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Sample records for silver islands grown

  1. Effect of underlayer on coalescence of silver islands grown byfiltered cathodic arc deposition

    SciTech Connect

    Byon, Eungsun; Anders, Andre

    2003-03-01

    For low-emissivity application on window glass, coalescenceof thin film silver islands is crucial for high transmittance in thevisible andhigh reflectance in the infrared. It is well known that theenergy of ions arriving at the substrate (kinetics) as wells as the typeof underlayer (thermodynamics) affect the nucleation and growth mode.Little is known about coalescence of silver islands synthesized byenergetic condensation, e.g., by filtered cathodic vacuum arc deposition.In this work, the effect of the underlayer on nucleation and growth ofsilver films deposited by filtered cathodic vacuum arc was investigatedby transmission electron microscopy (TEM) and atomic force microscopy(AFM). The results are compared with data obtained on magnetron sputteredfilms. It was found that uncoated and titanium-oxide-coated glass requiremore silver to achieve the same low value of sheet resistance than silveron zinc-oxide-coated glass. This can be associated with the energy ofinteraction between surface and silver atoms. Silver films made bycathodic arc deposition show an earlier onset of island coalescence andformation of short links. It was found that silver islands in energeticdeposition exhibit a reduced aspect ratio compared to evaporation andsputtering. A nominal 0.1 nm niobium underlayer increases the nucleationdensity and promotes coalescence of silver islands, however, a 0.2 nmlayer did not show these features, indicating the need for furtherstudies.

  2. Thermal stability of PLD grown silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-05-01

    Present work discusses the stability of silver nanoparticles at different annealing temperatures. Air muffle furnace annealing is performed to study the thermal stability of pulsed laser deposited silver nanoparticles. Silver reacts with atmospheric oxygen to form silver oxide at annealing temperatures below 473K and thermal decomposition of silver oxide takes place at temperatures above 473K. Oxide formation results in core shrinkage of silver, which in turn affects the surface plasmon resonance of silver nanoparticles. With increase in annealing temperature, the surface plasmon effect of nanoparticles starts to fade. SEM, XRD and UV-vis spectroscopy have been performed to analysis various structural and optical properties.

  3. Phtotochemically Grown Silver Nanocubes: Synthesis and Characterization

    NASA Astrophysics Data System (ADS)

    Deb, S.; Sarkar, D.

    2010-10-01

    Special shaped novel metal nanoparticles have become the focus of intensive research owing to their unique application in nanoscale devices.We report here the fabrication of silver nanocubes by photochemical method. Spherically shaped silver nanoparticles dispersed in polyvinyl alcohol are synthesized by chemical method which is then irradiated with monochromatic light of wavelength 510 nm for 23 hrs. The obtained silver nanocubes are characterised by SEM, XRD, UV-Vis spectrscopy and photoluminescence. SEM image shows that the particles are cubic in shape and average size of the particle is in the range120-150nm. UV-Vis spectra shows a very strong plasmon resonance peak at 435 nm. XRD pattern shows a characteristic peak of silver nano at 2θ = 38.1° for (111) plane.

  4. Antibacterial properties of biomedical surfaces containing micrometric silver islands

    NASA Astrophysics Data System (ADS)

    Pérez-Tanoira, R.; Pérez-Jorge, C.; Endrino, J. L.; Gómez-Barrena, E.; Horwat, D.; Pierson, J. F.; Esteban, J.

    2010-11-01

    A set of Cu-Mn-O and Ag-Cu-Mn-O films were sputter-deposited onto polished Ti-6Al-4V coupons and the microbiological adherence of Staphylococcus sp. was studied in these biomedical surfaces modified using advanced ternary and quaternary oxides that incorporated micrometric silver islands. The as-deposited ternary and quaternary compounds were amorphous. Upon air annealing the Ag-Cu-Mn-O films, silver-oxygen bonds in the compound destabilize, resulting in the segregation of metallic silver in the form of micrometric layered silver islands with high specific area dispersed at the surface of the remaining oxide. Silver is well known to have a natural biocidal character and its presence in the surface forming large micrometric escalonated islands is, in principle, predicted to enhance the antimicrobial properties of biomedical surfaces. Microbial adhesion tests were performed in triplicates using collection strains of Staphylococcus aureus and Staphylococcus epidermidis. Preliminary results indicate that both strains showed decreased adherence to modified materials, S. epidermidis showed higher adherence these materials than S. aureus, however, there was no statistically significant differences between Cu-Mn-O and Ag-Cu-Mn-O containing silver islands.

  5. Control of Pythium root rot on hydroponically grown cucumbers with silver-coated cloth.

    PubMed

    Zhao, Z H; Kusakari, S; Okada, K; Miyazaki, A; Osaka, T

    2000-07-01

    Silver-coated cloth (SCC) effectively controlled root rot that was caused by Pythium aphanidermatum in hydroponically grown cucumber plants. The presence of SCC in the hydroponic solution reduced the root rot from 100% to 10% 20 days after inoculation with zoospores of P. aphanidermatum. It was suggested that the inhibition of SCC was caused not only by the silver ion dissolved from SCC, but also by the metallic silver and silver compounds formed on the surface of the root.

  6. 78 FR 28149 - Cranberries Grown in States of Massachusetts, Rhode Island, Connecticut, New Jersey, Wisconsin...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    ... Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in States of Massachusetts, Rhode Island... history provisions currently prescribed under the cranberry marketing order (order). The order regulates the handling of cranberries grown in Massachusetts, Rhode Island, Connecticut, New Jersey,...

  7. Reduction of Cu2O Islands Grown on a Cu(100) Surface through Vacuum Annealing

    NASA Astrophysics Data System (ADS)

    Zhou, Guangwen; Yang, Judith C.

    2004-11-01

    The reduction of Cu2O islands grown on Cu(100) surfaces through vacuum annealing was visualized by an in situ ultrahigh vacuum transmission electron microscope. The shrinkage of the island followed a linear decay behavior. The complete reduction of the oxide islands leads to the formation of nanoindentations on the Cu surfaces. A simple phenomenological kinetic model based on the dissociation along the island perimeter suitably describes the reduction behavior of the surface oxide islands.

  8. 75 FR 20514 - Cranberries Grown in the States of Massachusetts, Rhode Island, Connecticut, New Jersey...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... on February 5, 2010 (75 FR 5898). Copies of the rule were mailed or sent facsimile to all Committee... Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in the States of Massachusetts, Rhode Island... handling of cranberries grown in the States of Massachusetts, Rhode Island, Connecticut, New...

  9. Gallium Arsenide Layers Grown by Molecular Beam Epitaxy on Single Crystalline Germanium Islands on Insulator

    NASA Astrophysics Data System (ADS)

    Takai, Mikio; Tanigawa, Takaho; Minamisono, Tadanori; Gamo, Kenji; Namba, Susumu

    1984-05-01

    Gallium arsenide (GaAs) layers have successfully been grown by molecular beam epitaxy on single crystalline germanium (Ge) islands, recrystallized by zone melting with SiO2 capping layers, on thermally-oxidized Si-wafers. The GaAs layers, grown on the single crystalline Ge islands, show smooth surfaces without any grain-boundaries, while those, grown on the Ge islands with grain-boundaries and on the SiO2, have grain-boundaries. The GaAs layers on the single crystalline Ge islands emit photoluminescence, the intensity of which is almost comparable to that of GaAs layers on bulk Ge crystals.

  10. Correction: The impact of doping rates on the morphologies of silver and gold nanowires grown in helium nanodroplets.

    PubMed

    Volk, Alexander; Thaler, Philipp; Knez, Daniel; Hauser, Andreas W; Steurer, Johannes; Grogger, Werner; Hofer, Ferdinand; Ernst, Wolfgang E

    2016-01-28

    Correction for 'The impact of doping rates on the morphologies of silver and gold nanowires grown in helium nanodroplets' by Alexander Volk et al., Phys. Chem. Chem. Phys., 2016, DOI: 10.1039/c5cp06248a. PMID:26728840

  11. Stability and structure of nanowires grown from silver, copper and their alloys by laser ablation into superfluid helium.

    PubMed

    Gordon, Eugene; Karabulin, Alexander; Matyushenko, Vladimir; Sizov, Vyacheslav; Khodos, Igor

    2014-12-14

    Nanowires with 5 nm diameter made of silver, copper, and their alloys were grown in superfluid helium. The silver nanowires being heated to 300 K disintegrated into individual clusters. In contrast, copper nanowires were stable at room temperature, and nanowires made of alloys were also stable despite their low melting temperature.

  12. Surface-Enhanced Raman Scattering of Rhodamine 123 in Silver Hydrosols and in Langmuir-Blodgett Films on Silver Islands.

    PubMed

    Chowdhury, Joydeep; Pal, Prabir; Ghosh, Manash; Misra, T. N.

    2001-03-15

    Surface-enhanced Raman scattering(SERS) of the Rhodamine 123 (Rh 123) molecule on ion-induced silver colloids has been studied. A time-dependent study of the SER spectra at a particular pH confirms charge transfer interaction between the probe molecule and the metal. The SER spectra of Rh 123 in Ag sol is compared with that of the molecules organized in a monolayer on silver island films by the Langmuir-Blodgett (LB) technique. The origin of high SERS activity of Rh 123 molecules in a monolayer on a silver island film is shown to be due to physisorption whereas in the ion-induced colloidal SERS both physisorption and chemisorption machanisms are involved. From these results, the contribution of charge transfer interaction to SERS in Ag sol has been estimated. In monolayer SERS, all the in-plane and out-of-plane (of xanthene ring) modes are more or less equally enhanced. This indicates that the xanthene plane of Rh 123 molecule organized in a LB film is oriented neither flat nor perpendicular to the silver island surface but is tilted. Copyright 2001 Academic Press.

  13. 75 FR 5900 - Cranberries Grown in the States of Massachusetts, Rhode Island, Connecticut, New Jersey...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-05

    ... Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in the States of Massachusetts, Rhode Island... procedures for independent growers on the Cranberry Marketing Committee (Committee). The order regulates the handling of cranberries produced in the States of Massachusetts, Rhode Island, Connecticut, New...

  14. 77 FR 52595 - Cranberries Grown in States of Massachusetts, Rhode Island, Connecticut, New Jersey, Wisconsin...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-30

    ... due in order to provide handlers with additional time to submit their report (75 FR 5898). Under that... Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in States of Massachusetts, Rhode Island... prescribed under the marketing order that regulates the handling of cranberries grown in the States...

  15. 75 FR 5898 - Cranberries Grown in the States of Massachusetts, Rhode Island, Connecticut, New Jersey...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-05

    ...; ] DEPARTMENT OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in the States of... dates prescribed under the marketing order that regulates the handling of cranberries grown in the..., Washington, and Long Island in the State of New York. The order is administered locally by the...

  16. 75 FR 18394 - Cranberries Grown in the States of Massachusetts, Rhode Island, Connecticut, New Jersey...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-12

    ... action was published in the Federal Register on February 5, 2010 (75 FR 5900). Copies of the rule were... Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in the States of Massachusetts, Rhode Island... growers on the Cranberry Marketing Committee (Committee). The order regulates the handling of...

  17. 78 FR 51043 - Cranberries Grown in States of Massachusetts, Rhode Island, Connecticut, New Jersey, Wisconsin...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-20

    ... FR 28149). Copies of the rule were mailed or sent via facsimile to all Committee members and... Agricultural Marketing Service 7 CFR Part 929 Cranberries Grown in States of Massachusetts, Rhode Island... prescribed under the cranberry marketing order (order). The order regulates the handling of cranberries...

  18. Evolution of strain and composition of Ge islands on Si (001) grown by molecular beam epitaxy during postgrowth annealing

    SciTech Connect

    Singha, R. K.; Das, S.; Majumdar, S.; Das, K.; Dhar, A.; Ray, S. K.

    2008-06-01

    Self-assembled Ge islands have been grown using a Stranski-Krastanov growth mechanism on Si (001) substrates by solid source molecular beam epitaxy. We performed time varying annealing experiments at a representative temperature of 650 deg. C to study the shape and size evolution of islands for a relatively high Ge coverage. Islands are found to coarsen due to heat treatment via structural and compositional changes through continuous strain relaxation. Different island morphologies, namely, 'pyramids', 'transitional domes', and 'domes' are found during the annealing sequence. The dominant coarsening mechanisms for the temporal evolution of islands of as-grown and annealed samples are explained by the comprehensive analysis of Rutherford back scattering, Raman spectroscopy, high-resolution x-ray diffraction, and atomic force microscopy. A correlation of the morphological evolution with the composition and strain relaxation of grown islands is presented.

  19. Thermal instabilities and Rayleigh breakup of ultrathin silver nanowires grown in helium nanodroplets.

    PubMed

    Volk, Alexander; Knez, Daniel; Thaler, Philipp; Hauser, Andreas W; Grogger, Werner; Hofer, Ferdinand; Ernst, Wolfgang E

    2015-10-14

    Ag nanowires with diameters below 6 nm are grown within vortex containing superfluid helium nanodroplets and deposited onto a heatable substrate at cryogenic temperatures. The experimental setup allows an unbiased investigation of the inherent stability of pristine silver nanowires, which is virtually impossible with other methods due to chemical processes or templates involved in standard production routes. We demonstrate by experiment and by adaption of a theoretical model that initially continuous wires disintegrate into chains of spheres. This phenomenon is well described by a Rayleigh-like breakup mechanism when the substrate is heated to room temperature. Our findings clarify the recent discussions on the cause of the observed segmented patterns, where a breakup during deposition [Gomez et al., Phys. Rev. Lett., 2012, 108, 155302] or mechanisms intrinsic to the helium droplet mediated growth process [Spence et al., Phys. Chem. Chem. Phys., 2014, 16, 6903] have been proposed. The experimental setup confirms the validity of previous suggestions derived from bulk superfluid helium experiments [Gordon et al., Phys. Chem. Chem. Phys., 2014, 16, 25229] for the helium droplet system, and further allows a much more accurate determination of the breakup temperature.

  20. Carbohydrate concentrations and freezing stress resistance of silver birch buds grown under elevated temperature and ozone.

    PubMed

    Riikonen, Johanna; Kontunen-Soppela, Sari; Vapaavuori, Elina; Tervahauta, Arja; Tuomainen, Marjo; Oksanen, Elina

    2013-03-01

    The effects of slightly elevated temperature (+0.8 °C), ozone (O3) concentration (1.3 × ambient O3 concentration) and their combination on over-wintering buds of Betula pendula Roth were studied after two growing seasons of exposure in the field. Carbohydrate concentrations, freezing stress resistance (FSR), bud dry weight to fresh weight ratio, and transcript levels of cytochrome oxidase (COX), alternative oxidase (AOX) and dehydrin (LTI36) genes were studied in two clones (clones 12 and 25) in December. Elevated temperature increased the bud dry weight to fresh weight ratio and the ratio of raffinose family oligosaccharides to sucrose and the transcript levels of the dehydrin (LTI36) gene (in clone 12 only), but did not alter the FSR of the buds. Genotype-specific alterations in carbohydrate metabolism were found in the buds grown under elevated O3. The treatments did not significantly affect the transcript level of the COX or AOX genes. No clear pattern of an interactive effect between elevated temperature and O3 concentration was found. According to these data, the increase in autumnal temperatures and slightly increasing O3 concentrations do not increase the risk for freeze-induced damage in winter in silver birch buds, although some alterations in bud physiology occur. PMID:23425688

  1. Carbohydrate concentrations and freezing stress resistance of silver birch buds grown under elevated temperature and ozone.

    PubMed

    Riikonen, Johanna; Kontunen-Soppela, Sari; Vapaavuori, Elina; Tervahauta, Arja; Tuomainen, Marjo; Oksanen, Elina

    2013-03-01

    The effects of slightly elevated temperature (+0.8 °C), ozone (O3) concentration (1.3 × ambient O3 concentration) and their combination on over-wintering buds of Betula pendula Roth were studied after two growing seasons of exposure in the field. Carbohydrate concentrations, freezing stress resistance (FSR), bud dry weight to fresh weight ratio, and transcript levels of cytochrome oxidase (COX), alternative oxidase (AOX) and dehydrin (LTI36) genes were studied in two clones (clones 12 and 25) in December. Elevated temperature increased the bud dry weight to fresh weight ratio and the ratio of raffinose family oligosaccharides to sucrose and the transcript levels of the dehydrin (LTI36) gene (in clone 12 only), but did not alter the FSR of the buds. Genotype-specific alterations in carbohydrate metabolism were found in the buds grown under elevated O3. The treatments did not significantly affect the transcript level of the COX or AOX genes. No clear pattern of an interactive effect between elevated temperature and O3 concentration was found. According to these data, the increase in autumnal temperatures and slightly increasing O3 concentrations do not increase the risk for freeze-induced damage in winter in silver birch buds, although some alterations in bud physiology occur.

  2. Thermal instabilities and Rayleigh breakup of ultrathin silver nanowires grown in helium nanodroplets.

    PubMed

    Volk, Alexander; Knez, Daniel; Thaler, Philipp; Hauser, Andreas W; Grogger, Werner; Hofer, Ferdinand; Ernst, Wolfgang E

    2015-10-14

    Ag nanowires with diameters below 6 nm are grown within vortex containing superfluid helium nanodroplets and deposited onto a heatable substrate at cryogenic temperatures. The experimental setup allows an unbiased investigation of the inherent stability of pristine silver nanowires, which is virtually impossible with other methods due to chemical processes or templates involved in standard production routes. We demonstrate by experiment and by adaption of a theoretical model that initially continuous wires disintegrate into chains of spheres. This phenomenon is well described by a Rayleigh-like breakup mechanism when the substrate is heated to room temperature. Our findings clarify the recent discussions on the cause of the observed segmented patterns, where a breakup during deposition [Gomez et al., Phys. Rev. Lett., 2012, 108, 155302] or mechanisms intrinsic to the helium droplet mediated growth process [Spence et al., Phys. Chem. Chem. Phys., 2014, 16, 6903] have been proposed. The experimental setup confirms the validity of previous suggestions derived from bulk superfluid helium experiments [Gordon et al., Phys. Chem. Chem. Phys., 2014, 16, 25229] for the helium droplet system, and further allows a much more accurate determination of the breakup temperature. PMID:26367114

  3. Paleomagnetism of Silver Island, Keweenaw Peninsula, Michigan: Additional Support (?) for the Primary Curvature of the MCR

    NASA Astrophysics Data System (ADS)

    Diehl, J. F.; Durant, A. J.; Schepke, C.

    2009-05-01

    Silver Island lies between Eagle Harbor and Copper Harbor on the NW coastline of the Keweenaw Peninsula, Michigan. The island consists of a series of basaltic lava flows which dip to the north-northwest (356°) at an angle of approximately 38°. These flows constitute part of the Lake Shore Traps (LST), a series of interbedded lava flows within the Copper Harbor Conglomerate (CHC). The LST represent the youngest eruptive material associated with the 1.1 Ga Mid-Continent Rift (MCR). The most recent paleomagnetic study (now 15 years old) on the Lakeshore Traps (LST) defined three distinct directional clusters. Each cluster of directions corresponded to a different stratigraphic package of the LST within the CHC and all have extremely low between-site dispersion (s ˜ 4°) suggesting rather rapid emplacement of the LST packages. Consequently, each cluster has its own unique direction of magnetization. Since the lower two LST packages crop out along the coast line of the Peninsula with different structural trends, an opportunity was presented to test the conclusions of Hnat et al. (2006) that the curvature of the MCR was primary. To that end nine lava flows were sampled on Silver Island and their mean direction compared to the equivalent mean from lava flows sampled by Diehl and Haig (1994) from the tip of the Keweenaw Peninsula (upper lava flows of the Middle LST) which have an entirely different structural trend. Characteristic directions of magnetization of the Silver Island lava flows were isolated either using alternating field, thermal or a combination of both. The mean direction of magnetization for the nine sites is: D = 277.7°, I = 46.9°, α95 = 3.0°, k = 292.5. The mean direction recalculated from the Diehl and Haig study is: D = 277.8°, I = 40.6°, α95 = 2.9°, k = 315.7. Although the declinations of the two means are identical, interestingly the two means are statistically distinct at the 95% confidence level. Fold tests were inconclusive. Nevertheless

  4. The impact of doping rates on the morphologies of silver and gold nanowires grown in helium nanodroplets.

    PubMed

    Volk, Alexander; Thaler, Philipp; Knez, Daniel; Hauser, Andreas W; Steurer, Johannes; Grogger, Werner; Hofer, Ferdinand; Ernst, Wolfgang E

    2016-01-21

    Silver and gold nanowires are grown within superfluid helium nanodroplets and investigated by high resolution electron microscopy after surface deposition. The wire morphologies depend on the rate of metal atom doping in the pickup sequence. While high doping rates result in a polycrystalline face-centered cubic nanowire structure, at lower doping rates the initial fivefold-symmetry seems to be preserved. An explanation for this observation is given by computer simulations, which allow the derivation of timescales for the nanowire growth process inside helium nanodroplets. PMID:26603482

  5. Silver island film substrates for ultrasensitive fluorescence detection of (bio)molecules.

    PubMed

    Szalkowski, Marcin; Ashraf, Khuram U; Lokstein, Heiko; Mackowski, Sebastian; Cogdell, Richard J; Kowalska, Dorota

    2016-01-01

    A silver island film (SIF) substrate was used to demonstrate that Metal-Enhanced Fluorescence (MEF) is a powerful tool to enable detection of emission from (bio)molecules at very low concentrations. The experiments were carried out with the Fenna-Matthews-Olson (FMO) pigment-protein complex from the photosynthetic green sulfur bacterium Chlorobaculum tepidum. FMO was diluted to a level, at which no emission was detectable on a glass substrate. In contrast, the fluorescence of FMO was readily observed on the SIF substrate, even though the emission wavelength of FMO is displaced by over 300 nm from the maximum of the plasmon resonance of the SIF layer. Estimated enhancements of the fluorescence intensity of FMO on SIF are about 40-fold. The enhancement factor correlates with the improvement of the signal-to-noise ratio for FMO emission on SIF substrates.

  6. Origin of bimodal fluorescence enhancement factors of Chlorobaculum tepidum reaction centers on silver island films.

    PubMed

    Maćkowski, Sebastian; Czechowski, Nikodem; Ashraf, Khuram U; Szalkowski, Marcin; Lokstein, Heiko; Cogdell, Richard J; Kowalska, Dorota

    2016-08-01

    We focus on the spectral dependence of plasmon-induced enhancement of fluorescence of Chlorobaculum tepidum reaction centers. When deposited on silver island film, they exhibit up to a 60-fold increase in fluorescence. The dependence of enhancement factors on the excitation wavelength is not correlated with the absorption spectrum of the plasmonic structure. In particular, the presence of one (or multiple) trimers of the Fenna-Matthews-Olson (FMO) protein reveals itself in bimodal distribution of enhancement factors for the excitation at 589 nm, the wavelength corresponding to bacteriochlorophyll absorption of FMO and the core of the RC. We conclude that the structure of multichromophoric complexes can substantially affect the impact of plasmonic excitations, which is important in the context of assembling functional biohybrid systems.

  7. Origin of bimodal fluorescence enhancement factors of Chlorobaculum tepidum reaction centers on silver island films.

    PubMed

    Maćkowski, Sebastian; Czechowski, Nikodem; Ashraf, Khuram U; Szalkowski, Marcin; Lokstein, Heiko; Cogdell, Richard J; Kowalska, Dorota

    2016-08-01

    We focus on the spectral dependence of plasmon-induced enhancement of fluorescence of Chlorobaculum tepidum reaction centers. When deposited on silver island film, they exhibit up to a 60-fold increase in fluorescence. The dependence of enhancement factors on the excitation wavelength is not correlated with the absorption spectrum of the plasmonic structure. In particular, the presence of one (or multiple) trimers of the Fenna-Matthews-Olson (FMO) protein reveals itself in bimodal distribution of enhancement factors for the excitation at 589 nm, the wavelength corresponding to bacteriochlorophyll absorption of FMO and the core of the RC. We conclude that the structure of multichromophoric complexes can substantially affect the impact of plasmonic excitations, which is important in the context of assembling functional biohybrid systems. PMID:27406896

  8. Silver

    Integrated Risk Information System (IRIS)

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

  9. Localized Si enrichment in coherent self-assembled Ge islands grown by molecular beam epitaxy on (001)Si single crystal

    NASA Astrophysics Data System (ADS)

    Valvo, M.; Bongiorno, C.; Giannazzo, F.; Terrasi, A.

    2013-01-01

    Transmission electron microscopy (TEM), atomic force microscopy, and Rutherford backscattering spectrometry (RBS) have been used to investigate the morphology, structure, and composition of self-assembled Ge islands grown on Si (001) substrates by molecular beam epitaxy (MBE) at different temperatures. Increasing the temperature from 550 °C to 700 °C causes progressive size and shape uniformity, accompanied by enhanced Si-Ge intermixing within the islands and their wetting layer. Elemental maps obtained by energy filtered-TEM (EF-TEM) clearly show pronounced Si concentration not only in correspondence of island base perimeters, but also along their curved surface boundaries. This phenomenon is strengthened by an increase of the growth temperature, being practically negligible at 550 °C, while very remarkable already at 650 °C. The resulting island shape is affected, since this localized Si enrichment not only provides strain relief near their highly stressed base perimeters but it also influences the cluster surface energy by effective alloying, so as to form Si-enriched SiGe interfaces. Further increase to 700 °C causes a shape transition where more homogenous Si-Ge concentration profiles are observed. The crucial role played by local "flattened" alloyed clusters, similar to truncated pyramids with larger bases and enhanced Si enrichment at coherently stressed interfaces, has been further clarified by EF-TEM analysis of a multi-layered Ge/Si structure containing stacked Ge islands grown at 650 °C. Sharp accumulation of Si has been here observed not only in proximity of the uncapped island surface in the topmost layer but also at the buried Ge/Si interfaces and even in the core of such capped Ge islands.

  10. Delayed plastic relaxation limit in SiGe islands grown by Ge diffusion from a local source

    SciTech Connect

    Vanacore, G. M.; Zani, M.; Tagliaferri, A.; Nicotra, G.; Bollani, M.; Bonera, E.; Montalenti, F.; Picco, A.; Boioli, F.; Capellini, G.; Isella, G.; Osmond, J.

    2015-03-14

    The hetero-epitaxial strain relaxation in nano-scale systems plays a fundamental role in shaping their properties. Here, the elastic and plastic relaxation of self-assembled SiGe islands grown by surface-thermal-diffusion from a local Ge solid source on Si(100) are studied by atomic force and transmission electron microscopies, enabling the simultaneous investigation of the strain relaxation in different dynamical regimes. Islands grown by this technique remain dislocation-free and preserve a structural coherence with the substrate for a base width as large as 350 nm. The results indicate that a delay of the plastic relaxation is promoted by an enhanced Si-Ge intermixing, induced by the surface-thermal-diffusion, which takes place already in the SiGe overlayer before the formation of a critical nucleus. The local entropy of mixing dominates, leading the system toward a thermodynamic equilibrium, where non-dislocated, shallow islands with a low residual stress are energetically stable. These findings elucidate the role of the interface dynamics in modulating the lattice distortion at the nano-scale, and highlight the potential use of our growth strategy to create composition and strain-controlled nano-structures for new-generation devices.

  11. Delayed plastic relaxation limit in SiGe islands grown by Ge diffusion from a local source

    NASA Astrophysics Data System (ADS)

    Vanacore, G. M.; Nicotra, G.; Zani, M.; Bollani, M.; Bonera, E.; Montalenti, F.; Capellini, G.; Isella, G.; Osmond, J.; Picco, A.; Boioli, F.; Tagliaferri, A.

    2015-03-01

    The hetero-epitaxial strain relaxation in nano-scale systems plays a fundamental role in shaping their properties. Here, the elastic and plastic relaxation of self-assembled SiGe islands grown by surface-thermal-diffusion from a local Ge solid source on Si(100) are studied by atomic force and transmission electron microscopies, enabling the simultaneous investigation of the strain relaxation in different dynamical regimes. Islands grown by this technique remain dislocation-free and preserve a structural coherence with the substrate for a base width as large as 350 nm. The results indicate that a delay of the plastic relaxation is promoted by an enhanced Si-Ge intermixing, induced by the surface-thermal-diffusion, which takes place already in the SiGe overlayer before the formation of a critical nucleus. The local entropy of mixing dominates, leading the system toward a thermodynamic equilibrium, where non-dislocated, shallow islands with a low residual stress are energetically stable. These findings elucidate the role of the interface dynamics in modulating the lattice distortion at the nano-scale, and highlight the potential use of our growth strategy to create composition and strain-controlled nano-structures for new-generation devices.

  12. Photodetection in Hybrid Single-Layer Graphene/Fully Coherent Germanium Island Nanostructures Selectively Grown on Silicon Nanotip Patterns.

    PubMed

    Niu, Gang; Capellini, Giovanni; Lupina, Grzegorz; Niermann, Tore; Salvalaglio, Marco; Marzegalli, Anna; Schubert, Markus Andreas; Zaumseil, Peter; Krause, Hans-Michael; Skibitzki, Oliver; Lehmann, Michael; Montalenti, Francesco; Xie, Ya-Hong; Schroeder, Thomas

    2016-01-27

    Dislocation networks are one of the most principle sources deteriorating the performances of devices based on lattice-mismatched heteroepitaxial systems. We demonstrate here a technique enabling fully coherent germanium (Ge) islands selectively grown on nanotip-patterned Si(001) substrates. The silicon (Si)-tip-patterned substrate, fabricated by complementary metal oxide semiconductor compatible nanotechnology, features ∼50-nm-wide Si areas emerging from a SiO2 matrix and arranged in an ordered lattice. Molecular beam epitaxy growths result in Ge nanoislands with high selectivity and having homogeneous shape and size. The ∼850 °C growth temperature required for ensuring selective growth has been shown to lead to the formation of Ge islands of high crystalline quality without extensive Si intermixing (with 91 atom % Ge). Nanotip-patterned wafers result in geometric, kinetic-diffusion-barrier intermixing hindrance, confining the major intermixing to the pedestal region of Ge islands, where kinetic diffusion barriers are, however, high. Theoretical calculations suggest that the thin Si/Ge layer at the interface plays, nevertheless, a significant role in realizing our fully coherent Ge nanoislands free from extended defects especially dislocations. Single-layer graphene/Ge/Si-tip Schottky junctions were fabricated, and thanks to the absence of extended defects in Ge islands, they demonstrate high-performance photodetection characteristics with responsivity of ∼45 mA W(-1) and an Ion/Ioff ratio of ∼10(3). PMID:26709534

  13. Microstructure of spinel islands on the sapphire surface grown by ion implantation and annealing.

    PubMed

    Wang, Y; Liu, X P; Qin, G W

    2014-09-01

    Fe ions were implanted into α-Al2O3 single crystals (sapphire) at energy of 50 keV and annealed in an oxidizing environment. Transmission electron microscopy (TEM) investigation indicated that Fe ions in the near surface region precipitated as α-Fe2O3 islands and spinel islands on the specimen surface, at the same time, Fe ions in the region away from the surface precipitated as α-Fe particles in the interior region of specimen. Two orientation relationships (ORs) between the spinel islands and sapphire substrate were discovered as follows: (111)spinel∥(0001)sapphire, [1 1 2¯]spinel∥[1 1 2¯ 0]sapphire and (1 1 2¯)spinel∥(0 0 0 1)sapphire, [1 1 1]spinel∥[1 1 2¯ 0]sapphire. The first OR was frequently observed in the spinel/sapphire system, however, the second OR has never been reported before. The interfaces between the spinel islands and sapphire substrate are a type-3 incoherent interface (i.e. low-index OR in at least one direction with an ill-matched low-index habit planes). The formation of spinel islands on the specimen surface can be attributed to the oxidizing atmosphere and the low accelerating voltage for ion implantation.

  14. High prevalence of Salmonella and IMP-4-producing Enterobacteriaceae in the silver gull on Five Islands, Australia

    PubMed Central

    Dolejska, Monika; Masarikova, Martina; Dobiasova, Hana; Jamborova, Ivana; Karpiskova, Renata; Havlicek, Martin; Carlile, Nicholas; Priddel, David; Cizek, Alois; Literak, Ivan

    2016-01-01

    Objectives The objective of this study was to investigate the silver gull as an indicator of environmental contamination by salmonellae and carbapenemase-producing Enterobacteriaceae (CPE) in south-east Australia. Methods A total of 504 cloacal samples were collected from gull chicks at three nesting colonies in New South Wales, Australia [White Bay (n = 144), Five Islands (n = 200) and Montague Island (n = 160)] and were examined for salmonellae and CPE. Isolates were tested for carbapenemase genes and susceptibility to 14 antibiotics. Clonality was determined by PFGE and MLST. Genetic context and conjugative transfer of the carbapenemase gene were determined. Results A total of 120 CPE of 10 species, mainly Escherichia coli (n = 85), carrying the gene blaIMP-4, blaIMP-38 or blaIMP-26 were obtained from 80 (40%) gulls from Five Islands. Thirty percent of birds from this colony were colonized by salmonellae. Most isolates contained the gene within a class 1 integron showing a blaIMP-4-qacG-aacA4-catB3 array. The blaIMP gene was carried by conjugative plasmids of variable sizes (80–400 kb) and diverse replicons, including HI2-N (n = 30), HI2 (11), A/C (17), A/C-Y (2), L/M (5), I1 (1) and non-typeable (6). Despite the overall high genetic variability, common clones and plasmid types were shared by different birds and bacterial isolates, respectively. Conclusions Our data demonstrate a large-scale transmission of carbapenemase-producing bacteria into wildlife, likely as a result of the feeding habits of the birds at a local waste depot. The isolates from gulls showed significant similarities with clinical isolates from Australia, suggesting the human origin of the isolates. The sources of CPE for gulls on Five Islands should be explored and proper measures applied to stop the transmission into the environment. PMID:26472769

  15. Fourier transform surface-enhanced Raman scattering of single-layer nucleolipid Langmuir-Blodgett films on silver island film substrates.

    PubMed

    Wu, Sanxie; Huang, Jianguo; Li, Chun; Liang, Yingqiu

    2004-02-15

    Surface-enhanced Raman scattering (SERS) spectra of four amphiphilic nucleolipids in single-layer Langmuir-Blodgett (LB) films deposited on silver island film substrates from pure water and complementary nucleotide-containing subphase and corresponding powder normal Raman spectra were obtained. The analysis of these spectra indicates that the SERS effect is mainly caused by a charge-transfer mechanism, and only the nucleobase headgroup moieties and complementary bases combined with them through hydrogen bonds, which are directly in contact with the silver island film substrates, could be enhanced. For the amphiphilic nucleolipids with the identical nucleobase headgroups, the SERS spectra of the LB films are similar, implying that the orientations of these nucleobase moieties on the silver substrates are analogous. However, the nucleobase takes different orientations on the silver substrates before and after complementary binding. The nucleobases in the LB films deposited from pure water are nearly lying flat on the silver surface, while the complementary binding pairs transferred from the air/water interface tend to take an end-on orientation on the metal surface.

  16. Somatic mutation frequencies in the stamen hairs of Tradescantia grown in soil samples from the Bikini Island.

    PubMed

    Ichikawa, S; Ishii, C

    1991-02-01

    Somatic pink mutation frequencies in the stamen hairs of Tradescantia BNL 02 clone grown for 76 days in two soil samples taken from the Bikini Island (where a hydrogen bomb explosion test had been conducted in 1954) were investigated. A significantly high mutation frequency (2.58 +/- 0.17 pink mutant events per 10(3) hairs or 1.34 +/- 0.09 pink mutant events per 10(4) hair-cell divisions) was observed for the plant grown in one of the two Bikini soil samples, as compared to the control plants (1.70 +/- 0.14 or 0.88 +/- 0.07, respectively) grown in the field soil of Saitama University. The soil sample which caused the significant increase in mutation frequency contained 6,880 +/- 330 mBq/g 137Cs, 62.5 +/- 4.4 mBq/g 60Co, and some other nuclides; a 150 microR/hr exposure rate being measured on the surface of the soil sample. The effective cumulative external exposures measured for the inflorescences of the plant grown in this soil sample averaged at most 60.8 mR, being too small to explain the significant elevation in mutation frequency observed. On the other hand, internal exposure due to uptake of radioactive nuclides was estimated to be 125 mrad (1.25 mGy) as an accumulated effective dose, mainly based on a gamma-spectrometrical analysis. However, it seemed highly likely that this value of internal exposure was a considerable underestimate, and the internal exposure was considered to be more significant than the external exposure. PMID:2064800

  17. Somatic mutation frequencies in the stamen hairs of Tradescantia grown in soil samples from the Bikini Island.

    PubMed

    Ichikawa, S; Ishii, C

    1991-02-01

    Somatic pink mutation frequencies in the stamen hairs of Tradescantia BNL 02 clone grown for 76 days in two soil samples taken from the Bikini Island (where a hydrogen bomb explosion test had been conducted in 1954) were investigated. A significantly high mutation frequency (2.58 +/- 0.17 pink mutant events per 10(3) hairs or 1.34 +/- 0.09 pink mutant events per 10(4) hair-cell divisions) was observed for the plant grown in one of the two Bikini soil samples, as compared to the control plants (1.70 +/- 0.14 or 0.88 +/- 0.07, respectively) grown in the field soil of Saitama University. The soil sample which caused the significant increase in mutation frequency contained 6,880 +/- 330 mBq/g 137Cs, 62.5 +/- 4.4 mBq/g 60Co, and some other nuclides; a 150 microR/hr exposure rate being measured on the surface of the soil sample. The effective cumulative external exposures measured for the inflorescences of the plant grown in this soil sample averaged at most 60.8 mR, being too small to explain the significant elevation in mutation frequency observed. On the other hand, internal exposure due to uptake of radioactive nuclides was estimated to be 125 mrad (1.25 mGy) as an accumulated effective dose, mainly based on a gamma-spectrometrical analysis. However, it seemed highly likely that this value of internal exposure was a considerable underestimate, and the internal exposure was considered to be more significant than the external exposure.

  18. A geological and geophysical study of the gold-silver vein system of Unga Island, Southwestern Alaska

    USGS Publications Warehouse

    Riehle, James R., (Edited By)

    1999-01-01

    Overview of the CD-ROM Contents: The topic of this CD-ROM is the geologic framework of gold-silver vein deposits on Unga Island, in the Shumagin Islands, southwestern Alaska. The core of the publication is a new geologic map at a scale of 1:63,360 and aeromagnetic and electromagnetic survey data acquired by industry over the area of mineralization. Both the geologic map as well as a preliminary interpretation of the geophysical data--which are included by permission of the owner--are aimed towards deciphering the relations among volcanism, tectonism, and mineralization. Data and discussions are organized in seven chapters, titles of which are outlined in the table of contents. The chapters consist of viewable text and figure images; postscript versions of the frontispiece figures and all chapter figures are included on the CD-ROM as well. The geologic map is a large viewable figure (Plate 1) that accompanies chapter 2. The map was constructed in ARC and its component coverages are provided in the folder 'Geology' for users who may wish to modify the geologic data or add their own data.

  19. Size, shape, and ordering of SiGe/Si(001) islands grown by means of liquid phase epitaxy under far-nonequilibrium growth conditions

    SciTech Connect

    Hanke, M.; Boeck, T.; Gerlitzke, A.-K.; Syrowatka, F.; Heyroth, F.; Koehler, R.

    2005-04-04

    Applying scanning electron microscopy, we have studied the evolution of shape and lateral positional correlation of Si{sub 1-x}Ge{sub x}/Si(001) Stranski-Krastanov islands grown by means of liquid phase epitaxy (LPE). However, in contrast to conventional near-equilibrium LPE, a distinctly higher cooling rate of 10 K/min ensures extremly nonequilibrium growth conditions. The facet inclination of subsequent island stages decreases from nearly vertical sidewalls toward {l_brace}111{r_brace}- and {l_brace}101{r_brace}-type facets. Energy dispersive x-ray microanalysis yields a size-independent germanium content of 8.9% within islands between 760 and 1700 nm base width which is--by more than a factor of 2--smaller than islands of the same concentration grown in a near-equilibrium LPE process. Square-like formations of subsequently smaller islands around a large central island indicate only next to island interactions during the lateral self-assembling.

  20. Quality assessment of Japanese knotweed (Fallopia japonica) grown on Prince Edward Island as a source of resveratrol.

    PubMed

    Chen, Huaguo; Tuck, Tina; Ji, Xiuhong; Zhou, Xin; Kelly, Glen; Cuerrier, Alain; Zhang, Junzeng

    2013-07-01

    Japanese knotweed (Fallopia japonica , also known as Polygonum cuspidatum) is a common invasive plant species on Prince Edward Island (PEI), Canada, whereas it has been used in Chinese medicine and more recently as a raw material for extracting resveratrol. This paper reports on the quantification of resveratrol, polydatin, emodin, and physcion in roots, stems, and leaves of Japanese knotweed samples from PEI and British Columbia (BC), Canada, and nine provinces of China, by ultraperformance liquid chromatography (UPLC). The results showed that the root contains a much higher level of resveratrol than the stem and leaf, and it is accumulated in its highest level in October. PEI-grown knotweed contains similar levels of resveratrol and polydatin compared to Chinese samples collected in the month of October, but the contents of the other anthraquinones (emodin and physcion) are different. As such, Japanese knotweed grown in PEI could be a commercially viable source of raw material for resveratrol production; however, caution has to be taken in harvesting the right plant species. PMID:23742076

  1. Microstructure analysis of epitaxially grown self-assembled Ge islands on nanometer-scale patterned SiO2/Si substrates by high-resolution transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Yoon, Tae-Sik; Kim, Hyun-Mi; Kim, Ki-Bum; Ryu, Du Yeol; Russell, Thomas P.; Zhao, Zuoming; Liu, Jian; Xie, Ya-Hong

    2007-11-01

    The microstructure of epitaxially grown self-assembled Ge islands on patterned SiO2/Si substrates was analyzed using high resolution transmission electron microscopy. The Ge islands were grown by molecular beam epitaxy on hexagonally ordered Si hole arrays with ˜25 nm diameter and ˜40 nm center-to-center distance, which are covered by 30 nm thick SiO2 mask layer patterned using self-assembled diblock copolymers. The Ge islands nucleate preferentially at the edge of overetched Si surface, and subsequently grow selectively on Si surface as opposed to SiO2 surface with increasing coverage. The lattice planes of some Ge islands are tilted from those of Si substrates. This is believed to be the reason for the observed misalignment of moiré fringes. The diameter of the Ge islands is identical to that of Si holes for large Ge coverage due to the selective growth behavior. These islands are found to have dislocations at the interface with the Si substrate. These results highlight the important microstructural issues and growth behavior of quantum dots on patterned substrates.

  2. Composition of volatile in micropropagated and field grown aromatic plants from Tuscany Islands.

    PubMed

    Pistelli, Laura; Noccioli, Cecilia; D'Angiolillo, Francesca; Pistelli, Luisa

    2013-01-01

    Aromatic plant species present in the natural Park of Tuscany Archipelago are used as flavoring agents and spices, as dietary supplements and in cosmetics and aromatherapy. The plants are usually collected from wild stands, inducing a depletion of the natural habitat. Therefore, micropropagation of these aromatic plants can play a role in the protection of the natural ecosystem, can guarantee a massive sustainable production and can provide standardized plant materials for diverse economical purposes. The aim of this study is to compare the volatile organic compounds produced by the wild plants with those from in vitro plantlets using headspace solid phase micro-extraction (HS-SPME) followed by capillary gas-chromatography coupled to mass spectrometry (GC-MS). Typical plants of this natural area selected for this work were Calamintha nepeta L., Crithmum maritimum L., Lavandula angustifolia L., Myrtus communis L., Rosmarinus officinalis L., Salvia officinalis L. and Satureja hortensis L. Different explants were used: microcuttings with vegetative apical parts, axillary buds and internodes. Sterilization percentage, multiplication rate and shoot length, as well as root formation were measured. The volatile aromatic profiles produced from in vitro plantlets were compared with those of the wild plants, in particular for C. maritimum, R. officinalis, S. officinalis and S. hortensis. This study indicated that the micropropagation technique can represent a valid alternative to produce massive and sterile plant material characterised by the same aromatic flavour as in the wild grown plants. PMID:23441303

  3. Photoreduced silver nanoparticles grown on femtosecond laser ablated, D-shaped fiber probe for surface-enhanced Raman scattering.

