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

International Nuclear Information System (INIS)

Afanasiev, Pavel

2016-01-01

Silver nitrate hexamethylenetetramine [Ag(NO 3 )·N 4 (CH 2 ) 6 ] coordination compound has been prepared via aqueous route and characterized by chemical analysis, XRD and electron microscopy. Decomposition of [Ag(NO 3 )·N 4 (CH 2 ) 6 ] under hydrogen and under inert has been studied by thermal analysis and mass spectrometry. Thermal decomposition of [Ag(NO 3 )·N 4 (CH 2 ) 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 sponges exhibited favorable activity toward H 2 O 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 3 )·N 4 (CH 2 ) 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 3 )·N 4 (CH 2 ) 6 ] orthorhombic phase prepared and characterized. • Decomposition of [Ag(NO 3 )·N 4 (CH 2 ) 6 ] leads to metallic silver sponge with opened porosity. • Ag sponge showed promising properties as a material for hydrogen peroxide sensors.

Synthesis and crystal structure of bis(1-{[(quinolin-8-ylimino]methyl}pyrene-κ2N,N′silver(I trifluoromethanesulfonate

Directory of Open Access Journals (Sweden)

Miguel Pinto

2016-10-01

Full Text Available The title compound, [Ag(qPyr2]CF3SO3 where qPyr = 1-(quinoline-2-ylmethyleneaminopyrene, C26H16N2, was synthesized from a reaction of silver trifluoromethanesulfonate and qPyr in dichloromethane–methanol mixed media. In this design, the qPyr ligand was chosen for its characteristic excitation and emission profiles, which could enable the tracking of the silver complex within biological targets. The AgI atom resides in a distorted tetrahedral N4 coordination sphere. Analysis of the packing pattern revealed significant intra- and intermolecular π–π stacking interactions between the [Ag(qPyr2]+ cations. In addition, a weak C—H...O hydrogen bond consolidates the packing between cations and anions.

Silver nanoparticles are broad-spectrum bactericidal and virucidal compounds

Directory of Open Access Journals (Sweden)

Ixtepan-Turrent Liliana

2011-08-01

Full Text Available Abstract The advance in nanotechnology has enabled us to utilize particles in the size of the nanoscale. This has created new therapeutic horizons, and in the case of silver, the currently available data only reveals the surface of the potential benefits and the wide range of applications. Interactions between viral biomolecules and silver nanoparticles suggest that the use of nanosystems may contribute importantly for the enhancement of current prevention of infection and antiviral therapies. Recently, it has been suggested that silver nanoparticles (AgNPs bind with external membrane of lipid enveloped virus to prevent the infection. Nevertheless, the interaction of AgNPs with viruses is a largely unexplored field. AgNPs has been studied particularly on HIV where it was demonstrated the mechanism of antiviral action of the nanoparticles as well as the inhibition the transmission of HIV-1 infection in human cervix organ culture. This review discusses recent advances in the understanding of the biocidal mechanisms of action of silver Nanoparticles.

Alkyne-Azide Cycloaddition Catalyzed by Silver Chloride and “Abnormal” Silver N-Heterocyclic Carbene Complex

Directory of Open Access Journals (Sweden)

Aldo I. Ortega-Arizmendi

2013-01-01

Full Text Available A library of 1,2,3-triazoles was synthesized from diverse alkynes and azides using catalytic amounts of silver chloride instead of copper compounds. In addition, a novel “abnormal” silver N-heterocyclic carbene complex was tested as catalyst in this process. The results suggest that the reaction requires only 0.5% of silver complex, affording 1,2,3-triazoles in good yields.

Copper and silver halates

CERN Document Server

Woolley, EM; Salomon, M

2013-01-01

Copper and Silver Halates is the third in a series of four volumes on inorganic metal halates. This volume presents critical evaluations and compilations for halate solubilities of the Group II metals. The solubility data included in this volume are those for the five compounds, copper chlorate and iodate, and silver chlorate, bromate and iodate.

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

Energy Technology Data Exchange (ETDEWEB)

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 sponges 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.

Transmission electron microscopy for elucidating the impact of silver-based treatments (ionic silver versus nanosilver-containing coating) on the model yeast Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Despax, B; Saulou, C; Raynaud, P [Universite de Toulouse, UPS, INPT, LAPLACE, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Datas, L [Universite de Toulouse, UPS, INPT, CIRIMAT, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Mercier-Bonin, M [Universite de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse (France)

2011-04-29

After exposure to ionic silver or nanosilver-containing plasma coating, the same visual aspect of scanning transmission electron microscopy (STEM) images was observed for the model yeast Saccharomyces cerevisiae. The main common feature was the presence of electron-dense nodules all over the cell. However, high resolution TEM (HRTEM), STEM, energy dispersive x-ray microanalysis spectroscopy (EDS) and electron microdiffraction revealed some striking differences. Regarding ionic silver exposure, the formation of electron-dense nodules was related to the Ag{sup +} reactivity towards sulfur-containing compounds to form clusters with Ag{sub 2}S-like structures, together with the production of a few silver nanocrystals, mainly at the cell wall periphery. For nanosilver-based treatment, some sulfur-containing silver clusters preferentially located at the cell wall periphery were detected, together with nodules composed of silver, sulfur and phosphorus all over the cell. In both silver-based treatments, nitrogen and silver signals overlapped, confirming the affinity of silver entities for proteinaceous compounds. Moreover, in the case of nanosilver, interactions of silver with phosphorus-containing subcellular structures were indicated.

Synthesis, Crystal Structure and Luminescence Property of a New Silver(I) Dimer with Isonicotinic Acid

International Nuclear Information System (INIS)

Yuan, Qi; Liu, Bing

2005-01-01

The absorption spectrum was calculated from reflection spectrum by the Kubelka.Munk function. The energy gap of the title compound determined by extrapolation from the linear portion of the absorption edge in a (α/S) versus energy plot is 1.91 eV, which suggests that the title compound behaves as semiconductor. Isonicotinic acid (Iso), namely 4.pyridinecarboxylate, a multi.functional chelating and/or bridging ligand, has proved to be very powerful for the construction of multi. dimensional metal.organic coordination networks. Furthermore, The isonicotinic acid complexes has raised many interests in fluorescence probing with numerous potential applications for studies of microsecond diffusion and dynamics of membranes. Metal centers are potential carriers of electrochemical, magnetic, catalytic, or optical properties that may be introduced into the inorganic.organic hybrid materials. d"1"0 metals with rich photophysical and photochemical character have focused attentions to synthesize polynuclear complexes. Considering the versatile coordination abilities of Iso, we employ the ligand to coordinate with silver nitrate to fabricate a coordination complex with excellent fluorescence property. Herein we report the synthesis, crystal structure and fluorescence property of a new d"1"0 coordination dimer [Ag_2(Iso)_2(NO_3)_2

Studies on ternary silver sulfides; Fukugo gin ryukabutsu ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-10-31

Some sulfides containing silver show high ion mobility based on movability of silver, whose application is expected. Studies have been carried out centrally on synthesis of new compounds of ternary silver sulfides by elucidating the relationship among their compositions, structures and properties by means of crystal chemical studies mainly on their phase relationship. A few new compounds have been synthesized, such as the ones having the argyrodite family compound structure including transition metals. The synthesizing process takes a kind of turbulent liquid state structure at elevated temperatures because of movability of silver, but silver is fixed at low temperatures in different sites between skeleton structures made by other atoms. These studies on phase transfer, structures, and silver movability have been based on X-ray diffraction, infrared and Raman spectroscopic measurements, NMR, measurements of electric and thermal characteristics. For the studies related to compositions and structures of ternary metal sulfides which take compound crystalline structure, a structure analyzing method based on multi-dimensional hyperspatial groups was used. This paper reports the summary of the studies in seven chapters, and dwells on the remaining problems and future prospects. 158 refs., 114 figs., 65 tabs.

Adsorbed States of phosphonate derivatives of N-heterocyclic aromatic compounds, imidazole, thiazole, and pyridine on colloidal silver: comparison with a silver electrode.

Science.gov (United States)

Podstawka, Edyta; Olszewski, Tomasz K; Boduszek, Bogdan; Proniewicz, Leonard M

2009-09-03

Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of phosphonate derivatives of the N-heterocyclic aromatic compounds imidazole (ImMeP ([hydroxy(1H-imidazol-5-yl)methyl]phosphonic acid) and (ImMe)(2)P (bis[hydroxy-(1H-imidazol-4-yl)-methyl]phosphinic acid)), thiazole (BAThMeP (butylaminothiazol-2-yl-methyl)phosphonic acid) and BzAThMeP (benzylaminothiazol-2-yl-methyl)phosphonic acid)), and pyridine ((PyMe)(2)P (bis[(hydroxypyridin-3-yl-methyl)]phosphinic acid)) adsorbed on nanometer-sized colloidal particles. We compared these structures to those on a roughened silver electrode surface to determine the relationship between the adsorption strength and the geometry. For example, we showed that all of these biomolecules interact with the colloidal surface through aromatic rings. However, for BzAThMeP, a preferential interaction between the benzene ring and the colloidal silver surface is observed more so than that between the thiazole ring and this substrate. The PC(OH)C fragment does not take part in the adsorption process, and the phosphonate moiety of ImMeP and (ImMe)(2)P, being removed from the surface, only assists in this process.

Synthesis, Crystal Structure and Luminescence Property of a New Silver(I) Dimer with Isonicotinic Acid

Energy Technology Data Exchange (ETDEWEB)

Yuan, Qi [Pharmacy College of Henan University, Kaifeng (China); Liu, Bing [Chinese Academy of Sciences, Fuzhou (China)

2005-10-15

The absorption spectrum was calculated from reflection spectrum by the Kubelka.Munk function. The energy gap of the title compound determined by extrapolation from the linear portion of the absorption edge in a (α/S) versus energy plot is 1.91 eV, which suggests that the title compound behaves as semiconductor. Isonicotinic acid (Iso), namely 4.pyridinecarboxylate, a multi.functional chelating and/or bridging ligand, has proved to be very powerful for the construction of multi. dimensional metal.organic coordination networks. Furthermore, The isonicotinic acid complexes has raised many interests in fluorescence probing with numerous potential applications for studies of microsecond diffusion and dynamics of membranes. Metal centers are potential carriers of electrochemical, magnetic, catalytic, or optical properties that may be introduced into the inorganic.organic hybrid materials. d{sup 10} metals with rich photophysical and photochemical character have focused attentions to synthesize polynuclear complexes. Considering the versatile coordination abilities of Iso, we employ the ligand to coordinate with silver nitrate to fabricate a coordination complex with excellent fluorescence property. Herein we report the synthesis, crystal structure and fluorescence property of a new d{sup 10} coordination dimer [Ag{sub 2}(Iso){sub 2}(NO{sub 3}){sub 2}].

Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

Science.gov (United States)

Nguyen, Thi Kim Lan; Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Hien Nguyen, Quoc

2013-12-01

Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag+ dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag+ is occurred by hydrated electron (e-aq) and hydrogen atom (H•) generated during radiolysis of ethanol/water. The conversion doses (Ag+ → Ag0) were determined by UV-Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5-40 nm for Ag+ concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg-1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc.

A Case of Argyria Following Colloidal Silver Ingestion

OpenAIRE

Kwon, Hyok Bu; Lee, Joon Ho; Lee, Seung Ho; Lee, Ai Young; Choi, Jong Sun; Ahn, Yeon Soon

2009-01-01

Argyria is a rare cutaneous discoloration caused by the intake of silver or various compounds containing silver. We report a case of argyria in a 73-year-old male following ingestion of colloidal silver as an alternative medicine over 5 years. He had a diffuse, slate gray discoloration of his face and hands. A biopsy specimen from the face revealed brown-black extracellular granules in the upper dermis and between collagen bundles. We also found silver particles in the mucous of the colon. Th...

Improving the Vase life of Cut Carnation ‘Tempo’ (Dianthus carryophyllusL. Flower by Silver Thiosulphate and Silver Nano-Particles

Directory of Open Access Journals (Sweden)

D. Hashemabadi

2014-08-01

Full Text Available Nanometer-sized silver particle can be act as an anti-microbial compound. Thus, in this research, the efficacy of silver thiosulphate and silver nano-particles as antimicrobial agents in extending the vase-life of cut carnation flowers was evaluated. A factorial experiment carried out based on randomized completely blocks design with two factors: silver thiosulphate (0, 0.1, 0.2 and 0.3 mM and silver nano-particles (0, 5, 10 and 15 mg/L. Mean comparison of the data showed that the combined treatments of 0.3 mM silver thiosulphate + 15 mg/L silver nano-particles had the highest vase life, water uptake and super oxide dismutase enzyme. Thus, the mentioned above treatment was proposed to increase prolong vase life and improvement of water relations and control of stem end blockage. Based to results of this study, silver thiosulphate and silver nano-particles can be used for increasing postharvest longevity of cut carnation "Tempo".

Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

International Nuclear Information System (INIS)

Nguyen, Thi Kim Lan; Dang, Van Phu; Nguyen, Ngoc Duy; Le, Anh Quoc; Nguyen, Quoc Hien; Nguyen, Thuy Ai Trinh

2013-01-01

Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag + dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag + is occurred by hydrated electron (e − aq ) and hydrogen atom (H • ) generated during radiolysis of ethanol/water. The conversion doses (Ag + → Ag 0 ) were determined by UV–Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5–40 nm for Ag + concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg −1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc. (paper)

Estimation of silver in Ag-meta kaolinite by neutron activation

International Nuclear Information System (INIS)

Daniels, E.A.; Rao, S.M.

1981-01-01

The present work is based on the neutron activation of Ag-meta kaolinite for the determination of its silver content from the β-activity of the compound using standard tables which showed the percentage of silver in mixtures of silver nitrate and meta kaolinite of known composition against β-activity of the mixture activated under identical conditions. (author)

Chemical Separation on Silver Nanorods Surface Monitored by TOF-SIMS

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Ondrej Petruš

2017-01-01

Full Text Available The article introduces a possible chemical separation of a mixture of two compounds on the metal nanorods surface. A silver nanorods surface has been prepared by controlled electrochemical deposition in anodic alumina oxide (AAO template. Rhodamine 6G and 4-aminothiophenol have been directly applied to the sampling point on a silver nanorods surface in an aliquot mixture. The position of the resolved compounds was analysed by time-of-flight secondary ion mass spectrometry (TOF-SIMS which measured the fragments and the molecular ions of the two compounds separated on the silver nanorods surface. Rhodamine 6G has been preconcentrated as 1.5 mm radial from the sampling point while 4-aminothiophenol formed a continuous self-assembled monolayer on the silver nanorods surface with a maximum molecular ion intensity at a distance of 0.5 mm from the sampling point. The separation of the single chemical components from the two-component mixture over the examined silver nanostructured films could clearly be shown. A fast separation on the mentioned nanotextured films was observed (within 50 s. This procedure can be easily integrated into the micro/nanofluidic systems or chips and different detection systems can be applied.

Crystal structure of catena-poly[silver(I-μ-l-tyrosinato-κ2O:N

Directory of Open Access Journals (Sweden)

Aqsa Yousaf

2015-03-01

Full Text Available The title compound, [Ag(C9H10NO3]n, is a polymeric silver(I complex of l-tyrosine. The AgI atom is connected to N and O atoms of two different l-tyrosine ligands in an almost linear arrangement, with an Ni—Ag—O1 bond angle of 173.4 (2° [symmetry code: (i x + 1, y, z]. The Ag—Ni and Ag—O bond lengths are 2.156 (5 and 2.162 (4 Å, respectively. The polymeric chains extend along the crystallographic a axis. Strong hydrogen bonds of the N—H...O and O—H...O types and additional C—H...O interactions connect these chains into a double-layer polymeric network in the ab plane.

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

Science.gov (United States)

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.

Mineral commodity profiles: Silver

Science.gov (United States)

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

Generation of Hybrid Peptide-Silver Nanoparticles for Antibacterial and Antifouling Applications

KAUST Repository

Seferji, Kholoud

2018-01-01

and antifouling agents. Our innovative antibacterial agents are hybrid peptide silver nanoparticles (CH-01-AgNPs) that are created de novo and in situ from a silver nitrate solution (AgNO3) in the presence of ultrashort self-assembling peptides compounds

Silver diamine fluoride: a caries "silver-fluoride bullet".

Science.gov (United States)

Rosenblatt, A; Stamford, T C M; Niederman, R

2009-02-01

The antimicrobial use of silver compounds pivots on the 100-year-old application of silver nitrate, silver foil, and silver sutures for the prevention and treatment of ocular, surgical, and dental infections. Ag(+) kills pathogenic organisms at concentrations of linings, water purification systems, hospital gowns, and caries prevention. To distill the current best evidence relative to caries, this systematic review asked: Will silver diamine fluoride (SDF) more effectively prevent caries than fluoride varnish? A five-database search, reference review, and hand search identified 99 human clinical trials in three languages published between 1966 and 2006. Dual review for controlled clinical trials with the patient as the unit of observation, and excluding cross-sectional, animal, in vitro studies, and opinions, identified 2 studies meeting the inclusion criteria. The trials indicated that SDF's lowest prevented fractions for caries arrest and caries prevention were 96.1% and 70.3%, respectively. In contrast, fluoride varnish's highest prevented fractions for caries arrest and caries prevention were 21.3% and 55.7%, respectively. Similarly, SDF's highest numbers needed to treat for caries arrest and caries prevention were 0.8 (95% CI=0.5-1.0) and 0.9 (95% CI=0.4-1.1), respectively. For fluoride varnish, the lowest numbers needed to treat for caries arrest and prevention were 3.7 (95% CI=3.4-3.9) and 1.1 (95% CI=0.7-1.4), respectively. Adverse events were monitored, with no significant differences between control and experimental groups. These promising results suggest that SDF is more effective than fluoride varnish, and may be a valuable caries-preventive intervention. As well, the availability of a safe, effective, efficient, and equitable caries-preventive agent appears to meet the criteria of both the WHO Millennium Goals and the US Institute of Medicine's criteria for 21st century medical care.

Gravimetric and volumetric determination of the purity of electrolytically refined silver and the produced silver nitrate

Directory of Open Access Journals (Sweden)

Ačanski Marijana M.

2007-01-01

Full Text Available Silver is, along with gold and the platinum-group metals, one of the so called precious metals. Because of its comparative scarcity, brilliant white color, malleability and resistance to atmospheric oxidation, silver has been used in the manufacture of coins and jewelry for a long time. Silver has the highest known electrical and thermal conductivity of all metals and is used in fabricating printed electrical circuits, and also as a coating for electronic conductors. It is also alloyed with other elements such as nickel or palladium for use in electrical contacts. The most useful silver salt is silver nitrate, a caustic chemical reagent, significant as an antiseptic and as a reagent in analytical chemistry. Pure silver nitrate is an intermediate in the industrial preparation of other silver salts, including the colloidal silver compounds used in medicine and the silver halides incorporated into photographic emulsions. Silver halides become increasingly insoluble in the series: AgCl, AgBr, AgI. All silver salts are sensitive to light and are used in photographic coatings on film and paper. The ZORKA-PHARMA company (Sabac, Serbia specializes in the production of pharmaceutical remedies and lab chemicals. One of its products is chemical silver nitrate (argentum-nitricum (l. Silver nitrate is generally produced by dissolving pure electrolytically refined silver in hot 48% nitric acid. Since the purity of silver nitrate, produced in 2002, was not in compliance with the p.a. level of purity, there was doubt that the electrolytically refined silver was pure. The aim of this research was the gravimetric and volumetric determination of the purity of electrolytically refined silver and silver nitrate, produced industrially and in a laboratory. The purity determination was carried out gravimetrically, by the sedimentation of silver(I ions in the form of insoluble silver salts: AgCl, AgBr and Agi, and volumetrically, according to Mohr and Volhardt. The

Waste treatment in NUCEF facility with silver mediated electrochemical oxidation technique

International Nuclear Information System (INIS)

Umeda, M.; Sugikawa, S.

2000-01-01

Silver mediated electrochemical oxidation technique has been considered one of promising candidates for alpha-bearing waste treatment. Destruction tests of organic compounds, such as insoluble tannin, TBP and dodecane, were carried out by this technique and the experimental data such as destruction rates, current efficiencies and intermediates were obtained. These compounds could be completely mineralized without the formation of reactive organic nitrate associated to safety hazards. On the basis of these results, the applicability of silver mediated electrochemical oxidation technique to waste treatment in NUCEF was evaluated. (authors)

Synthesis and characterization of nanophased silver tungstate

Indian Academy of Sciences (India)

nanoparticles were examined with scanning electron microscope (A Lieca Stereoscan. 440 model SEM) at an ... SEM image of rod-like nanocrystalline silver tungstate. Figure 3. ... Thermal analysis shows that the compound is thermally stable ...

Silver release and antimicrobial properties of PMMA films doped with silver ions, nano-particles and complexes

Energy Technology Data Exchange (ETDEWEB)

Lyutakov, O., E-mail: lyutakoo@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic); Goncharova, I. [Department of Analytical Chemistry, Institute of Chemical Technology, Prague (Czech Republic); Rimpelova, S. [Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague (Czech Republic); Kolarova, K.; Svanda, J.; Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology, Prague (Czech Republic)

2015-04-01

Materials prepared on the base of bioactive silver compounds have become more and more popular due to low microbial resistance to silver. In the present work, the efficiency of polymethylmethacrylate (PMMA) thin films doped with silver ions, nanoparticles and silver–imidazole polymer complex was studied by a combination of AAS, XPS and AFM techniques. The biological activities of the proposed materials were discussed in view of the rate of silver releasing from the polymer matrix. Concentrations of Ag active form were estimated by its ability to interact with L-cysteine using electronic circular dichroism spectroscopy. Rates of the released silver were compared with the biological activity in dependence on the form of embedded silver. Antimicrobial properties of doped polymer films were studied using two bacterial strains: Staphylococcus epidermidis and Escherichia coli. It was found that PMMA films doped with Ag{sup +} had greater activity than those doped with nanoparticles and silver–imidazole polymeric complexes. However, the antimicrobial efficiency of Ag{sup +} doped films was only short-term. Contrary, the antimicrobial activity of silver–imidazole/PMMA films increased in time of sample soaking. - Highlights: • PMMA thin films doped with silver ions, nanoparticles (AgNPs) and silver–imidazole helical complexes (AgIm) were studied. • Silver release from doped polymer films and its biological activity were estimated. • Antimicrobial properties of doped polymer films were also studied. • Ag ions doped films showed the strongest antimicrobial activity, which quickly disappeared. • AgIm and AgNPs doped films showed more stable antimicrobial properties. • AgIm complexes conserve their structure after addition into polymer and after leaching.

Silver release and antimicrobial properties of PMMA films doped with silver ions, nano-particles and complexes

International Nuclear Information System (INIS)

Lyutakov, O.; Goncharova, I.; Rimpelova, S.; Kolarova, K.; Svanda, J.; Svorcik, V.

2015-01-01

Materials prepared on the base of bioactive silver compounds have become more and more popular due to low microbial resistance to silver. In the present work, the efficiency of polymethylmethacrylate (PMMA) thin films doped with silver ions, nanoparticles and silver–imidazole polymer complex was studied by a combination of AAS, XPS and AFM techniques. The biological activities of the proposed materials were discussed in view of the rate of silver releasing from the polymer matrix. Concentrations of Ag active form were estimated by its ability to interact with L-cysteine using electronic circular dichroism spectroscopy. Rates of the released silver were compared with the biological activity in dependence on the form of embedded silver. Antimicrobial properties of doped polymer films were studied using two bacterial strains: Staphylococcus epidermidis and Escherichia coli. It was found that PMMA films doped with Ag + had greater activity than those doped with nanoparticles and silver–imidazole polymeric complexes. However, the antimicrobial efficiency of Ag + doped films was only short-term. Contrary, the antimicrobial activity of silver–imidazole/PMMA films increased in time of sample soaking. - Highlights: • PMMA thin films doped with silver ions, nanoparticles (AgNPs) and silver–imidazole helical complexes (AgIm) were studied. • Silver release from doped polymer films and its biological activity were estimated. • Antimicrobial properties of doped polymer films were also studied. • Ag ions doped films showed the strongest antimicrobial activity, which quickly disappeared. • AgIm and AgNPs doped films showed more stable antimicrobial properties. • AgIm complexes conserve their structure after addition into polymer and after leaching

Silver enhancement of nanogold and undecagold

Energy Technology Data Exchange (ETDEWEB)

Hainfield, J.F.; Furuya, F.R.

1995-07-01

A recent advance in immunogold technology has been the use of molecular gold instead of colloidal gold. A number of advantages are realized by this approach, such as stable covalent, site-specific attachment, small probe size and absence of aggregates for improved penetration. Silver enhancement has led to improved and unique results for electron and light microscopy, as well as their use with blots and gels. Most previous work with immunogold silver staining has been done with colloidal gold particles. More recently, large gold compounds (``clusters``) having a definite number of gold atoms and defined organic shell, have been used, frequently with improved results. These gold dusters, large compared to simple compounds, are, however, at the small end of the colloidal gold scale in size; undecagold is 0.8 nm and Nanogold is 1.4 nm. They may be used in practically all applications where colloidal gold is used (Light and electron microscopy, dot blots, etc.) and in some unique applications, where at least the larger colloidal golds don`t work, such as running gold labeled proteins on gels (which are later detected by silver enhancement). The main differences between gold clusters and colloidal golds are the small size of the dusters and their covalent attachment to antibodies or other molecules.

In situ synthesis of silver benzene-dithiolate hybrid films

Energy Technology Data Exchange (ETDEWEB)

Brenier, Roger, E-mail: roger.brenier@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Piednoir, Agnès, E-mail: agnes.piednoir@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Bertorelle, Franck, E-mail: franck.bertorelle@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Penuelas, José, E-mail: jose.penuelas@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France); Grenet, Geneviève, E-mail: genevieve.grenet@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France)

2016-02-01

In this article, a method for in situ synthesis of silver benzene-dithiolate hybrid films is presented. Silver nanoparticles, generated on ZrO{sub 2} films, are transformed into silver benzene 1,4-dithiolate or, partially, into silver benzene 1,2-dithiolate after sample immersion in the corresponding thiol solutions. These transformations occur at room temperature owing to the catalytic action of ZrO{sub 2}. It is also shown that TiO{sub 2} in place of ZrO{sub 2} is very efficient, both for the catalytic generation of silver nanoparticles and for their further transformation in benzene 1,4-dithiolate compound. This latter semiconductor has an optical bandgap of about 3 eV and the film is made of touching nanoparticles in an amorphous state. Our work has potential applications in the electronic and photovoltaic fields. - Highlights: • A method for in situ synthesis of silver benzene-dithiolate hybrid semiconductor films is presented. • Silver nanoparticles are, first, generated on ZrO{sub 2} or on TiO{sub 2} coated silica substrates. • The samples are immersed in benzene dithiol solution for two days at room temperature. • During the immersion, the silver nanoparticles are transformed into silver benzene dithiolate. • The silver benzene dithiolate film is made of amorphous nanoparticles with a banbgap of 3 eV.

Silver-Catalyzed Cyclopropanation of Alkenes Using N-Nosylhydrazones as Diazo Surrogates.

Science.gov (United States)

Liu, Zhaohong; Zhang, Xinyu; Zanoni, Giuseppe; Bi, Xihe

2017-12-15

An efficient silver-catalyzed [2 + 1] cyclopropanation of sterically hindered internal alkenes with diazo compounds in which room-temperature-decomposable N-nosylhydrazones are used as diazo surrogates is reported. The unexpected unique catalytic activity of silver was ascribed to its dual role as a Lewis acid activating alkene substrates and as a transition metal forming silver carbenoids. A wide range of internal alkenes, including challenging diarylethenes, were suitable for this protocol, thereby affording a variety of cyclopropanes with high efficiency in a stereoselective manner under mild conditions.

Green synthesis of silver nanoparticles using biopolymers, carboxymethylated-curdlan and fucoidan

International Nuclear Information System (INIS)

Leung, Thomas Chun-Yiu; Wong, Chung Kai; Xie Yong

2010-01-01

There is a growing need in developing a reliable and eco-friendly methodology for the synthesis of metallic nanoparticles, which may be applied for many nanotechnological applications. Natural compounds such as biopolymers are one of the resources which could be used for this purpose. The present study involves the development of a simple, ecological and user-friendly method in synthesizing silver nanoparticles by using carboxymethylated-curdlan or fucoidan as reducing and stabilizing agents. Reduction of silver ions by these biopolymers occurred when heating at 100 deg. C, led to the formation of silver nanoparticles in the range of 40-80 nm in dimensions. The silver nanoparticles were formed readily within 10-15 min. Morphological observation and characterization of the silver nanoparticles were performed by using dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM), and UV-vis absorption spectrophotometer. The size of silver nanoparticles can be controlled by using different concentrations of carboxymethylated-curdlan, fucoidan or silver nitrate. This way of silver nanoparticles preparation is easy, fast, user-friendly and suitable for large-scale production.

Optimization of silver-dielectric-silver nanoshell for sensing applications

International Nuclear Information System (INIS)

Shirzaditabar, Farzad; Saliminasab, Maryam

2013-01-01

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

ATP7B detoxifies silver in ciliated airway epithelial cells

International Nuclear Information System (INIS)

Ibricevic, Aida; Brody, Steven L.; Youngs, Wiley J.; Cannon, Carolyn L.

2010-01-01

Silver is a centuries-old antibiotic agent currently used to treat infected burns. The sensitivity of a wide range of drug-resistant microorganisms to silver killing suggests that it may be useful for treating refractory lung infections. Toward this goal, we previously developed a methylated caffeine silver acetate compound, SCC1, that exhibits broad-spectrum antimicrobial activity against clinical strains of bacteria in vitro and when nebulized to lungs in mouse infection models. Preclinical testing of high concentrations of SCC1 in primary culture mouse tracheal epithelial cells (mTEC) showed selective ciliated cell death. Ciliated cell death was induced by both silver- and copper-containing compounds but not by the methylated caffeine portion of SCC1. We hypothesized that copper transporting P-type ATPases, ATP7A and ATP7B, play a role in silver detoxification in the airway. In mTEC, ATP7A was expressed in non-ciliated cells, whereas ATP7B was expressed only in ciliated cells. The exposure of mTEC to SCC1 induced the trafficking of ATP7B, but not ATP7A, suggesting the presence of a cell-specific silver uptake and detoxification mechanisms. Indeed, the expression of the copper uptake protein CTR1 was also restricted to ciliated cells. A role of ATP7B in silver detoxification was further substantiated when treatment of SCC1 significantly increased cell death in ATP7B shRNA-treated HepG2 cells. In addition, mTEC from ATP7B -/- mice showed enhanced loss of ciliated cells compared to wild type. These studies are the first to demonstrate a cell type-specific expression of the Ag + /Cu + transporters ATP7A, ATP7B, and CTR1 in airway epithelial cells and a role for ATP7B in detoxification of these metals in the lung.

[Exposure to metal compounds in occupational galvanic processes].

Science.gov (United States)

Surgiewicz, Jolanta; Domański, Wojciech

2006-01-01

Occupational galvanic processes are provided in more than 600 small and medium enterprises in Poland. Workers who deal with galvanic coating are exposed to heavy metal compounds: tin, silver, copper and zinc. Some of them are carcinogenic, for example, hexavalent chromium compounds, nickel and cadmium compounds. Research covered several tens of workstations involved in chrome, nickel, zinc, tin, silver, copper and cadmium plating. Compounds of metals present in the air were determined: Cr, Ni, Cd, Sn, Ag--by atomic absorption spectrometry with electrothermal atomization (ET-AAS) and Zn--by atomic absorption spectrometry with flame atomization (F-AAS). The biggest metal concentrations--of silver and copper--were found at workstations of copper, brass, cadmium, nickel and chrome plating, conducted at the same time. Significant concentrations of copper were found at workstations of maintenance bathing and neutralizing of sewage. The concentrations of metals did not exceed Polish MAC values. MAC values were not exceeded for carcinogenic chromium(VI), nickel or cadmium, either. In galvanic processes there was no hazard related to single metals or their compounds, even carcinogenic ones. Combined exposure indicators for metals at each workstation did not exceed 1, either. However, if there are even small quantities of carcinogenic agents, health results should always be taken into consideration.

Silver nanostructures in laser desorption/ionization mass spectrometry and mass spectrometry imaging.

Science.gov (United States)

Sekuła, Justyna; Nizioł, Joanna; Rode, Wojciech; Ruman, Tomasz

2015-09-21

Silver nanoparticles have been successfully applied as a matrix replacement for the laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS). Nanoparticles, producing spectra with highly reduced chemical background in the low m/z region, are perfectly suited for low-molecular weight compound analysis and imaging. Silver nanoparticles (AgNPs) can efficiently absorb ultraviolet laser radiation, transfer energy to the analyte and promote analyte desorption, but also constitute a source of silver ions suitable for analyte cationisation. This review provides an overview of the literature on silver nanomaterials as non-conventional desorption and ionization promoters in LDI-MS and mass spectrometry imaging.

A novel wound rinsing solution based on nano colloidal silver

Directory of Open Access Journals (Sweden)

Soheila Kordestani

2014-10-01

Full Text Available Objective(s: The present study aimed to investigate the antiseptic properties of a colloidal nano silver wound rinsing solution to inhibit a wide range of pathogens including bacteria, viruses and fungus present in chronic and acute wounds. Materials and Methods:The wound rinsing solution named SilvoSept® was prepared using colloidal nano silver suspension. Physicochemical properties, effectiveness against microorganism including  Staphylocoocous aureus ATCC 6538P, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 8739 ,Candida albicans ATCC 10231, Aspergillus niger ATCC 16404, MRSA , Mycobacterium spp. , HSV-1 and H1N1, and biocompatibility tests were carried out according to relevant standards . Results: X-ray diffraction (XRD scan was performed on the sample and verify single phase of silver particles in the compound. The size of the silver particles in the solution, measured by dynamic light scattering (DLS techniqu, ranged 80-90 nm. Transmission electron microscopy (TEM revealed spherical shape with smooth surface of the silver nanoparticles. SilvoSept® reduced 5 log from the initial count of 107 CFU/mL of Staphylocoocous aureus ATCC 6538P, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 8739, Candida albicans ATCC 10231, Aspergillus niger ATCC 16404, MRSA, Mycobacterium spp. Further assessments of SilvoSept solution exhibited a significant inhibition on the replication of HSV-1 and H1N1. The biocompatibility studies showed that the solution was non-allergic, non-irritant and noncytotoxic. Conclusion: Findings of the present study showed that SilvoSept® wound rinsing solution containing nano silver particles is an effective antiseptic solution against a wide spectrum of microorganism. This compound can be a suitable candidate for wound irrigation.   

Precise micropatterning of silver nanoparticles on plastic substrates

International Nuclear Information System (INIS)

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

2017-01-01

Highlights: • Silver ink has been deposited on plastic substrate and silver nanoparticles have been produced. • 3D control allows both ink superimposing and deposition on complicated surfaces. • Polyol method ensures the formation of metallic mircopatterns with high uniformity. • Substrate wettability, ink volume, and sintering temperature influences deposited patterns. - Abstract: 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.

Precise micropatterning of silver nanoparticles on plastic substrates

Energy Technology Data Exchange (ETDEWEB)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A., E-mail: tapani.pakkanen@uef.fi

2017-04-15

Highlights: • Silver ink has been deposited on plastic substrate and silver nanoparticles have been produced. • 3D control allows both ink superimposing and deposition on complicated surfaces. • Polyol method ensures the formation of metallic mircopatterns with high uniformity. • Substrate wettability, ink volume, and sintering temperature influences deposited patterns. - Abstract: 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.

Silver iodide reduction in aqueous solution: application to iodine enhanced separation during spent nuclear fuels reprocessing

International Nuclear Information System (INIS)

Badie, Jerome

2002-01-01

Silver iodide is a key-compound in nuclear chemistry either in accidental conditions or during the reprocessing of spent nuclear fuel. In that case, the major part of iodine is released in molecular form into the gaseous phase at the time of dissolution in nitric acid. In French reprocessing plants, iodine is trapped in the dissolver off-gas treatment unit by two successive steps: the first consists in absorption by scrubbing with a caustic soda solution and in the second, residual iodine is removed from the gaseous stream before the stack by chemisorption on mineral porous traps made up of beds of amorphous silica or alumina porous balls impregnated with silver nitrate. Reactions of iodine species with the impregnant are assumed to lead to silver iodide and silver iodate. Enhanced separation policy would make necessary to recover iodine from the filters by silver iodide dissolution during a reducing treatment. After a brief silver-iodine chemical bibliographic review, the possible reagents listed in the literature were studied. The choice has been made to use ascorbic acid and hydroxylamine. An experimental work on silver iodide reduction by this two compounds allowed us to determinate reaction products, stoichiometry and kinetics parameters. Finally, the process has been initiated on stable iodine loaded filters samples. (author) [fr

Graphene coatings for chemotherapy: avoiding silver-mediated degradation

International Nuclear Information System (INIS)

Mazzola, Federico; Cooil, Simon; Skjønsfjell, Eirik Torbjørn Bakken; Breiby, Dag W; Wells, Justin W; Trinh, Thuat; Kjelstrup, Signe; Østli, Elise Ramleth; Høydalsvik, Kristin; Preobrajenski, Alexei; Cafolla, Attilio A; Evans, D Andrew

2015-01-01

Chemotherapy treatment usually involves the delivery of fluorouracil (5-Fu) together with other drugs through central venous catheters. Catheters and their connectors are increasingly treated with silver or argentic alloys/compounds. Complications arising from broken catheters are common, leading to additional suffering for patients and increased medical costs. Here, we uncover a likely cause of such failure through a study of the surface chemistry relevant to chemotherapy drug delivery, i.e. between 5-Fu and silver. We show that silver catalytically decomposes 5-Fu, compromising the efficacy of the chemotherapy treatment. Furthermore, HF is released as a product, which will be damaging to both patient and catheter. We demonstrate that graphene surfaces inhibit this undesirable reaction and would offer superior performance as nanoscale coatings in cancer treatment applications. (paper)

Comparison on Bactericidal and Cytotoxic Effect of Silver Nanoparticles Synthesized by Different Methods

Science.gov (United States)

Mala, R.; Celsia, A. S. Ruby; Malathi Devi, S.; Geerthika, S.

2017-08-01

Biologically synthesized silver nanoparticle are biocompatible for medical applications. The present work is aimed to synthesize silver nanoparticle using the fruit pulp of Tamarindusindica and to evaluate its antibacterial and anticancer activity against lung cancercell lines. Antibacterial activity was assessed by well diffusion method. Cytotoxicity was evaluated using MTT assay. GC-MS of fruit pulp extract showed the presence of levoglucosenone, n-hexadecanoic acid, 9,12-octadecadienoic acid etc. Antioxidant activity of the fruit pulp was determined by DPPH assay, hydrogen peroxide scavenging assay and lipid peroxidation. The size of biologically synthesized silver nanoparticle varied from 50 nm to 76 nm. It was 59 nm to 98 nm for chemically synthesized silver nanoparticle. Biologically synthesized silver nanoparticle showed 26 mm inhibition zone against E. coli and chemically synthesized silver nanoparticle showed 20 mm. Antioxidant activity of fruit extract by DPPH showed 84 % reduction. The IC 50 of biologically synthesized silver nanoparticle against lung cancer cell lines was 48 µg/ml. It was 95 µg/ml for chemically synthesized silver nanoparticle. The increased activity of biologically synthesized silver nanoparticle was due to its smaller size, stability and the bioactive compounds capping the silver nanoparticle extracted from the fruit extract.

Antibacterial potential of silver nanoparticle synthesized by marine ...

African Journals Online (AJOL)

Multi resistance to antibiotics is a serious and disseminated clinical problem, common to several new compounds that block the resistance mechanism. The present study aimed at the comparative study of silver nanoparticles synthesized through actinomycetes and their antimicrobial metabolites with standard antibiotic.

Characterization and antibacterial properties of porous fibers containing silver ions

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhaoyang; Fan, Chenxu; Tang, Xiaopeng; Zhao, Jianghui; Song, Yanhua; Shao, Zhongbiao [National Engineering Laboratory for Modern Silk, College of Textile and Engineering, Soochow University, 199 Ren-ai Road, Suzhou 215123 (China); Xu, Lan, E-mail: lanxu@suda.edu.cn [National Engineering Laboratory for Modern Silk, College of Textile and Engineering, Soochow University, 199 Ren-ai Road, Suzhou 215123 (China); Nantong Textile Institute of Soochow University, 58 Chong-chuan Road, Nantong 226018 (China)

2016-11-30

Highlights: • Antibacterial electrospun PLA porous fibers containing silver ions were prepared. • Porous structure and porosity of PLA/Ag{sup +} porous fibers were investigated. • The antibacterial effects of PLA/Ag{sup +} porous fibers were studied. • The released mechanism of silver ions in the porous fibers was illustrated. • The porous structure could improve the antibacterial properties. - Abstract: Materials prepared on the base of bioactive silver compounds have become more and more popular. In the present work, the surface morphology, structure and properties, of electrospun Polylactide Polylactic acid (PLA) porous fibers containing various ratios of silver ions were investigated by a combination of X-ray photoelectron spectroscopy (XPS), universal testing machine, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and et al. The biological activities of the proposed porous fibers were discussed in view of the released silver ions concentration. Antibacterial properties of these porous fibers were studied using two bacterial strains: Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Results of the antibacterial testing suggested that PLA porous fibers containing silver ions could be used as potent antibacterial wound dressing materials in the biomedical field.

Characterization and antibacterial properties of porous fibers containing silver ions

International Nuclear Information System (INIS)

Sun, Zhaoyang; Fan, Chenxu; Tang, Xiaopeng; Zhao, Jianghui; Song, Yanhua; Shao, Zhongbiao; Xu, Lan

2016-01-01

Highlights: • Antibacterial electrospun PLA porous fibers containing silver ions were prepared. • Porous structure and porosity of PLA/Ag + porous fibers were investigated. • The antibacterial effects of PLA/Ag + porous fibers were studied. • The released mechanism of silver ions in the porous fibers was illustrated. • The porous structure could improve the antibacterial properties. - Abstract: Materials prepared on the base of bioactive silver compounds have become more and more popular. In the present work, the surface morphology, structure and properties, of electrospun Polylactide Polylactic acid (PLA) porous fibers containing various ratios of silver ions were investigated by a combination of X-ray photoelectron spectroscopy (XPS), universal testing machine, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and et al. The biological activities of the proposed porous fibers were discussed in view of the released silver ions concentration. Antibacterial properties of these porous fibers were studied using two bacterial strains: Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Results of the antibacterial testing suggested that PLA porous fibers containing silver ions could be used as potent antibacterial wound dressing materials in the biomedical field.

One-step green synthesis and characterization of leaf extract-mediated biocompatible silver and gold nanoparticles from Memecylon umbellatum

Science.gov (United States)

Arunachalam, Kantha D; Annamalai, Sathesh Kumar; Hari, Shanmugasundaram

2013-01-01

In this experiment, green-synthesized silver and gold nanoparticles were produced rapidly by treating silver and gold ions with an extract of Memecylon umbellatum leaf. The reaction process was simple and easy to handle, and was monitored using ultraviolet-visible spectroscopy. The effect of the phytochemicals present in M. umbellatum, including saponins, phenolic compounds, phytosterols, and quinones, on formation of stable silver and gold nanoparticles was investigated by Fourier-transform infrared spectroscopy. The morphology and crystalline phase of the nanoparticles were determined by transmission electron microscopy and energy-dispersive x-ray spectroscopy. The results indicate that the saponins, phytosterols, and phenolic compounds present in the plant extract play a major role in formation of silver and gold nanoparticles in their respective ions in solution. The characteristics of the nanoparticles formed suggest application of silver and gold nanoparticles as chemical sensors in the future. Given the simple and eco-friendly approach for synthesis, these nanoparticles could easily be commercialized for large-scale production. PMID:23569372

Green synthesis of silver nanoparticles and silver colloidal solutions

International Nuclear Information System (INIS)

Nguyen Thi Phuong Phong; Ngo Hoang Minh; Ngo Vo Ke Thanh; Dang Mau Chien

2009-01-01

In this paper, silver colloidal solutions have been synthesized rapidly in green conditions by using microwave irradiation and non-toxic chemistry substances (acid oxalic, silver nitrate, polyvinyl pyrolidone (PVP; Mw = 55 000)). The particle size and morphology of these solutions can be controlled by altering several factors like the time, the power of microwave exposure, and the ratio of silver oxalate and PVP etc. The silver nanoparticles were fabricated by thermal decomposition of silver oxalate. The synthesized silver colloidal solutions and silver nanoparticles were characterized by several analytical techniques like UV- VIS, XRD, TEM, FESEM/EDS and ICP-AAS studies. Finally, we used the synthesized silver colloidal solutions for antibacterial purpose. The obtained results showed that the synthesized silver colloidal solutions, even at very low concentrations, have highly efficient anti-bacterial property.

