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Sample records for transformation fromsolid silver

  1. Transformation of Silver Nanoparticles in Fresh, Aged, and Incinerated Biosolids

    Science.gov (United States)

    Abstract The purpose of this research was to assess the chemical transformation of silver nanoparticles (AgNPs) in aged, fresh, and incinerated biosolids in order to provide information for AgNP life cycle analyses. Silver nanoparticles were introduced to the influent of a pilot...

  2. Environmental transformations of silver nanoparticles: impact on stability and toxicity.

    Science.gov (United States)

    Levard, Clément; Hotze, E Matt; Lowry, Gregory V; Brown, Gordon E

    2012-07-03

    Silver nanoparticles (Ag-NPs) readily transform in the environment, which modifies their properties and alters their transport, fate, and toxicity. It is essential to consider such transformations when assessing the potential environmental impact of Ag-NPs. This review discusses the major transformation processes of Ag-NPs in various aqueous environments, particularly transformations of the metallic Ag cores caused by reactions with (in)organic ligands, and the effects of such transformations on physical and chemical stability and toxicity. Thermodynamic arguments are used to predict what forms of oxidized silver will predominate in various environmental scenarios. Silver binds strongly to sulfur (both organic and inorganic) in natural systems (fresh and sea waters) as well as in wastewater treatment plants, where most Ag-NPs are expected to be concentrated and then released. Sulfidation of Ag-NPs results in a significant decrease in their toxicity due to the lower solubility of silver sulfide, potentially limiting their short-term environmental impact. This review also discusses some of the major unanswered questions about Ag-NPs, which, when answered, will improve predictions about their potential environmental impacts. Research needed to address these questions includes fundamental molecular-level studies of Ag-NPs and their transformation products, particularly Ag(2)S-NPs, in simplified model systems containing common (in)organic ligands, as well as under more realistic environmental conditions using microcosm/mesocosm-type experiments. Toxicology studies of Ag-NP transformation products, including different states of aggregation and sulfidation, are also required. In addition, there is the need to characterize the surface structures, compositions, and morphologies of Ag-NPs and Ag(2)S-NPs to the extent possible because they control properties such as solubility and reactivity.

  3. Electrochemical mechanism of silver nanoprisms transformation in aqueous solutions containing the halide ions

    Science.gov (United States)

    Abkhalimov, E. V.; Timofeev, A. A.; Ershov, B. G.

    2018-02-01

    The transformation process of 20-50 nm silver nanoprisms in the presence of Cl-, Br-, and I- ions was studied. The threshold concentrations of halide ions that initiate the transformation do not depend on the size of nanoprisms. It was shown that the structure change is caused by the formation of poorly soluble silver complexes on nanoprisms and occurs by an electrochemical mechanism. The induction period preceding the onset of shape transformation is related to the formation of silver halide nanoelectrodes. The electrochemical reactions involving silver and silver halide nanoelectrodes induce restructuring of silver particles the efficiency of which is determined by electrode potentials. [Figure not available: see fulltext.

  4. Transformation of Silver Nanoparticles in Sewage Sludge during Incineration.

    Science.gov (United States)

    Meier, Christoph; Voegelin, Andreas; Pradas del Real, Ana; Sarret, Geraldine; Mueller, Christoph R; Kaegi, Ralf

    2016-04-05

    Silver nanoparticles (Ag-NP) discharged into the municipal sewer system largely accumulate in the sewage sludge. Incineration and agricultural use are currently the most important strategies for sewage sludge management. Thus, the behavior of Ag-NP during sewage sludge incineration is essential for a comprehensive life cycle analysis and a more complete understanding of the fate of Ag-NP in the (urban) environment. To address the transformation of Ag-NP during sewage sludge incineration, we spiked metallic Ag(0)-NP to a pilot wastewater treatment plant and digested the sludge anaerobically. The sludge was then incinerated on a bench-scale fluidized bed reactor in a series of experiments under variable conditions. Complementary results from X-ray absorption spectroscopy (XAS) and electron microscopy-energy dispersive X-ray (EM-EDX) analysis revealed that Ag(0)-NP transformed into Ag2S-NP during the wastewater treatment, in agreement with previous studies. On the basis of a principal component analysis and subsequent target testing of the XAS spectra, Ag(0) was identified as a major Ag component in the ashes, and Ag2S was clearly absent. The reformation of Ag(0)-NP was confirmed by EM-EDX. The fraction of Ag(0) of the total Ag in the ashes was quantified by linear combination fitting (LCF) of XAS spectra, and values as high as 0.8 were found for sewage sludge incinerated at 800 °C in a synthetic flue gas atmosphere. Low LCF totals (72% to 94%) indicated that at least one relevant reference spectrum was missing in the LCF analysis. The presence of spherical Ag-NP with a diameter of sewage sludge incineration, as demonstrated in this study, needs to be considered in the life cycle assessment of engineered Ag-NP.

  5. The kinetics of formation and transformation of silver atoms on solid surfaces subjected to ionizing irradiation

    International Nuclear Information System (INIS)

    Popovich, G.M.

    1988-01-01

    The paper discusses the results obtained in ESR-assisted studies of the kinetics of formation and transformation of silver atoms generated by γ-irradiation of silver-containing carriers. Three types of dependences have been established: (1) extreme; (2) saturation curves and (3) step-like. All the kinetic curves display, after a definite period of time, stable concentrations of adsorbed silver atoms per unit of the surface at a given temperature. Depending on the temperature of the experiment, the composition and nature of the carrier, the number of adsorbed silver ions, the irradiation dose and conditions of the experiment, a stable concentration of silver atoms at a given temperature may be equal to, higher or lower than the number of silver atoms measured immediately after γ-irradiation at a temperature of liquid nitrogen. A kinetic scheme is proposed to explain the obtained curves. The model suggests that the silver atoms adsorbed on the surface, as well as those formed after γ-irradiation, are bonded to the surface by various energies, which are related to heterogeneity of the carrier surface. (author)

  6. Timescale of silver nanoparticle transformation in neural cell cultures impacts measured cell response

    Energy Technology Data Exchange (ETDEWEB)

    Hume, Stephanie L.; Chiaramonti, Ann N.; Rice, Katherine P.; Schwindt, Rani K. [National Institute of Standards and Technology (NIST), Applied Chemicals and Materials Division (United States); MacCuspie, Robert I. [National Institute of Standards and Technology (NIST), Materials Measurement Science Division (United States); Jeerage, Kavita M., E-mail: jeerage@boulder.nist.gov [National Institute of Standards and Technology (NIST), Applied Chemicals and Materials Division (United States)

    2015-07-15

    Both serum protein concentration and ionic strength are important factors in nanoparticle transformation within cell culture environments. However, silver nanoparticles are not routinely tracked at their working concentration in the specific medium used for in vitro toxicology studies. Here we evaluated the transformation of electrostatically stabilized citrate nanoparticles (C-AgNPs) and sterically stabilized polyvinylpyrrolidone nanoparticles (PVP-AgNPs) in a low-serum (∼ 0.2 mg/mL bovine serum albumin) culture medium, while measuring the response of rat cortex neural progenitor cells, which differentiate in this culture environment. After 24 h, silver nanoparticles at concentrations up to 10 µg/mL did not affect adenosine triphosphate levels, whereas silver ions decreased adenosine triphosphate levels at concentrations of 1.1 µg/mL or higher. After 240 h, both silver nanoparticles, as well as silver ion, unambiguously decreased adenosine triphosphate levels at concentrations of 1 and 1.1 µg/mL, respectively, suggesting particle dissolution. Particle transformation was investigated in 1:10 diluted, 1:2 diluted, or undiluted differentiation medium, all having an identical protein concentration, to separate the effect of serum protein stabilization from ionic strength destabilization. Transmission electron microscopy images indicated that particles in 1:10 medium were not surrounded by proteins, whereas particles became clustered within a non-crystalline protein matrix after 24 h in 1:2 medium and at 0 h in undiluted medium. Despite evidence for a protein corona, particles were rapidly destabilized by high ionic strength media. Polyvinylpyrrolidone increased the stability of singly dispersed particles compared to citrate ligands; however, differences were negligible after 4 h in 1:2 medium or after 1 h in undiluted medium. Thus low-serum culture environments do not provide sufficient colloidal stability for long-term toxicology studies with citrate

  7. Timescale of silver nanoparticle transformation in neural cell cultures impacts measured cell response

    International Nuclear Information System (INIS)

    Hume, Stephanie L.; Chiaramonti, Ann N.; Rice, Katherine P.; Schwindt, Rani K.; MacCuspie, Robert I.; Jeerage, Kavita M.

    2015-01-01

    Both serum protein concentration and ionic strength are important factors in nanoparticle transformation within cell culture environments. However, silver nanoparticles are not routinely tracked at their working concentration in the specific medium used for in vitro toxicology studies. Here we evaluated the transformation of electrostatically stabilized citrate nanoparticles (C-AgNPs) and sterically stabilized polyvinylpyrrolidone nanoparticles (PVP-AgNPs) in a low-serum (∼ 0.2 mg/mL bovine serum albumin) culture medium, while measuring the response of rat cortex neural progenitor cells, which differentiate in this culture environment. After 24 h, silver nanoparticles at concentrations up to 10 µg/mL did not affect adenosine triphosphate levels, whereas silver ions decreased adenosine triphosphate levels at concentrations of 1.1 µg/mL or higher. After 240 h, both silver nanoparticles, as well as silver ion, unambiguously decreased adenosine triphosphate levels at concentrations of 1 and 1.1 µg/mL, respectively, suggesting particle dissolution. Particle transformation was investigated in 1:10 diluted, 1:2 diluted, or undiluted differentiation medium, all having an identical protein concentration, to separate the effect of serum protein stabilization from ionic strength destabilization. Transmission electron microscopy images indicated that particles in 1:10 medium were not surrounded by proteins, whereas particles became clustered within a non-crystalline protein matrix after 24 h in 1:2 medium and at 0 h in undiluted medium. Despite evidence for a protein corona, particles were rapidly destabilized by high ionic strength media. Polyvinylpyrrolidone increased the stability of singly dispersed particles compared to citrate ligands; however, differences were negligible after 4 h in 1:2 medium or after 1 h in undiluted medium. Thus low-serum culture environments do not provide sufficient colloidal stability for long-term toxicology studies with citrate

  8. Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles

    International Nuclear Information System (INIS)

    Schwarz, Florian P.

    2010-01-01

    Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

  9. Transient Reactivity of Solid Silver Acetate in Hydrogen and Oxygen by In Situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy*

    OpenAIRE

    Tohru, KANNO; Masayoshi, KOBAYASHI

    1985-01-01

    The reactivity of solid silver acetate in hydrogen and oxygen has been studied by using the transient response method and the in situ diffuse reflectance infrared fourier transform spectroscopic (DKIFTS) technique to compare its nature to that of the reaction intermediates in ethylene oxidation. 0n the analysis of the transient response curves, solid silver acetate produced acetic acid and a small amount of carbon dioxide in a hydrogen stream, and produced CO_2 and a small amount of CH_3COOH ...

  10. Martensitic transformation and shape memory effect in NiTi alloy covered by chitosan/silver layer

    Directory of Open Access Journals (Sweden)

    Goryczka Tomasz

    2015-01-01

    Full Text Available The NiTi shape memory alloy was covered with chitosan/silver layer. Coatings were deposited at room temperature using combination of processing parameters such as deposition voltage and amount of silver in colloidal suspension. Structure of layers was studied by means of X-ray diffraction. Quality of the coatings was evaluated basing on observations done in scanning electron microscopy. Transformation behaviour of coated samples was studied with use of differential scanning calorimeter. The covered sample revealed presence of the reversible martensitic transformation and ability to deformation (in bending mode up to 8%. Forward martensitic transformation, in as-received NiTi alloy and in alloy after layer deposition occurred in two steps B2-R-B19’. After deformation quality of the chitosan/silver layer remained unchanged.

  11. Chloride-induced shape transformation of silver nanoparticles in a water environment

    International Nuclear Information System (INIS)

    Zhang, Lan; Li, Xin; He, Rong; Wu, Lijun; Zhang, Liyun; Zeng, Jie

    2015-01-01

    The effects of chloride on dissolution and toxicity of silver nanoparticles (AgNPs) have been well studied. However, their intermediate shapes during the transition have not been illustrated to-date. Herein, the chloride-induced shape transformation process of AgNPs under long-term, low-concentration conditions is explored. A unique triangular Ag–AgCl heterostructure is observed. The structure then evolves into a symmetric hexapod and finally into a smaller AgNP. This transformation process could be affected by other environmental conditions, such as 0.4 mg/mL humic acid, 5% surfactants and 1 mg/mL bovine serum albumin protein. Our results offer new knowledge regarding the shape transformation process of AgNPs in the presence of chloride, which can be valuable in relevant studies concerning the effect of water chemistry on the behavior of AgNPs. - Highlights: • Several significant intermediate structures have been firstly observed during AgNPs shape transformation process. • These findings of intermediate shapes offer the new knowledge on understanding the environmental fate of AgNPs. • The effects of other environmental factors on shape transformation have been well explored. - Significant intermediate structures are discovered during the AgNPs environmental process, enriching the knowledge of understanding the environmental fate of AgNPs

  12. Water chemistry controlled aggregation and photo-transformation of silver nanoparticles in environmental waters.

    Science.gov (United States)

    Yin, Yongguang; Yang, Xiaoya; Zhou, Xiaoxia; Wang, Weidong; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2015-08-01

    The inevitable release of engineered silver nanoparticles (AgNPs) into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of AgNPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered AgNPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone (PVP) coated AgNPs was investigated in eight typical environmental water samples (with different ionic strengths, hardness, and dissolved organic matter (DOM) concentrations) by using UV-visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of AgNPs. Further, the photo-transformation and morphology changes of AgNPs in environmental waters were studied by UV-visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes (especially Ca(2+) and Mg(2+)) and DOM in the surface waters are key parameters for AgNP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of AgNPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of AgNPs in the aquatic environments. Copyright © 2015. Published by Elsevier B.V.

  13. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    Science.gov (United States)

    Lobato, I.; Rojas, J.; Landauro, C. V.; Torres, J.

    2009-02-01

    The structural evolution and dynamics of silver nanodrops Ag2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 × 1013 K s-1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 × 1012 K s-1), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  14. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    International Nuclear Information System (INIS)

    Lobato, I; Rojas, J; Landauro, C V; Torres, J

    2009-01-01

    The structural evolution and dynamics of silver nanodrops Ag 2869 (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 x 10 13 K s -1 the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 x 10 12 K s -1 ), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  15. Atomic and electronic structure transformations of silver nanoparticles under rapid cooling conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, I; Rojas, J [Instituto Peruano de EnergIa Nuclear, Avenida Canada 1470, Lima 41 (Peru); Landauro, C V; Torres, J [Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, P.O. box 14-0149, Lima 14 (Peru)], E-mail: jrojast@unmsm.edu.pe

    2009-02-04

    The structural evolution and dynamics of silver nanodrops Ag{sub 2869} (4.4 nm in diameter) under rapid cooling conditions have been studied by means of molecular dynamics simulations and electronic density of state calculations. The interaction of silver atoms is modelled by a tight-binding semiempirical interatomic potential proposed by Cleri and Rosato. The pair correlation functions and the pair analysis technique are used to reveal the structural transition in the process of solidification. It is shown that Ag nanoparticles evolve into different nanostructures under different cooling processes. At a cooling rate of 1.5625 x 10{sup 13} K s{sup -1} the nanoparticles preserve an amorphous-like structure containing a large amount of 1551 and 1541 pairs which correspond to icosahedral symmetry. For a lower cooling rate (1.5625 x 10{sup 12} K s{sup -1}), the nanoparticles transform into a crystal-like structure consisting mainly of 1421 and 1422 pairs which correspond to the face centred cubic and hexagonal close packed structures, respectively. The variations of the electronic density of states for the differently cooled nanoparticles are small, but in correspondence with the structural changes.

  16. Nanoscaled gold and silver: Simultaneous removal and transformation to functional materials.

    Science.gov (United States)

    Xia, Youyi; Sun, Lin; Xiao, Hongping

    2018-01-15

    Based on an "acid-assisted cool welding" technology which was realized by virtue of the freezing process in the presence of acid, nanoscaled gold (Au) and silver (Ag) from wastewater could be removed very facilely and efficiently. The technology was independence of the freezing temperature, size as well as shape of those nanoscaled units. Besides, some functional materials like porous nanostructures with highly and stably catalytic activity could be also obtained during the removal. Our research not only provided a new method to remove nanoscaled Ag or Au from wastewater, but also built up a unique route to transform those nano-units into functional materials simultaneously. Copyright © 2017. Published by Elsevier B.V.

  17. Transformation of Four Silver/Silver Chloride Nanoparticles during Anaerobic Treatment of Wastewater and Post-processing of Sewage Sludge

    Science.gov (United States)

    The increasing use of silver (Ag) nanoparticles [containing either elemental Ag (Ag-NPs) or AgCl (AgCl-NPs)] in commercial products such as textiles will most likely result in these materials reaching wastewater treatment plants. Previous studies indicate that a conversion of Ag-...

  18. Identifying the hot spots of denitrification and nitrogen transformation across different land uses in the Silver Spring springshed, Florida

    Science.gov (United States)

    Liao, X.; Inglett, P.; Dobberfuhl, D. R.; Canion, A. K.

    2016-12-01

    Silver Springs is the largest of Florida's first magnitude springs and also likely the largest limestone spring in the United States. Land use in the springshed has changed from predominantly natural to urban/agricultural over the past 50 years, leading to more pollution for ground and surface water, and excess nitrate is considered as the major concern in restoring the Silver Springs. In this study, we investigated the effects of land uses on the nitrogen transformation by measuring the dissolved gases (e.g., dissolved N2, Ar, N2O, CH4) in the east and west vent of Silver Spring and ground water from 61 wells around the springshed. The dissolved CH4 and N2O in the ground water ranged from 0 to 106 µM, and 0 to 2.0 µM, respectively. Significantly higher dissolved N2O and CH4 were observed in the dry and wet season, respectively. In our study, significant positive correlation between N2O with dissolved oxygen and nitrate (P land uses of agriculture and urban, whereas higher dissolved N2 and N2:Ar were measured in the land uses of forest and wetlands. Moreover, the principal component analysis based on the geochemical properties of the water showed that the West and East vent reflected the land use of forests and wetlands, and of agriculture and urban, respectively, further suggesting the hot spots for nitrification and denitrification.

  19. Silver niobates

    International Nuclear Information System (INIS)

    Tanirbergenov, B.; Rozhenko, S.P.

    1979-01-01

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

  20. Transformation of silver nanowires into nanoparticles by Rayleigh instability: Comparison between laser irradiation and heat treatment

    Science.gov (United States)

    Oh, Harim; Lee, Jeeyoung; Lee, Myeongkyu

    2018-01-01

    We comparatively study the morphological evolutions of silver nanowires under nanosecond-pulsed laser irradiation and thermal treatment in ambient air. While single-crystalline, pure Ag nanospheres could be produced by laser-driven Rayleigh instability, the particles produced by heat treatment were subject to oxidation and exhibited polyhedron shapes. The different results are attributed to the significantly different time scales of the two processes. In this article, we also show that bimetallic Ag-Au nanospheres can be synthesized by irradiating Ag nanowires coated with a thin Au film using a pulsed laser beam. This may provide a facile route to tune the plasmonic behavior of metal nanoparticles.

  1. Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles; Ioneninduzierte Umwandlung von Polymerschichten zu diamantaehnlichem Kohlenstoff mit darin enthaltenen Silber-Nanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Florian P.

    2010-03-26

    Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

  2. TRANSFORMATION

    Energy Technology Data Exchange (ETDEWEB)

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  3. TRANSFORMER

    Science.gov (United States)

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  4. Transformation

    DEFF Research Database (Denmark)

    Peters, Terri

    2011-01-01

    Artiklen diskuterer ordet "transformation" med udgangspunkt i dels hvorledes ordet bruges i arkitektfaglig terminologi og dels med fokus på ordets potentielle indhold og egnethed i samme teminologi....

  5. Influence of Silver nanoparticles addition on the phase transformation, mechanical properties and corrosion behaviour of Cu–Al–Ni shape memory alloys

    International Nuclear Information System (INIS)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Bakhsheshi-Rad, H.R.; Farahany, S.; Abdolahi, A.; Taheri, M.M.

    2014-01-01

    Highlights: • Thermal analysis showed four different phase β, α, NiAl and γ2 during solidification. • The martensite appeared in the microstructure as a plate and needle like shape. • Shape recovery ratio of 80% was obtained after Ag nanoparticles addition. • Effect of Ag nanoparticles on the corrosion behaviour of Cu–Al–Ni SMA was investigated. - Abstract: Incorporation of silver nanoparticles into Cu-based shape memory alloys is recommended to enhance their phase transformation behaviour. However, this incorporation can affect their transformation temperatures, mechanical, microstructural and corrosion characteristics. Four different phase reactions β, α, NiAl and γ 2 were detected on a derivative curve during the solidification by-computer-aided cooling curve thermal analysis. The highest fraction solid (82%) was calculated for the parent phase (β) based on the Newtonian baseline method. The microstructural changes and mechanical properties were investigated using field emission scanning electron microscopy, X-ray diffraction tensile test and shape memory effect test. It was found that the addition of Ag can control the phase morphology and orientations along with the formation of the Ag-rich precipitates, and thus the tensile strength, elongation, fracture stress–strain, yield strength and shape memory effect are improved. Remarkably, the shape recovery ratio reached approximately 80% of the original shape. The corrosion behaviour of the Cu–Al–Ni shape memory alloy were investigated using electrochemical tests in NaCl solution and their results showed that the corrosion potential (E corr ) of Cu–Al–Ni SMA is shifted towards the nobler direction from −307.4 to −277.1 m V SCE with the addition of 0.25 wt.% Ag

  6. Influence of Silver nanoparticles addition on the phase transformation, mechanical properties and corrosion behaviour of Cu–Al–Ni shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Saud, Safaa N.; Hamzah, E., E-mail: esah@fkm.utm.my; Abubakar, T.; Bakhsheshi-Rad, H.R.; Farahany, S.; Abdolahi, A.; Taheri, M.M.

    2014-11-05

    Highlights: • Thermal analysis showed four different phase β, α, NiAl and γ2 during solidification. • The martensite appeared in the microstructure as a plate and needle like shape. • Shape recovery ratio of 80% was obtained after Ag nanoparticles addition. • Effect of Ag nanoparticles on the corrosion behaviour of Cu–Al–Ni SMA was investigated. - Abstract: Incorporation of silver nanoparticles into Cu-based shape memory alloys is recommended to enhance their phase transformation behaviour. However, this incorporation can affect their transformation temperatures, mechanical, microstructural and corrosion characteristics. Four different phase reactions β, α, NiAl and γ{sub 2} were detected on a derivative curve during the solidification by-computer-aided cooling curve thermal analysis. The highest fraction solid (82%) was calculated for the parent phase (β) based on the Newtonian baseline method. The microstructural changes and mechanical properties were investigated using field emission scanning electron microscopy, X-ray diffraction tensile test and shape memory effect test. It was found that the addition of Ag can control the phase morphology and orientations along with the formation of the Ag-rich precipitates, and thus the tensile strength, elongation, fracture stress–strain, yield strength and shape memory effect are improved. Remarkably, the shape recovery ratio reached approximately 80% of the original shape. The corrosion behaviour of the Cu–Al–Ni shape memory alloy were investigated using electrochemical tests in NaCl solution and their results showed that the corrosion potential (E{sub corr}) of Cu–Al–Ni SMA is shifted towards the nobler direction from −307.4 to −277.1 m V{sub SCE} with the addition of 0.25 wt.% Ag.

  7. Silver Nanoparticles

    Science.gov (United States)

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

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

  8. Mechanisms of Silver Nanoparticle Release, Transformation and Toxicity: A Critical Review of Current Knowledge and Recommendations for Future Studies and Applications

    Directory of Open Access Journals (Sweden)

    Iseult Lynch

    2013-06-01

    Full Text Available Nanosilver, due to its small particle size and enormous specific surface area, facilitates more rapid dissolution of ions than the equivalent bulk material; potentially leading to increased toxicity of nanosilver. This, coupled with their capacity to adsorb biomolecules and interact with biological receptors can mean that nanoparticles can reach sub-cellular locations leading to potentially higher localized concentrations of ions once those particles start to dissolve or degrade in situ. Further complicating the story is the capacity for nanoparticles to generate reactive oxygen species, and to interact with, and potentially disturb the functioning of biomolecules such as proteins, enzymes and DNA. The fact that the nanoparticle size, shape, surface coating and a host of other factors contribute to these interactions, and that the particles themselves are evolving or ageing leads to further complications in terms of elucidating mechanisms of interaction and modes of action for silver nanoparticles, in contrast to dissolved silver species. This review aims to provide a critical assessment of the current understanding of silver nanoparticle toxicity, as well as to provide a set of pointers and guidelines for experimental design of future studies to assess the environmental and biological impacts of silver nanoparticles. In particular; in future we require a detailed description of the nanoparticles; their synthesis route and stabilisation mechanisms; their coating; and evolution and ageing under the exposure conditions of the assay. This would allow for comparison of data from different particles; different environmental or biological systems; and structure-activity or structure-property relationships to emerge as the basis for predictive toxicology. On the basis of currently available data; such comparisons or predictions are difficult; as the characterisation and time-resolved data is not available; and a full understanding of silver

  9. Ternary Silver Halide Nanocrystals.

    Science.gov (United States)

    Abeyweera, Sasitha C; Rasamani, Kowsalya D; Sun, Yugang

    2017-07-18

    Nanocrystalline silver halides (AgX) such as AgCl, AgBr, and AgI, a class of semiconductor materials with characteristics of both direct and indirect band gaps, represent the most crucial components in traditional photographic processing. The nanocrystal surfaces provide sensitivity specks that can turn into metallic silver, forming an invisible latent image, upon exposure to light. The photographic processing implies that the AgX nanoparticles possess unique properties. First, pristine AgX nanoparticles absorb light only at low efficiency to convert surface AgX into tiny clusters of silver atoms. Second, AgX nanoparticles represent an excellent class of materials to capture electrons efficiently. Third, small metallic silver clusters can catalyze the reduction of AgX nanoparticles to Ag nanoparticles in the presence of mild reducing reagents, known as self-catalytic reduction. These properties indicate that AgX nanoparticles can be partially converted to metallic silver with high precision, leading to the formation of hybrid AgX/Ag nanoparticles. The nanosized metallic Ag usually exhibit intense absorption bands in the visible spectral region due to their strong surface plasmon resonances, which make the AgX/Ag nanoparticles a class of promising visible-light-driven photocatalysts for environmental remediation and CO 2 reduction. Despite the less attention paid to their ability of capturing electrons, AgX nanoparticles might be a class of ideal electron shuttle materials to bridge light absorbers and catalysts on which electrons can drive chemical transformations. In this Account, we focus on ternary silver halide alloy (TSHA) nanoparticles, containing two types of halide ions, which increase the composition complexity of the silver halide nanoparticles. Interdiffusion of halide ions between two types of AgX at elevated temperatures has been developed for fabricating ternary silver halide alloy crystals, such as silver chlorobromide optical fibers for infrared

  10. Thermal decomposition process of silver behenate

    International Nuclear Information System (INIS)

    Liu Xianhao; Lu Shuxia; Zhang Jingchang; Cao Weiliang

    2006-01-01

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

  11. Presence of nanoparticles in wash water from conventional silver and nano-silver textiles.

    Science.gov (United States)

    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, 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 assessment of nano-silver warrants a similar approach to conventional silver.

  12. In situ synthesis of silver benzene-dithiolate hybrid films

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-01

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

  13. Synthesis of silver nanoparticle and its application.

    Science.gov (United States)

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

    2015-11-01

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

  14. Russell-Silver syndrome

    Science.gov (United States)

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

  15. A prospective, randomised study of a novel transforming methacrylate dressing compared with a silver-containing sodium carboxymethylcellulose dressing on partial-thickness skin graft donor sites in burn patients.

    Science.gov (United States)

    Assadian, Ojan; Arnoldo, Brett; Purdue, Gary; Burris, Agnes; Skrinjar, Edda; Duschek, Nikolaus; Leaper, David J

    2015-06-01

    This prospective, randomised study compares a new transforming methacrylate dressing (TMD) with a silver-containing carboxymethylcellulose dressing (CMC-Ag) after application to split-thickness skin graft (STSG) donor sites. This was an unblinded, non-inferiority, between-patient, comparison study that involved patients admitted to a single-centre burn unit who required two skin graft donor sites. Each patient's donor sites were covered immediately after surgery: one donor site with TMD and the other with CMC-Ag. The donor sites were evaluated until healing or until 24 days post-application, whichever came first. Study endpoints were time to healing, daily pain scores, number of dressing changes, patient comfort and physicians' and patients' willingness to use the dressings in the future. Nineteen patients had both the dressings applied. No statistically significant difference was noted in time to healing between the two dressings (14·2 days using TMD compared with 13·2 days using CMC-Ag). When pain scores were compared, TMD resulted in statistically significantly less pain at three different time periods (2-5 days, 6-10 days and 11-15 days; P dressing, compared with CMC-Ag, were seen as clinical benefits as these are the major issues in donor site management. © 2013 The Authors. International Wound Journal © 2013 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  16. The Speciation Of Silver Nanoparticles In Antimicrobial Fabric Before and After Exposure To A Hypochlorite/Detergent Solution

    Science.gov (United States)

    Because of their antibacterial properties, silver nanoparticles are often used in consumer products. To assess environmental and/or human health risks from these nanoparticles, there is a need to identify the chemical transformations that Silver nanoparticles undergo in differen...

  17. Silvering of European eel (Anguilla anguilla L.): seasonal changes of morphological and metabolic parameters

    NARCIS (Netherlands)

    Ginneken, van V.; Durif, C.; Paul Balm, S.; Boot, R.; Verstegen, M.W.A.; Antonissen, E.; Thillart, van den G.

    2007-01-01

    The transformation of yellow eel into silver eel is called `silvering¿, and takes place prior to migration. We found the sedentary yellow phase in spring, the migratory silver phase in autumn, while August was a cross-over month. We used principal component analysis (PCA) to characterise the

  18. Biosynthesis of silver nanoparticles and its antibacterial activity ...

    African Journals Online (AJOL)

    In the present research work, biosynthesis of silver nanoparticles and its activity on bacterial pathogens were investigated. Silver nanoparticles were rapidly synthesized using Urospora sp. and the formation of nanoparticles was observed within 30 min. The results recorded from UV–vis spectrum, Fourier Transform Infrared ...

  19. Characterization of silver nanoparticles synthesized using an endophytic fungus, Penicillium oxalicum having potential antimicrobial activity

    Science.gov (United States)

    Bhattacharjee, Sukla; Debnath, Gopal; Das, Aparajita Roy; Krishna Saha, Ajay; Das, Panna

    2017-12-01

    The aim of the present study was to test the efficacy of the extracellular mycelium extract of Penicillium oxalicum isolated from Phlogacanthus thyrsiflorus to biosynthesize silver nanoparticles. It was characterized using ultraviolet-visible absorption spectroscopy, atomic force microscopy, transmission electron microscopy and Fourier transforms infrared spectroscopy. The silver nanoparticles were evaluated for antimicrobial activity. The characterization confirms the synthesis of silver nanoparticles. Both silver nanoparticles and combination of silver nanoparticles with streptomycin showed activity against the four bacteria. The results suggested that P. oxalicum offers eco-friendly production of silver nanoparticles and the antibacterial activity may find application in biomedicine.

  20. Fate of Zinc and Silver Engineered Nanoparticles in Sewerage Networks

    Science.gov (United States)

    Engineered zinc oxide (ZnO) and silver (Ag) nanoparticles (NPs) used in consumer products are largely released into the environment through the wastewater stream. Limited information is available regarding the transformations they undergo during their transit through sewerage sy...

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

    International Nuclear Information System (INIS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Shirzaditabar, Farzad; Saliminasab, Maryam [Department of Physics, Razi University, Kermanshah 67144-15111 (Iran, Islamic Republic of)

    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.

  3. PVDF nanofibers with silver nanoparticles and silver/titanium dioxide for antimicrobial applications

    International Nuclear Information System (INIS)

    Costa, Ligia M.M.; Olyveira, Gabriel M. de

    2009-01-01

    PVDF nanofibers with and without nanoparticles were produced by the method of electro spinning using dimethylformamide (DMF). Silver nitrate nanoparticles (0,5 and 2 wt %) and silver/titanium dioxide nanoparticles obtained by the reduction method (2 wt %) were synthesized and added to the PVDF solution to prepared nanofibers. The processes of electrospinning and film preparation using PVDF with the nanoparticles were compared. Silver/titanium dioxide nanoparticles were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDX and x-ray photoelectron spectroscopy (XPS) to show silver/titanium dioxide nanoparticles. Nanofibers mats were characterized with SEM to study the effects of the addition of the nanoparticles on the morphology behavior and spectroscopy by Fourier transform infrared (FTIR) to analyze the crystalline phase of PVDF films. (author)

  4. Synthesis of Chitosan /Alginate/ Silver Nanoparticles Hydrogel Scaffold

    Directory of Open Access Journals (Sweden)

    Ramli Roslinda Hani

    2016-01-01

    Full Text Available This work reports the preparation of silver nanoparticles (AgNPs and synthesis of natural based hydrogel scaffold with an inclusion of AgNPs, chitosan/alginate/silver nanoparticles. The synthesised hydrogel scaffolds were characterised by using Fourier Transform Infrared Resonance Spectroscopy (FTIR. The FTIR result revealed that the shifting of the three peaks of 3252.95 cm−1 (–OH and –NH2 stretching, 1591.33 cm−1 (C=O stretching and 1411.88 cm−1 (N–H stretching of chitosan/alginate/silver nanoparticles in compared to chitosan/alginate hydrogel indicating the presence of electrostatic interaction of –NH3+ in chitosan reacted with the – COO– group of alginate and binding of the silver (Ag. These results indicated that chitosan/alginate/silver nanoparticles were consolidated in the composite system.

  5. Polypyrrole-silver Nanocomposite: Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    D. M. Nerkar

    2016-07-01

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

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

    Directory of Open Access Journals (Sweden)

    M.R. Saeri

    2016-03-01

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

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

    Science.gov (United States)

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

    2018-03-01

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

  8. SYNTHSIS AND PHYSICAL PROPERTIES OF SILVER NANOCOMPOSITES POLYMER ELECTROLYTE

    OpenAIRE

    加藤, 仁和

    2016-01-01

    The silver nano composite polymer electrolytes are prepared by the method of two kinds of the ultrafine particle direct dispersion method and in situ synthesis. The structure of the silver nano composite polymer electrolyte is characterized by Fourier transform infrared spectrometer spectrophotometer (FT-IR), Raman spectroscopy (Raman), and Thermally Stimulated Current (TSC) .The optical property is evaluated by the optical absorption. The electrical property is also evaluated by the ac i...

  9. Synthesis of water soluble glycine capped silver nanoparticles and their surface selective interaction

    International Nuclear Information System (INIS)

    Agasti, Nityananda; Singh, Vinay K.; Kaushik, N.K.

    2015-01-01

    Highlights: • Synthesis of water soluble silver nanoparticles at ambient reaction conditions. • Glycine as stabilizing agent for silver nanoparticles. • Surface selective interaction of glycine with silver nanoparticles. • Glycine concentration influences crystalinity and optical property of silver nanoparticles. - Abstract: Synthesis of biocompatible metal nanoparticles has been an area of significant interest because of their wide range of applications. In the present study, we have successfully synthesized water soluble silver nanoparticles assisted by small amino acid glycine. The method is primarily based on reduction of AgNO 3 with NaBH 4 in aqueous solution under atmospheric air in the presence of glycine. UV–vis spectroscopy, transmission electron microscopy (TEM), X–ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG) and differential thermal analysis (DTA) techniques used for characterization of resulting silver nanoparticles demonstrated that, glycine is an effective capping agent to stabilize silver nanoparticles. Surface selective interaction of glycine on (1 1 1) face of silver nanoparticles has been investigated. The optical property and crystalline behavior of silver nanoparticles were found to be sensitive to concentration of glycine. X–ray diffraction studies ascertained the phase specific interaction of glycine on silver nanoparticles. Silver nanoparticles synthesized were of diameter 60 nm. We thus demonstrated an efficient synthetic method for synthesis of water soluble silver nanoparticles capped by amino acid under mild reaction conditions with excellent reproducibility

  10. Green Synthesis of Silver Nanoparticles Using Pimpinella anisum L. Seed Aqueous Extract and Its Antioxidant Activity

    Directory of Open Access Journals (Sweden)

    Hashem Akhlaghi

    2015-09-01

    Full Text Available An aqueous extract of Pimpinella anisum was used for green synthesis of silver nanoparticles by bio reduction of an aqueous solution of silver nitrate. Silver nanoparticles were characterized by UV–Vis spectrometry, Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD analysis, scanning electron microscopy (SEM and energy-dispersive X-ray analysis (EDAX. The increase in absorption at 420 nm was used for recording the formation of a colloidal suspension of silver nanoparticles. The binding properties of the capped Ag nanoparticles synthesized from aqueous extract of P. anisum were analyzed by FTIR. XRD studies revealed that most of the nanoparticles were cubic and face centered cubic in shape. SEM analysis showed the size and shape of silver nanoparticles and EDAX confirmed the presence of silver. The synthesized silver nanoparticles showed DPPH free radical scavenging activity.

  11. Synthesis, characterization and catalytic activity of silver nanoparticles using Tribulus terrestris leaf extract.

    Science.gov (United States)

    Ashokkumar, S; Ravi, S; Kathiravan, V; Velmurugan, S

    2014-01-01

    Biomediated silver nanoparticles were synthesized with the aid of an eco-friendly biomaterial, namely, aqueous Tribulus terrestris extract. Silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous T. terrestris leaf extracts as both the reducing and capping agent. Silver ions were rapidly reduced by aqueous T. terrestris leaf extracts, leading to the formation of highly crystalline silver nanoparticles. An attempt has been made and formation of the silver nanoparticles was verified by surface plasmon spectra using an UV-vis (Ultra violet), spectrophotometer. Morphology and crystalline structure of the prepared silver nanoparticles were characterized by TEM (Transmission Electron Microscope) and XRD (X-ray Diffraction), techniques, respectively. FT-IR (Fourier Transform Infrared), analysis suggests that the obtained silver nanoparticles might be stabilized through the interactions of carboxylic groups, carbonyl groups and the flavonoids present in the T. terrestris extract. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Copper and silver halates

    CERN Document Server

    Woolley, EM; Salomon, M

    2013-01-01

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

  13. Characterization of silver halide fiber optics and hollow silica waveguides for use in the construction of a mid-infrared attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy probe.

    Science.gov (United States)

    Damin, Craig A; Sommer, André J

    2013-11-01

    Advances in fiber optic materials have allowed for the construction of fibers and waveguides capable of transmitting infrared radiation. An investigation of the transmission characteristics associated with two commonly used types of infrared-transmitting fibers/waveguides for prospective use in a fiber/waveguide-coupled attenuated total internal reflection (ATR) probe was performed. Characterization of silver halide polycrystalline fiber optics and hollow silica waveguides was done on the basis of the transmission of infrared light using a conventional fiber optic coupling accessory and an infrared microscope. Using the fiber optic coupling accessory, the average percent transmission for three silver halide fibers was 18.1 ± 6.1% relative to a benchtop reflection accessory. The average transmission for two hollow waveguides (HWGs) using the coupling accessory was 8.0 ± 0.3%. (Uncertainties in the relative percent transmission represent the standard deviations.) Reduced transmission observed for the HWGs was attributed to the high numerical aperture of the coupling accessory. Characterization of the fibers/waveguides using a zinc selenide lens objective on an infrared microscope indicated 24.1 ± 7.2% of the initial light input into the silver halide fibers was transmitted. Percent transmission obtained for the HWGs was 98.7 ± 0.1%. Increased transmission using the HWGs resulted from the absence or minimization of insertion and scattering losses due to the hollow air core and a better-matched numerical aperture. The effect of bending on the transmission characteristics of the fibers/waveguides was also investigated. Significant deviations in the transmission of infrared light by the solid-core silver halide fibers were observed for various bending angles. Percent transmission greater than 98% was consistently observed for the HWGs at the bending angles. The combined benefits of high percent transmission, reproducible instrument responses, and increased bending

  14. Mineral commodity profiles: Silver

    Science.gov (United States)

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

    2005-01-01

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

  15. Synthesis, characterization and evaluation of silver nanoparticles through leaves of Abrus precatorius L.: an important medicinal plant

    Science.gov (United States)

    Gaddala, Bhumi; Nataru, Savithramma

    2015-01-01

    Biologically synthesized nanoparticles have been widely used in the field of medicine. The present study reports the green synthesis of silver nanoparticles using Abrus precatorius leaf extract with silver nitrate solution as reducing agent. The synthesized silver nanoparticles were analyzed through UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, atomic force microscopy and Fourier transform infrared. The synthesized silver nanoparticles were disk shaped with an average size of 19 nm. These silver nanoparticles were evaluated for antibacterial activity. The diameter of inhibition zones around the disk of Pseudomonas aeruginosa and Staphylococcus aureus are resistant to silver nanoparticles, whereas Escherichia coli and Bacillus thuringiensis are susceptible when compared with the other two species. The results were compared with the ciprofloxacin-positive control and silver nitrate. It is concluded that the green synthesis of silver nanoparticles is very fast, easy, cost-effective and eco-friendly and without any side effects.

  16. Antibacterial and anticancerous biocompatible silver nanoparticles synthesised from the cold-tolerant strain of Spirulina platensis

    OpenAIRE

    Selvaraj Karthick Raja Namasivayam; Duraisamy Jayakumar; Ramesh Kumar; Rajan Sowri Arvind Bharani

    2015-01-01

    Objective: To synthesize silver nanoparticles from the biomass of cold tolerant strain of Spirulina platensis and evalute the synthesized nanoparticles against antibacterial and anticancer activity. Methods: Silver nanoparticles were synthesized by the algal culture and characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X ray diffraction studies. Antibacterial activity has been studied with free nano...

  17. Silver Nanoparticles Synthesized by Decomposition of a Silver Organic Complex with Valence Tautomerism and Their Properties

    Science.gov (United States)

    Harbatsevich, H. I.; Loginova, N. V.; Koval‧chuk, T. V.; Osipovich, N. P.; Gres, A. T.

    2017-03-01

    Features of the formation of silver nanoparticles (Ag-NPs) via intramolecular redox transformation of the Ag(I) complex of 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde isonicotinoylhydrazone in organic solvents with donor numbers DN > 19 were studied. The stability of the organic sols depended on the nature of the dispersion medium and the presence of oxygen and water in it. The physical chemistry and morphology of the Ag-NP in the organic sol were investigated using molecular absorption spectroscopy, transmission electron microscopy, and atomic force microscopy. The silver sol consisted of spherical Ag-NPs 5-20 nm in size with a characteristic absorption band near 440 nm. It was found that the silver complex with valence tautomerism was a promising precursor for Ag-NPs. The synthesized Ag-NPs showed high antimicrobial activity compared with standard antibiotics and Ag-containing agents (MIC = 0.007 μmol/mL).

  18. Educational Alchemy: The Transformation of Schools.

    Science.gov (United States)

    Mugits, Michael James

    Alchemy is the magical or mysterious power or process involving chemistry, magic, and philosophy in transforming one thing into another. The term is often used to describe the medieval study that sought to transform cheaper metals into gold or silver. "Educational alchemy" is the process by which schools are converted into more effective learning…

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

    Science.gov (United States)

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

    2015-07-21

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

  20. Formation of novel assembled silver nanostructures from polyglycol solution

    International Nuclear Information System (INIS)

    Zhang Jie; Liu Ke; Dai Zhihui; Feng Yuying; Bao Jianchun; Mo Xiangyin

    2006-01-01

    This paper described a simple and mild chemical reduction approach to prepare novel silver nanostructures with different morphologies. Dendritic silver nanostructure was obtained by a fast reduction reaction using hydrazine as a reducing agent in aqueous solution of polyglycol, while both the zigzag and linear Ag nanostructures were slowly assembled using polyglycol as a reducing agent. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and field emission scanning electron microscopy (FE-SEM) were used to characterize the obtained silver nanostructures. Fourier transform infrared absorption (FT-IR) spectra were recorded to show that there exists a certain coordination of the oxygen atoms in the polyglycol with Ag + ions in aqueous solution of the AgNO 3 /polyglycol. Furthermore, the examination of the morphologies of the products obtained at different stages of the reaction of Ag + ions with polyglycol revealed that such a coordination is of utmost importance for the formation of the silver nanostructures, namely polyglycol provided lots of active sites for the coordination, nucleation, growth and serves as backbones for directing the assembly of the metal particles formed. The formation mechanism of the dendritic silver nanostructure was called a coordination-reduction-nucleation-growth-fractal growth process. The strong surface plasmon absorption bands at 470 nm for the zigzag silver and at 405 nm for the dendritic silver were found

  1. Synthesis and characterization of silver-polypyrrole film composite

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-15

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

  2. Synthesis and characterization of silver-polypyrrole film composite

    International Nuclear Information System (INIS)

    Ayad, Mohamad M.; Zaki, Eman

    2009-01-01

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

  3. Synthesis and characterization of silver-polypyrrole film composite

    Science.gov (United States)

    Ayad, Mohamad. M.; Zaki, Eman

    2009-11-01

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

  4. Electrochemical synthesis and optical properties of organically capped silver nanoparticles

    International Nuclear Information System (INIS)

    Rabinal, M.K.; Kalasad, M.N.; Praveenkumar, K.; Bharadi, V.R.; Bhikshavartimath, A.M.