    PubMed

    Yin, Zhen; Geng, Youfu; Xie, Qingli; Hong, Xueming; Tan, Xiaoling; Chen, Yuzhi; Wang, Lele; Wang, Wenjia; Li, Xuejin

    2016-07-10

    Surface-enhanced Raman scattering (SERS) probes are made by facile photochemical deposition of silver nanoparticles on a femtosecond (fs) laser ablated, D-shaped fiber. The structure and surface morphology of the probe are investigated by scanning electron microscopy. High-quality SERS signals are detected using Rhodamine 6G molecules via an in situ sensing mode. Experimental results show that the SERS signals increase with the increase of the length of fs laser ablated, D-shaped zone. Our D-shaped fiber SERS probe shows a feasible method for a large active area, high performance, and real-time and remote measurement of SERS signals in biochemical analysis. PMID:27409318

  4. Localized surface plasmon induced enhancement of electron-hole generation with silver metal island at n-Al:ZnO/p-Cu{sub 2}O heterojunction

    SciTech Connect

    Kaur, Gurpreet Yadav, K. L.; Mitra, Anirban

    2015-08-03

    Localized surface plasmon induced generation of electron-hole pairs with inclusion of metal islands of noble metal like Ag can enhance the photocurrent. A heterostructure of n-Al:ZnO/p-Cu{sub 2}O with inclusion of Ag metalislands at the junction has been fabricated. I-V characteristic curve of these heterostructures shows a significant enhancement of photocurrent under the illumination (1.5 AMU). This enhancement of photocurrent is attributed to the supply of hot electrons generated in silver metal nanoislands. It has also been shown that inclusion of metal islands increases the absorption of solar spectrum in visible region at 500 nm. Enhancement of photocurrent may also be due to the direct resonance energy transfer from Localized Surface Plasmons of metal islands to Cu{sub 2}O.

  5. Structural and optical properties of dense vertically aligned ZnO nanorods grown onto silver and gold thin films by galvanic effect with iron contamination

    SciTech Connect

    Scarpellini, D.; Paoloni, S.; Medaglia, P.G.; Pizzoferrato, R.; Orsini, A.; Falconi, C.

    2015-05-15

    Highlights: • ZnO nanorods were grown on Au and Ag films in aqueous solution by galvanic effect. • The method is prone to metal contamination which can influence the ZnO properties. • Iron doping improves the lattice matching between ZnO and the substrate. • Energy levels of point defects are lowered and the light emission is red-shifted. • Galvanic-induced nucleation starts and proceeds continuously during the growth. - Abstract: Dense arrays of vertically aligned ZnO nanorods have been grown onto either silver or gold seedless substrates trough a simple hydrothermal method by exploiting the galvanic effect between the substrate and metallic parts. The nanorods exhibit larger bases and more defined hexagonal shapes, in comparison with standard non-galvanic wet-chemistry synthesis. X-ray diffraction (XRD) shows that the iron contamination, associated with the galvanic contact, significantly improves the in-plane compatibility of ZnO with the Au and Ag cubic lattice. Photoluminescence (PL) measurements indicate that the contamination does not affect the number density of localized defects, but lowers their energy levels uniformly; differently, the band-edge emission is not altered appreciably. Finally, we have found that the ZnO hetero-nucleation by galvanic effect initiates at different times in different sites of the substrate area. Our results can be useful for the fabrication of high performance piezonanodevices comprising high-density metal-to-ZnO nanoscaled junctions without intermediate polycrystalline layers.

  6. Atmospheric pressure plasma enhanced spatial ALD of silver

    SciTech Connect

    Bruele, Fieke J. van den Smets, Mireille; Illiberi, Andrea; Poodt, Paul; Buskens, Pascal; Roozeboom, Fred

    2015-01-15

    The authors have investigated the growth of thin silver films using a unique combination of atmospheric process elements: spatial atomic layer deposition and an atmospheric pressure surface dielectric barrier discharge plasma source. Silver films were grown on top of Si substrates with good purity as revealed by resistivity values as low as 18 μΩ cm and C- and F-levels below detection limits of energy dispersive x-ray analysis. The growth of the silver films starts through the nucleation of islands that subsequently coalesce. The authors show that the surface island morphology is dependent on surface diffusion, which can be controlled by temperature within the deposition temperature range of 100–120 °C.

  7. Effects of green-synthesized silver nanoparticles on lung cancer cells in vitro and grown as xenograft tumors in vivo

    PubMed Central

    He, Yan; Du, Zhiyun; Ma, Shijing; Liu, Yue; Li, Dongli; Huang, Huarong; Jiang, Sen; Cheng, Shupeng; Wu, Wenjing; Zhang, Kun; Zheng, Xi

    2016-01-01

    Silver nanoparticles (AgNPs) have now been recognized as promising therapeutic molecules and are extending their use in cancer diagnosis and therapy. This study demonstrates for the first time the antitumor activity of green-synthesized AgNPs against lung cancer in vitro and in vivo. Cytotoxicity effect was explored on human lung cancer H1299 cells in vitro by MTT and trypan blue assays. Apoptosis was measured by morphological assessment, and nuclear factor-κB (NF-κB) transcriptional activity was determined by a luciferase reporter gene assay. The expressions of phosphorylated stat3, bcl-2, survivin, and caspase-3 were examined by Western blot analysis. AgNPs showed dose-dependent cytotoxicity and stimulation of apoptosis in H1299 cells. The effects on H1299 cells correlated well with the inhibition of NF-κB activity, a decrease in bcl-2, and an increase in caspase-3 and survivin expression. AgNPs significantly suppressed the H1299 tumor growth in a xenograft severe combined immunodeficient (SCID) mouse model. The results demonstrate the anticancer activities of AgNPs, suggesting that they may act as potential beneficial molecules in lung cancer chemoprevention and chemotherapy, especially for early-stage intervention. PMID:27217750

  8. Photocatalytic Properties of Silver Core/Titania Shell Nano-Wires Grown on a Glass Substrate Using a Glycothermal Process Assisted by a Photochemical Reaction.

    PubMed

    Song, Duck-Hyun; Hirato, Tetsuji

    2015-07-01

    A silver core/titania shell nano-wire film was successfully prepared on a glass substrate via a glycothermal process that was assisted by a photochemical reaction using tetra-n-butyl titanate as the titanium source and silver nitrate as the silver source in an autoclave with ethylene glycol as a solvent. The morphology, diameter, length, and density of the core/shell nano-wires that were synthesized could be varied by changing the silver/titanium molar ratio of the starting materials. The samples produced were characterized by X-ray diffraction and scanning electron microscopy. The photocatalytic activity of the silver core/titania shell nano-wire film was investigated by measuring the photodegradation rate of rhodamine B in aqueous solution. PMID:26373082

  9. Plasmon-Enhanced Enzymatic Reactions 2:Optimization of Enzyme Activity by Surface Modification of Silver Island Films with Biotin-Poly (Ethylene-glycol)-Amine.

    PubMed

    Abel, Biebele; Aslan, Kadir

    2012-01-01

    Surface modification of silver island films (SIFs) was carried out with Biotin-Poly (Ethylene-glycol)-Amine (BEA), which acts as a cross-linker between the silver surface and horse radish peroxidase (HRP) enzyme for optimum plasmon-enhanced enzymatic activity. SIFs-deposited blank glass slides and SIFs-deposited 3-Aminopropyltriethoxysilane(APTES)-coated glass slides were used as our plasmonic surfaces.In this regard, three different extent of loading of SIFs were also prepared (low, medium and high) on APTES-coated glass slides. Streptavidin-linked HRP enzyme was attached to SIFs-deposited blank glass slides and SIFs-deposited APTES-coated glass slides through the well-known biotin-streptavidin interactions. The characterization of these surfaces was done using optical absorption spectroscopy. The loading of SIFs on glass slides was observed to have significant effect on the efficiency of plasmon-enhanced enzymatic activity, where an enhancement of 200% in the enzymatic activity was observed when compared to our previously used strategies for enzyme immobilization in our preceding work[1]. In addition, SIFs-deposited on APTES-coated glass slides were found to be re-usable for plasmon-enhanced enzymatic reactions unlike SIFs deposited on to blank glass slides. PMID:22485194

  10. NaCl multi-layer islands grown on Au(111)-([Formula: see text]) probed by scanning tunneling microscopy.

    PubMed

    Sun, Xiaonan; Felicissimo, Marcella P; Rudolf, Petra; Silly, Fabien

    2008-12-10

    The growth of multi-layer NaCl islands on Au(111)-([Formula: see text]) surfaces was investigated using scanning tunneling microscopy (STM). We observed that the aspect of the NaCl islands drastically differs depending on the tunneling conditions. It is therefore possible to observe the layers forming an NaCl island or to image the gold reconstruction below the first NaCl layer. Atomically resolved STM images obtained on the first NaCl layer demonstrate that NaCl grows as an epitaxial crystalline film on Au(111)-([Formula: see text]). STM images also suggest that some NaCl layers can be non-crystalline. PMID:21730671

  11. Size Evolution of Ordered SiGe Islands Grown by Surface Thermal Diffusion on Pit-Patterned Si(100) Surface

    PubMed Central

    2010-01-01

    The ordered growth of self-assembled SiGe islands by surface thermal diffusion in ultra high vacuum from a lithographically etched Ge stripe on pit-patterned Si(100) surface has been experimentally investigated. The total surface coverage of Ge strongly depends on the distance from the source stripe, as quantitatively verified by Scanning Auger Microscopy. The size distribution of the islands as a function of the Ge coverage has been studied by coupling atomic force microscopy scans with Auger spectro-microscopy data. Our observations are consistent with a physical scenario where island positioning is essentially driven by energetic factors, which predominate with respect to the local kinetics of diffusion, and the growth evolution mainly depends on the local density of Ge atoms. PMID:21170398

  12. Silver island films as substrate for surface-enhanced Raman spectroscopy (SERS): a methodological study on their application to artists' red dyestuffs

    NASA Astrophysics Data System (ADS)

    Whitney, Alyson V.; Van Duyne, Richard P.; Casadio, Francesca

    2005-11-01

    Surface enhanced Raman spectroscopy (SERS) has enormous capabilities for the unambiguous identification of artists' red lake pigments and dyestuff. Until now, red lake pigments have been very poorly characterized with conventional Raman spectroscopy due to their high fluorescence and weak Raman scattering cross section. Furthermore, very small amount of dyestuff is necessary to achieve intense deep colors; therefore a characterization method with enhanced sensitivity is needed to accurately identify the dyestuff. This study focuses on two red dyestuffs, carminic acid and laccaic acid, which are extensively utilized in old masters' paintings. We propose an innovative sensing method using 6 nm silver island films (AgIFs) fabricated with electron beam (e-beam) deposition on the colorant particles under investigation. The results of an in-depth methodological investigation into the signal-enhancement achievable with various experimental conditions applied to these substrates are presented. We explore the effects of varying laser excitation frequencies (532.15 nm 632.8nm and 785.7 nm), laser power at the sample and we investigate the dependence of S/N in the spectra from different spot sizes. Finally, the sensitivity of the method is determined. The results of the semi-quantitative analysis have allowed us to determine the best experimental conditions to achieve the highest sensitivity in the investigation of this important class of artists' colorants.

  13. Superconductivity in epitaxially grown self-assembled indium islands: progress towards hybrid superconductor/semiconductor optical sources

    DOE PAGESBeta

    Gehl, Michael; Gibson, Ricky; Zandbergen, Sander; Keiffer, Patrick; Sears, Jasmine; Khitrova, Galina

    2016-02-01

    Currently, superconducting qubits lead the way in potential candidates for quantum computing. This is a result of the robust nature of superconductivity and the non-linear Josephson effect which make possible many types of qubits. At the same time, transferring quantum information over long distances typically relies on the use of photons as the elementary qubit. Converting between stationary electronic qubits in superconducting systems and traveling photonic qubits is a challenging yet necessary goal for the interface of quantum computing and communication. The most promising path to achieving this goal appears to be the integration of superconductivity with optically active semiconductors,more » with quantum information being transferred between the two by means of the superconducting proximity effect. Obtaining good interfaces between superconductor and semiconductor is the next obvious step for improving these hybrid systems. As a result, we report on our observation of superconductivity in self-assembled indium structures grown epitaxially on the surface of semiconductor material.« less

  14. Photo-induced valence change of the sulfur atom in an L-cysteine thin film grown on a silver metal substrate in a saliva-emulated aqueous solution

    NASA Astrophysics Data System (ADS)

    Tsujibayashi, Toru; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao

    2015-04-01

    A thin film of L-cysteine (HSCH2CH(NH2)COOH) is grown on a silver substrate in saliva-emulated aqueous solution. X-ray photoemission spectroscopic measurements have revealed that the sulfur atom shows valence change under IR laser irradiation at 825 nm. The valence change maintains for about a minute at room temperature and more than an hour between 110 and 250 K after stopping the laser irradiation. It is not observed at all at temperatures lower than 110 K. This temperature-dependent behavior indicates that the photo-excited electronic change should be accompanied by a conformational change in the L-cysteine molecule. It is strongly suggested that the reversible valence change of the sulfur atom is applicable to a memory used around room temperature.

  15. Photo-induced valence change of the sulfur atom in an L-cysteine thin film grown on a silver metal substrate in a saliva-emulated aqueous solution

    SciTech Connect

    Tsujibayashi, Toru; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao

    2015-04-27

    A thin film of L-cysteine (HSCH{sub 2}CH(NH{sub 2})COOH) is grown on a silver substrate in saliva-emulated aqueous solution. X-ray photoemission spectroscopic measurements have revealed that the sulfur atom shows valence change under IR laser irradiation at 825 nm. The valence change maintains for about a minute at room temperature and more than an hour between 110 and 250 K after stopping the laser irradiation. It is not observed at all at temperatures lower than 110 K. This temperature-dependent behavior indicates that the photo-excited electronic change should be accompanied by a conformational change in the L-cysteine molecule. It is strongly suggested that the reversible valence change of the sulfur atom is applicable to a memory used around room temperature.

  16. Influence of site, season, silvering stage, and length on the parasites of the European eel Anguilla anguilla in two Mediterranean coastal lagoons of the island of Corsica, France using indicator species method.

    PubMed

    Filippi, Jean-José; Quilichini, Yann; Foata, Joséphine; Marchand, Bernard

    2013-08-01

    The parasites of 425 European eels, Anguilla anguilla, were studied between 2009 and 2012 in two Mediterranean coastal lagoons of the island of Corsica, France. An indicator value (IndVal) method was used for analysis, which combines measures of fidelity and specificity. Because of its resilience to detect changes in abundance, IndVal is an effective ecological bioindicator. The IndVal method demonstrated that site, season, silvering stage, and length could influence the occurrence of parasite species in European eel. A randomization test identified ten parasite species as having a significant indicator value for site (lagoons differed principally in salinity: oligohaline to polyhaline for the Biguglia lagoon and polyhaline to euhaline for the Urbino lagoon; the digeneans Bucephalus anguillae and Lecithochirium musculus, the cestodes Bothriocephalus claviceps, Proteocephalus macrocephalus, and larvae of Myzophyllobothrium sp., the nematodes Anguillicoloides crassus, and encysted larvae of Contracaecum sp., the acanthocephalan Acanthocephaloides incrassatus, the monogenean Pseudodactyogyrus anguillae, and the copepod Ergasilus gibbus); one parasite species for the spring season (the acanthocephalan A. incrassatus); six parasite species for silvering stage (yellow, pre-silver, silver; the trematodes B. anguillae and Deropristis inflata, encysted larvae of the nematode Contracaecum sp., the acanthocephalan A. incrassatus, the monogenean P. anguillae, and the copepod E. gibbus); and three parasite species for some of the five length classes (the cestode P. macrocephalus, encysted larvae of the nematode Contracaecum sp., and the monogenean P. anguillae). Data for species composition and infection levels should help to improve the management of parasitism in the populations of European eels.

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

    SciTech Connect

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

    2010-01-01

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

  18. Silver Sulfadiazine

    MedlinePlus

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

  19. Emission of volatile organic compounds from two silver birch ( Betula pendula Roth) clones grown under ambient and elevated CO 2 and different O 3 concentrations

    NASA Astrophysics Data System (ADS)

    Vuorinen, Terhi; Nerg, Anne-Marja; Vapaavuori, Elina; Holopainen, Jarmo K.

    We analysed the emission of volatile organic compounds (VOCs) from two clones (4 and 80) of silver birch ( Betula pendula Roth) trees exposed to doubled ambient CO 2 and O 3 singly and in combination, in open-top chambers. VOCs were collected in July and in August from detached twigs. The effect of twig detachment as such on emissions was separately studied, and it increased the emissions of green leaf volatiles. The emission in July from both clones was dominated by sesquiterpenes (SQTs) germacrene D, ( E,E)- α-farnesene, α-copaene and β-bourbonene, while in August, the emission was dominated by monoterpenes (MTs) ( E)- β-ocimene and ( Z)-ocimene. Elevated CO 2 concentration marginally decreased total MT emission in July, while in August the total MT emission was enhanced by elevated CO 2. O 3 or CO 2+O 3-exposure did not have any effect on total MT or total SQT emissions. In general clones 4 and 80 emitted total quantified VOCs (19 compounds) 12520 and 8590 ng g -1 fw h -1 in July, and 4640 and 4990 ng g -1 fw h -1 in August, respectively. Clone 4 emitted more β-pinene+myrcene, ( Z)-ocimene and ( E)- β-ocimene in July than clone 80, which emitted more linalool in July, and hexanal in August than clone 4. Elevated CO 2 tended to decrease the emissions of nonanal and ( E)- β-ocimene in July, while O 3 and CO 2+O 3 had no effects on emissions. Our results indicate that elevated CO 2 and O 3 concentrations do not have considerable effect on silver birch emissions by increasing the carbon allocation to VOCs or by inducing the emission of novel compounds. Other factors, such as temperature, light and herbivores might conceal the effects of these atmospheric gases. High SQT proportion in emission profile suggests that B. pendula may have substantial role in biogenic aerosol formation in boreal forests.

  20. Rapid and long-term effects of water deficit on gas exchange and hydraulic conductance of silver birch trees grown under varying atmospheric humidity

    PubMed Central

    2014-01-01

    Background Effects of water deficit on plant water status, gas exchange and hydraulic conductance were investigated in Betula pendula under artificially manipulated air humidity in Eastern Estonia. The study was aimed to broaden an understanding of the ability of trees to acclimate with the increasing atmospheric humidity predicted for northern Europe. Rapidly-induced water deficit was imposed by dehydrating cut branches in open-air conditions; long-term water deficit was generated by seasonal drought. Results The rapid water deficit quantified by leaf (ΨL) and branch water potentials (ΨB) had a significant (P < 0.001) effect on gas exchange parameters, while inclusion of ΨB in models resulted in a considerably better fit than those including ΨL, which supports the idea that stomatal openness is regulated to prevent stem rather than leaf xylem dysfunction. Under moderate water deficit (ΨL≥-1.55 MPa), leaf conductance to water vapour (gL), transpiration rate and leaf hydraulic conductance (KL) were higher (P < 0.05) and leaf temperature lower in trees grown in elevated air humidity (H treatment) than in control trees (C treatment). Under severe water deficit (ΨL<-1.55 MPa), the treatments showed no difference. The humidification manipulation influenced most of the studied characteristics, while the effect was to a great extent realized through changes in soil water availability, i.e. due to higher soil water potential in H treatment. Two functional characteristics (gL, KL) exhibited higher (P < 0.05) sensitivity to water deficit in trees grown under increased air humidity. Conclusions The experiment supported the hypothesis that physiological traits in trees acclimated to higher air humidity exhibit higher sensitivity to rapid water deficit with respect to two characteristics - leaf conductance to water vapour and leaf hydraulic conductance. Disproportionate changes in sensitivity of stomatal versus leaf hydraulic conductance to water deficit

  1. Influence of site, season, silvering stage, and length on the parasites of the European eel Anguilla anguilla in two Mediterranean coastal lagoons of the island of Corsica, France using indicator species method.

    PubMed

    Filippi, Jean-José; Quilichini, Yann; Foata, Joséphine; Marchand, Bernard

    2013-08-01

    The parasites of 425 European eels, Anguilla anguilla, were studied between 2009 and 2012 in two Mediterranean coastal lagoons of the island of Corsica, France. An indicator value (IndVal) method was used for analysis, which combines measures of fidelity and specificity. Because of its resilience to detect changes in abundance, IndVal is an effective ecological bioindicator. The IndVal method demonstrated that site, season, silvering stage, and length could influence the occurrence of parasite species in European eel. A randomization test identified ten parasite species as having a significant indicator value for site (lagoons differed principally in salinity: oligohaline to polyhaline for the Biguglia lagoon and polyhaline to euhaline for the Urbino lagoon; the digeneans Bucephalus anguillae and Lecithochirium musculus, the cestodes Bothriocephalus claviceps, Proteocephalus macrocephalus, and larvae of Myzophyllobothrium sp., the nematodes Anguillicoloides crassus, and encysted larvae of Contracaecum sp., the acanthocephalan Acanthocephaloides incrassatus, the monogenean Pseudodactyogyrus anguillae, and the copepod Ergasilus gibbus); one parasite species for the spring season (the acanthocephalan A. incrassatus); six parasite species for silvering stage (yellow, pre-silver, silver; the trematodes B. anguillae and Deropristis inflata, encysted larvae of the nematode Contracaecum sp., the acanthocephalan A. incrassatus, the monogenean P. anguillae, and the copepod E. gibbus); and three parasite species for some of the five length classes (the cestode P. macrocephalus, encysted larvae of the nematode Contracaecum sp., and the monogenean P. anguillae). Data for species composition and infection levels should help to improve the management of parasitism in the populations of European eels. PMID:23739809

  2. Passive particle dosimetry. [silver halide crystal growth

    NASA Technical Reports Server (NTRS)

    Childs, C. B.

    1977-01-01

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

  3. High-resolution transmission electron microscopy study on the growth modes of GaSb islands grown on a semi-insulating GaAs (001) substrate

    NASA Astrophysics Data System (ADS)

    Kim, Y. H.; Lee, J. Y.; Noh, Y. G.; Kim, M. D.; Oh, J. E.

    2007-06-01

    The initial growth behaviors of GaSb on a GaAs substrate were studied using a high-resolution electron microscope (HRTEM). Four types of GaSb islands were observed by HRTEM. HRTEM micrographs showed that strain relaxation mechanisms were different in the four types of islands. Although 90° misfit dislocations relieve misfit strain in the islands, additional mechanisms are required to relax the remaining strain. The existence of elastic deformation near the surface related to dislocations and intermediate layers between GaSb and GaAs were demonstrated in island growths. Finally, the generation of planar defects to relieve strain was observed in a specific GaSb growth.

  4. Tris(phosphino)borato silver(I) complexes as precursors for metallic silver aerosol-assisted chemical vapor deposition.

    PubMed

    McCain, Matthew N; Schneider, Sven; Salata, Michael R; Marks, Tobin J

    2008-04-01

    A series of light- and air-stable tris(phosphino)borato silver(I) complexes has been synthesized, structurally and spectroscopically characterized, and implemented in the growth of low resistivity metallic silver thin films by aerosol-assisted chemical vapor deposition (AACVD). Of the four complexes in the series, [RB(CH2PR'2) 3]AgPEt3 (R = Ph (1, 3), (n)Bu (2, 4); R' = Ph (1, 2), (i)Pr (3, 4), complexes 1 and 2 have been characterized by single-crystal X-ray diffraction. Complex 2 represents a significant improvement over previously available nonfluorinated Ag precursors, owing to ease of handling and efficient film deposition characteristics. Thermogravimetric analysis (TGA) shows that the thermolytic properties of these complexes can be significantly modified by altering the ligand structure. Polycrystalline cubic-phase Ag thin films were grown on glass, MgO(100), and 52100 steel substrates. Ag films of thicknesses 3 microm, grown at rates of 14-18 nm/min, exhibit low levels of extraneous element contamination by X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) indicate that film growth proceeds primarily via an island growth (Volmer-Weber) mechanism. PMID:18293915

  5. Fluorescence Enhancements on Silver Colloid Coated Surfaces

    PubMed Central

    Lukomska, Joanna; Malicka, Joanna; Gryczynski, Ignacy; Lakowicz, Joseph R.

    2009-01-01

    We observed a strong, more than 16-fold, enhancement of Texas Red-labeled BSA fluorescence emission when deposited on silver colloid coated surfaces (SCCS). The same labeled protein deposited on silver island films (SIFs) showed an approximate 8-fold fluorescence enhancement. The lifetimes of Texas Red-BSA fluorescence are significantly shorter on silvered surfaces than on uncoated quartz substrate indicating a strong change in radiative decay rate of the dyes. We also observed a 36-fold increased brightness of overlabeled fluorescein-HSA deposited on silver colloid coated surface. Stronger enhancement observed for overlabeled Fl-HSA protein indicates that presence of silver particles partially decreased self-quenching. Our results indicate that surfaces coated with silver colloids are valuable substrates for metal-enhanced fluorescence. PMID:15617384

  6. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

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

  7. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

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

  8. Out-diffused silver island films for surface-enhanced Raman scattering protected with TiO2 films using atomic layer deposition

    PubMed Central

    2014-01-01

    We fabricated self-assembled silver nanoisland films using a recently developed technique based on out-diffusion of silver from an ion-exchanged glass substrate in reducing atmosphere. We demonstrate that the position of the surface plasmon resonance of the films depends on the conditions of the film growth. The resonance can be gradually shifted up to 100 nm towards longer wavelengths by using atomic layer deposition of titania, from 3 to 100 nm in thickness, upon the film. Examination of the nanoisland films in surface-enhanced Raman spectrometry showed that, in spite of a drop of the surface-enhanced Raman spectroscopy (SERS) signal after the titania spacer deposition, the Raman signal can be observed with spacers up to 7 nm in thickness. Denser nanoisland films show slower decay of the SERS signal with the increase in spacer thickness. PACS 78.67.Sc (nanoaggregates; nanocomposites); 81.16.Dn (self-assembly); 74.25.nd (Raman and optical spectroscopy) PMID:25170333

  9. The prevalence of vitamin A deficiency in 1994 on an atoll of the Marshall Islands and its relationship to locally grown food.

    PubMed

    Dickson, J; Hunt, D D

    2001-03-01

    In an area of the world not previously studied for the presence of nutritional deficiencies, this study conducted in 1994, examined the prevalence of Vitamin A deficiency on a representative atoll of the Marshall Islands. All children ages three through ten living on Mili atoll were surveyed. The study was conducted house-to-house with all 38 subjects on the atoll voluntarily enrolling in the study. Vitamin A status was assessed by conjunctival impression cytology with transfer ([CT), clinical ophthalmic signs, and nutritional survey in all children ages three through ten living on Mili atoll, Republic of the Marshall Islands. Forty-seven percent had xerophthannia (5% with XN, 39% with XN + XIA, and 3% with XN + XIB). More than three-quarters (78%) were ICT abnormal, indicating 31% of the population had mild sub-clinical vitamin A deficiency. Eighty-six percent of the children had not received the U.S. recommended daily allowance of vitamin A in the previous week. Oiven the World Health Organization's published guidelines that anything greater than a 1% prevalence, Vitamin A deficiency on Mili atoll may be classified as a significant public health problem.

  10. The prevalence of vitamin A deficiency in 1994 on an atoll of the Marshall Islands and its relationship to locally grown food.

    PubMed

    Dickson, J; Hunt, D D

    2001-03-01

    In an area of the world not previously studied for the presence of nutritional deficiencies, this study conducted in 1994, examined the prevalence of Vitamin A deficiency on a representative atoll of the Marshall Islands. All children ages three through ten living on Mili atoll were surveyed. The study was conducted house-to-house with all 38 subjects on the atoll voluntarily enrolling in the study. Vitamin A status was assessed by conjunctival impression cytology with transfer ([CT), clinical ophthalmic signs, and nutritional survey in all children ages three through ten living on Mili atoll, Republic of the Marshall Islands. Forty-seven percent had xerophthannia (5% with XN, 39% with XN + XIA, and 3% with XN + XIB). More than three-quarters (78%) were ICT abnormal, indicating 31% of the population had mild sub-clinical vitamin A deficiency. Eighty-six percent of the children had not received the U.S. recommended daily allowance of vitamin A in the previous week. Oiven the World Health Organization's published guidelines that anything greater than a 1% prevalence, Vitamin A deficiency on Mili atoll may be classified as a significant public health problem. PMID:12017837

  11. Kinetic aspects of the silver ion release from antimicrobial polyamide/silver nanocomposites

    NASA Astrophysics Data System (ADS)

    Damm, C.; Münstedt, H.

    2008-06-01

    Spherical silver nanoparticles were grown in situ in different polyamides by a thermal reduction of silver acetate during melt processing of the polymers. Most of the particles have a diameter of about 20 nm. The absolute amount as well as the kinetics of the silver ion release from the various polyamide/silver nanocomposites differ strongly, although the filler content in all materials is the same (1.5 wt. %) and the morphologies of the silver particles are not very different. One result of the investigations was that the absolute amount of the long-term silver ion release increases exponentially with the maximum water absorption of the polymers used as matrix materials, because silver ions are formed from elemental silver particles in the presence of water, only. Moreover, it was also found that the long-term silver ion release increases with a growing diffusion coefficient of water in the polymer. The water absorption properties of the polymers govern the kinetics of the silver ion release, too: for strong hydrophilic polyamides like PA6 or PA6.6, which are plasticized by water, the silver ion release is a zero-order process. For nanocomposites with less hydrophilic polyamides like a cycloaliphatic polyamide or a P12 modified with polytetrahydrofurane (PA12-poly-THF), the silver ion release is governed by diffusion. As expected from the efficacy of the silver ion release, PA6, PA6.6, PA12 and PA12 modified with polytetrahydrofurane and a cycloaliphatic polyamide filled with 1.5 wt. % of silver nanoparticles are active against Escherichia coli. But, only nanocomposites with PA6, PA6.6 and P12-poly-THF as matrix materials are suitable as long-term biocidal materials.

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

    PubMed

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

    2014-10-28

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

  13. Bioaccumulation and toxicity of silver compounds: A review

    SciTech Connect

    Ratte, H.T.

    1999-01-01

    A review of the literature revealed that bioaccumulation of silver in soil is rather low, even if the soil is amended with silver-containing sewage sludge. Plants grown on tailings of silver mines were found to have silver primarily in the root systems. In marine and freshwater systems, the highest reported bioconcentration factors (BCFs) were observed in algae, probably because of adsorption of the dissolved silver to the cell surface. In herbivorous organisms, the BCF was lower by about two orders of magnitude. Low amounts of silver were assimilated from food with no substantial biomagnification. In carnivores (e.g., fish), the BCF was also lower by one order of magnitude with no indication of biomagnification. Toxicity of silver occurs mainly in the aqueous phase and depends on the concentration of active, free Ag{sup +} ions. Accordingly, many processes and water characteristics reduce silver toxicity by stopping the formation of free Ag{sup +}, binding Ag{sup +}, or preventing binding of Ag{sup +} to the reactive surfaces of organisms. The solubility of a silver compound, and the presence of complexing agents dissolved organic carbon, and competing ions are important. In soil, sewage sludge, and sediment, in which silver sulfide predominates, the toxicity of silver, even at high total concentrations, is very low. The highly soluble silver thiosulfate complex has low toxicity, which can be attributed to the silver complexed by thiosulfate. Silver nitrate is one of the most toxic silver compounds. The toxic potential of silver chloride complexes in seawater is and will be an important issue for investigation. Aquatic chronic tests, long-term tests, and tests including sensitive life stages show lower toxicity thresholds. The organisms viewed as most sensitive to silver are small aquatic invertebrates, particularly embryonic and larval stages.

  14. Silver cyanide

    Integrated Risk Information System (IRIS)

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

  15. In situ Oxidation of Ultrathin Silver Films on Ni(111)

    SciTech Connect

    A Meyer; I Flege; S Senanayake; B Kaemena; R Rettew; F Alamgir; J Falta

    2011-12-31

    Oxidation of silver films of one- and two-monolayer thicknesses on the Ni(111) surface was investigated by low-energy electron microscopy at temperatures of 500 and 600 K. Additionally, intensity-voltage curves were measured in situ during oxidation to reveal the local film structure on a nanometer scale. At both temperatures, we find that exposure to molecular oxygen leads to the destabilization of the Ag film with subsequent relocation of the silver atoms to small few-layer-thick silver patches and concurrent evolution of NiO(111) regions. Subsequent exposure of the oxidized surface to ethylene initiates the transformation of bilayer islands back into monolayer islands, demonstrating at least partial reversibility of the silver relocation process at 600 K.

  16. The truth about silver.

    PubMed

    Ovington, Liza G

    2004-09-01

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

  17. Aggregation-based growth of silver nanowires at room temperature

    NASA Astrophysics Data System (ADS)

    Sun, Lanlan; Wang, Li; Song, Yonghai; Guo, Cunlan; Sun, Yujing; Peng, Chongyang; Liu, Zhelin; Li, Zhuang

    2008-02-01

    We describe an aggregation-based growth mechanism for formation of silver nanowires at room temperature. It is found that the pH of solution and the concentration of L-cysteine capping molecules have an important effect on the formation and growth of nanowires. Characterization by atomic force microscopy (AFM) and UV-vis spectroscopy recorded as time clearly shows that the silver nanowires are grown at the expense of nanoparticles.

  18. A possible oriented attachment growth mechanism for silver nanowire formation

    SciTech Connect

    Murph, Simona E. Hunyadi; Murphy, Catherine J.; Leach, Austin; Gall, Kenneth

    2015-04-06

    Electron microscopy studies suggest that silver nanowires prepared by an approach reported earlier by us (Caswell, K. K., Bender, C. M., Murphy, C. J. Nano Lett.,2003, 3, 667–669) form through a coarsening process via an oriented attachment mechanism. Initially, silver nucleation centers were produced by chemical reduction of silver ions in boiling water, with sodium citrate and sodium hydroxide as additives in solution. These nucleation centers, with a twinned crystallographic orientation, ultimately merge into fully grown silver nanowires. This is a completely different mechanism from the seed-mediated growth approach, which has also been used to produce silver nanowires. Furthermore, companion molecular dynamics performed with the embedded atom method are in agreement with our experimental data.

  19. A possible oriented attachment growth mechanism for silver nanowire formation

    DOE PAGESBeta

    Murph, Simona E. Hunyadi; Murphy, Catherine J.; Leach, Austin; Gall, Kenneth

    2015-04-06

    Electron microscopy studies suggest that silver nanowires prepared by an approach reported earlier by us (Caswell, K. K., Bender, C. M., Murphy, C. J. Nano Lett.,2003, 3, 667–669) form through a coarsening process via an oriented attachment mechanism. Initially, silver nucleation centers were produced by chemical reduction of silver ions in boiling water, with sodium citrate and sodium hydroxide as additives in solution. These nucleation centers, with a twinned crystallographic orientation, ultimately merge into fully grown silver nanowires. This is a completely different mechanism from the seed-mediated growth approach, which has also been used to produce silver nanowires. Furthermore, companionmore » molecular dynamics performed with the embedded atom method are in agreement with our experimental data.« less

  20. Incorporation Of Nanocrystalline Silver on Carbon Nanotubes by Electrodeposition Technique

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Pal, A. K.

    2008-10-01

    Nanocrystalline silver incorporated carbon nanotubes were grown on Si (001) substrate from an electrolytic bath containing acetonitrile (1% v/v) and water with appropriate amount of silver acetate at an applied d.c. potential ˜20V. The films were characterized by measuring their microstructural properties, FTIR and Raman studies. HRTEM image indicated that the diameter of the nanotubes as ˜5 nm and the d spacing as ˜0.34 nm for (002) plane of CNT. With the addition of nanocrystalline silver, the intensity of G-band decreases while the D-band located ˜1352 cm-1 becomes sharper.

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

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

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

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

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-01

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

  3. Canary Islands

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This easterly looking view shows the seven major volcanic islands of the Canary Island chain (28.0N, 16.5W) and offers a unique view of the islands that have become a frequent vacation spot for Europeans. The northwest coastline of Africa, (Morocco and Western Sahara), is visible in the background. Frequently, these islands create an impact on local weather (cloud formations) and ocean currents (island wakes) as seen in this photo.

  4. Genetics Home Reference: Silver syndrome

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions Silver syndrome Silver syndrome Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Silver syndrome belongs to a group of genetic disorders ...

  5. A Silver Opportunity.

    ERIC Educational Resources Information Center

    Desser, Debra M.

    1996-01-01

    Presents an assignment that involves forming student companies to determine and defend cost estimates for producing a silver Oscar statuette. Includes an assessment rubric for cooperative effort. (JRH)

  6. Dosimetry using silver salts

    DOEpatents

    Warner, Benjamin P.

    2003-06-24

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

  7. Bioconcentration factors (BCF) of silver in wild Agaricus campestris

    SciTech Connect

    Falandysz, J.; Danisiewicz, D.

    1995-07-01

    Silver is an element naturally occurring in small concentrations in different environmental sites. However, many anthropogenic sources of silver led to contamination of this element in soil surfaces, pastures, and coastal marine areas in different parts of the world. Estimates are that 40% of the 1.15x10{sup 4}t of silver produced annually worldwide, will escape into the environment. Due to municipal waste discharge and/or industrial effluents with high silver concentrations, 100 x above the background level have been reported in invertebrate species from polluted marine areas. The meta-stabile radioisotope, {sup 110m}Ag, is a main component of the liquid effluents from nuclear facilities under normal operating conditions. The presence of {sup 111}Ag and {sup 110m}Ag also has been widely found throughout Europe in the 1986 Chernobyl fallout. Silver ions are environmentally harmful. High toxic effects have been observed at low concentrations, especially in aquatic species. Species of lower fungi as well as the mushroom Agaricus bisporus are know to bioaccumulate high concentrations of silver when grown on an artificially enriched substrate. This study looks at the relationship between the silver content of soil and bioconcentration potential of wild Agaricus campestris from sites under different use and with different concentrations of heavy metals. 28 refs., 2 figs., 2 tabs.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  9. The Silver Bullet Syndrome.

    ERIC Educational Resources Information Center

    Dehne, George C.

    1995-01-01

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

  10. Photochemical Synthesis of Silver Nanodecahedrons and Related Nanostructures for Plasmonic Field Enhancement Applications

    NASA Astrophysics Data System (ADS)

    Lu, Haifei

    excitation. These silver NDs acting as seeds can be re-grown into larger silver NDs with LSPR ranging from 490 nm to 590 nm, upon receiving LED irradiation with emission close to the LSPR of silver ND seeds, which are suspended in a precursor solution containing small silver nanoparticles. With the aid of centrifugation, silver NDs with high purity can be obtained. Furthermore, silver ND with a broad tuning range (LSPR 490 ~ 660 nm) can be synthesized from these seeds using irradiation from a 500 nm LED. Second, the optical properties of silver NDs and their SERS application for sensitive molecular detection are presented. Raman signal obtained from silver NDs show remarkable advantage over noble nanoparticles of other shaped, thus revealing their strong localized field enhancement. Experimental results demonstrate that average enhancement factor from individual silver ND may be as high as 106. In order to explore their application for biosensing and bioimaging, stable silica coated SERS tags based on silver ND producing high Raman intensity have been studied. Our experiment results indicate that 10-8 M 4-MBA in solution can be detected by silver NDs modified silicon chip through SERS. Simulation result on the geometry of silver ND/silica spacer/gold film/substrate shows that the Raman sensitivity of the NDs modified chip can be further improved with the insertion of a dielectric/conductor film between them. Finally, we present a photochemical method for the preparation of silver nanostructures preparation with the use of 633 nm laser. Silver nanostructures composed of silver nanoplates could be grown from small silver nanoparticles deposited on a glass substrate. The periodicity of the silver nanostructures is several micrometers, revealing that this photochemical method has the potential for "writing" silver pattern on a solid substrate. Raman spectroscopy has also been explored for real-time monitoring of silver nanostructure growth and SERS hotspots formation.

  11. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, George A.

    1986-01-01

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

  12. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, G.A.

    1985-03-05

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

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

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

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

  14. Mineral commodity profiles: Silver

    USGS Publications Warehouse

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

    2005-01-01

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

  15. Dendrochronology of strain-relaxed islands.

    PubMed

    Merdzhanova, T; Kiravittaya, S; Rastelli, A; Stoffel, M; Denker, U; Schmidt, O G

    2006-06-01

    We report on the observation and study of tree-ring structures below dislocated SiGe islands (superdomes) grown on Si(001) substrates. Analogous to the study of tree rings (dendrochronology), these footprints enable us to gain unambiguous information on the growth and evolution of superdomes and their neighboring islands. The temperature dependence of the critical volume for dislocation introduction is measured and related to the composition of the islands. We show clearly that island coalescence is the dominant pathway towards dislocation nucleation at low temperatures, while at higher temperatures anomalous coarsening is effective and leads to the formation of a depletion region around superdomes.

  16. Dendrochronology of strain-relaxed islands.

    PubMed

    Merdzhanova, T; Kiravittaya, S; Rastelli, A; Stoffel, M; Denker, U; Schmidt, O G

    2006-06-01

    We report on the observation and study of tree-ring structures below dislocated SiGe islands (superdomes) grown on Si(001) substrates. Analogous to the study of tree rings (dendrochronology), these footprints enable us to gain unambiguous information on the growth and evolution of superdomes and their neighboring islands. The temperature dependence of the critical volume for dislocation introduction is measured and related to the composition of the islands. We show clearly that island coalescence is the dominant pathway towards dislocation nucleation at low temperatures, while at higher temperatures anomalous coarsening is effective and leads to the formation of a depletion region around superdomes. PMID:16803325

  17. Dendrochronology of Strain-Relaxed Islands

    SciTech Connect

    Merdzhanova, T.; Kiravittaya, S.; Rastelli, A.; Stoffel, M.; Denker, U.; Schmidt, O.G.

    2006-06-09

    We report on the observation and study of tree-ring structures below dislocated SiGe islands (superdomes) grown on Si(001) substrates. Analogous to the study of tree rings (dendrochronology), these footprints enable us to gain unambiguous information on the growth and evolution of superdomes and their neighboring islands. The temperature dependence of the critical volume for dislocation introduction is measured and related to the composition of the islands. We show clearly that island coalescence is the dominant pathway towards dislocation nucleation at low temperatures, while at higher temperatures anomalous coarsening is effective and leads to the formation of a depletion region around superdomes.

  18. Galapagos Islands

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color image of the Galapagos Islands was acquired on March 12, 2002, by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. The Galapagos Islands, which are part of Ecuador, sit in the Pacific Ocean about 1000 km (620 miles) west of South America. As the three craters on the largest island (Isabela Island) suggest, the archipelago was created by volcanic eruptions, which took place millions of years ago. Unlike most remote islands in the Pacific, the Galapagos have gone relatively untouched by humans over the past few millennia. As a result, many unique species have continued to thrive on the islands. Over 95 percent of the islands' reptile species and nearly three quarters of its land bird species cannot be found anywhere else in the world. Two of the more well known are the Galapagos giant tortoise and marine iguanas. The unhindered evolutionary development of the islands' species inspired Charles Darwin to begin The Origin of Species eight years after his visit there. To preserve the unique wildlife on the islands, the Ecuadorian government made the entire archipelago a national park in 1959. Each year roughly 60,000 tourists visit these islands to experience what Darwin did over a century and a half ago. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  19. Surfactantless synthesis of silver nanoplates and their application in SERS.

