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Sample records for prepared silver oxide

  1. Chitosan–silver oxide nanocomposite film: Preparation and antimicrobial activity

    Indian Academy of Sciences (India)

    Shipra Tripathi; G K Mehrotra; P K Dutta

    2011-02-01

    The chitosan–silver oxide encapsulated nanocomposite film was prepared by solution casting method. The prepared film was characterized by FTIR, scanning electron microscopy (SEM), thermal studies, and UV-Vis spectroscopy. The elemental composition of the film was studied by energy dispersive X-ray analysis (EDAX). The antibacterial activity of the composite film against pathogenic bacteria viz. Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa was measured by agar diffusion method. Our observations suggest that chitosan as biomaterial based nanocomposite film containing silver oxide has an excellent antibacterial ability for food packaging applications.

  2. Silver vanadium oxide cathode material and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, A.M.

    1993-06-22

    A method for making an electrochemical cell having the steps of admixing silver vanadium oxide with a conductive material and a binder and forming the admixture into a cathode, combining the cathode with a lithium metal anode; and combining an electrolyte with the anode and cathode, the method is described consisting of preparing the silver vanadium oxide by a chemical addition reaction consisting of admixing AgVO[sub 3] and V[sub 2]O[sub 5] in a 2:1 mole ratio heating the admixed AgVO[sub 3] and V[sub 3]O[sub 5] at a reaction temperature in the range of 300 C to 700 C for 5 to 24 hours. An electrochemical cell having a lithium metal anode, cathode and an electrolyte having a metal salt in a nonaqueous solvent comprising: the cathode including a crystalline silver vanadium oxide prepared by a chemical addition reaction.

  3. Aging in chemically prepared divalent silver oxide electrodes for silver/zinc reserve batteries

    Science.gov (United States)

    Smith, David F.; Brown, Curtis

    The instability of silver(II) oxide electrodes used in silver/zinc reserve batteries is the well known cause of capacity loss and delayed activation in reserve batteries after they are stored in the dry, unactivated state for extended periods of time. Metal contaminants in sintered/electroformed electrodes destabilize the oxide and the solid state reaction between AgO and elemental silver results in the formation of the lower capacity monovalent oxide Ag 2O. Chemically prepared (CP) AgO can be used to avoid the metal contaminants and to minimize the interfacial contact area between AgO and Ag, thus minimizing the affects of aging on the electrodes. Electrodes were fabricated with CP AgO and polytetrafluoroethylene (PTFE) binder and expanded silver metal current collectors. Experimentally, both electrode active material compacts (AgO and binder only) and electrodes complete with AgO/binder and silver current collector were tested to evaluate the influence of the current collector on aging. The electrode samples were discharged at a constant rate of 50 mA cm -2 before and after storage at 60°C for 21 days as well as after storage at room ambient temperature conditions for 91 months. The results indicate that the affects of aging upon the AgO/binder compacts are insignificant for long term storage at room temperature. However, thermally accelerated aging at high temperature (60°C) affects both transient and stabilized load voltage as well as capacity. In terms of capacity, the AgO/binder mix itself looses about 5% capacity after 21 days dry storage at 60°C while electrodes complete with current collector loose about 8%. The 60% increase in capacity loss is attributed to the solid state reaction between AgO and elemental silver.

  4. Preparation of silver nanoparticles loaded graphene oxide nanosheets for antibacterial activity

    Science.gov (United States)

    T, T. T., Vi; Lue, S. J.

    2016-11-01

    A simple, facile method to fabricate successfully silver nanoparticle (AgNPs) decorated on graphene oxide (GO) layers via grafted thiol groups. Samples were prepared with different concentrations of AgNO3. Resulting AgNPs were quasi-spherical in shape and attached on the layers of GO. Physical properties were confirmed by X-ray diffraction (XRD), zeta potential, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectra, thermogravimetric analyzer (TGA), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). Antimicrobial test was effectively showed using MRSA (Staphylococcus areus). The GO-Ag NPs with appropriate Ag NPs content of 0.2 M AgNO3 exhibited the strongest antibacterial activity at 48.77% inhibition after 4 hours incubation.

  5. Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

    Science.gov (United States)

    Shao, Wei; Liu, Xiufeng; Min, Huihua; Dong, Guanghui; Feng, Qingyuan; Zuo, Songlin

    2015-04-01

    In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

  6. Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Chimie Douce Preparation and Resulting Lithium Cell Electrochemistry.

    Science.gov (United States)

    Kim, Young Jin; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2011-08-15

    Recently, we have shown silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) to be a promising cathode material for lithium based batteries. Whereas the first reported preparation of SVPO employed an elevated pressure, hydrothermal approach, we report herein a novel ambient pressure synthesis method to prepare SVPO, where our chimie douce preparation is readily scalable and provides material with a smaller, more consistent particle size and higher surface area relative to SVPO prepared via the hydrothermal method. Lithium electrochemical cells utilizing SVPO cathodes made by our new process show improved power capability under constant current and pulse conditions over cells containing cathode from SVPO prepared via the hydrothermal method.

  7. Preparation of silver tin oxide powders by hydrothermal reduction and crystallization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw marrials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn(OH)4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor, the reduction of Ag+ and the crystallization of tin oxide were carried out simultaneonsly by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin.

  8. Preparation of graphene oxide-silver nanoparticle nanohybrids with highly antibacterial capability.

    Science.gov (United States)

    Zhu, Zhijun; Su, Min; Ma, Lan; Ma, Lina; Liu, Dianjun; Wang, Zhenxin

    2013-12-15

    A simple method based on electrostatic interactions was utilized to assemble silver nanoparticles (AgNPs) to graphene oxide (GO) sheets. This method allows conjugation of AgNPs with desired morphologies (densities, sizes and shapes) onto GO. In this process, poly(diallyldimethylammonium chloride) (PDDA) was introduced as an adhesive agent. The as-prepared graphene oxide-AgNPs composites (GO-AgNPs) have enhanced colloid stability and photo-stability than that of AgNPs. After conjugating to GO sheets, the antibacterial activities of AgNPs against Gram negative (G-) bacterial strain (Escherichia coli, E. coli) and Gram positive (G+) bacterial strain (Bacillus subtilis, B. subtilis) have been improved significantly. The antibacterial activity of GO-AgNPs is dependent on the size of AgNPs, i.e. the small AgNPs modified GO sheets show more effective antibacterial capability than that of large AgNPs modified GO sheets. Compared with AgNPs, the enhanced antibacterial activity of GO-AgNPs might not only be due to high stability of AgNPs anchored on GO sheets, but also the positive charged surface of hybrids which increases the electrostatic interaction of bacterial cell membrane with nanohybrids.

  9. Preparation and antibacterial activity of chitosan-based nanocomposites containing bentonite-supported silver and zinc oxide nanoparticles for water disinfection

    CSIR Research Space (South Africa)

    Motshekga, SC

    2015-07-01

    Full Text Available -assisted synthesis method. The resulting bentonite-supported silver and zinc oxide nanoparticles were dispersed in a chitosan biopolymer to prepare bentonite chitosan nanocomposites. The obtained bentonite chitosan nanocomposites were characterized with BET surface...

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

    Science.gov (United States)

    Tudela, David

    2008-01-01

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

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P. [Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2006-10-27

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

  13. Preparation and Anti-oxidation Property of Flaky Silver Covered Copper Powder%片状铜粉镀银及抗氧化性能研究

    Institute of Scientific and Technical Information of China (English)

    宋曰海; 马丽杰

    2013-01-01

    采用置换还原法在片状铜粉上镀银.对铜粉镀银制备过程及抗氧化性能做了研究.实验结果表明,在铜粉表面首先发生置换反应,生成点缀式银颗粒,之后银颗粒长大,不完全的包覆在铜粉表面,溶液中过量的银离子在还原剂的作用下,表面银层进一步生长,得到完全包覆银的铜粉.通过X-射线衍射分析,片状铜粉镀银层表面未见氧化物,所得粉末表层结构致密.铜粉镀银层具有良好的抗高温氧化性.%Flaky silver covered copper powder was prepared by displacement reaction.Preparation process and anti-oxidation property of the silver covered copper powder were studied.Experimental results showed that interspersed silver particles generated on the surface of copper powder by displacement reaction at first,and then the silver particles grew up and coated the copper powder incompletely.With excess silver ions in solution,silver layer grew further by reduction reaction and covered the copper powder completely.By XRD analysis,no oxide was detected on the surface of silver covered copper powder,the silver covered copper powder has dense surface structure and good high temperature oxidation resistance.

  14. Preparation of graphene oxide-wrapped carbon sphere@silver spheres for high performance chlorinated phenols sensor

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Tian, E-mail: gantsjy@163.com [College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000 (China); State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Lv, Zhen; Sun, Junyong; Shi, Zhaoxia; Liu, Yanming [College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000 (China)

    2016-01-25

    Highlights: • Hierarchical CS@Ag@GO composite was obtained by a simple solution route. • Signal amplification is achieved for sensitive detection of chlorinated phenols. • The low-cost method exhibits wide concentration range and acceptable accuracy. • The method can be successfully applied to detect chlorinated phenols in waters. - Abstract: A template-activated strategy was developed to construct core/shell structured carbon sphere@silver composite based on one-pot hydrothermal treatment. The CS@Ag possessed a uniform three-dimensional interconnected microstructure with an enlarged surface area and catalytic activity, which was further mechanically protected by graphene oxide (GO) nanolayers to fabricate intriguing configuration, which was beneficial for efficiently preventing the aggregation and oxidation of AgNPs and improving the electrical conductivity through intimate contact. By immobilizing this special material on electrode surface, the CS@Ag@GO was further used for sensitive determination of chlorinated phenols including 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. The tailored structure, fast electron transfer ability and facile preparation of CS@Ag@GO made it a promising electrode material for practical applications in phenols sensing.

  15. Hydrothermal preparation of reduced graphene oxide-silver nanocomposite using Plectranthus amboinicus leaf extract and its electrochemical performance.

    Science.gov (United States)

    Zheng, Yuhong; Wang, Aiwu; Cai, Wen; Wang, Zhong; Peng, Feng; Liu, Zhong; Fu, Li

    2016-12-01

    Graphene based nanocomposites are receiving increasing attention in many fields such as material chemistry, environmental science and pharmaceutical science. In this study, a facial synthesis of a reduced graphene oxide-silver nanocomposite (RGO-Ag) was carried out from Plectranthus amboinicus leaf extract. The synthesized nanocomposite was characterized by using X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscope and UV-vis spectroscopy for structural confirmation. The reduction of graphene oxide and silver ions was achieved simultaneously due to the reducibility of the Plectranthus amboinicus leaf extract. We further investigated the electrochemical properties of the biosynthesized RGO-Ag nanocomposite. A nonenzymatic H2O2 electrochemical sensor was shown to be successfully fabricated by using biosynthesized RGO-Ag nanocomposite. Moreover, the fabricated electrochemical sensor also showed good selectivity.

  16. 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.

  17. Preparation of silver powder through glycerol process

    Indian Academy of Sciences (India)

    Amit Sinha; B P Sharma

    2005-06-01

    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 through this process were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis. The powders were well crystalline and contained oxygen, carbon and hydrogen as impurities. Overall purity was better than 99.9%. The yield of silver powder was better than 99%.

  18. Preparation of a Microspherical Silver-Reduced Graphene Oxide-Bismuth Vanadate Composite and Evaluation of Its Photocatalytic Activity

    OpenAIRE

    2016-01-01

    A novel Ag-reduced graphene oxide (rGO)-bismuth vanadate (BiVO4) (AgGB) ternary composite was successfully synthesized via a one-step method. The prepared composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET) surface area measurement, Raman scattering spectroscopy, and ultraviolet-visible diffuse-reflection spectroscopy (UV-vis DRS). The results showed that...

  19. Preparation of glasses and glass ceramics of heavy metal oxides containing silver: optical, structural and electrochemical properties; Preparacao de vidros e vitroceramicas de oxidos de metais pesados contendo prata: propriedades opticas, estruturais e eletroquimicas

    Energy Technology Data Exchange (ETDEWEB)

    Bregadiolli, Bruna A. [Departamento de Fisica, Faculdade de Ciencias, Universidade Estadual Paulista, Bauru - SP (Brazil); Souza, Ernesto R.; Sigoli, Fernando A. [Instituto de Quimica, Universidade Estadual de Campinas, Campinas - SP (Brazil); Caiut, Jose M.A. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto - SP (Brazil); Alencar, Monica A.S.; Benedetti, Assis V. [Instituto de Quimica, Universidade Estadual Paulista, Araraquara - SP (Brazil); Nalin, Marcelo, E-mail: mnalin@ufscar.br [Departamento de Quimica, Universidade Federal de Sao Carlos, SP, (Brazil)

    2012-07-01

    Silver containing heavy metal oxide glasses and glass ceramics of the system WO{sub 3}-SbPO{sub 4} -PbO-AgCl with different AgCl contents have been prepared and their thermal, structural and optical properties characterized. Glass ceramics containing metallic silver nanoparticles have been prepared by annealing glass samples at temperatures above the glass transition and analyzed by transmission electron microscopy and energy dispersive X-ray microanalysis. The presence of the metallic clusters has been also confirmed by the observation of a surface plasmon resonance band in the visible range. Cyclic voltammetric measurements indicated the presence of metallic silver into the glasses, even before to perform the thermal treatment. (author)

  20. Antibacterial effects of electrospun chitosan/poly(ethylene oxide) nanofibrous membranes loaded with chlorhexidine and silver

    NARCIS (Netherlands)

    Song, J.; Remmers, S.J.; Shao, J.; Kolwijck, E.; Walboomers, X.F.; Jansen, J.A.; Leeuwenburgh, S.C.; Yang, F.

    2016-01-01

    To prevent percutaneous device associated infections (PDAIs), we prepared electrospun chitosan/poly(ethylene oxide) (PEO) nanofibrous membrane containing silver nanoparticles as an implantable delivery vehicle for the dual release of chlorhexidine and silver ions. We observed that the silver nanopar

  1. Electrodeposition of silver nanoparticle arrays on transparent conductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dezhong; Tang, Yang, E-mail: tangyang@nicenergy.com; Jiang, Fuguo; Han, Zhihua; Chen, Jie

    2016-04-30

    Highlights: • The sliver nanoparticles' size and the distance between nanoparticles are tunable. - Abstract: In this paper, we present a facile method for the preparation of silver nanoparticles on aluminum-doped zinc oxide (AZO) via electrodeposition techniques at room temperature. The morphology and structure of silver nanoparticles are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), respectively. Due to localized surface plasmon resonances, as-prepared silver nanoparticles on AZO glass exhibited different reflectivity in contrast with bare AZO glass. The weighted reflection of AZO substrate increased from 10.2% to 12.8%. The high reflection property of silver nanoparticle arrays on AZO substrate might be applicable for thin film solar cells and other optoelectronics applications.

  2. Preparation of a Microspherical Silver-Reduced Graphene Oxide-Bismuth Vanadate Composite and Evaluation of Its Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Mao Du

    2016-03-01

    Full Text Available A novel Ag-reduced graphene oxide (rGO-bismuth vanadate (BiVO4 (AgGB ternary composite was successfully synthesized via a one-step method. The prepared composite was characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, energy dispersive X-ray (EDX, Brunauer-Emmett-Teller (BET surface area measurement, Raman scattering spectroscopy, and ultraviolet-visible diffuse-reflection spectroscopy (UV-vis DRS. The results showed that bulk monoclinic needle-like BiVO4 and Ag nanoparticles with a diameter of approximately 40 nm formed microspheres (diameter, 5–8 μm with a uniform size distribution that could be loaded on rGO sheets to facilitate the transport of electrons photogenerated in BiVO4, thereby reducing the rate of recombination of photogenerated charge carriers in the coupled AgGB composite system. Ag nanoparticles were dispersed on the surface of the rGO sheets, which exhibited a localized surface plasmon resonance phenomenon and enhanced visible light absorption. The removal efficiency of rhodamine B dye by AgGB (80.2% was much higher than that of pure BiVO4 (51.6% and rGO-BiVO4 (58.3% under visible light irradiation. Recycle experiments showed that the AgGB composite still presented significant photocatalytic activity after five successive cycles. Finally, we propose a possible pathway and mechanism for the photocatalytic degradation of rhodamine B dye using the composite photocatalyst under visible light irradiation.

  3. Preparation of Gold-Silver Alloy Nanoparticles Supported on NiCo2O4 Spinel Oxides for the Treatment of CO in Atmosphere.

    Science.gov (United States)

    Chinh, Vu Duc; Trung, Nguyen Quoc

    2015-06-01

    Heterometallics are an important class of catalysts. Alloy nanoparticles have higher activities than monometallic counterparts in catalysis because of the synergistic effects between the two metals. The Ni-Co composition, which is a typical alloy chemical composition, has a remarkable effect on catalytic activity. Ni-Co mixed oxides were characterized by thermal effect, X-ray diffraction, energy dispersive X-ray spectroscopy, Scanning Electron Microscope and BET specific surface area techniques. X-ray diffraction show that the formation of small spinel oxides nanoparticles. Very small amounts of gold-silver alloy nanoparticles deposited on such mixed oxides improve the catalytical activity for CO oxidation.

  4. Characteristics of MOX dissolution with silver mediated electrolytic oxidation method

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, Miki; Nakazaki, Masato; Kida, Takashi; Sato, Kenji; Kato, Tadahito; Kihara, Takehiro; Sugikawa, Susumu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    MOX dissolution with silver mediated electrolytic oxidation method is to be applied to the preparation of plutonium nitrate solution to be used for criticality safety experiments at Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF). Silver mediated electrolytic oxidation method uses the strong oxidisation ability of Ag(II) ion. This method is though to be effective for the dissolution of MOX, which is difficult to be dissolved with nitric acid. In this paper, the results of experiments on dissolution with 100 g of MOX are described. It was confirmed from the results that the MOX powder to be used at NUCEF was completely dissolved by silver mediated electrolytic oxidation method and that Pu(VI) ion in the obtained solution was reduced to tetravalent by means of NO{sub 2} purging. (author)

  5. Electrically conductive nanostructured silver doped zinc oxide (Ag:ZnO) prepared by solution-immersion technique

    Science.gov (United States)

    Afaah, A. N.; Asib, N. A. M.; Aadila, A.; Mohamed, R.; Rusop, M.; Khusaimi, Z.

    2016-07-01

    p-type ZnO films have been fabricated on ZnO-seeded glass substrate, using AgNO3 as a source of silver dopant by facile solution-immersion. Cleaned glass substrate were seeded with ZnO by mist-atomisation, and next the seeded substrates were immersed in Ag:ZnO solution. The effects of Ag doping concentration on the Ag-doped ZnO have been investigated. The substrates were immersed in different concentrations of Ag dopant with variation of 0, 1, 3, 5 and 7 at. %. The surface morphology of the films was characterized by field emission scanning electron microscope (FESEM). In order to investigate the electrical properties, the films were characterized by Current-Voltage (I-V) measurement. FESEM micrographs showed uniform distribution of nanostructured ZnO and Ag:ZnO. Besides, the electrical properties of Ag-doped ZnO were also dependent on the doping concentration. The I-V measurement result indicated the electrical properties of 1 at. % Ag:ZnO thin film owned highest electrical conductivity.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-05

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

  7. Green synthesis of graphene oxide sheets decorated by silver nanoprisms and their anti-bacterial properties.

    Science.gov (United States)

    Zhang, Danhui; Liu, Xiaoheng; Wang, Xin

    2011-09-01

    A widely soluble graphene oxide sheets decorated by silver nanoprisms were prepared through green synthesis at the room temperature using gelatin as reducing and stabilizing agent. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy and fluorescence spectra. The results demonstrate that these silver-nanoprisms assembled on graphene oxide sheets are flexible and can form stable suspensions in aqueous solutions. Furthermore, the formation mechanism of soluble graphene oxide sheets decorated by silver nanoprisms was successfully explained. The anti-bacterial properties of graphene oxide sheets decorated by silver nanoprisms were tested against Escherichia coli. This work provides a simple and "green" method for the synthesis of graphene oxide sheets decorated by silver nanoprisms in aqueous solution with promising antibacterial property.

  8. Functionalization of textiles with silver and zinc oxide nanoparticles

    Science.gov (United States)

    Pulit-Prociak, Jolanta; Chwastowski, Jarosław; Kucharski, Arkadiusz; Banach, Marcin

    2016-11-01

    The paper presents a method for functionalization of textile materials using fabric dyes modified with silver or zinc oxide nanoparticles. Embedding of these nanoparticles into the structure of other materials makes that the final product is characterized by antimicrobial properties. Indigo and commercially available dye were involved in studies. It is worth to note that silver nanoparticles were obtained in-situ in the reaction of preparing indigo dye and in the process of preparing commercial dye baths. Such a method allows reducing technological steps. The modified dyes were used for dyeing of cotton fibers. The antimicrobial properties of final textile materials were studied. Saccharomyces cerevisiae strain was used in microbiological test. The results confirmed biocidal activity of prepared materials.

  9. Bismuth(V) oxide and silver bismuthate as oxidizing agents for gas-chromatographic elemental microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Shvykin, A.Y.; Platonov, V.V.; Proskuryakov, V.P.; Chilachava, K.B.; Khmarin, E.M.; Kovtun, I.V. [Tolstoy State Pedag University, Tula (Russian Federation)

    2004-07-01

    Bismuth(V) oxide, silver bismuthate, and a mixture of bismuth(V) oxide with fine silver powder were studied as oxidizing additives in gas-chromatographic elemental microanalysis of readily combustible organic substances and coal.

  10. Enhanced Photocatalytic Properties of Silver Oxide Loaded Bismuth Vanadate

    Institute of Scientific and Technical Information of China (English)

    Lianwei Shan; Jinbo Mi; Limin Dong; Zhidong Han; Bo Liu

    2014-01-01

    In this work, BiVO4 powders were synthesized by a sol-gel method, and the BiVO4 gels with different calcination temperature were investigated by X-ray diffraction (XRD). Absorption range and band gap energy, which are respon-sible for the observed photocatalyst behavior, were investigated by UV/vis diffuse reflectance spectroscopy (DRS) for pure and silver oxide loaded BiVO4. Photocatalytic properties of the prepared samples were examined by studying the degradation of the methyl orange. When using NaClO2 as an electron acceptor, the possible photocatalytic mech-anism has been discussed by photocatalytic reactions. With the help of electron acceptor, the results show clearly that the BiVO4 loaded silver oxide exhibited superior photocatalytic activity in simulated dye wastewater treatment.

  11. Low temperature chemical synthesis and comparative studies of silver oxide nanoparticles

    Science.gov (United States)

    Ahmad, Tokeer; Wani, Irshad A.; Al-Hartomy, Omar A.; Al-Shihri, Ayed S.; Kalam, Abul

    2015-03-01

    Silver oxide nanoparticles of various sizes (5-40 nm) have been successfully prepared by sonochemical, solvothermal and microemulsion methods. X-ray diffraction studies reveal the high phase purity of silver oxide nanoparticles with cubic and hexagonal symmetries. Transmission electron microscopic studies show the formation of spherical silver oxide nanoparticles (5-8 nm) using sonochemical and solvothermal methods, however, microemulsion method results in the formation of non spherical silver oxide nanoparticles (10-40 nm). UV-Visible spectroscopy shows the band appearance at 400 nm and 420 nm which correspond to the surface plasmon resonance of silver in silver oxide nanoparticles. Surface area studies give the surface areas of 19.7 m2/g and 12.6 m2/g using the sonochemical and solvothermal methods respectively. Where as surface area of 29.5 m2/g and 13.3 m2/g were obtained for the silver oxide nanoparticles prepared by the microemulsion method using Tergitol and Triton X-100 as the surfactants, respectively.

  12. 乙烯氧化制环氧乙烷银催化剂研究进展%Research Advances in Silver Catalyst of Preparing Ethylene Oxide by Ethylene Oxidation

    Institute of Scientific and Technical Information of China (English)

    刘宗语

    2012-01-01

    综述了乙烯氧化制环氧乙烷银催化剂的重要研究进展。包括通过调整添加组分及配比、改进载体结构、控制载体中各种杂质含量等方法改进载体;通过各种共促进剂的使用、改进载体浸渍方法和催化剂活化过程,提高Ag-Re-Cs体系催化剂的性能;通过低浓度CO2进料、高温预处理、反应抑制剂控制、反应失控控制和使用微通道反应器等工艺方法改善催化剂的使用性能。%The important research advances in silver catalyst of preparing ethylene oxide by ethylene oxidation are summarized in this article. Which includes: improving carrier performance through adjusting additives and thereof proportions, bettering pore structure and controlling various impurity content; improving the performance of Ag-Re-Cs catalyst by means of using kinds of co-promoter to improve carrier impregnation methods and catalyst activation process; optimizing catalyst performance via low concentration of carbon dioxide feeding, high temperature pretreatment, reaction nhibitors controlling, avoiding the danger of reaction out of control and using micro-channel reactor.

  13. Structural studies of lead lithium borate glasses doped with silver oxide

    Science.gov (United States)

    Coelho, João; Freire, Cristina; Hussain, N. Sooraj

    2012-02-01

    Silver oxide doped lead lithium borate (LLB) glasses have been prepared and characterized. Structural and composition characterization were accessed by XRD, FTIR, Raman, SEM and EDS. Results from FTIR and Raman spectra indicate that Ag 2O acts as a network modifier even at small quantities by converting three coordinated to four coordinated boron atoms. Other physical properties, such as density, molar volume and optical basicity are also evaluated. Furthermore, they are also affected by the silver oxide composition.

  14. Preparation of solid silver nanoparticles for inkjet printed flexible electronics with high conductivity

    Science.gov (United States)

    Shen, Wenfeng; Zhang, Xianpeng; Huang, Qijin; Xu, Qingsong; Song, Weijie

    2014-01-01

    Silver nanoparticles (NPs) which could be kept in solid form and were easily stored without degeneration or oxidation at room temperature for a long period of time were synthesized by a simple and environmentally friendly wet chemistry method in an aqueous phase. Highly stable dispersions of aqueous silver NP inks, sintered at room temperature, for printing highly conductive tracks (~8.0 μΩ cm) were prepared simply by dispersing the synthesized silver NP powder in water. These inks are stable, fairly homogeneous and suitable for a wide range of patterning techniques. The inks were successfully printed on paper and polyethylene terephthalate (PET) substrates using a common color printer. Upon annealing at 180 °C, the resistivity of the printed silver patterns decreased to 3.7 μΩ cm, which is close to twice that of bulk silver. Various factors affecting the resistivity of the printed silver patterns, such as annealing temperature and the number of printing cycles, were investigated. The resulting high conductivity of the printed silver patterns reached over 20% of the bulk silver value under ambient conditions, which enabled the fabrication of flexible electronic devices, as demonstrated by the inkjet printing of conductive circuits of LED devices.Silver nanoparticles (NPs) which could be kept in solid form and were easily stored without degeneration or oxidation at room temperature for a long period of time were synthesized by a simple and environmentally friendly wet chemistry method in an aqueous phase. Highly stable dispersions of aqueous silver NP inks, sintered at room temperature, for printing highly conductive tracks (~8.0 μΩ cm) were prepared simply by dispersing the synthesized silver NP powder in water. These inks are stable, fairly homogeneous and suitable for a wide range of patterning techniques. The inks were successfully printed on paper and polyethylene terephthalate (PET) substrates using a common color printer. Upon annealing at 180 °C, the

  15. Preparation of silver nanoparticles at low temperature

    Science.gov (United States)

    Mishra, Mini; Chauhan, Pratima

    2016-04-01

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

  16. 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.

  17. Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

    Institute of Scientific and Technical Information of China (English)

    SONG,Weihong; ZHANG,Xiaoxiao; YIN,Hongzong; SA,Panpan; LIU,Xiaoyan

    2009-01-01

    Silver nanoparticles were obtained by a chemical reduction method using aqueous polymers as dispersant and characterized by UV-Vis spectroscopy,transmission electron microscopy (TEM) and light-scattering spectroscopy.Solid polymer films containing the silver nanoparticles were also prepared after evaporating the solvent,and then dried with existing polymer.The stability of the silver nanoparticles was compared between primary fresh silver nanoparticle solution and redissolved solid polymer films by UV-Vis spectroscopy.The particle size ranged from 5 to l0 rim,and no obvious differences were found.Therefore,preparing solid nano-Ag/polymer was a novel and useful method in storage of silver nanoparticles.

  18. Influence of Metal Oxides on the Arc Erosion Behaviour of Silver Metal Oxides Electrical Contact Materials

    Institute of Scientific and Technical Information of China (English)

    P. Verma; O.P. Pandey; A. Verma

    2004-01-01

    In the present work investigations have been made to see the role of metal oxides on the performance of the silver metal oxides electrical contact materials. Silver metal oxide materials of three different compositions Ag-10CdO, Ag7.6SnO2-2.3In2O3 and Ag-10ZnO were prepared by internal oxidation process under identical processing conditions.These materials were tested for electrical conductivity, hardness, and erosion loss. Performing an accelerated test on the actual contactor assessed the electrical performance, involving erosion loss and temperature rise of the processed materials. The arc-eroded surface was characterized under scanning electron microscope. The study of the eroded surfaces of contacts indicates that the thermal stability of metal oxides depends on nature of silver-metal oxide interface and their mode of erosion. An attempt is made to correlate the surface features of the eroded contacts with the thermal stability of metal oxides.

  19. Photocatalytic oxidation of methane over silver decorated zinc oxide nanocatalysts.

    Science.gov (United States)

    Chen, Xuxing; Li, Yunpeng; Pan, Xiaoyang; Cortie, David; Huang, Xintang; Yi, Zhiguo

    2016-07-20

    The search for active catalysts that efficiently oxidize methane under ambient conditions remains a challenging task for both C1 utilization and atmospheric cleansing. Here, we show that when the particle size of zinc oxide is reduced down to the nanoscale, it exhibits high activity for methane oxidation under simulated sunlight illumination, and nano silver decoration further enhances the photo-activity via the surface plasmon resonance. The high quantum yield of 8% at wavelengths oxide nanostructures shows great promise for atmospheric methane oxidation. Moreover, the nano-particulate composites can efficiently photo-oxidize other small molecular hydrocarbons such as ethane, propane and ethylene, and in particular, can dehydrogenize methane to generate ethane, ethylene and so on. On the basis of the experimental results, a two-step photocatalytic reaction process is suggested to account for the methane photo-oxidation.

  20. Increased DNA damage and oxidative stress among silver jewelry workers.

    Science.gov (United States)

    Aktepe, Necmettin; Kocyigit, Abdurrahim; Yukselten, Yunus; Taskin, Abdullah; Keskin, Cumali; Celik, Hakim

    2015-04-01

    Silver has long been valued as a precious metal, and it is used to make ornaments, jewelry, high-value tableware, utensils, and currency coins. Human exposures to silver and silver compounds can occur oral, dermal, or by inhalation. In this study, we investigated genotoxic and oxidative effects of silver exposure among silver jewelry workers. DNA damage in peripheral mononuclear leukocytes was measured by using the comet assay. Serum total antioxidative status (TAS), total oxidative status (TOS), total thiol contents, and ceruloplasmin levels were measured by using colorimetric methods among silver jewelry workers. Moreover, oxidative stress index (OSI) was calculated. Results were compared with non-exposed healthy subjects. The mean values of mononuclear leukocyte DNA damage were significantly higher than control subjects (p jewelry workers caused oxidative stress and accumulation of severe DNA damage.