The Nevada Family: Political Crisis Leadership and Resilience Narratives in the Silver State

Science.gov (United States)

2017-12-01

POLITICAL CRISIS LEADERSHIP AND RESILIENCE NARRATIVES IN THE SILVER STATE by Caleb S. Cage December 2017 Thesis Advisor: Carolyn...2017 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE THE NEVADA FAMILY: POLITICAL CRISIS LEADERSHIP AND RESILIENCE... leadership , whereas applying the five tasks during the crisis amounts to political crisis management. Since the most important of these tasks for a

Development of Silver-exchanged Adsorbents for the Removal of Fission Iodine from Alkaline Dissolution

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Woon; Lee, Seung Kon; Lee, Su Seung; Lee, Jun Sig [KAERI, Daejeon (Korea, Republic of); Kim, Sang Wook [Dongguk University, Gyeongju (Korea, Republic of)

2016-05-15

{sup 99} Mo is extracted from the filtrate solution through column-based multistep separation and purification process. In the process, removal of radio-impurities from the solution is essential to acquire high-quality fission {sup 99} Mo. Iodine is the main impurity having about 15% of total radioactivity among the whole fission products. Most of the iodine exists in the caustic dissolution as iodide form. In this study, silver-exchanged adsorbent is used to adsorb iodide from the solution. Adsorbed iodide can be recovered and recycled for radiopharmaceuticals. Compound is dried again. After heating ascorbic acid solution, solution is added to dried compound. Heat the mixture. After removing supernatant, the mixture is washed with hot distilled water and then cool distilled water in the order named. Finally, the mixture is heated and then recovering by using the sieve. In this study, silver-exchanged adsorbent is used to adsorb iodide from the solution. Adsorbed iodide can be recovered and recycled for radiopharmaceuticals. Silver-doped DAW-70 alumina by using silver mirror reaction is less impurities and simpler than method using ascorbic acid.

CO2 laser direct writing of silver lines on epoxy resin from solid film

International Nuclear Information System (INIS)

Liu, J.G.; Chen, C.H.; Zheng, J.S.; Huang, J.Y.

2005-01-01

A technique of CO 2 laser direct writing from solid film was proposed in this paper. Patterns of silver lines were locally deposited on the non-conductive substrate using a preset layer of silver compound solid film, which was irradiated by focused CO 2 laser beam. The deposits were analyzed by XPS and EPMA. Results showed that metallic silver was dominant with an even distribution on the surface of the substrate, and part of the deposited silver had diffused into the substrate interior. The deposits had catalytic activity for the further electroless copper plating and had strong adhesion to the substrate. At last, the deposition mechanism and the dependence of the width of silver lines on the laser power and scan speed were roughly explored

Tapping the unexploited plant resources for the synthesis of silver ...

African Journals Online (AJOL)

STORAGESEVER

2008-09-03

Sep 3, 2008 ... Electron Microscopy). ... tinct property of nanoparticles is that they exhibit larger ... including the plant source, the organic compounds in the ... The XRD Image of silver nanoparticles synthesised using Sunflower leaf extract.

Silver Cation Coordination Study to AsW9 Ligand – A Trilacunar Arsenotungstate Compound

Directory of Open Access Journals (Sweden)

Berta Lavinia

2017-06-01

Full Text Available Objective: The main objective of this research is to find the coordination ratio between AsW9 and Ag+, as a preliminary study for synthesizing a new silver-arsenotungstate complex. Material and method: The ligand:cation molar ratio in complexes was determined by conductometric and potentiometric titrations of AsW9 with silver salts: CH3COOAg, AgNO3. Results: The ratio was obtained from the inflexion points of the curves when molar ratio was plotted versus conductivity, or from the equivalence point when silver added volume was plotted versus pH value. Each graphic shows one point of inflexion corresponding to 1:1.54 ratio of AsW9:Ag+. In the same manner, the equivalent volumes determined by graphical method gave the ratio 1:1.53. The spectral results confirmed that a AsW9:Ag+ complex was formed since the ligand absorption maxima values have been changed from 190 nm to 197 nm in the case of using AgNO3 and 196 nm for CH3COOAg corresponding to the W=Od bond, and from 246.5 nm to 274 nm (AgNO3 and 270 nm (CH3COO-Ag+ for the W-Ob,c-W bond. Conclusions: Silver cation exhibit a preference for AsW9 in a ratio of 3 to 2. This ratio can be associated to a sandwich type arrangement, with two trilacunary Keggin building blocks incorporating 3 metal cations in a tetrahedral geometry.

Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage

Science.gov (United States)

Raja, K.; Saravanakumar, A.; Vijayakumar, R.

2012-11-01

In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.

Influences of impurities on iodine removal efficiency of silver alumina adsorbent

Energy Technology Data Exchange (ETDEWEB)

Fukasawa, Tetsuo; Funabashi, Kiyomi [Hitachi, Ltd., Ibaraki (Japan); Kondo, Yoshikazu [Hitachi, Ltd., Ibaraki (Japan)

1997-08-01

Silver impregnated alumina adsorbent (AgA), which was developed for iodine removal from off-gas of nuclear power and reprocessing plants has been tested laying emphasis on investigation of the influences gaseous impurities have on adsorbent chemical stability and iodine removal efficiency. The influences of the major impurities such as nitrogen oxides and water vapor were checked on the chemical state of impregnated silver compound (AgNO{sub 3}) and decontamination factor (DF) value. At 150{degrees}C, a forced air flow with 1.5% nitrogen oxide (NO/NO{sub 2}=1/1) reduced silver nitrate to metallic silver, whereas pure air and air with 1.5% NO{sub 2} had no effect on the chemical state of silver. Metallic silver showed a lower DF value for methyl iodide in pure air (without impurities) than silver nitrate and the lower DF of metallic silver was improved when impurities were added. At 40{degrees}C, a forced air flow with 1.5% nitrogen dioxide (NO{sub 2}) increased the AgA weight by about 20%, which was caused by the adsorption of nitric acid solution on the AgA surface. AgA with l0wt% silver showed higher weight increase than that with 24wt% silver which had lower porosity. Adsorption of acid solution lowered the DF value, which would be due to the hindrance of contact between methyl iodide and silver. The influences of other gaseous impurities were also investigated and AgA showed superior characteristics at high temperatures. 14 refs., 11 figs.

Crystallic silver amalgam--a novel electrode material.

Science.gov (United States)

Danhel, Ales; Mansfeldova, Vera; Janda, Pavel; Vyskocil, Vlastimil; Barek, Jiri

2011-09-21

A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l(-1) of 4-nitrophenol at CAgAEs in 0.2 mol l(-1) acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1-100 μmol l(-1) with a limit of quantification of 1.5 μmol l(-1). The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.

Preconcentration of silver as silver xanthate on activated carbon

International Nuclear Information System (INIS)

Ramadevi, P.; Naidu, U.V.; Naidu, G.R.K.

1988-01-01

Silver from aqueous solution was preconcentrated by adsorption on activated carbon as silver xanthate. Factors influencing the adsorption of silver were studied. Optimum conditions for the preconcentration of silver were established. (author) 9 refs.; 3 tabs

catena-Poly[[tetrakis(hexamethylphosphoramide-κObis(nitrato-κ2O,O′lanthanum(III] [silver(I-di-μ2-sulfido-tungstate(VI-di-μ2-sulfido

Directory of Open Access Journals (Sweden)

Lude Lu

2008-02-01

Full Text Available Hexamethylphosphoramide (hmp, tetrathiotungstate(VI, silver sulfide and lanthanum(III nitrate are self-assembled to form discrete cations one-dimensional poylmeric anionic chains [AgWS4]nn− in the title compound, {[La(NO32(C6H18N3OP4][AgWS4]}n. The central La atom in the cation is coordinated by eight O atoms from two nitrate and four hmp ligands. Together with the two nitrate ligands, the cation is monovalent, which leads to the anionic chain having a monovalent repeat unit. The polymeric anionic chain with W...Ag...W and Ag...W...Ag angles of 165.94 (3 and 155.894 (14° presents a distorted linear configuration. Five N atoms, 18 C atoms and their attached H atoms are disordered equally over two positions.

Antibacterial effect of PEO coating with silver on AA7075

Energy Technology Data Exchange (ETDEWEB)

Cerchier, P., E-mail: pietrogiovanni.cerchier@studenti.unipd.it [Department of Industrial Engineering, University of Padua, Via Marzolo 9, 35131 Padova (Italy); Pezzato, L.; Brunelli, K. [Department of Industrial Engineering, University of Padua, Via Marzolo 9, 35131 Padova (Italy); Dolcet, P. [Department of Chemical Science, University of Padua, INSTM, UdR Padova and ICMATE-CNR, Padova (Italy); Bartolozzi, A.; Bertani, R.; Dabalà, M. [Department of Industrial Engineering, University of Padua, Via Marzolo 9, 35131 Padova (Italy)

2017-06-01

In this work, plasma electrolytic oxidation (PEO) coatings were produced on AA7075 using alkaline solution containing silicates compounds and silver micrometric particles in order to give to the coating an antimicrobial effect. In the optic of circular economy, silver chloride derived from the acid pre-treatment of electronic scraps was used as raw material and successively silver powders were synthesized from silver chloride solution using glucose syrup as reducing agent. The coatings were characterized by scanning electron microscope (SEM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and antimicrobial tests. The results evidenced that the obtained coatings were homogenous and give to the samples higher corrosion resistance than untreated alloy. The silver particles, found both inside and outside of the pores that characterize the PEO layer, produced an efficacious antimicrobial effect both against E. coli and S. aureus. - Highlights: • Silver particles were incorporated into PEO coatings produced on aluminum alloys. • The incorporation was performed with direct addition of the particles in the electrolyte. • The particles resulted equally distributed on the samples surfaces. • The obtained coatings show antimicrobial activity with both E. coli and S. aureus. • The obtained coatings were characterized by acceptable corrosion resistance.

Antibacterial effect of PEO coating with silver on AA7075

International Nuclear Information System (INIS)

Cerchier, P.; Pezzato, L.; Brunelli, K.; Dolcet, P.; Bartolozzi, A.; Bertani, R.; Dabalà, M.

2017-01-01

In this work, plasma electrolytic oxidation (PEO) coatings were produced on AA7075 using alkaline solution containing silicates compounds and silver micrometric particles in order to give to the coating an antimicrobial effect. In the optic of circular economy, silver chloride derived from the acid pre-treatment of electronic scraps was used as raw material and successively silver powders were synthesized from silver chloride solution using glucose syrup as reducing agent. The coatings were characterized by scanning electron microscope (SEM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and antimicrobial tests. The results evidenced that the obtained coatings were homogenous and give to the samples higher corrosion resistance than untreated alloy. The silver particles, found both inside and outside of the pores that characterize the PEO layer, produced an efficacious antimicrobial effect both against E. coli and S. aureus. - Highlights: • Silver particles were incorporated into PEO coatings produced on aluminum alloys. • The incorporation was performed with direct addition of the particles in the electrolyte. • The particles resulted equally distributed on the samples surfaces. • The obtained coatings show antimicrobial activity with both E. coli and S. aureus. • The obtained coatings were characterized by acceptable corrosion resistance.

Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage.

Science.gov (United States)

Raja, K; Saravanakumar, A; Vijayakumar, R

2012-11-01

In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods. Copyright © 2012 Elsevier B.V. All rights reserved.

Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

International Nuclear Information System (INIS)

Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R; Kolar, M

2011-01-01

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.

Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

Energy Technology Data Exchange (ETDEWEB)

Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17. Listopadu 12, 77146 Olomouc (Czech Republic); Kolar, M, E-mail: ales.panacek@upol.cz [Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 77520 Olomouc (Czech Republic)

2011-07-06

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.

and Silver(I) Complexes of Hydrazine-Bridged Diphosphine Ligands

African Journals Online (AJOL)

NICO

Gold(I), silver(I), hydrazine, diphosphine, antitumour, anticancer, mitochondrial membrane potential. 1. Introduction. The use of inorganic compounds as cancer treatment became well established with the FDA approval of cisplatin in 1978.1. Cisplatin, carboplatin and oxaliplatin are widely used in clinical settings today.

Morphological study of silver corrosion in highly aggressive sulfur environments

DEFF Research Database (Denmark)

Minzari, Daniel; Jellesen, Morten Stendahl; Møller, Per

2011-01-01

A silicone coated power module, having silver conducting lines, showed severe corrosion, after prolonged use as part of an electronic device in a pig farm environment, where sulfur containing corrosive gasses are known to exist in high amounts. Permeation of sulfur gasses and humidity through...... the silicone coating to the interface has resulted in three corrosion types namely: uniform corrosion, conductive anodic filament type of Ag2S growth, and silver migration with subsequent formation of sulfur compounds. Detailed morphological investigation of new and corroded power modules was carried out...

Green Synthesis of Silver Nanoparticles from several NTFP Plants

Directory of Open Access Journals (Sweden)

Somnath BHOWMIK

2016-03-01

Full Text Available The biological synthesis of nanoparticles using plant extracts plays an important role in the field of nanotechnology. In this study, rapid, simple approach was applied for synthesis of silver nanoparticles using , Clerodendrum infortunatum, Mucuna interrupta, Phlogancanthus thyrsiflorus and Sansevieria trifasciata aqueous leaf extract. The plant extract acts both as reducing agent as well as capping agent. To identify the compounds responsible for reduction of silver ions, the functional groups present in plant extract were investigated by FTIR. Various techniques used to characterize synthesized nanoparticles are Scanning Electron Microscopy (SEM, Atomic Force Microscopy (AFM and UV–Visible spectrophotometer. Results confirmed that this protocol was simple, rapid, one step, eco-friendly, non-toxic and might be an alternative conventional physical/chemical methods. Conversion of silver nanoparticles takes place at room temperature without the involvement of any hazardous chemicals.

Biosynthesis of silver nanoparticles using leaves of Stevia rebaudiana

International Nuclear Information System (INIS)

Yilmaz, M.; Turkdemir, H.; Kilic, M. Akif; Bayram, E.; Cicek, A.; Mete, A.; Ulug, B.

2011-01-01

Highlights: → Green synthesis of silver nanoparticles using leaves of Stevia Rebaudiana. → Spherical and polydispersed nanoparticles with diameters below 50 nm. → Interplay of nanoparticle formation and aggregation over time. → Capping reagents similar to those in gold synthesis via the same biomass. → Ketones to play active roles in the reduction of silver ions. - Abstract: The synthesis of silver nanoparticles employing a shadow-dried Stevia rebaudiana leaf extract in AgNO 3 solution is reported. Transmission electron microscopy and X-ray diffraction inspections indicate that nanoparticles are spherical and polydispersed with diameters ranging between 2 and 50 nm with a maximum at 15 nm. Ultraviolet-visible spectra recorded against the reaction time confirms the reduction of silver nanoparticles indicating that the formation and the aggregation of nanoparticles take place shortly after the mixing, as they persist concurrently with characteristic times of 48.5 min and 454.5 min, respectively. Aggregation is found to be the dominant mechanism after the first 73 min. Proton nuclear magnetic resonance spectrum of the silver nanoparticles reveals the existence of aliphatic, alcoholic and olefinic CH 2 and CH 3 groups, as well as some aromatic compounds but no sign of aldehydes or carboxylic acids. Infrared absorption of the silver nanoparticles suggests that the capping reagents of silver and gold nanoparticles reduced in plant extracts/broths are of the same chemical composition of different ratios. Ketones are shown to play a somehow active role for the formation of nanoparticles in plant extracts/broths.

Biosynthesis of silver nanoparticles using leaves of Stevia rebaudiana

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, M. [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Bartin University, Bartin (Turkey); Turkdemir, H. [Department of Chemistry, Faculty of Arts and Sciences, Uludag University, 16059 Goeruekle, Bursa (Turkey); Kilic, M. Akif [Department of Biology, Faculty of Science, Akdeniz University, Campus 07058, Antalya (Turkey); Bayram, E. [Department of Chemistry, Faculty of Science, Akdeniz University, Campus 07058, Antalya (Turkey); Cicek, A. [Department of Physics, Faculty of Arts and Sciences, Mehmet Akif Ersoy University, 15100 Burdur (Turkey); Department of Physics, Faculty of Science, Akdeniz University, Campus 07058, Antalya (Turkey); Mete, A. [Department of Chemistry, Faculty of Arts and Sciences, Inonu University, Malatya (Turkey); Ulug, B., E-mail: bulug@akdeniz.edu.tr [Department of Physics, Faculty of Science, Akdeniz University, Campus 07058, Antalya (Turkey)

2011-11-01

Highlights: {yields} Green synthesis of silver nanoparticles using leaves of Stevia Rebaudiana. {yields} Spherical and polydispersed nanoparticles with diameters below 50 nm. {yields} Interplay of nanoparticle formation and aggregation over time. {yields} Capping reagents similar to those in gold synthesis via the same biomass. {yields} Ketones to play active roles in the reduction of silver ions. - Abstract: The synthesis of silver nanoparticles employing a shadow-dried Stevia rebaudiana leaf extract in AgNO{sub 3} solution is reported. Transmission electron microscopy and X-ray diffraction inspections indicate that nanoparticles are spherical and polydispersed with diameters ranging between 2 and 50 nm with a maximum at 15 nm. Ultraviolet-visible spectra recorded against the reaction time confirms the reduction of silver nanoparticles indicating that the formation and the aggregation of nanoparticles take place shortly after the mixing, as they persist concurrently with characteristic times of 48.5 min and 454.5 min, respectively. Aggregation is found to be the dominant mechanism after the first 73 min. Proton nuclear magnetic resonance spectrum of the silver nanoparticles reveals the existence of aliphatic, alcoholic and olefinic CH{sub 2} and CH{sub 3} groups, as well as some aromatic compounds but no sign of aldehydes or carboxylic acids. Infrared absorption of the silver nanoparticles suggests that the capping reagents of silver and gold nanoparticles reduced in plant extracts/broths are of the same chemical composition of different ratios. Ketones are shown to play a somehow active role for the formation of nanoparticles in plant extracts/broths.

Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review.

Science.gov (United States)

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.

Synthesis of silver/silver chloride/graphene oxide composite and its surface-enhanced Raman scattering activity and self-cleaning property

Science.gov (United States)

Zhao, Nan; Fei, Xiao; Cheng, Xiaonong; Yang, Juan

2017-09-01

Recently, silver nanoparticles decorated with graphene and graphene oxide (GO) sheets can be employed as surface-enhanced Raman scattering (SERS) substrates. However, their SERS activity on macromolecular compound detection is all one-time process. In order to solve this issue and decrease the cost of routine SERS detection, silver/silver chloride (Ag/AgCl) with photocatalytic activity under visible light was introduced. In this study, a novel, simple and clean approach is carried out for synthesis of the Ag/AgCl/GO composite. The Ag/AgCl colloidal solution is obtained by hydrothermal method and then mixed with GO solution to obtain the Ag/AgCl/GO composite using a facile electrostatic self-assembly method. Results showed that the Ag/AgCl/GO composite has the optimized SERS activity to Rhodamine 6G molecules with the maximum enhancement factor value of 3.8×107. Furthermore, the Ag/AgCl particles with high efficient and stable photocatalytic activity under visible light lead to an outstanding self-cleaning property of the Ag/AgCl/GO composite.

Oral toxicity of silver ions, silver nanoparticles and colloidal silver – a review

DEFF Research Database (Denmark)

Hadrup, Niels; Lam, Henrik Rye

2014-01-01

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...

Silver nanoparticles and silver nitrate induce high toxicity to Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio

International Nuclear Information System (INIS)

Ribeiro, Fabianne; Gallego-Urrea, Julián Alberto; Jurkschat, Kerstin; Crossley, Alison; Hassellöv, Martin; Taylor, Cameron; Soares, Amadeu M.V.M.; Loureiro, Susana

2014-01-01

Silver nanoparticles (AgNP) have gained attention over the years due to the antimicrobial function of silver, which has been exploited industrially to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products will lead to the entry of silver compounds into the environment. In this study we have used Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio as model organisms to investigate the toxicity of AgNP and AgNO 3 by assessing different biological endpoints and exposure periods. Organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. AgNP were characterized in each test-media by Transmission Electron Microscopy (TEM) and experiments were performed by Dynamic Light Scattering (DLS) to investigate the aggregation and agglomeration behavior of AgNP under different media chemical composition and test-period. TEM images of AgNP in the different test-media showed dissimilar patterns of agglomeration, with some agglomerates inside an organic layer, some loosely associated particles and also the presence of some individual particles. The toxicity of both AgNO 3 and AgNP differ significantly based on the test species: we found no differences in toxicity for algae, a small difference for zebrafish and a major difference in toxicity for Daphnia magna. - Highlights: •Effects of silver nanoparticles and nitrate were compared in three aquatic species. •The presence of food on the immobilization assay for Daphnia magna significantly decreased AgNP toxicity. •AgNP and AgNO 3 differ in toxicity according to the test species and endpoint. •AgNP and AgNO 3 induced dissimilar abnormalities on zebrafish embryos' development. •AgNP behavior in the test media will rule its bioavailability and uptake and therefore toxicity

Silver nanoparticles and silver nitrate induce high toxicity to Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Fabianne, E-mail: ribeiro.f@ua.pt [Department of Biology and CESAM, University of Aveiro. Campus Universitario de Santiago, 3810-193. Aveiro (Portugal); Gallego-Urrea, Julián Alberto [Department of Chemistry and Molecular Biologyx, University of Gothenburg, Kemivägen 4, 41296 Gothenburg (Sweden); Jurkschat, Kerstin; Crossley, Alison [Department of Materials, Oxford University Begbroke Science Park OX5 1PF (United Kingdom); Hassellöv, Martin [Department of Chemistry and Molecular Biologyx, University of Gothenburg, Kemivägen 4, 41296 Gothenburg (Sweden); Taylor, Cameron [Department of Materials, Oxford University Begbroke Science Park OX5 1PF (United Kingdom); Soares, Amadeu M.V.M.; Loureiro, Susana [Department of Biology and CESAM, University of Aveiro. Campus Universitario de Santiago, 3810-193. Aveiro (Portugal)

2014-01-01

Silver nanoparticles (AgNP) have gained attention over the years due to the antimicrobial function of silver, which has been exploited industrially to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products will lead to the entry of silver compounds into the environment. In this study we have used Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio as model organisms to investigate the toxicity of AgNP and AgNO{sub 3} by assessing different biological endpoints and exposure periods. Organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. AgNP were characterized in each test-media by Transmission Electron Microscopy (TEM) and experiments were performed by Dynamic Light Scattering (DLS) to investigate the aggregation and agglomeration behavior of AgNP under different media chemical composition and test-period. TEM images of AgNP in the different test-media showed dissimilar patterns of agglomeration, with some agglomerates inside an organic layer, some loosely associated particles and also the presence of some individual particles. The toxicity of both AgNO{sub 3} and AgNP differ significantly based on the test species: we found no differences in toxicity for algae, a small difference for zebrafish and a major difference in toxicity for Daphnia magna. - Highlights: •Effects of silver nanoparticles and nitrate were compared in three aquatic species. •The presence of food on the immobilization assay for Daphnia magna significantly decreased AgNP toxicity. •AgNP and AgNO{sub 3} differ in toxicity according to the test species and endpoint. •AgNP and AgNO{sub 3} induced dissimilar abnormalities on zebrafish embryos' development. •AgNP behavior in the test media will rule its bioavailability and uptake and therefore toxicity.

Nanosilver against fungi. Silver nanoparticles as an effective biocidal factor.

Science.gov (United States)

Pulit, Jolanta; Banach, Marcin; Szczygłowska, Renata; Bryk, Mirosław

2013-01-01

The work presents a method of obtaining an aqueous raspberry extract as well as its physicochemical and analytical characteristics. The paper also contains a description of the method of preparation of nanosilver suspensions based on this extract. The raspberry extract served as a source of phenolic compounds which acted as both reducing and stabilizing agents. Suspensions of silver nanoparticles were obtained with the use of chemical reduction method. The silver ions concentration, pH value and temperature of samples incubation were independent variables. The next step of the research was to measure the antifungal activity of the received silver nanoparticles as well as to perform a mycological efficacy resistance analysis of the tested preparations in relation to different concentrations of nanostructured silver. Tests were conducted in compliance with the Eucast guidelines. The results of microbiological study of (the samples') biocidal effect against Cladosporium cladosporoides and Aspergillus niger are described. It was found that using nanosilver suspension at the concentration of 50 ppm inhibited the growth of Cladosporium cladosporoides and Aspergillus niger by 90% and 70%, respectively.

Biosynthesis of silver nanoparticles using bark extracts of Butea monosperma (Lam.) Taub. and study of their antimicrobial activity

Science.gov (United States)

Das, Manoja; Smita, Soumya Shuvra

2018-03-01

Biosynthesis of silver nanoparticles was achieved using bark extract of Butea monosperma (Lam.) Taub., a native plant of Indian subcontinent and southeast Asia. The plant parts are familiar for ailment of different diseases. The bioactive compounds present in bark of the plant were extracted with Soxhlet extractor. Silver nitrate (AgNO3) was used as a raw material for preparation of silver nanoparticles (AgNPs). The ratio of bark extract and silver nitrate solution for synthesis of AgNPs was standardized as 3:5. The change in colour of the solution from pale yellow to deep brown can be correlated to reduction reaction catalyzed by plant bioactive compounds. The formation of AgNPs was confirmed by UV-Vis spectrophotometer. The surface plasmon resonance (SPR) maxima, λmax, were recorded at 452 nm. SPR indicates the nature and type of particles present in the solution. The suitable concentration of AgNO3 was found to be 10 mM to carry out reduction reaction with the bark extract. Alkaline environment (pH 9) suitably promotes the reaction. FTIR graph of synthesized AgNPs shows the shifting peak of 3265.0 wavelength/cm and 1635.40 wavelength/cm indicates that AgNPs were coated with plant biomolecules, which is attributed to the stabilization of AgNPs. XRD and SEM photograph of the AgNPs showed that they were spherical in shape and capped with bioactive compounds. Thus, the synthesized AgNPs are more stable, less toxic and homogenous in shape. The average diameter of the nanoparticles was 81 nm. The synthesized AgNPs had efficacy against a Gram-negative bacteria (Escherichia coli), a Gram-positive bacteria (Staphylococcus aureus), and a mold (Aspergillus niger). The maximum conversion was 66%. From the present investigation, it can be concluded that the bioactive compounds present in the bark of Butea have the capacity to reduce silver ion into silver nanoparticles in aqueous condition and the synthesized AgNPs are stabilized and loss toxic. Moreover, they also possess

Silver(I) complexes of 2,4-dihydroxybenzaldehyde-amino acid Schiff bases-Novel noncompetitive α-glucosidase inhibitors.

Science.gov (United States)

Zheng, Jingwei; Ma, Lin

2015-01-01

A series of silver(I) complexes of 2,4-dihydroxybenzaldehyde-amino acid Schiff bases were designed and tested for α-glucosidase inhibition. Our results indicate that all the silver complexes (4a-18a) possessed strong inhibitory activity at μmolL(-1) level, especially glutamine (12a) and histidine (18a) Schiff base silver(I) complexes exhibited an IC50 value of less than 0.01μmolL(-1). This series of compounds exhibited noncompetitive inhibition characteristics in kinetic studies. In addition, we investigated the mechanism of inhibition and the structure-activity relationships of the amino acid Schiff base silver complexes. Our results reveal that Schiff base silver complexes may be explored for their therapeutic potential as alternatives of α-glucosidase inhibitors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multifaceted adsorption of α-cyano-4-hydroxycinnamic acid on silver colloidal and island surfaces

Science.gov (United States)

Jung, Dawoon; Jeon, Kooknam; Yeo, Juhyun; Hussain, Shafqat; Pang, Yoonsoo

2017-12-01

The surface adsorption of organic nitrile compounds on the silver colloidal and island surfaces has been studied using surface-enhanced Raman scattering (SERS). α-Cyano-4-hydroxycinnamic acid (CHCA) with nitrile and carboxyl groups shows various surface adsorption on the silver surfaces. In acidic conditions, the surface adsorption of CHCA via the nitrile group with a more or less tilted geometry to the surface was found. When the solution pH increases, the carboxylate and nitrile groups of deprotonated CHCA participate in the surface adsorption, whereas the molecular plane of CHCA becomes more parallel to the surface. The ν(Ctbnd N) band in SERS of CHCA is the indicator of the surface adsorption geometry. The strongly red-shifted and broadened ν(Ctbnd N) band in SERS represents the surface adsorption via π-electrons of the Ctbnd N bond (side-on geometry; π-coordination). Nitriles adsorbed on the surface via the nonbonding electron pair of the nitrogen atom (end-on geometry; σ-coordination) often cause the blue-shifts and small band broadening in ν(Ctbnd N) in SERS. The surface adsorption geometry of organic nitriles based on many previous experimental results was further confirmed by the surface adsorption of CHCA on the silver island surfaces and dinitrile compounds on the silver colloidal surfaces.

Biosorption of silver cations onto Lactococcus lactis and Lactobacillus casei isolated from dairy products.

Directory of Open Access Journals (Sweden)

Maciej Milanowski

Full Text Available The current work deals with the phenomenon of silver cations uptake by two kinds of bacteria isolated from dairy products. The mechanism of sorption of silver cations by Lactococcus lactis and Lactobacillus casei bacteria was investigated. Inductively coupled plasma-mass spectrometry (ICP-MS was used for determination of silver concentration sorbed by bacteria. Analysis of charge distribution was conducted by diffraction light scattering method. Changes in the ultrastructure of Lactococcus lactis and Lactobacillus casei cells after treatment with silver cations were investigated using transmission electron microscopy observation. Molecular spectroscopy methods, namely Fourier transform-infrared spectroscopy (FT-IR and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS were employed for description of the sorption mechanism. Moreover, an analysis of volatile organic compounds (VOCs extracted from bacterial cells was performed.

Synthesis and crystal structure of the cesium silver permanganate Cs_3Ag[MnO_4]_4

International Nuclear Information System (INIS)

Bauchert, Joerg M.; Henning, Harald; Schleid, Thomas

2012-01-01

After successful syntheses and structural refinements of the already known permanganates of cesium (Cs[MnO_4]) and silver (Ag[MnO_4]) we started to blend aqueous solutions of both components in various molar ratios. From crystallization experiments of these mixtures only three species of crystals with different chemical compositions were obtained: tricesium monosilver tetrakispermanganate (Cs_3Ag[MnO_4]_4) and, depending upon the respective ratio, either additional silver permanganate or surplus cesium permanganate, namely. The new title compound crystallizes in the orthorhombic space group Pnnm (no. 58) with two formula units per unit cell and cell dimensions of a = 764.53(4), b = 1883.57(9) and c = 584.34(3) pm. The crystal structure of Cs_3Ag[MnO_4]_4 consists of two crystallographically distinguishable cesium cations. (Cs1)"+ is surrounded by fourteen oxygen atoms constructing a slightly distorted bicapped hexagonal prism. These polyhedra are connected through edge-sharing with two other polyhedra of this kind to form chains along [001]. The chains are linked to each other via sixfold coordinated Ag"+ cations (d(Ag-O) = 238-246 pm), arranged in such a manner that they link three oxygen atoms of two cesium polyhedra, leading to a two-dimensional layer spreading out parallel to the (001) plane. Together with the two crystallographically different tetrahedral oxomanganate(VII) anions [MnO_4]"- (d(Mn-O) = 161-162 pm) the other kind of cesium cations ((Cs2)"+ with CN = 13) finally connect these layers three-dimensionally. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

Institute of Scientific and Technical Information of China (English)

Sirikamon Saengmee-anupharb; Toemsak Srikhirin; Boonyanit Thaweboon; Sroisiri Thaweboon; Taweechai Amornsakchai; Surachai Dechkunakorn; Theeralaksna Suddhasthira

2013-01-01

Objective: To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. Methods: The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candidaalbicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. Results: All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5-3.0 µm) and more uniformly shaped than AgZ. Conclusions: Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

Antimicrobial effects of silver zeolite,silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

Institute of Scientific and Technical Information of China (English)

Sirikamon; Saengmee-anupharb; Toemsak; Srikhirin; Boonyanit; Thaweboon; Sroisiri; Thaweboon; Taweechai; Amornsakchai; Surachai; Dechkunakorn; Theeralaksna; Suddhasthira

2013-01-01

Objective:To evaluate the antimicrobial activities of silver inorganic materials,including silver zeolite(AgZ),silver zirconium phosphate silicate(AgZrPSi)and silver zirconium phosphate(AgZrp),against oral microorganisms.In line with this objective,the morphology and structure of each type of silver based powders were also investigated.Methods:The antimicrobial activities of AgZ,AgZrPSi and AgZrP were tested against Streptococcus mutans,Lactobacillus casei,Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test.The minimum inhibitory concentration(MIC)and minimum lethal concentration(MLC)were determined using the modified membrane method.Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials.Results:All forms of silver inorganic materials could inhibit the growth of all test microorganisms.The MIC of AgZ,AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L.In terms of morphology and structure.AgZrPSi and AgZrP had smaller sized particles(1.5-3.0μm)and more uniformly shaped than AgZ.Conclusions:Silver inorganic materials in the form of AgZ,AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers.These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

Disinfection of Spacecraft Potable Water Systems by Passivation with Ionic Silver

Science.gov (United States)

Birmele, Michele N.; McCoy, LaShelle e.; Roberts, Michael S.

2011-01-01

Microbial growth is common on wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and physical disinfection methods. Advanced control technologies are needed to limit microorganisms and increase the reliability of life support systems required for long-duration human missions. Silver ions and compounds are widely used as antimicrobial agents for medical applications and continue to be used as a residual biocide in some spacecraft water systems. The National Aeronautics and Space Administration (NASA) has identified silver fluoride for use in the potable water system on the next generation spacecraft. Due to ionic interactions between silver fluoride in solution and wetted metallic surfaces, ionic silver is rapidly depleted from solution and loses its antimicrobial efficacy over time. This report describes research to prolong the antimicrobial efficacy of ionic silver by maintaining its solubility. Three types of metal coupons (lnconel 718, Stainless Steel 316, and Titanium 6AI-4V) used in spacecraft potable water systems were exposed to either a continuous flow of water amended with 0.4 mg/L ionic silver fluoride or to a static, pre-treatment passivation in 50 mg/L ionic silver fluoride with or without a surface oxidation pre-treatment. Coupons were then challenged in a high-shear, CDC bioreactor (BioSurface Technologies) by exposure to six bacteria previously isolated from spacecraft potable water systems. Continuous exposure to 0.4 mg/L ionic silver over the course of 24 hours during the flow phase resulted in a >7-log reduction. The residual effect of a 24-hour passivation treatment in 50 mg/L of ionic silver resulted in a >3-log reduction, whereas a two-week treatment resulted in a >4-log reduction. Results indicate that 0.4 mg/L ionic silver is an effective biocide against many bacteria and that a prepassivation of metal surfaces with silver can provide additional microbial control.

Argentation gas chromatography revisited: Separation of light olefin/paraffin mixtures using silver-based ionic liquid stationary phases.

Science.gov (United States)

Nan, He; Zhang, Cheng; Venkatesh, Amrit; Rossini, Aaron J; Anderson, Jared L

2017-11-10

Silver ion or argentation chromatography utilizes stationary phases containing silver ions for the separation of unsaturated compounds. In this study, a mixed-ligand silver-based ionic liquid (IL) was evaluated for the first time as a gas chromatographic (GC) stationary phase for the separation of light olefin/paraffin mixtures. The selectivity of the stationary phase toward olefins can be tuned by adjusting the ratio of silver ion and the mixed ligands. The maximum allowable operating temperature of these stationary phases was determined to be between 125°C and 150°C. Nuclear magnetic resonance (NMR) spectroscopy was used to characterize the coordination behavior of the silver-based IL as well as provide an understanding into the retention mechanism of light olefins. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of colloidal and dissolved silver in water samples using colorimetric solid-phase extraction.

Science.gov (United States)

Hill, April A; Lipert, Robert J; Porter, Marc D

2010-03-15

The increase in bacterial resistance to antibiotics has led to resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). However, growing concerns about the possible toxicity of colloidal silver to bacteria, aquatic organisms and humans have led to recently issued regulations by the US EPA and FDA regarding the usage of silver. As part of an ongoing project, we have developed a rapid, simple method for determining total silver, both ionic (silver(I)) and colloidal, in 0.1-1mg/L aqueous samples, which spans the ISS potable water target of 0.3-0.5mg/L (total silver) and meets the US EPA limit of 0.1mg/L in drinking water. The method is based on colorimetric solid-phase extraction (C-SPE) and involves the extraction of silver(I) from water samples by passage through a solid-phase membrane impregnated with the colorimetric reagent DMABR (5-[4-(dimethylamino)benzylidene]rhodanine). Silver(I) exhaustively reacts with impregnated DMABR to form a colored compound, which is quantified using a handheld diffuse reflectance spectrophotometer. Total silver is determined by first passing the sample through a cartridge containing Oxone, which exhaustively oxidizes colloidal silver to dissolved silver(I). The method, which takes less than 2 min to complete and requires only approximately 1 mL of sample, has been validated through a series of tests, including a comparison with the ICP-MS analysis of a water sample from ISS that contained both silver(I) and colloidal silver. Potential earth-bound applications are also briefly discussed. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Photocatalytic, antimicrobial activities of biogenic silver nanoparticles and electrochemical degradation of water soluble dyes at glassy carbon/silver modified past electrode using buffer solution.

Science.gov (United States)

Khan, Zia Ul Haq; Khan, Amjad; Shah, Afzal; Chen, Yongmei; Wan, Pingyu; Khan, Arif Ullah; Tahir, Kamran; Muhamma, Nawshad; Khan, Faheem Ullah; Shah, Hidayat Ullah

2016-03-01

In the present research work a novel, nontoxic and ecofriendly procedure was developed for the green synthesis of silver nano particle (AgNPs) using Caruluma edulis (C. edulis) extract act as reductant as well as stabilizer agents. The formation of AgNPs was confirmed by UV/Vis spectroscopy. The small and spherical sizes of AgNPs were conformed from high resolution transmission electron microscopy (HRTEM) analysis and were found in the range of 2-10nm, which were highly dispersion without any aggregation. The crystalline structure of AgNPs was conformed from X-ray diffraction (XRD) analysis. For the elemental composition EDX was used and FTIR helped to determine the type of organic compounds in the extract. The potential electrochemical property of modified silver electrode was also studied. The AgNPs showed prominent antibacterial motion with MIC values of 125 μg/mL against Bacillus subtilis and Staphylococcus aureus while 250 μg/mL against Escherichia coli. High cell constituents' release was exhibited by B. subtilis with 2 × MIC value of silver nanoparticles. Silver nanoparticles also showed significant DPPH free radical scavenging activity. This research would have an important implication for the synthesis of more efficient antimicrobial and antioxidant agent. The AgNP modified electrode (GC/AgNPs) exhibited an excellent electro-catalytic activity toward the redox reaction of phenolic compounds. The AgNPs were evaluated for electrochemical degradation of bromothymol blue (BTB) dyes which showed a significant activity. From the strong reductive properties it is obvious that AgNPs can be used in water sanitization and converting some organic perilous in to non-hazardous materials. The AgNPs showed potential applications in the field of electro chemistry, sensor, catalyst, nano-devices and medical. Copyright © 2016 Elsevier B.V. All rights reserved.

Leaching of Silver from Silver-Impregnated Food Storage Containers

Science.gov (United States)

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…

Silver niobates

International Nuclear Information System (INIS)

Tanirbergenov, B.; Rozhenko, S.P.

1979-01-01

By means of determination of residual concentrations and pH measurements investigated are the AgNO 3 -KNbO 3 -H 2 O, AgNO 3 -K 3 NbO 4 -H 2 O, AgNO 3 -K 8 Nb 16 O 19 -H 2 O systems and established is formation of meta-, ortho-and hexaniobates of silver. AgNbO 3 x H 2 O, Ag 8 Nb 6 O 19 x 6H 2 O and Ag 3 NbO 3 x 2.5H 2 O are separated from aqueous solution. Using the methods of differential-thermal, thermogravimetric and X-ray-phase analyses it is shown that silver metaniobate transforms into the crystal state at 530 deg C. Ortho- and hexaniobate of silver decompose at 500 deg C with formation of silver metaniobate and metal silver

Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction

International Nuclear Information System (INIS)

Shi, Yongzheng; Li, Yajing; Zhang, Jianfeng; Yu, Zhongzhen; Yang, Dongzhi

2015-01-01

The silver mirror reaction (SMR) method was selected in this paper to modify electrospun polyacrylonitrile (PAN) nanofibers, and these nanofibers loaded with silver nanoparticles showed excellent antibacterial properties. PAN nanofibers were first pretreated in AgNO 3 aqueous solution before the SMR process so that the silver nanoparticles were distributed evenly on the outer surface of the nanofibers. The final PAN nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), TEM-selected area electron diffraction (SAED), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). SEM, TEM micrographs and SAED patterns confirmed homogeneous dispersion of the silver nanoparticles which were composed of monocrystals with diameters 20–30 nm. EDS and XRD results showed that these monocrystals tended to form face-centered cubic single silver. TGA test indicated that the nanoparticles loaded on the nanofibers reached above 50 wt.%. This material was also evaluated by the viable cell-counting method. The results indicated that PAN nanofibers loaded with silver nanoparticles exhibited excellent antimicrobial activities against gram-negative Escherichia coli (E. coli), gram-positive Staphylococcus aureus (S. aureus) and the fungus Monilia albicans. Thus, this material had many potential applications in biomedical fields. - Highlights: • Silver mirror reaction was used to prepare nanofibers loaded with silver nanoparticles. • The SAED patterns demonstrated the monocrystallinity of silver nanocrystals. • The XRD results showed nanoparticles tended to be face-centered cubic single silver. • The material showed excellent antimicrobial activities against bacteria and fungi

Recovery of silver from waste photographic x-ray films

International Nuclear Information System (INIS)

Nartey, V.K.; Donkor, A.; Fianko, J.R.

2005-01-01

In this work, metallic silver has been recovered from disused X-ray films by leaching the silver (Ag) with 50% and 70% nitric acid(HNO 3 ) aqueous solutions. The films were collected from four hospitals in Accra. This method of retrieving Ag is more environmentally friendly compared with the current traditional technique employing dilute sulfuric acid (33%) by the indigenous population to win Ag. More so, the traditional method is characterized by the emission of toxic fuming gases (e.g. sulfur dioxide) and particulates (e.g. lead and arsenic compounds) during the refining of the Ag while reporting.Average yield of recovered Ag was 50.6% following the traditional method whereas 77.0% and 82.9% were obtained using 50% and 70% HNO 3 respectively. (au)

Synthesis, characterization and antimicrobial activities of novel silver(I) complexes with coumarin substituted N-heterocyclic carbene ligands.

Science.gov (United States)

Karataş, Mert Olgun; Olgundeniz, Begüm; Günal, Selami; Özdemir, İlknur; Alıcı, Bülent; Çetinkaya, Engin

2016-02-15

Eight new coumarin substituted silver(I) N-heterocyclic carbene (NHC) complexes were synthesized by the interaction of the corresponding imidazolium or benzimidazolium chlorides and Ag2O in dichloromethane at room temperature. Structures of these complexes were established on the basis of elemental analysis, (1)H NMR, (13)C NMR, IR and mass spectroscopic techniques. The antimicrobial activities of carbene precursors and silver NHC complexes were tested against standard strains: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungi Candida albicans and Candida tropicalis. Results showed that all the compounds inhibited the growth of the all bacteria and fungi strains and some complexes performed good activities against different microorganisms. Among all the compounds, the most lipophilic complex bis[1-(4-methylene-6,8-dimethyl-2H-chromen-2-one)-3-(naphthalene-2-ylmethyl)benzimidazol-2-ylidene]silver(I) dichloro argentate (5e) was found out as the most active one. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction

Energy Technology Data Exchange (ETDEWEB)

Shi, Yongzheng; Li, Yajing; Zhang, Jianfeng; Yu, Zhongzhen; Yang, Dongzhi, E-mail: yangdz@mail.buct.edu.cn

2015-06-01

The silver mirror reaction (SMR) method was selected in this paper to modify electrospun polyacrylonitrile (PAN) nanofibers, and these nanofibers loaded with silver nanoparticles showed excellent antibacterial properties. PAN nanofibers were first pretreated in AgNO{sub 3} aqueous solution before the SMR process so that the silver nanoparticles were distributed evenly on the outer surface of the nanofibers. The final PAN nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), TEM-selected area electron diffraction (SAED), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). SEM, TEM micrographs and SAED patterns confirmed homogeneous dispersion of the silver nanoparticles which were composed of monocrystals with diameters 20–30 nm. EDS and XRD results showed that these monocrystals tended to form face-centered cubic single silver. TGA test indicated that the nanoparticles loaded on the nanofibers reached above 50 wt.%. This material was also evaluated by the viable cell-counting method. The results indicated that PAN nanofibers loaded with silver nanoparticles exhibited excellent antimicrobial activities against gram-negative Escherichia coli (E. coli), gram-positive Staphylococcus aureus (S. aureus) and the fungus Monilia albicans. Thus, this material had many potential applications in biomedical fields. - Highlights: • Silver mirror reaction was used to prepare nanofibers loaded with silver nanoparticles. • The SAED patterns demonstrated the monocrystallinity of silver nanocrystals. • The XRD results showed nanoparticles tended to be face-centered cubic single silver. • The material showed excellent antimicrobial activities against bacteria and fungi.

