicillin in the hydrophilic compartment. Results showed for the first time that these silver nanoparticle-embedded polymersomes (AgPs) inhibited the growth of Escherichia coli transformed with a gene for ampicillin resistance (bla) in a dose-dependent fashion. Free ampicillin, AgPs without ampicillin, and ampicillin polymersomes without silver nanoparticles had no effect on bacterial growth. The relationship between the silver nanoparticles and ampicillin was determined to be synergistic and produced complete growth inhibition at a silver-to-ampicillin ratio of 1 : 0.64. In this manner, this study introduces a novel nanomaterial that can effectively treat problematic, antibiotic-resistant infections in an improved capacity which should be further examined for a wide range of medical applications.

Preliminary flight prototype silver ion monitoring system

NASA Technical Reports Server (NTRS)

Brady, J.

1974-01-01

The design, fabrication, and testing of a preliminary flight prototype silver ion monitoring system based on potentiometric principles and utilizing a solid-state silver sulfide electrode paired with a pressurized double-junction reference electrode housing a replaceable electrolyte reservoir is described. The design provides automatic electronic calibration utilizing saturated silver bromide solution as a silver ion standard. The problem of loss of silver ion from recirculating fluid, its cause, and corrective procedures are reported. The instability of the silver sulfide electrode is discussed as well as difficulties met in implementing the autocalibration procedure.

Synthesis and characterisation of co-evaporated tin sulphide thin films

NASA Astrophysics Data System (ADS)

Koteeswara Reddy, N.; Ramesh, K.; Ganesan, R.; Ramakrishna Reddy, K. T.; Gunasekhar, K. R.; Gopal, E. S. R.

2006-04-01

Tin sulphide films were grown at different substrate temperatures by a thermal co-evaporation technique. The crystallinity of the films was evaluated from X-ray diffraction studies. Single-phase SnS films showed a strong (040) orientation with an orthorhombic crystal structure and a grain size of 0.12 μm. The films showed an electrical resistivity of 6.1 Ω cm with an activation energy of 0.26 eV. These films exhibited an optical band gap of 1.37 eV and had a high optical absorption coefficient (>104 cm-1) above the band-gap energy. The results obtained were analysed to evaluate the potentiality of the co-evaporated SnS films as an absorber layer in solar photovoltaic devices.

Genetics Home Reference: Russell-Silver syndrome

MedlinePlus

... Facebook Twitter Home Health Conditions Russell-Silver syndrome Russell-Silver syndrome Printable PDF Open All Close All ... Javascript to view the expand/collapse boxes. Description Russell-Silver syndrome is a growth disorder characterized by ...

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.

Brain-Eating Amoebae: Silver Nanoparticle Conjugation Enhanced Efficacy of Anti-Amoebic Drugs against Naegleria fowleri.

PubMed

Rajendran, Kavitha; Anwar, Ayaz; Khan, Naveed Ahmed; Siddiqui, Ruqaiyyah

2017-12-20

The overall aim of this study was to determine whether conjugation with silver nanoparticles enhances effects of available drugs against primary amoebic meningoencephalitis due to Naegleria fowleri. Amphotericin B, Nystatin, and Fluconazole were conjugated with silver nanoparticles, and synthesis was confirmed using UV-visible spectrophotometry. Atomic force microscopy determined their size in range of 20-100 nm. To determine amoebicidal effects, N. fowleri were incubated with drugs-conjugated silver nanoparticles, silver nanoparticles alone, and drugs alone. The findings revealed that silver nanoparticles conjugation significantly enhanced antiamoebic effects of Nystatin and Amphotericin B but not Fluconazole at micromolar concentrations, compared with the drugs alone. For the first time, our findings showed that silver nanoparticle conjugation enhances efficacy of antiamoebic drugs against N. fowleri. Given the rarity of the disease and challenges in developing new drugs, it is hoped that modifying existing drugs to enhance their antiamoebic effects is a useful avenue that holds promise in improving the treatment of brain-eating amoebae infection due to N. fowleri.

Silver nanoparticles with tunable work functions

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

Wang, Pangpang, E-mail: pangpang@molecular-device.kyushu-u.ac.jp; Tanaka, Daisuke; Ryuzaki, Sou

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 probemore » 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.« less

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.

Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

PubMed

Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

2015-07-21

Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (<1%) amounts of translocation of silver into the shoot system. X-ray fluorescence (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

Near-infrared surface-enhanced fluorescence using silver nanoparticles in solution

NASA Astrophysics Data System (ADS)

Furtaw, Michael D.

Fluorescence spectroscopy is a widely used detection technology in many research and clinical assays. Further improvement to assay sensitivity may enable earlier diagnosis of disease, novel biomarker discovery, and ultimately, improved outcomes of clinical care along with reduction in costs. Near-infrared, surface-enhanced fluorescence (NIR-SEF) is a promising approach to improve assay sensitivity via simultaneous increase in signal with a reduction in background. This dissertation describes research conducted with the overall goal to determine the extent to which fluorescence in solution may be enhanced by altering specific variables involved in the formation of plasmon-active nanostructures of dye-labeled protein and silver nanoparticles in solution, with the intent of providing a simple solution that may be readily adopted by current fluorescence users in the life science research community. First, it is shown that inner-filtering, re-absorption of the emitted photons, can red-shift the optimal fluorophore spectrum away from the resonant frequency of the plasmon-active nanostructure. It is also shown that, under certain conditions, the quality factor may be a better indicator of SEF than the commonly accepted overlap of the fluorophore spectrum with the plasmon resonance of the nanostructure. Next, it is determined that streptavidin is the best choice for carrier protein, among the most commonly used dye-labeled detection antibodies, to enable the largest fluorescence enhancement when labeled with IRDye 800CW and used in combination with silver nanoparticles in solution. It is shown that the relatively small and symmetric geometry of streptavidin enables substantial electromagnetic-field confinement when bound to silver nanoparticles, leading to strong and reproducible enhancement. The role of silver nanoparticle aggregation is demonstrated in a droplet-based microfluidic chip and further optimized in a standard microtiter-plate format. A NIR-SEF technology

Addition of platinum and silver nanoparticles to toughen dental porcelain.

PubMed

Fujieda, Tokushi; Uno, Mitsunori; Ishigami, Hajime; Kurachi, Masakazu; Wakamatsu, Nobukazu; Doi, Yutaka

2012-01-01

Several studies have investigated toughening porcelain that is layered over a frame or a core. The introduction of residual compressive stress to the surface of porcelain has been shown to be effective to strengthen it. In the present study, nanoparticles of precious metals of silver and platinum (rather than non-precious metals) were used to evaluate if they could increase the fracture resistance of porcelain. The addition of silver and platinum nanoparticles was found to improve the mechanical properties of porcelain since it increased both the Young's modulus and the fracture toughness of commercial porcelain.

Homogenisation of sulphide inclusions within diamonds: A new approach to diamond inclusion geochemistry

NASA Astrophysics Data System (ADS)

McDonald, Iain; Hughes, Hannah S. R.; Butler, Ian B.; Harris, Jeffrey W.; Muir, Duncan

2017-11-01

Base metal sulphide (BMS) inclusions in diamonds provide a unique insight into the chalcophile and highly siderophile element composition of the mantle. Entombed within their diamond hosts, these provide a more robust (closed system) sample, from which to determine the trace element, Re-Os and S-isotopic compositions of the mantle than mantle xenoliths or orogenic peridotites, as they are shielded from alteration during ascent to the Earth's crust and subsequent surface weathering. However, at temperatures below 1100 °C some BMS inclusions undergo subsolidus re-equilibration from an original monosulphide solid solution (Mss) and this causes fractionation of the major and trace elements within the inclusions. Thus to study the subjects noted above, current techniques require the entire BMS inclusion to be extracted for analyses. Unfortunately, 'flaking' of inclusions during break-out is a frequent occurrence and hence the risk of accidentally under-sampling a portion of the BMS inclusion is inherent in current practices. This loss may have significant implications for Re-Os isotope analyses where incomplete sampling of a Re-rich phase, such as chalcopyrite that typically occurs at the outer margins of BMS inclusions, may induce significant bias in the Re-Os and 187Os/188Os measurements and resulting model and isochron ages. We have developed a method for the homogenisation of BMS inclusions in diamond prior to their break-out from the host stone. Diamonds are heated to 1100 °C and then quenched to chemically homogenise any sulphide inclusions for both major and trace elements. Using X-ray Computed Microtomography (μCT) we determine the shape and spatial setting of multiple inclusions within a host stone and crucially show that the volume of a BMS inclusion is the same both before and after homogenisation. We show that the homogenisation process significantly reduces the inherent variability of in situ analysis when compared with unhomogenised BMS, thereby

Development of silica-encapsulated silver nanoparticles as contrast agents intended for dual-energy mammography.

PubMed

Karunamuni, Roshan; Naha, Pratap C; Lau, Kristen C; Al-Zaki, Ajlan; Popov, Anatoliy V; Delikatny, Edward J; Tsourkas, Andrew; Cormode, David P; Maidment, Andrew D A

2016-09-01

Dual-energy (DE) mammography has recently entered the clinic. Previous theoretical and phantom studies demonstrated that silver provides greater contrast than iodine for this technique. Our objective was to characterize and evaluate in vivo a prototype silver contrast agent ultimately intended for DE mammography. The prototype silver contrast agent was synthesized using a three-step process: synthesis of a silver core, silica encapsulation and PEG coating. The nanoparticles were then injected into mice to determine their accumulation in various organs, blood half-life and dual-energy contrast. All animal procedures were approved by the institutional animal care and use committee. The final diameter of the nanoparticles was measured to be 102 (±9) nm. The particles were removed from the vascular circulation with a half-life of 15 min, and accumulated in macrophage-rich organs such as the liver, spleen and lymph nodes. Dual-energy subtraction techniques increased the signal difference-to-noise ratio of the particles by as much as a factor of 15.2 compared to the single-energy images. These nanoparticles produced no adverse effects in mice. Silver nanoparticles are an effective contrast agent for dual-energy x-ray imaging. With further design improvements, silver nanoparticles may prove valuable in breast cancer screening and diagnosis. • Silver has potential as a contrast agent for DE mammography. • Silica-coated silver nanoparticles are biocompatible and suited for in vivo use. • Silver nanoparticles produce strong contrast in vivo using DE mammography imaging systems.

Fluorescent DNA-templated silver nanoclusters

NASA Astrophysics Data System (ADS)

Lin, Ruoqian

Because of the ultra-small size and biocompatibility of silver nanoclusters, they have attracted much research interest for their applications in biolabeling. Among the many ways of synthesizing silver nanoclusters, DNA templated method is particularly attractive---the high tunability of DNA sequences provides another degree of freedom for controlling the chemical and photophysical properties. However, systematic studies about how DNA sequences and concentrations are controlling the photophysical properties are still lacking. The aim of this thesis is to investigate the binding mechanisms of silver clusters binding and single stranded DNAs. Here in this thesis, we report synthesis and characterization of DNA-templated silver nanoclusters and provide a systematic interrogation of the effects of DNA concentrations and sequences, including lengths and secondary structures. We performed a series of syntheses utilizing five different sequences to explore the optimal synthesis condition. By characterizing samples with UV-vis and fluorescence spectroscopy, we achieved the most proper reactants ratio and synthesis conditions. Two of them were chosen for further concentration dependence studies and sequence dependence studies. We found that cytosine-rich sequences are more likely to produce silver nanoclusters with stronger fluorescence signals; however, sequences with hairpin secondary structures are more capable in stabilizing silver nanoclusters. In addition, the fluorescence peak emission intensities and wavelengths of the DNA templated silver clusters have sequence dependent fingerprints. This potentially can be applied to sequence sensing in the future. However all the current conclusions are not warranted; there is still difficulty in formulating general rules in DNA strand design and silver nanocluster production. Further investigation of more sequences could solve these questions in the future.

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.

Synthesis and characterization of monodispersed silver nanoparticles

NASA Astrophysics Data System (ADS)

Jegatha Christy, A.; Umadevi, M.

2012-09-01

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO3), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM).

Glassy carbon/multi walled carbon nanotube/cadmium sulphide photoanode for light energy storage in vanadium photoelectrochemical cell

NASA Astrophysics Data System (ADS)

Peimanifard, Zahra; Rashid-Nadimi, Sahar

2015-12-01

The aim of this study is utilizing the artificial photosynthesis, which is an attractive and challenging theme in the photoelectrocatalytic water splitting, to charge the vanadium redox flow battery (VRFB). In this work multi walled carbon nanotube/cadmium sulphide hybrid is employed as a photoanode material to oxidize VO2+ toVO2+ for charging the positive vanadium redox flow battery's half-cell. Characterization studies are also described using the scanning electron microscopic-energy-dispersive X-ray spectroscopy (SEM-EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and UV-Visible methods. The phtoelectrochemical performance is characterized by cyclic voltammetry and chronoamperometry. Applied bias photon-to-current efficiency (ABPE) is achieved for both two and three-electrode configurations. The glassy carbon/multi walled carbon nanotube/cadmium sulphide yields high maximum ABPE of 2.6% and 2.12% in three and two-electrode setups, respectively. These results provide a useful guideline in designing photoelectrochemical cells for charging the vanadium redox flow batteries by sunlight as a low cost, free and abundant energy source, which does not rely on an external power input.

Preparation of bismuth stannate/silver@silver chloride film samples with enhanced photocatalytic performance and self-cleaning ability.

PubMed

Zhao, Xiaojuan; Lv, Xiang; Cui, Hongda; Wang, Tianhe

2017-12-01

We report a novel technique to fabricate bismuth stannate/silver@silver chloride (Bi 2 Sn 2 O 7 /Ag@AgCl) films on conventional glass substrates. The film exhibited a remarkable self-cleaning capability against organic dyes under visible light. Porous Bi 2 Sn 2 O 7 (BSO) film was first sintered on a glass substrate, followed by implantation of AgCl in it and photo-induction to produce Ag@AgCl. The degradation of organic dyes and photoelectrochemical studies indicate that, compared with BSO film, Bi 2 Sn 2 O 7 /Ag@AgCl film had a much improved photocatalytic ability, probably due to the enhanced electron transfer efficiency and synergistic effect of visible light absorption of the two semiconductors. The possible mechanism of this marked improvement was investigated and interpreted in terms of electrons and holes separation efficiency and charge circulation routes at the interfaces within the Bi 2 Sn 2 O 7 /Ag@AgCl composite film. The film provided in this study may well have practical applications due to its simplicity of preparation, excellent photocatalytic ability and reasonable stability. Copyright © 2017. Published by Elsevier Inc.

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.

Application of Cavity Enhanced Absorption Spectroscopy to the Detection of Nitric Oxide, Carbonyl Sulphide, and Ethane—Breath Biomarkers of Serious Diseases

PubMed Central

Wojtas, Jacek

2015-01-01

The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with some biomarkers showed that detection of pathogenic changes at the molecular level is possible using this technique. Thanks to cavity enhanced spectroscopy application, detection limits at the ppb-level and short measurements time (<3 s) were achieved. Absorption lines of reference samples of the selected volatile biomarkers were probed using a distributed feedback quantum cascade laser and a tunable laser system consisting of an optical parametric oscillator and difference frequency generator. Setup using the first source provided a detection limit of 30 ppb for nitric oxide and 250 ppb for carbonyl sulphide. During experiments employing a second laser, detection limits of 0.9 ppb and 0.3 ppb were obtained for carbonyl sulphide and ethane, respectively. The conducted experiments show that this type of diagnosis would significantly increase chances for effective therapy of some diseases. Additionally, it offers non-invasive and real time measurements, high sensitivity and selectivity as well as minimizing discomfort for patients. For that reason, such sensors can be used in screening for early detection of serious diseases. PMID:26091398

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.

Uptake and Distribution of Silver in the Aquatic Plant Landoltia punctata (Duckweed) Exposed to Silver and Silver Sulfide Nanoparticles.

PubMed

Stegemeier, John P; Colman, Benjamin P; Schwab, Fabienne; Wiesner, Mark R; Lowry, Gregory V

2017-05-02

Aquatic ecosystems are expected to receive Ag 0 and Ag 2 S nanoparticles (NPs) through anthropogenic waste streams. The speciation of silver in Ag-NPs affects their fate in ecosystems, but its influence on interactions with aquatic plants is still unclear. Here, the Ag speciation and distribution was measured in an aquatic plant, duckweed (Landoltia punctata), exposed to Ag 0 or Ag 2 S NPs, or to AgNO 3 . The silver distribution in duckweed roots was visualized using synchrotron-based micro X-ray fluorescence (XRF) mapping and Ag speciation was determined using extended X-ray absorption fine structure (EXAFS) spectroscopy. Duckweed exposed to Ag 2 S-NPs or Ag 0 -NPs accumulated similar Ag concentrations despite an order of magnitude smaller dissolved Ag fraction measured in the exposure medium for Ag 2 S-NPs compared to Ag 0 -NPs. By 24 h after exposure, all three forms of silver had accumulated on and partially in the roots regardless of the form of Ag exposed to the plants. Once associated with duckweed tissue, Ag 0 -NPs had transformed primarily into silver sulfide and silver thiol species. This suggests that plant defenses were active within or at the root surface. The Ag 2 S-NPs remained as Ag 2 S, while AgNO 3 exposure led to Ag 0 and sulfur-associated Ag species in plant tissue. Thus, regardless of initial speciation, Ag was readily available to duckweed.

Intra‐annual variability of Silver Carp populations in the Des Moines River, USA

USGS Publications Warehouse

Sullivan, Christopher J.; Camacho, Carlos A.; Weber, Michael J.; Pierce, Clay

2017-01-01

Since their introduction in the 1970s, Silver Carp Hypophthalmichthys molitrix have spread throughout the Mississippi River basin. Management of any species relies on an accurate understanding of population characteristics and dynamics. However, Silver Carp seasonal sampling variation is unknown. Sampling during periods of peak catch rates would facilitate Silver Carp assessment and management, improving monitoring and removal techniques. The objective of this study was to evaluate adult Silver Carp seasonal sampling variation with boat electroshocking and trammel nets. Silver Carp were collected monthly (April–October) during 2014 and 2015 from four locations in the Des Moines River, Iowa. Trammel nets rarely captured Silver Carp (mean ± SE = 4.9 ± 1.6 fish/net; 60% of fish were captured in 6.3% of net sets) and therefore were not included in analyses. Electroshocking catch rates (CPUEs) exhibited a bimodal distribution, with peak CPUEs generally occurring in May, June, and September and lower catch rates observed during July and August. Catch rates were positively related to river discharge at upstream sites but not at downstream sites. Silver Carp size structure was similar among months and sites except at Cliffland, where fish were smaller during August and October compared to earlier in the year. Finally, Silver Carp condition peaked during April and May and decreased throughout the year except at Keokuk, where peaks were observed during both May and August. Although spatiotemporal variability was substantial, these results suggest that sampling of Silver Carp via electroshocking in May–June and September–October generally produces higher catch rates compared to July–August sampling and generates a more representative size structure. Using site‐specific knowledge, monitoring and surveillance programs could more effectively sample during these periods of high vulnerability and densities in order to manage the spread and impacts of Silver Carp at

Concurrent In Vitro Release of Silver Sulfadiazine and Bupivacaine From Semi-Interpenetrating Networks for Wound Management

PubMed Central

Kleinbeck, Kyle R.; Bader, Rebecca A.; Kao, Weiyuan John

2013-01-01

In situ photopolymerized semi-interpenetrating networks (sIPNs) composed of poly(ethylene glycol) and gelatin are promising multifunctional matrices for a regenerative medicine approach to dermal wound treatment. In addition to previously demonstrated efficacy in critical defects, sIPNs also function as drug delivery matrices for compounds loaded as either soluble or covalently linked components. Simultaneous release of silver sulfadiazine and bupivacaine from the sIPN would provide multiple-hit management of dermal wounds that minimizes infection, and manages pain along with sIPN absorption of exudates and facilitation of epidermal regrowth. We characterized the release of soluble silver sulfadiazine and bupivacaine and compared it with an established release model. Efficacy of released silver sulfadiazine was confirmed in vitro on Staphylococcus aureus, methicillin resistant S. aureus, and Pseudomonas aeruginosa. Bupivacaine loaded without silver sulfadiazine showed incomplete release, whereas simultaneous loading with silver sulfadiazine facilitated 100% bupivacaine release. Silver sulfadiazine released at 98% without bupivacaine and 96% with bupivacaine. Silver sulfadiazine released onto bacterial cultures inhibited all three strains dose dependently. sIPNs effectively release bupivacaine and silver sulfadiazine while maintaining the antimicrobial activity of silver sulfadiazine. Drug loaded sIPNs have potential to improve wound management by providing multi-drug delivery along with an effective wound treatment. PMID:19060724

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.

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

2018-01-01

The hydrogen sulphide (H 2 S) levels from wastewater treatment plants (WWTPs) in Curitiba, Brazil have been quantified for the first time. H 2 S 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 H 2 S on populations living and/or working near WWTPs. The primary objective of this study was to evaluate the indoor and outdoor concentration of H 2 S 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 H 2 S average concentrations above the WHO recommendation of 10μgm -3 , and 15 points above the US EPA guideline of 2μgm -3 . At WWTP-B the H 2 S concentration was above US EPA guideline at all the sampling points. The I/O ratio on the different sampling sites showed accumulation of indoor H 2 S in some instances and result in exacerbating the exposure of the residents. The highest H 2 S 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.

Carboxylate and amino group coated silver nanoparticles as joining materials for copper-to-copper silver joints.

PubMed

Oestreicher, A; Röhrich, T; Lerch, M

2012-12-01

Organic silver complexes are introduced where silver is linked either with a carboxyl group or with an amino group. Upon heating, nanoparticles are generated if the respective ligands are long enough to act as stabilizing agents in the nanoparticulate regime. With decomposition and volatilization of the organic material, the sintering of silver occurs. The thermal characteristics of the carboxylates silver-n-octanoate, silver-n-decanoate, and AgOOC(CH2OCH2)2CH2OCH3 are compared with silver-n-alkylamines (n = 8, 9, and 12), and their thermal behavior is discussed based on thermogravimetry (TG) measurements. The consecutive stages of a metallization process are addressed based on the properties of AgOOC(CH2OCH2)2CH2OCH3, and the usable effects of the individual phases of this metal organic compound are analyzed by cross-sectional scanning electron microscope (SEM) images of silver joints. Selection criteria are addressed based on the thermal behavior. A mechanism for the joining process is proposed, considering formation and sintering of the nanoparticles. It was found that the bulk material can be used for low-temperature joining processes. Strong adherence to copper as a basic material can be achieved.

Impact of Plasma Surface Treatment on Bamboo Charcoal/silver Nanocomposite

NASA Astrophysics Data System (ADS)

Vignesh, K.; Vijayalakshmi, K. A.; Karthikeyan, N.

2016-10-01

Bamboo charcoal (BC) accompanied silver (Ag) nanocomposite is synthesized through sol-gel method. The produced BC/Ag nanocomposite was surface modified by air and oxygen plasma treatments. Silver ions (Ag+) will serve to improve the antibacterial activity as well as the surface area of BC. Plasma treatment has improved the surface functional groups, crystalline intensity and antibacterial activity of the prepared nanocomposite. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies show that Ag nanoparticles have good agreement with BC and the particle size has a mean diameter of 20-40nm. We observe the carboxyl functional groups in Fourier transform infrared spectroscopy (FTIR) after the oxygen plasma treatment. Moreover surface area and adsorption were analyzed by using the Brunauer, Emmett and Teller (BET) surface area (SBET) and UV-Vis spectroscopy.

Silver ion-mediated killing of a food pathogen: Melting curve analysis data of silver resistance genes and growth curve data.