  1. Preparation, Characterization and Antibacterial Properties of Silver ...

    African Journals Online (AJOL)

    Methods: A series of silver-chitosan nanoparticles of different sizes were produced ... weight (MW) grades of chitosan by an aqueous chemical reduction method. ... electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic ...

  2. Facile Preparation of Silver Halide Nanoparticles as Visible Light Photocatalysts

    Directory of Open Access Journals (Sweden)

    Linfan Cui

    2015-07-01

    Full Text Available In this study, highly efficient silver halide (AgX-based photocatalysts were successfully fabricated using a facile and template-free direct-precipitation method. AgX nanoparticles, which included silver chloride (AgCl, silver bromide (AgBr and silver iodide (AgI, were synthesized using different potassium halides and silver acetate as reactive sources. The size distribution of the AgX nanopar‐ ticles was determined by the reaction time and ratio of the reagents, which were monitored by UV-vis spectra. The as- prepared AgX nanoparticles exhibited different photoca‐ talytic properties. This shows the differences for the photodegradation of methyl orange and Congo red dyes. In addition, the AgCl nanoparticle-based photocatalyst exhibited the best photocatalytic property among all three types of AgX nanoparticles that are discussed in this study. Therefore, it is a good candidate for removing organic pollutants.

  3. Preparation and characterization of polyimide/silica/silver composite films

    Institute of Scientific and Technical Information of China (English)

    Ning LUO; Zhanpeng WU; Nanxiang MOU; Lizhong JIANG; Dezhen WU

    2008-01-01

    Polyimide/silica/silver hybrid films were pre-pared by the sol-gel method combined with in situ single-stage self-metallization technique.The structure of polyi-mide films in the thermal curing process and the influence of silica content on the migration and aggregation of silver particles to the surface of hybrid films were investigated.The hybrid films were characterized by transmission elec-tron microscopy,dynamic mechanical thermal analysis,Fourier transform infrared spectroscopy,ultraviolet visible spectroscopy and mechanical measurements.The results indicated that there was no degradation of the polyimide matrix after the formation of silica and silver particles.Silica acted as the nucleus for the silver particles.With increasing silica content,more and more silver particles were kept in the hybrid films instead of being migrated onto the surface of the hybrid films and the reflections of hybrid films decreased gradually.

  4. Preparation of amine coated silver nanoparticles using triethylenetetramine

    Indian Academy of Sciences (India)

    L Ramajo; R Parra; M Reboredo; M Castro

    2009-01-01

    This article presents a simple method towards the preparation of functionalized silver nanoparticles 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 with X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), UVvisible spectroscopy, thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM). Monocrystalline silver particles with cubic structure and an average size of 20 nm were obtained. The results reveal that it is possible to synthesize Ag nanoparticles functionalized with amine groups and that particle size is influenced by the processing route.

  5. Preparation and Electrochemical Properties of Silver Doped Hollow Carbon Nanofibers

    Directory of Open Access Journals (Sweden)

    LI Fu

    2016-11-01

    Full Text Available Silver doped PAN-based hollow carbon nanofibers were prepared combining co-electrospinning with in situ reduction technique subsequently heat treatment to improve the electrochemical performances of carbon based supercapacitor electrodes. The morphology, structure and electrochemical performances of the resulted nanofiber were studied. The results show that the silver nanoparticles can be doped on the surface of hollow carbon nanofibers and the addition of silver favors the improvement of the electrochemical performances, exhibiting the enhanced reversibility of electrode reaction and the capacitance and the reduced charge transfer impedance.

  6. Preparation of sintered silver nanosheets by coating technique using silver carbamate complex

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Hee-Yong; Cha, Jae-Ryung; Gong, Myoung-Seon, E-mail: msgong@dankook.ac.kr

    2015-03-01

    This study describes a coating technique approach for large-scale preparation of sintered silver nanosheets whose lateral dimensions were controlled in the thickness range of 50–65 nm. These procedures involved coating water-soluble poly (vinyl alcohol) (PVA) and silver 2-ethylhexylcarbamate (Ag-EHC), as well as thermal reduction of a silver precursor by heating at 150 °C, followed by dissolving away the PVA layer with alcoholic water. When the silver carbamate layer on the PVA layer was heated to 150 °C, the silver carbamate layer was thermally reduced and directed to grow into uniform sintered nanosheets with aspect ratios as high as 1000. The multi-stacked PVA/Ag structures and sintered silver nanosheets were confirmed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Measurements of the conductive property at room temperature indicated that these nanosheets were electrically continuous with a resistivity of approximately 7.3 × 10{sup −6} Ω cm. - Highlights: • A coating technique is used to make sintered Ag nanosheets. • PVA and silver carbamate act as a separation layer and a silver precursor. • The Ag nanosheets have thickness width 50–60 nm and width up to hundred μm. • The Ag nanosheets showed a resistivity of ca. 7.3 × 10{sup −6} Ω cm.

  7. Visualizing the mobility of silver during catalytic soot oxidation

    DEFF Research Database (Denmark)

    Gardini, Diego; Christensen, Jakob M.; Damsgaard, Christian Danvad;

    2016-01-01

    The catalytic activity and mobility of silver nanoparticles used as catalysts in temperature programmed oxidation of soot:silver (1:5 wt:wt) mixtures have been investigated by means of flow reactor experiments and in situ environmental transmission electron microscopy (ETEM). The carbon oxidation...... mobility during the soot oxidation, and this mobility, which increases the soot/catalyst contact, is expected to be an important factor for the lower oxidation temperature. In the intimate tight contact mixture the initial dispersion of the silver particles is greater,,and the onset of mobility occurs...

  8. Preparation of starch-stabilized silver nanoparticles from amylose-sodium palmitate inclusion complexes

    Science.gov (United States)

    Starch-stabilized silver nanoparticles were prepared from amylose-sodium palmitate complexes by first converting sodium palmitate to silver palmitate by reaction with silver nitrate and then reducing the silver ion to metallic silver. This process produced water solutions that could be dried and the...

  9. Sonochemical synthesis of silver vanadium oxide micro/nanorods: solvent and surfactant effects.

    Science.gov (United States)

    Mohandes, Fatemeh; Salavati-Niasari, Masoud

    2013-01-01

    In this investigation, a facile sonochemical route has been developed for the preparation of silver vanadium oxide (SVO) micro/nanorods by using silver salicylate and ammonium metavanadate as silver and vanadate precursor, respectively. Here, silver salicylate, [Ag(HSal)], is introduced as a new silver precursor to fabricate AgVO(3) nanorods. The effect of numerous solvents and surfactants on the morphology and sonochemical formation mechanism of AgVO(3) nanorods was studied. AgVO(3) nanorods were characterized by SEM and TEM images, XRD patterns, FT-IR, XPS, and EDS spectroscopy. SEM, TEM, and XRD results showed that AgO nanoparticles were formed onto AgVO(3) nanorods in the presence of ethanol, cyclohexanol, dimethylsulfoxide (DMSO), and acetone. By using polyethylene glycol (PEG-6000) and N,N-dimethylformamide (DMF) as organic additives, the thickness of AgVO(3) nanorods decreased.

  10. Functional Iron Oxide-Silver Hetero-Nanocomposites: Controlled Synthesis and Antibacterial Activity

    Science.gov (United States)

    Trang, Vu Thi; Tam, Le Thi; Van Quy, Nguyen; Huy, Tran Quang; Thuy, Nguyen Thanh; Tri, Doan Quang; Cuong, Nguyen Duy; Tuan, Pham Anh; Van Tuan, Hoang; Le, Anh-Tuan; Phan, Vu Ngoc

    2017-02-01

    Iron oxide-silver nanocomposites are of great interest for their antibacterial and antifungal activities. We report a two-step synthesis of functional magnetic hetero-nanocomposites of iron oxide nanoparticles and silver nanoparticles (Fe3O4-Ag). Iron oxide nanoparticles were prepared first by a co-precipitation method followed by the deposition of silver nanoparticles via a hydrothermal route. The prepared Fe3O4-Ag hetero-nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy and vibrating sample magnetometry. Their antibacterial activities were investigated by using paper-disc diffusion and direct-drop diffusion methods. The results indicate that the Fe3O4-Ag hetero-nanocomposites exhibit excellent antibacterial activities against two Gram-negative bacterial strains (Salmonella enteritidis and Klebsiella pneumoniae).

  11. XPS study of silver, nickel and bimetallic silver-nickel nanoparticles prepared by seed-mediated growth

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Pilar, E-mail: pilar.prieto@uam.es [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales ' Nicolas Cabrera' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Nistor, Valentin [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales ' Nicolas Cabrera' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Nouneh, Khalid [Institute for Nanomaterials and Nanotechnology (INANOTECH), Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), ENSET, Av. Armee Royale, 10100, Rabat (Morocco); Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8520 (Japan); Oyama, Munetaka [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8520 (Japan); Abd-Lefdil, Mohammed [Laboratory of Materials Physics, University Mohammed V-Agdal, Rabat (Morocco); Diaz, Raquel [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales ' Nicolas Cabrera' , Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer We have prepared Ag, Ni and AgNi NPs by derived seed-mediated growth method. Black-Right-Pointing-Pointer The combined use of optical, structural and chemical characterization techniques allows to determine the presence of core-shell structures. Black-Right-Pointing-Pointer The oxidation states of Ag and Ni at the outer layers of the NPs have been studied by XPS. Black-Right-Pointing-Pointer Ag NPs are purely metallic with a fcc structure. Black-Right-Pointing-Pointer Ni NPs are formed by Ni core-NiO + Ni(OH){sub 2} shell structure. Black-Right-Pointing-Pointer Ag core-NiO + Ni(OH){sub 2} shell structure is determined for AgNi NPs, with oxidized silver atoms at the interface. - Abstract: The chemical structure of silver, nickel and bimetallic silver-nickel nanoparticles, i.e. Ag, Ni and AgNi NPs, with sizes {<=}35 nm, obtained by derived seed-mediated growth method on transparent and conductive indium tin oxide (ITO) substrates, has been studied by a comparative X-ray photoelectron spectroscopy (XPS) analysis of Ag 3d, Ni 2p and O1s core levels in combination with X-ray diffraction and optical absorption spectroscopy in the visible range. XPS indicates that the surface of Ag NPs is not oxidized, while Ni NPs are clearly oxidized to nickel oxide and hydroxide. Absorptions at 384 and 600 nm in Ni optical spectrum are consistent with the presence of nickel in oxidized state; however the presence of metallic Ni 2p signal in Ni XPS spectrum indicates that a metallic nickel core is still present. In the case of bimetallic AgNi NPs, the XPS results are consistent with the presence of metallic silver core surrounded by NiO + Ni(OH){sub 2} shell. XPS spectra also show the presence of Ag{sub 2}O at the interface between the Ag metallic core and the oxidized nickel shell. XRD patterns of AgNi and Ag NPs show the typical fcc structure of metallic silver, confirming the presence of Ag metallic core in AgNi NPs. The surface plasmon

  12. Ultrafine Silver Peroxide Powders Prepared by Ozone Oxidization Method and Its Antibacterial Property%臭氧氧化法制备超细AgO粉末及其抗菌性能研究

    Institute of Scientific and Technical Information of China (English)

    沈文宁; 冯拉俊; 孔珍珍; 冯慧

    2011-01-01

    In view of the existing problems that the particle size of prepared powders is large, AgO content is low, the requirement for equipment is high and waste solution caused environmental pollution is produced in preparation process, in this paper ultrafine silver peroxide powders were prepared by chemical oxidation method using pollution-free ozone as oxidant.Effects of factors such as reaction temperature, initial pH value and ozone input time on silver peroxide content were studied.The prepared products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and shake-flask method.The results show that ultrafine powders with a AgO content of 83.56%, a platy morphology and a thickness around 100 nm are prepared in conditions of reaction temperature 45 ℃, initial pH value 14, ozone input time 5 h.There are only Ag and O elements in powders which silver exists mainly in the forms of monoclinic AgO and little cubic Ag2O.AgO possesses strong antibacterial ability.When the concentration of antibacterial agent is 1 mg·L-1 and acting time is 30 min, the bactericidal rates of powders with a AgO content of 83.56% against S.aureus and E.coli both exceed 99.9%.And in the same condition, the bactericidal rates of AgO are 7 times higher than that of Ag2O in 5 min.%针对现有方法制备AgO粉末存在粒径大、含量低、对设备要求高、制备过程产生污染环境的废液等问题,以无污染的臭氧为氧化剂,通过化学氧化法制备超细AgO粉末.研究了反应温度、初始pH值、臭氧通入时间等因素对AgO含量的影响.利用XRD,XPS,SEM,烧瓶振荡法对制备产物进行表征.结果表明,当反应温度为45℃、初始pH值为14、臭氧通入时间为5 h时,制得形状为板状,厚度约为100 nm,AgO含量为83.56%的超细粉末;粉末中只含有Ag,O两种元素,Ag主要以单斜AgO和少量的立方Ag2O形式存在;AgO具有强的抗菌能力,1 mg·L-1AgO含量为83.56%的粉

  13. Enantioselective silver nanoclusters: Preparation, characterization and photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Farrag, Mostafa, E-mail: mostafafarrag@aun.edu.eg

    2016-09-01

    prepared silver nanoclusters were investigated using nitrogen adsorption-desorption at −196 °C. Specific surface area S{sub BET}, pore volume and average pore diameter were calculated. - Highlights: • New wet chemistry method to prepare mirror image small silver clusters protected by penicillamine. • Preparation enantioselective catalysts by easy wet chemistry method. • The synthesized silver clusters have photoluminescence properties. • The synthesized silver clusters show high Anisotropy factors up to 3 × 10{sup −4}. • The adsorption isotherms of all synthesized clusters are mainly of type II of Brunaue’s classification.

  14. Antibacterial properties of composite resins incorporating silver and zinc oxide nanoparticles on Streptococcus mutans and Lactobacillus

    Directory of Open Access Journals (Sweden)

    Shahin Kasraei

    2014-05-01

    Full Text Available Objectives Recurrent caries was partly ascribed to lack of antibacterial properties in composite resin. Silver and zinc nanoparticles are considered to be broad-spectrum antibacterial agents. The aim of the present study was to evaluate the antibacterial properties of composite resins containing 1% silver and zinc-oxide nanoparticles on Streptococcus mutans and Lactobacillus. Materials and Methods Ninety discoid tablets containing 0%, 1% nano-silver and 1% nano zinc-oxide particles were prepared from flowable composite resin (n = 30. The antibacterial properties of composite resin discs were evaluated by direct contact test. Diluted solutions of Streptococcus mutans (PTCC 1683 and Lactobacillus (PTCC 1643 were prepared. 0.01 mL of each bacterial species was separately placed on the discs. The discs were transferred to liquid culture media and were incubated at 37℃ for 8 hr. 0.01 mL of each solution was cultured on blood agar and the colonies were counted. Data was analyzed with Kruskall-Wallis and Mann-Whitney U tests. Results Composites containing nano zinc-oxide particles or silver nanoparticles exhibited higher antibacterial activity against Streptococcus mutans and Lactobacillus compared to the control group (p < 0.05. The effect of zinc-oxide on Streptococcus mutans was significantly higher than that of silver (p < 0.05. There were no significant differences in the antibacterial activity against Lactobacillus between composites containing silver nanoparticles and those containing zinc-oxide nanoparticles. Conclusions Composite resins containing silver or zinc-oxide nanoparticles exhibited antibacterial activity against Streptococcus mutans and Lactobacillus.

  15. Electrical and optical properties of reactive DC magnetron sputtered silver oxide thin films: role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Kumar Barik, Ullash; Srinivasan, S.; Nagendra, C.L.; Subrahmanyam, A

    2003-04-01

    Silver oxide thin films have been prepared on soda lime glass substrates at room temperature (300 K) by reactive DC Magnetron sputtering technique using pure silver metal target; the oxygen flow rates have been varied in the range 0.00-2.01 sccm. The X-ray diffraction data on these films show a systematic change from metallic silver to silver (sub) oxides. The electrical resistivity increases with increasing oxygen flow. The films show a p-type behavior (by both Hall and Seebeck measurements) for the oxygen flow rates of 0.54, 1.09 and 1.43 sccm. The refractive index of the films (at 632.8 nm) decreases with increasing oxygen content and is in the range 1.167-1.145, whereas the p-type films show a higher refractive index (1.186-1.204). The work function of these silver oxide films has been measured by Kelvin Probe technique. The results, in specific, the p-type conductivity in the silver oxide films, have been explained on the basis of the theory of partial ionic charge proposed by Sanderson.

  16. Preparation of Silver Nanostructures from Bicontinuous Microemulsions

    Directory of Open Access Journals (Sweden)

    M. A. Pedroza-Toscano

    2012-01-01

    Full Text Available Precipitation of silver nanoparticles at 70°C was carried out by dosing a 1.3 M sodium borohydride aqueous solution over bicontinuous microemulsions formed with a mixture of sodium bis(2-ethylhexyl sulfosuccinate (AOT and sodium dodecylsulfate (SDS as surfactants, a 0.5 M silver nitrate aqueous solution, and toluene. Weight ratios of 2.5/1 and 3/1 AOT/SDS were used in the precipitation reactions. Silver nanoparticles were characterized by transmission electronic microscopy, X-ray diffraction, and atomic absorption spectroscopy. A mixture of isolated spheroidal nanoparticles (≈15 wt.% with an average diameter around 10 nm and wormlike structures (≈85 wt.% with an average length close to 480 nm and an average diameter ca. 40 nm was obtained, regardless of the AOT/SDS ratio. Higher yields were obtained compared with those reported when reverse microemulsions were employed. Formation of wormlike structures was ascribed to one-dimensional aggregation of crystal and particles within the channels of bicontinuous microemulsions, which performed as templates.

  17. Silver confined within zeolite EMT nanoparticles: preparation and antibacterial properties

    Science.gov (United States)

    Dong, B.; Belkhair, S.; Zaarour, M.; Fisher, L.; Verran, J.; Tosheva, L.; Retoux, R.; Gilson, J.-P.; Mintova, S.

    2014-08-01

    The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps.The preparation of pure zeolite nanocrystals (EMT-type framework) and their silver ion-exchanged (Ag+-EMT) and reduced silver (Ag0-EMT) forms is reported. The template-free zeolite nanocrystals are stabilized in water suspensions and used directly for silver ion-exchange and subsequent chemical reduction under microwave irradiation. The high porosity, low Si/Al ratio, high concentration of sodium and ultrasmall crystal size of the EMT-type zeolite permitted the introduction of a high amount of silver using short ion-exchange times in the range of 2-6 h. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against Escherichia coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not

  18. Antibacterial wound dressing from chitosan/polyethylene oxide nanofibers mats embedded with silver nanoparticles.

    Science.gov (United States)

    Wang, Xiaoli; Cheng, Feng; Gao, Jing; Wang, Lu

    2015-03-01

    Novel antibacterial nanomaterials have been developed for biomedical applications. The present study involves the preparation and properties of antibacterial nanofibers from chitosan/polyethylene oxide electrospun nanofibers incorporated with silver nanoparticles. Silver nanoparticles were efficiently synthesized in situ after ultra violet (UV) with AgNO3 as precursor and chitosan/polyethylene oxide as reducing agent and protecting agent, respectively. Then the resultant solutions were electrospun into nanofibers. The formation of silver nanoparticles was confirmed with ultraviolet visible (UV-vis) and transmission electron microscopy (TEM), and the electrospun nanofibers were characterized by scanning electron microscopy and energy dispersive X-ray. The resultant fibers exhibited uniform morphology with silver nanoparticles distributed throughout the fiber. Also, the fibers showed certain tensile strength and excellent antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Sustained release of silver nanoparticles from fibers could last for over 72 h. The silver-containing chitosan/polyethylene oxide nanofibers showed excellent cytocompatibility.

  19. Preparation of Phenolic Resin/Silver Nanocomposites via in-situ Reduction

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Resol type phenolic resin/silver nanocomposite was prepared by in-situ reduction method, in which the curing of phenolic resin and the formation of silver nano-particles took place simultaneously. The silver ions were reduced completely to silver nanoparticles, which were dispersed homogeneously in the resin matrix with narrow size distribution.

  20. Hybrid Copper-Silver Conductive Tracks for Enhanced Oxidation Resistance under Flash Light Sintering.

    Science.gov (United States)

    Yim, Changyong; Sandwell, Allen; Park, Simon S

    2016-08-31

    We developed a simple method to prepare hybrid copper-silver conductive tracks under flash light sintering. The developed metal nanoparticle-based ink is convenient because its preparation process is free of any tedious washing steps. The inks were composed of commercially available copper nanoparticles which were mixed with formic acid, silver nitrate, and diethylene glycol. The role of formic acid is to remove the native copper oxide layer on the surface of the copper nanoparticles. In this way, it facilitates the formation of a silver outer shell on the surface of the copper nanoparticles through a galvanic replacement. In the presence of formic acid, the copper nanoparticles formed copper formate, which was present in the unsintered tracks. However, under illumination by a xenon flash light, the copper formate was then converted to copper. Moreover, the resistance of the copper-only films increased by 6 orders of magnitude when oxidized at high temperatures (∼220 °C). However, addition of silver nitrate to the inks suppressed the oxidation of the hybrid copper-silver films, and the resistance changes in these inks at high temperatures were greatly reduced. In addition, the hybrid inks proved to be advantageous for use in electrical circuits as they demonstrated a stable electrical conductivity after exposure to ambient air at 180 °C.

  1. Antibacterial effects of electrospun chitosan/poly(ethylene oxide) nanofibrous membranes loaded with chlorhexidine and silver.

    Science.gov (United States)

    Song, Jiankang; Remmers, Stefan J A; Shao, Jinlong; Kolwijck, Eva; Walboomers, X Frank; Jansen, John A; Leeuwenburgh, Sander C G; Yang, Fang

    2016-07-01

    To prevent percutaneous device associated infections (PDAIs), we prepared electrospun chitosan/poly(ethylene oxide) (PEO) nanofibrous membrane containing silver nanoparticles as an implantable delivery vehicle for the dual release of chlorhexidine and silver ions. We observed that the silver nanoparticles were distributed homogeneously throughout the fibers, and a fast release of chlorhexidine in 2days and a sustained release of silver ions for up to 28days. The antibacterial efficacy of the membranes against Staphylococcus aureus showed that the membranes exhibited an obvious inhibition zone upon loading with either chlorhexidine (20μg or more per membrane) or AgNO3 (1 and 5wt% to polymer). Furthermore, long-term antibacterial effect up to 4days was verified using membranes containing 5wt% AgNO3. The results suggest that the membranes have strong potential to act as an active antibacterial dressing for local delivery of antibacterial agents to prevent PDAIs.

  2. Oxidative dissolution of silver nanoparticles: A new theoretical approach.

    Science.gov (United States)

    Adamczyk, Zbigniew; Oćwieja, Magdalena; Mrowiec, Halina; Walas, Stanisław; Lupa, Dawid

    2016-05-01

    A general model of an oxidative dissolution of silver particle suspensions was developed that rigorously considers the bulk and surface solute transport. A two-step surface reaction scheme was proposed that comprises the formation of the silver oxide phase by direct oxidation and the acidic dissolution of this phase leading to silver ion release. By considering this, a complete set of equations is formulated describing oxygen and silver ion transport to and from particles' surfaces. These equations are solved in some limiting cases of nanoparticle dissolution in dilute suspensions. The obtained kinetic equations were used for the interpretation of experimental data pertinent to the dissolution kinetics of citrate-stabilized silver nanoparticles. In these kinetic measurements the role of pH and bulk suspension concentration was quantitatively evaluated by using the atomic absorption spectrometry (AAS). It was shown that the theoretical model adequately reflects the main features of the experimental results, especially the significant increase in the dissolution rate for lower pH. Also the presence of two kinetic regimes was quantitatively explained in terms of the decrease in the coverage of the fast dissolving oxide layer. The overall silver dissolution rate constants characterizing these two regimes were determined.

  3. Silver Modified Degussa P25 for the Photocatalytic Removal of Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Neil Bowering

    2007-01-01

    Full Text Available A study of the photocatalytic behaviour of silver modified titanium dioxide materials for the decomposition and reduction of nitric oxide (NO gas has been carried out. The effects of silver loading, calcination temperature, and reaction conditions have been investigated. Prepared photocatalysts were characterised using XRD, TEM, and XPS. A continuous flow reactor was used to determine the photocatalytic activity and selectivity of NO decomposition in the absence of oxygen as well as NO reduction using CO as the reducing agent, over the prepared photocatalysts. XRD and TEM analysis of the photocatalysts showed that crystalline silver nitrate particles were present on the titanium dioxide surface after calcination at temperatures of up to 200∘C. The silver nitrate particles are thermally decomposed to form metallic silver clusters at higher temperatures. XPS analysis of the photocatalysts showed that for each of the temperatures used, both Ag+ and Ag0 were present and that the Ag0/Ag+ ratio increased with increasing calcination temperature. The presence of metallic silver species on the TiO2 surface dramatically increased the selectivity for N2 formation of both decomposition and reduction reactions. When CO was present in the reaction gas, selectivities of over 90% were observed for all the Ag-TiO2 photocatalysts that had been calcined at temperatures above 200∘C. Unfortunately these high selectivities were at the expense of photocatalytic activity, with lower NO conversion rates than those achieved over unmodified TiO2 photocatalysts.

  4. Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts

    DEFF Research Database (Denmark)

    Beier, Matthias Josef; Schimmoeller, Bjoern; Hansen, Thomas Willum

    2010-01-01

    an elevated pressure was required. Carboxylic acids, such as benzoic acid or p-toluic acid, additionally increased the reaction rate while CeO2 could act both as a promoter and an inhibitor depending on the substrate and the reaction conditions. Silver catalysts were prepared both by standard impregnation......Silver supported on silica effectively catalyzes the aerobic side-chain oxidation of alkyl aromatic compounds under solvent-free conditions. Toluene, p-xylene, ethylbenzene and cumene were investigated as model substrates. Typically, the reaction was performed at ambient pressure; only for toluene...... and flame spray pyrolysis. Addition of a Ce precursor to the FSP catalyst resulted in significantly smaller silver particles. Ce-doped FSP catalysts in general exhibited a superior catalytic performance with TONs up to 2000 except for cumene oxidation that appeared to proceed mainly by homogeneous catalysis...

  5. Fluorescence Microscopy of Nanoscale Silver Oxide Thin Films

    Institute of Scientific and Technical Information of China (English)

    PAN Xin-Yu; JIANG Hong-Bing; LIU Chun-Ling; GONG Qi-Huang; ZHANG Xi-Yao; ZHANG Qi-Feng; XU Bei-Xue; WU Jin-Lei

    2003-01-01

    The experimental conditions for photoactivated intermittent fluorescence from nanoscale silver oxide were studied with fluorescence microscopy. Strong fluorescence was observed from the Ag?O particles with size of 10-20nm excited with both blue and green light. We observed the saturation of photoexcitation with blue light and explained the experimental results using the model of agglomeration of silver atoms to form small clusters and the fluorescence of Ag2 and Ags clusters.

  6. Cadmium, lead and silver adsorption in hydrous niobium oxide(V) prepared by precipitation in homogeneous solution method; Adsorcao de chumbo, cadmio e prata em oxido de niobio(V) hidratado preparado pelo metodo da precipitacao em solucao homogenea

    Energy Technology Data Exchange (ETDEWEB)

    Tagliaferro, Geronimo V.; Pereira, Paulo Henrique F.; Rodrigues, Liana Alvares; Silva, Maria Lucia Caetano Pinto da, E-mail: fernandes_eng@yahoo.com.b [Universidade de Sao Paulo (USP), Lorena, SP (Brazil). Escola de Engenharia. Dept. de Engenharia Quimica

    2011-07-01

    This paper describes the adsorption of heavy metals ions from aqueous solution by hydrous niobium oxide. Three heavy metals were selected for this study: cadmium, lead and silver. Adsorption isotherms were well fitted by Langmuir model. Maximum adsorption capacity (Q{sub 0}) for Pb{sup 2+}, Ag{sup +} and Cd{sup 2+} was found to be 452.5, 188.68 and 8.85 mg g{sup -1}, respectively. (author)

  7. Preparation And Study Of Electrodeposited Silver-Nickel Binary System

    Science.gov (United States)

    Santhi, Kalavathy; Narmatha, R.; Narayanan, V.; Stephen, A.

    2011-06-01

    Ag-Ni binary system was prepared by the method of pulsed electrodeposition from an electrolyte that consisted of silver nitrate and nickel sulfate along with the complexing agents thiourea and sodium gluconate. The depositions were carried out by applying short current pulses of different current densities through electrolytes of same composition. The deposits were characterized using X-ray diffraction, vibrating sample magnetometer, energy dispersive X-ray analysis and SEM. The samples in their as prepared form exhibit ferromagnetic properties. This study shows that it is possible to simultaneously deposit the two immiscible constituents Ag and Ni with desired magnetic properties in pulsed electrolysis.

  8. Enhanced photocatalytic activity of silver nanoparticles modified TiO{sub 2} thin films prepared by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Meng Fanming, E-mail: mrmeng@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230039 (China); State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China); Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei 230039 (China); Sun Zhaoqi [School of Physics and Materials Science, Anhui University, Hefei 230039 (China); Anhui Key Laboratory of Information Materials and Devices, Anhui University, Hefei 230039 (China)

    2009-12-15

    Ag-TiO{sub 2} nanostructured thin films with silver volume fraction of 0-40% were prepared by RF magnetron sputtering. The microstructure, surface topography, and optical properties of the films were characterized by X-ray diffractometer, transmission electron microscope, and ultraviolet-visible spectrophotometer. Photocatalytic activity of the films was evaluated by light-induced degradation of methyl orange (C{sub 14}H{sub 14}N{sub 3}NaO{sub 3}S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and silver content was studied in detail. It is found that silver content influences microstructure of TiO{sub 2} thin films, and silver in the films is metallic Ag (Ag{sup 0}). Photocatalytic activity of the films increases with increasing silver content up to 5 vol.% Ag and then decreases to values significantly still bigger than that of pure TiO{sub 2} thin films. Silver nanoparticles significantly enhance the photocatalytic activity of TiO{sub 2} films. The better separation between electrons and holes on silver modified TiO{sub 2} thin films surface allowed more efficiency for the oxidation and reduction reactions. The enhanced photocatalytic activity was mainly attributed to the decrease of energy gap of the films and the increase of oxygen anion radicals O{sub 2}{sup -} and reactive center of surface Ti{sup 3+} on silver modified TiO{sub 2} thin films surface.