Development and Optimization of Silver Nanoparticle Formulation for Fabrication

Science.gov (United States)

2015-08-14

steady increase in multi - drug resistant organisms. Therefore , the development of next generation antimicrobial compounds , such as silver...information. Publication Clearance Request (CPP- 1) Version 9.3: 10.2014 D Animal Use Research Protocol No.: List the IACUC that approved the...nanoparticles, is a priority. However , due to the inconsistencies in current fabrication and processing methods , it is unclear whether the antimicrobial

Development kinetics of silver clusters on silver halides

International Nuclear Information System (INIS)

Grzesiak, S.; Belloni, J.; Marignier, J.-L.

2008-01-01

Silver nuclei are produced by pulse radiolysis at the surface of AgCl nanocrystallites in the presence of an electron donor, the methyl viologen, which induces the growth of silver nuclei. The experimental results observed on the increase of the silver atom concentration and on the decay of the donor concentration during this process, which is similar to the photographic development by an electron donor, are compared with the kinetics obtained from numerical simulation. The model assumes that the formation of silver clusters with a supercritical nuclearity is required before the start of an electron transfer reaction from the two reduced forms of the donor methyl viologen to the silver clusters. The reaction is controlled by the access of the donor to the surface sites of the AgCl crystallite. The rate constant values of the successive steps of the mechanism are derived from the adjustment of calculated kinetics to experimental signals under various conditions, using a single set of parameters which are fairly suitable under all conditions studied

XPS and Ag L3-edge XANES characterization of silver and silver-gold sulfoselenides

Science.gov (United States)

Mikhlin, Yuri L.; Pal'yanova, Galina A.; Tomashevich, Yevgeny V.; Vishnyakova, Elena A.; Vorobyev, Sergey A.; Kokh, Konstantin A.

2018-05-01

Gold and silver sulfoselenides are of interest as materials with high ionic conductivity and promising magnetoresistive, thermoelectric, optical, and other physico-chemical properties, which are strongly dependent on composition and structure. Here, we applied X-ray photoelectron spectroscopy and Ag L3 X-ray absorption near-edge structure (XANES) to study the electronic structures of low-temperature compounds and solid solutions Ag2SxSe1-x (0 compounds; in particular, the Ag L3-edge peak is about 35% lower for AgAuS relative to Ag2S. At the same time, the Au 4f binding energy and, therefore, charge at Au(I) sites increase with increasing S content due to the transfer of electron density from Au to Ag atoms. It was concluded that the effects mainly originate from shortening of the metal-chalcogen and especially the Ausbnd Ag interatomic distances in substances having similar coordination geometry.

Russell-Silver syndrome

Science.gov (United States)

Silver-Russell syndrome; Silver syndrome; RSS; Russell-Silver syndrome ... One in 10 children with this syndrome has a problem involving chromosome 7. In other people with the syndrome, it may affect chromosome 11. Most of the time, it ...

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

DEFF Research Database (Denmark)

Löschner, Katrin; Hadrup, Niels; Qvortrup, Klaus

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 Ag...

Silver matrix composites reinforced with galvanically silvered particles

OpenAIRE

J. Śleziona; J. Wieczorek,

2007-01-01

Purpose: The paper presents the possibility of the application of metalic layers drifted with the use of the galvanic methods on the ceramic particles surface. The application of the layers was aimed at obtaining the rewetting of the reinforcing particles with the liquid silver in the course of the producing of silver matrix composites with the use of mechanical stirring method. To enable introducing of the iron powder and glass carbon powder to liquid silver the solution of covering the powd...

[Comet assay of DNA fragmentation: modification of silver staining for obtaining permanent preparations].

Science.gov (United States)

Kamins'kyĭ, V O; Lutsyk, M D; Stoĭka, R S

2005-01-01

Modification of comet analysis is proposed for obtaining permanent preparations by DNA staining with silver compounds. The sensitivity of staining is similar to that observed at the treatment by ethidium bromide and other fluorochromes. The advantages of the method are stability of slides and possibility of their reinvestigation by light microscopy. The method does not need expensive fluorescent microscope and lacks contacting with carcinogenic compounds and UV light irradiation.

Silver(I) complexes of N-methylbenzothiazole-2-thione: Synthesis, structures and antibacterial activity

Energy Technology Data Exchange (ETDEWEB)

Aslanidis, P., E-mail: aslanidi@chem.auth.gr [Laboratory of Inorganic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Hatzidimitriou, A.G.; Andreadou, E.G. [Laboratory of Inorganic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Pantazaki, A.A., E-mail: natasa@chem.auth.gr [Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Voulgarakis, N. [Department of Logistics, Alexander Technological Educational Institute, GR-60100 Katerini (Greece)

2015-05-01

Three silver(I) complexes containing N-methylbenzothiazole-2-thione (mbtt) have been prepared and structurally characterized by X-ray single-crystal analysis. Silver(I) nitrate, and silver(I) triflate react with mbtt to give homoleptic complexes of formula [(mbtt){sub 2}Ag(μ-mbtt){sub 2}Ag(mbtt){sub 2}](NO{sub 3}){sub 2} (1) and [Ag(mbtt){sub 3}](CF{sub 3}SO{sub 3}) (2) respectively, while silver(I) chloride gives the binuclear halide-bridged [(mbtt){sub 2}Ag(μ{sub 2}-Cl){sub 2}Ag(mbtt){sub 2}] (3). In the binuclear complex 1 the two metal ions, separated by 3.73 Å from each other, are doubly bridged by the exocyclic S-atoms of two mbtt ligands, with the tetrahedral environment around each silver ion being completed by the S-atoms of two terminally bonded mbtt units. Compound 2 is mononuclear with the metal ion surrounded by the exocyclic S-atoms of three mbtt ligands in a nearly ideal trigonal planar arrangement. The new complexes showed significant in vitro antibacterial activity against certain Gram-positive and Gram-negative bacterial strains.

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

Science.gov (United States)

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).

Biological synthesis of very small silver nanoparticles by culture supernatant of Klebsiella pneumonia: The effects of visible-light irradiation and the liquid mixing process

International Nuclear Information System (INIS)

Mokhtari, Narges; Daneshpajouh, Shahram; Seyedbagheri, Seyedali; Atashdehghan, Reza; Abdi, Khosro; Sarkar, Saeed; Minaian, Sara; Shahverdi, Hamid Reza; Shahverdi, Ahmad Reza

2009-01-01

This study has investigated different visible-light irradiation's effect on the formation of silver nanoparticles from silver nitrate using the culture supernatant of Klebsiella pneumonia. Our study shows that visible-light emission can significantly prompt the synthesis of silver nanoparticles. Also, the study experimentally investigated the liquid mixing process effect on silver nanoparticle synthesis by visible-light irradiation. This study successfully synthesized uniformly dispersed silver nanoparticles with a uniform size and shape in the range of 1-6 nm with an average size of 3 nm. Furthermore, the study investigated the mechanism of the reduction of silver ions by culture supernatant of K. pneumonia, and used X-ray diffraction to characterize silver chloride as an intermediate compound. Silver chloride was prepared synthetically and used as a substrate for the synthesis of silver nanoparticles by culture supernatant of K. pneumonia. The silver nanoparticles have been prepared from silver chloride during this investigation for the first time.

Biological synthesis of very small silver nanoparticles by culture supernatant of Klebsiella pneumonia: The effects of visible-light irradiation and the liquid mixing process

Energy Technology Data Exchange (ETDEWEB)

Mokhtari, Narges [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Daneshpajouh, Shahram; Seyedbagheri, Seyedali; Atashdehghan, Reza [Hydrometallurgy Research Unit, Research and Development Center, National Iranian Copper Industries Company, Sarcheshmeh, Rafsanjan (Iran, Islamic Republic of); Abdi, Khosro [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Sarkar, Saeed [Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Minaian, Sara [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shahverdi, Hamid Reza [Department of Material Science, Faculty of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shahverdi, Ahmad Reza, E-mail: shahverd@sina.tums.ac.ir [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2009-06-03

This study has investigated different visible-light irradiation's effect on the formation of silver nanoparticles from silver nitrate using the culture supernatant of Klebsiella pneumonia. Our study shows that visible-light emission can significantly prompt the synthesis of silver nanoparticles. Also, the study experimentally investigated the liquid mixing process effect on silver nanoparticle synthesis by visible-light irradiation. This study successfully synthesized uniformly dispersed silver nanoparticles with a uniform size and shape in the range of 1-6 nm with an average size of 3 nm. Furthermore, the study investigated the mechanism of the reduction of silver ions by culture supernatant of K. pneumonia, and used X-ray diffraction to characterize silver chloride as an intermediate compound. Silver chloride was prepared synthetically and used as a substrate for the synthesis of silver nanoparticles by culture supernatant of K. pneumonia. The silver nanoparticles have been prepared from silver chloride during this investigation for the first time.

Liquid-Mercury Free Silver Solid Amalgam Electrode - Tool for Electroanalysis of Organic Compounds

Czech Academy of Sciences Publication Activity Database

Šelešovská-Fadrná, R.; Navrátil, Tomáš; Vlček, Milan

2007-01-01

Roč. 52, č. 6 (2007), s. 911-929 ISSN 0009-2223 R&D Projects: GA ČR GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40500505 Keywords : ascorbic acid * solid silver amalgam electrodes * cysteine * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 0.529, year: 2007

Synthesis of silver nanoparticles using DL-alanine for ESR dosimetry applications

International Nuclear Information System (INIS)

Guidelli, Eder José; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D.; Nicolucci, Patricia; Baffa, Oswaldo

2012-01-01

The potential use of alanine for the production of nanoparticles is presented here for the first time. Silver nanoparticles were synthesized using a simple green method, namely the thermal treatment of silver nitrate aqueous solutions with DL-alanine. The latter compound was employed both as a reducing and a capping agent. Particles with average size equal to 7.5 nm, face-centered cubic crystalline structure, narrow size distribution, and spherical shape were obtained. Interaction between the silver ions present on the surface of the nanoparticles and the amine group of the DL-alanine molecule seems to be responsible for reduction of the silver ions and for the stability of the colloid. The bio-hybrid nano-composite was used as an ESR dosimeter. The amount of silver nanoparticles in the nanocomposite was not sufficient to cause considerable loss of tissue equivalency. Moreover, the samples containing nanoparticles presented increased sensitivity and reduced energetic dependence as compared with pure DL-alanine, contributing to the construction of small-sized dosimeters. - Highlights: ► The synthesis is environmentally benign, easy to perform, and of low-cost. ► DL-Alanine was employed both as reducing and capping agent. ► Mean size of 7.5 nm, narrow size distribution, and spherical shape of particles. ► Increased sensitivity and reduced energetic dependence compared with pure alanine. ► The nanocomposite has potential application for ESR dosimetry.

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

Science.gov (United States)

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.

EFFECTS OF SILVER NANOPARTICLES IN SOLUTION AND LIPOSOMAL FORM ON SOME BLOOD PARAMETERS IN FEMALE RABBITS DURING FERTILIZATION AND EARLY EMBRYONIC DEVELOPMENT

Directory of Open Access Journals (Sweden)

Vasyl Syrvatka

2014-02-01

Full Text Available Silver nanoparticles are the most rapidly growing classes of nanoproducts. In this study, we investigated the influence of subcutaneous injections of silver nanoparticles in solution and in liposomal form on hematological and biochemical parameters of blood of New Zealand White rabbits during hormonal treatment, fertilization and early embryonic development. The females treated by free silver nanoparticles and silver nanoparticles in liposomal form received silver at a dose of 10 µg/kg/day in 5 % glucose solution during 28 days. Blood sampling was done four times: the day before the compounds administration; on day 7 after the compounds administration; in the period after hormonal induction and fertilization and on the 14th day of pregnancy. Our results showed changes in some biochemical (lactate dehydrogenase activities, progesterone and estradiol concentration, malondialdehyde level, etc. and hematological (hematocrit, mean cell volume, mean corpuscular hemoglobin concentration, etc. parameters under the influence of hormonal treatment and pregnancy. The concentration of progesterone showed significantly higher values (P˂0.05 on GDs 1 in S group than in C group. The percentage of neutrophils was significantly higher in SG rabbits after 7 days of silver nanoparticles administration than that in the CG. There were no significant changes in red blood cells parameters, platelets, and activity of some ferments (ALP, AST, ALT, LDH, GGT between control and silver groups during the entire period of experiment. In conclusion, the hematological and biochemical values of blood obtained in the given study showed that free silver nanoparticles and silver nanoparticles in liposomal form in the investigated concentrations had no toxic effect on hormonal treatment, fertilization and early embryonic development in New Zealand White rabbits.

Structure and decomposition of the silver formate Ag(HCO2)

International Nuclear Information System (INIS)

Puzan, Anna N.; Baumer, Vyacheslav N.; Mateychenko, Pavel V.

2017-01-01

Crystal structure of the silver formate Ag(HCO 2 ) has been determined (orthorhombic, sp.gr. Pccn, a=7.1199(5), b=10.3737(4), c=6.4701(3)Å, V=477.88(4) Å 3 , Z=8). The structure contains isolated formate ions and the pairs Ag 2 2+ which form the layers in (001) planes (the shortest Ag–Ag distances is 2.919 in the pair and 3.421 and 3.716 Å between the nearest Ag atoms of adjacent pairs). Silver formate is unstable compound which decompose spontaneously vs time. Decomposition was studied using Rietveld analysis of the powder diffraction patterns. It was concluded that the diffusion of Ag atoms leads to the formation of plate-like metal particles as nuclei in the (100) planes which settle parallel to (001) planes of the silver formate matrix. - Highlights: • Silver formate Ag(HCO 2 ) was synthesized and characterized. • Layered packing of Ag-Ag pairs in the structure was found. • Decomposition of Ag(HCO 2 ) and formation of metal phase were studied. • Rietveld-refined micro-structural characteristics during decomposition reveal the space relationship between the matrix structure and forming Ag phase REPLACE with: Space relationship between the matrix structure and forming Ag phase.

Studies on the antifungal activities of the novel synthesized chelating co-polymer emulsion lattices and their silver complexes

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Abd-El-Ghaffar M.A.

2008-01-01

Full Text Available The novel binary chelating co-polymers of butyl acrylate with itaconic and maleic acids were prepared by emulsion polymerization process. The chelating co-polymers of butyl acrylate-co-itaconic acid (BuA/IA and butyl acrylate-co-maleic acid (BuA/MA and their silver complexes were characterized and identified using IR spectroscopy and differential scanning calorimetry (DSC measurements. The biological activities of these compounds were studied against various types of fungal species. The dose and the rate of leached silver ions were controlled by the type of the co-polymers used and the solubility in the medium. The results provided laboratory support for the concept that the polymers containing chemically bound biocide are useful for controlling microbial growth. The silver uptake by strains of different fungal species was studied to determine their difference in behavior to the antifungal activities of these compounds. The uptake strategy was examined by transmission electron microscopy (TEM.

Red tea leaves infusion as a reducing and stabilizing agent in silver nanoparticles synthesis

Science.gov (United States)

Pluta, K.; Tryba, A. M.; Malina, D.; Sobczak-Kupiec, A.

2017-12-01

Due to the unique properties of silver nanoparticles there is growing interest in their applications. Current trends in nanotechnology are focused on developing a new technique to synthesize nanoparticles using biological methods associated with the use of plant extracts, fungi, bacteria or essential oils. These methods are a promising alternative to conventional approaches which can minimize the use of hazardous substances. The silver nanoparticles synthesis using red tea infusion as a reducing and stabilizing agent and their characteristics have been described. Total antioxidant capacity using DPPH radical and total content of phenolic compounds by Folin-Ciocalteau method were measured in tea infusion. Synthesis of silver nanoparticles was carried out using chemical reduction at various temperatures. Furthermore, the effect of tea infusion volume added to reaction mixture on nanoparticles’ properties was investigated. Finally, nanosilver suspensions were characterized by UV-vis spectrophotometer, dynamic light scattering (DLS) scanning electron microscope (SEM) and transmission electron microscope (TEM). Moreover, phytotoxicity of silver nanoparticles was determined using Phytotestkit microbiotest.

Comparing the characteristics of highly cited titles and highly alted titles

Energy Technology Data Exchange (ETDEWEB)

Didegah, F.; Bowman, T.D.; Bowman, S.; Hartley, J.

2016-07-01

This study examines differences in the types of titles for articles that show high altmetric activity (highly alted articles) versus highly cited articles. This work expands on previous research on document titles in combination with a grounded theory approach to develop a codebook in which articles were manually coded based on 11 characteristics. The results show that there are differences and similarities in titles across many of the examined characteristics; highly cited titles and highly mentioned titles on Wikipedia have some similar characteristics such as they have the the highest percentage of substantive words; in addition, there are no or very few titles referencing outside or with humor/lightness on both platforms. Twitter and Facebook also showed some similarities having the highest percentage of humorous/light titles and lowest percentage of substantive words in their titles. (Author)

Measurement of the isotope effect of the diffusion of silver and gold in gold and of silver in silver-gold alloys

International Nuclear Information System (INIS)

Wolter, D.

1974-01-01

The silver isotopes Ag 105 and Agsup(110m) and the gold isotopes Au 195 and Au 199 were used for isotope effect measurements. The isotope effect of the gold self-diffusion was measured on four monocrystals samples at about 850 0 C, that of silver in gold monocrystals at five different temperatures between 731 0 C and 1050 0 C. Furthermore, the isotope effect for silver at 904 0 C was measured on seven silver-gold alloys of varying silver concentration. The correlation factor was determined from the measurements. (HPOE/LH) [de

Hepatoprotective effect of engineered silver nanoparticles coated bioactive compounds against diethylnitrosamine induced hepatocarcinogenesis in experimental mice.

Science.gov (United States)

Prasannaraj, Govindaraj; Venkatachalam, Perumal

2017-02-01

Nanoparticle based drug delivery can rapidly improves the therapeutic potential of anti-cancer agents. The present study focused to evaluate the hepatoprotective activity of silver nanoparticles (AgNPs) synthesized using aqueous extracts of Andrographis paniculata leaves (ApAgNPs) and Semecarpus anacardium nuts (SaAgNPs) against diethylnitrosamine (DEN) induced liver cancer in mice model. The physico-chemical properties of synthesized AgNPs were characterized by Fourier transform infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX) spectrum, Zeta potential and Dynamic Light Scattering (DLS) analysis. The surface plasmon resonance (SPR) absorption spectrum revealed a strong peak at 420nm for both SaAgNPs and ApAgNPs. FTIR results exhibited the presence of possible functional groups in the synthesized AgNPs. TEM analysis determined the hexagonal, and spherical shape of the synthesized silver nanoparticles. The XRD and SAED pattern confirmed the crystalline nature and crystalline size of the AgNPs. EDX result clearly showed strong silver signals in the range between 2 and 4keV. Zeta potential measurements indicated a sharp peak at -3.93 and -13.8mV for ApAgNPs and SaAgNPs, respectively. DLS measurement expressed the particle size distribution was 70 and 60nm for ApAgNPs and SaAgNPs, respectively. DEN (20mg/kg b.wt.) was subjected to induce liver cancer in mice for 8weeks and treated with biosynthesized silver nanoparticles. Interestingly, ApAgNPs and SaAgNPs treated DEN induced animal groups show a decreased level of aspartate amino transferase (AST), alanine amino transferase (ALT), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) activity and elevated level of catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) activity over untreated DEN control

Effect of silver thiosulphate preservative on the physiology of cut carnations

International Nuclear Information System (INIS)

Ducasse, P.B.; Van Staden, J.

1981-01-01

This investigation attempted to determine the effect of silver thiosulphate on the carbohydrate status of cut carnation flowers. Labelled [ 14 C] sucrose was applied by microsyringe to two of the outer petals of each flower. At fixed intervals flowers were withdrawn from the different solutions and separated into labelled petals, untreated petals, gynoecia, and shoots. Paper chromatographic techniques were used to determine whether any detected radioactivity was associated with sucrose or its breakdown products. The vase life of flowers was extended by silver thiosulphate treatment and decreased by Ethrel application. Ethrel application enhanced carbohydrate utilization and also accelerated transport of labelled compounds from the treated petals to the rest of the flower

Highly efficient silver patterning without photo-resist using simple silver precursors

International Nuclear Information System (INIS)

Byun, Younghun; Hwang, Eoc-Chae; Lee, Sang-Yun; Lyu, Yi-Yeol; Yim, Jin-Heong; Kim, Jin-Young; Chang, Seok; Pu, Lyong Sun; Kim, Ji Man

2005-01-01

Highly efficient method for silver patterning without photo-resist was developed by using high photosensitive organo-silver precursors, which were prepared by a simple reaction of silver salts and excess of amines. The FT-IR and GC-MS spectra were recorded depending on UV exposure time, for (n-PrNH 2 )Ag(NO 3 ).0.5MeCN and (n-PrNH 2 )Ag(NO 2 ).0.5MeCN, to understand the photolysis mechanism. The results indicate not only dissociation of coordinated amine and acetonitrile, but also decomposition of corresponding anion upon UV irradiation. When a precursor thin film was exposed to broadband UV irradiation, a partially reduced and insoluble silver species were formed within several minutes. After development, the irradiated areas were treated with a reducing agent to obtain pure metallic patterns. Subsequently, annealing step was followed at 100-350 deg. C to increase the adhesion of interface and cohesion of silver particles. The line resolution of 5 μm was obtained by the present silver precursors. Film thickness was also controllable from 50 to 250 nm by repetition of the above procedure. The average electrical conductivity was in the range of 3-43 Ω cm, measured by four-point probe technique. AES depth profile of the silver pattern thus obtained showed carbon and oxygen contents are less than 1% through the whole range. Even though sulfur contaminant exists on the surface, it was believed that nearly pure silver pattern was generated

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

Energy Technology Data Exchange (ETDEWEB)

Uznanski, Pawel, E-mail: puznansk@cbmm.lodz.pl; Zakrzewska, Joanna [Centre of Molecular and Macromolecular Studies, PAS (Poland); Favier, Frederic, E-mail: fredf@univ-montp2.fr [Université Montpellier II, ICGM - UMR5253- Equipe AIME (France); Kazmierski, Slawomir; Bryszewska, Ewa [Centre of Molecular and Macromolecular Studies, PAS (Poland)

2017-03-15

A comparative study of amine and silver carboxylate adducts [R{sub 1}COOAg-2(R{sub 2}NH{sub 2})] (R{sub 1} = 1, 7, 11; R{sub 2} = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, {sup 13}C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ({sup 1}H and {sup 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.

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

Science.gov (United States)

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.

Plectranthus amboinicus-mediated silver, gold, and silver-gold nanoparticles: phyto-synthetic, catalytic, and antibacterial studies

Science.gov (United States)

Purusottam Reddy, B.; Mallikarjuna, K.; Narasimha, G.; Park, Si-Hyun

2017-08-01

Bio-based green nanotechnology aims to characterize compounds from natural sources and establish efficient routes for the preparation of nontoxic materials that have applicability in biodegradable and biocompatible devices. The present study has investigated the use of Plectranthus amboinicus leaf extracts as reducing and capping materials for the green fabrication of silver, gold, and silver-gold (Ag, Au, and Ag/Au) metal and bimetallic nanoparticles. The catalytic behavior of these phyto-inspired nanoparticles was then assessed in terms of the reduction of 4-nitrophenol. Transmission electron microscopy was used to investigate the shape, morphology, distribution, and diameter of the phytomolecules capped with Ag, Au, and Ag/Au metal nanoparticles. The nature of the crystallinity of the nanoparticles was studied by small area electron diffraction (SAED) and x-ray diffraction analysis (XRD), and Fourier transform infrared (FTIR) spectroscopy was used to study the reduction and stabilizing involvement of the phyto-organic moieties in aqueous medium. The phyto-inspired Ag and Ag/Au nanoparticles demonstrated good antibacterial properties toward Gram-negative Escherichia coli and Pseudomonas spp. and Gram-positive Bacillus spp. and Staphylococcus spp. microorganisms using the well diffusion method. Notably, the Ag nanoparticles were shown to possess effective antibacterial properties.

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

Directory of Open Access Journals (Sweden)

Marcia E. Richard

2013-10-01

Full Text Available A range of arylgold compounds have been synthesized and investigated as single-component catalysts for the hydrophenoxylation of unactivated internal alkynes. Both carbene and phosphine-ligated compounds were screened as part of this work, and the most efficient catalysts contained either JohnPhos or IPr/SIPr. Phenols bearing either electron-withdrawing or electron-donating groups were efficiently added using these catalysts. No silver salts, acids, or solvents were needed for the catalysis, and either microwave or conventional heating afforded moderate to excellent yields of the vinyl ethers.

Controllable synthesis of silver and silver sulfide nanocrystals via selective cleavage of chemical bonds

International Nuclear Information System (INIS)

Tang Aiwei; Wang Yu; Ye Haihang; Zhou Chao; Yang Chunhe; Li Xu; Peng Hongshang; Zhang Fujun; Hou Yanbing; Teng Feng

2013-01-01

A one-step colloidal process has been adopted to prepare silver (Ag) and silver sulfide (Ag 2 S) nanocrystals, thus avoiding presynthesis of an organometallic precursor and the injection of a toxic phosphine agent. During the reaction, a layered intermediate compound is first formed, which then acts as a precursor, decomposing into the nanocrystals. The composition of the as-obtained products can be controlled by selective cleavage of S–C bonds or Ag–S bonds. Pure Ag 2 S nanocrystals can be obtained by directly heating silver acetate (Ag(OAc)) and n-dodecanethiol (DDT) at 200 ° C without any surfactant, and pure Ag nanocrystals can be synthesized successfully if the reaction temperature is reduced to 190 ° C and the amount of DDT is decreased to 1 ml in the presence of a non-coordinating organic solvent (1-octadecene, ODE). Otherwise, the mixture of Ag and Ag 2 S is obtained by directly heating Ag(OAc) in DDT by increasing the reaction temperature or in a mixture of DDT and ODE at 200 ° C. The formation mechanism has been discussed in detail in terms of selective S–C and Ag–S bond dissociation due to the nucleophilic attack of DDT and the lower bonding energy of Ag–S. Interestingly, some products can easily self-assemble into two- or three-dimensional (2D or 3D) highly ordered superlattice structures on a copper grid without any additional steps. The excess DDT plays a key role in the superlattice structure due to the bundling and interdigitation of the thiolate molecules adsorbed on the as-obtained nanocrystals. (paper)

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

Science.gov (United States)

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.

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

Directory of Open Access Journals (Sweden)

Bianco C

2015-03-01

Full Text Available Carlotta Bianco,1 Sanja Kezic,2 Matteo Crosera,1 Vesna Svetličić,3 Suzana Šegota,3 Giovanni Maina,4 Canzio Romano,5 Francesca Larese,6,7 Gianpiero Adami11Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy; 2Academic Medical Center, Coronel Institute, University of Amsterdam, Amsterdam, the Netherlands; 3Laboratory for Bioelectrochemistry and Surface Imaging, Division for Marine and Environmental Research, Ruder Boškovic Institute, Zagreb, Croatia; 4Department of Clinical and Biological Sciences, University of Turin, Turin, Italy; 5Department of Public and Pediatric Health Sciences, University of Turin, Turin, Italy; 6Unit of Occupational Medicine, University of Trieste, Trieste, Italy; 7Department of Medical Sciences, University of Trieste, Trieste, ItalyAbstract: 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

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

Energy Technology Data Exchange (ETDEWEB)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.; Srivastava, A. K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India); Varshney, G. K. [Laser Bio-medical Applications & Instrumentation Division, Raja Ramanna Centre for Advanced Technology Indore, Madhya Pradesh 452013 (India)

2016-05-23

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.

Protein-Modified-Paramagnetic-Particles as a Tool for Detection of Silver(I) Ions

Science.gov (United States)

Kizek, R.; Krizkova, S.; Adam, V.; Huska, D.; Hubalek, J.; Trnkova, L.

2009-04-01

In a number of published articles the toxic effect of silver(I) ions on aquatic organisms is described. Silver(I) ions in aquatic environment are stable in a wide range of pH. Under alkali pH AgOH and Ag(OH)2- can be formed. However, in water environment there are many compounds to interact with silver(I) ions. The most important ones are chloride anions, which forms insoluble precipitate with silver(I) ions (AgCl). The insoluble silver containing compounds do not pose any threat to aquatic organisms. Toxicity of silver ions is probably caused by their very good affinity to nucleic acids and also proteins. The binding into active enzyme site leads to the expressive enzyme reaction inhibition. Silver(I) ions are into living environment introduced thanks to anthropogenic activities. They easily contaminate atmosphere as well as aquatic environment or soils. Several authors described using of carbon electrode as working electrode for determination of silver. Recently, we have suggested heavy metal biosensor based on interaction of metal ions with low molecular mass protein called metallothionein (MT), which was adsorbed on the surface of hanging mercury drop electrode (HMDE). The biosensor was successfully used for detection of cadmium(II) and zinc(II) ions, cisplatin, cisplatin-DNA adducts and palladium(II) ions. Due to the convincing results with MT as biological component we report on suggesting of heavy metal biosensor based on immobilization of metallothionein (MT) on the surface of carbon paste electrode (CPE) via MT-antibodies. Primarily we studied of basic electrochemical behaviour of MT at surface of carbon paste electrode by using of square wave voltammetry (SWV). Detection limit (3 S/N) for MT was evaluated as 0.1 μg/ml. After that we have evaluated the electroactivity of MT at surface of SWV, we aimed our attention on the way of capturing of MT on the surface of CPE. We choose antibody against MT obtained from chicken eggs for these purposes. Antibodies

Synthesis and characterization of silver nanoparticles by sol-gel route from silver nitrate

International Nuclear Information System (INIS)

Morales, Jorge; Moran, Jose; Quintana, Maria; Estrada, Walter

2009-01-01

Silver nanoparticles colloids have been synthesized by sol-gel method. This synthesis consists in silver nitrate reduction by ethylene glycol in a process called polyol. The growth of the nanoparticles have been controlled by the steric stabilization of the colloid with polyvinylpyrrolidone (PVP, M w = 40 000). The silver nanoparticle size and structure was depending on the control of parameters such as: molar concentrations ratio of silver nitrate and PVP, temperature of reaction and the reflux time. Colloids have been characterized by UV-vis spectroscopy in the range from 300 to 1000 nm. The results show that the typical peak of surface plasmon resonance is formed at 400-450 nm indicating the formation of silver nanoparticles. The presences of silver nanoparticles of spherical shape with size among 20-40 nm were observed by transmission electronic microscopy (TEM). Electron diffraction patterns confirmed that synthesized colloids contain metallic silver with a crystal structure face centered cubic FCC. (author)

Structure and decomposition of the silver formate Ag(HCO{sub 2})

Energy Technology Data Exchange (ETDEWEB)

Puzan, Anna N., E-mail: anna_puzan@mail.ru; Baumer, Vyacheslav N.; Mateychenko, Pavel V.

2017-02-15

Crystal structure of the silver formate Ag(HCO{sub 2}) has been determined (orthorhombic, sp.gr. Pccn, a=7.1199(5), b=10.3737(4), c=6.4701(3)Å, V=477.88(4) Å{sup 3}, Z=8). The structure contains isolated formate ions and the pairs Ag{sub 2}{sup 2+} which form the layers in (001) planes (the shortest Ag–Ag distances is 2.919 in the pair and 3.421 and 3.716 Å between the nearest Ag atoms of adjacent pairs). Silver formate is unstable compound which decompose spontaneously vs time. Decomposition was studied using Rietveld analysis of the powder diffraction patterns. It was concluded that the diffusion of Ag atoms leads to the formation of plate-like metal particles as nuclei in the (100) planes which settle parallel to (001) planes of the silver formate matrix. - Highlights: • Silver formate Ag(HCO{sub 2}) was synthesized and characterized. • Layered packing of Ag-Ag pairs in the structure was found. • Decomposition of Ag(HCO{sub 2}) and formation of metal phase were studied. • Rietveld-refined micro-structural characteristics during decomposition reveal the space relationship between the matrix structure and forming Ag phase REPLACE with: Space relationship between the matrix structure and forming Ag phase.

Use of a silver ion selective electrode to assess mechanisms responsible for biological effects of silver nanoparticles

International Nuclear Information System (INIS)

Koch, Marcus; Kiefer, Silke; Cavelius, Christian; Kraegeloh, Annette

2012-01-01

For a detailed analysis of the biological effects of silver nanoparticles, discrimination between effects related to the nano-scale size of the particles and effects of released silver ions is required. Silver ions are either present in the initial particle dispersion or released by the nanoparticles over time. The aim of this study is to monitor the free silver ion activity {Ag + } in the presence of silver nanoparticles using a silver ion selective electrode. Therefore, silver in the form of silver nanoparticles, 4.2 ± 1.4 nm and 2–30 nm in size, or silver nitrate was added to cell culture media in the absence or presence of A549 cells as a model for human type II alveolar epithelial cells. The free silver ion activity measured after the addition of silver nanoparticles was determined by the initial ionic silver content. The p {Ag + } values indicated that the cell culture media decrease the free silver ion activity due to binding of silver ions by constituents of the media. In the presence of A549 cells, the free silver ion activity was further reduced. The morphology of A549 cells, cultivated in DME medium containing 9.1% (v/v) FBS, was affected by adding AgNO 3 at concentrations of ≥30 μM after 24 h. In comparison, silver nanoparticles up to a concentration of 200 μM Ag did not affect cellular morphology. Our experiments indicate that the effect of silver nanoparticles is mainly mediated by silver ions. An effect of silver on cellular morphology was observed at p {Ag + } ≤ 9.2.

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

Energy Technology Data Exchange (ETDEWEB)

Mahl, Dirk; Diendorf, Joerg; Ristig, Simon [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Greulich, Christina [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Li Zian; Farle, Michael [University of Duisburg-Essen, Faculty of Physics, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Koeller, Manfred [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Epple, Matthias, E-mail: matthias.epple@uni-due.de [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

2012-10-15

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 {mu}g mL{sup -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.

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

Science.gov (United States)

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).

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

International Nuclear Information System (INIS)

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

2006-01-01

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)

Complexes of silver(I) ions and silver phosphate nanoparticles with hyaluronic acid and/or chitosan as promising antimicrobial agents for vascular grafts.

Science.gov (United States)

Chudobova, Dagmar; Nejdl, Lukas; Gumulec, Jaromir; Krystofova, Olga; Rodrigo, Miguel Angel Merlos; Kynicky, Jindrich; Ruttkay-Nedecky, Branislav; Kopel, Pavel; Babula, Petr; Adam, Vojtech; Kizek, Rene

2013-06-28

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes.

Fractionation of silver isotopes in native silver explained by redox reactions

Science.gov (United States)

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

Preparation of Crosslinked Amphiphilic Silver Nanogel as Thin Film Corrosion Protective Layer for Steel

Directory of Open Access Journals (Sweden)

Ayman M. Atta

2014-07-01

Full Text Available Monodisperse silver nanoparticles were synthesized by a new developed method via reaction of AgNO3 and oleic acid with the addition of a trace amount of Fe3+ ions. Emulsion polymerization at room temperature was employed to prepare a core-shell silver nanoparticle with controllable particle size. N,N'-methylenebisacrylamide (MBA and potassium peroxydisulfate (KPS were used as a crosslinker, and as redox initiator system, respectively for crosslinking polymerization. The structure and morphology of the silver nanogels were characterized by Fourier transform infrared spectroscopy (FTIR, transmission and scanning electron microscopy (TEM and SEM. The effectiveness of the synthesized compounds as corrosion inhibitors for steel in 1 M HCl was investigated by various electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS. Monolayers of silver nanoparticle were self-assembled on the fresh active surface of the steel electrode and have been tested as a corrosion inhibitor for steel in 1 M HCl solution. The results of polarization measurements showed that nanogel particles act as a mixed type inhibitor.

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

International Nuclear Information System (INIS)

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

2017-01-01

Highlights: • Silver is one of the biocides of water consumed in the International Space Station. • Ionic silver is depleted from potable water when in contact with stainless steel (SS). • SEM and XPS analysis reveal a uniform silver deposition over the SS surface. • Silver deposits in its metallic form, in line with a galvanic deposition mechanism. • Evidence is provided that Cr and/ or Ni oxide builds-up on SS surfaces. - Abstract: 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.

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

Energy Technology Data Exchange (ETDEWEB)

Petala, M., E-mail: petala@civil.auth.gr [Department of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece); Tsiridis, V. [Department of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece); Mintsouli, I. [Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece); Pliatsikas, N. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece); Spanos, Th. [Department of Petroleum and Mechanical Engineering Sciences, Eastern Macedonia and Thrace Institute of Technology, Kavala, 65404 (Greece); Rebeyre, P. [ESA/ESTEC, P.O.Box 299, 2200 AG, Noordwijk (Netherlands); Darakas, E. [Department of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece); Patsalas, P.; Vourlias, G. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece); Kostoglou, M.; Sotiropoulos, S.; Karapantsios, Th. [Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, 54124 (Greece)

2017-02-28

Highlights: • Silver is one of the biocides of water consumed in the International Space Station. • Ionic silver is depleted from potable water when in contact with stainless steel (SS). • SEM and XPS analysis reveal a uniform silver deposition over the SS surface. • Silver deposits in its metallic form, in line with a galvanic deposition mechanism. • Evidence is provided that Cr and/ or Ni oxide builds-up on SS surfaces. - Abstract: 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.

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

Science.gov (United States)

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.

Antimicrobial, Antioxidant and Cytotoxic Activity of Silver Nanoparticles Synthesized by Leaf Extract of Erythrina suberosa (Roxb.).

Science.gov (United States)

Mohanta, Yugal K; Panda, Sujogya K; Jayabalan, Rasu; Sharma, Nanaocha; Bastia, Akshaya K; Mohanta, Tapan K

2017-01-01

In this experiment, biosynthesized silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Erythrina suberosa (Roxb.). The biosynthesis of silver nanoparticle was continuously followed by UV-vis spectrophotometric analysis. The response of the phytoconstituents resides in E. suberusa during synthesis of stable AgNPs were analyzed by ATR- fourier-transform infrared spectroscopy. Further, the size, charge, and polydispersity nature of AgNPs were studied using dynamic light scattering spectroscopy. The morphology of the nanoparticles was determined by scanning electron microscopy. Current result shows core involvement of plant extracts containing glycosides, flavonoids, and phenolic compounds played a crucial role in the biosynthesis of AgNPs. The antimicrobial activities of silver nanoparticles were evaluated against different pathogenic bacterium and fungi. The antioxidant property was studied by radical scavenging (DPPH) assay and cytotoxic activity was evaluated against A-431 osteosarcoma cell line by MTT assay. The characteristics of the synthesized silver nanoparticles suggest their application as a potential antimicrobial and anticancer agent.

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

Science.gov (United States)

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.

Silver Nanoparticles and Graphitic Carbon Through Thermal Decomposition of a Silver/Acetylenedicarboxylic Salt

Directory of Open Access Journals (Sweden)

Komninou Philomela

2009-01-01

Full Text Available Abstract Spherically shaped silver nanoparticles embedded in a carbon matrix were synthesized by thermal decomposition of a Ag(I/acetylenedicarboxylic acid salt. The silver nanoparticles, which are formed either by pyrolysis at 300 °C in an autoclave or thermolysis in xylene suspension at reflux temperature, are acting catalytically for the formation of graphite layers. Both reactions proceed through in situ reduction of the silver cations and polymerization of the central acetylene triple bonds and the exact temperature of the reaction can be monitored through DTA analysis. Interestingly, the thermal decomposition of this silver salt in xylene partly leads to a minor fraction of quasicrystalline silver, as established by HR-TEM analysis. The graphitic layers covering the silver nanoparticles are clearly seen in HR-TEM images and, furthermore, established by the presence of sp2carbon at the Raman spectrum of both samples.

The mode of occurrence of gold and silver in the Dominian Reef and their response to cyanidation after pressure leading

International Nuclear Information System (INIS)

Glatthaar, C.W.; Feather, C.E.

1985-01-01

Gold and silver in the Upper Reef of the Dominion Group in the Afrikander Lease area occur in several minerals. Native gold, electrum, and amalgam are the main gold bearers, whereas silver, in addition to being present in the above alloys, is also represented by native silver, in mercurian silver (arquerite), acanthite, stromeyerite, and a bismuth-silver sulphide (schaba-chite or pavionite), and in solid solution in galena. Only minute quantities of these silver-bearing minerals were found, and attempts to evaluate their relative abundances in the ore proved to be difficult. It was possible, however, by use of an electron microprobe, to quantify the silver contents in electrum, amalgam, mercurian silver, and galena. Mass-balance studies based on the calculated galena content suggest that about half of the total silver is associated with galena in solid solution. In practice, the uranium present in the conglomerates of the Dominion Group is extracted first. Because of the refractory nature of the uranium-bearing minerals, a leach at high temperature and high pressure is recommended. While this pressure leach is beneficial to the subsequent cyanidation of gold, a large proportion of the silver present is rendered refractory. The poor recoveries of silver are believed to be due close association of silver and galena. It is believed that silver is released during the dissolution of galena, acanthite, other silver sulphides, and native silver, and subsequently precipitated either as an insoluble complex silver-iron sulphate (argentojarosite) or in solid solution in jarosite (potassium-iron sulphate). Neither compound is amenable to cyanidation. A mixture of plumbojarosite (lead-iron sulphate) and jarosite were seen to form protective coatings on galena particles, and may occlude other silver-bearing minerals in the same manner. In contrast, finely divided gold particles are liberated from pyrite and other minerals during pressure leaching and become readily available to

Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent

Energy Technology Data Exchange (ETDEWEB)

Holtz, R D; Souza Filho, A G; Alves, O L [Laboratorio de Quimica do Estado Solido (LQES), Instituto de Quimica, Universidade Estadual de Campinas, CP 6154, 13081-970, Campinas-SP (Brazil); Brocchi, M; Martins, D [Departamento de Genetica, Evolucao and Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP (Brazil); Duran, N, E-mail: rholtz@iqm.unicamp.br, E-mail: agsf@fisica.ufc.br, E-mail: oalves@iqm.unicamp.br [Laboratorio de Quimica Biologica, Instituto de Quimica, Universidade Estadual de Campinas, Campinas-SP (Brazil)

2010-05-07

In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

Comparison of the bacterial removal performance of silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane coated point-of-use ceramic water filters.

Science.gov (United States)

Zhang, Hongyin; Oyanedel-Craver, Vinka

2013-09-15

This study compares the disinfection performance of ceramic water filters impregnated with two antibacterial compounds: silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane (poly(trihydroxysilyl) propyldimethyloctadecyl ammonium chloride (TPA)). This study evaluated these compounds using ceramic disks manufactures with clay obtained from a ceramic filter factory located in San Mateo Ixtatan, Guatemala. Instead of using full size ceramic water filters, manufactured 6.5 cm diameter ceramic water filter disks were used. Results showed that TPA can achieve a log bacterial reduction value of 10 while silver nanoparticles reached up to 2 log reduction using a initial concentration of bacteria of 10(10)-10(11)CFU/ml. Similarly, bacterial transport demonstrated that ceramic filter disks painted with TPA achieved a bacterial log reduction value of 6.24, which is about 2 log higher than the values obtained for disks painted with silver nanoparticles (bacterial log reduction value: 4.42). The release of both disinfectants from the ceramic materials to the treated water was determined measuring the effluent concentrations in each test performed. Regarding TPA, about 3% of the total mass applied to the ceramic disks was released in the effluent over 300 min, which is slightly lower than the release percentage for silver nanoparticles (4%). This study showed that TPA provides a comparable disinfection performance than silver nanoparticles in ceramic water filter. Another advantage of using TPA is the cost as the price of TPA is considerable lower than silver nanoparticles. In spite of the use of TPA in several medical related products, there is only partial information regarding the health risk associated with the ingestion of this compound. Additional long-term toxicological information for TPA should be evaluated before its future application in ceramic water filters. Copyright © 2013 Elsevier B.V. All rights reserved.

Cytotoxic effects of nanosilver are highly dependent on the chloride concentration and the presence of organic compounds in the cell culture media.