    SciTech Connect

    Sun, Y.; Wiederrecht, G.; Center for Nanoscale Materials

    2007-11-01

    Silver nanoplates with thicknesses of 50-70 nm and edge lengths ranging from 200 nm to 1 mm are grown on semiconductor waters at room temperature through a simple galvanic reaction between an aqueous solution of silver nitrate and n-type GaAs. The as-grown silver structures have chemically clean surfaces because no surfactant or coordinating molecules are involved in the synthesis. Electron microscopy characterization indicates that each silver plate has rough surfaces and a half-moon morphology with one straight edge and on arclike edge. Systematic studies on varying reaction conditions reveal that the oxide (i.e., Ga{sub 2}O{sub 3} and As{sub 2}O{sub 3}) layers of GaAs, generated in situ in the reactions, play an important role in assisting the growth of anisotropic nanoplates. The cleanliness of the surfaces of the silver nanoplates is beneficial to attachment of interesting molecules on their surfaces for various applications, such as plasmonic-enhanced photophysical and photochemical processes and surface-enhanced spectroscopies.

  20. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    NASA Astrophysics Data System (ADS)

    Ashraf, Sumaira; Chatha, Mariyam Asghar; Ejaz, Wardah; Janjua, Hussnain Ahmed; Hussain, Irshad

    2014-10-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests.

  1. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

    PubMed Central

    2014-01-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests. PMID:25435831

  2. Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity.

    PubMed

    Ashraf, Sumaira; Chatha, Mariyam Asghar; Ejaz, Wardah; Janjua, Hussnain Ahmed; Hussain, Irshad

    2014-01-01

    Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests. PMID:25435831

  3. Synthesis of silver nanoparticles by electron irradiation of silver acetate

    NASA Astrophysics Data System (ADS)

    Li, Yue; Kim, Yong Nam; Lee, Eun Je; Cai, Wei Ping; Cho, Sung Oh

    2006-10-01

    A novel and facile route to synthesize crystalline silver nanoparticles is presented, which is based on electron irradiation technique. Only by irradiating an electron beam onto silver acetate precursor material, silver nanocrystals with the sizes of 15-40 nm were synthesized. The morphology and chemical composition of the irradiated samples were characterized by SEM, TEM, XRD and EELS. The precursor material was decomposed by the energetic electrons and consequently the chemical composition of the material was changed. As the electron fluence was gradually increased, the precursor was converted to silver (I) oxide and finally into silver nanocrystals. Thus, besides silver nanoparticles, silver oxide film can also be synthesized using the electron irradiation technique by controlling the electron fluence. The technique can be useful for mass production of silver nanoparticles and for patterned silver nanoparticle film.

  4. Akpatok Island

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Akpatok Island lies in Ungava Bay in northern Quebec, Canada. Accessible only by air, Akpatok Island rises out of the water as sheer cliffs that soar 500 to 800 feet (150 to 243 m) above the sea surface. The island is an important sanctuary for cliff-nesting seabirds. Numerous ice floes around the island attract walrus and whales, making Akpatok a traditional hunting ground for native Inuit people. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on January 22, 2001. Image provided by the USGS EROS Data Center Satellite Systems Branch

  5. Humidity sensing by nanocomposites of silver in silicate glass ceramics

    NASA Astrophysics Data System (ADS)

    Pal, B. N.; Kundu, T. K.; Banerjee, S.; Chakravorty, D.

    2003-04-01

    Silver nanoparticles of diameters in the range 3.4 to 13.2 nm were grown within a silicate glass ceramics containing barium titanate phase. The glass ceramics were filled with silver particles by subjecting the former to a Na+-Ag+ ion exchange process followed by a reduction treatment in hydrogen. Silver particles were formed at the interfaces of the silicate glass and the barium titanate phases, respectively. The silver particle sizes could be varied by controlling the fractal structure of the crystalline phase by prior heat treatment. Electrical resistivity measurements were carried out on cold-pressed specimens of nanocomposite powders prepared as just stated. A five order of magnitude resistivity change was recorded in the case of nanocomposite specimen with a silver particle diameter of 10.1 nm in the relative humidity range of 25% to 85%. The resistivity of the nanocomposites was found to be controlled by a variable range hopping conduction. It is believed that the silver nanoparticles provide sites where physisorption of water molecules takes place which increases the number of localized states near the Fermi level.

  6. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  7. Give silver a shine.

    PubMed

    Fromm, Katharina M

    2011-02-01

    Katharina M. Fromm explains how, as well as catalysis and jewellery, silver serves a myriad of medicinal applications--some of which are even behind poetic traditions such as throwing coins in wishing wells. PMID:21258393

  8. Electrochemical behavior of silver sulfide

    SciTech Connect

    Drouven, B.U.E.

    1982-01-01

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

  9. Island Hopping

    ERIC Educational Resources Information Center

    Bennett, Gayle

    2009-01-01

    At some institutions, it may feel as though faculty live on one island and advancement staff on another. The islands form part of an archipelago, and they exchange ambassadors and send emissaries occasionally, but interactions are limited. It may even seem as though the two groups speak different languages, deal in different currencies, and abide…

  10. Anatahan Island

    Atmospheric Science Data Center

    2013-04-19

    ... of the Mariana Islands in 1914 (the first year of World War l) and Germany released the islands to Japan in 1919. Japan received a ... States by the United Nations. The wreckage of a World War II B-29 Superfortress, a four-engine propeller-driven bomber, lies on the north ...

  11. Substrate decomposition in galvanic displacement reaction: Contrast between gold and silver nanoparticle formation

    SciTech Connect

    Ghosh, Tapas; Satpati, Biswarup

    2015-06-24

    We have investigated substrate decomposition during formation of silver and gold nanoparticles in galvanic displacement reaction on germanium surfaces. Silver and gold nanoparticles were synthesized by electroless deposition on sputter coated germanium thin film (∼ 200 nm) grown initially on silicon substrate. The nanoparticles formation and the substrate corrosion were studied using scanning transmission electron microscopy (STEM) and the energy dispersive X-ray (EDX) spectroscopy.

  12. Enhanced water splitting with silver decorated GaN photoelectrode

    NASA Astrophysics Data System (ADS)

    Hou, Y.; Syed, Z. A.; Smith, R.; Athanasiou, M.; Gong, Y.; Yu, X.; Bai, J.; Wang, T.

    2016-07-01

    By means of a cost-effective approach, we demonstrate a GaN-based photoelectrode decorated with self-organized silver nano-islands employed for solar powered hydrogen generation, demonstrating 4 times increase in photocurrent compared with a reference sample without using any silver. Our photoelectrode exhibits a 60% incident photon-to-electron conversion efficiency. The enhanced hydrogen generation is attributed to a significantly increased carrier generation rate as a result of strongly localized electric fields induced by surface plasmon coupling effect. The silver coating also contributes to the good chemical stability of our photoelectrode in a strong alkali electrolyte. This work paves the way for the development of GaN and also InGaN based photoelectrodes with ultra-high solar hydrogen conversion efficiency.

  13. Experimental evidence of direct contact formation for the current transport in silver thick film metallized silicon emitters

    NASA Astrophysics Data System (ADS)

    Cabrera, Enrique; Olibet, Sara; Glatz-Reichenbach, Joachim; Kopecek, Radovan; Reinke, Daniel; Schubert, Gunnar

    2011-12-01

    Great advances have been achieved in the development of silver pastes. The use of smaller silver particles, higher silver content, and, thus, less glass frit allow modern silver pastes to contact high resistive emitters without the necessity of a selective emitter or subsequent plating. To identify the microscopic key reasons behind the improvement of silver paste, it is essential to understand the current transport mechanism from the silicon emitter into the bulk of the silver finger. Two current transport theories predominate: i) The current flows through the Ag crystallites grown into the Si emitter, which are separated by a thin glass layer or possibly in direct contact with the silver finger. ii) The current is transported by means of multistep tunneling into the silver finger across nano-Ag colloids in the glass layer, which are formed at optimal firing conditions; the formation of Ag crystallites into the Si surface is synonymous with over-firing. In this study, we contact Si solar cell emitters with different silver pastes on textured and flat silicon surfaces. A sequential selective silver-glass etching process is employed to expose and isolate the different contact components for current transport. The surface configurations after the etching sequences are observed with scanning electron microscopy. Liquid conductive silver is then applied to each sample and the contact resistivity is measured to determine the dominant microscopic conduction path system. We observe glass-free emitter areas at the tops of the pyramidal-textured Si that lead to the formation of direct contacts between the Ag crystallites grown into the Si emitter and the bulk of the silver finger. We present experimental evidence that the major current flow into the silver finger is through these direct contacts.

  14. The efficacy of silver dressings and antibiotics on MRSA and MSSA isolated from burn patients.

    PubMed

    Percival, Steven L; Thomas, John G; Slone, Will; Linton, Sara; Corum, Linda; Okel, Tyler

    2011-11-01

    In this study our objectives were (1) to investigate whether meticillin-resistant Staphylococcus aureus (MRSA) showed an increased tolerance to silver wound dressings compared with meticillin-sensitive S. aureus (MSSA); and (2) to evaluate the effects of bacterial phenotypic states of MRSA and MSSA, and pH, on the activity of silver wound dressings and two antibiotics, ampicillin and clindamycin. Twenty MRSA strains and 10 MSSA strains isolated from burns patients in South Africa were evaluated for their susceptibility to a silver alginate and a silver carboxymethyl cellulose wound dressing, employing a corrected zone of inhibition assay, conducted on Mueller Hinton agar and a poloxamer-based biofilm model. When exposed to the two silver dressings, all 30 S. aureus strains showed susceptibility. Possible enhanced antimicrobial efficacy of the silver dressings occurred when pH was lowered to 5.5, compared with a pH of 7.0. When all S. aureus were grown in the biofilm phenotypic state and exposed to both silver dressings and antibiotics, enhanced tolerance was noted. Susceptibility to silver was overall higher for MRSA when compared with MSSA. This study showed that the effect of pH and bacterial phenotypic state must be considered when the antimicrobial activity of silver wound dressings is being investigated. It is evident from the data generated that both pH and the bacterial phenotypic state are factors that induce changes that affect both antimicrobial performance and bacterial susceptibility.

  15. Silver nanostructures formation in porous Si/SiO2 matrix

    NASA Astrophysics Data System (ADS)

    Sivakov, Vladimir; Kaniukov, Egor Yu.; Petrov, Alexander V.; Korolik, Olga V.; Mazanik, Alexander V.; Bochmann, Arne; Teichert, Steffen; Hidi, Izabella J.; Schleusener, Alexander; Cialla, Dana; Eugenia Toimil-Molares, Maria; Trautmann, Christina; Popp, Jürgen; Demyanov, Sergey E.

    2014-08-01

    Self-organized silver nanostructures were grown in porous Si/SiO2 matrix fabricated by ion track technology. The different silver nanostructures with shapes like “sunflowers”, “azalea” or “corn” were realized by applying wet-chemical electroless deposition. We show that reproducible self-organized silver “sunflower” like nanostructures provide a high enhanced Raman signal of Nile blue dye molecules. Signal enhancement for a few or even just a single silver “sunflower” is demonstrated by analyzing the surface-enhanced Raman signature of Nile blue dye molecules. According to this, the silver nanostructures can act as efficient surfaces for surface enhanced Raman spectroscopy as well as (bio)-sensor applications.

  16. Concerning the energy levels of silver in Ge-Si alloys

    SciTech Connect

    Tahirov, V. I.; Agamaliev, Z. A.; Sadixova, S. R.; Guliev, A. F.; Gahramanov, N. F.

    2012-03-15

    The emission from impurity states of silver (an element of the IB subgroup) in a Ge-Si alloy, containing 18 at % Si, has been studied. The donor level of silver has been found in crystals doubly doped with gallium and silver, while its first acceptor level has been revealed in crystals doped with only silver. Single crystals were grown by pulling from a melt using a feeding rod. Doping with gallium was performed by introducing this element into the feeding rod, and silver was introduced into the crystals via diffusion. The positions of the donor and first acceptor Ag levels with respect to the top of the valence band were found by analyzing the temperature dependence of the Hall coefficient and the electroneutrality equation for the crystal: 0.06 and 0.29 eV, respectively.

  17. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  18. Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

    PubMed Central

    Merrett, Neil D.

    2014-01-01

    Silver in its ionic form (Ag+), but not the bulk metal (Ag0), is toxic to microbial life forms and has been used for many years in the treatment of wound infections. The prevalence of bacterial resistance to silver is considered low due to the nonspecific nature of its toxicity. However, the recent increased use of silver as an antimicrobial agent for medical, consumer, and industrial products has raised concern that widespread silver resistance may emerge. Pseudomonas aeruginosa is a common pathogen that produces pyocyanin, a redox toxin and a reductant for molecular oxygen and ferric (Fe3+) ions. The objective of this study was to determine whether pyocyanin reduces Ag+ to Ag0, which may contribute to silver resistance due to lower bioavailability of the cation. Using surface plasmon resonance spectroscopy and scanning electron microscopy, pyocyanin was confirmed to be a reductant for Ag+, forming Ag0 nanoparticles and reducing the bioavailability of free Ag+ by >95% within minutes. Similarly, a pyocyanin-producing strain of P. aeruginosa (PA14) reduced Ag+ but not a pyocyanin-deficient (ΔphzM) strain of the bacterium. Challenge of each strain with Ag+ (as AgNO3) gave MICs of 20 and 5 μg/ml for the PA14 and ΔphzM strains, respectively. Removal of pyocyanin from the medium strain PA14 was grown in or its addition to the medium that ΔphzM mutant was grown in gave MICs of 5 and 20 μg/ml, respectively. Clinical isolates demonstrated similar pyocyanin-dependent resistance to Ag+. We conclude that pseudomonal silver resistance exists independently of previously recognized intracellular mechanisms and may be more prevalent than previously considered. PMID:25001302

  19. Devon Island

    Atmospheric Science Data Center

    2013-04-17

    article title:  Mars Researchers Rendezvous on Remote Arctic Island   ... each summer since 1999, researchers from NASA's Haughton-Mars Project and the Mars Society reside at this "polar desert" location to study the geologic and ...

  20. Island of Okinawa, Japan

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The island of Okinawa, (26.5N, 128.0E) largest of the Ryukyu Islands, Japan. The Ryukyu island group lies south of the main home islands of Japan in an arc towards the Chinese island Republic of Taiwan. As is typical throughout the Japanese home islands, intense urban development can be observed all over the island in this near vertical view.

  1. Increase of island density via formation of secondary ordered islands on pit-patterned Si (001) substrates

    SciTech Connect

    Zhong, Z.; Schmidt, O.G.; Bauer, G.

    2005-09-26

    Site-controlled groups of Ge islands are grown on pit-patterned Si (001) substrates. By varying the deposited amount of Ge, we find that the growth starts with the formation of a single island at the pit bottom and then proceeds to the formation of a highly symmetric Ge island group around the pit top. A bimodal size distribution of dome-shaped islands at the bottom and at the top corners of the pits is observed. A growth mechanism is proposed to qualitatively explain these phenomena. Our experiments help to promote a further understanding of Ge island growth on patterned substrates.

  2. Electrochemical deposition of silver crystals aboard Skylab 4

    NASA Technical Reports Server (NTRS)

    Grodzka, P. G.; Facemire, B. R.; Johnston, M. H.; Gates, D. W.

    1976-01-01

    Silver crystals were grown aboard Skylab 4 by an electro-chemical reaction and subsequently returned to earth for comparison with crystals grown at 1- and 5-g. Both the Skylab and earth-grown crystals show a variety of structures. Certain tendencies in structure dependency on gravity level, however, can be discerned. In addition, downward growing dendrite streamers; upward growing chunky crystal streamers; growth along an air/liquid interface; and ribbon, film, and fiber crystal habits were observed in experiments conducted on the ground with solutions of varying concentrations. It was also observed that the crystal structures of space and ground electro-deposited silver crystals were very similar to the structures of germanium selenide and germanium telluride crystals grown in space and on the ground by a vapor transport technique. Consideration of the data leads to the conclusions that: (1) the rate of electrochemical displacement of silver ions from a 5 percent aqueous solution by copper is predominantly diffussion controlled in space and kinetically controlled in 1- and higher-g because of augmentation of mass transport by convection; (2) downward and upward crystal streamers are the result of gravity-driven convection, the flow patterns of which can be delineated. Lateral growths along an air/liquid interface are the result of surface-tension-driven convection, the pattern of which also can be delineated; (3) electrolysis in space or low-g environments can produce either dendritic crystals with more perfect microcrystalline structures or massive, single crystals with fewer defects than those grown on ground or at higher g-levels. Ribbons or films of space-grown silicon crystals would find a ready market for electronic substrate and photocell applications. Space-grown dendritic, metal crystals present the possibility of unique catalysts. Large perfect crystals of various materials are desired for a number of electronic and optical applications; and (4) vapor

  3. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are about "strange…

  4. Potassium silver cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for potassium silver cyanide is inclu

  5. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  6. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  7. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  8. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  9. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  10. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  11. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  12. Siberian Islands

    Atmospheric Science Data Center

    2013-04-16

    ... Distinguishing Clouds from Ice over the East Siberian Sea, Russia     View Larger Image ... ocean are visible. The East Siberian Sea is part of the Arctic Ocean and is ice-covered most of the year. The New Siberian Islands are ...

  13. Hawaiian Islands

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This Multiangle Imaging Spectro-Radiometer (MISR) image of five Hawaiian Islands was acquired by the instrument's vertical- viewing (nadir) camera on June 3, 2000. The image shows the islands of Oahu, Molokai, Lanai, Maui, and Kahoolawe. The prevailing Pacific trade winds bring higher levels of rainfall to the eastern slopes of the islands, leading to a greater abundance of vegetation on the windward coasts. The small change in observation angle across the nadir camera's field-of- view causes the right-hand portion of the image to be more affected by Sun glint, making the ocean surface appear brighter. Oahu is the westernmost of the islands seen in this image. Waikiki Beach and the city of Honolulu are located on the southern shore, to the west of Diamond Head caldera. MISR is one of several Earth-observing instruments on the Terra satellite, launched in December 1999. The Terra spacecraft, the flagship of a fleet of satellites dedicated to understanding our global environment, is part of NASA's Earth Sciences Enterprise, a long-term research program dedicated to understanding how human-induced and natural changes affect our world. Image courtesy NASA/GSFC/JPL, MISR Team

  14. Hydrometallurgical recovery of silver from waste silver oxide button cells

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P.

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000 °C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600 V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated.

  15. Genetics Home Reference: Russell-Silver syndrome

    MedlinePlus

    ... Genetics Home Health Conditions Russell-Silver syndrome Russell-Silver syndrome Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Russell-Silver syndrome is a growth disorder characterized by slow ...

  16. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  17. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

  18. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  19. Graphic Grown Up

    ERIC Educational Resources Information Center

    Kim, Ann

    2009-01-01

    It's no secret that children and YAs are clued in to graphic novels (GNs) and that comics-loving adults are positively giddy that this format is getting the recognition it deserves. Still, there is a whole swath of library card-carrying grown-up readers out there with no idea where to start. Splashy movies such as "300" and "Spider-Man" and their…

  20. Streamlined Island

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-514, 15 October 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a streamlined island in Marte Vallis, a large outflow channel system that crosses the 180oW meridian between the Elysium and Amazonis regions of Mars. The flow patterns on the floor of Marte Vallis might be the remains of lava flows or mud flows. Marte is the Spanish word for Mars. Most of the largest valleys on the red planet are named for 'Mars' in various languages. This island is located near 21.8oN, 175.3oW. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the lower left.

  1. Assessing Pistia stratiotes for phytoremediation of silver nanoparticles and Ag(I) contaminated waters.

    PubMed

    Hanks, Nicole A; Caruso, Joseph A; Zhang, Peng

    2015-12-01

    To study the phytoremediation capabilities of Pistia stratiotes in silver nanoparticle (AgNP) and silver ion contaminated wastewaters, individual plants were grown in media spiked with different concentrations of silver nanoparticle and silver ions (0.02, 0.2, and 2 mg L(-1)). Control experiments were carried out at the same time for comparison purposes. Visual changes in the plants were also recorded periodically during each experiment. Total silver concentrations were monitored in the media before, during, and at the termination of the experiments. In addition, analysis of total silver in plant root and leaf samples after termination were carried out to determine the effect of the different media concentrations. The results showed that P. stratiotes can survive in AgNP and ions under 0.02 mg L(-1) and contaminants are retained within the plant. The use of P. stratiotes as a phytoremediator shows potential in removing heavy metal nanoparticles and is competitive in its removal of the ion counterpart. Even higher concentrations of silver, regardless of form, can be reduced to lower levels than the World Health Organization's maximum contamination limit.

  2. Effect of different carbon sources on morphology and silver accumulation in Cochliobolus lunatus.

    PubMed

    Salunkhe, Rahul B; Borase, Hemant P; Patil, Chandrashekhar D; Patil, Sucheta N; Patil, Satish V

    2015-12-01

    The morphology of filamentous fungi plays very important role in uptake of metabolites and enzyme production. A filamentous fungus may be fibrous, hyphae, pellets, clumps, etc. Cochliobolus lunatus is a fungus which has previously been reported for silver accumulation and nanoparticles formation. The present study investigated the role of various carbon sources on morphology, biochemical profile, silver accumulation, and biosynthesis of silver nanoparticles by fungal strain C. lunatus. In this investigation, effect of different carbon sources was studied on morphology of C. lunatus and its silver accumulating ability. As a result of different carbon sources like carboxymethyl cellulose (CMC), pectin, starch, agar, sucrose, and mannitol, the organism showed three kinds of morphologies like homogenous smooth branched clumps, tough short fibrous filaments, and tough pellets, as well as silver accumulating ability. Atomic absorption spectroscopy (AAS) studies showed maximum uptake of Ag(+): 87.44 ± 0.23 and 82.57 ± 0.19 % in pectin- and CMC-grown biomass, respectively. The crystalline nature of silver nanoparticles (AgNPs) was confirmed by X-ray diffraction studies. Transmission electron microscopy (TEM) micrographs of silver nanoparticles confirmed size ranging from 5 to 38 nm.

  3. Electronic properties of the silver-silver chloride cluster interface.

    PubMed

    Glaus, Stephan; Calzaferri, Gion; Hoffmann, Roald

    2002-04-15

    The objective of this study was to gain insight into the electronic structure of silver-silver chloride cluster composites and especially into the metal-semiconductor interface. For this purpose a theoretical study of (AgCl)(n) (n=4, 32, 108, 192, and 256), of Ag(m) (m=1-9, 30, 115, 276, and 409), and of the cluster composites Ag(115)-(AgCl)(192) and Ag(409)-(AgCl)(192) has been carried out. Density of levels (DOL), local density of levels (l-DOL), and projection of surface states, as well as projection of properties of individual atoms or groups of atoms obtained in molecular orbital calculations, are shown to be powerful tools for gaining deep insight into the properties of these large systems. The Ag(115)-(AgCl)(192) aggregate, consisting of a cubic Ag(115) cluster without corner atoms on top of a cubic (AgCl)(192) cluster, was found to be remarkably stable with a cluster-to-cluster distance of about 280 pm, and a geometry in which the number of bonding interactions between the silver atoms of Ag(115) and the chloride ions of (AgCl)(192) is at its maximum. A sharp jump in charge distribution occurs at the Ag(115)-(AgCl)(192) composite interface. The first AgCl slab picks up negative charge from the two adjacent silver slabs, so that in total the silver cluster is positively charged. In addition, the core of the silver cluster is positively charged with respect to its outermost layer. The main reason for the charge transfer from the silver cluster to the silver chloride is the newly formed MIGS (metal induced gap states) in the energy-gap range of the silver chloride and the MIdS (metal induced d states) in the d-orbital region. Their wave functions mix with orbitals of the silver cluster and with both the orbitals of the silver and the chloride ions of the silver chloride. The MIGS and the MIdS are of a quite localized nature. In them, nearest neighbor interactions dominate, with the exception of close-lying silver chloride surface states-which mix in to a large

  4. Carbon Nanotube Interconnects Realized through Functionalization and Sintered Silver Attachment.

    PubMed

    Gopee, V; Thomas, O; Hunt, C; Stolojan, V; Allam, J; Silva, S R P

    2016-03-01

    Carbon nanotubes (CNTs) in the form of interconnects have many potential applications, and their ability to perform at high temperatures gives them a unique capability. We show the development of a novel transfer process using CNTs and sintered silver that offers a unique high-temperature, high-conductivity, and potentially flexible interconnect solution. Arrays of vertically aligned multiwalled carbon nanotubes of approximately 200 μm in length were grown on silicon substrates, using low-temperature photothermal chemical vapor deposition. Oxygen plasma treatment was used to introduce defects, in the form of hydroxyl, carbonyl, and carboxyl groups, on the walls of the carbon nanotubes so that they could bond to palladium (Pd). Nanoparticle silver was then used to bind the Pd-coated multiwalled CNTs to a copper substrate. The silver-CNT-silver interconnects were found to be ohmic conductors, with resistivity of 6.2 × 10(-4) Ωm; the interconnects were heated to temperatures exceeding 300 °C (where common solders fail) and were found to maintain their electrical performance. PMID:26835786

  5. Classifying Pacific islands

    NASA Astrophysics Data System (ADS)

    Nunn, Patrick D.; Kumar, Lalit; Eliot, Ian; McLean, Roger F.

    2016-12-01

    An earth-science-based classification of islands within the Pacific Basin resulted from the preparation of a database describing the location, area, and type of 1779 islands, where island type is determined as a function of the prevailing lithology and maximum elevation of each island, with an island defined as a discrete landmass composed of a contiguous land area ≥1 ha (0.01 km2) above mean high-water level. Reefs lacking islands and short-lived (<20 years) transient islands are not included. The principal aim of the classification is to assess the spatial diversity of the geologic and geomorphic attributes of Pacific islands. It is intended to be valid at a regional scale and based on two attributes: five types of lithology (volcanic, limestone, composite, continental, surficial) and a distinction between high and low islands. These attributes yielded eight island types: volcanic high and low islands; limestone high and low islands; composite high and low islands; reef (including all unconsolidated) islands; and continental islands. Most common are reef islands (36 %) and volcanic high islands (31 %), whereas the least common are composite low islands (1 %). Continental islands, 18 of the 1779 islands examined, are not included in maps showing the distribution of island attributes and types. Rationale for the spatial distributions of the various island attributes is drawn from the available literature and canvassed in the text. With exception of the few continental islands, the distribution of island types is broadly interpretable from the proximity of island-forming processes. It is anticipated the classification will become the basis for more focused investigation of spatial variability of the climate and ocean setting as well as the biological attributes of Pacific islands. It may also be used in spatial assessments of second-order phenomena associated with the islands, such as their vulnerability to various disasters, coastal erosion, or ocean pollution as

  6. Island of Hawaii, Hawaiian Archipelago

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This single photo covers almost all of the big island of Hawaii (19.5N, 155.5E) in the Hawaiian Archipelago. The active Kilauea Volcano and lava flow is under clouds and hardly visible at the lower right edge but the Mauna Loa volcano crater and its older lava flow is at the bottom center. The Kona Coast, that produces the only coffee grown in the United States, is to the left. Mauna Kea is the extinct volcano and lava flow in the right center.

  7. Silver stain for electron microscopy

    NASA Technical Reports Server (NTRS)

    Corbett, R. L.

    1972-01-01

    Ammoniacal silver stain used for light microscopy was adapted advantageously for use with very thin biological sections required for electron microscopy. Silver stain can be performed in short time, has more contrast, and is especially useful for low power electron microscopy.

  8. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  9. Silver against Pseudomonas aeruginosa biofilms.

    PubMed

    Bjarnsholt, Thomas; Kirketerp-Møller, Klaus; Kristiansen, Søren; Phipps, Richard; Nielsen, Anne Kirstine; Jensen, Peter Østrup; Høiby, Niels; Givskov, Michael

    2007-08-01

    Silver has been recognized for its antimicrobial properties for centuries. Most studies on the antibacterial efficacy of silver, with particular emphasis on wound healing, have been performed on planktonic bacteria. Our recent studies, however, strongly suggest that colonization of wounds involves 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 mug/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 mug/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 primarily colonized either by biofilm-forming or planktonic bacteria.

  10. Growth of silver nanowires on GaAs wafers.

    PubMed

    Sun, Yugang

    2011-05-01

    Silver (Ag) nanowires with chemically clean surfaces have been directly grown on semi-insulating gallium arsenide (GaAs) wafers through a simple solution/solid interfacial reaction (SSIR) between the GaAs wafers themselves and aqueous solutions of silver nitrate (AgNO(3)) at room temperature. The success in synthesis of Ag nanowires mainly benefits from the low concentration of surface electrons in the semi-insulating GaAs wafers that can lead to the formation of a low-density of nuclei that facilitate their anisotropic growth into nanowires. The resulting Ag nanowires exhibit rough surfaces and reasonably good electric conductivity. These characteristics are beneficial to sensing applications based on single-nanowire surface-enhanced Raman scattering (SERS) and possible surface-adsorption-induced conductivity variation.

  11. Solomon Islands.

    PubMed

    1988-06-01

    The Solomon Islands, which form an archipelago in the Southwest Pacific about 1900 km northeast of Australia, are described. Included are brief descriptions about such points as geography, people, history, type of government, political conditions, economy, and foreign relations. In 1987 the population was 301,180 (49% under age 14); the annual growth rate was 3.67%. The infant mortality rate is 46/1000; the life expectancy, 54 years. Health conditions in the Solomons generally are adequate, and the country does not suffer from serious endemic diseases other than malaria, in both the vivax and falsiparum strains. Hospitals and pharmacies are limited to population centers and missions. PMID:12177986

  12. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  13. Island of Kauai, Hawaii

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The island of Kauai, of the Hawaiian Island archipelago (22.0N, 159.5W) peeks out from scattered cloud cover. The island's volcanic origins are easily seen by the distinctive lava flow topography and lush vegetation.

  14. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis. PMID:26977895

  15. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis.

  16. Retiring the Silver Bullet

    SciTech Connect

    Lasure, Linda L.

    2006-01-01

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

  17. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  18. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1997-05-06

    A process is disclosed for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles. 1 fig.

  19. Studies of n-butane conversion over silica-supported platinum, platinum-silver and platinum-copper catalysts

    SciTech Connect

    Gu, Junhua.

    1992-06-09

    The present work was undertaken to elucidate effect of adding silver and copper to silica-supported platinum catalyst on the activity and selectivity in the n-butane reactions. At the conditions of this study n-butane underwent both hydrogenolysis and structural isomerization. The catalytic activity and selectivities between hydrogenolysis and isomerization and within hydrogenolysis were measured at temperature varying from 330 C to 370 C. For platinum-silver catalysts, at lower temperatures studied the catalytic activity per surface platinum atom (turnover frequency) remained constant at lower silver content (between 0 at. % and 30 at. %) and decreased with further increased silver loading, suggesting that low- index planes could be dominant in the hydrogenolysis of n-butane. Moreover, increasing silver content resulted in an enhancement of the selectivity of isomerization products relative to hydrogenolysis products. At the higher temperature studied, no suppression in catalytic activity was observed. It is postulated that surface structure could change due to the mobility of surface silver atoms, leading to surface silver atoms forming islands or going to the bulk, and leaving large portions of basal planes exposed with active platinum atoms. It is also suggested that the presence of inert silver atoms results in weakening of the H-surface bond. This results in increased mobility of hydrogen atoms on the surface and hence, higher reactivity with other adsorbed species. For platinum copper catalysts, the mixed ensembles could play an active role in the hydrogenolysis of n-butane.

  20. Tenarife Island, Canary Island Archipelago, Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Tenarife Island is one of the most volcanically active of the Canary Island archipelago, Atlantic Ocean, just off the NW coast of Africa, (28.5N, 16.5W). The old central caldera, nearly filled in by successive volcanic activity culminating in two stratocones. From those two peaks, a line of smaller cinder cones extend to the point of the island. Extensive gullies dissect the west side of the island and some forests still remain on the east side.

  1. Silver Complexes of Dihalogen Molecules.

    PubMed

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

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). PMID:27404568

  2. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  3. Island Formation: Constructing a Coral Island

    ERIC Educational Resources Information Center

    Austin, Heather; Edd, Amelia

    2009-01-01

    The process of coral island formation is often difficult for middle school students to comprehend. Coral island formation is a dynamic process, and students should have the opportunity to experience this process in a synergistic context. The authors provide instructional guidelines for constructing a coral island. Students play an interactive role…

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

    PubMed Central

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

    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 (1.5–3.0 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. PMID:23570016

  5. Silver Nafion for Thermogalvanic Applications

    NASA Astrophysics Data System (ADS)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  6. Hawaiian Island Archipelago

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The entire Hawaiian Island Archipelago (21.5N, 158.0W) is seen in this single view. The islands are a favorite international resort and tourist attraction drawing visitors from all over the world to enjoy the tropical climate, year round beaches and lush island flora. Being volcanic in origin, the islands' offer a rugged landscape and on the big island of Hawaii, there is still an occasional volcanic eruption of lava flows and steam vents.

  7. Preliminary flight prototype silver ion monitoring system

    NASA Technical Reports Server (NTRS)

    Brady, J.

    1974-01-01

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

  8. Silver composite cathodes for alkaline secondary batteries

    NASA Astrophysics Data System (ADS)

    Ferrando, William A.

    1989-08-01

    This invention relates to electrochemical cells and more particularly to silver electrodes for electrochemical cells. Accordingly, an object of this invention is to provide a new, lighter weight silver electrode for secondary cells. Another object of this invention is to provide an electrode which requires less silver to operate. A further object of this invention is to provide a silver electrode which uses the silver more efficiently. Yet another object of the invention is to provide an easier, less expensive method of manufacturing silver electrodes for secondary cells.

  9. Phonons as probes in self-organized SiGe islands

    NASA Astrophysics Data System (ADS)

    Groenen, J.; Carles, R.; Christiansen, S.; Albrecht, M.; Dorsch, W.; Strunk, H. P.; Wawra, H.; Wagner, G.

    1997-12-01

    We show how optical phonons can be used as efficient probes in self-organized Si1-xGex islands grown on Si(001). Both the alloy composition and residual strain in the islands were originally determined from the phonon frequencies and Raman intensities. The experimental results are in good agreement with the strain relaxation simulated by means of the finite element method.

  10. X-ray diffraction analysis of LiCu2O2 crystals with additives of silver atoms

    NASA Astrophysics Data System (ADS)

    Sirotinkin, V. P.; Bush, A. A.; Kamentsev, K. E.; Dau, H. S.; Yakovlev, K. A.; Tishchenko, E. A.

    2015-09-01

    Silver-containing LiCu2O2 crystals up to 4 × 8 × 8 mm in size were grown by the crystallization of 80(1- x)CuO · 20 x AgNO3 · 20Li2CO3 (0 ≤ х ≤ 0.5) mixture melt. According to the X-ray spectral and Rietveld X-ray diffraction data, the maximum amount of silver incorporated in the LiCu2O2 structure is about 4 at % relative to the copper content. It was established that silver atoms occupy statistically crystallographic positions of lithium atoms. The incorporation of silver atoms is accompanied by a noticeable increase in parameter с of the LiCu2O2 rhombic unit cell, a slight increase in parameter а, and a slight decrease in parameter b.

  11. Theoretical investigations of silver clusters and silver-ligand systems.

    SciTech Connect

    Jellinek, J.; Salian, U.; Srinivas, S.

    1999-05-19

    Studies directed at understanding structural and electronic properties of silver clusters have been and remain the subject of an active theoretical [1-22] and experimental [23- 38] effort. One of the reasons is the (still) important role these systems play in the photographic process. Investigations of interactions of silver clusters with different atoms and molecules are motivated primarily by a possible utility of these clusters in catalytic processes. The important role of silver in the selective oxidation of ethylene into ethylene oxide, the feedstock for polyester production, is well-known [39]. Possible variations in chemical reactivity with the cluster size and understanding of the mechanisms of interactions with different ligands may lead to new and more efficient applications. Investigations of cluster-ligand systems also contribute a great deal to a better understanding of gas-surface interactions. Accordingly, theoretical studies of silver clusters and cluster-ligand systems [40-44] fall into two categories--those that use clusters as models for silver surfaces [40], and those that target clusters and cluster-ligand interactions as subjects in their own right [41-44]. The common goal of all these studies is to elucidate the nature of the interatomic interactions and bonding at the microscopic level and thereby arrive at a fundamental understanding and description of the various structural and electronic properties.

  12. Protein retention on plasma-treated hierarchical nanoscale gold-silver platform

    PubMed Central

    Fang, Jinghua; Levchenko, Igor; Mai-Prochnow, Anne; Keidar, Michael; Cvelbar, Uros; Filipic, Gregor; Han, Zhao Jun; Ostrikov, Kostya (Ken)

    2015-01-01

    Dense arrays of gold-supported silver nanowires of about 100 nm in diameter grown directly in the channels of nanoporous aluminium oxide membrane were fabricated and tested as a novel platform for the immobilization and retention of BSA proteins in the microbial-protective environments. Additional treatment of the silver nanowires using low-temperature plasmas in the inductively-coupled plasma reactor and an atmospheric-pressure plasma jet have demonstrated that the morphology of the nanowire array can be controlled and the amount of the retained protein may be increased due to the plasma effect. A combination of the neutral gold sublayer with the antimicrobial properties of silver nanowires could significantly enhance the efficiency of the platforms used in various biotechnological processes. PMID:26307515

  13. Morphology Analysis of Si Island Arrays on Si(001)

    PubMed Central

    2010-01-01

    The formation of nanometer-scale islands is an important issue for bottom-up-based schemes in novel electronic, optoelectronic and magnetoelectronic devices technology. In this work, we present a detailed atomic force microscopy analysis of Si island arrays grown by molecular beam epitaxy. Recent reports have shown that self-assembled distributions of fourfold pyramid-like islands develop in 5-nm thick Si layers grown at substrate temperatures of 650 and 750°C on HF-prepared Si(001) substrates. Looking for wielding control and understanding the phenomena involved in this surface nanostructuring, we develop and apply a formalism that allows for processing large area AFM topographic images in a shot, obtaining surface orientation maps with specific information on facets population. The procedure reveals some noticeable features of these Si island arrays, e.g. a clear anisotropy of the in-plane local slope distributions. Total island volume analysis also indicates mass transport from the substrate surface to the 3D islands, a process presumably related to the presence of trenches around some of the pyramids. Results are discussed within the framework of similar island arrays in homoepitaxial and heteroepitaxial semiconductor systems. PMID:21170139

  14. Silver coordination polymers for prevention of implant infection: thiol interaction, impact on respiratory chain enzymes, and hydroxyl radical induction.

    PubMed

    Gordon, Oliver; Vig Slenters, Tünde; Brunetto, Priscilla S; Villaruz, Amer E; Sturdevant, Daniel E; Otto, Michael; Landmann, Regine; Fromm, Katharina M

    2010-10-01

    Prosthetic joint replacements are used increasingly to alleviate pain and improve mobility of the progressively older and more obese population. Implant infection occurs in about 5% of patients and entails significant morbidity and high social costs. It is most often caused by staphylococci, which are introduced perioperatively. They are a source of prolonged seeding and difficult to treat due to antibiotic resistance; therefore, infection prevention by prosthesis coating with nonantibiotic-type anti-infective substances is indicated. A renewed interest in topically used silver has fostered development of silver nanoparticles, which, however, present a potential health hazard. Here we present new silver coordination polymer networks with tailored physical and chemical properties as nanostructured coatings on metallic implant substrates. These compounds exhibited strong biofilm sugar-independent bactericidal activity on in vitro-grown biofilms and prevented murine Staphylococcus epidermidis implant infection in vivo with slow release of silver ions and limited transient leukocyte cytotoxicity. Furthermore, we describe the biochemical and molecular mechanisms of silver ion action by gene screening and by targeting cell metabolism of S. epidermidis at different levels. We demonstrate that silver ions inactivate enzymes by binding sulfhydryl (thiol) groups in amino acids and promote the release of iron with subsequent hydroxyl radical formation by an indirect mechanism likely mediated by reactive oxygen species. This is the first report investigating the global metabolic effects of silver in the context of a therapeutic application. We anticipate that the compounds presented here open a new treatment field with a high medical impact.

  15. Antimicrobial activity of silver-containing dressings on wound microorganisms using an in vitro biofilm model.

    PubMed

    Percival, Steven L; Bowler, Phillip G; Dolman, Jayne

    2007-06-01

    Antimicrobial dressings such as those containing silver are now being used widely to control wound bioburden, and tests to demonstrate their efficacy predominantly involve in vitro models using free-living or planktonic bacteria. In this present study a wide range of antibiotic-sensitive and resistant bacteria were tested in their quasi-sessile state using a standard agar assay and a second method used a poloxamer gel (true biofilm state - poloxamer encourages microorganisms to exhibit a more clinically relevant biofilm phenotype) technique. The antimicrobial activity of two silver dressings, a silver-containing Hydrofiber (SCH) dressing and a nanocrystalline silver-containing dressing (NCS), were evaluated on a variety of microorganisms, using a zone-of-inhibition (ZOI) test. When grown on agar (presenting a quasi-sessile state of each organism), the antibiotic-susceptible microorganisms were generally more susceptible to the SCH dressing compared with the NCS. ZOIs associated with SCH dressing ranged between 5.7 and 17.5 mm; those for the NCS against the same group of organisms ranged between 1.9 and 8.6 mm. When grown on poloxamer gel, (presenting the biofilm state of each organism) the same group of microorganisms were less susceptible to both dressings. The SCH dressing was most effective against strains of Pseudomonas aeruginosa, Candida albicans and Staphylococcus aureus (ZOI range: 2.6-6 mm); the NCS was most effective against strains of Klebsiella pneumoniae, Enterococcus faecalis and Escherichia coli (i.e. ZOI range: 1-2.8 mm). Similarly to the antibiotic-susceptible microorganisms, nine of ten antibiotic-resistant bacterial strains when grown on agar were more susceptible to the SCH dressing compared with the NCS. Although the microorganisms tested were universally less susceptible to the silver dressings when in their biofilm state, in the majority of cases, the SCH dressing demonstrated greater biofilm-inhibiting activity than the NCS.

  16. Size distributions of quantum islands on stepped substrates.

    PubMed

    Liang, S; Zhu, H L; Wang, W

    2009-10-21

    The size distributions of self-assembled quantum islands on stepped substrates are studied using kinetic Monte Carlo simulations. It is found that the energy barrier E(SW) between the step and the terrace region is the key factor in affecting the size distribution of islands. With small E(SW) (< or = 0.1 eV), lines of uniform islands can be obtained at relative low surface coverage. As the surface coverage is increased, wirelike islands can be obtained. Scaling behavior is obeyed for the size distributions of the wirelike islands. When the size distributions are separated into their width and length components, however, scaling is only observed in the length distribution of the wirelike islands. With larger E(SW), the size distribution of islands shows a clear bimodal size distribution and anomalous growth temperature dependent island size evolutions are observed. The simulation results reproduce qualitatively the phenomena observed in the cases of InAs islands grown on stepped GaAs substrates.