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

    Science.gov (United States)

    Ahn, Yumi; Jeong, Youngjun; Lee, Youngu

    2012-12-01

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

  10. Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

    DEFF Research Database (Denmark)

    Hyllested, Jes Ærøe; Espina Palanco, Marta; Hagen, Nicolai

    2015-01-01

    Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges...... microscopy shows that the shapes of the nanoparticles are different depending on the fruit used for preparation. The green preparation process results mainly in individual nanoparticles with a very poor tendency to form aggregates with narrow gaps even when aggregation is forced by the addition of Na...... absorption correlates with the decrease of absorption band in the UV. This confirms the evolution of silver nanoparticles from silver clusters. The presence of various silver clusters on the surface of the “green” plasmonic silver nanoparticles is also supported by a strong multi-color luminesce signal...

  11. Synthesis and Characterization of Sol-Gel Prepared Silver Nanoparticles

    Science.gov (United States)

    Ahlawat, Dharamvir Singh; Kumari, Rekha; Rachna; Yadav, Indu

    2014-03-01

    Silver nanoparticles (SNPs) have been successfully prepared using sol-gel method by annealing the sample at 550°C for 30 min. The SNPs were not confirmed by X-ray diffraction (XRD) analysis when the annealing temperature was considered at 450°C. They were also not confirmed without calcination of the sample. The physical mechanism of silver clusters formation in the densified silica matrix with respect to thermal treatment has been understood. The presence of silver metal in the silica matrix was confirmed by XRD analysis and TEM image of the samples. The average size of nanoparticles dispersed in silica matrix was determined as 10.2 nm by the XRD technique. The synthesized nanocomposites were also characterized by UV-Visible spectroscopy with a peak in the absorption spectra at around 375 nm. The distribution of particle size has been reported here in the range from 8 nm to 25 nm by TEM observations of the sample prepared at 550°C. The spherically smaller size (≈10 nm) SNPs have reported the surface plasmons resonance (SPR) peak less than or near to 400 nm due to blue-shifting and effect of local refractive index. Without annealing the silica samples the absorption spectra does not show any peak around 375 nm. The FTIR spectroscopy of the three types of samples prepared at different temperatures (room temperature, 450°C and 550°C) has also been reported. This spectra have provided the identification of different chemical groups in the prepared samples. It has been predicted that the size of SNPs by XRD, UV-Visible and TEM results have agreed well with each other. It may be concluded that formation of SNPs is a function of annealing temperature.

  12. Preparation of tungsten oxide

    Science.gov (United States)

    Bulian, Christopher J.; Dye, Robert C.; Son, Steven F.; Jorgensen, Betty S.; Perry, W. Lee

    2009-09-22

    Tungsten trioxide hydrate (WO.sub.3.H.sub.2O) was prepared from a precursor solution of ammonium paratungstate in concentrated aqueous hydrochloric acid. The precursor solution was rapidly added to water, resulting in the crash precipitation of a yellow white powder identified as WO.sub.3.H.sub.2O nanosized platelets by x-ray diffraction and scanning electron microscopy. Annealing of the powder at 200.degree. C. provided cubic phase WO.sub.3 nanopowder, and at 400.degree. C. provided WO.sub.3 nanopowder as a mixture of monoclinic and orthorhombic phases.

  13. The Salts of Fatty Acids as Precursors for Preparation of Silver Nanoparticles in Organic Solvents

    Directory of Open Access Journals (Sweden)

    V. N. Glushko

    2016-08-01

    Full Text Available The silver salts of fatty acids were studied as precursors for the preparation of colloidal dispersions of silver nanoparticles and UHMWPE (ultra-high-molecular-weight polyethylene composite with silver nanoparticles, as well as the composition, the spectra and SEM (scanning electron microscopy results.

  14. Preparation and characterization of silver colloids with different morphologies under ultrasonic field

    Institute of Scientific and Technical Information of China (English)

    Cheng Jingquan; Yao Suwei; Zhang Weiguo; Zou Yi

    2006-01-01

    In the ultrasonic field,stable silver colloids were produced by the reduction of AgNO3 with the protection of PVP using KBH4 or N2H4.H2O as reductant.The main factors affecting the morphology of silver nanoparticles,such as distribution of the ultrasonic field,ultrasonic time,ultrasonic power,and the species of reductant,were studied.The silver colloids were identified by TEM and spectrophotometry.The results indicate that the factors such as distribution of the ultrasonic field,ultrasonic time,ultrasonic power,and the species of reductant have a great impact on the morphology of the silver nanoparticles.The size of the silver nanoparticles decreases with the ultrasonic power and ultrasonic time increasing.Ag nanoparticles prepared in standing wave field preferentially grow in a certain direction,which is propitious for forming hexagonal- and spherical-like silver nanoparticles.Monodispersed spherical silver nanoparticles are easily synthesized in the diffusion field.The stability of silver colloid becomes improved by ultrasonic treatment.For example,precipitate is not found after several weeks for the silver colloid prepared with an ultrasonic treatment time of 180 min.The silver nanoparticles prepared without ultrasonic treatment are large spherical-like and hexagonal.Well-dispersed spherical silver particles with a mean size of about 20 nm have been prepared under ultrasonic treatment.Spherical,spherical-like,and hexagonal silver nanoparticles can be obtained by changing the reductants..

  15. Controlled graphene oxide assembly on silver nanocube monolayers for SERS detection: dependence on nanocube packing procedure

    Directory of Open Access Journals (Sweden)

    Martina Banchelli

    2016-01-01

    Full Text Available Hybrid graphene oxide/silver nanocubes (GO/AgNCs arrays for surface-enhanced Raman spectroscopy (SERS applications were prepared by means of two procedures differing for the method used in the assembly of the silver nanocubes onto the surface: Langmuir–Blodgett (LB transfer and direct sequential physisorption of silver nanocubes (AgNCs. Adsorption of graphene oxide (GO flakes on the AgNC assemblies obtained with both procedures was monitored by quartz crystal microbalance (QCM technique as a function of GO bulk concentration. The experiment provided values of the adsorbed GO mass on the AgNC array and the GO saturation limit as well as the thickness and the viscoelastic properties of the GO film. Atomic force microscopy (AFM measurements of the resulting samples revealed that a similar surface coverage was achieved with both procedures but with a different distribution of silver nanoparticles. In the GO covered LB film, the AgNC distribution is characterized by densely packed regions alternating with empty surface areas. On the other hand, AgNCs are more homogeneously dispersed over the entire sensor surface when the nanocubes spontaneously adsorb from solution. In this case, the assembly results in less-packed silver nanostructures with higher inter-cube distance. For the two assembled substrates, AFM of silver nanocubes layers fully covered with GO revealed the presence of a homogeneous, flexible and smooth GO sheet folding over the silver nanocubes and extending onto the bare surface. Preliminary SERS experiments on adenine showed a higher SERS enhancement factor for GO on Langmuir–Blodgett films of AgNCs with respect to bare AgNC systems. Conversely, poor SERS enhancement for adenine resulted for GO-covered AgNCs obtained by spontaneous adsorption. This indicated that the assembly and packing of AgNCs obtained in this way, although more homogeneous over the substrate surface, is not as effective for SERS analysis.

  16. Simplified kinetic models of methanol oxidation on silver

    DEFF Research Database (Denmark)

    Andreasen, Anders; Lynggaard, Hasse Harloff; Stegelmann, Carsten;

    2005-01-01

    Recently the authors developed a microkinetic model of methanol oxidation on silver [A. Andreasen, H. Lynggaard, C. Stegelmann, P. Stoltze, Surf. Sci. 544 (2003) 5–23]. The model successfully explains both surface science experiments and kinetic experiments at industrial conditions applying...

  17. Simplified kinetic models of methanol oxidation on silver

    DEFF Research Database (Denmark)

    Andreasen, A.; Lynggaard, H.; Stegelmann, C.;

    2005-01-01

    Recently the authors developed a microkinetic model of methanol oxidation on silver [A. Andreasen, H. Lynggaard, C. Stegelmann, P. Stoltze, Surf. Sci. 544 (2003) 5-23]. The model successfully explains both surface science experiments and kinetic experiments at industrial conditions applying...

  18. Fabrication of dendritic silver-coated copper powders by galvanic displacement reaction and their thermal stability against oxidation

    Science.gov (United States)

    Park, Yu-Seon; An, Chang Yong; Kannan, Padmanathan Karthick; Seo, Nary; Zhuo, Kai; Yoo, Tae Kyong; Chung, Chan-Hwa

    2016-12-01

    Two steps of wet chemical processes have been developed for the preparation of core-shell nanostructures of copper and silver, which is a facile and low cost method for the production of large quantity of dendritic powders. First step involves a galvanic displacement reaction with hydrogen evolution which is the motive force of spontaneous electrochemical reaction. To achieve the core-shell structure, silver has been coated on the dendritic copper using the galvanic displacement reaction. The dendritic silver-coated copper powders exhibit high surface-area, excellent conductivity, and good oxidation resistance. It has been found that silver-coated copper powders maintain the electrical conductivity even after annealing at 150 °C for several to tens of minutes, thus it is a promising material and an alternative to pure silver powders in printed electronics application.

  19. Ethylene epoxidation catalyzed by chlorine-promoted silver oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ozbek, M O; Onal, I [Chemical Engineering Department, Middle East Technical University, 06531, Ankara (Turkey); Van Santen, R A, E-mail: r.a.v.santen@tue.nl [Chemical Engineering and Chemistry Department, Eindhoven University of Technology, 5600 MB, Eindhoven (Netherlands)

    2011-10-12

    It is demonstrated that, on a silver oxide surface, direct formation of ethylene oxide (EO) through the reaction between gas phase ethylene and surface oxygen is possible. The direct reaction channel produces EO selectively without competing with acetaldehyde (AA) formation. The oxometallacycle (OMC) forms on an oxygen vacant surface and reduces EO selectivity. Cl adsorption removes these surface vacant sites and hence prevents the formation of the OMC intermediate.

  20. Catalytic Preparation of Methyl Formate from Methanol over Silver

    Institute of Scientific and Technical Information of China (English)

    YANG Zhi; LI Jing; YANG Xiang-guang; WU Yue

    2005-01-01

    A catalytic reaction over a silver catalyst performed in an unregarded temperature region(473-873 K) with a long catalytic lifetime for the production of methyl formate from methanol was provided as a potential preparing route. The optimal yield of methyl formate(ca. 14.8%) with a selectivity >90% was obtained at about 573 K. Because α-oxygen species and bulk oxygen species coexist in the unregarded temperature region, a synergistic process concerning α-oxygen species and bulk oxygen species was proved over Oα -rich and Oγ-rich samples.

  1. Preparation of Silver-Coated Polystyrene Composite Particles

    Institute of Scientific and Technical Information of China (English)

    陈卓; 詹鹏; 章建辉; 王振林; 章维益; 闵乃本

    2003-01-01

    We report a feasible approach to the preparation of monodispersed metal-shell composite microspheres based on a combination of surface reaction and surface seeding techniques. The method was implemented for coating polystyrene (PS) spheres with silver shell having a variable thickness by controlling the amount of reagents in the reaction procedure. These composite spherical particles in dimensions of the submicrometer range may become attractive building blocks for the creation of metallo-dielectric photonic band gap materials when they are organized into crystals.

  2. Synthesis of silver nanotubes by electroless deposition in porous anodic aluminium oxide templates.

    Science.gov (United States)

    Zhang, Shu-Hong; Xie, Zhao-Xiong; Jiang, Zhi-Yuan; Xu, Xin; Xiang, Juan; Huang, Rong-Bin; Zheng, Lan-Sun

    2004-05-07

    An electroless deposition method has been employed for the synthesis of silver nanotubes using porous anodic aluminium oxide as templates, by which high-yield silver nanotubes with length over ten microns have been synthesized.

  3. Synthetic silver oxide and mercury-free zinc electrodes for silver-zinc reserve batteries

    Science.gov (United States)

    Smith, David F.; Gucinski, James A.

    Reserve activated silver oxide-zinc cells were constructed with synthetic silver oxide (Ag 2O) electrodes with Pb-treated zinc electrodes produced by a non-electrolytic process. The cells were tested before and after thermally accelerated aging. At discharge rates up to 80 mA cm -2, the discharge was limited by the Ag 2O electrode, with a coulombic efficiency between 89-99%. At higher rates, the cells are apparently zinc-limited. Test cells were artificially aged at 90°C for 19 h and discharged at 21°C at 80 mA cm -2. No capacity loss was measured, but a delayed activation rise time was noted (192 ms fresh vs. 567 ms aged). The delay is thought to be caused by zinc passivation due to the outgassing of cell materials.

  4. Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

    Directory of Open Access Journals (Sweden)

    Jes Ærøe Hyllested

    2015-01-01

    Full Text Available Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges as reducing agents. The evolvement of a characteristic surface plasmon extinction spectrum in the range of 420 nm to 480 nm indicates the formation of silver nanoparticles after mixing silver nitrate solution and fruit extract. Shifts in plasmon peaks over time indicate the growth of nanoparticles. Electron microscopy shows that the shapes of the nanoparticles are different depending on the fruit used for preparation. The green preparation process can result in individual nanoparticles with a very poor tendency to form aggregates with narrow gaps even when aggregation is forced by the addition of NaCl. This explains only modest enhancement factors for near-infrared-excited surface enhanced Raman scattering. In addition to the surface plasmon band, UV–visible absorption spectra show features in the UV range which indicates also the presence of small silver clusters, such as Ag42+. The increase of the plasmon absorption correlates with the decrease of absorption band in the UV. This confirms the evolution of silver nanoparticles from silver clusters. The presence of various silver clusters on the surface of the “green” plasmonic silver nanoparticles is also supported by a strong multicolor luminesce signal emitted by the plasmonic particles during 473 nm excitation.

  5. Carbon-Supported Silver Catalysts for CO Selective Oxidation in Excess Hydrogen

    Institute of Scientific and Technical Information of China (English)

    Limin Chen; Ding Ma; Barbara Pietruszka; Xinhe Bao

    2006-01-01

    Carbon materials were used as supports for Ag catalysts that are prepared using the conventional wet impregnation method, and their catalytic properties for CO selective oxidation in excess hydrogen at temperatures below 483 K were tested. A variety of techniques, e.g. N2 adsorption, XPS, TPD, UV-Vis DRS, TEM and SEM, were used to determine the influence of physical and chemical properties of the carbon on the properties of Ag catalyst. It was found that defects on the carbon surface served as nucleation sites for silver ions, while functional groups on carbon surface induced their reduction to the metallic form. The formation of silver particles on carbon was governed by homogeneous and/or heterogeneous nucleation during the impregnation and subsequent activation processes. The best catalytic performance was obtained with a Ag/carbon black catalyst with a uniform size distribution of silver nanoparticles (about 12 nm), moderate BET surface area (with a mesoporous structure), and a limited amount of carbon-oxygen groups. The research indicates that carbon materials are potentially good supports for silver catalysts for preferential oxidation of CO in excess hydrogen.

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

    Science.gov (United States)

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

    2014-04-01

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

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

    NARCIS (Netherlands)

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

    1986-01-01

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

  8. Preparation of silver nanoparticles fabrics against multidrug-resistant bacteria

    Science.gov (United States)

    Hanh, Truong Thi; Thu, Nguyen Thi; Hien, Nguyen Quoc; An, Pham Ngoc; Loan, Truong Thi Kieu; Hoa, Phan Thi

    2016-04-01

    The silver nanoparticles (AgNPs)/peco fabrics were prepared by immobilization of AgNPs on fabrics in which AgNPs were synthesized by γ-irradiation of the 10 mM AgNO3 chitosan solution at the dose of 17.6 kGy. The AgNPs size has been estimated to be about 11 nm from TEM image. The AgNPs content onto peco fabrics was of 143±6 mg/kg at the initial AgNPs concentration of 100 ppm. The AgNPs colloidal solution was characterized by UV-vis spectroscopy and TEM image. The antibacterial activity of AgNPs/peco fabrics after 60 washings against Staphylococcus aureus and Klebsiella pneumoniae was found to be over 99%. Effects of AgNPs fabics on multidrug-resistant pathogens from the clinical specimens were also tested.

  9. Pulicaria glutinosa extract: a toolbox to synthesize highly reduced graphene oxide-silver nanocomposites.

    Science.gov (United States)

    Al-Marri, Abdulhadi H; Khan, Mujeeb; Khan, Merajuddin; Adil, Syed F; Al-Warthan, Abdulrahman; Alkhathlan, Hamad Z; Tremel, Wolfgang; Labis, Joselito P; Siddiqui, Mohammed Rafiq H; Tahir, Muhammad N

    2015-01-05

    A green, one-step approach for the preparation of graphene/Ag nanocomposites (PE-HRG-Ag) via simultaneous reduction of both graphene oxide (GRO) and silver ions using Pulicaria glutinosa plant extract (PE) as reducing agent is reported. The plant extract functionalizes the surfaces of highly reduced graphene oxide (HRG) which helps in conjugating the Ag NPs to HRG. Increasing amounts of Ag precursor enhanced the density of Ag nanoparticles (NPs) on HRG. The preparation of PE-HRG-Ag nanocomposite is monitored by using ultraviolet-visible (UV-Vis) spectroscopy, powder X-ray diffraction (XRD), and energy dispersive X-ray (EDX). The as-prepared PE-HRG-Ag nanocomposities display excellent surface-enhanced Raman scattering (SERS) activity, and significantly increased the intensities of the Raman signal of graphene.

  10. Pulicaria glutinosa Extract: A Toolbox to Synthesize Highly Reduced Graphene Oxide-Silver Nanocomposites

    Directory of Open Access Journals (Sweden)

    Abdulhadi H. Al-Marri

    2015-01-01

    Full Text Available A green, one-step approach for the preparation of graphene/Ag nanocomposites (PE-HRG-Ag via simultaneous reduction of both graphene oxide (GRO and silver ions using Pulicaria glutinosa plant extract (PE as reducing agent is reported. The plant extract functionalizes the surfaces of highly reduced graphene oxide (HRG which helps in conjugating the Ag NPs to HRG. Increasing amounts of Ag precursor enhanced the density of Ag nanoparticles (NPs on HRG. The preparation of PE-HRG-Ag nanocomposite is monitored by using ultraviolet–visible (UV-Vis spectroscopy, powder X-ray diffraction (XRD, and energy dispersive X-ray (EDX. The as-prepared PE-HRG-Ag nanocomposities display excellent surface-enhanced Raman scattering (SERS activity, and significantly increased the intensities of the Raman signal of graphene.

  11. Oxidative Dissolution of Silver Nanoparticles by Chlorine: Implications to Silver Nanoparticle Fate and Toxicity.

    Science.gov (United States)

    Garg, Shikha; Rong, Hongyan; Miller, Christopher J; Waite, T David

    2016-04-05

    The kinetics of oxidative dissolution of silver nanoparticles (AgNPs) by chlorine is investigated in this work, with results showing that AgNPs are oxidized in the presence of chlorine at a much faster rate than observed in the presence of dioxygen and/or hydrogen peroxide. The oxidation of AgNPs by chlorine occurs in air-saturated solution in stoichiometric amounts with 2 mol of AgNPs oxidized for each mole of chlorine added. Dioxygen plays an important role in OCl(-)-mediated AgNP oxidation, especially at lower OCl(-) concentrations, with the mechanism shifting from stoichiometric oxidation of AgNPs by OCl(-) in the presence of dioxygen to catalytic removal of OCl(-) by AgNPs in the absence of dioxygen. These results suggest that the presence of chlorine will mitigate AgNP toxicity by forming less-reactive AgCl(s) following AgNP oxidation, although the disinfection efficiency of OCl(-) may not be significantly impacted by the presence of AgNPs because a chlorine-containing species is formed on OCl(-) decay that has significant oxidizing capacity. Our results further suggest that the antibacterial efficacy of nanosilver particles embedded on fabrics may be negated when treated with detergents containing strong oxidants, such as chlorine.

  12. Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

    DEFF Research Database (Denmark)

    Hyllested, Jes Ærøe; Espina Palanco, Marta; Hagen, Nicolai

    2015-01-01

    Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges...... as reducing agents. The evolvement of a characteristic surface plasmon extinction spectrum in the range of 420 nm to 480 nm indicates the formation of silver nanoparticles after mixing silver nitrate solution and fruit extract. Shifts in plasmon peaks over time indicate the growth of nanoparticles. Electron......Cl. This explains only modest enhancement factors for near-infrared-excited surface enhanced Raman scattering. In addition to the surface plasmon band, UV-visible absorption spectra show features in the UV range which indicates also the presence of small silver clusters, such as Ag42+. The increase of the plasmon...

  13. Imaging Dynamic Collision and Oxidation of Single Silver Nanoparticles at the Electrode/Solution Interface.

    Science.gov (United States)

    Hao, Rui; Fan, Yunshan; Zhang, Bo

    2017-09-06

    The electrochemical interface is an ultrathin interfacial region between the electrode surface and the electrolyte solution and is often characterized by numerous dynamic processes, such as solvation and desolvation, heterogeneous electron transfer, molecular adsorption and desorption, diffusion, and surface rearrangement. Many of these processes are driven and modulated by the presence of a large interfacial potential gradient. The study and better understanding of the electrochemical interface is important for designing better electrochemical systems where their applications may include batteries, fuel cells, electrocatalytic water splitting, corrosion protection, and electroplating. This, however, has proved to be a challenging analytical task due to the ultracompact and dynamic evolving nature of the electrochemical interface. Here, we describe the use of an electrochemical nanocell to image the dynamic collision and oxidation process of single silver nanoparticles at the surface of a platinum nanoelectrode. A nanocell is prepared by depositing a platinum nanoparticle at the tip of a quartz nanopipette forming a bipolar nanoelectrode. The compact size of the nanocell confines the motion of the silver nanoparticle in a 1-D space. The highly dynamic process of nanoparticle collision and oxidation is imaged by single-particle fluorescence microscopy. Our results demonstrate that silver nanoparticle collision and oxidation is highly dynamic and likely controlled by a strong electrostatic effect at the electrode/solution interface. We believe that the use of a platinum nanocell and single molecule/nanoparticle fluorescence microscopy can be extended to other systems to yield highly dynamic information about the electrochemical interface.

  14. Preparation of Manganese Oxide Nanobelts

    Institute of Scientific and Technical Information of China (English)

    Jisen WANG; Jinquan SUN; Ying BAO; Xiufang BIAN

    2003-01-01

    Oriented nanobelts of manganese oxide have been firstly and successfully prepared by a microemulsion techniqueunder controlled circumstances. The samples were characterized by X-ray diffraction (XRD), transmission electronmicroscope (TEM). Influences of sodium chloride and annealed temperature on the synthesis of Mn3O4 nanobeltswere investigated. It was found that NaCl is the key factor to synthesize oriented Mn3O4 nanobelts and 827 K isoptimum temperature to produce fine nanobelts. Oriented growth mechanism of Mn3O4 nanobelts was discussed.

  15. Preparation and Characterization of Silver Liquid Thin Films for Magnetic Fluid Deformable Mirror

    Directory of Open Access Journals (Sweden)

    Lianchao Zhang

    2015-01-01

    Full Text Available Silver liquid thin film, formed by silver nanoparticles stacking and spreading on the surface of the liquid, is one of the important parts of magnetic fluid deformable mirror. First, silver nanoparticles were prepared by liquid phase chemical reduction method using sodium citrate as reducing agent and stabilizer and silver nitrate as precursor. Characterization of silver nanoparticles was studied using X-ray diffractometer, UV-vis spectrophotometer, and transmission electron microscope (TEM. The results showed that silver nanoparticles are spherical and have a good monodispersity. Additionally, the effect of the reaction conditions on the particle size of silver is obvious. And then silver liquid thin films were prepared by oil-water two-phase interface technology using as-synthesized silver nanoparticles. Properties of the film were investigated using different technology. The results showed that the film has good reflectivity and the particle size has a great influence on the reflectivity of the films. SEM photos showed that the liquid film is composed of multilayer silver nanoparticles. In addition, stability of the film was studied. The results showed that after being stored for 8 days under natural conditions, the gloss and reflectivity of the film start to decrease.

  16. 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

  17. Preparation of Nanoelectrode Ensembles by Assembly of Nano- Silver Colloid on Gold Surface

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel method for preparing silver nanoelectrode ensembles (SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl mercaptan was then assembled on the electrode to form a thiol monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying an AC voltage with increasing frequency at 0.20 V (vs. SCE). Finally, GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method etc., this method enjoys some advantages of lower resistance, same diameter, easy preparation, controllable size and density.

  18. Preparation of Nanoelectrode Ensembles by Assembly of Nano—Silver Colloid on Gold Surface

    Institute of Scientific and Technical Information of China (English)

    GangXIA; XiaoYaHU; 等

    2002-01-01

    A novel method for preparing silver nanoelectrode ensembles(SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl nercaptan was then assembled on the electrode to form a thoil monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying and AC voltage with increasing frequency at 0.20V(vs.SCE). Finally,GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method ect., this method enjoys some advantages of lower resistance, same diameter,easy preparation,controllable size and density.

  19. Facile and green synthesis of silver nanoparticles using oxidized pectin

    Energy Technology Data Exchange (ETDEWEB)

    Tummalapalli, Mythili; Deopura, B.L. [Bioengineering Lab, Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India); Alam, M.S. [Department of Chemistry, Jamia Hamdard, New Delhi 110062 (India); Gupta, Bhuvanesh, E-mail: bgupta@textile.iitd.ernet.in [Bioengineering Lab, Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi 110016 (India)

    2015-05-01

    In the current work, an alternative route for facile synthesis of nanosilver is reported. Oxidized pectin has been used as the reducing agent as well as the stabilizing agent, resulting in the formation of oxidized pectin-nanosilver (OP-NS) core sheath nanohydrogels. The effect of reaction parameters on the synthesized nanoparticles is investigated. The structural and morphological features have been analyzed using X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) respectively. The crystal size of the synthesized nanosilver was calculated to be 28.76 nm. While the average size of the core sheath structure varied from 289 nm to 540 nm, the size of the silver nanoparticle entities at the core varied from 100 nm to 180 nm, with variation in reaction time. From the morphological examination, it could be seen that flower like nanostructures are formed with nanosilver in the core surrounded by a polymeric halo. - Highlights: • In-situ reduction of silver nitrate to nanosilver was carried out using oxidized pectin. • Oxidized pectin-nanosilver nanohydrogels were synthesized. • Nanoparticles with flower like morphology and face centered cubic crystal structure were fabricated.

  20. Preparation and Characterization of Nylon 6/Silver Nanocomposite Fibers for Permanent Antibacterial Effect

    Directory of Open Access Journals (Sweden)

    Laleh Maleknia

    2015-03-01

    Full Text Available The nylon 6/silver nano composite fibers were prepared for the attainment of permanent antibacterial activity to common synthetic textile. The fibers prepared by melt spinning and nylon 6/ Silver nanocomposite were prepared by a modular twin screw extruder.. The antibacterial activities of nano silver in fibers were calculated by percent reduction of two kinds of bacteria staphylococcus aurous and klebsiela peneumoniae. Scanning electron microscopy (SEM was carried out to observe particle distribution on the nanocomposite fibers. All the nanocomposite fibers were characterized by instron machine.

  1. Reduced Graphene Oxide-Based Silver Nanoparticle-Containing Composite Hydrogel as Highly Efficient Dye Catalysts for Wastewater Treatment

    Science.gov (United States)

    Jiao, Tifeng; Guo, Haiying; Zhang, Qingrui; Peng, Qiuming; Tang, Yongfu; Yan, Xuehai; Li, Bingbing

    2015-07-01

    New reduced graphene oxide-based silver nanoparticle-containing composite hydrogels were successfully prepared in situ through the simultaneous reduction of GO and noble metal precursors within the GO gel matrix. The as-formed hydrogels are composed of a network structure of cross-linked nanosheets. The reported method is based on the in situ co-reduction of GO and silver acetate within the hydrogel matrix to form RGO-based composite gel. The stabilization of silver nanoparticles was also achieved simultaneously within the gel composite system. The as-formed silver nanoparticles were found to be homogeneously and uniformly dispersed on the surface of the RGO nanosheets within the composite gel. More importantly, this RGO-based silver nanoparticle-containing composite hydrogel matrix acts as a potential catalyst for removing organic dye pollutants from an aqueous environment. Interestingly, the as-prepared catalytic composite matrix structure can be conveniently separated from an aqueous environment after the reaction, suggesting the potentially large-scale applications of the reduced graphene oxide-based nanoparticle-containing composite hydrogels for organic dye removal and wastewater treatment.

  2. Comparative Assessment of Antimicrobial Efficiency of Ionic Silver, Silver Monoxide, and Metallic Silver Incorporated onto an Aluminum Oxide Nanopowder Carrier

    Directory of Open Access Journals (Sweden)

    Agnieszka Maria Jastrzębska

    2013-01-01

    Full Text Available The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+, silver monoxide (Ag2O, and metallic silver (Ag incorporated onto an aluminum oxide nanopowder carrier (Al2O3. The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively and quantitatively by SEM, physical nitrogen sorption and XRD analyses. Results indicate that the Al2O3 nanopowders added with Ag+, Ag2O, and Ag, apart from phase composition, were not differing considerably from one another in terms of their morphology and physical properties. However, nanopowders of Al2O3-Ag were more agglomerated than Al2O3-Ag2O and Al2O3-Ag+ nanopowders. The antibacterial activity of the nanopowders was examined by the spread plate method using bacterial strains such as Escherichia coli, Sarcina lutea, and Bacillus subtilis. The best antibacterial properties against Sarcina lutea strain were achieved in the amorphous-Al2O3-Ag+ and Al2O3-Ag2O nanopowders, whereas the worst antimicrobial activity against Bacillus subtilis and Escherichia coli was shown by the Al2O3-Ag+ and Al2O3-Ag nanopowders. The observed increase of the antibacterial activity as the silver content was not however significant for Al2O3-Ag nanopowders. The results obtained in the present experiments show that the Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders, possessing good bactericidal properties, can be produced by using consecutive stages of dry sol-gel method, and Al2O3 nanopowder added with Ag2O is considered as the best raw material in the production of antiseptic materials.

  3. A microkinetic model of the methanol oxidation over silver

    DEFF Research Database (Denmark)

    Andreasen, A.; Lynggaard, H.; Stegelmann, C.

    2003-01-01

    , respectively. The model explains observed reaction orders, selectivity, apparent activation enthalpies and the choice of industrial reaction conditions. More interesting the model disproves the notion that the mechanism deduced from surface science in UHV cannot be responsible for formaldehyde synthesis......A simple microkinetic model for the oxidation of methanol on silver based on surface science studies at UHV and low temperatures has been formulated. The reaction mechanism is a simple Langmuir-Hinshelwood mechanism, with one type of active oxygen and one route to formaldehyde and carbon dioxide...

  4. Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

    DEFF Research Database (Denmark)

    Hyllested, Jes Ærøe; Espina Palanco, Marta; Hagen, Nicolai;

    2015-01-01

    microscopy shows that the shapes of the nanoparticles are different depending on the fruit used for preparation. The green preparation process results mainly in individual nanoparticles with a very poor tendency to form aggregates with narrow gaps even when aggregation is forced by the addition of Na......Cl. This explains only modest enhancement factors for near-infrared-excited surface enhanced Raman scattering. In addition to the surface plasmon band, UV-visible absorption spectra show features in the UV range which indicates also the presence of small silver clusters, such as Ag42+. The increase of the plasmon...... absorption correlates with the decrease of absorption band in the UV. This confirms the evolution of silver nanoparticles from silver clusters. The presence of various silver clusters on the surface of the “green” plasmonic silver nanoparticles is also supported by a strong multi-color luminesce signal...