Science.gov (United States)

Kaiser, Jean-Pierre; Roesslein, Matthias; Diener, Liliane; Wichser, Adrian; Nowack, Bernd; Wick, Peter

2017-01-06

Nanosilver shows great promise for use in industrial, consumer or medical products because of its antimicrobial properties. However, the underlying mechanisms of the effects of silver nanoparticles on human cells are still controversial. Therefore, in the present study the influence of the chloride concentration and different serum content of culture media on the cytotoxic effects of nanosilver was systematically evaluated. Our results show that nanosilver toxicity was strongly affected by the composition of the culture media. The chloride concentration, as well as the carbon content affected the silver agglomeration and the complex formation. But also the dissolution of nanosilver and the availability of free silver ions (Ag + ) were severely affected by the compositions of the culture media. Cells, only exposed to silver particles in suspension and dissolved silver complexes, did not show any effects under all conditions. Nanosilver agglomerates and silver complexes were not very soluble. Thus, cells growing on the bottom of the culture dishes were exposed to sedimented nanosilver agglomerates and precipitated silver complexes. Locally, the concentration of silver on the cell surface was very high, much higher compared the silver concentration in the bulk solution. The cytotoxic effects of nanosilver are therefore a combination of precipitated silver complexes and organic silver compounds rather than free silver ions. Silver coatings are used in health care products due to their bacteriostatic or antibacterial properties. The assessment of the toxicity of a certain compound is mostly done using in vitro assays. Therefore, cytotoxicity studies of nanosilver using human cell cultures have to be undertaken under well controlled and understood cultivations conditions in order to improve the compatibility of different studies. Especially when eukaryotic versus prokaryotic systems are compared for the evaluation of the use of nanosilver as antibacterial coatings for

The Synthesis of Silver Nanoparticles Produced by Chemical Reduction of Silver Salt Solution

International Nuclear Information System (INIS)

Sri Budi Harmani; Dewi Sondari; Agus Haryono

2008-01-01

Described in this research are the synthesis of silver nanoparticle produced by chemical reduction of silver salt (silver nitrate AgNO 3 ) solution. As a reducer, sodium citrate (C 6 H 5 O 7 Na 3 ) was used. Preparation of silver colloid is done by using chemical reduction method. In typical experiment 150 ml of 1.10 -3 M AgNO 3 solution was heated with temperature variation such as 90, 100, 110 degree of Celsius. To this solution 15 ml of 1 % trisodium citrate was added into solution drop by drop during heating. During the process, solution was mixed vigorously. Solution was heated until colour's change is evident (pale yellow solution is formed). Then it was removed from the heating element and stirred until cooled to room temperature. Experimental result showed that diameter of silver nanoparticles in colloid solution is about 28.3 nm (Ag colloid, 90 o C); 19.9 nm (Ag colloid, 100 o C)and 26.4 nm (Ag colloid, 110 o C). Characterization of the silver nanoparticle colloid conducted by using UV-Vis Spectroscopy, Particles Size Analyzer (PSA) and Scanning Electron Microscope (SEM) indicate the produced structures of silver nanoparticles. (author)

3-D silver(I)-lanthanide(III) heterometallic-organic frameworks constructed from 2,2'-bipyridine-3,3'-dicarboxylic acid: synthesis, structure, photoluminescence, and their remarkable thermostability.

Science.gov (United States)

Zhou, Yunshan; Li, Xiaomin; Zhang, Lijuan; Guo, Yan; Shi, Zonghai

2014-04-07

A new family of silver(I)-lanthanide(III) heterometallic-organic frameworks having the formula [AgLn(bpdc)2] (Ln = Eu (1), Tb (2), Sm (3), Dy (4), Y (5), Yb (6), Er (7), Ho (8); H2bpdc = 2,2'-bipyridine-3,3'-dicarboxylic acid), each of which crystallizes in the monoclinic space group C2/c with Z = 4, has been hydrothermally synthesized. The compounds were characterized by means of IR, elemental analysis, thermogravimetric-differential thermal analysis, and powder X-ray diffraction (XRD), wherein compounds 1, 2, and 4-8 were structurally characterized. The powder XRD and single-crystal structures of the title compounds indicate that all the compounds are isostructural and feature a three-dimensional (3-D) open framework. In the structures of the compounds, bpdc(2-) ligands link Ln(3+) through their carboxylic groups, resulting in the formation of a one-dimensional {Ln(bpdc)2}n infinite chain along the c direction. The adjacent chains are then connected to each other through the coordination interaction between Ag(+) and the pyridyl N atoms of bpdc(2-) ligands from the chains, resulting in a 3-D (2,4,6)-connected open framework with (4(11)·6(4))(4(3)·8(2)·10)(8)2 topology. The compounds show remarkable good thermally stability up to 370 °C because neither aquo ligands nor lattice water molecules exist in the composition of the compounds. The photoluminescent properties of compounds 1 and 2 were studied in detail. The energy level of the triplet states of the ligand H2bpdc 21,505 cm(-1) (465 nm) was determined based on the 77 K emission spectrum of the compound [Gd2(bpdc)3(phen)2(H2O)2]·6H2O 9. The (5)D0 and (5)D4 emission lifetimes (1.58 and 1.76 ms) and the overall quantum yields (21% and 22%) were determined for the compounds 1 and 2, respectively.

Synthesis and crystal structure of the cesium silver permanganate Cs{sub 3}Ag[MnO{sub 4}]{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Bauchert, Joerg M.; Henning, Harald; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany)

2012-09-15

After successful syntheses and structural refinements of the already known permanganates of cesium (Cs[MnO{sub 4}]) and silver (Ag[MnO{sub 4}]) we started to blend aqueous solutions of both components in various molar ratios. From crystallization experiments of these mixtures only three species of crystals with different chemical compositions were obtained: tricesium monosilver tetrakispermanganate (Cs{sub 3}Ag[MnO{sub 4}]{sub 4}) and, depending upon the respective ratio, either additional silver permanganate or surplus cesium permanganate, namely. The new title compound crystallizes in the orthorhombic space group Pnnm (no. 58) with two formula units per unit cell and cell dimensions of a = 764.53(4), b = 1883.57(9) and c = 584.34(3) pm. The crystal structure of Cs{sub 3}Ag[MnO{sub 4}]{sub 4} consists of two crystallographically distinguishable cesium cations. (Cs1){sup +} is surrounded by fourteen oxygen atoms constructing a slightly distorted bicapped hexagonal prism. These polyhedra are connected through edge-sharing with two other polyhedra of this kind to form chains along [001]. The chains are linked to each other via sixfold coordinated Ag{sup +} cations (d(Ag-O) = 238-246 pm), arranged in such a manner that they link three oxygen atoms of two cesium polyhedra, leading to a two-dimensional layer spreading out parallel to the (001) plane. Together with the two crystallographically different tetrahedral oxomanganate(VII) anions [MnO{sub 4}]{sup -} (d(Mn-O) = 161-162 pm) the other kind of cesium cations ((Cs2){sup +} with CN = 13) finally connect these layers three-dimensionally. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Drug products containing colloidal silver... Drug products containing colloidal silver ingredients or silver salts offered over-the-counter (OTC) for the treatment and/or prevention of disease. (a) Colloidal silver ingredients and silver salts have...

Characterization of Electrochemically Generated Silver

Science.gov (United States)

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 (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.

Relaxation of the silver/silver iodide electrode in aqueous solution

NARCIS (Netherlands)

Peverelli, K.J.

1979-01-01

The aim of this study is to detect and characterize relaxation processes on silver/silver iodide electrodes in aqueous electrolyte solution. The information obtained is to be used for an estimation of the consequences of similar processes on colloidal AgI

Synthesis, crystal structure and biological activity of a novel 1,2,3-thidiazole compound

International Nuclear Information System (INIS)

Ke, W.

2013-01-01

A new 1,2,3-thiadiazole compound was synthesized and characterized by 1H NMR, MS and HRMS. The crystal structure of the title compound (C/sub 12/H/sub 11/ClN/sub 2/O/sub 4/S/sub 2/, Mr = 346.80) has been determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P-1 with a = 8.4425(17) A, b = 8.9801(18) A, c = 9.859(2) A, alpha = 84.36(3) degree, beta = 86.71(3)degree, lambda = 83.25(3) degree, V = 737.9(3)A3, Z 2, F(000) = 356, Dc = 1.561 g/cm/sup 3/, mu = 0.557 mm-1, the final R1 0.0380 and wR2 = 0.0982 for 2160 observed reflections with I > 2sigma(I). A total of 12585 reflections were collected, of which 2601 were independent (Rint 0.0364). The herbicidal activity of title compound was determined, the results showed the title compound displayed excellent herbicidal activity against Brassica campestris. (author)

Size distribution of silver nanoclusters induced by ion, electron, laser beams and thermal treatments of an organometallic precursor

International Nuclear Information System (INIS)

D'Urso, L.; Nicolosi, V.; Compagnini, G.; Puglisi, O.

2004-01-01

Recently, a huge variety of physical and chemical synthetic processes have been reported to prepare nanostructured materials made of very small (diameter<50 nm) metallic clusters. Depending on the nature of clusters, this new kind of materials posses interesting properties (electronic, optical, magnetic, catalytic) that can be tailored as a function of the particles size and shape. Silver nanoparticles have been obtained by direct thermal treatment or by beam-enhanced decomposition (ion, electron and laser) of a silver organometallic compound (precursor) spinned onto suitable substrates. In this paper, we present the results of a study on the size distribution of such nanoparticles as a function of the different synthesis methods. It was found that the methods employed strongly affect the silver nanoparticles formation. Smaller silver nanoclusters were obtained after reduction by ion beam irradiation and thermal treatment, as observed by using different techniques (AFM, XRD and UV-Vis)

OBTAINING AND ACTIVITY OF SILVER NANOPARTICLES BASED ON THE EXOPOLYSACCHARIDE OF DIAZOTROPHIC STRAIN Bradyrhizobium japonicum 36 AND AgNO3

Directory of Open Access Journals (Sweden)

B. A. Rasulov

2014-12-01

Full Text Available The aim of the research was to obtain silver nanoparticles and to study of its antibacterial activity against pathogenic cultures Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538. Obtained complex was characterized by UV-Vis spectroscopy, X-ray diffraction (XRD and transmission electron microscopy (TEM. Colloid solutions of the complex absorbed radiation in the visible regions of 420–460 nm, which confirmed the formation of silver nanoparticles. The size of synthesized SNP varied from 6 to 50 nm. There has been confirmed presence in them of atomic silver. Obtained compound possessed antibacterial activity against pathogens, such as Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538.

Alternative Silver Production by Environmental Sound Processing of a Sulfo Salt Silver Mineral Found in Bolivia

Directory of Open Access Journals (Sweden)

Alexander Birich

2018-02-01

Full Text Available Very often, the production of silver causes devastating environmental issues, because of the use of toxic reagents like cyanide and mercury. Due to severe environmental damage caused by humans in the last decades, the social awareness regarding the sustainable production processes is on the rise. Terms like “sustainable” and “green” in product descriptions are becoming more and more popular and producers are forced to satisfy the rising environmental awareness of their customers. Within this work, an alternative environmental sound silver recovery process was developed for a vein type silver ore from Mina Porka, Bolivia. A foregoing characterization of the input material reveals its mineral composition. In the following mineral processing, around 92.9% silver was concentrated by separating 59.5 wt. % of non-silver minerals. Nitric acid leaching of the generated concentrate enabled a silver recovery of up to 98%. The dissolved silver was then separated via copper cementation to generate a metallic silver product of >99% purity. Summarizing all process steps, a silver yield of 87% was achieved in lab scale. A final upscaling trial was conducted to prove the process’ robustness. Within this trial, almost 4 kg of metallic silver with a purity of higher than 99.5 wt. % was produced.

Franklin D. Roosevelt, Silver, and China.

OpenAIRE

Friedman, Milton

1992-01-01

The silver purchase program, initiated by Franklin Roosevelt in late 1933 in response to the economically small but politically potent silver bloc, gave a large short-run subsidy to silver producers at the cost of destroying any long-run monetary role for silver. More important, it imposed severe deflation on China, the only major country still on a silver standard, and forced it off the silver standard and on to a fiat standard, which brought forward in time and increased in severity the sub...

42 CFR 476.86 - Correlation of Title XI functions with Title XVIII functions.

Science.gov (United States)

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Correlation of Title XI functions with Title XVIII functions. 476.86 Section 476.86 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF...) Qio Review Functions § 476.86 Correlation of Title XI functions with Title XVIII functions. (a...

Thermal decomposition process of silver behenate

International Nuclear Information System (INIS)

Liu Xianhao; Lu Shuxia; Zhang Jingchang; Cao Weiliang

2006-01-01

The thermal decomposition processes of silver behenate have been studied by infrared spectroscopy (IR), X-ray diffraction (XRD), combined thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS), transmission electron microscopy (TEM) and UV-vis spectroscopy. The TG-DTA and the higher temperature IR and XRD measurements indicated that complicated structural changes took place while heating silver behenate, but there were two distinct thermal transitions. During the first transition at 138 deg. C, the alkyl chains of silver behenate were transformed from an ordered into a disordered state. During the second transition at about 231 deg. C, a structural change took place for silver behenate, which was the decomposition of silver behenate. The major products of the thermal decomposition of silver behenate were metallic silver and behenic acid. Upon heating up to 500 deg. C, the final product of the thermal decomposition was metallic silver. The combined TG-MS analysis showed that the gas products of the thermal decomposition of silver behenate were carbon dioxide, water, hydrogen, acetylene and some small molecule alkenes. TEM and UV-vis spectroscopy were used to investigate the process of the formation and growth of metallic silver nanoparticles

A two-dimensional silver(I) coordination polymer constructed from 4-aminophenylarsonate and triphenylphosphane: poly[[(μ₃-4-aminophenylarsonato-κ³N:O:O)(triphenylphosphane-κP)silver(I)] monohydrate].

Science.gov (United States)

Xiao, Zu-Ping; Wen, Meng; Wang, Chun-Ya; Huang, Xi-He

2015-04-01

The title compound, {[Ag(C6H7AsNO3)(C18H15P)]·H2O}n, has been synthesized from the reaction of 4-aminophenylarsonic acid with silver nitrate, in aqueous ammonia, with the addition of triphenylphosphane (PPh3). The Ag(I) centre is four-coordinated by one amino N atom, one PPh3 P atom and two arsonate O atoms, forming a severely distorted [AgNPO2] tetrahedron. Two Ag(I)-centred tetrahedra are held together to produce a dinuclear [Ag2O2N2P2] unit by sharing an O-O edge. 4-Aminophenylarsonate (Hapa(-)) adopts a μ3-κ(3)N:O:O-tridentate coordination mode connecting two dinuclear units, resulting in a neutral [Ag(Hapa)(PPh3)]n layer lying parallel to the (101̄) plane. The PPh3 ligands are suspended on both sides of the [Ag(Hapa)(PPh3)]n layer, displaying up and down orientations. There is an R2(2)(8) hydrogen-bonded dimer involving two arsonate groups from two Hapa(-) ligands related by a centre of inversion. Additionally, there are hydrogen-bonding interactions involving the solvent water molecules and the arsonate and amine groups of the Hapa(-) ligands, and weak π-π stacking interactions within the [Ag(Hapa)(PPh3)]n layer. These two-dimensional layers are further assembled by weak van der Waals interactions to form the final architecture.

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

Science.gov (United States)

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.

Silver against Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Kirketerp-Møller, K.; Kristiansen, S.

2007-01-01

bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa......, but that the silver concentration is important. A concentration of 5-10 ig/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 ig/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate...... planktonic bacteria. These observations strongly indicate that the concentration of silver in currently available wound dressings is much too low for treatment of chronic biofilm wounds. It is suggested that clinicians and manufacturers of the said wound dressings consider whether they are treating wounds...

One-Pot Silver Nanoring Synthesis

Science.gov (United States)

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.

Timber industry waste-teak ( Tectona grandis Linn.) leaf extract mediated synthesis of antibacterial silver nanoparticles

Science.gov (United States)

Devadiga, Aishwarya; Shetty, K. Vidya; Saidutta, M. B.

2015-08-01

The current research article emphasizes efficacious use of teak leaves, an agro -biowaste from world's premier hardwood timber industry, for "green" synthesis of silver nanoparticles (AgNPs). Bioactive compounds of the leaves act as prolific reducing and stabilizing agents in AgNP synthesis. The characterization of the AgNPs synthesized using teak leaves revealed that the particles are spherical with an average size of 28 nm and the presence of bioactive compounds present in teak leaf extract as capping agents on the nanoparticles. A prominent decrease in the content of bioactive compounds such as polyphenols, antioxidants and flavonoids after the biosynthesis of AgNPs signifies that these class of compounds act as reductants and stabilizers during biosynthesis. The biosynthesized silver nanoparticles were also successfully evaluated for their antibacterial characteristics against waterborne pathogens, E. coli and S. aureus, with minimum inhibitory concentration of 25.6 μg/mL. Exploitation of agrowaste resources for synthesis of AgNPs curtails indiscriminate usage of food and commercial plant materials, rather contributing a sustainable way for effective plant waste biomass utilization and management. The biosynthesized AgNps have potential application in water purifiers, antibacterial fabrics, sports wear and in cosmetics as antibacterial agent and the process used for its synthesis being greener is highly beneficial from environmental, energy consumption and economic perspectives.

20 CFR 404.535 - How much will we withhold from your title VIII and title XVI benefits to recover a title II...

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title... Officer § 404.535 How much will we withhold from your title VIII and title XVI benefits to recover a title II overpayment? (a) If past-due benefits are payable to you, we will withhold the lesser of the...

Electrical studies on silver based fast ion conducting glassy materials

International Nuclear Information System (INIS)

Rao, B. Appa; Kumar, E. Ramesh; Kumari, K. Rajani; Bhikshamaiah, G.

2014-01-01

Among all the available fast ion conductors, silver based glasses exhibit high conductivity. Further, glasses containing silver iodide enhances fast ion conducting behavior at room temperature. Glasses of various compositions of silver based fast ion conductors in the AgI−Ag 2 O−[(1−x)B 2 O 3 −xTeO 2 ] (x=0 to1 mol% in steps of 0.2) glassy system have been prepared by melt quenching method. The glassy nature of the compounds has been confirmed by X-ray diffraction. The electrical conductivity (AC) measurements have been carried out in the frequency range of 1 KHz–3MHz by Impedance Analyzer in the temperature range 303–423K. The DC conductivity measurements were also carried out in the temperature range 300–523K. From both AC and DC conductivity studies, it is found that the conductivity increases and activation energy decreases with increasing the concentration of TeO 2 as well as with temperature. The conductivity of the present glass system is found to be of the order of 10 −2 S/cm at room temperature. The ionic transport number of these glasses is found to be 0.999 indicating that these glasses can be used as electrolyte in batteries

One-Pot Silver Nanoring Synthesis

Directory of Open Access Journals (Sweden)

Drogat Nicolas

2009-01-01

Full Text Available Abstract 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.

Investigation of interaction between silver oxide electrode and separator hydrated cellulose film in silver-cadmium accumulators

International Nuclear Information System (INIS)

Molotkova, E.N.; Yarochkina, E.N.

1975-01-01

Oxidation-reduction interaction of the oxysilver electrode with hydrocellulose film during storing charged silver-cadmium accumulators. It was demonstrated that accumulator electric characteristics durinq storing are linearly depending on the capacity of this hydrocellulose film to interact with silver oxide: the more silver is absorbed by film the quicker is the decreasing of the electromotive force and capacity of the accumulators. Preservation of the silver electrode capacity in the silver-cadmium accumulators is determined first of all by hydrocellulose separation film properties and especially by film layer adjacent to positive electrode. The more inert film layer is, regarding to silver oxide in the electrolite, the slower is dissolution of the electrode and also decompousing speed of AgO, the longer is the accumulator preservation time

Low-silver radiographic detectors

International Nuclear Information System (INIS)

Troitskii, V.A.; Novikov, I.A.; Nikitin, V.F.; Krasnyi-Admoni, L.V.; Valevich, M.I.; Belyi, N.G.; Grom, V.S.

1988-01-01

X-ray films and screens with low silver content for use in weld radiography are reviewed and tested. Properties examined include image graininess, brightness, and sensitivity to x radiation. Results are given for radiography of steel 08Kh18N10T, St20, AMG-6, copper, and titanium welds. Processing techniques for low-silver films are discussed. It is established that films and screens containing little silver can replace many x-ray films containing much more silver. Monitoring methods were developed for the new materials to cover items in classes 3-7 on GOST 23075-78 when used with equipment of RUP-150/300-10 type or classes 4-7 with pulsed x-ray equipment

One-pot silver nanoring synthesis.

OpenAIRE

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

2009-01-01

Abstract 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...

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

Science.gov (United States)

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.

Silver-Palladium Surfaces Inhibit Biofilm Formation

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

2009-01-01

Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

Antioxidant and anti-inflammatory activities of silver nanoparticles biosynthesized from aqueous leaves extracts of four Terminalia species

Science.gov (United States)

El-Rafie, Hanaa Mohamed; Abdel-Aziz Hamed, Manal

2014-09-01

The environmentally friendly synthesis of nanoparticles process is a revolutionary step in the field of nanotechnology. In recent years plant mediated biological synthesis of nanoparticles has been gaining importance due to its simplicity and eco-friendliness. In this study, a simple and an efficient eco-friendly approach for the biosynthesis of stable, monodisperse silver nanoparticles using aqueous extracts of four Terminalia species, namely, Terminalia catappa, Terminalia mellueri, Terminalia bentazoe and Terminalia bellerica were described. The silver nanoparticles were characterized in terms of synthesis, capping functionalities (polysaccharides, phenolics and flavonoidal compounds) and microscopic evaluation by UV-visible spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. The results showed a simple and feasible approach for obtaining stable aqueous monodispersive silver nanoparticles. Furthermore, biological activity of the biosynthesized silver nanoparticles was examined. Concerning this, dose-dependent antioxidant activity of silver nanoparticles imparted by the plant phenolic and flavonoidal components was evaluated using in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and found to be comparable to standard ascorbic acid. The same holds true for the anti-inflammatory activity where Terminalia catappa and Terminalia mellueri have a high-test inhibition percentage better than that of ascorbic acid in the carrageenan induced hind paw edema. The results also revealed that the aqueous extract of Terminallia catapa and its silver nanoparticles recorded the most potent in vivo antioxidant effect.

High-performance electrically conductive silver paste prepared by silver-containing precursor

Energy Technology Data Exchange (ETDEWEB)

Liu, Jianguo; Cao, Yu; Li, Xiangyou; Wang, Xiaoye; Zeng, Xiaoyan [Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Wuhan (China)

2010-09-15

A high-performance electrically conductive silver paste with no solid particles before drying and/or sintering is developed, in which silver-containing precursor is employed as conductive functional phase. Thermogravimetry analysis, volume electrical resistivity tests and sintering experiments show that the paste with about 14 wt.% silver pristine content is able to achieve the volume electrical resistivity of (2-3) x 10{sup -5} {omega} cm after it is sintered at 220 C. A micro-pen direct-writing process indicates that it is very suitable for the fabrication of high-resolution (25 {mu}m) and high-integration devices and apparatus. (orig.)

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

Science.gov (United States)

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.

In vitro assessment of the antimicrobial activity of silver and zinc oxide nanoparticles against fish pathogens.

Science.gov (United States)

Shaalan, Mohamed Ibrahim; El-Mahdy, Magdy Mohamed; Theiner, Sarah; El-Matbouli, Mansour; Saleh, Mona

2017-07-21

integrity. This is the first study on inhibitory effects of silver and zinc oxide nanoparticles towards A. salmonicida and A. invadans. Moreover, zinc oxide nanoparticles inhibited the growth of Y. ruckeri. In low concentrations, silver nanoparticles were less cytotoxic than zinc oxide nanoparticles and represent an alternative antimicrobial compound against A. hydrophila, A. salmonicida and A. invadans.

Interaction of simple indium iodides with silver- and aluminium iodides

International Nuclear Information System (INIS)

Denisov, Yu.N.; Halova, N.S.; Fedorov, P.I.

1976-01-01

Fusibility diagrams of the systems InI-AlI 3 , InI-AgI, InI 2 -AgI, and InI 2 -AlI 3 have been studied. In the system InI-AlI 3 a compound InAlI 4 has been detected having a melting point 194 deg C and two lamination regions. In the system InI-AgI two compounds In 2 AgI 3 and InAgI 2 are formed which melt incongruently at 272 deg and 220 deg C, respectively. The formation of the compounds has been confirmed by X-ray phase analysis. Specific electroconductivity of a number of alloys of the system InI-AlI 3 has been studied. The systems of eutectic type formed by diiodide of indium with iodides of silver and aluminium have been studied by thermal and X-ray analysis and by measuring electroconductivity

Generation of Hybrid Peptide-Silver Nanoparticles for Antibacterial and Antifouling Applications

KAUST Repository

Seferji, Kholoud

2018-05-01

An alarming increase of antibiotic-resistant bacterial strains has made the demand for novel antibacterial agents, for example, more effective antibiotics, highly crucial. One of the oldest antimicrobial agents is elementary silver which has been used for thousands of years. Even in our days, elementary silver is used for medical purposes, such as for burns, wounds, and microbial infections. We have taken the effectiveness of elementary silver into consideration to generate novel antibacterial and antifouling agents. Our innovative antibacterial agents are hybrid peptide silver nanoparticles (CH-01-AgNPs) that are created de novo and in situ from a silver nitrate solution (AgNO3) in the presence of ultrashort self-assembling peptides compounds. The nucleation of CH-01-AgNPs is initiated by irradiating the peptide solution mixed with the AgNO3 solution using ultraviolet (UV) light at a wavelength of 254 nm, in the absence of any reducing or capping agents. Obviously, the peptide itself serves as the reducing agent. The ultrashort peptides are four amino acids in length with an innate ability to self-assemble into nanofibrous scaffolds. Using these ultrashort peptides CH-01 we were able to create hybrid peptide silver nanoparticles CH-01-AgNPs with a diameter of 4-6 nm. The synthesized CH-01-AgNPs were further characterized using ultraviolet-visible spectroscopy, transmission electron microscopy, dynamic light scattering, and X-ray photoelectron spectroscopy. The antibacterial and antifouling activity of CH-01-AgNPs were then investigated using either gram-negative bacteria, such as antibiotic-resistant Top10 Escherichia coli and Pseudomonas aeruginosa PDO300, or gram-positive bacteria, such as Staphylococcus aureus CECT 976. The hybrid nanoparticles demonstrated very promising antibacterial and antifouling activity with higher antibacterial and antifouling activity as commercial silver nanoparticles. Quantitative Polymerase Chain Reaction (qPCR) results showed

Evaluation of optimal silver amount for the removal of methyl iodide on silver-impregnated adsorbents

International Nuclear Information System (INIS)

Park, G.I.; Cho, I.H.; Kim, J.H.; Oh, W.Z.

2001-01-01

The adsorption characteristics of methyl iodide generated from the simulated off-gas stream on various adsorbents such as silver-impregnated zeolite (AgX), zeocarbon and activated carbon were investigated. An extensive evaluation was made on the optimal silver impregnation amount for the removal of methyl iodide at temperatures up to 300 deg. C. The degree of adsorption efficiency of methyl iodide on silver-impregnated adsorbent is strongly dependent on impregnation amount and process temperature. A quantitative comparison of adsorption efficiencies on three adsorbents in a fixed bed was investigated. The influence of temperature, methyl iodide concentration and silver impregnation amount on the adsorption efficiency is closely related to the pore characteristics of adsorbents. It shows that the effective impregnation ratio was about 10wt%, based on the degree of silver utilization for the removal of methyl iodide. The practical applicability of silver-impregnated zeolite for the removal of radioiodine generated from the DUPIC process was consequently proposed. (author)

Bulk diffusion and solubility of silver and nickel in lead, lead-silver and lead-nickel solid solutions

International Nuclear Information System (INIS)

Amenzou-Badrour, H.; Moya, G.; Bernardini, J.

1988-01-01

The results of a study of solubility and bulk diffusion of /sup 110/Ag and /sup 63/Ni in lead, lead-silver and lead-nickel solid solutions in the temperature range 220 to 88 0 C are reported. Owing to the low solubility of silver and nickel in lead, Fick's solution corresponding to the boundary condition of a constant concentration of solute at the surface has been used. Depth profile concentration analysis suggests a fundamental difference between the diffusion mechanisms of silver and nickel. Since silver penetration profiles in pure lead give diffusion coefficients independent of the penetration depth and silver concentration, it is suggested that slight decreases of silver diffusivity in lead-silver solid solutions have no significance. This implies that the interstitial silver atoms do not associate significantly with each other to form Ag-Ag dimers. In contrast, different behaviors of /sup 63/Ni depth profile concentration in pure lead and saturated PbNi solid solutions agree with a Ni-Ni interaction leading to the formation of less mobile dimers near the surface in pure lead

Silver surface enrichment of silver-copper alloys: a limitation for the analysis of ancient silver coins by surface techniques

International Nuclear Information System (INIS)

Beck, L.; Bosonnet, S.; Reveillon, S.; Eliot, D.; Pilon, F.

2004-01-01

The surface enrichment of archaeological silver-copper alloys has been recognized for many years. However, the origin of this enrichment is not well defined and many hypotheses have been put forward to account for this behaviour: segregation of the components during casting, deliberate thermal and/or chemical post-treatment, abrasion or corrosion. Among the hypotheses mentioned above, we have focused our study on the first step of coin manufacturing. Replications of silver-copper standards of various compositions ranging from 30% to 80% Ag, reflecting the composition of silver blanks, have been produced. Metallographic examination, PIXE and SEM-EDS have been used for the characterization of each sample. A model of the direct enrichment has been established. This model allows us to propose a relationship between the surface composition and the silver content of the core. Comparison with data of Roman coins from the Roman site of Cha-hat teaubleau (France) and from the literature and consequences for the analyses of ancient coins by surface methods are presented

Mineral resource of the month: silver

Science.gov (United States)

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.

Butea monosperma bark extract mediated green synthesis of silver nanoparticles: Characterization and biomedical applications

Directory of Open Access Journals (Sweden)

Sutanuka Pattanayak

2017-09-01

Full Text Available The work deals with an environmentally benign process for the synthesis of silver nanoparticle using Butea monosperma bark extract which is used both as a reducing as well as capping agent at room temperature. The reaction mixture turned brownish yellow after about 24 h and an intense surface plasmon resonance (SPR band at around 424 nm clearly indicates the formation of silver nanoparticles. Fourier transform-Infrared (FT-IR spectroscopy showed that the nanoparticles were capped with compounds present in the plant extract. Formation of crystalline fcc silver nanoparticles is analysed by XRD data and the SAED pattern obtained also confirms the crystalline behaviour of the Ag nanoparticles. The size and morphology of these nanoparticles were studied using High Resolution Transmission Electron Microscopy (HRTEM which showed that the nanoparticles had an average dimension of ∼35 nm. A larger DLS data of ∼98 nm shows the presence of the stabilizer on the nanoparticles surface. The bio-synthesized silver nanoparticles revealed potent antibacterial activity against human bacteria of both Gram types. In addition these biologically synthesized nanoparticles also proved to exhibit excellent cytotoxic effect on human myeloid leukemia cell line, KG-1A with IC50 value of 11.47 μg/mL.

Browse Title Index

African Journals Online (AJOL)

2004): Special Issue 2004, Differential production of immune parameters by mouse strains ... agglutination and complement fixation tests in the field diagnosis ... List All Titles · Free To Read Titles This Journal is Open Access.

In Vivo Toxicity of Silver Nanoparticles and Silver Ions in Zebrafish (Danio rerio

Directory of Open Access Journals (Sweden)

Katrine Bilberg

2012-01-01

Full Text Available The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP- coated silver nanoparticles (81 nm was investigated. NaCl solution series of 100–800 mg L−1 lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5–8 had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO3. The nanosilver and silver ion 48-hour median lethal concentration (LC50 values were 84 μg L−1 and 25 μg L−1, respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish.

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

Energy Technology Data Exchange (ETDEWEB)

Ferraris, S., E-mail: sara.ferraris@polito.it [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy); Miola, M. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy); Department of Health Sciences, Università del Piemonte Orientale UPO, Via Solaroli 17, 28100, Novara (Italy); Cochis, A.; Azzimonti, B.; Rimondini, L. [Department of Health Sciences, Università del Piemonte Orientale UPO, Via Solaroli 17, 28100, Novara (Italy); Prenesti, E. [Department of Chemistry, Università degli Studi di Torino, Via Pietro Giuria 7, Torino, 10125 (Italy); Vernè, E. [Department of Applied Science and Technology, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129, Torino (Italy)

2017-02-28

Highlights: • Gallic acid and natural polyphenols were grafted onto bioactive glasses. • Grafting ability was dependent on glass reactivity. • In situ reduction of silver nanoparticles was performed onto functionalized glasses. • Bioactive glasses decorated with silver nanoparticles showed antibacterial activity. - Abstract: 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.

Genetics Home Reference: Russell-Silver syndrome

Science.gov (United States)

... Other Names for This Condition RSS Silver-Russell dwarfism Silver-Russell syndrome SRS Related Information How are ... M, Begemann M, Elbracht M. Epigenetic and genetic diagnosis of Silver-Russell syndrome. Expert Rev Mol Diagn. ...

Nucleic acid nanomaterials: Silver-wired DNA

Science.gov (United States)

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.

Biological synthesis of silver nanoparticles

International Nuclear Information System (INIS)

Maliszewska, I; Szewczyk, K; Waszak, K

2009-01-01

Fungus-mediated synthesis of silver nanoparticles is reported. The nanosilver was formed in contact with the cell-free filtrate of Penicillium strain studied. The nanoparticles were characterized by means of the UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized nanosilver showed a absorbed maximum at 425 nm in the visible region. The SEM characterization of the fungus cells treated with silver nitrite indicated that the protein might be responsible for the reduction of silver ions. Transmission electron microscopy (TEM) micrograph showed formation of silver nanoparticles in the range of 10-100 nm.

Silver precipitation from electrolytic effluents

International Nuclear Information System (INIS)

Rivera, I.; Patino, F.; Cruells, M.; Roca, A.; Vinals, J.

2004-01-01

The recovery of silver contained in electrolytic effluents is attractive due to its high economic value. These effluents are considered toxic wastes and it is not possible to dump them directly without any detoxification process. One of the most important way for silver recovery is the precipitation with sodium ditionite, sodium borohidride or hydrazine monohidrate. In this work, the most significant aspects related to the use of these reagents is presented. Results of silver precipitation with sodium ditionite from effluents containing thiosulfate without previous elimination of other species are also presented. silver concentration in the final effluents w <1 ppm. (Author) 15 refs

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

Science.gov (United States)

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.

Silver doped metal layers for medical applications

International Nuclear Information System (INIS)

Kocourek, T; Jelínek, M; Mikšovský, J; Jurek, K; Weiserová, M

2014-01-01

Biological, physical and mechanical properties of silver-doped layers of titanium alloy Ti6Al4V and 316L steel prepared by pulsed laser deposition were studied. Metallic silver-doped coatings could be a new route for antibacterial protection in medicine. Thin films of silver and silver-doped materials were synthesized using KrF excimer laser deposition. The materials were ablated from two targets, which were composed either from titanium alloy with silver segments or from steel with silver segments. The concentration of silver ranged from 1.54 at% to 4.32 at% for steel and from 3.04 at% to 13.05 at% for titanium alloy. The layer properties such as silver content, structure, adhesion, surface wettability, and antibacterial efficacy (evaluated by Escherichia coli and Bacillus subtilis bacteria) were measured. Film adhesion was studied using scratch test. The antibacterial efficacy changed with silver doping up to 99.9 %. Our investigation was focused on minimum Ag concentration needed to reach high antibacterial efficiency, high film adhesion, and hardness.

Silver-doped metal layers for medical applications

International Nuclear Information System (INIS)

Kocourek, T; Jelínek, M; Mikšovský, J; Jurek, K; Weiserová, M

2014-01-01

Biological, physical and mechanical properties of silver-doped layers of titanium alloy Ti6Al4V and 316 L steel prepared by pulsed laser deposition were studied. Metallic silver-doped coatings could be a new route for antibacterial protection in medicine. Thin films of silver and silver-doped materials were synthesized using KrF excimer laser deposition. The materials were ablated from two targets, which were composed either from titanium alloy with silver segments or from steel with silver segments. The concentration of silver ranged from 1.54 to 4.32 at% for steel and from 3.04 to 13.05 at% for titanium alloy. The layer properties such as silver content, structure, adhesion, surface wettability, and antibacterial efficiency (evaluated by Escherichia coli and Bacillus subtilis bacteria) were measured. Film adhesion was studied using a scratch test. The antibacterial efficiency changed with silver doping up to 99.9 %. Our investigation was focused on the minimum Ag concentration needed to reach high antibacterial efficiency, high film adhesion, and hardness. (paper)

Polypyrrole-silver Nanocomposite: Synthesis and Characterization

OpenAIRE

D. M. Nerkar; S. V. Panse; S. P. Patil; S. E. Jaware; G. G. Padhye

2016-01-01

Polypyrrole-Silver (PPy-Ag) nanocomposite has been successfully synthesized by the chemical oxidative polymerization of pyrrole with iron (III) chloride as an oxidant, in the presence of a colloidal suspension of silver nanoparticles. Turkevich method (Citrate reduction method) was used for the synthesis of silver nanoparticles (Ag NPs). The silver nanoparticles were characterized by UV-Visible spectroscopy which showed an absorption band at 423 nm confirming the formation of nanoparticles. P...

Impact of silver ions and silver nanoparticles on the plant growth and soil microorganisms

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D. Tomacheski

2017-12-01

Full Text Available There is a growing consumer market for products that proclaim to decrease microorganism counts to prevent infections. Most of these products are loaded with silver in its ionic or nanoparticle form. Through use or during production, these particles can find their way into the soil and cause an impact in microbial and plant communities. This study aims to evaluate the impact of silver based particles in Avena byzantina (oat, Lactuca sativa (lettuce and Raphanus sativus (radish development and in the soil microorganism abundance. Oat, lettuce and radish plants were cultivated in soil contaminated with particles of bentonite organomodified with silver (Ag+_bentonite, silver phosphate glass (Ag+_phosphate and silver nanoparticles adsorbed on fumed silica (AgNp_silica. Plant development and microorganisms’ abundance were evaluated. To some degree, Ag+_bentonite impacted plants development and AgNp_silica causes an adverse effect on microbial abundance. The impact on plants and microorganisms was contradictory and varied according to soil and particles physicochemical characteristics.

Conductive Adhesive Based on Mussel-Inspired Graphene Decoration with Silver Nanoparticles.

Science.gov (United States)

Casa, Marcello; Sarno, Maria; Liguori, Rosalba; Cirillo, Claudia; Rubino, Alfredo; Bezzeccheri, Emanuele; Liu, Johan; Ciambelli, Paolo

2018-02-01

Decoration with silver nanoparticles was obtained by coating graphene with a polydopamine layer, able to induce spontaneous metallic nanoparticles formation without any specific chemical interfacial modifier, neither using complex instrumentation. The choice of dopamine was inspired by the composition of adhesive proteins in mussels, related to their robust attach to solid surfaces. The synthesis procedure started from graphite and involved eco-friendly compounds, such as Vitamin C and glucose as reducing agent and water as reaction medium. Silver decorated graphene was inserted as secondary nanofiller in the formulation of a reference conductive adhesive based on epoxy resin and silver flakes. A wide characterization of the intermediate materials obtained along the step procedure for the adhesive preparation was carried out by several techniques. We have found that the presence of nanofiller yields, in addition to an improvement of the thermal conductivity (up to 7.6 W/m · K), a dramatic enhancement of the electrical conductivity of the adhesive. In particular, starting from 3 · 102 S/cm of the reference adhesive, we obtained a value of 4 · 104 S/cm at a nanofiller concentration of 11.5 wt%. The combined double filler conductivity was evaluated by Zallen's model. The effect of the temperature on the resistivity of the adhesive has been also studied.

Application of the atomic absorption technical to available the concentration of silver ions incorporated in glass matrix by ionic exchange process

International Nuclear Information System (INIS)

Mendes, E.; Silva, K.F.; Teixeira, A.; Silva, L.; Paula, M.M.S.; Angioletto, E.; Riella, H.G.; Fiori, M. A.

2009-01-01

Ion specimens can be incorporated in glasses or natural clays by ionic exchange process with different concentrations dependent of matrix's type and of the ionic exchange parameters. In particular, the incorporation of silver ions presents high interest by its biocidal properties. A compound contending ion silver specimens presents bactericidal and fungicidal properties with effect proportional to ion concentration. This work presents results about application of the atomic absorption technical to determine the silver ion concentration incorporated in a glass matrix by ionic exchange process. The ionic exchange experiments were realized with different AgNO 3 concentration and constant temperature. After ionic exchange process, the glass samples were submitted to characterization by Energy Dispersive X-Ray Spectroscopy and Atomic Absorption Techniques. The comparative results between different techniques showed that atomic absorption technical is adequate to determine ion silver concentration incorporated in the glass matrix after ionic exchange process. (author)

Silver powder effectiveness and mechanism of silver paste on silicon solar cells

International Nuclear Information System (INIS)

Tsai, Jung-Ting; Lin, Shun-Tian

2013-01-01

Highlights: ► Optimizing the silver paste in 80–85 wt.%. ► Optimizing its particle size in 1–1.5 μm spherical powder. ► The sheet resistance is 4 mΩ/sq during the 860 °C sintering process. ► Redox reaction cause Ag crystallites to grow on the interface. ► A thin layer of silicon oxide (75–150 nm) was formed. - Abstract: Since the silver paste plays a major role in the mass production of silicon solar cells, this work has succeeded in optimizing the silver paste in 80–85 wt.% and optimizing its particle size in 1–1.5 μm spherical powder. As the firing temperature is increased, the growth trend of silver grain is improved. The result of this work has showed that the lowest sheet resistance is 4 mΩ/sq during the 860 °C sintering process. The scanning electron microscope (SEM) observation has showed that the formation of silver oxide is formed during the melting process of glass and triggered redox reaction of Ag crystallites to grow on the interface. It has proven by transmission electron microscope (TEM) that a thin layer of silicon oxide (75–150 nm) was formed, respectively.

Raspberry Extract as Both a Stabilizer and a Reducing Agent in Environmentally Friendly Process of Receiving Colloidal Silver

Directory of Open Access Journals (Sweden)

Jolanta Pulit

2013-01-01

Full Text Available An ecofriendly method of nanosilver obtaining has been studied. The process involves the chemical reduction method carried out in aqueous environment. Silver nitrate (V was applied as a silver ions source. Raspberry extract was used as a natural source of both reducing and stabilizing agents. The total amount of phenolic compounds was determined by the Folin-Ciocalteu method. Obtained nanoparticles were analyzed by the dynamic light scattering technique so as to determine the particles size and suspension stability which was characterized by an electrokinetic potential. The results confirmed that the size of some nanoparticles was under 100 nm.

INIS: Authority List for Journal Titles

International Nuclear Information System (INIS)

1992-01-01

This is the nineteenth revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). It lists 10,797 journal titles which have contained articles within the scope of INIS. The purpose of this Authority List is to provide descriptive cataloguers with a standard abbreviation for journal titles and to assist users of INIS products with a tool for verifying the full title of a journal. A journal, or periodical, is generally published within a defined, fixed interval between issues, which usually has more than one issue a year, and which usually includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as Annual Review of Nuclear Science are included. Series titles as, for example the McGraw-Hill Series in Nuclear Engineering, are not included in this Authority. Entries: Each entry consists of: - the full journal title (highlighted); - the abbreviated title; - ISSN, if available; - CODEN, if available; - additional information related to the journal title. Arrangement: In Part I, the full journal titles are grouped by country or international organization name and ordered alphabetically, followed by the ISSN, the CODEN in square brackets if available, and then the abbreviated title. The abbreviated title is based on the rules of ISO 4: Documentation - International Code for the Abbreviation of Titles of Periodicals. The abbreviations of the words are taken from the ISDS List of Periodical Title Word Abbreviation. In Part II, the order of the citations is reversed: the abbreviated journal titles are arranged alphabetically, followed by country code. Then the full journal titles are followed by the country of publication, and if available, ISSN and CODEN. Additional Information: There is important information related to the journal titles which are fundamental for tracing the history of the title and the present status. They are listed below and are entered whenever applicable: - Ceased publication; - Superseded by

Effets of Silver Salt Concentrations on Green Synthesis of Silver Nanoparticles Using the Plant Nigella Saliva

Directory of Open Access Journals (Sweden)

M.R. Saeri

2016-03-01

Full Text Available Bio-inspired silver nanoparticles were synthesized with the aid of a novel method, using leaves of the plant Nigella sativa. After drying the leaves in air, they were first sweltered in boiling distilled water and the liquid was filtered subsequently. The result was the brothused to reduce solutions including various concentrations of silver nitrate in a proper amount of pH. The displayed UV–visible spectra identified formation of silver nanoparticles whenever the colorless initial acclimated mixture turned brown. The centrifuged powder samples were examined using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, scanning electron microscopy (FESEM and energy dispersive X-ray diffraction analysis (EDX methods. The results clearly revealed that the final particles of precipitated powder are high purity agglomerates of silver nanoparticles. Besides, the effects of various amounts of the silver salt on particle size of nano silver were studied, using a particle size analyzer. FTIR results also indicated the role of different functional groups in the synthetic process.