    2013-01-01

    Graphical abstract: A simple electrochemical method for the synthesis of organically capped silver nanoparticles by anodic dissolution of silver. Highlights: ► Electrochemical method has been developed to synthesize silver nanoparticles. ► The bulk silver is converted to monodispersed silver nanoparticles by anodic dissolution of metal. ► It permits in-situ capping of nanoparticles with suitable organic molecules. ► The method is simple, economical and greener in approach to prepare bulk quantity of stable sols of silver nanoparticles. -- Abstract: A top to bottom approach has been adopted to prepare silver nanoparticles by electrochemical dissolution of metal in suitable organic solvents. The method is being simple and economical, also permits in situ capping of nanoparticles with organic molecules. Thioglycolic acid is used as capping/stabilizing agent. Optical absorption, transmission electron microscopy, fourier transform infrared spectroscopy and X-ray diffraction measurements were carried out to study the effect of capping molecules on the size and shape of nanoparticles. It is found that thioglycolic acid is an effective capping agent and hence the resultant sol, even with high density of nanoparticles, is kinetically more stable. The present method can also be extended to synthesize other metal nanoparticles capped with various organic molecules

  5. Silver and gold nanoparticles for sensor and antibacterial applications

    Science.gov (United States)

    Bindhu, M. R.; Umadevi, M.

    2014-07-01

    Green biogenic method for the synthesis of gold and silver nanoparticles using Solanum lycopersicums extract as reducing agent was studied. The biomolecules present in the extract was responsible for reduction of Au3+ and Ag+ ions from HAuCl4 and AgNO3 respectively. The prepared nanoparticles were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) technique to identify the size, shape of nanoparticles and biomolecules act as reducing agents. UV-visible spectra show the surface plasmon resonance peak at 546 nm and 445 nm corresponding to gold and silver nanoparticles respectively. Crystalline nature of the nanoparticles was evident from TEM images and XRD analysis. TEM images showed average size of 14 nm and 12 nm for prepared gold and silver nanoparticles respectively. FTIR analysis provides the presence of biomolecules responsible for the reduction and stability of the prepared silver and gold nanoparticles. XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. The prepared gold and silver nanoparticles show good sensing and antimicrobial activity.

  6. Methanol sensing characteristics of conducting polypyrrole-silver nanocomposites

    Science.gov (United States)

    Kabir, L.; Mandal, S. K.

    2012-05-01

    Methanol sensing characteristics of conducting polypyrrole-silver nanocomposites are reported here. The nanocomposites are synthesized by wet chemical technique with different amount of silver loadings (5-15 mol%). The sensitivity of the nanocomposites upon exposure to gas molecules is critically dependent on the silver loadings and the concentration of the exposed gas. This is possibly instigated by the modified metal-polymer interface and the polar nature of the constituent metal and the exposed gas. Interaction of the alcohol gas with the polypyrrole chains in the presence of silver effectively determines the change in resistance and hence the sensitivity of the nanocomposites upon exposure to methanol. The adsorption of methanol molecules within the nanocomposites and the subsequent chemical reactions are studied by Fourier transform infrared (FTIR) spectroscopy.

  7. Surface Phenomena at Silver Nanoparticles in the Context of Toxicology

    DEFF Research Database (Denmark)

    Miclaus, Teodora

    2015-01-01

    is also observed in the third study, where transformation form metallic to sulphur-bound monovalent silver is shown inside cells. Ag nanoparticles are shown to dissolve much more rapidly inside cells than in cell culture medium and the ions are thought to bind to sulphur-containing proteins, disrupting...... associated with engineered nanomaterials. Among these materials, silver nanoparticles are some of the most widely employed and thus represent a major point of focus in nanotoxicology and the topic of this PhD thesis. While nanoparticles have, upon synthesis, well-defined characteristics, specific...... of nanotoxicology. The main aim of this PhD research is to investigate these phenomena at the surface of silver nanoparticles under conditions that are relevant for in vitro studies in order to understand their implications for nano-silver toxicity. Upon contact with biological fluids, particles get coated...

  8. Excellent electrochemical performance of graphene-silver nanoparticle hybrids prepared using a microwave spark assistance process

    International Nuclear Information System (INIS)

    Shanmugharaj, A.M.; Ryu, Sung Hun

    2012-01-01

    Highlights: ► A simple synthesis route is explored in preparing graphene-metal nanoparticle hybrids using cost effective microwave radiation process. ► Electrochemical performance of the synthesized graphene-silver nanoparticle hybrids have been compared with graphite and silver nanoparticle based anode materials. ► Graphene-silver nanoparticle hybrid exhibits stable charge/discharge characteristics of 714 mAh g −1 and it is significantly higher compared to natural graphite and silver based electrodes. - Abstract: A simple method is described for the synthesis of graphene-silver nanoparticle hybrids from graphite and silver precursors using microwave spark ignition process. Adding ecofriendly free radical initiators, in the presence of hydrogen peroxide solution leads to the expansion of graphite to graphene nanosheets. Simultaneously, silver ions intercalated between the graphene layers are reduced to silver nanocrystals leading to the development of graphene-silver nanoparticle hybrids. Transmission electron microscopic (TEM) studies reveal the successful formation of graphene-silver nanoparticle hybrids. X-ray diffraction (XRD) shows that the silver nanoparticles formed on the graphene surfaces are face centered cubic crystals. The surface composition and functional groups present on the graphene-silver nanoparticle hybrids are corroborated using X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FT-IR). The lithium storage capacity of the synthesized material, when used as an anode material for rechargeable lithium secondary batteries is investigated. Its first specific discharge capacity is observed to be 580 mAh g −1 and this has been increased to 827 mAh g −1 , by incorporating the silver nanoparticles between the graphene platelets. The reversible capacity of the graphene-silver nanoparticle hybrids is observed to be 714 mAh g −1 , which is significantly higher compared to that of graphene (420 mAh g −1

  9. Influence of surfactant on the preparation of silver nanoparticles by polyol method

    International Nuclear Information System (INIS)

    Dung Dang, Thi My; Tuyet Le, Thi Thu; Dang, Mau Chien; Fribourg-Blanc, Eric

    2012-01-01

    In this study, silver nanoparticles were synthesized from silver nitrate via a polyol method in ambient atmosphere. In our synthesis route, polyvinylpyrrolidone (PVP) is used as both size controller and capping agent, ethylene glycol acts both as solvent and reducing agent. The obtained silver nanoparticles were characterized by ultraviolet-visible spectrophotometry which indicated the formation of nanoparticles. Investigation of Fourier transform infrared spectroscopy clearly demonstrated the coordination between silver nanoparticles and PVP. Transmission electron microscopy (TEM) contributed to the particle size analysis. The surface plasmon resonance peak in absorption spectra of silver colloidal solution showed absorption from 406 to 409 nm. The average size of the resulting silver nanoparticles was below 10 nm with a dependency on the PVP concentration. (paper)

  10. Biosynthesis, characterization and antimicrobial action of silver nanoparticles from root bark extract of Berberislycium Royle.

    Science.gov (United States)

    Mehmood, Ansar; Murtaza, Ghulam; Bhatti, Tariq Mahmood; Kausar, Rehana; Ahmed, Muhammad Jamil

    2016-01-01

    Various biological methods are being recognized for the fabrication of silver nanoparticles, which are used in several fields. The phytosynthesis of nanoparticles came out as a cost effective and enviro-friendly approach. When root bark extract of Berberis lycium was treated with silver ions, they reduced to silver nanoparticles, which were spherical, crystalline, size ranged from 10-100nm and capped by biomolecules. Synthesized silver nanoparticles were characterized by UV-visible spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Fourier Transform Infra Red Spectroscopy (FTIR). The plant mediated synthesized silver nanoparticles showed pronounced antimicrobial activities against both Gram negative bacteria (Escherichia coli, Klebseilla pneumoniae, Pseudomonas aeruginosa) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis). The plant mediated process proved to be non-toxic and low cost contender as reducing agent for synthesizing stable silver nanoparticles.

  11. Electrospinning of silver nanoparticles loaded highly porous cellulose acetate nanofibrous membrane for treatment of dye wastewater

    Science.gov (United States)

    Wang, Ke; Ma, Qian; Wang, Shu-Dong; Liu, Hua; Zhang, Sheng-Zhong; Bao, Wei; Zhang, Ke-Qin; Ling, Liang-Zhong

    2016-01-01

    In this paper, silver nanoparticles (NPs) were reduced form silver nitrate. Morphology and distribution of the synthesized silver NPs were characterized. In order to obtain cellulose acetate (CA), nanofibrous membrane with high effective adsorption performance to carry silver NPs for treatment of dye wastewater, different solvent systems were used to fabricate CA nanofibrous membranes with different morphologies and porous structures via electrospinning. Morphologies and structures of the obtained CA nanofibrous membranes were compared by scanning electron microscopy (SEM), which showed that CA nanofibrous membrane obtained from acetone/dichloromethane (1/2, v/v) was with the highly porous structure. SEM, energy-dispersive spectrometry and Fourier transform infrared spectrometry showed that the silver NPs were effectively incorporated in the CA nanofibrous membrane and the addition of silver NPs did not damage the porous structure of the CA nanofibrous membrane. Adsorption of dye solution (rhodamine B aqueous solution) revealed that the highly porous CA nanofibrous membrane exhibited effective adsorption performance and the addition of silver NPs did not affect the adsorption of the dye. Antibacterial property of the CA nanofibrous membrane showed that the silver-loaded highly porous CA nanofibrous membrane had remarkable antibacterial property when compared to the CA nanofibrous membrane without silver NPs. The silver-loaded highly porous CA nanofibrous membrane could be considered as an ideal candidate for treatment of the dye wastewater.

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

    Directory of Open Access Journals (Sweden)

    Deepen Paul

    2013-12-01

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

  13. Antimicrobial, mechanical and thermal studies of silver particle-loaded polyurethane.

    Science.gov (United States)

    Paul, Deepen; Paul, Sharmistha; Roohpour, Nima; Wilks, Mark; Vadgama, Pankaj

    2013-12-09

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

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

    Science.gov (United States)

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

    2017-09-01

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

  15. Phycosynthesis of silver nanoparticles and photocatalytic degradation of methyl orange dye using silver (Ag) nanoparticles synthesized from Hypnea musciformis (Wulfen) J.V. Lamouroux

    Science.gov (United States)

    Ganapathy Selvam, G.; Sivakumar, K.

    2015-06-01

    In the present investigation, simple and eco-friendly chemical reaction for the synthesis reported on biological synthesis of nano-sized silver and biosynthesis of silver nanoparticles using Hypnea musciformis at room temperature along with photocatalytic degradation of methyl orange dye. The nanoparticles of silver were formed by the reduction of silver nitrate to aqueous silver metal ions during exposure to the extract of red alga H. musciformis. The optical properties of the obtained silver nanoparticles were characterized by applying UV-visible absorption and room temperature photoluminescence. The X-ray diffraction results revealed that the synthesized silver nanoparticles were in the cubic phase. The existence of functional groups was identified using Fourier transform infrared spectroscopy. The morphology and size of the synthesized particles were studied with atomic force microscope measurements. Photocatalytic degradation of methyl orange was measured spectrophotometrically by using silver as nanocatalyst under visible light illumination. The results revealed that biosynthesized silver nanoparticles using H. musciformis was found to be impressive in degrading methyl orange.

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

    Science.gov (United States)

    Hauri, James F.; Niece, Brian K.

    2011-01-01

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

  17. Sublimation-Induced Shape Evolution of Silver Cubes

    KAUST Repository

    Ding, Yong

    2009-12-18

    The heat is on: Surface sublimation and shape transformation of silver cubes, enclosed by {100} surfaces and about 100nm in size, are examined by in situ transmission electron microscopy (see picture). High-index surfaces, such as {110}, of face-centered cubic metals are more stable when the temperature is close to the melting point.

  18. Phase stability of silver particles embedded calcium phosphate ...

    Indian Academy of Sciences (India)

    Keywords. Biomaterial; hydroxyapatite; Raman spectroscopy. Abstract. In this paper, we report the compositional variation-dependent phase stability of hydroxyapatite (Ca10(PO4)6(OH)2) on doping with silver. The transformation of hydroxyapatite to (/) tricalcium phosphate phases during sintering has been explored ...

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

    Science.gov (United States)

    Lu, Haifei

    Noble-metal nanocrystals have received considerable attention in recent years for their size and shape dependent localized surface Plasmon resonances (LSPR). Various applications based on colloidal nanoparticles, such as surface enhanced Raman scattering (SERS), surface enhanced fluorescence (SEF), plasmonic sensing, photothermal therapy etc., have been broadly explored in the field of biomedicine, because of their extremely large optical scattering and absorption cross sections, as well as giant electric field enhancement on their surface. However, despite its high chemical stability, gold exhibits quite large losses and electric field enhancement is comparatively weaker than silver. Silver nanoparticles synthesized by the traditional technique only cover an LSPR ranged from 420~500 nm. On the other hand, the range of 500~660 nm, which is covered by several easily available commercial laser lines, very limited colloidal silver nanostructures with controllable size and shape have been reported, and realization of tuning the resonance to longer wavelengths is very important for the practical applications. In this thesis, a systematic study on photochemical synthesis of silver nanodecahedrons (NDs) and related nanostructures, and their plasmonic field enhancements are presented. First, the roles of chemicals and the light source during the formation of silver nanoparticles have been studied. We have also developed a preparation route for the production size-controlled silver nanodecahedrons (LSPR range 420 ~ 660 nm) in high purity. Indeed our experiments indicate that both the chemicals and the light sources can affect the shape and purity of final products. Adjusting the molar ratio between sodium citrate and silver nitrate can help to control the crystal structure following rapid reduction from sodium borohydride. Light from a blue LED (465 nm) can efficiently transform the polyvinylpyrrolidone stabilized small silver nanoparticles into silver NDs through photo

  20. Absorbent silver (I) antimicrobial fabrics

    Science.gov (United States)

    In recent years, silver in form of silver ions, has been gaining importance in the wound management as an effective broad-spectrum antimicrobial agent. Silver has a long history as an antimicrobial agent, especially in the treatment of wounds. Alginates and carboxymethyl (CM) cotton contain carboxyl...

  1. Silver-palladium cathode

    Energy Technology Data Exchange (ETDEWEB)

    Poizot, Philippe [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007, Universite de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cedex (France); Simonet, Jacques, E-mail: jacques.simonet@univ-rennes1.f [Laboratoire MaCSE, UMR CNRS 6226, Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France)

    2010-12-15

    The formation of silver-palladium electrodes is described. It mainly corresponds to the palladization of silver by means of treatment with palladium salts (nitrate and sulphate) in acidic media. Other ways may exist such as the modification of solid conductors like carbons by deposition of a silver-palladium alloy. By using those electrodes in polar aprotic solvents, the one-electron cleavage of carbon-halogen bonds of most alkyl iodides and bromides may yield free alkyl radicals. Coupling and cross-coupling reactions can easily be carried out at such electrodes. The present review aims at discussing the electro-catalytic process as well as providing an update on the state of the art on this new mode of scission regarding carbon-heteroatom bonds.

  2. Silver azide photolysis

    OpenAIRE

    Surovoy, E. P.; Sirik, S. M.; Bugerko, L. N.

    2007-01-01

    The preliminary silver azide light irradiation (?=365 nm, I>1·1015 quanta·cm-2·с-1) in vacuum (Р=1·10-5 Pа) alongside with increase in photolisys speed and a photocurrent results in occurrence new long-wave (up to ?=1280 nm) area of spectral sensitivity. Constants of silver azide photolysis speed are determined. As a result of measurements of a contact potential difference, volt - ampere of characteristics, a contact photoelectrical moving force, a photocurrent it is established, that at silv...

  3. Silver-Russell syndrome

    Directory of Open Access Journals (Sweden)

    Shohela Akhter

    2016-08-01

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

  4. Silver against Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

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

    2007-01-01

    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 ig/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 ig/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate...

  5. Laser-fabricated castor oil-capped silver nanoparticles

    Science.gov (United States)

    Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir

    2011-01-01

    Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time. PMID:21698083

  6. Laser-fabricated castor oil-capped silver nanoparticles.

    Science.gov (United States)

    Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir

    2011-01-01

    Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time.

  7. Green synthesis of silver nanoparticles and its application for mosquito control

    Directory of Open Access Journals (Sweden)

    Naba Kumar Mondal

    2014-02-01

    Full Text Available Objective: To synthesize and characterize silver nanoparticles from aqueous root extract of Parthenium hysterophorus (P. hysterophorus and also to evaluate the potentiality of synthesized silver nanoparticles as larvacidal agent against Culex quinquefasciatus (Cx. quinquefasciatus. Methods: The silver nano particles were generated using root extract of P. hysterophorus. The characterization of synthesized nanoparticles was done by visual color change, UV-Vis spectrum, scanning electron micrograph, fluorescent microscope and Fourier transform infrared spectroscopy. Results: It was found that aqueous silver ions can be reduced by aqueous root extract of P. hysterophorus to generate extremely stable silver nanoparticles in aqueous medium. Larvae were exposed to varying concentrations of plant extracts, aqueous silver nitrate solution and synthesized silver nanoparticles for 0, 24 and 48 h separately. Aqueous root extract showed moderate larvicidal effects; however, the maximum efficacy (60.18% was observed with the synthesized silver nanoparticles against the larvae of Cx. quinquefasciatus. Conclusions: These results suggest that the green synthesis of silver nanoparticles have the potential to be used as an ideal eco-friently approach for the control of the Cx. quinquefasciatus. This is the first report on the mosquito larvicidal activity of the nano particle synthesized by P. hysterophorus.

  8. Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens

    Science.gov (United States)

    Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Vanaja, Mahendran; Annadurai, Gurusamy

    2016-07-01

    The present investigation shows the biosynthesis of eco-friendly silver nanoparticles using culture supernatant of Enterococcus sp. and study the effect of enhanced antimicrobial activity, anticancer activity against pathogenic bacteria, fungi and cancer cell lines. Silver nanoparticles was synthesized by adding 1 mM silver nitrate into the 100 ml of 24 h freshly prepared culture supernatant of Enterococcus sp. and were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Selected Area Diffraction X-Ray (SAED), Energy Dispersive X Ray (EDX) and Fourier Transform Infra red Spectroscopy (FT-IR). The synthesized silver nanoparticles were impregnated with commercial antibiotics for evaluation of enhanced antimicrobial activity. Further these synthesized silver nanoparticles were assessed for its anticancer activity against cancer cell lines. In this study crystalline structured nanoparticles with spherical in the size ranges from 10 to 80 nm and it shows excellent enhanced antimicrobial activity than the commercial antibiotics. The in vitro assay of silver nanoparticles on anticancer have great potential to inhibit the cell viability. Amide linkages and carboxylate groups of proteins from Enterococcus sp. may bind with silver ions and convert into nanoparticles. The activities of commercial antibiotics were enhanced by coating silver nanoparticles shows significant improved antimicrobial activity. Silver nanoparticles have the great potential to inhibit the cell viability of liver cancer cells lines (HepG2) and lung cancer cell lines (A549).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-06

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Science.gov (United States)

    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.

  12. Kyllinga brevifolia mediated greener silver nanoparticles

    Science.gov (United States)

    Isa, Norain; Bakhari, Nor Aziyah; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

    2017-12-01

    Kyllinga brevifolia extract (KBE) was studied in this research as capping as well as reducing agent for the synthesis of greener plant mediated silver nanoparticles. This research was conducted in order to identify the compounds in the KBE that probable to work as reductant for the synthesis of Kyllinga brevifolia-mediated silver nanoparticles (AgNPs). Screening test such as Thin Layer Chromatography (TLC), Fourier Transform Infra-Red (FTIR), Carlo Erba Elemental analysis and Gas Chromatography-Mass Spectroscopy (GCMS) were used in identifying the natural compounds in KBE. The as-prepared AgNPs were characterized by UV-vis spectroscopy (UV-vis), Transmission Electron Microscope (TEM) and X-ray Diffraction (XRD). The TEM images showed that the as-synthesized silver have quasi-spherical particles are distributed uniformly with a narrow distribution from 5 nm to 40 nm. The XRD results demonstrated that the obtained AgNPs were face centre-cubic (FCC) structure. The catalytic activity of AgNPs on reduction of methylene blue (MB) using sodium borohydride (SB) was analyzed using UV-vis spectroscopy. This study showed that the efficacy of mediated AgNPs in catalysing the reduction of MB.

  13. 21 CFR 73.2500 - Silver.

    Science.gov (United States)

    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 ferrous...

  14. Characterization of Electrochemically Generated Silver

    Science.gov (United States)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

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

  15. Silver matrix composites reinforced with galvanically silvered particles

    OpenAIRE

    J. Śleziona; J. Wieczorek,

    2007-01-01

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

  16. Biosynthesis of silver nanoparticles using Ocimum sanctum (Tulsi) leaf extract and screening its antimicrobial activity

    Science.gov (United States)

    Singhal, Garima; Bhavesh, Riju; Kasariya, Kunal; Sharma, Ashish Ranjan; Singh, Rajendra Pal

    2011-07-01

    Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles. In this study, biosynthesis of stable silver nanoparticles was done using Tulsi ( Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV-vis spectrophotometer, Atomic Absorption Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV-vis absorption spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4-30 nm possessing antimicrobial activity suggesting their possible application in medical industry.

  17. The reduction process of phytic acid-silver ion system: A pulse radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Ravi [Radiation and Photochemistry Division, Chemistry Group, Bhabha Atomic Research Center, Mumbai 400 085 (India)]. E-mail: rjudrin@yahoo.com; Mukherjee, Tulsi [Radiation and Photochemistry Division, Chemistry Group, Bhabha Atomic Research Center, Mumbai 400 085 (India)

    2007-05-15

    Reduction of silver ion in a silver-phytic acid (1:1 ratio) system has been studied using pulse radiolysis technique. Time-resolved transformation of the intermediates, Ag{sup +{yields}}Ag{sup 0{yields}}Ag{sub 2} {sup +{yields}}Ag{sub 3} {sup 2+}, has been clearly observed in the reduction of silver-phytic acid (1:1) system. The effect of phytic acid on the formation and decay of initial silver clusters has been also studied. The surface plasmon absorption band of stable silver nanoparticle (410 nm) and dynamic light scattering technique has been used to characterize the nanoparticles and measure the average size (R {sub av}=100 nm)

  18. Biocatalytic and antibacterial visualization of green synthesized silver nanoparticles using Hemidesmus indicus.

    Science.gov (United States)

    Latha, M; Sumathi, M; Manikandan, R; Arumugam, A; Prabhu, N M

    2015-05-01

    In the present investigation, we described the green synthesis of silver nanoparticles using plant leaf extract of Hemidesmus indicus. The synthesized silver nanoparticles were characterized by UV-visible spectroscopy, fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). TEM images proved that the synthesized silver nanoparticles were spherical in shape with an average particle size of 25.24 nm. To evaluate antibacterial efficacy, bacteria was isolated from poultry gut and subjected to 16S rRNA characterization and confirmed as Shigella sonnei. The in vitro antibacterial efficacy of synthesized silver nanoparticles was studied by agar bioassay, well diffusion and confocal laser scanning microscopy (CLSM) assay. The H. indicus mediated synthesis of silver nanoparticles shows rapid synthesis and higher inhibitory activity (34 ± 0.2 mm) against isolated bacteria S. sonnei at 40 μg/ml. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Biosynthesis of silver nanoparticles using aqueous leaf extract of Thevetia peruviana Juss and its antimicrobial activities

    Science.gov (United States)

    Oluwaniyi, Omolara O.; Adegoke, Haleemat I.; Adesuji, Elijah T.; Alabi, Aderemi B.; Bodede, Sunday O.; Labulo, Ayomide H.; Oseghale, Charles O.

    2016-08-01

    Biosynthesizing of silver nanoparticles using microorganisms or various plant parts have proven more environmental friendly, cost-effective, energy saving and reproducible when compared to chemical and physical methods. This investigation demonstrated the plant-mediated synthesis of silver nanoparticles using the aqueous leaf extract of Thevetia peruviana. UV-Visible spectrophotometer was used to measure the surface plasmon resonance of the nanoparticles at 460 nm. Fourier Transform Infrared showed that the glycosidic -OH and carbonyl functional group present in extract were responsible for the reduction and stabilization of the silver nanoparticles. X ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and Selected Area Electron Diffraction analyses were used to confirm the nature, morphology and shape of the nanoparticles. The silver nanoparticles are spherical in shape with average size of 18.1 nm. The synthesized silver nanoparticles showed activity against fungal pathogens and bacteria. The zone of inhibition observed in the antimicrobial study ranged between 10 and 20 mm.

  20. Coleus aromaticus leaf extract mediated synthesis of silver nanoparticles and its bactericidal activity

    Science.gov (United States)

    Vanaja, Mahendran; Annadurai, Gurusamy

    2013-06-01

    The utilization of various plant resources for the biosynthesis of metallic nanoparticles is called green nanotechnology, and it does not utilize any harmful chemical protocols. The present study reports the plant-mediated synthesis of silver nanoparticles using the plant leaf extract of Coleus aromaticus, which acts as a reducing and capping agent. The silver nanoparticles were characterized by ultraviolet visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and the size of the silver nanoparticles is 44 nm. The bactericidal activity of the silver nanoparticles was carried out by disc diffusion method that showed high toxicity against Bacillus subtilis and Klebsiella planticola. Biosynthesis of silver nanoparticles by using plant resources is an eco-friendly, reliable process and suitable for large-scale production. Moreover, it is easy to handle and a rapid process when compared to chemical, physical, and microbe-mediated synthesis process.

  1. Coconut water assisted green synthesis of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Erusan Kuppan Elumalai

    2014-01-01

    Full Text Available Aim of the Study: The synthesis, characterization and application of biologically synthesized nanomaterials are an important aspect in nanotechnology. Materials and Methods: The present study deals with the synthesis of silver nanoparticles (Ag-NPs using the coconut water (C. nucifera as the reducing agent. The formation of Ag-NPs was characterized by UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM, EDX, X-ray Diffraction (XRD and FTIR spectroscopy. Results: The synthesized Ag-NPs were predominately polydispersed. Crystalline nature of the nanoparticle in the face centered cubic (fcc structure are confirmed by the peaks in the XRD pattern corresponding to (111, (200, (220 and (311 planes. Fourier Transform Infra-Red (FT-IR spectroscopy analysis showed that the synthesized nanoparicles was capped with bimolecular compounds which are responsible for the reduction of silver ions. Conclusion: The approach of green synthesis appears to be cost efficient, ecofriendly and easy alternative to conventional methods of silver nanoparticle synthesis.

  2. Coconut water assisted green synthesis of silver nanoparticles.

    Science.gov (United States)

    Elumalai, Erusan Kuppan; Kayalvizhi, Karuppsamy; Silvan, Simon

    2014-10-01

    The synthesis, characterization and application of biologically synthesized nanomaterials are an important aspect in nanotechnology. The present study deals with the synthesis of silver nanoparticles (Ag-NPs) using the coconut water (C. nucifera) as the reducing agent. The formation of Ag-NPs was characterized by UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM), EDX, X-ray Diffraction (XRD) and FTIR spectroscopy. The synthesized Ag-NPs were predominately polydispersed. Crystalline nature of the nanoparticle in the face centered cubic (fcc) structure are confirmed by the peaks in the XRD pattern corresponding to (111), (200), (220) and (311) planes. Fourier Transform Infra-Red (FT-IR) spectroscopy analysis showed that the synthesized nanoparicles was capped with bimolecular compounds which are responsible for the reduction of silver ions. The approach of green synthesis appears to be cost efficient, ecofriendly and easy alternative to conventional methods of silver nanoparticle synthesis.

  3. Silver nanoparticles delivery system based on natural rubber latex membranes

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, Eder Jose, E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo/FFCLRP-DF (Brazil); Kinoshita, Angela [Universidade do Sagrado Coracao (Brazil); Ramos, Ana Paula [Universidade de Sao Paulo/FFCLRP-DQ (Brazil); Baffa, Oswaldo [Universidade de Sao Paulo/FFCLRP-DF (Brazil)

    2013-04-15

    The search for new materials for biomedical applications is extremely important. Here, we present results on the performance of a silver nanoparticles delivery system using natural rubber latex (NRL) as the polymeric matrix. Our aim was to obtain an optimized wound dressing by combining materials with potential healing action. The synthesis of silver nanoparticles and their characterization by UV-Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, and Fourier transform infrared spectroscopy (FTIR) are depicted. The NRL membranes are good matrix for silver nanoparticles and allow for their gradual release. The release of 30 nm silver nanoparticles by the NRL membranes depends on their mass percentage in NRL membranes. The total concentration of AgNP released by the NRL membranes was calculated. The AgNP attached to the cis-isoprene molecules in the NRL matrix remain attached to the membrane ({approx}0.1 % w/w). So, only the AgNP bound to the non-rubber molecules are released. FTIR spectra suggest that non-rubber molecules, like aminoacids and proteins, associated with the serum fraction of the NRL may be attached to the surfaces of the released nanoparticles, thereby increasing the release of such molecules. The released silver nanoparticles are sterically stabilized, more stable and well dispersed. Because the serum fraction of the NRL is responsible for the angiogenic properties of the matrix, the silver nanoparticles could increment the angiogenic properties of NRL. This biomaterial has desirable properties for the fabrication of a wound dressing with potential healing action, since it combines the angiogenic and antibacterial properties of the silver nanoparticles with the increased angiogenic properties of the NRL.Graphical AbstractThe AgNP attached to the cis-isoprene molecules remain in the NRL matrix and only the AgNP bound to the non-rubber molecules (NRL serum fraction) are released. The released AgNP are

  4. Silver nanoparticles delivery system based on natural rubber latex membranes

    Science.gov (United States)

    Guidelli, Éder José; Kinoshita, Angela; Ramos, Ana Paula; Baffa, Oswaldo

    2013-04-01

    The search for new materials for biomedical applications is extremely important. Here, we present results on the performance of a silver nanoparticles delivery system using natural rubber latex (NRL) as the polymeric matrix. Our aim was to obtain an optimized wound dressing by combining materials with potential healing action. The synthesis of silver nanoparticles and their characterization by UV-Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, and Fourier transform infrared spectroscopy (FTIR) are depicted. The NRL membranes are good matrix for silver nanoparticles and allow for their gradual release. The release of 30 nm silver nanoparticles by the NRL membranes depends on their mass percentage in NRL membranes. The total concentration of AgNP released by the NRL membranes was calculated. The AgNP attached to the cis-isoprene molecules in the NRL matrix remain attached to the membrane ( 0.1 % w/w). So, only the AgNP bound to the non-rubber molecules are released. FTIR spectra suggest that non-rubber molecules, like aminoacids and proteins, associated with the serum fraction of the NRL may be attached to the surfaces of the released nanoparticles, thereby increasing the release of such molecules. The released silver nanoparticles are sterically stabilized, more stable and well dispersed. Because the serum fraction of the NRL is responsible for the angiogenic properties of the matrix, the silver nanoparticles could increment the angiogenic properties of NRL. This biomaterial has desirable properties for the fabrication of a wound dressing with potential healing action, since it combines the angiogenic and antibacterial properties of the silver nanoparticles with the increased angiogenic properties of the NRL.

  5. Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity.

    Science.gov (United States)

    Kumar, Deenadayalan Ashok; Palanichamy, V; Roopan, Selvaraj Mohana

    2014-06-05

    A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Biosynthesis of silver nanoparticles from the marine seaweed Sargassum wightii and their antibacterial activity against some human pathogens

    Science.gov (United States)

    Shanmugam, N.; Rajkamal, P.; Cholan, S.; Kannadasan, N.; Sathishkumar, K.; Viruthagiri, G.; Sundaramanickam, A.

    2014-10-01

    In this paper, we have reported on biological synthesis of nano-sized silver and its antibacterial activity against human pathogens. The nanoparticles of silver were formed by the reduction of silver nitrate to aqueous silver metal ions during exposure to the extract of marine seaweed Sargassum wightii. The optical properties of the obtained silver nanoparticles were characterized using UV-visible absorption and room temperature photoluminescence. The X-ray diffraction results reveal that the synthesized silver nanoparticles are in the cubic phase. The existence of functional groups was identified using Fourier transform infrared spectroscopy. The morphology and size of the synthesized particles were studied with atomic force microscope and high-resolution transmission electron microscope measurements. The synthesized nanoparticles have an effective antibacterial activity against S. aureus, K. pneumoniae, and S. typhi.

  7. Comparison study on biosynthesis of silver nanoparticles using fresh and hot air oven dried IMPERATA CYLINDRICA leaf

    Science.gov (United States)

    Najmi Bonnia, Noor; Fairuzi, Afiza Ahmad; Akhir, Rabiatuladawiyah Md.; Yahya, Sabrina M.; Rani, Mohd Azri Ab; Ratim, Suzana; Rahman, Norafifah A.; Akil, Hazizan Md

    2018-01-01

    The perennial rhizomatous grass; Imperata cylindrica (I. cylindrica) has been reported rich in various phytochemicals. In present study, silver nanoparticles were synthesized from aqueous leaf extract of I. cylindrica at two different leaf conditions; fresh leaves and hot-air oven dried leaves. Biosynthesized silver nanoparticles were characterized by UV-visible spectroscopy, field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). Maximum absorption was recorded between 400 nm to 500 nm. FESEM analysis revealed that the silver nanoparticles predominantly form spherical shapes. The particles sizes were ranging from 22-37 nm. The elemental composition of the synthesized silver nanoparticles was confirmed by using energy dispersive X-ray spectroscopy (EDX) analysis. Fourier transform infrared spectroscopy (FTIR) confirmed the reducing and stabilizing actions came from biomolecules associated with I. cylindrica leaf extract. Thus in this investigation, an environmentally safe method to synthesized silver nanoparticles using local plant extract was successfully established.

  8. Biological synthesis of silver nanoparticles

    International Nuclear Information System (INIS)

    Maliszewska, I; Szewczyk, K; Waszak, K

    2009-01-01

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

  9. MOD silver metallization for photovoltaics

    Science.gov (United States)

    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.

  10. Biosynthesis of silver nanoparticles.

    Science.gov (United States)

    Poulose, Subin; Panda, Tapobrata; Nair, Praseetha P; Théodore, Thomas

    2014-02-01

    Metal nanoparticles have unique optical, electronic, and catalytic properties. There exist well-defined physical and chemical processes for their preparation. Those processes often yield small quantities of nanoparticles having undesired morphology, and involve high temperatures for the reaction and the use of hazardous chemicals. Relatively, the older technique of bioremediation of metals uses either microorganisms or their components for the production of nanoparticles. The nanoparticles obtained from bacteria, fungi, algae, plants and their components, etc. appear environment-friendly, as toxic chemicals are not used in the processes. In addition to this, the formation of nanoparticles takes place at almost normal temperature and pressure. Control of the shape and size of the nanoparticles is possible by appropriate selection of the pH and temperature. Three important steps are the bioconversion of Ag+ ions, conversion of desired crystals to nanoparticles, and nanoparticle stability. Generally, nanoparticles are characterized by the UV-visible spectroscopy and use of the electron microscope. Silver nanoparticles are used as antimicrobial agents and they possess antifungal, anti-inflammatory, and anti-angiogenic properties. This review highlights the biosynthesis of silver nanoparticles by various organisms, possible mechanisms of their synthesis, their characterization, and applications of silver nanoparticles.

  11. Size-dependent structure of silver nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Koski, Kristie Jo [Univ. of California, Berkeley, CA (United States)

    2008-12-31

    Silver noble metal nanoparticles that are<10 nm often possess multiply twinned grains allowing them to adopt shapes and atomic structures not observed in bulk materials. The properties exhibited by particles with multiply twinned polycrystalline structures are often far different from those of single-crystalline particles and from the bulk. I will present experimental evidence that silver nanoparticles<10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. Results for nanoparticles in the intermediate size range of 5 to 10 nm suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. I propose a mechanism for this transitiion that considers the bond-length distribution in idealized multiply twinned icosahedral particles. Results for nanoparticles of 3.9 nm suggest a reversible linear pressure-dependent orthorhombic distortion. This distortion is interpreted in the context of idealized decahedral particles. In addition, given these size-dependent measurements of silver nanoparticle compression with pressure, we have constructed a pressure calibration curve. Encapsulating these silver nanoparticles in hollow metal oxide nanospheres then allows us to measure the pressure inside a nanoshell using x-ray diffraction. We demonstrate the measurement of pressure gradients across nanoshells and show that these nanoshells have maximum resolved shear strengths on the order of 500 MPa to IGPa.

  12. Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

    Energy Technology Data Exchange (ETDEWEB)

    Venil, Chidambaram Kulandaisamy, E-mail: ckvenil@gmail.com [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Sathishkumar, Palanivel [Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Malathi, Mahalingam [Department of Chemistry, Bannari Amman Institute of Technology, Sathyamangalam 638 401, Tamil Nadu (India); Usha, Rajamanickam [Department of Microbiology, Karpagam University, Coimbatore 641 023, Tamil Nadu (India); Jayakumar, Rajarajeswaran [Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia); Yusoff, Abdull Rahim Mohd [Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Ahmad, Wan Azlina, E-mail: azlina@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia)

    2016-02-01

    In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ({sup 1}H NMR and {sup 13}C NMR), UV–Vis, and LC–MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36 μg mL{sup −1}. This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent. - Highlights: • First report on flexirubin mediated silver nanoparticles • Silver nanoparticles synthesised using flexirubin • Flexirubin mediated silver nanoparticles found to possess in vitro anti-cancer activity.

  13. Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

    International Nuclear Information System (INIS)

    Venil, Chidambaram Kulandaisamy; Sathishkumar, Palanivel; Malathi, Mahalingam; Usha, Rajamanickam; Jayakumar, Rajarajeswaran; Yusoff, Abdull Rahim Mohd; Ahmad, Wan Azlina

    2016-01-01

    In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ( 1 H NMR and 13 C NMR), UV–Vis, and LC–MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36 μg mL −1 . This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent. - Highlights: • First report on flexirubin mediated silver nanoparticles • Silver nanoparticles synthesised using flexirubin • Flexirubin mediated silver nanoparticles found to possess in vitro anti-cancer activity

  14. Formation process of silver-polypyrrole coaxial nanocables synthesized by redox reaction between AgNO3 and pyrrole in the presence of poly(vinylpyrrolidone).

    Science.gov (United States)

    Chen, Aihua; Kamata, Kaori; Nakagawa, Masaru; Iyoda, Tomokazu; Haiqiao Wang, Haiqiao; Li, Xiaoyu

    2005-10-06

    We have recently demonstrated a one-step process to fabricate silver-polypyrrole (PPy) coaxial nanocables (Chen, A.; Wang, H.; Li, X. Chem. Commun. 2005, 14, 1863). The formation process of silver-PPy coaxial nanocables is discussed in this article. It was found from the results of TEM and SEM images that large numbers of silver atoms were formed when AgNO3 was added to a pyrrole solution. Then silver atoms transform to silver-PPy nanosheets with regular morphology, which will connect together to be more stable. Silver-PPy nanocables will be able to grow at the expense of the silver-PPy nanosheets. Poly(vinylpyrrolidone) (PVP) plays crucial roles in this process: as a capping agent to form silver nanowires, and as a dispersant of pyrrole monomers, which can influence the site at which pyrrole monomer exists. On the basis of experimental analysis, the possible mechanism was proposed. Because of the effect of PVP, silver ions and pyrrole monomers are apt to be adsorbed at the [111] and [100] facets of silver nanosheets, respectively. Obvious polymerization will take place on the boundary of the [111] and [100] facets. The PPy layer stays stable on the [100] facets. Meanwhile, newly formed silver atoms and silver nanosheets will further ripen and grow on the [111] facets. In a word, the morphology of final products and the formation process are determined by the reaction site between AgNO3 and the pyrrole monomer, which is influenced by PVP.

  15. In-situ photo-assisted deposition of silver particles on hydrogel fibers for antibacterial applications

    International Nuclear Information System (INIS)

    Raho, Riccardo; Paladini, Federica; Lombardi, Fiorella Anna; Boccarella, Sandro; Zunino, Benedetta; Pollini, Mauro

    2015-01-01

    Silver nanoparticles (AgNPs) have attracted intensive research interest and have been recently incorporated in polymers, medical devices, hydrogels and burn dressings to control the proliferation of microorganisms. In this study a novel silver antibacterial coating was deposited for the first time on hydrogel fibers through an in-situ photo-chemical reaction. Hydrogel blends obtained by mixing different percentages of silver-treated and untreated fibers were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four different fluids, such as phosphate buffered saline (PBS), simulated body fluid (SBF), chemical simulated wound fluid (cSWF), and deionized water (DI water), were used for evaluating the swelling properties. The results obtained confirmed that the presence of silver did not affect the properties of the hydrogel. Moreover, the results obtained through inductively coupled plasma mass spectrometry (ICP-MS) demonstrated very low silver release values, thus indicating the perfect adhesion of the silver coating to the substrate. Good antibacterial capabilities were demonstrated by any hydrogel blend on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through agar diffusion tests and optical density readings. - Highlights: • An innovative nano-silver deposition technique was adopted on hydrogel fibers. • Antibacterial effects was verified by agar diffusion and optical density tests. • The swelling properties were investigated using 4 different fluids. • Hydrogel blends with different percentages of silver-treated fibers were compared

  16. In-situ photo-assisted deposition of silver particles on hydrogel fibers for antibacterial applications

    Energy Technology Data Exchange (ETDEWEB)

    Raho, Riccardo [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); CBN, Center for Biomolecular Nanotechnologies, Fondazione Istituto Italiano di Tecnologia, Via Barsanti, 73010 Arnesano, Lecce (Italy); Paladini, Federica; Lombardi, Fiorella Anna [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Boccarella, Sandro [Megatex S.p.A., Via Cima D' Aosta, 73040 Melissano, Lecce (Italy); Zunino, Benedetta [Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00198 Roma (Italy); Pollini, Mauro, E-mail: mauro.pollini@unisalento.it [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Silvertech Ltd., Via per Monteroni, 73100 Lecce (Italy)

    2015-10-01

    Silver nanoparticles (AgNPs) have attracted intensive research interest and have been recently incorporated in polymers, medical devices, hydrogels and burn dressings to control the proliferation of microorganisms. In this study a novel silver antibacterial coating was deposited for the first time on hydrogel fibers through an in-situ photo-chemical reaction. Hydrogel blends obtained by mixing different percentages of silver-treated and untreated fibers were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four different fluids, such as phosphate buffered saline (PBS), simulated body fluid (SBF), chemical simulated wound fluid (cSWF), and deionized water (DI water), were used for evaluating the swelling properties. The results obtained confirmed that the presence of silver did not affect the properties of the hydrogel. Moreover, the results obtained through inductively coupled plasma mass spectrometry (ICP-MS) demonstrated very low silver release values, thus indicating the perfect adhesion of the silver coating to the substrate. Good antibacterial capabilities were demonstrated by any hydrogel blend on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through agar diffusion tests and optical density readings. - Highlights: • An innovative nano-silver deposition technique was adopted on hydrogel fibers. • Antibacterial effects was verified by agar diffusion and optical density tests. • The swelling properties were investigated using 4 different fluids. • Hydrogel blends with different percentages of silver-treated fibers were compared.

  17. A Deep Investigation of the Thermal Decomposition Process of Supported Silver Catalysts

    International Nuclear Information System (INIS)

    Jiang, Jun; Xu, Tianhao; Li, Yaping; Lei, Xiaodong; Zhang, Hui; Evans, D. G.; Sun, Xiaoming; Duan, Xue

    2014-01-01

    A deep understanding of the metallic silver catalysts formation process on oxide support and the formation mechanism is of great scientific and practical meaning for exploring better catalyst preparing procedures. Herein the thermal decomposition process of supported silver catalyst with silver oxalate as the silver precursor in the presence of ethylenediamine and ethanolamine is carefully investigated by employing a variety of characterization techniques including thermal analysis, in situ diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation mechanism of supported silver particles was revealed. Results showed that formation of metallic silver begins at about 100 .deg. C and activation process is essentially complete below 145 .deg. C. Formation of silver was accompanied by decomposition of oxalate group and removal of organic amines. Catalytic performance tests using the epoxidation of ethylene as a probe reaction showed that rapid activation (for 5 minutes) at a relatively low temperature (170 .deg. C) afforded materials with optimum catalytic performance, since higher activation temperatures and/or longer activation times resulted in sintering of the silver particles

  18. Green Synthesis of Silver Nanoparticles by using Eucalyptus Globulus Leaf Extract

    Science.gov (United States)

    Balamurugan, Madheswaran; Saravanan, Shanmugam

    2017-12-01

    A single step eco-friendly, energy efficient and economically scalable green method was employed to synthesize silver nanoparticles. In this work, the synthesis of silver nanoparticles using Eucalyptus globulus leaf extract as reducing and capping agent along with water as solvent at normal room temperature is described. Silver nanoparticles were prepared from aqueous silver nitrate solution by adding the leaf extract. The prepared nanoparticles were characterized by using UV-visible Spectrophotometer, X-ray diffractometer, High Resolution Transmission Electron Microscope (HR-TEM) and Fourier Transform Infrared Spectroscope (FTIS). X-ray diffraction studies brought to light the crystalline nature and the face centered cubic structure of the silver nanoparticles. Using HR-TEM. the nano sizes and morphology of the particles were studied. The mean sizes of the prepared silver nanoparticles ranged from 30 to 36 nm. The density of the particles was tuned by varying the molar ratio of silver nitrate. FTIS studies showed the functional group of organic molecules which were located on the surface of the silver nanoparticles. Originating from the leaf extracts, these organic molecules reduced and capped the particles.

  19. Corrosion protection for silver reflectors

    Science.gov (United States)

    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.

  20. Silver Nanowire Exposure Results in Internalization and Toxicity to Daphnia Magna

    Science.gov (United States)

    Scanlan, Leona D.; Reed, Robert B.; Loguinov, Alexandre V.; Antczak, Philipp; Tagmount, Abderrahmane; Aloni, Shaul; Nowinski, Daniel Thomas; Luong, Pauline; Tran, Christine; Karunaratne, Nadeeka; Pham, Don; Lin, Xin Xin; Falciani, Francesco; Higgins, Chris P.; Ranville, James F.; Vulpe, Chris D.; Gilbert, Benjamin

    2013-01-01

    Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physico-chemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within one-hour following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry (spICPMS) distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy (SEM) imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna. PMID:24099093

  1. Rethinking Schools and the Power of Silver

    Science.gov (United States)

    Sleeter, Christine

    2011-01-01

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

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

    DEFF Research Database (Denmark)

    Hadrup, Niels; Lam, Henrik Rye

    2014-01-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin...

  3. Synthesis of sub-micron silver and silver sulfide particles via solvothermal silver azide decomposition

    International Nuclear Information System (INIS)

    Grocholl, Luke; Wang Jianjun; Gillan, Edward G.