  5. Preparation of silver-coated glass frit and its application in silicon solar cells

    Science.gov (United States)

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

    2016-07-01

    A simple electroless plating process was employed to prepare silver-coated glass frits for solar cells. The surface of the glass frits was modified with polyvinyl-pyrrolidone (PVP) before the electroless plating process. Infrared (IR) spectroscopy, field emission scanning electron microscopy (FESEM), and x-ray diffraction (XRD) were used to characterize the PVP modified glass frits and investigate the mechanism of the modification process. It was found that the PVP molecules adsorbed on the glass frit surface and reduced the silver ions to the silver nanoparticles. Through epitaxial growth, these nanoparticles were uniformly deposited onto the surface of the glass frit. Silicon solar cells with this novel silver coating exhibited a photoelectric conversion efficiency increase of 0.33%. Compared with the electroless plating processes, this method provides a simple route to prepare silver-coated glass frits without introducing impurity ions.

  6. Preparation of silver-coated glass frit and its application in silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    向锋; 李碧渊; 黎应芬; 周健; 甘卫平

    2016-01-01

    A simple electroless plating process was employed to prepare silver-coated glass frits for solar cells. The surface of the glass frits was modified with polyvinyl-pyrrolidone (PVP) before the electroless plating process. Infrared (IR) spectroscopy, field emission scanning electron microscopy (FESEM), and x-ray diffraction (XRD) were used to characterize the PVP modified glass frits and investigate the mechanism of the modification process. It was found that the PVP molecules adsorbed on the glass frit surface and reduced the silver ions to the silver nanoparticles. Through epitaxial growth, these nanoparticles were uniformly deposited onto the surface of the glass frit. Silicon solar cells with this novel silver coating exhibited a photoelectric conversion efficiency increase of 0.33%. Compared with the electroless plating processes, this method provides a simple route to prepare silver-coated glass frits without introducing impurity ions.

  7. Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    de Moraes ACM

    2015-11-01

    Full Text Available Ana Carolina Mazarin de Moraes,1 Bruna Araujo Lima,2 Andreia Fonseca de Faria,1 Marcelo Brocchi,2 Oswaldo Luiz Alves1 1Laboratory of Solid State Chemistry, Institute of Chemistry, University of Campinas, Campinas, São Paulo, Brazil; 2Department of Genetics, Evolution and Bioagents, Institute of Biology, University of Campinas, Campinas, São Paulo, Brazil Background: Methicillin-resistant Staphylococcus aureus (MRSA has been responsible for serious hospital infections worldwide. Nanomaterials are an alternative to conventional antibiotic compounds, because bacteria are unlikely to develop microbial resistance against nanomaterials. In the past decade, graphene oxide (GO has emerged as a material that is often used to support and stabilize silver nanoparticles (AgNPs for the preparation of novel antibacterial nanocomposites. In this work, we report the synthesis of the graphene-oxide silver nanocomposite (GO-Ag and its antibacterial activity against relevant microorganisms in medicine. Materials and methods: GO-Ag nanocomposite was synthesized through the reduction of silver ions (Ag+ by sodium citrate in an aqueous GO dispersion, and was extensively characterized using ultraviolet-visible absorption spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The antibacterial activity was evaluated by microdilution assays and time-kill experiments. The morphology of bacterial cells treated with GO-Ag was investigated via transmission electron microscopy. Results: AgNPs were well distributed throughout GO sheets, with an average size of 9.4±2.8 nm. The GO-Ag nanocomposite exhibited an excellent antibacterial activity against methicillin-resistant S. aureus, Acinetobacter baumannii, Enterococcus faecalis, and Escherichia coli. All (100% MRSA cells were inactivated after 4 hours of exposure to GO-Ag sheets. In addition, no toxicity was found for either pristine GO or bare Ag

  8. Preparation and microwave shielding property of silver-coated carbonyl iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiao Guo, E-mail: xgcao@gdut.edu.cn [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Ren, Hao [Guangzhou Research Institute of O-M-E Technology, Guangzhou 510006, Guangdong (China); Zhang, Hai Yan [School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China)

    2015-05-15

    Highlights: • The silver-coated carbonyl iron powder is prepared by the electroless plating process. • The silver-coated carbonyl iron powder is a new kind of conductive filler. • The reflection and absorption dominate the shielding mechanism of the prepared powder. • Increasing the thickness of electroconductive adhesive will increase the SE. - Abstract: Electroless silver coating of carbonyl iron powder is demonstrated in the present investigation. The carbonyl iron powders are characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD) before and after the coating process. The relatively uniform and continuous silver coating is obtained under the given coating conditions. In this paper, the electromagnetic interference (EMI) shielding mechanism of the silver-coated carbonyl iron powder is suggested. The reflection of silver coating and absorption of carbonyl iron powder dominate the shielding mechanism of the silver-coated carbonyl iron powder. The silver-coated carbonyl iron powders are used as conductive filler in electroconductive adhesive for electromagnetic interference shielding applications. The effect of the thickness of electroconductive adhesive on the shielding effectiveness (SE) is investigated. The results indicate that the SE increases obviously with the increase of the thickness of electroconductive adhesive. The SE of the electroconductive adhesive with 0.35 mm thickness is above 38 dB across the tested frequency range.

  9. Electrical and optical properties of reactive dc magnetron sputtered silver-doped indium oxide thin films: role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, A.; Barik, U.K. [Indian Institute of Technology Madras, Semiconductor Physics Laboratory, Department of Physics, Chennai (India)

    2006-07-15

    Silver-doped indium oxide thin films have been prepared on glass and quartz substrates at room temperature (300 K) by a reactive dc magnetron sputtering technique using an alloy target of pure indium and silver (80:20 at. %). During sputtering, the oxygen flow rates are varied in the range 0.00-2.86 sccm keeping the magnetron power constant at 40 W. The resistivity of these films is in the range 10{sup 0}-10{sup -3} {omega}cm and they show a negative temperature coefficient of resistivity. The films exhibit p-type conductivity at an oxygen flow rate of 1.71 sccm. The work function of these silver-indium oxide films has been measured by a Kelvin probe technique. The refractive index of the films (at 632.8 nm) varies in the range 1.13-1.20. Silver doping in indium oxide narrows the band gap of indium oxide (3.75 eV). (orig.)

  10. Silver nanoplates: controlled preparation, self-assembly, and applications in surface-enhanced Raman scattering

    Science.gov (United States)

    Yi, Zao; Xu, Xibin; Wu, Xiaoqiang; Chen, Chaohua; Li, Xibo; Luo, Bingchi; Luo, Jiangshan; Jiang, Xiaodong; Wu, Weidong; Yi, Yougen; Tang, Yongjian

    2013-02-01

    Silver nanoplates were prepared in a dual reduction system with NaBH4 and sodium citrate both as reducing agents. And then the as-prepared nanoplates could be growing up through multistage growth methodology. The average edge length of Ag nanoplates can be tailored from 40 nm to 260 nm without changing their shape, crystallinity, and the average thickness. Furthermore, the effectiveness of these silver nanoplates as substrates prepared by the silanization self-assembly method toward surface-enhanced Raman scattering (SERS) detection was evaluated by using 4-aminothiophenol (4-ATP) and rhodamine 6G (R6G) as probe molecules. It was found that the enhancement ability of the silver nanoplates film is remarkable lower than that of the spherical silver nanoparticle film. The reason is attributed to the electromagnetic mechanism and chemical mechanism. This work will be of great significance in understanding the SERS enhancement mechanism and in the fabrication of nanoparticle films for biosensing.

  11. Synthesis of one-dimensional silver oxide nanoparticle arrays and silver nanorods templated by Langmuir monolayers.

    Science.gov (United States)

    Liu, Hong-Guo; Xiao, Fei; Wang, Chang-Wei; Xue, Qingbin; Chen, Xiao; Lee, Yong-Ill; Hao, Jingcheng; Jiang, Jianzhuang

    2007-10-01

    One-dimensional (1D) silver oxide nanoparticle arrays were synthesized by illuminating the composite Langmuir-Blodgett monolayers of porphyrin derivatives/Ag(+) and n-hexadecyl dihydrogen phosphate (n-HDP)/Ag(+) deposited on carbon-coated copper grids with daylight and then exposing them to air. Transmission electron microscopy (TEM) observation shows that the nanoparticle size is around 3 nm, with the separation of about 2-3 nm. High-resolution TEM (HRTEM) investigation indicates that the particles are made up of Ag(2)O. Ag nanorods with the width of 15-35 nm and the length of several hundreds of nanometers were synthesized by irradiating the composite Langmuir monolayers of porphyrin derivatives/Ag(+) and n-HDP/Ag(+) by UV-light directly at the air/water interface at room temperature. HRTEM image and selected-area electron diffraction (SAED) pattern indicate that the nanorods are single crystals with the (110) face of the face-centered cubic (fcc) silver parallel to the air/water interface. The formation of the 1D arrays and the nanorods should be attributed to the templating effect of the linear supramolecules formed by porphyrin derivative or n-HDP molecules in Langmuir monolayers through non-covalent interactions.

  12. Single-stage synthesis and characterization of reflective and conductive silver-polyimide films prepared from silver(I) complexes with ODPA/4,4'-ODA.

    Science.gov (United States)

    Thompson, D Scott; Davis, Luke M; Thompson, David W; Southward, Robin E

    2009-07-01

    Reflective and surface conductive polyimide films were prepared by the incorporation of silver(I) acetate and trifluoroacetylacetone into a dimethylacetamide solution of the poly(amic acid) formed 3,3',4,4'-oxidiphthalic dianhydride (ODPA) and 4,4'-oxidianiline (4,4'-ODA). Thermal curing of (trifluoroacetylacetonato)silver(I)-poly(amic acid) films led to cycloimidization with concomitant silver(I) reduction, which yielded a reflective and conductive silver surface at selected silver concentrations if the film was cured to a final temperature of 300 degrees C for several hours. The metallized ODPA/4,4'-ODA films retain the essential mechanical properties of an undoped film and have good thermal stability, particularly under a nitrogen atmosphere. The bulk of the composite film was not electrically conductive. The use of (hexafluoroacetylacetonato)silver(I) and silver(I) tetrafluoroborate as sources of silver(I) with ODPA/4,4'-ODA yielded modestly reflective films that never developed conductivity. The silvered films prepared with (trifluoroacetylacetonato)silver(I) can be patterned using mask-etch techniques. Comparisons are made among four similar silver-polyimide systems, with the polyimides being ODPA/4,4'-ODA, BTDA/4,4'-ODA, BPDA/4,4'-ODA, and 6FDA/4-BDAF.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

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

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

    Science.gov (United States)

    Liu, Jianguo; Cao, Yu; Li, Xiangyou; Wang, Xiaoye; Zeng, Xiaoyan

    2010-09-01

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

  15. Anti-adhesion and antibacterial activity of silver nanoparticles supported on graphene oxide sheets.

    Science.gov (United States)

    de Faria, Andreia Fonseca; Martinez, Diego Stéfani Teodoro; Meira, Stela Maris Meister; de Moraes, Ana Carolina Mazarin; Brandelli, Adriano; Filho, Antonio Gomes Souza; Alves, Oswaldo Luiz

    2014-01-01

    This work reports on the preparation, characterization and antibacterial activity of a nanocomposite formed from graphene oxide (GO) sheets decorated with silver nanoparticles (GO-Ag). The GO-Ag nanocomposite was prepared in the presence of AgNO3 and sodium citrate. The physicochemical characterization was performed by UV-vis spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), Raman spectroscopy and transmission electron microscopy (TEM). The average size of the silver nanoparticles anchored on the GO surface was 7.5 nm. Oxidation debris fragments (a byproduct adsorbed on the GO surface) were found to be crucial for the nucleation and growth of the silver nanoparticles. The antibacterial activity of the GO and GO-Ag nanocomposite against the microorganism Pseudomonas aeruginosa was investigated using the standard counting plate methodology. The GO dispersion showed no antibacterial activity against P. aeruginosa over the concentration range investigated. On the other hand, the GO-Ag nanocomposite displayed high biocidal activity with a minimum inhibitory concentration ranging from 2.5 to 5.0 μg/mL. The anti-biofilm activity toward P. aeruginosa adhered on stainless steel surfaces was also investigated. The results showed a 100% inhibition rate of the adhered cells after exposure to the GO-Ag nanocomposite for one hour. To the best of our knowledge, this work provides the first direct evidence that GO-Ag nanocomposites can inhibit the growth of microbial adhered cells, thus preventing the process of biofilm formation. These promising results support the idea that GO-Ag nanocomposites may be applied as antibacterial coatings material to prevent the development of biofilms in food packaging and medical devices.

  16. Graphene oxide functionalized with silver@silica-polyethylene glycol hybrid nanoparticles for direct electrochemical detection of quercetin.

    Science.gov (United States)

    Veerapandian, Murugan; Seo, Yeong-Tai; Yun, Kyusik; Lee, Min-Ho

    2014-08-15

    A direct electrochemical detection of quercetin based on functionalized graphene oxide modified on gold-printed circuit board chip was demonstrated in this study. Functionalized graphene oxide materials are prepared by the covalent reaction of graphene oxide with silver@silica-polyethylene glycol nanoparticles (~12.35nm). Functionalized graphene oxide electrode shows a well-defined voltammetric response in phosphate buffered saline and catalyzes the oxidation of quercetin to quinone without the need of an enzyme. Significantly, the functionalized graphene oxide modified electrode exhibited a higher sensitivity than pristine gold-printed circuit board and graphene oxide electrodes, a wide concentration range of 7.5 to 1040nM and detection limit of 3.57nM. Developed biosensor platform is selective toward quercetin in the presence of an interferent molecule.

  17. Magnetron sputtering of silver nanowires using anodic aluminum oxide template: a new active substrate of surface enhanced Raman scattering and an investigation of its enhanced mechanism.

    Science.gov (United States)

    Zhang, Lisheng; Zhang, Pengxiang; Fang, Yan

    2007-05-22

    A high quality anodic aluminum oxide (AAO) template with ordered apertures about 50-80 nm was fabricated by anodizing aluminum in electrolytes through a two-step method, and silver nanowires with diameters from 40 nm to 70 nm were prepared on this AAO template by magnetron sputtering. On the glass covered with silver nanowires, high quality surface enhanced Raman scattering (SERS) spectra of sudan II (C18H16N2O) with enhancement factors of 10(5) were obtained. And comparison of SERS spectra on silver nanowires with the SERS spectra of silver colloids indicates that main enhanced mode is lightning rod effect of nanorods on the Sudan II/silver nanowires system.

  18. Silver nanowires-templated metal oxide for broadband Schottky photodetector

    Science.gov (United States)

    Patel, Malkeshkumar; Kim, Hong-Sik; Park, Hyeong-Ho; Kim, Joondong

    2016-04-01

    Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W-1) and detectivity (2.75 × 1015 Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxide devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.

  19. Participation of the Third Order Optical Nonlinearities in Nanostructured Silver Doped Zinc Oxide Thin Solid Films

    Directory of Open Access Journals (Sweden)

    C. Torres-Torres

    2012-01-01

    Full Text Available We report the transmittance modulation of optical signals in a nanocomposite integrated by two different silver doped zinc oxide thin solid films. An ultrasonic spray pyrolysis approach was employed for the preparation of the samples. Measurements of the third-order nonlinear optical response at a nonresonant 532 nm wavelength of excitation were performed using a vectorial two-wave mixing. It seems that the separated contribution of the optical nonlinearity associated with each film noticeable differs in the resulting nonlinear effects with respect to the additive response exhibited by the bilayer system. An enhancement of the optical Kerr nonlinearity is predicted for prime number arrays of the studied nanoclusters in a two-wave interaction. We consider that the nanostructured morphology of the thin solid films originates a strong modification of the third-order optical phenomena exhibited by multilayer films based on zinc oxide.

  20. Silver ion impregnated composite biomaterial optimally prepared using zeta potential measurements.

    Science.gov (United States)

    Sakthivel, N; Socrates, R; Shanthini, G M; Rajaram, A; Kalkura, S Narayana

    2015-02-01

    Biodegradable, antimicrobial composite of various silver ion concentrations was synthesized using zeta potential and isoelectric point measurements, for a controlled release of silver ions, and in addition to assess the effect of protein adsorption with the increase of the silver ion concentration. The interaction between hydroxyapatite (HAp) and silver incorporated hydroxyapatite (AgHAp) with gelatin was increased by optimally adjusting the zeta potential and isoelectric point of the ceramic (HAp and AgHAp), and bio-polymer individually. The electrostatic interactions between the ceramic and biopolymer were confirmed, through shifts in N-H stretching, decrease in the swelling ratio, and increase in the degradation temperature observed by the derivative thermo-gravimetric analysis (DTG). These results substantiate that, the zeta potential is a novel tool to increase the ceramic-biopolymer interaction. Increasing electrostatic interaction between the biopolymer and ceramic, decreases the release of silver ions in the simulated body fluid, due to the controlled degradation of the biopolymer. The isoelectric point decreases with the increase of the silver ion concentration, which evidenced the change in the net surface charge. With the increase of the silver ion concentration, the protein adsorption decreases due to an increase in hydrophilic character of the composite. This study examines the minimum concentration of silver ion essential for maximum protein adsorption, antimicrobial and hemocompatibility. This study provides a novel route to control the release of silver ions by enhancing the ceramic-polymer interaction and estimate the silver ion concentration suitable for protein adsorption. The prepared composite is nontoxic, degradable, and antimicrobial, with the controlled release of silver ions in the simulated body fluid.

  1. Adsorption and reaction of silver on an oxidized Si(0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, S., E-mail: sohno@ynu.ac.jp [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Tanaka, H. [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Takahashi, K.; Kamada, M. [Synchrotron Light Application Center, Saga University, Honjo 1, Saga 840-8502 (Japan); Tanaka, M. [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2015-08-15

    Highlights: • Electronic states associated with silver adsorption processes on oxidized silicon surfaces were investigated. • Characterization of oxide thin films on Si surfaces was performed using photoelectron spectroscopy with synchrotron radiation. • The changes in the Si 2p oxide components upon silver adsorption are ascribed to charge transfer rather than a conformation change. - Abstract: The adsorption and reaction of silver on an oxidized Si(0 0 1) surface were investigated on the basis of Si 2p, Ag 3d and O 1s core-level photoemission measurements at room temperature (RT). We compared the present results with those obtained in the case of titanium in our previous study. We found that silver on an oxidized Si(0 0 1) surface at RT causes a reduction in the intensity of the Si{sup 1+} and Si{sup 2+} states and an increase in the intensity of the Si{sup 3+} and Si{sup 4+} states. Based on an analysis of the Ag 3d and O 1s states, we concluded that the change in the Si 2p oxidized states upon silver adsorption is due to charge transfer rather than conformation change, although the applicability of the charge transfer scheme may be dependent on the thickness of the silver layer. We also deduced that penetration of silver atoms through a thin silicon oxide film occurs.

  2. A facile method for preparing highly conductive and reflective surface-silvered polyimide films

    Science.gov (United States)

    Liao, Yuan; Cao, Bing; Wang, Wen-Cai; Zhang, Liqun; Wu, Dezhen; Jin, Riguang

    2009-07-01

    A novel method was developed for the preparation of reflective and electrically conductive surface-silvered polyimide (PI) films. The polyimide films were functionalized with poly(dopamine), simply by dipping the PI films into aqueous dopamine solution and mildly stirring at room temperature. Electroless plating of silver was readily carried out on the poly(dopamine) deposited PI (PI-DOPA) surface. The surface compositions of the modified PI films were studied by X-ray photoelectron spectroscopy (XPS). XPS results show that the PI-DOPA surfaces were successfully deposited with ploy(dopamine) and were ready for electroless deposition of silver. The poly(dopamine) layer was used not only as the chemi-sorption sites for silver particles during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The as-prepared silvered PI films show high conductivity and reflectivity, with a surface resistance of 1.5 Ω and a reflectivity of 95%, respectively.

  3. A facile method for preparing highly conductive and reflective surface-silvered polyimide films

    Energy Technology Data Exchange (ETDEWEB)

    Liao Yuan; Cao Bing [State Key Laboratory of Chemical Resource Engineering, and the Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing 100029 (China); Wang Wencai, E-mail: wangw@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, and Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing 100029 (China); Zhang Liqun; Wu Dezhen; Jin Riguang [State Key Laboratory of Chemical Resource Engineering, and Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Beijing 100029 (China)

    2009-07-15

    A novel method was developed for the preparation of reflective and electrically conductive surface-silvered polyimide (PI) films. The polyimide films were functionalized with poly(dopamine), simply by dipping the PI films into aqueous dopamine solution and mildly stirring at room temperature. Electroless plating of silver was readily carried out on the poly(dopamine) deposited PI (PI-DOPA) surface. The surface compositions of the modified PI films were studied by X-ray photoelectron spectroscopy (XPS). XPS results show that the PI-DOPA surfaces were successfully deposited with ploy(dopamine) and were ready for electroless deposition of silver. The poly(dopamine) layer was used not only as the chemi-sorption sites for silver particles during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The as-prepared silvered PI films show high conductivity and reflectivity, with a surface resistance of 1.5 {Omega} and a reflectivity of 95%, respectively.

  4. ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION

    Energy Technology Data Exchange (ETDEWEB)

    Dang, Y. Y.; Bhuiyan, M.S.; Paranthaman, M. P.

    2008-01-01

    Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic fi lms can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide fi lm to fl ake off. Further studies are needed to defi ne the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  5. Preparation, Characterization and Optical Properties of Host-guest Nanocomposite Material Mordenite-silver Iodide

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Silver iodide nanoclusters were successfully prepared in the channels of mordenite by a heat diffusion method. Powder X-ray diffraction, adsorption technique and infrared spectroscopy were used to characterize the prepared materials, which showed that the guest silver iodide had been encapsulated in the channels of mordenite. The optical properties of the solid phase diffuse reflectance absorption of nanocomposite material NaM-AgI were studied, showing that the absorption bands of the diffuse reflectance absorption of the prepared material moved to the region of high energy. The absorption peak of the material prepared shifted to the region of high energy. Namely, blue shift was caused. This has demonstrated the incorporation of silver iodide into the channels of the zeolite. We observed the luminescence and surface photovoltage spectra of NaM-AgI sample, proposing the mechanisms of the photoluminescence and photovoltaic responses.

  6. Preparation,Characterization and Optical Properties of Hostguest Nanocomposite Material Mordenite—silver Iodide

    Institute of Scientific and Technical Information of China (English)

    ZHAIQing-zhou; QIUShi-lun

    2003-01-01

    Silver iodide nanoclusters were successfully prepared in the channels of mordenite by a heat diffusion method.Powder X-ray diffraction.adsorption technique and infrared spectroscopy were used to characterize the prepared materials,which showed that the guest silver iodied had been encapsulated in the channels of mordenite.The optical properties of the solid phase diffuse reflectance absorption of nanocomposite material NaM-AgI were studied,showing that the absorption bands of the diffuse reflectance absorption of the prepared material moved to the region of high energy.The absorption peak of the material prepared shifted to the region of high energy.Namely,blue shift was caused.This has demonstrated the incorporation of silver iodide into the channels of the zeolite.We observed the luminescence and surface photovoltage spectra of NaM-AgI sample,proposing the mechanisms of the photoluminescence and photovoltaic responses.

  7. Preparation and anti-bacterial properties of a temperature sensitive gel containing silver nanoparticles

    Science.gov (United States)

    The purpose of this study was to prepare a novel temperature-sensitive spray gel containing silver nanoparticles and investigate its anti-bacterial properties in vitro. Methods: The aqueous complex gel was prepared by Pluronic F127 (18-22%) and Pluronic F68 (3-9%) through a cold method to obtain a p...

  8. A Three-Step Laboratory Sequence to Prepare a Carbene Complex of Silver(I) Chloride

    Science.gov (United States)

    Canal, John P.; Ramnial, Taramatee; Langlois, Lisa D.; Abernethy, Colin D.; Clyburne, Jason A. C.

    2008-01-01

    We have developed a multistep inorganic synthesis experiment for our second-year undergraduate teaching laboratory that introduces students to modern organometallic chemistry. The ligands are prepared in two simple steps and the preparation of an air-stable silver carbene complex is accomplished in the third step. The students are introduced to…

  9. Preparation, Characterization and Properties of Graphene-silver Sulphide Hybrid

    Institute of Scientific and Technical Information of China (English)

    CHEN Guang-yi; WEI Zhi-yong; LIANG Ce; WANG De-jin; LIANG Ji-cai; ZHANG Wan-xi

    2012-01-01

    A facile and efficient strategy was reported for the preparation of graphene nanosheets-Ag2S hybrid by a simple hydrothermal process.First,Ag2S particles deposited on the surface of graphene oxide(GO) sheet.GO was then reduced by hydrazine hydrate to graphcne.The results of X-ray diffraction(XRD) and Fourier transform infrared(FTIR) demonstrated the efficient reduction of GO to graphene.Transmission electron microscopy(TEM) image of the sample reveals the morphology of the architecture of graphene-Ag2S hybrid.Ultraviolet-visible spectroscopy(UV-Vis) and photoluminescence(PL) measurement were further employed to study the optical properties of the obtained nanocomposite.This work can be extended to design other graphene-based hybrid nanomaterials,and the as-grown architectures may hold promise for many applications.

  10. Facile and Scalable Preparation of Solid Silver Nanoparticles (<10 nm) for Flexible Electronics

    KAUST Repository

    Tai, Yanlong

    2015-07-02

    Metal conductive ink for flexible electroncs has exhibited a promising future recently. Here, an innovative strategy was reported to synthesize silver nanocolloid (2.5 ± 0.5 nm) and separate solid silver nanoparticles (<10 nm) effectively. Specifically, silver nitrate (AgNO3) was used as silver precursor, sodium borohydride (NaBH4) as reducing agent, fatty acid (CnH2n+1COOH) as dispersant agent, ammonia (NH3•H2O) and hydrochloride (HCl) as pH regulator and complexing agent in aqueous. The main mechanism is the solubility changes of fatty acid salts (CnH2n+1 COO-NH4+) and fatty acid (CnH2n+1 COOH) coated on the synthesized silver nanoparticles (NPs) in aqueous. This change determinates the suspension and precipitation of silver NPs directly. The results show that when n in dispersant is 12, and molar ratio (C12H24O2/AgNO3) is 1.0, the separation yield of silver NPs is up to 94.8 %. After sintered at 125 ℃ for 20 minutes, the as-prepared conductive silver nanoink (20 wt. %) presents a satisfactory resistivity (as low as 6.6 μΩ.cm on polyester-PET substrate), about 4 times the bulk silver. In addition, the efficacy of the as-prepared conductive ink was verified with the construction of radio frequency antenna by inkjet printing and conductive character pattern (Fudan-Fudan) by direct wiring, showing with excellent electrical performance.

  11. Preparation of silver nanoparticle via active template under ultrasonic

    Institute of Scientific and Technical Information of China (English)

    ZHENG Min; WANG Zuo-shan; ZHU Ya-wei

    2006-01-01

    A novel method was described for the production of silver nanoparticle by using nano-carbon as active template. Special ultrasonic condition was used to assure the active effect of the template and achieve an even and stable micro-reactor system,therefore yield uniform silver nanoparticle without obvious agglomeration. By laser granularity instrument measurement, the silver nanoparticles show a mean diameter of 20.4 nm and narrow distribution between 18.7 nm and 23.0 nm according to the optimum technology. Regular spherical morphology can be observed by transmission electron microscopy(TEM). X-ray diffraction analysis indicates that Ag+ is deoxidized to form metal Ag during producing precursor, subsequent calcinations promote phase transformation from nonholonomic crystal to complete cubic crystal, which is consistent with the standard JCPDS card of silver. The results reveal that the nano-carbon in active template system not only exerts micro-reactor and steric stabilization effect, but also acts as reducing agent during the reaction.

  12. Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    de Moraes, Ana Carolina Mazarin; Lima, Bruna Araujo; de Faria, Andreia Fonseca; Brocchi, Marcelo; Alves, Oswaldo Luiz

    2015-01-01

    Methicillin-resistant Staphylococcus aureus (MRSA) has been responsible for serious hospital infections worldwide. Nanomaterials are an alternative to conventional antibiotic compounds, because bacteria are unlikely to develop microbial resistance against nanomaterials. In the past decade, graphene oxide (GO) has emerged as a material that is often used to support and stabilize silver nanoparticles (AgNPs) for the preparation of novel antibacterial nanocomposites. In this work, we report the synthesis of the graphene-oxide silver nanocomposite (GO-Ag) and its antibacterial activity against relevant microorganisms in medicine. GO-Ag nanocomposite was synthesized through the reduction of silver ions (Ag(+)) by sodium citrate in an aqueous GO dispersion, and was extensively characterized using ultraviolet-visible absorption spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The antibacterial activity was evaluated by microdilution assays and time-kill experiments. The morphology of bacterial cells treated with GO-Ag was investigated via transmission electron microscopy. AgNPs were well distributed throughout GO sheets, with an average size of 9.4±2.8 nm. The GO-Ag nanocomposite exhibited an excellent antibacterial activity against methicillin-resistant S. aureus, Acinetobacter baumannii, Enterococcus faecalis, and Escherichia coli. All (100%) MRSA cells were inactivated after 4 hours of exposure to GO-Ag sheets. In addition, no toxicity was found for either pristine GO or bare AgNPs within the tested concentration range. Transmission electronic microscopy images offered insights into how GO-Ag nanosheets interacted with bacterial cells. Our results indicate that the GO-Ag nanocomposite is a promising antibacterial agent against common nosocomial bacteria, particularly antibiotic-resistant MRSA. Morphological injuries on MRSA cells revealed a likely loss of viability as a result of the

  13. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue

    2010-03-16

    Nanoparticles that self-assemble on a liquid-liquid interface serve as the building block for making heterodimeric nanostructures. Specifically, hollow iron oxide nanoparticles within hexane form colloidosomes in the aqueous solution of silver nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectrometry, X-ray diffraction, UV-vis spectroscopy, and SQUID were used to characterize the heterodimers. Interestingly, the formation of silver nanoparticles helps the removal of spinglass layer on the hollow iron oxide nanoparticles. This work demonstrates a powerful yet convenient strategy for producing sophisticated, multifunctional nanostructures. © 2010 American Chemical Society.

  14. Preparation of conductive silk fabric with antibacterial properties by electroless silver plating

    Science.gov (United States)

    Yu, Dan; Kang, Gengen; Tian, Weicheng; Lin, Lu; Wang, Wei

    2015-12-01

    To obtain an efficient approach to metalize silk fabric, a novel method was explored and silver-plated silk was prepared. In this study, tris (2-carboxyethyl) phosphine (TCEP) was utilized as a reducing agent to generate thiol groups on the silk surface. These thiol groups react with silver ions to form metal complexes, which were used as catalytic seeds and successfully initiated electroless silver plating. A variety of methods, including Raman, XRD, TG, SEM and EDS were used to characterize the intermediates and final products. The results showed that a uniform and smooth metal layer could be obtained when compared with that without TCEP pretreatment. The silver-plated silk fabric exhibited good electrical conductivity and high anti-bacterial properties. These attractive features enable this conductive silk fabric to be a good candidate as a biomedical material.