Title IX Resource Guide

Science.gov (United States)

Office for Civil Rights, US Department of Education, 2015

2015-01-01

Title IX of the Education Amendments of 1972 (Title IX) prohibits discrimination based on sex in education programs and activities in federally funded schools at all levels. If any part of a school district or college receives any Federal funds for any purpose, all of the operations of the district or college are covered by Title IX. The essence…

Getting to one from title 10 + title 32 unity of effort in the homeland

OpenAIRE

Prosch, Caroline Ross.

2011-01-01

CHDS State/Local Approved for public release; distribution is unlimited This thesis bridges the knowledge gap between Title 10 Active Duty and Title 32 National Guard in order to breakdown cultural barriers and reach unity of effort for response operations in the homeland. Regrettably, a unified response was missing among Title 10 Active Duty and Title 32 National Guard members following Hurricane Katrina. Since then, initiatives based in doctrine, statutes and formal recommendations...

Synthesis and characterization of monodispersed silver nanoparticles

Science.gov (United States)

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).

Synthesis and characterization of monodispersed silver nanoparticles

International Nuclear Information System (INIS)

Christy, A Jegatha; Umadevi, M

2012-01-01

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 (AgNO 3 ), 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). (paper)

Browse Title Index

African Journals Online (AJOL)

Items 601 - 650 of 788 ... Browse Title Index ... Issue, Title ... Vol 14, No 1 (2006), Social science research: a critique of quantitative and qualitative methods ... Vol 18, No 1 (2010), Stress among part-time business students: a study in a Ghanaian ...

Catalytic effects of silver plasmonic nanoparticles on the redox reaction leading to ABTS˙+ formation studied using UV-visible and Raman spectroscopy.

Science.gov (United States)

Garcia-Leis, A; Jancura, D; Antalik, M; Garcia-Ramos, J V; Sanchez-Cortes, S; Jurasekova, Z

2016-09-29

ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a compound extensively employed to evaluate the free radical trapping capacity of antioxidant agents and complex mixtures such as biological fluids or foods. This evaluation is usually performed by using a colourimetric experiment, where preformed ABTS radical cation (ABTS˙ + ) molecules are reduced in the presence of an antioxidant causing an intensity decrease of the specific ABTS˙ + UV-visible absorption bands. In this work we report a strong effect of silver plasmonic nanoparticles (Ag NPs) on ABTS leading to the formation of ABTS˙ + . The reaction of ABTS with Ag NPs has been found to be dependent on the interfacial and plasmonic properties of NPs. Specifically, this reaction is pronounced in the presence of spherical nanoparticles prepared by the reduction of silver nitrate with hydroxylamine (AgH) and in the case of star-shaped silver nanoparticles (AgNS). On the other hand, spherical nanoparticles prepared by the reduction of silver nitrate with citrate apparently do not react with ABTS. Additionally, the formation of ABTS˙ + is investigated by surface-enhanced Raman scattering (SERS) and the assignment of the most intense vibrational bands of this compound is performed. The SERS technique enables us to detect this radical cation at very low concentrations of ABTS (∼2 μM). Altogether, these findings allow us to suggest the use of ABTS/Ag NPs-systems as reliable and easy going substrates to test the antioxidant capacity of various compounds, even at concentrations much lower than those usually used in the spectrophotometric assays. Moreover, we have suggested that ABTS could be employed as a suitable agent to investigate the interfacial and plasmonic properties of the metal nanoparticles and, thus, to characterize the nanoparticle metal systems employed for various purposes.

20 CFR 408.931 - How much will we withhold from your title II and title XVI benefits to recover a title VIII...

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title II... and Overpayments Adjustment of Title II Benefits § 408.931 How much will we withhold from your title...-due benefits. (b)(1) We will collect the overpayment from current monthly benefits due in a month...

Technology transfer and application of SERS continuous monitor for trace organic compounds

International Nuclear Information System (INIS)

Swindle, D.W. Jr.; Vo-Dinh, T.; Yalcintas, M.G.

1992-01-01

An in situ-enhanced Raman Scattering (SERS) continuous monitoring system was developed for exciting and collecting SERS signals generated on silver-coated microparticles deposited on a continuously rotating filter-paper support. SERS measurements were successfully conducted for several organic compounds. An in situ SERS fiber-optic system was also developed for exciting and collecting SERS signals generated from a sensing tip having silver-coated microparticles deposited on a glass-plate support. These devices will be very useful in remote identification of unknown chemicals from hazardous waste sites. This patented technology has been licensed from Oak Ridge National Laboratory to an analytical instrumentation firm which is in the process of completing development and marketing these detectors. Advantages to using this technology range from increased safety and sensitivity for detecting hazardous compounds to better statistics and reliable results. During this presentation, efforts of the Environmental Restoration Program to evaluate and support development of this technology will be described

Browse Title Index

African Journals Online (AJOL)

Items 151 - 200 of 229 ... Browse Title Index ... Issue, Title. Vol 14, No 2 ... Vol 15, No 1 (2017), Qualitative and quantitative methods of suicide research in old age, Abstract PDF ... Vol 11, No 2 (2013), Simple Algorithm in the Management of Fetal ...

The Use of Silver Solid Amalgam Electrodes for Voltammetric and Amperometric Determination of Nitrated Polyaromatic Compounds Used as Markers of Incomplete Combustion

Directory of Open Access Journals (Sweden)

Oksana Yosypchuk

2012-01-01

Full Text Available Genotoxic nitrated polycyclic aromatic hydrocarbons (NPAHs are formed during incomplete combustion processes by reaction of polycyclic aromatic hydrocarbons (PAHs with atmospheric nitrogen oxides. 1-Nitropyrene, 2-nitrofluorene, and 3-nitrofluoranthene as the dominating substances are used as markers of NPAHs formation by these processes. In the presented study, voltammetric properties and quantification of these compounds and of 5-nitroquinoline (as a representative of environmentally important genotoxic heterocyclic compounds have been investigated using a mercury meniscus modified silver solid amalgam electrode (m-AgSAE, which represent a nontoxic alternative to traditional mercury electrodes. Linear calibration curves over three orders of magnitude and limits of determination mostly in the 10−7 mol L−1 concentration range were obtained using direct current and differential pulse voltammetry. Further, satisfactory HPLC separation of studied analytes in fifteen minutes was achieved using 0.01 mol L−1 phosphate buffer, pH 7.0 : methanol (15 : 85, v/v mobile phase, and C18 reversed stationary phase. Limits of detection of around 1 · 10−5 mol L−1 were achieved using amperometric detection at m-AgSAE in wall-jet arrangement for all studied analytes. Practical applicability of this technique was demonstrated on the determination of 1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene, and 5-nitroquinoline in drinking water after their preliminary separation and preconcentration using solid phase extraction with the limits of detection around 1 · 10−6 mol L−1.

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

Directory of Open Access Journals (Sweden)

Kuppan Gokulan

2017-04-01

Full Text Available 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.

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

Science.gov (United States)

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 .

Light insensitive silver(I) cyanoximates as antimicrobial agents for indwelling medical devices.

Science.gov (United States)

Gerasimchuk, Nikolay; Gamian, Andrzej; Glover, Garrett; Szponar, Bogumila

2010-11-01

Ten silver(I) cyanoximates of AgL composition (L = NC-C(NO)-R, where R is electron withdrawing groups: -CN, -C(O)NR(2), -C(O)R' (alkyl), -C(O)OEt, 2-heteroaryl fragments such as 2-pyridyl, 2-benzimidazolyl, 2-benzoxazolyl, 2-benzthiazolyl) were synthesized and characterized using spectroscopic methods and X-ray analysis. Crystal structures of four complexes were determined and revealed the formation of two-dimensional (2D) coordination polymers of different complexity in which anions exhibit bridging or combined chelate and bridging binding modes. In these compounds, anions are in the nitroso form. All studied AgL complexes are sparingly soluble in water and are thermally stable to 150 °C. Synthesized compounds demonstrated remarkable insensitivity toward visible light and UV-radiation, which was explained based on their polymeric structures with multiple covalent bonds between bridging cyanoxime ligands and Ag(I) centers. All 10 silver(I) cyanoximates were tested in vitro on the subject of their antimicrobial activity against both Gram-positive and Gram-negative microorganisms such as Escherichia coli, Klebsiella pneumoniae, Proteus sp., Pseudomonas aeruginosa, Enterococcus hirae, Streptococcus mutans, Staphylococcus aureus, and Mycobacterium fortuitum as well as against Candida albicans in solutions, and in the solid state as pressed pellets and dried filter paper disks presoaked with solutions of AgL in DMF. Results showed pronounced antimicrobial activity for all investigated complexes. A combination of five factors: (1) light insensitivity, (2) poor water solubility, (3) high thermal stability, (4) lack of toxicity of organic ligands, and (5) in vitro antimicrobial activity allows development of silver(I) cyanoximates for medical applications. These include antimicrobial additives to acrylate glue, cured by UV-radiation, used in introduction of prosthetic joints and dental implants, and prevention of biofilm formation on several types of indwelling medical

Silver as antibacterial towards Listeria monocytogenes

Directory of Open Access Journals (Sweden)

Simone eBelluco

2016-03-01

Full Text Available Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs or silver nitrate (AgNO3. Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action.

Silver(i) complexes with 1'-(diphenylphosphino)-1-cyanoferrocene: the art of improvisation in coordination.

Science.gov (United States)

Škoch, Karel; Uhlík, Filip; Císařová, Ivana; Štěpnička, Petr

2016-06-28

1'-(Diphenylphosphino)-1-cyanoferrocene () reacts with silver(i) halides at a 1 : 1 metal-to-ligand ratio to afford the heterocubane complexes [Ag(μ3-X)(-κP)]4, where X = Cl (), Br (), and I (). In addition, the reaction with AgCl with 2 equiv. of leads to chloride-bridged dimer [(μ-Cl)2{Ag(-κP)2}2] () and, presumably, also to [(μ(P,N)-){AgCl(-κP)}]2 (). While similar reactions with AgCN furnished only the insoluble coordination polymer [(-κP)2Ag(NC)Ag(CN)]n (), those with AgSCN afforded the heterocubane [Ag(-κP)(μ-SCN-S,S,N)]4 () and the thiocyanato-bridged disilver(i) complex [Ag(-κP)2(μ-SCN-S,N)]2 (), thereby resembling reactions in the AgCl- system. Attempted reactions with AgF led to ill-defined products, among which [Ag(-κP)2(μ-HF2)]2 () and [(μ-SiF6){Ag(-κP)2}2] () could be identified. The latter compound was prepared also from Ag2[SiF6] and . Reactions between and AgClO4 or Ag[BF4] afforded disilver complexes [(μ(P,N)-)Ag(ClO4-κO)]2 () and [(μ(P,N)-)Ag(BF4-κF)]2 () featuring pseudolinear Ag(i) centers that are weakly coordinated by the counter anions. A similar reaction with Ag[SbF6] followed by crystallization from ethyl acetate produced an analogous complex, albeit with coordinated solvent, [(μ(P,N)-)Ag(AcOEt-κO)]2[SbF6]2 (). Ultimately, a compound devoid of any additional ligands at the Ag(i) centers, [(μ(P,N)-)Ag]2[B(C6H3(CF3)2-3,5)4]2 (), was obtained from the reaction of with silver(i) tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. The reaction of Ag[BF4] with two equivalents of produced unique coordination polymer [Ag(-κP)(μ(P,N)-)]n[BF4]n (), the structure of which contained one of the phosphinoferrocene ligands coordinated as a P,N-chelate and the other forming a bridge to an adjacent Ag(i) center. All of these compounds were structurally characterized by single-crystal X-ray crystallography, revealing that the lengths of the bonds between silver and its anionic ligand(s) typically exceed the sum of the respective

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

International Nuclear Information System (INIS)

Shams, Gholamabbas; Ranjbar, Morteza; Amiri, Aliasghar

2013-01-01

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.

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

Energy Technology Data Exchange (ETDEWEB)

Shams, Gholamabbas, E-mail: ghs@iaushiraz.net; Ranjbar, Morteza [Shiraz Branch, Islamic Azad University, Department of Physics (Iran, Islamic Republic of); Amiri, Aliasghar [Shiraz Branch, Islamic Azad University, Department of Chemistry (Iran, Islamic Republic of)

2013-05-15

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.

N-heterocyclic carbene complexes of silver and gold as novel tools against breast cancer progression.

Science.gov (United States)

Saturnino, Carmela; Barone, Ines; Iacopetta, Domenico; Mariconda, Annaluisa; Sinicropi, Maria Stefania; Rosano, Camillo; Campana, Antonella; Catalano, Stefania; Longo, Pasquale; Andò, Sebastiano

2016-12-01

Metal carbenic complexes have received considerable attention in both the catalysis and biological fields for their potential applications in cancer and antimicrobial therapies. A small series of new silver and gold N-heterocyclic carbene complexes has been designed and synthesized. Among the tested complexes, one compound was particularly active in inhibiting anchorage-dependent and -independent breast cancer proliferation, and inducing cell apoptosis via a mitochondria-related process. The antitumor activity was associated to the transcriptional activation of the tumor suppressor gene p53 in an Sp1-dependent manner, as evidenced by biological and docking studies. Our results highlight the importance and the versatility of N-heterocyclic carbene complexes of gold and silver as useful tools against breast cancer progression.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Hanley, Traci A.; Saadawi, Ryan; Zhang, Peng; Caruso, Joseph A., E-mail: joseph.caruso@uc.edu; 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{sup +}) 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{sup −1} detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100 nm.

INIS: Authority list for journal titles

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-03-01

This is the twenty-ninth revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). It lists the titles of 12 990 journals which have contained articles within the scope of INIS. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the reader to find titles easily, the list is divided into two parts. In Part I, the full journal titles are grouped by country or international organization responsible for coverage and ordered alphabetically. In Part II, the full journal titles of all countries or international organizations are arranged alphabetically. The country name or the international organization name responsible for coverage of the journal title to INIS is entered in parentheses. Journal titles marked with an asterisk are regularly scanned by INIS. Titles that have been identified by INIS Centres as 'Key Journals' are marked with the hash sign.

INIS: Authority list for journal titles

International Nuclear Information System (INIS)

2003-01-01

This is the twenty-ninth revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). It lists the titles of 12 990 journals which have contained articles within the scope of INIS. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the reader to find titles easily, the list is divided into two parts. In Part I, the full journal titles are grouped by country or international organization responsible for coverage and ordered alphabetically. In Part II, the full journal titles of all countries or international organizations are arranged alphabetically. The country name or the international organization name responsible for coverage of the journal title to INIS is entered in parentheses. Journal titles marked with an asterisk are regularly scanned by INIS. Titles that have been identified by INIS Centres as 'Key Journals' are marked with the hash sign

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

Science.gov (United States)

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.

Influence of Thermal Treatment on the Antimicrobial Activity of Silver-Doped Biological Apatite

Science.gov (United States)

Popa, Cristina Liana; Ciobanu, Carmen Steluta; Voicu, Georgeta; Vasile, Eugenia; Chifiriuc, Mariana Carmen; Iconaru, Simona Liliana; Predoi, Daniela

2015-12-01

In this paper, we report the structural and morphological properties of silver-doped hydroxyapatite (AgHAp) with a silver concentration x Ag = 0.5 before and after being thermal treated at 600 and 1000 °C. The results obtained by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy suggest that the structure of the samples changes gradually, from hydroxyapatite (AgHAp_40) to a predominant β-TCP structure (AgHAp_1000), achieved when the thermal treatment temperature is 1000 °C. In the AgHAp_600 sample, the presence of two phases, HAp and β-TCP, was highlighted. Also, scanning electron microscopy studies suggest that the shape and dimension of the nanoparticles begin to change when the temperature increases. The antimicrobial activity of the obtained compounds was evaluated against Klebsiella pneumoniae, Staphylococcus aureus, and Candida albicans strains.

A high-temperature, high-pressure, silver-silver chloride reference electrode

International Nuclear Information System (INIS)

King, F.; Bailey, M.G.; Clarke, C.F.; Ikeda, B.M.; Litke, C.D.; Ryan, S.R.

1989-05-01

A high-temperature, high-pressure, silver-silver chloride reference electrode is described. This report is meant to serve as a user's guide to the experimentalist. Consequently, the design and construction of the electrode are dealt with in some detail. The problems that may be encountered, along with their possible causes and remedies, are also discussed. Conversion factors are given for both internal and external reference electrodes, so that measured potentials can be related to the standard hydrogen electrode scale

SR-XRD and SR-FTIR study of the alteration of silver foils in medieval paintings.

Science.gov (United States)

Salvadó, Nati; Butí, Salvador; Labrador, Ana; Cinque, Gianfelice; Emerich, Hermann; Pradell, Trinitat

2011-03-01

Altarpieces and polychrome carved wood from the fifteenth century AD usually exhibit golden and silvery areas by the application of a very thin foil of metal. The metal foils were normally protected from the atmosphere by a varnish or resin which maybe either preserved or absent. Moreover, they were glued to the background surface by adhesive substances (egg yolk, drying oil or animal glue). The high proportion of the glueing substances often renders the development of reaction compounds. With time, silver alters blacken or simply disappear completely. In this paper, we study the alterations to metal foils from a selection of fifteenth century artworks showing different glueing agents, organic coatings and several degrees of conservation of the organic coatings and metal leafs. The submillimetric layered structure and the high variability and low amount of most of the compounds present in the different layers, as well as their differing nature (organic and inorganic) make the use of micron-sensitive high-resolution techniques essential for their study. In particular, the high resolution, high brilliance and small footprint renders synchrotron radiation most adequate for their study. SR-XRD was performed to identify the reaction compounds formed in the different layers; μFTIR was used at to identify the silver protecting organic coatings, the metal foil glueing layers and the corresponding reaction compounds. The results obtained suggest that atmospheric corrosion is the dominant mechanism, and therefore that the degree of corrosion of the metal foils is mainly related to the conservation state of the protecting coatings.

Preparation of silver nanoparticles at low temperature

Energy Technology Data Exchange (ETDEWEB)

Mishra, Mini, E-mail: mishramini5@gmail.com [Centre of Environmental Science, Department of Botany, University of Allahabad, Allahabad, U.P. (India); Chauhan, Pratima, E-mail: mangu167@yahoo.co.in [Department of Physics, University of Allahabad, Allahabad U.P. (India)

2016-04-13

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 peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

Preparation of silver nanoparticles at low temperature

International Nuclear Information System (INIS)

Mishra, Mini; Chauhan, Pratima

2016-01-01

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 peaks of silver and oxygen. Water absorbed by silver nanoparticles was removed by the calcinations.

Additive interaction of carbon dots extracted from soluble coffee and biogenic silver nanoparticles against bacteria

International Nuclear Information System (INIS)

Andrade, Patricia F.; Durán, Nelson; Nakazato, Gerson

2017-01-01

It is known the presence of carbon dots (CDs) in carbohydrate based foods. CDs extracted from coffee grounds and instant coffee was also published. CDs from soluble coffee revealed an average size of 4.4 nm. CDs were well-dispersed in water, fluorescent and we have characterized by XPS, XRD analysis, fluorescence and by FTIR spectra. The MIC value by serial micro-dilution assays for CDs on S. aureus ATCC 25923 was 250 μg/mL and E. coli ATCC 25922 >1000 ug/mL. For silver nanoparticles biogenically synthesized was 6.7 μg/mL. Following the checkerboard assay with combining ½ MIC values of the MICs of 125 μg/mL of carbon dots and 3.4 μg/mL of silver nanoparticles, following the fractionated inhibitory concentration (FIC) index methodology, on S. aureus gave a fractionated inhibitory concentration (FIC) value of 1.0, meaning additive interaction. In general, the unfunctionalized CDs showed to be inefficient as antibacterial compounds, however the CDs extracted from Coffee powder and together silver nanoparticles appeared interesting as antibacterial association. (paper)

Toxicological Assessment of a Lignin Core Nanoparticle Doped with Silver as an Alternative to Conventional Silver Core Nanoparticles

Directory of Open Access Journals (Sweden)

Cassandra E. Nix

2018-05-01

Full Text Available Elevated levels of silver in the environment are anticipated with an increase in silver nanoparticle (AgNP production and use in consumer products. To potentially reduce the burden of silver ion release from conventional solid core AgNPs, a lignin-core particle doped with silver ions and surface-stabilized with a polycationic electrolyte layer was engineered. Our objective was to determine whether any of the formulation components elicit toxicological responses using embryonic zebrafish. Ionic silver and free surface stabilizer were the most toxic constituents, although when associated separately or together with the lignin core particles, the toxicity of the formulations decreased significantly. The overall toxicity of lignin formulations containing silver was similar to other studies on a silver mass basis, and led to a significantly higher prevalence of uninflated swim bladder and yolk sac edema. Comparative analysis of dialyzed samples which had leached their loosely bound Ag+, showed a significant increase in mortality immediately after dialysis, in addition to eliciting significant increases in types of sublethal responses relative to the freshly prepared non-dialyzed samples. ICP-OES/MS analysis indicated that silver ion release from the particle into solution was continuous, and the rate of release differed when the surface stabilizer was not present. Overall, our study indicates that the lignin core is an effective alternative to conventional solid core AgNPs for potentially reducing the burden of silver released into the environment from a variety of consumer products.

Use of bioreporters and deletion mutants reveals ionic silver and ROS to be equally important in silver nanotoxicity.

Science.gov (United States)

Joshi, Nimisha; Ngwenya, Bryne T; Butler, Ian B; French, Chris E

2015-04-28

The mechanism of antibacterial action of silver nanoparticles (AgNp) was investigated by employing a combination of microbiology and geochemical approaches to contribute to the realistic assessment of nanotoxicity. Our studies showed that suspending AgNp in media with different levels of chloride relevant to environmental conditions produced low levels of ionic silver thereby suggesting that dissolution of silver ions from nanoparticulate surface could not be the sole mechanism of toxicity. An Escherichia coli based bioreporter strain responsive to silver ions together with mutant strains of E. coli lacking specific protective systems were tested against AgNp. Deletion mutants lacking silver ion efflux systems and resistance mechanisms against oxidative stress showed an increased sensitivity to AgNp. However, the bioreporter did not respond to silver nanoparticles. Our results suggest that oxidative stress is a major toxicity mechanism and that this is at least partially associated with ionic silver, but that bulk dissolution of silver into the medium is not sufficient to account for the observed effects. Chloride ions do not appear to offer significant protection, indicating that chloride in receiving waters will not necessarily protect environmental bacteria from the toxic effects of nanoparticles in effluents. Copyright © 2015 Elsevier B.V. All rights reserved.

Aligned Layers of Silver Nano-Fibers

Directory of Open Access Journals (Sweden)

Andrii B. Golovin

2012-02-01

Full Text Available 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.

Bioactive Phytochemicals: Bioactivity, Sources, Preparations, and/or Modifications via Silver Tetrafluoroborate Mediation

Directory of Open Access Journals (Sweden)

Matthew C. Achilonu

2015-01-01

Full Text Available This review provides an overview of the biological activities, natural occurrences, and the silver tetrafluoroborate- (AgBF4- mediated synthesis of proanthocyanidins, glycosides, N-heterocyclic alkaloid analogues (of pyrrole, morphine, quinoline, isoquinoline, and indole, furan analogues, and halocompounds. AgBF4 has been reviewed as an effective reaction promoter, used extensively in the synthesis of relevant biologically active compounds via carbon-carbon and carbon-heteroatom bonds formation. The literatures from 1979 to April 2014 were reviewed.

Multiple surface plasmon polaritons modes on thin silver film controlled by a two-dimensional lattice of silver nanodimers

Energy Technology Data Exchange (ETDEWEB)

Chang, Ying; Jiang, Yongyuan, E-mail: jiangyy@hit.edu.cn [Harbin Institute of Technology, Department of Physics (China)

2015-01-15

We study the optical resonant spectrum of a two-dimensional periodic array of silver nanodimers on a thin silver film using multiple scattering formalism. The excited multiple plasmonic modes on two interfaces of the silver film reveal that the dispersion relationships of surface plasmon polaritons on metallic film are modified by doubly periodic lattice due to the fact that wave vectors matching conditions are satisfied. Moreover, we demonstrate that the plasmonic modes are directly controlled by the thickness of silver film, as well as the gap between nanodimer array and silver film. These effects provide novel high-efficient and steady way for excitation in future plasmonic nanodevices.

Ink composition for making a conductive silver structure

Science.gov (United States)

Walker, Steven B.; Lewis, Jennifer A.

2016-10-18

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 the 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.

Browse Title Index

African Journals Online (AJOL)

Items 201 - 250 of 488 ... African Journal of Paediatric Surgery. ... Ileocecal valve atresia: Introduction of a new surgical approach ... Vol 4, No 1 (2007), Isolated Bilateral Macrostomia: Case Series and ... Vol 9, No 2 (2012), Laparoscopic inguinal hernia repair in ... List All Titles · Free To Read Titles This Journal is Open Access.

Diameter-dependent coloration of silver nanowires

International Nuclear Information System (INIS)

Stewart, Mindy S; Qiu Chao; Jiang Chaoyang; Kattumenu, Ramesh; Singamaneni, Srikanth

2011-01-01

Silver nanowires were synthesized with a green method and characterized with microscopic and diffractometric methods. The correlation between the colors of the nanowires deposited on a solid substrate and their diameters was explored. Silver nanowires that appear similar in color in the optical micrographs have very similar diameters as determined by atomic force microscopy. We have summarized the diameter-dependent coloration for these silver nanowires. An optical interference model was applied to explain such correlation. In addition, microreflectance spectra were obtained from individual nanowires and the observed spectra can be explained with the optical interference theory. This work provides a cheap, quick and simple screening method for studying the diameter distribution of silver nanowires, as well as the diameter variations of individual silver nanowires, without complicated sample preparation.

Silver halide sensitized gelatin process effects in holographic lenses recorded on Slavich PFG-01 plates

Science.gov (United States)

Collados, Maria Victoria; Arias, Isabel; García, Ana; Atencia, Jesús; Quintanilla, Manuel

2003-02-01

In this work we study the feasibility of using silver halide sensitized gelatin based on PFG-01 (Slavich) emulsions to construct uniaxial compound lenses. This processing is able to introduce variations in the thickness and refractive index of the emulsion. We prove that these changes are not sufficient to provide the observed variations in Bragg conditions in the reconstruction and that a shear-type effect must exist to explain the performance of processed emulsions. We study the characteristics of a compound lens, obtaining acceptable image quality, good resolution, and the typical field limitation of volume holographic elements.

Synthesis and antimicrobial effects of silver nanoparticles

Directory of Open Access Journals (Sweden)

S kheybari

2010-09-01

Full Text Available "n  "n "nBackground and the purpose of the study:The most prominent nanoparticles for medical uses are nanosilver particles which are famous for their high anti-microbial activity. Silver ion has been known as a metal ion that exhibit anti-mold, anti-microbial and anti-algal properties for a long time. In particular, it is widely used as silver nitrate aqueous solution which has disinfecting and sterilizing actions. The purpose of this study was to evaluate the antimicrobial activity as well as physical properties of the silver nanoparticles prepared by chemical reduction method. "nMethods:Silver nanoparticles (NPs were prepared by reduction of silver nitrate in the presence of a reducing agent and also poly [N-vinylpyrolidone] (PVP as a stabilizer. Two kinds of NPs were synthesized by ethylene glycol (EG and glucose as reducing agent. The nanostructure and particle size of silver NPs were confirmed by scanning electron microscopy (SEM and laser particle analyzer (LPA. The formations of the silver NPs were monitored using ultraviolet-visible spectroscopy. The anti-bacterial activity of silver NPs were assessed by determination of their minimum inhibitory concentrations (MIC against the Gram positive (Staphylococcus aureus and Staphylococcus epidermidis as well as Gram-negative (Escherichia coli and Pseudomonas aeruginosa bacteria. "nResults and Conclusion:The silver nanoparticles were spherical with particle size between 10 to 250 nm. Analysis of the theoretical (Mie light scattering theory and experimental results showed that the silver NPs in colloidal solution had a diameter of approximately 50 nm. "nBoth colloidal silver NPs showed high anti-bacterial activity against Gram positive and Gram negative bacteria. Glucose nanosilver colloids showed a shorter killing time against most of the tested bacteria which could be due to their nanostructures and uniform size distribution patterns.

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

OpenAIRE

Kuppan Gokulan; Katherine Williams; Sangeeta Khare

2017-01-01

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 analysi...

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Activity of Antimicrobial Silver Polystyrene Nanocomposites

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M. Palomba

2012-01-01

Full Text Available A simple technique based on doping polymers with in situ generated silver nanoparticles (Ag/PS films has been developed. In particular, an antiseptic material has been prepared by dissolving silver 1,5-cyclooctadiene-hexafluoroacetylacetonate in amorphous polystyrene, and the obtained solid solution has been heated for ca. 10 s at a convenient temperature (180°C. Under such conditions the metal precursor decomposes producing silver atoms that diffuse into the polymer and clusterize. The antimicrobial characteristics of the resulting polystyrene-based material have been accurately evaluated toward Escherichia coli (E. coli comparing the cytotoxicity effect of 10 wt.% and 30 wt.% (drastic and mild annealing silver-doped polystyrene to the corresponding pure micrometric silver powder. Two different bacterial viability assays were performed in order to demonstrate the cytotoxic effect of Ag/PS films on cultured E. coli: (1 turbidimetric determination of optical density; (2 BacLight fluorescence-based test. Both methods have shown that silver-doped polystyrene (30 wt.% provides higher antibacterial activity than pure Ag powder, under similar concentration and incubation conditions.

Antimicrobial active silver nanoparticles and silver/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid

International Nuclear Information System (INIS)

An Jing; Wang Desong; Luo Qingzhi; Yuan Xiaoyan

2009-01-01

Uniform silver nanoparticles and silver/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM].BF 4 ). [BMIM].BF 4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5-15 nm and 15-25 nm, respectively. The X-ray diffraction analysis reveals the face-centered cubic geometry of silver nanoparticles. The as-prepared nanoparticles were also characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. In addition, antimicrobial activities against E. coli and S. aureus were studied and the results show that both silver nanoparticles and core-shell nanoparticles possess excellent antimicrobial activities. The antimicrobial mechanism of the as-prepared nanoparticles was discussed.

Evaluation of antioxidant, antibacterial and cytotoxic effects of green synthesized silver nanoparticles by Piper longum fruit

International Nuclear Information System (INIS)

Reddy, N. Jayachandra; Nagoor Vali, D.; Rani, M.; Rani, S. Sudha

2014-01-01

Silver nanoparticles synthesized through bio-green method has been reported to have biomedical applications to control pathogenic microbes as it is cost effective compared to commonly used physical and chemical methods. In present study, silver nanoparticles were synthesized using aqueous Piper longum fruit extract (PLFE) and confirmed by UV–visible spectroscopy. The nanoparticles were spherical in shape with an average particle size of 46 nm as determined by scanning electronic microscopy (SEM) and dynamic light scattering (DLS) particle size analyzer respectively. FT-IR spectrum revealed the capping of the phytoconstituents, probably polyphenols from P. longum fruit extract and stabilizing the nanoparticles. Further the ferric ion reducing test, confirmed that the capping agents were condensed tannins. The aqueous P. longum fruit extract (PLFE) and the green synthesized silver nanoparticles (PLAgNPs) showed powerful antioxidant properties in in vitro antioxidant assays. The results from the antimicrobial assays suggested that green synthesized silver nanoparticles (PLAgNPs) were more potent against pathogenic bacteria than the P. longum fruit extract (PLFE) alone. The nanoparticles also showed potent cytotoxic effect against MCF-7 breast cancer cell lines with an IC 50 value of 67 μg/ml/24 h by the MTT assay. These results support the advantages of using bio-green method for synthesizing silver nanoparticles with antioxidant, antimicrobial and cytotoxic activities those are simple and cost effective as well. - Highlights: • 46 nm spherical shaped P. longum fruit silver nanoparticles was prepared. • Capping and reducing bioactive plant compounds with in nanoparticles were condensed tannins. • Particles are potent antioxidant and anti microbial in biological systems. • They are cytotoxic against MCF-7 cell lines

Evaluation of antioxidant, antibacterial and cytotoxic effects of green synthesized silver nanoparticles by Piper longum fruit

Energy Technology Data Exchange (ETDEWEB)

Reddy, N. Jayachandra; Nagoor Vali, D.; Rani, M.; Rani, S. Sudha, E-mail: sadrassudha@gmail.com

2014-01-01

Silver nanoparticles synthesized through bio-green method has been reported to have biomedical applications to control pathogenic microbes as it is cost effective compared to commonly used physical and chemical methods. In present study, silver nanoparticles were synthesized using aqueous Piper longum fruit extract (PLFE) and confirmed by UV–visible spectroscopy. The nanoparticles were spherical in shape with an average particle size of 46 nm as determined by scanning electronic microscopy (SEM) and dynamic light scattering (DLS) particle size analyzer respectively. FT-IR spectrum revealed the capping of the phytoconstituents, probably polyphenols from P. longum fruit extract and stabilizing the nanoparticles. Further the ferric ion reducing test, confirmed that the capping agents were condensed tannins. The aqueous P. longum fruit extract (PLFE) and the green synthesized silver nanoparticles (PLAgNPs) showed powerful antioxidant properties in in vitro antioxidant assays. The results from the antimicrobial assays suggested that green synthesized silver nanoparticles (PLAgNPs) were more potent against pathogenic bacteria than the P. longum fruit extract (PLFE) alone. The nanoparticles also showed potent cytotoxic effect against MCF-7 breast cancer cell lines with an IC 50 value of 67 μg/ml/24 h by the MTT assay. These results support the advantages of using bio-green method for synthesizing silver nanoparticles with antioxidant, antimicrobial and cytotoxic activities those are simple and cost effective as well. - Highlights: • 46 nm spherical shaped P. longum fruit silver nanoparticles was prepared. • Capping and reducing bioactive plant compounds with in nanoparticles were condensed tannins. • Particles are potent antioxidant and anti microbial in biological systems. • They are cytotoxic against MCF-7 cell lines.

Tailoring silver nanoparticle construction using dendrimer templated silica networks

International Nuclear Information System (INIS)

Liu Xiaojun; Kakkar, Ashok

2008-01-01

We have examined the role of the internal environment of dendrimer templated silica networks in tailoring the construction of silver nanoparticle assemblies. Silica networks from which 3,5-dihydroxybenzyl alcohol based dendrimer templates have been completely removed, slowly wet with an aqueous solution of silver acetate. The latter then reacts with internal silica silanol groups, leading to chemisorption of silver ions, followed by the growth of silver oxide nanoparticles. Silica network constructed using generation 4 dendrimer contains residual dendrimer template, and mixes with aqueous silver acetate solution easily. Upon chemisorption, silver ions get photolytically reduced to silver metal under a stabilizing dendrimer environment, leading to the formation of silver metal nanoparticles

Effects of silver nitrate and silver nanoparticles on a planktonic community: general trends after short-term exposure.

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Jens Boenigk

Full Text Available Among metal pollutants silver ions are one of the most toxic forms, and have thus been assigned to the highest toxicity class. Its toxicity to a wide range of microorganisms combined with its low toxicity to humans lead to the development of a wealth of silver-based products in many bactericidal applications accounting to more than 1000 nano-technology-based consumer products. Accordingly, silver is a widely distributed metal in the environment originating from its different forms of application as metal, salt and nanoparticle. A realistic assessment of silver nanoparticle toxicity in natural waters is, however, problematic and needs to be linked to experimental approaches. Here we apply metatranscriptome sequencing allowing for elucidating reactions of whole communities present in a water sample to stressors. We compared the toxicity of ionic silver and ligand-free silver nanoparticles by short term exposure on a natural community of aquatic microorganisms. We analyzed the effects of the treatments on metabolic pathways and species composition on the eukaryote metatranscriptome level in order to describe immediate molecular responses of organisms using a community approach. We found significant differences between the samples treated with 5 µg/L AgNO3 compared to the controls, but no significant differences in the samples treated with AgNP compared to the control samples. Statistical analysis yielded 126 genes (KO-IDs with significant differential expression with a false discovery rate (FDR <0.05 between the control (KO and AgNO3 (NO3 groups. A KEGG pathway enrichment analysis showed significant results with a FDR below 0.05 for pathways related to photosynthesis. Our study therefore supports the view that ionic silver rather than silver nanoparticles are responsible for silver toxicity. Nevertheless, our results highlight the strength of metatranscriptome approaches for assessing metal toxicity on aquatic communities.

[Corrected Title: Solid-Phase Extraction of Polar Compounds from Water] Automated Electrostatics Environmental Chamber

Science.gov (United States)

Sauer, Richard; Rutz, Jeffrey; Schultz, John

2005-01-01

A solid-phase extraction (SPE) process has been developed for removing alcohols, carboxylic acids, aldehydes, ketones, amines, and other polar organic compounds from water. This process can be either a subprocess of a water-reclamation process or a means of extracting organic compounds from water samples for gas-chromatographic analysis. This SPE process is an attractive alternative to an Environmental Protection Administration liquid-liquid extraction process that generates some pollution and does not work in a microgravitational environment. In this SPE process, one forces a water sample through a resin bed by use of positive pressure on the upstream side and/or suction on the downstream side, thereby causing organic compounds from the water to be adsorbed onto the resin. If gas-chromatographic analysis is to be done, the resin is dried by use of a suitable gas, then the adsorbed compounds are extracted from the resin by use of a solvent. Unlike the liquid-liquid process, the SPE process works in both microgravity and Earth gravity. In comparison with the liquid-liquid process, the SPE process is more efficient, extracts a wider range of organic compounds, generates less pollution, and costs less.

Antimicrobial beeswax coated polylactide films with silver control release capacity.

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Martínez-Abad, Antonio; Lagarón, Jose Maria; Ocio, María Jose

2014-03-17

Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrated a high burst release which in some instances implied surpassing some current migration restrictions (food), the addition of a beeswax layer allowed a sustained release of the antimicrobial compound. Increasing the thickness of the beeswax layer resulted in an increase in the water barrier properties of the films while reducing the relatively constant values of sustained release. Antimicrobial performance was correlated with the release of silver ions, indicating threshold concentrations for biocide action of films displayed a strong bactericidal effect against Salmonella enterica. The application of this functional barrier thus offers the possibility of tuning the release profiles of the films to suit a specific application and puts forth the possible suitability of these materials for food packaging or other migration sensitive applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Content and Phrasing in Titles of Original Research and Review Articles in 2015: Range of Practice in Four Clinical Journals

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Mary Ellen Kerans

2016-04-01

Full Text Available Reporting guidelines for clinical research designs emerged in the mid-1990s and have influenced various aspects of research articles, including titles, which have also been subject to changing uses with the growth of electronic database searching and efforts to reduce bias in literature searches. We aimed (1 to learn more about titles in clinical medicine today and (2 to develop an efficient, reliable way to study titles over time and on the fly—for quick application by authors, manuscript editors, translators and instructors. We compared content and form in titles from two general medical journals—the New England Journal of Medicine (NEJM and the British Medical Journal—and two anesthesiology journals (the European Journal of Anaesthesiology and Anesthesiology; we also analyzed the inter-rater reliability of our coding. Significant content differences were found in the frequencies of mentions of methods, results (between general and subspecialty titles, and geographic setting; phrasing differences were found in the prevalence of full-sentence and compound titles (and their punctuation. NEJM titles were significantly shorter, and this journal differed consistently on several features. We conclude that authors must learn to efficiently survey titles for form and content patterns when preparing manuscripts to submit to unfamiliar journals or on resubmitting to a new journal after rejection.

2-(Substituted phenyl-3,4-dihydroisoquinolin-2-iums as Novel Antifungal Lead Compounds: Biological Evaluation and Structure-Activity Relationships

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Xin-Juan Yang

2013-08-01

Full Text Available The title compounds are a class of structurally simple analogues of quaternary benzo[c]phenanthridine alkaloids (QBAs. In order to develop novel QBA-like antifungal drugs, in this study, 24 of the title compounds with various substituents on the N-phenyl ring were evaluated for bioactivity against seven phytopathogenic fungi using the mycelial growth rate method and their SAR discussed. Almost all the compounds showed definite activities in vitro against each of the test fungi at 50 μg/mL and a broad antifungal spectrum. In most cases, the mono-halogenated compounds 2–12 exhibited excellent activities superior to the QBAs sanguinarine and chelerythrine. Compound 8 possessed the strongest activities on each of the fungi with EC50 values of 8.88–19.88 µg/mL and a significant concentration-dependent relationship. The SAR is as follows: the N-phenyl group is a high sensitive structural moiety for the activity and the characteristics and position of substituents intensively influence the activity. Generally, electron-withdrawing substituents remarkably enhance the activity while electron-donating substituents cause a decrease of the activity. In most cases, ortha- and para-halogenated isomers were more active than the corresponding m-halogenated isomers. Thus, the title compounds emerged as promising lead compounds for the development of novel biomimetic antifungal agrochemicals. Compounds 8 and 2 should have great potential as new broad spectrum antifungal agents for plant protection.

Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract.

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Mamun Or Rashida, Md; Shafiul Islam, Md; Azizul Haque, Md; Arifur Rahman, Md; Tanvir Hossain, Md; Abdul Hamid, Md

2016-01-01

Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV-Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can't be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program.

Role of Anions Associated with the Formation and Properties of Silver Clusters.

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Wang, Quan-Ming; Lin, Yu-Mei; Liu, Kuan-Guan

2015-06-16

Metal clusters have been very attractive due to their aesthetic structures and fascinating properties. Different from nanoparticles, each cluster of a macroscopic sample has a well-defined structure with identical composition, size, and shape. As the disadvantages of polydispersity are ruled out, informative structure-property relationships of metal clusters can be established. The formation of a high-nuclearity metal cluster involves the organization of metal ions into a complex entity in an ordered way. To achieve controllable preparation of metal clusters, it is helpful to introduce a directing agent in the formation process of a cluster. To this end, anion templates have been used to direct the formation of high nuclearity clusters. In this Account, the role of anions played in the formation of a variety of silver clusters has been reviewed. Silver ions are positively charged, so anionic species could be utilized to control the formation of silver clusters on the basis of electrostatic interactions, and the size and shape of the resulted clusters can be dictated by the templating anions. In addition, since the anion is an integral component in the silver clusters described, the physical properties of the clusters can be modulated by functional anions. The templating effects of simple inorganic anions and polyoxometales are shown in silver alkynyl clusters and silver thiolate clusters. Intercluster compounds are also described regarding the importance of anions in determining the packing of the ion pairs and making contribution to electron communications between the positive and negative counterparts. The role of the anions is threefold: (a) an anion is advantageous in stabilizing a cluster via balancing local positive charges of the metal cations; (b) an anion template could help control the size and shape of a cluster product; (c) an anion can be a key factor in influencing the function of a cluster through bringing in its intrinsic properties. Properties

Influence of nano-fiber membranes on the silver ions released from hollow fibers containing silver particles

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Li Huigai

2016-01-01

Full Text Available Polyether sulfone was dissolved into dimethylacetamide with the concentration of 20% to prepare a uniform solution for fabrication of nanofiber membranes by bubble electrospinning technique. Morphologies of the nanofiber film were carried out with a scanning electron microscope. The influence on the silver ions escaped from hollow fiber loaded with silver particles was exerted by using different release liquid. The water molecular clusters obtained from the nanofiber membranes filter can slow down the release of silver ions. However, the effect of slowing was weakened with the time increasing. In the end, the trend of change is gradually consistent with the trend of release of silver ions in the deionized water.

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

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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 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.

Electrodeposited Silver Nanoparticles Patterned Hexagonally for SERS

International Nuclear Information System (INIS)

Gu, Geun Hoi; Lee, Sue Yeone; Suh, Jung Sang

2010-01-01

We have fabricated hexagonally patterned silver nanoparticles for surface-enhanced Raman scattering (SERS) by electrodepositing silver on the surface of an aluminum plate prepared by completely removing the oxide from anodic aluminum oxide (AAO) templates. Even after completely removing the oxide, well-ordered hexagonal patterns, similar to the shape of graphene, remained on the surface of the aluminum plate. The borders of the hexagonal pattern protruded up to form sorts of nano-mountains at both the sides and apexes of the hexagon, with the apexes protruding even more significantly than the sides. The aluminum plate prepared by completely removing the oxide has been used in the preparation of SERS substrates by sputter-coating of gold or silver on it. Instead of sputter-coating, here we have electro-deposited silver on the aluminum plate. When silver was electro-deposited on the plate, silver nanoparticles were made along the hexagonal margins.