    2003-01-01

    Many transition-metal azides are thermodynamically unstable with respect to the elements and thus, may serve as energetic precursor sources in nanoscale metal particle synthesis. This report describes the use of silver azide (AgN 3 ) in nonaqueous, solvothermal decomposition reactions to produce crystalline sub-micron silver particles and interconnected structures. The thermal decomposition of AgN 3 directly produces silver and N 2 and no secondary chemical reducing agent is required. This solvothermal conversion was examined in toluene, tetrahydrofuran (THF), and trioctylamine below 250 deg. C. The coordinating solvents produced the smallest particles (150-500 nm), while the toluene reaction products were near 1 μm in size. The addition of soluble elemental sulfur to the THF reaction results in the growth of silver sulfide particles near 1 μm in size. The silver and Ag 2 S products are crystalline by X-ray diffraction and show some faceting by scanning electron microscopy

  4. Process for making silver metal filaments

    Science.gov (United States)

    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.

  5. A Silver DNAzyme.

    Science.gov (United States)

    Saran, Runjhun; Liu, Juewen

    2016-04-05

    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.

  6. GREEN SYNTHESIS OF SILVER NANO PARTICLES

    OpenAIRE

    Pallavi Sharma; Valentina V Umrania

    2017-01-01

    The research was carried out to investigate the synthesis of silver nano particles. The silver nano particles have wide tremendous application in the therapeutics, antimicrobials, diagnostics, catalysis, micro-electronics and high sensitivity biomolecular detection. Silver nano particles grow in a single-step method, at room temperature, and with no addition of external energy. The silver nanoparticles were synthesized from silver nitrate aqueous solution through a simple, ecofriendly and cos...

  7. Synthesis, Characterization, and Evaluation of the Antibacterial Activity of Allophylus serratus Leaf and Leaf Derived Callus Extracts Mediated Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kero Jemal

    2017-01-01

    Full Text Available Allophylus serratus mediated silver nanoparticles biosynthesis, characterization, and antimicrobial activity were described. The synthesis of silver nanoparticles was confirmed by visual observation: UV-Vis spectrum, X-ray diffraction (XRD, Scanning Electron Microscopy (SEM, Energy Dispersive Spectroscopy (EDS, and Fourier Transform Infra-Red (FTIR. UV-Vis spectroscopy studies showed that the absorption spectra of synthesized silver nanoparticles from leaf and callus extracts had absorbance peak range of 440 nm and 445 nm, respectively. The X-RD pattern revealed the presence of crystalline, dominantly spherical silver nanoparticles in the sample having size ranging from 42 to 50 nm. The XRD peaks 38.2°, 44.1°, 64.1°, and 77.0° for leaf extract and 38.1°, 44.3°, 64.5°, 77.5°, and 81.33° for callus extract can be assigned the plane of silver crystals (111, (200, (220, and (311, respectively, and indicate that the silver nanoparticles are face-centered, cubic, and crystalline in nature. SEM and EDS analysis also confirmed the presence of silver nanoparticles. The FTIR results showed the presence of some biomolecules in extracts that act as reducing and capping agent for silver nanoparticles biosynthesis. The synthesized silver nanoparticles showed significant antibacterial activity against Klebsiella pneumoniae and Pseudomonas aeruginosa.

  8. Silver clusters from nozzle expansions

    International Nuclear Information System (INIS)

    Hagena, O.F.

    1990-01-01

    This note reports on the first successful experiments to generate silver clusters (N≤100) in supersonic nozzle flows. A mixture of argon/silver-vapor was used expanding from a conical nozzle (0.35 mm, 10deg full cone angle, 17 mm long conical section). Source temperature and total pressure ranged up to 2200 K/300 kPa, and silver partial pressure up to 25 kPa. The data confirm the scaling laws developed to compare clustering of metals with that of rare gases. (orig.)

  9. MOD silver metallization for photovoltaics

    Science.gov (United States)

    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.

  10. Wool keratin-stabilized silver nanoparticles.

    Science.gov (United States)

    Lü, Xiaowen; Cui, Shuxun

    2010-06-01

    In this paper, we explored a facile method to prepare stable silver nanoparticles (Ag NPs) using extracted wool keratin as the capping agent. The formation of Ag NPs was investigated by UV-Vis spectroscopy, X-ray photo-electron spectrometer and X-ray diffraction spectrometer. The morphology of the NPs was detected by scanning electron microscopy in vacuum and atomic force microscopy in fluid. The possible interactions between the silver core and the capping agent have been investigated using Fourier transform infrared spectroscopy. The effects of keratin concentration on the incubation of the NPs were studied by UV-Vis spectra. It was found that under alkaline condition the process of incubation was much faster than that under neutral pH condition. The photoluminescence properties of the Ag NPs were also investigated. We believe that this work is helpful for the high-value utilization of wool and other keratin-rich bioresource. (c) 2010 Elsevier Ltd. All rights reserved.

  11. Release of silver nanoparticles from outdoor facades.

    Science.gov (United States)

    Kaegi, Ralf; Sinnet, Brian; Zuleeg, Steffen; Hagendorfer, Harald; Mueller, Elisabeth; Vonbank, Roger; Boller, Markus; Burkhardt, Michael

    2010-09-01

    In this study we investigate the release of metallic silver nanoparticles (Ag-NP) from paints used for outdoor applications. A facade panel mounted on a model house was exposed to ambient weather conditions over a period of one year. The runoff volume of individual rain events was determined and the silver and titanium concentrations of 36 out of 65 runoff events were measured. Selected samples were prepared for electron microscopic analysis. A strong leaching of the Ag-NP was observed during the initial runoff events with a maximum concentration of 145 micro Ag/l. After a period of one year, more than 30% of the Ag-NP were released to the environment. Particles were mostly <15 nm and are released as composite colloids attached to the organic binders of the paint. Microscopic results indicate that the Ag-NP are likely transformed to considerably less toxic forms such as Ag2S. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  12. Biosynthesis of silver nanoparticle from leaf extract of Desmodium gangeticum (L.) DC. and its biomedical potential

    Science.gov (United States)

    Thirunavoukkarasu, M.; Balaji, U.; Behera, S.; Panda, P. K.; Mishra, B. K.

    2013-12-01

    An aqueous leaf extract of Desmodium gangeticum was employed to synthesize silver nano particles. Rapid formation of stable silver nanoparticles were observed on exposure of the aqueous leaf extract with solution of silver nitrate. The silver nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy (TEM), and Fourier Transform Infra-Red spectroscopy (FTIR) UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and Fourier Transform Infra-Red spectroscopy (FTIR). UV-visible spectrum of the aqueous medium peaked at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. SEM analysis revealed the spherical shape of the particles with sizes ranging from 18 to 39 nm and the EDAX spectrum confirmed the presence of silver along with other elements in the plant metabolite. Further, these biologically synthesized nanoparticles were found to be highly toxic against pathogenic bacteria Escherichia coli, thus implying significance of the present study in production of biomedical products.

  13. Bioprospective of Sorbus aucuparia leaf extract in development of silver and gold nanocolloids.

    Science.gov (United States)

    Dubey, Shashi Prabha; Lahtinen, Manu; Särkkä, Heikki; Sillanpää, Mika

    2010-10-01

    At the present time the bioprospective field is a dynamic area of research. The rapid biosynthesis of silver and gold nanoparticles without using toxic chemicals is reported here. Sorbus aucuparia is omnipresent in Europe. The aqueous leaves extract of the plant were used as reducing agent for the synthesis of silver and gold nanoparticles from their salt solutions. The synthesized nanoparticles were spherical, triangular and hexagonal in shape with an average size of 16 and 18nm for silver and gold, respectively. Different extract quantities, metal concentrations, temperatures and contact times were investigated to find their effect on nanoparticles synthesis. The resulting silver and gold nanoparticles were characterized by transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). The concentration of residual silver and gold ions was measured by Inductively Coupled Plasma (ICP) spectroscopy. Silver and gold nanoparticle suspensions gave maximum UV-vis absorbance at 446 and 560nm, respectively. The XRD data illustrated characteristic diffraction patterns of the elemental silver and gold phases and the average size of the crystallites were estimated from the peak profiles by Scherrer method. FTIR spectra of the leaf extract before and after the development of nanoparticles were determined to allow identification of possible functional groups responsible for the conversion of metal ions to metal nanoparticles.

  14. Anglesite and silver recovery from jarosite residues through roasting and sulfidization-flotation in zinc hydrometallurgy.

    Science.gov (United States)

    Han, Haisheng; Sun, Wei; Hu, Yuehua; Jia, Baoliang; Tang, Honghu

    2014-08-15

    Hazardous jarosite residues contain abundant valuable minerals that are difficult to be recovered by traditional flotation process. This study presents a new route, roasting combined with sulfidization-flotation, for the recovery of anglesite and silver from jarosite residues of zinc hydrometallurgy. Surface appearance and elemental distribution of jarosite residues was examined by scanning electron microscopy and energy dispersive X-ray spectrometry analysis, respectively. Decomposition and transformation mechanisms of jarosite residues were illustrated by differential thermal analysis. Results showed that after roasting combined with flotation, the grade and recovery of lead were 43.89% and 66.86%, respectively, and those of silver were 1.3 kg/t and 81.60%, respectively. At 600-700 °C, jarosite was decomposed to release encapsulated valuable minerals such as anglesite (PbSO4) and silver mineral; silver jarosite decomposed into silver sulfate (Ag2SO4); and zinc ferrite (ZnO · Fe2O3) decomposed into zinc sulfate (ZnSO4) and hematite (Fe2O3). Bared anglesite and silver minerals were modified by sodium sulfide and easily collected by flotation collectors. This study demonstrates that the combination of roasting and sulfidization-flotation provides a promising process for the recovery of zinc, lead, and silver from jarosite residues of zinc hydrometallurgy. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Preparation and characterization of silver loaded montmorillonite modified with sulfur amino acid

    Science.gov (United States)

    Li, Tian; Lin, Oulian; Lu, Zhiyuan; He, Liuimei; Wang, Xiaosheng

    2014-06-01

    The Na+ montmorillonite (MMT) was modified with sulfur containing amino acid (L-cystine, L-cysteine or L-methionine) and characterized by energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectrum (FT-IR). The results showed the modification was smooth and the surface condition of MMT was changed with sulfur containing groups. Then silver was loaded on the modified MMTs via ion-exchange reaction under microwave irradiation, the spectra of X-ray photoelectron spectroscopy (XPS), EDS and FT-IR confirmed the successful loading of massive silver and the strong interaction between sulfur and silver, the silver loaded L-cystine modified MMT (Ag@AA-MMT-3) with a silver content of 10.93 wt% was the highest of all. Further more, the Ag@AA-MMT-3 was under the irradiation of a UV lamp to turn silver ions to silver nano particles (Ag NPs). The XPS, specific surface area (SSA), transmission electron microscopy (TEM), XRD patterns and UV-vis spectra proved the existence of uniform nano scaled metallic Ag NPs. By contrast, the UV irradiated Ag@AA-MMT-3 (Ag@AA-MMT-UV) showed a much better slow release property than Ag@AA-MMT-3 or Ag@MMT. The Ag@AA-MMT-UV showing a large inhibition zone and high inhibition ratio presented very good antibacterial property.

  16. Green synthesis of silver nanoparticles from marigold flower and its synergistic antimicrobial potential

    Directory of Open Access Journals (Sweden)

    Hemali Padalia

    2015-09-01

    Full Text Available In the present study, silver nanoparticles were synthesized using flower broth of Tagetes erecta as reductant by a simple and eco-friendly route. The aqueous silver ions when exposed to flower broth were reduced and resulted in green synthesis of silver nanoparticles. The silver nanoparticles were characterized by UV–visible spectroscopy, zeta potential, Fourier transform infra-red spectroscopy (FTIR, X-ray diffraction, Transmission electron microscopy (TEM analysis, Energy dispersive X-ray analysis (EDX and selected area electron diffraction (SAED pattern. UV–visible spectrum of synthesized silver nanoparticles showed maximum peak at 430 nm. TEM analysis revealed that the particles were spherical, hexagonal and irregular in shape and size ranging from 10 to 90 nm and Energy dispersive X-ray (EDX spectrum confirmed the presence of silver metal. Synergistic antimicrobial potential of silver nanoparticles was evaluated with various commercial antibiotics against Gram positive (Staphylococcus aureus and Bacillus cereus, Gram negative (Escherichia coli and Pseudomonas aeruginosa bacteria and fungi (Candida glabrata, Candida albicans, Cryptococcae neoformans. The antifungal activity of AgNPs with antibiotics was better than antibiotics alone against the tested fungal strains and Gram negative bacteria, thus signification of the present study is in production of biomedical products.

  17. Room temperature synthesis and high temperature frictional study of silver vanadate nanorods.

    Science.gov (United States)

    Singh, D P; Polychronopoulou, K; Rebholz, C; Aouadi, S M

    2010-08-13

    We report the room temperature (RT) synthesis of silver vanadate nanorods (consisting of mainly beta-AgV O(3)) by a simple wet chemical route and their frictional study at high temperatures (HT). The sudden mixing of ammonium vanadate with silver nitrate solution under constant magnetic stirring resulted in a pale yellow coloured precipitate. Structural/microstructural characterization of the precipitate through x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the high yield and homogeneous formation of silver vanadate nanorods. The length of the nanorods was 20-40 microm and the thickness 100-600 nm. The pH variation with respect to time was thoroughly studied to understand the formation mechanism of the silver vanadate nanorods. This synthesis process neither demands HT, surfactants nor long reaction time. The silver vanadate nanomaterial showed good lubrication behaviour at HT (700 degrees C) and the friction coefficient was between 0.2 and 0.3. HT-XRD revealed that AgV O(3) completely transformed into silver vanadium oxide (Ag(2)V(4)O(11)) and silver with an increase in temperature from RT to 700 degrees C.

  18. Green Synthesis of Gold and Silver Nanoparticles Using Averrhoa bilimbi Fruit Extract

    International Nuclear Information System (INIS)

    Rimal Isaac, R.S.; Sakthivel, G.; Murthy, Ch.

    2013-01-01

    We report on rapid one-step green synthesis of gold and silver nanoparticles using fruit extract of Averrhoa bilimbi Linn. UV-Vis absorption spectroscopy was used to monitor the quantitative formation of gold and silver nanoparticles. The characteristics of the obtained gold and silver nanoparticles were studied using UV-Vis absorption spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy-dispersive spectroscopy (EDX). UV/Vis spectrum showed Surface Plasmon Resonance (SPR) for both gold and silver nanoparticles at 540 and 420 nm. The EDX spectrum of the solution containing gold and silver nanoparticles confirmed the presence of elemental gold and silver signals. The average diameter of the prepared nanoparticles in solution was about 50–150 nm. Synthesized particles were either hexagonal or rhomboidal in shape. This synthesis approach of gold and silver nanoparticles is cost effective and can be widely used in biological systems. The effect of fruit extract and metal ion concentration was also studied.

  19. Silver nanoparticles embedded titania nanotube with tunable blue light band gap

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei-Lin; Yang, Chung-Sung, E-mail: csyang@mail.ncyu.edu.tw

    2016-06-01

    Silver nanoparticles embedded titania nanotube (SET) have been successfully prepared by titania nanotubes and silver nanoparticles via a template-free reaction. Powder X-ray diffraction (P-XRD) spectra and Fourier transform infrared (FT-IR) spectra show that the charge of silver atoms maintains neutral in the formation of silver nanoparticles. The Ag atom of Ag nanoparticles and the oxygen atom of TiO{sub 2} possess a chemical bonding with an ionic character rather than a covalent character. The quantitative microanalysis data collected from X-ray photo-emission (XPS) spectra indicate that the ratio of Ag/Ti in SET is 15.2 ± 2.7%. The cut-off band gap of SET is adjustable from 420 nm (Ag/Ti = 12.5%) to 430 nm (Ag/Ti = 17.8%). - Highlights: • The self-assembly silver nanoparticles are embedded on titania nanotube. • The charge of silver atoms is neutral in the formation of silver nanoparticles. • The quantitative microanalysis data confirm that ratio of Ag/Ti is 15.2 ± 2.7%. • The band gap of SET locates in the desirable blue light region.

  20. Green Synthesis of Silver Nanoparticles Using an Aqueous Extract of Monotheca buxifolia (Flac.) Dcne

    Science.gov (United States)

    Anwar, Natasha; Khan, Abbas; Shah, Mohib; Anwar, Saad

    2018-01-01

    This study deals with the synthesis and physicochemical investigation of silver nanoparticles using an aqueous extract of Monotheca buxifolia (Flac.). On the treatment of aqueous solution of silver nitrate with the plant extract, silver nanoparticles were rapidly fabricated. The synthesized particles were characterized by using UV-visible spectrophotometry (UV), Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray (EDX) and Scanning electron microscopy (SEM). The formation of AgNPs was confirmed by noting the change in colour through visual observations as well as via UV-Vis spectroscopy. UV-Vis spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 440 nm. FTIR was used to identify the chemical composition of silver nanoparticles and Ag-capped plant extract. The presence of elemental silver was also confirmed through EDX analysis. The SEM analysis of the silver nanoparticles showed that they have a uniform spherical shape with an average size in the range of 40-78 nm. This green system showed better capping and stabilizing agent for the fine particles. Further, in vitro the antioxidant activity of Monotheca buxifolia (Flac.) and Ag-capped with the plant was also evaluated using FeCl3/K3Fe (CN)6 essay.

  1. An in vitro antifungal efficacy of silver nanoparticles activated by diode laser to Candida albicans

    Science.gov (United States)

    Astuti, S. D.; Kharisma, D. H.; Kholimatussa'diah, S.; Zaidan, A. H.

    2017-09-01

    Microbial infectious diseases and increased resistance to antibiotics become urgent problems requiring immediate solutions. One promising alternative is the using of silver nanoparticles. The combination of the microbial inhibition characteristic of silver nanotechnology enhances the activity of antimicrobial effect. This study aims to determine effectiveness of antifungal silver nanoparticles with the activation of the diode laser on Candida albicans. The samples were culture of Candida albicans. Candida albicans cultures were incubated with silver nanoparticles (concentration 10-4 M) and treated with various exposure time of diode laser (15, 30, 45, 60, 75, 90)s. The suspension was planted on Sabouraud Dextrone Agar sterile media and incubated for 24 hours at temperature of 37oC. The number of colony-forming units per milliliter (CFU/ml) was determined after incubation. The results were log-transformed and analyzed by analysis of variance (ANOVA). In this analysis, P value ≤0.05 was considered to indicate a statistically significant difference. The result of this study showed the quantum yield of silver nanoparticles with diode laser 450 nm was 63,61%. Irradiating with diode laser 450 nm for 75 s resulted in the highest decreasing percentage of Candida albicans viability 65,03%. Irradiating with diode laser 450 nm 75 s with silver nanoparticles resulted in the higest decreasing percentage of Candida albicans viability 84,63%. Therefore, silver nanoparticles activated with diode laser irradiation of 450 nm resulted antifungal effect to Candida albicans viability.

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

    Directory of Open Access Journals (Sweden)

    Maciej Milanowski

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

  3. Antibacterial activity of silver nanoparticles synthesized from serine

    Energy Technology Data Exchange (ETDEWEB)

    Jayaprakash, N. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); SRM Valliammai Engineering College, Department of Chemistry, Chennai 603 203 (India); Judith Vijaya, J., E-mail: jjvijayaloyola@yahoo.co.in [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); John Kennedy, L. [Materials Division, School of Advanced Sciences, VIT University, Chennai Campus, Chennai 600 048 (India); Priadharsini, K.; Palani, P. [Department of Center for Advanced Study in Botany, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2015-04-01

    Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV–Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443 nm. The emission spectrum of Ag NPs showed an emission band at 484 nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO{sub 3} against Gram-positive and Gram-negative bacteria. - Highlights: • Microwave irradiation method is used to synthesize silver nanoparticles. • Highly stable silver nanoparticles are produced from serine. • A detailed study of antibacterial activities is discussed. • Formation mechanism of silver microspheres has been proposed.

  4. Size-dependent surface plasmon resonance in silver silica nanocomposites

    International Nuclear Information System (INIS)

    Thomas, Senoy; Nair, Saritha K; Jamal, E Muhammad Abdul; Anantharaman, M R; Al-Harthi, S H; Varma, Manoj Raama

    2008-01-01

    Silver silica nanocomposites were obtained by the sol-gel technique using tetraethyl orthosilicate (TEOS) and silver nitrate (AgNO 3 ) as precursors. The silver nitrate concentration was varied for obtaining composites with different nanoparticle sizes. The structural and microstructural properties were determined by x-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopic (XPS) studies were done for determining the chemical states of silver in the silica matrix. For the lowest AgNO 3 concentration, monodispersed and spherical Ag crystallites, with an average diameter of 5 nm, were obtained. Grain growth and an increase in size distribution was observed for higher concentrations. The occurrence of surface plasmon resonance (SPR) bands and their evolution in the size range 5-10 nm is studied. For decreasing nanoparticle size, a redshift and broadening of the plasmon-related absorption peak was observed. The observed redshift and broadening of the SPR band was explained using modified Mie scattering theory

  5. Green biosynthesis of silver nanoparticles using Curcuma longa tuber powder

    Science.gov (United States)

    Shameli, Kamyar; Ahmad, Mansor Bin; Zamanian, Ali; Sangpour, Parvanh; Shabanzadeh, Parvaneh; Abdollahi, Yadollah; Zargar, Mohsen

    2012-01-01

    Green synthesis of noble metal nanoparticles is a vastly developing area of research. Metallic nanoparticles have received great attention from chemists, physicists, biologists, and engineers who wish to use them for the development of a new-generation of nanodevices. In this study, silver nanoparticles were biosynthesized from aqueous silver nitrate through a simple and eco-friendly route using Curcuma longa tuber-powder extracts, which acted as a reductant and stabilizer simultaneously. Characterizations of nanoparticles were done using different methods, which included ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray fluorescence spectrometry, and Fourier-transform infrared spectroscopy. The ultraviolet-visible spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 415 nm. Transmission electron microscopy showed that mean diameter and standard deviation for the formation of silver nanoparticles was 6.30 ± 2.64 nm. Powder X-ray diffraction showed that the particles are crystalline in nature, with a face-centered cubic structure. The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries. PMID:23341739

  6. Silver nanoparticles in dentistry.

    Science.gov (United States)

    Noronha, Victor T; Paula, Amauri J; Durán, Gabriela; Galembeck, Andre; Cogo-Müller, Karina; Franz-Montan, Michelle; Durán, Nelson

    2017-10-01

    Silver nanoparticles (AgNPs) have been extensively studied for their antimicrobial properties, which provide an extensive applicability in dentistry. Because of this increasing interest in AgNPs, the objective of this paper was to review their use in nanocomposites; implant coatings; pre-formulation with antimicrobial activity against cariogenic pathogens, periodontal biofilm, fungal pathogens and endodontic bacteria; and other applications such as treatment of oral cancer and local anesthesia. Recent achievements in the study of the mechanism of action and the most important toxicological aspects are also presented. Systematic searches were carried out in Web of Science (ISI), Google, PubMed, SciFinder and EspaceNet databases with the keywords "silver nano* or AgNP*" and "dentist* or dental* or odontol*". A total of 155 peer-reviewed articles were reviewed. Most of them were published in the period of 2012-2017, demonstrating that this topic currently represents an important trend in dentistry research. In vitro studies reveal the excellent antimicrobial activity of AgNPs when associated with dental materials such as nanocomposites, acrylic resins, resin co-monomers, adhesives, intracanal medication, and implant coatings. Moreover, AgNPs were demonstrated to be interesting tools in the treatment of oral cancers due to their antitumor properties. The literature indicates that AgNPs are a promising system with important features such as antimicrobial, anti-inflammatory and antitumor activity, and a potential carrier in sustained drug delivery. However, there are some aspects of the mechanisms of action of AgNPs, and some important toxicological aspects arising from the use of this system that must be completely elucidated. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Electrodeposition of silver nanodendrites

    International Nuclear Information System (INIS)

    Kaniyankandy, Sreejith; Nuwad, J; Thinaharan, C; Dey, G K; Pillai, C G S

    2007-01-01

    Nanodendrites of silver were synthesized by electrodeposition using AgNO 3 as the source in ammoniacal solution. The method was remarkably fast, simple and scalable. X-ray diffraction (XRD) studies confirmed the formation of a cubic phase of silver. Scanning electron microscopy (SEM) revealed the formation of well-shaped dendrites. The nanodendrites were hyperbranched with lengths of the order of a few micrometres. The concentration of NH 3 in the electrolyte solution was found to have remarkable influence on the morphology, crystallite size and formation of branched nanodendrites. The branchings were found to occur at regular intervals of ∼50 nm along the main stem. Transmission electron microscopy (TEM) studies confirmed the SEM observation and revealed the 2D nature of the dendrites. Selected area electron diffraction (SAED) revealed that the dendrites were single crystalline in nature and the branching could have a crystalline origin. The direction of growth as inferred from SAED was . UV-vis spectra showed a single broad band centred on ∼380 nm indicating the spherical shape of the individual crystallites. The intrinsic size effect of the metal surface plasmon was used to explain the increase in the broadening on addition of NH 3 . The asymmetry of the band was explained on the basis of agglomeration of crystallites. The nanodendrites prepared by this method showed extension of the plasmon band through the entire visible region, indicating potential use in detection of single molecules based on enhanced Raman scattering. The deposition mechanism is described using the diffusion-limited aggregation model

  8. Silver Nanoparticles in Dental Biomaterials

    OpenAIRE

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; Cruz, Adriana Dibo da; Poiate, EdgardJr.; 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 re...

  9. Hadamard Transforms

    CERN Document Server

    Agaian, Sos; Egiazarian, Karen; Astola, Jaakko

    2011-01-01

    The Hadamard matrix and Hadamard transform are fundamental problem-solving tools in a wide spectrum of scientific disciplines and technologies, such as communication systems, signal and image processing (signal representation, coding, filtering, recognition, and watermarking), digital logic (Boolean function analysis and synthesis), and fault-tolerant system design. Hadamard Transforms intends to bring together different topics concerning current developments in Hadamard matrices, transforms, and their applications. Each chapter begins with the basics of the theory, progresses to more advanced

  10. Franklin D. Roosevelt, Silver, and China.

    OpenAIRE

    Friedman, Milton

    1992-01-01

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

  11. Interfacial reaction of silver ultra-thin film deposited on interpenetrating polymer network substrate by liquor-phase reduction

    Energy Technology Data Exchange (ETDEWEB)

    Tang Dongyan, E-mail: dytang@hit.edu.cn [Department of Chemistry, School of Science, Harbin Institute of Technology, Harbin 150001 (China); Guo Yudi [Department of Chemistry, School of Science, Harbin Institute of Technology, Harbin 150001 (China); Zhang Xiaohong [College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Yin Yuelong [Department of Chemistry, School of Science, Harbin Institute of Technology, Harbin 150001 (China)

    2010-08-01

    The interfacial reaction, metal transformations, and nonmetal bond types of silver ultra-thin film deposited on polyurethane (PU) based interpenetrating polymer networks (IPN) substrate by the liquor-phase reduction at room temperatures were studied by atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The IPN substrate was prepared by dip-pulling precursors onto a silicon wafer or a glass plate, followed by solidification at room temperature. The interpenetrate structures of IPN with two crosslinked networks restricted the aggregation of silver during the reduction and deposition. The devised -OH terminal group in PU simplified the determination of reactive site in IPN and reinforced the adhesion between IPN and silver through interfacial reaction. The XPS results, which matched well with the ATR-FTIR results, verified the chemical reactive site of PU in IPN with silver in the oxide state.

  12. Application of statistical experimental design for optimization of silver nanoparticles biosynthesis by a nanofactory Streptomyces viridochromogenes.

    Science.gov (United States)

    El-Naggar, Noura El-Ahmady; Abdelwahed, Nayera A M

    2014-01-01

    Central composite design was chosen to determine the combined effects of four process variables (AgNO3 concentration, incubation period, pH level and inoculum size) on the extracellular biosynthesis of silver nanoparticles (AgNPs) by Streptomyces viridochromogenes. Statistical analysis of the results showed that incubation period, initial pH level and inoculum size had significant effects (Pbiosynthesis of silver nanoparticles at their individual level. The maximum biosynthesis of silver nanoparticles was achieved at a concentration of 0.5% (v/v) of 1 mM AgNO3, incubation period of 96 h, initial pH of 9 and inoculum size of 2% (v/v). After optimization, the biosynthesis of silver nanoparticles was improved by approximately 5-fold as compared to that of the unoptimized conditions. The synthetic process of silver nanoparticle generation using the reduction of aqueous Ag+ ion by the culture supernatants of S. viridochromogenes was quite fast, and silver nanoparticles were formed immediately by the addition of AgNO3 solution (1 mM) to the cell-free supernatant. Initial characterization of silver nanoparticles was performed by visual observation of color change from yellow to intense brown color. UV-visible spectrophotometry for measuring surface plasmon resonance showed a single absorption peak at 400 nm, which confirmed the presence of silver nanoparticles. Fourier Transform Infrared Spectroscopy analysis provided evidence for proteins as possible reducing and capping agents for stabilizing the nanoparticles. Transmission Electron Microscopy revealed the extracellular formation of spherical silver nanoparticles in the size range of 2.15-7.27 nm. Compared to the cell-free supernatant, the biosynthesized AgNPs revealed superior antimicrobial activity against Gram-negative, Gram-positive bacterial strains and Candida albicans.

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

    Science.gov (United States)

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

    2017-11-01

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

  14. Green synthesis of silver nanoparticles using leaf extract of medicinally potent plant Saraca indica: a novel study

    Science.gov (United States)

    Perugu, Shyam; Nagati, Veerababu; Bhanoori, Manjula

    2016-06-01

    Eco-friendly silver nanoparticles (AgNPs) have various applications in modern biotechnology for better outcomes and benefits to the society. In the present study, we report an eco-friendly synthesis of silver nanoparticles using Saraca indica leaf extract. Characterization of S. indica silver nanoparticles (SAgNPs) was carried out by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometry, Zeta potential, and transmission electron microscopy. SAgNPs showed antimicrobial activity against Gram-negative and Gram-positive bacteria.

  15. Development kinetics of silver clusters on silver halides

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  16. Chemo- and Enantioselective Intramolecular Silver-Catalyzed Aziridinations.

    Science.gov (United States)

    Ju, Minsoo; Weatherly, Cale D; Guzei, Ilia A; Schomaker, Jennifer M

    2017-08-07

    Asymmetric nitrene-transfer reactions are a powerful tool for the preparation of enantioenriched amine building blocks. Reported herein are chemo- and enantioselective silver-catalyzed aminations which transform di- and trisubstituted homoallylic carbamates into [4.1.0]-carbamate-tethered aziridines in good yields and with ee values of up to 92 %. The effects of the substrate, silver counteranion, ligand, solvent, and temperature on both the chemoselectivity and ee value were explored. Stereochemical models were proposed to rationalize the observed absolute stereochemistry of the aziridines, which undergo nucleophilic ring opening to yield enantioenriched amines with no erosion in stereochemical integrity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Tannic acid-mediated green synthesis of antibacterial silver nanoparticles.

    Science.gov (United States)

    Kim, Tae Yoon; Cha, Song-Hyun; Cho, Seonho; Park, Youmie

    2016-04-01

    The search for novel antibacterial agents is necessary to combat microbial resistance to current antibiotics. Silver nanoparticles (AgNPs) have been reported to be effective antibacterial agents. Tannic acid is a polyphenol compound from plants with antioxidant and antibacterial activities. In this report, AgNPs were prepared from silver ions by tannic acid-mediated green synthesis (TA-AgNPs). The reaction process was facile and involved mixing both silver ions and tannic acid. The absorbance at 423 nm in the UV-Visible spectra demonstrated that tannic acid underwent a reduction reaction to produce TA-AgNPs from silver ions. The synthetic yield of TA-AgNPs was 90.5% based on inductively coupled plasma mass spectrometry analysis. High-resolution transmission electron microscopy and atomic force microscopy images indicated that spherical-shaped TA-AgNPs with a mean particle size of 27.7-46.7 nm were obtained. Powder high-resolution X-ray diffraction analysis indicated that the TA-AgNP structure was face-centered cubic with a zeta potential of -27.56 mV. The hydroxyl functional groups of tannic acid contributed to the synthesis of TA-AgNPs, which was confirmed by Fourier transform infrared spectroscopy. The in vitro antibacterial activity was measured using the minimum inhibitory concentration (MIC) method. The TA-AgNPs were more effective against Gram-negative bacteria than Gram-positive bacteria. The MIC for the TA-AgNPs in all of the tested strains was in a silver concentration range of 6.74-13.48 μg/mL. The tannic acid-mediated synthesis of AgNPs afforded biocompatible nanocomposites for antibacterial applications.

  18. Green biosynthesis of silver nanoparticles using Curcuma longa tuber powder

    Directory of Open Access Journals (Sweden)

    Shameli K

    2012-10-01

    Full Text Available Kamyar Shameli,1,2 Mansor Bin Ahmad,1 Ali Zamanian,2 Parvanh Sangpour,2 Parvaneh Shabanzadeh,3 Yadollah Abdollahi,4 Mohsen Zargar51Department of Chemistry, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Materials and Energy Research Center, Karaj, Iran; 3Department of Mathematics, 4Advanced Materials and Nanotechnology Laboratory, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 5Department of Biology, Islamic Azad University, Qom, IranAbstract: Green synthesis of noble metal nanoparticles is a vastly developing area of research. Metallic nanoparticles have received great attention from chemists, physicists, biologists, and engineers who wish to use them for the development of a new-generation of nanodevices. In this study, silver nanoparticles were biosynthesized from aqueous silver nitrate through a simple and eco-friendly route using Curcuma longa tuber-powder extracts, which acted as a reductant and stabilizer simultaneously. Characterizations of nanoparticles were done using different methods, which included ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray fluorescence spectrometry, and Fourier-transform infrared spectroscopy. The ultraviolet-visible spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 415 nm. Transmission electron microscopy showed that mean diameter and standard deviation for the formation of silver nanoparticles was 6.30 ± 2.64 nm. Powder X-ray diffraction showed that the particles are crystalline in nature, with a face-centered cubic structure. The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries.Keywords: silver nanoparticles, Curcuma longa, biosynthesis, green synthesis, transmission electron microscopy

  19. Synthesis of Silver Nanoparticles in Cotton Fabric by Polyvinyl-2-pyrrolidone as a Reducing and Stabilizing Agent

    Directory of Open Access Journals (Sweden)

    Farbod Alimohammadi

    2012-12-01

    Full Text Available Silver nanoparticles have been extensively applied in various fields suchas polymers and textile fibers considering their well known antimicrobialproperties. In conventional methods nano silver is synthesized through chemical reduction however, in this paper a novel synthesis method based on aqueous solution of ammonia/silver complex with cationic stabilizer along with UV-C irradiation is introduced. On this basis, silver nitrate was oxidized with sodium hydroxide and then transformed into [Ag(NH32]+ aqueous solution with ammonia followed by adding PVP as a reducing and stabilizing agent and irradiated by UV-C. The formation of silver nanoparticles was confirmed from the appearance of surface plasmon absorption and the X-ray diffraction (XRD demonstrated that the colloidal nanoparticles were pure silver and Zeta sizer showed particle size distribution. Cotton fabric finishing was accomplished in pad process with various concentrations of nano-sized colloidal silver. Some characteristics of the fabric such as antimicrobial against different microorganisms including gram positive bacteria (Staphylococcous aureus, one gram negative bacteria (Escherichia coli, UV–vis spectrophotometry, color space a*, b* and L*, scanning electron microscopy, EDAX were investigated. Very good antibacterial efficacy against S. aureus and E. coli (higher than 97% appeared even by applying a low nanosilver content (200 ppm for twenty cycles of home laundering. Polyvinyl pyrrolidone resulted in a remarkable control in the release of silver nanoparticle from the coating and can improve the long-term microbiological activity, especially against home laundering.

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

    African Journals Online (AJOL)

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

  1. Reactions of osmabenzene with silver/copper acetylides: from metallabenzene to benzene.

    Science.gov (United States)

    Han, Feifei; Li, Jinhua; Zhang, Hong; Wang, Tongdao; Lin, Zhenyang; Xia, Haiping

    2015-01-07

    The transformations of metallabenzene to substituted benzenes have been achieved by reactions of osmabenzenes with silver/copper acetylides. In this investigation, novel tetraphenylphosphonium salts containing two phosphonium substituents on the same benzene ring are generated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Alternative Plasmonic Materials: Alternative Plasmonic Materials: Beyond Gold and Silver (Adv. Mater. 24/2013)

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Shalaev, Vladimir M.; Boltasseva, Alexandra

    2013-01-01

    Beyond Silver and Gold: Better material buildingblocks are essential in transforming the novel ideas of plasmonics and metamaterials into technologies of the future, as reviewed by Alexandra Boltasseva and co-workers on page 3264. Devices built from tailored materials offer improved performance...

  3. Effect of silver nanoparticle on the properties of poly(methyl ...

    Indian Academy of Sciences (India)

    Abstract. Here we report preparation and characterization of poly(methyl methacrylate)/silver nanoparticles. (PMMA/AgNPs) ... (DC%) during polymerization was followed quantitatively via Fourier transform infrared spectroscopy. DC% of nanocomposite ... Methyl methacrylate (MMA), allyl methacrylate. (AMA) as crosslinking ...

  4. The Mode of Action of Silver and Silver Halides Nanoparticles against Saccharomyces cerevisiae Cells

    Directory of Open Access Journals (Sweden)

    A. A. Kudrinskiy

    2014-01-01

    Full Text Available Silver and silver halides nanoparticles (NPs (Ag, AgCl, AgBr, and AgI capped with two different stabilizers (sodium citrate and nonionic surfactant Tween 80 were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The effect of the biocidal action of as-prepared synthesized materials 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 depending on concentration of silver. The results clearly indicate that the silver ions either remained in the dispersion of silver NPs and silver halides NPs after their synthesis or were generated afterwards by dissolving silver and silver halides particles playing a major part in the cytotoxic activity of NPs against yeast cells. It was also supposed that this activity most likely does not relate to the damage of cell membrane.

  5. Silver and Chan revisited

    Science.gov (United States)

    Walsh, E.; Arnold, R.; Savage, M. K.

    2013-10-01

    Seismic shear waves emitted by earthquakes can be modeled as plane (transverse) waves. When entering an anisotropic medium, they can be split into two orthogonal components moving at different speeds. This splitting occurs along an axis, the fast polarization, that is determined by geologic conditions. We present here a comprehensive analysis of the Silver and Chan (1991) method, used to obtain shear wave splitting parameters, comprising theoretical derivations and statistical tests of the assumptions used to construct the standard errors. We find discrepancies in the derivations of equations in their article, with the most important being a mistake in how the standard errors are calculated. Our simulations suggest that the degrees of freedom are being overestimated by this method, and consequently, the standard errors are too small. Using a set of S waveforms from very similar shallow earthquakes on Reunion Island, we perform a statistical analysis on the noise of these replicates and find that the assumption of Gaussian noise does not hold. Further, the properties of background noise differ substantially from the noise obtained from the shear wave splitting analysis. However, we find that the estimated standard errors for the fast polarization are comparable to the spread in the fast polarization parameters between events. Delay time errors appear to be comparable to delay time estimates once cycle skipping is accounted for. Future work using synthetic seismograms with simulated noise should be conducted to confirm this is the case for earthquakes in general.

  6. Polypyrrole-silver Nanocomposite: Synthesis and Characterization

    OpenAIRE

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

    2016-01-01

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

  7. Preparation of silver nanopatterns on DNA templates

    OpenAIRE

    Dai, Shuxi; Zhang, Xingtang; Li, Tianfeng; Du, Zuliang; Dang, Hongxin

    2010-01-01

    Patterns of silver metal were prepared on DNA networks by a template-directed selective deposition and subsequent metallization process. Scanning force microscopic observations and XPS investigations demonstrated that uniform networks of nanosized silver metal clusters formed after incubation of DNA LB films with silver ions and subsequent chemical reduction of silver ions/DNA films samples. The results showed that this template-directed metallization on DNA LB films provided a simple and eff...

  8. Synthesis, characterization and biocompatibility of silver nanoparticles synthesized from Nigella sativa leaf extract in comparison with chemical silver nanoparticles.

    Science.gov (United States)

    Amooaghaie, Rayhaneh; Saeri, Mohammad Reza; Azizi, Morteza

    2015-10-01

    Despite the development potential in the field of nanotechnology, there is a concern about possible effects of nanoparticles on the environment and human health. In this study, silver nanoparticles (AgNPs) were synthesized by 'green' and 'chemical' methods. In the wet-chemistry method, sodium borohydrate, sodium citrate and silver nitrate were used as raw materials. Leaf extract of Nigella sativa was used as reducing as well as capping agent to reduce silver nitrate in the green synthesis method. In addition, toxic responses of both synthesized AgNPs were monitored on bone-building stem cells of mice as well as seed germination and seedling growth of six different plants (Lolium, wheat, bean and common vetch, lettuce and canola). In both synthesis methods, the colorless reaction mixtures turned brown and UV-visible spectra confirmed the presence of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites and fourier transform infra-red spectroscopy (FTIR) indicated the role of different functional groups in the synthetic process. MTT assay showed cell viability of bone-building stem cells of mice was further in the green AgNPs synthesized using black cumin extract than chemical AgNPs. IC50 (inhibitory concentrations) values for seed germination, root and shoot length for 6 plants in green AgNPs exposures were higher than the chemical AgNPs. These results suggest that cytotoxicity and phytotoxicity of the green synthesized AgNPs were significantly less than wet-chemistry synthesized ones. This study indicated an economical, simple and efficient ecofriendly technique using leaves of N. sativa for synthesis of AgNPs and confirmed that green AgNPs are safer than chemically-synthesized AgNPs. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Visualizing Transformation

    DEFF Research Database (Denmark)

    Pedersen, Pia

    2012-01-01

    Transformation, defined as the step of extracting, arranging and simplifying data into visual form (M. Neurath, 1974), was developed in connection with ISOTYPE (International System Of TYpographic Picture Education) and might well be the most important legacy of Isotype to the field of graphic...... design. Recently transformation has attracted renewed interest because of the book The Transformer written by Robin Kinross and Marie Neurath. My on-going research project, summarized in this paper, identifies and depicts the essential principles of data visualization underlying the process...

  10. Synthesis and characterization of nanophased silver tungstate

    Indian Academy of Sciences (India)

    of silver tungstate nanoparticles. 2. Experimental. Silver tungstate nanoparticles were synthesized by reacting AR grade silver nitrate. (AgNO3) and sodium tungstate (Na2WO4) using distilled water as solvent at room temperature. The method followed for this synthesis is similar to that used by. Takahashi et al [9]. However ...

  11. Topical silver for treating infected wounds

    NARCIS (Netherlands)

    Vermeulen, H.; van Hattem, J. M.; Storm-Versloot, M. N.; Ubbink, D. T.

    2007-01-01

    BACKGROUND: Topical silver treatments and silver dressings are increasingly used for the local treatment of contaminated or infected wounds, however, there is a lack of clarity regarding the evidence for their effectiveness. OBJECTIVES: To evaluate the effects on wound healing of topical silver and

  12. Synthesis and characterization of silver molybdate nanowires ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. Silver molybdate nanowires, nanorods and multipods like structures have been prepared by an organic free hydrothermal process using ammonium molybdate and silver nitrate solutions. The powder X-ray diffraction (PXRD) patterns reveal that the silver molybdate belongs to anorthic structure. The thickness,.

  13. Purification of simulated waste water using green synthesized silver nanoparticles of Piliostigma thonningii aqueous leave extract

    Science.gov (United States)

    Shittu, K. O.; Ihebunna, O.

    2017-12-01

    Synthesis of nanoparticles from various biological systems has been reported, but among all such systems, biosynthesis of nanoparticles from plants is considered the most suitable method. The use of plant material not only makes the process eco-friendly, but also the abundance makes it more economical. The aim of this study was to biologically synthesize silver nanoparticle using Piliostigma thonningii aqueous leaf extract and applied in the purification of laboratory stimulated waste with optimization using the different conditions of silver nanoparticle production such as time, temperature, pH, concentration of silver nitrate and volume of the aqueous extract. The biosynthesized silver nanoparticles were characterized by UV-visible spectrophotometry, nanosizer, energy dispersive x-ray analysis (EDX), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The time intervals for the reaction with aqueous silver nitrate solution shows an increase in the absorbance with time and became constant giving a maximum absorbance at 415 nm at 60 min of incubation. The pH of 6.5, temperature 65 °C, 1.25 mM of silver nitrate and 5 ml of plant extract was the best condition with maximum absorbance. The results from nanosizer, UV-vis and TEM suggested the biosynthesis silver nanoparticle to be spherical ranging from 50 nm to 114 nm. The EDX confirmed the elemental synthesis of silver at 2.60 keV and FTIR suggested the capping agent to be hydroxyl (OH) group with -C=C stretching vibrations. The synthesized silver nanoparticle also shows heavy metal removal activity in laboratory simulated waste water. The safety toxicity studies show no significant difference between the orally administered silver nanoparticles treated water group and control group, while the histopathological studies show well preserved hepatic architecture for the orally administered silver nanoparticle treated waste water group when compared with the control

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

    Energy Technology Data Exchange (ETDEWEB)

    Shirzaditabar, Farzad; Saliminasab, Maryam [Department of Physics, Razi University, Kermanshah 67144-15111 (Iran, Islamic Republic of)

    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.

  15. The toxicity of silver to soil organisms exposed to silver nanoparticles and silver nitrate in biosolids-amended field soil.