  15. Variations in fluorescence quantum yield of basic fuchsin with silver nanoparticles prepared by femtosecond laser ablation.

    Science.gov (United States)

    Pathrose, Bini; Sahira, H; Nampoori, V P N; Radhakrishnan, P; Mujeeb, A

    2014-07-15

    Nano structured noble metals have very important applications in diverse fields such as photovoltaics, catalysis, electronic and magnetic devices, etc. In the present work, the application of dual beam thermal lens technique is employed for the determination of the absolute fluorescence quantum yield of the triaminotriphenylmethane dye, basic fuchsin in the presence of silver sol is studied. Silver sol is prepared by femtosecond laser ablation. It is observed that the presence of silver sol decreases the fluorescence quantum efficiency. The observed results are in line with the conclusion that the reduction in quantum yield in the quenching region is essentially due to the non-radiative relaxation of the absorbed energy. It is also observed that the presence of silver sol enhances the thermal lens signal which makes its detection easier at any concentration.

  16. High-temperature processing of oxide superconductors and superconducting oxide-silver oxide composite

    Science.gov (United States)

    Wu, M. K.; Loo, B. H.; Peters, P. N.; Huang, C. Y.

    1988-01-01

    High temperature processing was found to partially convert the green 211 phase oxide to 123 phase. High Tc superconductivity was observed in Bi-Sr-Cu-O and Y-Sr-Cu-O systems prepared using the same heat treatment process. High temperature processing presents an alternative synthetic route in the search for new high Tc superconductors. An unusual magnetic suspension with enhancement in critical current density was observed in the 123 and AgO composite.

  17. Surface-Enhanced Raman Scattering Study of Silver Nanoparticles Prepared by Using MC as a Template

    Directory of Open Access Journals (Sweden)

    Yudong Lu

    2013-01-01

    Full Text Available A good Ag-based SERS substrate has been prepared by one-pot reaction using methyl cellulose as a template. Effects of methyl cellulose concentration, silver ammonia chloride solution concentration, reaction duration, and reducing agent on silver nanoparticles were discussed in this paper. The performance of the obtained Ag nanoparticles was characterized by UV-visible spectroscopy, transmission electron microscopy, and surface-enhanced Raman spectroscopy. Results show that the reducing agent plays a crucial role in the performance of silver nanoparticles. Optimum preparation conditions of synthesis of SERS substrates were as follows: 10 mM silver ammonia chloride and 0.2% MC at 75°C, reducing in 0.2% reducing agent at 120 min. TEM studies reveal that particles are mostly spherical and rod in shape with an average size of 80 nm. Silver nanoparticles prepared with MC as a template have been shown to provide strong SERS enhancement signals of R6G, which can be used as a good Ag-based SERS substrate in the analytical environment for routine measurements.

  18. Preparation of silver-carbon nanotubes composites with plasma electrochemistry

    Science.gov (United States)

    Hoefft, Oliver; Lohmann, Lara; Olschewski, Mark; Endres, Frank

    2016-09-01

    Plasma electrochemistry is a powerful tool to generate free nanoparticles in aqueous solutions and especially in ionic liquids (ILs). Due to their very low vapour pressure, ionic liquids can be employed under vacuum conditions as fluid substrates or solvents. Thus, ionic liquids are well suitable electrolytes for plasma electrochemical processes delivering stable and homogeneous plasmas. We have shown that free copper and germanium nanoparticles can be obtained in ILs by applying a plasma as a mechanically contact-free electrode. Here we present our results using an argon plasma for the electrochemical synthesis of silver on pure and pre-treated multiwall carbon nanotubes (MWCNTs) in 1-ethyl-3-methylimidazolium dicyanamide. For the pre-treatment of the MWCNTS we have used a dielectric barrier discharge plasma (DBD) at atmospheric pressure. For the untreated MWCNTs we have found a formation of free silver nanoparticles between, on and in the vicinity of the carbon nanotubes. In case of the plasma treated MWCNTs a silver-carbon nanotubes composite is formed. Thus, the treatment of the MWCNTs obviously has a great influence on the deposit. Therefore we additionally have investigated the influence of the DBD on the chemical composition of the MWCNTs surface with X-Ray Photoelectron Spectroscopy.

  19. Preparation and characterization of silver nanoparticles in methyl cellulose matrix and their antibacterial activity

    Science.gov (United States)

    Kolarova, Katerina; Samec, Daniel; Kvitek, Ondrej; Reznickova, Alena; Rimpelova, Silvie; Svorcik, Vaclav

    2017-06-01

    In this work we present in situ preparation of silver nanoparticles (NPs) by reduction of silver nitrate by methyl cellulose (MC). The aim of this study was to prepare a stable solution of MC-Ag, convert it to solid film, redissolve it and determine how this process influences the form and properties of the prepared NPs. MC was analysed by UV-vis spectrometry, transmission electron microscopy and X-ray photoelectron spectroscopy; it was studied in forms of a solution and as a solid film. We also evaluated the antibacterial activity and material properties of prepared films. Our results indicate that the size and distribution of particles are not negatively influenced by the conversion process. These findings can be used for preparation of antibacterial films or as a way of nanoparticle storage.

  20. Heterogeneous nanocomposites of silver selenide and hollow platinum nanoparticles toward methanol oxidation reaction

    Science.gov (United States)

    Cui, Penglei; He, Hongyan; Liu, Hui; Zhang, Suojiang; Yang, Jun

    2016-09-01

    Making use of the electronic coupling between different domains in composite nanomaterials is an effective way to enhance the activity of electrocatalysts. Herein, we demonstrate the preparation of nanocomposites consisting of silver selenide (Ag2Se) and platinum (Pt) nanoparticles with a hollow interior by combining the inside-out diffusion of Ag in core-shell Ag-Pt nanoparticles with the synthesis of highly active hydrophobic Se species. In specific, the Ag2Se-hPt nanocomposites are found to have superior activity and stability for methanol oxidation reaction in an acidic condition due to the strong electronic coupling effect between semiconductor and metal domains. This strategy may provide a greener and less expensive way to the large-scale synthesis of Pt-based nanocomposites, and might be used to generate other heterogeneous nanomaterials with technological importance.

  1. One-step microwave-assisted colloidal synthesis of hybrid silver oxide/silver nanoparticles: characterization and catalytic study

    Science.gov (United States)

    Prakoso, S. P.; Taufik, A.; Saleh, R.

    2017-04-01

    This study reports the characterization and catalytic activities of silver-oxide/silver nanoparticles (Ag2O/Ag NPs) synthesized by microwave-assisted colloidal method in the presence of anionic sodium dodecyl sulfate (SDS) surfactant. To promote different contents of silver in silver oxide, the volume ratio (VR) of ethylene glycol (EG) was varied (VR: 10% to 14%) in relation to the total volume of distilled water solvent. The plasmonic resonance of Ag2O/Ag NPs could be detected around a wavelength of 350 nm, and it is suggested that Ag2O/Ag NPs were successfully formed in the colloid solution following exposure to microwaves. Additionally, the growth rate for each crystal phase within Ag2O and Ag was influenced by an increase of EG as revealed by x-ray diffraction patterns. The morphology, average diameter, and uniformity of Ag2O/Ag NPs were studied simultaneously by transmission electron microscopy. Infrared absorption measurement of Ag2O/Ag NPs confirmed the existence of SDS surfactant as a protective agent. Based on the characterization data, Ag2O/Ag NPs synthesized using this technique exhibited good properties, with high-yield production of NPs. The photocatalytic experiments demonstrate the key role of the crystal phase of Ag2O/Ag NPs in photocatalytic efficiency.

  2. Unusual inherent electrochemistry of graphene oxides prepared using permanganate oxidants.

    Science.gov (United States)

    Eng, Alex Yong Sheng; Ambrosi, Adriano; Chua, Chun Kiang; Saněk, Filip; Sofer, Zdeněk; Pumera, Martin

    2013-09-16

    Graphene and graphene oxides are materials of significant interest in electrochemical devices such as supercapacitors, batteries, fuel cells, and sensors. Graphene oxides and reduced graphenes are typically prepared by oxidizing graphite in strong mineral acid mixtures with chlorate (Staudenmaier, Hofmann) or permanganate (Hummers, Tour) oxidants. Herein, we reveal that graphene oxides pose inherent electrochemistry, that is, they can be oxidized or reduced at relatively mild potentials (within the range ±1 V) that are lower than typical battery potentials. This inherent electrochemistry of graphene differs dramatically from that of the used oxidants. Graphene oxides prepared using chlorate exhibit chemically irreversible reductions, whereas graphene oxides prepared through permanganate-based methods exhibit very unusual inherent chemically reversible electrochemistry of oxygen-containing groups. Insight into the electrochemical behaviour was obtained through cyclic voltammetry, chronoamperometry, and X-ray photoelectron spectroscopy experiments. Our findings are of extreme importance for the electrochemistry community as they reveal that electrode materials undergo cyclic changes in charge/discharge cycles, which has strong implications for energy-storage and sensing devices.

  3. Charge density modification of carboxylated cellulose nanocrystals for stable silver nanoparticles suspension preparation

    Energy Technology Data Exchange (ETDEWEB)

    Hoeng, Fanny; Denneulin, Aurore [Université Grenoble Alpes, LGP2 (France); Neuman, Charles [Poly-Ink (France); Bras, Julien, E-mail: julien.bras@grenoble-inp.fr [Université Grenoble Alpes, LGP2 (France)

    2015-06-15

    Synthesis of silver nanoparticles using cellulose nanocrystals (CNC) has been found to be a great method for producing metallic particles in a sustainable way. In this work, we propose to evaluate the influence of the charge density of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-oxidized CNC on the morphology and the stability of synthetized silver nanoparticles. Silver nanoparticles were obtained by sol–gel reaction using borohydride reduction, and charge density of TEMPO-oxidized CNC was tuned by an amine grafting. The grafting was performed at room temperature and neutral pH. Crystallinity and morphology were kept intact during the peptidic reaction on CNC allowing knowing the exact impact of the charge density. Charge density has been found to have a strong impact on shape, organization, and suspension stability of resulting silver particles. Results show an easy way to tune the charge density of CNC and propose a sustainable way to control the morphology and stability of silver nanoparticles in aqueous suspension.

  4. Preparation of Silver Immobilised TiO2-Hectorite for Phenol Removal and Eschericia coli Desinfection

    Directory of Open Access Journals (Sweden)

    Is Fatimah

    2013-03-01

    Full Text Available Preparation of silver immobilized TiO2-Hectorite and its application in phenol photooxidation and Eschericia coli bacteria desinfection has been conducted. Material was obtained by two steps of synthesis: preparation of TiO2-Hectorite and silver immobilization into TiO2-Hectorite. Physico-chemical characterization to the prepared material compared to raw hectorite was conducted by X-ray Diffraction, gas sorption analyzer, scanning electron microscope and DRUV-Visible spectrophotometry and for photoactivity study, phenol photooxidation and Eschericia coli desinfection were investigated. The results indicated that the modification to hectorite material improve the physico-chemical character related to its role as photo-catalyst. Kinetic study of phenol photooxidation revealed the role of TiO2 pillarization and silver immobilization in enhancing rate of reaction as well as increased photoactivity of the materials in E. coli desinfection. © 2013 BCREC UNDIP. All rights reservedReceived: 28th September 2012; Revised: 7th December 2012; Accepted: 20th Decemberber 2012[How to Cite: I. Fatimah (2013. Preparation of Silver Immobilised TiO2-Hectorite for Phenol Removal and Eschericia coli Desinfection. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 191-197. (doi:10.9767/bcrec.7.3.4047.191-197][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4047.191-197 ] View in  |

  5. Preparation of silver-hydroyapatite/PVA nanocomposites: Giant dielectric material for industrial and clinical applications

    Science.gov (United States)

    Uddin, Md Jamal; Middya, T. R.; Chaudhuri, B. K.

    2015-02-01

    Pure hydroxyappatite Ca10(PO4)6(OH)2 (or HAP) was prepared from eggshell and potassium dihydrogen phosphate (KH2PO4) by a simple self-chemical reaction method. The clean eggshell was heated at 800 °C in air giving the source of CaO. Appropriate amount of CaO was dissolved in KH2PO4 solution at 37°C for few days. The PH value decreases with increasing the duration of preparation of HAP. Silver nanoparticles derived from silver nitrate solution using black tea leaf extract had been introduced to hydroxyapatite due to its biocompatibility. The unique size- dependent properties of nanomaterials make them superior and indispensable. In this work, hydroxyapatite-silver nanoparticles/polyvinyl alcohol (PVA) composites with 4 different concentrations of hydroxyapatite (1-4 wt %) were prepared by bio-reduction method. Several techniques like XRD and SEM were used to characterize the prepared samples. Frequency dependent capacitance and conductance of the samples were measured using an impedance analyzer. The results showed a remarkable increase in dielectric permittivity (~5117) with low loss (~0.23) at1000 HZ and room temperature (300K) for 4wt% Hydroxapatie-Silver/PVA nanocomposite. Such nanocomposite might be directly applied in manufacturing clinical devices and also for embedding capacitor applications.

  6. Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations.

    Science.gov (United States)

    Salvioni, Lucia; Galbiati, Elisabetta; Collico, Veronica; Alessio, Giulia; Avvakumova, Svetlana; Corsi, Fabio; Tortora, Paolo; Prosperi, Davide; Colombo, Miriam

    2017-01-01

    The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens) and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs) are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases. Water-soluble, negatively charged silver nanoparticles (AgNPs) were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet-visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs. In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells. We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared to currently available colloidal silver, suitable for cosmetic preservatives and pharmaceutical preparations administrable to humans and/or animals as needed.

  7. Initial stages of anodic oxidation of silver in sodium hydroxide solution studied by potential sweep voltammetry and ellipsometry

    NARCIS (Netherlands)

    Droog, J.M.M.; Alderliesten, P.T.; Bootsma, G.A.

    1979-01-01

    The first stages of the oxidation of polycrystalline silver electrodes in NaOH solutions were studied by potential sweep voltammetry and ellipsometry. Formation of bulk Ag2O was found to be preceded by dissolution of silver species and deposition of a surface oxide. The equilibrium oxide coverage de

  8. Gold core@silver semishell Janus nanoparticles prepared by interfacial etching

    Science.gov (United States)

    Chen, Limei; Deming, Christopher P.; Peng, Yi; Hu, Peiguang; Stofan, Jake; Chen, Shaowei

    2016-07-01

    Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold cores, as manifested in transmission electron microscopy, UV-vis absorption, and X-ray photoelectron spectroscopy measurements. Interestingly, the Au@Ag semishell Janus nanoparticles exhibited enhanced electrocatalytic activity in oxygen reduction reactions, as compared to their Au@Ag and Ag@Au core-shell counterparts, likely due to a synergistic effect between the gold cores and silver semishells that optimized oxygen binding to the nanoparticle surface.Gold core@silver semishell Janus nanoparticles were prepared by chemical etching of Au@Ag core-shell nanoparticles at the air/water interface. Au@Ag core-shell nanoparticles were synthesized by chemical deposition of a silver shell onto gold seed colloids followed by the self-assembly of 1-dodecanethiol onto the nanoparticle surface. The nanoparticles then formed a monolayer on the water surface of a Langmuir-Blodgett trough, and part of the silver shell was selectively etched away by the mixture of hydrogen peroxide and ammonia in the water subphase, where the etching was limited to the side of the nanoparticles that was in direct contact with water. The resulting Janus nanoparticles exhibited an asymmetrical distribution of silver on the surface of the gold

  9. Preparation of iron oxides and oxihydroxides

    Directory of Open Access Journals (Sweden)

    Iveta Štyriaková

    2006-12-01

    Full Text Available Iron oxides are common minerals that occur in the environment, either naturally or as a result of human activities.The most common Fe(III-hydroxides and -oxides include ferrihydrite (Fe5HO8 .4H2O that transforms to hematite (a-Fe2O3 and/or goethite (a-FeOOH.That depends on the solution composition, temperature and pH. Depending on the composition of the solid and solution, oxidation can transform the green rust (a product formed by a metal corrosion to lepidocrocite (γ -FeOOH or magnetite (Fe(IIFe(III 2O4 . Weathering can degrade magnetite to maghemite (γ –Fe2O3 and all of the Fe-oxides are subject to an attack and dissolution by organic acids and ligands that are formed during the breakdown of biological material. Iron oxides can be prepared by hydrolysis of acidic Fe3+ solutions or by controlled oxidation of Fe2+ solutions. Goethite, lepidocrocite and magnetite were prepared by oxidation of Fe2+ solutions under slightly different values of pH, Fe concentrations and rates of oxidation. Maghemite was prepared by a thermal transformation from synthetic lepidocrocite heated in a furnace at 250 °C for 2h. Hematite was prepared by forced hydrolysis of Fe3+ solution from a chlorine system (FeCl3 at the temperature close to 100 °C under strongly acidic conditions (pH 1-2. Main mineral phases were confirmed by the RTG diffraction and IR spectroscopy method. Iron oxides are excellent, renewable adsorbents, and often control free metals through adsorption reaction.

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

    Science.gov (United States)

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

    2011-01-01

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

  11. Preparation of nanometer yttrium oxide

    Institute of Scientific and Technical Information of China (English)

    HUO; Cheng-zhang; LIU; Zhi-qiang; LIANG; Zhen-feng; LI; Xing-ying

    2005-01-01

    The nanometer yttrium oxides were obtained through precipitation in aqueous solution by reaction with ammonium bicarbonate. The reaction between yttrium chloride and ammonium bicarbonate, the effect of surfactants on particle size and the methods of controlling agglomeration were studied. Compared to other methods, the method of controlling the agglomeration by adding surfactant is one of the best methods for controlling the agglomeration of nanometer particles in wetchemical process. Increasing surfactants in process of precipitation deduced particle size, obtained narrow size distribution of primary particles. As for the concentration range studied, excess surfactants increased the particle size on the contrary. Characteristics of the thermal decomposition of yttrium carbonate were studied. It indicated that the approximate chemical composition of the precipi tate was Y(OH)Clx (CO3)(1-x/2) · 3H2O,the cubic Y2O3 was obtained above 600℃ , the specific surface and the remain chloride of nanometer Y2O3 was decreased with calcinating temperature rising. The spherical nanometer yttrium oxide was gained with primary particles<50 nm,agglomerate distribution D50 < 150 nm, BET> 35 m2/g, agglomerate constant (D50/DBET ) <6.

  12. 石墨烯/磷酸银复合材料的制备及其光催化性能研究%Study on the preparation and photocatalytic properties of graphene oxide/silver phosphate composites

    Institute of Scientific and Technical Information of China (English)

    张文; 许淼; 刘琪; 郭家伟

    2015-01-01

    The graphite oxide (GO)was prepared by an improved Hummers method.For the synthesis of the GO/Ag3 PO 4 composite,AgNO 3 solution was added to the GO solution whilst magnetically stirring. Subsequently,Na2 HPO 4 aqueous solution was added drop by drop to the solution.The prepared GO/Ag3 PO 4 composites were characterized by Scanning electron microscope (SEM),transmission elec-tron microscopy (TEM),X-ray diffraction (XRD)and X-ray photoelectron spectroscopy (XPS)analysis. The photocatalytic activity of the composite was evaluated by the degradation of Rhodamine B organic dye (RhB)solution (100 mL,10 mg/L)under visible-light irradiation.The results indicate that small Ag3 PO 4 nanoparticles are well dispersed and anchored onto the exfoliated GO sheets.Compared with bare Ag3 PO 4 ,this GO/Ag3 PO 4 composite exhibits significantly higher photocatalytic activities and im-proves stability under visible-light irradiation,which is attributed to high-surface-area GO sheets,en-hances absorption of organic dyes and efficient separation of photogenerated electron-hole pairs.The deg-radation rate of RhB solution was approximately 98% under visible light irradiation in just 20 minutes, nearly twice that of bare Ag3 PO 4 photocatalyst.%采用改进 Hummers 法制备氧化石墨,将氧化石墨烯与硝酸银溶液搅拌处理一段时间后,滴加适量磷酸氢二钠溶液,制备得到石墨烯/磷酸银(GO/Ag3 PO 4)复合材料。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X 射线衍射仪(XRD)、X 射线光电子能谱仪(XPS)等手段对制备的复合材料进行了表征,并以有机染料罗丹明 B 的降解反应为模型评价催化剂在可见光下的光催化活性。测试结果表明,该方法不仅合成过程简单,而且石墨烯表面所负载的 Ag3 PO 4纳米颗粒尺寸小、分散性好,与石墨烯的结合牢固。由于氧化石墨烯优异的吸附性能和对载流子的高迁移率,GO/Ag3 PO 4复合光催化剂显示出较高的

  13. Conductive nylon fabric through in situ synthesis of nano-silver: Preparation and characterization.

    Science.gov (United States)

    Montazer, M; Komeily Nia, Z

    2015-11-01

    A simple, green and low cost method based on Tollens' reagent is presented to synthesize a nano-conductive silver layer on nylon 6 fabric. The nylon fabric was first treated with potassium permanganate to oxidize fabric surface and thereby, increasing the number of assembled particles on the fabric surface. SEM images indicated distribution of silver nanoparticles on the fabric surface and formation of nanolayer on the fiber surface. EDX and XRD patterns confirmed assembling silver nanoparticles on the nylon fibers. The treated fabrics displayed a very low electrical resistivity i.e. 4.5Ω/sq. Furthermore, the fabric color was indicated by a reflectance spectrophotometer in order to study the effects of the synthesized nanoparticles on the fabric color. It is also indicated that oxidation process has no significant influence on the mechanical properties of the fabric, and nano-treatment revenged the negative effect of oxidation of nylon fabric. Moreover, silver nanoparticles imparted reasonable antibacterial properties to the fabric against Staphylococcus aureus.

  14. Silver nanoparticles prepared by chemical reduction-protection method, and their application in electrically conductive silver nanopaste

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jianguo, E-mail: ljg712@yahoo.com.c [Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li Xiangyou; Zeng Xiaoyan [Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2010-04-02

    Ag nanoparticles were prepared in a water-phase system with a mixture of silver-ammonia complex, sodium borohydride, and lauric acid according to molar feed ratio of approximately 6:3:1. The mechanism of preparation and separation by chemical reduction-protection method was explored. The as-synthesized Ag nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis spectroscopy, respectively. It was found that the size of high purity Ag particles was ranging from 30 to 50 nm with slight agglomeration. In addition, the as-synthesized wet Ag nanoparticles were dispersed stably in organic vehicle to formulate electrically conductive nanopaste. Upon direct-written and sintered, the array pattern of the nanopaste with the resolution of about 30 {mu}m was achieved with the electrical resistivity in the order of magnitude of 10{sup -5} {Omega} cm.

  15. Lithium insertion into silver vanadium oxide, Ag{sub 2}V{sub 4}O{sub 11}

    Energy Technology Data Exchange (ETDEWEB)

    West, K. [Dept. of Physical Chemistry, Technical Univ. of Denmark, Lyngby (Denmark); Crespi, A.M. [Medtronic, Inc., Minneapolis, MN (United States)

    1995-04-01

    Lithium insertion into the silver vanadium oxide, Ag{sub 2}V{sub 4}O{sub 11}, was investigated at 25 and 100 C, and was found to be reversible throughout the composition interval 0 < x < 7, x being the composition parameter in Li{sub x}Ag{sub 2}V{sub 4}O{sub 11}. Silver was found to be mobile in the oxide, and for 0 < x < 2 insertion of lithium is associated with reduction of silver ions to metallic silver. When lithium is extracted, silver ions re-enter the structure. (orig.)

  16. Preparation of Silver Nanoshells on Silica Particles by a Simple Two-step Process

    Institute of Scientific and Technical Information of China (English)

    Yu ZHANG; Ming MA; Ning GU; Ling XU; Kun Ji CHEN

    2004-01-01

    A simple two-step method was developed to prepare silver nanoshells coated on silica paticles.The method involves two steps: concentration of reaction precursor (AgNO3) on particle surfaces and subsequent reduction by formaldehyde.The obtained composite particles were characterized by TEM, ED, and SEM-EDS measurements.The results show that the silver nanoshell is coated on silica particle surface in the form of a polycrystalline (cubic structure) layer with average thickness of 20 nm and weight percentage of 19%.

  17. Electroless Deposition of Silver Nanoparticles on Graphene Oxide Surface and Its Applications for the Detection of Hydrogen Peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jun [Jining Medical College (China); Kim, KeunSoo [Montclair State Univ., NJ (United States); Liu, Zhenxian [Carnegie Inst. of Washington, DC (United States); Feng, Huan [Montclair State Univ., NJ (United States); Hou, Shifeng [Montclair State Univ., NJ (United States)

    2014-09-29

    We developed a new process to decorate graphene oxide (GO) with silver nanoparticles through electroless deposition technique, which was performed by treating GO with Sn2+ first and then with Ag+. Furthermore, silver nanoparticles-GO (AgNPs-GO) nanocomposites were prepared by this technique. The process was monitored using UV-vis spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM). The electrochemical behaviour of AgNPs-GO modified glassy carbon electrode was investigated by cyclic voltammetry. The potential application of this technique for hydrogen peroxide detection was tested with a range from 10 µM to 20 mM with a detection limit of 0.5 µM.

  18. The Photocatalytic Activity of SiO2-TiO2/Graphite and Its Composite with Silver and Silver oxide

    Directory of Open Access Journals (Sweden)

    Fitria Rahmawati

    2014-03-01

    Full Text Available This research study the mixed semiconductor of SiO2-TiO2 which was immobilized on graphite substrate and also studies the effect of surface modification on its mixed semiconductor. The surface modification was carried out by electrode position of Ag from 0.4 M of AgNO3 solution at various applied current. The electrode position was conducted for 30 minutes at 0.004; 0.008; 0.010; 0.012 and 0.014 A. In the electrode position cell, SiO2-TiO2/Graphite was used as cathode and a graphite rod was used as anode. The weight of deposited Ag was analyzed gravimetrically. The current efficiency of electrode position was calculated by comparing its experimental weight to its theoretical weight founded from calculation using Faraday’s equation for electrolytic cell. Meanwhile, the photo electrochemical testing was carried out to investigate the efficiency of induced photon to current conversion; it was measured as %IPCE (% Induced Photon to Current Efficiency. The crystallinity and crystal structure of the prepared materials were analyzed by X-ray diffraction and their surface morphology was analyzed by Scanning Electron Microscope (SEM. This research found that silver was deposited as silver metal, Ag and as silver oxide, AgO. The electrode position efficiency at applied current of 0.014 A is 92.30 % with diameter of cluster is 7 - 11.9 mm. It is founded that Ag and AgO deposition enhanced the efficiency of photon conversion into current up to 89.92 %. The optimum %IPCE value is at 28.6 % of Ag content. Ag-SiO2-TiO2/G has higher photo conversion than Ag-TiO2/G, shown by the %IPCE value at 300 nm is 83.25 % higher than Ag-TiO2/G. It indicates the significant role of silica network in photo excitation mechanisms in the composite material. © 2014 BCREC UNDIP. All rights reservedReceived: 1st September 2013; Revised: 26th November 2013; Accepted: 7th December 2013[How to Cite: Rahmawati, F., Wahyuningsih, S., Irianti, D. (2014. The Photocatalytic Activity of

  19. Highly catalytic hollow palladium nanoparticles derived from silver@silver-palladium core-shell nanostructures for the oxidation of formic acid

    Science.gov (United States)

    Chen, Dong; Cui, Penglei; He, Hongyan; Liu, Hui; Yang, Jun

    2014-12-01

    Hollow Palladium (hPd) nanoparticles (NPs) are prepared via a simple and mild successive method. Firstly, core-shell NPs with silver (Ag) cores and silver-palladium (Ag-Pd) alloy shells are synthesized in aqueous phase by galvanic replacement reaction (GRR) between Ag NPs and Pd2+ ion precursors. Saturated aqueous sodium chloride (NaCl) solution was then employed to remove the Ag component from the core and shell regions of core-shell Ag@Ag-Pd NPs, resulting in the formation of hPd NPs with shrunk sizes in comparison with their core-shell parents. Specifically, the hPd NPs exhibit superior catalytic activity and durability for catalyzing the oxidation of formic acid, compared with the Pd NPs reduced by NaBH4 in aqueous solution and commercial Pd/C catalyst from Johnson Matthey, mainly due to the large electrochemically active surface areas of the hollow particles. In addition, The Ag component in core-shell Ag@Ag-Pd NPs has an unfavorable influence on catalytic activity of NPs for formic acid oxidation. However, the durability could be improved due to the electron donating effect from Ag to Pd atoms in the core-shell NPs.

  20. Preparation and the antibacterial activity of silver-loaded Chitosan-grafted-vanillin sol

    Directory of Open Access Journals (Sweden)

    Jing AN

    2016-08-01

    Full Text Available In order to enhance the antibacterial activity of chitosan and expand its application field, silver nanoparticles are introduced into the matrix, and the grafting modification is carried out. Chitosan grafted vanillin (CS-g-VA is prepared with microwave-radiation method, and silver nitrate is reduced by vanillin, so that silver nanoparticles are separated evenly in CS-g-VA sol, which is Ag/CS-g-VA composite sol. The effects on the preparation of Ag/CS-g-VA composite sol are studied, and the structure and thermal property of the obtained composite sol are characterized by SEM, TEM, FTIR, XRD, UV-vis and TG-DSC. The experiment results show that the optimum conditions for the preparation of Ag/CS-g-VA are as following: Vanillin concentration of 6.0%, CS-g-VA concentration of 4.0%, and silver nitrate concentration of 0.20 mol/L. The inhibition of Ag/CS-g-VA composite sol against Escherichia coli and Bacillus subtilis is investigated through antibacterial tests. The results show that the antibacterial activity of Ag/CS-g-VA composite sol is more efficient than that of single CS materials.

  1. An electrochemical dopamine aptasensor incorporating silver nanoparticle, functionalized carbon nanotubes and graphene oxide for signal amplification.

    Science.gov (United States)

    Bahrami, Shokoh; Abbasi, Amir Reza; Roushani, Mahmoud; Derikvand, Zohreh; Azadbakht, Azadeh

    2016-10-01

    In this work, immobilization of a dopamine (DA) aptamer was performed at the surface of an amino functionalized silver nanoparticle-carbon nanotube graphene oxide (AgNPs/CNTs/GO) nanocomposite. A 58-mer DA-aptamer was immobilized through the formation of phosphoramidate bonds between the amino group of chitosan and the phosphate group of the aptamer at the 5' end. An AgNPs/CNTs/GO nanocomposite was employed as a highly catalytic label for electrochemical detection of DA based on electrocatalytic activity of the nanocomposite toward hydrogen peroxide (H2O2). Interaction of DA with the aptamer caused conformational changes of the aptamer which, in turn, decreased H2O2 oxidation and reduction peak currents. On the other hand, the presumed folding of the DA-aptamer complexes on the sensing interface inhibited the electrocatalytic activity of AgNPs/CNTs/GO toward H2O2. Sensitive quantitative detection of DA was carried out by monitoring the decrease of differential pulse voltammetric (DPV) responses of AgNPs/CNTs/GO nanocomposite toward H2O2 oxidation. The DPV signal linearly decreased with increased concentration of DA from 3 to 110nmolL(-1) with a detection limit of 700±19.23pmolL(-1). Simple preparation, low operation cost, speed and validity are the decisive factors of this method motivating its application to biosensing investigation.