Silver sources of archaic Greek coinage

International Nuclear Information System (INIS)

Gentner, W.; Mueller, O.; Wagner, G.A.; Gale, N.H.

1978-01-01

The authors report on new chemical and lead isotopic results and interpretations of archaic Greek silver coins from the Asyut hoard which was buried around 475 B.C. Aeginetan coins were of central interest in this study. Possible ancient silver mines were explored in the Aegean region in the course of several geologic expeditions, and chemically and isotopically investigated. Some of the silver sources in Greece were traced by combination of the analytical methods and questions of provenance were solved. In addition, processes of silver smelting and refining were studied. Results and implications of this work are summarized in the final section on Conclusions. (orig.) [de

In vitro study of the antibacterial and anticancer activities of silver nanoparticles synthesized from Penicillium brevicompactum (MTCC-1999

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Shahnaz Majeed

2016-07-01

Full Text Available Among the most promising nanomaterials, metallic nanoparticles with antibacterial and antitumor properties are expected to open new avenues to fight and prevent various tumours and infectious diseases. The study of bactericidal nanomaterial is particularly timely considering the recent increase in new resistant strains of bacteria to the most potent antibiotics and the potential role of bactericidal nanomaterial as anticancer agents. This has promoted the research of the well-known activity of silver ions and silver-based compounds, including silver nanoparticles. The present work is the study of silver nanoparticles synthesized from Penicillium brevicompactum (MTCC-1999. The colour of the cell filtrate changes to dark brown upon addition of 1 mM AgNO3, suggesting the formation of silver nanoparticles. These silver nanoparticles (AgNPs were characterized and analyzed by UV–vis spectrophotometric analysis, which showed a peak of absorbance at 420 nm. Fourier transform infrared (FTIR analysis showed amines and amides that are responsible for the stabilization of AgNPs. To determine the particle size, atomic force microscopy (AFM analysis was used, which showed that the nanoparticles are spherical and are 30–50 nm in size. High-resolution transmission electron microscopy (HRTEM showed that AgNPs were well dispersed, spherical, and well within the range of 40–50 nm. These nanoparticles displayed good antibacterial activity and also increased the antibiotic activity of gatifloxacin, tetracycline, and vancomycin. These nanoparticles were further studied for their anticancer activity and showed high toxicity towards the MCF-7 breast cancer cell line.

Silver linings.

Science.gov (United States)

Bultas, Margaret W; Pohlman, Shawn

2014-01-01

The purpose of this interpretive phenomenological study was to gain a better understanding of the experiences of 11 mothers of preschool children with autism spectrum disorder (ASD). Mothers were interviewed three times over a 6 week period. Interviews were analyzed using interpretive methods. This manuscript highlights one particular theme-a positive perspective mothers described as the "silver lining." This "silver lining" represents optimism despite the adversities associated with parenting a child with ASD. A deeper understanding of this side of mothering children with ASD may help health care providers improve rapport, communication, and result in more authentic family centered care. Copyright © 2014 Elsevier Inc. All rights reserved.

Large silver-cadmium technology program

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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.

Plasmon enhanced silver quantum cluster fluorescence for biochemical applications

DEFF Research Database (Denmark)

Bernard, S.; Kutter, J.P.; Mogensen, Klaus Bo

2014-01-01

Fluorescence microscopy of individual silver quantum clusters on the surface of silver nanoparticles reveals strong photoactivated emission under blue light excitation [1-4]. In this work, silver nanoparticles are produced by annealing silver thin films deposited on a glass substrate and silver q...... purposes. It was found, that in presence of a strong nucleophile (such as CN-), silver quantum clusters are dissolved into non-fluorescing AgCN complexes, resulting in a fast and observable decrease of the fluorescent signal....

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

Science.gov (United States)

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.

The role of tannic acid and sodium citrate in the synthesis of silver nanoparticles

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Ranoszek-Soliwoda, Katarzyna; Tomaszewska, Emilia; Socha, Ewelina; Krzyczmonik, Pawel; Ignaczak, Anna; Orlowski, Piotr; Krzyzowska, Małgorzata; Celichowski, Grzegorz; Grobelny, Jaroslaw

2017-08-01

We describe herein the significance of a sodium citrate and tannic acid mixture in the synthesis of spherical silver nanoparticles (AgNPs). Monodisperse AgNPs were synthesized via reduction of silver nitrate using a mixture of two chemical agents: sodium citrate and tannic acid. The shape, size and size distribution of silver particles were determined by UV-Vis spectroscopy, dynamic light scattering (DLS) and scanning transmission electron microscopy (STEM). Special attention is given to understanding and experimentally confirming the exact role of the reagents (sodium citrate and tannic acid present in the reaction mixture) in AgNP synthesis. The oxidation and reduction potentials of silver, tannic acid and sodium citrate in their mixtures were determined using cyclic voltammetry. Possible structures of tannic acid and its adducts with citric acid were investigated in aqueous solution by performing computer simulations in conjunction with the semi-empirical PM7 method. The lowest energy structures found from the preliminary conformational search are shown, and the strength of the interaction between the two molecules was calculated. The compounds present on the surface of the AgNPs were identified using FT-IR spectroscopy, and the results are compared with the IR spectrum of tannic acid theoretically calculated using PM6 and PM7 methods. The obtained results clearly indicate that the combined use of sodium citrate and tannic acid produces monodisperse spherical AgNPs, as it allows control of the nucleation, growth and stabilization of the synthesis process. [Figure not available: see fulltext.

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

Science.gov (United States)

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

Science.gov (United States)

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

Synthesis of positively charged hybrid PHMB-stabilized silver nanoparticles: the search for a new type of active substances used in plant protection products

Science.gov (United States)

Krutyakov, Yurii A.; Kudrinsky, Alexey A.; Gusev, Alexander A.; Zakharova, Olga V.; Klimov, Alexey I.; Yapryntsev, Alexey D.; Zherebin, Pavel M.; Shapoval, Olga A.; Lisichkin, Georgii V.

2017-07-01

Modern agriculture calls for a decrease in pesticide application, particularly in order to decrease the negative impact on the environment. Therefore the development of new active substances and plant protection products (PPP) to minimize the chemical load on ecosystems is a very important problem. Substances based on silver nanoparticles are a promising solution of this problem because of the fact that in correct doses such products significantly increase yields and decrease crop diseases while displaying low toxicity to humans and animals. In this paper we for the first time propose application of polymeric guanidine compounds with varying chain lengths (from 10 to 130 elementary links) for the design and synthesis of modified silver nanoparticles to be used as the basis of a new generation of PPP. Colloidal solutions of nanocrystalline silver containing 0.5 g l-1 of silver and 0.01-0.4 g l-1 of polyhexamethylene biguanide hydrochloride (PHMB) were obtained by reduction of silver nitrate with sodium borohydride in the presence of PHMB. The field experiment has shown that silver-containing solutions have a positive effect on agronomic properties of potato, wheat and apple. Also the increase in activity of such antioxidant system enzymes as peroxidase and catalase in the tissues of plants treated with nanosilver has been registered.

Poly[[{μ3-2-[4-(2-hydroxyethylpiperazin-1-yl]ethanesulfonato}silver(I] trihydrate

Directory of Open Access Journals (Sweden)

Stephanie M. Bilinovich

2011-09-01

Full Text Available Ethanesulfonic acid-based buffers like 2-[4-(2-hydroxyethylpiperazin-1-yl]ethanesulfonic acid (HEPES are commonly used in biological experiments because of their ability to act as non-coordinating ligands towards metal ions. However, recent work has shown that some of these buffers may in fact coordinate metal ions. The title complex, {[Ag(C8H17N2O4S]·3H2O}n, is a metal–organic framework formed from HEPES and a silver(I ion. In this polymeric complex, each Ag atom is primarily coordinated by two N atoms in a distorted linear geometry. Weaker secondary bonding interactions from the hydroxy and sulfate O atoms of HEPES complete a distorted seesaw geometry. The crystal structure is stabilized by O—H...O hydrogen-bonding interactions.

Direct observation of the formation of silver precipitations by means of electron diffraction

International Nuclear Information System (INIS)

Benz, V.; Ostwald, R.; Weil, K.G.

1976-01-01

Thin films (20-1,000 A) of copper (I)-, silver, and lead(II)-halides were prepared by evaporation onto silver (III), gold (III), and PbTe (III)-surfaces. These films were irradiated in vacuo with 40 kV-electrons, in some cases also with the light of a Xenon-lamp. At the same time the diffraction pattern, produced by the electron beam at glancing incidence, was observed and registered photographically. Silver precipitates could be detected by their diffraction pattern, when the crystallites had grown to a size of about 50 A. From all materials investigated silveriodide showed maximum sensitivity. The precipitates formed show no orientation with respect to the host crystal. From the temperature dependence of the sensitivity an activation energy of 0.12 eV can be deduced leading to interstitial ion migration as rate determining step. Pure silverchloride can not been radiolyzed by 40 kV-electrons. After doping it with 0.3 mol% CaCl 2 or MgCl 2 it becomes very sensitive. The precipitate showes orientation with respect to the host lattice. Also pure CuJ is resistant against the electron beam. Mixed crystals (Ag, Cu)J with xsub(AgJ) > 0.5 behave similar as pure AgJ. Pb(II)-halides show no sensitivity, but the compounds AgBr x 2 PbBr 2 and 5 AgJ x PbJ 2 are readily radiolyzed, forming polycrystalline silver precipitates. The mechanism of radiolysis, its dependency on temperature and film thickness is discussed. (orig.) [de

Hydrothermal-induced assembly of colloidal silver spheres into various nanoparticles on the basis of HTAB-modified silver mirror reaction.

Science.gov (United States)

Yu, Dabin; Yam, Vivian Wing-Wah

2005-03-31

Small colloidal silver spheres (diameter synthesis process. Adjustment of the synthesis parameters, in particular the concentrations of HTAB and [Ag(NH3)2]+, led to an obvious shape evolution of silver nanoparticles, thus resulting in the shape-selective formation of the silver nanoparticles. The monodisperse nanocubes with a well-defined crystallographical structure (a single crystal bounded by six {200} facets) have a strong tendency to assemble into two-dimensional arrays on substrates. The nanowires with uniform diameter usually existed in the form of two-dimensional alignments. The findings suggested that hydrothermal-induced assembly of small silver colloidal particles should be a convenient and effective approach to the preparation of various silver nanoparticles.

Glass frits coated with silver nanoparticles for silicon solar cells

International Nuclear Information System (INIS)

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

2015-01-01

Graphical abstract: - Highlights: • Silver-coated glass frits for solar cells were prepared by electroless plating. • Gum Arabic was used as the activating agent of glass frits. • Silver-coated glass frits can improve the photovoltaic performances of solar cells. - Abstract: 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

Glass frits coated with silver nanoparticles for silicon solar cells

Energy Technology Data Exchange (ETDEWEB)

Li, Yingfen, E-mail: lyf350857423@163.com; Gan, Weiping; Zhou, Jian; Li, Biyuan

2015-06-30

Graphical abstract: - Highlights: • Silver-coated glass frits for solar cells were prepared by electroless plating. • Gum Arabic was used as the activating agent of glass frits. • Silver-coated glass frits can improve the photovoltaic performances of solar cells. - Abstract: 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.

Silica artificial opal incorporated with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

2009-07-15

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Silica artificial opal incorporated with silver nanoparticles

International Nuclear Information System (INIS)

Li Wenjiang; Sun Tan

2009-01-01

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Bibliography about silicon non-organic fluorine compounds

International Nuclear Information System (INIS)

Carles, M.

1963-01-01

This bibliography is made from Professor I.G. Ryss' book published in Moscow in 1956, translated in English under the title 'The chemistry of fluorine and its inorganic compounds' (Translation series. AEC tr 3927, Pt 1 and 2), and completed with the data found in the 'Chemical Abstracts' of the years 1946 to 1962 [fr

Micellized sequestered silver atoms and small silver clusters

International Nuclear Information System (INIS)

Borgarello, E.; Lawless, D.; Serpone, N.; Pelizzetti, E.; Meisel, D.

1990-01-01

Pulse radiolysis was used to examine the nature of the silver species obtained when an aqueous solution containing sequestered Ag + ions was reduced by hydrated electrons in the presence of a surfactant macrocyclic crown ether, labeled L, and/or a maltoside surfactant. The initially formed product is the Ag 0 (L) species which rapidly loses its ligand (half-life ≤5 μs) and reacts with another Ag + (L) ion to form Ag 2 + (L). The latter species decays by a bimolecular process to form the Ag 4 2+ (L) n species at a faster rate than its ligand free analogue. Ultimately, colloidal metallic silver, (Ag) n , forms which is stabilized by the surfactant moieties. No long-term stability to the reduced monomolecular species could be obtained

32 CFR 644.62 - Title evidence.

Science.gov (United States)

2010-07-01

... HANDBOOK Acquisition Procurement of Title Evidence, Title Clearance, and Closings § 644.62 Title evidence... and their charter to issue the same. They must also be financially sound and be willing and able to...

Silver manganese oxide electrodes for lithium batteries

Science.gov (United States)

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

2006-05-09

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

Title to mining properties

International Nuclear Information System (INIS)

Crouch, K.M.

1976-01-01

The requirements of the law which must be met in order to create title to an unpatented mining claim and the procedures which should be followed when an attempt is made to determine the title to the claim is acceptable are reviewed

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

Science.gov (United States)

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.

Ammonia sensing properties of silver nanocomposite with polypyrrole

Science.gov (United States)

Karmakar, N. S.; Kothari, D. C.; Bhat, N. V.

2013-02-01

Silver-polypyrrole nanocomposite thin film was prepared by a novel method. UV-Vis spectroscopic studies confirmed the presence of silver nanoparticles and also polymerization of pyrrole surrounding the silver nanoparticles. All the important X-ray diffraction peaks corresponding to silver were present in the composites. The silver nanoparticles and its composites with polypyrrole were observed by SEM and TEM. Electrical conductivity measurements were carried out using two probe method and it was found that the conductivity of nanocomposites is 10-5 S/cm. It was found that functionalized silver nanoparticles can act as efficient gas sensor for ammonia. The present result of the increase in conductivity with ammonia exposure is in contrast with the previously reported results of the decrease in conductivity.

Silver-Russell syndrome

Directory of Open Access Journals (Sweden)

Shohela Akhter

2016-08-01

Full Text Available Silver-Russell syndrome is clinically and genetically a heterogeneous disorder. In most of the cases, etiology is unknown, only in 10% cases defect in chromosome 7 is identified. It bas distinctive facial features and asymmetric limbs. Most predominant symptom is growth failure. A case of Silver-Russell syndrome reported here who presented with growth failure, hemihypertrophy ofleft side oftbe body, dysmorphic facial profile and difficulty in speech. Counseling was done with the parents regarding the etiology, progression and outcome of the disease.

Nanosecond (ns) laser transfer of silver nanoparticles from silver-exchanged soda-lime glass to transparent soda-lime glass and shock waves formation

International Nuclear Information System (INIS)

Sow, Mohamed Chérif; Blondeau, Jean-Philippe; Sagot, Nadine; Ollier, Nadège; Tite, Teddy

2015-01-01

Highlights: • Silver nanoparticles growth by nanosecond laser irradiation of silver exchanged soda-lime glasses. • Silver nanoparticles transfer. • Nanosecond laser induced shock waves formation on glass. - Abstract: In this contribution, we showed for the first time in our knowledge a single-step process for silver clusters and nanoparticles growth and transfer from silver-exchanged soda-lime glass to un-exchanged soda-lime glass (transparent glass in visible and NIR domain) by nanosecond (ns) laser irradiation. The transferred silver nanoparticles in transparent glass are strongly linked to the glass surface. In addition, we point out the formation of shock waves, with selective silver clustering on the top wave. This technique provides an alternative and simple way to obtain metallic nanoparticles in different media which can be traversed by laser wavelength used. Moreover, this experiment is made at room temperature and air environment. It is worth noting that our technique requires a glass previously doped with the corresponding silver ions

Pulsed EPR for studying silver clusters

International Nuclear Information System (INIS)

Michalik, J.; Wasowicz, T.; Sadlo, J.; Reijerse, E.J.; Kevan, L.

1996-01-01

The cationic silver clusters of different nuclearity have been produced by radiolysis of zeolite A and SAPO molecular sieves containing Ag + as exchangeable cations. The pulsed EPR spectroscopy has been applied for studying the local environment of silver cluster in order to understand the mechanism of cluster formation and stabilization. the electron spin echo modulation (ESEM) results on Ag 6 n+ cluster in dehydration zeolite A indicate that the hexameric silver is stabilized only in sodalite cages which are surrounded by α-cages containing no water molecules. Trimeric silver clusters formed in hydrated A zeolites strongly interact with water, thus the paramagnetic center can be considered as a cluster-water adduct. In SAPO-molecular sieves, silver clusters are formed only in the presence of adsorbed alcohol molecules. From ESEM it is determined that Ag 4 n+ in SAPO-42 is stabilized in α cages, where it is directly coordinated by two methanol molecules. Dimeric silver, Ag 2 + in SAPO-5 and SAPO-11 is located in 6-ring channels and interacts with three CH 3 OH molecules, each in different 10 ring or 12 ring channels. The differences of Ag 2 + stability in SAPO-5 and SAPO-11 are also discussed. (Author)

Electroless silver coating of rod-like glass particles.

Science.gov (United States)

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.

Radiolytic reduction reaction of colloidal silver bromide solution

International Nuclear Information System (INIS)

Oya, Yasuhisa; Zushi, Takehiro; Hasegawa, Kunihiko; Matsuura, Tatsuo.

1995-01-01

The reduction reaction of colloidal silver bromide (AgBr 3 ) 2- in nitrous oxide gas saturated solution of some alcohols: methanol, ethanol, 2-propanol and 2-methyl-2-propanol by γ-irradiation was studied spectrophotometrically in order to elucidate the mechanism of the formation of colloidal silver bromide (AgBr 3 ) 3- at ambient temperature. The amount of colloidal silver bromide formed increases in the order: i-PrOH, EtOH, MeOH. In t-BuOH, colloidal silver bromide did not form. The relative reactivities of alcohols for colloidal silver bromide was also studied kinetically. (author)

Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

Directory of Open Access Journals (Sweden)

Hernane S. Barud

2011-01-01

Full Text Available Antimicrobial bacterial cellulose-silver nanoparticles composite membranes have been obtained by “in situ” preparation of Ag nanoparticles from hydrolytic decomposition of silver nitrate solution using triethanolamine as reducing and complexing agent. The formation of silver nanoparticles was evidenced by the X-ray diffraction, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and absorption in the UV-Visible (350 nm to 600 nm. Thermal and mechanical properties together with swelling behavior for water were considered. TEA concentration was observed to be important in order to obtain only Ag particles and not a mixture of silver oxides. It was also observed to control particle size and amount of silver contents in bacterial cellulose. The composite membranes exhibited strong antimicrobial activity against Gram-negative and Gram-positive bacteria.

Silver Nanoparticles-graphene Oxide Nanocomposite for Antibacterial Purpose

International Nuclear Information System (INIS)

Chook, S.W.; Chia, C.H.; Sarani Zakaria; Mohd Khan Ayob; Chee, K.L.; Neoh, H.M.; Huang, N.M.

2011-01-01

Graphene oxide (GO) sheets, a single layer of carbon atoms which can be served as substrates for fabricating metallic nanoparticles-GO nano composites, have been used in this study The nanocomposite of silver nanoparticles and graphene oxide were produced via in-situ synthesis and with the aid of chitosan to investigate the formation of silver nanoparticles on the graphene oxide sheets. XRD and UV-Vis studies confirmed the formation of silver nanoparticles on GO sheets, while TEM and FESEM images presented the loading of silver nanoparticles on the GO sheets. The degree of loading and distribution of the silver nanoparticles on the graphene oxide were depended on the procedure during the formation of silver nanoparticles. The nano composites can be potentially used in food packaging and biomedical applications. (author)

Fluorescent silver nanoparticles via exploding wire technique

Indian Academy of Sciences (India)

Pure silver nanoparticles in double distilled water were generated via simple physical method using pure (99.9%) silver wires with 0.2 mm diameter. These wires have been exploded in water by bringing them into sudden contact with pure (99.9%) silver plate when subjected to a potential difference of 36 V DC. High current.

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

Science.gov (United States)

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].

Science.gov (United States)

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.

Effects of silver adsorbed on fumed silica, silver phosphate glass, bentonite organomodified with silver and titanium dioxide in aquatic indicator organisms.

Science.gov (United States)

Tomacheski, Daiane; Pittol, Michele; Simões, Douglas Naue; Ribeiro, Vanda Ferreira; Santana, Ruth Marlene Campomanes

2017-06-01

In order to reduce the level of transmission of diseases caused by bacteria and fungi, the development of antimicrobial additives for use in personal care, hygiene products, clothing and others has increased. Many of these additives are based on metals such as silver and titanium. The disposal of these products in the environment has raised concerns pertaining to their potential harmfulness for beneficial organisms. The objective of this study was to evaluate the influence of the shape, surface chemistry, size and carrier of three additives containing silver and one with titanium dioxide (TiO 2 ) on microcrustacean survival. Daphnia magna was used as a bioindicator for acute exposure test in suspensions from 0.0001 to 10,000ppm. Ceriodaphnia dubia was used for chronic test in TiO 2 suspensions from 0.001 to 100ppm. D. magna populations presented high susceptibility to all silver based additives, with 100% mortality after 24hr of exposure. A different result was found in the acute experiments containing TiO 2 suspensions, with mortality rates only after 48hr of incubation. Even on acute and chronic tests, TiO 2 did not reach a linear concentration-response versus mortality, with 1ppm being more toxic than 10,000ppm on acute test and 0.001 more toxic than 0.01ppm on chronic assay. Silver based material toxicity was attributed to silver itself, and had no relation to either form (nano or ion) or carrier (silica, phosphate glass or bentonite). TiO 2 demonstrated to have a low acute toxicity against D. magna. Copyright © 2016. Published by Elsevier B.V.

INIS: Authority list for journal titles

International Nuclear Information System (INIS)

2005-01-01

This is the 31st revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13,104 journal titles, 2,078 regularly scanned journals and 561 key journals. It was last updated in February 2005. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part III, all journals that are regularly scanned by INIS Centers are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part IV, all journals that are regularly scanned by INIS Centers are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part V, all journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part VI, all journals are sorted alphabetically under their title. The name of the

INIS: Authority list for journal titles

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-03-01

This is the 31st revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13,104 journal titles, 2,078 regularly scanned journals and 561 key journals. It was last updated in February 2005. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part III, all journals that are regularly scanned by INIS Centers are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part IV, all journals that are regularly scanned by INIS Centers are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part V, all journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part VI, all journals are sorted alphabetically under their title. The name of the

INIS: Authority list for journal titles

International Nuclear Information System (INIS)

2006-01-01

This is the 32nd revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13,231 journal titles, 2,125 regularly scanned journals and 555 key journals. It was last updated in February 2006. The purpose of this report is to provide descriptive cataloguers with a standard entry for the full title of a journal. In addition to the full journal title, the ISSN (International Standard Serial Number), administered by the ISSN International Centre, Paris, France, and/or CODEN, assigned by Chemical Abstracts Service, USA, are given in this manual. In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part III, all journals that are regularly scanned by INIS Centres are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part IV, all journals that are regularly scanned by INIS Centres are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. In Part V, all journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. In Part VI, all journals are sorted alphabetically under their title. The name of the

Suitsetamisega võitlemisel ei aita inimeste kiusamine / Silver Meikar

Index Scriptorium Estoniae

Meikar, Silver, 1978-

2004-01-01

Suitsetamise vastu võitlemisel ei tohiks kasutada rangelt seadusi vaid võimaldada soodsalt osta suitsetamisvastaseid vahendeid, leiab autor. Vt. ka: Silver Meikar: Olen valmis hoidma Eesti edu; Silver Meikar saatis lugejakirja Saksamaa päevalehtedele; Arvamusi Silver Meikarist; Silver Meikar loobus paberkandjale trükitud seaduseelnõudest

Thermal stability of LiNaR2F8 compounds (R=Ho-Lu, Y)

International Nuclear Information System (INIS)

Fedorov, P.P.; Medvedeva, L.V.; Bondareva, O.S.; Sobolev, B.P.

1990-01-01

Monoclinic pseudorhombic compound mentioned in the title are investigated. It is determined, that the compounds are stable within temperature narrow range: Ho - 575-693 degC, Er - 566-712deg C, Tm - 560-710 deg C, Yb - less than 685 deg C, Y - 580-712 deg C. Triangulation of LiF-NaF-YF 3 system is carried out

Synthesis and characterization of colloidal fluorescent silver nanoclusters.

Science.gov (United States)

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.

Modelling the effect of temperature and free acid, silver, copper and lead concentrations on silver electrorefining electrolyte conductivity

OpenAIRE

Aji, Arif T.; Kalliomäki, Taina; Wilson, Benjamin P.; Aromaa, Jari; Lundström, Mari

2016-01-01

Conductivity is one of the key physico-chemical properties of electrolyte in silver electrorefining since it affects the energy consumption of the process. As electrorefining process development trends towards high current density operation, having electrolytes with high conductivities will greatly reduce the energy consumption of the process. This study outlines investigations into silver electrorefining electrolyte conductivity as a function of silver, free acid, copper and lead concentrati...

Antimicrobial activity of biopolymeric thin films containing flavonoid natural compounds and silver nanoparticles fabricated by MAPLE: A comparative study

International Nuclear Information System (INIS)

Cristescu, R.; Visan, A.; Socol, G.; Surdu, A.V.; Oprea, A.E.; Grumezescu, A.M.; Chifiriuc, M.C.; Boehm, R.D.; Yamaleyeva, D.; Taylor, M.; Narayan, R.J.; Chrisey, D.B.

2016-01-01

Highlights: • We successfully deposited composite quercetin dehydrate-, resveratrol- and silver nanoparticle-polyvinylpyrrolidone thin coatings with chemical structure close to that of the starting materials by MAPLE. • Thin film morphology studies revealed a uniform surface without aggregates or grains on the top of the surface. • MAPLE-deposited thin films exhibited antibacterial activity against Gram-positive and Gram-negative bacterial strains. • We demonstrated the potential use of these hybrid systems and MAPLE deposition method for the development of new harmless, ecological antimicrobial strategies. - Abstract: The purpose of this study was to investigate the interactions between microorganisms, including the planktonic and adherent organisms, and biopolymer (polyvinylpyrrolidone), flavonoid (quercetin dihydrate and resveratrol)-biopolymer, and silver nanoparticles-biopolymer composite thin films that were deposited using matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF * excimer laser source was used to deposit the aforementioned composite thin films, which were characterized using Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The antimicrobial activity of thin films was quantified using an adapted disk diffusion assay against Gram-positive and Gram-negative bacteria strains. FT-IR, AFM and SEM studies confirmed that MAPLE may be used to fabricate thin films with chemical properties corresponding to the input materials as well as surface properties that are appropriate for medical use. The silver nanoparticles and flavonoid-containing films exhibited an antimicrobial activity both against Gram-positive and Gram-negative bacterial strains demonstrating the potential use of these hybrid systems for the development of novel antimicrobial strategies.

Antimicrobial activity of biopolymeric thin films containing flavonoid natural compounds and silver nanoparticles fabricated by MAPLE: A comparative study

Energy Technology Data Exchange (ETDEWEB)

Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Visan, A.; Socol, G. [National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Surdu, A.V.; Oprea, A.E.; Grumezescu, A.M. [Faculty of Applied Chemistry and Materials Science, Politehnica University of Bucharest, 1–7 Polizu Street, Bucharest, 011061 Romania (Romania); Chifiriuc, M.C. [Microbiology Immunology Department, Faculty of Biology, Research Institute of the University of Bucharest - ICUB, Bucharest, 77206 (Romania); Boehm, R.D.; Yamaleyeva, D.; Taylor, M.; Narayan, R.J. [Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC (United States); Chrisey, D.B. [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA (United States)

2016-06-30

Highlights: • We successfully deposited composite quercetin dehydrate-, resveratrol- and silver nanoparticle-polyvinylpyrrolidone thin coatings with chemical structure close to that of the starting materials by MAPLE. • Thin film morphology studies revealed a uniform surface without aggregates or grains on the top of the surface. • MAPLE-deposited thin films exhibited antibacterial activity against Gram-positive and Gram-negative bacterial strains. • We demonstrated the potential use of these hybrid systems and MAPLE deposition method for the development of new harmless, ecological antimicrobial strategies. - Abstract: The purpose of this study was to investigate the interactions between microorganisms, including the planktonic and adherent organisms, and biopolymer (polyvinylpyrrolidone), flavonoid (quercetin dihydrate and resveratrol)-biopolymer, and silver nanoparticles-biopolymer composite thin films that were deposited using matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF{sup *} excimer laser source was used to deposit the aforementioned composite thin films, which were characterized using Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The antimicrobial activity of thin films was quantified using an adapted disk diffusion assay against Gram-positive and Gram-negative bacteria strains. FT-IR, AFM and SEM studies confirmed that MAPLE may be used to fabricate thin films with chemical properties corresponding to the input materials as well as surface properties that are appropriate for medical use. The silver nanoparticles and flavonoid-containing films exhibited an antimicrobial activity both against Gram-positive and Gram-negative bacterial strains demonstrating the potential use of these hybrid systems for the development of novel antimicrobial strategies.

Towards conducting inks: Polypyrrole–silver colloids

International Nuclear Information System (INIS)

Omastová, Mária; Bober, Patrycja; Morávková, Zuzana; Peřinka, Nikola; Kaplanová, Marie; Syrový, Tomáš; Hromádková, Jiřina; Trchová, Miroslava; Stejskal, Jaroslav

2014-01-01

Graphical abstract: - Highlights: • Composite colloidal particles combining conducting polymer and metal have been prepared. • Conducting colloids are suitable for printing applications. • Polypyrrole/silver colloids are prepared in a single reaction step. • The conductivity control is discussed and still needs improvement. - Abstract: The oxidation of pyrrole with silver nitrate in the presence of suitable water-soluble polymers yields composite polypyrrole–silver colloids. The polypyrrole–silver nanoparticles stabilized with poly(N-vinylpyrrolidone) have a typical size around 350 nm and polydispersity index 0.20, i.e. a moderate polydispersity in size. Similar results have been obtained with poly(vinyl alcohol) as stabilizer. The effect of stabilizer concentration on the particle size is marginal. In the present study, several types of stabilizers have been tested in addition to currently used poly(N-vinylpyrrolidone). Transmission electron microscopy and optical microscopy revealed the gemini morphology of polypyrrole and silver colloidal nanoparticles and confirmed their size and size-distribution determined by dynamic light scattering. The use of colloidal dispersions provides an efficient tool for the UV–vis and FT Raman spectroscopic characterization of polypyrrole, including the transition between polypyrrole salt and corresponding polypyrrole base. The dispersions were used for the preparation of coatings on polyethylene terephthalate foils, and the properties for polypyrrole–silver composites have been compared with those produced from polypyrrole colloids alone

A simple method of growing silver chloride nanocubes on silver nanowires

Science.gov (United States)

Hosseinzadeh Khaligh, Hadi; Goldthorpe, Irene A.

2015-09-01

The growth of AgCl nanocubes directly on the sidewalls of Ag nanowires is demonstrated. The nanocubes can be simply obtained through extended low temperature annealing of polyol-synthesized silver nanowires in a vacuum. The length of time and temperature of the anneal and the diameter of the nanowire affect the size and density of the nanocubes obtained. It is hypothesized that the AgCl material is supplied from reactants leftover from the silver nanowire synthesis. This novel hybrid nanostructure may have applications in areas such as photovoltaics, surface enhanced Raman spectroscopy, and photocatalysis.

Synthesis and characterization of silver-polypyrrole film composite

Energy Technology Data Exchange (ETDEWEB)

Ayad, Mohamad M., E-mail: mayad12000@yahoo.com [Department of Chemistry, Faculty of Science, University of Tanta, Tanta (Egypt); Zaki, Eman [Department of Chemistry, Faculty of Science, University of Tanta, Tanta (Egypt)

2009-11-15

In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO{sub 3}. Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO{sub 3} solution increases. The morphology of the surface of the PPy film and the silver-PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples.

Synthesis and characterization of silver-polypyrrole film composite

International Nuclear Information System (INIS)

Ayad, Mohamad M.; Zaki, Eman

2009-01-01

In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO 3 . Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO 3 solution increases. The morphology of the surface of the PPy film and the silver-PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples.

Synthesis and characterization of silver-polypyrrole film composite

Science.gov (United States)

Ayad, Mohamad. M.; Zaki, Eman

2009-11-01

In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO 3. Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO 3 solution increases. The morphology of the surface of the PPy film and the silver-PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples.

Isatis tinctoria mediated synthesis of amphotericin B-bound silver nanoparticles with enhanced photoinduced antileishmanial activity: A novel green approach.

Science.gov (United States)

Ahmad, Aftab; Wei, Yun; Syed, Fatima; Khan, Shafiullah; Khan, Gul Majid; Tahir, Kamran; Khan, Arif Ullah; Raza, Muslim; Khan, Faheem Ullah; Yuan, Qiping

2016-08-01

After malaria, Leishmaniasis is the most prevalent infectious disease in terms of fatality and geographical distribution. The availability of a limited number of antileishmanial agents, emerging resistance to the available drugs, and the high cost of treatment complicate the treatment of leishmaniasis. To overcome these issues, critical research for new therapeutic agents with enhanced antileishmanial potential and low treatment cost is needed. In this contribution, we developed a green protocol to prepare biogenic silver nanoparticles (AgNPs) and amphotericin B-bound biogenic silver nanoparticles (AmB-AgNPs). Phytochemicals from the aqueous extract of Isatis tinctoria were used as reducing and capping agents to prepare silver nanoparticles. Amphotericin B was successfully adsorbed on the surface of biogenic silver nanoparticles. The prepared nanoparticles were characterized by various analytical techniques. UV-Visible spectroscopy was employed to detect the characteristic localized surface plasmon resonance peaks (LSPR) for the prepared nanoparticles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies revealed the formation of spherical silver nanoparticles with an average particle size of 10-20nm. The cubic crystalline structure of the prepared nanoparticles was confirmed by X-ray diffraction (XRD) study. FTIR spectroscopic analysis revealed that plant polyphenolic compounds are mainly involved in metal reduction and capping. Under visible light irradiation, biogenic silver nanoparticles exhibited significant activity against Leishmania tropica with an IC50 value of 4.2μg/mL. The leishmanicidal activity of these nanoparticles was considerably enhanced by conjugation with amphotericin B (IC50=2.43μg/mL). In conclusion, the findings of this study reveal that adsorption of amphotericin B, an antileishmanial drug, to biogenic silver nanoparticles, could be a safe, more effective and economic alternative to the available

Toxicity of silver nanoparticles in monocytes and keratinocytes

DEFF Research Database (Denmark)

Orłowski, Piotr; Krzyzowska, Malgorzata; Winnicka, Anna

2012-01-01

Silver nanoparticles are of interest to be used as antimicrobial agents in wound dressings and coatings in medical devices, but potential adverse effects have been reported in the literature. The possible local inflammatory response to silver nanoparticles and the role of cell death in determining...... these effects are largely unknown. Effects of the mixture of silver nanoparticles of different sizes were compared in in vitro assays for cytotoxicity, caspase-1 and caspase-9 activity and bax expression. In all tested concentrations, silver nanoparticles were more toxic for RAW 264.7 monocytes than for 291.03C...... keratinocytes and induced significant caspase-1 activity and necrotic cell death. In keratinocytes, more significantly than in macrophages, silver nanoparticles led to increase of caspase-9 activity and apoptosis. These results indicate that effects of silver nanoparticles depend on the type of exposed cells...

Polypyrrole-silver Nanocomposite: Synthesis and Characterization

Directory of Open Access Journals (Sweden)

D. M. Nerkar

2016-07-01

Full Text Available Polypyrrole-Silver (PPy-Ag nanocomposite has been successfully synthesized by the chemical oxidative polymerization of pyrrole with iron (III chloride as an oxidant, in the presence of a colloidal suspension of silver nanoparticles. Turkevich method (Citrate reduction method was used for the synthesis of silver nanoparticles (Ag NPs. The silver nanoparticles were characterized by UV-Visible spectroscopy which showed an absorption band at 423 nm confirming the formation of nanoparticles. PPy-Ag nanocomposite was characterized by Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM, Fourier Transform Infrared Spectroscopy (FTIR and X-ray diffraction (XRD techniques for morphological and structural confirmations. TEM and SEM images revealed that the silver nanoparticles were well dispersed in the PPy matrix. XRD pattern showed that PPy is amorphous but the presence of the peaks at 2q values of 38.24°, 44.57°, 64.51° and 78.45° corresponding to a cubic phase of silver, revealed the incorporation of silver nanoparticles in the PPy matrix. A possible formation mechanism of PPy-Ag nanocomposite was also proposed. The electrical conductivity of PPy-Ag nanocomposite was studied using two probe method. The electrical conductivity of the PPy-Ag nanocomposite prepared was found to be 4.657´10- 2 S/cm, whereas that of pure PPy was found to be 9.85´10-3 S/cm at room temperature (303 K. The value of activation energy (Ea for pure PPy was 0.045 eV while it decreased to 0.034 eV for PPy-Ag nanocomposite. The synthesized nanocomposite powder can be utilized as a potential material for fabrication of gas sensors operating at room temperature.

Synthesis of battery grade reduced silver powder

International Nuclear Information System (INIS)

Qadeer, R.; Hameed, M.; Ikram, S.; Munir, A.

2002-01-01

Process for production of battery grade reduced silver powder, an active positive material for zinc-silver oxide batteries, having specific characteristics has been optimized and the synthesized reduced silver powder was characterized. Results reveal that the values of bulk density (1.25 0.1 g/cm3) and activity (73.27 %) of synthesized reduced silver powder lies within the recommended range for use as battery material. It has purity ≥ 98% and contains Fe and Cu as traces in the concentration range of 30 5 ppm and 15 7 ppm respectively. Others determined values of surface and pores parameters are: surface area 2.6 .4 m2/g: pore volume 3.10 cm3/g: pore diameter 0.043 mu m and porosity 20%. XRD studies reveal that reduced silver powder has a cubic structure. (author)

Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells.

Science.gov (United States)

Klíma, Petr; Laňková, Martina; Vandenbussche, Filip; Van Der Straeten, Dominique; Petrášek, Jan

2018-05-01

Silver ions increase plasma membrane permeability for water and small organic compounds through their stimulatory effect on plasma membrane calcium channels, with subsequent modulation of intracellular calcium levels and ion homeostasis. The action of silver ions at the plant plasma membrane is largely connected with the inhibition of ethylene signalling thanks to the ability of silver ion to replace the copper cofactor in the ethylene receptor. A link coupling the action of silver ions and cellular auxin efflux has been suggested earlier by their possible direct interaction with auxin efflux carriers or by influencing plasma membrane permeability. Using tobacco BY-2 cells, we demonstrate here that besides a dramatic increase of efflux of synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthalene acetic acid (NAA), treatment with AgNO 3 resulted in enhanced efflux of the cytokinin trans-zeatin (tZ) as well as the auxin structural analogues tryptophan (Trp) and benzoic acid (BA). The application of AgNO 3 was accompanied by gradual water loss and plasmolysis. The observed effects were dependent on the availability of extracellular calcium ions (Ca 2+ ) as shown by comparison of transport assays in Ca 2+ -rich and Ca 2+ -free buffers and upon treatment with inhibitors of plasma membrane Ca 2+ -permeable channels Al 3+ and ruthenium red, both abolishing the effect of AgNO 3 . Confocal microscopy of Ca 2+ -sensitive fluorescence indicator Fluo-4FF, acetoxymethyl (AM) ester suggested that the extracellular Ca 2+ availability is necessary to trigger the response to silver ions and that the intracellular Ca 2+ pool alone is not sufficient for this effect. Altogether, our data suggest that in plant cells the effects of silver ions originate from the primal modification of the internal calcium levels, possibly by their interaction with Ca 2+ -permeable channels at the plasma membrane.

Selective Rayleigh light scattering determination of trace quercetin with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Usoltseva, Liliya O.; Samarina, Tatiana O. [Department of Chemistry, M.V.Lomonosov Moscow State University, 119991 GSP-1 Moscow (Russian Federation); Abramchuk, Sergei S. [Nesmeyanov Institute of Organoelement Compounds (INEOS), Russian Academy of Sciences, Vavilova 28, Moscow 119991 (Russian Federation); Prokhorova, Aleksandra F. [Department of Chemistry, M.V.Lomonosov Moscow State University, 119991 GSP-1 Moscow (Russian Federation); Beklemishev, Mikhail K., E-mail: mkb@analyt.chem.msu.ru [Department of Chemistry, M.V.Lomonosov Moscow State University, 119991 GSP-1 Moscow (Russian Federation)

2016-11-15

Rayleigh light scattering (RLS) is a simple technique with a high potential of sensitive determination of small organic molecules. We have found that ppb amounts of quercetin (Qu) greatly enhance the RLS of the solution of silver nanoparticles (AgNPs) stabilized with cetyltrimethylammonium bromide (CTAB) or sodium n-dodecyl sulfate (SDS). Enhancement of light scattering is observed only in the presence of an excess of AgNO{sub 3}, which implies that it is a result of nanoparticle growth; another reason for the enhanced scattering is the aggregation of AgNPs by the analyte that was confirmed by dynamic light scattering technique. The conditions were chosen for the determination of Qu in aqueous solution with the detection limits of 0.01 and 0.03 μmol L{sup −1} and linear ranges of 0.1–1.3 and 0.1–2.0 μmol L{sup −1} for SDS- and CTAB-stabilized AgNPs, respectively; the intra-day RSDs did not exceed 7%. Unexpectedly, other bioflavonoids (rutin, dihydroquercetin, and naringenin) did not change the signal of Qu and did not interfere with its determination in 1:1 M ratio (0.5 μmol L{sup −1} each). Other compounds (asparagin, uric acid, urea and some inorganic ions) were also tolerated in high amounts. - Highlights: • Low concentrations of quercetin enhance the light scattering by silver nanoparticles. • Main processes are aggregation, nanoparticle growth and formation of new particles. • Other compounds exert a weaker effect on the light scattering signal.

Tribological properties of adaptive phosphate composite coatings with addition of silver and molybdenum disulfide

Energy Technology Data Exchange (ETDEWEB)

Liu, Cancan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou (China); University of Chinese Academy of Sciences, Beijing (China); Chen, Lei, E-mail: chenlei@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou (China); Zhou, Jiansong, E-mail: jszhou@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou (China); Zhou, Huidi; Chen, Jianmin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou (China)

2014-05-01

Highlights: • A new kind of adaptive coatings was fabricated using relatively simple spraying techniques. • The tribological properties of Ag/MoS{sub 2} phosphate composite coatings were investigated at the temperature from 20 °C to 700 °C. • The composition and wear mechanisms of Ag/MoS{sub 2} phosphate composite coatings were also discussed. • The Ag/MoS{sub 2} phosphate composite coatings have self-repairing capability in the rubbing process at 700 °C. - Abstract: Adaptive phosphate composite coatings with addition of solid lubricants of molybdenum disulfide (MoS{sub 2}) and silver (Ag) using aluminum chromium phosphate as the binder were fabricated on high-temperature steel. The tribological properties of phosphate composite coatings were evaluated from room temperature (RT) to 700 °C. The phase composition and microstructure were investigated according to the characterization by power X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The results show that the composite coating with the Ag/MoS{sub 2} mass ratio of 2:1 exhibits the stable and low friction coefficients from RT to 700 °C and relative low wear rates at all testing temperatures. The tribo-chemical reaction between Ag and MoS{sub 2} occurred in the rubbing process to form silver molybdates compounds lubricating film. The temperature-adaptive tribological properties were attributed to the formation of lubricating films composed of lubricants silver, MoS{sub 2} and silver molybdates phases on the worn surfaces of the composites coatings in a wide-temperature range.

Clinical spectrum of silver - Russell syndrome

Directory of Open Access Journals (Sweden)

Sapna N.K. Varma

2013-01-01

Full Text Available Silver - Russell syndrome is a clinically and genetically heterogenous condition characterized by severe intrauterine and postnatal growth retardation, craniofacial disproportion and normal intelligence downward curvature of the corner of the mouth, syndactyly and webbed fingers. Diagnosis of Silver - Russell syndrome remains clinical; no definite etiology or specific tests have been established. In the recent years, it has been shown that more than 38% of patients have hypomethylation in the imprinting control region 1 of 11p15 and one-tenth of patients carry a maternal uniparental disomy of chromosome seven. The pathophysiological mechanisms resulting in the Silver - Russell phenotype remain unknown despite the recent progress in deciphering the molecular defects associated with this condition. This case report describes the clinical features of Silver - Russell syndrome in a father and daughter.