    Science.gov (United States)

    Jesmer, Alexander H; Velicogna, Jessica R; Schwertfeger, Dina M; Scroggins, Richard P; Princz, Juliska I

    2017-10-01

    The use of engineered silver nanoparticles (AgNPs) is widespread, with expected release to the terrestrial environment through the application of biosolids onto agricultural lands. The toxicity of AgNPs and silver nitrate (AgNO 3 ; as ionic Ag + ) to plant (Elymus lanceolatus and Trifolium pratense) and soil invertebrate (Eisenia andrei and Folsomia candida) species was assessed using Ag-amended biosolids applied to a natural sandy loam soil. Bioavailable Ag + in soil samples was estimated using an ion-exchange technique applied to KNO 3 soil extracts, whereas exposure to dispersible AgNPs was verified by single-particle inductively coupled plasma-mass spectrometry and transmission electron microscopy-energy dispersive X-ray spectroscopy analysis. Greater toxicity to plant growth and earthworm reproduction was observed in AgNP exposures relative to those of AgNO 3 , whereas no difference in toxicity was observed for F. candida reproduction. Transformation products in the AgNP-biosolids exposures resulted in larger pools of extractable Ag + than those from AgNO 3 -biosolids exposures, at similar total Ag soil concentrations. The results of the present study reveal intrinsic differences in the behavior and bioavailability of the 2 different forms of Ag within the biosolids-soils pathway. The present study demonstrates how analytical methods that target biologically relevant fractions can be used to advance the understanding of AgNP behavior and toxicity in terrestrial environments. Environ Toxicol Chem 2017;36:2756-2765. © 2017 Crown in the Right of Canada. Published Wiley Periodicals Inc., on behalf of SETAC. © 2017 Crown in the Right of Canada. Published Wiley Periodicals Inc., on behalf of SETAC.

  16. Durable silver coating for mirrors

    Science.gov (United States)

    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.

  17. Durable silver coating for mirrors

    International Nuclear Information System (INIS)

    Wolfe, J.D.; Thomas, N.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

  18. A Simple and High Yield Solvothermal Synthesis of Uniform Silver Nanowires with Controllable Diameters

    Directory of Open Access Journals (Sweden)

    M. Khademalrasool

    2015-10-01

    Full Text Available Silver nanowires were synthesized by solvothermal method through reducing silver nitrate (AgNO3 with ethylene glycol (EG in the presence of polyvinylpyrrolidone (PVP. In order to prevent the agglomeration of Ag+ in the initial Ag seeds formation, sodium chloride (NaCl was added into the solution to form AgCl colloids. By dissolving AgCl in the late stages, Ag+ ions were released into the solution. So the diameters of silver nanowires could be controlled by modifying the PVP concentration. The effect of reaction time, reaction temperature, and for first time purity of EG over the shape of resulted silver nanowires were investigated. The wire, sphere and tree-like nanostructures were formed with changing these parameters. The structural and optical properties of the silver nanostructures were studied by X-ray diffraction (XRD, scanning electron microscopy (SEM, field emission scanning electron microscopy (FESEM, Fourier transform infrared spectroscopy (FTIR, and UV–visible absorption spectrophotometer. In order to synthesis silver nanowires with smaller diameters and longer lengths, the optimum molar ratio of PVP/AgNO3, reaction time, reaction temperature, and EG purity were found to be 1.5, 2.5 h, 160 °C, and 99.5%, respectively.

  19. Polyol synthesis of silver nanoplates: The crystal growth mechanism based on a rivalrous adsorption

    International Nuclear Information System (INIS)

    Luo Xiaolin; Li Zongxiao; Yuan Chunlan; Chen Yashao

    2011-01-01

    Highlights: → Silver nanoplates have been successfully synthesized by polyol reduction in the presence of poly (vinylpyrrolidone) (PVP) and HNO 3 . → Due to the discovery of CN - ions in the solution, a mechanism for the anisotropic growth of silver nanoplates is systematically discussed. → TG, FT-IR and SERS were used to provide some direct evidences of rivalrous adsorption between PVP and CN - ions on the surface of the silver crystals. - Abstract: A polyol reducing approach has been applied to synthesize silver nanoplates with an average thickness of 50 nm and edge length of 3 μm in the presence of poly (vinylpyrrolidone) (PVP) and HNO 3 . X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscropy (TEM), and electron diffraction are used to characterize these silver nanoplates. Findings indicate that the nanoplates are single crystals and with their basal plane as (1 1 1) lattice plane. On the basis of the results from thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy, a crystal growth mechanism based on the rivalrous adsorption between PVP and CN - ions on the surface of silver nanoplates is supposed to explain the crystal anisotropic growth.

  20. Synthesis and characterization of silver nanoparticles: effect on phytopathogen Colletotrichum gloesporioides

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Mendez, Miguel A., E-mail: maguilarme@ipn.mx; San Martin-Martinez, Eduardo; Ortega-Arroyo, Lesli [Instituto Politecnico Nacional, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (Mexico); Cobian-Portillo, Georgina [Instituto Politecnico Nacional, Centro Interdisciplinario de Investigacion para el Desarrollo Integral Regional (Mexico); Sanchez-Espindola, Esther [Instituto Politecnico Nacional, Escuela Nacional de Ciencias Biologicas, Prolongacion Manuel M. Carpio s/n, esq. Plan de Ayala (Mexico)

    2011-06-15

    Colloidal silver nanoparticles were synthesized by reducing silver nitrate solutions with glucose, in the presence of gelatin as capping agent. The obtained nanoparticles were characterized by means of UV-Vis spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The response surface methodology (RSM) was also used to determine the influence of the variables on the size of the nanoparticles. The antifungal activity of the silver nanoparticles was evaluated on the phytopathogen Colletotrichum gloesporioides, which causes anthracnose in a wide range of fruits. The UV-Vis spectra indicated the formation of silver nanoparticles preferably spherical and of relatively small size (<20 nm). The above-mentioned was confirmed by TEM, observing a size distribution of 5-24 nm. According to RSM the synthesis variables influenced on the size of the silver nanoparticles. By means of FTIR spectroscopy it was determined that gelatin, through their amide and hydroxyl groups, interacts with nanoparticles preventing their agglomeration. The growth of C. gloesporioides in the presence of silver nanoparticles was significantly delayed in a dose dependent manner.

  1. Antibacterial and anticancerous biocompatible silver nanoparticles synthesised from the cold-tolerant strain of Spirulina platensis

    Directory of Open Access Journals (Sweden)

    Selvaraj Karthick Raja Namasivayam

    2015-04-01

    Full Text Available Objective: To synthesize silver nanoparticles from the biomass of cold tolerant strain of Spirulina platensis and evalute the synthesized nanoparticles against antibacterial and anticancer activity. Methods: Silver nanoparticles were synthesized by the algal culture and characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X ray diffraction studies. Antibacterial activity has been studied with free nanoparticles adopting agar diffusion assay, biofilm inhibition assay and nanoparticles fabricated wound dressing against representative Gram-negative organism Pseudomonas aeruginosa and Gram-positive organism Staphylococcus aureus respectively. The in vitro anticancer activity of silver nanoparticles were screened against human Hep2 cell lines by means of MTT assay. Results: Reduction of silver ions by the algal culture was observed during 72 h of incubation and the synthesized nanoparticles were further characterized. Antibacterial study reveals both the strains were susceptible to free nanoparticles and fabricated wound dressing treatment. The in vitro anticancer activity of silver nanoparticles were screened against human Hep 2 cell lines by means of MTT assay which reveals that cell viability has been reduced as dose dependent manner. Conclusions: The observed results imply that silver nanoparticles synthesized from Spirulina platensis cold tolerant strain can be used as potential antibacterial and anticancerous agent.

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

    Science.gov (United States)

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

    2011-10-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  4. Biosynthesis of silver nanoparticles using Moringa oleifera leaf extract and its application to optical limiting.

    Science.gov (United States)

    Sathyavathi, R; Krishna, M Bala Murali; Rao, D Narayana

    2011-03-01

    The Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. The work presented here with the biosynthesis of silver nanoparticles using Moringa oleifera leaf extract as reducing and stabilizing agent and its application in nonlinear optics. The aqueous silver ions when exposed to Moringa oleifera leaf extract are reduced resulting in silver nanoparticles demonstrating the biosynthesis. The silver nanoparticles were characterized by UV-Visible, X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM) techniques. TEM analysis shows a dispersion of the nanoparticles in a range of 5-80 nm with the average around 46 nm and are crystallized in face centred cubic symmetry. To show that these biosynthesized silver nanoparticles possess very good nonlinear properties similar to those nanoparticles synthesized by chemical route, we carried out the Z-scan studies with a 6 ns, 532 nm pulsed laser. We estimated the nonlinear absorption coefficient and compare it with the literature values of the nanoparticles synthesized through chemical route. The silver nanoparticles suspended in solution exhibited reverse saturable absorption with optical limiting threshold of 100 mJ/cm2.

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

    Energy Technology Data Exchange (ETDEWEB)

    Parashar, Upendra Kumar; Srivastava, Sunil K; Srivastava, Anchal [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumar, Vinod; Saxena, Preeti S [Department of Zoology, Banaras Hindu University, Varanasi 22005 (India); Bera, Tanmay [Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Nath, Gopal [Department of Microbiology, Institute of Medical Science, Banaras Hindu University, Varanasi 22005 (India); Giri, Rajiv, E-mail: anchalbhu@gmail.com [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)

    2011-10-14

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

  6. Non-monotonic wetting behavior of chitosan films induced by silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Praxedes, A.P.P.; Webler, G.D.; Souza, S.T. [Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, AL (Brazil); Ribeiro, A.S. [Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-970 Maceió, AL (Brazil); Fonseca, E.J.S. [Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, AL (Brazil); Oliveira, I.N. de, E-mail: italo@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, AL (Brazil)

    2016-05-01

    Highlights: • The addition of silver nanoparticles modifies the morphology of chitosan films. • Metallic nanoparticles can be used to control wetting properties of chitosan films. • The contact angle shows a non-monotonic dependence on the silver concentration. - Abstract: The present work is devoted to the study of structural and wetting properties of chitosan-based films containing silver nanoparticles. In particular, the effects of silver concentration on the morphology of chitosan films are characterized by different techniques, such as atomic force microscopy (AFM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). By means of dynamic contact angle measurements, we study the modification on surface properties of chitosan-based films due to the addition of silver nanoparticles. The results are analyzed in the light of molecular-kinetic theory which describes the wetting phenomena in terms of statistical dynamics for the displacement of liquid molecules in a solid substrate. Our results show that the wetting properties of chitosan-based films are high sensitive to the fraction of silver nanoparticles, with the equilibrium contact angle exhibiting a non-monotonic behavior.

  7. Teslin transformator

    OpenAIRE

    Ivanić, Doron

    2015-01-01

    U ovom radu se dotiče povijest transformatora. Općenito je obrađen transformator kao električni uređaj s naglaskom na to kako i što koji elementi rade te je obješnjen princip njegovog rada s matematičkim opisom. Teslin je transformator na isti način detaljnije opisan, uz širi proračun njegovih elemenata.

  8. Covariant Transform

    Energy Technology Data Exchange (ETDEWEB)

    Kisil, Vladimir V, E-mail: kisilv@maths.leeds.ac.uk [School of Mathematics, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2011-03-01

    Dedicated to the memory of Cora Sadosky The paper develops theory of covariant transform, which is inspired by the wavelet construction. It was observed that many interesting types of wavelets (or coherent states) arise from group representations which are not square integrable or vacuum vectors which are not admissible. Covariant transform extends an applicability of the popular wavelets construction to classic examples like the Hardy space H{sub 2}, Banach spaces, covariant functional calculus and many others.

  9. Landscape transformation

    OpenAIRE

    Koželj, Urša

    2014-01-01

    In my work, titled Landscape transformation, in the first theoretical-art part, I focus on a landscape painting style in fifteen exposed works, done by different authors. While analyzing depictions of the landscape I establish how the development of photography has in any way affected the transformation of the landscape. In the practical part I describe my work, soft ground graphics with the motive of the landscape, mountain landscape and caves. I devoted the last chapter of my thesis to the ...

  10. Antituberculous effect of silver nanoparticles

    International Nuclear Information System (INIS)

    Kreytsberg, G N; Gracheva, I E; Kibrik, B S; Golikov, I V

    2011-01-01

    The in vitro experiment, involving 1164 strains of the tuberculosis mycobacteria, exhibited a potentiating effect of silver nanoparticles on known antituberculous preparations in respect of overcoming drug-resistance of the causative agent. The in vitro experiment, based on the model of resistant tuberculosis, was performed on 65 white mice. An evident antituberculous effect of the nanocomposite on the basis of silver nanoparticles and isoniazid was proved. Toxicological assessment of the of nanopreparations was carried out. The performed research scientifically establishes efficacy and safety of the nanocomposite application in combination therapy of patients suffering from drug-resistant tuberculosis.

  11. Mineral resource of the month: silver

    Science.gov (United States)

    Brooks, William E.

    2007-01-01

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

  12. Antioxidant properties of biohybrids based on liposomes and sage silver nanoparticles.

    Science.gov (United States)

    Barbinta-Patrascu, Marcela Elisabeta; Bunghez, Ioana-Raluca; Iordache, Stefan Marian; Badea, Nicoleta; Fierascu, Radu-Claudiu; Ion, Rodica Mariana

    2013-03-01

    This paper is aimed to describe a simple and rapid eco-friendly bottom-up approach for the preparation of antioxidant silver bionanostructures using a leaf extract from sage (Salvia officinalis L.). The bioreduction property of sage in the synthesis of silver nanoparticles was investigated by UV-VIS and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy. During their preparation, the particle size analysis was performed by using Dynamic Light Scattering technique. Ultrasonic irradiation was used to obtain sage silver nanoparticles. The morphology (size and shape) of the herbal silver nanoparticles was evaluated by Scanning Electron Microscopy that revealed the formation of spherical phytonanoparticles with size less than 80 nm. In order to increase their stability and their biocompatibility, the sage silver nanoparticles were introduced in two types of liposomes: soybean lecithin- and Chla-DPPC-lipid vesicles which were prepared by thin film hydration method. X-Ray Fluorescence analysis confirmed the silver presence in liposomes/sage-AgNPs biohybrids. The stability of liposomes/herbal AgNPs bioconstructs was checked by zeta potential measurements. The most stable biohybrids: Chla-DPPC/sage-AgNPs with zeta potential value of -34.2 mV, were characterized by Atomic Force Microscopy revealing the spherical and quasi-spherical shaped profiles of these nanobiohybrids with size less than 96 nm. The antioxidant activity of the silver bionanostructures was evaluated using chemiluminescence assay. The developed eco-friendly silver phytonanostructures based on lipid membranes, nanosilver and sage extract, manifest strong antioxidant properties (between 86.5% and 98.6%).

  13. Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Elavazhagan T

    2011-06-01

    Full Text Available Tamizhamudu Elavazhagan, Kantha D ArunachalamCentre for Interdisciplinary Research, Directorate of Research, SRM University, Kattankulathur-603203, Tamilnadu, IndiaAbstract: We used an aqueous leaf extract of Memecylon edule (Melastomataceae to synthesize silver and gold nanoparticles. To our knowledge, this is the first report where M. edule leaf broth was found to be a suitable plant source for the green synthesis of silver and gold nanoparticles. On treatment of aqueous solutions of silver nitrate and chloroauric acid with M. edule leaf extract, stable silver and gold nanoparticles were rapidly formed. The gold nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM, transmission electron microscopy (TEM, energy dispersive X-ray analysis (EDAX and Fourier transform infra-red spectroscopy (FTIR. The kinetics of reduction of aqueous silver and gold ions during reaction with the M. edule leaf broth were easily analyzed by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to M. edule leaf broth, were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. TEM analysis of gold nanoparticles showed formation of triangular, circular, and hexagonal shapes in the size range 10–45 nm. The resulting silver nanoparticles were predominantly square with uniform size range 50–90 nm. EDAX results confirmed the presence of triangular nanoparticles in the adsorption peak of 2.30 keV. Further FTIR analysis was also done to identify the functional groups in silver and gold nanoparticles. The characterized nanoparticles of M. edule have potential for various medical and industrial applications. Saponin presence in aqueous extract of M. edule is responsible for the mass production of silver and gold nanoparticles.Keywords: Memecylon edule, nanoparticles, bioreduction, electron microscopy, FTIR

  14. Chrysopogon zizanioides aqueous extract mediated synthesis characterization of crystalline silver and gold nanoparticles for biomedical applications

    Directory of Open Access Journals (Sweden)

    Arunachalam KD

    2013-07-01

    Full Text Available Kantha D Arunachalam, Sathesh Kumar Annamalai Center for Environmental Nuclear Research, Directorate of Research, SRM University, Chennai, Tamil Nadu, India Abstract: The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3 and chloroauric acid (HAuCl4 respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV-visible spectroscopy, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDAX, Fourier transform infrared spectroscopy (FTIR, and X-ray diffraction (XRD analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. Keywords: nanoparticles, bioreduction, SEM, silver, gold

  15. Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles

    Science.gov (United States)

    Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

    2011-01-01

    We used an aqueous leaf extract of Memecylon edule (Melastomataceae) to synthesize silver and gold nanoparticles. To our knowledge, this is the first report where M. edule leaf broth was found to be a suitable plant source for the green synthesis of silver and gold nanoparticles. On treatment of aqueous solutions of silver nitrate and chloroauric acid with M. edule leaf extract, stable silver and gold nanoparticles were rapidly formed. The gold nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and Fourier transform infra-red spectroscopy (FTIR). The kinetics of reduction of aqueous silver and gold ions during reaction with the M. edule leaf broth were easily analyzed by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to M. edule leaf broth, were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. TEM analysis of gold nanoparticles showed formation of triangular, circular, and hexagonal shapes in the size range 10–45 nm. The resulting silver nanoparticles were predominantly square with uniform size range 50–90 nm. EDAX results confirmed the presence of triangular nanoparticles in the adsorption peak of 2.30 keV. Further FTIR analysis was also done to identify the functional groups in silver and gold nanoparticles. The characterized nanoparticles of M. edule have potential for various medical and industrial applications. Saponin presence in aqueous extract of M. edule is responsible for the mass production of silver and gold nanoparticles. PMID:21753878

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

    Directory of Open Access Journals (Sweden)

    Ačanski Marijana M.

    2007-01-01

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

  17. Interaction of silver nanoparticles with Tacaribe virus

    Directory of Open Access Journals (Sweden)

    Speshock Janice L

    2010-08-01

    Full Text Available Abstract Background Silver nanoparticles possess many unique properties that make them attractive for use in biological applications. Recently they received attention when it was shown that 10 nm silver nanoparticles were bactericidal, which is promising in light of the growing number of antibiotic resistant bacteria. An area that has been largely unexplored is the interaction of nanomaterials with viruses and the possible use of silver nanoparticles as an antiviral agent. Results This research focuses on evaluating the interaction of silver nanoparticles with a New World arenavirus, Tacaribe virus, to determine if they influence viral replication. Surprisingly exposing the virus to silver nanoparticles prior to infection actually facilitated virus uptake into the host cells, but the silver-treated virus had a significant reduction in viral RNA production and progeny virus release, which indicates that silver nanoparticles are capable of inhibiting arenavirus infection in vitro. The inhibition of viral replication must occur during early replication since although pre-infection treatment with silver nanoparticles is very effective, the post-infection addition of silver nanoparticles is only effective if administered within the first 2-4 hours of virus replication. Conclusions Silver nanoparticles are capable of inhibiting a prototype arenavirus at non-toxic concentrations and effectively inhibit arenavirus replication when administered prior to viral infection or early after initial virus exposure. This suggests that the mode of action of viral neutralization by silver nanoparticles occurs during the early phases of viral replication.

  18. Silver based batteries for high power applications

    Science.gov (United States)

    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.

  19. Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bharti, Amardeep, E-mail: abharti@pu.ac.in; Goyal, Navdeep [Department of Physics, Panjab University, Chandigarh, INDIA-160014 (India); Singh, Suman; Singla, M. L. [Agrionics, Central Scientific Instruments Organization, CSIR, Chandigarh, INDIA-160030 (India)

    2015-08-28

    Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

  20. Magneto optical properties of silver doped magnetic nanocomposite material

    Directory of Open Access Journals (Sweden)

    N. Abirami

    2017-11-01

    Full Text Available Magnetic composite materials challenge traditional materials in broad applications such as transformer, sensors and electrical motors. In this work by studying the permittivity and permeability spectra of silver doped magnetic nanocomposite system, the variation of the effective refractive index with frequency is investigated for different filling factor. It is found that the value of resonance frequency decrease with filling factor. The polariton dispersion of the system is also studied. This study of the nanocomposite system can be exploited in designing modern optical devices.PACS: 75.50-y, 71.36.+c, 78.67.Sc, 78.20.Ci. Keywords: Permittivity, Permeability, Nanocomposite system, Polariton

  1. Piper nigrum leaf and stem assisted green synthesis of silver nanoparticles and evaluation of its antibacterial activity against agricultural plant pathogens.

    Science.gov (United States)

    Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Pandian, Kannaiyan; Annadurai, Gurusamy

    2014-01-01

    Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). The observation of the peak at 460 nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7-50 nm and 9-30 nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology.

  2. Green synthesis and characterization of monodispersed silver nanoparticles using root bark aqueous extract of Annona muricata Linn and their antimicrobial activity

    Science.gov (United States)

    Ezealisiji, K. M.; Noundou, X. S.; Ukwueze, S. E.

    2017-11-01

    In recent time, various phytosynthetic methods have been employed for the fabrication of silver nanoparticles; these unique metal nanoparticles are used in several applications which include pharmaceuticals and material engineering. The current research reports a rapid and simple synthetic partway for silver nanoparticles (AgNPs) using root bark aqueous extract of Annona muricata and the evaluation of its antimicrobial efficacy against pathogenic microorganisms. The root bark extract was treated with aqueous silver nitrate solution. Silver ions were reduced to silver atoms which on aggregation gave Silver nanoparticles; the biosynthesized AgNPs were characteristically spherical, discreet and stabilized by phytochemical entities and were characterized using ultraviolet visible spectroscopy, transmission electron microscope (TEM) and photon correlation microscopy. The aqueous plant extract-AgNPs suspension was subjected to Fourier transform infrared spectroscopy. TEM result for the average particle size is 22 ± 2 nm. The polydispersity index and zeta-potential were found to be 0.44 ± 0.02 and - 27.90 ± 0.01 mV, respectively (Zeta-Sizer). The antimicrobial evaluation result showed that the synthesized silver nanoparticles at different concentration were very active against the Gram-positive bacteria ( B. subtilis, S. aureous) and Gram-negative bacteria ( K. Pneumonia, E. Coli and Pseudomonas aeruginosa), P. aeruginosa being most susceptible to the anti microbial effect of the silver nanoparticles. Stable silver nanoparticles with antimicrobial activity were obtained through biosynthesis.

  3. Piper nigrum Leaf and Stem Assisted Green Synthesis of Silver Nanoparticles and Evaluation of Its Antibacterial Activity Against Agricultural Plant Pathogens

    Science.gov (United States)

    Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Pandian, Kannaiyan; Annadurai, Gurusamy

    2014-01-01

    Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). The observation of the peak at 460 nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7–50 nm and 9–30 nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology. PMID:24558336

  4. Piper nigrum Leaf and Stem Assisted Green Synthesis of Silver Nanoparticles and Evaluation of Its Antibacterial Activity Against Agricultural Plant Pathogens

    Directory of Open Access Journals (Sweden)

    Kanniah Paulkumar

    2014-01-01

    Full Text Available Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM, energy dispersive X-ray analysis (EDAX, and Fourier Transform Infrared Spectroscopy (FTIR. The observation of the peak at 460 nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7–50 nm and 9–30 nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology.

  5. Conducting polymer-silver composites

    Czech Academy of Sciences Publication Activity Database

    Stejskal, Jaroslav

    2013-01-01

    Roč. 67, č. 8 (2013), s. 814-848 ISSN 0366-6352 R&D Projects: GA TA ČR TE01020022 Institutional support: RVO:61389013 Keywords : polyaniline * polypyrrole * silver Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.193, year: 2013

  6. Sustainable transformation

    DEFF Research Database (Denmark)

    Andersen, Nicolai Bo

    This paper is about sustainable transformation with a particular focus on listed buildings. It is based on the notion that sustainability is not just a question of energy conditions, but also about the building being robust. Robust architecture means that the building can be maintained and rebuilt......, that it can be adapted to changing functional needs, and that it has an architectural and cultural value. A specific proposal for a transformation that enhances the architectural qualities and building heritage values of an existing building forms the empirical material, which is discussed using different...... theoretical lenses. It is proposed that three parameters concerning the ꞌtransformabilityꞌ of the building can contribute to a more nuanced understanding of sustainable transformation: technical aspects, programmatic requirements and narrative value. It is proposed that the concept of ꞌsustainable...

  7. Transformational leadership.

    Science.gov (United States)

    Taccetta-Chapnick, M

    1996-01-01

    Rapid changes in the health care system have caused competition among institutions, as organizations are restructured to increase client satisfaction, resulting in the need for a new style of leadership. The transformational leader communicates the mission and vision of the organization and empowers others to effectively resolve conflicts that may arise with change. The health care team that can cope with changes and conflicts views restructuring as a positive transaction and approaches client satisfaction with energy and motivation. Institutions with transformational leadership are the ones that will survive the transition.

  8. Sustainable transformation

    DEFF Research Database (Denmark)

    Andersen, Nicolai Bo

    This paper is about sustainable transformation with a particular focus on listed buildings. It is based on the notion that sustainability is not just a question of energy conditions, but also about the building being robust. Robust architecture means that the building can be maintained and rebuilt...... theoretical lenses. It is proposed that three parameters concerning the ꞌtransformabilityꞌ of the building can contribute to a more nuanced understanding of sustainable transformation: technical aspects, programmatic requirements and narrative value. It is proposed that the concept of ꞌsustainable...

  9. Microbial Biosynthesis of Silver Nanoparticles in Different Culture Media.

    Science.gov (United States)

    Luo, Ke; Jung, Samuel; Park, Kyu-Hwan; Kim, Young-Rok

    2018-01-31

    Microbial biosynthesis of metal nanoparticles has been extensively studied for the applications in biomedical sciences and engineering. However, the mechanism for their synthesis through microorganism is not completely understood. In this study, several culture media were investigated for their roles in the microbial biosynthesis of silver nanoparticles (AgNPs). The size and morphology of the synthesized AgNPs were analyzed by UV-vis spectroscopy, Fourier-transform-infrared (FT-IR), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The results demonstrated that nutrient broth (NB) and Mueller-Hinton broth (MHB) among tested media effectively reduced silver ions to form AgNPs with different particle size and shape. Although the involved microorganism enhanced the reduction of silver ions, the size and shape of the particles were shown to mainly depend on the culture media. Our findings suggest that the growth media of bacterial culture play an important role in the synthesis of metallic nanoparticles with regard to their size and shape. We believe our findings would provide useful information for further exploration of microbial biosynthesis of AgNPs and their biomedical applications.

  10. Plasmon enhanced silver quantum cluster fluorescence for biochemical applications

    DEFF Research Database (Denmark)

    Bernard, S.; Kutter, Jörg P.; Mogensen, K. B.

    2014-01-01

    Fluorescence microscopy of individual silver quantum clusters on the surface of silver nanoparticles reveals strong photoactivated emission under blue light excitation [1-4]. In this work, silver nanoparticles are produced by annealing silver thin films deposited on a glass substrate and silver...

  11. Plasmon enhanced silver quantum cluster fluorescence for biochemical applications

    DEFF Research Database (Denmark)

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

    2014-01-01

    Fluorescence microscopy of individual silver quantum clusters on the surface of silver nanoparticles reveals strong photoactivated emission under blue light excitation [1-4]. In this work, silver nanoparticles are produced by annealing silver thin films deposited on a glass substrate and silver q...

  12. PVDF nanofibers with silver nanoparticles and silver/titanium dioxide for antimicrobial applications;Eletrofiacao de nanofibras de PVDF com nanoparticulas de prata e de prata/dioxido de titanio para aplicacoes antimicrobiais

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Ligia M.M.; Olyveira, Gabriel M. de, E-mail: gmolyveira@yahoo.com.b, E-mail: ligialmmc@hotmail.co [Universidade Federal de Sao Carlos (PPGCEM/UFScar), SP (Brazil). Programa de Pos Graduacao em Ciencia e Engenharia de Materiais; Gregorio Filho, Rinaldo; Pessan, Luiz A., E-mail: pessan@ufscar.b, E-mail: gregorio@ufscar.b [Universidade Federal de Sao Carlos (UFScar), SP (Brazil)

    2009-07-01

    PVDF nanofibers with and without nanoparticles were produced by the method of electro spinning using dimethylformamide (DMF). Silver nitrate nanoparticles (0,5 and 2 wt %) and silver/titanium dioxide nanoparticles obtained by the reduction method (2 wt %) were synthesized and added to the PVDF solution to prepared nanofibers. The processes of electrospinning and film preparation using PVDF with the nanoparticles were compared. Silver/titanium dioxide nanoparticles were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDX and x-ray photoelectron spectroscopy (XPS) to show silver/titanium dioxide nanoparticles. Nanofibers mats were characterized with SEM to study the effects of the addition of the nanoparticles on the morphology behavior and spectroscopy by Fourier transform infrared (FTIR) to analyze the crystalline phase of PVDF films. (author)

  13. Electroless plating of silver on cenosphere particles and the investigation of its corrosion behavior in composite silicon rubber

    Science.gov (United States)

    Hu, Yong-jun; Zhang, Hai-yan; Cheng, Xiao-ling; Li, Feng; Chen, Tian-li

    2011-01-01

    In this paper, silver coating on the surface of cenosphere particles was prepared by electroless plating method. The adhesion, oxidation resistance and corrosion resistance properties of silver coating mixed in silicone rubber were investigated. The corrosion characteristic of silver coating was evaluated by anodic polarization curves of the silicone rubber composite in sulfuric acid solution. The results showed that the silver coating on the surface of cenosphere particles was smooth and uniform. The silver film was not oxidized and peeling off during preparation of composite silicone rubber. The adhesion between the cenosphere particle and silver film was good enough. The anodic polarization curves of the silicone rubber composite showed typical activation and passivation transformation. The values of corrosion potential, the initiating passive potential and maintaining passivity potential of composites filled with different contents of Ag-coated cenosphere particles were the same and related to the nature of silver coating. The passive current density of composite increased with increase of the amount of Ag-coated cenosphere particles and was inversely proportional to the resistance of silicone rubber composite. The better the conductivity of silicone rubber composite is, the higher corrosion rate will be.

  14. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2010-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  15. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2008-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  16. Identity transformation

    DEFF Research Database (Denmark)

    Neergaard, Helle; Robinson, Sarah; Jones, Sally

    This paper develops the concept of ‘pedagogical nudging’ and examines four interventions in an entrepreneurship classroom and the potential it has for student identity transformation. Pedagogical nudging is positioned as a tool, which in the hands of a reflective, professional, with an understand......This paper develops the concept of ‘pedagogical nudging’ and examines four interventions in an entrepreneurship classroom and the potential it has for student identity transformation. Pedagogical nudging is positioned as a tool, which in the hands of a reflective, professional......, as well as the resources they have when they come to the classroom. It also incorporates perspectives from (ii) transformational learning and explores the concept of (iii) nudging from a pedagogical viewpoint, proposing it as an important tool in entrepreneurship education. The study incorporates......) assists students in straddling the divide between identities, the emotions and tensions this elicits, and (iv) transform student understanding. We extend nudging theory into a new territory. Pedagogical nudging techniques may be able to unlock doors and bring our students beyond the unacknowledged...

  17. Micellized sequestered silver atoms and small silver clusters

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    Science.gov (United States)

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

  19. Synthesis of silver nanoparticles by using tea leaf extract from Camellia sinensis.

    Science.gov (United States)

    Loo, Yuet Ying; Chieng, Buong Woei; Nishibuchi, Mitsuaki; Radu, Son

    2012-01-01

    The development of the biological synthesis of nanoparticles using microorganisms or plant extracts plays an important role in the field of nanotechnology as it is environmentally friendly and does not involve any harmful chemicals. In this study, the synthesis of silver nanoparticles using the leaves extract of Chinese tea from Camellia sinensis is reported. The synthesized nanoparticles were characterized using UV-vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The XRD analysis shows that the synthesized silver nanoparticles are of face-centered cubic structure. Well-dispersed silver nanoparticles with an approximate size of 4 nm were observed in the TEM image. The application of the green synthesized nanoparticles can be used in many fields such as cosmetics, foods, and medicine.

  20. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

    Science.gov (United States)

    Bindhu, M. R.; Umadevi, M.

    2013-01-01

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  1. Photocatalytic activity of biogenic silver nanoparticles synthesized using yeast ( Saccharomyces cerevisiae) extract

    Science.gov (United States)

    Roy, Kaushik; Sarkar, C. K.; Ghosh, C. K.

    2015-11-01

    Synthesis of metallic and semiconductor nanoparticles through physical and chemical route is quiet common but biological synthesis procedures are gaining momentum due to their simplicity, cost-effectivity and eco-friendliness. Here, we report green synthesis of silver nanoparticles from aqueous solution of silver salts using yeast ( Saccharomyces cerevisiae) extract. The nanoparticles formation was gradually investigated by UV-Vis spectrometer. X-ray diffraction analysis was done to identify different phases of biosynthesized Ag nanoparticles. Transmission electron microscopy was performed to study the particle size and morphology of silver nanoparticles. Fourier transform infrared spectroscopy of the nanoparticles was performed to study the role of biomolecules capped on the surface of Ag nanoparticles during interaction. Photocatalytic activity of these biosynthesized nanoparticles was studied using an organic dye, methylene blue under solar irradiation and these nanoparticles showed efficacy in degrading the dye within a few hours of exposure.

  2. Structural distortions in 5-10 nm silver nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Koski, Kristie J.; Kamp, Noelle M.; Kunz, Martin; Knight, Jason K.; Alivisatos, A.P.; Smith, R.K.

    2008-10-13

    We present experimental evidence that silver nanoparticles in the size range of 5-10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. We have used x-ray diffraction with a synchrotron light source to investigate pressure-dependent and size-dependent trends in the crystal structure of silver nanoparticles in a hydrostatic medium compressed in a diamond-anvil cell. Results suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. We propose a mechanism for this transition that considers the bond-length distribution in idealized multiply twinned icosahedral particles. To further support this hypothesis, we also show that similar measurements of single-crystal platinum nanoparticles reveal no such distortions.

  3. Synthesis of silver nanoparticles using flavonoids: hesperidin, naringin and diosmin, and their antibacterial effects and cytotoxicity

    Science.gov (United States)

    Sahu, Nidhi; Soni, Deepika; Chandrashekhar, B.; Satpute, D. B.; Saravanadevi, Sivanesan; Sarangi, B. K.; Pandey, R. A.

    2016-07-01

    Three different flavonoids -hesperidin, naringin and diosmin (constituents of citrus plants) were used for the synthesis of silver nanoparticles (AgNPs). Aqueous solutions of pure flavonoids (0.2 mg mL-1) mixed with 1 mM AgNO3 solution were exposed to bright sunlight to prepare the nanoparticles. Characterization of the synthesized nanoparticles by UV-Visible spectrophotometer, X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy revealed that the synthesized silver nanoparticles were 10-80 nm in size and polydispersed in nature. Bactericidal effect against common pathogens and cytotoxicity of the synthesized silver nanoparticles was investigated on human promyelocytic leukemic (HL-60) cells. It is concluded that AgNPs synthesized using Naringin as reducing agent showed higher stability and better antibacterial and cytotoxic activities.

  4. Synthesis and Characterization of Polyethylene Glycol Mediated Silver Nanoparticles by the Green Method

    Directory of Open Access Journals (Sweden)

    Yadollah Abdollahi

    2012-05-01

    Full Text Available The roles of green chemistry in nanotechnology and nanoscience fields are very significant in the synthesis of diverse nanomaterials. Herein, we report a green chemistry method for synthesized colloidal silver nanoparticles (Ag NPs in polymeric media. The colloidal Ag NPs were synthesized in an aqueous solution using silver nitrate, polyethylene glycol (PEG, and β-d-glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag NPs were studied at different reaction times. The ultraviolet-visible spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM and their size distributions. The Ag NPs were characterized by utilizing X-ray diffraction (XRD, zeta potential measurements and Fourier transform infrared (FT-IR. The use of green chemistry reagents, such as glucose, provides green and economic features to this work.

  5. Synthesis and Characterization of Polyethylene Glycol Mediated Silver Nanoparticles by the Green Method

    Science.gov (United States)

    Shameli, Kamyar; Ahmad, Mansor Bin; Jazayeri, Seyed Davoud; Sedaghat, Sajjad; Shabanzadeh, Parvaneh; Jahangirian, Hossein; Mahdavi, Mahnaz; Abdollahi, Yadollah

    2012-01-01

    The roles of green chemistry in nanotechnology and nanoscience fields are very significant in the synthesis of diverse nanomaterials. Herein, we report a green chemistry method for synthesized colloidal silver nanoparticles (Ag NPs) in polymeric media. The colloidal Ag NPs were synthesized in an aqueous solution using silver nitrate, polyethylene glycol (PEG), and β-D-glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag NPs were studied at different reaction times. The ultraviolet-visible spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The Ag NPs were characterized by utilizing X-ray diffraction (XRD), zeta potential measurements and Fourier transform infrared (FT-IR). The use of green chemistry reagents, such as glucose, provides green and economic features to this work. PMID:22837654

  6. Synthesis of silver nanoparticles by using tea leaf extract from Camellia Sinensis

    Science.gov (United States)

    Loo, Yuet Ying; Chieng, Buong Woei; Nishibuchi, Mitsuaki; Radu, Son

    2012-01-01

    The development of the biological synthesis of nanoparticles using microorganisms or plant extracts plays an important role in the field of nanotechnology as it is environmentally friendly and does not involve any harmful chemicals. In this study, the synthesis of silver nanoparticles using the leaves extract of Chinese tea from Camellia sinensis is reported. The synthesized nanoparticles were characterized using UV-vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The XRD analysis shows that the synthesized silver nanoparticles are of face-centered cubic structure. Well-dispersed silver nanoparticles with an approximate size of 4 nm were observed in the TEM image. The application of the green synthesized nanoparticles can be used in many fields such as cosmetics, foods, and medicine. PMID:22904632

  7. Carboxymethylguargum-silver nanocomposite: green synthesis, characterization and an optical sensor for ammonia detection

    International Nuclear Information System (INIS)

    Gupta, Anek Pal; Verma, Devendra Kumar

    2014-01-01

    This work describes the preparation of new carboxymethyl guar gum-silver nanocomposite (CMGG/Ag NC) by green synthesis method. For this carboxymethyl guar gum was used as a reducing agent as well as stabilizer. The silver nanoparticles obtained were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV–vis spectroscopy, Fourier transform infrared (FTIR) and energy dispersive x-ray analysis (EDX). The average size of the silver nanoparticles was found of ∼6 nm. Thus, the obtained CMGG/AgNPs NC was examined for optical sensing property for detection of ammonia in aqueous medium. The response time and the detection limit of ammonia in aqueous solution were detected at room temperature. It was concluded that in the future, at this room temperature optical ammonia sensor may be used for medical diagnosis and clinically for detecting low ammonia level (up to 1 ppm) in biological samples for various biomedical applications. (paper)

  8. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires

    Directory of Open Access Journals (Sweden)

    Eun Kyung Sohn

    2015-01-01

    Full Text Available 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.

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

    OpenAIRE

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

    2012-01-01

    Silver toxicity is a problem that microorganisms face in medical and environmental settings. Through exposure to silver compounds, some bacteria have adapted to growth in high concentrations of silver ions. Such adapted microbes may be dangerous as pathogens but, alternatively, could be potentially useful in nanomaterial-manufacturing applications. While naturally adapted isolates typically utilize efflux pumps to achieve metal resistance, we have engineered a silver-tolerant Escherichia coli...

  10. Preparation of silver nanoparticles at low temperature

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-13

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

  11. Discrete transforms

    CERN Document Server

    Firth, Jean M

    1992-01-01

    The analysis of signals and systems using transform methods is a very important aspect of the examination of processes and problems in an increasingly wide range of applications. Whereas the initial impetus in the development of methods appropriate for handling discrete sets of data occurred mainly in an electrical engineering context (for example in the design of digital filters), the same techniques are in use in such disciplines as cardiology, optics, speech analysis and management, as well as in other branches of science and engineering. This text is aimed at a readership whose mathematical background includes some acquaintance with complex numbers, linear differen­ tial equations, matrix algebra, and series. Specifically, a familiarity with Fourier series (in trigonometric and exponential forms) is assumed, and an exposure to the concept of a continuous integral transform is desirable. Such a background can be expected, for example, on completion of the first year of a science or engineering degree cour...

  12. Transformative Agency

    DEFF Research Database (Denmark)

    Majgaard, Klaus

    The purpose of this paper is to enhance the conceptual understanding of the mediatory relationship between paradoxes on an organizational and an individual level. It presents a concept of agency that comprises and mediates between a structural and individual pole. The constitution of this agency...... is achieved through narrative activity that oscillates between the poles and transforms paradoxes through the configuration of plots and metaphors. Empirical cases are introduced in order to illustrate the implications of this understanding....

  13. XML Transformations

    Directory of Open Access Journals (Sweden)

    Felician ALECU

    2012-04-01

    Full Text Available XSLT style sheets are designed to transform the XML documents into something else. The two most popular parsers of the moment are the Document Object Model (DOM and the Simple API for XML (SAX. DOM is an official recommendation of the W3C (available at http://www.w3.org/TR/REC-DOM-Level-1, while SAX is a de facto standard. A good parser should be fast, space efficient, rich in functionality and easy to use.

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

    Science.gov (United States)

    Gatemala, Harnchana; Ekgasit, Sanong; Wongravee, Kanet

    2017-07-01

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

  15. Synthesis and optical properties of silver nanoparticles

    Science.gov (United States)

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

    2015-07-01

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

  16. Biosynthesis of Silver Nanoparticles and Its Applications

    OpenAIRE

    M. Jannathul Firdhouse; P. Lalitha

    2015-01-01

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

  17. Risk assessment of silver nanoparticles

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (paper)

  18. Anglesite and silver recovery from jarosite residues through roasting and sulfidization-flotation in zinc hydrometallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Haisheng; Sun, Wei, E-mail: hanhaishengjingji@126.com; Hu, Yuehua; Jia, Baoliang; Tang, Honghu

    2014-08-15

    Highlights: • Jarosite precipitate hindered the recovery of valuable minerals. • Under 600–700 °C, jarosite decomposed and released the encapsulated valuable minerals. • The bared valuable minerals were easily collected by flotation process. • The new process was promising for dealing with jarosite residues. - Abstract: Hazardous jarosite residues contain abundant valuable minerals that are difficult to be recovered by traditional flotation process. This study presents a new route, roasting combined with sulfidization-flotation, for the recovery of anglesite and silver from jarosite residues of zinc hydrometallurgy. Surface appearance and elemental distribution of jarosite residues was examined by scanning electron microscopy and energy dispersive X-ray spectrometry analysis, respectively. Decomposition and transformation mechanisms of jarosite residues were illustrated by differential thermal analysis. Results showed that after roasting combined with flotation, the grade and recovery of lead were 43.89% and 66.86%, respectively, and those of silver were 1.3 kg/t and 81.60%, respectively. At 600–700 °C, jarosite was decomposed to release encapsulated valuable minerals such as anglesite (PbSO{sub 4}) and silver mineral; silver jarosite decomposed into silver sulfate (Ag{sub 2}SO{sub 4}); and zinc ferrite (ZnO·Fe{sub 2}O{sub 3}) decomposed into zinc sulfate (ZnSO{sub 4}) and hematite (Fe{sub 2}O{sub 3}). Bared anglesite and silver minerals were modified by sodium sulfide and easily collected by flotation collectors. This study demonstrates that the combination of roasting and sulfidization-flotation provides a promising process for the recovery of zinc, lead, and silver from jarosite residues of zinc hydrometallurgy.

  19. Green biosynthesis of silver nanoparticles using leaves extract of Artemisia vulgaris and their potential biomedical applications.

    Science.gov (United States)

    Rasheed, Tahir; Bilal, Muhammad; Iqbal, Hafiz M N; Li, Chuanlong

    2017-10-01

    Biosynthesis of nanoparticles from plant extracts is receiving enormous interest due to their abundant availability and a broad spectrum of bioactive reducing metabolites. In this study, the reducing potential of Artemisia vulgaris leaves extract (AVLE) was investigated for synthesizing silver nanoparticles without the addition of any external reducing or capping agent. The appearance of blackish brown color evidenced the complete synthesis of nanoparticles. The synthesized silver nanoparticles were characterized by UV-vis spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), atomic force microscopy (AFM) and Fourier transforms infrared spectroscopy (FT-IR) analysis. UV-vis absorption profile of the bio-reduced sample elucidated the main peak around 420nm, which correspond to the surface plasmon resonance of silver nanoparticles. SEM and AFM analyses confirmed the morphology of the synthesized nanoparticles. Similarly, particles with a distinctive peak of silver were examined with EDX. The average diameter of silver nanoparticles was about 25nm from Transmission Electron Microscopy (TEM). FTIR spectroscopy scrutinized the involvement of various functional groups during nanoparticle synthesis. The green synthesized nanoparticles presented effective antibacterial activity against pathogenic bacteria than AVLE alone. In-vitro antioxidant assays revealed that silver nanoparticles (AV-AgNPs) exhibited promising antioxidant properties. The nanoparticles also displayed a potent cytotoxic effect against HeLa and MCF-7 cell lines. In conclusion, the results supported the advantages of employing a bio-green approach for developing silver nanoparticles with antimicrobial, antioxidant, and antiproliferative activities in a simple and cost- competitive manner. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Enhancement of antibacterial properties of silver nanoparticles-ceftriaxone conjugate through Mukia maderaspatana leaf extract mediated synthesis.