PubMed

Gokulan, Kuppan; Williams, Katherine; Khare, Sangeeta

2017-04-01

Limited antibacterial activity of silver ions leached from silver-impregnated food contact materials could be due to: 1) the presence of silver resistance genes in tested bacteria ; or 2) lack of susceptibility to silver ion-mediated killing in the bacterial strain (K. Williams, L. Valencia, K. Gokulan, R. Trbojevich, S. Khare, 2016 [1]). This study contains data to address the specificity of silver resistance genes in Salmonella Typhimurium during the real time PCR using melting curve analysis and an assessment of the minimum inhibitory concentration of silver ions for Salmonella .

Anti-inflammatory activity of nanocrystalline silver-derived solutions in porcine contact dermatitis

PubMed Central

2010-01-01

Background Nanocrystalline silver dressings have anti-inflammatory activity, unlike solutions containing Ag+ only, which may be due to dissolution of multiple silver species. These dressings can only be used to treat surfaces. Thus, silver-containing solutions with nanocrystalline silver properties could be valuable for treating hard-to-dress surfaces and inflammatory conditions of the lungs and bowels. This study tested nanocrystalline silver-derived solutions for anti-inflammatory activity. Methods Inflammation was induced on porcine backs using dinitrochlorobenzene. Negative and positive controls were treated with distilled water. Experimental groups were treated with solutions generated by dissolving nanocrystalline silver in distilled water adjusted to starting pHs of 4 (using CO2), 5.6 (as is), 7, and 9 (using Ca(OH)2). Solution samples were analyzed for total silver. Daily imaging, biopsying, erythema and oedema scoring, and treatments were performed for three days. Biopsies were processed for histology, immunohistochemistry (for IL-4, IL-8, IL-10, TNF-α, EGF, KGF, KGF-2, and apoptotic cells), and zymography (MMP-2 and -9). One-way ANOVAs with Tukey-Kramer post tests were used for statistical analyses. Results Animals treated with pH 7 and 9 solutions showed clear visual improvements. pH 9 solutions resulted in the most significant reductions in erythema and oedema scores. pH 4 and 7 solutions also reduced oedema scores. Histologically, all treatment groups demonstrated enhanced re-epithelialisation, with decreased inflammation. At 24 h, pMMP-2 expression was significantly lowered with pH 5.6 and 9 treatments, as was aMMP-2 expression with pH 9 treatments. In general, treatment with silver-containing solutions resulted in decreased TNF-α and IL-8 expression, with increased IL-4, EGF, KGF, and KGF-2 expression. At 24 h, apoptotic cells were detected mostly in the dermis with pH 4 and 9 treatments, nowhere with pH 5.6, and in both the epidermis and dermis

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…

Second-surface silvered glass solar mirrors of very high reflectance

NASA Astrophysics Data System (ADS)

Butel, Guillaume P.; Coughenour, Blake M.; Macleod, H. Angus; Kennedy, Cheryl E.; Olbert, Blain H.; Angel, J. Roger P.

2011-10-01

This paper reports methods developed to maximize the overall reflectance second-surface silvered glass. The reflectance at shorter wavelengths is increased with the aid of a dielectric enhancing layer between the silver and the glass, while at longer wavelengths it is enhanced by use of glass with negligible iron content. The calculated enhancement of reflectance, compared to unenhanced silver on standard low-iron float glass, corresponds to a 4.4% increase in reflectance averaged across the full solar spectrum, appropriate for CSP, and 2.7% for CPV systems using triple junction cells. An experimental reflector incorporating these improvements, of drawn crown glass and a silvered second-surface with dielectric boost, was measured at NREL to have 95.4% solar weighted reflectance. For comparison, non-enhanced, wetsilvered reflectors of the same 4 mm thickness show reflectance ranging from 91.6 - 94.6%, depending on iron content. A potential drawback of using iron-free drawn glass is reduced concentration in high concentration systems because of the inherent surface errors. This effect is largely mitigated for glass shaped by slumping into a concave mold, rather than by bending.

Crossed asymmetry in Russell-Silver syndrome.

PubMed Central

Qazi, Q H; Kassner, E G; Ganapathy, C

1977-01-01

Since the initial report by Silver et al (1953), more than 50 examples of the Russell-Silver syndrome have been reported. Unilateral congenital asymmetry of the extremities has been considered one of the major features of this disorder (Silver, 1964). We recently observed a child with otherwise typical features of the Russell-Silver syndrome who had enlargement of the right hand and of the left lower extremity. We know of no other recorded example of crossed asymmetry in this clinical entity. Images PMID:839508

Silver Recycling in the United States in 2000

USGS Publications Warehouse

Hilliard, Henry E.

2003-01-01

In 2000, the global silver supply deficit (the difference between mine and scrap supply and silver demand) was more than 3,000 metric tons. U.S. silver demand for photographic applications alone was nearly equal to annual U.S. silver production. Until 1968, the U.S. silver deficit was filled by withdrawals from the U.S. Treasury reserves. In 2000, the deficit was filled by destocking, imports, and recycling. Photographic wastes, spent catalysts, and electronic scrap are the major sources of materials for silver recycling. Nearly 1,800 tons of silver contained in these materials were available for recycling in 2000. Other recyclable silver-bearing materials include dental alloys, jewelry, and silverware. In 2000, an estimated 1,700 tons of silver were recovered from secondary sources in the United States. The U.S. recycling efficiency for old scrap was calculated to have been 97 percent in 2000; the recycling rate was estimated to be 32 percent.

Silver recycling in the United States in 2000

USGS Publications Warehouse

Hilliard, Henry E.

2003-01-01

In 2000, the global silver supply deficit (the difference between mine and scrap supply and silver demand) was more than 3,000 metric tons. U.S. silver demand for photographic applications alone was nearly equal to annual U.S. silver production. Until 1968, the U.S. silver deficit was filled by withdrawals from the U.S. Treasury reserves. In 2000, the deficit was filled by destocking, imports, and recycling. Photographic wastes, spent catalysts, and electronic scrap are the major sources of materials for silver recycling. Nearly 1,800 metric tons of silver contained in these materials were available for recycling in 2000. Other recyclable silver-bearing materials include dental alloys, jewelry, and silverware. In 2000, an estimated 1,700 tons of silver were recovered from secondary sources in the United States. The U.S. recycling efficiency for old scrap was calculated to have been 97 percent in 2000; the recycling rate was estimated to be 32 percent.

Study of mechanism of enhanced antibacterial activity by green synthesis of silver nanoparticles

NASA Astrophysics Data System (ADS)

Parashar, Upendra Kumar; Kumar, Vinod; Bera, Tanmay; Saxena, Preeti S.; Nath, Gopal; Srivastava, Sunil K.; Giri, Rajiv; Srivastava, Anchal

2011-10-01

The extensive use of silver nanoparticles needs a synthesis process that is greener without compromising their properties. The present study describes a novel green synthesis of silver nanoparticles using Guava (Psidium guajava) leaf extract. In order to compare with the conventionally synthesized ones, we also prepared Ag-NPs by chemical reduction. Their optical and morphological characteristics were thoroughly investigated and tested for their antibacterial properties on Escherichia coli. The green synthesized silver nanoparticles showed better antibacterial properties than their chemical counterparts even though there was not much difference between their morphologies. Fourier transform infrared (FTIR) spectroscopic analysis of the used extract and as-synthesized silver nanoparticles suggests the possible reduction of Ag + by the water-soluble ingredients of the guava leaf like tannins, eugenol and flavonoids. The possible reaction mechanism for the reduction of Ag + has been proposed and discussed. The time-dependent electron micrographs and the simulation studies indicated that a physical interaction between the silver nanoparticles and the bacterial cell membrane may be responsible for this effect. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is not just an environmentally viable technique but it also opens up scope to improve their antibacterial properties.

Negative pressure and nanocrystalline silver dressings for nonhealing ulcer: A randomized pilot study.

PubMed

Sáez-Martín, Luis C; García-Martínez, Lourdes; Román-Curto, Concepción; Sánchez-Hernández, Miguel V; Suárez-Fernández, Ricardo M

2015-01-01

Chronic wounds have a high prevalence and wound care, treatment, and prevention consume large quantities of resources. Chronic wounds are a growing challenge for clinicians. A prospective randomized pilot study was conducted to assess the effectiveness in terms of reduction in area and safety of the combined use of negative-pressure wound therapy and nanocrystalline silver dressings as compared to negative pressure wound therapy (NPWT) alone in the management of outpatients with chronic wounds. A total of 17 patients were included in the study, 10 were treated with the combined method and 7 with NPWT. Patients were followed for 6 weeks, with a final assessment at 3 months. Clinical improvement, microbiologic data, and toxicity of silver were evaluated. The antibacterial effects of ionic silver together with the development of granulation tissue promoted by NPWT reduced significantly the median extension of the wound between weeks 3 and 6 of treatment. The combination with silver also reduced bacterial colonization with Pseudomonas aeruginosa and the bacterial load on the surface of the wound. The silver levels correlated positively with the extension of the wound, although in none of the patients' toxic levels were reached. The combination of NPWT with nanocrystalline silver dressings was safe and as effective as NPWT alone. © 2015 by the Wound Healing Society.

Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

NASA Astrophysics Data System (ADS)

Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A.; Landero-Figueroa, Julio

2014-10-01

The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV-VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag+) by cation exchange chromatography with 0.5 M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04 mg kg- 1 detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm.

A novel cetyltrimethyl ammonium silver bromide complex and silver bromide nanoparticles obtained by the surfactant counterion.

PubMed

Liu, Xian-Hao; Luo, Xiao-Hong; Lu, Shu-Xia; Zhang, Jing-Chang; Cao, Wei-Liang

2007-03-01

A novel cetyltrimethyl ammonium silver bromide (CTASB) complex has been prepared simply through the reaction of silver nitrate with cetyltrimethyl ammonium bromide (CTAB) in aqueous solution at room temperature by controlling the concentration of CTAB and the molar ratio of CTAB to silver nitrate in the reaction solution, in which halogen in CTAB is used as surfactant counterion. The structure and thermal behavior of cetyltrimethyl ammonium silver bromide have been investigated by using X-ray diffraction (XRD), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), UV/vis spectroscopy, thermal analysis (TG-DTA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results show that the complex possesses a metastable layered structure. Upon heating the CTASB aqueous dispersion to above 80 degrees C, the structure change of the complex took place and CTAB-capped nanosized silver bromide particles further formed.

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

Step-reduced synthesis of starch-silver nanoparticles.

PubMed

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

2016-05-01

In the present process, silver nanoparticles were directly synthesized in a single step by microwave irradiation of a mixture of starch, silver nitrate, and deionized water. This is different from the commonly adopted procedure for starch-silver nanoparticle synthesis in which silver nanoparticles are synthesized by preparing a starch solution as a reaction medium first. Thus, the additional step associated with the preparation of the starch solution was eliminated. In addition, no additional reducing agent was utilized. The adopted method was facile and straight forward, affording spherical silver nanoparticles with diameter below 10nm that exhibited good antibacterial activity. Further, influence of starch on the size of the silver nanoparticles was noticed. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of silver nanoparticles at low temperature

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

Mishra, Mini, E-mail: mishramini5@gmail.com; Chauhan, Pratima, E-mail: mangu167@yahoo.co.in

Silver from ancient time is used as antimicrobial agent in the bulk form but now with the advancement in nanotechnology silver in the form of nanoparticles shown potential effect against microbes which make us easy to fight with many diseases plants and animals. In this work silver nanoparticles were synthesized by chemical routes using sodium borohydride as reducing agent at low temperature. The particles were characterized through UV-Visible spectroscopy as well as X-Ray Diffraction. The UV-visible spectra of silver nanoparticles exhibited absorption at 425 cm; the crystallite size of the particles is between 19nm to 39nm. EDAX graph shows two peaksmore » of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.« less

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.

Influence of pH on optoelectronic properties of zinc sulphide thin films prepared using hydrothermal and spin coating method

NASA Astrophysics Data System (ADS)

Choudapur, V. H.; Bennal, A. S.; Raju, A. B.

2018-04-01

The ZnS nanomaterial is synthesized by hydrothermal method under optimized conditions using Zinc acetate and sodium sulphide as precursors. The Zinc Sulphide thin films are obtained by simple spin coating method with high optical transmittance. The prepared thin films are adhesive and uniform. The x-ray diffraction analysis showed that the films are polycrystalline in cubic phase with the preferred orientation along (111) direction. Current-voltage curves were recorded at room temperature using Keithley 617 programmable electrometer and conductivity is calculated for the film coated on ITO by two probe method. The pH of the solution is varied by using ammonia and hydrochloric acid. The comparative studies of effect of pH on the morphology, crystallanity and optoelectronic properties of the films are studied. It is observed that the pH of the solution has large influence on optoelectronic properties. The thin film prepared with neutral pH has higher crystallanity, bandgap and conductivity as compared to the samples prepared in acidic or basic solutions.

Cycle life test. Evaluation program for secondary spacecraft cells. [performance tests on silver zinc batteries, silver cadmium batteries, and nickel cadmium batteries

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1976-01-01

Considerable research is being done to find more efficient and reliable means of starting electrical energy for orbiting satellites. Rechargeable cells offer one such means. A test program is described which has been established in order to further the evaluation of certain types of cells and to obtain performance and failure data as an aid to their continued improvement. The purpose of the program is to determine the cycling performance capabilities of packs of cells under different load and temperature conditions. The various kinds of cells tested were nickel-cadmium, silver-cadmium, and silver-zinc sealed cells. A summary of the results of the life cycling program is given in this report.

In situ reduction of antibacterial silver ions to metallic silver nanoparticles on bioactive glasses functionalized with polyphenols

NASA Astrophysics Data System (ADS)

Ferraris, S.; Miola, M.; Cochis, A.; Azzimonti, B.; Rimondini, L.; Prenesti, E.; Vernè, E.

2017-02-01

The realization of surfaces with antibacterial properties due to silver nanoparticles loaded through a green approach is a promising research challenge of the biomaterial field. In this research work, two bioactive glasses have been doubly surface functionalized with polyphenols (gallic acid or natural polyphenols extracted from red grape skins and green tea leaves) and silver nanoparticles deposited by in situ reduction from a silver nitrate aqueous solution. The presence of biomolecules - showing reducing ability to directly obtain in situ metallic silver - and silver nanoparticles was investigated by means of UV-vis spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM). The antibacterial activity of the modified surfaces was tested against a multidrug resistant Staphylococcus aureus bacterial strain.

Aligned Layers of Silver Nano-Fibers.

PubMed

Golovin, Andrii B; Stromer, Jeremy; Kreminska, Liubov

2012-02-01

We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polarization of transmitted light. The aligned layers of silver nano-fibers might be used in optics, microwave applications, and organic electronics.

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…

Low-Temperature Properties of Silver

PubMed Central

Smith, David R.; Fickett, F. R.

1995-01-01

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. PMID:29151733

Versatile Molecular Silver Ink Platform for Printed Flexible Electronics.

PubMed

Kell, Arnold J; Paquet, Chantal; Mozenson, Olga; Djavani-Tabrizi, Iden; Deore, Bhavana; Liu, Xiangyang; Lopinski, Gregory P; James, Robert; Hettak, Khelifa; Shaker, Jafar; Momciu, Adrian; Ferrigno, Julie; Ferrand, Olivier; Hu, Jian Xiong; Lafrenière, Sylvie; Malenfant, Patrick R L

2017-05-24

A silver molecular ink platform formulated for screen, inkjet, and aerosol jet printing is presented. A simple formulation comprising silver neodecanoate, ethyl cellulose, and solvent provides improved performance versus that of established inks, yet with improved economics. Thin, screen-printed traces with exceptional electrical (<10 mΩ/□/mil or 12 μΩ·cm) and mechanical properties are achieved following thermal or photonic sintering, the latter having never been demonstrated for silver-salt-based inks. Low surface roughness, submicron thicknesses, and line widths as narrow as 41 μm outperform commercial ink benchmarks based on flakes or nanoparticles. These traces are mechanically robust to flexing and creasing (less than 10% change in resistance) and bind strongly to epoxy-based adhesives. Thin traces are remarkably conformal, enabling fully printed metal-insulator-metal band-pass filters. The versatility of the molecular ink platform enables an aerosol jet-compatible ink that yields conductive features on glass with 2× bulk resistivity and strong adhesion to various plastic substrates. An inkjet formulation is also used to print top source/drain contacts and demonstrate printed high-mobility thin film transistors (TFTs) based on semiconducting single-walled carbon nanotubes. TFTs with mobility values of ∼25 cm 2 V -1 s -1 and current on/off ratios >10 4 were obtained, performance similar to that of evaporated metal contacts in analogous devices.

Argyria secondary to ingestion of homemade silver solution.

PubMed

Brandt, Douglas; Park, Betty; Hoang, Mai; Jacobe, Heidi T

2005-08-01

Argyria is a rare skin disease caused by cutaneous deposition of silver granules in the skin as a result of exposure to silver substrate or ingestion of silver salt. This report describes a patient with generalized argyria caused by ingestion of homemade colloidal silver solution. The patient learned about the uses of the silver solution and its preparation at a convention for "natural medicine."

Photosensitized synthesis of silver nanoparticles using Withania somnifera leaf powder and silver nitrate.

PubMed

Raut, Rajesh Warluji; Mendhulkar, Vijay Damodhar; Kashid, Sahebrao Balaso

2014-03-05

The metal nanoparticle synthesis is highly explored field of nanotechnology. The biological methods seem to be more effective; however, due to slow reduction rate and polydispersity of the resulting products, they are less preferred. In the present study, we report rapid and facile synthesis of silver nanoparticles at room temperature. The exposure of reaction mixtures containing silver nitrate and dried leaf powder of Withania somnifera Linn to direct sunlight resulted in reduction of metal ions within five minutes whereas, the dark exposure took almost 12h. Further studies using different light filters reveal the role of blue light in reduction of silver ions. The synthesized silver nanoparticles were characterized by UV-Vis, Infrared spectroscopy (IR), Transmission Electron Microscopy (TEM), X-ray Diffraction studies (XRD), Nanoparticle Tracking Analysis (NTA), Energy Dispersive Spectroscopy (EDS), and Cyclic Voltammetry (CV). The Antibacterial and antifungal studies showed significant activity as compared to their respective standards. Copyright © 2014 Elsevier B.V. All rights reserved.

Silver ions are responsible for memory impairment induced by oral administration of silver nanoparticles.

PubMed

Węsierska, M; Dziendzikowska, K; Gromadzka-Ostrowska, J; Dudek, J; Polkowska-Motrenko, H; Audinot, J N; Gutleb, A C; Lankoff, A; Kruszewski, M

2018-06-15

Increasing use of silver nanoparticles (AgNPs) results in increased human exposure. AgNPs are able to cross brain-blood barrier and are a risk factor for the brain. Thus, we hypothesized that AgNPs exposure might affect hippocampal dependent memory, which required cognitive coordination processes. To verify the assumption, in this study we evaluated the effects of orally administered bovine serum albumin (BSA)-coated AgNPs on spatial memory, which engage cognitive coordination processes for on-going stimuli segregation. Rats following 28 days of oral administration with 1 mg/kg (n = 10) or 30 mg/kg (n = 10) BSA-AgNPs or saline, a control groups (n = 10, n = 8), were tested with an active place avoidance task in the Carousel Maze test. The study revealed significant impairment of long- and short-term memory, irrespectively of dose of AgNPs, whereas non-cognitive activity was on a similar level. We found significantly higher content of silver in the hippocampus in comparison to the lateral cortex. No silver was found in the cerebellum and the frontal cortex. The nanoSIMS analysis reveal a weak signal of silver in the hippocampus of AgNPs treated animals that should be attributed to the presence of silver in ionic form rather than AgNPs. Our findings indicate that oral exposure to a low dose AgNPs induces detrimental effect on memory and cognitive coordination processes. The presence of silver ions rather than AgNPs in different brain regions, in particular the hippocampus, suggests crucial role of silver ions in AgNPs-induced impairment of the higher brain functions. Copyright © 2018 Elsevier B.V. All rights reserved.

Studying the morphological features of plasma treated silver and PEGylated silver nanoparticles: antibacterial activity

NASA Astrophysics Data System (ADS)

Waseem, M.; Awan, T.; Yasin, H. M.; Rehman, N. U.

2018-03-01

A strategy to treat the silver and PEGylated silver nanoparticles with plasma was being purposed. Oil in water (o/w) microemulsion method was used for the synthesis of Ag nanoparticles (AgNPs). Polyethylene glycol (PEG) having molecular weight 600 was used to coat the surface of AgNPs. Optical emission spectroscopy (OES) was used to characterize the plasma and it is noted that plasma treatment is useful to modify the structural characteristic of silver nanoparticles. The nanoparticles were treated with helium-oxygen mixture plasma, generated in plasma needle at atmospheric pressure. Both AgNPs and PEGylated AgNPs before and after plasma treatment were characterized by x-rays diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The crystallite size of silver nanoparticles after the treatment of plasma decreases from 71 nm to 27 nm. The SEM micrographs show that the size of Ag nanoparticles was nearly 118 nm whereas the thickness of the silver needle was around 135 nm. All the characteristics IR bands associated to the silver nanoparticles were detected. The FTIR spectrum also support the accumulation of OH radicals in the plasma treated samples. The samples before and after plasma treatment were screened against Gram positive (Bacillus Subtilis and Staphylococcus Aureus) and Gram negative (Escherichia Coli and Pseudomonas Aeruginosa) bacteria. The promising response was detected when plasma treated PEGylated AgNPs was tested against bacterial strains.

Testing nano-silver food packaging to evaluate silver migration and food spoilage bacteria on chicken meat.

PubMed

Gallocchio, Federica; Cibin, Veronica; Biancotto, Giancarlo; Roccato, Anna; Muzzolon, Orietta; Carmen, Losasso; Simone, Belluco; Manodori, Laura; Fabrizi, Alberto; Patuzzi, Ilaria; Ricci, Antonia

2016-06-01

Migration of nanomaterials from food containers into food is a matter of concern because of the potential risk for exposed consumers. The aims of this study were to evaluate silver migration from a commercially available food packaging containing silver nanoparticles into a real food matrix (chicken meat) under plausible domestic storage conditions and to test the contribution of such packaging to limit food spoilage bacteria proliferation. Chemical analysis revealed the absence of silver in chicken meatballs under the experimental conditions in compliance with current European Union legislation, which establishes a maximum level of 0.010 mg kg(-1) for the migration of non-authorised substances through a functional barrier (Commission Regulation (EU) No. 10/2011). On the other hand, microbiological tests (total microbial count, Pseudomonas spp. and Enterobacteriaceae) showed no relevant difference in the tested bacteria levels between meatballs stored in silver-nanoparticle plastic bags or control bags. This study shows the importance of testing food packaging not only to verify potential silver migration as an indicator of potential nanoparticle migration, but also to evaluate the benefits in terms of food preservation so as to avoid unjustified usage of silver nanoparticles and possible negative impacts on the environment.

Irradiation of silver and agar/silver nanoparticles with argon, oxygen glow discharge plasma, and mercury lamp.

PubMed

Ahmad, Mahmoud M; Abdel-Wahab, Essam A; El-Maaref, A A; Rawway, Mohammed; Shaaban, Essam R

2014-01-01

The irradiation effect of argon, oxygen glow discharge plasma, and mercury lamp on silver and agar/silver nanoparticle samples is studied. The irradiation time dependence of the synthesized silver and agar/silver nanoparticle absorption spectra and their antibacterial effect are studied and compared. In the agar/silver nanoparticle sample, as the irradiation time of argon glow discharge plasma or mercury lamp increases, the peak intensity and the full width at half maximum, FWHM, of the surface plasmon resonance absorption band is increased, however a decrease of the peak intensity with oxygen glow plasma has been observed. In the silver nanoparticle sample, as the irradiation time of argon, oxygen glow discharge plasma or mercury lamp increases, the peak intensity of the surface plasmon resonance absorption band is increased, however, there is no significant change in the FWHM of the surface plasmon resonance absorption band. The SEM results for both samples showed nanoparticle formation with mean size about 50 nm and 40 nm respectively. Throughout the irradiation time with the argon, oxygen glow discharge plasma or mercury lamp, the antibacterial activity of several kinds of Gram-positive and Gram-negative bacteria has been examined.