Structural, electronic and optical properties of silver delafossite oxides: A first-principles study with hybrid functional

International Nuclear Information System (INIS)

Kumar, Mukesh; Persson, Clas

2013-01-01

Ternary delafossite compounds are potential materials for optoelectronic devices. Employing a first-principles method, we calculate the structural, electronic, and optical properties of the silver based compounds AgMO 2 (M=Al, Ga or In), which crystallize in delafossite structure. Our calculations show that these AgMO 2 oxides have indirect band gaps and the gap energies are in the region of 1.6–3.0 eV whereas, the lowest direct band gap energies are estimated in the range of 2.6–4.3 eV. Furthermore, we find that AgMO 2 compounds exhibit a strong anisotropy for the dielectric function and absorption spectra. The absorption onset for these compounds occurs well above the band gap energies. Overall, we show that the hybrid functional improves the lattice parameters and band gap energies and the calculated values are in good agreement with the experimental values

7 CFR 1927.55 - Title clearance services.

Science.gov (United States)

2010-01-01

... REGULATIONS TITLE CLEARANCE AND LOAN CLOSING Real Estate Title Clearance and Loan Closing § 1927.55 Title clearance services. (a) Responsibilities of closing agents. Services to be provided to the agency and the borrower by a closing agent in connection with the transaction vary depending on whether a title insurance...

Shape transformation of silver nanospheres to silver nanoplates induced by redox reaction of hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Parnklang, Tewarak; Lamlua, Banjongsak; Gatemala, Harnchana; Thammacharoen, Chuchaat [Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Kuimalee, Surasak [Industrial Chemistry and Textile Technology Programme, Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Lohwongwatana, Boonrat [Metallurgical Engineering Department, Faculty of Engineering, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Ekgasit, Sanong, E-mail: sanong.e@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand)

2015-03-01

In this paper we demonstrate a simple and rapid shape transformation of silver nanospheres (AgNSs) to silver nanoplates (AgNPls) using the oxidation and reduction capabilities of hydrogen peroxide. AgNPls having tunable surface plasmon resonance across the visible region with average size of 40–100 nm and thickness of 10–15 nm can be fabricated within 2 min simply by adding H{sub 2}O{sub 2} into a colloid of AgNSs with average particle size of 7 nm. The efficiency of H{sub 2}O{sub 2} as a shape-transforming agent depends strongly on its concentration, pH of the AgNS colloid, and the employed stabilizers. H{sub 2}O{sub 2} oxidizes AgNSs to silver ions while concertedly reduces silver ions to silver atom necessary for the growth of AgNPls. The shape transformation reaction was conducted at a relatively low concentration of H{sub 2}O{sub 2} in order to minimize the oxidative dissolution while facilitating kinetically controlled growth of AgNPls under a near neutral pH. Polyvinyl-pyrrolidone is an effective steric stabilizer preventing aggregation while assisting the growth of AgNPls. Trisodium citrate inhibits the formation of AgNPls under the H{sub 2}O{sub 2} reduction as it forms a stable complex with silver ions capable of withstanding the weakly reducing power of H{sub 2}O{sub 2}. After a complete consumption of AgNSs, large nanoplates grows with an expense of smaller nanoplates. The growth continues until H{sub 2}O{sub 2} is exhausted. A high concentration H{sub 2}O{sub 2} promotes catalytic decomposition of H{sub 2}O{sub 2} on the surface of AgNSs and oxidative dissolution of AgNSs without a formation of AgNPls. - Graphical abstract: Proposed mechanism for the shape transformation of AgNSs to AgNPls induced by the oxidation/reduction of H{sub 2}O{sub 2}. - Highlights: • Rapid shape transformation of silver nanospheres to nanoplates by H{sub 2}O{sub 2}. • Structural change completes in 2 min with a yellow-to-blue color change. • Selective fabrication of

Autometallography: tissue metals demonstrated by a silver enhancement kit

DEFF Research Database (Denmark)

Danscher, G; Nørgaard, J O; Baatrup, E

1987-01-01

, primarily intended for the amplification of colloidal gold particles, has been used to demonstrate these catalytic tissue metals. Sections from animals exposed intravitally to aurothiomalatate, silver lactate, mercury chloride, sodium selenite or perfused with sodium sulphide were subjected to a commercial......In biological tissue, minute accumulations of gold, silver, mercury and zinc can be visualized by a technique whereby metallic silver is precipitated on tiny accumulations of the two noble metals, or on selenites or sulphides of all four metals. In the present study a silver enhancement kit...... silver enhancement kit (IntenSE, Janssen Pharmaceutica). It was found that the kit performs adequately to the silver lactate gum arabic developer and to the photographic emulsion technique. The kit can be used as a silver enhancement medium for the demonstration of zinc by the Neo-Timm and selenium...

A new crystal modification of diammonium hydrogen phosphate, (NH42(HPO4

Directory of Open Access Journals (Sweden)

Bernhard Spingler

2010-04-01

Full Text Available The addition of hexafluoridophosphate salts (ammonium, silver, thallium or potassium is usually used to precipitate complex cations from aqueous solutions. It has long been known that PF6− is sensitive towards hydrolysis under acidic conditions [Gebala & Jones (1969. J. Inorg. Nucl. Chem. 31, 771–776; Plakhotnyk et al. (2005. J. Fluorine Chem. 126, 27–31]. During the course of our investigation into coinage metal complexes of diphosphine ligands, we used ammonium hexafluoridophosphate in order to crystallize [Ag(diphosphine2]PF6 complexes. From these solutions we always obtained needle-like crystals which turned out to be the title compound, 2NH4+·HPO42−. It was received as the hydrolysis product of NH4PF6. The crystals are a new modification of diammonium hydrogen phosphate. In contrast to the previously published polymorph [Khan et al. (1972. Acta Cryst. B28, 2065–2069], Z′ of the title compound is 2. In the new modification of the title compound, there are eight molecules of (NH42(HPO4 in the unit cell. The structure consists of PO3OH and NH4 tetrahedra, held together by O—H...O and N—H...O hydrogen bonds.

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

Science.gov (United States)

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.

Cadmium removal from aqueous solution by green synthesis zero valent silver nanoparticles with Benjamina leaves extract

Directory of Open Access Journals (Sweden)

Khairia M. Al-Qahtani

2017-12-01

Full Text Available Cadmium (II is an important element used in various industries, however, it is a poisonous element that affects the health of plants, animals and humans alike. It’s very important to remove this element from contaminated waters. This study aims at synthesizing zero valent silver nanoparticles by environmentally ecofriendly method without using hazardous compounds (via green approach. In this work, silver nanoparticles were prepared using hot water for the Ficus tree (Ficus Benjamina leaf extract (FBLE. The size of crystalline for AgNPs was measured by UV–vis spectroscopy and flourier transform infrared (FTIR. The properties of nano-silver particles (AgNPs have been studied using scanning electron microscope (SEM. The capability of nanoparticles to remove Cd2+ from contaminated solution was then studied. Parameter like adsorbent dose, heavy metal concentration, pH, agitation speed and contact time were studied. Cadmium removal increased when the dosage of biosorbent increases, pH increased from 1 to 6, contact time from 5 to 40 and initial concentration of Cd decrease. Isotherm adsorption was also described by the Freundleich model with a constant correlation (R2 higher than 0.973.

Preparation of silver chloride nanoparticles by a mechanical treatment of the system NH4Cl−AgNO3−NH4NO3

Directory of Open Access Journals (Sweden)

Farit Urakaev

2014-08-01

Full Text Available Silver chloride nanoparticles dispersed within ammonium nitrate matrix have been prepared though displacement mechanochemical reaction NH4Cl + AgNO3 + z NH4NO3 = (z+1 NH4 NO3 + AgCl at various z coefficients z1 = 7.22 and z2 = 3.64. The intermediate compound of NH4Ag(NO32 were recorded after mechanochemical processing of studied system. By using simultaneous TG and DSC measurements possibilities to prepare silver chloride in its free form have been discussed by using thermal treatment.

Analyzing silver concentration in soil using laser-induced breakdown spectroscopy

Science.gov (United States)

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.

Highly Stable Monocrystalline Silver Clusters for Plasmonic Applications

DEFF Research Database (Denmark)

Novikov, Sergey M.; Popok, Vladimir N.; Evlyukhin, Andrey B.

2017-01-01

Plasmonic sensor configurations utilizing localized plasmon resonances in silver nanostructures typically suffer from the rapid degradation of silver under ambient atmospheric conditions. In this work, we report on the fabrication and detailed characterization of ensembles of monocrystalline silver......-beam technique and characterized by linear spectroscopy, two-photon-excited photoluminescence, surface-enhanced Raman scattering microscopy, and transmission electron, helium ion, and atomic force microscopies. It is found that the fabricated ensembles of monocrystalline silver NPs preserve their plasmonic...... properties (monitored with optical spectroscopy) and strong field enhancements (revealed by surface-enhanced Raman spectroscopy) at least 5 times longer as compared to chemically synthesized silver NPs with similar sizes. The obtained results are of high practical relevance for the further development...

Rapid and Efficient Synthesis of Silver Nanofluid Using Electrical Discharge Machining

Directory of Open Access Journals (Sweden)

Kuo-Hsiung Tseng

2013-01-01

Full Text Available The electrical discharge machining (EDM system has been proven feasible as a rapid and efficient method for silver nanofluid preparation. This study prepared the silver nano-fluid via EDM and investigated the relationship between its process parameters and product characteristics. The prior study had found that the silver nano-fluid prepared by EDM contained both silver nanoparticles and silver ions. Silver ions had revealed the cause of the high suspension of the silver nanoparticles. To examine the relationship between the stability of silver nanofluid and the process parameters, this study quantified the relationship of process parameters to the material removal rate (MRR of silver electrode and silver ion output rate (IOR in the fluid, in order to achieve the most effective process parameter condition. Furthermore, the stability of silver nano-fluid was analyzed by various devices, including UV-Vis spectroscopy, size-distribution, and Zeta-potential analyzer. The effects of MRR, IOR, particle size, Zeta-potential, and optical properties of silver nanofluid under different process parameters are also discussed.

ANTIFUNGAL ACTIVITY OF SILVER NANOPARTICLES OBTAINED BY GREEN SYNTHESIS

Directory of Open Access Journals (Sweden)

Eduardo José J. MALLMANN

2015-04-01

Full Text Available Silver nanoparticles (AgNPs are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment.

Preparation of counterion stabilized concentrated silver sols.

Science.gov (United States)

LaPlante, Sylas; Halaciuga, Ionel; Goia, Dan V

2011-07-01

A strategy for obtaining stable concentrated silver dispersions without dedicated stabilizing agents is presented. This approach consists of rapidly mixing aqueous solutions of silver salicylate and ascorbic acid. By using salicylate as Ag(+) counterion, it is possible to prepare stable sols with metal concentrations up to two orders of magnitude higher than with silver nitrate. The stabilizing effect of the counterion is the result of a decreased ionic strength due to salicylate protonation and its adsorption on the surface of silver. Both effects increase the range of the electrostatic repulsive forces by expanding the electrical double layer. Copyright © 2011 Elsevier Inc. All rights reserved.

Silver Uptake and Reuse of Biomass by Saccharomyces cerevisiae ...

African Journals Online (AJOL)

Studies were carried out on the recovery of bound silver and reuse of Chlorella emersonii and Saccharomyces cerevisiae biomass for further silver uptake after they were placed in contact with 20mg/l silver for 30 minutes to allow for maximum binding. It was found that 0.16M nitric acid gave the best recovery rates of silver.

Effect of Silver Nanoparticles and Sodium Silicate on Vase Life and Quality of Cut Chrysanthemum Dendranthema grandiflorum L. (Flower

Directory of Open Access Journals (Sweden)

S. Kazemipour

2016-02-01

Full Text Available Dendranthema grandiflorum L. is one of the widely cultivated flowers around the world for producing of cut flowers. Nanometer-sized silver particles are used in various applications as an anti-microbial compound. This experiment was carried out to study the effects of silver nanoparticles (0, 5, 10 and 20 mg/L and sodium silicate (0, 50, 100 and 150 mg/L on longevity and quality of cut chrysanthemum (Dendranthema grandiflorum L. flowers. A factorial experiment was conducted based on randomized complete block design with 16 treatments, 3 replications, 48 plots and 192 cut flowers. The cut flowers were pulsed for 24 h with pulse solutions and then transported to 300 mg L-1 8-hidroxy quinoline sulfate and 3% sucrose. The characteristics such as vase life, loss of fresh weight, number of bacterial colonies in stem, lipid peroxidation, and activity of superoxide dismutase (SOD were measured. Results showed that all treatments had positive effects on the vase life of flowers. Pulse solution with 10 mg/L silver nanoparticles and 100 mg/L sodium silicate and interaction between them, increased vase life compared to the control (3.21, 4.46 and 8.50 days, respectively. In addition, the flowers pulsed with silver nanoparticles and sodium silicate exhibited higher activity of SOD, compared to control. The present study showed that using proper concentrations of silver nanoparticles and sodium silicate can enhance the vase life of cut chrysanthemum flowers.

National Ignition Facility Title II Design Plan

International Nuclear Information System (INIS)

Kumpan, S

1997-01-01

This National Ignition Facility (NIF) Title II Design Plan defines the work to be performed by the NIF Project Team between November 1996, when the U.S. Department of Energy (DOE) reviewed Title I design and authorized the initiation of Title H design and specific long-lead procurements, and September 1998, when Title 11 design will be completed

Antibacterial properties and mechanisms of gold-silver nanocages

Science.gov (United States)

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.

In situ SU-8 silver nanocomposites

Directory of Open Access Journals (Sweden)

Søren V. Fischer

2015-07-01

Full Text Available Nanocomposite materials containing metal nanoparticles are of considerable interest in photonics and optoelectronics applications. However, device fabrication of such materials always encounters the challenge of incorporation of preformed nanoparticles into photoresist materials. As a solution to this problem, an easy new method of fabricating silver nanocomposites by an in situ reduction of precursors within the epoxy-based photoresist SU-8 has been developed. AgNO3 dissolved in acetonitrile and mixed with the epoxy-based photoresist SU-8 forms silver nanoparticles primarily during the pre- and post-exposure soft bake steps at 95 °C. A further high-temperature treatment at 300 °C resulted in the formation of densely homogeneously distributed silver nanoparticles in the photoresist matrix. No particle growth or agglomeration of nanoparticles is observed at this point. The reported new in situ silver nanocomposite materials can be spin coated as homogeneous thin films and structured by using UV lithography. A resolution of 5 µm is achieved in the lithographic process. The UV exposure time is found to be independent of the nanoparticle concentration. The fabricated silver nanocomposites exhibit high plasmonic responses suitable for the development of new optoelectronic and optical sensing devices.

24 CFR 202.12 - Title II.

Science.gov (United States)

2010-04-01

... INSTITUTIONS AND MORTGAGEES Title I and Title II Specific Requirements § 202.12 Title II. (a) Tiered pricing—(1... rate up to two percentage points under the mortgagee's customary lending practices must be based on... after accounting for the value of servicing rights generated by making the loan and other income to the...

Mechanisms of silver diamine fluoride on arresting caries: a literature review.

Science.gov (United States)

Zhao, Irene Shuping; Gao, Sherry Shiqian; Hiraishi, Noriko; Burrow, Michael Francis; Duangthip, Duangporn; Mei, May Lei; Lo, Edward Chin-Man; Chu, Chun-Hung

2018-04-01

To review the evidence regarding the mechanisms of silver diamine fluoride (SDF) for arresting caries. A literature search was conducted using the keywords silver diamine fluoride, and its alternative names, in seven databases: PubMed, Embase and Scopus (English); China National Knowledge Infrastructure (Chinese); Bilioteca Virtual em Saude (Portuguese); Biblioteca Virtual en Salud Espana (Spanish); and Ichushi-Web (Japanese). The titles and abstracts were screened. Full texts were retrieved for publications that studied mechanisms of actions of SDF, including its effects on remineralisation of carious lesions and on cariogenic bacteria. A total of 1,123 publications were identified. Twenty-nine articles were included and they investigated the effect of SDF on cariogenic bacteria and dental hard tissues. Eleven studies investigated the antibacterial properties of SDF. They found that SDF was bactericidal to cariogenic bacteria, mainly Streptococcus mutans. It inhibited the growth of cariogenic biofilms on teeth. Twenty studies reported the remineralisation of demineralised enamel or dentine by SDF. They found that mineral loss of demineralised enamel and dentine was reduced after SDF treatment. A highly mineralised surface rich in calcium and phosphate was formed on arrested carious lesions. Four studies examined the effect of SDF on dentine collagen. They found that SDF inhibited collagenases (matrix metalloproteinases and cysteine cathepsins) and protected dentine collagen from destruction. SDF is a bactericidal agent and reduces the growth of cariogenic bacteria. It inhibits demineralisation and promotes the remineralisation of demineralised enamel and dentine. It also hampers degradation of the dentine collagen. © 2017 FDI World Dental Federation.

Biosynthesis and structural characterization of silver nanoparticles from bacterial isolates

International Nuclear Information System (INIS)

Zaki, Sahar; El Kady, M.F.; Abd-El-Haleem, Desouky

2011-01-01

Graphical abstract: In this study five bacterial isolates belong to different genera were found to be able to biosynthesize silver nanoparticles. Biosynthesis and spectral characterization are reported here. Highlights: → About 300 bacterial isolates were screened for their ability to produce nanosilvers → Five of them were potential candidates for synthesis of silver nanoparticles → Production of silver nanoparticles was examined using UV-Vis, XRD, SEM and EDS. → The presence of nanoparticles with all five bacterial isolates was confirmed. -- Abstract: This study aimed to develop a green process for biosynthesis of silver nanomaterials by some Egyptian bacterial isolates. This target was achieved by screening an in-house culture collection consists of 300 bacterial isolates for silver nanoparticle formation. Through screening process, it was observed that strains belonging to Escherichia coli (S30, S78), Bacillus megaterium (S52), Acinetobacter sp. (S7) and Stenotrophomonas maltophilia (S54) were potential candidates for synthesis of silver nanoparticles. The extracellular production of silver nanoparticles by positive isolates was investigated by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy micrograph showed formation of silver nanoparticles in the range of 15-50 nm. XRD-spectrum of the silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal that produce in hexagonal and cubic crystal configurations with different plane of orientation. In addition, the signals of the silver atoms were observed by EDS-spectrum analysis that confirms the presence of silver nanoparticles (AgNPs) in all positive

Fabrication of silver nanowires via a β-cyclodextrin-derived soft template

Directory of Open Access Journals (Sweden)

C. Y. Liu

2018-07-01

Full Text Available Supramolecular β-cyclodextrin (β-CD was used as a soft template for the fabrication of long silver nanowires. A novel design using self-assembled β-CD for the reduction of silver ions was studied. The concentrations of iron chloride, silver nitrate, and the template were controlling factors for the growth of the silver nanowires. Iron chloride was used to accelerate and facilitate the formation of the silver nanowires and inhibit oxidative etching. However, an excessive concentration of Fe+3 resulted in etching of the silver nanostructures. Furthermore, the silver concentration was another controlling factor. The length of the silver nanowires increased as the concentration of silver cations increased. Nevertheless, an excess concentration of silver cations formed various silver crystalline structures. In this study, the optimal ratio between iron chloride and silver nitrate was determined to be 1:13.3. A maximum length of 20 µm was achieved using a concentration of 0.23 M for the soft template. Moreover, the junction of two growing silver nanowires was observed, forming a long fused nanowire, and some significant boundaries were observed. The observed results were further confirmed using scanning electron microscopy (SEM and transmission electron microscopy (TEM analyses. X-ray diffraction (XRD and energy dispersive spectrometer (EDS analyses were used to indicate the presence of silver and the formation of crystalline materials.

Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

Science.gov (United States)

Martínez-Bernett, D.; Silva-Granados, A.; Correa-Torres, S. N.; Herrera, A.

2016-02-01

It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution.

Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

International Nuclear Information System (INIS)

Martínez-Bernett, D; Silva-Granados, A; Herrera, A; Correa-Torres, S N

2016-01-01

It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO 3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution. (paper)

INIS: Authority list for journal titles

International Nuclear Information System (INIS)

2007-01-01

This is the 33rd revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13 396 journal titles, 2 170 regularly scanned journals and 578 key journals. It was last updated in February 2007. A journal - or periodical - is a continuing publication issued in a succession of discrete parts, usually bearing numbering and/or chronological designations and intended to be continued indefinitely. It is generally published within a defined, fixed interval between issues and normally appears more than once per year. It includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as the Annual Review of Nuclear Science are included, but series titles such as the McGraw-Hill Series in Nuclear Engineering are not. The purpose of this document is to provide descriptive cataloguers with standard elements to include in bibliographic level 'S' of the INIS record. These elements include field (tag) 229 (Full Journal Title), 320 (ISSN) and 321 (CODEN). The full journal title is mandatory, and either the ISSN or the CODEN must be included (both may appear). Instructions on how to use this and other elements of the INIS record format are found in INIS: Guide to Bibliographic Description (IAEA-INIS-1). In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: - In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. - In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. - In Part III, all journals that are regularly scanned by

A simple method of growing silver chloride nanocubes on silver nanowires

International Nuclear Information System (INIS)

Khaligh, Hadi Hosseinzadeh; Goldthorpe, Irene A

2015-01-01

The growth of AgCl nanocubes directly on the sidewalls of Ag nanowires is demonstrated. The nanocubes can be simply obtained through extended low temperature annealing of polyol-synthesized silver nanowires in a vacuum. The length of time and temperature of the anneal and the diameter of the nanowire affect the size and density of the nanocubes obtained. It is hypothesized that the AgCl material is supplied from reactants leftover from the silver nanowire synthesis. This novel hybrid nanostructure may have applications in areas such as photovoltaics, surface enhanced Raman spectroscopy, and photocatalysis. (fast track communication)

Synthesis and anti-lung cancer activity of a novel arsenomolybdate compound

Science.gov (United States)

Zhu, Tian-Tian; Wang, Juan; Chen, Song-Hu

2017-12-01

The new compound based on Wells-Dawson-type arsenomolybdate: [{Cu10(pz)11Cl4}{As2IIIAs2VMo6VMo12VIO62}]·H2O (1) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, X-ray powder diffraction (XRPD), XPS spectroscopy and thermogravimetric analysis (TG). Compound 1 is consisted of two As caps Wells-dawson-type arsenomolybdate and {Cu10(py)11} complexes by chloride bridge. In addition, the antitumor effects of the title compound 1 were studied on three human lung cancer cells (A549, SK-LU-1 and SW1573). The results showed that compared with the positive reference drug carboplatin, compound 1 displayed efficient antitumor activity.

Antimicrobial activity of biopolymeric thin films containing flavonoid natural compounds and silver nanoparticles fabricated by MAPLE: A comparative study

Science.gov (United States)

Cristescu, R.; Visan, A.; Socol, G.; Surdu, A. V.; Oprea, A. E.; Grumezescu, A. M.; Chifiriuc, M. C.; Boehm, R. D.; Yamaleyeva, D.; Taylor, M.; Narayan, R. J.; Chrisey, D. B.

2016-06-01

The purpose of this study was to investigate the interactions between microorganisms, including the planktonic and adherent organisms, and biopolymer (polyvinylpyrrolidone), flavonoid (quercetin dihydrate and resveratrol)-biopolymer, and silver nanoparticles-biopolymer composite thin films that were deposited using matrix assisted pulsed laser evaporation (MAPLE). A pulsed KrF* excimer laser source was used to deposit the aforementioned composite thin films, which were characterized using Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), Grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM). The antimicrobial activity of thin films was quantified using an adapted disk diffusion assay against Gram-positive and Gram-negative bacteria strains. FT-IR, AFM and SEM studies confirmed that MAPLE may be used to fabricate thin films with chemical properties corresponding to the input materials as well as surface properties that are appropriate for medical use. The silver nanoparticles and flavonoid-containing films exhibited an antimicrobial activity both against Gram-positive and Gram-negative bacterial strains demonstrating the potential use of these hybrid systems for the development of novel antimicrobial strategies.

20 CFR 416.573 - How much will we withhold from your title II and title VIII benefits to recover a title XVI...

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title II... Payment of Benefits, Overpayments, and Underpayments § 416.573 How much will we withhold from your title...-due benefits. (b)(1) We will collect the overpayment from current monthly benefits due in a month by...

21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

Science.gov (United States)

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...

Comparison of silver and molybdenum microfocus X-ray sources for single-crystal structure determination

OpenAIRE

Krause, Lennard; Herbst-Irmer, Regine; Sheldrick, George M.; Stalke, Dietmar

2015-01-01

The quality of diffraction data obtained using silver and molybdenum microsources has been compared for six model compounds with a wide range of absorption factors. The experiments were performed on two 30 W air-cooled Incoatec IµS microfocus sources with multilayer optics mounted on a Bruker D8 goniometer with a SMART APEX II CCD detector. All data were analysed, processed and refined using standard Bruker software. The results show that Ag Kα radiation can be beneficial when heavy elements ...

Rapid dehalogenation of pesticides and organics at the interface of reduced graphene oxide-silver nanocomposite.

Science.gov (United States)

Koushik, Dibyashree; Sen Gupta, Soujit; Maliyekkal, Shihabudheen M; Pradeep, T

2016-05-05

This paper reports dehalogenation of various organohalides, especially aliphatic halocarbons and pesticides at reduced graphene oxide-silver nanocomposite (RGO@Ag). Several pesticides as well as chlorinated and fluorinated alkyl halides were chosen for this purpose. The composite and the products of degradation were characterized thoroughly by means of various microscopic and spectroscopic techniques. A sequential two-step mechanism involving dehalogenation of the target pollutants by silver nanoparticles followed by adsorption of the degraded compounds onto RGO was revealed. The composite showed unusual adsorption capacity, as high as 1534 mg/g, which facilitated the complete removal of the pollutants. Irrespective of the pollutants tested, a pseudo-second-order rate equation best described the adsorption kinetics. The affinity of the composite manifested chemical differences. The high adsorption capacity and re-usability makes the composite an excellent substrate for purification of water. Copyright © 2016 Elsevier B.V. All rights reserved.

Biosynthesis of Silver Nanoparticles and Its Applications

International Nuclear Information System (INIS)

Firdhouse, M. J.; Lalitha, P.

2015-01-01

Silver nanoparticles possess unique properties which find myriad applications such as antimicrobial, anticancer, larvicidal, catalytic, and wound healing activities. Biogenic syntheses of silver nanoparticles using plants and their pharmacological and other potential applications are gaining momentum owing to its assured rewards. This critical review is aimed at providing an insight into the phyto mediated synthesis of silver nanoparticles, its significant applications in various fields, and characterization techniques involved.

Spatially controlled synthesis of silver nanoparticles and nanowires by photosensitized reduction

Energy Technology Data Exchange (ETDEWEB)

Jradi, S; Zeng, X H; Plain, J; Royer, P; Bachelot, R; Akil, S [Laboratoire de Nanotechnologie et d' Instrumentation Optique, ICD CNRS FRE 2848, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France); Balan, L; Lougnot, D J; Soppera, O; Vidal, L, E-mail: lavinia.balan@uha.fr [Institut de Science des Materiaux de Mulhouse CNRS LRC 7228, 15 rue Jean Starcky, 68057 Mulhouse (France)

2010-03-05

The present paper reports on the spatially controlled synthesis of silver nanoparticles (NPs) and silver nanowires by photosensitized reduction. In a first approach, direct photogeneration of silver NPs at the end of an optical fiber was carried out. Control of both size and density of silver NPs was possible by changing the photonic conditions. In a further development, a photochemically assisted procedure allowing silver to be deposited at the surface of a polymer microtip was implemented. Finally, polymer tips terminated by silver nanowires were fabricated by simultaneous photopolymerization and silver photoreduction. The silver NPs were characterized by UV-visible spectroscopy and scanning electron microscopy.

Synthesis and characterization of silver nanoparticles in AOT microemulsion system

International Nuclear Information System (INIS)

Zhang Wanzhong; Qiao Xueliang; Chen Jianguo

2006-01-01

Colloidal silver nanoparticles have been synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of one microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another microemulsion as reducing agent, dodecane as the oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The UV-vis absorption spectra and transmission electron microscopy (TEM) have been used to trace the growth process and elucidate the structure of the silver nanoparticles. UV-vis spectra show that the Ag 4 + intermediates formed at early stages of the reaction and then the clusters grow or aggregate to larger nanoparticles. TEM micrographs confirm that the silver nanoparticles are all spherical. The resulting particles have a very narrow size distribution. Meanwhile, the diameter size of the particles is so small that the smallest mean diameter is only 1.6nm. IR results show that the surfactant molecules are strongly adsorbed on the surface of silver particles through a coordination bond between the silver atom and the sulfonic group of AOT molecules, which endows the particles with a good stability in oil solvents. As dodecane is used as oil solvent to prepare silver nanoparticles, the formed nano-silver sol is almost nontoxic. As a result, the silver nanoparticles need not be separated from the reaction solution and the silver sol may be directly used in antibacterial fields

Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

Energy Technology Data Exchange (ETDEWEB)

Silva, Ana Rosa; Unali, Gianfranco, E-mail: ana.rosa.silva@ua.pt [Structured Materials Expertise Group, Unilever Discover Port Sunlight, Quarry Road East, Bebington CH63 3JW (United Kingdom)

2011-08-05

Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu{sub 2}O) nanocomposites.

Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

International Nuclear Information System (INIS)

Silva, Ana Rosa; Unali, Gianfranco

2011-01-01

Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu 2 O) nanocomposites.

Dermal exposure potential from textiles that contain silver nanoparticles.

Science.gov (United States)

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%); Pmasterbatch 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

Science.gov (United States)

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.

Browse Title Index

African Journals Online (AJOL)

Items 201 - 250 of 449 ... Vol 65 (2012), Nano-Fe3O4/O2: Green, Magnetic and Reusable Catalytic System for the ... Vol 70 (2017), Novel silver-doped NiTiO3: auto-combustion synthesis, ... K Wang, H Wang, R Wang, J Key, V Linkov, S Ji.

Radiation synthesis of silver nanostructures in cotton matrix

International Nuclear Information System (INIS)

Chmielewska, Dagmara; Sartowska, Bożena

2012-01-01

Cotton is one of the most popular natural fibres, composed mainly of cellulose, which finds a wide range of applications in paper, textile and health care products industry. Researchers have focused their interest on the synthesis of cotton nanocomposites, which enhances its mechanical, thermal and antimicrobial properties by the incorporation of various nanoparticles into the cotton matrix. Silver is one of the most popular antimicrobial agents with a wide spectrum of antibacterial and antifungal activity that results from a complex mechanism of its interactions with the cells of harmful microorganism. In this work, electron beam radiation was applied to synthesise silver nanostructures in cotton fibres. Investigations of the influence of the initial silver salt concentration on the size and distribution of the obtained silver nanostructures were carried out. A detailed characterisation of these nanocomposites with SEM-BSE and EDS methods was performed. TGA and DSC analyses were performed to assess the influence of different size silver nanoparticles and the effect of electron beam irradiation on the thermal properties of cotton fibres. A microbiological investigation to determine the antibacterial activity of Ag-cotton nanocomposites was carried out. - Highlights: ► Ag NPs embedded in cotton matrix were synthesised by electron beam irradiation. ► Concentration of silver salt solution influences on size of silver nanoparticles. ► Silver content as well as irradiation affect thermal properties of cotton fabrics. ► Ag-cotton nanocomposites exhibit antibacterial activity against bacteria and fungi.

[Toxicological evaluation of nanosized colloidal silver, stabilized with polyvinylpyrrolidone. I. Characterization of nanomaterial, integral, hematological parameters, level of thiol compounds and liver cell apoptosis].

Science.gov (United States)

Shumakova, A A; Shipelin, V A; Sidorova, Yu S; Trushina, E N; Mustafina, O K; Pridvorova, S M; Gmoshinsky, I V; Khotimchenko, S A

2015-01-01

Nano-sized colloidal silver (NCS) is currently one of the most widely used nanomaterials in medicine and consumer’s products. Nanoparticles (NPs) of silver, in addition to the direct exposition through products may expose human via various environmental objects. The aim of the study is to assess the safe doses of silver NP received orally. The investigated NCS contained silver NPs with diameter of 10–60 nm, predominantly with a nearly spherical form stabilized with polyvinylpyrrolidone (PVP). The experiment was performed during 92 days in 5 groups of male Wistar rats (n=15 in each group), receiving a balanced semisynthetic diet. Animal of group 1 (control) received vehicle (deionized water) intragastrically for 30 days and then with food, groups from 2nd to 4th – PVP and groups from 3rd to 5th NCS, in doses respectively, 0.1; 1.0 and 10 mg/kg body weight (b.w.) in terms of silver. The dose of PVP in groups from 2nd to 5th did not differ, amounting to 200 mg/kg b.w. During the experiment, the weight gain, skin condition, activity, stool, cognitive function were assessed. At the end of the feeding period weight of internal organs, intestinal wall permeability to protein macromolecules, liver thiols, standard values of blood erythrocytes, leukocytes and platelets, hepatocyte apoptosis by flow cytometry were studied. These results suggest that in terms of weight gain, lung relative mass, average erythrocyte volume, hemoglobin content and concentration in erythrocytes, the relative proportion of lymphocytes and neutrophils adverse changes have been observed at a dose of 10 mg NPs per kg of b.w. At lower levels of exposure (0.1 and 1.0 mg/kg b.w.) some specific changes were also observed (in terms of thiols pool in liver, cognitive function, relative abundance of monocytes, the number of dead hepatocytes), which, however, did not possess an unambiguous dependence on the dose. Possible mechanisms of the toxic action of the NCS have been discussed.

Anesthetic activity and bio-guided fractionation of the essential oil of Aloysia gratissima (Gillies & Hook.) Tronc. in silver catfish Rhamdia quelen.

Science.gov (United States)

Benovit, Simone C; Silva, Lenise L; Salbego, Joseânia; Loro, Vania L; Mallmann, Carlos A; Baldisserotto, Bernardo; Flores, Erico M M; Heinzmann, Berta M

2015-09-01

This work aimed to determine the efficacy of the essential oil of A. gratissima as anesthetic for silver catfish, and to perform the bio-guided fractionation of essential oil aiming to isolate compounds responsible for the noted effects. Fish were submitted to anesthesia bath with essential oil, its fractions and isolated compounds to determine time of anesthetic induction and recovery. Eugenol (50 mg L(-1)) was used as positive control. Essential oil of A. gratissima was effective as an anesthetic at concentrations of 300 to 900 mg L(-1). Fish presented involuntary muscle contractions during induction and recovery. The bio-guided fractionation of essential oil furnished E-(-)-pinocamphone, (-)-caryophyllene oxide, (-)-guaiol and (+)-spathulenol. E-(-)-pinocamphone caused the same side effects observed for essential oil. (-)-Caryophyllene oxide, (-)-guaiol and (+)-spathulenol showed only sedative effects at proportional concentrations to those of the constituents in essential oil. (+)-Spathulenol (51.2 mg L(-1)) promoted deep anesthesia without side effects. A higher concentration of (+)-spathulenol, and lower or absent amounts ofE-(-)-pinocamphone could contribute to increase the activity and safety of the essential oil of A. gratissima. (+)-Spathulenol showed potent sedative and anesthetic activities in silver catfish, and could be considered as a viable compound for the development of a new anesthetic.

Topical silver for preventing wound infection

NARCIS (Netherlands)

Storm-Versloot, Marja N.; Vos, Cornelis G.; Ubbink, Dirk T.; Vermeulen, Hester

2010-01-01

BACKGROUND: Silver-containing treatments are popular and used in wound treatments to combat a broad spectrum of pathogens, but evidence of their effectiveness in preventing wound infection or promoting healing is lacking. OBJECTIVES: To establish the effects of silver-containing wound dressings and

Properties of silver chloride track detectors

International Nuclear Information System (INIS)

Dmitriev, V.D.; Kocherov, N.P.; Novikova, N.R.; Perfilov, N.A.

1976-01-01

The experiments on preparation of silver chloride track detectors and their properties are described. The results of X-ray structural analysis and data on sensitivity to charged particles and actinic light of silver chloride crystals, doped with several elements, are presented. (orig.) [de

Surface-enhanced Raman scattering from silver electrodes

International Nuclear Information System (INIS)

Trott, G.R.

1982-01-01

The chemical and physical origins of the anomalously large enhancement of the Raman scattering cross section for molecules adsorbed on silver electrodes in an electrochemical cell were investigated. The effect of the chemical reactions which occur during the anodization/activation procedure were studied using the Ag-CN system. It was shown that the function of the anodization process is to roughen the electrode surface and create an activated site for bonding to the cyanide. A new nonelectrochemical technique for activating the silver surface, along with a study of the enhanced cyanide Raman scattering in different background electrolytes, showed that the Raman active entity on the surface must be a silver-cyanide complex. In order to study the physical mechanism of the enhancement, the angular dependence of the scattered radiation was measured from pyridine adsorbed on an evaporated silver electrode. Both polycrystalline and single crystalline silver films were used. The angular dependence of the scattered radiation from these films showed that the metal surface was controlling the directional properties of the scattered radiation, and not the polarizability tensor of the adsorbate. Based on these experimental results, it was concluded that for weakly roughened silver electrodes the source of the anomalous enhancement is due to a resonant Raman scattering process

Silver nanoparticles in X-ray biomedical applications

International Nuclear Information System (INIS)

Mattea, Facundo; Vedelago, José; Malano, Francisco; Gomez, Cesar; Strumia, Miriam C.

2017-01-01

The fluorescence of silver nanoparticles or ions can be used for detection and dose enhancement purposes in X-ray irradiation applications. This study is focused on the full integration of the chemical synthesis of silver nanoparticles suitable for dosimetric and radiological purposes with characteristics that can be exploited in radiotherapy and radiodiagnostic. A narrow size distribution and a compatible stabilizing agent is often desired in order to obtain homogeneous behaviors in nanoparticle suspension. With the method proposed in this study, nanoparticles ranging from 5 to 20 nm were obtained. The fluorescence of aqueous suspensions of silver nanoparticles has been measured experimentally and simulated with the Monte Carlo PENELOPE code for different silver concentrations and geometrical configurations. Finally, the feasibility of using these nanoparticles for the elaboration of Fricke gel dosimeters has been tested obtaining a dose enhancement when compared with the same material irradiated below the silver K-edge. - Highlights: • A method to compare NP's fluorescence in simulations and experiments was developed. • Silver nanoparticles suitable for typical dosimetry systems were synthesized. • Concentration and depth of a Ag doped volume was measured with X-ray fluorescence. • A feasibility test of Ag NPs in Fricke gel dosimetry was performed. • Good agreement between Monte Carlo simulations and experiments was obtained.

Crystal structure and optical properties of silver nanorings

Science.gov (United States)

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.

New Strategies in the Development of Antimicrobial Coatings: The Example of Increasing Usage of Silver and Silver Nanoparticles

Directory of Open Access Journals (Sweden)

Leo H. Koole

2011-01-01

Full Text Available Bacterial infection from medical devices is a major problem and accounts for an increasing number of deaths as well as high medical costs. Many different strategies have been developed to decrease the incidence of medical device related infection. One way to prevent infection is by modifying the surface of the devices in such a way that no bacterial adhesion can occur. This requires modification of the complete surface with, mostly, hydrophilic polymeric surface coatings. These materials are designed to be non-fouling, meaning that protein adsorption and subsequent microbial adhesion are minimized. Incorporation of antimicrobial agents in the bulk material or as a surface coating has been considered a viable alternative for systemic application of antibiotics. However, the manifestation of more and more multi-drug resistant bacterial strains restrains the use of antibiotics in a preventive strategy. The application of silver nanoparticles on the surface of medical devices has been used to prevent bacterial adhesion and subsequent biofilm formation. The nanoparticles are either deposited directly on the device surface, or applied in a polymeric surface coating. The silver is slowly released from the surface, thereby killing the bacteria present near the surface. In the last decade there has been a surplus of studies applying the concept of silver nanoparticles as an antimicrobial agent on a range of different medical devices. The main problem however is that the exact antimicrobial mechanism of silver remains unclear. Additionally, the antimicrobial efficacy of silver on medical devices varies to a great extent. Here we will review existing antimicrobial coating strategies and discuss the use of silver or silver nanoparticles on surfaces that are designed to prevent medical device related infections.

Antimicrobial, Mechanical and Thermal Studies of Silver Particle-Loaded Polyurethane

Directory of Open Access Journals (Sweden)

Deepen Paul

2013-12-01

Full Text Available Silver-particle-incorporated polyurethane films were evaluated for antimicrobial activity towards two different bacteria: Escherichia coli (E. coli and Staphylococcus aureus (S. aureus. Distributed silver particles sourced from silver nitrate, silver lactate and preformed silver nanoparticles were mixed with polyurethane (PU and variously characterized by field emission scanning electron microscopy (FESEM, fourier transform infra-red (FTIR spectroscopy, X-ray diffraction (XRD and contact angle measurement. Antibacterial activity against E.coli was confirmed for films loaded with 10% (w/w AgNO3, 1% and 10% (w/w Ag lactate and preformed Ag nanoparticles. All were active against S. aureus, but Ag nanoparticles loaded with PU had a minor effect. The apparent antibacterial performance of Ag lactate-loaded PU is better than other Ag ion-loaded films, revealed from the zone of inhibition study. The better performance of silver lactate-loaded PU was the likely result of a porous PU structure. FESEM and FTIR indicated direct interaction of silver with the PU backbone, and XRD patterns confirmed that face-centred cubic-type silver, representative of Ag metal, was present. Young’s modulus, tensile strength and the hardness of silver containing PU films were not adversely affected and possibly marginally increased with silver incorporation. Dynamic mechanical analysis (DMA indicated greater thermal stability.

INIS: Authority list for journal titles

International Nuclear Information System (INIS)

2008-01-01

This is the 34th revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13 538 journal titles, 2 106 regularly scanned journals and 613 key journals. It was last updated in February 2008. A journal - or periodical - is a continuing publication issued in a succession of discrete parts, usually bearing numbering and/or chronological designations and intended to be continued indefinitely. It is generally published within a defined, fixed interval between issues and normally appears more than once per year. It includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as the Annual Review of Nuclear Science are included, but series titles such as the McGraw-Hill Series in Nuclear Engineering are not. The purpose of this document is to provide descriptive cataloguers with standard elements to include in bibliographic level 'S' of the INIS record. These elements include field (tag) 229 (Full Journal Title), 320 (ISSN) and 321 (CODEN). The full journal title is mandatory, and either the ISSN or the CODEN must be included (both may appear). Instructions on how to use this and other elements of the INIS record format are found in INIS: Guide to Bibliographic Description (IAEA-INIS-1). In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: - In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. - In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. - In Part III, all journals that are regularly scanned by

Synthesis and optical properties of silver nanoparticles

Science.gov (United States)

Singh, Jaiveer; Kaurav, Netram; Choudhary, K. K.; Okram, Gunadhor S.

2015-07-01

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.

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

Science.gov (United States)

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.

Bactericidal properties of silver films on intramedullary implants

Science.gov (United States)

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.

Subchronic oral toxicity of silver nanoparticles

Directory of Open Access Journals (Sweden)

Kim Yong

2010-08-01

Full Text Available Abstract Background The antibacterial effect of silver nanoparticles has resulted in their extensive application in health, electronic, consumer, medicinal, pesticide, and home products; however, silver nanoparticles remain a controversial area of research with respect to their toxicity in biological and ecological systems. Results This study tested the oral toxicity of silver nanoparticles (56 nm over a period of 13 weeks (90 days in F344 rats following Organization for Economic Cooperation and Development (OECD test guideline 408 and Good Laboratory Practices (GLP. Five-week-old rats, weighing about 99 g for the males and 92 g for the females, were divided into four 4 groups (10 rats in each group: vehicle control, low-dose (30 mg/kg, middle-dose (125 mg/kg, and high-dose (500 mg/kg. After 90 days of exposure, clinical chemistry, hematology, histopathology, and silver distribution were studied. There was a significant decrease (P Conclusions The target organ for the silver nanoparticles was found to be the liver in both the male and female rats. A NOAEL (no observable adverse effect level of 30 mg/kg and LOAEL (lowest observable adverse effect level of 125 mg/kg are suggested from the present study.