    Science.gov (United States)

    Harshiny, Muthukumar; Matheswaran, Manickam; Arthanareeswaran, Gangasalam; Kumaran, Shanmugam; Rajasree, Shanmuganathan

    2015-11-01

    Green synthesis of nanoparticles with low range of toxicity and conjugation to antibiotics has become an attractive area of research for several biomedical applications. Nanoconjugates exhibited notable increase in biological activity compared to free antibiotic molecules. With this perception, we report the biosynthesis of silver nanoparticles using aqueous extract of leaves of Mukia maderaspatana and subsequent conjugation of the silver nanoparticles to antibiotic ceftriaxone. The leaves of this plant are known to be a rich source of phenolic compounds with high antioxidant activity that are used as reducing agents. The size, morphology, crystallinity, composition of the synthesized silver nanoparticles and conjugation of ceftriaxone to silver nanoparticles were studied using analytical techniques. The activity of the conjugates against Bacillus subtilis (MTCC 1790), Klebsiella pneumoniae (MTCC 3384), Staphylococcus aureus (ATCC 25923), and Salmonella typhi (MTCC 3224) was compared to ceftriaxone and unconjugated nanoparticles using disc diffusion method. The effect of silver nanoparticles on the reduction of biofilms of Pseudomonas fluorescens (MTCC 6732) was determined by micro plate assay method. The antioxidant activities of extract, silver nitrate, silver nanoparticles, ceftriaxone and conjugates of nanoparticles were evaluated by radical scavenging 1, 1- diphenyl-2-picrylhydrazyl test. Ultraviolet visible spectroscopy and Fourier transform infrared spectroscopy confirmed the formation of metallic silver nanoparticles and conjugation to ceftriaxone. Atomic force microscopy, transmission electron microscopy and particle size analysis showed that the formed particles were of spherical morphology with appreciable nanosize and the conjugation was confirmed by slight increase in surface roughness. The results thus showed that the conjugation of ceftriaxone with silver nanoparticles has better antioxidant and antimicrobial effects than ceftriaxone and unconjugated

  1. Preparation of counterion stabilized concentrated silver sols.

    Science.gov (United States)

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

    2011-07-01

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

  2. Cementation of silver ions on metallic copper

    International Nuclear Information System (INIS)

    Jaskula, M.

    2009-01-01

    The silver cementation on metallic copper was investigated in the presence or absence of oxygen. The influence of sulphuric acid and copper sulphate concentration on the silver cement morphology was studied in details, and results were linked with the previously determined kinetics data of the process. The morpgology of silver depopsit was found to be independent of the prosence of oxygen in the system in as well as the sulphuric acide concentration. Contrary, the concentration of copper sulphate strongly influenced the morphology of silver deposite. Two-stage mechanism of cementation was proposed. (authors).

  3. Tailoring silver nanoparticle construction using dendrimer templated silica networks

    International Nuclear Information System (INIS)

    Liu Xiaojun; Kakkar, Ashok

    2008-01-01

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

  4. One-step synthesis of silver nanoparticles in an aqueous solution and their antibacterial activities

    Science.gov (United States)

    Zhang, Guangyu; Zhang, Feng; Morikawa, Hideaki; Chen, Yueyue

    2014-03-01

    A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented in this research. In the synthesis, an amino-terminated hyperbranched polymer (HBP-NH2) was applied as a stabilizer and a reductant. The syntheses, performed at various initial AgNO3 concentrations (0.28-0.56 g/l) in a 2 g/l HBP-NH2 aqueous solution, produced silver colloid nanoparticles having average sizes from 3 to 30 nm with narrow size distributions. The formation of silver colloid nanoparticles was characterized by Fourier Transform Infrared Spectrophotometry (FTIR), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), UV/Visible Absorption Spectrophotometry, and X-ray Diffraction (XRD) measurements. The results indicated that both particle size and the UV absorption are strongly dependent on the initial AgNO3 concentrations. The silver colloid nanoparticles, prepared with a 0.35 g/l AgNO3 aqueous solution in the presences of 2 g/l HBP-NH2, showed good antibacterial activities against Gram-negative bacteria ( Escherichia coli) and Gram-positive bacteria ( Staphylococcus aureus). A very low concentration of nano-silver (as low as 3.0 ug/ml Ag) also gave excellent antibacterial performance.

  5. Highly water-dispersible silver sulfadiazine decorated with polyvinyl pyrrolidone and its antibacterial activities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ping; Wu, Longlong [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Li, Binjie, E-mail: lbj821@163.com [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Medical School of Henan University, Kaifeng 475004 (China); Zhao, Yanbao [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Qu, Peng [Department of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China)

    2016-03-01

    Highly water-dispersible silver sulfadiazine (SSD) was prepared by liquid phase method with polyvinyl pyrrolidone (PVP) as a surface modification agent. The structure and morphology of the PVP-modified silver sulfadiazine (P-SSD) were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared (FT-IR) spectrometry. The produced particles are ginkgo leaf-like architecture with the sizes of micron-nanometer. Due to hydrophilic PVP decorated on the surface, the P-SSD has excellent dispersion in water over a period of 24 h, which is obviously stable by comparison to that of the commercial silver sulfadiazine (C-SSD). In addition, the P-SSD exhibits good antibacterial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). - Highlights: • Polyvinyl pyrrolidone decorated silver sulfadiazine was synthesized via a one-pot protocol. • The produced particles present ginkgo leaf-like architectures with sizes of micro-nanometer. • The resulted silver sulfadiazine has highly dispersible in water over a period of 24 h. • The obtained sliver sulfadiazine exhibits excellent antibacterial activities against E. coli, P. aeruginosa and S. aureus.

  6. Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

    Science.gov (United States)

    Hanim, Siti Aishah Mohd; Malek, Nik Ahmad Nizam Nik; Ibrahim, Zaharah

    2016-01-01

    Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver ions and APTES used during modification.

  7. Removal of pathogenic bacteria from wastewater using silver nanoparticles synthesized by two fungal species

    Directory of Open Access Journals (Sweden)

    Mohammed Taha Moustafa

    2017-10-01

    Full Text Available Nanotechnology are fast advancing and currently became more effective than the conventional technologies used in water treatment that offers safe opportunities for using unconventional water supply sources. Fungi are more versatile in growth and metal tolerance in contrast to bacterial population. This work aims to demonstrate the extracellular synthesis of silver nanoparticle by using two filamentous fungi Penciillium Citreonigum Dierck and Scopulaniopsos brumptii Salvanet-Duval isolated from Lake Burullus, examine the biosynthesized nano-silver particles by UV–vis spectroscopy, transmission electron microscopy (TEM. The functional group of protein molecules surrounding AgNPs was identified using Fourier transform infrared (FTIR analysis. Check the antibacterial activity of biosynthesized silver nanoparticles at two concentrations (550.7 and 676.9 mg/l and interact it with bacteria for different durations (15, 60 and 120 min. Polyurethane foam was used as silver carrier and nano-silver solution for the removal of pathogenic bacteria in polluted water. The synthesized AgNPs showed an excellent antibacterial property on gram positive and gram negative bacterial strains.

  8. Synthesis of gold and silver nanoparticles usingMukia maderaspatnaplant extract and its anticancer activity.

    Science.gov (United States)

    Devi, Guruviah Karthiga; Sathishkumar, Kannaiyan

    2017-03-01

    The present investigation reveals the in vitro cytotoxic effect of the biosynthesised metal nanoparticles on the MCF 7 breast cancer cell lines. The gold and silver nanoparticles were synthesised through an environmentally admissible route using the Mukia Maderaspatna plant extract. Initially, the biomolecules present in the plant extract were analysed using phytochemical analysis. Further, these biomolecules reduce the metal ion solution resulting from the formation of metal nanoparticles. The reaction parameters were optimised to control the size of nanoparticles which were confirmed by UV visible spectroscopy. Various instrumental techniques such as Fourier transform-infrared spectroscopy, high resolution transmission electron microscopy, energy dispersive X-ray and scanning electron microscopy were employed to characterise the synthesised gold and silver nanoparticles. The synthesised gold and silver nanoparticles were found to be 20-50 nm and were of different shapes including spherical, triangle and hexagonal. MTT and dual staining assays were carried out with different concentrations (1, 10, 25, 50 and 100 µg/ml) of gold and silver nanoparticles. The results show that the nanoparticles exhibited significant cytotoxic effects with IC 50 value of 44.8 µg/g for gold nanoparticles and 51.3 µg/g for silver nanoparticles. The observations in this study show that this can be developed as a promising nanomaterial in pharmaceutical and healthcare sector.

  9. Photochemical formation of silver and gold nanostructures at the air water interface and their electrocatalytic properties

    Science.gov (United States)

    Chen, Hongjun; Jia, Jianbo; Dong, Shaojun

    2007-06-01

    In this paper, we report a simple method of fabricating silver and gold nanostructures at the air-water interface, which can be spontaneously assembled through the reduction of AgNO3 and HAuCl4 with ultraviolet (UV) irradiation in the presence of polyacrylic acid (PAA), respectively. It was found that the building blocks in the silver nanostructure are mainly interwoven silver nanofilaments, while those of the gold nanostructure are mainly different sizes of gold nanoparticles and some truncated gold nanoplates, and even coalescence into networks. At the air-water interface, these silver and gold nanostructures can be easily transferred onto the surface of indium tin oxide (ITO) slides and used for electrochemical measurements. After a replacement reaction with H2PdCl4, the silver nanostructure is transformed into a Ag-Pd bimetallic nanostructure, with good electrocatalytic activity for O2 reduction. The gold nanostructure can also show high electrocatalytic activity to the oxidation of nitric oxide (NO) with a detection limit of about 10 µM NaNO2 at S/N = 3.

  10. Electrospun Polycaprolactone Membrane Incorporated with Biosynthesized Silver Nanoparticles as Effective Wound Dressing Material.

    Science.gov (United States)

    Thomas, Roshmi; Soumya, K R; Mathew, Jyothis; Radhakrishnan, E K

    2015-08-01

    Biosynthesized silver nanoparticles (AgNPs) incorporated polycaprolactone (PCL) nanomembrane was prepared by electrospinning as a cost-effective nanocomposite for application as an antimicrobial agent against wound infection. The nanocomposite membrane was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis and Scanning Electron microscopy (SEM). The hydrophilicity analysis of electrospun membranes as evaluated by water contact angle measurement showed the change of hydrophobicity of PCL to hydrophilic upon incorporation of silver nanoparticles. Better mechanical properties were also observed for PCL membrane due to the incorporation of silver nanoparticles and are highly supportive to explore its biomedical applications. Further antibacterial analysis of silver nanoparticle-incorporated PCL membrane against common wound pathogens coagulase-negative Staphylococcus epidermidis and Staphylococcus haemolyticus showed remarkable activity. As biosynthesized AgNPs are least explored for clinical applications, the current study is a promising cost-effective method to explore the development of silver nanoparticle-based electrospun nanocomposite to resist wound-associated infection.

  11. Green synthesis of silver nanoparticles using Terminalia chebula extract at room temperature and their antimicrobial studies

    Science.gov (United States)

    Mohan Kumar, Kesarla; Sinha, Madhulika; Mandal, Badal Kumar; Ghosh, Asit Ranjan; Siva Kumar, Koppala; Sreedhara Reddy, Pamanji

    2012-06-01

    A green rapid biogenic synthesis of silver nanoparticles (Ag NPs) using Terminalia chebula (T. chebula) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 452 nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by T. chebula extract was completed within 20 min which was evidenced potentiometrically. Synthesised nanoparticles were characterised using UV-vis spectroscopy, Fourier transformed infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The hydrolysable tannins such as di/tri-galloyl-glucose present in the extract were hydrolyzed to gallic acid and glucose that served as reductant while oxidised polyphenols acted as stabilizers. In addition, it showed good antimicrobial activity towards both Gram-positive bacteria (S. aureus ATCC 25923) and Gram-negative bacteria (E. coli ATCC 25922). Industrially it may be a smart option for the preparation of silver nanoparticles.

  12. Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum β-lactamase producing (ESBL) strains of Enterobacteriaceae

    International Nuclear Information System (INIS)

    Banu, Afreen; Rathod, Vandana; Ranganath, E.

    2011-01-01

    Highlights: → Silver nanoparticle production by using Rhizopus stolonifer. → Antibacterial activity of silver nanoparticles against extended spectrum β-lactamase producing (ESBL) strains of Enterobacteriaceae. → Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. → Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silver nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.

  13. Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

    Energy Technology Data Exchange (ETDEWEB)

    Banu, Afreen [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India); Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India); Ranganath, E. [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India)

    2011-09-15

    Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silver nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.

  14. Holonic transformation

    Science.gov (United States)

    Sugiyama, Shigeki

    2001-11-01

    Here introduces a new idea of Holonic Transformation Method (HTM) which is able to represent the huge and complexed systems clearly and precisely as they are expected and the time whenever they are wanted, and which is also able to control them intelligently and flexibly. This idea is originated from Arthur Koestler, the late Hungarian novelist, science writer, and philosopher, who defined the idea in terms of living systems. Here, by expanding this idea philosophically and mathematically in order to use for management in the field of engineering, it has made possible to treat the huge and complexed system, which is not possible in the conventional methods.

  15. Transforming Society

    DEFF Research Database (Denmark)

    Enemark, Stig; Dahl Højgaard, Pia

    2017-01-01

    This paper provides an understanding of the cadastral evolution in Denmark with a focus on establishing the cadastre as an outcome of the enclosure movement in the late 1700s. The purpose of the cadastre was collection of tax based on the yielding capacity of the soil. The Danish cadastre, this way......, was a result of transforming society from a feudal system to a capitalistic and market based economy. This story is interesting in itself - but it also provides a key to understanding the cadastral system of today. The system has evolved over time and now serves a whole range of functions in society. The paper...

  16. Uptake and elimination kinetics of silver nanoparticles and silver nitrate by Raphidocelis subcapitata: The influence of silver behaviour in solution

    NARCIS (Netherlands)

    Ribeiro, Fabianne; Gallego-Urrea, Julián Alberto; Goodhead, Rhys M.; van Gestel, C.A.M.; Moeger, Julian; Soares, Amadeu M.V.M.; Loureiro, Susana

    2015-01-01

    Raphidocelis subcapitata is a freshwater algae species that constitutes the basis of many aquatic trophic chains. In this study, R. subcapitata was used as a model species to investigate the kinetics of uptake and elimination of silver nanoparticles (AgNP) in comparison to silver nitrate

  17. Synthesis and antimicrobial effects of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    S kheybari

    2010-09-01

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

  18. Serum and urinary silver levels in thermal injury patients.

    Science.gov (United States)

    Boosalis, M G; McCall, J T; Ahrenholz, D H; Solem, L D; McClain, C J

    1987-01-01

    Although silver sulfadiazine has been used extensively as an effective topical antimicrobial agent in thermal injury patients, little is known about the cutaneous absorption of the silver moiety in these patients. Therefore, we longitudinally evaluated both serum silver concentration and 24-hour urinary excretion of silver in 23 patients with second- and third-degree thermal burns. Mean serum silver concentrations were modestly elevated throughout the patients' hospital course. Urinary excretion of silver was markedly elevated, especially in those patients with more severe burns. Indeed, in patients who had burns covering more than 60% of the total body surface area mean peak silver excretion was 1100 micrograms/24 hr (normal, less than 1 micrograms/24 hr). Thus, silver ion is absorbed across the burn wound in thermal injury patients treated with silver sulfadiazine. The 24-hour urinary excretion of silver appears to be a very sensitive indicator of cutaneous absorption in these patients. Possible implications of this cutaneous silver absorption warrant further evaluation.

  19. Antibacterial activities of silver nanoparticles and antibiotic-adsorbed silver nanoparticles against biorecycling microbes.

    Science.gov (United States)

    Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

    2014-09-20

    Silver nanoparticles have a huge share in nanotechnology based products used in clinical and hygiene products. Silver nanoparticles leaching from these medical and domestic products will eventually enter terrestrial ecosystems and will interact with the microbes present in the land and water. These interactions could be a threat to biorecycling microbes present in the Earth's crust. The antimicrobial action towards biorecycling microbes by leached silver nanoparticles from medical waste could be many times greater compared to that of silver nanoparticles leached from other domestic products, since medical products may contain traditional antibiotics along with silver nanoparticles. In the present article, we have evaluated the antimicrobial activities of as-synthesized silver nanoparticles, antibiotics - tetracycline and kanamycin, and antibiotic-adsorbed silver nanoparticles. The antimicrobial action of silver nanoparticles with adsorbed antibiotics is 33-100% more profound against the biorecycling microbes B. subtilis and Pseudomonas compared to the antibacterial action of silver nanoparticles of the same concentration. This study indicates that there is an immediate and urgent need for well-defined protocols for environmental exposure to silver nanoparticles, as the use of silver nanoparticles in nanotechnology based products is poorly restricted.

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

    Science.gov (United States)

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

    2006-03-01

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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  3. Silver nanoparticles cause complications in pregnant mice

    Directory of Open Access Journals (Sweden)

    Zhang XF

    2015-11-01

    Full Text Available Xi-Feng Zhang,1,2 Jung-Hyun Park,1 Yun-Jung Choi,1 Min-Hee Kang,1 Sangiliyandi Gurunathan,1 Jin-Hoi Kim11Department of Animal Biotechnology, Konkuk University, Seoul, Republic of Korea; 2College of Biological and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, People’s Republic of ChinaBackground: Silver nanoparticles (AgNPs have attracted much interest and have been used for antibacterial, antifungal, anticancer, and antiangiogenic applications because of their unique properties. The increased usage of AgNPs leads to a potential hazard to human health. However, the potential effects of AgNPs on animal models are not clear. This study was designed to investigate the potential impact of AgNPs on pregnant mice.Methods: The synthesis of AgNPs was performed using culture extracts of Bacillus cereus. The synthesized AgNPs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. AgNPs were administrated into pregnant mice via intravenous infusion at 1.0 mg/kg doses at 6.5 days postcoitum (dpc. At 13.5, 15.5, and 17.5 dpc, the pregnant mice were euthanized, and the embryo and placenta were isolated. The meiotic status of oocytes was evaluated. DNA methylation studies were performed, and aberrant imprinting disrupted fetal, placental, and postnatal development. Quantitative real-time polymerase chain reaction analysis and Western blot were used to analyze various gene expressions.Results: The synthesized AgNPs were uniformly distributed and were spherical in shape with an average size of 8 nm. AgNPs exposure increased the meiotic progression of female germ cells in the fetal mouse ovaries, and maternal AgNP exposure significantly disrupted imprinted gene expression in 15.5 dpc embryos and placentas, such as Ascl2, Snrpn, Kcnq1ot1, Peg3, Zac1, H19, Igf2r, and Igf2; DNA methylation studies revealed that AgNPs exposure significantly altered the methylation levels of

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-07

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

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

    Science.gov (United States)

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

    2015-02-01

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

  6. Preparation of silver powder through glycerol process

    Indian Academy of Sciences (India)

    Unknown

    These in- clude reduction of silver salts by NaBH4, HCHO/NaOH/ ... solid inorganic/organic salt of metal is suspended in a liquid polyol, the suspension is stirred and heated to a given temperature. The reduction of metallic salt by polyol quantitatively ... Though the solubility of silver nitrate in glycerol at room temperature is ...

  7. Synthesis and characterization of fluorophore attached silver ...

    Indian Academy of Sciences (India)

    Silver nanoparticles stabilized by soluble starch were synthesized and characterized. in vivo studies in rats showed no toxicity and revealed their distribution in various tissues and permeability across BBB. This starch stabilized silver nanoparticles have good biological characteristics to act as a potential promising vector for ...

  8. Preparation of silver powder through glycerol process

    Indian Academy of Sciences (India)

    High purity fine silver powder with uniform particle morphology was prepared through glycerol process. The process involves reduction of silver nitrate by glycerol under atmospheric conditions at a temperature below 175°C. Glycerol, in this process, acts as a solvent as well as a reducing agent. The powders prepared ...

  9. Topical silver for preventing wound infection

    NARCIS (Netherlands)

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

    2010-01-01

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

  10. Preparation of silver powder through glycerol process

    Indian Academy of Sciences (India)

    Unknown

    Abstract. High purity fine silver powder with uniform particle morphology was prepared through glycerol process. The process involves reduction of silver nitrate by glycerol under atmospheric conditions at a tem- perature below 175°C. Glycerol, in this process, acts as a solvent as well as a reducing agent. The powders.

  11. Preparation of amine coated silver nanoparticles using ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. This article presents a simple method towards the preparation of functionalized silver nano- particles in a continuous medium. Silver nanoparticles were obtained through AgNO3 chemical reduction in ethanol and triethylenetetramine was used to stabilize and functionalize the metal. The product was characterized ...

  12. ECO-FRIENDLY SYNTHESIS OF SILVER NANOPARTICLES ...

    African Journals Online (AJOL)

    userpc

    thermal and antibacterial properties of silver nanoparticles have made them suitable for many industrial applications as such it is being rated as being amongst the most commercialized metallic nanoparticles. Quite a number of studies have reported either the extracellular or intracellular synthesis of silver nanoparticles ...

  13. Biosynthesis of silver nanoparticles synthesized by Aspergillus

    Indian Academy of Sciences (India)

    In the present study, biosynthesis of silver nanoparticles and its antioxidant, antimicrobial and cytotoxic activities were investigated. Silver nanoparticles were extracellularly synthesized using Aspergillus flavus and the formation of nanoparticles was observed after 72 h of incubation. The results recorded from colour ...

  14. Pharmacological Properties of Nanometals (Silver, Copper, Iron)

    OpenAIRE

    Chekman, I.S.

    2015-01-01

    The article summarizes the results of studies on the pharmacological, toxicological and specific properties of nanometals (silver, iron, copper). It is established that nanoparticles of silver, copper, iron exhibit antimicrobial action. Acute toxicity of nanometals depends on their nature, administration route and animal sex. Effects on heart activity and hemodynamic status as well as erythrocyte osmotic fragility have dose-dependent nature.

  15. Gold and Silver Extraction from Leach Solutions

    OpenAIRE

    Bagdaulet K. Kenzhaliyev; Renata R. Iskhakova; Zamzagul D. Dosymbaeva; Esen N. Sulejmenov

    2014-01-01

    There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  16. ELECTRO-GRAVIMETRIC RECOVERY OF SILVER FROM ...

    African Journals Online (AJOL)

    Silver is also used in X-ray photography, medicine (Ag2O,. AgNO3, Argyrols), bactericide, antiseptic, oil and water purifier (Ag3PO4). In tableware, electric components, circuits, stable electrodes, medals and batteries silver is applied as a conductor and corrosion resistant metal [4-6]. In Pakistan three main types of rocks like ...

  17. Characterization of Fe -doped silver phosphate glasses

    Indian Academy of Sciences (India)

    Silver-ion- conducting glasses (superionic solids) exhibit high electrical conductivity and therefore they are attractive as electrolytes for all-solid-state batteries or microbatteries operating at ambient temperature [4–6]. Recently, we used BaO/SrO as dopants in silver phosphate glass and studied various prop- erties [7,8].

  18. Biological and electrical properties of biosynthesized silver

    Indian Academy of Sciences (India)

    Biological and electrical properties of biosynthesized silver nanoparticles. Madhulika ... Abstract. In this work, silver nanoparticles (AgNPs) were synthesized biochemically at room temperature using aqueous extract of rhizome of Rheum australe plant. ... The obtained results may have potential applications as sensors.

  19. Biosynthesis of silver nanoparticles synthesized by Aspergillus ...

    Indian Academy of Sciences (India)

    In the present study, biosynthesis of silver nanoparticles and its antioxidant, antimicrobial and cytotoxic activities were investigated. Silver nanoparticles were extracellularly synthesized using Aspergillus flavus and the formation of nanoparticles was observed after 72 h of incubation. The results recorded from colour ...

  20. Radiation Transition of Hexagonal Silver to Cubic One Under Irradiation of Helium Ions

    International Nuclear Information System (INIS)

    Martynov, I.S.; Krasil'nikov, V.V.; Perepelkin, I.N.; Yasser El' Gendy; Ruzhitsky, V.V.

    2006-01-01

    It is shown by the method of structure electronography and transmission microscopy that a hexagonal nonequilibrium phase of silver with periods a=0,288(1) nm and c=0,471(1) nm and other platypus are created on chips of NaCl crystal and glist in superhigh cryogenic vacuum by condensation of silver films of 100 nm thickness on optical quartz glass. The phase is stable under heating up to T=673 K and irradiating by helium ions of 7...10 keV energy up tp the dose of 1·10 17 ion/cm 2 . It is transformed to the cubic phase with period a=0,40847(36) nm when irradiated by the dose beyond this value. Breaking blocks-crystallites of size up to 50...100 nm and decreasing two-dimensional their defects and forming gas micro bubbles foregoes to the transformation

  1. Effect of silver nitrate concentration of silver nanowires synthesized using a polyol method and their application as transparent conductive films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jian-Yang [Department of Electronic Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China); Hsueh, Yu-Lee [Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China); Huang, Jung-Jie, E-mail: jjhuang@mail.dyu.edu.tw [Department of Industrial Engineering and Management, DaYeh University, Changhua 51591, Taiwan (China); Wu, Jia-Rung [Department of Computer Science and Information Engineering, Asia University, Taichung 413, Taiwan (China)

    2015-06-01

    Silver nanowires were synthesized using a polyol process by employing ethylene glycol, poly(N-vinylpyrrolidone), and silver nitrate as precursors. The concentration of silver nitrate was varied to study the resulting changes in aspect ratios of silver nanowires. The experimental results indicated that the growth characteristics of silver nanowires were affected by the synthesis temperature, the concentration of silver nitrate, and the rate at which silver nitrate was added. Field-emission scanning electron microscopy, UV–visible spectrophotometry, and X-ray diffractometry were employed to characterize the silver nanowires. As the concentration of silver nitrate was reduced, the diameters of the silver nanowires decreased, increasing the aspect ratio. The optimal diameter and length of the silver nanowires were 100 nm and 20 μm, respectively. A thin film composed of silver nanowires exhibited average transmittance of 92.15% at visible wavelengths and a sheet resistance of 20 Ω/sq; such a film could be used as a transparent conductive film in commercial applications. - Highlights: • Using a polyol method to synthesize of silver nanowire • Concentration effect of silver nitrate on the synthesis was discussed. • Seed precursors are not used during the silver nanowire synthesizing. • The silver nanowire diameter and length were 100 nm and 20 μm, respectively. • High transmittance and low sheet resistance of silver nanowire film can be obtained.

  2. One-Pot Silver Nanoring Synthesis

    Directory of Open Access Journals (Sweden)

    Drogat Nicolas

    2009-01-01

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

  3. Synthesis of battery grade reduced silver powder

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  4. Silver manganese oxide electrodes for lithium batteries

    Science.gov (United States)

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

    2006-05-09

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

  5. Identity transformation

    DEFF Research Database (Denmark)

    Neergaard, Helle; Robinson, Sarah; Jones, Sally

    , with an understanding and rationale for using it, provides students with the opportunity to explore their own entrepreneurial identity in unforeseen ways. It builds on insights from three different streams of literature: (i) Bordieu’s theory of practice is used to analyze student understandings of themselves and others......) assists students in straddling the divide between identities, the emotions and tensions this elicits, and (iv) transform student understanding. We extend nudging theory into a new territory. Pedagogical nudging techniques may be able to unlock doors and bring our students beyond the unacknowledged...... of the courses lies outside the usual territory of entrepreneurship courses, being aimed at the students in the pre-idea phase. During the course students change their understandings about what an entrepreneurial habitus is and as a result they become more willing to take on this habitus, for some of them...

  6. Transforming vulnerability.

    Science.gov (United States)

    Jones, Patricia S; Zhang, Xinwei Esther; Meleis, Afaf I

    2003-11-01

    Asian American immigrant women engaged in filial caregiving are at special risk for health problems due to complex contextual factors related to immigration, cultural traditions, and role transition. This study examines the experience of two groups of immigrant Asian American women who are caring for older parents. A total of 41 women (22 Chinese American and 19 Filipino American) were interviewed in a study based on Strauss and Corbin's grounded theory methodology. The women were determined to be loyal to their traditional culture, which included strong filial values, while adapting to a new culture. Through the struggle of meeting role expectations and coping with paradox, the women mobilized personal and family resources to transform vulnerability into strength and well-being.

  7. Radioactive transformations

    CERN Document Server

    Rutherford, Ernest

    2012-01-01

    Radioactive Transformations describes Ernest Rutherford's Nobel Prize-winning investigations into the mysteries of radioactive matter. In this historic work, Rutherford outlines the scientific investigations that led to and coincided with his own research--including the work of Wilhelm Rӧntgen, J. J. Thomson, and Marie Curie--and explains in detail the experiments that provided a glimpse at special relativity, quantum mechanics, and other concepts that would shape modern physics. This new edition features a comprehensive introduction by Nobel Laureate Frank Wilczek which engagingly explains how Rutherford's early research led to a better understanding of topics as diverse as the workings of the atom's nucleus, the age of our planet, and the fusion in stars.

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

    Science.gov (United States)

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

    2014-09-01

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

  9. Biosynthesis of silver nanoparticles using Bacillus subtilis EWP-46 cell-free extract and evaluation of its antibacterial activity.

    Science.gov (United States)

    Velmurugan, Palanivel; Iydroose, Mahudunan; Mohideen, Mohmed Hanifa Abdul Kader; Mohan, Thankiah Selva; Cho, Min; Oh, Byung-Taek

    2014-08-01

    This study highlights the ability of nitrate-reducing Bacillus subtilis EWP-46 cell-free extract used for preparation of silver nanoparticles (AgNPs) by reduction of silver ions into nano silver. The production of AgNPs was optimized with several parameters such as hydrogen ion concentration, temperature, silver ion (Ag(+) ion) and time. The maximum AgNPs production was achieved at pH 10.0, temperature 60 °C, 1.0 mM Ag(+) ion and 720 min. The UV-Vis spectrum showed surface plasmon resonance peak at 420 nm, energy-dispersive X-ray spectroscopy (SEM-EDX) spectra showed the presence of element silver in pure form. Atomic force microscopy (AFM) and transmission electron microscopy images illustrated the nanoparticle size, shape, and average particle size ranging from 10 to 20 nm. Fourier transform infrared spectroscopy provided the evidence for the presence of biomolecules responsible for the reduction of silver ion, and X-ray diffraction analysis confirmed that the obtained nanoparticles were in crystalline form. SDS-PAGE was performed to identify the proteins and its molecular mass in the purified nitrate reductase from the cell-free extract. In addition, the minimum inhibitory concentration and minimum bactericidal concentration of AgNPs were investigated against gram-negative (Pseudomonas fluorescens) and gram-positive (Staphylococcus aureus) bacteria.

  10. Effect of Temperature on the Growth of Silver Nanoparticles Using Plasmon-Mediated Method under the Irradiation of Green LEDs

    Directory of Open Access Journals (Sweden)

    Shan-Wei Lee

    2014-12-01

    Full Text Available Plasmon-mediated shape conversion of spherical silver nanoparticles (NPs to nanostructures with other shapes under the irradiation of green LEDs (520 ± 20 nm, 35 mw/cm2 at various temperatures (60, 40, 20, 10, 5, and 0 °C was performed in this study. It was found that the bath temperature used in the reaction can influence the reaction rates, i.e., the times needed for the shape transformation process were 5, 11.5, 25, 45, 72, and 100 h at 60, 40, 20, 10, 5, and 0 °C, respectively. In addition, the bath temperature can also alter the morphologies of the final products. The major products are silver nanoplates at 60, 40 and 20 °C. However, they became decahedral silver NPs at 5 and 0 °C. The percentages of decahedral silver NPs synthesized at 60, 40, 20, 10, 5, and 0 °C are 0%, 1%, 5%, 45%, 73%, and 89%, respectively. Measuring the surface-enhanced Raman spectroscopy (SERS spectra of the probe molecule R6G in the presence of KBr showed that both silver nanoplate colloids synthesized at 60 °C and decahedral silver NP colloids synthesized at 0 °C in the absence of PVP had good SERS activities.

  11. Effect of Temperature on the Growth of Silver Nanoparticles Using Plasmon-Mediated Method under the Irradiation of Green LEDs.

    Science.gov (United States)

    Lee, Shan-Wei; Chang, Shi-Hise; Lai, Yen-Shang; Lin, Chang-Cheng; Tsai, Chin-Min; Lee, Yao-Chang; Chen, Jui-Chang; Huang, Cheng-Liang

    2014-12-05

    Plasmon-mediated shape conversion of spherical silver nanoparticles (NPs) to nanostructures with other shapes under the irradiation of green LEDs (520 ± 20 nm, 35 mw/cm²) at various temperatures (60, 40, 20, 10, 5, and 0 °C) was performed in this study. It was found that the bath temperature used in the reaction can influence the reaction rates, i.e. , the times needed for the shape transformation process were 5, 11.5, 25, 45, 72, and 100 h at 60, 40, 20, 10, 5, and 0 °C, respectively. In addition, the bath temperature can also alter the morphologies of the final products. The major products are silver nanoplates at 60, 40 and 20 °C. However, they became decahedral silver NPs at 5 and 0 °C. The percentages of decahedral silver NPs synthesized at 60, 40, 20, 10, 5, and 0 °C are 0%, 1%, 5%, 45%, 73%, and 89%, respectively. Measuring the surface-enhanced Raman spectroscopy (SERS) spectra of the probe molecule R6G in the presence of KBr showed that both silver nanoplate colloids synthesized at 60 °C and decahedral silver NP colloids synthesized at 0 °C in the absence of PVP had good SERS activities.

  12. Preparation and characterization of chitosan-silver/hydroxyapatite composite coatings onTiO{sub 2} nanotube for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yajing [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, Xuejiao [Medical Informatics, Hebei North University, Zhangjiakou 075000 (China); Li, Caixia [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Huang, Yong [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); College of Lab Medicine, Hebei North University, Zhangjiakou 075000 (China); Ding, Qiongqiong [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Pang, Xiaofeng, E-mail: xfpang@aliyun.com [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2015-03-30

    Highlights: • Chitosan/silver-doped hydroxyapatite biocomposite coating was successfully deposited on anodized Ti by electrochemical deposition. • The chemical state of silver in the synthesized coatings was studied by XPS peak deconvolution. • The synthesized coatings have excellent antibacterial activity because of synergistic effect of the Ag and CS. • The CSAgHAp coatings showed good biocompatibility and no adverse effect in cell culture tests. - Abstract: A biocomposite coating containing chitosan, silver, and hydroxyapatite was developed on anodized titanium substrate by electrochemical deposition. Coatings were characterized by field-emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and polarisation studies. Results showed that the prepared coatings had compact and dense morphology with a thickness of 6.2 ± 0.7 μm and that silver was evenly distributed. Testing the prepared coatings with Gram-positive and Gram-negative bacterial strains exhibited antibacterial activity because of the synergistic effect of silver and chitosan. The prepared coatings were also found to be nontoxic to MC3T3-E1 cells. These results suggested that chitosan/silver-hydroxyapatite biocomposite coatings can prevent the bacterial infection of implants.

  13. Characterization of silver nanoparticles by green synthesis method using Pedalium murex leaf extract and their antibacterial activity

    Science.gov (United States)

    Anandalakshmi, K.; Venugobal, J.; Ramasamy, V.

    2016-03-01

    In this paper, an aqueous extract of fresh leaves of Pedalium murex was used for the synthesis of silver (Ag) nanoparticles. Different biological methods are gaining recognition for the production of silver nanoparticles (AgNPs) due to their multiple applications. The use of plants in the green synthesis of nanoparticles emerges as a cost-effective and eco-friendly approach. Characterization of nanoparticles was done using different methods, which include; ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FTIR), powder X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray analysis (EDAX), fluorescence emission spectroscopy, transmission electron microscope (TEM), dynamic light scattering (DLS), zeta potential and antibacterial activity. UV-visible spectrum of the aqueous medium containing silver nanoparticles showed absorption peak at around 430 nm. Fourier transform infrared spectra had shown that the biomolecule compounds were responsible for the reduction and capping material of silver nanoparticles. XRD study showed the particles to be crystalline in nature, with a face-centered cubic (fcc) structure. The size and stability were detected using DLS and zeta potential analysis. The antibacterial activity of AgNPs against generally found bacteria was assessed to find their potential use in silver-containing antibacterial product.

  14. Simultaneous size characterization and mass quantification of the in vivo core-biocorona structure and dissolved species of silver nanoparticles.

    Science.gov (United States)

    Dong, Lijie; Zhou, Xiaoxia; Hu, Ligang; Yin, Yongguang; Liu, Jingfu

    2018-01-01

    Size characterization of silver nanoparticles with biomolecule corona (AgNP@BCs) and mass quantification of various silver species in organisms are essential for understanding the in vivo transformation of AgNPs. Herein, we report a versatile method that allows simultaneous determination of the size of AgNP@BCs and mass concentration of various silver species in rat liver. Both particulate and ionic silver were extracted in their original forms from the organs by alkaline digestion, and analyzed by size exclusion chromatography combined with inductively coupled plasma mass spectrometry (SEC-ICP-MS). While the silver mass concentrations were quantified by ICP-MS with a detection limit of 0.1μg/g, the effective diameter of AgNP@BCs was determined based on the retention time in SEC separation with size discrimination of 0.6-3.3nm. More importantly, we found that the BC thickness of AgNP@BCs is core size independent, and a linear correlation was found between the effective diameter and core diameter of AgNP@BCs in extracted tissues, which was used to calibrate the core diameter with standard deviations in the range of 0.2-1.1nm. The utility of this strategy was demonstrated through application to rat livers in vivo. Our method is powerful for investigating the transformation mechanism of AgNPs in vivo. Copyright © 2017. Published by Elsevier B.V.

  15. Synthesis of eco-friendly silver nanoparticles from Morinda tinctoria leaf extract and its larvicidal activity against Culex quinquefasciatus.

    Science.gov (United States)

    Kumar, K Ramesh; Nattuthurai, N; Gopinath, Ponraj; Mariappan, Tirupathi

    2015-02-01

    Mosquitoes are the major vector for the transmission of malaria, dengue fever, yellow fever, filariasis, chikungunya and Japanese encephalitis, and they accounted for global mortality and morbidity with increased resistance to common insecticides. The aim of this study was to investigate the larvicidal potential of the acetone leaf extracts of Morinda tinctoria and synthesized silver nanoparticles against third instar larvae of Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. Synthesized AgNPs were characterized by ultraviolet-visible (UV-vis) spectroscopy, Atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) analysis. The synthesized silver nanoparticles have also been tested against the third instar larvae of C. quinquefasciatus. The leaf extract and the AgNPs high mortality values were 50 % lethal concentration (LC50) = 8.088 and 1.442 ppm against C. quinquefasciatus, respectively. The results recorded from ultraviolet-visible spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy support the biosynthesis and characterization of silver nanoparticles. These results suggest that the leaf extract of M. tinctoria and synthesis of AgNPs have the potential to be used as an ideal eco-friendly approach for the control of C. quinquefasciatus. By this approach, it is suggestive that this rapid synthesis of nanoparticles would be proper for developing a biological process for mosquito control.

  16. Corrosion processes of triangular silver nanoparticles compared to bulk silver

    Energy Technology Data Exchange (ETDEWEB)

    Keast, V. J., E-mail: vicki.keast@newcastle.edu.au; Myles, T. A. [University of Newcastle, School of Mathematical and Physical Sciences (Australia); Shahcheraghi, N.; Cortie, M. B. [University of Technology Sydney, Institute for Nanoscale Technology (Australia)

    2016-02-15

    Excessive corrosion of silver nanoparticles is a significant impediment to their use in a variety of potential applications in the biosensing, plasmonic and antimicrobial fields. Here we examine the environmental degradation of triangular silver nanoparticles (AgNP) in laboratory air. In the early stages of corrosion, transmission electron microscopy shows that dissolution of the single-crystal, triangular, AgNP (side lengths 50–120 nm) is observed with the accompanying formation of smaller, polycrystalline Ag particles nearby. The new particles are then observed to corrode to Ag{sub 2}S and after 21 days nearly full corrosion has occurred, but some with minor Ag inclusions remaining. In contrast, a bulk Ag sheet, studied in cross section, showed an adherent corrosion layer of only around 20–50 nm in thickness after over a decade of being exposed to ambient air. The results have implications for antibacterial properties and ecotoxicology of AgNP during corrosion as the dissolution and reformation of Ag particles during corrosion will likely be accompanied by the release of Ag{sup +} ions.

  17. Analysis of ancient silver coins

    International Nuclear Information System (INIS)

    Flament, Christophe; Marchetti, Patrick

    2004-01-01

    Writing from the numismatist point of view, the authors open this paper by reviewing critically the use of scientific methods for the studies of ancient coins. They also report about an application of the PIXE method at low incident proton energy to one of the most celebrated and known coinage in the ancient history: the Athenian silver coins of the fifth century BC. The results of those analyses indicate that the metallic composition of several coins usually taken as ancient imitations of Athenian coins does not differ from that of the genuine ones. Those analyses confirm what the authors have inferred from numismatic sources: These coins are probably genuinely Athenian

  18. Nanopackaging of Silver using Spice Extract and their ...

    African Journals Online (AJOL)

    The aim of the present study was to synthesize silver nanoparticles using spice extracts as reducing agents and further evaluate their anti-microbial activities. Silver has been shown to possess antimicrobial activity. The silver nanoparticles were prepared by solvent evaporation method. The silver nanoparticles were ...

  19. Mycosynthesis of Silver Nanoparticles from Candida albicans and its ...

    African Journals Online (AJOL)

    Purpose: To produce and characterize silver nanoparticles using Candida albicans and evaluate its antibacterial properties. Methods: Extracellular silver nanoparticles were biosynthesized using C. albicans. The biomass obtained from cultures of C. albicans was used to synthesize silver nanoparticles in 1.5 mM silver ...

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

    African Journals Online (AJOL)

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

  1. Suitsetamisega võitlemisel ei aita inimeste kiusamine / Silver Meikar

    Index Scriptorium Estoniae

    Meikar, Silver, 1978-

    2004-01-01

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

  2. 21 CFR 872.3840 - Endodontic silver point.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 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 to...

  3. Green synthesis of silver nanoparticles from leaf extracts of ...

    African Journals Online (AJOL)

    In this work, metallic silver nanoparticles were synthesized from leaf extracts of Parquetina nigrescens and Synedrella nodiflora. Silver ion was reduced to metallic silver on treatment of AgNO solution with aqueous extracts of the 3 two plants within 30minutes. The effects of time and the volume of extract to silver salt solution ...

  4. Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Alexander Birich

    2018-02-01

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

  6. Catalytic coupling reaction mechanism of 4-nitrobenzenethiol on silver clusters: a density functional theoretical study.

    Science.gov (United States)

    Chen, Xiao; Wei, Wei; Li, Laicai; Liu, Liuxie; Pan, Rui; Tian, Anmin

    2017-10-23

    The catalytic coupling reaction mechanism of the transformation from 4-nitrobenzenethiol (4-NBT) to 4,4'-dimercaptoazobenzene (4,4'-DMAB) on a silver cluster was studied by density functional theory. Reactants, intermediates, transition states and products were optimized with the B3LYP method using the 6-311 + G(d,p) basis set (Ag using the pseudo potential basis set of LanL2DZ). Transition states and intermediates were confirmed by the corresponding vibration analysis and intrinsic reaction coordinates (IRC). Consistent with literature reports, the key point of the transformation from 4-NBT absorbed on the surface of Ag 5 clusters to 4,4'-DMAB is the elimination of two O atoms on the amino group. Meanwhile, the catalytic coupling reaction of 4-nitrobenzenethiol on a silver cluster is easy to carry out under irradiation. The possibility of "inter system channeling" (ISC) between different potential energy surfaces in the coupling reaction of 4-NBT is further discussed. The irradiation has an auxiliary catalytic effect on the coupling reaction. Our research results can explain the observed experimental phenomena. Graphical abstract Catalytic coupling reaction mechanism of the transformation from 4-nitrothiophenol (4-NBT) to 4,4'-dimercaptoazobenzene (4,4'-DMAB) on silver clusters studied by density functional theory.

  7. Preparation and stability of silver/kerosene nanofluids.

    Science.gov (United States)

    Li, Dan; Fang, Wenjun

    2012-07-02

    A series of silver nanoparticles surface-coated with di-n-dodecyldithiophosphate, di-n-cetyldithiophosphate, or di-n-octadecyldithiophosphate have been prepared and have good dispersity in alkanes or kerosene. Stable silver nanofluids can be formed in alkanes or kerosene with the surface-coated silver nanoparticles. Thermal stability of the silver nanofluids has been measured at different temperatures. The effects of the silver nanoparticles on the thermal oxidation of kerosene have been investigated at different temperatures. The coatings can be released from the surface of the silver nanoparticles above 150°C, giving oxygen access to the silver core and inhibiting the kerosene oxidized by oxygen.

  8. Synthesis of silver nanoparticles by coastal plant Prosopis chilensis (L.) and their efficacy in controlling vibriosis in shrimp Penaeus monodon

    Science.gov (United States)

    Kandasamy, Kathiresan; Alikunhi, Nabeel M.; Manickaswami, Gayathridevi; Nabikhan, Asmathunisha; Ayyavu, Gopalakrishnan

    2013-02-01

    The present work investigated the effect of leaf extract from coastal plant Prosopis chilensis on synthesis of silver nanoparticles using AgNO3 as a substrate and to find their antibacterial potential on pathogenic Vibrio species in the shrimp, Penaeus monodon. The leaf extract could be able to produce silver nanoparticles, as evident by gradual change in colour of the reaction mixture consisted of the extract and 1 mM AgNO3 to dark brown. The silver nanoparticles exhibited 2 θ values corresponding to the presence of silver nanocrystal, as evident by X-ray diffraction spectrum. The peaks corresponding to flavanones and terpenoids were found to be stabilizing agents of the nanoparticles, as revealed by Fourier transform infrared spectroscopy. The size of silver nanoparticles ranged from 5 to 25 nm with an average of 11.3 ± 2.1 nm and was mostly of spherical in shape, as confirmed by transmission electron microscopy. The silver nanoparticles were found to inhibit Vibrio pathogens viz., Vibrio cholerae, V. harveyi, and V. parahaemolyticus and this antibacterial effect was better than that of leaf extract, as proved by disc diffusion assay. The nanoparticles were then tested in the shrimp Penaeus monodon challenged with the four species of Vibrio pathogens for 30 days. The shrimps fed with silver nanoparticles exhibited higher survival, associated with immunomodulation in terms of higher haemocyte counts, phenoloxidase and antibacterial activities of haemolymph of P. monodon which is on par with that of control. Thus, the present study proved the possibility of using silver nanoparticles produced by coastal Prosopis chilensis as antibacterial agent in controlling vibriosis.