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

Synergistic bactericidal activity of chlorhexidine-loaded, silver-decorated mesoporous silica nanoparticles.

PubMed

Lu, Meng-Meng; Wang, Qiu-Jing; Chang, Zhi-Min; Wang, Zheng; Zheng, Xiao; Shao, Dan; Dong, Wen-Fei; Zhou, Yan-Min

2017-01-01

Combination of chlorhexidine (CHX) and silver ions could engender synergistic bactericidal effect and improve the bactericidal efficacy. It is highly desired to develop an efficient carrier for the antiseptics codelivery targeting infection foci with acidic microenvironment. In this work, monodisperse mesoporous silica nanoparticle (MSN) nanospheres were successfully developed as an ideal carrier for CHX and nanosilver codelivery through a facile and environmentally friendly method. The CHX-loaded, silver-decorated mesoporous silica nanoparticles (Ag-MSNs@CHX) exhibited a pH-responsive release manner of CHX and silver ions simultaneously, leading to synergistically antibacterial effect against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli . Moreover, the effective antibacterial concentration of Ag-MSNs@CHX showed less cytotoxicity on normal cells. Given their synergistically bactericidal ability and good biocompatibility, these nanoantiseptics might have effective and broad clinical applications for bacterial infections.

Ink composition for making a conductive silver structure

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

Walker, Steven B.; Lewis, Jennifer A.

An ink composition for making a conductive silver structure comprises a silver salt and a complex of (a) a complexing agent and a short chain carboxylic acid or (b) a complexing agent and a salt of a short chain carboxylic acid, according to one embodiment. A method for making a silver structure entails combining a silver salt and a complexing agent, and then adding a short chain carboxylic acid or a salt of the short chain carboxylic acid to the combined silver salt and a complexing agent to form an ink composition. A concentration of the complexing agent in themore » ink composition is reduced to form a concentrated formulation, and the silver salt is reduced to form a conductive silver structure, where the concentrated formulation and the conductive silver structure are formed at a temperature of about 120.degree. C. or less.« less

Physicochemical properties of protein-modified silver nanoparticles in seawater

NASA Astrophysics Data System (ADS)

Zhong, Hangyue

2013-10-01

This study investigated the physicochemical properties of silver nanoparticles stabilized with casein protein in seawater. UV?vis spectrometry, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were applied to measure the stability of silver nanoparticles in seawater samples. The obtained results show an increased aggregation tendency of silver nanoparticles in seawater, which could be attributed its relatively high cation concentration that could neutralize the negatively charges adsorbed on the surface of silver nanoparticles and reduce the electrostatic repulsion forces between nanoparticles. Similarly, due to the surface charge screening process, the zeta potential of silver nanoparticles in seawater decreased. This observation further supported the aggregation behavior of silver nanoparticles. This study also investigated the dissolution of silver nanoparticles in seawater. Result shows that the silver nanoparticle dissolution in DI water is lower than in seawater, which is attributed to the high Cl? concentration present in seawater. As Cl? can react with silver and form soluble AgCl complex, dissolution of silver nanoparticles was enhanced. Finally, this study demonstrated that silver nanoparticles are destabilized in seawater condition. These results may be helpful in understanding the environmental risk of discharged silver nanoparticles in seawater conditions.

Synthesis and characterization of biopolymer protected zinc sulphide nanoparticles

NASA Astrophysics Data System (ADS)

Senapati, U. S.; Sarkar, D.

2015-09-01

Zinc sulphide (ZnS) nanoparticles are prepared by a simple, economic and green synthesis route. X-ray diffraction patterns confirm zinc blend structure. ZnS formation is confirmed through chemical analysis by energy dispersive analysis of X-rays. Transmission electron microscopy reveals formation of nanosize with dimension in the range of 8-2 nm. Band gap of the nanocrystals is found to lie in the range of 4.51-4.65 eV. Photoluminescence study indicate defect like vacancies. The growth mechanism of ZnS nanoparticles is discussed with the help of Fourier transform infrared spectroscopy and thermogravimetric analysis. The materials show high dielectric constant compared to its bulk counterpart. The dielectric loss of the samples shows anomalous behaviour. The frequency dependent A.C. conductivity of the samples is discussed both in high and low frequency regimes. Current-voltage (I-V) characteristic performed under dark and under illumination, shows excellent light response of the material.

Structural and optical properties of hydrazine hydrate capped cadmium sulphide nanoparticles

NASA Astrophysics Data System (ADS)

Solanki, Rekha Garg; Rajaram, P.

2018-05-01

Semiconductor nanoparticles have received considerable interest due to their size-dependent optical properties. CdS is an important semiconductor material widely used in low cost photovoltaic devices, light-emitting diodes and biological imaging. The nanoparticles of CdS were prepared by a simple chemical precipitation method in aqueous medium. The reaction was carried out at room temperature. The cadmium sulphide nanoparticles were characterized using X-ray powder diffraction (XRD) and UV-visible spectroscopy. The lattice strain, crystallite size and dislocation density were calculated using the Williamson-Hall (W-H) method. The band gap was obtained from the UV-Visible spectra of CdS nanoparticles. The band gap of CdS nanoparticles is around 2.68 eV and the crystallite size is around 5.8 nm.

Enhancement of Single Molecule Fluorescence Signals by Colloidal Silver Nanoparticles in Studies of Protein Translation

PubMed Central

Bharill, Shashank; Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Mandecki, Wlodek; Gryczynski, Ignacy; Gryczynski, Zygmunt; Cooperman, Barry S.; Goldman, Yale E.

2011-01-01

Metal enhanced fluorescence (MEF) increased total photon emission of Cy3- and Cy5-labeled ribosomal initiation complexes near 50 nm silver particles 4- and 5.5-fold respectively. Fluorescence intensity fluctuations above shot noise, at 0.1 – 5 Hz, were greater on silver particles. Overall signal to noise ratio was similar or slightly improved near the particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosome, and tRNA translocation induced by elongation factor G. PMID:21158483

Enhancement of single-molecule fluorescence signals by colloidal silver nanoparticles in studies of protein translation.

PubMed

Bharill, Shashank; Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Mandecki, Wlodek; Gryczynski, Ignacy; Gryczynski, Zygmunt; Cooperman, Barry S; Goldman, Yale E

2011-01-25

Metal-enhanced fluorescence (MEF) increased total photon emission of Cy3- and Cy5-labeled ribosomal initiation complexes near 50 nm silver particles 4- and 5.5-fold, respectively. Fluorescence intensity fluctuations above shot noise, at 0.1-5 Hz, were greater on silver particles. Overall signal-to-noise ratio was similar or slightly improved near the particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosome, and tRNA translocation induced by elongation factor G.

Surface mapping and drilling of extinct seafloor massive sulphide deposits (eSMS) from the TAG Hydrothermal Field, 26oN: A tale of two `Jaspers'

NASA Astrophysics Data System (ADS)

Stobbs, I. J.; Lusty, P.; Petersen, S.; Murton, B. J.

2017-12-01

Two extinct seafloor massive sulphide (eSMS) deposits within the TAG hydrothermal field, 26oN, mid-Atlantic ridge, were mapped and drilled: Southern Mound and the newly discovered `Rona Mound'. Surface mapping was undertaken by combining high definition video footage and high resolution bathymetry to interpret surface geological and geomorphological features. Drill core was recovered using the BGS RD2 robotic drilling rig. Surface mapping of the mounds revealed a superficial cover of carbonate and iron-oxyhydroxides sediments, observed to directly overly oxide coated sulphide material within fault scarps, which dissect the flanks of both mounds. Drilling at the summits of the mounds revealed similar stratigraphy to the mapping, with the addition of a coherent and dense layer of red-coloured silica-rich `jasper', up to 3m thick, underlying the sediments and overlying unoxidised massive sulphides. The jasper mineralogy is dominated by silica, with minor iron oxides and rare disseminated sulphides. It displays a range of complex textures including filamentous and dendritic iron oxides often coated in silica. Drill core samples show the material to be porous, but relatively impermeable. Strong and positive Eu (REE) anomalies indicates a hydrothermal origin with little evidence of a seawater signature (lack of negative Ce anomaly). Silica precipitation is associated with low temperature hydrothermal activity, chert and jasper materials are locally present within the nearby hydrothermally active TAG mound and are more widespread at low-temperature diffuse hydrothermal sites such as within the MESO field. We interpret the `jasper' layers to be a common product, formed during the waning, low temperature, stage of the hydrothermal cycle which may form an impermeable and resistant `cap' that protects the underlying massive sulphide ore body from oxidation and dissolution. The formation of a `jasper cap' could act automatically to preserve eSMS deposits when hydrothermal

In-Situ Silver Acetylide Silver Nitrate Explosive Deposition Measurements Using X-Ray Fluorescence.

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

Covert, Timothy Todd

2014-09-01

The Light Initiated High Explosive facility utilized a spray deposited coating of silver acetylide - silver nitrate explosive to impart a mechanical shock into targets of interest. A diagnostic was required to measure the explosive deposition in - situ. An X - ray fluorescence spectrometer was deployed at the facility. A measurement methodology was developed to measure the explosive quantity with sufficient accuracy. Through the use of a tin reference material under the silver based explosive, a field calibration relationship has been developed with a standard deviation of 3.2 % . The effect of the inserted tin material into themore » experiment configuration has been explored.« less

In vitro caries-inhibitory properties of a silver cermet.

PubMed

Swift, E J

1989-06-01

Recurrent caries is one of the primary causes of failure of dental restorations. One method for reducing the frequency and severity of this problem is the use of fluoride-releasing restorative materials. The glass-ionomer cements are a type of fluoride-releasing material. They have been used extensively in recent years for a variety of clinical applications. However, in comparison with other restorative materials such as amalgam and composite resins, glass ionomers have relatively poor physical properties. Sintering of silver particles to glass-ionomer powder is a means of improving these physical properties. The sintered material is called a silver-glass ionomer or silver cermet. This study examined the in vitro caries-inhibitory potential of a silver cement by means of two methods. First, long-term fluoride release was measured. Second, an artificial caries system was used for evaluation of caries inhibition by cerment restorations in extracted teeth. In comparison with a standard glass-ionomer restorative material, fluoride release from the cermet material was significantly less throughout a 12-month period. The results from the artificial caries system indicated that this decreased fluoride release corresponded with a lesser degree of caries inhibition. Lesions around cermet restorations in both enamel and root surfaces were significantly more severe than those around conventional glass-ionomer restorations. However, in comparison with amalgam and composite resin restorations, the cermet did have some cariostatic activity.

Amphotericin B-conjugated biogenic silver nanoparticles as an innovative strategy for fungal infections.

PubMed

Ahmad, Aftab; Wei, Yun; Syed, Fatima; Tahir, Kamran; Taj, Raheela; Khan, Arif Ullah; Hameed, Muhammad Usman; Yuan, Qipeng

2016-10-01

New strategies are required to improve the efficacy of drugs and to treat the emerging microbial resistance. An effective strategy is to combine drugs with metal nanoparticles for the control of microbial infections and resistance. Keeping in view this fact, we developed a facile and eco-friendly protocol for the synthesis of amphotericin B-conjugated silver nanoparticles and their assessment as an antifungal agent. Phytochemicals from the aqueous extract of Maytenus royleanus and amphotericin B were used as capping agents to prepare two types of silver nanoparticles i.e. (i) biogenic silver nanoparticles (b-AgNPs) and (ii) amphotericin B-conjugated biogenic silver nanoparticles (Amp-bAgNPs). UV-Vis spectroscopy was used to detect the characteristic surface Plasmon resonance peaks (SPR) for the prepared nanoparticles (424-433 nm). High-resolution transmission electron microscopy (HRTEM) study revealed the formation of well dispersed and spherical silver nanoparticles and Amp-bAgNPs with an average particles size of 10 and 15 nm. EDX and FTIR studies confirmed the elemental composition and surface adhered biomolecules in the prepared nanoparticles respectively. Biogenic silver nanoparticles revealed low to moderate antifungal activity (4-8 mm ± 0.2), however, the amphotericin B conjugated silver nanoparticles exhibited significant activity against Candida albicans (16 mm ± 1.4) and Candida tropicalis (18 mm ± 1.5). In conclusion, the enhanced antifungal activity of the Amp-AgNPs conjugate system is due to the synergy between the antifungal activity of amphotericin B and the antimicrobial property of silver. The findings of this study suggest that the conjugated nanoparticles could be used as efficient antifungal agents and drug delivery vehicles. Furthermore, this is the first report describing the synthesis of silver nanoparticles using the aqueous extract of Maytenus royleanus and the conjugation of amphotericin B, an antifungal drug, to the

Effect of curcumin caged silver nanoparticle on collagen stabilization for biomedical applications.

PubMed

Srivatsan, Kunnavakkam Vinjimur; Duraipandy, N; Begum, Shajitha; Lakra, Rachita; Ramamurthy, Usha; Korrapati, Purna Sai; Kiran, Manikantan Syamala

2015-04-01

The current study aims at understanding the influence of curcumin caged silver nanoparticle (CCSNP) on stability of collagen. The results indicated that curcumin caged silver nanoparticles efficiently stabilize collagen, indicated by enhanced tensile strength, fibril formation and viscosity. The tensile strength of curcumin caged silver nanoparticle cross-linked collagen and elongation at break was also found to be higher than glutaraldehyde cross-linked collagen. The physicochemical characteristics of curcumin caged nanoparticle cross-linked collagen exhibited enhanced strength. The thermal properties were also good with both thermal degradation temperature and hydrothermal stability higher than native collagen. CD analysis showed no structural disparity in spite of superior physicochemical properties suggesting the significance of curcumin caged nanoparticle mediated cross-linking. The additional enhancement in the stabilization of collagen could be attributed to multiple sites for interaction with collagen molecule provided by curcumin caged silver nanoparticles. The results of cell proliferation and anti-microbial activity assays indicated that curcumin caged silver nanoparticles promoted cell proliferation and inhibited microbial growth making it an excellent biomaterial for wound dressing application. The study opens scope for nano-biotechnological strategies for the development of alternate non-toxic cross-linking agents facilitating multiple site interaction thereby improving therapeutic values to the collagen for biomedical application. Copyright © 2015 Elsevier B.V. All rights reserved.

Oxic microshield and local pH enhancement protects Zostera muelleri from sediment derived hydrogen sulphide.

PubMed

Brodersen, Kasper Elgetti; Nielsen, Daniel Aagren; Ralph, Peter J; Kühl, Michael

2015-02-01

Seagrass is constantly challenged with transporting sufficient O₂ from above- to belowground tissue via aerenchyma in order to maintain aerobic metabolism and provide protection against phytotoxins. Electrochemical microsensors were used in combination with a custom-made experimental chamber to analyse the belowground biogeochemical microenvironment of Zostera muelleri under changing environmental conditions. Measurements revealed high radial O₂ release of up to 500 nmol O2 cm(-2) h(-1) from the base of the leaf sheath, maintaining a c. 300-μm-wide plant-mediated oxic microzone and thus protecting the vital meristematic regions of the rhizome from reduced phytotoxic metabolites such as hydrogen sulphide (H₂S). H₂S intrusion was prevented through passive diffusion of O₂ to belowground tissue from leaf photosynthesis in light, as well as from the surrounding water column into the flow-exposed plant parts during darkness. Under water column hypoxia, high belowground H₂S concentrations at the tissue surface correlated with the inability to sustain the protecting oxic microshield around the meristematic regions of the rhizome. We also found increased pH levels in the immediate rhizosphere of Z. muelleri, which may contribute to further detoxification of H₂S through shifts in the chemical speciation of sulphide. Zostera muelleri can modify the geochemical conditions in its immediate rhizosphere, thereby reducing its exposure to H₂S. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Synthesis and characterization of lead sulphide thin films from ethanolamine (ETA) complexing agent chemical bath

NASA Astrophysics Data System (ADS)

Gashaw Hone, Fekadu; Dejene, F. B.

2018-02-01

Polycrystalline lead sulphide (PbS) thin films were grown on glass substrates by chemical bath deposition route using ethanolamine (ETA) as a complexing agent. The effects of ETA molar concentration on the structural, morphological, electrical and optical properties of lead sulphide thin films were thoroughly studied. The XRD analyses revealed that all the deposited thin films were face center cubic crystal structure and their preferred orientations were varied along the (111) and (200) planes. The XRD results further confirmed that ETA concentration had a significant effects on the strain, average crystalline size and dislocation density of the deposited thin films. The SEM studies illustrated the evolution and transformation of surface morphology as ETA molar concentration increased from 0.41 M to 1.64 M. The energy dispersive x-ray analysis was used to verify the compositional elements of the deposited thin films. Optical spectroscopy investigation established that the band gap of the PbS thin films were reduced from 0.98 eV to 0.68 eV as ETA concentration increased. The photoluminescence spectra showed a well defined peak at 428 nm and shoulder around 468 nm for all PbS thin films. The electrical resistivity of the thin films found in the order of 103 Ω cm at room temperature and decreased as the ETA molar concentration was increased.

The Electrodeposition of Silver from Supercritical Carbon Dioxide/Acetonitrile

PubMed Central

Bartlett, Philip N; Perdjon-Abel, Magdalena; Cook, David; Reid, Gillian; Levason, William; Cheng, Fei; Zhang, Wenjian; George, Michael W; Ke, Jie; Beanland, Richard; Sloan, Jeremy

2014-01-01

Cyclic voltammetry of silver coordination complexes in acetonitrile and in a single-phase supercritical carbon dioxide/acetonitrile (scCO2/CH3CN) system is reported. Five silver precursors are investigated: (1,5-cyclooctadiene)(hexafluoroacetylacetonato) silver(I) [Ag(hfac)(COD)], (hexafluoroacetylacetonato)(triphenylphosphine) silver(I) [Ag(hfac)(PPh3)], (perfluorooctanoato)bis(triphenylphosphine) silver(I) [Ag(CF3(CF2)6CO2)(PPh3)2], tetrakis(triphenylphosphine) silver(I) tetrafluoroborate [Ag(PPh3)4][BF4] and tetrakis(acetonitrile) silver(I) tetrafluoroborate [Ag(CH3CN)4][BF4]. Of these, [Ag(CH3CN)4][BF4] is found to be the most suitable for electrodeposition of silver from scCO2/CH3CN.

The Myth of the Silver Surfer

ERIC Educational Resources Information Center

Gorard, Stephen; Selwyn, Neil

2008-01-01

In this article, the authors write about the myth of the "silver surfers"--those third-age learners adept at using the internet and other technologies for a mixture of formal and informal learning episodes. The notion of the silver surfer has endured since the latter half of the 1990s. It is sustained by the annual Silver Surfer week, media…

MOD silver metallization for photovoltaics

NASA Technical Reports Server (NTRS)

Vest, G. M.; Vest, R. W.

1985-01-01

The feasibility of utilizing metallo-organic decomposition (MOD) silver inks were investigated for front contact metallization of solar cells. Generic synthesis procedures were developed for all metallo-organic compounds investigated. Silver neodecanoate was found to be the most suitable silver metallo-organic compound for use in thick film inks, but the quality of the inks was found to be highly dependent on its purity. Although neither the process nor inks were completely optimized for solar cell front contact metallization, they show great promise for this application.

Antibacterial properties of nano-silver coated PEEK prepared through magnetron sputtering.

PubMed

Liu, Xiuju; Gan, Kang; Liu, Hong; Song, Xiaoqing; Chen, Tianjie; Liu, Chenchen

2017-09-01

(P<0.01). CCK-8 cytotoxicity test results showed that coated samples did not exhibit cytotoxicity. The antibacterial experimental results showed that the nano-silver coating can significantly improve the antibacterial activity and bacterial adhesion ability of the PEEK samples. The compact and homogeneous nano-silver coating was successfully prepared on the surface of PEEK through magnetron sputtering. The nano-silver coated PEEKs demonstrated enhanced antibacterial activities and bacterial adhesion abilities and had no cytotoxic effects. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Large silver-cadmium technology program

NASA Technical Reports Server (NTRS)

Charlip, S.; Lerner, S.

1971-01-01

The effects of varying cell design on operation factors on the electrochemical performance of sealed, silver-cadmium cells were determined. A factorial experiment was conducted for all test cells constructed with organic separators. Three operating factors were evaluated: temperature, depth of discharge, and charge rate. The six construction factors considered were separator, absorber, electrolyte quantity, cadmium electrode type, cadmium-to-silver ratio, and auxiliary electrode. Test cells of 4 ampere-hour capacity were fabricated and cycled. The best performing cells, on a 94 minute orbit, at 40% depth of discharge, were those containing silver-treated fibrous sausage casings as the separator, and Teflon-ated, pressed cadmium electrodes. Cycling data of cells with inorganic separators (Astroset) are given. Best performance was shown by cells with nonwoven nylon absorbers. Rigid inorganic separators provided the best barrier to silver migration.

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.

Evaluation of dose dependent antimicrobial activity of self-assembled chitosan, nano silver and chitosan-nano silver composite against several pathogens.

PubMed

Tareq, Foysal Kabir; Fayzunnesa, Mst; Kabir, Md Shahariar; Nuzat, Musrat

2018-01-01

The aim of this investigation to preparation of silver nanoparticles organized chitosan nano polymer, which effective against microbial and pathogens, when apply to liquid medium and edible food products surface, will rescue the growth of microbes. Self-assembly approach used to synthesis of silver nanoparticles and silver nanoparticles organized chitosan nano polymer. Silver nanoparticles and silver nanoparticles organized chitosan nano polymer and film characterized using Ultra-violate visible spectrometer (UV-vis), X-ray diffraction (X-ray), and Scanning electronic microscope (SEM). The crystalline structured protein capped nano silver successfully synthesized at range of 12 nm-29 nm and organized into chitosan nano polymer. Antimicrobial ingredient in liquid medium and food product surface provide to rescue oxidative change and growth of microorganism to provide higher safety. The silver nanoparticles organized chitosan nano polymer caused the death of microorganism. The materials in nano scale synthesized successfully using self-assembly method, which showed good antimicrobial properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver Complexes of Dihalogen Molecules.

PubMed

Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

2016-08-01

The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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).

Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles

EPA Science Inventory

Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxic...

Intravenous Exposure of Pregnant Mice to Silver Nanoparticles: Silver Tissue Distribution and Effects in Maternal and Extra-Embryonic Tissues and Embryos

NASA Astrophysics Data System (ADS)

Austin, Carlye Anne

This research explores the tissue distribution of silver, as well as adverse effects in pregnant mice and embryos, following prenatal silver nanoparticle (AgNP) exposure. Chapter one of this dissertation is a survey of the published literature on the reproductive and/or developmental toxicity of AgNPs. The available data indicate that AgNPs adversely affect sperm count, viability, and/or motility both in vivo and in vitro, and cause apoptosis and necrosis in spermatogonial stem cells and testicular cells. Additionally, AgNP exposure results in mortality and morphological deformities in fish embryos, but produces no adverse effects in chicken embryos. The current published research on in vivo AgNP exposure to mammals during gestation consists of only three studies, one of which is described in chapter two of this dissertation. These studies report results that may suggest a potential for adverse effects on fetal development (e.g. , decreased viability and fetal and placental weights, increased incidence of developmentally young embryos), but additional research is needed. Chapter two of this dissertation investigates the distribution of silver in tissues of pregnant mice and gestation day (GD) 10 embryos following intravenous maternal exposure to 50 nm AgNPs during early organogenesis (GDs 7-9). Examinations of embryo morphology and histology were also performed. Results demonstrated the presence of silver in all organs and tissues examined. Silver concentrations were highest in liver, spleen, and visceral yolk sac, and lowest in embryos. Groups of mice were also treated with soluble silver nitrate, and the pattern of silver tissue distribution following silver nitrate exposure was similar to that which followed AgNP treatment. Transmission electron microscopy-energy dispersive x-ray spectroscopy (TEM-EDS) confirmed the presence of vesicle-bound nanoparticulate silver in visceral yolk sac endoderm, but not mesoderm. This finding, along with the high silver

Nickel-silver alloy electrocatalysts for hydrogen evolution and oxidation in an alkaline electrolyte.