High temperature creep of single crystals of gold, silver and solid solution gold silver 50-50

International Nuclear Information System (INIS)

Dorizzi, Paul

1973-01-01

We have studied in compression creep along a direction, single crystals of gold, silver and a 50-50 gold-silver solid solution. The experiments were made at temperatures above 0.7 Tf. We have shown that under these conditions and for these three metals a new slip system is operating: the deformation is due to the slip of dislocations having a 1/2 burgers vector on the {110} planes. For gold the activation energy for creep is equal to the self-diffusion energy. We found the same result for silver when the contribution of divacancies to the self-diffusion energy is taken into account. For the alloy the activation energy for creep is very close to the self-diffusion energy of gold in a 50-50 gold-silver alloy, gold being the slower diffusing species in the alloy. The curves giving the creep rate versus the stress can be fitted with the following laws: ε 0 = σ 5 for gold; ε 0 = σ 2,2 for silver and ε 0 = σ 2,5 for the alloy. The dislocation substructure was studied using the crystalline contrast given by the electron microprobe. This new method gives images which are very sensitive to the sub-grains misorientation. The substructure is made of parallelepipedic cells divided by tilt boundaries that are perpendicular to the {110} slip planes. (author) [fr

Silver percutaneous absorption after exposure to silver nanoparticles: a comparison study of three human skin graft samples used for clinical applications.

Science.gov (United States)

Bianco, C; Adami, G; Crosera, M; Larese, F; Casarin, S; Castagnoli, C; Stella, M; Maina, G

2014-11-01

Silver nanoparticles (AgNPs) are increasingly applied to a wide range of materials for biomedical use. These enable a close contact with human skin, thanks to the large release of silver ions that is responsible for a broad spectrum of antimicrobial activity. Silver can permeate the skin; however, there are no data available on silver permeation through skin grafts commonly used in burns recovery. The aim of our study was to evaluate silver penetration using fresh, cryopreserved, and glycerolized human skin grafts after exposure to a suspension of AgNPs in synthetic sweat using a Franz diffusion cell apparatus for 24 h. Silver permeation profiles revealed a significantly higher permeation through glycerolized skin compared with both fresh and cryopreserved skin: 24-h silver flux penetration was 0.2 ng cm(-2) h(-1) (lag time: 8.2 h) for fresh skin, 0.3 ng cm(-2) h(-1) (lag time: 10.9 h) for cryopreserved skin, and 3.8 ng cm(-2) h(-1) (lag time: 6.3 h) for glycerolized skin. Permeation through glycerolized skin is significantly higher compared to both fresh and cryopreserved skin. This result can generate relevant clinical implications for burns treatment with products containing AgNPs. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Land Titles and Rice Production in Vietnam

DEFF Research Database (Denmark)

Van Den Broeck, Katleen; Newman, Carol; Tarp, Finn

In most of the empirical literature on land titling, the household is regarded as unitary, and land rights are found to have ambiguous effects on land allocation, investment and productivity. Using data from 12 provinces in Vietnam, we diversify land titles, and show in a household fixed effects...... analysis of plot level rice yields that land titles are indeed important. Only exclusively held titles have the expected positive effects, and the positive effect on yields is found in male headed households. Furthermore, a household level rice yield function reveals that exclusive user rights...... are inefficiency decreasing, while jointly held user rights have no efficiency effects. Finally, once the gender of the head of household is controlled for, exclusively held female titles have a greater positive effect on the efficiency of the household than that of male held titles...

Colloidal silver: a novel treatment for Staphylococcus aureus biofilms?

Science.gov (United States)

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 colloidal silver (mean differences = -4.0681 and -4.0675μm(3) /μm(2) , respectively, p Colloidal silver directly attenuates in vitro S. aureus biofilms. © 2014 ARS-AAOA, LLC.

The sorption of silver by poorly crystallized manganese oxides

Science.gov (United States)

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.

Ground configurations of highly ionized silver

International Nuclear Information System (INIS)

Denne, B.; Hinnov, E.; Cohen, S.; Timberlake, J.

1985-01-01

A number of lines mostly corresponding to magnetic-dipole transitions in the n = 3 and n = 4 shells of silver have been identified. The lines were observed in the Princeton Large Torus tokamak discharges, into which silver was injected by means of the laser-ablation method

Analysis of impurities in silver matrix by atomic absorption spectrophotometry

International Nuclear Information System (INIS)

Hussain, R.; Ishaque, M.; Mohammad, D.

1999-01-01

A procedure for the analysis of aluminium, chromium, copper, lead, mercury, nickel and zinc mainly using flame lens atomic absorption spectrophotometry has been described. The results depict that the presence of silver does not introduce any significant interference, when standards are prepared in matching silver matrix solutions. The calibration curves obey the straight-line equations passing through the origin. Thus the separation of silver matrix from the analyte solutions is not necessary. The method has successfully been applied for the analysis of silver foils, wires, battery grade silver oxides and silver nitrate samples containing analyte elements in the concentration range 2 to 40 ppm. (author)

Chromaticity and Glossiness of Gold, Silver, and Bronze Colors

Directory of Open Access Journals (Sweden)

Tomohisa Matsumoto

2011-05-01

Full Text Available Appearance of metallic colors, such as gold, silver and bronze, depends on chromaticity and glossiness of a surface. We aim to obtain the chromaticity region of gold, silver, and bronze by using CG simulated surfaces with various glossiness. The physical glossiness was defined by the intensity ratio of specular reflectance of the surface stimulus. The observer estimated degree of perceived glossiness, and also degree of gold, silver, or bronze appearance of the stimulus with a physical glossiness and a chromaticity. The results showed that the stimulus began to appear gold, silver or bronze at a certain chromaticity point only when the stimulus had glossiness. The chromaticity range, where gold, silver and bronze colors were observed, expanded as the degree of glossiness increased. Furthermore the ratio of the degree of gold, silver or bronze colors to that of glossiness of the stimulus was found to be different among the chromaticity points of the stimulus. This ratio was highest with highly saturated stimuli for gold and bronze colors, and with achromatic stimuli for silver color.

Recovery of Silver and Gold from Copper Anode Slimes

Science.gov (United States)

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.

Silver Nanoparticles and Studies on Using in Poultry Nutrition

Directory of Open Access Journals (Sweden)

Mehmet Akif Özcan

2015-02-01

Full Text Available The use of colloidal silver as an antibiotic was becoming widespread until the 1940s. However, with the discovery of antibiotics, usage of colloidal silver had been reduced because of being expensive. The fact that bacteria develop resistance to antibiotics lead to prohibiton the usage of antibiotics in poultry diets as growth promoters. Based on these developments reuse of colloidal silver has been raised as an alternative to antibiotics. Without prejudice to the beneficial enzymes, colloidal silver disables certain enzymes needed by bacteria, viruses, yeasts, and fungus resulting in the destruction of these enzymes. It is reported that increase in surface area of nano-particles of silver increase antibacterial activity. The most important limitation on the widespread use of silver nanoparticles as feed additives is uncertainty about the possible toxic effects. In this review, studies for the use of colloidal silver particles in poultry feed were evaluated and tried to seek answer the question “may be a new resource that can be used as an alternative to antibiotics?

The oxidative dehydrogenation of methanol to formaldehyde over silver catalysts in relation to the oxygen-silver interaction

NARCIS (Netherlands)

Lefferts, Leonardus; van Ommen, J.G.; Ross, J.R.H.

1986-01-01

The properties of silver in the oxidative dehydrogenation of methanol were studied in a flow reactor under near industrial conditions. The influences of temperature, concentration of both reactants, gas velocity, space velocity, the form of the silver catalyst and surface composition of the catalyst

Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold

International Nuclear Information System (INIS)

Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

2014-01-01

The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO 3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. - Highlights: • The hydroxyapatite and silver nanoparticles were grown on the polyurethane scaffold • The hydroxyapatite/polyurethane acts as reducing agent, stabilizer and matrix for Ag • The samples were well characterized by SEM-EDX, XRD, XPS, UV-visible spectroscopy • The hydroxyapatite/silver polyurethane scaffold shows antibacterial property

Biosynthesis of silver nanoparticles | Silambarasan | African Journal ...

African Journals Online (AJOL)

friendly and exciting approach. Several microorganisms have been known to produce silver nanoparticles (Ag NPs), when silver molecules are exposed either intracellularly or extracellularly. Intracellular synthesis may accomplish a better ...

Silver nasal sprays: misleading Internet marketing.

Science.gov (United States)

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.

Formation of silver microbelt structures by laser irradiation of silver nanoparticles in ethanol

Directory of Open Access Journals (Sweden)

Zamiri R

2011-10-01

Full Text Available Reza Zamiri1, Azmi Zakaria1,2, Mohd Shahril Husin1, Zaidan Abd Wahab1, Forough Kalaei Nazarpour3 1Department of Physics, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 3Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia Abstract: In the present work, we prepared silver nanoparticles by laser ablation of pure silver plate in ethanol and then irradiated the silver nanoparticles using a 532 nm Q-switched Nd:YAG pulsed laser. Transmission electron microscopic images of the sample after irradiation clearly showed formation of big structures, such as microrods and microbelts in ethanol. The obtained microbelts had a width of about 0.166 µm and a length of 1.472 µm. The reason for the formation of such a big structure is the tendency of the nanoparticles to aggregate in ethanol before irradiation, which causes fusion of the nanoparticles. Keywords: nanomaterial, laser ablation, nanoparticles

Biosynthesis of Silver and Gold Crystals Using Grapefruit Extract

OpenAIRE

Chen Long; Wang Jianli; Wang Hongfeng; Qi Zhaopeng; Zheng Yuchuan; Wang Junbo; Pan Le; Chang Guanru; Yang Yongmei

2016-01-01

In this paper, biological synthesis of silver and gold crystals using grapefruit extract is reported. On treatment of aqueous solutions of silver nitrate and chloroauric acid with grapefruit extract, the formation of stable silver and gold particles at high concentrations is observed to occur. The silver particles formed are quasi-spherical or irregular with sizes ranging from several hundred nanometers to several microns. The gold quasi-spheres with holes on surfaces and with diameters rangi...

Silver nanoparticles: Synthesis methods, bio-applications and properties.

Science.gov (United States)

Abbasi, Elham; Milani, Morteza; Fekri Aval, Sedigheh; Kouhi, Mohammad; Akbarzadeh, Abolfazl; Tayefi Nasrabadi, Hamid; Nikasa, Parisa; Joo, San Woo; Hanifehpour, Younes; Nejati-Koshki, Kazem; Samiei, Mohammad

2016-01-01

Silver nanoparticles size makes wide range of new applications in various fields of industry. Synthesis of noble metal nanoparticles for applications such as catalysis, electronics, optics, environmental and biotechnology is an area of constant interest. Two main methods for Silver nanoparticles are the physical and chemical methods. The problem with these methods is absorption of toxic substances onto them. Green synthesis approaches overcome this limitation. Silver nanoparticles size makes wide range of new applications in various fields of industry. This article summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations with respect to the biomedical applicability and regulatory requirements concerning silver nanoparticles.

Silver nano fabrication using leaf disc of Passiflora foetida Linn

Science.gov (United States)

Lade, Bipin D.; Patil, Anita S.

2017-06-01

The main purpose of the experiment is to develop a greener low cost SNP fabrication steps using factories of secondary metabolites from Passiflora leaf extract. Here, the leaf extraction process is omitted, and instead a leaf disc was used for stable SNP fabricated by optimizing parameters such as a circular leaf disc of 2 cm (1, 2, 3, 4, 5) instead of leaf extract and grade of pH (7, 8, 9, 11). The SNP synthesis reaction is tried under room temperature, sun, UV and dark condition. The leaf disc preparation steps are also discussed in details. The SNP obtained using (1 mM: 100 ml AgNO3+ singular leaf disc: pH 9, 11) is applied against featured room temperature and sun condition. The UV spectroscopic analysis confirms that sun rays synthesized SNP yields stable nano particles. The FTIR analysis confirms a large number of functional groups such as alkanes, alkyne, amines, aliphatic amine, carboxylic acid; nitro-compound, alcohol, saturated aldehyde and phenols involved in reduction of silver salt to zero valent ions. The leaf disc mediated synthesis of silver nanoparticles, minimizes leaf extract preparation step and eligible for stable SNP synthesis. The methods sun and room temperature based nano particles synthesized within 10 min would be use certainly for antimicrobial activity.

A new antibacterial silver(I) complex incorporating 2,5-dimethylpyrazine and the anti-inflammatory diclofenac.

Science.gov (United States)

Hamamci Alisir, Sevim; Dege, Necmi

2016-12-01

Ag I -containing coordination complexes have attracted attention because of their photoluminescence properties and antimicrobial activities and, in principle, these properties depend on the nature of the structural topologies. A novel two-dimensional silver(I) complex with the anti-inflammatory diclofenac molecule, namely bis{μ-2-[2-(2,6-dichloroanilino)phenyl]acetato-κ 3 O,O':O}bis(μ-2,5-dimethylpyrazine-κ 2 N:N')silver(I), [Ag 2 (C 14 H 10 Cl 2 NO 2 ) 2 (C 6 H 8 N 2 )] n , (I), has been synthesized and characterized by single-crystal X-ray diffraction, revealing that the Ag I ions are chelated by the carboxylate groups of the anionic 2-[2-(2,6-dichloroanilino)phenyl]acetate (dicl) ligand in a μ 3 -η 1 :η 2 coordination mode. Each dicl ligand links three Ag I atoms to generate a one-dimensional infinite chain. Adjacent chains are connected through 2,5-dimethylpyrazine (dmpyz) ligands to form a two-dimensional layer structure parallel to the crystallographic bc plane. The layers are further connected by C-H...π interactions to generate a three-dimensional supramolecular structure. Additionally, the most striking feature is that the structure contains an intramolecular C-H ...Ag anagostic interaction. Furthermore, the title complex has been tested for its in vitro antibacterial activity and is determined to be highly effective on the studied microorganisms.

In vitro cytotoxity of silver: implication for clinical wound care.

Science.gov (United States)

Poon, Vincent K M; Burd, Andrew

2004-03-01

In this study, we look at the cytotoxic effects of silver on keratinocytes and fibroblasts. We have assessed the viability of monolayer cultures using the MTT and BrdU assays. The composition of the culture medium and also the culture technique were modified to assess the effects of culture 'environment' on the susceptibility of the cells to the toxic action of silver. Further in vitro, experiments were performed using tissue culture models to allow cellular behavior in three dimensional planes which more closely simulated in vivo behavior. The silver source was both silver released from silver nitrate solution but also nanocrystalline silver released from a commercially available dressing. The results show that silver is highly toxic to both keratinocytes and fibroblasts in monolayer culture. When using optimized and individualized culture the fibroblasts appear to be more sensitive to silver than keratinocytes. However, when both cell types were grown in the same medium their viability was the same. Using tissue culture models again indicated an 'environmental effect' with decreased sensitivity of the cells to the cytotoxic effects of the silver. Nevertheless in these studies the toxic dose of skin cells ranging from 7 x 10(-4) to 55 x 10(-4)% was similar to that of bacteria. These results suggest that consideration of the cytotoxic effects of silver and silver-based products should be taken when deciding on dressings for specific wound care strategies. This is important when using keratinocyte culture, in situ, which is playing an increasing role in contemporary wound and burn care.

Biological sensing with surface-enhanced Raman spectroscopy (SERS) using a facile and rapid silver colloid-based synthesis technique

Science.gov (United States)

Smyth, C.; Mehigan, S.; Rakovich, Y. P.; Bell, S. E. J.; McCabe, E. M.

2011-03-01

Optical techniques towards the realisation of sensitive and selective biosensing platforms have received a considerable amount of attention in recent times. Techniques based on interferometry, surface plasmon resonance, field-effect transistors and waveguides have all proved popular, and in particular, spectroscopy offers a large range of options. Raman spectroscopy has always been viewed as an information rich technique in which the vibrational frequencies reveal a lot about the structure of a compound. The issue with Raman spectroscopy has traditionally been that its rather low cross section leads to poor limits-of-detection. In response to this problem, Surface-enhanced Raman Scattering (SERS), which increases sensitivity by bringing the sample in contact with many types of enhanceing substrates, has been developed. Here we discuss a facile and rapid technique for the detection of pterins using colloidal silver suspensions. Pteridine compounds are a family of biochemicals, heterocyclic in structure, and employed in nature as components of colour pigmentation and also as facilitators for many metabolic pathways, particularly those relating to the amino acid hydroxylases. In this work, xanthopterin, isoxanthopterin and 7,8- dihydrobiopterin have been examined whilst absorbed to SERS-active silver colloids. SERS, while far more sensitive than regular Raman spectroscopy, has its own issues relating to the reproducibility of substrates. In order to obtain quantitative data for the pteridine compounds mentioned above, exploratory studies of methods for introducing an internal standard for normalisation of the signals have been carried out.e

Carbon paste electrode modified with silver thimerosal for the potentiometric flow injection analysis of silver(I)

Energy Technology Data Exchange (ETDEWEB)

Ibrahim, Hosny [Chemistry Department, Faculty of Science, Cairo University, Cairo (Egypt)]. E-mail: dr_hosny@yahoo.com

2005-07-27

The utility of carbon paste electrode modified with silver ethylmercurythiosalicylate (silver thimerosal) in both static mode and flow injection analysis (FIA) is demonstrated. The electrode was fully characterized in terms of composition, response time, thermal stability, usable pH and ionic strength ranges. It has been shown that diisononyl phthalate (DINP) acts as more suitable solvent mediator for preparation of the electrode, which exhibits linear response range to Ag(I) extending from 5.0 x 10{sup -7} to 1.0 x 10{sup -3} M with detection limit of 2.5 x 10{sup -7} M and Nernstian slope of 59.3 {+-} 1.0 mV/decade. The proposed chemically modified carbon paste electrode shows a very good selectivity for Ag(I) over a wide variety of metal ions and successfully used for the determination of the silver content of silver sulphadiazine (burning cream) and developed radiological films. The electrode was also used as an indicator electrode in the potentiometric titration of thiopental and thimerosal with AgNO{sub 3}.

Biosynthesis, characterization, and antimicrobial applications of silver nanoparticles.

Science.gov (United States)

Singh, Priyanka; Kim, Yeon Ju; Singh, Hina; Wang, Chao; Hwang, Kyu Hyon; Farh, Mohamed El-Agamy; Yang, Deok Chun

2015-01-01

In the present study, the strain Brevibacterium frigoritolerans DC2 was explored for the efficient and extracellular synthesis of silver nanoparticles. These biosynthesized silver nanoparticles were characterized by ultraviolet-visible spectrophotometry, which detected the formation of silver nanoparticles in the reaction mixture and showed a maximum absorbance at 420 nm. In addition, field emission transmission electron microscopy revealed the spherical shape of the nanoparticles. The dynamic light scattering results indicated the average particle size of the product was 97 nm with a 0.191 polydispersity index. Furthermore, the product was analyzed by energy dispersive X-ray spectroscopy, X-ray diffraction, and elemental mapping, which displayed the presence of elemental silver in the product. Moreover, on a medical platform, the product was checked against pathogenic microorganisms including Vibrio parahaemolyticus, Salmonella enterica, Bacillus anthracis, Bacillus cereus, Escherichia coli, and Candida albicans. The nanoparticles demonstrated antimicrobial activity against all of these pathogenic microorganisms. Additionally, the silver nanoparticles were evaluated for their combined effects with the commercial antibiotics lincomycin, oleandomycin, vancomycin, novobiocin, penicillin G, and rifampicin against these pathogenic microorganisms. These results indicated that the combination of antibiotics with biosynthesized silver nanoparticles enhanced the antimicrobial effects of antibiotics. Therefore, the current study is a demonstration of an efficient biological synthesis of silver nanoparticles by B. frigoritolerans DC2 and its effect on the enhancement of the antimicrobial efficacy of well-known commercial antibiotics.

Silver-induced reconstruction of an adeninate-based metal-organic framework for encapsulation of luminescent adenine-stabilized silver clusters.

Science.gov (United States)

Jonckheere, Dries; Coutino-Gonzalez, Eduardo; Baekelant, Wouter; Bueken, Bart; Reinsch, Helge; Stassen, Ivo; Fenwick, Oliver; Richard, Fanny; Samorì, Paolo; Ameloot, Rob; Hofkens, Johan; Roeffaers, Maarten B J; De Vos, Dirk E

2016-05-21

Bright luminescent silver-adenine species were successfully stabilized in the pores of the MOF-69A (zinc biphenyldicarboxylate) metal-organic framework, starting from the intrinsically blue luminescent bio-MOF-1 (zinc adeninate 4,4'-biphenyldicarboxylate). Bio-MOF-1 is transformed to the MOF-69A framework by selectively leaching structural adenine linkers from the original framework using silver nitrate solutions in aqueous ethanol. Simultaneously, bright blue-green luminescent silver-adenine clusters are formed inside the pores of the recrystallized MOF-69A matrix in high local concentrations. The structural transition and concurrent changes in optical properties were characterized using a range of structural, physicochemical and spectroscopic techniques (steady-state and time-resolved luminescence, quantum yield determination, fluorescence microscopy). The presented results open new avenues for exploring the use of MOFs containing luminescent silver clusters for solid-state lighting and sensor applications.

Quarterly title list for the period ending June 1980

International Nuclear Information System (INIS)

1980-01-01

The title list contains: a) 17 titles and abstracts of laboratory reports, b) 36 titles of publications (32 with abstracts), c) 13 titles of articles submitted for publication (12 with abstracts), and d) 72 titles of lectures (52 with abstracts.) (GG) [de

Silver recovery aqueous techniques from diverse sources: Hydrometallurgy in recycling.

Science.gov (United States)

Syed, S

2016-04-01

The demand of silver is ever increasing with the advance of the industrialized world, whereas worldwide reserves of high grade silver ores are retreating. However, there exist large stashes of low and lean grade silver ores that are yet to be exploited. The main impression of this work was to draw attention to the most advance technologies in silver recovery and recycling from various sources. The state of the art in recovery of silver from different sources by hydrometallurgical and bio-metallurgical processing and varieties of leaching, cementing, reducing agents, peeling, electro-coagulants, adsorbents, electro-dialysis, solvent extraction, ion exchange resins and bio sorbents are highlighted in this article. It is shown that the major economic driver for recycling of depleted sources is for the recovery of silver. In order to develop an nature-friendly technique for the recovery of silver from diverse sources, a critical comparison of existing technologies is analyzed for both economic viability and environmental impact was made in this amendment and silver ion toxicity is highlighted. Copyright © 2016 Elsevier Ltd. All rights reserved.

N-acetylcysteine induced quenching of red fluorescent oligonucleotide-stabilized silver nanoclusters and the application in pharmaceutical detection

International Nuclear Information System (INIS)

Wang, Xinyi; Lin, Ruoyun; Xu, Zhihan; Huang, Hongduan; Li, Limei; Liu, Feng; Li, Na; Yang, Xiaoda

2013-01-01

Graphical abstract: -- Highlights: •A new method for nanomolar NAC determination with LOD of 50 nM was reported. •The combined mechanism for NAC quenching with static dominating was suggested. •DNA-Ag NC structure changed with addition of NAC, proved by spectroscopic studies. -- Abstract: In this work, we reported a new, simple and sensitive method for determination of N-acetylcysteine (NAC) based on quenching of the red fluorescence of oligonuleotide-protected silver nanoculsters (Ag NCs) with the quantum yield of 68.3 ± 0.3%. This method was successfully used for the assay of NAC granules presenting a linear range from 100 nM to 1200 nM (LOD of 50 nM) with minimal interferences from potential coexisting substances. It is for the first time that quenching performance of the thiol-containing compound was found to follow a non-linear Stern–Volmer profile, indicative of a complicated quenching mechanism with static quenching dominating, in which DNA-template of Ag NCs was partly replaced by NAC, as elucidated by spectral investigations. This study extended the analytical application of silver nanoclusters as well as provided a more insightful understanding of the quenching mechanism of thiol-compounds on the fluorescence of Ag NCs

A New Silver Complex with Ofloxacin – Preliminary Study

Directory of Open Access Journals (Sweden)

Rusu Aura

2016-06-01

Full Text Available Objective: Silver complexes of antibacterial quinolones have the potential advantage of combining the antibacterial activity of silver and fluoroquinolones. The objective of our study was the preparation and the preliminary physico-chemical characterization of a silver complex with ofloxacin.

Title of the paper goes here second line

Indian Academy of Sciences (India)

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Spectrum of antimicrobial activity associated with ionic colloidal silver.

Science.gov (United States)

Morrill, Kira; May, Kathleen; Leek, Daniel; Langland, Nicole; Jeane, La Deana; Ventura, Jose; Skubisz, Corey; Scherer, Sean; Lopez, Eric; Crocker, Ephraim; Peters, Rachel; Oertle, John; Nguyen, Krystine; Just, Scott; Orian, Michael; Humphrey, Meaghan; Payne, David; Jacobs, Bertram; Waters, Robert; Langland, Jeffrey

2013-03-01

Silver has historically and extensively been used as a broad-spectrum antimicrobial agent. However, the Food and Drug Administration currently does not recognize colloidal silver as a safe and effective antimicrobial agent. The goal of this study was to further evaluate the antimicrobial efficacy of colloidal silver. Several strains of bacteria, fungi, and viruses were grown under multicycle growth conditions in the presence or absence of ionic colloidal silver in order to assess the antimicrobial activity. For bacteria grown under aerobic or anaerobic conditions, significant growth inhibition was observed, although multiple treatments were typically required. For fungal cultures, the effects of ionic colloidal silver varied significantly between different genera. No viral growth inhibition was observed with any strains tested. The study data support ionic colloidal silver as a broad-spectrum antimicrobial agent against aerobic and anaerobic bacteria, while having a more limited and specific spectrum of activity against fungi.

Catalytic oxidation of butyl acetate over silver-loaded zeolites

International Nuclear Information System (INIS)

Wong, Cheng Teng; Abdullah, Ahmad Zuhairi; Bhatia, Subhash

2008-01-01

The performance of silver-loaded zeolite (HY and HZSM-5) catalysts in the oxidation of butyl acetate as a model volatile organic compound (VOC) was studied. The objective was to find a catalyst with superior activity, selectivity towards deep oxidation product and stability. The catalyst activity was measured under excess oxygen condition in a packed bed reactor operated at gas hourly space velocity (GHSV) = 15,000-32,000 h -1 , reaction temperature between 150 and 500 deg. C and butyl acetate inlet concentration of 1000-4000 ppm. Both AgY and AgZSM-5 catalysts exhibited high activity in the oxidation of butyl acetate. Despite lower silver content, AgY showed better activity, attributed to better metal dispersion, surface characteristics and acidity, and its pore system. Total conversion of butyl acetate was achieved at above 400 deg. C. The oxidation of butyl acetate followed a simple power law model. The reaction orders, n and m were evaluated under differential mode by varying the VOC partial pressure between 0.004 and 0.018 atm and partial pressure of oxygen between 0.05 and 0.20 atm. The reaction rate was independent of oxygen concentration and single order with respect to VOC concentration. The activation energies were 19.78 kJ/mol for AgY and 32.26 kJ/mol for AgZSM-5, respectively

Green synthesis of silver nanoparticles and their characterization by XRD

Science.gov (United States)

Mehta, B. K.; Chhajlani, Meenal; Shrivastava, B. D.

2017-05-01

A cost effective and environment friendly technique for green synthesis of silver nanoparticles has been reported. Silver nanoparticles have been synthesized using ethanol extract of fruits of Santalum album (Family Santalaceae), commonly known as East Indian sandalwood. Fruits of S.album were collected and crushed. Ethanol was added to the crushed fruits and mixture was exposed to microwave for few minutes. Extract was concentrated by Buchi rotavaporator. To this extract, 1mM aqueous solution of silver nitrate (AgNO3) was added. After about 24 hr incubation Ag+ ions in AgNO3 solution were reduced to Ag atoms by the extract. Silver nanoparticles were obtained in powder form. X-ray diffraction (XRD) pattern of the prepared sample of silver nanoparticles was recorded The diffractogram has been compared with the standard powder diffraction card of JCPDS silver file. Four peaks have been identified corresponding to (hkl) values of silver. The XRD study confirms that the resultant particles are silver nanoparticles having FCC structure. The average crystalline size D, the value of the interplanar spacing between the atoms, d, lattice constant and cell volume have been estimated. Thus, silver nanoparticles with well-defined dimensions could be synthesized by reduction of metal ions due to fruit extract of S.album.

Antimicrobial effects of zinc oxide nanoparticles modified with silver

International Nuclear Information System (INIS)

Lopes, Rayssa Souza; Arantes, Tatiane Moraes

2016-01-01

Full text: With the emergence of resistant microbial organisms to multiple antibiotics, different shapes of silver nanoparticles are among the most promising antimicrobial agents that have been developed from nanotechnology. Besides the silver nanoparticles oxide nanoparticles such as zinc oxide (ZnO) is gaining prominence due to its bactericidal properties. [1-3]. Thus, this study aims to develop biomaterials from zinc oxide nanoparticles modified with silver with antimicrobial properties. The ZnO nanoparticles were synthesized by hydrothermal processing by alkaline hydrolysis zinc acetate. Colloidal dispersions of silver nanoparticles were synthesized by the Turkevich method using sodium citrate to reduce silver nitrate at high pH and at 90 °C in the presence of zinc oxide nanoparticles. Both nanoparticles were characterized by X-ray diffraction (XRD), FTIR and Raman spectroscopy and scanning electron microscopy (SEM). The XRD and Raman spectra showed crystalline ZnO colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed cubic silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated zinc oxide nanoparticles. SEM images showed ZnO nanoparticles presented a nanorod shapes with length around 80 nm decorated with spherical silver nanoparticles about 20 nm in diameter The results showed that crystalline zinc oxide colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. Results of antibacterial tests indicate that the ZnO/Ag nanoparticles have antibacterial properties against both Staphylococcus aureus and Escherichia coli. The results demonstrated that the ZnO/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

Antimicrobial effects of zinc oxide nanoparticles modified with silver

Energy Technology Data Exchange (ETDEWEB)

Lopes, Rayssa Souza; Arantes, Tatiane Moraes, E-mail: rayssasouza.net@gmail.com [Universidade Federal de Goias (UFG), Goiania (Brazil)

2016-07-01

Full text: With the emergence of resistant microbial organisms to multiple antibiotics, different shapes of silver nanoparticles are among the most promising antimicrobial agents that have been developed from nanotechnology. Besides the silver nanoparticles oxide nanoparticles such as zinc oxide (ZnO) is gaining prominence due to its bactericidal properties. [1-3]. Thus, this study aims to develop biomaterials from zinc oxide nanoparticles modified with silver with antimicrobial properties. The ZnO nanoparticles were synthesized by hydrothermal processing by alkaline hydrolysis zinc acetate. Colloidal dispersions of silver nanoparticles were synthesized by the Turkevich method using sodium citrate to reduce silver nitrate at high pH and at 90 °C in the presence of zinc oxide nanoparticles. Both nanoparticles were characterized by X-ray diffraction (XRD), FTIR and Raman spectroscopy and scanning electron microscopy (SEM). The XRD and Raman spectra showed crystalline ZnO colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed cubic silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated zinc oxide nanoparticles. SEM images showed ZnO nanoparticles presented a nanorod shapes with length around 80 nm decorated with spherical silver nanoparticles about 20 nm in diameter The results showed that crystalline zinc oxide colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. Results of antibacterial tests indicate that the ZnO/Ag nanoparticles have antibacterial properties against both Staphylococcus aureus and Escherichia coli. The results demonstrated that the ZnO/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

Iodine, krypton and xenon retention efficiencies of silver impregnated silica gel media with different silver loadings and under different test conditions

International Nuclear Information System (INIS)

Motes, B.G.; Fernandez, S.J.; Tkachyk, J.W.

1983-02-01

The purpose of an independent study conducted by Exxon Nuclear Idaho, Co. (ENICO) was to evaluate a silver impregnated silica gel adsorption medium associated with a radioiodine air sampler developed at Brookhaven National Laboratory (BNL). Specifically, ENICO's responsibility was to evaluate the iodine and noble gas retention efficiencies of the adsorption medium. The evaluation was comprised of a four-phase program: 1) test assemblies capable of challenging the silver silica gel filled adsorber canister with radioiodine species or noble gases at flow rates up to 10 scfm and relative humidities up to 83% were constructed; 2) more than 45 kgs of the 4 and 8% silver impregnated silica gel were prepared and characterized for particle size distribution, bulk silver content, bulk density, and silver content by particle size; 3) iodine species retention efficiencies of the silver silica gel were determined; and 4 krypton and xenon retention efficiencies were measured. The iodine species retention efficiencies were greater than 90% under most conditions. A combination of flow rates >5 scfm and 4% silver loaded silica gel reduced the methyl iodide retention efficiency to less than 90%. The retention efficiencies for both krypton and xenon were on the order of 8 x 10 -2 % and were not affected greatly by any test variable except test duration. A reduced retention efficiency with increased test durations indicates adsorption equilibrium may be established within five minutes. (author)

ELLIPSOMETRIC STUDY OF SEMITRANSPARENT SILVER LAYERS DEPOSITED ON GLASS

Directory of Open Access Journals (Sweden)

Víctor Toranzos

2014-12-01

Full Text Available Using ellipsometry, the film structure is characterized by optical indices n, k (visible region, 450 nm <  < 580 nm and the thickness (15 < d < 35 nm. The optical indices change with the quantity of silver deposited, obtaining effective indices of 1.0 < n < 1.8 and 1.6 < k < 2.6 to the smaller deposits that belong to a volumetric fraction between 0.35 and 0.5 of silver in the air. An effective optical thickness film decrease is observed when the silver volumetric fraction increases, and a thickness increase with close indices to solid silver when the deposited silver increases. Optical and effective medium theory indices are compared.

Cytotoxicity and antimicrobial activities of green synthesized silver nanoparticles.

Science.gov (United States)

Lokina, S; Stephen, A; Kaviyarasan, V; Arulvasu, C; Narayanan, V

2014-04-09

Bio-inspired silver nanoparticles are synthesized using Malus domestica (apple) extract. Polyphenols present in the apple extract act as a reducing and capping agent to produce the silver nanoparticles. UV-Visible analysis shows the surface plasmon resonance (SPR) absorption at 420 nm. The FTIR analysis was used to identify the functional groups responsible for the bio-reduction of silver ion. The XRD and HRTEM images confirm the formation of silver nanoparticles. The minimal inhibitory concentration (MIC) of silver nanoparticles was recorded against most of the bacteria and fungus. Further, MCF-7 human breast adenocarcinoma cancer cell line was employed to observe the efficacy of cancer cell killing. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

International Nuclear Information System (INIS)

Shao-Peng, Zhu; Shao-Chun, Tang; Xiang-Kang, Meng

2009-01-01

Silver nanoparticles with an average size of about 20 nm are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method. The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability. (cross-disciplinary physics and related areas of science and technology)

Antibacterial potency of V.A.C. GranuFoam Silver(®) Dressing.

Science.gov (United States)

Sachsenmaier, Saskia; Peschel, Andreas; Ipach, Ingmar; Kluba, Torsten

2013-10-01

V.A.C.(®) GranuFoam™ therapy is regularly used in the surgical therapy of infected wounds and soft tissue injuries. Silver nanoparticles can destroy bacterial cell walls and inhibit enzymes for cell replication. Silver dressings are therefore successfully used for many indications in wound therapy. In this study, we investigated the antimicrobial potency of ionic silver released from the silver-coated V.A.C.(®) GranuFoam™ during vacuum therapy. Silver dressing was exposed to agar plates populated with bacteria to measure silver release. A total of 15 agar plates colonised with either Staphylococcus aureus populations or with Staphylococcus epidermidis, were loaded with V.A.C. GranuFoam Silver(®) Dressing polyurethane foam (KCI, San Antonio, Texas). Each of 13 pieces of silver-coated foam was applied to an agar plate. Two plates were loaded with conventional black foam without any coating. After connecting to a vacuum pump, the vacuum therapy of the 15 plates lasted 5 days. The zone of inhibition of bacterial growth around the foam was measured daily. Silver release was also determined as a function of time. At each time point, there was evidence of silver in the agar independent of bacterial colonisation. The S. aureus agar showed a consecutive increase in silver concentration from baseline upon 48 h after exposure to the negative pressure of V.A.C. therapy. An increasing mean silver level after 48, 72 and 96 h was measured under V.A.C. therapy with a peak value after 120 h. In contrast, the results from the S. epidermidis plates did not follow a linear pattern. At the beginning of vacuum therapy, we documented a rise in silver concentration. After 48-96h, the silver levels fluctuated. A maximum zone of inhibition in both bacterial colonised plates (S. aureus and S. epidermidis) was found 39 h after the start of the V.A.C. GranuFoam Silver(®) therapy. From our results, we confirmed the antimicrobial effect of the silver ions against S. aureus and S

Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

NARCIS (Netherlands)

Manea, F.; Motoc, S.; Pop, A.; Remes, A.; Schoonman, J.

2012-01-01

The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon

Inkjet printing of silver citrate conductive ink on PET substrate

International Nuclear Information System (INIS)

Nie Xiaolei; Wang Hong; Zou Jing

2012-01-01

Highlights: ► A direct synthesis method of silver conductive film on PET substrate was presented. ► A stable particle-free conductive ink was prepared. ► Formation of silver-amine complex reduced the thermal decomposition temperature. ► Conductive patterns for flexible electronics were fabricated by inkjet printing. ► Silver film on PET substrate possessed highest adhesion rating even without polymer. - Abstract: Direct synthesis of silver conductive film on PET substrate by inkjet printing silver citrate conductive ink was presented in this paper. This kind of conductive ink contained silver citrate as silver precursor, 1,2-diaminopropane as complex agent dissolving the silver salt and methanol and isopropanol as a media adjusting the viscosity and surface tension. The formation of silver-amine complex reduced the decomposition temperature from 180 °C to 135 °C, thus the ink could be cured at relatively low temperature. The film reached the lowest resistivity of 17 μΩ cm after cured at 150 °C for 50 min, 3.1 μΩ cm at 230 °C and possessed high reflection and excellent adhesive property. Electrical conductivity, surface morphology and composition were investigated by four-point probe method, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). It is demonstrated how the cured condition affects the silver film. Moreover, radio-frequency identification (RFID) antenna was fabricated by inkjet printing, which opens up routes for the flexible electronics fabrication.

Detection of colloidal silver chloride near solubility limit

Science.gov (United States)

Putri, K. Y.; Adawiah, R.

2018-03-01

Detection of nanoparticles in solution has been made possible by several means; one of them is laser-induced breakdown detection (LIBD). LIBD is able to distinguish colloids of various sizes and concentrations. This technique has been used in several solubility studies. In this study, the formation of colloids in a mixed system of silver nitrate and sodium chloride was observed by acoustic LIBD. Silver chloride has low solubility limit, therefore LIBD measurement is appropriate. Silver and chloride solutions with equal concentrations, set at below and above the solubility of silver chloride as the expected solid product, were mixed and the resulting colloids were observed. The result of LIBD measurement showed that larger particles were present as more silver and chloride introduced. However, once the concentrations exceeded the solubility limit of silver chloride, the detected particle size seemed to be decreasing, hence suggested the occurrence of coprecipitation process. This phenomenon indicated that the ability of LIBD to detect even small changes in colloid amounts might be a useful tool in study on formation and stability of colloids, i.e. to confirm whether nanoparticles synthesis has been successfully performed and whether the system is stable or not.

Silver(I) and copper(I) complexes with the closo-decaborate anion B10H102- as a ligand

International Nuclear Information System (INIS)

Malinina, E.A.; Zhizhin, K.Yu.; Polyakova, I.N.; Lisovskij, M.V.; Kuznetsov, N.T.

2002-01-01

Studying the process of silver(I) and copper(I) complexing with closo-borate anion B 10 H 10 2- it is determined that the last can to play a role of intraspherical ligand forming stable coordination compounds of two types: Cat[MB 10 H 10 ] and [M 2 B 10 H 10 ] (M=Ag(I), Cu(I)). In these compounds the bond metal-boron skeleton is realized by means of formation of three-center bonds M-H-B. Structure of the complexes Cs[AgB 10 H 10 ] and [(C 2 H 5 ) 3 NH][AgB 10 H 10 ] and possible mechanism of their formation are discussed [ru

Microstructural and Z-scan measurement of silver nanoparticles

International Nuclear Information System (INIS)

Sivakami, R.; Dhanuskodi, S.

2015-01-01

Graphical abstract: - Highlights: • Novel Ag nanoparticles were prepared by hydrothermal method. • The modified forms of W-H analysis of Ag nanoparticles are reported first time. • Nonlinear optical (NLO) properties of Ag nanoflowers are reported and high nonlinearity was obtained. - Abstract: Silver nanoflowers were synthesized by the hydrothermal route. Formation of Ag nanoparticles is confirmed from the UV–vis spectrum where the surface plasmon absorption maxima are observed at 415–454 nm. FE-SEM and TEM images revealed the formation of silver nanoflowers and the flower-like silver nanostructures are estimated using transmission electron microscopy. XRD confirms that the synthesized silver is highly crystalline with face centered cubic structure. The X-ray line broadening is studied by the modified forms of Williamson–Hall analysis. The Z-scan results reveal that the flower-like silver nanostructures exhibit the nonlinear susceptilibility as 1.14 × 10 −5 esu

INIS: Authority list for journal titles

International Nuclear Information System (INIS)

2009-01-01

This is the 35th revision of the INIS: Authority List for Journal Titles (IAEA-INIS-11). This list is published annually and includes the titles of all journals which have contained articles submitted to INIS at the time of publication. The current list contains 13 750 journal titles, 1 965 regularly scanned journals and 593 key journals. It was last updated in March 2009. A journal - or periodical - is a continuing publication issued in a succession of discrete parts, usually bearing numbering and/or chronological designations and intended to be continued indefinitely. It is generally published within a defined, fixed interval between issues and normally appears more than once per year. It includes a mixture of articles, letters, summaries, etc. Within this definition, annuals such as the Annual Review of Nuclear Science are included, but series titles such as the McGraw-Hill Series in Nuclear Engineering are not. The purpose of this document is to provide descriptive cataloguers with standard elements to include in bibliographic level 'S' of the INIS record. These elements include field (tag) 229 (Full Journal Title), 320 (ISSN) and 321 (CODEN). The full journal title is mandatory, and either the ISSN or the CODEN must be included (both may appear). Instructions on how to use this and other elements of the INIS record format are found in INIS: Guide to Bibliographic Description (IAEA-INIS-1). In order to help the user find titles easily, the list is arranged in six parts, followed by summary statistics: - In Part I, all key journals are grouped under the name of the country or international organization responsible for their input in INIS, then sorted alphabetically under their title. - In Part II, all key journals are sorted alphabetically under their title. The name of the country or international organization responsible for their input in INIS is entered in parentheses within the body of the entry. - In Part III, all journals that are regularly scanned by the

[Silver-Russell syndrome with panhypopituitarism (author's transl)].

Science.gov (United States)

Stögmann, W; Borkenstein, M; Grubbauer, H M

1978-11-01

This is a report on a 14 years old boy suffering from the unusual combination of Silver-Russell syndrome with panhypopituitarism. The Silver-Russell syndrome is a special form of primordial dwarfism characterised by congenital asymmetry, craniofacial dysmorphy and other anomalies. Its cause is unknown, intrauterine noxes and genetical factors are discussed. In the most cases results of hormone determinations are normal, but also cases with elevated or very low hormone levels were published. This is the first report about a Silver-Russell syndrome combined with panhypopituitarism.

Antibacterial Potential of Jatropha curcas Synthesized Silver Nanoparticles against Food Borne Pathogens

Science.gov (United States)

Chauhan, Nitin; Tyagi, Amit K.; Kumar, Pushpendar; Malik, Anushree

2016-01-01

The aqueous leaf extract of Jatropha curcas was used for the synthesis of silver nanoparticles (Jc-AgNps) which were further evaluated for its antibacterial potential against food borne pathogens. J. curcas leaf extract could synthesize stable silver nanoparticles (Zeta potential: -23.4 mV) with absorption band at 430 nm. Fourier transform infrared spectroscopy indicated various biological compounds responsible for capping and stabilizing Jc-AgNps in suspension, while the presence of silver was authenticated by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray. Jc-AgNps were confirmed to be uniform in shape, size and behavior through dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction, SEM, and atomic force microscopy (AFM) analysis. To investigate the antibacterial activity, disk diffusion and microplate dilution assays were performed and zone of inhibition (ZOI) as well as minimum inhibitory/bactericidal concentrations (MIC/MBCs) were evaluated against selected bacterial strains. Overall results showed that Escherichia coli (ZOI: 23 mm, MBC: 0.010 mg/ml) was the most sensitive organism, whereas Staphylococcus aureus (ZOI: 14.66 mm, MBC: 0.041 mg/ml) and Salmonella enterica (ZOI: 16.66 mm, MBC: 0.041 mg/ml) were the least sensitive against Jc-AgNps. The detailed microscopic investigations using SEM, TEM, and AFM were performed to understand the antibacterial impacts of Jc-AgNps against Listeria monocytogenes. SEM and TEM analysis showed the clear deformation and disintegration of treated L. monocytogenes cells, whereas AFM established a decrease in the height and cell surface roughness (root mean square value) in the treated L. monocytogenes. PMID:27877160