  17. Effects of simulated acidic rainfalls on yields of field-grown radishes and garden beets

    SciTech Connect

    Evans, L S; Cunningham, E A; Lewin, K F

    1981-01-01

    The effects of small additions of simulated acidic rain on radishes and garden beets grown under standard agronomic practices was determined. Only the foliage of plants was sprayed with simulated rain. The composition of the simulated rainfall approximated that of rain falling in the Long Island, NY area. (ACR)

  18. Processes involved in the formation of silver clusters on silicon surface

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S. R.; Chini, T. K.; Datta, D.; Hippler, R.; Shyjumon, I.; Smirnov, B. M.

    2008-12-01

    We analyze scanning electron microscopy measurements for structures formed in the deposition of solid silver clusters onto a silicon(100) substrate and consider theoretical models of cluster evolution onto a surface as a result of diffusion and formation of aggregates of merged clusters. Scanning electron microscopy (SEM) data are presented in addition to energy dispersive X-ray spectrometry (EDX) measurements of the these films. Solid silver clusters are produced by a DC magnetron sputtering source with a quadrupole filter for selection of cluster sizes (4.1 and 5.6 nm or 1900 and 5000 atoms per cluster in this experiment); the energy of cluster deposition is 0.7 eV/atom. Rapid thermal annealing of the grown films allows analysis of their behavior at high temperatures. The results exhibit formation of cluster aggregates via the diffusion of deposited solid clusters along the surface; an aggregate consists of up to hundreds of individual clusters. This process is essentially described by the diffusion-limited aggregation (DLA) model, and thus a grown porous film consists of cluster aggregates joined by bridges. Subsequent annealing of this film leads to its melting at temperatures lower than to the melting point of bulk silver. Analysis of evaporation of this film at higher temperatures gives a binding energy in bulk silver of ɛ0= (2.74 ± 0.03) eV/atom.

  19. Growth of fcc(111) Dy multi-height islands on 6H-SiC(0001) graphene.

    PubMed

    Hershberger, M T; Hupalo, M; Thiel, P A; Tringides, M C

    2013-06-01

    Graphene based spintronic devices require an understanding of the growth of magnetic metals. Rare earth metals have large bulk magnetic moments so they are good candidates for such applications, and it is important to identify their growth mode. Dysprosium was deposited on epitaxial graphene, prepared by thermally annealing 6H-SiC(0001). The majority of the grown islands have triangular instead of hexagonal shapes. This is observed both for single layer islands nucleating at the top of incomplete islands and for fully completed multi-height islands. We analyze the island shape distribution and stacking sequence of successively grown islands to deduce that the Dy islands have fcc(111) structure, and that the triangular shapes result from asymmetric barriers to corner crossing.

  20. The Myth of the Silver Surfer

    ERIC Educational Resources Information Center

    Gorard, Stephen; Selwyn, Neil

    2008-01-01

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

  1. Durable silver coating for mirrors

    DOEpatents

    Wolfe, Jesse D.; Thomas, Norman L.

    2000-01-01

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

  2. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-15

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  3. Geometrical parameters effects on local electric field enhancement of silver-dielectric-silver multilayer nanoshell

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-05-01

    The local electric field enhancement at different points of silver-dielectric-silver nanoshell is investigated using quasi-static theory. Because of the symmetric and anti-symmetric coupling between surface plasmon of inner silver core and outer silver shell, the local electric field spectrum of silver-dielectric-silver has two distinct peaks at resonance wavelengths. The silver core size and middle dielectric thickness affect the local electric field enhancement at different points of silver-dielectric-silver nanoshell. Increasing the silver core radius always leads to blue shift of shorter resonance wavelength and red shift of longer resonance wavelength. We observed two distinct local electric field peaks, which are corresponded to the symmetric and anti-symmetric coupling between inner and outer surface plasmons. In a system with thick silver shell, local electric field enhancement is greater than a system with thin silver shell. However, the local electric field variations as a function of silver core radius in both systems are different at different points of nanoshell. The effects of the dielectric thickness variations on local electric field are different from those from silver core size variations. As the dielectric thickness is about 3 nm, the highest local electric field enhancement occurs at the surface of the inner silver core, where the symmetric and anti-symmetric modes are mixed together.

  4. Sulfidation of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Levard, C.; Michel, F. M.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies that exploit the properties of silver nanoparticles (Ag-NPs) raises questions concerning the impact of Ag on the environment. Ag-NPs are currently among the most widely used in the nanotechnology industry and the amount released into the environment is expected to increase along with production (1). When present in geochemical systems, Ag-NPs may undergo a variety of changes due to varying redox, pH, and chemical conditions. Expected changes range from surface modification (e.g., oxidation, sulfidation, chloridation etc.) to complete dissolution and re-precipitation. In this context, the focus of our work is on understanding the behavior of synthetic Ag-NPs with different particle sizes under varying conditions relevant to the environment. Sulfidation of Ag-NPs is of particular interest since it among the processes most likely to occur in aqueous systems, in particular under reducing conditions. Three sizes of Ag-NPs coated with polyvinyl pyrrolidone were produced using the polyol process (2) (7 ±1; 20 ±4, and 40 ±9 nm). Batch solutions containing the different Ag-NPs were subsequently reacted with Na2S solutions of different concentrations. The sulfidation process was followed step-wise for 24 hours and the corrosion products formed were characterized by electron microscopy (TEM/SEM), diffraction (XRD), and photo-electron spectroscopy (XPS). Surface charge (pHPZC) of the products formed during this process was also measured, as were changes in solubility and reactivity. Based on experimental observations we infer that the sulfidation process is the result of dissolution-precipitation and find that: (i) acanthite (Ag2S) is formed as a corrosion product; (ii) Ag-NPs aggregation increased with sulfidation rate; (iii) pHPZC increases with the rate of sulfidation; and (iv) the solubility of the corrosion products formed from sulfidation appears lower than that of non-sulfidated Ag-NPs. We observe size-dependent differences in

  5. Japan: Shikoku Island

    Atmospheric Science Data Center

    2016-08-24

    ... deploying instruments aboard several ships, aircraft, and island stations in the waters surrounding Japan and Korea. They characterized ... These MISR images, centered just north of Shikoku Island in southwest Japan, were acquired on April 13, 2001 during Terra orbit ...

  6. Barrier Island Hazard Mapping.

    ERIC Educational Resources Information Center

    Pilkey, Orrin H.; Neal, William J.

    1980-01-01

    Describes efforts to evaluate and map the susceptibility of barrier islands to damage from storms, erosion, rising sea levels and other natural phenomena. Presented are criteria for assessing the safety and hazard potential of island developments. (WB)

  7. Synthesis and application of graphene-silver nanowires composite for ammonia gas sensing

    NASA Astrophysics Data System (ADS)

    Tran, Quang Trung; Hoa Huynh, Tran My; Tong, Duc Tai; Tam Tran, Van; Dinh Nguyen, Nang

    2013-12-01

    Graphene, consisting of a single carbon layer in a two-dimensional (2D) lattice, has been a promising material for application to nanoelectrical devices in recent years. In this study we report the development of a useful ammonia (NH3) gas sensor based on graphene-silver nanowires ‘composite’ with planar electrode structure. The basic strategy involves three steps: (i) preparation of graphene oxide (GO) by modified Hummers method; (ii) synthesis of silver nanowires by polyol method; and (iii) preparation of graphene and silver nanowires on two electrodes using spin and spray-coating of precursor solutions, respectively. Exposure of this sensor to NH3 induces a reversible resistance change at room temperature that is as large as ΔR/R0 ˜ 28% and this sensitivity is eight times larger than the sensitivity of the ‘intrinsic’ graphene based NH3 gas sensor (ΔR/R0 ˜ 3,5%). Their responses and the recovery times go down to ˜200 and ˜60 s, respectively. Because graphene synthesized by chemical methods has many defects and small sheets, it cannot be perfectly used for gas sensor or for nanoelectrical devices. The silver nanowires are applied to play the role of small bridges connecting many graphene islands together to improve electrical properties of graphene/silver nanowires composite and result in higher NH3 gas sensitivity.

  8. Hawaiian Islands, Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This cloudy view of the Hawaiian Islands (21.0N, 157.5W) demonstrates the phenomena of island water wakes and, to a lesser extent, cloud wakes as well. The islands form an obstruction to the ocean current flow and in effect create an observable turbulence in the water on the backside of the islands. The same effect can be observed in clouds as they leave wind blown wisps or streamers around obstacles in their path.

  9. Canary Island Archipelago

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This nearly vertical view of the Canary Archipelago (28.5N, 16.5W) shows five of the seven islands: Grand Canary, Tenerife, Gomera, Hierro and La Palma. The largest island in view is Tenerife. Island cloud wakes evident in this photo are the result of southerly winds giving rise to cloud banks on the lee side especially on Tenerife which has the highest volcanic peaks. Island water wakes and internal waves are also evident but not as apparent.

  10. Henderson Island, Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Henderson Island (24.5S, 128.5W) Pacific Ocean southeast of the Tuamotu Archipelago, is a good example of the many barren islands that but for lack of a source of water could be another lush tropical paradise. The crew of HMS Bounty, in searching for a refuge, sailed past this island but rejected it in favor of nearby Pitcairn Island because of the lack of resources and water.

  11. Arctic ice islands

    SciTech Connect

    Sackinger, W.M.; Jeffries, M.O.; Lu, M.C.; Li, F.C.

    1988-01-01

    The development of offshore oil and gas resources in the Arctic waters of Alaska requires offshore structures which successfully resist the lateral forces due to moving, drifting ice. Ice islands are floating, a tabular icebergs, up to 60 meters thick, of solid ice throughout their thickness. The ice islands are thus regarded as the strongest ice features in the Arctic; fixed offshore structures which can directly withstand the impact of ice islands are possible but in some locations may be so expensive as to make oilfield development uneconomic. The resolution of the ice island problem requires two research steps: (1) calculation of the probability of interaction between an ice island and an offshore structure in a given region; and (2) if the probability if sufficiently large, then the study of possible interactions between ice island and structure, to discover mitigative measures to deal with the moving ice island. The ice island research conducted during the 1983-1988 interval, which is summarized in this report, was concerned with the first step. Monte Carlo simulations of ice island generation and movement suggest that ice island lifetimes range from 0 to 70 years, and that 85% of the lifetimes are less then 35 years. The simulation shows a mean value of 18 ice islands present at any time in the Arctic Ocean, with a 90% probability of less than 30 ice islands. At this time, approximately 34 ice islands are known, from observations, to exist in the Arctic Ocean, not including the 10-meter thick class of ice islands. Return interval plots from the simulation show that coastal zones of the Beaufort and Chukchi Seas, already leased for oil development, have ice island recurrences of 10 to 100 years. This implies that the ice island hazard must be considered thoroughly, and appropriate safety measures adopted, when offshore oil production plans are formulated for the Alaskan Arctic offshore. 132 refs., 161 figs., 17 tabs.

  12. Falkland Islands, UK

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This view of the Falkland Islands (52.0S, 58.5W) was taken with a dual camera mount. Compare this scene with STS048-109-043 to analyze the unique properties of each film type. Seldom seen cloud free, the Falkland Islands lie off the southern coast of Argentina. The cold Falklands Ocean Current keeps the islands chilly, ideal for sheep herding and fishing, the two main industries. Colonies of seals and penguins also thrive on the islands.

  13. Energy dependence of island nucleation density during ion beam deposition

    NASA Astrophysics Data System (ADS)

    Pomeroy, Joshua M.; Brock, Joel D.

    2002-03-01

    Thin copper films were grown on single crystal copper substrates using highly collimated copper ion beams with precisely controlled incidence energies. The energetic collisions between the copper ions and the surface can form adatom-vacancy pairs or sputter eject atoms into the vaccuum. Island nucleation densities are affected by these atomistic mechanisms, which increase surface adatom densities and surface defect densities. This paper reports STM measurements of the island nucleation density for films grown both thermally and at energies between 10-150 eV. The measured island nucleation density systematically deviates with increasing energy from the density predicted by mean field nucleation theory (J.A. Venables, et.al., Rep. Prog. Phys. 47 (1984) p. 399-459). This deviation can be understood using a phenomenological extension of mean field nucleation theory that includes the effects of adatom-vacancy pair production and sputter ejection on the effective flux.

  14. Generation Behaviors of Optical Anisotropy Caused by Silver Nanoparticles Precipitated in Uniaxially Drawn Polyimide Films

    NASA Astrophysics Data System (ADS)

    Matsuda, Sho-ichi; Ando, Shinji

    2005-01-01

    The optical anisotropy generated during thermal curing and simultaneous uniaxial drawing of poly(amic acid) (PAA) films dissolving silver nitrate was investigated. The PAA was converted to polyimide (PI) during thermal curing, and silver nanoparticles were precipitated in the oriented PI films. The anisotropy in optical transmittance, i.e., the polarization characteristic, of the films strongly depended on the holding time at the final curing temperature, and a large anisotropy in transmittance with a wide wavelength region (wide-range optical anisotropy) was observed only for a film cured for the optimal holding time. During heating at the final curing temperature, silver nanoparticles were anisotropically grown and aggregated along the drawing direction, generating a significant optical anisotropy. However, additional heating induces isotropic growth, aggregation, and fusion of silver nanoparticles, resulting in the reduction in anisotropy. A numerical analysis based on the Mie theory revealed that the wide-range optical anisotropy can be generated by the anisotropies in shape and the preferential aggregation and arrays of silver nanoparticles in the drawing direction as well as the large birefringence of PI films as dielectric media.

  15. Mineral resource of the month: silver

    USGS Publications Warehouse

    Brooks, William E.

    2007-01-01

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

  16. Pine Island Glacier

    Atmospheric Science Data Center

    2013-04-16

    article title:  Pine Island Glacier, Antarctica     View ... Imaging SpectroRadiometer (MISR) images of the Pine Island Glacier in western Antarctica was acquired on December 12, 2000 during ... sea ice between the glacier and the open water in Pine Island Bay. To the left of the "icebergs" label are chunks of floating ice. ...

  17. Diomede Islands, Bering Straight

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Diomede Islands consisting of the western island Big Diomede (also known as Imaqliq, Nunarbuk or Ratmanov Island), and the eastern island Little Diomede (also known as Krusenstern Island or Inaliq), are two rocky islands located in the middle of the Bering Strait between Russia and Alaska. The islands are separated by an international border and the International Date Line which is approximately 1.5 km from each island; you can look from Alaska into tomorrow in Russia. At the closest land approach between the United States, which controls Little Diomede, and Russia, which controls Big Diomede, they are 3 km apart. Little Diomede Island constitutes the Alaskan City of Diomede, while Big Diomede Island is Russia's easternmost point. The first European to reach the islands was the Russian explorer Semyon Dezhnev in 1648. The text of the 1867 treaty finalizing the sale of Alaska uses the islands to designate the border between the two nations.

    The image was acquired July 8, 2000, covers an area of 13.5 x 10.8 km, and is located at 65.8 degrees north latitude, 169 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  18. The role of Ag buffer layer in Fe islands growth on Ge (111) surfaces

    SciTech Connect

    Fu, Tsu-Yi Wu, Jia-Yuan; Jhou, Ming-Kuan; Hsu, Hung-Chan

    2015-05-07

    Sub-monolayer iron atoms were deposited at room temperature on Ge (111)-c(2 × 8) substrates with and without Ag buffer layers. The behavior of Fe islands growth was investigated by using scanning tunneling microscope (STM) after different annealing temperatures. STM images show that iron atoms will cause defects and holes on substrates at room temperature. As the annealing temperature rises, iron atoms pull out germanium to form various kinds of alloyed islands. However, the silver layer can protect the Ag/Ge(111)-(√3×√3) reconstruction from forming defects. The phase diagram shows that ring, dot, and triangular defects were only found on Ge (111)-c(2 × 8) substrates. The kinds of islands found in Fe/Ge system are similar to Fe/Ag/Ge system. It indicates that Ge atoms were pulled out to form islands at high annealing temperatures whether there was a Ag layer or not. But a few differences in big pyramidal or strip islands show that the silver layer affects the development of islands by changing the surface symmetry and diffusion coefficient. The structure characters of various islands are also discussed.

  19. The antimicrobial efficacy of a silver alginate dressing against a broad spectrum of clinically relevant wound isolates.

    PubMed

    Percival, Steven L; Slone, Will; Linton, Sara; Okel, Tyler; Corum, Linda; Thomas, John G

    2011-06-01

    Wound dressings impregnated with silver have a role to play in aiding to reduce both the dressing and wound microbial bioburden. It is therefore imperative that antimicrobial wound dressings have efficacy on a broad range of clinical significant microorganisms. Accordingly, this study aimed to determine the antimicrobial efficacy of a silver alginate dressing against 115 wound isolates that had been isolated routinely from patients at West Virginia University Hospital. Standardised corrected zones of inhibition (CZOIs) were performed on all clinical isolates. It was found that the silver alginate dressing was able to inhibit the growth of all microorganisms tested. In particular, the silver alginate dressing inhibited the growth of Candida albicans and yeasts with CZOI of 3-11·5 mm. All meticillin-resistant Staphylococcus aureus (MRSA) strains were found to be sensitive to the silver alginate dressing with a CZOI range calculated at 3-7·8 mm. Sensitivity to the silver alginate dressing was also evident for S. aureus and vancomycin-resistant Enterococci. CZOIs of 4·25 mm were calculated for Enterococcus faecium and 9·8 mm for viridans streptococcus. The bacteria which demonstrated the highest tolerance to ionic silver included Enterobacter cloacae and Acinetobacter baumannii. Contrary to this the most responsive microorganisms to ionic silver included strains of staphylococci, viridans streptococcus and Candida albicans. No antibiotic-resistant isolates, as identified by Kirby Bauer Clinical Laboratory Standards Institute classification system, were found to be resistant to ionic silver. When a selected number of microorganisms were grown in the biofilm phenotypic state enhanced tolerance to silver was observed, compared to their non biofilm counterparts. Overall, this study has demonstrated the broad antimicrobial activity of a silver alginate dressing on wound isolates grown in the non biofilm and biofilm state. This finding is clinically relevant as both the

  20. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    NASA Astrophysics Data System (ADS)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  1. Silver based batteries for high power applications

    NASA Astrophysics Data System (ADS)

    Karpinski, A. P.; Russell, S. J.; Serenyi, J. R.; Murphy, J. P.

    The present status of silver oxide-zinc technology and applications has been described by Karpinski et al. [A.P. Karpinski, B. Makovetski, S.J. Russell, J.R. Serenyi, D.C. Williams, Silver-Zinc: status of technology and applications, Journal of Power Sources, 80 (1999) 53-60], where the silver-zinc couple is still the preferred choice where high specific energy/energy density, coupled with high specific power/power density are important for high-rate, weight or size/configuration sensitive applications. Perhaps the silver oxide cathode can be considered one of the most versatile electrode materials. When coupled with other anodes and corresponding electrolyte management system, the silver electrode provides for a wide array of electrochemical systems that can be tailored to meet the most demanding, high power requirements. Besides zinc, the most notable include cadmium, iron, metal hydride, and hydrogen electrode for secondary systems, while primary systems include lithium and aluminum. Alloys including silver are also available, such as silver chloride, which when coupled with magnesium or aluminum are primarily used in many seawater applications. The selection and use of these couples is normally the result of a trade-off of many factors. These include performance, safety, risk, reliability, and cost. When high power is required, silver oxide-zinc, silver oxide-aluminum, and silver oxide-lithium are the most energetic. For moderate performance (i.e., lower power), silver oxide-zinc or silver-cadmium would be the system of choice. This paper summarizes the suitability of the silver-based couples, with an emphasis on the silver-zinc system, as primary or rechargeable power sources for high energy/power applications.

  2. Comparison of 20 nm silver nanoparticles synthesized with and without a gold core: Structure, dissolution in cell culture media, and biological impact on macrophages.

    PubMed

    Munusamy, Prabhakaran; Wang, Chongmin; Engelhard, Mark H; Baer, Donald R; Smith, Jordan N; Liu, Chongxuan; Kodali, Vamsi; Thrall, Brian D; Chen, Shu; Porter, Alexandra E; Ryan, Mary P

    2015-09-15

    Widespread use of silver nanoparticles raises questions of environmental and biological impact. Many synthesis approaches are used to produce pure silver and silver-shell gold-core particles optimized for specific applications. Since both nanoparticles and silver dissolved from the particles may impact the biological response, it is important to understand the physicochemical characteristics along with the biological impact of nanoparticles produced by different processes. The authors have examined the structure, dissolution, and impact of particle exposure to macrophage cells of two 20 nm silver particles synthesized in different ways, which have different internal structures. The structures were examined by electron microscopy and dissolution measured in Rosewell Park Memorial Institute media with 10% fetal bovine serum. Cytotoxicity and oxidative stress were used to measure biological impact on RAW 264.7 macrophage cells. The particles were polycrystalline, but 20 nm particles grown on gold seed particles had smaller crystallite size with many high-energy grain boundaries and defects, and an apparent higher solubility than 20 nm pure silver particles. Greater oxidative stress and cytotoxicity were observed for 20 nm particles containing the Au core than for 20 nm pure silver particles. A simple dissolution model described the time variation of particle size and dissolved silver for particle loadings larger than 9 μg/ml for the 24-h period characteristic of many in-vitro studies.

  3. Comparison of 20 nm silver nanoparticles synthesized with and without a gold core: Structure, dissolution in cell culture media, and biological impact on macrophages

    PubMed Central

    Munusamy, Prabhakaran; Wang, Chongmin; Engelhard, Mark H.; Baer, Donald R.; Smith, Jordan N.; Liu, Chongxuan; Kodali, Vamsi; Thrall, Brian D.; Chen, Shu; Porter, Alexandra E.; Ryan, Mary P.

    2015-01-01

    Widespread use of silver nanoparticles raises questions of environmental and biological impact. Many synthesis approaches are used to produce pure silver and silver-shell gold-core particles optimized for specific applications. Since both nanoparticles and silver dissolved from the particles may impact the biological response, it is important to understand the physicochemical characteristics along with the biological impact of nanoparticles produced by different processes. The authors have examined the structure, dissolution, and impact of particle exposure to macrophage cells of two 20 nm silver particles synthesized in different ways, which have different internal structures. The structures were examined by electron microscopy and dissolution measured in Rosewell Park Memorial Institute media with 10% fetal bovine serum. Cytotoxicity and oxidative stress were used to measure biological impact on RAW 264.7 macrophage cells. The particles were polycrystalline, but 20 nm particles grown on gold seed particles had smaller crystallite size with many high-energy grain boundaries and defects, and an apparent higher solubility than 20 nm pure silver particles. Greater oxidative stress and cytotoxicity were observed for 20 nm particles containing the Au core than for 20 nm pure silver particles. A simple dissolution model described the time variation of particle size and dissolved silver for particle loadings larger than 9 μg/ml for the 24-h period characteristic of many in-vitro studies. PMID:26178265

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

    NASA Astrophysics Data System (ADS)

    Sudheer, Tiwari, P.; Varshney, G. K.; Rai, V. N.; Srivastava, A. K.

    2016-05-01

    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.

  5. Effect of nano-silver and boric acid on extending the vase life of cut rose (Rosa hybrida L.).

    PubMed

    Hashemabadi, Davood; Liavali, Mahbanoo Hoseinzadeh; Kaviani, Behzad; Mousavi, Meysam; Keyghobadi, Saghi; Zahiri, Samaneh

    2014-09-01

    Silver nano-particles (2-5 nm diam.), as antimicrobial agent and boric acid, as ethylene production inhibitor are used for enhancing the quality and vase life of cut flowers. In the present study the effects of a preservative solution containing nano-silver and boric acid on some traits of cut rose (Rosa hybrida L. cv. Yellow Island) including vase life, ethylene production, dry weight percentage, chlorophyll content, flower opening index, beta-carotene of petals and the number of basal stem end bacteria were investigated. The results showed that the effect of nano-silver and boric acid as either solitary or in combination with each other were significant (p < or = 0.01) on vase life, ethylene production and beta-carotene pigment. The effect of nano-silver on the number of bacteria on the end of stem was significant (p < or = 0.01). The highest cut flower longevity (9.69 day) was obtained in pulse-treated flowers with 100 mg l(-1) boric acid. The least ethylene production (0.59 nl(-1) g(-1) h(-1)) was observed in cut rose treated with 100 mg l(-1) boric acid along with 5 mg l(-1) nano-silver. The lowest number of bacteria in the end of stem was calculated in cut flowers treated with the highest concentrations of boric acid (300 mg l(-1)) and nano-silver (20 mg l(-1)).

  6. Self-organized single crystal mixed magnetite/cobalt ferrite films grown by infrared pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    de la Figuera, Juan; Quesada, Adrián; Martín-García, Laura; Sanz, Mikel; Oujja, Mohamed; Rebollar, Esther; Castillejo, Marta; Prieto, Pilar; Muñoz-Martín, Ángel; Aballe, Lucía; Marco, José F.

    2015-12-01

    We have grown mixed magnetite/cobalt ferrite epitaxial films on SrTiO3 by infrared pulsed-laser deposition. Diffraction experiments indicate epitaxial growth with a relaxed lattice spacing. The films are flat with two distinct island types: nanometric rectangular mounds in two perpendicular orientations, and larger square islands, attributed to the two main components of the film as determined by Mössbauer spectroscopy. The origin of the segregation is suggested to be the oxygen-deficiency during growth.

  7. Protein Crystals Grown in Space

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A collage of protein and virus crystals, many of which were grown on the U.S. Space Shuttle or Russian Space Station, Mir. The crystals include the proteins canavalin; mouse monoclonal antibody; a sweet protein, thaumatin; and a fungal protease. Viruses are represented here by crystals of turnip yellow mosaic virus and satellite tobacco mosaic virus. The crystals are photographed under polarized light (thus causing the colors) and range in size from a few hundred microns in edge length up to more than a millimeter. All the crystals are grown from aqueous solutions and are useful for X-ray diffraction analysis. Credit: Dr. Alex McPherson, University of California, Irvine.

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

    PubMed Central

    2014-01-01

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

  9. Contemporary anthropogenic silver cycle: a multilevel analysis.

    PubMed

    Johnson, Jeremiah; Jirikowic, Julie; Bertram, Marlen; van Beers, D; Gordon, R B; Henderson, Kathryn; Klee, R J; Lanzano, Ted; Lifset, R; Oetjen, Lucia; Graedel, T E

    2005-06-15

    Anthropogenic cycling of silver in 1997 is presented using three discrete governmental units: 64 countries encompassing what we believe to be over 90% of global silver flows, 9 world regions, and the entire planet. Using material flow analysis (MFA) techniques, the country level cycles are aggregated to produce the regional cycles, which are used to form a "best estimate" global cycle. Interesting findings include the following: (1) several silver-mining countries export ore and concentrate but also import silver-containing semiproducts and products; (2) the level of development for a country, as indicated by the gross domestic product, is a fair indicator of silver use, but several significant outliers exist; (3) the countries with the greatest mine production include Mexico, the United States, Peru, and China, whereas the United States, Japan, India, Germany, and Italy lead in the fabrication and manufacture of products; (4) North America and Europe's use of silver products exceed that of other regions on a per capita basis; (5) global silver discards, including tailings and separation waste, totaled approximately 57% of the silver mined; (6) approximately 57% of the silver entering waste management globally is recycled; and (7) the amount of silver entering landfills globally is comparable to the amount found in tailings. The results of this MFA lay the basis for further analysis, which in turn can offer insight into natural resource policy, the characterization of environmental impact, and better resource management.

  10. Contemporary anthropogenic silver cycle: a multilevel analysis.

    PubMed

    Johnson, Jeremiah; Jirikowic, Julie; Bertram, Marlen; van Beers, D; Gordon, R B; Henderson, Kathryn; Klee, R J; Lanzano, Ted; Lifset, R; Oetjen, Lucia; Graedel, T E

    2005-06-15

    Anthropogenic cycling of silver in 1997 is presented using three discrete governmental units: 64 countries encompassing what we believe to be over 90% of global silver flows, 9 world regions, and the entire planet. Using material flow analysis (MFA) techniques, the country level cycles are aggregated to produce the regional cycles, which are used to form a "best estimate" global cycle. Interesting findings include the following: (1) several silver-mining countries export ore and concentrate but also import silver-containing semiproducts and products; (2) the level of development for a country, as indicated by the gross domestic product, is a fair indicator of silver use, but several significant outliers exist; (3) the countries with the greatest mine production include Mexico, the United States, Peru, and China, whereas the United States, Japan, India, Germany, and Italy lead in the fabrication and manufacture of products; (4) North America and Europe's use of silver products exceed that of other regions on a per capita basis; (5) global silver discards, including tailings and separation waste, totaled approximately 57% of the silver mined; (6) approximately 57% of the silver entering waste management globally is recycled; and (7) the amount of silver entering landfills globally is comparable to the amount found in tailings. The results of this MFA lay the basis for further analysis, which in turn can offer insight into natural resource policy, the characterization of environmental impact, and better resource management. PMID:16047806

  11. Ultrafast electronic relaxation processes in semiconductor nanoparticles (silver iodide, silver iodide/silver sulfide, silver bromide/silver sulfide, silver sulfide, cupric sulfide, and copper sulfide) and carotenoids

    NASA Astrophysics Data System (ADS)

    Brelle, Michael Chris

    2000-11-01

    This dissertation examines primarily the ultrafast dynamics of excited state charge carriers in semiconductor nanoparticles. The dissertation also briefly examines the excited state lifetimes of a few carotenoids. Understanding the dynamic properties of charge carriers in semiconductor nanoparticles is crucial for the further development of applications utilizing these systems. The dynamic properties including shallow and deep trapping as well as recombination have been studied in a variety of semiconductor nanoparticle systems. Kinetic modeling was utilized to assist in the assignment of all observed signals and the nature of the decays. The first observation of ultrafast trapping in silver halides was observed in AgI nanoparticles including the identification that interstitial silver ions may act as deep traps. Several interesting phenomena were observed in Ag2S and CuxS nanoparticles including dark shallow trap states and shallow trap state saturation leading to increased transient absorption over transient bleach with increasing excitation intensity. These observations have provided further insight into the relaxation pathways for charge carriers in semiconductor nanoparticle systems. Lifetimes of the S2 excited states of four carotenoids have also been determined. The S2 lifetime for beta-carotene was confirmed from previous fluorescence up-conversion experiments whereas the S2 lifetimes that were previously unknown for three carotenoids, violaxanthin, neaxanthin, and lutein were discovered. These experiments together demonstrate the capabilities of femtosecond pump-probe spectroscopy to characterize and better understand the processes involved in the ultrafast relaxation events in both molecular and nanoparticle systems.

  12. Room temperature direct band gap emission characteristics of surfactant mediated grown compressively strained Ge films

    NASA Astrophysics Data System (ADS)

    Katiyar, Ajit K.; Grimm, Andreas; Bar, R.; Schmidt, Jan; Wietler, Tobias; Joerg Osten, H.; Ray, Samit K.

    2016-10-01

    Compressively strained Ge films have been grown on relaxed Si0.45Ge0.55 virtual substrates using molecular beam epitaxy in the presence of Sb as a surfactant. Structural characterization has shown that films grown in the presence of surfactant exhibit very smooth surfaces with a relatively higher strain value in comparison to those grown without any surfactant. The variation of strain with increasing Ge layer thickness was analyzed using Raman spectroscopy. The strain is found to be reduced with increasing film thickness due to the onset of island nucleation following Stranski-Krastanov growth mechanism. No phonon assisted direct band gap photoluminescence from compressively strained Ge films grown on relaxed Si0.45Ge0.55 has been achieved up to room temperature. Excitation power and temperature dependent photoluminescence have been studied in details to investigate the origin of different emission sub-bands.

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

    EPA Science Inventory

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

  14. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires.

    PubMed

    Sohn, Eun Kyung; Johari, Seyed Ali; Kim, Tae Gyu; Kim, Jin Kwon; Kim, Ellen; Lee, Ji Hyun; Chung, Young Shin; Yu, Il Je

    2015-01-01

    To better understand the potential ecotoxicological impact of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) released into freshwater environments, the toxicities of these nanomaterials were assessed and compared using Organization for Economic Cooperation and Development (OECD) test guidelines, including a "Daphnia sp., acute immobilization test," "Fish, acute toxicity test," and "freshwater alga and cyanobacteria, growth inhibition test." Based on the estimated median lethal/effective concentrations of AgNPs and AgNWs, the susceptibility to the nanomaterials was different among test organisms (daphnia > algae > fish), suggesting that the AgNPs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 1" for Raphidocelis subcapitata, while the AgNWs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 2" for Raphidocelis subcapitata, according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals). In conclusion, the present results suggest that more attention should be paid to prevent the accidental or intentional release of silver nanomaterials into freshwater aquatic environments. PMID:26125025

  15. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires

    PubMed Central

    Kim, Tae Gyu; Kim, Jin Kwon; Kim, Ellen; Lee, Ji Hyun; Chung, Young Shin

    2015-01-01

    To better understand the potential ecotoxicological impact of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) released into freshwater environments, the toxicities of these nanomaterials were assessed and compared using Organization for Economic Cooperation and Development (OECD) test guidelines, including a “Daphnia sp., acute immobilization test,” “Fish, acute toxicity test,” and “freshwater alga and cyanobacteria, growth inhibition test.” Based on the estimated median lethal/effective concentrations of AgNPs and AgNWs, the susceptibility to the nanomaterials was different among test organisms (daphnia > algae > fish), suggesting that the AgNPs are classified as “category acute 1” for Daphnia magna, “category acute 2” for Oryzias latipes, and “category acute 1” for Raphidocelis subcapitata, while the AgNWs are classified as “category acute 1” for Daphnia magna, “category acute 2” for Oryzias latipes, and “category acute 2” for Raphidocelis subcapitata, according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals). In conclusion, the present results suggest that more attention should be paid to prevent the accidental or intentional release of silver nanomaterials into freshwater aquatic environments. PMID:26125025

  16. Silver ions eluted from partially protected silver nanoparticles.

    PubMed

    Heidari Zare, Hamideh; Düttmann, Oliver; Vass, Attila; Franz, Gerhard; Jocham, Dieter

    2016-01-01

    The most prominent character of a new type of antibacterial urological catheters is the zebra-stripe pattern of a silver film, which is plated electroless on their interior wall and capped by a very thin semipermeable layer of parylene. This design effectively controls the release rate of Ag(+) ions in artificial urine, which has been measured as function of time with optical emission spectroscopy. By evaluating the minimum inhibitory concentration against certain strains of bacteria with solutions of AgNO3 of known concentration with the method of optical density and applying this analysis to the silver-eluting catheters, it was shown that this moderation prolongs the period of their application significantly. But to act as antibacterial agent in chlorine-containing solutions, as in urine, the presence of urea is required to avoid precipitation of AgCl and to meet or even exceed the minimum inhibitory concentration of Ag(+). The quality of the silver depot layer was further determined by the deposition rate and its morphology, which revealed that the film consisted of grains with a mean size of 150 nm. PMID:27400747

  17. Application of Silver and Silver Oxide Nanoparticles Impregnated on Activated Carbon to the Degradation of Bromate.

    PubMed

    Choi, J S; Lee, H; Park, Y K; Kim, S J; Kim, B J; An, K H; Kim, B H; Jung, S C

    2016-05-01

    Silver and silver oxide nanoparticles were impregnated on the surface of powdered activated carbon (PAC) using a single-step liquid phase plasma (LPP) method. Spherical silver and silver oxide nanoparticles of 20 to 100 nm size were dipersed evenly on the surface of PAC. The impregnated PAC exhibited a higher activity for the decomposition of bromate than bare PAC. The XPS, Raman and EDX analyses showed that the Ag/PAC composites synthesized by the LPP process. PMID:27483780

  18. Silver nanocluster catalytic microreactors for water purification

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  19. Preparation of silver nanoparticles at low temperature

    NASA Astrophysics Data System (ADS)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

    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.

  20. 21 CFR 872.3840 - Endodontic silver point.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3840 Endodontic silver point. (a) Identification. An endodontic silver point is a device made of silver intended for use during endodontic therapy...

  1. Preparation of silver-activated zinc sulfide thin films

    NASA Technical Reports Server (NTRS)

    Feldman, C.; Swindells, F. E.

    1968-01-01

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

  2. Liquid source metal-organic chemical-vapor deposition of high-quality YBa2Cu3O7-x films on polycrystalline silver substrates

    NASA Astrophysics Data System (ADS)

    Studebaker, D. B.; Zhang, J.; Marks, T. J.; Wang, Y. Y.; Dravid, V. P.; Schindler, J. L.; Kannewurf, C. R.

    1998-03-01

    High-temperature superconducting YBa2Cu3O7-x films were grown by liquid delivery metal-organic chemical-vapor deposition on silver-coated stainless-steel substrates. The films are highly c-axis oriented, have a Tc above 90 K, and exhibit a surface resistance of 110 μΩ at 77 K and 3 GHz.

  3. Risk assessment of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shipelin, V. A.; Gmoshinski, I. V.; Khotimchenko, S. A.

    2015-11-01

    Nanoparticles of metallic silver (Ag) are among the most widely used products of nanotechnology. Nanosized colloidal silver (NCS) is presented in many kinds of production as solutions of particles with diameter less than 100 nm. NCS is used in a variety of fields, including food supplements, medicines, cosmetics, packaging materials, disinfectants, water filters, and many others. Problems of toxicity and related safety of NCS for humans and environmental systems are recently overestimated basing on data of numerous toxicological studies in vitro and in vivo. The article discusses the results of current studies in recent years and the data of author's own experiments on studying the safety of NCS, that allows to move on to risk assessment of this nanomaterial presented in consumer products and environmental samples.

  4. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  5. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  6. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  7. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  8. 40 CFR 421.120 - Applicability: Description of the secondary silver subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... secondary silver subcategory. 421.120 Section 421.120 Protection of Environment ENVIRONMENTAL PROTECTION... CATEGORY Secondary Silver Subcategory § 421.120 Applicability: Description of the secondary silver... silver from secondary silver facilities processing photographic and nonphotographic raw materials....

  9. Synthesis and optical properties of silver nanoparticles

    SciTech Connect

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

    2015-07-31

    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.

  10. Synthesis and optical properties of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    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.

  11. Silver europium(III) polyphosphate

    PubMed Central

    Ayadi, Mounir; Férid, Mokhtar; Moine, Bernard

    2009-01-01

    Europium(III) silver polyphosphate, AgEu(PO3)4, was prepared by the flux method. The atomic arrangement is built up by infinite (PO3)n chains (periodicity of 4) extending along the c axis. These chains are joined to each other by EuO8 dodeca­hedra. The Ag+ cations are located in the voids of this arrangement and are surrounded by five oxygen atoms in a distorted [4+1] coordination. PMID:21582031

  12. Synthesis and structural evolution of mesoporous silica silver nanocomposites

    NASA Astrophysics Data System (ADS)

    Armelao, L.; Bottaro, G.; Campostrini, R.; Gialanella, S.; Ischia, M.; Poli, F.; Tondello, E.

    2007-04-01

    Mesoporous silica materials were prepared by a sol-gel procedure using Si(OCH2CH3)4 (TEOS) as the silica source and the non-ionic alkyl-poly(ethyleneoxide) oligomer Brij76 as the structure-directing agent. Pure inorganic hexagonal-like mesostructured SiO2 powders were obtained after annealing, performed in air between 400 and 600 °C. Upon calcination, the organic template was removed and silica networks with a different amount of Si-OH groups as well as porous features were prepared. Ag-SiO2 nanocomposites were obtained by metallation of the mesoporous silica powders with aqueous solutions of silver acetate. Ag+ ions were chemically grafted on the silica pores by taking advantage of the basic character of acetate anions and the acidic properties of Si-OH groups. Different silver concentrations were achieved on the mesostructured silica powders, depending on their former annealing treatment. For all samples the formation of silver nanoclusters occurred spontaneously at room temperature. Monodispersed, spherical Ag crystallites, with an average diameter of a few nanometres, were obtained starting from the 400 °C-treated silica, whereas clusters with different sizes (3-20 nm) and irregular shapes were grown for metallation of the 600 °C-heated SiO2 matrix. The sample's chemical composition was studied by x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger electron spectroscopy (XE-AES), whereas the porous features were investigated by N2 BET adsorption. Information concerning structure and microstructure was obtained by x-ray diffraction (XRD) and transmission electron microscopy (TEM).

  13. Properties of polypropylene nanocomposites containing silver nanoparticles.

    PubMed

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

    2007-11-01

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

  14. Morphology of a silver/polyacrylonitrile nanocomposite

    NASA Astrophysics Data System (ADS)

    Kudryashov, M. A.; Mashin, A. I.; Tyurin, A. S.; Fedosov, A. E.; Chidichimo, G.; De Filpo, G.

    2011-01-01

    Silver/polyacrylonitrile (Ag/PAN) nanocomposites are synthesized at the stage of simultaneous acrylonitrile polymerization and the reduction of silver ions from a mixture of silver nitrate AgNO3, acrylonitrile, and a photoinitiator. The synthesized films are transparent in the visible region and are characterized by a uniform dispersion of silver nanoparticles in a PAN matrix without any macroscopic agglomeration. The effects of the metal salt and photoinitiator concentrations on the size and density of metal nanoparticles in a composite are revealed.

  15. Spectroscopic analysis of biologically synthesized silver nanoparticles under clinorotation

    NASA Astrophysics Data System (ADS)

    Jagtap, Sagar; Vidyasagar, Pandit; Ghemud, Vipul; Dixit, Jyotsana

    Nanoparticles are one of the hot topics of research due to their size dependent optical, electrical and magnetic properties & their anti-bacterial and anti-fungal nature. Synthesis of nano particles can be done by various physical and chemical methods. However, Biosynthesis of nanoparticles is environment friendly, can take place around room temperature, and require little intervention or input of energy. In the present study, the synthesis of silver nanoparticles (AgNPs) using bacteria and the effect of clinorotation on rate of synthesis is discussed. The freshly grown bacterial isolate was inoculated in to 250-ml Erlenmeyer flask containing 50 ml sterile nutrient broth (LB). The cultured flasks were incubated in a shaker at 120 rpm for 24 h at 370C. Culture was centrifuged at 10,000 rpm for 10 min. The supernatant was used for carrying extracellular production of silver nanoparticles by mixing it with 5mM AgNO3 solution. The above solution was clinorotated at 2 rpm for 24 h. The synthesis was carried out at 60oC. Visual observation was conducted periodically to check for the nanoparticles formation in normal gravity as well as under clinorotation. UV-visible spectroscopic analysis showed that rate of synthesis was faster in case of clinorotated sample than control. Further, the results of FTIR and XRD characterization will be discussed.

  16. Ober's Island, One of the Review Islands on Rainy Lake, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Ober's Island, One of the Review Islands on Rainy Lake, bounded on the south by The Hawk Island and on the north by The Crow Island. These islands are located seven miles east of Ranier, Minnesota, three miles west of Voyageur National Park, and one mile south of the international border of the United States of America and Canada. The legal description of Mallard Island is Lot 6, Section 19, T-17-N, R-22-W, Koochiching County, Minnesota, Ranier, Koochiching County, MN

  17. X-ray diffraction analysis of LiCu{sub 2}O{sub 2} crystals with additives of silver atoms

    SciTech Connect

    Sirotinkin, V. P. Bush, A. A.; Kamentsev, K. E.; Dau, H. S.; Yakovlev, K. A.; Tishchenko, E. A.