PubMed

Tang, Maureen H; Hahn, Christopher; Klobuchar, Aidan J; Ng, Jia Wei Desmond; Wellendorff, Jess; Bligaard, Thomas; Jaramillo, Thomas F

2014-09-28

The development of improved catalysts for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in basic electrolytes remains a major technical obstacle to improved fuel cells, water electrolyzers, and other devices for electrochemical energy storage and conversion. Based on the free energy of adsorbed hydrogen intermediates, theory predicts that alloys of nickel and silver are active for these reactions. In this work, we synthesize binary nickel-silver bulk alloys across a range of compositions and show that nickel-silver alloys are indeed more active than pure nickel for hydrogen evolution and, possibly, hydrogen oxidation. To overcome the mutual insolubility of silver and nickel, we employ electron-beam physical vapor codeposition, a low-temperature synthetic route to metastable alloys. This method also produces flat and uniform films that facilitate the measurement of intrinsic catalytic activity with minimal variations in the surface area, ohmic contact, and pore transport. Rotating-disk-electrode measurements demonstrate that the hydrogen evolution activity per geometric area of the most active catalyst in this study, Ni0.75Ag0.25, is approximately twice that of pure nickel and has comparable stability and hydrogen oxidation activity. Our experimental results are supported by density functional theory calculations, which show that bulk alloying of Ni and Ag creates a variety of adsorption sites, some of which have near-optimal hydrogen binding energy.

Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles.

PubMed

Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

2018-06-22

Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

Effect of Diluent on Ultra-low Temperature Curable Conductive Silver Adhesive

NASA Astrophysics Data System (ADS)

Zhou, Xingli; Wang, Likun; Liao, Qingwei; Yan, Chao; Du, Haibo; Qin, Lei

2018-03-01

The ultra-low temperature curable conductive silver adhesive needed urgently for the surface conductive treatment of piezoelectric composite material. The effect of diluent acetone on ultra-low temperature curable conductive silver adhesive were investigated for surface conductive treatment of piezoelectric composite material. In order to improve the operability and extend the life of the conductive adhesive, the diluent was added to dissolve and disperse conductive adhesive. With the increase of the content of diluent, the volume resistivity of conductive adhesive decreased at first and then increased, and the shear strength increased at first and then decreased. When the acetone content is 10%, the silver flaky bonded together, arranged the neatest, the smallest gap, the most closely connected, the surface can form a complete conductive network, and the volume resistivity is 2.37 × 10-4Ω · cm, the shear strength is 5.13MPa.

Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles

NASA Astrophysics Data System (ADS)

Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

2018-06-01

Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

Synthesis and Characterization of Composite Hydroxyapatite-Silver Nanoparticles

NASA Astrophysics Data System (ADS)

Charlena; Nuzulia, N. A.; Handika

2017-03-01

Hydroxyapatite (HAp) is commonly used as bone implant coating recently; however, the material has disadvantage such as lack of antibacterial properties, that can cause an bacterial infection. Addition of silver nanoparticles is expected to be able to provide antibacterial properties. Silver nanoparticles was obtained by reduction of AgNO3 using glucose monohydrate with microwave heating at 100p for 4 minutes. The composite of hydroxyapatite-silver nanoparticles was synthesized using chemical methods by coprecipitation suspension of Ca(OH)2 with (NH4)HPO4, followed by adding silver nanoparticles solution. The size of the synthesized silver nanoparticles was 30-50 nm and exhibited good antibacterial activity. Nevertheless, when it was composited with HAp to form HAp-AgNPs, there was no antibacterial activity due to very low concentration of silver nanoparticles. This was indicated by the absence of silver nanoparticles diffraction patterns. Infrared spectra indicated the presence of chemical shift and the results of scanning electron microscope showed size of the HAp-AgNPs composite was smaller than that of the HAp. This showed the interaction between HAp and the silver nanoparticles.

Maple leaf (Acer sp.) extract mediated green process for the functionalization of ZnO powders with silver nanoparticles.

PubMed

Vivekanandhan, Singaravelu; Schreiber, Makoto; Mason, Cynthia; Mohanty, Amar Kumar; Misra, Manjusri

2014-01-01

The functionalization of ZnO powders with silver nanoparticles (AgNPs) through a novel maple leaf extract mediated biological process was demonstrated. Maple leaf extract was found to be a very effective bioreduction agent for the reduction of silver ions. The reduction rate of Ag(+) into Ag(0) was found to be much faster than other previously reported bioreduction rates and was comparable to the reduction rates obtained through chemical means. The functionalization of ZnO particles with silver nanoparticles through maple leaf extract mediated bioreduction of silver was investigated through UV-visible spectrophotometry, transmission electron microscopy (TEM), and X-ray diffraction analysis. It was found that the ZnO particles were coated with silver nanoparticles 5-20 nm in diameter. The photocatalytic ability of the ZnO particles functionalized with silver nanoparticles was found to be significantly improved compared to the photocatalytic ability of the neat ZnO particles. The silver functionalized ZnO particles reached 90% degradation of the dye an hour before the neat ZnO particles. Copyright © 2013 Elsevier B.V. All rights reserved.

The effectiveness of silver-releasing dressings in the management of non-healing chronic wounds: a meta-analysis.

PubMed

Lo, Shu-Fen; Chang, Chee-Jen; Hu, Wen-Yu; Hayter, Mark; Chang, Yu-Ting

2009-03-01

The purpose of this study was to examine the efficacy of silver-releasing dressings in the management of non-healing chronic wounds. Non-healing chronic wounds often have a negative physical impact on patients and place a financial burden on healthcare systems. Silver dressings are wound products designed to control infection and provide a wound environment conducive to healing. However, validation of the clinical efficacy of these dressings is lacking. Systematic review and meta-analysis. A systematic search of the major electronic databases PubMed, CINAHL, Cochrane, MEDLINE, British Nursing Index, EBSCO, OCLC and Proquest between 1950-June 2007 was conducted. Hand searches of selected periodicals, textbooks and checking reference lists and contacting experts was also performed. Eight studies were selected from a potentially relevant 1957 references screened. Analysis incorporated data from 1399 participants in the eight randomised control trials. We found that silver dressings significantly improved wound healing (CI(95): 0.16-0.39, p < 0.001), reduced odour (CI(95): 0.24-0.52, p < 0.001) and pain-related symptoms (CI(95): 0.18-0.47, p < 0.001), decreased wound exudates (CI(95): 0.17-0.44, p < 0.001) and had a prolonged dressing wear time (CI(95): 0.19-0.48, p = 0.028) when compared with alternative wound management approaches. An analysis of sensitivity in these studies by subgroup analysis generally supported these associations. Furthermore, studies indicated an improvement in quality of life (CI(95): 0.04-0.33, p = 0.013) using silver dressings in wound management with no associated severe adverse events. This meta-analysis confirms the effectiveness of silver dressings in wound healing and improving patients' quality of life. However, it also highlights the need for additional well-designed randomised controlled trials to evaluate the effectiveness of silver-related dressings further. The results of this study provide objective data on the effectiveness of

Antibacterial Effect of Silver Diamine Fluoride on Cariogenic Organisms.

PubMed

Lou, Yali; Darvell, Brain W; Botelho, Michael G

2018-05-01

To screen the possible antimicrobial activity of a range of clinically used, silver-based compounds on cariogenic organisms: silver diamine fluoride (SDF), silver fluoride, and silver nitrate. Preliminary screening disk-diffusion susceptibility tests were conducted on Mueller-Hinton agar plates inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces naeslundii, organisms known to be cariogenic. In order to identify which component of the silver compounds was responsible for any antibacterial (AB) effect, and to provide controls, the following were also investigated at high and low concentrations: sodium fluoride, ammonium fluoride, ammonium chloride, sodium fluoride, sodium chloride, and sodium nitrate, as well as deionized water as control. A volume of 10 pL of a test solution was dispensed onto a paper disk resting on the inoculated agar surface, and the plate incubated anaerobically at 37°C for 48 hours. The zones of inhibition were then measured. Silver diamine fluoride, silver fluoride, silver nitrate, and ammonium fluoride had significant AB effect (p < 0.05) on all three test organisms, although ammonium fluoride had no effect at low concentration; the remaining other compounds had no effect. Silver ions appear to be the principal AB agent at both high and low concentration; fluoride ions only have an AB effect at high concentration, while ammonium, nitrate, chloride and sodium ions have none. The anticaries effect of topical silver solutions appears restricted to that of the silver ions. Silver compounds, such as SDF, silver fluoride, and silver nitrate have AB effect against cariogenic organisms and these may have clinical impact in arresting or preventing dental decay. Sodium fluoride did not have AB effect under the conditions tested.

Modulators of haemocyanin oxygen affinity in the hypoxia- and sulphide-tolerant Baltic isopod Saduria entomon (L.).

PubMed

Hagerman, L; Vismann, B

2001-11-01

Dialysed haemocyanin from the isopod Saduria entomon had a considerably increased oxygen affinity (lower P50) and Bohr factor (-1.71) compared to native haemocyanin (Bohr factor -1.36) indicating that dialysis removes a small molecule size modulating factor decreasing the affinity of native haemolymph. Dialysed haemocyanin had a slightly lower co-operativity (2.42 +/- 0.3) than native haemocyanin (2.9 +/- 0.2). L-Lactate (10 mmol l(-1)) improved oxygen affinity by 1-1.5 torr while urate had no effect. Mg2+ affected affinity in a pH-dependent manner (Bohr-factor increased to -1.67) while Ca2+ had no effect on the Bohr factor but increased affinity with ca 1 torr. Thiosulphate changed the Bohr factor to -1.75 to -1.82, similar to dialysed blood. Co-operativity was in neither case affected. The haemocyanin characteristics of S. entomon are similar to those of crustaceans from hydrothermal vents. These characteristics are probably general for crustaceans that are more or less permanently exposed to sulphide.

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.

Experimental investigation of sulphur isotope partitioning during outgassing of hydrogen sulphide from diluted aqueous solutions and seawater.

PubMed

Baune, Claudia; Bottcher, Michael E

2010-12-01

The diffusion of hydrogen sulphide across the sediment-water interface and subsequent liberation to the atmosphere may occur in iron-deficient coastal marine environments with enhanced microbial activity in surface sediments and corresponding accumulation of dissolved H2S in near-surface pore waters. The involvement of analogue processes in periods of global mass extinctions during Earth's history (e.g. at the Permian-Triassic boundary) is currently in discussion [L.R. Kump, A. Pavlov, and M. Arthur,Massive Release of Hydrogen Sulfide to the Surface Ocean and Atmosphere During Intervals of Oceanic Anoxia, Geology 33, 397 (2005)]. The outgassing of H₂S is associated with a fractionation of the stable sulphur isotopes, which has so far only been investigated experimentally at selected acidic and neutral pH values, and no experiments with seawater had been carried out. In this communication, we report on sulphur isotope fractionation that takes place during the experimental degassing of H₂S from aqueous solution by an inert gas (N₂) at 21 °C. Experiments were conducted in the pH range between 2.6 and 10.8, corresponding to the dominance fields of dissolved hydrogen sulphide (H₂S(aq)), bisulphide (HS-(aq)), and mixtures of both sulphide species. Overall isotope enrichment factors between -1.6 and +3.0‰ were observed, with the residual dissolved sulphide being enriched or depleted in ³⁴S compared to the liberated H₂S at low and high pH values, respectively. The difference in the low and high pH isotope fractionation effects can be explained by isotope exchange between H₂S(aq) and HS-(aq) [B. Fry, H. Gest, and J.M. Hayes, Sulfur Isotope Effects Associated with Protonation of HS- and Volatilization of H₂S, Chem. Geol. (Isot. Geosci. Sec.) 58, 253 (1986); R. Geßler and K. von Gehlen, Investigation of Sulfur Isotope Fractionation Between H2S Gas and Aqueous Solutions, Fresenius J. Anal. Chem. 324, 130 (1986)] followed by the subsequent transfer of H�

Formation of recent Pb-Ag-Au mineralization by potential sub-surface microbial activity

NASA Astrophysics Data System (ADS)

Tornos, Fernando; Velasco, Francisco; Menor-Salván, César; Delgado, Antonio; Slack, John F.; Escobar, Juan Manuel

2014-08-01

Las Cruces is a base-metal deposit in the Iberian Pyrite Belt, one of the world’s best-known ore provinces. Here we report the occurrence of major Pb-Ag-Au mineralization resulting from recent sub-surface replacement of supergene oxyhydroxides by carbonate and sulphide minerals. This is probably the largest documented occurrence of recent microbial activity producing an ore assemblage previously unknown in supergene mineralizing environments. The presence of microbial features in the sulphides suggests that these may be the first-described natural bacteriomorphs of galena. The low δ13C values of the carbonate minerals indicate formation by deep anaerobic microbial processes. Sulphur isotope values of sulphides are interpreted here as reflecting microbial reduction in a system impoverished in sulphate. We suggest that biogenic activity has produced around 3.1 × 109 moles of reduced sulphur and 1010 moles of CO2, promoting the formation of ca. 1.19 Mt of carbonates, 114,000 t of galena, 638 t of silver sulphides and 6.5 t of gold.

The Hydrometallurgical Extraction and Recovery of High-Purity Silver

NASA Astrophysics Data System (ADS)

Hoffmann, James E.

2012-06-01

With the continuous reduction in the availability of extractive metallurgical curricula in colleges and universities, the concern has in part been from where will the next generation of extractive metallurgists come? One objective of this article is to emphasize the fact that extractive metallurgy is, in fact, one of many areas of chemical engineering technology. Thus, although the extractive metallurgist may have disappeared in name, its activity is alive and well, subsumed in the field of chemical engineering. One goal of this lecture is to demonstrate the applicability of chemical engineering principles to what is typically considered "the field of extractive metallurgy." Two processes will be described that have supplanted typical pyrometallurgical fire refining of precious metals, particularly silver. The origins of fire refining can be traced back to biblical times. There are numerous references to it in the old testament: Ezekiel 22:20, "As men gather silver and bronze and iron and lead and tin into a furnace to blow the fire upon it in order melt it"; Jeremiah 6:29, "The bellows blow fiercely; the lead is consumed by the fire; in vain the refining goes on"; and Malachi 3:2 (The Oxford Annotated Bible with the Apocrypha), "For he is like a refiners fire." Many references to it will also be found in "De Re Metallurgica" and as well in Lazarus Ercker's 1574 Manual "Treatise on Ores and Refining." Today, fire refining has been improved greatly by innovative furnace design, new fluxing technologies, and the improved use of oxygen. However, fundamentally, the process chemistry has not changed much in the last millennium. Illustrations of hydrometallurgical processing of silver-bearing inputs will be provided by the treatment of sulfated silver-bearing materials and chlorinated slimes. The first of these technologies will be described briefly as practiced by the Phelps Dodge Refining Corporation for several years. The second, the treatment of silver chloride

Silver nanocluster catalytic microreactors for water purification

NASA Astrophysics Data System (ADS)

Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

2016-07-01

A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

Passive particle dosimetry. [silver halide crystal growth

NASA Technical Reports Server (NTRS)

Childs, C. B.

1977-01-01

Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

Size Selective Green Synthesis of Silver and Gold Nanoparticles: Enhanced Antibacterial Efficacy of Resveratrol Capped Silver Sol.

PubMed

Shukla, Shashi P; Roy, Mainak; Mukherjee, Poulomi; Das, Laboni; Neogy, Suman; Srivastava, Dinesh; Adhikari, Soumyakanti

2016-03-01

In view of potential biomedical application of the noble metal nanoparticles, we report a size controlled yet simple and green synthesis of resveratrol stabilized silver and gold nanoparticles having low polydispersity of size. Here, resveratrol plays two simultaneous roles, reducing the metal ions and providing efficient capping of the small nanoparticles. This gives rise to specific size of silver and gold nanoparticles at specific ratios of metal to resveratrol. The particles have been characterized by XRD and transmission electron microscopy. The nanoparticle sols are stable for months. The UV Visible absorption spectra of the silver sol show the plasmon peak of spherical nanoparticles, presence of which is further reflected in the TEM images. Size of the silver particles obtained is in between 11 to 21 nm depending on the ratio of resveratrol to metal ion used. Resveratrol capped silver nanoparticles exhibit high antibacterial activity against Gram negative wild type E coli BW (25113). The minimum inhibitory concentration (MIC) of nano-silver against the bacterium has been estimated to be 6.48 μg/ml, which is significantly lower than that reported in some earlier as well as recent publications. Reaction of gold ions with resveratrol, on the other hand, produces gold nanoparticles of sizes varying from 7 to 29 nm at different ratios of resveratrol to the metal ions. Particles with higher size and aspect ratio are formed at lower concentration of the capping agent whereas particles with very small size and pseudo-spherical morphology are formed at higher capping concentration. Difference in the formation kinetics of silver and gold nanoparticles has been attributed to the different growth mechanisms in the two cases. Possible modes of anchorage of resveratrol to silver nanoparticles have been investigated using surface enhanced resonance Raman spectroscopy (SERS) which shows that the silver nanoparticles are capped by resveratrol molecule primarily through O

Adsorption mechanism of physiologically active L-phenylalanine phosphonodipeptide analogues: Comparison of colloidal silver and macroscopic silver substrates

NASA Astrophysics Data System (ADS)

Podstawka, E.; Kudelski, A.; Proniewicz, L. M.

2007-11-01

Here we present SERS spectra of several L-phenylalanine (Phe) phosphonodipeptides, i.e., L-Phe- L-Ala-PO 3H 2 ( MD1), L-Phe- L-Va L-PO 3H 2 ( MD2), L-Phe-β-Ala-CH(OH)-PO 3H 2 ( MD3), L-Phe- L-Ala-CH(OH)-PO 3H 2 ( MD4), L-Ala-(3,4-dimethoxy)- L-Phe-PO 3H 2 ( MD5), and L-Ala-(3,4-dimethoxy)-(des-CH 2)- L-Phe-PO 3H 2 ( MD6), immobilized on electrochemically roughened silver electrodes. These spectra are analyzed by theoretical calculations using density functional theory (DFT) at the B3LYP level with 6-31++G∗∗ basis set. In addition, these spectra are compared with SERS spectra of these species adsorbed on a colloidal silver surface. We showed that on the macroscopic silver substrate, the Phe aromatic ring of MD3 and MD4 is oriented vertically, while for MD1 it almost "stands up" on this surface. In the other three cases, the Phe ring adopts a tilted orientation in regard to the substrate. We also find that the phosphonate (-PO32-), methyl/methane, or dimethoxy groups of MD1, MD2, MD3, MD5, and MD6 are involved in the interaction of these phosphonodipeptides with the electrochemically roughened surface. This phenomenon is clearly seen for -CH 2-/-CH 3/-OCH 3 moieties as well as for the PO32- group that adsorbs on the macroscopic silver substrates mainly via the P dbnd O fragment. We also showed that MD4 binds to the macroscopic silver substrate through the hydroxyl, amine, and phosphonate groups, while the methylene/methane moieties are remote from this surface. We found that studied phosphonodipeptides often adsorb differently on the macroscopic silver substrate and on the colloidal silver nanoparticles. For example, MD1 adopts an almost vertical orientation on the electrochemically roughened silver substrate and is tilted or close to flat on the silver nanoparticles.

In Vivo Interactions Between Cobalt or Ferric Compounds and the Pools of Sulphide in the Blood During and After H2S Poisoning

PubMed Central

Haouzi, Philippe; Sonobe, Takashi; Torsell-Tubbs, Nicole; Prokopczyk, Bogdan; Chenuel, Bruno; Klingerman, Candice M.

2014-01-01

Hydrogen sulphide (H2S), a chemical hazard in oil and gas production, has recently become a dreadful method of suicide, posing specific risks and challenges for the first responders. Currently, there is no proven effective treatment against H2S poisoning and its severe neurological, respiratory or cardiac after-effects. We have recently described that H2S is present in various compartments, or pools, in the body during sulphide exposure, which have different levels of toxicity. The general goals of our study were to (1) determine the concentrations and kinetics of the various pools of hydrogen sulphide in the blood, i.e., gaseous (CgH2S) versus total sulphide, i.e., reacting with monobromobimane (CMBBH2S), during and following H2S exposure in a small and large mammal and (2) establish the interaction between the pools of H2S and a methemoglobin (MetHb) solution or a high dose of hydroxocobalamin (HyCo). We found that CgH2S during and following H2S infusion was similar in sedated sheep and rats at any given rate of infusion/kg and provoked symptoms, i.e., hyperpnea and apnea, at the same CgH2S. After H2S administration was stopped, CgH2S disappeared within 1 min. CMBBH2S also dropped to 2–3μM, but remained above baseline levels for at least 30 min. Infusion of a MetHb solution during H2S infusion produced an immediate reduction in the free/soluble pool of H2S only, whereas CMBBH2S increased by severalfold. HyCo (70 mg/kg) also decreased the concentrations of free/soluble H2S to almost zero; CgH2S returned to pre-HyCo levels within a maximum of 20 min, if H2S infusion is maintained. These results are discussed in the context of a relevant scenario, wherein antidotes can only be administered after H2S exposure. PMID:25015662

Effect of aluminum and yttrium doping on zinc sulphide nanoparticles

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

Sharma, Swati, E-mail: sharma.swati1507@gmail.com; Kashyap, Jyoti; Kapoor, A.

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 Ymore » 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.« less

Synthesis of silver nanoparticle and its application.

PubMed

Pandian, A Muthu Kumara; Karthikeyan, C; Rajasimman, M; Dinesh, M G

2015-11-01

In this work, silver nanoparticles have been synthesized by wet chemical technique, green synthesis and microbial methods. Silver nitrate (10(-3)M) was used with aqueous extract to produce silver nanoparticles. From the results it was observed that the yield of nanoparticles was high in green synthesis. The size of the silver nanoparticles was determined from Scanning Electron Microscope analysis (SEM). Fourier Transform Infrared spectroscopy (FTIR) was carried out to determine the presence of biomolecules in them. Its cytotoxic effect was studied in cancerous cell line and normal cell line. MTT assay was done to test its optimal concentration and efficacy which gives valuable information for the use of silver nanoparticles for future cancer therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

Geochemical characterisation of seepage and drainage water quality from two sulphide mine tailings impoundments: Acid mine drainage versus neutral mine drainage

USGS Publications Warehouse

Heikkinen, P.M.; Raisanen, M.L.; Johnson, R.H.