  9. Phytofabrication of bioinduced silver nanoparticles for biomedical applications

    Directory of Open Access Journals (Sweden)

    Ahmad N

    2015-11-01

    Full Text Available Nabeel Ahmad,1 Sharad Bhatnagar,1 Syed Salman Ali,2 Rajiv Dutta3 1School of Biotechnology, 2School of Pharmaceutical Sciences, IFTM University, Lodhipur Rajput, Moradabad, Uttar Pradesh, India; 3Institute of Bio-Science and Technology, Shri Ramswaroop Memorial University, Barabanki, Uttar Pradesh, India Abstract: Synthesis of nanomaterials holds infinite possibilities as nanotechnology is revolutionizing the field of medicine by its myriad applications. Green synthesis of nanoparticles has become the need of the hour because of its eco-friendly, nontoxic, and economic nature. In this study, leaf extract of Rosa damascena was used as a bioreductant to reduce silver nitrate, leading to synthesis of silver nanoparticles (AgNPs in a single step, without the use of any additional reducing or capping agents. The synthesized nanoparticles were characterized by the use of UV-visible spectroscopy, fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy. Time-dependent synthesis of AgNPs was studied spectrophotometrically. Synthesized AgNPs were found to possess flower-like spherical structure where individual nanoparticles were of 16 nm in diameter, whereas the agglomerated AgNPs were in the range of 60–80 nm. These biologically synthesized AgNPs exhibited significant antibacterial activity against Gram-negative bacterial species but not against Gram-positive ones (Escherichia coli and Bacillus cereus. Anti-inflammatory and analgesic activities were studied on a Wistar rat model to gauge the impact of AgNPs for a probable role in these applications. AgNPs tested positive for both these activities, although the potency was less as compared to the standard drugs. Keywords: silver nanoparticles, green synthesis, anti-inflammatory, analgesic, animal model study, antibacterial

  10. Polystyrene Based Silver Selective Electrodes

    Directory of Open Access Journals (Sweden)

    Shiva Agarwal

    2002-06-01

    Full Text Available Silver(I selective sensors have been fabricated from polystyrene matrix membranes containing macrocycle, Me6(14 diene.2HClO4 as ionophore. Best performance was exhibited by the membrane having a composition macrocycle : Polystyrene in the ratio 15:1. This membrane worked well over a wide concentration range 5.0×10-6–1.0×10-1M of Ag+ with a near-Nernstian slope of 53.0 ± 1.0 mV per decade of Ag+ activity. The response time of the sensor is <15 s and the membrane can be used over a period of four months with good reproducibility. The proposed electrode works well in a wide pH range 2.5-9.0 and demonstrates good discriminating power over a number of mono-, di-, and trivalent cations. The sensor has also been used as an indicator electrode in the potentiometric titration of silver(II ions against NaCl solution. The sensor can also be used in non-aqueous medium with no significant change in the value of slope or working concentration range for the estimation of Ag+ in solution having up to 25% (v/v nonaqueous fraction.

  11. Sunlight mediated synthesis of silver nanoparticles by a novel actinobacterium (Sinomonas mesophila MPKL 26) and its antimicrobial activity against multi drug resistant Staphylococcus aureus.

    Science.gov (United States)

    Manikprabhu, Deene; Cheng, Juan; Chen, Wei; Sunkara, Anil Kumar; Mane, Sunilkumar B; Kumar, Ram; das, Mousumi; N Hozzein, Wael; Duan, Yan-Qing; Li, Wen-Jun

    2016-05-01

    Synthesis of silver nanoparticles using microorganism are many, but there are only scanty reports using actinobacteria. In the present study, the actinobacterium of the genus Sinomonas was reported to synthesis silver nanoparticles for the first time. A photo-irradiation based method was developed for the synthesis of silver nanoparticles, which includes two day old cultural supernatant of novel species Sinomonas mesophila MPKL 26 and silver nitrate solution, exposed to sunlight. The preliminary synthesis of silver nanoparticles was noted by the color change of the solution from colorless to brown; the synthesis was further confirmed using UV-visible spectroscopy which shows a peak between 400 and 450nm. Spherical shape silver nanoparticles of size range 4-50nm were synthesized, which were characterized using transmission electron microscopy. The Fourier transform infrared spectroscopy result indicates that, the metabolite produced by the novel species S. mesophila MPKL 26 was the probable reducing/capping agent involved in the synthesis of silver nanoparticles. The synthesized silver nanoparticles maintained consistent shape with respect to different time periods. The synthesized silver nanoparticles were evaluated for the antimicrobial activity against multi drug resistant Staphylococcus aureus which show good antimicrobial activity. The method developed for synthesis is easy, requires less time (20min) and produces spherical shape nanoparticles of size as small as 4nm, having good antimicrobial activity. Hence, our study enlarges the scope of actinobacteria for the rapid biosynthesis of silver nanoparticles and can be used in formulating remedies for multi drug resistant S. aureus. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    OpenAIRE

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver ...

  13. Nanostructured Antibacterial Silver Deposited on Polypropylene Nonwovens

    Science.gov (United States)

    Hong-Bo, Wang; Jin-Yan, Wang; Qu-Fu, Wei; Jian-Han, Hong; Xiao-Yan, Zhao

    Nanostructured silver films were deposited on polypropylene (PP) nonwovens by RF magnetron sputter coating to obtain the antibacterial properties. Shake flask test was used to evaluate the antibacterial properties of the materials. Atomic force microscope (AFM) was utilized to observe the surface morphology. Energy-dispersive X-ray (EDX) was also employed to analyze the surface elemental compositions. The antibacterial results indicated that the prolonged deposition time led to a significant improvement in antibacterial effect, and sputtering power and argon pressure did not show obvious effect on antibacterial performance. It is believed that the total amount of silver ions released from the silver coating was increased as the deposition time increased. AFM images and quantitative analysis of EDX, respectively revealed that increase in deposition time led to the increased coverage of silver film and the increased silver weight percentage per unit surface, which provided evidences for the increased release rate of silver ions from the coating. Moreover, it was found that the optimum silver coating thickness was about 3 nm, taking antibacterial effect and cost of production into account.

  14. Silver nanoparticles in soil–plant systems

    International Nuclear Information System (INIS)

    Anjum, Naser A.; Gill, Sarvajeet S.; Duarte, Armando C.; Pereira, Eduarda; Ahmad, Iqbal

    2013-01-01

    Silver nanoparticles (AgNPs) have broad spectrum antimicrobial/biocidal properties against all classes of microorganisms and possess numerous distinctive physico-chemical properties compared to bulk Ag. Hence, AgNPs are among the most widely used engineered NPs in a wide range of consumer products and are expected to enter natural ecosystems including soil via diverse pathways. However, despite: (i) soil has been considered as a critical pathway for NPs environmental fate, (ii) plants (essential base component of all ecosystems) have been strongly recommended to be included for the development of a comprehensive toxicity profile for rapidly mounting NPs in varied environmental compartments, and (iii) the occurrence of an intricate relationship between “soil–plant systems” where any change in soil chemical/biological properties is bound to have impact on plant system, the knowledge about AgNPs in soils and investigations on AgNPs–plants interaction is still rare and in its rudimentary stage. To this end, the current paper: (a) overviews sources, status, fate, and chemistry of AgNPs in soils, AgNPs-impact on soil biota, (b) critically discusses terrestrial plant responses to AgNPs exposure, and (c) illustrates the knowledge-gaps in the current perspective. Based on the available literature critically appraised herein, a multidisciplinary integrated approach is strongly recommended for future research in the current direction aimed at unveiling the rapidly mounting AgNPs-fate, transformation, accumulation, and toxicity potential in “soil–plant systems,” and their cumulative impact on environmental and human health

  15. Silver nanoparticles in soil-plant systems

    Energy Technology Data Exchange (ETDEWEB)

    Anjum, Naser A., E-mail: anjum@ua.pt [University of Aveiro, CESAM-Centre for Environmental and Marine Studies, Department of Chemistry (Portugal); Gill, Sarvajeet S. [MD University, Stress Physiology and Molecular Biology Lab, Centre for Biotechnology, Faculty of Life Sciences (India); Duarte, Armando C.; Pereira, Eduarda; Ahmad, Iqbal, E-mail: ahmadr@ua.pt [University of Aveiro, CESAM-Centre for Environmental and Marine Studies, Department of Chemistry (Portugal)

    2013-09-15

    Silver nanoparticles (AgNPs) have broad spectrum antimicrobial/biocidal properties against all classes of microorganisms and possess numerous distinctive physico-chemical properties compared to bulk Ag. Hence, AgNPs are among the most widely used engineered NPs in a wide range of consumer products and are expected to enter natural ecosystems including soil via diverse pathways. However, despite: (i) soil has been considered as a critical pathway for NPs environmental fate, (ii) plants (essential base component of all ecosystems) have been strongly recommended to be included for the development of a comprehensive toxicity profile for rapidly mounting NPs in varied environmental compartments, and (iii) the occurrence of an intricate relationship between 'soil-plant systems' where any change in soil chemical/biological properties is bound to have impact on plant system, the knowledge about AgNPs in soils and investigations on AgNPs-plants interaction is still rare and in its rudimentary stage. To this end, the current paper: (a) overviews sources, status, fate, and chemistry of AgNPs in soils, AgNPs-impact on soil biota, (b) critically discusses terrestrial plant responses to AgNPs exposure, and (c) illustrates the knowledge-gaps in the current perspective. Based on the available literature critically appraised herein, a multidisciplinary integrated approach is strongly recommended for future research in the current direction aimed at unveiling the rapidly mounting AgNPs-fate, transformation, accumulation, and toxicity potential in 'soil-plant systems,' and their cumulative impact on environmental and human health.

  16. Comparison of bioconcentration of ionic silver and silver nanoparticles in zebrafish eleutheroembryos.

    Science.gov (United States)

    López-Serrano, A; Muñoz-Olivas, R; Sanz-Landaluze, J; Olasagasti, M; Rainieri, S; Cámara, C

    2014-08-01

    The production of silver nanoparticles has reached nowadays high levels. Bioconcentration studies, information on persistence and toxicity are fundamental to assess their global risk and thus necessary to establish legislations regarding their use. Previous studies on silver nanoparticle toxicity have determined a clear correlation between their chemical stability and toxicity. In this work, experimental conditions able to assure silver nanoparticles stability have been optimized. Then, zebrafish (Danio rerio) eleutheroembryos were exposed to ionic silver and to Ag NPs for comparison purposes. A protocol alternative to the OECD 305 technical guideline was used. To determine silver concentration in both the eleutheroembryos and the exposure media, an analytical method consisting in ultrasound assisted extraction, followed by inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry, was developed. Then, bioconcentration factors were calculated. The results revealed that ionic silver was more accumulative for zebrafish eleutheroembryos than nanoparticles at the levels tested. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Komninou Philomela

    2009-01-01

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

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

    Science.gov (United States)

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

    2018-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-28

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

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

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

    OpenAIRE

    Zamiri, Reza; Zakaria, Azmi; Husin, Mohd Shahril; Wahab, Zaidan Abd; Nazarpour, Forough Kalaei

    2011-01-01

    Reza Zamiri1, Azmi Zakaria1,2, Mohd Shahril Husin1, Zaidan Abd Wahab1, Forough Kalaei Nazarpour3 1Department of Physics, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 3Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia Abstract: In the present work, we prepared silver nanoparticles by laser ablation of pure silver plate in ethanol and then irradiated the silver nanoparticles using a 532 nm Q-switched Nd:Y...

  3. Silver-Russell Syndrome: A Case Report

    Science.gov (United States)

    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

  4. Transforming giants.

    Science.gov (United States)

    Kanter, Rosabeth Moss

    2008-01-01

    Large corporations have long been seen as lumbering, inflexible, bureaucratic--and clueless about global developments. But recently some multinationals seem to be transforming themselves: They're engaging employees, moving quickly, and introducing innovations that show true connection with the world. Harvard Business School's Kanter ventured with a research team inside a dozen global giants--including IBM, Procter & Gamble, Omron, CEMEX, Cisco, and Banco Real--to discover what has been driving the change. After conducting more than 350 interviews on five continents, she and her colleagues came away with a strong sense that we are witnessing the dawn of a new model of corporate power: The coordination of actions and decisions on the front lines now appears to stem from widely shared values and a sturdy platform of common processes and technology, not from top-down decrees. In particular, the values that engage the passions of far-flung workforces stress openness, inclusion, and making the world a better place. Through this shift in what might be called their guidance systems, the companies have become as creative and nimble as much smaller ones, even while taking on social and environmental challenges of a scale that only large enterprises could attempt. IBM, for instance, has created a nonprofit partnership, World Community Grid, through which any organization or individual can donate unused computing power to research projects and see what is being done with the donation in real time. IBM has gained an inspiring showcase for its new technology, helped business partners connect with the company in a positive way, and offered individuals all over the globe the chance to contribute to something big.

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

    Science.gov (United States)

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

    2013-09-01

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

  6. Phytofabrication of bioinduced silver nanoparticles for biomedical applications

    Science.gov (United States)

    Ahmad, Nabeel; Bhatnagar, Sharad; Ali, Syed Salman; Dutta, Rajiv

    2015-01-01

    Synthesis of nanomaterials holds infinite possibilities as nanotechnology is revolutionizing the field of medicine by its myriad applications. Green synthesis of nanoparticles has become the need of the hour because of its eco-friendly, nontoxic, and economic nature. In this study, leaf extract of Rosa damascena was used as a bioreductant to reduce silver nitrate, leading to synthesis of silver nanoparticles (AgNPs) in a single step, without the use of any additional reducing or capping agents. The synthesized nanoparticles were characterized by the use of UV-visible spectroscopy, fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy. Time-dependent synthesis of AgNPs was studied spectrophotometrically. Synthesized AgNPs were found to possess flower-like spherical structure where individual nanoparticles were of 16 nm in diameter, whereas the agglomerated AgNPs were in the range of 60–80 nm. These biologically synthesized AgNPs exhibited significant antibacterial activity against Gram-negative bacterial species but not against Gram-positive ones (Escherichia coli and Bacillus cereus). Anti-inflammatory and analgesic activities were studied on a Wistar rat model to gauge the impact of AgNPs for a probable role in these applications. AgNPs tested positive for both these activities, although the potency was less as compared to the standard drugs. PMID:26648715

  7. Discovery of ionic silver in silver nanoparticle suspension fabricated by arc discharge method

    International Nuclear Information System (INIS)

    Tien, D.-C.; Tseng, K.-H.; Liao, C.-Y.; Huang, J.-C.; Tsung, T.-T.

    2008-01-01

    As a result of mankind's over-reliance on antibiotics, germs are becoming more drug-resistant every year. The gradual but inexorable decline in the efficacy of traditional antibiotics is forcing scientists and doctors to search for new weapons in the fight against germs. Metallic silver nanoparticle (Ag 0 ) and ionic silver (Ag + ) are the future of the post-antibiotic era, with the latter playing perhaps the central role in this fight. Using the arc discharge method (ADM), our research has allowed us to fabricate silver nanoparticle suspension (SNPS) in deionized water with no added surfactants. Most related research in this field is confined to explore the composition of nanoparticle, ignoring ions. However, we aim to identify and measure the proportion of ionic silver in ADM-SNPS, using conductivity meters, centrifuges, titrator, and atomic absorption spectrophotometer (AA). The results of our experiments show that SNPS fabricated by means of ADM with no added surfactants contains metallic silver nanoparticle and ionic silver. The fabrication consumes silver rods at a rate of 100 mg/min, yielding metallic silver nanoparticle and ionic silver with concentrations of approximately 11 ppm and 19 ppm, respectively

  8. Green synthesis and characterization of silver nanoparticles using alcoholic flower extract of Nyctanthes arbortristis and in vitro investigation of their antibacterial and cytotoxic activities

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, Nayanmoni [Biotech Hub, Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Babu, Punuri Jayasekhar [Biotech Hub, Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Biomaterials and Tissue Engineering Laboratory, Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Mahanta, Chandan [Biotech Hub, Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Bora, Utpal, E-mail: ubora@iitg.ernet.in [Biotech Hub, Centre for the Environment, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India); Biomaterials and Tissue Engineering Laboratory, Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India)

    2015-01-01

    Here we report the synthesis of silver nanoparticles using ethanolic flower extract of Nyctanthes arbortristis, UVvisible spectra and TEM indicated the successful formation of silver nanoparticles. Crystalline nature of the silver nanoparticles was confirmed by X-ray diffraction. Fourier Transform Infra-Red Spectroscopy analysis established the capping of the synthesized silver nanoparticles with phytochemicals naturally occurring in the ethanolic flower extract of N. arbortristis. The synthesized silver nanoparticles showed antibacterial activity against the pathogenic strain of Escherichia coli MTCC 443. Furthermore, cytotoxicity of the silver nanoparticles was tested on mouse fibroblastic cell line (L929) and found to be non-toxic, which thus proved their biocompatibility. Antibacterial activity and cytotoxicity assay carried out in this study open up an important perspective of the synthesized silver nanoparticles. - Highlights: • The present study depicts the green synthesis of AgNPs using Nyctanthes arbortristis. • AuNPs found to be biocompatible and can be used for biomedical applications. • The FTIR, TGA and DTA results showed that AgNPs are bounded by organic coating. • The synthesized AgNPs showed antibacterial activity on E. Coli MTCC 443. • We investigated the antioxidant activity for both EFE and AgNPs.

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

    Science.gov (United States)

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

    2017-08-01

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

  10. Synthesis of water-dispersible silver nanoparticles by thermal decomposition of water-soluble silver oxalate precursors.

    Science.gov (United States)

    Togashi, Takanari; Saito, Kota; Matsuda, Yukiko; Sato, Ibuki; Kon, Hiroki; Uruma, Keirei; Ishizaki, Manabu; Kanaizuka, Katsuhiko; Sakamoto, Masatomi; Ohya, Norimasa; Kurihara, Masato

    2014-08-01

    Silver oxalate, one of the coordination polymer crystals, is a promising synthetic precursor for transformation into Ag nanoparticles without any reducing chemicals via thermal decomposition of the oxalate ions. However, its insoluble nature in solvents has been a great disadvantage, especially for systematic control of crystal growth of the Ag nanoparticles, while such control of inorganic nanoparticles has been generally performed using soluble precursors in homogeneous solutions. In this paper, we document our discovery of water-soluble species from the reaction between the insoluble silver oxalate and N,N-dimethyl-1,3-diaminopropane. The water-soluble species underwent low-temperature thermal decomposition of the oxalate ions at 30 °C with evolution of CO2 to reduce Ag+ to Ag0. Water-dispersible Ag nanoparticles have been successfully synthesized from the water-soluble species in the presence of gelatin via similar thermal decomposition at 100 °C. The gelatin-protected and water-dispersible Ag nanoparticles with a mean diameter of 25.1 nm appeared. In addition, antibacterial activity of the prepared water-dispersible Ag nanoparticles has been preliminarily investigated.

  11. Biosynthesis of Silver Nanoparticles by Marine Invertebrate (Polychaete and Assessment of Its Efficacy against Human Pathogens

    Directory of Open Access Journals (Sweden)

    Reena Singh

    2014-01-01

    Full Text Available Synthesis of metallic nanoparticles by chemical and physical method makes the process often cumbersome due the usage of toxic and expensive chemicals. The present study reports the biosynthesis of silver nanoparticles using marine invertebrate (polychaete extract at room temperature. The ultraviolet-visible (UV-Vis spectroscopy revealed the formation of silver nanoparticles (AgNPs by exhibiting the typical surface plasmon absorption maximum at 418–420 nm. Structure and composition of AgNPs were analyzed by atomic force microscopy (AFM. Average particle size of AgNPs ranged from 40 to 90 nm, confirmed by scanning electron microscopy (SEM analysis. The energy-dispersive X-ray spectroscopy (EDX of the nanoparticles dispersion confirmed the presence of elemental silver signal, whereas X-ray diffraction (XRD substantiated the crystalline nature of synthesized nanoparticle. Fourier transform infrared spectroscopy (FTIR spectral analysis showed the presence of amides phenols, ethers, and fatty acids as major biomolecules responsible for the reduction of silver ions. The possible mechanism responsible for the synthesis of AgNPs by these biomolecules was also illustrated by chemical reactions. The synthesized AgNPs showed comparatively good antibacterial activity against the tested human pathogens. This study advocates that not only plants and microbes but also marine invertebrates do have potential for synthesizing nanoparticles by a cost-effective and eco-friendly approach.

  12. Preparation of silver-chitosan nanocomposites and coating on bandage for antibacterial wound dressing application

    Energy Technology Data Exchange (ETDEWEB)

    Susilowati, Endang, E-mail: endwati@yahoo.co.id; Ashadi [Chemistry Education Department, Faculty of Teacher Training and Education, Universitas Sebelas Maret Surakarta (Indonesia); Maryani [Medical Doctor Program, Faculty of Medicine, Universitas Sebelas Maret Surakarta, Indonesia Jl. Ir Sutami 36 A Surakarta Indonesia 53126 (Indonesia)

    2016-02-08

    Bandage is a medical device that is essential for wound dressing. To improve the performance of the bandage, it has been coated by silver-chitosan nanocomposites (Ag/Chit) with pad-dry-cure method. The nanocomposites were performed by chemical reduction method at room temperature using glucose as reducing agent, sodium hydroxide (NaOH) as accelerator reagent, silver nitrate (AgNO{sub 3}) as metal precursor and chitosan as stabilizing agent. Localized surface plasmon resonance (LSPR) absorption band of silver nanoparticles was investigated using UV-Vis spectrophotometer. The bandage coated Ag/Chit nanocomposites (B-Ag/Chit) were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). In addition, antibacterial activity of the bandage toward Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) were also studied. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 412.2 – 423.2 nm. Coating of nanocomposite cause increasing rigidity of bandage and decreasing on crystallinity. The bandages of B-Ag/Chit demonstrated good activity against both Gram positive (S. aureus) and Gram negative (E.Coli). Thus the bandages have a potential to be used for antibacterial wound dressing application.

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

    Directory of Open Access Journals (Sweden)

    Sutanuka Pattanayak

    2017-09-01

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

  14. Microwave-Assisted Synthesis of Chitosan/Polyvinyl Alcohol Silver Nanoparticles Gel for Wound Dressing Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Hiep

    2016-01-01

    Full Text Available The purpose of this study was to fabricate chitosan/poly(vinyl alcohol/Ag nanoparticles (CPA gels with microwave-assistance for skin applications. Microwave irradiation was employed to reduce silver ions to silver nanoparticles and to crosslink chitosan (CS with polyvinyl alcohol (PVA. The presence of silver nanoparticles in CPA gels matrix was examined using UV-Vis spectroscopy, transmission electron microscopy, and X-ray diffraction. The interaction of CS and PVA was analysed by Fourier transform infrared spectroscopy. The release of silver ions was determined by atomic absorption spectrometry. The antimicrobial properties of CPA gels against P. aeruginosa and S. aureus were investigated using agar diffusion method. Finally, the biocompatibility and wound-healing ability of the gels were studied using fibroblast cells (in vitro and mice models (in vivo. In conclusion, the results showed that CPA gels were successfully fabricated using microwave irradiation method. These gels can be applied to heal an open wound thanks to their antibacterial activity and biocompatibility.

  15. Characterization of n-TiO2 thin films modified with silver nanoparticles

    International Nuclear Information System (INIS)

    Cueto, L.F.; Sanchez-Cervantes, E.M.

    2010-01-01

    Carbon dioxide accumulation in the atmosphere has gained much attention and has reopened many research lines that initiated two or three decades ago. Electrochemical reduction represents one of the most discussed methods, especially where semiconductor and metal-semiconductor cathodes are used to achieve CO 2 transformation into higher-energy products. In the present work, the influence of silver nanoparticles upon CO 2 reduction on n-TiO 2 cathodes in aqueous media is presented. Silver nanoparticles with an average diameter of 250nm were deposited on n-TiO 2 surfaces by the electrochemical Double-Pulse Potential method. A Grazing-Incidence X-Ray Diffraction structural analysis is presented showing the presence of metallic silver, while Atomic Force Microscopy shows surface roughness and particle size before and after surface modification. These measurements were confirmed by Scanning-Electron Microscopy acquainting for the formation of metal particles on the n-TiO 2 surface. Enhancement of CO 2 reduction by the presence of silver on cathodes is shown by cyclic voltammetry. (author)

  16. Cellulase assisted synthesis of nano-silver and gold: Application as immobilization matrix for biocatalysis.

    Science.gov (United States)

    Mishra, Abhijeet; Sardar, Meryam

    2015-01-01

    In the present study, we report in vitro synthesis of silver and gold nanoparticles (NPs) using cellulase enzyme in a single step reaction. Synthesized nanoparticles were characterized by UV-VIS spectroscopy, Dynamic Light Spectroscopy (DLS), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), Circular Dichroism (CD) and Fourier Transform Infrared Spectroscopy (FTIR). UV-visible studies shows absorption band at 415nm and 520nm for silver and gold NPs respectively due to surface plasmon resonance. Sizes of NPs as shown by TEM are 5-25nm for silver and 5-20nm for gold. XRD peaks confirmed about phase purity and crystallinity of silver and gold NPs. FTIR data shows presence of amide I peak on both the NPs. The cellulase assisted synthesized NPs were further exploited as immobilization matrix for cellulase enzyme. Thermal stability analysis reveals that the immobilized cellulase on synthesized NPs retained 77-80% activity as compared to free enzyme. While reusability data suggests immobilized cellulase can be efficiently used up to sixth cycles with minimum loss of enzyme activity. The secondary structural analysis of cellulase enzyme during the synthesis of NPs and also after immobilization of cellulase on these NPs was carried out by CD spectroscopy. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Ayman M. Atta

    2014-07-01

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

  18. Green Biosynthesis of Silver Nanoparticles Using Callicarpa maingayi Stem Bark Extraction

    Directory of Open Access Journals (Sweden)

    Mohammed Zidan

    2012-07-01

    Full Text Available Different biological methods are gaining recognition for the production of silver nanoparticles (Ag-NPs due to their multiple applications. The use of plants in the green synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. In this study the green biosynthesis of silver nanoparticles using Callicarpa maingayi stem bark extract has been reported. Characterizations of nanoparticles were done using different methods, which include; ultraviolet-visible spectroscopy (UV-Vis, powder X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy dispersive X-ray fluorescence (EDXF spectrometry, zeta potential measurements and Fourier transform infrared (FT-IR spectroscopy. UV-visible spectrum of the aqueous medium containing silver nanoparticles showed absorption peak at around 456 nm. The TEM study showed that mean diameter and standard deviation for the formation of silver nanoparticles were 12.40 ± 3.27 nm. The XRD study showed that the particles are crystalline in nature, with a face centered cubic (fcc structure. The most needed outcome of this work will be the development of value added products from Callicarpa maingayi for biomedical and nanotechnology based industries.

  19. Wound healing applications of sericin/chitosan-capped silver nanoparticles incorporated hydrogel.

    Science.gov (United States)

    Verma, Jyoti; Kanoujia, Jovita; Parashar, Poonam; Tripathi, Chandra Bhusan; Saraf, Shubhini A

    2017-02-01

    Microbial contamination in wounds leading to severe sepsis can be treated by silver-based antiseptics. However, frequent application of silver-based antiseptics, staining of skin, burning, and irritation at application site resulted to poor patient compliances. Thus, we formulated sericin- and chitosan-capped silver nanoparticle (S/C-SNP)-loaded hydrogel for accelerated wound healing and antimicrobial properties. The wound healing property of sericin, antibacterial nature of chitosan and silver, and mucoadhesive property of carbopol were utilized in development of novel wound dressing hydrogel to investigate the combined effect of these materials for effective treatment of wounds. The chemical reduction method was successfully employed for the synthesis of SNPs using sericin and chitosan as a capping/reducing agent. The SNPs were characterized by ultraviolet-spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The optimized SNPs were further used for preparation of carbopol hydrogel (0.5, 0.75, and 1.0 % w/v). The prepared hydrogels were characterized for pH, viscosity, and texture analysis. The antimicrobial activity and wound healing activity of the optimized hydrogel (S/C-SNPs G-1) demonstrated higher bactericidal activity and wound closure, as supported by results of histopathology. Hydrogel containing capped SNPs has application in wound healing treatment.

  20. Characterization and Antimicrobial Activity of Silver Doped Hydroxyapatite Obtained by the Microwave Method

    Directory of Open Access Journals (Sweden)

    Meruyert KOIZHAIGANOVA

    2016-09-01

    Full Text Available In this study, silver (Ag doped hydroxyapatite (HA was produced by the microwave method and its antimicrobial activity was investigated. The physical, chemical and structural characteristics of the material were determined using multi-purpose X-ray diffractometry (XRD, Fourier transform infrared spectrometry (FTIR, and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS apparatus. The amount of silver in the solutions of silver-doped hydroxyapatite obtained were determined with the use of an inductively coupled plasma optical emission spectroscopy instrument (ICP-OES. The minimum inhibition concentration (MIC of the silver doped hydroxyapatite (Ag-HA against the test microorganisms was determined by the Broth Microdilution method. It was established that a concentration of 2.09-12.25 µg/ml was effective against gram-negative bacteria (Escherichia coli ATCC 12228, Salmonella typhimurium CCM 5445, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae CCM 2318, and 4.18-12.25 µg/ml was effective against gram-positive bacteria (Staphylococcus aureus ATCC6538-P, Bacillus subtilis ATCC 6633, Enterococcus faecalis ATCC 29212 and the yeast Candida albicans ATCC 10239.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.12133

  1. Synthesis and characterization of silver/talc nanocomposites using the wet chemical reduction method

    Directory of Open Access Journals (Sweden)

    Kamyar Shameli

    2010-09-01

    Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Wan Zin Wan Yunus1, Nor Azowa Ibrahim1, Majid Darroudi21Department of Chemistry, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, Selangor, MalaysiaAbstract: In this study, silver nanoparticles (Ag-NPs were synthesized using the wet chemical reduction method on the external surface layer of talc mineral as a solid support. Silver nitrate and sodium borohydride were used as the silver precursor and reducing agent in talc. The talc was suspended in aqueous AgNO3 solution. After the absorption of Ag+ on the surface, the ions were reduced with NaBH4. The interlamellar space limits were without many changes (ds = 9.34–9.19 Aº; therefore, Ag-NPs formed on the exterior surface of talc, with dave = 7.60–13.11 nm in diameter. The properties of Ag/talc nanocomposites (Ag/talc-NCs and the diameters of the Ag-NPs prepared in this way depended on the primary AgNO3 concentration. The prepared Ag-NPs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared. These Ag/talc-NCs may have potential applications in the chemical and biological industries.Keywords: nanocomposites, silver nanoparticles, talc, powder X-ray diffraction, scanning electron microscopy

  2. Synthesis of silver nanoparticles by using tea leaf extract from Camellia Sinensis

    Directory of Open Access Journals (Sweden)

    Loo YY

    2012-08-01

    Full Text Available Yuet Ying Loo,1 Buong Woei Chieng,2 Mitsuaki Nishibuchi,3 Son Radu11Centre of Excellent for Food Safety Research, Faculty of Food Science and Technology, Universiti Putra Malaysia, Selangor, Malaysia; 2Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia; 3Center for South East Asian Studies, Kyoto University, Kyoto, JapanAbstract: The development of the biological synthesis of nanoparticles using microorganisms or plant extracts plays an important role in the field of nanotechnology as it is environmentally friendly and does not involve any harmful chemicals. In this study, the synthesis of silver nanoparticles using the leaves extract of Chinese tea from Camellia sinensis is reported. The synthesized nanoparticles were characterized using UV-vis spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, and Fourier transform infrared (FTIR spectroscopy. The XRD analysis shows that the synthesized silver nanoparticles are of face-centered cubic structure. Well-dispersed silver nanoparticles with an approximate size of 4 nm were observed in the TEM image. The application of the green synthesized nanoparticles can be used in many fields such as cosmetics, foods, and medicine.Keywords: silver, nanoparticles, green synthesis, leaf extract, transmission electron microscopy, nanotechnology

  3. Preparation of silver-chitosan nanocomposites and coating on bandage for antibacterial wound dressing application

    Science.gov (United States)

    Susilowati, Endang; Maryani, Ashadi

    2016-02-01

    Bandage is a medical device that is essential for wound dressing. To improve the performance of the bandage, it has been coated by silver-chitosan nanocomposites (Ag/Chit) with pad-dry-cure method. The nanocomposites were performed by chemical reduction method at room temperature using glucose as reducing agent, sodium hydroxide (NaOH) as accelerator reagent, silver nitrate (AgNO3) as metal precursor and chitosan as stabilizing agent. Localized surface plasmon resonance (LSPR) absorption band of silver nanoparticles was investigated using UV-Vis spectrophotometer. The bandage coated Ag/Chit nanocomposites (B-Ag/Chit) were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). In addition, antibacterial activity of the bandage toward Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) were also studied. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 412.2 - 423.2 nm. Coating of nanocomposite cause increasing rigidity of bandage and decreasing on crystallinity. The bandages of B-Ag/Chit demonstrated good activity against both Gram positive (S. aureus) and Gram negative (E.Coli). Thus the bandages have a potential to be used for antibacterial wound dressing application.

  4. Antimicrobial Activity of Thin Solid Films of Silver Doped Hydroxyapatite Prepared by Sol-Gel Method

    Science.gov (United States)

    Iconaru, Simona Liliana; Chapon, Patrick; Le Coustumer, Philippe; Predoi, Daniela

    2014-01-01

    In this work, the preparation and characterization of silver doped hydroxyapatite thin films were reported and their antimicrobial activity was characterized. Silver doped hydroxyapatite (Ag:HAp) thin films coatings substrate was prepared on commercially pure Si disks by sol-gel method. The silver doped hydroxyapatite thin films were characterized by various techniques such as Scanning electron microscopy (SEM) with energy Dispersive X-ray attachment (X-EDS), Fourier transform infrared spectroscopy (FT-IR), and glow discharge optical emission spectroscopy (GDOES). These techniques have permitted the structural and chemical characterisation of the silver doped hydroxyapatite thin films. The antimicrobial effect of the Ag:HAp thin films on Escherichia coli and Staphylococcus aureus bacteria was then investigated. This is the first study on the antimicrobial effect of Ag:HAp thin films obtained by sol-gel method. The results of this study have shown that the Ag:HAp thin films with x Ag = 0.5 are effective against E. coli and S. aureus after 24 h. PMID:24523630

  5. Characterization of self-assembled silver pattern forming in argon and ammonia mixed atmospheric pressure plasma

    Science.gov (United States)

    Kihara, Naoya; Blanquet, Ella; Hiraoka, Yu; Sakai, Osamu

    2015-09-01

    Self-assembly fractal-like silver pattern was observed when the silver nitrate solution was dried with the gas flow of argon and ammonia mixed atmospheric plasma. This process can generate hydrazine, which is a powerful reductive agent, and silver particles are deposited from silver nitrate self-assembly and form fractal-like pattern in sub- μm order. This pattern shows abnormal optical response, so our self-assembly plasma process will be likely to bring a good method to make optical metamaterials because of its simplicity. In addition, we proposed that this process is applicable for widely sensitive metamaterials process, since we made sub- μm and several ten micrometers mingled microstructure through the plasma process with the use of micro particles. We diagnosed the characteristics of this typical pattern by Fourier transform infrared spectroscopy and numerical simulation, and confirmed that the pattern was widely sensitive from mid-infrared to far-infrared region. We aim at controlling the typical response phenomena and making widely sensitive optical metamaterials with changing deposition condition.

  6. Antibacterial Activity of Silver Nanoparticles against Staphylococcus warneri Synthesized Using Endophytic Bacteria by Photo-irradiation

    Directory of Open Access Journals (Sweden)

    Zhou-Yan Dong

    2017-06-01

    Full Text Available Diseases caused by Staphylococcus warneri have a significant impact on human health. We evaluated the antibacterial activity of silver nanoparticles (synthesized using the endophytic strain SYSU 333150 against S. warneri. The strain SYSU 333150 was isolated from the roots of Borszczowia aralocaspica Bunge. The 16S rRNA sequence results suggest that SYSU 333150 belongs to the genus Isoptericola and is likely a new species. Photo-irradiation was used to synthesize silver nanoparticles, which were characterized using UV-visible spectroscopy, transmission electron microscopy and X-ray diffraction. The nanoparticles were spherical and measured to be11 to 40 nm. X-ray diffraction revealed four peaks corresponding to the 111, 200, 220, and 311 planes of the face-centered cubic lattice, indicating a crystalline nature. Fourier transform infrared spectroscopy suggested that the metabolites in the culture supernatant were likely reducing and capping agents. The silver nanoparticles possessed antimicrobial activity (14 mm zone of inhibition against S. warneri, which was likely a result of DNA cleavage. The synthesized silver nanoparticles have potent antibacterial activity against S. warneri and can be used to control infection.

  7. Green synthesis of silver nanoparticles with antibacterial activities using aqueous Eriobotrya japonica leaf extract

    Science.gov (United States)

    Rao, Bo; Tang, Ren-Cheng

    2017-03-01

    An eco-friendly approach for the preparation of silver nanoparticles (AgNPs) from silver nitrate solution using aqueous Eriobotrya japonica leaf extract was investigated. The reduction of silver ions in solution was monitored using UV-visible absorption spectroscopy, and the surface plasmon resonance of AgNPs at 435 nm was observed. The proper condition to biosynthesize AgNPs using E. japonica leaf extract was optimized by UV-visible absorption spectroscopy and dynamic light scattering measurement (DLS). The biosynthesised nanoparticles were characterised using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), DLS, x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). XRD and EDX analyses confirmed the crystalline character of AgNPs and the presence of elemental silver. The prepared AgNPs were spherical in shape, and their average particle size determined by TEM was about 20 nm. Furthermore the AgNPs were found to exhibit effective antibacterial activities against Escherichia coli and Staphylococcus aureus.

  8. Lippia javanica: a cheap natural source for the synthesis of antibacterial silver nanocolloid

    Science.gov (United States)

    Kumar, Santosh; Singh, Mukesh; Halder, Dipankar; Mitra, Atanu

    2016-10-01

    Aqueous silver nanocolloid was synthesized in a single step by a biogenic approach using aqueous leaf extract of Lippia javanica plant which acts as both reducing as well as capping agent. The as-synthesized silver nanoparticles were characterized by UV-visible absorption spectroscopy, high-resolution transmission electron microscopy and Fourier transform infrared spectroscopy (FTIR). The UV-Vis absorption spectra of colloidal silver nanoparticles showed characteristic surface plasmon resonance peak centered at a wavelength of 415 nm. The kinetic study showed that the reduction process was complete within 2 h of time. The TEM analysis showed that most of the particles were spherical in shape and their average diameter was about 17.5 nm. FTIR study confirmed the presence of some organic functional groups in leaf extract and their participation during the reduction as well as stabilization process. In addition, the as-synthesized silver nanoparticles showed antimicrobial activity against clinically isolated pathogenic strain of E. coli and B. subtilis.

  9. Investigation of thermo-optical characteristics of the interaction processes of laser radiation with silver nanoparticles

    International Nuclear Information System (INIS)

    Pustovalov, V K; Astafyeva, L G

    2013-01-01

    Metallic nanoparticles have been actively investigated in recent years by different optical and laser methods with the purpose of their applications in optoelectronics and photonics, chemistry, laser nanobiomedicine, optical diagnostics, and other fields. A major role among metallic nanoparticles is played by nanoparticles from the noble metals (silver, gold, etc). These particles have unique plasmonic properties (resonances in the range of wavelength 400–540 nm), which can be used for the absorption, scattering and transformation of laser energy. Analysis of the thermo-optical characteristics of the interaction processes of laser radiation with silver nanoparticles is carried out, taking into account absorption, scattering and extinction of laser radiation by nanoparticles, as well as the thermo-optical and other properties of nanoparticles. Estimations are made of the influence of these nanoparticle properties on the possible results of laser radiation interaction with silver nanoparticles, including heating, heat exchange, possible melting and evaporation, and processes in the ambient media. These results can be used in laser processing of silver nanoparticles and their applications in laser nanomedicine. (paper)

  10. Antibacterial nanocarriers of resveratrol with gold and silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sohyun [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cha, Song-Hyun [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Inyoung [School of Civil, Environmental and Architecture Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Park, Soomin [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Yohan [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cho, Seonho [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Youmie, E-mail: youmiep@inje.ac.kr [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2016-01-01

    This study focused on the preparation of resveratrol nanocarrier systems and the evaluation of their in vitro antibacterial activities. Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) for resveratrol nanocarrier systems were synthesized using green synthetic routes. During the synthesis steps, resveratrol was utilized as a reducing agent to chemically reduce gold and silver ions to AuNPs and AgNPs. This system provides green and eco-friendly synthesis routes that do not involve additional chemical reducing agents. Resveratrol nanocarriers with AuNPs (Res-AuNPs) and AgNPs (Res-AgNPs) were observed to be spherical and to exhibit characteristic surface plasmon resonance at 547 nm and at 412–417 nm, respectively. The mean size of the nanoparticles ranged from 8.32 to 21.84 nm, as determined by high-resolution transmission electron microscopy. The face-centered cubic structure of the Res-AuNPs was confirmed by high-resolution X-ray diffraction. Fourier-transform infrared spectra indicated that the hydroxyl groups and C=C in the aromatic ring of resveratrol were involved in the reduction reaction. Res-AuNPs retained excellent colloidal stability during ultracentrifugation and re-dispersion, suggesting that resveratrol also played a role as a capping agent. Zeta potentials of Res-AuNPs and Res-AgNPs were in the range of − 20.58 to − 48.54 mV. Generally, against Gram-positive and Gram-negative bacteria, the Res-AuNPs and Res-AgNPs exhibited greater antibacterial activity compared to that of resveratrol alone. Among the tested strains, the highest antibacterial activity of the Res-AuNPs was observed against Streptococcus pneumoniae. The addition of sodium dodecyl sulfate during the synthesis of Res-AgNPs slightly increased their antibacterial activity. These results suggest that the newly developed resveratrol nanocarrier systems with metallic nanoparticles show potential for application as nano-antibacterial agents with enhanced activities. - Highlights

  11. Silver-hafnium braze alloy

    Science.gov (United States)

    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.

  12. Tuning Properties in Silver Clusters

    KAUST Repository

    Joshi, Chakra Prasad

    2015-07-09

    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.

  13. Biological synthesis and characterization of silver nanoparticles ...

    Indian Academy of Sciences (India)

    Biological synthesis and characterization of silver nanoparticles using. Eclipta alba leaf extract and evaluation of its cytotoxic and antimicrobial potential. PARAMASIVAM PREMASUDHA1, MUDILI VENKATARAMANA2,∗, MARRIAPPAN ABIRAMI3,. PERIYASAMY VANATHI4, KADIRVELU KRISHNA2 and RAMASAMY ...

  14. Silver Biocide Analysis & Control Device, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Rapid, accurate measurement and process control of silver ion biocide concentrations in future space missions is needed. The purpose of the Phase I program is to...

  15. Electrolytic silver ion cell sterilizes water supply

    Science.gov (United States)

    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.

  16. Large silver-cadmium technology program

    Science.gov (United States)

    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.

  17. Tartu on Eesti Boston / Silver Meikar

    Index Scriptorium Estoniae

    Meikar, Silver, 1978-

    2007-01-01

    Tartu eeldustest kujuneda hariduse, innovaatilise tootmise, pärimuskultuuri ja linnaruumi tasakaalustatud kasutamise südameks. Ettevõtluse, transpordi ja turismi arengust. Lisa: Silver Meikari Lõuna-Eesti edu top 10

  18. Anaerobic Toxicity of Cationic Silver Nanoparticles

    Data.gov (United States)

    U.S. Environmental Protection Agency — Toxicity data for the impact of nano-silver on anaerobic degradation. This dataset is associated with the following publication: Gitipour, A., S. Thiel, K. Scheckel,...

  19. Low-Temperature Properties of Silver

    Science.gov (United States)

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

    1995-01-01

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

  20. Silver behaviour in InSb

    International Nuclear Information System (INIS)

    Khlystovskaya, M.D.; Kirichenko, L.S.; Popkov, A.N.; Kiseleva, E.V.

    1976-01-01

    Specimens of InSb, alloyed with silver at concentrations of 2.4x10 14 to 1.1x10 15 cm -3 , have been obtained and investigated. The distribution of Ag along the length of ingots was studied. The effective coefficient of silver distribution in InSb was found to be equal to 5.7x10 -6 . The limit solubility of silver was evaluated by the disturbance of the smooth front of solidification and the appearance of cubstructures and second phases on polished sections, said solubility corresponds to the concentration of approximately 1x10 15 cm -3 of silver. The properties of InSb, alloyed with Ag with various degrees of compensation by residual donors and tellurium were investigated. It was found that in the p-n junction range the specific resistance of specimens rises to 2.3x10 3 Ohm.cm

  1. Silver Biocide Analysis & Control Device, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Rapid, accurate measurement and process control of silver ion biocide concentrations in future space missions is needed. The purpose of the Phase II program is to...

  2. Silver nanowires - unique templates for functional nanostructures

    Science.gov (United States)

    Sun, Yugang

    2010-09-01

    This feature article reviews the synthesis and application of silver nanowires with the focus on a polyol process that is capable of producing high quality silver nanowires with high yield. The as-synthesized silver nanowires can be used as both physical templates for the synthesis of metal/dielectric core/shell nanowires and chemical templates for the synthesis of metal nanotubes as well as semiconductor nanowires. Typical examples including Ag/SiO2 coaxial nanocables, single- and multiple-walled nanotubes made of Au-Ag alloy, AgCl nanowires and AgCl/Au core/shell nanowires are discussed in detail to illustrate the versatility of nanostructures derived from silver nanowire templates. Novel properties associated with these one-dimensional nanostructures are also briefly discussed to shed the light on their potential applications in electronics, photonics, optoelectronics, catalysis, and medicine.

  3. Alternative Plasmonic Materials: Beyond Gold and Silver

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Shalaev, Vladimir M.; Boltasseva, Alexandra

    2013-01-01

    such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent...