    2015-09-15

    Silver-containing LiCu{sub 2}O{sub 2} crystals up to 4 × 8 × 8 mm in size were grown by the crystallization of 80(1-x)CuO · 20{sub x}AgNO{sub 3} · 20Li{sub 2}CO{sub 3} (0 ≤ x ≤ 0.5) mixture melt. According to the X-ray spectral and Rietveld X-ray diffraction data, the maximum amount of silver incorporated in the LiCu{sub 2}O{sub 2} structure is about 4 at % relative to the copper content. It was established that silver atoms occupy statistically crystallographic positions of lithium atoms. The incorporation of silver atoms is accompanied by a noticeable increase in parameter c of the LiCu{sub 2}O{sub 2} rhombic unit cell, a slight increase in parameter a, and a slight decrease in parameter b.

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

    PubMed

    Barillo, David J; Marx, David E

    2014-12-01

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

  19. Tailoring silver nanoparticle construction using dendrimer templated silica networks

    NASA Astrophysics Data System (ADS)

    Liu, Xiaojun; Kakkar, Ashok

    2008-06-01

    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.

  20. Hydrologic data for Block Island, Rhode Island

    USGS Publications Warehouse

    Burns, Emily

    1993-01-01

    This report was compiled as part of a study to assess the hydrogeology and the quality and quantity of fresh ground water on Block Island, Rhode Island. Hydrologic data were collected on Block Island during 1988-91. The data are pre- sented in illustrations and tables. Data collec- ted include precipitation, surfae-water, ground- water, lithologic, and well-construction and dis- charge information. Precipitation data include total monthly precipitation values from 11 rain gages and water-quality analyses of 14 precipi- tation samples from one station. Surface-water data include water-level measurements at 12 ponds, water-quality data for five ponds, and field specific-conductance measurements at 56 surface- water sites (streams, ponds, and springs). Ground- water data include water-level measurements at 159 wells, water-quality data at 150 wells, and field specific-conductance data at 52 wells. Lithologic logs for 375 wells and test borings, and construc- tion and location data for 570 wells, springs, and test borings are included. In addition, the data set contains data on water quality of water samples, collected by the Rhode Island Department of Health during 1976-91, from Fresh and Sands Ponds and from wells at the Block Island Water Company well field north of Sands Pond.

  1. Fluorescence enhancement on silver nanostructures: studies of components of ribosomal translation in vitro

    NASA Astrophysics Data System (ADS)

    Mandecki, Wlodek; Bharill, Shashank; Borejdo, Julian; Cabral, Diana; Cooperman, Barry S.; Farrell, Ian; Fetter, Linus; Goldman, Emanuel; Gryczynski, Zygmunt; Jakubowski, Hieronim; Liu, Hanqing; Luchowski, Rafal; Matveeva, Evgenia; Pan, Dongli; Qin, Haiou; Tennant, Donald; Gryczynski, Ignacy

    2008-02-01

    Metallic particles, silver in particular, can significantly enhance the fluorescence of dye molecules in the immediate vicinity (5-20 nm) of the particle. This magnifying effect can be theoretically explained/predicted by considering the change of photonic mode density near the fluorophore due to coupling to the conducting surface. We are using this method to observe fluorescence from a single ribosomal particle in a project aimed at acquiring sequence information from the translating ribosome (NIH's $1000 Genome Initiative). Several quartz slides with silver nanostructures were made using electron beam lithography techniques. The structures were approximately 50 nm high silver tiles measuring 400-700 nm on the side, and were spaced differently over a total area of 1 mm x 1 mm on any given quartz slide. In a preliminary experiment, we coated this surface with the Alexa 647-labeled antibodies and collected single molecule images using the MicroTime 200 (PicoQuant) confocal system. We showed that the fluorescence intensity measured over the silver islands film was more than 100-fold higher than fluorescence from a comparable site on uncoated section of the quartz slide. No noticeable photobleaching was seen. The fluorescence lifetime was very short, about 200 ps or less (this is the resolution limit of the system). The method has great promise for investigations of biologically relevant single molecules.

  2. "Go local" island food network: using email networking to promote island foods for their health, biodiversity, and other "CHEEF" benefits.

    PubMed

    Englberger, L; Lorens, A; Pretrick, M E; Spegal, R; Falcam, I

    2010-04-01

    Dietary- and lifestyle-related diseases are problems of epidemic proportion in the Federated States of Micronesia (FSM). Public health resources to help prevent nutrition-related problems are limited. There is also concern about biodiversity, neglect of traditional staple foods, and threatened loss of traditional knowledge. A "Go Local" campaign was initiated to increase production and consumption of locally grown foods, for their Culture, Health, Environment, Economics, and Food security ("CHEEF") benefits. To provide updates and discuss local island food topics, the Island Food Community of Pohnpei launched an interagency email network in 2003. Interested members' email addresses were recorded in distribution lists, weekly/bi-weekly emails were sent and from these messages, a database was organized to record email topic details. An analysis of all emails up to July 2009 showed that membership had expanded to over 600 listed people from all FSM states, other Pacific Island countries and beyond. Information was shared on topics ranging from scientific findings of carotenoid content in local island food cultivars, to discussions on how daily habits related to island food use can be improved. Over 200 men and women, aged 22 to 80 years, contributed items, some indicating that they had shared emails to a further network at their workplace or community. In conclusion, this email network is a simple, cost-effective method to share information, create awareness, and mobilize island food promotion efforts with potential for providing health, biodiversity and other benefits of island foods to populations in the FSM and other countries.

  3. Biocompatible Silver-containing a-C:H and a-C coatings: AComparative Study

    SciTech Connect

    Endrino, Jose Luis; Allen, Matthew; Escobar Galindo, Ramon; Zhang, Hanshen; Anders, Andre; Albella, Jose Maria

    2007-04-01

    Hydrogenated diamond-like-carbon (a-C:H) and hydrogen-free amorphous carbon (a-C) coatings are known to be biocompatible and have good chemical inertness. For this reason, both of these materials are strong candidates to be used as a matrix that embeds metallic elements with antimicrobial effect. In this comparative study, we have incorporated silver into diamond-like carbon (DLC) coatings by plasma based ion implantation and deposition (PBII&D) using methane (CH4) plasma and simultaneously depositing Ag from a pulsed cathodic arc source. In addition, we have grown amorphous carbon - silver composite coatings using a dual-cathode pulsed filtered cathodic-arc (FCA) source. The silver atomic content of the deposited samples was analyzed using glow discharge optical spectroscopy (GDOES). In both cases, the arc pulse frequency of the silver cathode was adjusted in order to obtain samples with approximately 5 at.% of Ag. Surface hardness of the deposited films was analyzed using the nanoindentation technique. Cell viability for both a-C:H/Ag and a-C:/Ag samples deposited on 24-well tissue culture plates has been evaluated.

  4. Effect of fractal silver electrodes on charge collection and light distribution in semiconducting organic polymer films

    SciTech Connect

    Chamousis, RL; Chang, LL; Watterson, WJ; Montgomery, RD; Taylor, RP; Moule, AJ; Shaheen, SE; Ilan, B; van de Lagemaat, J; Osterloh, FE

    2014-08-21

    Living organisms use fractal structures to optimize material and energy transport across regions of differing size scales. Here we test the effect of fractal silver electrodes on light distribution and charge collection in organic semiconducting polymer films made of P3HT and PCBM. The semiconducting polymers were deposited onto electrochemically grown fractal silver structures (5000 nm x 500 nm; fractal dimension of 1.71) with PEDOT:PSS as hole-selective interlayer. The fractal silver electrodes appear black due to increased horizontal light scattering, which is shown to improve light absorption in the polymer. According to surface photovoltage spectroscopy, fractal silver electrodes outperform the flat electrodes when the BHJ film thickness is large (>400 nm, 0.4 V photovoltage). Photocurrents of up to 200 microamperes cm(-2) are generated from the bulk heterojunction (BHJ) photoelectrodes under 435 nm LED (10-20 mW cm(-2)) illumination in acetonitrile solution containing 0.005 M ferrocenium hexafluorophosphate as the electron acceptor. The low IPCE values (0.3-0.7%) are due to slow electron transfer to ferrocenium ion and due to shunting along the large metal-polymer interface. Overall, this work provides an initial assessment of the potential of fractal electrodes for organic photovoltaic cells.

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

    PubMed Central

    2011-01-01

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

  6. Pine Island Bay

    Atmospheric Science Data Center

    2013-04-16

    ... article title:  Birth of a Large Iceberg in Pine Island Bay, Antarctica     View ... iceberg (42 kilometers x 17 kilometers) broke off Pine Island Glacier, West Antarctica (75°S latitude, 102°W longitude) sometime ...

  7. Island Natural Science School.

    ERIC Educational Resources Information Center

    Toronto Board of Education (Ontario).

    Prepared for students in grade six attending the Island Natural Science School, Toronto, Ontario, Canada, this booklet offers information and suggests activities in the areas of ecology, conservation, natural resources, and outdoor recreation. Introductory material describes island lore, its formation and significant features, followed by units of…

  8. Back to Treasure Island

    ERIC Educational Resources Information Center

    Shriki, Atara

    2011-01-01

    In this article, the author presents the Treasure Island problem and some inquiry activities derived from the problem. Trying to find where pirates buried a treasure leads to a surprising answer, multiple solutions, and a discussion of problem solving. The Treasure Island problem is an example of an inquiry activity that can be implemented in…

  9. Islands in a Storm.

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1995-01-01

    Smith Island in the Chesapeake Bay is actually a group of three islands: Ewell, Rhodes Point, and Tylerton. Dwindling enrollment jeopardizes the community's two schools that contain grades one through seven. The school board believes they can give the sixth and seventh graders at Ewell and Tylerton a better education on the mainland. (MLF)

  10. Basaltic island sand provenance

    SciTech Connect

    Marsaglia, K.M. . Dept. of Geological Sciences)

    1992-01-01

    The Hawaiian Islands are an ideal location to study basaltic sand provenance in that they are a series of progressively older basaltic shield volcanoes with arid to humid microclimates. Sixty-two sand samples were collected from beaches on the islands of Hawaii, Maui, Oahu and Kauai and petrographically analyzed. The major sand components are calcareous bioclasts, volcanic lithic fragments, and monomineralic grains of dense minerals and plagioclase. Proportions of these components vary from island to island, with bioclastic end members being more prevalent on older islands exhibiting well-developed fringing reef systems and volcanic end members more prevalent on younger, volcanically active islands. Climatic variations across the island of Hawaii are reflected in the percentage of weathered detritus, which is greater on the wetter, northern side of the island. The groundmass of glassy, basaltic lithics is predominantly black tachylite, with lesser brown sideromelane; microlitic and lathwork textures are more common than holohyaline vitric textures. Other common basaltic volcanic lithic fragments are holocrystalline aggregates of silt-sized pyroxene or olivine, opaque minerals and plagioclase. Sands derived from alkalic lavas are texturally and compositionally indistinguishable from sands derived from tholeiitic lavas. Although Hawaiian basaltic sands overlap in composition with magmatic arc-derived sands in terms of their relative QFL, QmPK and LmLvLs percentages, they are dissimilar in that they lack felsic components and are more enriched in lathwork volcanic lithic fragments, holocrystalline volcanic lithic fragments, and dense minerals.

  11. Marine and Island Ecology.

    ERIC Educational Resources Information Center

    Stephens, Lawrence J.; And Others

    1988-01-01

    Describes an ecology course which provides students with an opportunity to observe aquatic and terrestrial life in the Bahamas. States that students learn scientific methodology by measuring physical and chemical aspects of the island habitats. Provides information on the island, course description and objectives, transportation, facilities, and…

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

    SciTech Connect

    Liu Suwen; Wehmschulte, Rudolf J. . E-mail: rwehmsch@fit.edu; Lian Guoda; Burba, Christopher M.

    2006-03-15

    Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 {mu}m, some even more than 100 {mu}m, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the 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)

  13. Toxicity of various silver nanoparticles compared to silver ions in Daphnia magna

    PubMed Central

    2012-01-01

    Background To better understand the potential ecotoxicological impacts of silver nanoparticles released into freshwater environments, the Daphnia magna 48-hour immobilization test was used. Methods The toxicities of silver nitrate, two types of colloidal silver nanoparticles, and a suspension of silver nanoparticles were assessed and compared using standard OECD guidelines. Also, the swimming behavior and visible uptake of the nanoparticles by Daphnia were investigated and compared. The particle suspension and colloids used in the toxicity tests were well-characterized. Results The results obtained from the exposure studies showed that the toxicity of all the silver species tested was dose and composition dependent. Plus, the silver nanoparticle powders subsequently suspended in the exposure water were much less toxic than the previously prepared silver nanoparticle colloids, whereas the colloidal silver nanoparticles and AgNO3 were almost similar in terms of mortality. The silver nanoparticles were ingested by the Daphnia and accumulated under the carapace, on the external body surface, and connected to the appendages. All the silver species in this study caused abnormal swimming by the D. magna. Conclusion According to the present results, silver nanoparticles should be classified according to GHS (Globally Harmonized System of classification and labeling of chemicals) as "category acute 1" to Daphnia neonates, suggesting that the release of nanosilver into the environment should be carefully considered. PMID:22472056

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Holtz, R. D.; Souza Filho, A. G.; Brocchi, M.; Martins, D.; Durán, N.; Alves, O. L.

    2010-05-01

    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.

  16. Silver disinfection in water distribution systems

    NASA Astrophysics Data System (ADS)

    Silvestry Rodriguez, Nadia

    Silver was evaluated as disinfectant to maintain water quality in water distribution system. It was used to inhibit growth of two opportunistic bacteria in planktonik form and in biofilm formation in Robbins devices with stainless steel and PVC surfaces. The results of this work show that silver is a potential secondary disinfectant to be used in water distribution systems.

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

    ERIC Educational Resources Information Center

    Twigg, Carol A.

    2011-01-01

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

  18. A silver ion water sterilization system

    NASA Technical Reports Server (NTRS)

    Parry, E. P.

    1971-01-01

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

  19. Silver Trees: Chemistry on a TEM Grid

    EPA Science Inventory

    The copper/carbon substrate of a TEM grid reacted with aqueous silver nitrate solution within minutes to yield spectacular tree-like silver dendrites, without using any added capping or reducing reagents. These results demonstrate a facile, aqueous, room temperature synthesis of...

  20. Intravesical silver nitrate for refractory hemorrhagic cystitis

    PubMed Central

    Montgomery, Brian D.; Boorjian, Stephen A.; Ziegelmann, Matthew J.; Joyce, Daniel D.; Linder, Brian J.

    2016-01-01

    Objective Hemorrhagic cystitis is a challenging clinical entity with limited evidence available to guide treatment. The use of intravesical silver nitrate has been reported, though supporting literature is sparse. Here, we sought to assess outcomes of patients treated with intravesical silver nitrate for refractory hemorrhagic cystitis. Material and methods We identified nine patients with refractory hemorrhagic cystitis treated at our institution with intravesical silver nitrate between 2000–2015. All patients had failed previous continuous bladder irrigation with normal saline and clot evacuation. Treatment success was defined as requiring no additional therapy beyond normal saline irrigation after silver nitrate instillation prior to hospital discharge. Results Median patient age was 80 years (IQR 73, 82). Radiation was the most common etiology for hemorrhagic cystitis 89% (8/9). Two patients underwent high dose (0.1%–0.4%) silver nitrate under anesthesia, while the remaining seven were treated with doses from 0.01% to 0.1% via continuous bladder irrigation for a median of 3 days (range 2–4). All nine patients (100%) had persistent hematuria despite intravesical silver nitrate therapy, requiring additional interventions and red blood cell transfusion during the hospitalization. There were no identified complications related to intravesical silver nitrate instillation. Conclusion Although well tolerated, we found that intravesical silver nitrate was ineffective for bleeding control, suggesting a limited role for this agent in the management of patients with hemorrhagic cystitis.

  1. Intravesical silver nitrate for refractory hemorrhagic cystitis

    PubMed Central

    Montgomery, Brian D.; Boorjian, Stephen A.; Ziegelmann, Matthew J.; Joyce, Daniel D.; Linder, Brian J.

    2016-01-01

    Objective Hemorrhagic cystitis is a challenging clinical entity with limited evidence available to guide treatment. The use of intravesical silver nitrate has been reported, though supporting literature is sparse. Here, we sought to assess outcomes of patients treated with intravesical silver nitrate for refractory hemorrhagic cystitis. Material and methods We identified nine patients with refractory hemorrhagic cystitis treated at our institution with intravesical silver nitrate between 2000–2015. All patients had failed previous continuous bladder irrigation with normal saline and clot evacuation. Treatment success was defined as requiring no additional therapy beyond normal saline irrigation after silver nitrate instillation prior to hospital discharge. Results Median patient age was 80 years (IQR 73, 82). Radiation was the most common etiology for hemorrhagic cystitis 89% (8/9). Two patients underwent high dose (0.1%–0.4%) silver nitrate under anesthesia, while the remaining seven were treated with doses from 0.01% to 0.1% via continuous bladder irrigation for a median of 3 days (range 2–4). All nine patients (100%) had persistent hematuria despite intravesical silver nitrate therapy, requiring additional interventions and red blood cell transfusion during the hospitalization. There were no identified complications related to intravesical silver nitrate instillation. Conclusion Although well tolerated, we found that intravesical silver nitrate was ineffective for bleeding control, suggesting a limited role for this agent in the management of patients with hemorrhagic cystitis. PMID:27635296

  2. [Clinical study of Silver Lubricath Foley catheter].

    PubMed

    Nakada, J; Kawahara, M; Onodera, S; Oishi, Y

    1996-06-01

    We evaluated the Silver Lubricath Foley Catheter (silver catheter) coated with silver and hydrogel developed to prevent urinary infection, in comparison with the silicone-coated catheter (silicone catheter). Twelve patients ranging from 71 to 95 years of age (median age, 82 years) were catheterized and the 16 of 18F catheter was replaced every 2 weeks. They answered a questionnaire which included inquiry about the treatment with urinary catheter. Because of less leakage and discomfort to the urethra, the silver catheter had advantages over the silicone catheter. The risk of bacteriuria after 14 days of catheterization was not significantly different between the two types of catheter. Scanning electron microscopic analysis revealed that bacterial biofilm developed on the inner surface of both catheters after 14 days of catheterization. On the other hand, the amount of bacterial biofilm on the outer surface of a silver catheter was less than that on the outer surface of a silicone catheter.

  3. Recovery of silver from radiographic fixer.

    PubMed

    Goshima, T; Hori, K; Yamamoto, A

    1994-06-01

    This study examined the silver content of 10 brands of dental x-ray film that are commercially available in Japan. Kodak Ektaspeed EP-22 (Eastman Kodak Co., Rochester, N.Y.) was found to have the highest silver content, and SD 100 Gold X-ray Film (San Dental Co., Ltd., Tokyo, Japan) had the lowest content of silver. Electrolysis and ion exchange were used as the methods of silver recovery from films in the general dental office. Ion exchange was more than 99% efficient in silver recovery from the radiographic fixer and resulted in an 80% reduction in biochemical oxygen demand and a 95% reduction in chemical oxygen demand. However, these levels and other environmental pollutants were still above the limits set by the Japanese Pollutant Control law. PMID:8065739

  4. Silver manganese oxide electrodes for lithium batteries

    DOEpatents

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

    2006-05-09

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

  5. Silver Doped Titanium Dioxide Humidity Sensor

    NASA Astrophysics Data System (ADS)

    Hooshiar Zare, Ali; Mohammadi, Somayye

    2011-02-01

    The effect of silver doping on the sensitivity, dynamic range and the response time of a titanium dioxide-based resistive humidity sensor is studied. Sample pallets were prepared by sintering the dry pressed samples at 900°C in air. Silver was added to the ceramic raw material in the form of AgNO3 which was decomposed during the sintering process. Large area silver electrodes were deposited on the sintered disks by paste printing. The resistance and the response time of the various pallets containing different additive levels were measured at relative humidity range of 4-100%. Silver doping, substantially increased the sensitivity to the ambient humidity. Moreover, it resulted in faster responses; the response time of the silver added pallets were about four times shorter than the pure ones.

  6. Synthesis of silver nanoparticle and its application.

    PubMed

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

    2015-11-01

    In this work, silver nanoparticles have been synthesized by wet chemical technique, green synthesis and microbial methods. Silver nitrate (10(-3)M) was used with aqueous extract to produce silver nanoparticles. From the results it was observed that the yield of nanoparticles was high in green synthesis. The size of the silver nanoparticles was determined from Scanning Electron Microscope analysis (SEM). Fourier Transform Infrared spectroscopy (FTIR) was carried out to determine the presence of biomolecules in them. Its cytotoxic effect was studied in cancerous cell line and normal cell line. MTT assay was done to test its optimal concentration and efficacy which gives valuable information for the use of silver nanoparticles for future cancer therapy. PMID:25866204

  7. Synthesis of silver nanoparticle and its application.

    PubMed

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

    2015-11-01

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

  8. Fabrication of silver nanorods embedded in PDMS film and its application for strain sensing

    NASA Astrophysics Data System (ADS)

    Goel, Pratibha; Singh, J. P.

    2014-11-01

    Highly reflective and surface conductive strain gauges have been prepared by embedding the silver nanorods (AgNRs) into polydimethylsiloxane (PDMS). Thermal curing of PDMS on AgNRs grown Si wafer leads to a flexible, reflective and conductive silver surface. The reflectance of the as prepared films were observed to be 60% with a low value of sheet resistance. The reflectance of the film was able to be tuned from 60% to 15% in the visible region. The fabrication of a parallel plate capacitor strain sensor from AgNRs embedded PDMS, and tuning of the capacitance with respect to the applied strain, leads to a gauge factor of ~1. These mechanically tunable AgNRs/PDMS films demonstrate potential application as a strain sensor.

  9. Remobilisation of silver and silver sulphide nanoparticles in soils.

    PubMed

    Navarro, Divina A; Kirby, Jason K; McLaughlin, Mike J; Waddington, Lynne; Kookana, Rai S

    2014-10-01

    Manufactured nanoparticles (NPs) present in consumer products could enter soils through re-use of biosolids. Among these NPs are those based on silver (Ag), which are found sulphidised (e.g. silver sulphide, Ag2S) in biosolids. Herein, our aim was to examine the release of retained Ag(0) and Ag2S NPs in soils and biosolids as facilitated by environmentally and agriculturally relevant ligands. Under natural soil conditions, exemplified by potassium nitrate and humic acid experiments, release of Ag retained in soil was limited. The highest total Ag release was facilitated by ligands that simulated root exudates (citrate) or fertilisers (thiosulphate). Released Ag was predominantly present in the colloidal phase (>3 kDa-< 0.45 μm); intact NPs only identified in Ag2S-NP extracts. For biosolids containing nanoparticulate-Ag-S, release was also enhanced by thiosulphate, though mostly as colloidal-Ag - not intact NPs. These results suggest that exposure to NPs as a result of its release from soils or biosolids will be low. PMID:25014017

  10. Remobilisation of silver and silver sulphide nanoparticles in soils.

    PubMed

    Navarro, Divina A; Kirby, Jason K; McLaughlin, Mike J; Waddington, Lynne; Kookana, Rai S

    2014-10-01

    Manufactured nanoparticles (NPs) present in consumer products could enter soils through re-use of biosolids. Among these NPs are those based on silver (Ag), which are found sulphidised (e.g. silver sulphide, Ag2S) in biosolids. Herein, our aim was to examine the release of retained Ag(0) and Ag2S NPs in soils and biosolids as facilitated by environmentally and agriculturally relevant ligands. Under natural soil conditions, exemplified by potassium nitrate and humic acid experiments, release of Ag retained in soil was limited. The highest total Ag release was facilitated by ligands that simulated root exudates (citrate) or fertilisers (thiosulphate). Released Ag was predominantly present in the colloidal phase (>3 kDa-< 0.45 μm); intact NPs only identified in Ag2S-NP extracts. For biosolids containing nanoparticulate-Ag-S, release was also enhanced by thiosulphate, though mostly as colloidal-Ag - not intact NPs. These results suggest that exposure to NPs as a result of its release from soils or biosolids will be low.

  11. Ober's Island: The Mallard Ober's Island, One of the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Ober's Island: The Mallard - Ober's Island, One of the Review Islands on Rainy Lake, bounded on the south by The Hawk Island and on the north by The Crow Island. These islands are located seven miles east of Ranier, Minnesota, three miles west of Voyageur National Park, and one mile south of the international border of the United States of America and Canada. The legal description of Mallard Island is Lot 6, Section 19, T-17-N, R-22-W, Koochiching County, Minnesota, Ranier, Koochiching County, MN

  12. 21 CFR 872.3840 - Endodontic silver point.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Endodontic silver point. 872.3840 Section 872.3840...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3840 Endodontic silver point. (a) Identification. An endodontic silver point is a device made of silver intended for use during endodontic therapy...

  13. 21 CFR 872.3840 - Endodontic silver point.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Endodontic silver point. 872.3840 Section 872.3840...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3840 Endodontic silver point. (a) Identification. An endodontic silver point is a device made of silver intended for use during endodontic therapy...

  14. 21 CFR 872.3840 - Endodontic silver point.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Endodontic silver point. 872.3840 Section 872.3840...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3840 Endodontic silver point. (a) Identification. An endodontic silver point is a device made of silver intended for use during endodontic therapy...

  15. 21 CFR 872.3840 - Endodontic silver point.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Endodontic silver point. 872.3840 Section 872.3840...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3840 Endodontic silver point. (a) Identification. An endodontic silver point is a device made of silver intended for use during endodontic therapy...

  16. Effects of Nano Silver Oxide and Silver Ions on Growth of Vigna radiata.

    PubMed

    Singh, Divya; Kumar, Arun

    2015-09-01

    Transformation of silver oxide nanoparticles (nano-Ag2O) to silver nanoparticles (nano-Ag) and silver ions in environment is possible which might pose toxicity to plants and other species. The objective of this study was to study effects of nano-Ag2O and silver ions on growth of Mung bean (Vigna radiata) seedlings. V. radiata seeds were exposed to nano-Ag2O and silver ions (concentration range: 4.3 × 10(-7), 4.3 × 10(-6), 4.3 × 10(-5), 4.3 × 10(-4), and 4.3 × 10(-3) mol/L) for 6 days. Root length, shoot length and dry weight of seedlings were found to decrease due to exposure of nano-Ag2O and silver ions. These findings indicate silver ions to be more toxic to V. radiata seeds than nano-Ag2O. Silver content in seedlings was found to increase with increasing concentrations of nano-Ag2O and silver ions. Overall, findings of the present study add to the existing knowledge of phytotoxicity of silver-based nanoparticles of different chemical compositions to V. radiata seeds and need to be considered during use of nanoparticles-contaminated water for irrigation purposes. PMID:26155963

  17. Piezoelectric nanogenerator based on zinc oxide nanorods grown on textile cotton fabric

    NASA Astrophysics Data System (ADS)

    Khan, Azam; Ali Abbasi, Mazhar; Hussain, Mushtaque; Hussain Ibupoto, Zafar; Wissting, Jonas; Nur, Omer; Willander, Magnus

    2012-11-01

    This investigation explores piezoelectricity generation from ZnO nanorods, which were grown on silver coated textile cotton fabrics using the low temperature aqueous chemical growth method. The morphology and crystal structure studies were carried out by x-ray diffraction, scanning electron microscopic and high resolution transmission electron microscopic techniques, respectively. ZnO nanorods were highly dense, well aligned, uniform in spatial distribution and exhibited good crystal quality. The generation of piezoelectricity from fabricated ZnO nanorods grown on textile cotton fabrics was measured using contact mode atomic force microscopy. The average output voltage generated from ZnO nanorods was measured to be around 9.5 mV. This investigation is an important achievement regarding the piezoelectricity generation on textile cotton fabric substrate. The fabrication of this device provides an alternative approach for a flexible substrate to develop devices for energy harvesting and optoelectronic technology on textiles.

  18. Cognitive Constraints and Island Effects

    ERIC Educational Resources Information Center

    Hofmeister, Philip; Sag, Ivan A.

    2010-01-01

    Competence-based theories of island effects play a central role in generative grammar, yet the graded nature of many syntactic islands has never been properly accounted for. Categorical syntactic accounts of island effects have persisted in spite of a wealth of data suggesting that island effects are not categorical in nature and that…

  19. Rhabdomyosarcoma in a Silver Carp.

    PubMed

    Rezaie, Annahita; Mousavi, Seyed Mohammad; Ansari, Mahshid Bagherzadeh

    2016-06-01

    Rhabdomyosarcoma is a primitive neoplasm that originates from skeletal muscle progenitor cells. In a routine inspection of a cyprinid farm in southwestern Iran, an approximately 2-year-old female Silver Carp was observed to have a raised mass located on the dorsolateral surface just caudal to the head. Macroscopic examination revealed a firm irregular fleshy pink mass (5 × 4 cm, depth = 3 cm) that appeared to arise from the subcutaneous musculature. Histologic sections were prepared using routine methods and separate sections were stained with hematoxylin-eosin and Massons' trichrome. Microscopically, the tumor mass was composed of spindle cells that were densely packed and arranged in long interwoven bundles. The nuclei were vesicular and oval to elongated or cigar-shaped. Nuclear pleomorphism and multinucleate tumor giant cells were clearly evident. The neoplastic cell cytoplasm was eosinophilic with indistinct cell margins, and clear cross striations were observed in fibrils. The striated fibrils stained diffusely red with Masson's trichrome. This account represents the first reported occurrence of rhabdomyosarcoma in Silver Carp Hypophthalmichthys molitrix. Received July 10, 2015; accepted February 4, 2016.

  20. Rhabdomyosarcoma in a Silver Carp.

    PubMed

    Rezaie, Annahita; Mousavi, Seyed Mohammad; Ansari, Mahshid Bagherzadeh

    2016-06-01

    Rhabdomyosarcoma is a primitive neoplasm that originates from skeletal muscle progenitor cells. In a routine inspection of a cyprinid farm in southwestern Iran, an approximately 2-year-old female Silver Carp was observed to have a raised mass located on the dorsolateral surface just caudal to the head. Macroscopic examination revealed a firm irregular fleshy pink mass (5 × 4 cm, depth = 3 cm) that appeared to arise from the subcutaneous musculature. Histologic sections were prepared using routine methods and separate sections were stained with hematoxylin-eosin and Massons' trichrome. Microscopically, the tumor mass was composed of spindle cells that were densely packed and arranged in long interwoven bundles. The nuclei were vesicular and oval to elongated or cigar-shaped. Nuclear pleomorphism and multinucleate tumor giant cells were clearly evident. The neoplastic cell cytoplasm was eosinophilic with indistinct cell margins, and clear cross striations were observed in fibrils. The striated fibrils stained diffusely red with Masson's trichrome. This account represents the first reported occurrence of rhabdomyosarcoma in Silver Carp Hypophthalmichthys molitrix. Received July 10, 2015; accepted February 4, 2016. PMID:27229885

  1. Structural evolution of platinum thin films grown by atomic layer deposition

    SciTech Connect

    Geyer, Scott M.; Methaapanon, Rungthiwa; Bent, Stacey; Johnson, Richard; Clemens, Bruce; Brennan, Sean; Toney, Mike F.

    2014-08-14

    The structural properties of Pt films grown by atomic layer deposition (ALD) are investigated with synchrotron based x-ray scattering and x-ray diffraction techniques. Using grazing incidence small angle scattering, we measure the lateral growth rate of the Pt islands to be 1.0 Å/cycle. High resolution x-ray diffraction reveals that the in-plane strain of the Pt lattice undergoes a transition from compressive strain to tensile strain when the individual islands coalescence into a continuous film. This transition to tensile strain is attributed to the lateral expansion that occurs when neighboring islands merge to reduce their surface energy. Using 2D grazing incidence x-ray diffraction, we show that the lattice orientation becomes more (111) oriented during deposition, with a sharp transition occurring during coalescence. Pt ALD performed at a lower deposition temperature (250 °C) is shown to result in significantly more randomly oriented grains.

  2. Hydrophobicity of silver surfaces with microparticle geometry

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  3. Lost island found

    NASA Astrophysics Data System (ADS)

    An abandoned ll-by-5-km kidney-shaped chunk of freshwater ice, used as a research station for 25 years, was rediscovered after the National Oceanic and Atmospheric Administration (NOAA) lost track of the island for 6 months. The recent find may foreshadow another loss, however: The island is drifting through the Greenland Sea and into the North Atlantic where it should melt within several months and d u m p its cargo of oil drums, equipment, and a wrecked plane into the ocean.Known as Fletcher's Ice Island—after Joseph O. Fletcher, a member of the first team of researchers to inhabit the island and a recently retired NOAA climate researcher—the ice chunk has already melted to a third of its original 49 m thickness. A pilot flying over the area to measure annual pollution buildup in the Arctic located the drifting island 242 km from the North Pole near the International Date Line.

  4. Island Watershed Activity.

    ERIC Educational Resources Information Center

    Benson, Rod

    2003-01-01

    Describes a 90-minute "Island Watershed" activity to help earth science students understand the concept of the water cycle. Introduces a surface waters unit appropriate for students in grades 7-10. Includes watershed project guidelines. (Author/KHR)

  5. Small islands adrift

    NASA Astrophysics Data System (ADS)

    Petherick, Anna

    2015-07-01

    With the charismatic former president of the Maldives, Mohamed Nasheed, behind bars on a widely derided terrorism charge, Anna Petherick asks whether small island states can really make themselves heard in Paris.

  6. Islands, resettlement and adaptation

    NASA Astrophysics Data System (ADS)

    Barnett, Jon; O'Neill, Saffron J.

    2012-01-01

    Resettlement of people living on islands in anticipation of climate impacts risks maladaptation, but some forms of population movement carry fewer risks and larger rewards in terms of adapting to climate change.

  7. Shape selectivity using ionic liquids for the preparation of silver and silver sulphide nanomaterials.

    PubMed

    Patil, Amol B; Bhanage, Bhalchandra M

    2014-02-21

    Electrodeposition of silver and silver sulphide was carried out from two protic ionic liquids. A change of the anion moiety of ionic liquid was found to bring about significant changes in the morphology of the nanocrystalline silver and silver sulphide deposits obtained. Effects of various parameters like deposition overpotential, change of the substrate, deposition time, etc. on the particle size and shape were studied. It was found that a change of anions of the ionic liquid from acetate to nitrate results in a wide difference in the morphology of the deposits obtained. Acetate containing ionic liquids result in globular nanocrystalline deposits whereas nitrate containing ionic liquids result in flat plates or sheets of silver deposits. Similar results were obtained for silver sulphide nanocrystals. PMID:24394372

  8. Melville Island, Australia

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Melville Island, just off the coast of Darwin, Northern Territory, Australia (11.5S, 131.0E) is a sparsely inhabited tropical island with heavy woodland concentrations. The widespread and prominant smoke plumes were most likely set to renew pasture under open canopy woodland. Soil erosion is almost non- existant as can be seen by the clear and clean river flow. The offshore sediments are coastal current borne deposits from King Sound to the west.

  9. Macroporous silver monoliths using a simple surfactant

    NASA Astrophysics Data System (ADS)

    Khan, Farid; Eswaramoorthy, Muthusamy; Rao, C. N. R.

    2007-01-01

    An elegant method to synthesize porous silver monoliths using a simple surfactant cum reductant, Triton X-114, as the sacrificial template is described. The gel forming property of the surfactant with silver nitrate is utilized to make the porous framework. The monoliths obtained with a mixture of Triton X-114 and dextran have also been examined. A significant improvement in the pore structure was observed when Triton X-114 was used along with Ludox silica sol, followed by calcination and HF treatment. The presence of interparticle pores in the 20-25 nm range on the macroporous silver framework suggests the role of silica spheres in the nanopore formation.

  10. Atomistic potentials for palladium-silver hydrides

    NASA Astrophysics Data System (ADS)

    Hale, L. M.; Wong, B. M.; Zimmerman, J. A.; Zhou, X. W.

    2013-06-01

    New embedded-atom method potentials for the ternary palladium-silver-hydrogen system are developed by extending a previously developed palladium-hydrogen potential. The ternary potentials accurately capture the heat of mixing and structural properties associated with solid solution alloys of palladium-silver. Stable hydrides are produced with properties that smoothly transition across the compositions. Additions of silver to palladium are predicted to alter the properties of the hydrides by decreasing the miscibility gap and increasing the likelihood of hydrogen atoms occupying tetrahedral interstitial sites over octahedral interstitial sites.

  11. Silver-Russell Syndrome: A Case Report

    PubMed Central

    Kumar, Sunil; Jain, AP; Agrawal, Sachin; Chandran, Sindu

    2008-01-01

    A 15-year-old male boy with hemihypertrophy (left side) of the body was admitted in the hospital with the history of repeated attacks of convulsion. The patient was diagnosed as Silver-Russell syndrome on clinical ground. Silver-Russell syndrome (SRS) is a very rare genetic disorder that appears no later than early childhood. This is usually characterized by asymmetry in the size of the two halves or other parts of the body. Silver-Russell Syndrome occurs mostly in isolated cases because of sporadic genetic changes (mutations) for no apparent reason. For lack of facilities we were not able to do genetic study. PMID:18992170

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  14. Alkyne-azide cycloaddition catalyzed by silver chloride and "abnormal" silver N-heterocyclic carbene complex.

    PubMed

    Ortega-Arizmendi, Aldo I; Aldeco-Pérez, Eugenia; Cuevas-Yañez, Erick

    2013-01-01

    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. PMID:24307866

  15. Hug-like island growth of Ge on strained vicinal Si(111) surfaces

    NASA Astrophysics Data System (ADS)

    Persichetti, L.; Menditto, R.; Sgarlata, A.; Fanfoni, M.; Balzarotti, A.

    2011-10-01

    We examine the structure and the evolution of Ge islands epitaxially grown on vicinal Si(111) surfaces by scanning tunneling microscopy. Contrary to what is observed on the singular surface, three-dimensional Ge nanoislands form directly through the elastic relaxation of step-edge protrusions during the unstable step-flow growth. As the substrate misorientation is increased, the islands undergo a shape transformation which is driven by surface energy minimization and controlled by the miscut angle. Using finite element simulations, we show that the dynamics of islanding observed in the experiment results from the anisotropy of the strain relaxation.

  16. Copper vapor-assisted growth of hexagonal graphene domains on silica islands

    NASA Astrophysics Data System (ADS)

    Li, Jun; Shen, Chengmin; Que, Yande; Tian, Yuan; Jiang, Lili; Bao, Deliang; Wang, Yeliang; Du, Shixuan; Gao, Hong-Jun

    2016-07-01

    Silica (SiO2) islands with a dendritic structure were prepared on polycrystalline copper foil, using silane (SiH4) as a precursor, by annealing at high temperature. Assisted by copper vapor from bare sections of the foil, single-layer hexagonal graphene domains were grown directly on the SiO2 islands by chemical vapor deposition. Scanning electron microscopy, atomic force microscopy, Raman spectra, and X-ray photoelectron spectroscopy confirm that hexagonal graphene domains, each measuring several microns, were synthesized on the silica islands.

  17. Harvesting microalgae grown on wastewater.

    PubMed

    Udom, Innocent; Zaribaf, Behnaz H; Halfhide, Trina; Gillie, Benjamin; Dalrymple, Omatoyo; Zhang, Qiong; Ergas, Sarina J

    2013-07-01

    The costs and life cycle impacts of microalgae harvesting for biofuel production were investigated. Algae were grown in semi-continuous culture in pilot-scale photobioreactors under natural light with anaerobic digester centrate as the feed source. Algae suspensions were collected and the optimal coagulant dosages for metal salts (alum, ferric chloride), cationic polymer (Zetag 8819), anionic polymer (E-38) and natural coagulants (Moringa Oleifera and Opuntia ficus-indica cactus) were determined using jar tests. The relative dewaterability of the algae cake was estimated by centrifugation. Alum, ferric chloride and cationic polymer could all achieve >91% algae recovery at optimal dosages. Life cycle assessment (LCA) and cost analysis results revealed that cationic polymer had the lowest cost but the highest environmental impacts, while ferric chloride had the highest cost and lowest environmental impacts. Based on the LCA results, belt presses are the recommended algae dewatering technology prior to oil extraction.

  18. Harvesting microalgae grown on wastewater.

    PubMed

    Udom, Innocent; Zaribaf, Behnaz H; Halfhide, Trina; Gillie, Benjamin; Dalrymple, Omatoyo; Zhang, Qiong; Ergas, Sarina J

    2013-07-01

    The costs and life cycle impacts of microalgae harvesting for biofuel production were investigated. Algae were grown in semi-continuous culture in pilot-scale photobioreactors under natural light with anaerobic digester centrate as the feed source. Algae suspensions were collected and the optimal coagulant dosages for metal salts (alum, ferric chloride), cationic polymer (Zetag 8819), anionic polymer (E-38) and natural coagulants (Moringa Oleifera and Opuntia ficus-indica cactus) were determined using jar tests. The relative dewaterability of the algae cake was estimated by centrifugation. Alum, ferric chloride and cationic polymer could all achieve >91% algae recovery at optimal dosages. Life cycle assessment (LCA) and cost analysis results revealed that cationic polymer had the lowest cost but the highest environmental impacts, while ferric chloride had the highest cost and lowest environmental impacts. Based on the LCA results, belt presses are the recommended algae dewatering technology prior to oil extraction. PMID:23648758

  19. AgBiS2 single crystal grown using slow cooling method and its characterization

    NASA Astrophysics Data System (ADS)

    Nakamura, Masaru; Nakamura, Hiroaki; Ohsawa, Takeo; Imura, Masataka; Shimamura, Kiyoshi; Ohashi, Naoki

    2015-02-01

    Silver bismuth sulfide (AgBiS2) single crystal was successfully grown using the slow cooling method. Characterization of a grown crystal using power X-ray diffraction (XRD) revealed a single AgBiS2 phase and a cubic structure with lattice parameter a=5.641 Å. The crystal was found to have a high-temperature phase with a cubic structure. XRD measurement and composition analysis showed that the stoichiometric composition of the AgBiS2 was equivalent to the congruent melt composition. The grown AgBiS2 crystal was confirmed to be single crystal by observing the Laue X-ray backscattering pattern. Differential thermal analysis showed that the melting point of the AgBiS2 was 805 °C. The grown crystal had n-type conductivity, a carrier concentration of 2.6×1018 cm-3, electrical resistivity of 2.1 Ω cm, and hole mobility of 1.1 cm2/V s at room temperature.

  20. Tuning Properties in Silver Clusters.

    PubMed

    Joshi, Chakra P; Bootharaju, Megalamane S; Bakr, Osman M

    2015-08-01

    The properties of Ag nanoclusters are not as well understood as those of their more precious Au cousins. However, a recent surge in the exploration of strategies to tune the physicochemical characteristics of Ag clusters addresses this imbalance, leading to new insights into their optical, luminescence, crystal habit, metal-core, ligand-shell, and environmental properties. In this Perspective, we provide an overview of the latest strategies along with a brief introduction of the theoretical framework necessary to understand the properties of silver nanoclusters and the basis for their tuning. The advances in cluster research and the future prospects presented in this Perspective will eventually guide the next large systematic study of nanoclusters, resulting in a single collection of data similar to the periodic table of elements. PMID:26267198

  1. Silver-hafnium braze alloy

    DOEpatents

    Stephens, Jr., John J.; Hosking, F. Michael; Yost, Frederick G.

    2003-12-16

    A binary allow braze composition has been prepared and used in a bonded article of ceramic-ceramic and ceramic-metal materials. The braze composition comprises greater than approximately 95 wt % silver, greater than approximately 2 wt % hafnium and less than approximately 4.1 wt % hafnium, and less than approximately 0.2 wt % trace elements. The binary braze alloy is used to join a ceramic material to another ceramic material or a ceramic material, such as alumina, quartz, aluminum nitride, silicon nitride, silicon carbide, and mullite, to a metal material, such as iron-based metals, cobalt-based metals, nickel-based metals, molybdenum-based metals, tungsten-based metals, niobium-based metals, and tantalum-based metals. A hermetic bonded article is obtained with a strength greater than 10,000 psi.