2009-01-01

Seepage water and drainage water geochemistry (pH, EC, O2, redox, alkalinity, dissolved cations and trace metals, major anions, total element concentrations) were studied at two active sulphide mine tailings impoundments in Finland (the Hitura Ni mine and Luikonlahti Cu mine/talc processing plant). The data were used to assess the factors influencing tailings seepage quality and to identify constraints for water treatment. Changes in seepage water quality after equilibration with atmospheric conditions were evaluated based on geochemical modelling. At Luikonlahti, annual and seasonal changes were also studied. Seepage quality was largely influenced by the tailings mineralogy, and the serpentine-rich, low sulphide Hitura tailings produced neutral mine drainage with high Ni. In contrast, drainage from the high sulphide, multi-metal tailings of Luikonlahti represented typical acid mine drainage with elevated contents of Zn, Ni, Cu, and Co. Other factors affecting the seepage quality included weathering of the tailings along the seepage flow path, process water input, local hydrological settings, and structural changes in the tailings impoundment. Geochemical modelling showed that pH increased and some heavy metals were adsorbed to Fe precipitates after net alkaline waters equilibrated with the atmosphere. In the net acidic waters, pH decreased and no adsorption occurred. A combination of aerobic and anaerobic treatments is proposed for Hitura seepages to decrease the sulphate and metal loading. For Luikonlahti, prolonged monitoring of the seepage quality is suggested instead of treatment, since the water quality is still adjusting to recent modifications to the tailings impoundment.

Rapid Fabrication of Silver Nanowires through Photoreduction of Silver Nitrate from an Anodic-Aluminum-Oxide Template

NASA Astrophysics Data System (ADS)

Lin, Yu-Hsuan; Chen, Kun-Tso; Ho, Jeng-Rong

2011-06-01

A method for rapidly fabricating dense and high-aspect-ratio silver nanowires, with wire diameter of 200 nm and wire length more than 30 µm, is reported. The fabrication process simply involves filling the silver nitrate solution into the pores of an anodic-aluminum-oxide (AAO) membrane through capillary attraction and irradiating the dried template AAO membrane using a pulsed ArF excimer laser. Through varying the thickness and pore diameter of the employed AAO membrane, the primary dimensions of the targeted silver nanowires can be plainly specified; and, by amending the initial concentration of the silver nitrate solution and adjusting the laser operation parameters, laser fluence and number of laser pulses, the surface morphology and size of the resulting nanowires can be finely regulated. The wire formation mechanism is considered through two stages: the period of precipitation of silver particles from the dried silver nitrate film through the laser-induced photoreduction; and, the phase of clustering, merging and fusing of the reduced particles to form nanowires in the template pores by the thermal energy owing to photothermal effect. This approach is straightforward and takes the advantage that all the fabrication processes can be executed in an ambient environment and at room temperature. In addition, by the excellence in local processing that the laser possesses, this method is suitable for precisely growing nanowires.

Synthesis of silver nanoparticles by silver salt reduction and its characterization

NASA Astrophysics Data System (ADS)

Muzamil, Muhammad; Khalid, Naveed; Danish Aziz, M.; Aun Abbas, S.

2014-06-01

The wet chemical method route by metal salt reduction has been used to synthesize nanoparticles, using silver nitrate as an inorganic salt, aldehyde as a reducing agent and amino acid as a catalyst. During the reaction aldehyde oxidizes to carboxylic acid and encapsulates the silver nanoparticles to prevent agglomeration and provide barrier in the growth of particle. The existing work produces particles using lab grade chemical, here the presented work is by using industrial grade chemicals to make the process more cost & time effective. The nano silver powder has been studied for their formation, particle size, shape & compositional analysis using Scanning Electron Microscope (SEM) equipped with EDS. The particles size distributions were analyzed by Laser Particle Analyzer (LPA), structure & morphological analysis using x-ray diffraction (XRD) and Fourier-transform-infrared Spectroscopy (FTIR) confirmed the stabilization of particles by coating of carboxylic group. These studies infer that the particles are mostly spherical in shape and have an average size between 70 to 350 nm.

Electroless silver coating of rod-like glass particles.

PubMed

Moon, Jee Hyun; Kim, Kyung Hwan; Choi, Hyung Wook; Lee, Sang Wha; Park, Sang Joon

2008-09-01

An electroless silver coating of rod-like glass particles was performed and silver glass composite powders were prepared to impart electrical conductivity to these non-conducting glass particles. The low density Ag-coated glass particles may be utilized for manufacturing conducting inorganic materials for electromagnetic interference (EMI) shielding applications and the techniques for controlling the uniform thickness of silver coating can be employed in preparation of biosensor materials. For the surface pretreatment, Sn sensitization was performed and the coating powders were characterized by scanning electron microscopy (SEM), focused ion beam microscopy (FIB), and atomic force microscopy (AFM) along with the surface resistant measurements. In particular, the use of FIB technique for determining directly the Ag-coating thickness was very effective on obtaining the optimum conditions for coating. The surface sensitization and initial silver loading for electroless silver coating could be found and the uniform and smooth silver-coated layer with thickness of 46 nm was prepared at 2 mol/l of Sn and 20% silver loading.

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 )

Sustainable colloidal-silver-impregnated ceramic filter for point-of-use water treatment.

PubMed

Oyanedel-Craver, Vinka A; Smith, James A

2008-02-01

Cylindrical colloidal-silver-impregnated ceramic filters for household (point-of-use) water treatment were manufactured and tested for performance in the laboratory with respect to flow rate and bacteria transport. Filters were manufactured by combining clay-rich soil with water, grog (previously fired clay), and flour, pressing them into cylinders, and firing them at 900 degrees C for 8 h. The pore-size distribution of the resulting ceramic filters was quantified by mercury porosimetry. Colloidal silver was applied to filters in different quantities and ways (dipping and painting). Filters were also tested without any colloidal-silver application. Hydraulic conductivity of the filters was quantified using changing-head permeability tests. [3H]H2O water was used as a conservative tracer to quantify advection velocities and the coefficient of hydrodynamic dispersion. Escherichia coli (E. coli) was used to quantify bacterial transport through the filters. Hydraulic conductivity and pore-size distribution varied with filter composition; hydraulic conductivities were on the order of 10(-5) cm/s and more than 50% of the pores for each filter had diameters ranging from 0.02 to 15 microm. The filters removed between 97.8% and 100% of the applied bacteria; colloidal-silver treatments improved filter performance, presumably by deactivation of bacteria. The quantity of colloidal silver applied per filter was more important to bacteria removal than the method of application. Silver concentrations in effluent filter water were initially greater than 0.1 mg/L, but dropped below this value after 200 min of continuous operation. These results indicate that colloidal-silver-impregnated ceramic filters, which can be made using primarily local materials and labor, show promise as an effective and sustainable point-of-use water treatment technology for the world's poorest communities.

Green synthesis of silver nanoparticle and silver based chitosan bionanocomposite using stem extract of Saccharum officinarum and assessment of its antibacterial activity

NASA Astrophysics Data System (ADS)

Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Pavunraj, Manickam; Annadurai, Gurusamy

2017-09-01

Synthesis of nanoparticles and nanocomposites using green route is a major focus of modern nanotechnology. Herein we demonstrate the synthesis of silver nanoparticle and silver based chitosan bionanocomposite using the stem extract of Saccharum officinarum. The absorbance peak at 460 nm in the UV-Vis spectrum reveals the synthesis of silver nanoparticles using the stem extract of Saccharum officinarum. The size of the synthesized silver nanoparticle was in the range of 10-60 nm obtained from transmission electron microscope (TEM) analysis. The presence of silver nanoparticles on the chitosan suspension was identified by scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS). The presence of possible functional group involved in the reduction of silver metal ions into silver nanoparticles was identified by Fourier transform infrared spectroscopy (FTIR) analysis. The antibacterial activity of the synthesized silver based chitosan bionanocomposite was evaluated against Bacillus subtilis (MTCC 3053), Klebsiella planticola (MTCC 2277), Streptococcus faecalis (ATCC 8043), Pseudomonas aeruginosa (ATCC 9027) and Escherichia coli (ATCC 8739). The antibacterial activity of silver based chitosan bionanocomposite has remarkable scope in medicine, food packaging, textile and pharmaceuticals.

Green chemical synthesis of silver nanomaterials with maltodextrin.

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

Tallant, David Robert; Lu, Ping; Lambert, Timothy N.

2010-11-01

Silver nanomaterials have significant application resulting from their optical properties related to surface enhanced Raman spectroscopy, high electrical conductivity, and anti-microbial impact. A 'green chemistry' synthetic approach for silver nanomaterials minimizes the environmental impact of silver synthesis, as well as lowers the toxicity of the reactive agents. Biopolymers have long been used for stabilization of silver nanomaterials during synthesis, and include gum Arabic, heparin, and common starch. Maltodextrin is a processed derivative of starch with lower molecular weight and an increase in the number of reactive reducing aldehyde groups, and serves as a suitable single reactant for the formation ofmore » metallic silver. Silver nanomaterials can be formed under either a thermal route at neutral pH in water or by reaction at room temperature under more alkaline conditions. Deposited silver materials are formed on substrates from near neutral pH solutions at low temperatures near 50 C. Experimental conditions based on material concentrations, pH and reaction time are investigated for development of deposited films. Deposit morphology and optical properties are characterized using SEM and UV-vis techniques. Silver nanoparticles are generated under alkaline conditions by a dissolution-reduction method from precipitated silver (II) oxide. Synthesis conditions were explored for the rapid development of stable silver nanoparticle dispersions. UV-vis absorption spectra, powder X-ray diffraction (PXRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques were used to characterize the nanoparticle formation kinetics and the influence of reaction conditions. The adsorbed content of the maltodextrin was characterized using thermogravimetric analysis (TGA).« less

The antifungal effect of silver nanoparticles on Trichosporon asahii.

PubMed

Xia, Zhi-Kuan; Ma, Qiu-Hua; Li, Shu-Yi; Zhang, De-Quan; Cong, Lin; Tian, Yan-Li; Yang, Rong-Ya

2016-04-01

Silver nanoparticles are receiving increasing attention in biomedical applications. This study aims at evaluating the antifungal properties of silver nanoparticles against the pathogenic fungus Trichosporon asahii. The growth of T. asahii on potato dextrose agar medium containing different concentrations of silver nanoparticles was examined and the antifungal effect was evaluated using minimum inhibitory concentration. Scanning and transmission electron microscopy were also used to investigate the antifungal effect of silver nanoparticles on T. asahii. Silver nanoparticles had a significant inhibitory effect on the growth of T. asahii. The minimum inhibitory concentration of silver nanoparticles against T. asahii was 0.5 μg/mL, which was lower than amphotericin B, 5-flucytosine, caspofungin, terbinafine, fluconazole, and itraconazole and higher than voriconazole. Silver nanoparticles obviously damaged the cell wall, cell membrane, mitochondria, chromatin, and ribosome. Our results demonstrate that silver nanoparticles have good antifungal activity against T. asahii. Based on our electron microscopy observations, silver nanoparticles may inhibit the growth of T. asahii by permeating the fungal cell and damaging the cell wall and cellular components. Copyright © 2014. Published by Elsevier B.V.

Interference of Steroidogenesis by Gold Nanorod Core/Silver Shell Nanostructures: Implications for Reproductive Toxicity of Silver Nanomaterials.

PubMed

Jiang, Xiumei; Wang, Liming; Ji, Yinglu; Tang, Jinglong; Tian, Xin; Cao, Mingjing; Li, Jingxuan; Bi, Shuying; Wu, Xiaochun; Chen, Chunying; Yin, Jun-Jie

2017-03-01

As a widely used nanomaterial in daily life, silver nanomaterials may cause great concern to female reproductive system as they are found to penetrate the blood-placental barrier and gain access to the ovary. However, it is largely unknown about how silver nanomaterials influence ovarian physiology and functions such as hormone production. This study performs in vitro toxicology study of silver nanomaterials, focusing especially on cytotoxicity and steroidogenesis and explores their underlying mechanisms. This study exposes primary rat granulosa cells to gold nanorod core/silver shell nanostructures (Au@Ag NRs), and compares outcomes with cells exposed to gold nanorods. The Au@Ag NRs generate more reactive oxygen species and reduce mitochondrial membrane potential and less production of adenosine triphosphate. Au@Ag NRs promote steroidogenesis, including progesterone and estradiol, in a time- and dose-dependent manner. Chemical reactivity and transformation of Au@Ag NRs are then studied by electron spin resonance spectroscopy and X-ray absorption near edge structure, which analyze the generation of free radical and intracellular silver species. Results suggest that both particle-specific activity and intracellular silver ion release of Au@Ag NR contribute to the toxic response of granulosa cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In situ green synthesis and characterization of sericin-silver nanoparticle composite with effective antibacterial activity and good biocompatibility.

PubMed

He, Huawei; Tao, Gang; Wang, Yejing; Cai, Rui; Guo, Pengchao; Chen, Liqun; Zuo, Hua; Zhao, Ping; Xia, Qingyou

2017-11-01

Silver nanoparticle has been widely applied to a variety of fields for its outstanding antimicrobial activity. However, the stability of silver nanoparticle limits its application under certain conditions. Thus, improving the stability of silver nanoparticle via biosynthesis is a promising shortcut to expand its application. Sericin from silkworm cocoon has good hydrophilicity, reaction activity, biocompatibility and biodegradability. In this study, we developed a novel, simple, one-step biosynthesis method to prepare sericin-silver nanoparticle composite in situ in solution. Sericin served as the reductant of silver ion, the dispersant and stabilizer of the prepared sericin-silver nanoparticle composite. Natural light was the only power source used to catalyze the synthesis of silver nanoparticle in situ in solution. The novel sericin-silver nanoparticle composite was characterized by ultraviolet-visible and fluorescence spectroscopy, X-ray diffraction, transmission electron microscopy and fourier transform infrared spectroscopy. The results showed silver nanoparticle could be synthesized through the reduction of AgNO 3 by the phenolic hydroxyl group of tyrosine residues of sericin under the catalysis of natural light. The synthesized silver nanoparticle had good crystalline, size distribution and long-term stability at room temperature. Light irradiation was essential for the preparation of sericin-silver nanoparticle composite. The antibacterial activity assay showed 25mg/L and 100mg/L were the minimum concentrations of sericin-silver nanoparticle composite required to inhibit the growth of Staphylococcus aureus and kill this bacterium, respectively. The cytotoxicity assay showed cell viability and cell growth were almost not affected by sericin-silver nanoparticle composite under the concentration of 25mg/L. Our study suggested the preparation of sericin-silver nanoparticle composite was environmentally friendly and energy conservation, and the prepared sericin-silver

Biomedical properties of laser prepared silver-doped hydroxyapatite

NASA Astrophysics Data System (ADS)

Jelínek, M.; Weiserová, M.; Kocourek, T.; Zezulová, M.; Strnad, J.

2011-07-01

Thin films of hydroxyapatite (HA) and silver-doped HA were synthesized using KrF excimer laser deposition. Material was ablated from one target composed from silver and HA segments. Layers properties as silver content, structure, color, FTIR spectra and antibacterial properties (Gram-positive Bacillus subtilis) were measured. Silver concentration in HA layers of 0.06, 0.3, 1.2, 4.4, 8.3, and 13.7 at % was detected. The antibacterial efficacy changed with silver dopation from 71.0 to 99.9%. The focus is on investigation of minimum Ag concentration needed to reach a high antibacterial efficacy.

Occurrence of silver minerals in a silver-rich pocket in the massive sulfide zinc-lead ores in the Edwards mine, New York

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

Serviss, C.R.; Grout, C.M.; Hagni, R.D.

1985-01-01

Ore microscopic examination of uncommon silver-rich ores from the Edwards mine has detected three silver minerals, native silver, freibergite, and argentite, that were previously unreported in the literature from the Balmat-Edwards district. The zinc-lead ore deposits of the Balmat-Edwards District in northern New York are composed of very coarse-grained massive sulfides, principally sphalerite, galena, and pyrite. The typical ores contain small amounts of silver in solid solution galena. Galena concentrates produced from those ores have contained an average of 15 ounces of silver per ton of 60% lead concentrates. In contrast to the typical ore a silver-rich pocket, that measuredmore » three feet by three feet on the vertical mine face and was the subject of this study, contained nearly 1% silver in a zinc ore. Ore microscopic study shows that this ore is especially characterized by abundant, relatively fine-grained chalcopyrite with anhedral pyrite inclusions. Fine-grained sphalerite, native silver, argentite, freibergite and arsenopyrite occur in association with the chalcopyrite and as fracture-fillings in gangue minerals. Geochemically anomalous amounts of tin, barium, chromium, and nickel also are present in the silver-rich pocket. The silver-rich pocket may mark the locus of an early feeder vent or alternatively it may record a hydrothermal event that was superimposed upon the event responsible for the metamorphic ore textures.« less

Environmental Impact on the Northern Persian Gulf: A Mine Drift and Chemical Spill Study Centered on Iraq’s Oil Terminals using Navy’s Ocean-Atmospheric Physical and Chemical Models

DTIC Science & Technology

2007-03-01

acids. Violent reactions are possible. It also readily combines with silver oxide or mercury to form compounds that explode on contact with halogens...soldiers in 1917 (Sidell, et al, 1998). Mustard Gas is chemically called beta-chloroethyl sulphide (C4H8Cl2S) and has the ability to form large blisters

Femtosecond laser structuring of silver-containing glass: Silver redistribution, selective etching, and surface topology engineering

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

Desmoulin, Jean-Charles; Petit, Yannick; Cardinal, Thierry, E-mail: thierry.cardinal@icmcb.cnrs.fr

2015-12-07

Femtosecond direct laser writing in silver-containing phosphate glasses allows for the three-dimensional (3D) implementation of complex photonic structures. Sample translation along or perpendicular to the direction of the beam propagation has been performed, which led to the permanent formation of fluorescent structures, either corresponding to a tubular shape or to two parallel planes at the vicinity of the interaction voxel, respectively. These optical features are related to significant modifications of the local material chemistry. Indeed, silver depletion areas with a diameter below 200 nm were evidenced at the center of the photo-produced structures while photo-produced luminescence properties are attributed to themore » formation of silver clusters around the multiphoton interaction voxel. The laser-triggered oxidation-reduction processes and the associated photo-induced silver redistribution are proposed to be at the origin of the observed original 3D luminescent structures. Thanks to such material structuring, surface engineering has been also demonstrated. Selective surface chemical etching of the glass has been obtained subsequently to laser writing at the location of the photo-produced structures, revealing features with nanometric depth profiles and radial dimensions strongly related to the spatial distributions of the silver clusters.« less

Mechanism of Silver Sulfadiazine Action on Burn Wound Infections

PubMed Central

Fox, Charles L.; Modak, Shanta M.

1974-01-01

The role of silver and sulfadiazine in the mechanism of action of silver sulfadiazine on burn wound infections was investigated. Silver, but not sulfadiazine, was bound by bacteria. Sulfadiazine did not act as an antibacterial agent in low concentrations, but exhibited specific synergism in combination with subinhibitory levels of silver sulfadiazine. The efficacy of silver sulfadiazine is thought to result from its slow and steady reactions with serum and other sodium chloride-containing body fluids, which permits the slow and sustained delivery of silver ions into the wound environs. In this circumstance, a relatively minute amount of sulfadiazine appears active. PMID:15825409

Single-Stroke Synthesis of Tin Sulphide/Oxide Nanocomposites Within Engineering Thermoplastic and Their Humidity Response.

PubMed

Adkar, Dattatraya; Adhyapak, Parag; Mulik, Uttamrao; Jadkar, Sandesh; Vutova, Katia; Amalnerkar, Dinesh

2018-05-01

SnS nanostructured materials have attracted enormous interest due to their important properties and potential application in low cost solar energy conversion systems and optical devices. From the perspective of SnS based device fabrication, we offer single-stroke in-situ technique for the generation of Sn based sulphide and oxide nanostructures inside the polymer network via polymer-inorganic solid state reaction route. In this method, polyphenylene sulphide (PPS)-an engineering thermoplastic-acts as chalcogen source as well as stabilizing matrix for the resultant nano products. Typical solid state reaction was accomplished by simply heating the physical admixtures of the tin salts (viz. tin acetate/tin chloride) with PPS at the crystalline melting temperature (285 °C) of PPS in inert atmosphere. The synthesized products were characterized by using various physicochemical characterization techniques. The prima facie observations suggest the concurrent formation of nanocrystalline SnS with extraneous oxide phase. The TEM analysis revealed formation of nanosized particles of assorted morphological features with polydispersity confined to 5 to 50 nm. However, agglomerated particles of nano to submicron size were also observed. The humidity sensing characterization of these nanocomposites was also performed. The resistivity response with the level of humidity (20 to 85% RH) was compared for these nanocomposites. The linear response was obtained for both the products. Nevertheless, the nanocomposite product obtained from acetate precursor showed higher sensitivity towards the humidity than that of one prepared from chloride precursor.

Plasmonic particles of colloidal silver in high-resolution recording media

NASA Astrophysics Data System (ADS)

Andreeva, O. V.; Andreeva, N. V.; Kuzmina, T. B.

2017-01-01

The optical properties of colloidal silver particles formed photographically in high-resolution silver halide photographic materials have been considered. The conditions that allow one to obtain exposed and developed light-sensitive silver halide particles in the form of colloidal particles of metallic silver having the properties of localized plasmons have been described. The results of the studies of the developed silver particles in traditional photographic materials for image holography and in nanoporous silver halide photographic materials for volume holography have been presented. The perspectives of using plasmonic silver nanoparticles produced photographically have been discussed.

Oxygen isotope exchange with quartz during pyrolysis of silver sulfate and silver nitrate.

PubMed

Schauer, Andrew J; Kunasek, Shelley A; Sofen, Eric D; Erbland, Joseph; Savarino, Joel; Johnson, Ben W; Amos, Helen M; Shaheen, Robina; Abaunza, Mariana; Jackson, Terri L; Thiemens, Mark H; Alexander, Becky

2012-09-30

Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data. Copyright © 2012 John Wiley & Sons, Ltd.

[Design and application of silver needle-knife].

PubMed

Sun, Guodong; Shi, Bin; Zhang, Benwu; Xu, Haidong

2015-04-01

A silver needle-knife which has the dual function of silver needle and needle-knife is designed. The main components of this silver needle-knife are approximately 50% silver and approximately 50% nichrome. The silver needle-knife is composed of five parts, including needle-knife tail, spiral handle; steering handle, needle-knife body and needle-knife edge. It converges the advantages of needle-knife and silver needle, which can cut loose of diseased tissue and peel adhesion of lesions, but also be heated with moxa cone and thermal therapeutic instrument, and connect with electroacupuncture apparatus. It has the function of warming channel and removing coldness, dispelling wind and eliminating dampness, resolving spasm and relieving pain, dredging the channel and so on. Due to the spiral handle and the steering handle, the operation is easier, which reduces the blindness of cutting and increase the safety. It is mainly used for soft tissue injury, rheumatism and rheumatoid arthritis, as well as degenerative diseases of spine and joint, and it has obvious efficacy on some internal medical diseases.

Control of in vitro rooting and plant development in Corymbia maculata by silver nitrate, silver thiosulfate and thiosulfate ion.

PubMed

Steinitz, Benjamin; Barr, Nurit; Tabib, Yona; Vaknin, Yiftach; Bernstein, Nirit

2010-11-01

Plant regeneration and transformation in vitro is often improved by adding silver ion (Ag(+)) to the culture media as AgNO(3) or silver thiosulfate (STS). Ag(+) reacts with substances to form insoluble precipitates, while thiosulfate (S(2)O(3) (2-)) interferes with these reactions. We studied the implications of silver precipitation and S(2)O(3) (2-) in the medium for culture development by (1) examining formation of Ag(+) precipitates from AgNO(3) versus STS in agar gels and their possible dependence on agar type; (2) comparing Corymbia maculata culture responses to AgNO(3) and STS and determining which better suits control of culture development; (3) clarifying whether STS-dependent alterations in culture development are due to Ag(+) alone or also to a separate influence of S(2)O(3) (2-). Silver precipitates appeared in aqueous gels of four agar brands supplemented with AgNO(3), but not in Phytagel(™), which remained transparent. No precipitation was observed in gels with STS. Indole-3-butyric acid (IBA)-mediated adventitious root induction and shoot growth were higher in C. maculata shoot tips cultured on gels with STS versus AgNO(3) (6-25 μM Ag(+)). IBA-treated shoot tips exhibited enhanced adventitious root regeneration, accelerated root elongation, increased frequency of lateral root formation, and stimulated shoot growth mediated by 100-250 μM sodium thiosulfate (Na(2)S(2)O(3)) in medium without Ag(+). The potency of S(2)O(3) (2-) in facilitating culture development has never been recognized. It is inferred that superiority of STS in stimulating multiple responses of C. maculata culture results from sustained biological activity of Ag(+) through prevention of its precipitation, and from impact of S(2)O(3) (2-) on cell differentiation and growth.