  4. Silver nasal sprays: misleading Internet marketing.

    Science.gov (United States)

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

    2008-04-01

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

  5. Green synthesis of silver nanoparticles using tannins

    Science.gov (United States)

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

    2014-09-01

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

  6. In situ SU-8 silver nanocomposites

    DEFF Research Database (Denmark)

    Fischer, Søren Vang; Uthuppu, Basil; Jakobsen, Mogens Havsteen

    2015-01-01

    Nanocomposite materials containing metal nanoparticles are of considerable interest in photonics and optoelectronics applications. However, device fabrication of such materials always encounters the challenge of incorporation of preformed nanoparticles into photoresist materials. As a solution...... to this problem, an easy new method of fabricating silver nanocomposites by an in situ reduction of precursors within the epoxy-based photoresist SU-8 has been developed. AgNO3 dissolved in acetonitrile and mixed with the epoxy-based photoresist SU-8 forms silver nanoparticles primarily during the pre- and post...... silver nanocomposite materials can be spin coated as homogeneous thin films and structured by using UV lithography. A resolution of 5 mu m is achieved in the lithographic process. The UV exposure time is found to be independent of the nanoparticle concentration. The fabricated silver nanocomposites...

  7. Controlling fires in silver/zinc batteries

    Science.gov (United States)

    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.

  8. Sealed Cylindrical Silver/Zinc Batteries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — RBC Technologies has significanly improved the cycle life and wet life of silver/zinc battery technology through novel separator and anode formulations. This...

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  10. An optical tweezer-based study of antimicrobial activity of silver ...

    Indian Academy of Sciences (India)

    traditional cell counting methods. Keywords. Antimicrobial activity; optical tweezer; bacterial suspensions; silver nanoparticles. 1. Introduction. The toxicity of silver ions and silver containing compounds on microbes is well known. Nanoparticles of silver are expected to exhibit enhanced antimicrobial properties when.

  11. Characterization of engineered nanoparticles in commercially available spray disinfectant products advertised to contain colloidal silver

    Science.gov (United States)

    Given the potential for human exposure to silver nanoparticles from spray disinfectants and dietary supplements, we characterized the silver-containing nanoparticles in 22 commercial products that advertised the use of silver or colloidal silver as the active ingredient. Characte...

  12. Neutron scattering and models: Silver

    International Nuclear Information System (INIS)

    Smith, A.B.

    1996-07-01

    Differential neutron elastic-scattering cross sections of elemental silver were measured from 1.5 → 10 MeV at ∼ 100 keV intervals up to 3 MeV, at ∼ 200 keV intervals from 3 → 4 MeV, and at ∼ 500 keV intervals above 4 MeV. At ≤ 4 MeV the angular range of the measurements was ∼ 20 0 → 160 0 with 10 measured values below 3 MeV and 20 from 3 → 4 MeV at each incident energy. Above 4 MeV ≥ 40 scattering angles were used distributed between ∼ 17 0 and 16 0 All of the measured elastic distributions included some contributions due to inelastic scattering. Below 4 MeV the measurements determined cross sections for ten inelastically-scattered neutron groups corresponding to observed excitations of 328 ± 13, 419 ± 50, 748 ± 25, 908 ± 26, 115 ± 38, 1286 ± 25, 1507 ± 20, 1632 ± 30, 1835 ± 20 and 1944 ± 26 keV. All of these inelastic groups probably were composites of contributions from the two isotopes 107 Ag and 109 Ag. The experimental results were interpreted in terms of the spherical optical model and of rotational and vibrational coupled-channels models, and physical implications are discussed. In particular, the neutron-scattering results are consistent with a ground-state rotational band with a quadrupole deformation Β 2 = 0.20 ± ∼ 10% for both of the naturally-occurring silver isotopes

  13. Thermally induced morphological transition of silver fractals

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Solov'yov, Andrey; Kébaili, Nouari

    2014-01-01

    We present both experimental and theoretical study of thermally induced morphological transition of silver nanofractals. Experimentally, those nanofractals formed from deposition and diffusion of preformed silver clusters on cleaved graphite surfaces exhibit dendritic morphologies that are highly...... sensitive to any perturbation, particularly caused by temperature. We analyze and characterize the morphological transition both in time and temperature using the recently developed Monte Carlo simulation approach for the description of nanofractal dynamics and compare the obtained results...

  14. Electrocatalytic activity of bismuth doped silver electrodes

    CERN Document Server

    Amjad, M

    2002-01-01

    Investigation of redox reactions on silver, and bismuth doped silver electrodes in aqueous KOH solutions, by using potentiostatic steady-state polarization technique, has been carried out. The redox wave potential and current displacements along with multiplicity of the latter have been examined. These electrodes were employed for the oxidation of organic molecules such as ethylamine in alkaline media. Subsequently, these electrodes were ranked with respect to their activity for the redox reactions. (author)

  15. Pharmacological Properties of Nanometals (Silver, Copper, Iron

    Directory of Open Access Journals (Sweden)

    Chekman, I.S.

    2015-01-01

    Full Text Available The article summarizes the results of studies on the pharmacological, toxicological and specific properties of nanometals (silver, iron, copper. It is established that nanoparticles of silver, copper, iron exhibit antimicrobial action. Acute toxicity of nanometals depends on their nature, administration route and animal sex. Effects on heart activity and hemodynamic status as well as erythrocyte osmotic fragility have dose-dependent nature.

  16. Gold and Silver Extraction from Leach Solutions

    Directory of Open Access Journals (Sweden)

    Bagdaulet K. Kenzhaliyev

    2014-03-01

    Full Text Available There has been carried out an investigation on the extraction of gold and silver from thiosulfate solutions: standard test and technological solutions of chemical and electrochemical leaching. The influence of related metals on the process of extracting gold from solution was studied. There has been conducted a comparative study of the IR spectra of solutions after the sorption of gold, silver and related metals.

  17. Biosynthesis of silver nanoparticles using Stevia extracts

    International Nuclear Information System (INIS)

    Laguta, I.V.; Fesenko, T.V.; Stavinskaya, O.N.; Shpak, L.M.; Dzyuba, O.I.

    2015-01-01

    Silver nanoparticles are synthesized using Stevia rebaudiana extracts. It is shown that the rate of nanoparticles formation is affected by plant cultivation conditions. It is found that, in the presence of the extract from callus, the formation of nanoparticles occurs faster than in the presence of extracts from plants grown under conditions of ex situ and in vitro. The synthesized silver nanoparticles were studied by UV and IR spectroscopies

  18. Engineered Escherichia coli silver-binding periplasmic protein that promotes silver tolerance.

    Science.gov (United States)

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

    2012-04-01

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

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

    Science.gov (United States)

    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.

  20. Microwave-assisted green synthesis of silver nanoparticles from Fraxinus excelsior leaf extract and its antioxidant assay

    Science.gov (United States)

    Parveen, Mehtab; Ahmad, Faheem; Malla, Ali Mohammed; Azaz, Shaista

    2016-02-01

    The biosynthesis of nanoparticles has been proposed as a cost effective and environmentally benevolent alternative to chemical and physical methods. In the present study, microwave assisted synthesis of silver nanoparticles (AgNPs) has been demonstrated using leaf extract of Fraxinus excelsior reducing aqueous AgNO3 solution. The synthesized nanoparticles have been characterized on the basis of fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis. The presence of a characteristic surface plasmon resonance (SPR) absorption band at 425 nm in UV-Vis reveals the reduction of silver metal ions into silver nanoparticles. FT-IR analysis was carried out to probe the possible functional group involved in the synthesis of AgNPs. Further leaf extracts and AgNPs were evaluated for antiradical scavenging activity by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay.

  1. Activity of Antimicrobial Silver Polystyrene Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Palomba

    2012-01-01

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

  2. Towards conducting inks: Polypyrrole–silver colloids

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  3. Metastable fragmentation of silver bromide clusters

    International Nuclear Information System (INIS)

    L'Hermite, J.M.; Rabilloud, F.; Marcou, L.; Labastie, P.

    2001-01-01

    The abundance spectra and the fragmentation channels of silver bromide clusters have been measured and analyzed. The most abundant species are Ag n Br n - 1 + and Ag n Br n + 1 - and Ag 14 Br 13 + is a magic number, revealing their ionic nature. However, some features depart from what is generally observed for alkali-halide ionic clusters. From a certain size, Ag n Br n - 1 + is no more the main series, and Ag n Br n - 2, 3 + series become almost as important. The fast fragmentation induced by a UV laser makes the cations lose more bromine than silver ions and lead to more silver-rich clusters. Negative ions mass spectra contain also species with more silver atoms than required by stoichiometry. We have investigated the metastable fragmentation of the cations using a new experimental method. The large majority of the cations release mainly a neutral Ag 3 Br 3 cluster. These decay channels are in full agreement with our recent ab initio DFT calculations, which show that Ag + -Ag + repulsion is reduced due to a globally attractive interaction of their d orbitals. This effect leads to a particularly stable trimer (AgBr) 3 and to quasi-planar cyclic structures of (AgBr) n clusters up to n = 6. We have shown that these two features may be extended to other silver halides, to silver hydroxides (AgOH) n , and to cuprous halide compounds. (orig.)

  4. Silver as antibacterial towards Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Simone eBelluco

    2016-03-01

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

  5. The Bargmann transform and canonical transformations

    International Nuclear Information System (INIS)

    Villegas-Blas, Carlos

    2002-01-01

    This paper concerns a relationship between the kernel of the Bargmann transform and the corresponding canonical transformation. We study this fact for a Bargmann transform introduced by Thomas and Wassell [J. Math. Phys. 36, 5480-5505 (1995)]--when the configuration space is the two-sphere S 2 and for a Bargmann transform that we introduce for the three-sphere S 3 . It is shown that the kernel of the Bargmann transform is a power series in a function which is a generating function of the corresponding canonical transformation (a classical analog of the Bargmann transform). We show in each case that our canonical transformation is a composition of two other canonical transformations involving the complex null quadric in C 3 or C 4 . We also describe quantizations of those two other canonical transformations by dealing with spaces of holomorphic functions on the aforementioned null quadrics. Some of these quantizations have been studied by Bargmann and Todorov [J. Math. Phys. 18, 1141-1148 (1977)] and the other quantizations are related to the work of Guillemin [Integ. Eq. Operator Theory 7, 145-205 (1984)]. Since suitable infinite linear combinations of powers of the generating functions are coherent states for L 2 (S 2 ) or L 2 (S 3 ), we show finally that the studied Bargmann transforms are actually coherent states transforms

  6. Analysis of impurities in silver matrix by atomic absorption spectrophotometry

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  7. Silver as antibacterial agent: ion, nanoparticle, and metal.

    Science.gov (United States)

    Chernousova, Svitlana; Epple, Matthias

    2013-02-04

    The antibacterial action of silver is utilized in numerous consumer products and medical devices. Metallic silver, silver salts, and also silver nanoparticles are used for this purpose. The state of research on the effect of silver on bacteria, cells, and higher organisms is summarized. It can be concluded that the therapeutic window for silver is narrower than often assumed. However, the risks for humans and the environment are probably limited. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Light-induced reduction of silver ions to silver nanoparticles in aquatic environments by microbial extracellular polymeric substances (EPS).

    Science.gov (United States)

    Zhang, Xin; Yang, Chuan-Wang; Yu, Han-Qing; Sheng, Guo-Ping

    2016-12-01

    Microbial extracellular polymeric substances (EPS) widely exist in natural environments and affect the migration and transformation of pollutants in aquatic environments. Previous works report that EPS have some reducing functional groups and can reduce heavy metals. However, because of the weak reducing capability of EPS, the reduction of heavy metals by EPS without cells is extremely slow, and its effect on heavy metals species is insignificant. In this work, the accelerated reduction of silver ions (Ag + ) by EPS from Shewanella oneidensis MR-1 under illumination was investigated. UV-visible spectroscopy, transmission electron microscopy (TEM) coupled with an energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) were used to confirm the formation of silver nanoparticles (AgNPs) via the reduction of Ag + by EPS under light illumination. The Ag + reduction by EPS follows pseudo-first-order kinetics under both visible and UV light, and the light irradiation can significantly accelerate AgNPs formation. On the one hand, visible light can excite AgNPs for their surface plasma resonance (SPR) and accelerate the electrons from the EPS to adjacent Ag + . On the other hand, EPS molecules may be excited by UV light to produce strong reducing species, which enhance Ag + reduction. Moreover, pH, dissolved oxygen were found to affect the formation of AgNPs by EPS. This work proves the reducing capability of EPS on the reduction of Ag + , and this process can be accelerated under light illumination, which may affect the speciation and transformation of heavy metals in natural waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    NARCIS (Netherlands)

    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

  10. A silver tattoo of the nasal mucosa after silver nitrate cautery.

    Science.gov (United States)

    Mayall, F; Wild, D

    1996-06-01

    We report a silver tattoo of the nasal mucosa that occurred after silver nitrate cautery for nasal bleeding. This type of tattoo is a very rare potential mimic of melanoma and appears not to have been described before. It has similar features to an amalgam tattoo of the oral mucosa on histology and energy dispersive X-ray analysis (EDAX).

  11. Ultrastructural localization of silver in rat testis and organ distribution of radioactive silver in the rat

    DEFF Research Database (Denmark)

    Ernst, E; Rungby, J; Baatrup, E

    1992-01-01

    The deposition of silver after a single intravenous injection (2 micrograms Ag g-1 body weight) was studied in the testes of Wistar rats 24 h and 1 and 2 weeks after dosing with radiolabelled 110AgNo3 (2 micrograms Ag and 1.2 kBq g-1 body weight). Also, the temporal accumulation of silver during...

  12. Silver behenate and silver stearate powders for calibration of SAS instruments

    Czech Academy of Sciences Publication Activity Database

    Nyam-Osor, M.; Soloviov, D. V.; Kovalev, Yu. S.; Zhigunov, Alexander; Rogachev, A. V.; Ivankov, O. I.; Erhan, R. V.; Kuklin, A. I.

    2012-01-01

    Roč. 351, č. 1 (2012), 012024_1-012024_9 ISSN 1742-6588. [SANS-YuMO User Meeting. Dubna, 27.05.2011-30.05.2011] Institutional research plan: CEZ:AV0Z40500505 Keywords : silver behenate * silver stearate * SAS Subject RIV: CD - Macromolecular Chemistry

  13. Surface Structure of Silver Nanoparticles as a Model for Understanding the Oxidative Dissolution of Silver Ions

    NARCIS (Netherlands)

    Molleman, Bastiaan; Hiemstra, Tjisse

    2015-01-01

    The toxicity of silver nanoparticles (AgNPs) has been related to the release of ionic silver. This process is influenced by a large variety of factors and is poorly understood. The key to understanding Ag+ release by AgNPs is its subvalency. This is a fundamental property of Ag that

  14. Generalized Fourier transforms classes

    DEFF Research Database (Denmark)

    Berntsen, Svend; Møller, Steen

    2002-01-01

    The Fourier class of integral transforms with kernels $B(\\omega r)$ has by definition inverse transforms with kernel $B(-\\omega r)$. The space of such transforms is explicitly constructed. A slightly more general class of generalized Fourier transforms are introduced. From the general theory foll...... follows that integral transform with kernels which are products of a Bessel and a Hankel function or which is of a certain general hypergeometric type have inverse transforms of the same structure....

  15. Synthesis of silver nanoparticles using Nelumbo nucifera leaf extract and its larvicidal activity against malaria and filariasis vectors.

    Science.gov (United States)

    Santhoshkumar, Thirunavukkarasu; Rahuman, Abdul Abdul; Rajakumar, Govindasamy; Marimuthu, Sampath; Bagavan, Asokan; Jayaseelan, Chidambaram; Zahir, Abdul Abduz; Elango, Gandhi; Kamaraj, Chinnaperumal

    2011-03-01

    The aim of this study was to investigate the larvicidal potential of the hexane, chloroform, ethyl acetate, acetone, methanol, and aqueous leaf extracts of Nelumbo nucifera Gaertn. (Nymphaeaceae) and synthesized silver nanoparticles using aqueous leaf extract against fourth instar larvae of Anopheles subpictus Grassi and Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. The results recorded from UV-vis spectrum, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared support the biosynthesis and characterization of silver nanoparticles. Larvae were exposed to varying concentrations of plant extracts and synthesized silver nanoparticles for 24 h. All extracts showed moderate larvicidal effects; however, the maximum efficacy was observed in crude methanol, aqueous, and synthesized silver nanoparticles against the larvae of A. subpictus (LC(50) = 8.89, 11.82, and 0.69 ppm; LC(90) = 28.65, 36.06, and 2.15 ppm) and against the larvae of C. quinquefasciatus (LC(50) = 9.51, 13.65, and 1.10 ppm; LC(90) = 28.13, 35.83, and 3.59 ppm), respectively. These results suggest that the leaf methanol, aqueous extracts of N. nucifera, and green synthesis of silver nanoparticles have the potential to be used as an ideal eco-friendly approach for the control of the A. subpictus and C. quinquefasciatus. This is the first report on the mosquito larvicidal activity of the plant extracts and synthesized nanoparticles.

  16. “Synthesis, characterization and studies on antioxidant activity of silver nanoparticles using Elephantopus scaber leaf extract”

    Energy Technology Data Exchange (ETDEWEB)

    Kharat, Sopan N., E-mail: sopankharat@gmail.com; Mendhulkar, Vijay D., E-mail: drmendhulkar@gmail.com

    2016-05-01

    The simple, eco-friendly and cost effective method of green synthesis of silver nanoparticle in the leaf extract of medicinal plant Elephantopus scaber L. is illustrated in the present work. The synthesized silver nanoparticles (AgNPs) were characterized with UV–Vis-spectroscopy, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The UV-spectra show maximum absorbance at 435 nm, NTA analysis shows 78 nm average sizes of nanoparticles, TEM analysis indicates spherical shape of the nanoparticles with the average diameter of 50 nm. The XRD peaks at 2θ range of 30–80° correspond to (111), (200), (220), (311) reflection planes that indicate the structure of metallic silver. FTIR analysis reveals surface capping of phenolic groups. Existence of peaks in the range of 1611 to 1400 cm{sup −1} indicates the presence of aromatic rings in the leaf extract. The peak at 1109 cm{sup −1} is due to the presence of OH groups. The antioxidant activity of synthesized nanoparticles was evaluated performing DPPH assay and it is observed that the photosynthesized nanoparticle also possesses antioxidant potentials. Thus, it can be used as potential free radical scavenger. Silver particles have tremendous applications in the field of diagnostics and therapeutics. To this context, the surface coating of plant metabolite constituents has great potentials. Therefore, the present work has been undertaken to synthesize the AgNPs using leaf extract of medicinal plant, E. scaber, to characterize and access their antioxidant properties. - Highlights: • Green synthesis of silver nanoparticle using leaf extract of medicinal plant Elephantopus scaber L. • Synthesized nanoparticles (SNP's) were characterized by UV-Spectroscopy, NTA, TEM, XRD and FTIR analysis. • Silver nanoparticles (AgNPs) showed average size of 78 nm in NTA analysis and spherical shape in TEM analysis.

  17. A study on the stability and green synthesis of silver nanoparticles using Ziziphora tenuior (Zt) extract at room temperature

    Science.gov (United States)

    Sadeghi, Babak; Gholamhoseinpoor, F.

    2015-01-01

    Biomolecules present in plant extracts can be used to reduce metal ions to nanoparticles in a single-step green synthesis process. This biogenic reduction of metal ion to base metal is quite rapid, readily conducted at room temperature and pressure, and easily scaled up. Mediated Synthesis by plant extracts is environmentally benign. The involved reducing agents include the various water soluble plant metabolites (e.g. alkaloids, phenolic compounds, terpenoids) and co-enzymes. Silver (Ag) nanoparticles have the particular focus of plant-based syntheses. Extracts of a diverse range of Ziziphora tenuior (Zt) have been successfully used in making nanoparticles. The aim of this study was to investigate the antioxidant properties of this plant and its ability to synthesize silver nanoparticles. Z.tenuior leaves were used to prepare the aqueous extract for this study. Silver nanoparticles were characterized with different techniques such as UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Transmission electron microscopy experiments showed that these nanoparticles are spherical and uniformly distributed and its size is from 8 to 40 nm. FT-IR spectroscopy revealed that silver nanoparticles were functionalized with biomolecules that have primary amine group (sbnd NH2), carbonyl group, sbnd OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of silver nanoparticles with size of 38 nm. In addition to plant extracts, live plants can be used for the synthesis. Here were view the methods of making nanoparticles using plant extracts. The scanning electron microscopy (SEM) implies the right of forming silver nanoparticles. The results of TEM, SEM, FT-IR, UV-VIS and XRD confirm that the leaves extract of Zt can synthesis silver nanoparticles.

  18. Synthesis and characterization of silver doped hydroxyapatite nanocomposite coatings and evaluation of their antibacterial and corrosion resistance properties in simulated body fluid.

    Science.gov (United States)

    Mirzaee, Majid; Vaezi, Mohammadreza; Palizdar, Yahya

    2016-12-01

    Silver-doped hydroxyapatite (Ca10-xAgx(PO4)6(OH)2-x) films were synthesized and deposited on anodized titanium (Ti) using electrophoretic. The influence of different silver-dopant contents (X=0, 0.02, 0.05, 0.08 and 0.1) on the phase formation and microstructure of the powders were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), and Fourier transform infrared spectrum analysis (FT-IR). XRD analysis confirmed the formation of Hexagonal structure of hydroxyapatite (HAp) annealed at 600°C with a small shift in the major peak position toward lower angles with adding silver. FT-IR spectroscopy disclosed the presence of the different vibrational modes matching to phosphates and hydroxyl groups and the absence of any band characteristics to silver. XPS analysis showed that 75% and 23% of silver was in the chemical states of Ag(2+) and Ag(+), respectively. However, only about 2% of silver was in the Ag(0) state, resulting in the high quality of nanocomposite films. The anodization treatment improves the bond strength between the Ag doped HAp deposited layers on TiO2. HAp and silver doped HAp (X=0.05) are regarded to be hydrophilic due to a large number of -OH groups on the surface. The sample with content of silver (x=0.05) also showed excellent antimicrobial efficacy (>99% reduction in viable cells). Electrochemical reveals the passive current densities of the HAp coated anodized Ti are lower than those of silver doped HAp coated anodized Ti, leading to a slightly lower corrosion resistance. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Bioactive compound loaded stable silver nanoparticle synthesis from microwave irradiated aqueous extracellular leaf extracts of Naringi crenulata and its wound healing activity in experimental rat model.

    Science.gov (United States)

    Bhuvaneswari, T; Thiyagarajan, M; Geetha, N; Venkatachalam, P

    2014-07-01

    An efficient and eco-friendly protocol for the synthesis of bioactive silver nanoparticles was developed using Naringi crenulata leaf extracts via microwave irradiation method. Silver nanoparticles were synthesized by treating N. crenulata leaf extracts with 1mM of aqueous silver nitrate solution. An effective bioactive compound such as alkaloids, phenols, saponins and quinines present in the N. crenulata reduces the Ag(+) into Ag(0). The synthesized silver nanoparticles were monitored by UV-vis spectrophotometer and further characterized by X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM). UV-vis spectroscopy showed maximum absorbance at 390nm due to surface plasmon resonance of AgNPs. From FESEM results, an average crystal size of the synthesized nanoparticle was 72-98nm. FT-IR results showed sharp absorption peaks and they were assigned to phosphine, alkyl halides and sulfonate groups. Silver nanoparticles synthesized were generally found to be spherical and cubic shape. Topical application of ointment prepared from silver nanoparticles of N. crenulata were formulated and evaluated in vivo using the excision wound healing model on Wistar albino rats. The measurement of the wound areas was performed on 3rd, 6th, 9th, 12th and 15th days and the percentage of wound closures was calculated accordingly. By the 15th day, the ointment base containing 5% (w/w) of silver nanoparticles showed 100% wound healing activity compared with that of the reference as well as control bases. The results strongly suggested that the batch C ointment containing silver nanaoparticles synthesized from the leaf extracts of N. crenulata was found to be very effective in wound repair and encourages harnessing the potentials of the plant biomolecules loaded silver nanoparticle in the treatment of tropical diseases including wound healing. Copyright © 2014 Elsevier B.V. All rights

  20. Synthesis and characterization of silver/alanine nanocomposites for radiation detection in medical applications: the influence of particle size on the detection properties.

    Science.gov (United States)

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

    2012-04-28

    Silver/alanine nanocomposites with varying mass percentage of silver have been produced. The size of the silver nanoparticles seems to drive the formation of the nanocomposite, yielding a homogeneous dispersion of the silver nanoparticles in the alanine matrix or flocs of silver nanoparticles segregated from the alanine crystals. The alanine crystalline orientation is modified according to the particle size of the silver nanoparticles. Concerning a mass percentage of silver below 0.1%, the nanocomposites are homogeneous, and there is no particle aggregation. As the mass percentage of silver is increased, the system becomes unstable, and there is particle flocculation with subsequent segregation of the alanine crystals. The nanocomposites have been analyzed by transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy and they have been tested as radiation detectors by means of electron spin resonance (ESR) spectroscopy in order to detect the paramagnetic centers created by the radiation. In fact, the sensitivity of the radiation detectors is optimized in the case of systems containing small particles (30 nm) that are well dispersed in the alanine matrix. As the agglomeration increases, particle growth (up to 1.5 μm) and segregation diminish the sensitivity. In conclusion, nanostructured materials can be used for optimization of alanine sensitivity, by taking into account the influence of the particles size of the silver nanoparticles on the detection properties of the alanine radiation detectors, thus contributing to the construction of small-sized detectors. This journal is © The Royal Society of Chemistry 2012

  1. Army Maintenance System Transformation

    National Research Council Canada - National Science Library

    Gilbertson, Frank V

    2006-01-01

    .... Used in conjunction with pertinent historical data and developed with Army transformation goals in mind, General Systems thinking can provide the framework for guiding maintenance transformation...

  2. Encapsulated Silver Nanoparticles Can Be Directly Converted to Silver Nanoshell in the Gas Phase.

    Science.gov (United States)

    Yang, Peipei; Xu, Yong; Chen, Lei; Wang, Xuchun; Mao, Baohua; Xie, Zhongzhi; Wang, Sui-Dong; Bao, Feng; Zhang, Qiao

    2015-12-09

    We report, for the first time, that an encapsulated silver nanoparticle can be directly converted to a silver nanoshell through a nanoscale localized oxidation and reduction process in the gas phase. Silver can be etched when exposed to a mixture of NH3/O2 gases through a mechanism analogous to the formation of aqueous Tollens' reagent, in which a soluble silver-ammonia complex was formed. Starting with Ag@resorcinol-formaldehyde (RF) resin core-shell nanoparticles, we demonstrate that RF-core@Ag-shell nanoparticles can be prepared successfully when the etching rate and RF thickness were well controlled. Due to the strong surface plasmon resonance (SPR) coupling effect among neighboring silver nanoparticles, the RF@Ag nanoparticle showed great SPR and SERS performance. This process provides a general route to the conversion of Ag-core to Ag-shell nanostructures and might be extended to other systems.

  3. Biologically synthesised silver nanoparticles from three diverse family of plant extracts and their anticancer activity against epidermoid A431 carcinoma.

    Science.gov (United States)

    Nayak, Debasis; Pradhan, Sonali; Ashe, Sarbani; Rauta, Pradipta Ranjan; Nayak, Bismita

    2015-11-01

    Biological synthesis of silver nanoparticles is a cost effective natural process where the phytochemicals specifically phenols, flavonoids and terpenoids present in the plant extracts act as capping and reducing agent. Due to their nano size regime the silver nanoparticles may directly bind to the DNA of the pathogenic bacterial strains leading to higher antimicrobial activity. In the current study silver nanoparticles were synthesised using plant extracts from different origin Cucurbita maxima (petals), Moringa oleifera (leaves) and Acorus calamus (rhizome). The synthesised nanoparticles were characterized by UV-visible spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), field emission scanning electron microscopy (Fe-SEM) and Fourier transform infrared spectroscopy (FTIR). Highly crystalline, roughly spherical and cuboidal silver nanoparticles of 30-70 nm in size were synthesised. The nanoparticles provided strong antimicrobial activity against pathogenic strains. The effect of the synthesised nanoparticles against A431 skin cancer cell line was tested for their toxicity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. The IC50 values of 82.39±3.1, 83.57±3.9 and 78.58±2.7 μg/ml were calculated for silver nanoparticles synthesised by C. maxima, M. oleifera and A. calamus respectively. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. The shape conversion of silver nanoparticles through heating and its application as homogeneous catalyst in reduction of 4- nitrophenol

    Science.gov (United States)

    Ariyanta, H. A.; Yulizar, Y.

    2016-02-01

    The shape conversion of silver nanoparticles (AgNPs) through heating and its application as a homogeneous catalyst in the reduction of 4-nitrophenol is reported here. Synthesis of AgNPs by reduction of AgNO3 using NaBH4 and sodium citrate as reducing agent were successfully conducted. The addition of PVP was used as stabilizing agent. The synthesized AgNPs were heated at 95 °C and observed using UV-Vis spectrophotometer, transmission electron microscopy (TEM), Fourier-transformed infrared (FTIR) spectroscopy and particle size analyzer (PSA). Characteristics of AgNPs before heated were blue with UV- Vis absorbance spectrum at λmax = 786 nm and the shape was pseudo nano prism sized ± 28 nm. During the heating process, the color changed gradually from blue (λmax = 786 nm) to orange (λmax = 486 nm) and also its shape from nano prism to nanodisk. Silver nano prism has a lattice constant, 4.160 Å, larger than the silver nanodisk, 4.081 Å, which was possibly achieved through rearrangement of silver atoms on the surface of AgNPs. Both silver nanodisk and nano prism were tested as a homogeneous catalyst for the reduction of 4-nitrophenol (4- NP) with NaBH4.

  5. Biofabrication, characterization and antibacterial efficacy of extracellular silver nanoparticles using novel fungal strain of Penicillium atramentosum KM

    Directory of Open Access Journals (Sweden)

    Vikas Sarsar

    2015-11-01

    Full Text Available The biofabricated silver nanoparticles are extensively used in environmental, biotechnological and biomedical applications. The synthesis of SNPs has been carried out by using the filtrate extract of novel fungal strain Penicillium atramentosum KM. To undertake this study, P. atramentosum KM extract was exposed to silver nitrate and the obtained SNPs were thoroughly analyzed using physicochemical characterization tools such as UV–visible spectroscopy (UV–vis, Fourier transformation infrared (FTIR, X-ray diffraction (XRD and transmission electron microscopy (TEM. As evident from the FTIR spectra plausibly the protein components of fungal extract caused the reduction of silver nitrate. The SNPs showed a characteristic UV–visible peak at 420 nm with an average size of 5–25 nm. The XRD record exhibited the characteristic peaks of 111, 200, 220 and 311 nanoparticles signifying that these nanoparticles were crystalline in nature. Parametric optimization showed maximum absorbance of 420 nm at pH 7, 25 °C with 3 mM silver nitrate, concentration ratio of fungal extract and silver nitrate was 5:5 in 72 h. The synthesized SNPs showed antimicrobial activity against bacterial strains.

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

    Science.gov (United States)

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

    2013-01-01

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

  7. Synthesis of silver nanoparticles through green approach using Dioscorea alata and their characterization on antibacterial activities and optical limiting behavior.

    Science.gov (United States)

    Pugazhendhi, S; Sathya, P; Palanisamy, P K; Gopalakrishnan, R

    2016-06-01

    In this work, we have successfully synthesized highly biocompatible and functionalized Dioscorea alata (D. alata) mediated silver nanoparticles with different quantities of its extract for the evaluation of proficient bactericidal activity and optical limiting behavior. The crystalline nature of the synthesized silver nanoparticles was confirmed by powder X-ray powder diffraction (XRD) analysis and furthermore confirmed from SAED pattern of HRTEM Analysis. The Surface Plasmon Resonance band was measured and monitored by UV-Visible spectral studies. The functional groups present in the extract for the reduction and stabilization of the nanoparticles were analyzed by Fourier transform infrared spectroscopy (FTIR) technique. Surface morphology and size of particles were determined by high-resolution transmission electron microscopy analysis (HRTEM). The elemental analysis was made by Energy Dispersive X-ray Spectroscopy (EDX). The synthesized silver nanoparticles (AgNPs) in colloidal form were found to exhibit third order optical nonlinearity as studied by closed aperture Z-scan technique and open aperture technique using 532nm Nd:YAG (SHG) CW laser beam (COHERENT-Compass 215M-50 diode-pumped) output as source. The negative nonlinearity observed was well utilized for the study of optical limiting behavior of the silver nanoparticles. D. alata mediated silver nanoparticles possess very good antimicrobial activity which was confirmed by agar well diffusion assay method. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-30

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

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

    International Nuclear Information System (INIS)

    Wolter, D.

    1974-01-01

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

  10. Silver nanoparticles from silver halide photography to plasmonics

    CERN Document Server

    Tani, Tadaaki

    2015-01-01

    This book provides systematic knowledge and ideas on nanoparticles of Ag and related materials. While Ag and metal nanoparticles are essential for plasmonics, silver halide (AgX) photography relies to a great extent on nanoparticles of Ag and AgX which have the same crystal structure and have been studied extensively for many years. This book has been written to combine the knowledge of nanoparticles of Ag and related materials in plasmonics and AgX photography in order to provide new ideas for metal nanoparticles in plasmonics. Chapters 1–3 of this book describe the structure and formation of nanoparticles of Ag and related materials. Systematic descriptions of the structure and preparation of Ag, Au, and noble-metal nanoparticles for plasmonics are followed by and related to those of nanoparticles of Ag and AgX in AgX photography. Knowledge of the structure and preparation of Ag and AgX nanoparticles in photography covers nanoparticles with widely varying sizes, shapes, and structures, and formation proce...

  11. Silver diffusion and isotope effect in silver rubidium iodide

    International Nuclear Information System (INIS)

    Arzigian, J.S.

    1980-01-01

    The diffusion coefficient of silver in RbAg 4 I 5 was measured in both superionic phases using radiotracer Ag-110m and serial sectioning with a low temperature sectioning apparatus. The activation energies for diffusion in alpha-RbAg 4 I 5 and beta-RbAg 4 I 5 , respectively, are 0.11 +- 0.01 eV and 0.20 +- 0.04 eV. An isotope effect for diffusion was also measured in both superionic phases. Ag-105 and Ag-110m radioisotopes were used with gamma spectroscopy and energy discrimination. The effect is small, with no significant temperature variation, with the value at 333 0 K being 0.12 +- 0.01. The second-order phase transition at 208 0 K has a small effect, if any, on the magnitude of the effect. The data suggest that a highly cooperative transport mechanism is responsible for the unusually high values of both the conductivity and diffusion coefficient. Although it is not possible to deduce the particular mechanism involved, theories inolving ionic polarons, or cooperative motion, such as crowdions or solitons, seem consistent with the observed results

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-15

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

  14. Green synthesis of silver nanoparticles by Chrysanthemum morifolium Ramat. extract and their application in clinical ultrasound gel.

    Science.gov (United States)

    He, Yan; Du, Zhiyun; Lv, Huibin; Jia, Qianfa; Tang, Zhikai; Zheng, Xi; Zhang, Kun; Zhao, Fenghua

    2013-01-01

    Eco-friendly green synthesis with plant extracts plays a very important role in nanotechnology, without any harmful chemicals. In this report, the synthesis of water-soluble silver nanoparticles was developed by treating silver ions with Chrysanthemum morifolium Ramat. extract at room temperature. The effect of the extract on the formation of silver nanoparticles was characterized by ultraviolet and visible absorption spectroscopy, X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The ultraviolet and visible absorption spectroscopy results show a strong resonance centered on the surface of silver nanoparticles (AgNP) at 430 nm. The Fourier transform infrared spectroscopy spectral study demonstrates Chrysanthemum morifolium Ramat. extract acted as the reducing and stabilizing agent during the synthesis. The X-ray diffraction analysis confirmed that the synthesized AgNP are single crystallines, corresponding with the result of transmission electron microscopy. Water-soluble AgNP, with an approximate size of 20 nm-50 nm were also observed in the transmission electron microscopy image. The bactericidal properties of the synthesized AgNP were investigated using the agar-dilution method and the growth-inhibition test. The results show the AgNP had potent bactericidal activity on Staphylococcus aureus and Escherichia coli, as well as a strong antibacterial activity against gram-negative bacteria, as compared to gram-positive bacteria with a dose-dependent effect, thus providing a clinical ultrasound gel with bactericidal property for prevention of cross infections.

  15. Green synthesis of silver nanoparticles using Delphinium denudatum root extract exhibits antibacterial and mosquito larvicidal activities

    Science.gov (United States)

    Suresh, Gopal; Gunasekar, Poosali Hariharan; Kokila, Dhanasegaran; Prabhu, Durai; Dinesh, Devadoss; Ravichandran, Nagaiya; Ramesh, Balasubramanian; Koodalingam, Arunagirinathan; Vijaiyan Siva, Ganesan

    2014-06-01

    Green synthesis of silver nanoparticles (AgNPs) using aqueous root extract of Delphinium denudatum (Dd) by reduction of Ag+ ions from silver nitrate solution has been investigated. The synthesized DdAgNPs were characterized by using UV-Vis spectroscopy, X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). The prepared DdAgNPs showed maximum absorbance at 416 nm and particles were polydispersed in nature, spherical in shape and the size of the particle obtained was ⩽85 nm. The DdAgNPs exhibited antibacterial activity against Staphylococcus aureus ATCC 6538, Bacillus cereus NCIM 2106, Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027. The DdAgNPs showed potent larvicidal activity against second instar larvae of dengue vector Aedes aegypti with a LC50 value of 9.6 ppm.

  16. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition.

    Science.gov (United States)

    Boies, Adam M; Roberts, Jeffrey T; Girshick, Steven L; Zhang, Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO2) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 degrees C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10(7) particles cm(-3).

  17. Biocomposites of nanofibrillated cellulose, polypyrrole, and silver nanoparticles with electroconductive and antimicrobial properties.

    Science.gov (United States)

    Bober, Patrycja; Liu, Jun; Mikkonen, Kirsi S; Ihalainen, Petri; Pesonen, Markus; Plumed-Ferrer, Carme; von Wright, Atte; Lindfors, Tom; Xu, Chunlin; Latonen, Rose-Marie

    2014-10-13

    In this work, flexible and free-standing composite films of nanofibrillated cellulose/polypyrrole (NFC/PPy) and NFC/PPy-silver nanoparticles (NFC/PPy-Ag) have been synthesized for the first time via in situ one-step chemical polymerization and applied in potential biomedical applications. Incorporation of NFC into PPy significantly improved its film formation ability resulting in composite materials with good mechanical and electrical properties. It is shown that the NFC/PPy-Ag composite films have strong inhibition effect against the growth of Gram-positive bacteria, e.g., Staphylococcus aureus. The electrical conductivity and strong antimicrobial activity makes it possible to use the silver composites in various applications aimed at biomedical treatments and diagnostics. Additionally, we report here the structural and morphological characterization of the composite materials with Fourier-transform infrared spectroscopy, atomic force microscopy, and scanning and transmission electron microscopy techniques.

  18. PVP-coated silver nanoparticles showing antifungal improved activity against dermatophytes

    Science.gov (United States)

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

    2014-11-01

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

  19. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition

    International Nuclear Information System (INIS)

    Boies, Adam M; Girshick, Steven L; Roberts, Jeffrey T; Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-01-01

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO 2 ) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO 2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO 2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 0 C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10 7 particles cm -3 .

  20. Plasma-assisted reduction of silver ions impregnated into a natural zeolite framework

    Science.gov (United States)

    Osonio, Airah P.; Vasquez, Magdaleno R.

    2018-02-01

    A green, dry, and energy-efficient method for the fabrication of silver-zeolite (AgZ) composite via 13.56 MHz radio-frequency plasma reduction is demonstrated. Impregnation by soaking and ion-exchange deposition were performed to load the silver ions (Ag+) into the sodium-zeolite samples. Characterization was performed by optical emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analyses. Results indicate the successful reduction of Ag+ to its metallic state on the surface of the zeolite with a mean diameter of 165 nm. This plasma-induced reduction technique opens possibilities in several areas including catalysis, adsorption, water treatment, and medicine.

  1. Sustainable synthesis of silver nanoparticles using macroalgae Spirogyra varians and analysis of their antibacterial activity

    Directory of Open Access Journals (Sweden)

    Zeinab Salari

    2016-07-01

    Full Text Available In this research, silver nanoparticles (SNPs were synthesized through bio-reduction of silver ions using the Spirogyra varians. The procedure used is simple and sustainable making it suitable for economic production of SNPs. The structure and morphology of SNPs were characterized by UV–visible spectroscopy, X-ray diffraction (XRD pattern, scanning electron microscopy (SEM and Fourier Transform Infra-Red (FTIR. These nanoparticles indicated an absorption peak at 430 nm in the UV–visible spectrum. The crystallite average size was estimated about 17.6 nm and SEM image confirmed synthesis of relatively uniform nanoparticles. The antibacterial effect of SNPs was also tested on several micro-organisms by measuring the inhibition zone, MIC and MBC. The results confirmed that SNPs can act as a powerful antibacterial agent against various pathogenic bacteria.

  2. Biosynthesis, characterisation and antimicrobial activity of silver nanoparticles using Hibiscus rosa-sinensis petals extracts.

    Science.gov (United States)

    Nayak, Debasis; Ashe, Sarbani; Rauta, Pradipta Ranjan; Nayak, Bismita

    2015-10-01

    Green synthesis of metallic nanoparticles has lured the world from the chemical and physical approaches owing to its rapid, non-hazardous and economic aspect of production mechanism. In this study, silver nanoparticles (AgNPs) were synthesised using petal extracts of Hibiscus rosa-sinensis. The AgNPs displayed characteristic surface plasmon resonance peak at around 421 nm having a mean particle size of 76.25±0.17 nm and carried a charge of -41±0.2 mV. The X-ray diffraction patterns displayed typical peaks of face centred cubic crystalline silver. The surface morphology was characterised by scanning electron microscopy and atomic force microscopy. Fourier transform infrared spectroscopy studies confirmed the surface modifications of the functional groups for the synthesis of AgNPs. Furthermore, the synthesised AgNPs displayed proficient antimicrobial activity against pathogenic strains of Vibrio cholerae, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus.

  3. Evaluation of the Antimicrobial Activity of Different Antibiotics Enhanced with Silver-Doped Hydroxyapatite Thin Films

    Directory of Open Access Journals (Sweden)

    Daniela Predoi

    2016-09-01

    Full Text Available The inhibitory and antimicrobial effects of silver particles have been known since ancient times. In the last few years, a major health problem has arisen due to pathogenic bacteria resistance to antimicrobial agents. The antibacterial activities of new materials including hydroxyapatite (HAp, silver-doped hydroxyapatite (Ag:HAp and various types of antibiotics such as tetracycline (T-HAp and T-Ag:HAp or ciprofloxacin (C-HAp and C-Ag:HAp have not been studied so far. In this study we reported, for the first time, the preparation and characterization of various thin films based on hydroxyapatite and silver-doped hydroxyapatite combined with tetracycline or ciprofloxacin. The structural and chemical characterization of hydroxyapatite and silver-doped hydroxyapatite thin films has been evaluated by X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FTIR. The morphological studies of the HAp, Ag:HAp, T-HAp, T-Ag:HAp, C-HAp and C-Ag:HAp thin solid films were performed using scanning electron microscopy (SEM. In order to study the chemical composition of the coatings, energy dispersive X-ray analysis (EDX and glow discharge optical emission spectroscopy (GDOES measurements have been used, obtaining information on the distribution of the elements throughout the film. These studies have confirmed the purity of the prepared hydroxyapatite and silver-doped hydroxyapatite thin films obtained from composite targets containing Ca10−xAgx(PO46(OH2 with xAg = 0 (HAp and xAg = 0.2 (Ag:HAp. On the other hand, the major aim of this study was the evaluation of the antibacterial activities of ciprofloxacin and tetracycline in the presence of HAp and Ag:HAp thin layers against Staphylococcus aureus and Escherichia coli strains. The antibacterial activities of ciprofloxacin and tetracycline against Staphylococcus aureus and Escherichia coli test strains increased in the presence of HAp and Ag:HAp thin layers.

  4. Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Hanim, Siti Aishah Mohd; Malek, Nik Ahmad Nizam Nik, E-mail: niknizam@fbb.utm.my; Ibrahim, Zaharah

    2016-01-01

    Graphical abstract: - Highlights: • Functionalization of Ag-exchanged zeolite NaY with 3-aminopropyltriethoxysilane APTES (ZSA) as antibacterial agent. • Antibacterial assay of ZSA was performed against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538. • Functionalization of Ag-exchanged zeolite NaY with APTES significantly increased the antibacterial agent. • Different mechanisms of bacterial death were suggested for each bacteria type by the functionalized Ag-exchanged zeolite NaY. - Abstract: Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver

  5. Thermal conductivity studies of novel nanofluids based on metallic silver decorated mesoporous silica nanoparticles

    International Nuclear Information System (INIS)

    Tadjarodi, Azadeh; Zabihi, Fatemeh

    2013-01-01

    Graphical abstract: - Highlights: • Metallic silver was decorated in mSiO 2 with grafted hemiaminal functional groups. • Synthesized nanoparticles were used for preparation of glycerol based nanofluids. • The effect of temperature, weight fraction of mSiO 2 and concentration of silver nanoparticles on thermal conductivity of nanofluids was investigated. - Abstract: In the present study, the mesoporous structure of silica (mSiO 2 ) nanoparticles as well as hemiaminal grafted mSiO 2 decorated by metallic silver (Ag/mSiO 2 ) has been used for the preparation of glycerol based nanofluids. Structural and morphological characterization of the synthesized products have been carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), UV–vis spectroscopy, inductively coupled plasma (ICP) and N 2 adsorption–desorption isotherms. The thermal conductivity and viscosity of the nanofluids have been measured as a function of temperature for various weight fractions and silver concentrations of mSiO 2 and Ag/mSiO 2 nanoparticles, respectively. The results show that the thermal conductivity of the nanofluids increase up to 9.24% as the weight fraction of mSiO 2 increases up to 4 wt%. Also, increasing the percent of the silver decorated mSiO 2 (Ag/mSiO 2 ) up to 2.98% caused an enhancement in the thermal conductivity of the base fluid up to 10.95%. Furthermore, the results show that the nanofluids have Newtonian behavior in the tested temperature range for various concentrations of nanoparticles

  6. Characterization and antibacterial properties of stable silver substituted hydroxyapatite nanoparticles synthesized through surfactant assisted microwave process

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Nida [Medical Implant Technology Group (MEDITEG), Faculty of Bioscience and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Abdul Kadir, Mohammed Rafiq, E-mail: rafiq@biomedical.utm.my [Medical Implant Technology Group (MEDITEG), Faculty of Bioscience and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Nik Malek, Nik Ahmad Nazim [Faculty of Bioscience and Medical Engineering (FBME), Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Mahmood, Nasrul Humaimi Bin [Medical Implant Technology Group (MEDITEG), Faculty of Bioscience and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor Darul Takzim (Malaysia); Murali, Malliga Raman; Kamarul, T. [Tissue Engineering Group, NOCERAL, Department of Orthopaedic Surgery, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2013-09-01

    Highlights: • Stable nano sized silver substitute hydroxyapatite is prepared under surfactant assisted microwave process at 600 W power for 7 min. • The nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. • Increase in silver concentration resulted in better dielectric properties. • Good antibacterial activity and silver release. - Abstract: The present study reports a relatively simple method for the synthesis of stable silver substituted hydroxyapatite nanoparticles with controlled morphology and particle size. In order to achieve this, CTAB is included as a surfactant in the microwave refluxing process (600 W for 7 min). The nanoparticles produced with different silver ion concentrations (0.05, 0.1 and 0.2 wt%) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX) and Brunauer–Emmett–Teller (BET) analysis. XRD and FTIR analyses reveal that the Ag-HA nanoparticles were phase pure at 1000 °C. FESEM images showed that the produced nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. The dielectric properties suggest that the increase in dielectric constant (ε′) and dissipation factor (D) values with increasing Ag concentrations. Antibacterial performance of the Ag-HA samples elucidated using disk diffusion technique (DDT) and minimum inhibitory concentration (MIC) demonstrates anti-bacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. This effect was dose dependent and was more pronounced against Gram-negative bacteria than Gram-positive organisms.