  2. Silicene structures on silver surfaces.

    PubMed

    Enriquez, Hanna; Vizzini, Sébastien; Kara, Abdelkader; Lalmi, Boubekeur; Oughaddou, Hamid

    2012-08-01

    In this paper we report on several structures of silicene, the analog of graphene for silicon, on the silver surfaces Ag(100), Ag(110) and Ag(111). Deposition of Si produces honeycomb structures on these surfaces. In particular, we present an extensive theoretical study of silicene on Ag(111) for which several recent experimental studies have been published. Different silicene structures were obtained only by varying the silicon coverage and/or its atomic arrangement. All the structures studied show that silicene is buckled, with a Si-Si nearest neighbor distance varying between 2.28 and 2.5 Å. Due to the buckling in the silicene sheet, the apparent (lateral) Si-Si distance can be as low as 1.89 Å. We also found that for a given coverage and symmetry, one may observe different scanning tunneling microscopy images corresponding to structures that differ by only a translation.

  3. Interpreting plasmonic response of epitaxial Ag/Si(100) island ensembles

    SciTech Connect

    Kong, Dexin; Jiang, Liying; Drucker, Jeff

    2015-12-07

    Associating features in the experimentally measured optical response of epitaxial Ag islands grown on Si(100) with the localized surface plasmon resonances (LSPRs) hosted by the Ag islands is challenging due to the variation of the Si dielectric function over the energy range under consideration. However, it is possible to conclusively identify features in the experimental spectra with LSPR modes oscillating both parallel and perpendicular to the epitaxial interface by simulating the optical response. The Abeles matrix method is used to describe the composite layered system and the Ag islands are modeled using the thin island film model developed by Bedeaux and Vlieger. By incorporating island morphology parameters determined by quantitative analysis of electron micrographs, the simulation faithfully reproduces the main features of the experimental spectra. Individually zeroing the dipoles associated with the LSPR modes enables conclusive identification of their contribution to the optical response of the composite system.

  4. Antimicrobial silver: an unprecedented anion effect.

    PubMed

    Swathy, J R; Sankar, M Udhaya; Chaudhary, Amrita; Aigal, Sahaja; Anshup; Pradeep, T

    2014-01-01

    Silver is an indispensable metal but its use has to be minimised for sustainable growth. Much of the silver lost during use is unrecoverable; an example being its use as an antimicrobial agent, a property known since ages. While developing methods to create an affordable drinking water purifier especially for the developing world, we discovered that 50 parts per billion (ppb) of Ag(+) released continuously from silver nanoparticles confined in nanoscale cages is enough to cause antimicrobial activity in conditions of normal water. Here we show that the antibacterial and antiviral activities of Ag(+) can be enhanced ~1,000 fold, selectively, in presence of carbonate ions whose concentration was maintained below the drinking water norms. The protective layers of the organisms were affected during the carbonate-assisted antimicrobial activity. It is estimated that ~1,300 tons of silver can be saved annually using this new way to enhance its antimicrobial activity. PMID:25418185

  5. Silver to Black--and Back.

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 2000

    2000-01-01

    Presents an activity that allows students to remove tarnish from silver using the reaction of tarnish with aluminum rather than the abrasion method of commercial tarnish removers. Makes suggestions for adapting the activity to an at-home investigation. (WRM)

  6. Controlling fires in silver/zinc batteries

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  7. The bactericidal effect of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ruben Morones, Jose; Elechiguerra, Jose Luis; Camacho, Alejandra; Holt, Katherine; Kouri, Juan B.; Tapia Ramírez, Jose; Yacaman, Miguel Jose

    2005-10-01

    Nanotechnology is expected to open new avenues to fight and prevent disease using atomic scale tailoring of materials. Among the most promising nanomaterials with antibacterial properties are metallic nanoparticles, which exhibit increased chemical activity due to their large surface to volume ratios and crystallographic surface structure. The study of bactericidal nanomaterials is particularly timely considering the recent increase of new resistant strains of bacteria to the most potent antibiotics. This has promoted research in the well known activity of silver ions and silver-based compounds, including silver nanoparticles. The present work studies the effect of silver nanoparticles in the range of 1 100 nm on Gram-negative bacteria using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM). Our results indicate that the bactericidal properties of the nanoparticles are size dependent, since the only nanoparticles that present a direct interaction with the bacteria preferentially have a diameter of ~1 10 nm.

  8. Realistic Silver Optical Constants for Plasmonics.

    PubMed

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

    2016-01-01

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

  9. Photocatalytic silver enhancement reaction for gravimetric immunosensors

    NASA Astrophysics Data System (ADS)

    Seo, Hyejung; Joo, Jinmyoung; Ko, Wooree; Jung, Namchul; Jeon, Sangmin

    2010-12-01

    A novel microgravimetric immunosensor has been developed using TiO2 nanoparticle-modified immunoassay and silver enhancement reaction. An antibody-conjugated TiO2 nanoparticle is bound to the AFP antigen immobilized on a quartz resonator. When the nanoparticles are exposed to UV light in a silver nitrate solution, the photocatalytic reduction of silver ions results in the formation of metallic silver onto the nanoparticles and induces a decrease in the resonance frequency. The frequency change by this photocatalytic reduction reaction is three orders of magnitude larger than the change by antigen binding alone. The efficiency of the photocatalytic reaction has been found to increase with the fraction of anatase crystallites in the nanoparticles and the concentration of the AgNO3 solution. The results highlight the potential of the photocatalytic nanoparticles for the detection of low concentrations of target molecules using gravimetric sensors.

  10. Photocatalytic silver enhancement reaction for gravimetric immunosensors.

    PubMed

    Seo, Hyejung; Joo, Jinmyoung; Ko, Wooree; Jung, Namchul; Jeon, Sangmin

    2010-12-17

    A novel microgravimetric immunosensor has been developed using TiO(2) nanoparticle-modified immunoassay and silver enhancement reaction. An antibody-conjugated TiO(2) nanoparticle is bound to the AFP antigen immobilized on a quartz resonator. When the nanoparticles are exposed to UV light in a silver nitrate solution, the photocatalytic reduction of silver ions results in the formation of metallic silver onto the nanoparticles and induces a decrease in the resonance frequency. The frequency change by this photocatalytic reduction reaction is three orders of magnitude larger than the change by antigen binding alone. The efficiency of the photocatalytic reaction has been found to increase with the fraction of anatase crystallites in the nanoparticles and the concentration of the AgNO(3) solution. The results highlight the potential of the photocatalytic nanoparticles for the detection of low concentrations of target molecules using gravimetric sensors.

  11. Electrolytic silver ion cell sterilizes water supply

    NASA Technical Reports Server (NTRS)

    Albright, C. F.; Gillerman, J. B.

    1968-01-01

    Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

  12. Energy science: Fast track for silver

    NASA Astrophysics Data System (ADS)

    Nilges, Tom

    2016-08-01

    A solid composite material has been made that conducts electricity through the rapid transport of silver ions, which diffuse faster than in some liquids. The material holds promise for applications in charge-storage devices. See Article p.159

  13. Antimicrobial silver: An unprecedented anion effect

    PubMed Central

    Swathy, J. R.; Sankar, M. Udhaya; Chaudhary, Amrita; Aigal, Sahaja; Anshup; Pradeep, T.

    2014-01-01

    Silver is an indispensable metal but its use has to be minimised for sustainable growth. Much of the silver lost during use is unrecoverable; an example being its use as an antimicrobial agent, a property known since ages. While developing methods to create an affordable drinking water purifier especially for the developing world, we discovered that 50 parts per billion (ppb) of Ag+ released continuously from silver nanoparticles confined in nanoscale cages is enough to cause antimicrobial activity in conditions of normal water. Here we show that the antibacterial and antiviral activities of Ag+ can be enhanced ~1,000 fold, selectively, in presence of carbonate ions whose concentration was maintained below the drinking water norms. The protective layers of the organisms were affected during the carbonate-assisted antimicrobial activity. It is estimated that ~1,300 tons of silver can be saved annually using this new way to enhance its antimicrobial activity. PMID:25418185

  14. Large silver-cadmium technology program

    NASA Technical Reports Server (NTRS)

    Charlip, S.; Lerner, S.

    1971-01-01

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

  15. Realistic Silver Optical Constants for Plasmonics

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  16. Realistic Silver Optical Constants for Plasmonics

    PubMed Central

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

    2016-01-01

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

  17. Realistic Silver Optical Constants for Plasmonics.

    PubMed

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

    2016-07-29

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

  18. Green synthesis of silver nanoparticles using tannins

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  19. Examination of Ostwald ripening in the photocatalytic growth of silver nanoparticles on titanium dioxide coatings

    NASA Astrophysics Data System (ADS)

    Piwoński, Ireneusz; Spilarewicz-Stanek, Kaja; Kisielewska, Aneta; Kądzioła, Kinga; Cichomski, Michał; Ginter, Joanna

    2016-06-01

    Silver nanoparticles (AgNPs) were grown on the surface of titanium dioxide coating (TiO2) using a photochemical method. The size and number of AgNPs were monitored using scanning electron microscopy (SEM) after 20, 30, 180 and 300 s of UV illumination. It was found that for short illumination times (20 s) a significant number of small nanoparticles were grown. However, after an additional 10 s of illumination, small nanoparticles were subject to decomposition and the released Ag+ ions were utilized for the growth of the existing larger nanoparticles, causing an increase in their dimensions. The observed results indicate that the nucleation and further growth of AgNPs proceed according to Ostwald ripening. For longer illumination times (180, 300 s) a coalescence of closely located particles was observed.

  20. Fluorescent DNA-templated silver nanoclusters

    NASA Astrophysics Data System (ADS)

    Lin, Ruoqian

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

  1. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, C.Q. Jr.

    1980-01-28

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

  2. Process for preparing improved silvered glass mirrors

    DOEpatents

    Buckwalter, Jr., Charles Q.

    1981-01-01

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

  3. 'Chrysanthemum petal' arrangements of silver nano wires.

    PubMed

    Cui, Hui-Wang; Jiu, Jin-Ting; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki; Uchida, Hiroshi

    2014-12-01

    Highly ordered 'Chrysanthemum petal' arrangements of silver nano wires were fabricated in a biodegradable polymer of polyvinyl alcohol using a simple one-step blending method without any template. The degree of the arrangement increased with the decreasing content of polyvinyl alcohol. The mechanism for the formation of these 'Chrysanthemum petal' arrangements was discussed specifically. These 'Chrysanthemum petal' arrangements will be helpful to increase the electrical conductivity of silver nano wires films. PMID:25397618

  4. Characterisations of collagen-silver-hydroxyapatite nanocomposites

    NASA Astrophysics Data System (ADS)

    Ciobanu, C. S.; Popa, C. L.; Petre, C. C.; Jiga, G.; Trusca, R.; Predoi, D.

    2016-05-01

    The XRD analysis were performed to confirm the formation of hydroxyapatite structure in collagen-silver-hydroxyapatite nanocomposites. The molecular interaction in collagen-hydroxyapatite nanocomposites was highlighted by Fourier transform infrared spectroscopy (FTIR) analysis. The SEM showed a nanostructure of collagen-silverhydroxyapatite nanocomposites composed of nano needle-like particles in a veil with collagen texture. The presence of vibrational groups characteristics to the hydroxyapatite structure in collagen-silver-hydroxyapatite (AgHApColl) nanocomposites was investigated by FTIR.

  5. Silver and gold-catalyzed multicomponent reactions

    PubMed Central

    Abbiati, Giorgio

    2014-01-01

    Summary Silver and gold salts and complexes mainly act as soft and carbophilic Lewis acids even if their use as σ-activators has been rarely reported. Recently, transformations involving Au(I)/Au(III)-redox catalytic systems have been reported in the literature. In this review we highlight all these aspects of silver and gold-mediated processes and their application in multicomponent reactions. PMID:24605168

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

    PubMed

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

    2015-01-01

    The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS) and by inductively coupled plasma mass spectrometer (ICP-MS). The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX). Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM). On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration) ranged from 0.7 to 4.7 μg/mL (0.6-4.0 μg/cm(2)), fitting the bactericidal range. Silver and silver chloride aggregates at sizes of up to 1 μm were identified both in the epidermis and dermis. The large size of these particles suggests that the aggregation occurred in the skin. The formation of these aggregates likely slowed down the systemic absorption of silver. Conversely, these aggregates may form a reservoir enabling prolonged release of silver ions, which might lead to local effects.

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

    PubMed Central

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

    2015-01-01

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

  8. [In vitro percutaneous absorption of silver nanoparticles].

    PubMed

    Filon, F Larese; D'Agostin, F; Crosera, M; Adami, G; Rosani, R; Romano, C; Bovenzi, M; Maina, G

    2007-01-01

    There is a growing interest in the debate on nanoparticle safety for topical use. The benefits of nanoparticles have been shown in several scientific fields, but little is known about their potential to penetrate the skin lies. This study aims at evaluating in vitro silver nanoparticles skin penetration. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. Physiological solution was used as receiving phase and 70 microg/cm2 of silver nanoparticles dispersed in synthetic sweat were applied as donor phase to the outer surface of the skin for 24h. The receptor fluid measurements were performed by Electro Thermal Atomic Absorption Spectroscopy (ETAAS). Silver concentration of 0.2 microg/L was found in the receiving solutions of two cells, in which damaged skin membranes were set up. In the other tests, we obtained a silver concentration below the limit of detection in the receiving cells. Our experimental data show that silver nanoparticles permeation through intact and damaged skin is negligible. These findings are consistent with previously published results. Further researches are necessary to explore skin absorption of silver nanoparticles.

  9. Silver As Antibacterial toward Listeria monocytogenes.

    PubMed

    Belluco, Simone; Losasso, Carmen; Patuzzi, Ilaria; Rigo, Laura; Conficoni, Daniele; Gallocchio, Federica; Cibin, Veronica; Catellani, Paolo; Segato, Severino; Ricci, Antonia

    2016-01-01

    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. PMID:27014230

  10. Acoustical deterrence of Silver Carp (Hypophthalmichthys molitrix)

    USGS Publications Warehouse

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

    2015-01-01

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

  11. Pulsed EPR for studying silver clusters

    NASA Astrophysics Data System (ADS)

    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 6n+ 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 4n+ 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 3OH 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.

  12. Silver As Antibacterial toward Listeria monocytogenes

    PubMed Central

    Belluco, Simone; Losasso, Carmen; Patuzzi, Ilaria; Rigo, Laura; Conficoni, Daniele; Gallocchio, Federica; Cibin, Veronica; Catellani, Paolo; Segato, Severino; Ricci, Antonia

    2016-01-01

    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. PMID:27014230

  13. Heron Island, Australia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Heron Island is located at the sourthern end of Australia's 2,050 km-long Great Barrier Reef. Surrounded by coral reef and home to over 1000 species of fish, scuba divers and scientists alike are drawn to the island's resort and research station. The true-color image above was taken by Space Imaging's Ikonos satellite with a resolution of 4 meters per pixel-high enough to see individual boats tied up at the small marina. The narrow channel leading from the marina to the ocean was blasted and dredged decades ago, before the island became a national park. Since then the Australian government has implemented conservation measures, such as limiting the number of tourists and removing or recycling, instead of incinerating, all trash. One of the applications of remote sensing data from Ikonos is environmental monitoring, including studies of coral reef health. For more information about the island, read Heron Island. Image by Robert Simmon, based on data copyright Space Imaging

  14. Enhancement of critical current density in YBa2Cu3O7-dgr thin films grown using PLD on YSZ (001) surface modified with Ag nano-dots

    NASA Astrophysics Data System (ADS)

    Ionescu, M.; Li, A. H.; Zhao, Y.; Liu, H. K.; Crisan, A.

    2004-07-01

    Y123 thin films were grown by pulsed laser deposition (PLD) on YSZ (001) substrate. Prior to the film deposition, a discontinuous layer of Ag was deposited on the substrate, also using PLD, in the form of separate islands. Atomic force microscopy (AFM) investigation of the Ag layer showed that its morphology consisted of self-assembled islands of nanometre size, randomly distributed on the surface of the substrate, called nano-dots. The Y123 superconducting films grown on such a surface were characterized using AFM, x-ray diffraction, secondary electron microscopy, ac susceptibility and dc magnetization. The results show that there is no significant difference in surface morphology, crystallographic orientation, phase composition or superconducting transition temperature between the Y123 films grown on YSZ (001) with an Ag nano-dots layer and a control Y123 film grown on a virgin YSZ (001) surface. On the other hand, at 77 K, the magnetic critical current density ( J_c^m ) was three times higher for the Y123 film grown on YSZ with the modified (001) surface than for the film grown on YSZ with a virgin (001) surface. At 5 K the enhancement of J_c^m was approximately seven times, at both low and high fields. This suggests an increase in pinning, caused presumably by point defects formed in the Y123 film above the Ag islands.

  15. Effects of Disinfectants in Water on Mir- and Earth-Grown Wheat

    NASA Technical Reports Server (NTRS)

    Campbell, William .F.; Bubenheim, D. L.; Bugbee, B.; Salisbury, F. B.; Bingham, G. E.; Levinskikh, M.; Sytchev, V. N.; Ivanova, I.; Chernova, L.; Podolsky, I.

    2002-01-01

    -based post-flight analyses, the levels of iodine- and/or silver fluoride-treated water used on Mir-grown plants onboard the Mir did not cause the poor growth and development of the wheat plants.

  16. Habitat and environment of islands: primary and supplemental island sets

    USGS Publications Warehouse

    Matalas, Nicholas C.; Grossling, Bernardo F.

    2002-01-01

    The original intent of the study was to develop a first-order synopsis of island hydrology with an integrated geologic basis on a global scale. As the study progressed, the aim was broadened to provide a framework for subsequent assessments on large regional or global scales of island resources and impacts on those resources that are derived from global changes. Fundamental to the study was the development of a comprehensive framework?a wide range of parameters that describe a set of 'saltwater' islands sufficiently large to Characterize the spatial distribution of the world?s islands; Account for all major archipelagos; Account for almost all oceanically isolated islands, and Account collectively for a very large proportion of the total area of the world?s islands whereby additional islands would only marginally contribute to the representativeness and accountability of the island set. The comprehensive framework, which is referred to as the ?Primary Island Set,? is built on 122 parameters that describe 1,000 islands. To complement the investigations based on the Primary Island Set, two supplemental island sets, Set A?Other Islands (not in the Primary Island Set) and Set B?Lagoonal Atolls, are included in the study. The Primary Island Set, together with the Supplemental Island Sets A and B, provides a framework that can be used in various scientific disciplines for their island-based studies on broad regional or global scales. The study uses an informal, coherent, geophysical organization of the islands that belong to the three island sets. The organization is in the form of a global island chain, which is a particular sequential ordering of the islands referred to as the 'Alisida.' The Alisida was developed through a trial-and-error procedure by seeking to strike a balance between 'minimizing the length of the global chain' and 'maximizing the chain?s geophysical coherence.' The fact that an objective function cannot be minimized and maximized simultaneously

  17. Grades of the Not So Modeled: Asian American and Pacific Islander Transfer Students at Middle University

    ERIC Educational Resources Information Center

    Lui, Joyce

    2013-01-01

    The understanding of Asian-American and Pacific Islander (AAPI) students, beyond stereotypes, has been limited (Museus, 2009). Although literature on transfer students has grown, the limited research on AAPI transfer students is lacking. A more accurate portrayal of their academic progress needs to be examined. One of the ways to better understand…

  18. Maintenance of biodiversity on islands.

    PubMed

    Chisholm, Ryan A; Fung, Tak; Chimalakonda, Deepthi; O'Dwyer, James P

    2016-04-27

    MacArthur and Wilson's theory of island biogeography predicts that island species richness should increase with island area. This prediction generally holds among large islands, but among small islands species richness often varies independently of island area, producing the so-called 'small-island effect' and an overall biphasic species-area relationship (SAR). Here, we develop a unified theory that explains the biphasic island SAR. Our theory's key postulate is that as island area increases, the total number of immigrants increases faster than niche diversity. A parsimonious mechanistic model approximating these processes reproduces a biphasic SAR and provides excellent fits to 100 archipelago datasets. In the light of our theory, the biphasic island SAR can be interpreted as arising from a transition from a niche-structured regime on small islands to a colonization-extinction balance regime on large islands. The first regime is characteristic of classic deterministic niche theories; the second regime is characteristic of stochastic theories including the theory of island biogeography and neutral theory. The data furthermore confirm our theory's key prediction that the transition between the two SAR regimes should occur at smaller areas, where immigration is stronger (i.e. for taxa that are better dispersers and for archipelagos that are less isolated).

  19. Maintenance of biodiversity on islands.

    PubMed

    Chisholm, Ryan A; Fung, Tak; Chimalakonda, Deepthi; O'Dwyer, James P

    2016-04-27

    MacArthur and Wilson's theory of island biogeography predicts that island species richness should increase with island area. This prediction generally holds among large islands, but among small islands species richness often varies independently of island area, producing the so-called 'small-island effect' and an overall biphasic species-area relationship (SAR). Here, we develop a unified theory that explains the biphasic island SAR. Our theory's key postulate is that as island area increases, the total number of immigrants increases faster than niche diversity. A parsimonious mechanistic model approximating these processes reproduces a biphasic SAR and provides excellent fits to 100 archipelago datasets. In the light of our theory, the biphasic island SAR can be interpreted as arising from a transition from a niche-structured regime on small islands to a colonization-extinction balance regime on large islands. The first regime is characteristic of classic deterministic niche theories; the second regime is characteristic of stochastic theories including the theory of island biogeography and neutral theory. The data furthermore confirm our theory's key prediction that the transition between the two SAR regimes should occur at smaller areas, where immigration is stronger (i.e. for taxa that are better dispersers and for archipelagos that are less isolated). PMID:27122558

  20. Silver cycles: The stocks and flows project, part 3

    NASA Astrophysics Data System (ADS)

    Johnson, Jeremiah; Gordon, Robert; Graedel, Thomas

    2006-02-01

    The quantitative assessment of the flows of materials from resource extraction to final disposal informs resource policy, energy planning, environmental science, and waste management. This article reports the technological cycles of silver worldwide and in representative countries for 1997. Most silver is produced in conjunction with other metals; only a quarter of world production is from silver ore. Industrial applications account for 40% of silver use. While about a third of world use goes into jewelry, tableware, and the arts, silver cycles through the world economy to recycling faster than metals such as copper and zinc. Despite decreasing use in photography, demand for silver continues to increase.

  1. Reprotoxicity of gold, silver, and gold-silver alloy nanoparticles on mammalian gametes.

    PubMed

    Tiedemann, Daniela; Taylor, Ulrike; Rehbock, Christoph; Jakobi, Jurij; Klein, Sabine; Kues, Wilfried A; Barcikowski, Stephan; Rath, Detlef

    2014-03-01

    Metal and alloy nanoparticles are increasingly developed for biomedical applications, while a firm understanding of their biocompatibility is still missing. Various properties have been reported to influence the toxic potential of nanoparticles. This study aimed to assess the impact of nanoparticle size, surface ligands and chemical composition of gold, silver or gold-silver alloy nanoparticles on mammalian gametes. An in vitro assay for porcine gametes was developed, since these are delicate primary cells, for which well-established culture systems exist and functional parameters are defined. During coincubation with oocytes for 46 h neither any of the tested gold nanoparticles nor the gold-silver alloy particles with a silver molar fraction of up to 50% showed any impact on oocyte maturation. Alloy nanoparticles with 80% silver molar fraction and pure silver nanoparticles inhibited cumulus-oocyte maturation. Confocal microscopy revealed a selective uptake of gold nanoparticles by oocytes, while silver and alloy particles mainly accumulated in the cumulus cell layer surrounding the oocyte. Interestingly sperm vitality parameters (motility, membrane integrity and morphology) were not affected by any of the tested nanoparticles. Only sporadic association of nanoparticles with the sperm plasma membrane was found by transmission electron microscopy. In conclusion, mammalian oocytes were sensitive to silver containing nanoparticles. Likely, the delicate process of completing meiosis in maternal gametes features high vulnerability towards nanomaterial derived toxicity. The results imply that released Ag(+)-ions are responsible for the observed toxicity, but the compounding into an alloy seemed to alleviate the toxic effects to a certain extent.

  2. The Silver Complexes of Porphyrins, Corroles, and Carbaporphyrins: Silver in the Oxidation States II and III

    ERIC Educational Resources Information Center

    Bruckner, Christian

    2004-01-01

    Studies in relation to the silver complexes of porphyrins, corroles and carbaporphyrins are presented especially with relation to silver in the oxidation states II and III. It is seen that the Ag(sub III) complex was electrochemically readily and reversibly reduced to the corresponding Ag(sub II) complex, thus indicating that the complex could be…

  3. Radioactive iodine capture in silver-containing mordenites through nanoscale silver iodide formation.

    SciTech Connect

    Chapman, K. W.; Chupas, P. J.; Nenoff, T. M.; X-Ray Science Division; SNL

    2010-01-01

    The effective capture and storage of radiological iodine ({sup 129}I) remains a strong concern for safe nuclear waste storage and safe nuclear energy. Silver-containing mordenite (MOR) is a longstanding benchmark for iodine capture; however, the molecular level understanding of this process needed to develop more effective iodine getters has remained elusive. Here we probe the structure and distribution of iodine sorbed by silver-containing MOR using differential pair distribution function analysis. While iodine is distributed between {gamma}-AgI nanoparticles on the zeolite surface and subnanometer {alpha}-AgI clusters within the pores for reduced silver MOR, in the case of unreduced silver-exchanged MOR, iodine is exclusively confined to the pores as subnanometer {alpha}-AgI. Consequently, unreduced silver-containing zeolites may offer a more secure route for radioactive iodine capture, with the potential to more effectively trap the iodine for long-term storage.

  4. Radioactive iodine capture in silver-containing mordenites through nanoscale silver iodide formation.

    PubMed

    Chapman, Karena W; Chupas, Peter J; Nenoff, Tina M

    2010-07-01

    The effective capture and storage of radiological iodine ((129)I) remains a strong concern for safe nuclear waste storage and safe nuclear energy. Silver-containing mordenite (MOR) is a longstanding benchmark for iodine capture; however, the molecular level understanding of this process needed to develop more effective iodine getters has remained elusive. Here we probe the structure and distribution of iodine sorbed by silver-containing MOR using differential pair distribution function analysis. While iodine is distributed between gamma-AgI nanoparticles on the zeolite surface and subnanometer alpha-AgI clusters within the pores for reduced silver MOR, in the case of unreduced silver-exchanged MOR, iodine is exclusively confined to the pores as subnanometer alpha-AgI. Consequently, unreduced silver-containing zeolites may offer a more secure route for radioactive iodine capture, with the potential to more effectively trap the iodine for long-term storage. PMID:20550110

  5. Archaeoastronomy of Easter Island

    NASA Astrophysics Data System (ADS)

    Edwards, Edmundo

    Astronomer priests or "skywatchers" on Easter Island lived in stone towers that were used as observatories and built stone markers in the periphery that indicated the heliacal rising of certain stars that served to indicate the arrival of marine birds, turtles, the offshore fishing season, and times for planting and harvest. Petroglyphs related to such sites depict outriggers, fishhooks, pelagic fish, and turtles and supposedly represented a star map. In this chapter, we analyze a set of such skywatchers dwellings, and stone markers located upon the North coast of Easter Island that have astronomic orientations, its related petroglyphs, and the relations between these directions with their yearly activities and their ritual calendar.

  6. Island custom blocking technique

    SciTech Connect

    Carabetta, R.J. )

    1988-03-01

    The technique of Island blocking is being used more frequently since the advent of our new head and neck blocking techniques and the implementation of a newly devised lung protocol. The system presented affords the mould room personnel a quick and accurate means of island block fabrication without the constant remeasuring or subtle shifting to approximate correct placement. The cookie cutter is easily implemented into any department's existing block cutting techniques. The device is easily and inexpensively made either in a machine shop or acquired by contacting the author.

  7. Long Island Solar Farm

    SciTech Connect

    Anders, R.

    2013-05-01

    The Long Island Solar Farm (LISF) is a remarkable success story, whereby very different interest groups found a way to capitalize on unusual circumstances to develop a mutually beneficial source of renewable energy. The uniqueness of the circumstances that were necessary to develop the Long Island Solar Farm make it very difficult to replicate. The project is, however, an unparalleled resource for solar energy research, which will greatly inform large-scale PV solar development in the East. Lastly, the LISF is a superb model for the process by which the project developed and the innovation and leadership shown by the different players.

  8. Sakhalin Island terrain intelligence

    USGS Publications Warehouse

    ,

    1943-01-01

    This folio of maps and explanatory tables outlines the principal terrain features of Sakhalin Island. Each map and table is devoted to a specialized set of problems; together they cover the subjects of terrain appreciation, climate, rivers, water supply, construction materials, suitability for roads, suitability for airfields, fuels and other mineral resources, and geology. In most cases, the map of the island is divided into two parts: N. of latitude 50° N., Russian Sakhalin, and south of latitude 50° N., Japanese Sakhalin or Karafuto. These maps and data were compiled by the United States Geological Survey during the period from March to September, 1943.

  9. Self-alignment of silver nanoparticles in highly ordered 2D arrays.

    PubMed

    Rodríguez-León, Ericka; Íñiguez-Palomares, Ramón; Urrutia-Bañuelos, Efraín; Herrera-Urbina, Ronaldo; Tánori, Judith; Maldonado, Amir

    2015-01-01

    We have synthesized silver nanoparticles in the non-polar phase of non-aqueous microemulsions. The nanocrystals have been grown by reducing silver ions in the microemulsion cylindrical micelles formed by the reducing agent (ethylene glycol). By a careful deposit of the microemulsion phase on a substrate, the micelles align in a hexagonal geometry, thus forming a 2D array of parallel strings of individual silver nanoparticles on the substrate. The microemulsions are the ternary system of anionic surfactant, non-polar solvent (isooctane), and solvent polar (ethylene glycol); the size of synthesized nanoparticles is about 7 nm and they are monodisperse. The study of the microstructure was realized by transmission electron microscopy, high-resolution technique transmission electron microscopy (HR-TEM), and Fourier processing using the software Digital Micrograph for the determination of the crystalline structure of the HR-TEM images of the nanocrystals; chemical composition was determined using the energy-dispersive X-ray spectroscopy. Addition technique polarizing light microscopy allowed the observation of the hexagonal phase of the system. This method of synthesis and self-alignment could be useful for the preparation of patterned materials at the nanometer scale.

  10. Effect of silver on the phase transition and wettability of titanium oxide films

    NASA Astrophysics Data System (ADS)

    Mosquera, Adolfo A.; Albella, Jose M.; Navarro, Violeta; Bhattacharyya, Debabrata; Endrino, Jose L.

    2016-08-01

    The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance.

  11. Effect of silver on the phase transition and wettability of titanium oxide films.

    PubMed

    Mosquera, Adolfo A; Albella, Jose M; Navarro, Violeta; Bhattacharyya, Debabrata; Endrino, Jose L

    2016-01-01

    The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance. PMID:27571937

  12. Effect of silver on the phase transition and wettability of titanium oxide films

    PubMed Central

    Mosquera, Adolfo A.; Albella, Jose M.; Navarro, Violeta; Bhattacharyya, Debabrata; Endrino, Jose L.

    2016-01-01

    The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance. PMID:27571937

  13. Self-alignment of silver nanoparticles in highly ordered 2D arrays

    NASA Astrophysics Data System (ADS)

    Rodríguez-León, Ericka; Íñiguez-Palomares, Ramón; Urrutia-Bañuelos, Efraín; Herrera-Urbina, Ronaldo; Tánori, Judith; Maldonado, Amir

    2015-03-01

    We have synthesized silver nanoparticles in the non-polar phase of non-aqueous microemulsions. The nanocrystals have been grown by reducing silver ions in the microemulsion cylindrical micelles formed by the reducing agent (ethylene glycol). By a careful deposit of the microemulsion phase on a substrate, the micelles align in a hexagonal geometry, thus forming a 2D array of parallel strings of individual silver nanoparticles on the substrate. The microemulsions are the ternary system of anionic surfactant, non-polar solvent (isooctane), and solvent polar (ethylene glycol); the size of synthesized nanoparticles is about 7 nm and they are monodisperse. The study of the microstructure was realized by transmission electron microscopy, high-resolution technique transmission electron microscopy (HR-TEM), and Fourier processing using the software Digital Micrograph for the determination of the crystalline structure of the HR-TEM images of the nanocrystals; chemical composition was determined using the energy-dispersive X-ray spectroscopy. Addition technique polarizing light microscopy allowed the observation of the hexagonal phase of the system. This method of synthesis and self-alignment could be useful for the preparation of patterned materials at the nanometer scale.

  14. Effect of silver on the phase transition and wettability of titanium oxide films.

    PubMed

    Mosquera, Adolfo A; Albella, Jose M; Navarro, Violeta; Bhattacharyya, Debabrata; Endrino, Jose L

    2016-08-30

    The effect of silver on the phase transition and microstructure of titanium oxide films grown by pulsed cathodic arc had been investigated by XRD, SEM and Raman spectroscopy. Following successive thermal annealing up to 1000 °C, microstructural analysis of annealed Ag-TiO2 films reveals that the incorporation of Ag nanoparticles strongly affects the transition temperature from the initial metastable amorphous phase to anatase and stable rutile phase. An increase of silver content into TiO2 matrix inhibits the amorphous to anatase phase transition, raising its temperature boundary and, simultaneously reduces the transition temperature to promote rutile structure at lower value of 600 °C. The results are interpreted in terms of the steric effects produced by agglomeration of Ag atoms into larger clusters following annealing which hinders diffusion of Ti and O ions for anatase formation and constrains the volume available for the anatase lattice, thus disrupting its structure to form rutile phase. The effect of silver on the optical and wetting properties of TiO2 was evaluated to demonstrate its improved photocatalytic performance.

  15. Self-alignment of silver nanoparticles in highly ordered 2D arrays.

    PubMed

    Rodríguez-León, Ericka; Íñiguez-Palomares, Ramón; Urrutia-Bañuelos, Efraín; Herrera-Urbina, Ronaldo; Tánori, Judith; Maldonado, Amir

    2015-01-01

    We have synthesized silver nanoparticles in the non-polar phase of non-aqueous microemulsions. The nanocrystals have been grown by reducing silver ions in the microemulsion cylindrical micelles formed by the reducing agent (ethylene glycol). By a careful deposit of the microemulsion phase on a substrate, the micelles align in a hexagonal geometry, thus forming a 2D array of parallel strings of individual silver nanoparticles on the substrate. The microemulsions are the ternary system of anionic surfactant, non-polar solvent (isooctane), and solvent polar (ethylene glycol); the size of synthesized nanoparticles is about 7 nm and they are monodisperse. The study of the microstructure was realized by transmission electron microscopy, high-resolution technique transmission electron microscopy (HR-TEM), and Fourier processing using the software Digital Micrograph for the determination of the crystalline structure of the HR-TEM images of the nanocrystals; chemical composition was determined using the energy-dispersive X-ray spectroscopy. Addition technique polarizing light microscopy allowed the observation of the hexagonal phase of the system. This method of synthesis and self-alignment could be useful for the preparation of patterned materials at the nanometer scale. PMID:25883540

  16. Overgrowth of Silver Nanodisks on a Substrate into Vertically Aligned Nanopillars for Chromatic Light Polarization.

    PubMed

    Mahmoud, Mahmoud A

    2016-09-14

    Vertically aligned and well-separated 1D silver nanopillars (AgNPLs) are prepared on a large-area quartz surface using a robust colloidal chemical technique. Silver nanodisk (AgND) monolayers were first deposited on quartz using the Langmuir-Blodgett technique, and the presence of the substrate induced asymmetric chemical overgrowth of the AgNDs into AgNPLs. The height and diameter of the prepared AgNPLs were controlled by changing the rate of the overgrowth reaction. Chloride ions were used during overgrowth to etch the silver atoms that formed sharp features on the sides of the AgNDs and to limit growth in the lateral direction. The grown AgNPLs displayed two surface plasmon resonance modes corresponding to the transverse and longitudinal electron oscillations. The intensity of the longitudinal mode increased by a factor of 9 while the intensity of the transverse mode decreased by a factor of 2.5 upon increasing the angle of incidence of the exciting light from 0° to 60°. This interesting property makes these AgNPL arrays on quartz useful as chromatic light polarizers. PMID:27561747

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

    ERIC Educational Resources Information Center

    Trujillo, Carlos Alexander

    2007-01-01

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

  18. Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent

    NASA Astrophysics Data System (ADS)

    Zienkiewicz-Strzałka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

    2013-02-01

    Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV

  19. Silver nanoclusters emitting weak NIR fluorescence biomineralized by BSA

    NASA Astrophysics Data System (ADS)

    Li, Baoshun; Li, Jianjun; Zhao, Junwu

    2015-01-01

    Noble metal (e.g., gold and silver) nanomaterials possess unique physical and chemical properties. In present work, silver nanoclusters (also known as silver quantum clusters or silver quantum dots) were synthesized by bovine serum albumin (BSA) biomineralization. The synthesized silver nanoclusters were characterized by UV-VIS absorption spectroscopy, fluorescence spectroscopy, upconversion emission spectroscopy, TEM, HRTEM and FTIR spectroscopy. TEM results showed that the average size of the silver nanoclusters was 2.23 nm. Fluorescence results showed that these silver nanoclusters could emit weak near-infrared (NIR) fluorescence (the central emission wavelength being about 765 nm). And the central excitation wavelength was about 395 nm, in the UV spectral region. These silver nanoclusters showed an extraordinarily large gap (about 370 nm) between the central excitation wavelength and central emission wavelength. In addition, it was found that these silver nanoclusters possess upconversion emission property. Upconversion emission results showed that the upconversion emission spectrum of the silver nanoclusters agreed well with their normal fluorescence emission spectrum. The synthesized silver nanoclusters showed high stability in aqueous solution and it was considered that they might be confined in BSA molecules. It was found that silver nanoclusters might enhance and broaden the absorption of proteins, and the protein absorption peak showed an obvious red shift (being 7 nm) after the formation of silver nanoclusters.

  20. Distribution of dissolved silver in marine waters

    NASA Astrophysics Data System (ADS)

    Barriada, J. L.; Achterberg, E. P.; Tappin, A.; Truscott, J.

    2003-04-01

    Silver is one of the most toxic heavy metals, surpassed only by mercury [1-3]. Monitoring of dissolved silver concentrations in natural waters is therefore of great importance. The determination of dissolved silver in waters is not without challenges, because of its low (picomolar) concentrations. Consequently, there are only a few reported studies in marine waters, which have been performed in USA [4-6] and Japan [7]. The analytical techniques used in the reported studies for the determination of silver in seawater were Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) after solvent extraction [2,4,5], and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after solvent extraction or solid phase extraction [7,8]. In this contribution, we will present an optimised Magnetic Sector (MS) ICP-MS technique for the determination of dissolved silver in marine waters. The MS-ICP-MS method used anion exchange column to preconcentrate silver from saline waters, and to remove the saline matrix. The ICP-MS method has been used successfully to determine total dissolved silver in estuarine and oceanic samples. Bibliography 1. H. T. Ratte, Environ. Toxicol. Chem. 1999, 18: p. 89-108. 2. R. T. Herrin, A. W. Andren and D. E. Armstrong, Environ. Sci. Technol. 2001, 35: 1953-1958. 3. D. E. Schildkraut, P. T. Dao, J. P. Twist, A. T. Davis and K. A. Robillard, Environ. Toxicol. Chem. 1998, 17: 642-649. 4. E. Breuer, S. A. Sanudo-Wilhelmy and R. C. Aller, Estuaries. 1999, 22:603-615. 5. A. R. Flegal, S. A. Sanudowilhelmy and G. M. Scelfo, Mar. Chem. 1995, 49: 315-320. 6. S. N. Luoma, Y. B. Ho and G. W. Bryan, Mar. Pollut. Bull. 1995, 31: 44-54. 7. Y. Zhang, H. Amakawa and Y. Nozaki, Mar. Chem. 2001, 75: 151-163. 8. L. Yang and R. E. Sturgeon, J. Anal. At. Spectrom. 2002, 17: 88-93.

  1. Biomineralization of hydroxyapatite in silver ion-exchanged nanocrystalline ZSM-5 zeolite using simulated body fluid.

    PubMed

    Kaur, Balwinder; Srivastava, Rajendra; Satpati, Biswarup; Kondepudi, Kanthi Kiran; Bishnoi, Mahendra

    2015-11-01

    Silver ion-exchanged nanocrystalline zeolite (Ag-Nano-ZSM-5) and silver ion-exchanged conventional zeolite (Ag-ZSM-5) were synthesized. Zeolites were incubated in simulated body fluid at 310K for different time periods to grow hydroxyapatite in their matrixes. Significant large amount of hydroxyapatite was grown in Ag-Nano-ZSM-5 matrix after incubation in simulated body fluid when compared to Ag-ZSM-5. The resultant material was characterized using X-ray diffraction, N2-adsorption, scanning/transmission electron microscopy, energy dispersive X-ray, and inductively coupled plasma analysis. Mechanical properties such as compressive modulus, compressive strength, and strain at failure of the parent materials were evaluated. Biocompatibility assays suggested that Ag-Nano-ZSM-5 and hydroxyapatite grown in Ag-Nano-ZSM-5 were compatible and did not impose any toxicity to RAW 264.7 cells macrophase and Caco2 cells suggesting considerable potential for biomedical applications such as bone implants.

  2. Biomineralization of hydroxyapatite in silver ion-exchanged nanocrystalline ZSM-5 zeolite using simulated body fluid.

    PubMed

    Kaur, Balwinder; Srivastava, Rajendra; Satpati, Biswarup; Kondepudi, Kanthi Kiran; Bishnoi, Mahendra

    2015-11-01

    Silver ion-exchanged nanocrystalline zeolite (Ag-Nano-ZSM-5) and silver ion-exchanged conventional zeolite (Ag-ZSM-5) were synthesized. Zeolites were incubated in simulated body fluid at 310K for different time periods to grow hydroxyapatite in their matrixes. Significant large amount of hydroxyapatite was grown in Ag-Nano-ZSM-5 matrix after incubation in simulated body fluid when compared to Ag-ZSM-5. The resultant material was characterized using X-ray diffraction, N2-adsorption, scanning/transmission electron microscopy, energy dispersive X-ray, and inductively coupled plasma analysis. Mechanical properties such as compressive modulus, compressive strength, and strain at failure of the parent materials were evaluated. Biocompatibility assays suggested that Ag-Nano-ZSM-5 and hydroxyapatite grown in Ag-Nano-ZSM-5 were compatible and did not impose any toxicity to RAW 264.7 cells macrophase and Caco2 cells suggesting considerable potential for biomedical applications such as bone implants. PMID:26255163

  3. Versatile synthesis of PHMB-stabilized silver nanoparticles and their significant stimulating effect on fodder beet (Beta vulgaris L.).

    PubMed

    Gusev, Alexander А; Kudrinsky, Alexey A; Zakharova, Olga V; Klimov, Alexey I; Zherebin, Pavel M; Lisichkin, George V; Vasyukova, Inna A; Denisov, Albert N; Krutyakov, Yurii A

    2016-05-01

    Silver nanoparticles (AgNPs) are well-known bactericidal agents. However, information about the influence of AgNPs on the morphometric parameters and biochemical status of most important agricultural crops is limited. The present study reports the influence of AgNPs stabilized with cationic polymer polyhexamethylene biguanide hydrochloride (PHMB) on growth, development, and biochemical status of fodder beet Beta vulgaris L. under laboratory and greenhouse conditions. PHMB-stabilized AgNPs were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The average diameter of thus prepared AgNPs was 10 nm. It appears that the results of experiments with laboratory-grown beets in the nanosilver-containing medium, where germination of seeds and growth of roots were suppressed, do not correlate with the results of greenhouse experiments. The observed growth-stimulating action of PHMB-stabilized AgNPs can be explained by the change of activity of oxidases and, consequently, by the change of auxins amount in plant tissues. In beets grown in the presence of PHMB-stabilized AgNPs no negative deviations of biological parameters from normal values were registered. Furthermore, the SEM/EDS examination revealed no presence of silver in the tissues of the studied plants.