Silver in medicine: a brief history BC 335 to present.

PubMed

Barillo, David J; Marx, David E

2014-12-01

Silver is a naturally occurring element. Similar to other metals, the ionized form of silver (Ag(+1)) has known antimicrobial properties. A number of wound dressings incorporating silver ion or silver compounds have recently been developed and marketed. In addition, the antimicrobial effects of silver are currently being promoted in consumer products such as clothing and household appliances. The present use of silver in medical and consumer products has prompted concerns for potential toxicity and ecological effects, including induction of microbial resistance to antibiotics. These concerns ignore the fact that silver has been used for medicinal purposes for several thousand years. A historical review of the uses of silver in medicine is presented.

Synthesis and characterization of colloidal fluorescent silver nanoclusters.

PubMed

Huang, Sherry; Pfeiffer, Christian; Hollmann, Jana; Friede, Sebastian; Chen, Justin Jin-Ching; Beyer, Andreas; Haas, Benedikt; Volz, Kerstin; Heimbrodt, Wolfram; Montenegro Martos, Jose Maria; Chang, Walter; Parak, Wolfgang J

2012-06-19

Ultrasmall water-soluble silver nanoclusters are synthesized, and their properties are investigated. The silver nanoclusters have high colloidal stability and show fluorescence in the red. This demonstrates that like gold nanoclusters also silver nanoclusters can be fluorescent.

Chronic effects of silver exposure on ion levels, survival, and silver distribution within developing rainbow trout (Oncorhynchus mykiss) embryos.

PubMed

Guadagnolo, C M; Brauner, C J; Wood, C M

2001-03-01

Rainbow trout embryos were chronically exposed to silver (as AgNO3) in moderately hard water (120 mg CaCO3/L, 0.70 mM Cl-, 1.3 mg/L dissolved organic matter. 12.3+/-0.1 degrees C) at nominal concentrations of 0.1, 1, and 10 microg/L (measured = 0.117+/-0.008, 1.22+/-0.16, and 13.51+/-1.58 microg/L, respectively) to investigate the effects on mortality, ionoregulation, and silver uptake and distribution of the embryo. Mortalities in the low concentrations (0.1 and 1.2 microg/L) were not significantly different from controls throughout embryonic development (days 1-32 postfertilization). Mortalities of embryos in the 13.5-microg/L treatment reached 56% by day 32 postfertilization (33% when accounting for control mortality), by which time more than 50% of surviving embryos had hatched. Accumulation of silver in whole embryos of 1.2- and 13.5-microg/L treatments reached the highest concentrations of 0.13 and 0.24 microg/g total silver, respectively, by day 32, but whole embryo silver burden was not correlated with mortality. Silver concentrations in different compartments of the whole embryo (chorion, dissected embryo, and yolk) were greatest just before hatch and were higher in the chorion for all experimental treatments. Up to 85% of total whole embryo silver content was bound to the chorion, which acts as a protective barrier during silver exposure. Whole embryo Na+ concentration in the 13.5-microg/L treatment was significantly reduced relative to controls from days 23 to 32 postfertilization, and levels in the embryo were reduced by 40% at day 32 postfertilization, indicating that silver toxicity in the whole embryo is associated with an ion regulatory disturbance that is similar to the acute effect of AgNO3 in juvenile and adult trout.

Synthesis of Silver Polymer Nanocomposites and Their Antibacterial Activity

NASA Astrophysics Data System (ADS)

Gavade, Chaitali; Shah, Sunil; Singh, N. L.

2011-07-01

PVA (Polyvinyl Alcohol) silver nanocomposites of different sizes were prepared by chemical reduction method. Silver nitrate was taken as the metal precursor and amine hydrazine as a reducing agent. The formation of the silver nanoparticles was noticed using UV- visible absorption spectroscopy. The UV-visible spectroscopy revealed the formation of silver nanoparticles by exhibiting the surface plasmon resonance. The bactericidal activity due to silver release from the surface was determined by the modification of conventional diffusion method. Salmonella typhimurium, Serratia sps and Shigella sps were used as test bacteria which are gram-negative type bacteria. Effect of the different sizes of silver nano particles on antibacterial efficiency was discussed. Zones of inhibition were measured after 24 hours of incubation at 37 °C which gave 20 mm radius for high concentration of silver nanoparticles.

Synthesis and Optical Properties of Silver Bicrystalline Nanowires

NASA Astrophysics Data System (ADS)

Sun, Yugang; Xia, Younan

2002-11-01

This paper describes a solution-phase route to the large-scale synthesis of silver nanowires with diameters in the range of 30-40 nm, and lengths up to ~50 μm. The initial step of this synthesis involved the formation of Pt nanoparticles by reducing PtCl2 with ethylene glycol (EG) refluxed at ~160 °C. These Pt nanoparticles could serve as seeds for the growth of silver (formed by reducing AgNO3 with EG) through heterogeneous nucleation process because their crystal structures and lattice constants matched closely. In the presence of poly(vinyl pyrrolidone) (PVP), the growth of silver could be led to a highly anisotropic mode with formation of uniform nanowires. UV-visible spectroscopy was used to track the growth process of silver nanowires because different silver nanostructures exhibited distinctive surface plasmon resonance peaks at different frequencies. SEM, TEM, XRD, and electron diffraction were used to characterize these silver nanowires, indicating the formation of a highly pure face-centered cubic phase, as well as uniform diameter and bicrystalline structure. The morphology of these silver nanostructures could be varied from particles and rods to long wires by tuning the reaction conditions, including reaction temperature, and the ratio of PVP to silver nitrate. These silver nanowires could be used as sacrificial templates to synthesize gold nanotubes via a template-engaged replacement reaction. The dispersion of gold nanotubes exhibited a strong extinction peak in the red regime, which was around 760 nm.

Electrical and mechanical behavior of polymethyl methacrylate/cadmium sulphide composites

NASA Astrophysics Data System (ADS)

Kaur, Rajdeep; Samra, Kawaljeet Singh

2018-06-01

In the present investigation, electrical and mechanical behavior of cadmium sulphide (CdS) doped polymethyl methacrylate (PMMA) have been studied using different techniques. Dip casting technique was used for preparing free standing films of pristine and CdS doped PMMA at different compositions (i.e. 1 and 5 wt%). Optical absorbance as a function of wavelength was studied, by UV-visible spectroscopy, to find the impact of CdS doping on the optical band gap of synthesized PMMA/CdS composite. DC and AC conductivities were measured as a function of dopant concentration and temperature. Considerable increase in electrical conductivity was observed with the increase of CdS contents in polymer matrix. Overall electrical conduction mechanism in PMMA/CdS composites was attributed to movement of electrons through the uniformly distributed CdS aggregates within the matrix of PMMA. Mechanical properties, such as Young's modulus, tensile strength, elongation and ductility, of PMMA/CdS composites were determined and relevant responsible phenomena were discussed.

Mechanism of Prophylaxis by Silver Compounds against Infection of Burns

PubMed Central

Ricketts, C. R.; Lowbury, E. J. L.; Lawrence, J. C.; Hall, M.; Wilkins, M. D.

1970-01-01

To clarify tthe mechanism by which local application of silver compounds protects burns against infection, an ion-specific electrode was used to measùre the concentration of silver ions in solutions. By this method it was shown that in burn dressings silver ions were reduced to a very low level by precipitation as silver chloride. The antibacterial effect was found to depend on the availability of silver ions from solution in contact with precipitate. Between 10-5 and 10-6 molar silver nitrate solution in water was rapidly bactericidal. The minimal amount of silver nitrate causing inhibition of respiration of skin in tissue culture was about 25 times the minimal concentration of silver nitrate that inhibited growth of Pseudomonas aeruginosa. PMID:4986877

Colloidal complexed silver and silver nanoparticles in extrapallial fluid of Mytilus edulis.

PubMed

Zuykov, Michael; Pelletier, Emilien; Demers, Serge

2011-02-01

Metal transport in mollusk extrapallial fluid (EPF) that acts as a "bridge" between soft tissues and shell has surprisingly received little attention until now. Using ultrafiltration and radiotracer techniques we determined silver concentrations and speciation in the EPF of the blue mussel Mytilus edulis after short-term uptake and depuration laboratory experiments. Radiolabelled silver ((¹¹⁰m)Ag) was used in dissolved or nanoparticulate phases (AgNPs < 40 nm), with a similar low Ag concentration (total radioactive and cold Ag ~0.7 μg/L) in a way that mussels could uptake radiotracers only from seawater. Our results indicated that silver nanoparticles were transported to the EPF of blue mussels at a level similar to the Ag ionic form. Bulk activity of radiolabelled silver in the EPF represented only up to 7% of the bulk activity measured in the whole mussels. The EPF extracted from mussels exposed to both treatments exhibited an Ag colloidal complexed form based on EPF ultrafiltration through a 3 kDa filter. This original study brings new insights to internal circulation of nanoparticles in living organisms and contributes to the international effort in studying the potential impacts of engineered nanomaterials on marine bivalves which play an essential role in coastal ecosystems, and are important contributors to human food supply from the sea. © 2010 Elsevier Ltd. All rights reserved.

The Empirical Formula of Silver Sulfide: An Experiment for Introductory Chemistry

ERIC Educational Resources Information Center

Trujillo, Carlos Alexander

2007-01-01

An experiment is described that allows students to experimentally determine an empirical formula for silver sulfide. At elevated temperatures, silver sulfide reacts in air to form silver, silver sulfate, and sulfur dioxide. At higher temperatures (960 [degree]C) silver sulfate decomposes to produce metallic silver. (Contains 1 figure and 1 table.)

Biopersistence of silver nanoparticles in tissues from Sprague–Dawley rats

PubMed Central

2013-01-01

Silver nanoparticles are known to be distributed in many tissues after oral or inhalation exposure. Thus, understanding the tissue clearance of such distributed nanoparticles is very important to understand the behavior of silver nanoparticles in vivo. For risk assessment purposes, easy clearance indicates a lower overall cumulative toxicity. Accordingly, to investigate the clearance of tissue silver concentrations following oral silver nanoparticle exposure, Sprague–Dawley rats were assigned to 3 groups: control, low dose (100 mg/kg body weight), and high dose (500 mg/kg body weight), and exposed to two different sizes of silver nanoparticles (average diameter 10 and 25 nm) over 28 days. Thereafter, the rats were allowed to recover for 4 months. Regardless of the silver nanoparticle size, the silver content in most tissues gradually decreased during the 4-month recovery period, indicating tissue clearance of the accumulated silver. The exceptions were the silver concentrations in the brain and testes, which did not clear well, even after the 4-month recovery period, indicating an obstruction in transporting the accumulated silver out of these tissues. Therefore, the results showed that the size of the silver nanoparticles did not affect their tissue distribution. Furthermore, biological barriers, such as the blood–brain barrier and blood-testis barrier, seemed to play an important role in the silver clearance from these tissues. PMID:24059869

Efficacy of some colloidal silver preparations and silver salts against Proteus bacteria, one possible cause of rheumatoid arthritis.

PubMed

Disaanayake, D M B T; Faoagali, Joan; Laroo, Hans; Hancock, Gerald; Whitehouse, Michael

2014-04-01

There has been increased interest in the role of anti-Proteus antibodies in the aetiology of rheumatoid arthritis (RA) and whether chemotherapeutic agents active against Proteus species might reduce the risk and/or exacerbations of RA. We examined the in vitro antibacterial effects of ten different silver preparations which were either ionic silver [Ag(I)] solutions or nanoparticulate silver (NPS) (Ag(0)) suspensions against ATCC and two wild (clinical) strains of Proteus. The data establish the low minimum inhibitory concentration and minimum bactericidal concentration of all the silver formulations tested against these four Proteus strains. In a pilot study, a potent NPS preparation ex vivo showed long-lasting anti-Proteus activity in a normal human volunteer.

Antimicrobial activity of silver nanoparticles impregnated wound dressing

NASA Astrophysics Data System (ADS)

Shinde, V. V.; Jadhav, P. R.; Patil, P. S.

2013-06-01

In this work, silver nanoparticles were synthesized by simple wet chemical reduction method. The silver nitrate was reduced by Sodium borohydride used as reducing agent and Poly (vinyl pyrrolidone) (PVP) as stabilizing agent. The formation of silver nanoparticles was evaluated by UV-visible spectroscope and transmission electron microscope (TEM). Absorption spectrum consist two plasmon peaks at 410 and 668 nm revels the formation of anisotropic nanoparticles confirmed by TEM. The formation of silver nanoparticles was also evidenced by dynamic light scattering (DLS) study. DLS showed polydisperse silver nanoparticles with hydrodynamic size 32 nm. Protecting mechanism of PVP was manifested by FT-Raman study. Silver nanoparticles were impregnated into wound dressing by sonochemical method. The Kirby-Bauer disc diffusion methods were used for antimicrobial susceptibility testing. The antimicrobial activity of the samples has been tested against gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus.

Silver microparticles plus fibrin tissue sealant prevents incisional hernias in rats.

PubMed

Primus, Frank E; Young, David M; Grenert, James P; Harris, Hobart W

2018-07-01

Open abdominal surgery is frequently complicated by the subsequent development of an incisional hernia. Consequently, more than 400,000 incisional hernia repairs are performed each year, adding over $15 billion per year to U.S. health-care expenditures. While the vast majority of studies have focused on improved surgical techniques or prosthetic materials, we examined the use of metallic silver microparticles to prevent incisional hernia formation through enhanced wound healing. A rodent incisional hernia model was used. Eighty-two rats were randomly placed into two control groups (saline alone and silver microparticles alone), and three experimental groups (0 mg/cm, 2.5 mg/cm, and 25 mg/cm of silver microparticles applied with a fibrin sealant). Incisional hernia incidence and size, tensile strength, and tissue histology were assessed after 28 days. A significant reduction of both incisional hernia incidence and hernia size was observed between the control groups and 2.5 mg/cm group, and between the control and 25 mg/cm group by nearly 60% and 90%, respectively (P < 0.05). Histological samples showed a noticeable increase in new fibrosis in the treated animals as compared with the controls, whereas the tensile strength between the groups did not differ. The novel approach of using silver microparticles to enhance wound healing appears to be a safe and effective method to prevent incisional hernias from developing and could herald a new era of medicinal silver use. Copyright © 2018 Elsevier Inc. All rights reserved.

Evaluation of a Silver-Embedded Ceramic Tablet as a Primary and Secondary Point-of-Use Water Purification Technology in Limpopo Province, S. Africa

PubMed Central

Ehdaie, Beeta; Rento, Chloe T.; Son, Veronica; Turner, Sydney S.; Samie, Amidou; Dillingham, Rebecca A.

2017-01-01

The World Health Organization (WHO) recognizes point-of-use water treatment (PoUWT) technologies as effective means to improve water quality. This paper investigates long-term performance and social acceptance of a novel PoUWT technology, a silver-infused ceramic tablet, in Limpopo Province, South Africa. When placed in a water storage container, the silver-embedded ceramic tablet releases silver ions into water, thereby disinfecting microbial pathogens and leaving the water safe for human consumption. As a result of its simplicity and efficiency, the silver-embedded ceramic tablet can serve as a stand-alone PoUWT method and as a secondary PoUWT to improve exisitng PoUWT methods, such as ceramic water filters. In this paper, three PoUWT interventions were conducted to evaluate the silver-embedded ceramic tablet: (1) the silver-embedded ceramic tablet as a stand-alone PoUWT method, (2) ceramic water filters stand-alone, and (3) a filter-tablet combination. The filter-tablet combination evaluates the silver-embedded ceramic tablet as a secondary PoUWT method when placed in the lower reservoir of the ceramic water filter system to provide residual disinfection post-filtration. Samples were collected from 79 households over one year and analyzed for turbidity, total silver levels and coliform bacteria. Results show that the silver-embedded ceramic tablet effectively reduced total coliform bacteria (TC) and E. coli when used as a stand-alone PoUWT method and when used in combination with ceramic water filters. The silver-embedded ceramic tablet’s performance as a stand-alone PoUWT method was comparable to current inexpensive, single-use PoUWT methods, demonstrating 100% and 75% median reduction in E. coli and TC, respectively, after two months of use. Overall, the the filter-tablet combination performed the best of the three interventions, providing a 100% average percent reduction in E. coli over one year. User surveys were also conducted and indicated that the

Evaluation of a Silver-Embedded Ceramic Tablet as a Primary and Secondary Point-of-Use Water Purification Technology in Limpopo Province, S. Africa.

PubMed

Ehdaie, Beeta; Rento, Chloe T; Son, Veronica; Turner, Sydney S; Samie, Amidou; Dillingham, Rebecca A; Smith, James A

2017-01-01

The World Health Organization (WHO) recognizes point-of-use water treatment (PoUWT) technologies as effective means to improve water quality. This paper investigates long-term performance and social acceptance of a novel PoUWT technology, a silver-infused ceramic tablet, in Limpopo Province, South Africa. When placed in a water storage container, the silver-embedded ceramic tablet releases silver ions into water, thereby disinfecting microbial pathogens and leaving the water safe for human consumption. As a result of its simplicity and efficiency, the silver-embedded ceramic tablet can serve as a stand-alone PoUWT method and as a secondary PoUWT to improve exisitng PoUWT methods, such as ceramic water filters. In this paper, three PoUWT interventions were conducted to evaluate the silver-embedded ceramic tablet: (1) the silver-embedded ceramic tablet as a stand-alone PoUWT method, (2) ceramic water filters stand-alone, and (3) a filter-tablet combination. The filter-tablet combination evaluates the silver-embedded ceramic tablet as a secondary PoUWT method when placed in the lower reservoir of the ceramic water filter system to provide residual disinfection post-filtration. Samples were collected from 79 households over one year and analyzed for turbidity, total silver levels and coliform bacteria. Results show that the silver-embedded ceramic tablet effectively reduced total coliform bacteria (TC) and E. coli when used as a stand-alone PoUWT method and when used in combination with ceramic water filters. The silver-embedded ceramic tablet's performance as a stand-alone PoUWT method was comparable to current inexpensive, single-use PoUWT methods, demonstrating 100% and 75% median reduction in E. coli and TC, respectively, after two months of use. Overall, the the filter-tablet combination performed the best of the three interventions, providing a 100% average percent reduction in E. coli over one year. User surveys were also conducted and indicated that the silver

Identification of a silver binding protein associated with the cytological silver staining of actively transcribing nucleolar regions.

PubMed

Hubbell, H R; Rothblum, L I; Hsu, T C

1979-10-01

Nucleoli isolated from Novikoff hepatoma cells were stained with AgNO3 to demonstrate the typical staining of active ribosomal cistrons. Pre-treatment of the nucleoli with 80 mM Tris-HCl (pH 7.5) -- 2.0 M NaCl did not interfere with silver staining. Treatment of the nucleoli with 80 mM Tris-HCl (pH 7.5) -- 0.15 M NaCl did, however, eliminate silver binding. Serial extraction of nucleoli with 2.0 M NaCl buffer followed by 0.15 M NaCl buffer also abolished silver staining. Analysis of the supernatant fraction of these extracts by polyacrylamide gel electrophoresis indicates that, although more than one nucleolar protein can bind silver, only one protein is associated with the staining of active ribosomal cistrons.

Efficacy of scalp hair decontamination following exposure to vapours of sulphur mustard simulants 2-chloroethyl ethyl sulphide and methyl salicylate.

PubMed

Spiandore, Marie; Piram, Anne; Lacoste, Alexandre; Prevost, Philippe; Maloni, Pascal; Torre, Franck; Asia, Laurence; Josse, Denis; Doumenq, Pierre

2017-04-01

Chemical warfare agents are an actual threat and victims' decontamination is a main concern when mass exposure occurs. Skin decontamination with current protocols has been widely documented, as well as surface decontamination. However, considering hair ability to trap chemicals in vapour phase, we investigated hair decontamination after exposure to sulphur mustard simulants methyl salicylate and 2-chloroethyl ethyl sulphide. Four decontamination protocols were tested on hair, combining showering and emergency decontamination (use of Fuller's earth or Reactive Skin Decontamination Lotion RSDL ® ). Both simulants were recovered from hair after treatment, but contents were significantly reduced (42-85% content allowance). Showering alone was the least efficient protocol. Concerning 2-chloroethyl ethyl sulphide, protocols did not display significant differences in decontamination efficacy. For MeS, use of emergency decontaminants significantly increased showering efficacy (10-20% rise), underlining their usefulness before thorough decontamination. Our results highlighted the need to extensively decontaminate hair after chemical exposure. Residual amounts after decontamination are challenging, as their release from hair could lead to health issues. Copyright © 2016. Published by Elsevier B.V.

Analyzing silver concentration in soil using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Prasetyo, S.; Isnaeni; Zaitun; Mitchell, K.; Suliyanti, M. M.; Herbani, Y.

2018-03-01

Determination of concentration of heavy metal ions in soil, such as silver, is very important to study soil pollution levels. Several techniques have been developed to determine silver ion concentration in soil. In this paper, we utilized laser-induced breakdown spectroscopy (LIBS) to study silver concentration in soil. We used four different data analysis methods to calculate silver concentration. In this case, we prepared soil samples with different silver ion concentrations from 400 ppm to 1000 ppm. Our analysis was focused on the 843.15 nm silver atomic absorption line. We found that plasma intensity increased as silver concentration increased. Our findings were based on our analysis using four different analysis methods. We believe that these analysis methods are able to calculate silver concentration in soil using LIBS.

Properties of thin silver films with different thickness

NASA Astrophysics Data System (ADS)

Zhao, Pei; Su, Weitao; Wang, Reng; Xu, Xiaofeng; Zhang, Fengshan

2009-01-01

In order to investigate optical properties of silver films with different film thickness, multilayer composed of thin silver film sandwiched between ZnS films are sputtered on the float glass. The crystal structures, optical and electrical properties of films are characterized by various techniques, such as X-ray diffraction (XRD), spectrum analysis, etc. The optical constants of thin silver film are calculated by fitting the transmittance ( T) and reflectance ( R) spectrum of the multilayer. Electrical and optical properties of silver films thinner than 6.2 nm exhibit sharp change. However, variation becomes slow as film thickness is larger than 6.2 nm. The experimental results indicate that 6.2 nm is the optimum thickness for properties of silver.

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

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

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 thismore » 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.« less

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.

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

Principal Locations of Metal Loading from Flood-Plain Tailings, Lower Silver Creek, Utah, April 2004

USGS Publications Warehouse

Kimball, Briant A.; Runkel, Robert L.; Walton-Day, Katherine

2007-01-01

Because of the historical deposition of mill tailings in flood plains, the process of determining total maximum daily loads for streams in an area like the Park City mining district of Utah is complicated. Understanding the locations of metal loading to Silver Creek and the relative importance of these locations is necessary to make science-based decisions. Application of tracer-injection and synoptic-sampling techniques provided a means to quantify and rank the many possible source areas. A mass-loading study was conducted along a 10,000-meter reach of Silver Creek, Utah, in April 2004. Mass-loading profiles based on spatially detailed discharge and chemical data indicated five principal locations of metal loading. These five locations contributed more than 60 percent of the cadmium and zinc loads to Silver Creek along the study reach and can be considered locations where remediation efforts could have the greatest effect upon improvement of water quality in Silver Creek.