  7. Mechanochemical pretreatment and thiosulphate leaching of silver from complex sulphide concentrate

    Directory of Open Access Journals (Sweden)

    Boldižárová Eva

    2003-09-01

    Full Text Available The refractory character of complex ores and concentrates is at present one of the main problems of their metallurgical processing. The research activity in this sphere is aimed at the methods of improving the process of metal extraction from the sulphidic minerals representing the major components of these ores and concentrates.One of the sulphidics components of complex ores is tetrahedrite. It represents a compound of complicated structure containing several metals among which copper, antimony and arsenic prevail. Some deposits are aspecially rich in silver. The Peruvian complex sulphidic concentrate of provenience Casapalca is each from these rich deposits.In this study the physico-chemical transformations and leachability of silver from Peruvian sulphide concentrate mechanochemically activated by ultrafine alkaline milling in the attritor were investigated. The experiments with alkaline leaching of using samples have shown that this hydrometallurgical process represents an effective method to prepare of treated concentrate with physico-chemical means for further leaching process. Ammonium thiosulphate were used as agent for obtain of silver to leaching solution.The leaching of as-received concentrate with the alkaline thiosulphate solution afforded only 6 % Ag into leach. The use of milling in attritor as an innovation method of pretreatment brought about 57% of structure degradation of tetrahedrite as silver-bearing mineral in concentrate as well as to the increase in specific surface area from the original value 0.26 m2g-1 to the maximum value of 16 m2g-1. This pretreatment has been performed in an attritor using the method of experiment design. The physico-chemical changes had influence on the two step process of thiosulphate leaching of silver.The optimum results obtained by mechanochemical pretreatment and subsequent leaching of the concentrate with ammonium thiosulphate were achieved by using milling time 30 min and weight of sample

  8. Characterization and antibacterial properties of stable silver substituted hydroxyapatite nanoparticles synthesized through surfactant assisted microwave process

    International Nuclear Information System (INIS)

    Iqbal, Nida; Abdul Kadir, Mohammed Rafiq; Nik Malek, Nik Ahmad Nazim; Mahmood, Nasrul Humaimi Bin; Murali, Malliga Raman; Kamarul, T.

    2013-01-01

    Highlights: • Stable nano sized silver substitute hydroxyapatite is prepared under surfactant assisted microwave process at 600 W power for 7 min. • The nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. • Increase in silver concentration resulted in better dielectric properties. • Good antibacterial activity and silver release. - Abstract: The present study reports a relatively simple method for the synthesis of stable silver substituted hydroxyapatite nanoparticles with controlled morphology and particle size. In order to achieve this, CTAB is included as a surfactant in the microwave refluxing process (600 W for 7 min). The nanoparticles produced with different silver ion concentrations (0.05, 0.1 and 0.2 wt%) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX) and Brunauer–Emmett–Teller (BET) analysis. XRD and FTIR analyses reveal that the Ag-HA nanoparticles were phase pure at 1000 °C. FESEM images showed that the produced nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. The dielectric properties suggest that the increase in dielectric constant (ε′) and dissipation factor (D) values with increasing Ag concentrations. Antibacterial performance of the Ag-HA samples elucidated using disk diffusion technique (DDT) and minimum inhibitory concentration (MIC) demonstrates anti-bacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. This effect was dose dependent and was more pronounced against Gram-negative bacteria than Gram-positive organisms

  9. Fabrication of biogenic antimicrobial silver nanoparticles by Streptomyces aegyptia NEAE 102 as eco-friendly nanofactory.

    Science.gov (United States)

    El-Naggar, Noura El-Ahmady; Abdelwahed, Nayera A M; Darwesh, Osama M M

    2014-04-01

    The current research was focused on the extracellular biosynthesis of bactericidal silver nanoparticles (AgNPs) using cell-free supernatant of a local isolate previously identified as a novel Streptomyces aegyptia NEAE 102. The biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102 was quite fast and required far less time than previously published strains. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy, which confirmed the presence of AgNPs. Response surface methodology was chosen to evaluate the effects of four process variables (AgNO3 concentration, incubation period, pH levels, and inoculum size) on the biosynthesis of silver nanoparticles by Streptomyces aegyptia NEAE 102. Statistical analysis of the results showed that the linear and quadratic effects of incubation period, initial pH, and inoculum size had a significant effect (p nanoparticles by Streptomyces aegyptia NEAE 102. The maximum silver nanoparticles biosynthesis (2.5 OD, at 400 nm ) was achieved in runs number 5 and 14 under the conditions of 1 mM AgNO3 (1-1.5% (v/v)), incubation period (72-96 h), initial pH (9-10), and inoculum size (2-4% (v/v)). An overall 4-fold increase in AgNPs biosynthesis was obtained as compared with that of unoptimized conditions. The biosynthesized silver nanoparticles were characterized using UV-VIS spectrophotometer and Fourier transform infrared spectroscopy analysis, in addition to antimicrobial properties. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic gram-positive (Staphylococcus aureus) and gram-negative bacteria (Pseudomonas aeruginosa) and yeast (Candida albicans).

  10. Ink composition for making a conductive silver structure

    Science.gov (United States)

    Walker, Steven B.; Lewis, Jennifer A.

    2016-10-18

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

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

    Science.gov (United States)

    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.

  12. Biosynthesis of silver nanoparticles by Aspergillus niger , Fusarium ...

    African Journals Online (AJOL)

    ... scanning electron microscope (SEM). Results indicate the synthesis of silver nanoparticles in the reaction mixture. The synthesis of nanoparticles would be suitable for developing a microbial nanotechnology biosynthesis process for mass scale production. Keywords: Silver nanoparticles, biosynthesis, fungi, Aspergillus.

  13. A book on Silver fir (Abies alba in Romania

    Directory of Open Access Journals (Sweden)

    Mercurio R

    2005-01-01

    Full Text Available The contents of a new book on Silver fir (Abies alba in Romania is presented, which describes with special emphasis the characteristics of Silver fir forest in Southern Carpathians

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

    Science.gov (United States)

    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##

  15. Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol.

    Science.gov (United States)

    Naraginti, Saraschandra; Sivakumar, A

    2014-07-15

    The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (111), (200), (222) and (311) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol

    Science.gov (United States)

    Naraginti, Saraschandra; Sivakumar, A.

    2014-07-01

    The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (1 1 1), (2 0 0), (2 2 2) and (3 1 1) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs.

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

    Directory of Open Access Journals (Sweden)

    Bianco C

    2015-03-01

    Full Text Available Carlotta Bianco,1 Sanja Kezic,2 Matteo Crosera,1 Vesna Svetličić,3 Suzana Šegota,3 Giovanni Maina,4 Canzio Romano,5 Francesca Larese,6,7 Gianpiero Adami11Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy; 2Academic Medical Center, Coronel Institute, University of Amsterdam, Amsterdam, the Netherlands; 3Laboratory for Bioelectrochemistry and Surface Imaging, Division for Marine and Environmental Research, Ruder Boškovic Institute, Zagreb, Croatia; 4Department of Clinical and Biological Sciences, University of Turin, Turin, Italy; 5Department of Public and Pediatric Health Sciences, University of Turin, Turin, Italy; 6Unit of Occupational Medicine, University of Trieste, Trieste, Italy; 7Department of Medical Sciences, University of Trieste, Trieste, ItalyAbstract: The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS and by inductively coupled plasma mass spectrometer (ICP-MS. The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX. Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM. On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration ranged from 0.7 to 4.7 µg/mL (0.6–4.0 µg/cm2, fitting the bactericidal range. Silver and silver

  18. Silver Nanoparticles and Mitochondrial Interaction

    Directory of Open Access Journals (Sweden)

    Eriberto Bressan

    2013-01-01

    Full Text Available Nanotechnology has gone through a period of rapid growth, thus leading to the constant increase in the application of engineered nanomaterials in daily life. Several different types of nanoparticles have been engineered to be employed in a wide array of applications due to their high surface to volume ratio that leads to unique physical and chemical properties. So far, silver nanoparticles (AgNps have been used in many more different medical devices than any other nanomaterial, mainly due to their antimicrobial properties. Despite the promising advantages posed by using AgNps in medical applications, the possible health effects associated with the inevitable human exposure to AgNps have raised concerns as to their use since a clear understanding of their specific interaction with biological systems has not been attained yet. In light of such consideration, aim of the present work is the morphological analysis of the intracellular behavior of AgNps with a diameter of 10 nm, with a special attention to their interaction with mitochondria.

  19. Silver nanowire decorated heatable textiles

    Science.gov (United States)

    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.

  20. Biogenic silver nanoparticles using Rhinacanthus nasutus leaf extract: synthesis, spectral analysis, and antimicrobial studies

    Directory of Open Access Journals (Sweden)

    Pasupuleti VR

    2013-09-01

    Full Text Available Visweswara Rao Pasupuleti,1 TNVKV Prasad,2 Rayees Ahmad Shiekh,3 Satheesh Krishna Balam,4 Ganapathi Narasimhulu,5 Cirandur Suresh Reddy,4 Ismail Ab Rahman,3 Siew Hua Gan1 1Human Genome Center, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia; 2Institute of Frontier Technology, Regional Agricultural Research Station, Acharya NG Ranga Agricultural University, Tirupati, Andhra Pradesh, India; 3Biomaterial Research Unit, School of Dental Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia; 4Department of Chemistry, Sri Venkateswara University, Tirupati, Andhra Pradesh, India; 5Pharmacology and Toxicology, Faculty of Pharmacy, University of Technology Mara, Malaysia Abstract: Nanotechnology is gaining momentum due to its ability to transform metals into nanoparticles. The synthesis, characterization, and applications of biologically synthesized nanomaterials have become an important branch of nanotechnology. Plant extracts are a cost-effective, ecologically friendly, and efficient alternative for the large-scale synthesis of nanoparticles. In this study, silver nanoparticles (AgNps were synthesized using Rhinacanthus nasutus leaf extract. After exposing the silver ions to the leaf extract, the rapid reduction of silver ions led to the formation of AgNps in solution. The synthesis was confirmed by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. The in vitro antimicrobial activity of the AgNps synthesized using R. nasutus leaf extract was investigated against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli, Aspergillus niger, and Aspergillus flavus using a disc diffusion method. The AgNps showed potential activity against all of the bacterial strains and fungal colonies, indicating that R. nasutus has the potential to be used in the development of value-added products in the

  1. Spiraling into Transformative Learning

    Science.gov (United States)

    Cranton, Patricia

    2010-01-01

    This article explores how technical and vocational learning may spiral into transformative learning. Transformative learning theory is reviewed and the learning tasks of critical theory are used to integrate various approaches to transformative learning. With this as a foundation, the article explores how transformative learning can be fostered in…

  2. Enhanced Fluorescence from Fluorophores on Fractal Silver Surfaces

    OpenAIRE

    Parfenov, Alexandr; Gryczynski, Ignacy; Malicka, Joanna; Geddes, Chris D.; Lakowicz, Joseph R.

    2003-01-01

    Recent reports have shown enhanced fluorescence for fluorophores in close proximity to chemically deposited silver islands or colloids. To expand the usefulness of metal-enhanced fluorescence we tested fractal silver structures formed on, or near, silver electrodes by passage of electric currents. The emission intensity of fluorescein-labeled human serum albumin (FITC-HSA) was enhanced over 100-fold when adsorbed to the fractal silver structures as compared to glass. The amplitude-weighted li...

  3. Cytotoxicity and genotoxicity of biogenic silver nanoparticles

    International Nuclear Information System (INIS)

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

    2013-01-01

    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.

  4. In situ SU-8 silver nanocomposites

    Directory of Open Access Journals (Sweden)

    Søren V. Fischer

    2015-07-01

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

  5. Complex conductivity response to silver nanoparticles in ...

    Science.gov (United States)

    The increase in the use of nanoscale materials in consumer products has resulted in a growing concern of their potential hazard to ecosystems and public health from their accidental or intentional introduction to the environment. Key environmental, health, and safety research needs include knowledge and methods for their detection, characterization, fate, and transport. Specifically, techniques available for the direct detection and quantification of their fate and transport in the environment are limited. Their small size, high surface area to volume ratio, interfacial, and electrical properties make metallic nanoparticles, such as silver nanoparticles, good targets for detection using electrical geophysical techniques. Here we measured the complex conductivity response to silver nanoparticles in sand columns under varying moisture conditions (0–30%), nanoparticle concentrations (0–10 mg/g), lithology (presence of clay), pore water salinity (0.0275 and 0.1000 S/m), and particle size (35, 90–210 and 1500–2500 nm). Based on the Cole-Cole relaxation models we obtained the chargeability and the time constant. We demonstrate that complex conductivity can detect silver nanoparticles in porous media with the response enhanced by higher concentrations of silver nanoparticles, moisture content, ionic strength, clay content and particle diameter. Quantification of the volumetric silver nanoparticles content in the porous media can also be obtained from complex co

  6. Inkjet-printed silver conductors using silver nitrate ink and their electrical contacts with conducting polymers

    International Nuclear Information System (INIS)

    Liu Zhengchun; Su Yi; Varahramyan, Kody

    2005-01-01

    This paper presents a low-cost and direct-writing silver metallization process based on drop-on-demand inkjet printing technique. Silver nitrate dissolved in the mixture of water and dimethyl sulfoxide (DMSO) was used as a metal precursor for metallization. The fabricated silver films on polyimide substrate were characterized by means of scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and electrical measurements. The experimental results show that the inkjet-printed silver tracks have well-defined shapes. The resistivity of the printed silver tracks is around 1.5x10 -5 Ω.cm, one order of magnitude larger than that of bulk silver, which is attributed to the porosities as well as the residual impurities. Two conducting polymers (CP), sulfonated polyaniline (SPANi) and poly(ethylene dioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS), were inkjet-printed on the surface of the silver tracks to study electrical properties of the Ag-polymer contacts. The current-voltage measurement results show that the printed Ag-PEDOT/PSS and Ag-SPANi contacts exhibit 'ohmic' behavior

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

    Science.gov (United States)

    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. © 2014 Wiley Periodicals, Inc.

  8. Synthesis of silver nanoparticles by sophorolipids: Effect of ...

    Indian Academy of Sciences (India)

    We report in situ synthesis of silver nanoparticles using biosurfactants called sophorolipids as reducing and capping agents. We further study the effect of temperature and the structure of sophorolipid on the size of silver nanoparticles obtained. The silver nanoparticles were characterized by UVvisible, transmission electron ...

  9. Pulsed laser excitation of phosphate stabilised silver nanoparticles

    Indian Academy of Sciences (India)

    Laser flash photolysis studies were carried out on two types of silver nanoparticles prepared by -radiolysis of Ag+ solutions in the presence of polyphosphate as the stabiliser. Type I silver nanoparticles displayed a surface plasmon band at 390 nm. Type II silver nanoparticles showed a 390 nm surface plasmon band with a ...

  10. Synthesis of nanosized silver colloids by microwave dielectric heating

    Indian Academy of Sciences (India)

    Silver nanosized crystallites have been synthesized in aqueous and polyols viz., ethylene glycol and glycerol, using a microwave technique. Dispersions of colloidal silver have been prepared by the reduction of silver nitrate both in the presence and absence of stabilizer poly(vinylpyrolidone) (PVP). It was observed that ...

  11. In vitro assessment of activity of graphene silver composite sheets ...

    African Journals Online (AJOL)

    Purpose: To synthesize graphene-based silver nanocomposites and evaluate their antimicrobial and anti-Tomato Bushy Stunt Virus (TBSV) activities. Methods: A graphene-based silver composite was prepared by adsorbing silver nanoparticles AgNPs to the surfaces of graphene oxide (GO) sheets. Scanning electron ...

  12. A New Silver Complex with Ofloxacin – Preliminary Study

    Directory of Open Access Journals (Sweden)

    Rusu Aura

    2016-06-01

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

  13. Antimicrobial efficacy and ocular cell toxicity from silver nanoparticles.

    Science.gov (United States)

    Santoro, Colleen M; Duchsherer, Nicole L; Grainger, David W

    2007-05-01

    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.

  14. Facile fabrication of dendritic silver structures and their surface ...

    Indian Academy of Sciences (India)

    in AgNO3 solution. The growth speed, morphologies and structures of the silver dendrites strongly depend on AgNO3 concentration and reaction time. The silver dendrites were formed from nanosheets and the crystal structure is face-centered cubic. Rhodamine 6G was used as probe molecule to show that the silver ...

  15. Silver plating ensures reliable diffusion bonding of dissimilar metals

    Science.gov (United States)

    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.

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

    African Journals Online (AJOL)

    It was found that 0.16M nitric acid gave the best recovery rates of silver. We conclude that, although both organisms were amenable to reuse in further binding of silver, Chlorella emersonii was more efficient than Saccharomyces cerevisiae. Both organisms lost efficiency in metal uptake after two cycles of silver uptake and ...

  17. 25 CFR 304.3 - Classifying and marking of silver.

    Science.gov (United States)

    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 Board...

  18. 33 CFR 13.01-10 - Gold and silver bars.

    Science.gov (United States)

    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 one...

  19. Evaluation of silver nanoparticles as a possible coccidiostat in ...

    African Journals Online (AJOL)

    ... silver content of the livers of the silver nanoparticle group was 0.083 mg/kg compared to 0.001 mg/kg in the control group. The results of this study on the use of silver nanoparticles as a coccidiostat were therefore not conclusive, but holds promise so that further investigation is warranted. Keywords: Ag, protozoa, oocysts, ...

  20. Synthesis of silver nanoparticles by sophorolipids: Effect of ...

    Indian Academy of Sciences (India)

    Wintec

    Abstract. We report in situ synthesis of silver nanoparticles using biosurfactants called sophorolipids as reducing and capping agents. We further study the effect of temperature and the structure of sophoro- lipid on the size of silver nanoparticles obtained. The silver nanoparticles were characterized by UV- visible ...

  1. Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

    NARCIS (Netherlands)

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

    2012-01-01

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

  2. Antimicrobial Activity of Silver Nanoparticles Synthesized by Marine ...

    African Journals Online (AJOL)

    In this work, in vitro biosynthesis of silver nanoparticles was achieved using AgNO3 as a substrate by L. plantrum isolated from mangrove rhizosphere region in South East Coast of India (Gulf of Mannar). The biosynthesis was faster within a minute of silver ion coming in contact with the cell filtrate. Presence of silver ...

  3. Facile fabrication of dendritic silver structures and their surface ...

    Indian Academy of Sciences (India)

    A simple and efficient approach was developed to fabricate silver dendrites by Cu reducing Ag+ in AgNO3 solution. The growth speed, morphologies and structures of the silver dendrites strongly depend on AgNO3 concentration and reaction time. The silver dendrites were formed from nanosheets and the crystal structure ...

  4. The Benefits of Recycling Silver - A Precious Metal.

    Science.gov (United States)

    1985-09-01

    Silver Recovery Costs . . . . . . . . . . . . . . . . 36 IV. DOD Total Savings - Yardney Industries ... 39 V. Total PMRP Silver Recovery Savings...locations -- New Jersey, New York, and Connecticut. Yardney Electric stores only silver at its Connecticut facilities. These companies have storage...GFM are Yardney , and Engelhard and Engelhard Industries (20:11885). The contracts and GFM management are administered by the Defense Contracts

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

    Science.gov (United States)

    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

  6. Method for the improvement of the oxidation resistance of hydrocarbon oil, especially transformer oils by the selective removal of pro-oxidant nitrogen and sulfur compounds therefrom

    Energy Technology Data Exchange (ETDEWEB)

    Felsky, G.

    1984-02-07

    Liquid hydrocarbon streams, preferably petroleum streams, most preferably lube and specialty oil streams and in particular transformer oils are rendered resistant to oxidation by treatment with a silver salt impregnated adsorbent, preferably silver nitrate impregnated alumina by the process of contacting the hydrocarbon oil stream with the silver salt impregnated adsorbent and recovering a hydrocarbon stream of reduced pro-oxidant heteroatom compound (nitrogen compound and sulfur compound) content. The silver salt impregnated adsorbent is regenerated by sequential washing with portions of aromatic solvent and polar solvent. The aromatic solvent strips aromatic sulfides from the adsorbent. This fraction may be recombined with the hydrocarbon stream, especially in the case of transformer oils, so as to enhance the oxidation stability/resistance of the oil. The polar solvent, such as 3% methanol in toluene, strips the aliphatic sulfides from the adsorbent. The regenerated column is then ready for reuse.

  7. Comparison of silver nylon wound dressing and silver sulfadiazine in partial burn wound therapy.

    Science.gov (United States)

    Abedini, Fereydoon; Ahmadi, Abdollah; Yavari, Akram; Hosseini, Vahid; Mousavi, Sarah

    2013-10-01

    The study aims to perform a comparative assessment of two types of burn wound treatment. To do the assessment, patients with partial thickness burn wounds with total body surface area nylon wound dressing or silver sulfadiazine cream. Efficacy of treatment, use of analgesics, number of wound dressing change, wound infection and final hospitalisation cost were evaluated. The study showed silver nylon wound dressing significantly reduced length of hospital stay, analgesic use, wound infection and inflammation compared with silver sulfadiazine. © 2012 The Authors. International Wound Journal © 2012 John Wiley & Sons Ltd and Medicalhelplines.com Inc.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    Zamiri, Reza; Zakaria, Azmi; Husin, Mohd Shahril; Wahab, Zaidan Abd; Nazarpour, Forough Kalaei

    2011-01-01

    In the present work, we prepared silver nanoparticles by laser ablation of pure silver plate in ethanol and then irradiated the silver nanoparticles using a 532 nm Q-switched Nd:YAG pulsed laser. Transmission electron microscopic images of the sample after irradiation clearly showed formation of big structures, such as microrods and microbelts in ethanol. The obtained microbelts had a width of about 0.166 μm and a length of 1.472 μm. The reason for the formation of such a big structure is the tendency of the nanoparticles to aggregate in ethanol before irradiation, which causes fusion of the nanoparticles. PMID:22114485

  10. Silver nanoparticle containing silk fibroin bionanotextiles

    Energy Technology Data Exchange (ETDEWEB)

    Calamak, Semih; Aksoy, Eda Ayse [Hacettepe University, Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy (Turkey); Erdogdu, Ceren; Sagıroglu, Meral [Hacettepe University, Department of Pharmaceutical Microbiology, Faculty of Pharmacy (Turkey); Ulubayram, Kezban, E-mail: ukezban@hacettepe.edu.tr [Hacettepe University, Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy (Turkey)

    2015-02-15

    Development of new generation bionanotextiles is an important growing field, and they have found applications as wound dressings, bandages, tissue scaffolds, etc. In this study, silver nanoparticle (AgNP) containing silk-based bionanotextiles were fabricated by electrospinning, and processing parameters were optimized and discussed in detail. AgNPs were in situ synthesized within fibroin nanofibers by UV reduction of silver ions to metallic silver. The influence of post-treatments via methanol treatment and glutaraldehyde (GA) vapor exhibited changes in the secondary structure of silk. Methanol treatment increased the tensile properties of fibers due to supported crystalline silk structure, while GA vapor promoted amorphous secondary structure. AgNP containing silk fibroin bionanotextiles had strong antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa.

  11. Deposition of silver layer on different substrates

    Science.gov (United States)

    Krzemiński, J.; Kiełbasiński, K.; Szałapak, J.; Jakubowska, M.; MłoŻniak, A.; Zwierkowska, E.

    2015-09-01

    The hole process of producing continuous layer with silver nanoparticles is presented in this paper. First the ink preparation and then the spray process is shown and discussed. The silver layers were obtained on sodium glass substrate. Three different ink carriers were considered and the best one has been chosen. Spray coating process was carried out using special spray can. After obtaining sprayed layers the samples were sintered in several temperatures to investigate the lowest suitable sintering temperature. After that layers resistivity were measured. Then the silver layers were cracked to produce breakthrough fracture that was investigated by a scanning electron microscope. In this paper, the authors investigated the spray coating technique as an alternative to electroplating and other techniques, considering layer resistivity, thickness and production process.

  12. Genetics of behavior in the silver fox.

    Science.gov (United States)

    Kukekova, Anna V; Temnykh, Svetlana V; Johnson, Jennifer L; Trut, Lyudmila N; Acland, Gregory M

    2012-02-01

    The silver fox provides a rich resource for investigating the genetics of behavior, with strains developed by intensely selective breeding that display markedly different behavioral phenotypes. Until recently, however, the tools for conducting molecular genetic investigations in this species were very limited. In this review, the history of development of this resource and the tools to exploit it are described. Although the focus is on the genetics of domestication in the silver fox, there is a broader context. In particular, one expectation of the silver fox research is that it will be synergistic with studies in other species, including humans, to yield a more comprehensive understanding of the molecular mechanisms and evolution of a wider range of social cognitive behaviors.

  13. Release of silver nanoparticles from outdoor facades

    International Nuclear Information System (INIS)

    Kaegi, Ralf; Sinnet, Brian; Zuleeg, Steffen; Hagendorfer, Harald; Mueller, Elisabeth; Vonbank, Roger; Boller, Markus; Burkhardt, Michael

    2010-01-01

    In this study we investigate the release of metallic silver nanoparticles (Ag-NP) from paints used for outdoor applications. A facade panel mounted on a model house was exposed to ambient weather conditions over a period of one year. The runoff volume of individual rain events was determined and the silver and titanium concentrations of 36 out of 65 runoff events were measured. Selected samples were prepared for electron microscopic analysis. A strong leaching of the Ag-NP was observed during the initial runoff events with a maximum concentration of 145 μ Ag/l. After a period of one year, more than 30% of the Ag-NP were released to the environment. Particles were mostly 2 S. - We provide direct evidence for the release of silver nanoparticles from exterior paints to the aquatic environment.

  14. Raman scattering of Cisplatin near silver nanoparticles

    Science.gov (United States)

    Mirsaleh-Kohan, Nasrin; Duplanty, Michael; Torres, Marjorie; Moazzezi, Mojtaba; Rostovtsev, Yuri V.

    2018-03-01

    The Raman scattering of Cisplatin (the first generation of anticancer drugs) has been studied. In the presence of silver nanoparticles, strong modifications of Raman spectra have been observed. The Raman frequencies have been shifted and the line profiles are broadened. We develop a theoretical model to explain the observed features of the Raman scattering. The model takes into account self-consistently the interaction of molecules with surface plasmonic waves excited in the silver nanoparticles, and it provides a qualitative agreement with the observed Raman spectra. We have demonstrated that the using silver nanoparticles can increase sensitivity of the technique, and potentially it has a broader range of applications to both spectroscopy and microscopy.

  15. Synthesis of silver nanoparticles using Solanum trilobatum fruits extract and its antibacterial, cytotoxic activity against human breast cancer cell line MCF 7

    Science.gov (United States)

    Ramar, Manikandan; Manikandan, Beulaja; Marimuthu, Prabhu Narayanan; Raman, Thiagarajan; Mahalingam, Anjugam; Subramanian, Palanisamy; Karthick, Saravanan; Munusamy, Arumugam

    2015-04-01

    In the present study, we have synthesized silver nanoparticles by a simple and eco-friendly method using unripe fruits of Solanum trilobatum. The aqueous silver ions when exposed to unripe fruits extract were reduced and stabilized over long time resulting in biosynthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction (XRD). These biologically synthesized silver nanoparticles were tested for its antibacterial activity against few human pathogenic bacteria including Gram-positive (Streptococcus mutans, Enterococcus faecalis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria. In addition, we also demonstrated anticancer activity of these nanoparticles in vitro against human breast cancer cell line (MCF 7) using MTT, nuclear morphology assay, Western blot and RT-PCR expression. These results taken together show the potential applications of biosynthesized silver nanoparticles using S. trilobatum fruits.

  16. Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

    Science.gov (United States)

    Stevanović, Magdalena; Kovačević, Branimir; Petković, Jana; Filipič, Metka; Uskoković, Dragan

    2011-01-01

    Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly-α, γ, L-glutamic acid (PGA), a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species. PMID:22131829

  17. A facile biomimetic preparation of highly stabilized silver nanoparticles derived from seed extract of Vigna radiata and evaluation of their antibacterial activity

    Science.gov (United States)

    Choudhary, Manoj Kumar; Kataria, Jyoti; Cameotra, Swaranjit Singh; Singh, Jagdish

    2016-01-01

    The significant antibacterial activity of silver nanoparticles draws the major attention toward the present nanobiotechnology. Also, the use of plant material for the synthesis of metal nanoparticles is considered as a green technology. In this context, a non-toxic, eco-friendly, and cost-effective method has been developed for the synthesis of silver nanoparticles using seed extract of mung beans ( Vigna radiata). The synthesized nanoparticles have been characterized by UV-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS), and X-ray diffraction (XRD). The UV-visible spectrum showed an absorption peak at around 440 nm. The different types of phytochemicals present in the seed extract synergistically reduce the Ag metal ions, as each phytochemical is unique in terms of its structure and antioxidant function. The colloidal silver nanoparticles were observed to be highly stable, even after 5 months. XRD analysis showed that the silver nanoparticles are crystalline in nature with face-centered cubic geometry and the TEM micrographs showed spherical particles with an average size of 18 nm. Further, the antibacterial activity of silver nanoparticles was evaluated by well-diffusion method and it was observed that the biogenic silver nanoparticles have an effective antibacterial activity against Escherichia coli and Staphylococcus aureus. The outcome of this study could be useful for nanotechnology-based biomedical applications.

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

    NARCIS (Netherlands)

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

    2015-01-01

    Human data on dermal absorption of silver under "in use" scenario are scarce which hampers health risk assessment. The main objective of the present study was to determine percutaneous penetration of silver after dermal exposure to silver containing garment in healthy individuals and atopic

  19. Synthesis, characterization and evaluation of antimicrobial and cytotoxic activities of biogenic silver nanoparticles synthesized from Streptomyces xinghaiensis OF1 strain

    OpenAIRE

    Wypij, Magdalena; Czarnecka, Joanna; Świecimska, Magdalena; Dahm, Hanna; Rai, Mahendra; Golinska, Patrycja

    2018-01-01

    We report synthesis of silver nanoparticles (AgNPs) from Streptomyces xinghaiensis OF1 strain, which were characterised by UV–Vis and Fourier transform infrared spectroscopy, Zeta sizer, Nano tracking analyser, and Transmission electron microscopy. The antimicrobial activity of AgNPs alone, and in combination with antibiotics was evaluated against bacteria, namely Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, and yeasts viz., Candida albicans and Malas...

  20. Asymmetric Mannich Reaction of Isatin-Based Ketimines with α-Diazomethylphosphonates Catalyzed by Chiral Silver Phosphate.

    Science.gov (United States)

    Chen, Jing; Wen, Xiaojing; Wang, Yan; Du, Fei; Cai, Liu; Peng, Yungui

    2016-09-02

    An efficient asymmetric Mannich reaction of isatin-based ketimines with α-diazomethylphosphonates has been developed using a chiral binaphthanol-derived silver phosphate as the catalyst. This reaction allowed the construction of a series of chiral oxindoles bearing a quaternary stereocenter and amino group at the C3 position with up to 95% yields and 99% ee. Those products could be further transformed into promising densely functionalized compounds by merging of the oxindole and β-aminophosphonate.

  1. Growth and galvanic replacement of silver nanocubes in organic media

    Science.gov (United States)

    Polavarapu, Lakshminarayana; Liz-Marzán, Luis M.

    2013-05-01

    Although metal nanoparticles with various shapes can be prepared in polar organic solvents, little has been advanced toward the shape-controlled synthesis in non-polar solvents. We report a simple method for the synthesis of nearly monodisperse single crystalline silver nanocubes in a non-polar solvent (1,2-dichlorobenzene) by using oleylamine as both a reducing and capping agent. Mechanistic studies based on the time evolution of Ag nanoparticles revealed that multiply twinned nanocrystals form at the beginning of the reaction, which are gradually transformed into single crystalline Ag nanocubes by oxidative etching. Control experiments showed that the solvent plays an important role in the formation of such single crystalline Ag nanocubes. The effects of reaction temperature, oleylamine concentration, solvent, and the nature of the silver ion precursor on the morphology and monodispersity of the nanoparticles were systematically investigated. Additionally, the galvanic replacement reaction with HAuCl4 in an organic medium was implemented to prepare hydrophobic hollow Au-Ag nanocages with tunable localized surface plasmon resonances.Although metal nanoparticles with various shapes can be prepared in polar organic solvents, little has been advanced toward the shape-controlled synthesis in non-polar solvents. We report a simple method for the synthesis of nearly monodisperse single crystalline silver nanocubes in a non-polar solvent (1,2-dichlorobenzene) by using oleylamine as both a reducing and capping agent. Mechanistic studies based on the time evolution of Ag nanoparticles revealed that multiply twinned nanocrystals form at the beginning of the reaction, which are gradually transformed into single crystalline Ag nanocubes by oxidative etching. Control experiments showed that the solvent plays an important role in the formation of such single crystalline Ag nanocubes. The effects of reaction temperature, oleylamine concentration, solvent, and the nature of the

  2. Electrochemical and Laser Deposition of Silver for Use in Metal-Enhanced Fluorescence

    OpenAIRE

    Geddes, Chris D.; Parfenov, Alexandr; Roll, David; Fang, Jiyu; Lakowicz, Joseph R.

    2003-01-01

    We describe two reagentless methods of silver deposition for metal-enhanced fluorescence. Silver was deposited on glass positioned between two silver electrodes with a constant current in pure water. Illumination of the glass between the electrodes resulted in localized silver deposition. Alternatively, silver was deposited on an Indium Tin Oxide cathode, with a silver electrode as the anode. Both types of deposited silver produced a 5–18-fold increase in the fluorescence intensity of a nearb...

  3. Rapid and Efficient Synthesis of Silver Nanofluid Using Electrical Discharge Machining

    OpenAIRE

    Kuo-Hsiung Tseng; Heng-Lin Lee; Chih-Yu Liao; Kuan-Chih Chen; Hong-Shiou Lin

    2013-01-01

    The electrical discharge machining (EDM) system has been proven feasible as a rapid and efficient method for silver nanofluid preparation. This study prepared the silver nano-fluid via EDM and investigated the relationship between its process parameters and product characteristics. The prior study had found that the silver nano-fluid prepared by EDM contained both silver nanoparticles and silver ions. Silver ions had revealed the cause of the high suspension of the silver nanoparticles. To ex...

  4. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten

    2000-01-01

    , and copper oxides is inserted into a silver tube and reduced by multi-step drawing. These single-filaments are packed in a new silver tube thus forming a multi-filament containing e.g. 37 single-filaments, which is subsequently reduced by drawing and rolling to tapes approximately 0.2 mm thick by 3 mm wide...... and current leading properties of the final superconducting fibres. The present work describes studies on alternative packing geometries and process parameters in the flat rolling operations. The aim is to obtain homogenous filaments with advantageous geometry and good texture while avoiding potential defects...

  5. Silver release from coated particle fuel

    International Nuclear Information System (INIS)

    Brown, P.E.; Nabielek, H.

    1977-03-01

    The fission product Ag-110 m released from coated particles can be the dominant source of radioactivity from the core of a high temperature reactor in the early stages of the reactor life and possibly limits the accessability of primary circuit components. It can be shown that silver is retained in oxide fuel by a diffusion process (but not in carbide or carbon-diluted fuel) and that silver is released through all types of pyrocarbon layers. The retention in TRISO particles is variable and seems to be mainly connected with operating temperature and silicon carbide quality. (orig.) [de

  6. Silver nanoparticles – wolves in sheep's clothing?

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus; Jiang, Xiumei; Miclaus, Teodora

    2015-01-01

    Silver nanoparticles (Ag NPs) are one of the most widely utilized engineered nanomaterials (ENMs) in commercial products due to their effective antibacterial activity, high electrical conductivity, and optical properties. Therefore, they have been one of the most intensively investigated...... effects following exposure to Ag NPs, information about the mechanisms for their cytotoxicity and genotoxicity is necessary. The present paper attempts to review the cellular and molecular mechanisms behind Ag NP toxicity. In addition, the role of silver ions in the toxicity of Ag NPs is discussed....

  7. Recovery of silver from CEPOD anolyte solutions

    International Nuclear Information System (INIS)

    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 2 (and other Pu species) to (PuO 2 ) 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 2 or H 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 6 H 8 O 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

  8. Mineral resource of the month: silver

    Science.gov (United States)

    Katrivanos, Florence C.

    2015-01-01

    Silver, one of the eight precious or noble metals, has been used extensively throughout recorded history for various medical purposes, ornaments and utensils, and for its intrinsic value as the basis for trade and monetary systems. Silver has played a significant role in world history, financing a Greek victory over the Persians in 480 B.C., helping Spain become a world power in the 16th and 17th centuries, and helping fund the Union forces during the U.S. Civil War, to give a few examples.

  9. Selective Electroless Silver Deposition on Graphene Edges

    DEFF Research Database (Denmark)

    Durhuus, D.; Larsen, M. V.; Andryieuski, Andrei

    2015-01-01

    on silica substrate and thus potentially restoring electric connectivity with minimal influence on the overall graphene electrical and optical properties. The presented technique could find applications in graphene based transparent conductors as well as selective edge functionalization and can be extended......We demonstrate a method of electroless selective silver deposition on graphene edges or between graphene islands without covering the surface of graphene. Modifications of the deposition recipe allow for decoration of graphene edges with silver nanoparticles or filling holes in damaged graphene...

  10. James Cox’s Silver Swan

    OpenAIRE

    Smith, Roger

    2018-01-01

    The Silver Swan (ill. 25) is a life-sized automaton that has been in the Bowes Museum in the northern English town of Barnard Castle since 1872. It was first exhibited in 1773 by the jeweller and entrepreneur James Cox (c. 1723-1800), as part of his « museum » of musical clocks and automata in Spring Gardens, London. Before considering the Swan itself, it is important to understand the unusual circumstances which led to its creation. Figure 25 - Silver Swan, c. 1773 H. 80 cm © Bowes Museum, ...

  11. Fluorescent DNA Stabilized Silver Nanoclusters as Biosensors

    Directory of Open Access Journals (Sweden)

    Alfonso Latorre

    2013-01-01

    Full Text Available DNA stabilized fluorescent silver nanoclusters are promising materials, of which fluorescent properties can be exploited to develop sensors. Particularly, the presence of a DNA strand in the structure has promoted the development of gene sensors where one part of the sensor is able to recognize the target gene sequence. Moreover, since oligonucleotides can be designed to have binding properties (aptamers a variety of sensors for proteins and cells have been developed using silver nanoclusters. In this review the applications of this material as sensors of different biomolecules are summarized.

  12. Biosynthesis of silver nanoparticles using Saccharomyces cerevisiae.

    Science.gov (United States)

    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.

  13. Investigation of antibacterial properties silver nanoparticles prepared via green method

    Directory of Open Access Journals (Sweden)

    Shameli Kamyar

    2012-07-01

    Full Text Available Abstract Background This study aims to investigate the influence of different stirring times on antibacterial activity of silver nanoparticles in polyethylene glycol (PEG suspension. The silver nanoparticles (Ag-NPs were prepared by green synthesis method using green agents, polyethylene glycol (PEG under moderate temperature at different stirring times. Silver nitrate (AgNO3 was taken as the metal precursor while PEG was used as the solid support and polymeric stabilizer. The antibacterial activity of different sizes of nanosilver was investigated against Gram–positive [Staphylococcus aureus] and Gram–negative bacteria [Salmonella typhimurium SL1344] by the disk diffusion method using Müeller–Hinton Agar. Results Formation of Ag-NPs was determined by UV–vis spectroscopy where surface plasmon absorption maxima can be observed at 412–437 nm from the UV–vis spectrum. The synthesized nanoparticles were also characterized by X-ray diffraction (XRD. The peaks in the XRD pattern confirmed that the Ag-NPs possessed a face-centered cubic and peaks of contaminated crystalline phases were unable to be located. Transmission electron microscopy (TEM revealed that Ag-NPs synthesized were in spherical shape. The optimum stirring time to synthesize smallest particle size was 6 hours with mean diameter of 11.23 nm. Zeta potential results indicate that the stability of the Ag-NPs is increases at the 6 h stirring time of reaction. The Fourier transform infrared (FT-IR spectrum suggested the complexation present between PEG and Ag-NPs. The Ag-NPs in PEG were effective against all bacteria tested. Higher antibacterial activity was observed for Ag-NPs with smaller size. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field. Conclusions Ag-NPs were successfully synthesized in PEG suspension under moderate temperature at different stirring times. The study clearly showed that the Ag-NPs with

  14. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO3) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils

    International Nuclear Information System (INIS)

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A.M.; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J.

    2015-01-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value. - Highlights: • Toxicity of silver nanoparticles in soils increased with time. • Standard tests do not adequately assess toxicity of silver NPs to earthworms. • Internal Ag in earthworms did not always explain toxicity after shorter aging times. • With aging time, Ag ion and Ag NP effect in soils will merge to a common value. - Toxicity of silver nanoparticles in soils increased with time with the result that commonly applied tests of 28 days exposure with freshly spiked soils do not adequately assess the environmental hazard of silver nanoparticles

  15. Capillary electrophoresis coupled with inductively coupled mass spectrometry as an alternative to cloud point extraction based methods for rapid quantification of silver ions and surface coated silver nanoparticles

    OpenAIRE

    Qu, Haiou; Mudalige, Thilak K.; Linder, Sean W.

    2015-01-01

    Speciation and accurate quantification of ionic silver and metallic silver nanoparticles are critical to investigate silver toxicity and to determine the shelf-life of products that contain nano silver under various storage conditions. We developed a rapid method for quantification of silver ions and silver nanoparticles using capillary electrophoresis (CE) interfaced with inductively-coupled plasma mass spectrometry (ICPMS). The addition of 2-mercaptopropionylglycine (tiopronin) to the backg...

  16. Sunlight based irradiation strategy for rapid green synthesis of highly stable silver nanoparticles using aqueous garlic (Allium sativum) extract and their antibacterial potential

    Energy Technology Data Exchange (ETDEWEB)

    Rastogi, Lori [National Center for Chemical Characterization of Materials, Bhabha Atomic Research Centre, ECIL-PO, Hyderabad 500 062 (India); Arunachalam, J., E-mail: aruncccm@rediffmail.com [National Center for Chemical Characterization of Materials, Bhabha Atomic Research Centre, ECIL-PO, Hyderabad 500 062 (India)

    2011-09-15

    Highlights: {yields} We report green synthetic route for the production crystalline silver nanoparticles using garlic as both reducing and stabilizing agent. {yields} Synthesis has been achieved by exposing the solution mixture of [Ag(NH{sub 3}){sub 2}]{sup +} and aqueous garlic extract under sunlight. {yields} Role of light in the synthesis process has been investigated and is discussed in detail. {yields} The antibacterial effect of the synthesized silver nanoparticles has been assessed against both Gram classes of bacteria. {yields} Synthesized silver colloidal solutions were found to be stable for a very long period and retained their bactericidal potential. - Abstract: A green synthetic route for the production of highly stable silver nanoparticles using aqueous garlic extract is being reported for the first time. The silver nanoparticles were synthesized by exposing a mixture of 0.1 M [Ag(NH{sub 3}){sub 2}]{sup +} and diluted aqueous garlic extract under bright sunlight for 15 min. The garlic extract components served as both reducing and capping agents in the synthesis of silver nanoparticles while the sunlight acted as catalyst in the synthesis process. The synthesized nanoparticles were characterized using UV-visible (UV-vis) spectrophotometer; transmission electron microscopy (TEM), glancing angle X-ray diffraction (GA-XRD) and Fourier transform infra red (FTIR) spectrometry. The nanoparticles were found to be poly-dispersed in nature, spherical in shape and of 7.3 {+-} 4.4 nm in size. The FTIR analysis was suggestive of proteins as capping agents around the nanoparticles. The yield of synthesized nanoparticles was calculated to be approximately 80% by dry weight and 85% ICP-AES method. The synthesized silver nanoparticles exhibited good antibacterial potential against both Gram positive and Gram negative bacterial strains, as measured using well diffusion assay. Most importantly, the silver colloidal solutions thus synthesized were found to be stable for

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

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

    Science.gov (United States)

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

    2014-03-05

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

  19. Sunlight-Driven Reduction of Silver Ions by Natural Organic Matter: Formation and Transformation of Silver Nanoparticles

    Science.gov (United States)

    Photobiogeochemical reactions involving metal species can be a source of naturally occurring nanoscale materials in the aquatic environment. This study demonstrates that, under simulated sunlight exposure, ionic Ag is photoreduced in river water or synthetic natural water samples...

  20. Synthesis and characterization of silver nanoparticles in AOT microemulsion system

    Science.gov (United States)

    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.