  2. Characterization of silver vanadium oxide cathode material by high-resolution electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, A.M. [Medtronic, Inc., Minneapolis, MN (United States); Skarstad, P.M. [Medtronic, Inc., Minneapolis, MN (United States); Zandbergen, H.W. [National Centre for HREM, Lab. of Materials Science, Delft Univ. of Technology (Netherlands)

    1995-03-01

    The nature of the discharge reaction of lithium/silver vanadium oxide batteries was investigated. The lithiation of silver vanadium oxide, which has the formula Ag{sub 2-y}V{sub 4}O{sub 11}, proceeds by a multistep reaction, as indicated by the open-circuit voltage curve. The first step in the discharge reaction involves reduction of silver and separation of the oxide into two phases of differing composition. Electron diffraction of lithiated materials of various compositions suggests that the layered structure of the oxide is maintained, but with an increased amount of stacking disorder. High-resolution electron micrographs of lithiated Ag{sub 2-y}V{sub 4}O{sub 11} at atomic resolution could not be obtained because of sample decomposition in the electron beam. (orig.)

  3. Randomized controlled trial on collagen/oxidized regenerated cellulose/silver treatment

    DEFF Research Database (Denmark)

    Gottrup, Finn; Cullen, Breda Mary; Karlsmark, Tonny;

    2014-01-01

    Collagen/oxidized regenerated cellulose (ORC)/silver therapy has been designed to facilitate wound healing by normalizing the microenvironment and correcting biochemical imbalances in chronic wounds. The aim of this study was to compare collagen/ORC/silver therapy to control (standard treatment......). Patients with diabetic foot ulcers were randomized to either collagen/ORC/silver (24) or control treatment (15). Wound area measurements and wound fluid samples were taken weekly. Protease levels were measured in wound fluid samples to investigate differences between responders (≥50% reduction in wound...

  4. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    Science.gov (United States)

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-01

    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10−8, 1.6 × 10−8, 2.4 × 10−8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method. PMID:21289983

  5. Control of Colloid Surface Chemistry through Matrix Confinement: Facile Preparation of Stable Antibody Functionalized Silver Nanoparticles

    Science.gov (United States)

    Skewis, Lynell R.; Reinhard, Björn M.

    2010-01-01

    Here we describe a simple yet efficient gel matrix assisted preparation method which improves synthetic control over the interface between inorganic nanomaterials and biopolymers and yields stable biofunctionalized silver nanoparticles. Covalent functionalization of the noble metal surface is aided by the confinement of polyethylene glycol acetate functionalized silver nanoparticles in thin slabs of a 1% agarose gel. The gel confined nanoparticles can be transferred between reaction and washing media simply by immersing the gel slab in the solution of interest. The agarose matrix retains nanoparticles but is swiftly penetrated by the antibodies of interest. The antibodies are covalently anchored to the nanoparticles using conventional crosslinking strategies, and the resulting antibody functionalized nanoparticles are recovered from the gel through electroelution. We demonstrate the efficacy of this nanoparticle functionalization approach by labeling specific receptors on cellular surfaces with functionalized silver nanoparticles that are stable under physiological conditions. PMID:20161660

  6. Preparation of silver nanoparticles in virgin coconut oil using laser ablation.

    Science.gov (United States)

    Zamiri, Reza; Azmi, B Z; Sadrolhosseini, Amir Reza; Ahangar, Hossein Abbastabar; Zaidan, A W; Mahdi, M A

    2011-01-07

    Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10(-8), 1.6 × 10(-8), 2.4 × 10(-8), respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method.

  7. Catalytic properties and activity of copper and silver containing Al-pillared bentonite for CO oxidation

    Science.gov (United States)

    Basoglu, Funda Turgut; Balci, Suna

    2016-02-01

    Al-pillared bentonite (Al-PB) using bentonite obtained from the Middle Anatolia region (Hançılı) was synthesized, and Cu@Al-PB and Ag@Al-PB were obtained after the second metal impregnation step. Cu/AlPB prepared using a hydrothermal method was obtained with a Cu/(Cu + Al) mole ratio of 0.05. The SEM/EDS, scanning electron microscopy/energy dispersive X-ray spectroscopy analyses indicated that the impregnation method resulted in a higher copper loading in the structure. Based on the XPS, X-ray photoelectron spectroscopy analysis, the aluminum in all of the samples was in the Al2O3 form with 2s and 2p3 orbitals. Although no copper peaks were observed for Cu/Al-PB, the 2p3 and 2p1 orbitals of copper as well as the 3d3 and 3d5 orbitals of silver were observed in the copper or silver impregnated samples, respectively. Metal incorporation resulted in an increase especially in the strength of the Brønsted acid peaks in the FTIR, Fourier transform infrared spectra. The intensity of the peaks corresponding to the Brønsted sites did not change substantially as pyridine desorption temperature increased. The impregnated samples created a decrease in the 50% conversion temperature for carbon monoxide oxidation. Cu@Al-PB, which was calcined at 500 °C, gave a carbon monoxide conversion that was as high as 100% at approximately 200 °C and maintained its activity to 500 °C. In the impregnated samples, the reaction may use the surface oxygen provided by the metal oxide.

  8. Structure and photocatalysis activity of silver doped titanium oxide nanotubes array for degradation of pollutants

    Science.gov (United States)

    Al-Arfaj, E. A.

    2013-10-01

    Semiconductor titanium oxide showed a wonderful performance as a photocatalysis for environmental remediation. Owing to high stability and promising physicochemical properties, titanium oxide nanostructures are used in various applications such as wastewater treatment, antimicrobial and air purification. In the present study, titanium oxide nanotubes and silver doped titanium oxide nanotubes were synthesized via anodic oxidation method. The morphology and composition structure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results depicted that nanotubes possess anatase phase with average tube diameter of 65 nm and 230 ± 12 nm in length. The band gap of the un-doped and silver doped titanium dioxide nanotubes was determined using UV-Vis. spectrophotometer. The results showed that the band gap of titanium dioxide nanotubes is decreased when doped with silver ions. The photocatalysis activity of un-doped and silver doped TiO2 nanotubes were evaluated in terms of degradation of phenol in the presence of ultra violet irradiation. It was found that silver doped TiO2 nanotubes exhibited much higher photocatalysis activity than un-doped TiO2 nanotubes.

  9. 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.

  10. ANTIMICROBIAL TEXTILE PREPARED BY SILVER DEPOSITION ON DIELECTRIC BARRIER DISCHARGE TREATED COTTON/POLYESTER FABRIC

    Directory of Open Access Journals (Sweden)

    Mirjana Kostić

    2008-11-01

    Full Text Available The objective of this research was to impart the additional value on cotton//polyester (Co/PES fabrics (i.e. antimicrobial properties to improve the quality of life and thus to tap new markets with the product. In this paper, silver ions were incorporated in Co/PES fabrics by chemisorptions into the fabric previously treated in a dielectric barrier discharge (DBD. A series of the DBD fabric treatments were done in order to determine the most suitable experimental conditions for the DBD activation of the fabric surface, while the optimal conditions for silver ions sorption by Co/PES fabrics were determined by changing sorption conditions. The antimicrobial Co/PES fabrics prepared by dielectric barrier discharge mediated silver deposition show an antimicrobial activity against tested pathogens: S. aureus, E. coli, and C. albicans under in vitro conditions. The obtained results confirm the practicability of the plasma modification process and furthermore show that with some delays in the next step, i.e. silver ion sorption, we can get the increase in the amount of the sorbed silver ions; the maximum sorption capacity of modified Co/PES fabrics was 0.135 mmol of Ag+ ions per gram of a fabric.

  11. Preparation of silver nanoparticle containing silica micro beads and investigation of their antibacterial activity

    Science.gov (United States)

    Quang, Dang Viet; Sarawade, Pradip B.; Hilonga, Askwar; Kim, Jong-Kil; Chai, Young Gyu; Kim, Sang Hoon; Ryu, Jae-Yong; Kim, Hee Taik

    2011-05-01

    Silver nanoparticle containing silica micro beads (Ag-NPBs) were successfully prepared by using sodium silicate, a cheap precursor, involving chemical reductive method. First, silica gel was synthesized and crushed into micro beads which have sizes ranging from 0.5 to 1 mm. Silica micro beads were then modified with 3-aminopropyltriethoxysilane to graft amino functional groups onto their surface. Silver ions were loaded onto the surface of the modified silica and reduced to silver crystal by adding NaBH 4. The presence of silver nanoparticles as well as structure of materials was characterized with FT-IR, XRD, BET, FE-SEM, TEM, UV-vis spectrophotometer, and optical microscope. Silver nanoparticles with an average size about 5 nm were found in the pore and on the surface of amino functionalized silica beads. Ag-NPBs samples were tested for their antibacterial activity against Escherichia coli ( E. coli). The antibacterial activity was examined by both zone inhibition and test tube test method. Biological results indicated that the synthesized materials have an excellent antibacterial performance against E. coli which was completely inhibited after 5 min contact with Ag-NPBs.

  12. Structural and silver/vanadium ratio effects on silver vanadium phosphorous oxide solution formation kinetics: impact on battery electrochemistry.

    Science.gov (United States)

    Bock, David C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

    2015-01-21

    The detailed understanding of non-faradaic parasitic reactions which diminish battery calendar life is essential to the development of effective batteries for use in long life applications. The dissolution of cathode materials including manganese, cobalt and vanadium oxides in battery systems has been identified as a battery failure mechanism, yet detailed dissolution studies including kinetic analysis are absent from the literature. The results presented here provide a framework for the quantitative and kinetic analyses of the dissolution of cathode materials which will aid the broader community in more fully understanding this battery failure mechanism. In this study, the dissolution of silver vanadium oxide, representing the primary battery powering implantable cardioverter defibrillators (ICD), is compared with the dissolution of silver vanadium phosphorous oxide (Ag(w)VxPyOz) materials which were targeted as alternatives to minimize solubility. This study contains the first kinetic analyses of silver and vanadium solution formation from Ag0.48VOPO4·1.9H2O and Ag2VP2O8, in a non-aqueous battery electrolyte. The kinetic results are compared with those of Ag2VO2PO4 and Ag2V4O11 to probe the relationships among crystal structure, stoichiometry, and solubility. For vanadium, significant dissolution was observed for Ag2V4O11 as well as for the phosphate oxide Ag0.49VOPO4·1.9H2O, which may involve structural water or the existence of multiple vanadium oxidation states. Notably, the materials from the SVPO family with the lowest vanadium solubility are Ag2VO2PO4 and Ag2VP2O8. The low concentrations and solution rates coupled with their electrochemical performance make these materials interesting alternatives to Ag2V4O11 for the ICD application.

  13. Synaptic plasticity and oscillation at zinc tin oxide/silver oxide interfaces

    Science.gov (United States)

    Murdoch, Billy J.; McCulloch, Dougal G.; Partridge, James G.

    2017-02-01

    Short-term plasticity, long-term potentiation, and pulse interval dependent plasticity learning/memory functions have been observed in junctions between amorphous zinc-tin-oxide and silver-oxide. The same junctions exhibited current-controlled negative differential resistance and when connected in an appropriate circuit, they behaved as relaxation oscillators. These oscillators produced voltage pulses suitable for device programming. Transmission electron microscopy, energy dispersive X-ray spectroscopy, and electrical measurements suggest that the characteristics of these junctions arise from Ag+/O- electromigration across a highly resistive interface layer. With memory/learning functions and programming spikes provided in a single device structure, arrays of similar devices could be used to form transistor-free neuromorphic circuits.

  14. Comparison of properties of silver-metal oxide electrical contact materials

    Directory of Open Access Journals (Sweden)

    Ćosović V.

    2012-01-01

    Full Text Available Changes in physical properties such as density, porosity, hardness and electrical conductivity of the Ag-SnO2 and Ag-SnO2In2O3 electrical contact materials induced by introduction of metal oxide nanoparticles were investigated. Properties of the obtained silver-metal oxide nanoparticle composites are discussed and presented in comparison to their counterparts with the micro metal oxide particles as well as comparable Ag-SnO2WO3 and Ag-ZnO contact materials. Studied silvermetal oxide composites were produced by powder metallurgy method from very fine pure silver and micro- and nanoparticle metal oxide powders. Very uniform microstructures were obtained for all investigated composites and they exhibited physical properties that are comparable with relevant properties of equivalent commercial silver based electrical contact materials. Both Ag-SnO2 and Ag- SnO2In2O3 composites with metal oxide nanoparticles were found to have lower porosity, higher density and hardness than their respective counterparts which can be attributed to better dispersion hardening i.e. higher degree of dispersion of metal oxide in silver matrix.

  15. 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.

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

    Directory of Open Access Journals (Sweden)

    Simona Liliana Iconaru

    2014-01-01

    Full Text Available 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 xAg=0.5 are effective against E. coli and S. aureus after 24 h.

  17. One-step preparation of antimicrobial silver nanoparticles in polymer matrix

    Energy Technology Data Exchange (ETDEWEB)

    Lyutakov, O., E-mail: lyutakoo@vscht.cz; Kalachyova, Y. [Institute of Chemical Technology, Department of Solid State Engineering (Czech Republic); Solovyev, A. [Institute of Chemical Process Fundamentals of the ASCR (Czech Republic); Vytykacova, S. [Institute of Chemical Technology, Department of Glass and Ceramics (Czech Republic); Svanda, J.; Siegel, J. [Institute of Chemical Technology, Department of Solid State Engineering (Czech Republic); Ulbrich, P. [Institute of Chemical Technology, Department of Biochemistry and Microbiology (Czech Republic); Svorcik, V. [Institute of Chemical Technology, Department of Solid State Engineering (Czech Republic)

    2015-03-15

    Simple one-step procedure for in situ preparation of silver nanoparticles (AgNPs) in the polymer thin films is described. Nanoparticles (NPs) were prepared by reaction of N-methyl pyrrolidone with silver salt in semi-dry polymer film and characterized by transmission electron microscopy, XPS, and UV–Vis spectroscopy techniques. Direct synthesis of NPs in polymer has several advantages; even though it avoids time-consuming NPs mixing with polymer matrix, uniform silver distribution in polymethylmethacrylate (PMMA) films is achieved without necessity of additional stabilization. The influence of the silver concentration, reaction temperature and time on reaction conversion rate, and the size and size-distribution of the AgNPs was investigated. Polymer films doped with AgNPs were tested for their antibacterial activity on Gram-negative bacteria. Antimicrobial properties of AgNPs/PMMA films were found to be depended on NPs concentration, their size and distribution. Proposed one-step synthesis of functional polymer containing AgNPs is environmentally friendly, experimentally simple and extremely quick. It opens up new possibilities in development of antimicrobial coatings with medical and sanitation applications.

  18. A solid control strategy for preparation of silver nanoparticles in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Daechul [Soonchunhyang University, Asan (Korea, Republic of); Kwon, Sung-Hyun [Gyeongsang National University, Tongyong (Korea, Republic of)

    2015-12-15

    Uniformly distributed, spherically shaped, mild concentrated silver nanoparticles with single-digit to hundreds nm size have been prepared by reducing silver nitrate with popular reducers like sodium borohydride or hydrazine in the presence of ordinary stabilizers such as SDS, PVP, Polysorbates and ultrasonication. Uv-visble spectroscopic analysis, particle size analysis, and particle-imaging through transmission electron microscopy (TEM) were used for nanoparticle characterization. Higher temperature accelerated the reduction rates, which follows the typical autocatalytic kinetics. Particularly, ultrasonication helped to facilitate the crucial stage of reduction phase to result in excellent quality of nanosolution, such as narrow distribution of particles and size uniformity. We found that initial location or arrangement of silver ions in clouds of stabilizers and 'effectve mixing' in the stage of reduction were vital for successful preparation of silver nanosolution. Also, reagent/stabilizer ratio, reducer input, solution environment such as pH, temperature, and stabilizer properties were optimized and discussed in detail. Proper selection of stabilizer and molar ratio to reagent and effective 'mixing' for preventing grain growth needs to be investigated more in the future work.

  19. Preparation of poly (Vinyl Alcohol) nanofibers containing silver nanoparticles by gamma-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yun Hye [AMOTECH Co., Ltd., Kimpo (Korea, Republic of); Shin, Jun Wha; An, Sung Jun; Youn, Min Ho; Lim, Youn Mook; Gwon, Hui Jeong; Nho, Young Chang [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2008-08-15

    PVA nanofibers containing silver nanoparticles were prepared by two methods. The first method was electrospinning of irradiated solution. The prepared PVA/AgNO{sub 3} solution was irradiated by gamma-rays. And then the irradiated solution was electrospun. The second method was irradiation of electrospun nanofibers. Nanofibers prepared by electrospinning of unirradiated PVA/AgNO{sub 3} solution. The morphology of the nanofibers was observed with a SEM, TEM. When the irradiated PVA/AgNO{sub 3} solution were electrospun, the average size of the Ag nanoparticles was increased, but their number was decreased.

  20. [Potential exposure to silver nanoparticles during spraying preparation for air-conditioning cleaning].

    Science.gov (United States)

    Jankowska, Elzbieta; Łukaszewska, Joanna

    2013-01-01

    Unique properties of engineered nanomaterials (ENMs) and products made of them have contributed to a rapid progress in the production and application of ENMs in different branches of industry and in factories with different production scale. Bearing in mind that nano-objects (nanoplates, nanofibres, nanoparticles), emitted during ENM production and application, can cause many diseases, even those not yet recognized, extensive studies have been carried all over the world to assess the extent of exposure to nano-objects at workstations and related health effects in workers employed in ENM manufacture and application processes. The study of potential exposure to silver nanoparticles contained in the preparation for air-conditioning cleaning (Nano Silver from Amtra Sp. z o.o.) involved the determination of concentrations and size distribution of particles, using different devices, allowing for tracing changes in a wide range of dimensions, from nano-size (10 nm) to micrometer-size (10 pm), of the particles which are usually inhaled by humans. The results of the study shows that even during a short-term spraying of Nano Silver preparation (for 10 s) at the distance of 52 cm from the place of preparation spraying--particles of 10 nm-10 microm can be emitted into in the air. During a three-fold preparation spraying in similar conditions differences in concentration increase were observed, but in each case the particles remained in the air for a relatively long time.

  1. Biocidal effects of silver and zinc oxide nanoparticles on the bioluminescent bacteria

    Science.gov (United States)

    Taran, M. V.; Starodub, N. F.; Katsev, A. M.; Guidotti, M.; Khranovskyy, V. D.; Babanin, A. A.; Melnychuk, M. D.

    2013-11-01

    The effect of silver and zinc oxide nanoparticles in combination with alginate on bioluminescent Photobacterium leiognathi Sh1 bacteria was investigated. Silver nanoparticles were found to be more toxic than zinc oxide nanoparticles on bioluminescent bacteria. The nanoparticles and their ions released results in the same effect, however, it was absent in combination with alginate. The effective inhibiting concentration (EC50) for silver nanoparticles was found about 0.3 - 0.4 μg mL-1, which was up to two times larger then for zinc oxide nanoparticles. The absence of sodium chloride in the tested media prevented the formation of colloidal particles of larger size and the effective inhibition concentrations of metal derivatives were lower than in the presence of sodium chloride.

  2. Which Oxide for Low-Emissivity Glasses? First-Principles Modeling of Silver Adhesion.

    Science.gov (United States)

    Cornil, David; Wiame, Hugues; Lecomte, Benoit; Cornil, Jérôme; Beljonne, David

    2017-05-31

    Density functional theory (DFT) calculations were performed to assess the work of adhesion of silver layers deposited on metal oxide surfaces differing by their chemical nature (ZnO, TiO2, SnO2, and ZrO2) and their crystallographic face. The calculated work of adhesion values range from ∼0 to 3 J m(-2) and are shown to originate from the interplay between ionic (associated with charge transfer at the interface) and covalent (as probed by atomic bond orders between silver and the metal oxide atoms) interactions. The results are discussed in the context of the design of silver/metal oxide interfaces for low-emissivity glasses.

  3. Enhanced Bonding of Silver Nanoparticles on Oxidized TiO2(110)

    DEFF Research Database (Denmark)

    Hansen, Jonas Ørbæk; Salazar, Estephania Lira; Galliker, Patrick

    2010-01-01

    The nucleation and growth of silver nanoclusters on TiO2(110) surfaces with on-top O adatoms (oxidized TiO2), surface O vacancies and H adatoms (reduced TiO2) have been studied. From the interplay of scanning tunneling microscopy/photoelectron spectroscopy experiments and density functional theory...... calculations, it is found that silver clusters are much more strongly bonded to oxidized TiO2(110) surfaces than to reduced TiO2(110) model supports. It is shown that electronic charge can be transferred from silver clusters to the oxidized TiO2(110) surface as evidenced by the reappearance of the Ti3d defect...... state upon silver exposure. Furthermore, from both scanning tunneling microscopy data and density functional theory calculations the most favorable adsorption site of silver monomers on oxidized TiO2(110) is one that bridges between on-top O adatoms and regular surface O atoms nearby....

  4. 银纤维的制备和应用%Preparation and Application of Silver Fiber

    Institute of Scientific and Technical Information of China (English)

    毛俊峰; 李可欣

    2013-01-01

    The characteristics including antibacterial, deodorant, antistatic, electromagnetic shielding and attemperation of silver fiber are introduced. The fiber preparation methods with the popularly applications attracted much attention are also described. Finally, the existing problems and predicts prospect of the preparation and application of silver fiber are pointed out.%介绍了银纤维的抗菌、除臭、抗静电、电磁波屏蔽等特性;同时叙述了银纤维的制备方法,以及银纤维作为备受关注的功能性纤维的应用;最后指出了目前银纤维制备和应用中存在的问题,并对其前景进行了展望.

  5. Waste treatment in NUCEF facility with silver mediated electrochemical oxidation technique

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, M.; Sugikawa, S. [Tokai Establishment, Japan Atomic Energy Research Institute, Tokai-Mura, Naka-Gun, Ibaraki-Ken (Japan)

    2000-07-01

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

  6. Photochemical decoration of silver nanoparticles on graphene oxide nanosheets and their optical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Nguyen Thi; Chi, Do Thi; Dinh, Ngo Xuan; Hung, Nguyen Duy; Lan, Hoang [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Tuan, Pham Anh [Vietnam Metrology Institute, 08 Hoang Quoc Viet Road, Cau Giay District, Hanoi (Viet Nam); Thang, Le Hong [School of Materials Science and Engineering, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Trung, Nguyen Ngoc [School of Engineering Physics, Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Hoa, Nguyen Quang [Department of Physics, Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Huy, Tran Quang [Laboratory for Ultrastructure and Bionanotechnology (LUBN), National Institute of Hygiene and Epidemiology (NIHE), No. 1 Yecxanh Street, Hai Ba Trung District, Hanoi (Viet Nam); Quy, Nguyen Van [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Duong, Thanh-Tung [Department of Materials Engineering, Chungnam National University, Daeduk Science Town, 305-764 Daejeon (Korea, Republic of); Phan, Vu Ngoc [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan, E-mail: tuan.leanh1@hust.edu.vn [Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), No. 1 Dai Co Viet Street, Hai Ba Trung District, Hanoi (Viet Nam)

    2014-12-05

    Highlights: • A photochemical method for effective decoration of the Ag-NPs on GO nanosheets is presented. • The average size of the Ag-NPs on the GO nanosheets obtained ∼6–7 nm with uniform size distribution. • Surface interaction of Ag-NPs with GO nanosheets leads to surface plasmon-enhanced luminescence. - Abstract: Nanohybrid materials based on silver nanoparticles (Ag-NPs) and graphene oxide (GO) are attracting considerable research interest because of their potential many applications including surface-enhanced Raman scattering, catalysis, sensors, biomedicine and antimicrobials. In this study, we established a simple and effective method of preparing a finely dispersed Ag-GO aqueous solution using modified Hummer and photochemical technique. The Ag-NPs formation on GO nanosheets was analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the GO nanosheets was approximately 6–7 nm with nearly uniform size distribution. The Ag-GO nanohybrid also exhibits an adsorption band at 435 nm because of the presence of Ag-NPs on the GO nanosheets. Photoluminescence emission of the Ag-GO nanohybrid was found at 400 and 530 nm, which can be attributed to the interaction between the luminescence of exploited GO nanosheets and localized surface plasmon resonance from metallic Ag-NPs. The observed excellent optical properties of the as-prepared Ag-GO nanohybrid showed a significant potential for optoelectronics applications.

  7. Self-Assembly of Single-Crystal Silver Microflakes on Reduced Graphene Oxide and their Use in Ultrasensitive Sensors

    KAUST Repository

    Chen, Ye

    2016-01-19

    Compared to 1D structures, 2D structures have higher specific and active surface, which drastically improves electron transfer and extensibility along 2D plane. Herein, 2D-single crystal silver microflakes (AgMFs) are prepared for the first time in situ on reduced graphene oxide (RGO) by solvothermal synthesis with thickness around 100 nm and length around 10 μm. The oriented attachment mechanism is hypothesized to control the silver crystal growth and self-assembly of reduced silver units to form single-crystal AgMF structure on RGO sheets. Employing it as an electrode to fabricate reliable and extremely sensitive pressure sensors verifies the applicability of this novel 2D structure. Contrary to nanowires, 2D microflakes can intercalate better within the polymer matrix to provide an enhanced network for electron movement. The designed sensor can retain more than 4.7 MPa-1 after 10 000 cycles. The design proves functional for monitoring various actions such as wrist movement, squatting, walking, and delicate finger touch with high durability. A highly sensitive and flexible pressure sensor is fabricated based on the self-assembly of silver microflakes on reduced graphene oxide. This sensor exhibits an excellent pressure sensitivity as it can retain more than 4.7 MPa-1 after 10 000 cycles. This system is successfully used to monitor wrist movement, walking, and squatting and can be applied in touch screen panels, robotic systems, and prosthetics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Investigation of the antimicrobial effect of silver doped Zinc Oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Farzane Hoseyni Dowlatababdi

    2017-01-01

    Full Text Available The antimicrobial effect of metal nanoparticles such as zinc oxide and silver nanoparticles has been taken into great consideration separately during recent years. The useful application of these nanoparticles in the areas of medicine, biotechnology, and professional prevention of microbes motivated us. The aim of this study was to evaluate antibacterial activity properties of silver doped zinc oxide nanoparticles (ZnO: Ag by synthesizing them.Materials and Methods: The silver doped zinc oxide nanoparticles (ZnO:Ag were provided with wet chemical method in an aqueous solution, and mercaptoethanol. The physical properties of the sample were investigated with UV, XRD, and TEM techniques. Then, the antibacterial activity of 50 to 3.12 concentrations of the silver doped zinc oxide nanoparticles (ZnO:Ag was investigated against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis by well diffusion method. Moreover, the MIC and MBC values of these nanoparticles were assessed by microdilution method.Results: The size of the nanoparticles was obtained as between 12 and 13 nanometers in average. The optical study of the nanoparticles demonstrated that the band gap of the silver doped nanostructures is higher than that of the pure sample. The zone of inhibition diameter in the presence of 50 mg/ml density was 19, 15 and 8 mm against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, respectively.Conclusion: The results showed that silver doped zinc oxide nanoparticles prevented Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, but did not affect Enterococcus faecalis. The zone of inhibition diameter increases as the density of the nanoparticles does.

  9. Antidiabetic Activity of Zinc Oxide and Silver Nanoparticles on Streptozotocin-Induced Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Ali Alkaladi

    2014-01-01

    Full Text Available The use of nanoparticles in medicine is an attractive proposition. In the present study, zinc oxide and silver nanoparticles were evaluated for their antidiabetic activity. Fifty male albino rats with weight 120 ± 20 and age 6 months were used. Animals were grouped as follows: control; did not receive any type of treatment, diabetic; received a single intraperitoneal dose of streptozotocin (100 mg/kg, diabetic + zinc oxide nanoparticles (ZnONPs, received single daily oral dose of 10 mg/kg ZnONPs in suspension, diabetic + silver nanoparticles (SNPs; received a single daily oral dose of SNP of 10 mg/kg in suspension and diabetic + insulin; received a single subcutaneous dose of 0.6 units/50 g body weight. Zinc oxide and silver nanoparticles induce a significant reduced blood glucose, higher serum insulin, higher glucokinase activity higher expression level of insulin, insulin receptor, GLUT-2 and glucokinase genes in diabetic rats treated with zinc oxide, silver nanoparticles and insulin. In conclusion, zinc oxide and sliver nanoparticles act as potent antidiabetic agents.

  10. Facile route for preparation of silver nanoparticle-coated precipitated silica

    Science.gov (United States)

    Quang, Dang Viet; Sarawade, Pradip B.; Hilonga, Askwar; Park, Sung Dae; Kim, Jong-Kil; Kim, Hee Taik

    2011-02-01

    In this research, a facile route was used to prepare silver nanoparticle-coated precipitated silica using sodium silicate, a cheap precursor. Precipitated silica (PS) was synthesized by dropping 8% H2SO4 into a mixed solution of sodium silicate 24% (Na2O·3.4SiO2) and NaCl 4%; under constant stirring. The precipitated silica was then modified by simultaneous addition of 3-aminopropyltriethoxysilane (3-APTES) and 8% H2SO4. The resulting material was aged at 80 °C for 1 h to produce amino-functionalized precipitated silica (AFPS). Silver nanoparticle-coated precipitated silica (Ag-NPS) was synthesized by adding silver nitrate (AgNO3). The synthesis procedure also involved mixing for 2 h and dropping 0.05 M sodium borohydride (NaBH4). The final products, namely, PS, AFPS, and Ag-NPS were characterized using BET analyzer, FE-SEM, TEM and XRD. Silver nanoparticles with an average size ranging from 18 to 25 nm were found mostly coated on the exterior layer of the precipitated silica. The synthesis method reported in this work is facile and might be used for large-scale industrial production of inexpensive Ag-NPS.

  11. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    Directory of Open Access Journals (Sweden)

    Reza Zamiri,B Z Azmi. Amir Reza Sadrolhosseini

    2011-01-01

    Full Text Available Reza Zamiri1, B Z Azmi1,2, Amir Reza Sadrolhosseini1, Hossein Abbastabar Ahangar3, A W Zaidan1, M A Mahdi41Department of Physics, 2Advanced Materials and Nanotechnology Laboratory, 3Department of Chemistry, 4Wireless and Photonics Networks Research Center, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaAbstract: Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10-8, 1.6 × 10-8, 2.4 × 10-8, respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method.Keywords: silver nanoparticles, laser ablation, virgin coconut oil

  12. 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.