Durable Corrosion and Ultraviolet-Resistant Silver Mirror

DOEpatents

Jorgensen, G. J.; Gee, R.

2006-01-24

A corrosion and ultra violet-resistant silver mirror for use in solar reflectors; the silver layer having a film-forming protective polymer bonded thereto, and a protective shield overlay comprising a transparent multipolymer film that incorporates a UV absorber. The corrosion and ultraviolet resistant silver mirror retains spectral hemispherical reflectance and high optical clarity throughout the UV and visible spectrum when used in solar reflectors.

Antibacterial properties and mechanisms of gold-silver nanocages

NASA Astrophysics Data System (ADS)

Wang, Yulan; Wan, Jiangshan; Miron, Richard J.; Zhao, Yanbin; Zhang, Yufeng

2016-05-01

Despite the number of antibiotics used in routine clinical practice, bacterial infections continue to be one of the most important challenges faced in humans. The main concerns arise from the continuing emergence of antibiotic-resistant bacteria and the difficulties faced with the pharmaceutical development of new antibiotics. Thus, advancements in the avenue of novel antibacterial agents are essential. In this study, gold (Au) was combined with silver (Ag), a well-known antibacterial material, to form silver nanoparticles producing a gold-silver alloy structure with hollow interiors and porous walls (gold-silver nanocage). This novel material was promising in antibacterial applications due to its better biocompatibility than Ag nanoparticles, potential in photothermal effects and drug delivery ability. The gold-silver nanocage was then tested for its antibacterial properties and the mechanism involved leading to its antibacterial properties. This study confirms that this novel gold-silver nanocage has broad-spectrum antibacterial properties exerting its effects through the destruction of the cell membrane, production of reactive oxygen species (ROS) and induction of cell apoptosis. Therefore, we introduce a novel gold-silver nanocage that serves as a potential nanocarrier for the future delivery of antibiotics.

Synthesis of silver nanoparticles in melts of amphiphilic polyesters

NASA Astrophysics Data System (ADS)

Vasylyev, S.; Damm, C.; Segets, D.; Hanisch, M.; Taccardi, N.; Wasserscheid, P.; Peukert, W.

2013-03-01

The current work presents a one-step procedure for the synthesis of amphiphilic silver nanoparticles suitable for production of silver-filled polymeric materials. This solvent free synthesis via reduction of Tollens’ reagent as silver precursor in melts of amphiphilic polyesters consisting of hydrophilic poly(ethylene glycol) blocks and hydrophobic alkyl chains allows the production of silver nanoparticles without any by-product formation. This makes them especially interesting for the production of medical devices with antimicrobial properties. In this article the influences of the chain length of the hydrophobic block in the amphiphilic polyesters and the process temperature on the particle size distribution (PSD) and the stability of the particles against agglomeration are discussed. According to the results of spectroscopic and viscosimetric investigations the silver precursor is reduced to elemental silver nanoparticles by a single electron transfer process from the poly(ethylene glycol) chain to the silver ion.

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

Antimicrobial action of silver nitrate.

PubMed

Richards, R M

1981-01-01

Silver nitrate 3 mug/ml prevented the separation into two daughter cells of sensitive dividing cells of Pseudomonas aeruginosa growing in nutrient broth plus the chemical. Cell size of sensitive cells was increased and the cytoplasmic contents, cytoplasmic membrane and external cell envelope structures were all abnormal. P. aeruginosa cells grown in the presence of silver nitrate 9 mug/ml showed all these changes to a marked degree except inhibition of cell division was not observed. Silver nitrate (1.5 mug/ml) in distilled water inactivated bacteriophage T2 particles as determined by their infectivity to Escherichia coli B cultures. Lysozyme (50 mug/ml) reduced, and sodium chloride (0.9%) blocked this activity.

Toward Interpreting Failure in Sintered-Silver Interconnection Systems

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

Wereszczak, Andrew A; Waters, Shirley B

2016-01-01

The mechanical strength and subsequent reliability of a sintered-silver interconnection system is a function of numerous independent parameters. That system is still undergoing process development. Most of those parameters (e.g., choice of plating) are arguably and unfortunately taken for granted and are independent of the silver s cohesive strength. To explore such effects, shear strength testing and failure analyses were completed on a simple, mock sintered-silver interconnection system consisting of bonding two DBC ceramic substrates. Silver and gold platings were part of the test matrix, as was pre-drying strategies, and the consideration of stencil-printing vs. screen-printing. Shear strength of sintered-silvermore » interconnect systems was found to be was insensitive to the choice of plating, drying practice, and printing method provided careful and consistent processing of the sintered-silver are practiced. But if the service stress in sintered silver interconnect systems is anticipated to exceed ~ 60 MPa, then the system will likely fail.« less

Reduced contact resistance of a-IGZO thin film transistors with inkjet-printed silver electrodes

NASA Astrophysics Data System (ADS)

Chen, Jianqiu; Ning, Honglong; Fang, Zhiqiang; Tao, Ruiqiang; Yang, Caigui; Zhou, Yicong; Yao, Rihui; Xu, Miao; Wang, Lei; Peng, Junbiao

2018-04-01

In this study, high performance amorphous In–Ga–Zn–O (a-IGZO) TFTs were successfully fabricated with inkjet-printed silver source-drain electrodes. The results showed that increased channel thickness has an improving trend in the properties of TFTs due to the decreased contact resistance. Compared with sputtered silver TFTs, devices with printed silver electrodes were more sensitive to the thickness of active layer. Furthermore, the devices with optimized active layer showed high performances with a maximum saturation mobility of 8.73 cm2 · V‑1 · S‑1 and an average saturation mobility of 6.97 cm2 · V‑1 · S‑1, I on/I off ratio more than 107 and subthreshold swing of 0.28 V/decade, which were comparable with the analogous devices with sputtered electrodes.

The Effect of Silver Chloride Formation on the Kinetics of Silver Dissolution in Chloride Solution

PubMed Central

Ha, Hung; Payer, Joe

2011-01-01

The precipitation and growth of AgCl on silver in physiological NaCl solution were investigated. AgCl was found to form at bottom of scratches on the surface which may be the less effective sites for diffusion or the favorable sites for heterogeneous nucleation. Patches of silver chloride expanded laterally on the substrate until a continuous film formed. The ionic transport path through this newly formed continuous film was via spaces between AgCl patches. As the film grew, the spaces between AgCl patches closed and ion transport was primarily via micro-channels running through AgCl patches. The decrease of AgCl layer conductivity during film growth were attributed to the clogging of micro-channels or decrease in charge carrier concentration inside the micro-channels. Under thin AgCl layer, i.e. on the order of a micrometer, the dissolution of silver substrate was under mixed activation-Ohmic control. Under thick AgCl layer, i.e. on the order of tens of micrometers, the dissolution of silver substrate was mediated by the Ohmic resistance of AgCl layer. PMID:21516171

21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Enrofloxacin, silver sulfadiazine emulsion. 524... ANIMAL DRUGS § 524.802 Enrofloxacin, silver sulfadiazine emulsion. (a) Specifications. Each milliliter contains 5 milligrams (mg) enrofloxacin and 10 mg silver sulfadiazine. (b) Sponsor. See No. 000859 in § 510...

Preparation and characterization of silver nanoparticles homogenous thin films

NASA Astrophysics Data System (ADS)

Hegazy, Maroof A.; Borham, E.

2018-06-01

The wet chemical method by metal salt reduction has been widely used to synthesize nanoparticles. Accordingly the silver nitrate used as silver precursor and sodium borohydrate as reduction agent. The silver nanoparticles were characterized by different characterization techniques including UV-VIS spectrometry, Transmission electron microscope (TEM), and Zeta potential technique. Thin films of the colloidal solution were fabricated using direct precipitation technique on ITO glass, silicon substrate and commercial glass substrate and characterized by imaging technique. The absorption peak of the silver nanoparticles colloidal solution was around 400 nm. The TEM images indicate that the silver nanoparticles had spherical shape and their sizes were from 10 to 17 nm. The particle size of the silver nanoparticles was confirmed by Zeta potential technique. The imaging technique indicated that the homogeneous distribution of the colloidal silver solution thin film on the silicon substrate was stronger than the ITO glass and inhomogeneous film was emerged on the commercial glass.

Charcoal as a capture material for silver nanoparticles in the aquatic environment

NASA Astrophysics Data System (ADS)

McGillicuddy, Eoin; Morrison, Liam; Cormican, Martin; Morris, Dearbháile

2017-04-01

Background: The reported antibacterial activity of silver nanoparticles (AgNPs) has led to their incorporation into numerous consumer products including; textiles, domestic appliances, food containers, cosmetics, paints, medical and medicinal products. The AgNPs incorporated into these products can be released into the environment and aquatic system during their production, use and end of life disposal. In the aquatic environment, uncertainties surround the concentration, fate and effects of AgNPs. The aim of this project is to examine charcoal as a potential material for capture of silver nanoparticles from the aquatic environment. Material/methods: Activated charcoal is a commonly used filter material and was selected for this project to determine its suitability as a capture material for AgNPs in water samples. Activated charcoal (Norit® CA1 (Sigma-Aldrich)) was exposed to 100 ppb, 25 nm PVP coated AgNPs (nanoComposix) prepared in Milli-Q water. These solutions were exposed to unaltered charcoal granules for 20 hours after which the decrease of silver in the solution was measured using ICP-MS. In order to improve the removal, the surface area of the charcoal was increased firstly by grinding with a pestle and mortar and secondly by milling the charcoal. The milled charcoal was prepared using an agate ball mill running at 500 rpm for 5 minutes. The activated charcoal was then exposed to samples containing 10 ppb AgNPs. Results: In the initial tests, approximately 10% of the silver was removed from the water samples using the unaltered activated charcoal granules. Further experiments were carried out to compare the unaltered granules with the ground and milled charcoal. These tests were carried out similarly to the previous test however lower concentration of 10 ppb was used. After 20 hours of exposure the granule samples, as previously, showed approximately a 10% reduction in silver content with the ground charcoal giving approximately 30% reduction in silver

Biomimetics of silver nanoparticles by white rot fungus, Phaenerochaete chrysosporium.

PubMed

Vigneshwaran, Nadanathangam; Kathe, Arati A; Varadarajan, P V; Nachane, Rajan P; Balasubramanya, R H

2006-11-01

Extracellular synthesis of silver nanoparticles by a white rot fungus, Phaenerochaete chrysosporium is reported in this paper. Incubation of P. chrysosporium mycelium with silver nitrate solution produced silver nanoparticles in 24h. These silver nanoparticles were characterized by means of UV-vis spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The synthesized silver nanoparticles absorbed maximum at 470 nm in the visible region. XRD spectrum of the silver nanoparticles confirmed the formation of metallic silver. The SEM characterization of the fungus reacted on the Ag+ indicated that the protein might be responsible for the stabilization of silver nanoparticles. This result was further supported by the TEM examination. Though shape variation was noticed, majority of the nanoparticles were found to be of pyramidal shape as seen under TEM. Photoluminescence spectrum showed a broad emission peak of silver nanoparticles at 423 nm when excited at 350 nm. Apart from eco-friendliness, fungus as bio-manufacturing unit will give us an added advantage in ease of handling when compared to other classes of microorganisms.

Dermal exposure potential from textiles that contain silver nanoparticles

PubMed Central

Stefaniak, Aleksandr B; Duling, Mathew G; Lawrence, Robert B; Thomas, Treye A; LeBouf, Ryan F; Wade, Eleanor E; Abbas Virji, M

2014-01-01

Background: Factors that influence exposure to silver particles from the use of textiles are not well understood. Objectives: The aim of this study was to evaluate the influence of product treatment and physiological factors on silver release from two textiles. Methods: Atomic and absorbance spectroscopy, electron microscopy, and dynamic light scattering (DLS) were applied to characterize the chemical and physical properties of the textiles and evaluate silver release in artificial sweat and saliva under varying physiological conditions. One textile had silver incorporated into fiber threads (masterbatch process) and the other had silver nanoparticles coated on fiber surfaces (finishing process). Results: Several complementary and confirmatory analytical techniques (spectroscopy, microscopy, etc.) were required to properly assess silver release. Silver released into artificial sweat or saliva was primarily in ionic form. In a simulated “use” and laundering experiment, the total cumulative amount of silver ion released was greater for the finishing process textile (0.51±0.04%) than the masterbatch process textile (0.21±0.01%); P<0.01. Conclusions: We found that the process (masterbatch vs finishing) used to treat textile fibers was a more influential exposure factor than physiological properties of artificial sweat or saliva. PMID:25000110

Dermal exposure potential from textiles that contain silver nanoparticles.

PubMed

Stefaniak, Aleksandr B; Duling, Mathew G; Lawrence, Robert B; Thomas, Treye A; LeBouf, Ryan F; Wade, Eleanor E; Virji, M Abbas

2014-01-01

Factors that influence exposure to silver particles from the use of textiles are not well understood. The aim of this study was to evaluate the influence of product treatment and physiological factors on silver release from two textiles. Atomic and absorbance spectroscopy, electron microscopy, and dynamic light scattering (DLS) were applied to characterize the chemical and physical properties of the textiles and evaluate silver release in artificial sweat and saliva under varying physiological conditions. One textile had silver incorporated into fiber threads (masterbatch process) and the other had silver nanoparticles coated on fiber surfaces (finishing process). Several complementary and confirmatory analytical techniques (spectroscopy, microscopy, etc.) were required to properly assess silver release. Silver released into artificial sweat or saliva was primarily in ionic form. In a simulated "use" and laundering experiment, the total cumulative amount of silver ion released was greater for the finishing process textile (0·51±0·04%) than the masterbatch process textile (0·21±0·01%); P<0·01. We found that the process (masterbatch vs finishing) used to treat textile fibers was a more influential exposure factor than physiological properties of artificial sweat or saliva.

Green synthesis of silver nanoparticles using tannins

NASA Astrophysics Data System (ADS)

Raja, Pandian Bothi; Rahim, Afidah Abdul; Qureshi, Ahmad Kaleem; Awang, Khalijah

2014-09-01

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

Synthesis and applications of novel silver nanoparticle structures

NASA Astrophysics Data System (ADS)

Dukes, Kyle

The field of nanotechnology is rapidly expanding across disciplines as each new development is realized. New exciting technologies are being driven by advances in the application of nanotechnology; including biochemical, optical, and semiconductors research. This thesis will focus on the use of silver nanoparticles as optical labels on cells, methods of forming different small structures of silver nanoparticles, as well as the use of silver nanoparticles in the development of a photovoltaic cell. Silver nanoparticles have been modified with self-assembled monolayers of hydroxyl-terminated long chain thiols and encapsulated with a silica shell. The resulting core-shell nanoparticles were used as optical labels for cell analysis using flow cytometry and microscopy. The excitation of plasmon resonances in nanoparticles results in strong depolarized scattering of visible light permitting detection at the single nanoparticle level. The nanoparticles were modified with neutravidin via epoxide-azide coupling chemistry and biotinylated antibodies targeting cell surface receptors were bound to the nanoparticle surface. The nanoparticle labels exhibited long-term stability under physiological conditions without aggregation or silver ion leaching. Labeled cells exhibited two orders of magnitude enhancement of the scattering intensity compared to unlabeled cells. Dimers of silver nanoparticles have been fabricated by first immobilizing a monolayer of single silver nanoparticles onto poly(4-vinylpyridine) covered glass slides. The monolayer was then exposed to adenine, which has two amines which will bind to silver. The nanoparticle monolayer, now modified with adenine, is exposed to a second suspension of nanoparticles which will bind with the amine modified monolayer. Finally, a thin silica shell is formed about the structure via solgel chemistry to prevent dissolution or aggregation upon sonication/striping. Circular arrays of silver nanoparticels are developed using a

Sintered silver joints via controlled topography of electronic packaging subcomponents

DOEpatents

Wereszczak, Andrew A.

2014-09-02

Disclosed are sintered silver bonded electronic package subcomponents and methods for making the same. Embodiments of the sintered silver bonded EPSs include topography modification of one or more metal surfaces of semiconductor devices bonded together by the sintered silver joint. The sintered silver bonded EPSs include a first semiconductor device having a first metal surface, the first metal surface having a modified topography that has been chemically etched, grit blasted, uniaxial ground and/or grid sliced connected to a second semiconductor device which may also include a first metal surface with a modified topography, a silver plating layer on the first metal surface of the first semiconductor device and a silver plating layer on the first metal surface of the second semiconductor device and a sintered silver joint between the silver plating layers of the first and second semiconductor devices which bonds the first semiconductor device to the second semiconductor device.

PREDICTING THE TOXICITY OF SEDIMENTS SPIKED WITH SILVER

EPA Science Inventory

Previous experiments conducted with freshwater sediments spiked with silver have shown that, when expressed on a dry weight basis, the toxicity of silver is sediment-specific and dependent on the form of silver added (e.g., AgNO3, Ag2S). This study was conducted to assess the use...

Silver Ion Biocide Delivery System for Water Disinfection

NASA Technical Reports Server (NTRS)

Slote, Benjamin M.; Salley, Edward; Carr, Daniel; Kimble, Michael C.; Adam, Niklas

2016-01-01

U.S. space exploration missions have long considered returning to the Moon and exploration of Mars that challenge life support systems. For these long duration missions, there is interest in replacing the iodine water treatment system with ionic silver, a proven biocide. For long duration exploration missions, it is imperative that an effective biocide be used that prevents microbial growth, biofilm formation, and microbially induced corrosion in the water storage and distribution systems while minimizing logistical supply requirements associated with the biocide delivery system. Two biocide delivery systems have been developed that electrochemically produce silver ions for disinfecting water throughout the water storage and distribution system. One system uses a newly developed hybrid micro-filtration and ion-exchange membrane to produce an abundance of silver ions at the 1000 ppb level upstream in the water distribution system to prevent biofilm growth. This is followed by a downstream collection module that electrochemically removes these silver ions before the water is discharged. Another approach uses a membraneless reactor to produce a 1000 ppb silver ion concentration level that also has a mechanically driven electrode cleaning mechanism that removes oxide films ensuring long life operation. By maintaining a sufficiently high level of silver ions throughout the water storage and distribution system, biofilm formation is suppressed. This approach overcomes present concerns where spurious silver deposition occurs on the container and flow line surfaces thus lowering the silver ion concentration to unsatisfactory disinfection levels.

A silver ion water sterilization system

NASA Technical Reports Server (NTRS)

Parry, E. P.

1971-01-01

Small amounts of silver are incorporated in mixture of ion exchange resins, and water passing through this mixture is thus exposed to silver ion concentration. System is useful in self-contained water systems except city water systems where residual chlorine level is stipulated.

Silver Nanoparticle Storage Stability in Aqueous and Biological Media

DTIC Science & Technology

2015-06-22

silver nanoparticle stability from the point of synthesis to the point of testing. The recommended conditions of water storage at 4°C protected from... silver nanoparticle formulation for fabrication. (Report No. 2014-73). 13 Métraux, G. S. & Mirkin, C. A. Rapid thermal synthesis of silver ...NAVAL MEDICAL RESEARCH UNIT SAN ANTONIO SILVER NANOPARTICLE STORAGE STABILITY IN AQUEOUS AND BIOLOGICAL MEDIA NATALIE A

Acoustical deterrence of Silver Carp (Hypophthalmichthys molitrix)

USGS Publications Warehouse

Brooke J. Vetter,; Cupp, Aaron R.; Fredricks, Kim T.; Gaikowski, Mark P.; Allen F. Mensinger,

2015-01-01

The invasive Silver Carp (Hypophthalmichthys molitrix) dominate large regions of the Mississippi River drainage and continue to expand their range northward threatening the Laurentian Great Lakes. This study found that complex broadband sound (0–10 kHz) is effective in altering the behavior of Silver Carp with implications for deterrent barriers or potential control measures (e.g., herding fish into nets). The phonotaxic response of Silver Carp was investigated using controlled experiments in outdoor concrete ponds (10 × 4.9 × 1.2 m). Pure tones (500–2000 Hz) and complex sound (underwater field recordings of outboard motors) were broadcast using underwater speakers. Silver Carp always reacted to the complex sounds by exhibiting negative phonotaxis to the sound source and by alternating speaker location, Silver Carp could be directed consistently, up to 37 consecutive times, to opposite ends of the large outdoor pond. However, fish habituated quickly to pure tones, reacting to only approximately 5 % of these presentations and never showed more than two consecutive responses. Previous studies have demonstrated the success of sound barriers in preventing Silver Carp movement using pure tones and this research suggests that a complex sound stimulus would be an even more effective deterrent.

Quantitatively in Situ Imaging Silver Nanowire Hollowing Kinetics

DOE PAGES

Yu, Le; Yan, Zhongying; Cai, Zhonghou; ...

2016-09-28

We report the in-situ investigation of the morphological evolution of silver nanowires to hollow silver oxide nanotubes using transmission x-ray microscopy (TXM). Complex silver diffusion kinetics and hollowing process via the Kirkendall effect have been captured in real time. Further quantitative x-ray absorption analysis reveals the difference between the longitudinal and radial diffusions. In conclusion, the diffusion coefficient of silver in its oxide nanoshell is, for the first time, calculated to be 1.2 × 10 -13 cm 2/s from the geometrical parameters extracted from the TXM images.

Crystal structure and optical properties of silver nanorings

NASA Astrophysics Data System (ADS)

Zhou, Li; Fu, Xiao-Feng; Yu, Liao; Zhang, Xian; Yu, Xue-Feng; Hao, Zhong-Hua

2009-04-01

We report the polyol synthesis and crystal structure characterization of silver nanorings, which have perfect circular shape, smooth surface, and elliptical wire cross-section. The characterization results show that the silver nanorings have well-defined crystal of singly twinned along the whole ring. The spatial distribution of the scattering of a silver nanoring with slanted incidence reveals the unique focus effect of the nanoring, and the focus scattering varies with the incident wavelength. The silver nanorings with perfect geometry and well-defined crystal have potential applications in nanoscaled photonics, plasmonic devices, and optical manipulation.

Pure silver ohmic contacts to N- and P- type gallium arsenide materials

DOEpatents

Hogan, Stephen J.

1986-01-01

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

Preparation and in vitro Antimicrobial Activity of Silver-Bearing Degradable Polymeric Nanoparticles of Polyphosphoester-block-Poly(L-lactide)

PubMed Central

Lim, Young H.; Tiemann, Kristin M.; Heo, Gyu Seong; Wagers, Patrick O.; Rezenom, Yohannes H.; Zhang, Shiyi; Zhang, Fuwu; Youngs, Wiley J.; Hunstad, David A.; Wooley, Karen L.

2015-01-01

The development of well-defined polymeric nanoparticles (NPs) as delivery carriers for antimicrobials targeting human infectious diseases requires rational design of the polymer template, an efficient synthetic approach and fundamental understanding of the developed NPs, e.g., drug loading/release, particle stability, and other characteristics. Herein, we developed and evaluated the in vitro antimicrobial activity of silver-bearing, fully biodegradable and functional polymeric NPs. A series of degradable polymeric nanoparticles (dNPs), composed of phosphoester and L-lactide and designed specifically for silver loading into the hydrophilic shell and/or the hydrophobic core, were prepared as potential delivery carriers for three different types of silver-based antimicrobials – silver acetate or one of two silver carbene complexes (SCCs). Silver-loading capacities of the dNPs were not influenced by the hydrophilic block chain length, loading site (i.e., core or shell), or type of silver compound, but optimization of the silver feed ratio was crucial to maximize the silver loading capacity of dNPs, up to ca. 12% (w/w). The release kinetics of silver-bearing dNPs revealed 50% release at ca. 2.5–5.5 h depending on the type of silver compound. In addition, we undertook a comprehensive evaluation of the rates of hydrolytic or enzymatic degradability and performed structural characterization of the degradation products. Interestingly, packaging of the SCCs in the dNP-based delivery system improved minimum inhibitory concentrations up to 70%, compared with the SCCs alone, as measured in vitro against ten contemporary epidemic strains of Staphylococcus aureus and eight uropathogenic strains of Escherichia coli. We conclude that these dNP-based delivery systems may be beneficial for direct epithelial treatment and/or prevention of ubiquitous bacterial infections, including those of the skin and urinary tract. PMID:25621868

Preparation and in vitro antimicrobial activity of silver-bearing degradable polymeric nanoparticles of polyphosphoester-block-poly(L-lactide).