  4. Versatile synthesis of PHMB-stabilized silver nanoparticles and their significant stimulating effect on fodder beet (Beta vulgaris L.).

    PubMed

    Gusev, Alexander А; Kudrinsky, Alexey A; Zakharova, Olga V; Klimov, Alexey I; Zherebin, Pavel M; Lisichkin, George V; Vasyukova, Inna A; Denisov, Albert N; Krutyakov, Yurii A

    2016-05-01

    Silver nanoparticles (AgNPs) are well-known bactericidal agents. However, information about the influence of AgNPs on the morphometric parameters and biochemical status of most important agricultural crops is limited. The present study reports the influence of AgNPs stabilized with cationic polymer polyhexamethylene biguanide hydrochloride (PHMB) on growth, development, and biochemical status of fodder beet Beta vulgaris L. under laboratory and greenhouse conditions. PHMB-stabilized AgNPs were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The average diameter of thus prepared AgNPs was 10 nm. It appears that the results of experiments with laboratory-grown beets in the nanosilver-containing medium, where germination of seeds and growth of roots were suppressed, do not correlate with the results of greenhouse experiments. The observed growth-stimulating action of PHMB-stabilized AgNPs can be explained by the change of activity of oxidases and, consequently, by the change of auxins amount in plant tissues. In beets grown in the presence of PHMB-stabilized AgNPs no negative deviations of biological parameters from normal values were registered. Furthermore, the SEM/EDS examination revealed no presence of silver in the tissues of the studied plants. PMID:26952409

  5. Combined roughness and electric polarization for the local-field enhancement of the second harmonic response from a silver-electrolyte interface

    NASA Astrophysics Data System (ADS)

    El Harfouch, Y.; Benichou, E.; Russier-Antoine, I.; Bachelier, G.; Jonin, Ch.; Berlouis, L.; Brevet, P. F.

    2009-03-01

    A nanoscale rough silver film is electrodeposited from a silver cyanide aqueous solution and its growth is monitored by second harmonic generation (SHG). For growth by potential step into the diffusion controlled region, a maximum in the SHG intensity is always obtained for an equivalent silver film thickness of ˜60nm , based on the charge consumed. The SH intensity decreases for thicker but smoother films. A study as a function of an applied static electric field for an already grown film shows that the combination of nanoscale roughness and electric polarization is able to yield large enhancement of SH signal intensities. From a microscopic analysis of the data, it is shown that the nonlinear surface current perpendicular to the interface exhibits a nonlinear dependence with the applied potential, owing to the combination of roughness and electric polarization.

  6. Silver nanowire decorated heatable textiles.

    PubMed

    Doganay, Doga; Coskun, Sahin; Genlik, Sevim Polat; Unalan, Husnu Emrah

    2016-10-28

    The modification of insulating fabrics with electrically conductive nanomaterials has opened up a novel application field. With the help of Joule heating mechanism, conductive fabrics can be used as mobile heaters. In this work, heatable textiles are fabricated using silver nanowires (Ag NWs). Cotton fabrics are decorated with polyol synthesized Ag NWs via a simple dip-and-dry method. The time-dependent thermal response of the fabrics under different applied voltages is investigated. It is found that the fabrics can be heated to 50 °C under an applied power density of as low as 0.05 W cm(-2). Uniform deposition of Ag NWs resulted in the homogeneous generation of heat. In addition, the stability of the fabrics with time and under different bending and washing conditions is examined. Moreover, a simple control circuit is fabricated and integrated in order to demonstrate the high potential of the fabrics for mobile applications. This work provides a roadmap for researchers who would like to work on heatable textiles with metallic NWs. PMID:27651222

  7. Silver nanowire decorated heatable textiles

    NASA Astrophysics Data System (ADS)

    Doganay, Doga; Coskun, Sahin; Polat Genlik, Sevim; Emrah Unalan, Husnu

    2016-10-01

    The modification of insulating fabrics with electrically conductive nanomaterials has opened up a novel application field. With the help of Joule heating mechanism, conductive fabrics can be used as mobile heaters. In this work, heatable textiles are fabricated using silver nanowires (Ag NWs). Cotton fabrics are decorated with polyol synthesized Ag NWs via a simple dip-and-dry method. The time-dependent thermal response of the fabrics under different applied voltages is investigated. It is found that the fabrics can be heated to 50 °C under an applied power density of as low as 0.05 W cm-2. Uniform deposition of Ag NWs resulted in the homogeneous generation of heat. In addition, the stability of the fabrics with time and under different bending and washing conditions is examined. Moreover, a simple control circuit is fabricated and integrated in order to demonstrate the high potential of the fabrics for mobile applications. This work provides a roadmap for researchers who would like to work on heatable textiles with metallic NWs.

  8. Silver nanowire decorated heatable textiles.

    PubMed

    Doganay, Doga; Coskun, Sahin; Genlik, Sevim Polat; Unalan, Husnu Emrah

    2016-10-28

    The modification of insulating fabrics with electrically conductive nanomaterials has opened up a novel application field. With the help of Joule heating mechanism, conductive fabrics can be used as mobile heaters. In this work, heatable textiles are fabricated using silver nanowires (Ag NWs). Cotton fabrics are decorated with polyol synthesized Ag NWs via a simple dip-and-dry method. The time-dependent thermal response of the fabrics under different applied voltages is investigated. It is found that the fabrics can be heated to 50 °C under an applied power density of as low as 0.05 W cm(-2). Uniform deposition of Ag NWs resulted in the homogeneous generation of heat. In addition, the stability of the fabrics with time and under different bending and washing conditions is examined. Moreover, a simple control circuit is fabricated and integrated in order to demonstrate the high potential of the fabrics for mobile applications. This work provides a roadmap for researchers who would like to work on heatable textiles with metallic NWs.

  9. Kiritimati, Kiribati (Christmas Island)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Pronounced 'Ki-ris-mas,' Kiritimati Island has a large infilled lagoon that gives it the largest land area (125 square miles, 321 square km) of any atoll in the world. Captain Cook named the atoll Christmas Island when he arrived on Christmas Eve in 1777. Used for nuclear testing in the 1950s and 1960s, the island is now valued for its marine and wildlife resources. It is particularly important as a seabird nesting site-with an estimated 6 million birds using or breeding on the island, including several million Sooty Terns. Rainfall on Kiritimati is linked to El Nino patterns, with long droughts experienced between the wetter El Nino years. This image is based on a mosaic of four digital photographs taken on 16 January 2002 from the Space Station Alpha as part of the Crew Earth Observations Project. The underlying data have 10 meter spatial resolution. Coral reefs are one of the areas selected as a scientific theme for this project (see also the recent Earth Observatory article, Mapping the Decline of Coral Reefs. The mosaic, based on images ISS004-ESC-6249 to 6252, was provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  10. Hawaii's Sugar Islands.

    ERIC Educational Resources Information Center

    Hawaiian Sugar Planters' Association, Aiea, HI.

    A warm and sunny subtropical climate helps make Hawaii an important sugar producer. History records that sugarcane was already present when Captain James Cook discovered the islands in 1778, and that the first successful sugarcane plantation was started in 1835 by Ladd and Company at Koloa. The first recorded export of Hawaiian sugar was in 1837,…

  11. Bouvet Island near Antarctica

    Atmospheric Science Data Center

    2013-04-16

    ... supplies were discovered on the island in 1964, but their origin could not be determined. Seals in the area were declared to be ... NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed ...

  12. Christmas Island birds returning

    NASA Astrophysics Data System (ADS)

    Six months after their mass exodus, birds are beginning to return to Christmas Island. Roughly 17 million birds, almost the entire adult bird population, either perished or fled their mid-Pacific atoll home last autumn, leaving behind thousands of nestlings to starve (Eos, April 5, 1983, p. 131). It is believed that the strong El Niño altered the ecology of the surrounding waters and forced the birds to flee. Christmas Island is the world's largest coral atoll.“Ocean and atmosphere scientists are unsure of future directions for the El Niño conditions and cannot now predict what will happen to the birds in the coming months,” said Ralph W. Schreiber, curator of ornithology at the Natural History Museum of Los Angeles County in California. Heisthe ornithologist who discovered the disappearance. “The recovery of the bird populations depends on the food supply in the waters surrounding the island.” The island's birds feed exclusively on small fish and squid.

  13. Multidecadal shoreline changes of atoll islands in the Marshall Islands

    NASA Astrophysics Data System (ADS)

    Ford, M.

    2012-12-01

    Atoll islands are considered highly vulnerable to the impacts of continued sea level rise. One of the most commonly predicted outcomes of continued sea level rise is widespread and chronic shoreline erosion. Despite the widespread implications of predicted erosion, the decadal scale changes of atoll island shorelines are poorly resolved. The Marshall Islands is one of only four countries where the majority of inhabited land is comprised of reef and atoll islands. Consisting of 29 atolls and 5 mid-ocean reef islands, the Marshall Islands are considered highly vulnerable to the impacts of sea level rise. A detailed analysis of shoreline change on over 300 islands on 10 atolls was undertaken using historic aerial photos (1945-1978) and modern high resolution satellite imagery (2004-2012). Results highlight the complex and dynamic nature of atoll islands, with significant shifts in shoreline position observed over the period of analysis. Results suggest shoreline accretion is the dominant mode of change on the islands studied, often associated with a net increase in vegetated island area. However, considerable inter- and intra-atoll variability exists with regards to shoreline stability. Findings are discussed with respect to island morphodynamics and potential hazard mitigation and planning responses within atoll settings.

  14. Silver nitrate masquerading as a radiopaque foreign body.

    PubMed

    Healy, Claragh; Canney, Mark; Murphy, Adrian; Regan, Padraic

    2007-04-01

    Silver nitrate is commonly used as a method of chemical cauterization to areas of hypergranulation. We report two cases wherein silver nitrate in the hand was misinterpreted radiologically as foreign bodies.

  15. Undercoat prevents blistering of silver plating at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Kuster, C. A.

    1967-01-01

    Gold undercoat prevents blistering in the silver plating of Inconel 718 seals from steam at high temperatures. The undercoat is diffused into the surface of the parent metal by baking prior to silver plating.

  16. 1. View looking south on Montana Street. The Silver Bow ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. View looking south on Montana Street. The Silver Bow County Courthouse (1910-1912) is on the left. - Butte Historic District, Bounded by Copper, Arizona, Mercury & Continental Streets, Butte, Silver Bow County, MT

  17. Ink composition for making a conductive silver structure

    DOEpatents

    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.

  18. Sintered silver joints via controlled topography of electronic packaging subcomponents

    DOEpatents

    Wereszczak, Andrew A.

    2014-09-02

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

  19. Silver-catalyzed synthesis of amides from amines and aldehydes

    DOEpatents

    Madix, Robert J; Zhou, Ling; Xu, Bingjun; Friend, Cynthia M; Freyschlag, Cassandra G

    2014-11-18

    The invention provides a method for producing amides via the reaction of aldehydes and amines with oxygen adsorbed on a metallic silver or silver alloy catalyst. An exemplary reaction is shown in Scheme 1: (I), (II), (III). ##STR00001##

  20. 1. General view of silver street, looking southwest downhill toward ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. General view of silver street, looking southwest downhill toward the Mississippi River, showing group of historic buildings - Natchez Bluffs & Under-the-Hill Historic District, Silver Street & adjacent area, Natchez, Adams County, MS

  1. AERIAL VIEW, LOOKING NORTH NORTHWEST, OF ARRASTRA GULCH, WITH SILVER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AERIAL VIEW, LOOKING NORTH NORTHWEST, OF ARRASTRA GULCH, WITH SILVER LAKE IN FOREGROUND. NOTE SILVER LAKE MINE AND MILL RUINS ON FAR SHORE. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

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

    PubMed

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

    2015-04-01

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

  3. AERIAL VIEW, LOOKING NORTH, OF SILVER LAKE. NOTE IOWA MINE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AERIAL VIEW, LOOKING NORTH, OF SILVER LAKE. NOTE IOWA MINE RUINS AT LEFT CENTER AND SILVER LAKE MINE RUINS BEYOND NORTHWEST SHORE. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  4. Magnetic island induced bootstrap current on island dynamics in tokamaks

    SciTech Connect

    Shaing, K.C.; Spong, D.A.

    2006-02-15

    When a magnetic island is embedded in toroidally symmetric tokamaks, the toroidal symmetry in |B| is broken [K. C. Shaing, Phys. Rev. Lett. 87, 245003 (2001)]. Here, B is the magnetic field. This broken symmetry induces an additional bootstrap current density in the vicinity of the island. It is illustrated that this island induced bootstrap current density modifies the island evolution equation and imposes a lower limit on the absolute value of the tearing mode stability parameter {delta}{sup '} for the island to be unstable. This lower limit depends on the local poloidal plasma beta {beta}{sub p}, the ratio of the plasma pressure to the poloidal magnetic field pressure. If {beta}{sub p} is high enough, the magnetic island is stable. This mechanism provides an alternative route to stabilize the island.

  5. Magnetic Island Induced Bootstrap Current on Island Dynamics in Tokamaks

    SciTech Connect

    Spong, Donald A; Shaing, K. C.

    2006-02-01

    When a magnetic island is embedded in toroidally symmetric tokamaks, the toroidal symmetry in |B| is broken [K. C. Shaing, Phys. Rev. Lett. 87, 245003 (2001)] . Here, B is the magnetic field. This broken symmetry induces an additional bootstrap current density in the vicinity of the island. It is illustrated that this island induced bootstrap current density modifies the island evolution equation and imposes a lower limit on the absolute value of the tearing mode stability parameter |{Delta}{prime}| for the island to be unstable. This lower limit depends on the local poloidal plasma beta {beta}{sub p}, the ratio of the plasma pressure to the poloidal magnetic field pressure. If {beta}{sub p} is high enough, the magnetic island is stable. This mechanism provides an alternative route to stabilize the island.

  6. "Go local" island food network: using email networking to promote island foods for their health, biodiversity, and other "CHEEF" benefits.

    PubMed

    Englberger, L; Lorens, A; Pretrick, M E; Spegal, R; Falcam, I

    2010-04-01

    Dietary- and lifestyle-related diseases are problems of epidemic proportion in the Federated States of Micronesia (FSM). Public health resources to help prevent nutrition-related problems are limited. There is also concern about biodiversity, neglect of traditional staple foods, and threatened loss of traditional knowledge. A "Go Local" campaign was initiated to increase production and consumption of locally grown foods, for their Culture, Health, Environment, Economics, and Food security ("CHEEF") benefits. To provide updates and discuss local island food topics, the Island Food Community of Pohnpei launched an interagency email network in 2003. Interested members' email addresses were recorded in distribution lists, weekly/bi-weekly emails were sent and from these messages, a database was organized to record email topic details. An analysis of all emails up to July 2009 showed that membership had expanded to over 600 listed people from all FSM states, other Pacific Island countries and beyond. Information was shared on topics ranging from scientific findings of carotenoid content in local island food cultivars, to discussions on how daily habits related to island food use can be improved. Over 200 men and women, aged 22 to 80 years, contributed items, some indicating that they had shared emails to a further network at their workplace or community. In conclusion, this email network is a simple, cost-effective method to share information, create awareness, and mobilize island food promotion efforts with potential for providing health, biodiversity and other benefits of island foods to populations in the FSM and other countries. PMID:20968235

  7. Role of silver nanoparticles in the laser-induced reversible colour-marking and controlled crystallization of mesoporous titania films

    NASA Astrophysics Data System (ADS)

    Crespo-Monteiro, N.; Destouches, N.; Gamet, E.; Bois, L.; Chassagneux, F.; Nadar, L.; Vocanson, F.

    2011-10-01

    Due to their surface plasmon resonance silver nanoparticles are known to absorb visible light and give glasses various colors. Grown in mesoporous titania films, they give the material a photochromic behaviour that can be used to produce rewritable data carriers. On the one hand, UV light forms silver nanoparticles thanks to the photo-induced generation of electrons by titania matrix. On the other hand, visible light oxidizes the silver nanoparticles via the photoexcitation of electrons on Ag and their stabilization by oxygen molecules. The well controlled porosity of the mesoporous films allows to tune the nanoparticles size and to obtain, under UV illumination, homogenous distributions of small nanoparticles embedded within the titania matrix, which color the films. As all nanoparticles absorb light similarly, the film can then be completely bleached under exposure to a visible laser beam whose wavelength falls in the SPR band of the particles. Therefore, CW UV and visible focused-laser radiations, respectively, can repeatedly print and completely erase colored micropatterns within TiO2/Ag films. The paper shows patterns printed under different conditions, deals with the reproducibility of the process and the inscription stability, and explains the nanoscale mechanisms, including silver migration during exposures, leading to the reversible color changes on the basis of TEM, SEM, absorption spectroscopy and Raman micro-spectroscopy characterizations. This paper also evidences that CW laser illuminations at higher intensity locally crystallize the titania matrix and investigates the influence of the absorption-induced heating around nanoparticles.

  8. Synthesis of Silver Nanostructures by Multistep Methods

    PubMed Central

    Zhang, Tong; Song, Yuan-Jun; Zhang, Xiao-Yang; Wu, Jing-Yuan

    2014-01-01

    The shape of plasmonic nanostructures such as silver and gold is vital to their physical and chemical properties and potential applications. Recently, preparation of complex nanostructures with rich function by chemical multistep methods is the hotspot of research. In this review we introduce three typical multistep methods to prepare silver nanostructures with well-controlled shapes, including the double reductant method, etching technique and construction of core-shell nanostructures. The growth mechanism of double the reductant method is that different favorable facets of silver nanocrystals are produced in different reductants, which can be used to prepare complex nanostructures such as nanoflags with ultranarrow resonant band bandwidth or some silver nanostructures which are difficult to prepare using other methods. The etching technique can selectively remove nanoparticles to achieve the aim of shape control and is widely used for the synthesis of nanoflowers and hollow nanostructures. Construction of core-shell nanostructures is another tool to control shape and size. The three methods can not only prepare various silver nanostructures with well-controlled shapes, which exhibit unique optical properties, such as strong surface-enhanced Raman scattering (SERS) signal and localized surface plasmon resonance (LSPR) effect, but also have potential application in many areas. PMID:24670722

  9. Cytotoxicity and genotoxicity of biogenic silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Lima, R.; Feitosa, L. O.; Ballottin, D.; Marcato, P. D.; Tasic, L.; Durán, N.

    2013-04-01

    Biogenic silver nanoparticles with 40.3 ± 3.5 nm size and negative surface charge (- 40 mV) were prepared with Fusarium oxysporum. The cytotoxicity of 3T3 cell and human lymphocyte were studied by a TaliTM image-based cytometer and the genotoxicity through Allium cepa and comet assay. The results of BioAg-w (washed) and BioAg-nw (unwashed) biogenic silver nanoparticles showed cytotoxicity exceeding 50 μg/mL with no significant differences of response in 5 and 10 μg/mL regarding viability. Results of genotoxicity at concentrations 5.0 and 10.0 ug/mL show some response, but at concentrations 0.5 and 1.0 μg/mL the washed and unwashed silver nanoparticles did not present any effect. This in an important result since in tests with different bacteria species and strains, including resistant, MIC (minimal inhibitory concentration) had good answers at concentrations less than 1.9 μg/mL. This work concludes that biogenic silver nanoparticles may be a promising option for antimicrobial use in the range where no cyto or genotoxic effect were observed. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other cells.

  10. Characterization of antibacterial silver coated yarns.

    PubMed

    Pollini, M; Russo, M; Licciulli, A; Sannino, A; Maffezzoli, A

    2009-11-01

    Surface treatments of textile fibers and fabrics significantly increase their performances for specific biomedical applications. Nowadays, silver is the most used antibacterial agent with a number of advantages. Among them, it is worth to note the high degree of biocompatibility, an excellent resistance to sterilization conditions, antibacterial properties with respect to different bacteria associated with a long-term of antibacterial efficiency. However, there are only a few antibacterial fibres available, mainly synthetic with high production cost and limited effectiveness. Cotton yarns with antimicrobial properties are most suitable for wound healing applications and other medical treatments thanks to their excellent moisture absorbance while synthetic based fibres are most suitable for industrial applications such as automotive tapestry and air filters. The silver-coated fibers were developed applying an innovative and low cost silver deposition technique for natural and synthetic fibers or yarns. The structure and morphology of the silver nanoclusters on the fibers was observed by scanning electron microscopy (SEM), atomic force microscopy analysis (AFM) and XRD analysis, and quantitatively confirmed by thermogravimetric analysis (TGA) measurements. Good silver coating stability has been confirmed performing several industrial washing. Antimicrobial tests with Escherichia coli were performed. PMID:19526328

  11. 78 FR 58880 - Safety Zone; Catawba Island Club Wedding Event, Catawba Island Club, Catawba Island, OH

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-25

    ... DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking TFR... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Catawba Island Club Wedding Event, Catawba Island Club, Catawba Island, OH ACTION: Temporary final rule. SUMMARY: The Coast Guard is...

  12. Effect of silver nanoparticles on the DC conductivity in chitosan-silver triflate polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Aziz, Shujahadeen B.; Abidin, Z. H. Z.; Arof, A. K.

    2010-11-01

    A solid polymer electrolyte composed of chitosan and silver triflate (AgCF 3SO 3) has been prepared by the solution cast technique. The formation of polymer-salt complex has been confirmed by X-ray diffraction. The DC electrical conductivity of chitosan-silver triflate electrolyte has been investigated between 303 and 423 K, using electrochemical impedance spectroscopy over the frequency range from 50 Hz to 1000 kHz. The conductivity was found to increase with increase in AgCF 3SO 3 concentration at room temperature. The DC conductivity obeys Arrhenius relationship up to a particular temperature and decreases at higher temperatures due to decrease in silver ions as a result of the formation of silver nanoparticles. The presence of an additional semicircular arc in the Cole-Cole plot obtained above 328 K indicates the existence of grain boundaries, which can be attributed to the silver particles. The presence of silver particles also have been proven by XRD after heating at 333, 363, and 393 K where the (1 1 1) peak of Ag is observed to increase with temperature. The silver particles were shown to be of nanosize using transmission electron microscopy (TEM).

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

    PubMed

    Tseng, Kuo-Hsiung; Liao, Chih-Yu

    2011-03-01

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

  14. Comparison of in vitro toxicity of silver ions and silver nanoparticles on human hepatoma cells.

    PubMed

    Vrček, Ivana Vinković; Žuntar, Irena; Petlevski, Roberta; Pavičić, Ivan; Dutour Sikirić, Maja; Ćurlin, Marija; Goessler, Walter

    2016-06-01

    Scientific information on the potential harmful effects of silver nanoparticles (AgNPs) on human health severely lags behind their exponentially growing applications in consumer products. In assessing the toxic risk of AgNP usage, liver, as a detoxifying organ, is particularly important. The aim of this study was to explore the toxicity mechanisms of nano and ionic forms of silver on human hepatoblastoma (HepG2) cells. The results showed that silver ions and citrate-coated AgNPs reduced cell viability in a dose-dependent manner. The IC50 values of silver ions and citrate-coated AgNPs were 0.5 and 50 mg L(-1) , respectively. The LDH leakage and inhibition of albumin synthesis, along with decreased ALT activity, indicated that treatment with either AgNP or Ag ions resulted in membrane damage and reduced the cell function of human liver cells. Evaluation of oxidative stress markers demonstrating depletion of GSH, increased ROS production, and increased SOD activity, indicated that oxidative stress might contribute to the toxicity effects of nano and ionic forms of silver. The observed toxic effect of AgNP on HepG2 cells was substantially weaker than that caused by ionic silver, while the uptake of nano and ionic forms of silver by HepG2 cells was nearly the same. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 679-692, 2016. PMID:25448069

  15. Autocatalytic Patterning with Silver Using Tin(II) Chloride Sensitizer

    ERIC Educational Resources Information Center

    Mbindyo, Jeremiah K. N.; Anna, Laura J.; Fell, B. Andrew; Patton, David A.

    2011-01-01

    A silver mirror can be deposited on many types of surfaces from the reduction of the silver-diammine complex by a reducing sugar as proposed by Kemp in this "Journal". Three extensions of Kemp's demonstration that highlight the role of SnCl[subscript 2] sensitizer in the deposition of a silver mirror on surfaces are presented. The demonstration…

  16. Endogenous and exogenous ocular and systemic silver deposition.

    PubMed

    Spencer, W H; Garron, L K; Contreras, F; Hayes, T L; Lai, C

    1980-04-01

    The ocular distribution of particulate silver after prolonged ingestion and the topical application of an organic silver compound (argyrol) are described and compared with the distribution after long-term occupational contact with refined silver. The deposits appear to be inert and to cause no functional visual deficit.

  17. Silver Dissolution and Release from Ceramic Water Filters.

    PubMed

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

    2015-07-21

    Application of silver nanoparticles (nAg) or silver nitrate (AgNO3) has been shown to improve the microbiological efficacy of ceramic water filters used for household water treatment. Silver release, however, can lead to undesirable health effects and reduced filter effectiveness over time. The objectives of this study were to evaluate the contribution of nanoparticle detachment, dissolution, and cation exchange to silver elution, and to estimate silver retention under different influent water chemistries. Dissolved silver (Ag(+)) and nAg release from filter disks painted with 0.03 mg/g casein-coated nAg or AgNO3 were measured as a function of pH (5-9), ionic strength (1-50 mM), and cation species (Na(+), Ca(2+), Mg(2+)). Silver elution was controlled by dissolution as Ag(+) and subsequent cation exchange reactions regardless of the applied silver form. Effluent silver levels fell below the drinking water standard (0.1 mg/L) after flushing with 30-42 pore volumes of pH 7, 10 mM NaNO3 at pH 7. When the influent water was at pH 5, contained divalent cations or 50 mM NaNO3, silver concentrations were 5-10 times above the standard. Our findings support regular filter replacement and indicate that saline, hard, or acidic waters should be avoided to minimize effluent silver concentrations and preserve silver treatment integrity. PMID:26068303

  18. Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray (Final Report)

    EPA Science Inventory

    silver_cover.jpg" vspace = "5" hspace="5" align="right" border="2" alt="Cover of the Nanoscale Silver Final report"> This final report presents a case study of engineered nanoscale silver (nano-Ag), focusing on...

  19. 16 CFR 23.6 - Misrepresentation as to silver content.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Misrepresentation as to silver content. 23.6... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.6 Misrepresentation as to silver content. (a) It is unfair or deceptive to misrepresent that an industry product contains silver, or to misrepresent...

  20. 25 CFR 304.3 - Classifying and marking of silver.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 2 2014-04-01 2014-04-01 false Classifying and marking of silver. 304.3 Section 304.3 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.3 Classifying and marking of silver. For the present the Indian Arts and Crafts...

  1. 25 CFR 304.7 - Eligibility of silver meeting standards.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 2 2014-04-01 2014-04-01 false Eligibility of silver meeting standards. 304.7 Section 304.7 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.7 Eligibility of silver meeting standards. In addition to...

  2. 33 CFR 13.01-10 - Gold and silver bars.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Gold and silver bars. 13.01-10... DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-10 Gold and silver bars. No person shall receive more than one Gold Lifesaving Medal and...

  3. 25 CFR 304.7 - Eligibility of silver meeting standards.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 2 2013-04-01 2013-04-01 false Eligibility of silver meeting standards. 304.7 Section 304.7 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.7 Eligibility of silver meeting standards. In addition to...

  4. 16 CFR 23.6 - Misrepresentation as to silver content.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Misrepresentation as to silver content. 23.6... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.6 Misrepresentation as to silver content. (a) It is unfair or deceptive to misrepresent that an industry product contains silver, or to misrepresent...

  5. 33 CFR 13.01-10 - Gold and silver bars.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Gold and silver bars. 13.01-10... DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-10 Gold and silver bars. No person shall receive more than one Gold Lifesaving Medal and...

  6. 16 CFR 23.6 - Misrepresentation as to silver content.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Misrepresentation as to silver content. 23.6... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.6 Misrepresentation as to silver content. (a) It is unfair or deceptive to misrepresent that an industry product contains silver, or to misrepresent...

  7. 16 CFR 23.6 - Misrepresentation as to silver content.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Misrepresentation as to silver content. 23.6... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.6 Misrepresentation as to silver content. (a) It is unfair or deceptive to misrepresent that an industry product contains silver, or to misrepresent...

  8. 25 CFR 304.7 - Eligibility of silver meeting standards.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 2 2012-04-01 2012-04-01 false Eligibility of silver meeting standards. 304.7 Section 304.7 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.7 Eligibility of silver meeting standards. In addition to...

  9. 21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 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 §...

  10. 25 CFR 304.7 - Eligibility of silver meeting standards.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Eligibility of silver meeting standards. 304.7 Section 304.7 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.7 Eligibility of silver meeting standards. In addition to...

  11. 25 CFR 304.3 - Classifying and marking of silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Classifying and marking of silver. 304.3 Section 304.3 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.3 Classifying and marking of silver. For the present the Indian Arts and Crafts...

  12. 21 CFR 524.802 - Enrofloxacin, silver sulfadiazine emulsion.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 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 §...

  13. 16 CFR 23.6 - Misrepresentation as to silver content.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Misrepresentation as to silver content. 23.6... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.6 Misrepresentation as to silver content. (a) It is unfair or deceptive to misrepresent that an industry product contains silver, or to misrepresent...

  14. 25 CFR 304.7 - Eligibility of silver meeting standards.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 2 2011-04-01 2011-04-01 false Eligibility of silver meeting standards. 304.7 Section 304.7 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.7 Eligibility of silver meeting standards. In addition to...

  15. 25 CFR 304.3 - Classifying and marking of silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 2 2011-04-01 2011-04-01 false Classifying and marking of silver. 304.3 Section 304.3 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.3 Classifying and marking of silver. For the present the Indian Arts and Crafts...

  16. 25 CFR 304.3 - Classifying and marking of silver.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 2 2012-04-01 2012-04-01 false Classifying and marking of silver. 304.3 Section 304.3 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.3 Classifying and marking of silver. For the present the Indian Arts and Crafts...

  17. 25 CFR 304.3 - Classifying and marking of silver.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 2 2013-04-01 2013-04-01 false Classifying and marking of silver. 304.3 Section 304.3 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER, USE OF GOVERNMENT MARK § 304.3 Classifying and marking of silver. For the present the Indian Arts and Crafts...

  18. Antimicrobial efficacy and ocular cell toxicity from silver nanoparticles

    PubMed Central

    Santoro, Colleen M.; Duchsherer, Nicole L.

    2009-01-01

    Silver in various forms has long been recognized for antimicrobial properties, both in biomedical devices and in eyes. However, soluble drugs used on the ocular surface are rapidly cleared through tear ducts and eventually ingested, resulting in decreased efficacy of the drug on its target tissue and potential concern for systemic side effects. Silver nanoparticles were studied as a source of anti-microbial silver for possible controlled-release contact lens controlled delivery formulations. Silver ion release over a period of several weeks from nanoparticle sources of various sizes and doses in vitro was evaluated in vitro against Pseudomonas aeruginosa strain PA01. Mammalian cell viability and cytokine expression in response to silver nanoparticle exposure is evaluated using corneal epithelial cells and eye-associated macrophages cultured in vitro in serum-free media. Minimal microcidal and cell toxic effects were observed for several silver nanoparticle suspensions and aqueous extraction times for bulk total silver concentrations commensurate with comparative silver ion (e.g., Ag+(aq)) toxicity. This indicates that (1) silver particles themselves are not microcidal under conditions tested, and (2) insufficient silver ion is generated from these particles at these loadings to produce observable biological effects in these in vitro assays. If dosing allows substantially increased silver particle loading in the lens, the bactericidal efficacy of silver nanoparticles in vitro is one possible approach to limiting bacterial colonization problems associated with extended-wear contact lenses. PMID:19865601

  19. Silver plating ensures reliable diffusion bonding of dissimilar metals

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Dissimilar metals are reliably joined by diffusion bonding when the surfaces are electroplated with silver. The process involves cleaning and etching, anodization, silver striking, and silver plating with a conventional plating bath. It minimizes the formation of detrimental intermetallic phases and provides greater tolerance of processing parameters.

  20. 33 CFR 13.01-10 - Gold and silver bars.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Gold and silver bars. 13.01-10... DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-10 Gold and silver bars. No person shall receive more than one Gold Lifesaving Medal and...

  1. 33 CFR 13.01-10 - Gold and silver bars.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Gold and silver bars. 13.01-10... DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-10 Gold and silver bars. No person shall receive more than one Gold Lifesaving Medal and...

  2. 33 CFR 13.01-10 - Gold and silver bars.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Gold and silver bars. 13.01-10... DECORATIONS, MEDALS, RIBBONS AND SIMILAR DEVICES Gold and Silver Lifesaving Medals, Bars, and Miniatures § 13.01-10 Gold and silver bars. No person shall receive more than one Gold Lifesaving Medal and...

  3. Low-Temperature Bonding of Silver to Aluminum

    NASA Astrophysics Data System (ADS)

    Yasuda, Yusuke; Terada, Shohei; Morita, Toshiaki; Kawaji, Hitoshi

    2012-02-01

    Direct bonding of silver to aluminum was achieved using silver-oxide particles with silver acetate (CH3COOAg) as a bonding material. When silver acetate was used, it reduced the silver oxide, and the resulting silver powder was sintered at 190 °C. In contrast, when silver oxide alone was used, the reduction and sintering required a temperature of 400 °C. The shear strength of the bonds formed with the silver-oxide/silver-acetate joining medium increased with increasing bonding temperature; for example, 2.5 min holding at 400 °C in air under a bonding pressure of 2.5 MPa yielded an average shear strength of 9 MPa. As confirmed by cross-sectional transmission electron microscopy equipped with electron-energy-loss spectroscopy (TEM-EELS), the bonding of sintered silver to aluminum was achieved through an aluminum-oxide layer formed on the aluminum. This bonding of sintered silver to aluminum oxide at a temperature of 400 °C or less is thought to be due to the large amount of heat (680 J/g) generated by the combustion of CH3 radicals in silver acetate during sintering.

  4. Silver Dissolution and Release from Ceramic Water Filters.

    PubMed

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

    2015-07-21

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

  5. Physicochemical properties of protein-modified silver nanoparticles in seawater

    NASA Astrophysics Data System (ADS)

    Zhong, Hangyue

    2013-10-01

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

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

    PubMed Central

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

    2013-01-01

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

  7. The inhibitory effects of silver nanoparticles, silver ions, and silver chloride colloids on microbial growth.

    PubMed

    Choi, Okkyoung; Deng, Kathy Kanjun; Kim, Nam-Jung; Ross, Louis; Surampalli, Rao Y; Hu, Zhiqiang

    2008-06-01

    Emerging nanomaterials are of great concern to wastewater treatment utilities and the environment. The inhibitory effects of silver nanoparticles (Ag NPs) and other important Ag species on microbial growth were evaluated using extant respirometry and an automatic microtiter fluorescence assay. Using autotrophic nitrifying organisms from a well-controlled continuously operated bioreactor, Ag NPs (average size=14+/-6 nm), Ag(+) ions (AgNO(3)), and AgCl colloids (average size=0.25 microm), all at 1mg/L Ag, inhibited respiration by 86+/-3%, 42+/-7%, and 46+/-4%, respectively. Based on a prolonged microtiter assay, at about 0.5mg/L Ag, the inhibitions on the growth of Escherichia coli PHL628-gfp by Ag NPs, Ag(+) ions, and AgCl colloids were 55+/-8%, 100%, and 66+/-6%, respectively. Cell membrane integrity was not compromised under the treatment of test Ag species by using a LIVE/DEAD Baclight bacterial viability assay. However, electron micrographs demonstrated that Ag NPs attached to the microbial cells, probably causing cell wall pitting. The results suggest that nitrifying bacteria are especially susceptible to inhibition by Ag NPs, and the accumulation of Ag NPs could have detrimental effects on the microorganisms in wastewater treatment.

  8. Multif requency three-dimensional optical read-only memory disks using metallic island films: preliminary experiments.

    PubMed

    Baba, K; Yamada, R; Nakao, S; Miyagi, M

    1993-06-10

    Basic operation of new multifrequency three-dimensional (3-D) optical read-only memory (ROM) disks has been demonstrated experimentally. Several types of metallic island film exhibiting a selectiveresonance absorption in a visible-near infrared region are used as recording layers on the 3-D disks. The monochromatic light with a suitable wavelength near the resonance wavelength of each layer is used for the readout of information. We demonstrate that bar-code patterns recorded in silver and copper island layers can be read by using transmitted or reflected light. Furthermore, we also show that the 3-D disks with ≥3 recording layers can be realized. PMID:20829926

  9. LOUISIANA BARRIER ISLAND EROSION STUDY.

    USGS Publications Warehouse

    Sallenger,, Asbury H.; Penland, Shea; Williams, S. Jeffress; Suter, John R.

    1987-01-01

    During 1986, the U. S. Geological Survey and the Louisiana Geological Survey began a five-year cooperative study focused on the processes which cause erosion of barrier islands. These processes must be understood in order to predict future erosion and to better manage our coastal resources. The study area includes the Louisiana barrier islands which serve to protect 41% of the nation's wetlands. These islands are eroding faster than any other barrier islands in the United States, in places greater than 20 m/yr. The study is divided into three parts: geological development of barrier islands, quantitative processes of barrier island erosion and applications of results. The study focuses on barrier islands in Louisiana although many of the results are applicable nationwide.

  10. Light splitting in nanoporous gold and silver.

    PubMed

    Bosman, Michel; Anstis, Geoffrey R; Keast, Vicki J; Clarke, Jackson D; Cortie, Michael B

    2012-01-24

    Nanoporous gold and silver exhibit strong, omnidirectional broad-band absorption in the far-field. Even though they consist entirely of gold or silver atoms, these materials appear black and dull, in great contrast with the familiar luster of continuous gold and silver. The nature of these anomalous optical characteristics is revealed here by combining nanoscale electron energy loss spectroscopy with discrete dipole and boundary element simulations. It is established that the strong broad-band absorption finds its origin in nanoscale splitting of light, with great local variations in the absorbed color. This nanoscale polychromaticity results from the excitation of localized surface plasmon resonances, which are imaged and analyzed here with deep sub-wavelength, nanometer spatial resolution. We demonstrate that, with this insight, it is possible to customize the absorbance and reflectance wavelength bands of thin nanoporous films by only tuning their morphology.

  11. Modifications to the silver physical developer.

    PubMed

    Burow, David; Seifert, Donald; Cantu, Antonio A

    2003-09-01

    The silver physical developer is currently the most successful reagent used for visualizing the water-insoluble components (e.g., lipids) of latent prints on porous surfaces. It is normally used after the amino acid visualizing reagents (e.g., ninhydrin and DFO) are used. This work found that the performance of the current formulation of silver physical developer is strongly reduced when the water used is changed from the usual distilled water to the more purified reverse osmosis/deionized (RO/DI) water. Based on numerous experiments involving the systematic variation of the component concentrations, the performance was restored and even improved by reducing the concentration of all the components (except that of the ferric salt) and by including malic acid in the formulation. These modifications resulted in a new silver physical developer formulation that performs as well as or better than the current formulation and is less expensive to make.

  12. Nanosecond laser ablation of silver nanoparticle film

    NASA Astrophysics Data System (ADS)

    Chung, Jaewon; Han, Sewoon; Lee, Daeho; Ahn, Sanghoon; Grigoropoulos, Costas P.; Moon, Jooho; Ko, Seung H.

    2013-02-01

    Nanosecond laser ablation of polyvinylpyrrolidone (PVP) protected silver nanoparticle (20 nm diameter) film is studied using a frequency doubled Nd:YAG nanosecond laser (532 nm wavelength, 6 ns full width half maximum pulse width). In the sintered silver nanoparticle film, absorbed light energy conducts well through the sintered porous structure, resulting in ablation craters of a porous dome shape or crown shape depending on the irradiation fluence due to the sudden vaporization of the PVP. In the unsintered silver nanoparticle film, the ablation crater with a clean edge profile is formed and many coalesced nanoparticles of 50 to 100 nm in size are observed inside the ablation crater. These results and an order of magnitude analysis indicate that the absorbed thermal energy is confined within the nanoparticles, causing melting of nanoparticles and their coalescence to larger agglomerates, which are removed following melting and subsequent partial vaporization.

  13. Immunogold-silver staining by capillary action.

    PubMed

    Kumar, R K; Braye, S G; Crouch, R L

    1989-12-01

    The authors have developed an improved method for immunogold-silver staining of paraffin sections. Using a manual capillary action staining system, they were able to simplify the technical aspects of the procedure, permitting rapid processing of large batches of slides with better reproducibility. Background staining was decreased by use of buffers containing a detergent. The use of a light-stable silver reagent permitted greater control of the enhancement stage. The method yielded a high degree of contrast with negligible nonspecific staining. Sensitivity was comparable to that obtained with conventional enzymatic immunostaining. However, the authors noted that trypsinization of sections was rendered unnecessary for those antigens for which such pretreatment was usually required, and the need for special fixatives could be eliminated. The method was also applicable to immunostaining of frozen sections. Immunogold-silver staining by capillary action deserves consideration as an alternative to existing immunohistochemical methods in diagnostic histopathology.

  14. Inkjet printing of nanosized silver colloids.

    PubMed

    Lee, Hsien-Hsueh; Chou, Kan-Sen; Huang, Kuo-Cheng

    2005-10-01

    A water-based conducting ink, composed of well dispersed nano-silver particles, has been successfully inkjet printed using an ordinary commercial printer. The silver colloids with diameter around 50 nm were dispersed in a water and diethylene glycol cosolvent system. The 25 wt% silver ink had a viscosity of about 7.4 cP and surface tension of 33.5 dyn cm(-1) at 20 degrees C, which is appropriate for printing jobs. Continuous and smooth lines of 130 microm width could be printed on ordinary glass substrates using an Epson R210 printer. After baking at 260 degrees C for 3 min, these lines exhibited a resistivity of 1.6 x 10(-5) Omega cm, which could serve as conducting lines for electronic applications.

  15. Hydrogels made from chitosan and silver nitrate.

    PubMed

    Kozicki, Marek; Kołodziejczyk, Marek; Szynkowska, Małgorzata; Pawlaczyk, Aleksandra; Leśniewska, Ewa; Matusiak, Aleksandra; Adamus, Agnieszka; Karolczak, Aleksandra

    2016-04-20

    This work describes a gelation of chitosan solution with silver nitrate. Above the critical concentration of chitosan (c*), continuous hydrogels of chitosan-silver can be formed. At lower concentrations, the formation of nano- and micro-hydrogels is discussed. The sol-gel analysis was performed to characterise the hydrogels' swelling properties. Moreover, the following were employed: (i) mechanical testing of hydrogels, (ii) inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the measurement of silver concentration, (iii) scanning electron microscopy (SEM) to examine the morphology of products obtained, and (iv) dynamic light scattering (DLS) and UV-vis spectrophotometry to examine products formed at low concentration of chitosan (c

  16. Silver nanowires-templated metal oxide for broadband Schottky photodetector

    NASA Astrophysics Data System (ADS)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-04-01

    Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W-1) and detectivity (2.75 × 1015 Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxide devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.