  13. Preparation of crosslinked amphiphilic silver nanogel as thin film corrosion protective layer for steel.

    Science.gov (United States)

    Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; Ezzat, Abdelrahman O

    2014-07-17

    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.

  14. Preparation of Silver Nano-Particles and Use as a Material for Water Sterilization

    Directory of Open Access Journals (Sweden)

    Tran Hong Con

    2011-01-01

    Full Text Available High dispersed nanodimensional silver metal (nanosilver solution of concentration ranging from 40 to 400 mg/L was prepared from silver nitrate in water media with and without dispersing reagent. The reduction process was initiated by ammonium hydroxide and glucose was used as a reductive reagent. The nanosilver solution was characterized by color changing from light-yellow to yellow, brown, red-brown, brown-green, dark-green, blue, dark-blue and those were depending on silver concentration and dimension of silver metal particles. The nanosilver solution was possibly used as a direct sterilizing reagent or coating on calcinated laterite grains to create sterilizing material in bacterial removing filter. Direct sterilization ability of nanosilver solution and nanosilver coated material was investigated. The results showed that with 10 ppb nanosilver in supplied water, all bacteria will be removed within 25–30 min. 10 mm thick layer of silica gel or 20 mm of calcinated laterite coated nanosilver could remove all bacteria in water flowed though with maximum flow rate of 100 L.m2/min. Moreover, sterilizing material was nontoxic and applicable for drinking water production.

  15. Preparation and characterization of mesoporous indium oxide

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi-zhe; CHENG Zhi-xuan; PAN Qing-yi; DONG Xiao-wen; ZHANG Jian-cheng; PAN Ling-li

    2009-01-01

    Indium oxide nanocrystals with mesoporous structure were successfully synthesized by using triblock copolymer as a template,and characterized by thermogravimetry-differential scanning calorimeter (TG-DSC),X-ray powder diffraction (XRD),high resolution transmission electron microscopy (HRTEM) and N2 adsorption.A high EO/PO ratio is thought to be the key point to prepare mesoporous In2O3.The results show that the average pore diameter of the products is 6 nm,the BET surface area is 54.78 m2/g,and the adsorbing pore volume is 0.345 cm3/g.After comparing with normal indium oxide nanoparticles by BET test,mesoporous indium oxide demonstrates a large difference in adsorbing pore volume and average pore diameters from normal ones.

  16. Electrical properties of silver selenide thin films prepared by reactive evaporation

    Indian Academy of Sciences (India)

    M C Santhosh Kumar; B Pradeep

    2002-10-01

    The electrical properties of silver selenide thin films prepared by reactive evaporation have been studied. Samples show a polymorphic phase transition at a temperature of 403 ± 2 K. Hall effect study shows that it has a mobility of 2000 cm2V–1s–1 and carrier concentration of 1018 cm–3 at room temperature. The carriers are of -type. X-ray diffraction study indicates that the as-prepared films are polycrystalline in nature. The lattice parameters were found to be = 4.353 Å, = 6.929 Å and = 7.805 Å.

  17. Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method.

    Science.gov (United States)

    Rhim, Jong-Whan; Wang, Long-Feng; Lee, Yonghoon; Hong, Seok-In

    2014-03-15

    Silver nanoparticles (AgNPs) were prepared by a laser ablation method and composite films with the AgNPs and agar were prepared by solvent casting method. UV-vis absorbance test and transmission electron microscopy (TEM) analysis results revealed that non-agglomerated spherical AgNPs were formed by the laser ablation method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the AgNPs with the maximum absorption peaks of 400-407 nm. X-ray diffraction (XRD) test results also exhibited characteristic AgNPs crystals with diffraction peaks observed at 2θ values of 38.39°, 44.49°, and 64.45°, which were corresponding to (111), (200), and (220) crystallographic planes of face-centered cubic (fcc) silver crystals, respectively. Thermogravimetric analysis (TGA) results showed that thermal stability of the agar/AgNPs composite films was increased by the inclusion of metallic silver. Water vapor barrier properties and surface hydrophobicity of the agar/AgNPs films increased slightly with the increase in AgNPs content but they were not statistically significant (p>0.05), while mechanical strength and stiffness of the composite films decreased slightly (p<0.05). The agar/AgNPs films exhibited distinctive antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens.

  18. Antibacterial continuous nanofibrous hybrid yarn through in situ synthesis of silver nanoparticles: Preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Barani, Hossein, E-mail: barani@birjand.ac.ir

    2014-10-01

    Nanofibrous hybrid yarns of polyvinyl alcohol (PVA) and poly-L-lactide acid (PLLA) with the antibacterial activity were prepared that contains 0, 5, 10, 20, and 30 wt.% of silver nanoparticles according to the PVA polymer content. This was performed by electrospinning using distilled water and 2, 2, 2-trifluoroethanol as a solvent for PVA and PLLA respectively, and sodium borohydride was used as a reducing agent. The scanning electron microscope observation confirmed the formation of AgNPs into the PVA nanofiber structure, and they were uniform, bead free, cylindrical and smooth. The diameter of hybrid yarns and their nanofiber component was decreased as the silver nitrate concentration in electrospinning solutions was increased. The differential scanning calorimetry results indicated that the silver nanoparticles can form interactions with polymer chains and decrease the melting enthalpy. The mechanical analysis showed a lower stress and strain at break of the AgNP-loaded nanofibrous hybrid yarns than the unloaded hybrid yarn. However, there wasn't a statistically significant difference between the strain at break of electrospun nanofibrous hybrid yarns. Moreover, the bactericidal efficiency of all loaded samples was over 99.99%. - Highlights: • Nanofibrous hybrid yarns of PVA/PLLA with antibacterial activity were prepared. • The diameter of nanofibers was decreased as the AgNP concentration was increased. • AgNPs make interactions with amorphous phase of polymer and increase the Tg. • All loaded samples presented a good bactericidal and bacteriostatic efficiency.

  19. Silver(Ⅰ) Oxide Mediated Regioselective Monoacylation of 2,4-Dihydroxyls in L-Rhamnopyranosides

    Institute of Scientific and Technical Information of China (English)

    Qian YANG; Xing Mei ZHU; Jin Song YANG

    2006-01-01

    A series of acyls (Ac, Bz and Ts) were introduced regioselectively to the 2-hydroxyl in methyl and ally 3-O-benzyl-α-L-rhamnopyranosides mediated by silver(Ⅰ) oxide in the presence of a catalytic amount of potassium iodide in 56-78% yields.

  20. Thickness dependence of oxygen permeation through erbia-stabilized bismuth oxide-silver composites

    NARCIS (Netherlands)

    Chen, C.S.; Kruidhof, H.; Bouwmeester, H.J.M.; Verweij, H.; Burggraaf, A.J.

    1997-01-01

    Oxygen permeation measurements were performed on erbia-stabilized bismuth oxide-silver (40 v/o) composite membranes in the range of thickness of 1.60–0.23 mm and temperature of 850–650 °C. Air was fed at one side of the membranes while permeated oxygen on the other side was swept away with helium. A

  1. Biosynthesis of silver and zinc oxide nanoparticles using Pichia fermentans JA2 and their antimicrobial property

    Science.gov (United States)

    Chauhan, Ritika; Reddy, Arpita; Abraham, Jayanthi

    2015-01-01

    The development of eco-friendly alternative to chemical synthesis of metal nanoparticles is of great challenge among researchers. The present study aimed to investigate the biological synthesis, characterization, antimicrobial study and synergistic effect of silver and zinc oxide nanoparticles against clinical pathogens using Pichia fermentans JA2. The extracellular biosynthesis of silver and zinc oxide nanoparticles was investigated using Pichia fermentans JA2 isolated from spoiled fruit pulp bought in Vellore local market. The crystalline and stable metallic nanoparticles were characterized evolving several analytical techniques including UV-visible spectrophotometer, X-ray diffraction pattern analysis and FE-scanning electron microscope with EDX-analysis. The biosynthesized metallic nanoparticles were tested for their antimicrobial property against medically important Gram positive, Gram negative and fungal pathogenic microorganisms. Furthermore, the biosynthesized nanoparticles were also evaluated for their increased antimicrobial activities with various commercially available antibiotics against clinical pathogens. The biosynthesized silver nanoparticles inhibited most of the Gram negative clinical pathogens, whereas zinc oxide nanoparticles were able to inhibit only Pseudomonas aeruginosa. The combined effect of standard antibiotic disc and biosynthesized metallic nanoparticles enhanced the inhibitory effect against clinical pathogens. The biological synthesis of silver and zinc oxide nanoparticles is a novel and cost-effective approach over harmful chemical synthesis techniques. The metallic nanoparticles synthesized using Pichia fermentans JA2 possess potent inhibitory effect that offers valuable contribution to pharmaceutical associations.

  2. Zinc oxide and silver nanoparticles influence the antioxidative status in a higher aquatic plant, Spirodela punctata

    CSIR Research Space (South Africa)

    Thwala, Melusi

    2012-09-01

    Full Text Available , and emphasize the importance of a comprehensive evaluation of the sublethal effects on various aquatic species. T35 Zinc oxide and silver nanoparticles influence the antioxidative status in a higher aquatic plant, Spirodela punctata. M Thwala 1,2, N Musee3...

  3. 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

  4. Graphene supported silver@silver chloride & ferroferric oxide hybrid, a magnetically separable photocatalyst with high performance under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Suting; Jiang, Wei, E-mail: superfine_jw@126.com; Han, Mei; Liu, Gongzong; Zhang, Na; Lu, Yue

    2015-08-30

    Graphical abstract: - Highlights: • The composites were synthesized via a facile and effective process. • Plenty of Fe{sub 3}O{sub 4} and Ag@AgCl nanoparticles are deposited on the reduced graphene oxide nanosheets. • The catalyst exhibited an enhanced photocatalytic performance and magnetic property. • The catalyst is stable under the visible light irradiation. - Abstract: A stable magnetic separable plasmonic photocatalyst was successfully fabricated by grafting silver@silver chloride (Ag@AgCl) and ferroferric oxide (Fe{sub 3}O{sub 4}) nanoparticles on graphene sheets. The composite exhibited high activity degrading methylene blue (MB) and rhodamine B (RB) under visible light irradiation: decomposition 97.4% of MB in 100 min and 97.9% of RB in 120 min. The enhanced photocatalytic activities can be attributed to synergistic effect between Ag@AgCl and graphene: the effective charge transfer from Ag@AgCl to graphene thus promotes the separation of electron–hole pairs. Moreover, the excellent magnetic property gives a more convenient way to recycle the photocatalysts.

  5. The preparation of highly active antimicrobial silver nanoparticles by an organometallic approach

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Eduardo J; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M; Monge, Miguel [Departamento de Quimica Grupo de SIntesis Quimica de La Rioja, UA-CSIC, Universidad de La Rioja, Complejo CientIfico-Tecnologico, E-26004 Logrono (Spain); Laguna, Antonio [Departamento de Quimica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, E-50009 Zaragoza (Spain); Torres, Carmen [Departamento de Agricultura y Alimentacion, Universidad de La Rioja, Complejo Cientifico-Tecnologico, E-26004 Logrono (Spain)], E-mail: eduardo.fernandez@unirioja.es

    2008-05-07

    Silver nanoparticles of small size with a high surface to volume ratio have been prepared using an organometallic approach. For this, the complex NBu{sub 4}[Ag(C{sub 6}F{sub 5}){sub 2}] has been treated with AgClO{sub 4} in a 1:1 molar ratio, giving rise to the nanoparticle precursor [Ag(C{sub 6}F{sub 5})] in solution. Addition of one equivalent of hexadecylamine (HDA) and 5 h of reflux in toluene leads to a deep yellow solution containing monodisperse silver nanoparticles (Ag NPs) of ca. 10 nm. This approach leads to nanoparticles with almost uncontaminated surfaces which make them very reactive. Antimicrobial studies show that these nanoparticles are very active as antimicrobial agents. Very low concentrations between 12 and 25 {mu}g ml{sup -1} of Ag NPs are enough to produce bacteriostatic and bactericidal effectiveness.

  6. Surface Enhanced Raman Scattering (SERS Studies of Gold and Silver Nanoparticles Prepared by Laser Ablation

    Directory of Open Access Journals (Sweden)

    Samuel P. Hernandez-Rivera

    2013-03-01

    Full Text Available Gold and silver nanoparticles (NPs were prepared in water, acetonitrile and isopropanol by laser ablation methodologies. The average characteristic (longer size of the NPs obtained ranged from 3 to 70 nm. 4-Aminobenzebethiol (4-ABT was chosen as the surface enhanced Raman scattering (SERS probe molecule to determine the optimum irradiation time and the pH of aqueous synthesis of the laser ablation-based synthesis of metallic NPs. The synthesized NPs were used to evaluate their capacity as substrates for developing more analytical applications based on SERS measurements. A highly energetic material, TNT, was used as the target compound in the SERS experiments. The Raman spectra were measured with a Raman microspectrometer. The results demonstrate that gold and silver NP substrates fabricated by the methods developed show promising results for SERS-based studies and could lead to the development of micro sensors.

  7. Bactericidal activity and silver release of porous ceramic candle filter prepared by sintering silica with silver nanoparticles/zeolite for water disinfection

    Science.gov (United States)

    Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Thanh Nguyen, Duc; Hien Nguyen, Quoc

    2014-09-01

    Porous ceramic candle filters (PCCF) were prepared by sintering silica from rice husk with silver nanoparticles (AgNPs)/zeolite A at about 1050 °C to create bactericidal PCCF/AgNPs for water disinfection. The silver content in PCCF/AgNPs was of 300-350 mg kg-1 determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and the average pore size of PCCF/AgNPs was of 50-70 Å measured by Brunauer-Emmett-Teller (BET) method. The bactericidal activity and silver release of PCCF/AgNPs have been investigated by flow test with water flow rate of 5 L h-1 and initial inoculation of E. coli in inlet water of 106 CFU/100 mL. The volume of filtrated water was collected up to 500 L. Results showed that the contamination of E. coli in filtrated water was water was low, far under the WHO guideline of 100 μg L-1 at maximum for drinking water. Based on the content of silver in PCCF/AgNPs and in filtrated water, it was estimated that one PCCF/AgNPs could be used to filtrate of ˜100 m3 water. Thus, as-prepared PCCF/AgNPs releases low content of silver into water and shows effectively bactericidal activity that is promising to apply as point-of-use water treatment technology for drinking water disinfection.

  8. Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Salvioni L

    2017-03-01

    Full Text Available Lucia Salvioni,1 Elisabetta Galbiati,1 Veronica Collico,1 Giulia Alessio,1 Svetlana Avvakumova,1 Fabio Corsi,2,3 Paolo Tortora,1 Davide Prosperi,1 Miriam Colombo1 1Nanobiolab, Department of Biotechnology and Bioscience, University of Milano-Bicocca, 2Biological and Clinical Science Department, University of Milan, Milano, 3Surgery Department, Breast Unit, IRCCS S Maugeri Foundation, Pavia, Italy Background: The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases.Methods: Water-soluble, negatively charged silver nanoparticles (AgNPs were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet–visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs.Results: In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells.Conclusion: We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared

  9. Preparation Calcium Oxide From Chicken Eggshells

    Directory of Open Access Journals (Sweden)

    Risfidian Mohadi

    2016-08-01

    Full Text Available The preparation of metal oxide CaO from chicken eggshell has been carried out by decomposition at various temperatures 600, 700, 800, 900, and 1000oC. The metal oxide CaO was characterized using XRD. Furthermore, The optimum temperature for preparation of CaO was determined based on the XRD pattern, then the characterization of CaO was extended using FT-IR spectrophotometer and BET analysis. The results show that the optimum temperature for preparation of CaO from chicken eggshell is 900oC with peak of 2Ө at 32.3o, 37.4o, 53.9o, 64.2o and 67.5o, respectively. The FT-IR spectrums show the unique vibration for Ca-O at 393 cm-1. The BET analysis show that CaO has surface area 68 m2/g with pore volume 1.65 cm3/g and pore size 6.6 nm which can be classified as mesoporous.

  10. Studies on the electrical properties of reactive DC magnetron-sputtered indium-doped silver oxide thin films: The role of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Subrahmanyam, A. [Semiconductor Physics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)]. E-mail: manu@iitm.ac.in; Barik, Ullash Kumar [Semiconductor Physics Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2007-03-15

    Indium ({approx}10 at.%)-doped silver oxide (AIO) thin films have been prepared on glass substrates at room temperature (300 K) by reactive DC magnetron sputtering technique using an alloy target made of pure (99.99%) silver and indium (90:10 at.%) metals. The oxygen flow rates have been varied in the range 0.00-3.44 sccm during sputtering. The X-ray diffraction data on these indium-doped silver oxide films show polycrystalline nature. With increasing oxygen flow rate, the carrier concentration, the Hall mobility and the electron mean free path decrease. These films show a very low positive temperature coefficient of resistivity {approx}3.40x10{sup -8} ohm-cm/K. The work function values for these films (measured by Kelvin probe technique) are in the range 4.81-5.07 eV. The high electrical resistivity indicate that the films are in the island state (size effects). Calculations of the partial ionic charge (by Sanderson's theory) show that indium doping in silver oxide thin films enhance the ionicity.

  11. Preparation of silver material used for detection of biocomplexes by surface-enhanced Raman scattering

    Science.gov (United States)

    Nowak, M.; Binczyk, M.; Skrobanska, M.; Marciniak, L.; Runka, T.; Jastrzab, R.

    2016-08-01

    Silver dendrites were obtained on Cu plate by a classic galvanic displacement process. The process of preparing Ag particles was performed at different immersion times in AgNO3 solution, and the best process parameters were selected according to the enhancement effect of the Raman spectra of Rhodamine 6G. Ag-Cu substrates were chosen for a Surface-enhanced Raman scattering (SERS) study of biocomplexes because their preparation is cost effective and simple, and the relative homogeneous signal enhancement on the prepared silver SERS-active substrate was obtained. The rapid process of surface preparation was applied to identify the mode of coordination. Biocomplexes of Co and Ni ions with adenosine triphosphate form in neutral pH were immersed on the Ag dendrites, and SERS spectra of these compounds were collected. This research work was carried out in order to determine different types of coordination in the same pH conditions and relatively low concentration using SERS which is an emerging and promising technique for the determination of coordination types in biocomplexes.

  12. An improved method of preparation of nanoparticular metal oxide catalysts

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns an improved method of preparation of nanoparticular vanadium oxide/anatase titania catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular vanadium oxide/anatase titania catalyst precursors comprising...... combustible crystallization seeds upon which the catalyst metal oxide is coprecipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step.......The present invention concerns an improved method of preparation of nanoparticular vanadium oxide/anatase titania catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular vanadium oxide/anatase titania catalyst precursors comprising...

  13. Potential exposure to silver nanoparticles during spraying preparation for air-conditioning cleaning

    Directory of Open Access Journals (Sweden)

    Elżbieta Jankowska

    2013-02-01

    Full Text Available Background: Unique properties of engineered nanomaterials (ENMs and products made of them have contributed to a rapid progress in the production and application of ENMs in different branches of industry and in factories with different production scale. Bearing in mind that nano-objects (nanoplates, nanofibres, nanoparticles, emitted during ENM production and application, can cause many diseases, even those not yet recognized, extensive studies have been carried all over the world to assess the extent of exposure to nano-objects at workstations and related health effects in workers employed in ENM manufacture and application processes. Material and Methods: The study of potential exposure to silver nanoparticles contained in the preparation for airconditioning cleaning (Nano Silver from Amtra Sp. z o.o. involved the determination of concentrations and size distribution of particles, using different devices, allowing for tracing changes in a wide range of dimensions, from nano-size (10 nm to micrometrsize (10 µm, of the particles which are usually inhaled by humans. Results and Conclusions: The results of the study shows that even during a short-term spraying of Nano Silver preparation (for 10 s at the distance of 52 cm from the place of preparation spraying - particles of 10 nm-10 µm can be emitted into in the air. During a three-fold preparation spraying in similar conditions differences in concentration increase were observed, but in each case the particles remained in the air for a relatively long time. Med Pr 2013;64(1:57–67

  14. Analysis on superhydrophobic silver decorated copper Oxide nanostructured thin films for SERS studies.

    Science.gov (United States)

    Jayram, Naidu Dhanpal; Aishwarya, D; Sonia, S; Mangalaraj, D; Kumar, P Suresh; Rao, G Mohan

    2016-09-01

    The present work demonstrates the superhydrophobic and Surface Enhanced Raman Spectroscopy (SERS) active substrate performance of silver coated copper oxide (Ag@CuO) nanostructured thin films prepared by the SILAR process. Super hydrophobic substrates that combine super hydrophobic condensation effect and high enhancement ability of Ag@CuO nanoflowers are investigated for SERS studies. The possible growth mechanism for the formation of nanoflower arrays from nanospindles has been discussed. Morphology and crystallinity of the Ag@CuO thin films are confirmed using FESEM and XRD. The results obtained in the present study indicate that the as-deposited hydrophobic nanospindles structure converts to super hydrophobic nanoflower arrays on annealing at 200°C. The Ag@CuO super hydrophobic nanoflowers thin film based SERS substrates show highly enhanced Raman spectra with an EF value of 2.0×10(7) for (Rhodamine 6G) R6G, allowing a detection limit from a 10(-10)molL(-1) solution. The present study may provide a new perception in fabricating efficient super hydrophobic substrates for SERS, suggesting that the fabricated substrates are promising candidates for trace analysis of R6G dye and are expected to be widely used as highly sensitive SERS active substrates for various toxic dyes in the future.

  15. Electrochemical immunosensor for ethinylestradiol using diazonium salt grafting onto silver nanoparticles-silica-graphene oxide hybrids.

    Science.gov (United States)

    Cincotto, Fernando H; Martínez-García, Gonzalo; Yáñez-Sedeño, Paloma; Canevari, Thiago C; Machado, S A S; Pingarrón, José M

    2016-01-15

    This work describes the preparation of an electrochemical immunosensor for ethinylestradiol (EE2) based on grafting of diazonium salt of 4-aminobenzoic acid onto a glassy carbon electrode modified with silver nanoparticles/SiO2/graphene oxide hybrid followed by covalent binding of anti-ethinylestradiol (anti-EE2) to activated carboxyl groups. A competitive immunoassay was developed for the determination of the hormone using peroxidase-labeled ethinylestradiol (HRP-EE2) and measurement of the amperometric response at -200mV in the presence of hydroquinone (HQ) as redox mediator. The calibration curve for EE2 exhibited a linear range between 0.1 and 50ng/mL (r(2)=0.996), with a detection limit of 65pg/mL. Interference studies with other hormones related with EE2 revealed the practical specificity of the developed method for the analyte. A good reproducibility, with RSD=4.5% (n=10) was also observed. The operating stability of a single bioelectrode modified with anti-EE2 was maintained at least for 15 days when it was stored at 4°C under humid conditions between measurements. The developed immunosensor was applied to the analysis of spiked urine with good results.

  16. Silver-catalyzed arylation of (hetero)arenes by oxidative decarboxylation of aromatic carboxylic acids.

    Science.gov (United States)

    Kan, Jian; Huang, Shijun; Lin, Jin; Zhang, Min; Su, Weiping

    2015-02-09

    A long-standing challenge in Minisci reactions is achieving the arylation of heteroarenes by oxidative decarboxylation of aromatic carboxylic acids. To address this challenge, the silver-catalyzed intermolecular Minisci reaction of aromatic carboxylic acids was developed. With an inexpensive silver salt as a catalyst, this new reaction enables a variety of aromatic carboxylic acids to undergo decarboxylative coupling with electron-deficient arenes or heteroarenes regardless of the position of the substituents on the aromatic carboxylic acid, thus eliminating the need for ortho-substituted aromatic carboxylic acids, which were a limitation of previously reported methods.

  17. Laser-Induced Silver Nanoparticles on Titanium Oxide for Photocatalytic Degradation of Methylene Blue

    OpenAIRE

    Jyun-Jen Chen; Thou-Jen Whang; Mu-Tao Hsieh; Hsien-Yu Huang

    2009-01-01

    Silver nanoparticles doped on titanium oxide (TiO2) were produced by laser-liquid interaction of silver nitrate (AgNO3) in isopropanol. Characteristics of Ag/TiO2 (Ag doped TiO2) nanoparticles produced by the methods presented in this article were investigated by XRD, TEM, SEM, EDX, and UV-Vis. From the UV-Vis measurements, the absorption of visible light of the Ag/TiO2 photocatalysts was improved (additional absorption at longer wavelength in visible light region) obviously. The photocatalyt...

  18. Study on Preparation and Characterization of Silver Nanoparticle Colloid Solution%纳米银的制备与表征

    Institute of Scientific and Technical Information of China (English)

    马守栋; 李明春; 叶勇; 曹恩惠; 赵丽艳

    2011-01-01

    目的 制备粒径小、性质稳定、抗菌活性强的纳米银.方法 化学合成法制备纳米银,以超滤法将反应体系中的杂质除去得高纯度的纳米银.以紫外分光光度计、透射电子显微镜、激光纳米粒度测定仪对其进行理化表征.结果 制备出的纳米银平均粒径为18.29nm,分布窄;表面带负电荷,平均表面Zeta电位为-36.5 mV;性质稳定,抗菌活性强.结论 实验结果表明,本方法可以制备出优良的纳米银.%OBJECTIVE To prepare silver nanoparticles with small particle diameter, good stability and high antimicrobial activity. METHODS The silver nanoparticles were prepared by chemical synthesis using silver nitrate,maltose and ammonia water as the reactants. The main physical properties of silver nanoparticles were characterized by UV spectrophotometer, transmission electron microscope and laser nanoparticle detecter. The bacteriostasis activity was determined by tube dilution method,using silver sulphadia-zine as the positive control. RESULTS The mean diameter of the silver nanoparticles was 18. 29 nm,and the Zeta potential was -36. 5 mV. The silver nanoparticles were steady and had higher bacteriostatic activity than silver sulphadiazine. CONCLUSION Hie chemical synthesis method can be used to prepare desired silver nanoparticles.

  19. Preparation and Characterization of Copper/Silver Alloy Nanoparticles%铜/银合金纳米粒子的制备及表征

    Institute of Scientific and Technical Information of China (English)

    张念椿; 胡建强

    2014-01-01

    The preparation method of copper/silver alloy nanoparticles was studied. The small particle size of nano copper was prepared by using the environmentally friendly ascorbic acid as a reducing agent. But this nano copper had poor stability, and is easy to be oxidized. In order to improve its stability, a small amount of Ag+was added during the preparation of nano copper. The silver layer was covered on the nano copper surface by reduction reaction. The copper/silver alloy nanocrystalline possesses good stability and nanoparticles effect. The copper/silver alloy nanoparticles are expected to having potential application in production of printed circuits. The preparation method has shorter product process than the conventional PCB production, thus it can save resources and reduce the environmental pollution.%研究了铜/银合金纳米粒子的制备方法,用抗坏血酸做还原剂,制备了粒径小的纳米铜粉。由于纳米铜粉的稳定性差,易氧化,为了提高其稳定性,在制备的纳米铜粉中加了少量的Ag+,在纳米铜粉表面还原制备出银纳米层覆盖于在铜上。所制备的纳米铜/银合金纳米粒子稳定性好,具有纳米粒子的效应,有望应用于印制电路的制造。该制备方法可以减少传统印制电路板制作方法的工序,节约资源,且减少对环境的污染。

  20. Oxidative Pressure Leaching of Silver from Flotation Concentrates with Ammonium Thiocyanate Solution

    Science.gov (United States)

    Yang, Sheng-Hai; Yang, Jian-Guang; Liu, Wei; Chen, Geng-Tao; Tang, Mo-Tang; Qiu, Guan-Zhou

    2010-02-01

    The thermodynamics and technologies of the selective pressure leaching of silver from flotation concentrates were investigated in an ammonium thiocyanate medium. Thermodynamic analyses, which include silver solubility in NH4SCN solution and Eh-pH diagrams of the Me-MeS-NH4SCN-H2O system at 25 °C, were discussed. The effects of several factors, such as temperature, leaching time, oxidant, pH value, flotation concentrates concentration, surfactant concentration, and so on, on the extraction percentages of silver and zinc were investigated. The following optimal leaching conditions were obtained: NH4SCN concentration 1.5 M, lignin concentration 0.5 g/L, Fe3+ concentration 2 g/L, flotation concentrates addition 200 g/L, and oxygen pressure 1.2 MPa at 130 °C for 3 hours. Under these optimum conditions, the average extraction percentage of silver exceeded 94 pct, whereas the average extraction percentage of zinc was less than 3 pct. Only 7 pct of ammonium thiocyanate was consumed after 4 cycles, which indicated that ammonium thiocyanate hardly was oxidized under these oxidative pressure leaching conditions.

  1. Bioaccumulation and oxidative stress parameters in silver catfish (Rhamdia quelen) exposed to different thorium concentrations.

    Science.gov (United States)

    Kochhann, Daiani; Pavanato, Maria A; Llesuy, Susana F; Correa, Lizelia M; Konzen Riffel, Ana P; Loro, Vania L; Mesko, Márcia F; Flores, Erico M M; Dressler, Valderi L; Baldisserotto, Bernardo

    2009-10-01

    The objective of this study was to evaluate the effect of chronic thorium (Th) exposure on bioaccumulation, metabolism (through biochemical parameters of the muscle) and oxidative parameters (lipidic peroxidation levels and antioxidant enzymes in the gills and in the hepatic and muscular tissues) of silver catfish (Rhamdia quelen). Silver catfish juveniles were exposed to different waterborne Th levels (in microg L(-1)): 0 (control), 25.3+/-3.2, 80.6+/-12.0, 242.4+/-35.6, and 747.2+/-59.1 for 30 d. The gills and skin were the organs that accumulated the highest Th levels. The increase in the waterborne Th concentration corresponded to a progressive increase in the Th levels in the gills and kidney. Chronic Th exposure causes alterations in the oxidative parameters of silver catfish gills, which are correlated with the Th accumulation in this organ. The levels of GST decreased in the gills of fish exposed to 747.2 microg L(-1) Th and SOD activity decreased in silver catfish exposed to 242.4 and 747.2 microg L(-1) Th. In addition, the increase in the LPO in the gills exposed to 242.4 and 747.2 microg L(-1) Th suggests that higher oxidative damage occurred in the gills. However, in the liver and muscle, these alterations occurred mainly in the lowest waterborne Th level. Metabolic intermediates in the muscle were altered by Th exposure, but no clear relationship was found.

  2. The influence of the capping agent on the oxidation of silver nanoparticles: nano-impacts versus stripping voltammetry.