PubMed

Lim, Young H; Tiemann, Kristin M; Heo, Gyu Seong; Wagers, Patrick O; Rezenom, Yohannes H; Zhang, Shiyi; Zhang, Fuwu; Youngs, Wiley J; Hunstad, David A; Wooley, Karen L

2015-02-24

The development of well-defined polymeric nanoparticles (NPs) as delivery carriers for antimicrobials targeting human infectious diseases requires rational design of the polymer template, an efficient synthetic approach, and fundamental understanding of the developed NPs, e.g., drug loading/release, particle stability, and other characteristics. Herein, we developed and evaluated the in vitro antimicrobial activity of silver-bearing, fully biodegradable and functional polymeric NPs. A series of degradable polymeric nanoparticles (dNPs), composed of phosphoester and L-lactide and designed specifically for silver loading into the hydrophilic shell and/or the hydrophobic core, were prepared as potential delivery carriers for three different types of silver-based antimicrobials-silver acetate or one of two silver carbene complexes (SCCs). Silver-loading capacities of the dNPs were not influenced by the hydrophilic block chain length, loading site (i.e., core or shell), or type of silver compound, but optimization of the silver feed ratio was crucial to maximize the silver loading capacity of dNPs, up to ca. 12% (w/w). The release kinetics of silver-bearing dNPs revealed 50% release at ca. 2.5-5.5 h depending on the type of silver compound. In addition, we undertook a comprehensive evaluation of the rates of hydrolytic or enzymatic degradability and performed structural characterization of the degradation products. Interestingly, packaging of the SCCs in the dNP-based delivery system improved minimum inhibitory concentrations up to 70%, compared with the SCCs alone, as measured in vitro against 10 contemporary epidemic strains of Staphylococcus aureus and eight uropathogenic strains of Escherichia coli. We conclude that these dNP-based delivery systems may be beneficial for direct epithelial treatment and/or prevention of ubiquitous bacterial infections, including those of the skin and urinary tract.

Hypocrellin B and nano silver loaded polymeric nanoparticles: Enhanced generation of singlet oxygen for improved photodynamic therapy.

PubMed

Natesan, Subramanian; Krishnaswami, Venkateshwaran; Ponnusamy, Chandrasekar; Madiyalakan, Madi; Woo, Thomas; Palanisamy, Rajaguru

2017-08-01

A nanoparticulate photodynamic approach was employed with an objective to achieve enhanced production of singlet oxygen ( 1 O 2 ), for the management of posterior segment eye diseases like age related macular degeneration. The hypocrellin B (HB) loaded poly lactide-co-glycolide nanoparticle formulations were incorporated with nano silver (HBS-NPs). The optimized HBS-NPs contained 2.60±0.06mg/mL of HB and showed (i) 135.6 to 828.2nm size range, and (ii) negative zeta potential with a narrow polydispersity index. The DSC thermograms suggested the amorphous nature of HB inside the HBS-NPs. With the average encapsulation efficiency of 92.9±1.79%, the drug release from the HBS-NPs followed a biphasic pattern with an initial burst of 3.50% during first 8h followed by a sustained release of 47.82% within 3days. The interaction between nano silver and HB as assessed by the increase in spectral intensity of Raman spectrum demonstrates that HB may be attached over the nano silver. Generation of reactive oxygen species (ROS) by HBS-NPs was significantly higher than that of HB/HB-NPs. The singlet oxygen generating efficiency assessed using EPR spectrometer follows the order of nano silver>HB-NPs>pure HB drug solution>HBS-NPs. The HBS-NPs had a concentration and time dependent phototoxicity on A549 (human adeno lung carcinoma) cells in the presence of light providing a superior phototoxic effect (82.2% at 50μM) at 2h irradiation. The CAM treated with HBS-NPs showed a significant anti-angiogenic effect compared to a blank formulation. In vivo biodistribution studies revealed that intravenous administration of HBS-NPs lead into significant exposure to the posterior segment of the eye. This proof of principle study demonstrates that HB based nanoparticles may be a valuable new tool for application in ocular photodynamic therapy for the treatment of AMD in future. Copyright © 2017 Elsevier B.V. All rights reserved.

Precise micropatterning of silver nanoparticles on plastic substrates

NASA Astrophysics Data System (ADS)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

2017-04-01

Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV-vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

Solid state synthesis of starch-capped silver nanoparticles.

PubMed

Hebeish, A; Shaheen, Th I; El-Naggar, Mehrez E

2016-06-01

The present research addresses the establishment of a technique which is solely devoted to environmentally friendly one-pot green synthesis of dry highly stable powdered silver nanoparticles (AgNPs) using starch as both reductant and stabilizing agent in the presence of sodium hydroxide. It is believed that the sodium hydroxide can improve the reduction potential of starch. Thus when the alkali treated starch is submitted to addition of silver nitrate (AgNO3), the alkali treated starch induces the well-established dual role of starch; reduction of silver ions (Ag(+)) to AgNPs and capping the as-formed AgNPs to prevent them from further growth and agglomeration. Beside assessment of AgNPs formation, structural and morphological characteristics of AgNPs are investigated by making use of UV-vis spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, FT-IR and X-ray diffraction (XRD) analysis. Research outputs signify (a) the absorbance around 410-420nm in the UV-vis spectra of AgNPs appears most, probably owing to the presence of nanosized silver particles and the intensity of this peak increases by increasing AgNO3 concentration; (b) that highly stable AgNPs with well-dispersed particle are successfully prepared using the present research-based innovation; (c) that the size of AgNPs does not exceed 30nm with sphere-like morphology even at the highest Ag(+) concentration employed during synthesis operation; (d) that the XRD and FT-IR confirm the successful preparation of pure AgNPs without noticeable impurities; (d) and that the one-pot synthesis of powdered AgNPs in large scale is clean and easily operated and easily transportation which may be applied as per demands of industries such as textile and painting industry. Copyright © 2016. Published by Elsevier B.V.

Synthesis and optical properties of silver nanoparticles

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

Singh, Jaiveer; Kaurav, Netram, E-mail: netramkaurav@yahoo.co.uk; Choudhary, K. K.

The preparation of stable, uniform silver nanoparticles by reduction of silver acetate by ethylene glycol (EG) is reported in the present paper. It is a simple process of recent interest for obtaining silver nanoparticles. The samples were characterized by X-Ray diffraction (XRD), which reveals an average particle size (D) of 38 nm. The UV/Vis spectra show that an absorption peak, occurring due to surface plasmon resonance (SPR), exists at 319 nm.

Hydrophobicity of silver surfaces with microparticle geometry

NASA Astrophysics Data System (ADS)

Macko, Ján; Oriňaková, Renáta; Oriňak, Andrej; Kovaľ, Karol; Kupková, Miriam; Erdélyi, Branislav; Kostecká, Zuzana; Smith, Roger M.

2016-11-01

The effect of the duration of the current deposition cycle and the number of current pulses on the geometry of silver microstructured surfaces and on the free surface energy, polarizability, hydrophobicity and thus adhesion force of the silver surfaces has been investigated. The changes in surface hydrophobicity were entirely dependent on the size and density of the microparticles on the surface. The results showed that formation of the silver microparticles was related to number of current pulses, while the duration of one current pulse played only a minor effect on the final surface microparticle geometry and thus on the surface tension and hydrophobicity. The conventional geometry of the silver particles has been transformed to the fractal dimension D. The surface hydrophobicity depended predominantly on the length of the dendrites not on their width. The highest silver surface hydrophobicity was observed on a surface prepared by 30 current pulses with a pulse duration of 1 s, the lowest one when deposition was performed by 10 current pulses with a duration of 0.1 s. The partial surface tension coefficients γDS and polarizability kS of the silver surfaces were calculated. Both parameters can be applied in future applications in living cells adhesion prediction and spectral method selection. Silver films with microparticle geometry showed a lower variability in final surface hydrophobicity when compared to nanostructured surfaces. The comparisons could be used to modify surfaces and to modulate human cells and bacterial adhesion on body implants, surgery instruments and clean surfaces.

Factors influencing the preparation of silver-coated glass frit with polyvinyl-pyrrolidone

NASA Astrophysics Data System (ADS)

Xiang, Feng; Gan, Weiping

2018-01-01

In this work, a new electroless silver plating method for the synthesis of silver-coated glass frit composite powders with good morphology has been proposed and the polyvinyl-pyrrolidone (PVP) was used the activating agent. It was found that the weight ratio of PVP to glass frit affected the distribution and number of silver nanoparticles. Moreover, the loading capacity of the glass frit, the pH value and reaction temperature could influence the size of the silver nanoparticles and morphology of silver on the surface of glass frit. The as-prepared silver-coated glass frit was used to prepare a silver paste using an optimized process to form silver nanoparticles with uniform size and high density. The silver paste with silver-coated glass frit increased the photovoltaic conversion efficiency of silicon solar cells by 0.271% compared with the silver paste prepared with pure glass frit. The silver nanoparticles can promoted the precipitation of Ag crystallites on the silicon wafer. Therefore, the silver-coated glass frit can further optimize and enhance the electrical performance of solar cells.

Draft genome sequence of the silver pomfret fish, Pampus argenteus.

PubMed

AlMomin, Sabah; Kumar, Vinod; Al-Amad, Sami; Al-Hussaini, Mohsen; Dashti, Talal; Al-Enezi, Khaznah; Akbar, Abrar

2016-01-01

Silver pomfret, Pampus argenteus, is a fish species from coastal waters. Despite its high commercial value, this edible fish has not been sequenced. Hence, its genetic and genomic studies have been limited. We report the first draft genome sequence of the silver pomfret obtained using a Next Generation Sequencing (NGS) technology. We assembled 38.7 Gb of nucleotides into scaffolds of 350 Mb with N50 of about 1.5 kb, using high quality paired end reads. These scaffolds represent 63.7% of the estimated silver pomfret genome length. The newly sequenced and assembled genome has 11.06% repetitive DNA regions, and this percentage is comparable to that of the tilapia genome. The genome analysis predicted 16 322 genes. About 91% of these genes showed homology with known proteins. Many gene clusters were annotated to protein and fatty-acid metabolism pathways that may be important in the context of the meat texture and immune system developmental processes. The reference genome can pave the way for the identification of many other genomic features that could improve breeding and population-management strategies, and it can also help characterize the genetic diversity of P. argenteus.

Bactericidal properties of silver films on intramedullary implants

NASA Astrophysics Data System (ADS)

Gallagher, C.; Walker, C.; Cortes, E.; Hettinger, Jeffrey; Krchnavek, R.; Caputo, G. A.; Ostrum, R.

2011-03-01

We report on investigations of silver films on titanium and stainless steel substrates as anti-bacterial coatings for intramedullary nails used in orthopedic trauma. Silver films are deposited using a magnetron sputtering technique from a single elemental target. The deposition parameter (energy, pressure, and temperature) dependence of the silver film microstructure and adhesion will be presented. Preliminary measurements of the effectiveness of the silver films as a bactericide on S. aureus bacteria demonstrate that the films are effective destroying the bacteria. The process of this investigation will be presented. Preliminary transmission electron microscopy measurements will also presented which image healthy and damaged bacteria helping to identify the fundamental mechanism leading to the effectiveness of silver as an anti-bacterial coating. We acknowledge the support of Rowan University, College of Liberal Arts and Sciences.

Comparative toxicity of silver nanoparticles and silver ions to Escherichia coli.

PubMed

Choi, Yoojin; Kim, Hyun-A; Kim, Kyoung-Woong; Lee, Byung-Tae

2018-04-01

With the increase in silver (Ag)-based products in our lives, it is essential to test the potential toxicity of silver nanoparticles (AgNPs) and silver ions (Ag ions) on living organisms under various conditions. Here, we investigated the toxicity of AgNPs with Ag ions to Escherichia coli K-12 strain under various conditions. We observed that both AgNPs and Ag ions display antibacterial activities, and that Ag ions had higher toxicity to E. coli K-12 strain than AgNPs under the same concentrations. To understand the toxicity of AgNPs at a cellular level, reactive oxygen species (ROS) enzymes were detected for use as antioxidant enzymatic biomarkers. We have also studied the toxicity of AgNPs and Ag ions under various coexistence conditions including: fixed total concentration, with a varied the ratio of AgNPs to Ag ions; fixed the AgNPs concentration and then increased the Ag ions concentration; fixed Ag ions concentration and then increasing the AgNPs concentration. Exposure to AgNPs and Ag ions clearly had synergistic toxicity; however, decreased toxicity (for a fixed AgNPs concentration of 5mg/L, after increasing the Ag ions concentration) to E. coli K-12 strain. AgNPs and Ag ions in the presence of L-cysteine accelerated the bacterial cell growth rate, thereby reducing the bioavailability of Ag ions released from AgNPs under the single and coexistence conditions. Further works are needed to consider this potential for AgNPs and Ag ions toxicity across a range of environmental conditions. As silver nanoparticles (AgNPs)-based products are being broadly used in commercial industries, an ecotoxicological understanding of the AgNPs being released into the environment should be further considered. Here, we investigate the comparative toxicity of AgNPs and silver ions (Ag ions) to Escherichia coli K-12 strain, a representative ecotoxicological bioreporter. This study showed that toxicities of AgNPs and Ag ions to E. coli K-12 strain display different relationships

Rate Dependency of Silver Vanadium Phosphorous Oxide Reduction

NASA Astrophysics Data System (ADS)

Cheng, Po-Jen

2011-12-01

The silver vanadium phosphorus oxide (Ag2VO2PO 4) is a high-capacity and good-compatibility material for the cathode in the battery. Due to their innovative properties, they are used as cathode in lithium batteries. Therefore, when the lithium batteries begin to discharge, the anodes of the cell perform an electrochemical oxidation and release electrons. In the mean time, the cathodes in the cells perform the electrochemical reduction and catch the electrons. For reduction of Ag2VO2PO 4, two silver ions (Ag+) catch two electrons to form silver particles, and the vanadium ions (V5+) catch two electrons to form V3+. It means that four electrons will be released by lithium anode. We call this four electrons discharge as 100% discharge. In my most of the projects, the Ag2VO2PO4 material is tested by differential scanning calorimetry (DSC) to check purity. My study is based on the discharge of batteries, and I focus on the morphology and the intensity of silver particles on the cathode after discharge. Depending on different adjustment of factors, such as discharge time, discharge rate, storage time, storage temperature, I try to investigate the silver intensity, conductivity as a function of DOD (Depth of Discharge). The silver particles could be examined by optical microscope, and scanning electron microscope (SEM). Moreover, I do some x-ray diffraction analysis to quantify the silver particles after discharge. Also, I perform magnetic susceptibility measurement to check the mechanism of the reduction of vanadium ions. Under the research on silver ions and vanadium ions, I will know a big frame of reduction process on silver vanadium phosphorous oxide and the time effect on this cathode material.

Antibacterial effect of gallium and silver on Pseudomonas aeruginosa treated with gallium-silver-phosphate-based glasses.

PubMed

Valappil, Sabeel P; Higham, Susan M

2014-01-01

Gallium and silver incorporated phosphate-based glasses were evaluated for antibacterial effect on the growth of Pseudomonas aeruginosa, which is a leading cause of opportunistic infections. The glasses were produced by conventional melt quenching methods at 1100°C for 1 h. Glass degradation studies were conducted by weight loss method. Disc diffusion assay and cell viability assay displayed statistically significant (p ≤ 0.0005) effect on P. aeruginosa growth which increased with decreasing calcium content in the glasses. The gallium ion release rates (1.83, 0.69 and 0.48 ppm·h(-1)) and silver ion release rates (2.97, 2.84 and 2.47 ppm·h(-1)) were found to account for this variation. Constant depth film fermentor was used to evaluate the anti-biofilm properties of the glasses. Both gallium and silver in the glass contributed to biofilm growth inhibitory effect on P. aeruginosa (up to 2.68 reduction in log 10 values of the viable counts compared with controls). The glasses were found to deliver gallium and silver in a controlled way and exerted cumulative antibacterial action on planktonic and biofilm growth of P. aeruginosa. The antibacterial, especially anti-biofilm, properties of the gallium and silver incorporated phosphate-based glasses make them a potential candidate to combat infections caused by P. aeruginosa.

Determination of gold in copper-bearing sulphide ores and metallurgical flotation products by atomic-absorption spectrometry.

PubMed

Strong, B; Murray-Smith, R

1974-12-01

A method is described which is specific for the determination of gold in sulphide copper ores and concentrates. Direct decomposition with aqua regia was found to be incomplete. A carefully controlled roasting stage followed by treatment with hydrochloric acid and then aqua regia was effective for dissolving all the gold. The gold is extracted into 4-methylpentan-2-one (methyli-sobutylketone) then aspirated into a very lean air-acetylene flame and the gold determined by atomic-absorption spectrometry. No interferences were observed from large concentrations of copper, iron or nickel.

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.

Capsaicin-capped silver nanoparticles: its kinetics, characterization and biocompatibility assay

NASA Astrophysics Data System (ADS)

Amruthraj, Nagoth Joseph; Preetam Raj, John Poonga; Lebel, Antoine

2015-04-01

Capsaicin was used as a bio-reductant for the reduction of silver nitrate to form silver nanoparticles. The formation of the silver nanoparticles was initially confirmed by color change and Tyndall effect of light scattering. It was characterized with UV-visible spectroscopy, FTIR and TEM. Hemagglutination (H) test and H-inhibition assay were performed in the presence of AgNPs-capsaicin conjugates. The silver colloid solution after complete reduction turned into pale gray color. The characteristic surface plasmon resonance of silver nanoparticles (SNPs) was observed at 450 nm. Time taken for complete bio-reduction of silver nitrate and capping was found to be 16 hours. The amount of capsaicin required to reduce 20 ml of 1 mM silver nitrate solution was found to be 40 μg approximately. The FTIR results confirmed the capping of capsaicin on the silver metal. The particle size was within the range of 20-30 nm. The hemagglutination and H-inhibition test was negative for all the blood groups. The capsaicin-capped silver nanoparticles were compatible with blood cells in hemagglutination test implying biocompatibility as future therapeutic drug.

The sorption of silver by poorly crystallized manganese oxides

USGS Publications Warehouse

Anderson, B.J.; Jenne, E.A.; Chao, T.T.

1973-01-01

The sorption of silver by poorly crystallized manganese oxides was studied using synthesized samples of three members of the manganous manganite (birnessite) group, of different chemical composition and crystallinity, and a poorly organized ??-MnO2. All four oxides sorbed significant quantities of silver. The manganous manganites showed the greatest sorption (up to 0.5 moles silver/mole MnOx at pH 7) while the ??-MnO2 showed the least (0.3 moles silver/ mole MnOx at pH 7). Sorption of silver was adequately described by the Langmuir equation over a considerable concentration range. The relationship failed at low pH values and high equilibrium silver concentrations. The sorption capacity showed a direct relationship with pH. However, the rate of increase of sorption capacity decreased at the higher pH values. Silver sorption maxima. were not directly related to surface area but appeared to vary with the amount of occluded sodium and potassium present in the manganese oxide. The important processes involved in the uptake of silver by the four poorly crystallized manganese oxides ara considered to be surface exchange for manganese, potassium and sodium as well as exchange for structural manganese, potassium and sodium. ?? 1973.

Recovery of Silver and Gold from Copper Anode Slimes

NASA Astrophysics Data System (ADS)

Chen, Ailiang; Peng, Zhiwei; Hwang, Jiann-Yang; Ma, Yutian; Liu, Xuheng; Chen, Xingyu

2015-02-01

Copper anode slimes, produced from copper electrolytic refining, are important industrial by-products containing several valuable metals, particularly silver and gold. This article provides a comprehensive overview of the development of the extraction processes for recovering silver and gold from conventional copper anode slimes. Existing processes, namely pyrometallurgical processes, hydrometallurgical processes, and hybrid processes involving the combination of pyrometallurgical and hydrometallurgical technologies, are discussed based in part on a review of the form and characteristics of silver and gold in copper anode slimes. The recovery of silver and gold in pyrometallurgical processes is influenced in part by the slag and matte/metal chemistry and related characteristics, whereas the extraction of these metals in hydrometallurgical processes depends on the leaching reagents used to break the structure of the silver- and gold-bearing phases, such as selenides. By taking advantage of both pyrometallurgical and hydrometallurgical techniques, high extraction yields of silver and gold can be obtained using such combined approaches that appear promising for efficient extraction of silver and gold from copper anode slimes.

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

Silver ion doped ceramic nano-powder coated nails prevent infection in open fractures: In vivo study.

PubMed

Kose, Nusret; Çaylak, Remzi; Pekşen, Ceren; Kiremitçi, Abdurrahman; Burukoglu, Dilek; Koparal, Savaş; Doğan, Aydın

2016-02-01

Despite improvement in operative techniques and antibiotic therapy, septic complications still occur in open fractures. We developed silver ion containing ceramic nano powder for implant coating to provide not only biocompatibility but also antibacterial activity to the orthopaedic implants. We hypothesised silver ion doped calcium phosphate based ceramic nano-powder coated titanium nails may prevents bacterial colonisation and infection in open fractures as compared with uncoated nails. 33 rabbits divided into three groups. In the first group uncoated, in the second group hydroxyapatite coated, and in the third group silver doped hydroxyapatite coated titanium nails were inserted left femurs of animals from knee regions with retrograde fashion. Before implantation of nails 50 μl solution containing 10(6)CFU/ml methicillin resistance Staphylococcus aureus (MRSA) injected intramedullary canal. Rabbits were monitored for 10 weeks. Blood was taken from rabbits before surgery and on 2nd, 6th and 10th weeks. Blood was analysed for biochemical parameters, blood count, C-reactive protein and silver levels. At the end of the 10 weeks animals were sacrificed and rods were extracted in a sterile fashion. Swab cultures were taken from intramedullary canal. Bacteria on titanium rods were counted. Liver, heart, spleen, kidney and central nervous tissues samples were taken for determining silver levels. Histopathological evaluation of bone surrounding implants was also performed. No significant difference was detected between the groups from hematologic, biochemical, and toxicological aspect. Microbiological results showed that less bacterial growth was detected with the use of silver doped ceramic coated implants compared to the other two groups (p=0.003). Accumulation of silver was not detected. No cellular inflammation was observed around the silver coated prostheses. No toxic effect of silver on bone cells was seen. Silver ion doped calcium phosphate based ceramic nano

Silver nasal sprays: misleading Internet marketing.

PubMed

Gaslin, Michael T; Rubin, Cory; Pribitkin, Edmund A

2008-04-01

Long-term use of silver-containing products is associated with a permanent bluish-gray discoloration of the skin known as argyria, but they remain widely available despite several measures by the FDA to regulate them. Several recent case reports have described the occurrence of argyria as a result of using these "natural" products. We used the five most common Internet search engines to find Web sites providing information on silver-containing nasal sprays. Of 49 Web sites analyzed, only 2 (4%) mentioned argyria as a possible complication, although 30 (61%) did caution against long-term use. Eight sites (16%) made specific claims about the health benefits of the product. All 49 sites (100%) provided direct or indirect links to buy silver-containing nasal sprays. We conclude that information about silver-containing nasal sprays on the Internet is misleading and inaccurate. Therefore, otolaryngologists should be aware of the misinformation their patients may be receiving about these products.