  17. Silver indium diphosphate, AgInP(2)O(7).

    PubMed

    Zouihri, Hafid; Saadi, Mohamed; Jaber, Boujemaa; El Ammari, Lehcen

    2010-01-01

    Polycrystalline material of the title compound, AgInP(2)O(7), was synthesized by traditional high-temperature solid-state methods and single crystals were grown from the melt of a mixture of AgInP(2)O(7) and B(2)O(3) as flux in a platinium crucible. The structure consists of InO(6) octa-hedra, which are corner-shared to PO(4) tetra-hedra into a three-dimensional network with hexa-gonal channels running parallel to the c axis. The silver cation, located in the channel, is bonded to seven O atoms of the [InP(2)O(7)] framework with Ag-O distances ranging from 2.370 (2) to 3.015 (2) Å. The P(2)O(7) diphosphate anion is characterized by a P-O-P angle of 137.27 (9) and a nearly eclipsed conformation. AgInP(2)O(7) is isotypic with the M(I)FeP(2)O(7) (M(I) = Na, K, Rb, Cs and Ag) diphosphate family. PMID:21522510

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

    USGS Publications Warehouse

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

    2004-01-01

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

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

    SciTech Connect

    Covert, Timothy Todd

    2014-09-01

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

  20. Presence of nanoparticles in wash water from conventional silver and nano-silver textiles.

    PubMed

    Mitrano, Denise M; Rimmele, Elisa; Wichser, Adrian; Erni, Rolf; Height, Murray; Nowack, Bernd

    2014-07-22

    Questions about how to regulate nanoenhanced products regularly arise as researchers determine possible nanoparticle transformation(s). Focusing concern on the incorporation and subsequent release of nano-Ag in fabrics often overshadows the fact that many "conventional silver" antimicrobials such as ionic silver, AgCl, metallic Ag, and other forms will also form different species of silver. In this study we used a laboratory washing machine to simulate the household laundering of a number of textiles prepared with known conventional Ag or nano-Ag treatments and a commercially available fabric incorporating yarns coated with bulk metallic Ag. Serial filtration allowed for quantification of total Ag released in various size fractions (>0.45 μm, < 0.45 μm, <0.1 μm, and <10 kDa), while characterization of particles with TEM/EDX provided insight on Ag transformation mechanisms. Most conventional Ag additives yielded more total Ag and more nanoparticulate-sized Ag in the washing liquid than fabrics that used nano-Ag treatments. Incorporating nano-silver into the fiber (as opposed to surface treatments) yielded less total Ag during fabric washing. A variety of metallic Ag, AgCl, and Ag/S particles were observed in washing solution by TEM/EDX to various extents depending on the initial Ag speciation in the fabrics. Very similar particles were also observed when dissolved ionic Ag was added directly into the washing liquid. On the basis of the present study, we can state that all silver-treated textiles, regardless of whether the treatment is "conventional" or "nano", can be a source of silver nanoparticles in washing solution when laundering fabrics. Indeed, in this study we observed that textiles treated with "conventional" silver have equal or greater propensity to form nano-silver particles during washing conditions than those treated with "nano"-silver. This fact needs to be strongly considered when addressing the risks of nano-silver and emphasizes that regulatory

  1. FLANDERS FIELDS MEMORIAL IN TRAFFIC ISLAND ON EAST DRIVE. VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FLANDERS FIELDS MEMORIAL IN TRAFFIC ISLAND ON EAST DRIVE. VIEW TO NORTHEAST. - Rock Island National Cemetery, Rock Island Arsenal, 0.25 mile north of southern tip of Rock Island, Rock Island, Rock Island County, IL

  2. Landscapes of Santa Rosa Island, Channel Islands National Park, California

    USGS Publications Warehouse

    Schumann, R. Randall; Minor, Scott A.; Muhs, Daniel R.; Pigati, Jeffery S.

    2014-01-01

    Santa Rosa Island (SRI) is the second-largest of the California Channel Islands. It is one of 4 east–west aligned islands forming the northern Channel Islands chain, and one of the 5 islands in Channel Islands National Park. The landforms, and collections of landforms called landscapes, of Santa Rosa Island have been created by tectonic uplift and faulting, rising and falling sea level, landslides, erosion and deposition, floods, and droughts. Landscape features, and areas delineating groups of related features on Santa Rosa Island, are mapped, classified, and described in this paper. Notable landscapes on the island include beaches, coastal plains formed on marine terraces, sand dunes, and sand sheets. In this study, the inland physiography has been classified into 4 areas based on relief and degree of fluvial dissection. Most of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep- to vertical-walled arroyos, or barrancas, leaving a relict floodplain above the present channel. A better understanding of the processes and mechanisms that created these landscapes enhances visitors’ enjoyment of their surroundings and contributes to improving land and resource management strategies in order to optimize and balance the multiple goals of conservation, preservation, restoration, and visitor experience.

  3. Assembling silver nanowires using optoelectronic tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Shuailong; Cooper, Jonathan M.; Neale, Steve L.

    2016-03-01

    Light patterned dielectrophoresis or optoelectronic tweezers (OET) has been proved to be an effective micromanipulation technology for cell separation, cell sorting and control of cell interactions. Apart from being useful for cell biology experiments, the capability of moving small objects accurately also makes OET an attractive technology for other micromanipulation applications. In particular, OET has the potential to be used for efficiently and accurately assembling small optoelectronic/electronic components into circuits. This approach could produce a step change in the size of the smallest components that are routinely assembled; down from the current smallest standard component size of 400×200 μm (0402 metric) to components a few microns across and even nanostructured components. In this work, we have demonstrated the use of OET to manipulate conductive silver nanowires into different patterns. The silver nanowires (typical diameter: 60 nm; typical length: 10 μm) were suspended in a 15 mS/m solution of KCL in water and manipulated by positive dielectrophoresis force generated by OET. A proof-of-concept demonstration was also made to prove the feasibility of using OET to manipulate silver nanowires to form a 150-μm-long conductive path between two isolated electrodes. It can be seen that the resistance between two electrodes was effectively brought down to around 700 Ω after the silver nanowires were assembled and the solution evaporated. Future work in this area will focus on increasing the conductivity of these tracks, encapsulating the assembled silver nanowires to prevent silver oxidation and provide mechanical protection, which can be achieved via 3D printing and inkjet printing technology.

  4. Innovative method to avoid the reduction of silver ions to silver nanoparticles \\left( A{{g}^{+}}\\to Ag{}^\\circ \\right) in silver ion conducting based polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Aziz, Shujahadeen B.; Abidin, Zul Hazrin Z.; Kadir, M. F. Z.

    2015-03-01

    In this research work an innovative method is used to prevent the silver ion reduction in solid polymer electrolytes. The x-ray diffraction (XRD) results reveal the disruption of the crystalline nature of chitosan (CS) and formation of silver nanoparticles upon addition of silver triflate (AgTf) salt. The UV-vis measurement confirms the existence of silver nanoparticles via the broad surface plasmon resonance (SPR) peak. Upon the addition of Al2O3 nanoparticles the SPR peak intensity is greatly reduced. The amorphous domain of the CS:silver triflate (CS:AgTf) system increases with the addition of Al2O3 nanoparticles up to 4 wt.%. Deconvolution of the XRD results reveals that a larger crystallite size is obtained for higher Al2O3 concentrations and the peaks due to silver nanoparticles almost disappear. Scanning electron microscope (SEM) analyses show that Al2O3 nanoparticles are well dispersed at low concentrations and the leakage of chains of silver nanoparticles to the membrane surface almost disappear. The XRD, UV-vis, SEM and energy-dispersive x-ray (EDX) results strongly support that the reduction of silver ions to silver nanoparticles (Ag+ → Ag°) in the CS:silver triflate system is significantly avoided upon the addition of an Al2O3 filler.

  5. Comparison of the potential dependence of the surface-enhanced raman effect at colloid silver particles and bulk silver electrodes

    NASA Astrophysics Data System (ADS)

    Wetzel, H.; Gerischer, H.; Pettinger, B.

    1982-01-01

    The potential dependence of surface-enhanccd Raman signals from pyridine adsorbed onto silver sol particles is identical to that from pyridine adsorbed on flat silver electrodes. Variation of the potential at the interface silver sol particle/electrolyte was achieved by adding the redox system europiums 3+/europium 2+ and varying the concentration ratio.

  6. 21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  7. 21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  8. 21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  9. 21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  10. 21 CFR 310.548 - Drug products containing colloidal silver ingredients or silver salts offered over-the-counter...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  11. Prevalence of silver resistance in bacteria isolated from diabetic foot ulcers and efficacy of silver-containing wound dressings.

    PubMed

    Percival, Steven L; Woods, Emma; Nutekpor, Moses; Bowler, Phil; Radford, Alan; Cochrane, Christine

    2008-03-01

    Silver dressings are used to manage wounds at risk of infection or locally infected. This in vitro study was conducted to assess the prevalence of silver resistance genes in 112 bacterial isolates obtained from the diabetic foot ulcers of patients attending the Diabetic Foot Clinic at Tameside General Hospital, UK. Using polymerase chain reaction to screen for three silver-resistance transcriptional units--silE, silS and silP--two silver-resistant bacteria were identified; both are strains of Enterobacter cloacae, an organism rarely implicated as a primary pathogen in chronic wounds. No recognized wound pathogens (Staphylococcus aureus-24 isolates and Pseudomonas aeruginosa-nine isolates) were found to contain silver-resistant genes. Analysis of the efficacy of silver-containing dressings on the silver-resistant strains of Enterobacter cloacae using confocal laser microscopy showed that, despite evidence of genetic resistance to silver, all strains were killed following a maximum of 48 hours of exposure to the dressings. Results suggest that presence of silver resistance genes is rare and that genetic resistance does not necessarily translate to phenotypic resistance to silver. While silver resistance in wound care should be monitored, the threat of widespread resistance is low and silver-containing dressings remain an extremely important tool in managing wound infection. PMID:18382046

  12. Recovery of silver from CEPOD anolyte solutions

    SciTech Connect

    Blanchard, D.L.; Surma, J.E.; Alexander, D.L.; Shade, E.H.; Matheson, J.D.; Cochran, D.L.; Wheelwright, E.J.; Boyd, T.

    1994-09-01

    The process known as Catalyzed Electrochemical Plutonium Oxide Dissolution (CEPOD) has been shown effective for removing plutonium from a variety of residues and solids. This process involves the electrochemical oxidation of PuO{sub 2} (and other Pu species) to (PuO{sub 2}){sup 2+}, and dissolution of the latter species in the anode solution (anolyte). Silver is used to transfer charge from the electrodes to the solid Pu oxide. Ag (1) is oxidized at the anode to Ag(II) and carried by the solution to the plutonium oxide solids, where the silver and oxide undergo a redox reaction that converts Pu(IV) to Pu(VI), and Ag(II) to Ag(I). Other metal ions [such as Ce(IV) and Co(III)] may also be used for this charge transfer, but have been found to be less effective than silver. The same process may be used to destroy various organic materials (such as paper and wood, oil and fuels, and synthetic polymer materials) by complete oxidation to CO{sub 2} or H{sub 2}O, for example. Upon completion of a CEPOD dissolver run, the anolyte may be processed to remove solution species of interest (i.e., Pu), or the anolyte may be recycled, or disposed. Because silver is a Resource Conservation and Recovery Act (RCRA) land ban material, it must be removed from waste streams. Preliminary experiments, completed in FY 1991, demonstrated a simple, effective technique for silver removal from solutions. Ascorbic acid (C{sub 6}H{sub 8}O{sub 6}) Was Used to reduce silver ion to metallic silver, which precipitates from solution. The process was demonstrated effective on a bench scale using samples of actual CEPOD anolyte. Further experiments, in FY 1993, optimized these parameters and demonstrated the effectiveness of the technique on CEPOD anolyte on a larger, process scale (liters of solution). This report describes both the preliminary bench-scale experiments and the more recent process-scale experiments. The results are also compared to electro-deposition, another method of silver ion removal.

  13. Silver doped catalysts for treatment of exhaust

    DOEpatents

    Park, Paul Worn [Peoria, IL; Boyer, Carrie L [Shiloh, IL

    2006-12-26

    A method of making an exhaust treatment catalyst includes dispersing a metal-based material in a first solvent to form a first slurry and allowing polymerization of the first slurry to occur. Polymerization of the first slurry may be quenched and the first slurry may be allowed to harden into a solid. This solid may be redistributed in a second solvent to form a second slurry. The second slurry may be loaded with a silver-based material, and a silver-loaded powder may be formed from the second slurry.

  14. Subchronic oral toxicity of silver nanoparticles

    PubMed Central

    2010-01-01

    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 < 0.05) in the body weight of male rats after 4 weeks of exposure, although there were no significant changes in food or water consumption during the study period. Significant dose-dependent changes were found in alkaline phosphatase and cholesterol for the male and female rats, indicating that exposure to more than 125 mg/kg of silver nanoparticles may result in slight liver damage. Histopathologic examination revealed a higher incidence of bile-duct hyperplasia, with or without necrosis, fibrosis, and/or pigmentation, in treated animals. There was also a dose-dependent accumulation of silver in all tissues examined. A gender-related difference in the accumulation of silver was noted in the kidneys, with a twofold increase in female kidneys compared to male kidneys. 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

  15. Biosynthesis of silver nanoparticles using Saccharomyces cerevisiae.

    PubMed

    Korbekandi, Hassan; Mohseni, Soudabeh; Mardani Jouneghani, Rasoul; Pourhossein, Meraj; Iravani, Siavash

    2016-01-01

    The objectives of this study were the biosynthesis of silver nanoparticles (NPs) by biotransformations using Saccharomyces cerevisiae and analysis of the sizes and shapes of the NPs produced. Dried and freshly cultured S. cerevisiae were used as the biocatalyst. Dried yeast synthesized few NPs, but freshly cultured yeast produced a large amount of them. Silver NPs were spherical, 2-20 nm in diameter, and the NPs with the size of 5.4 nm were the most frequent ones. NPs were seen inside the cells, within the cell membrane, attached to the cell membrane during the exocytosis, and outside of the cells.

  16. Optical Properties of Silver Nanoparticulate Glasses

    NASA Astrophysics Data System (ADS)

    Evans, Rachel N.; Cannavino, Sarah A.; King, Christy A.; Lamartina, Joseph A.; Magruder, Robert H.; Ferrara, Davon W.

    The ion exchange method of embedding metal nanoparticles (NPs) into float glass is an often used technique of fabricating colored glasses and graded-index waveguides. The depth and size of NP formation in the glass depends on the concentration and temperature of metal ions in the molten bath. In this study we explore the dichroic properties of silver metal ion exchange restricted to only one side of a glass microscope slide using reflection and transmission spectroscopy and its dependence on temperature, concentration of silver ions, and length of time in the molten bath.

  17. Molecule diagram from space-grown crystals

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Researchers' at Hauptman-Woodward Medical Research Institute, in Buffalo, N.Y. have analyzed the molecular structures of insulin crystals grown during Space Shuttle experiments and are unlocking the mystery of how insulin works.

  18. Growth and characteristics of self-assembly defect-free GaN surface islands by molecular beam epitaxy.

    PubMed

    Hsu, Kuang-Yuan; Wang, Cheng-Yu; Liu, Chuan-Pu

    2011-04-01

    GaN surface nano-islands of high crystal quality, without any dislocations or other extended defects, are grown on a c-plane sapphire substrate by plasma-assisted molecular beam epitaxy. Nano-island growth requires special conditions in terms of V/III ratio and substrate temperature, distinct from either film or nanocolumn growth. The insertion of a nitrided Ga layer can effectively improve the uniformity of the nano-islands in both shape and size. The islands are well faced truncated pyramids with island size ranged from 30 to 110 nm, and height ranged from 30 to 55 nm. On, the other hand, the density and facet of the GaN surface islands would be affected by the growth conditions. An increase of the V/III ratio from 30 to 40 led to an increase in density from 1.4 x 10(9) to 4.3 x 10(9) cm(-2) and an evolution from {1-21-1} facets to {1-21-2} facets. The GaN layers containing the surface islands can moderate the compressive strain due to the lattice and thermal mismatch between GaN and c-sapphire. Conductive atomic force microscopy shows that the off-axis sidewall facets are more electrically active than those at the island center. The formation of the GaN surface islands is strongly induced by the Ehrlich-Schwoebel barrier effect of preexisting islands grown in the early growth stage. GaN surface islands are ideal templates for growing nano-devices.

  19. Charge Islands Through Tunneling

    NASA Technical Reports Server (NTRS)

    Robinson, Daryl C.

    2002-01-01

    It has been recently reported that the electrical charge in a semiconductive carbon nanotube is not evenly distributed, but rather it is divided into charge "islands." This paper links the aforementioned phenomenon to tunneling and provides further insight into the higher rate of tunneling processes, which makes tunneling devices attractive. This paper also provides a basis for calculating the charge profile over the length of the tube so that nanoscale devices' conductive properties may be fully exploited.

  20. Island of Hawaii

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Three main volcanoes make up the island of Hawaii (19.5N, 155.5W): the older volcanoes Mauna Loa, Mauna Kea and the recent Kilauea seen venting steam. This color infrared image is one of a pair (see STS052-77-002) to compare the differences between color film and color infrared film. Color film presents an image as it appears to the human eye whereas color infrared imagery reduces atmospheric haze and portrays vegetation as shades of red.

  1. Silver ion bactericide system. [for Space Shuttle Orbiter potable water

    NASA Technical Reports Server (NTRS)

    Jasionowski, W. J.; Allen, E. T.

    1974-01-01

    Description of a preliminary flight prototype system which uses silver ions as the bactericide to preserve sterility of the water used for human consumption and hygiene in the Space Shuttle Orbiter. The performance of silver halide columns for passively dosing fuel cell water with silver ions is evaluated. Tests under simulated Orbiter mission conditions show that silver ion doses of 0.05 ppm are bactericidal for Pseudomonas aeruginosa and Type IIIa, the two bacteria found in Apollo potable water systems. The design of the Advance Prototype Silver Ion Water Bactericide System now under development is discussed.

  2. The combined oxidation of methanol and ethanol on silver catalysts

    SciTech Connect

    Kurina, L.N.; Gryaznov, V.M.; Gul yanova, S.G.; Plakidkin, A.A.; Vedernikov, V.I.

    1985-10-01

    The authors study the oxidation of methanol, ethanol, and mixtures of these alcohols on industrial silver-pumice and silver membrane catalysts as well as the adsorption of these alcohols on silver. The oxidation of the alcohol mixture on the industrial silver-pumice catalyst gives higher yields of both formaldehyde and acetaldehyde than in the oxidation of the alcohols taken individually. It is also shown that an increase in the rates of formaldehyde formation in the combined oxidation of methanol and ethanol was observed on the silver membrane catalyst.

  3. Nucleation and coalescence behavior for epitaxial ZnO layers on ZnO/sapphire templates grown by halide vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Fujii, Tetsuo; Yoshii, Naoki; Masuda, Rui; Tanabe, Tetsuhiro; Kamisawa, Akira; Hosaka, Shigetoshi; Kumagai, Yoshinao; Koukitu, Akinori

    2009-02-01

    The effects of growth conditions for ZnO layers grown by halide vapor phase epitaxy (HVPE) on (0 0 0 1) ZnO/sapphire templates are investigated. Micron-sized pyramidal ZnO islands nucleate on the template at the initial growth stage and each island grows differently with the process conditions. The high temperature of 1000 °C promotes a lateral growth rate and coalescence between the islands. The full-width at half-maximums (FWHMs) of X-ray rocking curves for the (0 0 0 2) and (1 0 1¯ 1) planes from a fully coalesced ZnO layer are quite narrow values below 160 arcsec. Transmission electron microscopy (TEM) reveals that screw character dislocations in the template do not propagate into the HVPE-grown layer.

  4. [Salmonella pathogenicity islands].

    PubMed

    Sırıken, Belgin

    2013-01-01

    Salmonella species are facultative intracellular pathogenic bacteria. They can invade macrophages, dendritic and epithelial cells. The responsible virulence genes for invasion, survival, and extraintestinal spread are located in Salmonella pathogenicity islands (SPIs). SPIs are thought to be acquired by horizontal gene transfer. Some of the SPIs are conserved throughout the Salmonella genus, and some of them are specific for certain serovars. There are differences between Salmonella serotypes in terms of adaptation to host cell, virulence factors and the resulting infection according to SPA presence and characteristics. The most important Salmonella virulence gene clusters are located in 12 pathogenicity islands. Virulence genes that are involved in the intestinal phase of infection are located in SPI-1 and SPI-2 and the remaining SPIs are required for intracellular survival, fimbrial expression, magnesium and iron uptake, multiple antibiotic resistance and the development of systemic infections. In addition SPIs, Sigma ss (RpoS) factors and adaptive acid tolerance response (ATR) are the other two important virulence factors. RpoS and ATR found in virulent Salmonella strains help the bacteria to survive under inappropriate conditions such as gastric acidity, bile salts, inadequate oxygen concentration, lack of nutrients, antimicrobial peptides, mucus and natural microbiota and also to live in phagosomes or phagolysosomes. This review article summarizes the data related to pathogenicity islands in Salmonella serotypes and some factors which play role in the regulation of virulence genes.

  5. Silver corrosion and sulfur detection using a quartz crystal microbalance with silver electrode surfaces

    SciTech Connect

    Zabarnick, S.; Zelesnik, P.; Whitacre, S.D.

    1996-08-01

    A quartz crystal microbalance (QCM) with silver electrodes is used for detection of sulfur and measurement of silver corrosion by sulfur in jet fuels. It is found that the device responds very sensitively to elemental sulfur by reaction at the silver surface, resulting in the formation of surface silver sulfide. It is also expected that the device will respond to hydrogen sulfide. The response of the QCM is found to depend on the fuel matrix. The presence of oxygen inhibits the surface reaction, resulting in a lower mass accumulation. It is also found that the sulfur compounds which produce a response in this test are not players in the formation of autoxidative surface deposition. It is shown that the QCM response (surface mass per unit time) is proportional to the concentration of elemental sulfur present in the fuel.

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

    PubMed

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

    2014-03-01

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

  7. Bactericidal Effect of Silver Nanoparticles on Intramacrophage Brucella abortus 544

    PubMed Central

    Alizadeh, Hamed; Salouti, Mojtaba; Shapouri, Reza

    2014-01-01

    Background: Brucellosis is an infectious disease that is caused by Brucella spp. As Brucella spp. are intramacrophage pathogens, the treatment of this infection is very difficult. On the other hand, due to the side effects of the brucellosis treatment regime, it is necessary to find new antimicrobial agents against it. Objectives: The aim of this study was to investigate the antimicrobial effect of silver nanoparticles against Brucella abortus 544 in the intramacrophage condition. Materials and Methods: The antimicrobial effect of silver nanoparticles was determined by an agar well diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of silver nanoparticles against B. abortus 544 were determined by a broth macrodilution method. The effect of time on the antimicrobial activity of silver nanoparticles was analyzed. The effect of silver nanoparticles on the intramacrophage survival of B. abortus 544 was studied on mice peritoneal macrophages. Results: The well diffusion agar study showed that silver nanoparticles have an antimicrobial effect on B. abortus 544. The MIC and MBC of silver nanoparticles against B. abortus 544 were; 6 ppm and 8 ppm, respectively. The silver nanoparticles showed antibacterial effects within 40 minutes. The results of the macrophage culture indicated that silver nanoparticles have antibacterial activity against intramacrophage B. abortus 544, and the highest efficiency was observed at a concentration of 8-10 ppm of silver nanoparticles. Conclusions: The results showed that silver nanoparticles have an antimicrobial effect against intramacrophage B. abortus 544. PMID:25147682

  8. Synthesis and characterization of silver nanoparticles in AOT microemulsion system

    NASA Astrophysics Data System (ADS)

    Zhang, Wanzhong; Qiao, Xueliang; Chen, Jianguo

    2006-11-01

    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 Ag4+ 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 1.6 nm. 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.

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

    PubMed

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

    2013-08-01

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

  10. Silver speciation in wastewater effluent, surface waters, and pore waters

    SciTech Connect

    Adams, N.W.H.; Kramer, J.R.

    1999-12-01

    Silver, inorganic sulfide, and thiol compounds were measured in municipal wastewater effluent, receiving waters, and pore waters from an anoxic lake sediment in order to predict silver speciation in these systems. The authors found submicromolar concentrations of inorganic sulfide even in fully oxic surface water. This inorganic sulfide is likely to exist in the form of colloidal metal sulfides, which have been shown to be stable under oxidizing conditions for periods of several hours. Inorganic sulfide in both the wastewater effluent and receiving waters was found to be 200 to 300 times in excess of silver concentrations, whereas inorganic sulfide in pore waters was 1,000 to 15,000 times in excess of silver concentrations. With sulfide in excess of silver, the authors predict silver sulfide complexes to dominate silver speciation. Thiols were present at low nanomolar levels in pore waters but were not detectable in wastewater effluent or receiving waters. Thiols do not appear to be important to silver speciation in these freshwater systems. Partitioning of silver into particular, colloidal, and dissolved size fractions showed that a significant proportion of silver is in the colloidal and dissolved phases. Dissolved phase concentrations were relatively constant in the treatment plant effluent and receiving waters, suggesting that silver in the <10-kDa size fraction is strongly complexed by ligands that are not significantly affected by aggregation or sorption processes.

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

    PubMed

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

    2016-08-01

    The antimicrobial impact of biogenic-synthesized silver-based nanoparticles has been the focus of increasing interest. As the antimicrobial activity of nanoparticles is highly dependent on their size and surface, the complete and adequate characterization of the nanoparticle is important. This review discusses the characterization and antimicrobial activity of biogenic synthesized silver nanoparticles and silver chloride nanoparticles. By revising the literature, there is confusion in the characterization of these two silver-based nanoparticles, which consequently affects the conclusion regarding to their antimicrobial activities. This review critically analyzes recent publications on the synthesis of biogenic silver nanoparticles and silver chloride nanoparticles by attempting to correlate the characterization of the nanoparticles with their antimicrobial activity. It was difficult to correlate the size of biogenic nanoparticles with their antimicrobial activity, since different techniques are employed for the characterization. Biogenic synthesized silver-based nanoparticles are not completely characterized, particularly the nature of capped proteins covering the nanomaterials. Moreover, the antimicrobial activity of theses nanoparticles is assayed by using different protocols and strains, which difficult the comparison among the published papers. It is important to select some bacteria as standards, by following international foundations (Pharmaceutical Microbiology Manual) and use the minimal inhibitory concentration by broth microdilution assays from Clinical and Laboratory Standards Institute, which is the most common assay used in antibiotic ones. Therefore, we conclude that to have relevant results on antimicrobial effects of biogenic silver-based nanoparticles, it is necessary to have a complete and adequate characterization of these nanostructures, followed by standard methodology in microbiology protocols. PMID:27289481

  12. Moiré superstructures of graphene on faceted nickel islands.

    PubMed

    Murata, Yuya; Petrova, Vania; Kappes, Branden B; Ebnonnasir, Abbas; Petrov, Ivan; Xie, Ya-Hong; Ciobanu, Cristian V; Kodambaka, Suneel

    2010-11-23

    Using scanning tunneling microscopy and spectroscopy, in combination with density functional theory calculations, we investigated the morphology and electronic structure of monolayer graphene grown on the (111) and (110) facets of three-dimensional nickel islands on highly oriented pyrolytic graphite substrate. We observed graphene domains exhibiting hexagonal and striped moiré patterns with periodicities of 22 and 12 Å, respectively, on (111) and (110) facets of the Ni islands. Graphene domains are also observed to grow, as single crystals, across adjacent facets and over facet boundaries. Scanning tunneling spectroscopy data indicate that the graphene layers are metallic on both Ni(111) and Ni(110), in agreement with the calculations. We attribute this behavior to a strong hybridization between the d-bands on Ni and the π-bands of carbon. Our findings point to the possibility of preparing large-area epitaxial graphene layers even on polycrystalline Ni substrates.

  13. Extracellular biosynthesis of silver nanoparticles using the fungus Fusarium semitectum

    SciTech Connect

    Basavaraja, S.; Balaji, S.D.; Lagashetty, Arunkumar; Rajasab, A.H.; Venkataraman, A.

    2008-05-06

    Development of environmental friendly procedures for the synthesis of metal nanoparticles through biological processes is evolving into an important branch of nanobiotechnology. In this paper, we report on the use of fungus 'Fusarium semitectum' for the extracellular synthesis of silver nanoparticles from silver nitrate solution (i.e. through the reduction of Ag{sup +} to Ag{sup 0}). Highly stable and crystalline silver nanoparticles are produced in solution by treating the filtrate of the fungus F. semitectum with the aqueous silver nitrate solution. The formations of nanoparticles are understood from the UV-vis and X-ray diffraction studies. Transmission electron microscopy of the silver particles indicated that they ranged in size from 10 to 60 nm and are mostly spherical in shape. Interestingly the colloidal suspensions of silver nanoparticles are stable for many weeks. Possible medicinal applications of these silver nanoparticles are envisaged.

  14. Synthesis of Silver Polymer Nanocomposites and Their Antibacterial Activity

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  15. Defect chemistry of silver selenogallate

    NASA Astrophysics Data System (ADS)

    Whittaker, Matthew Thomas

    2007-12-01

    The source of 9.3 mum absorption in silver selenogallate, AgGaSe 2 was investigated. Infrared spectrophotometric analysis of two as-received, reportedly stoichiometric, single crystals found 9.3 mum absorption coefficients of 0.109 and 0.101 cm-1. Infrared transmission of the slabs was otherwise uniform at 0.007 cm-1 through the range 6--12 gym. X-ray fluorescence measurements did not indicate an extrinsic impurity was responsible for the absorption. Intrinsic defect reactions were investigated and a Brouwer diagram was constructed to determine probable native defects. Analysis of the Brouwer diagram led to the hypothesis that the 9.3 mum absorption was caused by a native selenium vacancy. A series of heat treatments were conducted at 790°C with selenium partial pressures of 0.026, 0.040, 0.057, 0.138, and 0.243 atmospheres. Heat treatments below 0.060 atmospheres selenium partial pressure resulted in null or increased absorption at 9.3 mum up to 0.128 cm-1. Heat treatment at 0.243 atmospheres selenium partial pressure resulted in a decrease of the 9.3 mum absorption coefficient of 63% to 0.037 cm-1. A linear least-squares regression of the 9.3 mum absorption coefficient versus selenium partial pressure during heat treatment resulted in an equation for the absorption coefficient. alpha9.3mum = -0.4048 (PSe) atm -1cm-1 + 0.1322cm -1. The highest electrical resistivity of AgGaSe2 was measured at 7.6 x 1011 Ocm for a crystal with a 9.3 mum absorption coefficient of 0.037 cm-1. A linear least-squares regression of the 9.3 mum absorption coefficient versus bulk electrical resistivity resulted in an equation for the resistivity: rho = -7 x 1012 alpha9.3mumO cm2 + 1 x 1012 O cm. Thus, the electrical resistivity increases as the stoichiometric composition is approached and may be used as a measure of stoichiometry. The deleterious 9.3 mum absorption has not been entirely eliminated; however, the reduction in the 9.3 mum absorption coefficient from greater than 0.100 cm-1

  16. A new molecular silver precursor for the preparation of thin conductive silver films

    NASA Astrophysics Data System (ADS)

    Fritsch, Julia; Wisser, Florian M.; Eckhardt, Kai; Bon, Volodymyr; Mondin, Giovanni; Schumm, Benjamin; Grothe, Julia; Kaskel, Stefan

    2013-11-01

    The synthesis and characterization of a new molecular silver precursor is reported. The presented complex [Ag(DioxoNic)2]NO3 (DioxoNic=(2,2-Dimethyl-1,3-dioxolan-4-yl)methyl nicotinate) can be obtained by the reaction of silver(I) nitrate and (2,2-Dimethyl-1,3-dioxolan-4-yl)methyl nicotinate in ethanol. The product crystallizes in the monoclinic space group P21/c (No. 14). Concentrated ethanolic solutions allow the fabrication of thin films via dip coating. Using UV-irradiation and subsequent moderate temperature treatment compact films of elemental silver can be obtained. The resulting silver films show excellent electrical properties with sheet resistances down to 0.7 Ω/sq at a film thickness of 25 nm corresponding to a specific electrical resistance of 1.75×10-8 Ωm very close to the value of bulk silver. For the potential application in optoelectronic devices, the complex was tested as an ink in a soft printing process for the preparation of patterned silver films.

  17. Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction.

    PubMed

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

    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 AgNO3 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 20-30nm. 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 50wt.%. 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. PMID:25842144

  18. Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction.

    PubMed

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

    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 AgNO3 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 20-30nm. 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 50wt.%. 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.

  19. Rhizobia from Lanzarote, the Canary Islands, that nodulate Phaseolus vulgaris have characteristics in common with LMW RNA group II Sinorhizobium meliloti of Medicago, Melilotus and Trigonella from soils of mainland Spain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several isolates from nodules of Phaseolus vulgaris grown in soil of Lanzarote, an island of the Canaries, had electrophoretic LMW RNA patterns identical with a less common pattern within S. meliloti (assigned as group II) obtained from nodules of alfalfa and alfalfa-related legumes grown in northe...

  20. Plasmonic biocompatible silver-gold alloyed nanoparticles.

    PubMed

    Sotiriou, Georgios A; Etterlin, Gion Diego; Spyrogianni, Anastasia; Krumeich, Frank; Leroux, Jean-Christophe; Pratsinis, Sotiris E

    2014-11-14

    The addition of Au during scalable synthesis of nanosilver drastically minimizes its surface oxidation and leaching of toxic Ag(+) ions. These biocompatible and inexpensive silver-gold nanoalloyed particles exhibit superior plasmonic performance than commonly used pure Au nanoparticles, and as such these nanoalloys have great potential in theranostic applications.

  1. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Science Inventory

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged p...

  2. A dental cloud over a silver filling

    SciTech Connect

    Van Pelt, D.

    1990-10-01

    For 150 years, silver fillings have been used for cavities. Now some dentists are urging their colleagues to stop using the mixture because it includes mercury, which they say poses health risks. While a small group of dentists have complied, the mainstream profession says the claims are unsubstantiated.

  3. Efficacy of silver (I) antimicrobial dressings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Burn wounds, particularly those due to third and fourth degree burns, are highly susceptible to infection and scar formation. These complications can be reduced if bacterial growth is inhibited and there is a moist wound environment that promotes healing. Silver has long been known to have antimicr...

  4. Microscopical Examination of Ancient Silver Coins

    SciTech Connect

    Pistofidis, N.; Vourlias, G.; Pavlidou, El.; Stergioudis, G.; Polychroniadis, E. K.; Dilo, T.; Prifti, I.; Bilani, O.; Civici, N.; Stamati, F.; Gjongecaj, Sh.

    2007-04-23

    The microstructure of three silver coins of the IIId century B.C. from the Illyrian king Monounios, the ancient Greek city of Dyrrachion and of Korkyra was studied with XRF and microscopy. From this investigation it turned out that these coins have different chemical composition and microstructure that imply different minting method.

  5. Photochromic silver nanoparticles fabricated by sputter deposition

    SciTech Connect

    Okumu, J.; Dahmen, C.; Sprafke, A.N.; Luysberg, M.; Plessen, G. von; Wuttig, M.

    2005-05-01

    In this study a simple route to preparing photochromic silver nanoparticles in a TiO{sub 2} matrix is presented, which is based upon sputtering and subsequent annealing. The formation of silver nanoparticles with sizes of some tens of nanometers is confirmed by x-ray diffraction and transmission electron microscopy. The inhomogeneously broadened particle-plasmon resonance of the nanoparticle ensemble leads to a broad optical-absorption band, whose spectral profile can be tuned by varying the silver load and the annealing temperature. Multicolor photochromic behavior of this Ag-TiO{sub 2} system upon irradiation with laser light is demonstrated and discussed in terms of a particle-plasmon-assisted electron transfer from the silver nanoparticles to TiO{sub 2} and subsequent trapping by adsorbed molecular oxygen. The electron depletion in the nanoparticles reduces the light absorption at the wavelength of irradiation. A gradual recovery of the absorption band is observed after irradiation, which is explained with a slow thermal release of electrons from the oxygen trapping centers and subsequent capture into the nanoparticles. The recovery can be accelerated by ultraviolet irradiation; the explanation for this observation is that electrons photoexcited in the TiO{sub 2} are captured into the nanoparticles and restore the absorption band.

  6. Preventing Delamination of Silverized FEP Films

    NASA Technical Reports Server (NTRS)

    Domnikov, L.; May, J.; Gallego, R.

    1986-01-01

    Edge treatment inhibits attack by moisture. New technique prevents delamination by sealing edges where delamination starts. Samples of aluminum/FEP/silver laminate survive humidity tests and other environmental tests when edges of layers are covered by epoxy bead. Untreated laminates, in contrast, deteriorated seriously during such tests.

  7. Silver Voyage from Macro- to Nanoworld

    ERIC Educational Resources Information Center

    Soukupova, Jana; Kvitek, Libor; Kratochvilova, Martina; Panacek, Ales; Prucek, Robert; Zboril, Radek

    2010-01-01

    Nanoscience and nanotechnology currently represent one of the most rapidly developing fields of science and technology; therefore, the fundamental principles of nanoscience and nanotechnology should be understood by college and even high school students as well as by members of scientific communities. Silver, as the pioneer material in these…

  8. Silver doped catalysts for treatment of exhaust

    DOEpatents

    Park, Paul Worn; Hester, Virgil Raymond; Ragle, Christie Susan; Boyer, Carrie L.

    2009-06-02

    A method of making an exhaust treatment element includes washcoating a substrate with a slurry that includes a catalyst support material. At least some of the catalyst support material from the slurry may be transferred to the substrate, and silver metal (Ag) is dispersed within the catalyst support material.

  9. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1998-04-01

    This invention relates to a process for making filaments of metal compounds and more particularly to a process for making silver metal filaments. The United States Government has rights to this invention pursuant to Contract No. DE-AC05-8421400 with Lockheed Martin Energy Systems, Inc. awarded by the US Department of Energy.

  10. Silver oxide sorbent for carbon dioxide

    NASA Technical Reports Server (NTRS)

    Colombo, G. V.

    1974-01-01

    Material can be regenerated at least 20 times by heating at 250 C. Sorbent is compatible with environment of high humidity; up to 20% by weight of carbon dioxide can be absorbed. Material is prepared from silver carbonate, potassium hydroxide or carbonate, and sodium silicate.

  11. Synthesis and Study of Silver Nanoparticles

    ERIC Educational Resources Information Center

    Soloman, Sally D.; Bahadory, Mozghan; Jeyarajasingam, Aravindan V.; Rutkowsky, Susan A.; Boritz, Charles; Mulfinger, Lorraine

    2007-01-01

    A laboratory experiment was conducted in which the students synthesized yellow colloidal silver, estimate particle size using visible spectroscopy and studied aggregation effects. The students were thus introduced to nanotechnology along with other topics such as redox chemistry, limiting and excess reactants, spectroscopy and atomic size.

  12. Madame Tussaud's Prepare for Silver Jubilee Year

    ERIC Educational Resources Information Center

    Clark, Stephanie

    1977-01-01

    In preparation for the Silver Jubilee of Queen Elizabeth, some of the wax figure scenes of the royal family at Madame Tussaud's Waxworks are being renewed. A bit of the history of Tussaud's is given. The most popular exhibits are named, and technical details are added. (IFS/WGA)

  13. Super-dense array of Ge quantum dots grown on Si(100) by low-temperature molecular beam epitaxy

    SciTech Connect

    Talochkin, A. B. Shklyaev, A. A.; Mashanov, V. I.

    2014-04-14

    Ge layer grown on Si(100) at the low temperature of ∼100 °C by molecular beam epitaxy is studied using scanning tunneling microscopy and Raman spectroscopy. It is found that crystalline and pseudomorphic to the Si substrate Ge islands are formed at the initial growth stage. The islands acquire the base size of 1.2–2.6 nm and they form arrays with the super-high density of (5–8) × 10{sup 12} cm{sup −2} at 1–2 nm Ge coverages. Such a density is at least 10 times higher than that of Ge “hut” clusters grown via the Stranski-Krastanov growth mode. It is shown that areas between the crystalline Ge islands are filled with amorphous Ge, which is suggested to create potential barrier for holes localized within the islands. As a result, crystalline Ge quantum dots appear being isolated from each other.

  14. 32 CFR 935.62 - Island Attorney.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Island Attorney. 935.62 Section 935.62 National... WAKE ISLAND CODE Judiciary § 935.62 Island Attorney. There is an Island Attorney, appointed by the General Counsel as needed. The Island Attorney shall serve at the pleasure of the General Counsel....

  15. 32 CFR 935.62 - Island Attorney.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Island Attorney. 935.62 Section 935.62 National... WAKE ISLAND CODE Judiciary § 935.62 Island Attorney. There is an Island Attorney, appointed by the General Counsel as needed. The Island Attorney shall serve at the pleasure of the General Counsel....

  16. 32 CFR 935.62 - Island Attorney.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Island Attorney. 935.62 Section 935.62 National... WAKE ISLAND CODE Judiciary § 935.62 Island Attorney. There is an Island Attorney, appointed by the General Counsel as needed. The Island Attorney shall serve at the pleasure of the General Counsel....

  17. 32 CFR 935.62 - Island Attorney.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Island Attorney. 935.62 Section 935.62 National... WAKE ISLAND CODE Judiciary § 935.62 Island Attorney. There is an Island Attorney, appointed by the General Counsel as needed. The Island Attorney shall serve at the pleasure of the General Counsel....

  18. 32 CFR 935.62 - Island Attorney.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Island Attorney. 935.62 Section 935.62 National... WAKE ISLAND CODE Judiciary § 935.62 Island Attorney. There is an Island Attorney, appointed by the General Counsel as needed. The Island Attorney shall serve at the pleasure of the General Counsel....

  19. Asthma and Native Hawaiians/Pacific Islanders

    MedlinePlus

    ... Other Pacific Islander > Asthma Asthma and Native Hawaiians/Pacific Islanders Native Hawaiians/Pacific Islanders are 70 percent more likely to have ... being told they had asthma, 2014 Native Hawaiian/Pacific Islander Non-Hispanic White Native Hawaiian/Pacific Islander/ ...

  20. Secondary growth mechanism of SiGe islands deposited on a mixed-phase microcrystalline Si by ion beam co-sputtering.

    PubMed

    Ke, S Y; Yang, J; Qiu, F; Wang, Z Q; Wang, C; Yang, Y

    2015-11-01

    We discuss the SiGe island co-sputtering deposition on a microcrystalline silicon (μc-Si) buffer layer and the secondary island growth based on this pre-SiGe island layer. The growth phenomenon of SiGe islands on crystalline silicon (c-Si) is also investigated for comparison. The pre-SiGe layer grown on μc-Si exhibits a mixed-phase structure, including SiGe islands and amorphous SiGe (a-SiGe) alloy, while the layer deposited on c-Si shows a single-phase island structure. The preferential growth and Ostwald ripening growth are shown to be the secondary growth mechanism of SiGe islands on μc-Si and c-Si, respectively. This difference may result from the effect of amorphous phase Si (AP-Si) in μc-Si on the island growth. In addition, the Si-Ge intermixing behavior of the secondary-grown islands on μc-Si is interpreted by constructing the model of lateral atomic migration, while this behavior on c-Si is ascribed to traditional uphill atomic diffusion. It is found that the aspect ratios of the preferential-grown super islands are higher than those of the Ostwald-ripening ones. The lower lateral growth rate of super islands due to the lower surface energy of AP-Si on the μc-Si buffer layer for the non-wetting of Ge at 700 °C and the stronger Si-Ge intermixing effect at 730 °C may be responsible for this aspect ratio difference.