    Science.gov (United States)

    Toh, Her Shuang; Jurkschat, Kerstin; Compton, Richard G

    2015-02-09

    The influence of capping agents on the oxidation of silver nanoparticles was studied by using the electrochemical techniques of anodic stripping voltammetry and anodic particle coulometry ("nano-impacts"). Five spherical silver nanoparticles each with a different capping agent (branched polyethylenimine (BPEI), citrate, lipoic acid, polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP)) were used to perform comparative experiments. In all cases, regardless of the capping agent, complete oxidation of the single nanoparticles was seen in anodic particle coulometry. The successful quantitative detection of the silver nanoparticle size displays the potential application of anodic particle coulometry for nanoparticle characterisation. In contrast, for anodic stripping voltammetry using nanoparticles drop casting, it was observed that the capping agent has a very significant effect on the extent of silver oxidation. All five samples gave a low oxidative charge corresponding to partial oxidation. It is concluded that the use of anodic stripping voltammetry to quantify nanoparticles is unreliable, and this is attributed to nanoparticle aggregation.

  3. Amino acid mediated synthesis of silver nanoparticles and preparation of antimicrobial agar/silver nanoparticles composite films.

    Science.gov (United States)

    Shankar, Shiv; Rhim, Jong-Whan

    2015-10-05

    Silver nanoparticles (AgNPs) were synthesized using amino acids (tyrosine and tryptophan) as reducing and capping agents, and they were incorporated into the agar to prepare antimicrobial composite films. The AgNPs solutions exhibited characteristic absorption peak at 420 nm that showed a red shift to ∼434 nm after forming composite with agar. XRD data demonstrated the crystalline structure of AgNPs with dominant (111) facet. Apparent surface color and transmittance of agar films were greatly influenced by the AgNPs. The incorporation of AgNPs into agar did not exhibit any change in chemical structure, thermal stability, moisture content, and water vapor permeability. The water contact angle, tensile strength, and modulus decreased slightly, but elongation at break increased after AgNPs incorporation. The agar/AgNPs nanocomposite films possessed strong antibacterial activity against Listeria monocytogenes and Escherichia coli. The agar/AgNPs film could be applied to the active food packaging by controlling the food-borne pathogens.

  4. Preparation of Silver- and Zinc-Doped Mullite-Based Ceramics Showing Anti-Bacterial Biofilm Properties

    Directory of Open Access Journals (Sweden)

    Suhair Saleh

    2011-03-01

    Full Text Available Zinc- and silver-doped mullite ceramic discs were prepared and tested as potentially resistant materials against bacterial adhesion and biofilm formation. Elemental analysis and X-ray diffraction studies showed that zinc ions were incorporated in the structural framework of the mullite, while silver ions remained outside the mullite crystal lattice, which allowed their slow (0.02 ppm/24 hours leaching into the surrounding aqueous environment. In agreement with this behavior, silver-doped mullite showed potent resistance against surface attachment of Pseudomonas aeruginosa, while on the other hand, zinc-doped mullite failed to stop bacterial attachment.

  5. In situ growth of silver nanoparticles on TEMPO-oxidized jute fibers by microwave heating.

    Science.gov (United States)

    Cao, Xinwang; Ding, Bin; Yu, Jianyong; Al-Deyab, Salem S

    2013-01-30

    Cellulose fibers deposited with metallic nanoparticles as one kind of renewable, biocompatible and antimicrobial nanomaterials evoke much interest because of their versatility in various applications. Herein, for the first time, a facile, simple and rapid method was developed to fabricate TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) selectively oxidized jute fibers in situ deposited with silver nanoparticles in the absence of reducing reagents. The average size of silver nanoparticles deposited on the fibers is 50.0 ± 2.0 nm by microwave heating for 5 min and 90.0 ± 4.7 nm for 10 min heating sample, respectively. The versatile jute-silver nanoparticles nanocomposites with superior thermal stability and high crystallinity would be particularly useful for applications in the public health care and biomedical fields. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Preparation and characterization of silver nanoparticles in natural polymers using laser ablation

    Indian Academy of Sciences (India)

    Reza Zamiri; B Z Azmi; Hossein Abbastabar Ahangar; Golnoosh Zamiri; M Shahril Husin; Z A Wahab

    2012-10-01

    In this paper we have done a comparative study on efficiency of natural polymers for stabilizing silver nanoparticles (Ag-NPs) prepared by laser ablation technique. The selected polymers are starch (St), gelatin (Gt) and chitosan (Ct). The fabrication process was carried out through ablation of a pure Ag plate by nanosecond Q-switched Nd–Yg pulsed laser ( = 532 nm, 360 mJ/pulse). The stability of the samples was studied by measuring UV-visible absorption spectra of the samples one month after preparation. The result showed that the formation efficiency of NPs in St were highest and also the prepared NPs in St solution were more stable than other polymers during one month storage.

  7. Graphene oxide decorated with silver nanoparticles as a coating on a stainless-steel fiber for solid-phase microextraction.

    Science.gov (United States)

    Wang, Licheng; Hou, Xiudan; Li, Jubai; Liu, Shujuan; Guo, Yong

    2015-07-01

    A novel graphene oxide decorated with silver nanoparticles coating on a stainless-steel fiber for solid-phase microextraction was prepared. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the coating surface and showed that silver nanoparticles were dispersed on the wrinkled graphene oxide surface. Coupled to gas chromatography with flame ionization detection, the extraction abilities of the fiber for polycyclic aromatic hydrocarbons were examined in the headspace solid-phase microextraction mode. The extraction parameters including adsorption time, adsorption temperature, salt concentration, desorption time and desorption temperature were investigated. Under the optimized condition, wide linearity with low limits of detection from 2 to 10 ng/L was obtained. The relative standard deviations for single-fiber repeatability and fiber-to-fiber reproducibility were less than 10.6 and 17.5%, respectively. The enrichment factors were from 1712.5 to 4503.7, showing the fiber has good extraction abilities. Moreover, the fiber exhibited a good stability and could be reused for more than 120 times. The established method was also applied for determination of polycyclic aromatic hydrocarbons in two real water samples and the recoveries of analytes ranged from 84.4-116.3% with relative standard deviations less than 16.2%.

  8. Study on the Preparation and Characteristics of Cellulose/Silver Iodide Nanocomposite Film.

    Science.gov (United States)

    Lee, Yang Hun; Han, Sung Soo; Kang, Young Ah; Shin, Eun Joo

    2016-06-01

    In this study, the structure and properties of an organic-inorganic composite material prepared from cellulose doped with fine particles of silver iodide (AgI) were examined. The preparation of the composite involved the complexation of cellulose with polyiodide ions, such as I- and 13-, by immersion in iodine/potassium iodide (I2/KI: 0.2, 0.4, 0.6, 0.8, 1.0 M) or potassium iodide (KI: 0.6, 1.2, 1.8, 2.4, 3.0 M) aqueous solutions followed by reaction in a silver nitrate (AgNO3:1.0 M) aqueous solution. These procedures resulted in the in situ formation of fine β-AgI particles within the cellulose matrix. The characteristics and conductivities of prepared cellulose/silver iodide (AgI) nanocomposite films with different I2/KI and KI concentrations were investigated. AgI particle formation and aggregation increased on increasing I2/KI and KI concentrations as determined by SEM. X-ray results showed that KI could penetrate the cellulose crystal region and form AgI particles. The electrical conductivities of nanocomposite films treated with KI were higher than that of I2/KI at < 1.0 M of I2/KI and 3 M of KI, although the weight gain by AgI formation was lower than that of I2/KI. This was also attributed to the formation of smaller AgI particles and crystal defects. Highest electrical conductivity (3.8 x 10(-7) Ω(-1) cm(-1)) was obtained from the cellulose films (1.25 x 10(-11) Ω(-1) cm(-1)) treated with the aqueous solutions of 1.0 M I2/KI and 1.0 M AgNO3.

  9. Preparation and antibacterial properties of hybrid-zirconia films with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Azocar, Ignacio, E-mail: manuel.azocar@usach.cl [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Vargas, Esteban [Facultad de Ingenieria, Departamento de Metalurgia, Universidad de Santiago de Chile, USACH (Chile); Duran, Nicole [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Arrieta, Abel [Departamento de Biologia, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH (Chile); Gonzalez, Evelyn [Departamento de Quimica de los Materiales, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH, Avenida Bernardo O' Higgins 3363, Casilla 40, Correo 33, Santiago (Chile); Facultad de Ingenieria, Departamento de Metalurgia, Universidad de Santiago de Chile, USACH (Chile); Departamento de Biologia, Facultad de Quimica y Biologia, Universidad de Santiago de Chile, USACH (Chile); Departamento de Quimica Farmacologica y Toxicologica, Facultad de Ciencias Quimicas, Universidad de Chile, Sergio Livingstone Polhammer 1007, Santiago (Chile); and others

    2012-11-15

    The antimicrobial effect of incorporating silver nanoparticles (AgNps) into zirconia matrix-polyether glycol was studied. AgNps of 4-6 nm in size were synthesized using the inverse micelles method, and different doses of metallic nanoparticles were incorporated into zirconia-polyether glycol mixtures during the ageing procedure. Atomic force microscopy (AFM) of the modified hybrid film showed a homogenous distribution of 20-80 nm diameter AgNps, indicating agglomeration of these structures during film modification; such agglomerations were greater when increasing the dosage of the colloidal system. The AgNps-hybrid films showed higher antimicrobial activity against Gram-positive bacteria than for Gram-negative bacteria. Hybrid films prepared with dioctyl sodium sulfosuccinate (AOT) stabilized AgNps presented enhanced antibacterial activity compared to that obtained through the addition of a high AgNO{sub 3} concentration (0.3 wt%). -- Graphical abstract: Atomic Force Micrographs, top and cross section view, showing silver nanoparticles embedded in a zirconia-polyether glycol hybrid film. Highlights: Black-Right-Pointing-Pointer Antibacterial activity of films (zirconia-polyether glycol) modified with silver nanoparticles. Black-Right-Pointing-Pointer Biofilm formation is prevented. Black-Right-Pointing-Pointer High sensibility against gram positive bacteria.

  10. Preparation and rapid analysis of antibacterial silver, copper and zinc doped sol-gel surfaces.

    Science.gov (United States)

    Jaiswal, Swarna; McHale, Patrick; Duffy, Brendan

    2012-06-01

    The colonisation of clinical and industrial surfaces with microorganisms, including antibiotic-resistant strains, has promoted increased research into the development of effective antibacterial and antifouling coatings. This study describes the preparation of metal nitrate (Ag, Cu, Zn) doped methyltriethoxysilane (MTEOS) coatings and the rapid assessment of their antibacterial activity using polyproylene microtitre plates. Microtitre plate wells were coated with different volumes of liquid sol-gel and cured under various conditions. Curing parameters were analysed by thermogravimetric analysis (TGA) and visual examination. The optimum curing conditions were determined to be 50-70°C using a volume of 200 μl. The coated wells were challenged with Gram-positive and Gram-negative bacterial cultures, including biofilm-forming and antibiotic-resistant strains. The antibacterial activities of the metal doped sol-gel, at equivalent concentrations, were found to have the following order: silver>zinc>copper. The order is due to several factors, including the increased presence of silver nanoparticles at the sol-gel coating surface, as determined by X-ray photoelectron spectroscopy, leading to higher elution rates as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The use of microtitre plates enabled a variety of sol-gel coatings to be screened for their antibacterial activity against a wide range of bacteria in a relatively short time. The broad-spectrum antibacterial activity of the silver doped sol-gel showed its potential for use as a coating for biomaterials.

  11. PREPARATION AND THEIR ANTIBACTERIAL ACTIVITY OF ACTIVATED CARBON FIBER CONTAINING SILVER

    Institute of Scientific and Technical Information of China (English)

    CHENShuixia; LUOYing; 等

    2000-01-01

    Several kinds of activated carbon fiber(ACF),Granule Activated carbon(AC) containing silver ion or fine silver particle(Ag-ACF/AC) have been prepared by soaking ACF or AC in the salt solution of silver.Ag,AgCl and AgI compounds have been loaded onto the fibers:The stucture of the fibers was measured by scanning electron microscopy(SEM) and power X-ray diffraction(XRD),THe Ag content in the fiber was obtained by an Atomic absorption spectroscopy(AAS),The Ag+ content in water after the antibacterial test was measured by an Inductively Coupled plasma(ICP) emission spectroscopy.Antibacterial test was carried out against Escherichia coli(E.coli) and Staphylococcus aureus(S.aureus).The results show that Ag-ACF/AC have strong antibacterial activity against E.Coli and S.aureus.After dealt with ACF/AC loading Ag,AgCl,AgI,no E.coli and S.aureus alive in solution can be detected.The analysis of Agcontent in water after antibacterial test showed that the content of Ag meet the quality requirement of the National Potable Water Standrd,It is indicated that ACF/AC-Ag in this experiment would be a safe antibacterial agent.

  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. Preparation and Application of Chitosan Membranes to Filter Silver from X-ray Film Processing Wastes

    Science.gov (United States)

    Nyoman Rupiasih, N.; Rustam Purnomo, Rendra; Sumadiyasa, Made

    2016-04-01

    Chitosan is a natural polysaccharide biopolymer which has been widely used in different processes and applications. Chitosan based membranes have been used in reverse osmosis, gas separation, dialysis and pervaporation. The object of this research was investigating the possibility of chitosan membrane used as a filter for removing silver (Ag) from X-ray film processing wastes. Several of chitosan membranes such as M1, M2, M3 and M4 have been prepared for the purpose and filtration was done using dead-end filtration method. The filtration experiments were performed on a flat sheet membrane using pure water and X-ray film processing wastes as feeds. The analysis of silver concentration has been done by atomic absorption spectrometers (AAS). The results show that chitosan membrane M2 gave the highest filtration coefficient (Rcoeff ) i.e. 99.9%, with the pure water flux (PWF) and product flux (PF) are 2972.56 L/m2h and 1761.18 L/m2h respectively. The rejection coefficient of the membranes decreases with increasing the amount of chitosan, while the pure water flux and product flux are increased. The filtration coefficients show that the chitosan membranes are able to filter silver waste from X-ray film processing wastes with performance dependent on their characteristic such as pores size. This suggests that, chitosan membrane can be used as one method that is safe and friendly environment for recovering silver from X-ray film processing waste to improve the quality of treated to an acceptable quality level.

  14. Electrochemistry of the Zinc-Silver Oxide System. Part 2: Practical Measurements of Energy Conversion Using Commercial Miniature Cells.

    Science.gov (United States)

    Smith, Michael J.; Vincent, Colin A.

    1989-01-01

    Summarizes the quantitative relationships pertaining to the operation of electrochemical cells. Energy conversion efficiency, cycle efficiency, battery power, and energy/power density of two types of zinc-silver oxide cells are discussed. (YP)

  15. Electrochemical Oxidation of Silver and Copper in Aqueous Basic Media and in Fused Hydroxide Electrolytes

    Directory of Open Access Journals (Sweden)

    Tejada-Rosales, E. M.

    2004-04-01

    Full Text Available The anodic oxidations of copper and silver electrodes in basic media are reported. Experiments were conducted both in aqueous NaOH solutions and in a flux of molten NaOH/KOH eutectic. The oxidation processes were studied by means of cyclic voltammetry and chronoamperometries and the phases obtained were systematically characterized by x-ray diffraction. The ranges of stability of each phase in the different media studied are reported. In addition to known oxides of copper or silver, a new silver oxide was isolated.

    En este trabajo se describe la oxidación anódico de electrodos de plata y de cobre en medios básicos. Se han utilizado tanto medios acuosos como hidróxidos fundidos (eutéctico NaOH/KOH. Los procesos de oxidación se han estudiado mediante voltametría cíclica y cronoamperometría, y las fases resultantes han sido caracterizadas por difracción de Rayos X. Los rangos de estabilidad encontrados para cada uno dependen del medio utilizado. Además de óxidos conocidos de cobre y de plata, se ha aislado un nuevo óxido de plata.

  16. Preparation of an agar-silver nanoparticles (A-AgNp) film for increasing the shelf-life of fruits.

    Science.gov (United States)

    Gudadhe, Janhavi A; Yadav, Alka; Gade, Aniket; Marcato, Priscyla D; Durán, Nelson; Rai, Mahendra

    2014-12-01

    Preparation of protective coating possessing antimicrobial properties is present day need as they increase the shelf life of fruits and vegetables. In the present study, preparation of agar-silver nanoparticle film for increasing the shelf life of fruits is reported. Silver nanoparticles (Ag-NPs) biosynthesised using an extract of Ocimum sanctum leaves, were mixed with agar-agar to prepare an agar-silver nanoparticles (A-AgNp) film. This film was surface-coated over the fruits, Citrus aurantifolium (Thornless lime) and Pyrus malus (Apple), and evaluated for the determination of antimicrobial activity of A-AgNp films using disc diffusion method, weight loss and shelf life of fruits. This study demonstrates that these A-AgNp films possess antimicrobial activity and also increase the shelf life of fruits.

  17. Characterization of silver/polystyrene nanocomposites prepared by in situ bulk radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Vukoje, Ivana D., E-mail: ivanav@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Vodnik, Vesna V., E-mail: vodves@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com [Institute of Chemistry, Technology and Metallurgy (ICTM)-Center of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Džunuzović, Enis S., E-mail: edzunuzovic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Marinović-Cincović, Milena T., E-mail: milena@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Jeremić, Katarina, E-mail: kjeremic@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade (Serbia); Nedeljković, Jovan M., E-mail: jovned@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)

    2014-01-01

    Graphical abstract: - Highlights: • Synthesis and characterization of polystyrene nanocomposites based on Ag nanoparticles. • The glass transition temperature decreased in nanocomposites with respect to the pure polymer. • Resistance of the polymer to thermal degradation enhanced with Ag nanoparticles content. - Abstract: Nanocomposites (NCs) with different content of silver nanoparticles (Ag NPs) embeded in polystyrene (PS) matrix were prepared by in situ bulk radical polymerization. The nearly monodisperse Ag NPs protected with oleylamine were synthesized via organic solvo-thermal method and further used as a filler. The as-prepared spherical Ag NPs with diameter of 7.0 ± 1.5 nm were well dispersed in the PS matrix. The structural properties of the resulting Ag/PS NCs were characterized by transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectroscopy, while optical properties were characterized using optical absorption measurements. The gel permeation chromatography (GPC) measurements showed that the presence of Ag NPs stabilized with oleylamine has no influence on the molecular weight and polydispersity of the PS matrix. The influence of silver content on the thermal properties of Ag/PS NCs was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that resistance of PS to thermal degradation was improved upon incorporation of Ag NPs. The Ag/PS NCs have lower glass transition temperatures than neat PS because loosely packed oleylamine molecules at the interface caused the increase of free volume and chain segments mobility near the surface of Ag NPs.

  18. Preparation and characterization of silver nanoparticles immobilized on multi-walled carbon nanotubes by poly(dopamine) functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yi; Lu Yonglai; Zhang Liqun; Liu Li; Dai Yajie; Wang Wencai, E-mail: wangw@mail.buct.edu.cn [Beijing University of Chemical Technology, State Key Laboratory of Organic-Inorganic Composites and Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials (China)

    2012-06-15

    Multi-walled carbon nanotubes (MWNTs) functionalized with poly(dopamine) (PDA) were found to cause the immobilization of silver nanoparticles on the surface. The PDA functional layer not only improved the dispersion of MWNTs in aqueous solution, but also was used as a platform for subsequent silver nanoparticle immobilization. The surface morphology of the functionalized MWNTs was observed by high-resolution transmission electron microscopy. The results showed that PDA layers with controlled thickness on the nanometer scale were formed on MWNT surfaces by in situ spontaneous oxidative polymerization of dopamine, and that high-density of homogeneously dispersed spherical silver nanoparticles with sizes of 3-4 nm were immobilized on their outer surface. The space between spherical silver nanoparticles is less than 10 nm. Both X-ray photoelectron spectroscopy and X-ray diffraction results showed that the Ag nanoparticles on the surface of hybrids exist in the zero valent state.

  19. Preparation and characterization of silver nanoparticles immobilized on multi-walled carbon nanotubes by poly(dopamine) functionalization

    Science.gov (United States)

    Jiang, Yi; Lu, Yonglai; Zhang, Liqun; Liu, Li; Dai, Yajie; Wang, Wencai

    2012-06-01

    Multi-walled carbon nanotubes (MWNTs) functionalized with poly(dopamine) (PDA) were found to cause the immobilization of silver nanoparticles on the surface. The PDA functional layer not only improved the dispersion of MWNTs in aqueous solution, but also was used as a platform for subsequent silver nanoparticle immobilization. The surface morphology of the functionalized MWNTs was observed by high-resolution transmission electron microscopy. The results showed that PDA layers with controlled thickness on the nanometer scale were formed on MWNT surfaces by in situ spontaneous oxidative polymerization of dopamine, and that high-density of homogeneously dispersed spherical silver nanoparticles with sizes of 3-4 nm were immobilized on their outer surface. The space between spherical silver nanoparticles is less than 10 nm. Both X-ray photoelectron spectroscopy and X-ray diffraction results showed that the Ag nanoparticles on the surface of hybrids exist in the zero valent state.

  20. Preparation of mono-dispersed silver nanoparticles assisted by chitosan-g-poly(ε-caprolactone) micelles and their antimicrobial application

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Chunhua [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Huan [State Key Laboratory of Bioreactor Engineering, New World Biotechnology Institute, East China University of Science and Technology, Shanghai 200237 (China); Lang, Meidong, E-mail: mdlang@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2014-05-01

    Graphical abstract: - Highlights: • Chemical modification of chitosan were conducted after phthaloyl protection of amino groups. • Silver nanoparticles were prepared in the presence of chitosan-based copolymer micelles. • The optimal time scale and weight ratios of silver to micelles were monitored by UV–vis spectrometer. - Abstract: Amphiphilic chitosan-graft-poly(ε-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by {sup 1}H NMR, FTIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV–vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coli and Staphylococcus aureus as model Gram-negative and positive bacteria.

  1. Preparation of Mixed Perovskite Oxides for Blue-Green Lasers

    Science.gov (United States)

    1984-02-01

    higher for oxide or fluoride . 𔃽. A high radiative lifetime and high fluorescent quantum yield for Ce or the rare earth are desirable. 3 + 4...for all of our single crystal -4- preparations are lanthanum oxide (La„0 ), aluminum oxide (Al^O^) , scandium oxide (Sc„0-.) , and cerium oxide (Ce...crystal material is highly important. Ideally, oxides should be grown in O2, fluorides in ?„, and so forth in order to prevent defects such as

  2. Green chemistry for the preparation of L-cysteine functionalized silver nanoflowers

    Science.gov (United States)

    Ma, Xinfu; Guo, Qingquan; Xie, Yu; Ma, Haixiang

    2016-05-01

    The preparation of size- and shape-controlled metallic nanostructures in an eco-friendly manner has been regarded as one of the key issues in nanoscience research today. In this paper, biosynthesis of silver nanoflowers (AgNFs) using L-cysteine as reducing and capping agent in alkaline solution via 70 °C water bath for 4 h has been demonstrated. The formation of L-cys-AgNPs was observed visually by color change of the samples. The prepared samples were characterized by UV-vis spectroscopy, Transmission electron microscopy (TEM) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). These results indicate that single-crystalline of AgNFs have been successfully synthesized.

  3. Preparation and Electrocatalytic Activity of Polyaniline-poly(propylene oxide)

    Institute of Scientific and Technical Information of China (English)

    Mei Chao LI; Chun An MA

    2005-01-01

    A novel copolymer of polyaniline-poly(propylene oxide) (PAN-PPO) was prepared by cyclic voltammetry (CV) and characterized by FTIR and SEM. It showed good electroactivity for methanol oxidation in H2SO4 solution.

  4. Antimicrobial, free radical scavenging activities and catalytic oxidation of benzyl alcohol by nano-silver synthesized from the leaf extract of Aristolochia indica L.: a promenade towards sustainability

    Science.gov (United States)

    Shanmugam, C.; Sivasubramanian, G.; Parthasarathi, Bera; Baskaran, K.; Balachander, R.; Parameswaran, V. R.

    2016-06-01

    Silver nanoparticles (Ag-NPs) were synthesized from aqueous silver nitrate through a simple route using the leaf extract of Aristolochia indica L. (LAIL) which acted as a reducing as well as capping agent. X-ray diffraction confirmed that the synthesized silver particles have a face centred cubic structure. EDS predicted the presence of elemental silver. The SEM images showed the synthesis of spherically mono-dispersed particles, with nano dimensions accounted by the TEM images. Infra-red spectrum adopted to the different organic functionalities present at the surface of the particles. TGA indicated an overall 11 % weight loss up to 1000 °C, suggesting desorption of biomolecules from the surface. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of metallic silver nanoparticles. The prepared material was utilized as catalyst in the oxidation of benzyl alcohol with molecular oxygen as the oxidant in methanol, under ambient conditions of temperature and pressure. Also Ag-NPs showed good to moderate anti-microbial activity employing the Agar disc diffusion method against various strains using Ciprofloxacin and Fluconazole as standard. Free radical scavenging activity of the nanoparticles were observed by modified 1,1-diphynyl-2-picrylhydrazyl, DPPH and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS in vitro assays. The work presented here demonstrates the adaptability of the synthesized Ag-NPs in participating as a disinfectant agent, free radical scavenger and an effective oxidation catalyst. The basic premise of attaining sustainability through the green synthesis of smart multifaceted materials has been consciously addressed.

  5. Poly(vinylpyrrolidone)/silver nanoparticles: preparation and characterization; Nanoparticulas de prata/poli(vinilpirrolidona): obtencao e caracterizacao

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, P.F.; Goncalves, M.C. [Instituto de Quimica - UNICAMP, Campinas, SP (Brazil)], e-mail: patandrade@iqm.unicamp.br

    2010-07-01

    In this work silver nanoparticles were prepared by chemical reduction method using PVP as dispersant agent. The formation of silver nanoparticles was investigated by UV-vis optical spectroscopy and X-ray diffraction. FT-IR spectroscopy confirmed the formation of Ag/PVP complex. The transmission electron microscopy images indicated that the concentration of Ag{sup +} precursor influenced the nanoparticles dispersion and size distribution significantly. The results indicated that dispersed nanoparticles with uniform size distribution can be prepared by this methodology to obtain polymeric nano composites. (author)

  6. Preparation and Characterization of Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Jianguo Song

    2014-01-01

    Full Text Available Graphene oxide (GO films with two-dimensional structure were successfully prepared via the modified Hummer method. It is proven that redox method is a promising way to synthesize GO films on a large scale. Comprehensive characterizations of the properties of GO films were conducted. TEM and DFM analyses showed that GO sheets prepared in this study had single and double lamellar layer structure and a thickness of 2~3 nm. X-ray diffraction (XRD was selected to measure the crystal structure of GO sheet. Fourier-transform infrared spectra analyzer (FT-IR was used to certify the presence of oxygen-containing functional groups in GO films. The tests of UV-VIS spectrometer and TGA analyzer indicated that GO sheet possessed excellent optical response and outstanding thermal stability. Elemental analyzer (EA and X-ray photoelectron spectroscope (XPS analyzed the components synthetic material. Simultaneously, chemical structure of GO sheet was described in this study. Discussion and references for further research on graphene are provided.

  7. Influence of different synthesis approach on doping behavior of silver nanoparticles onto the iron oxide-silica coreshell surfaces

    Science.gov (United States)

    Mahmed, Norsuria; Jiang, Hua; Heczko, Oleg; Söderberg, Outi; Hannula, Simo-Pekka

    2012-08-01

    Silver (Ag) nanoparticles with the crystallite size ranging from 13-24 nm were successfully doped onto the surface of iron oxide-silica coreshell particles. In the process, iron oxide particles having a size distribution within 8-19 nm were prepared by using a reverse co-precipitation method followed by the formation of iron oxide-core with silica shell (with 50-150 nm diameter of silica spheres) by using a modified Stöber method. The reduction of Ag ions was done at room temperature in a solution containing polyvinylpyrrolidone and ethanol by using mechanical and ultrasonic mixing. Four different synthesis approaches were used in doping of Ag nanoparticles. The phase, morphology, optical and magnetic properties of the synthesized powders were characterized by using X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope, UV-visible spectrometer (UV-Vis) and vibrating sample magnetometer. Spherical morphology of the Ag nanoparticles was found to deposit on the iron oxide-silica surfaces. The particle size distribution is depending on the synthesis approach used. The UV-Vis absorption peak at 404-410 nm of wavelength confirmed the existence of the Ag nanoparticles.

  8. Influence of different synthesis approach on doping behavior of silver nanoparticles onto the iron oxide-silica coreshell surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mahmed, Norsuria, E-mail: norsuria.mahmed@aalto.fi [Aalto University School of Chemical Technology, Department of Materials Science and Engineering (Finland); Jiang Hua [Aalto University School of Science, Department of Applied Physics (Finland); Heczko, Oleg [Academy of Sciences, Institute of Physics (Czech Republic); Soederberg, Outi; Hannula, Simo-Pekka [Aalto University School of Chemical Technology, Department of Materials Science and Engineering (Finland)

    2012-08-15

    Silver (Ag) nanoparticles with the crystallite size ranging from 13-24 nm were successfully doped onto the surface of iron oxide-silica coreshell particles. In the process, iron oxide particles having a size distribution within 8-19 nm were prepared by using a reverse co-precipitation method followed by the formation of iron oxide-core with silica shell (with 50-150 nm diameter of silica spheres) by using a modified Stoeber method. The reduction of Ag ions was done at room temperature in a solution containing polyvinylpyrrolidone and ethanol by using mechanical and ultrasonic mixing. Four different synthesis approaches were used in doping of Ag nanoparticles. The phase, morphology, optical and magnetic properties of the synthesized powders were characterized by using X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope, UV-visible spectrometer (UV-Vis) and vibrating sample magnetometer. Spherical morphology of the Ag nanoparticles was found to deposit on the iron oxide-silica surfaces. The particle size distribution is depending on the synthesis approach used. The UV-Vis absorption peak at 404-410 nm of wavelength confirmed the existence of the Ag nanoparticles.

  9. Aqueously Dispersed Silver Nanoparticle-Decorated Boron Nitride Nanosheets for Reusable, Thermal Oxidation-Resistant Surface Enhanced Raman Spectroscopy (SERS) Devices

    Science.gov (United States)

    Lin, Yi; Bunker, Christopher E.; Fernandos, K. A. Shiral; Connell, John W.

    2012-01-01

    The impurity-free aqueous dispersions of boron nitride nanosheets (BNNS) allowed the facile preparation of silver (Ag) nanoparticle-decorated BNNS by chemical reduction of an Ag salt with hydrazine in the presence of BNNS. The resultant Ag-BNNS nanohybrids remained dispersed in water, allowing convenient subsequent solution processing. By using substrate transfer techniques, Ag-BNNS nanohybrid thin film coatings on quartz substrates were prepared and evaluated as reusable surface enhanced Raman spectroscopy (SERS) sensors that were robust against repeated solvent washing. In addition, because of the unique thermal oxidation-resistant properties of the BNNS, the sensor devices may be readily recycled by short-duration high temperature air oxidation to remove residual analyte molecules in repeated runs. The limiting factor associated with the thermal oxidation recycling process was the Ostwald ripening effect of Ag nanostructures.

  10. Aqueously Dispersed Silver Nanoparticle-Decorated Boron Nitride Nanosheets for Reusable, Thermal Oxidation-Resistant Surface Enhanced Raman Spectroscopy (SERS) Devices

    Science.gov (United States)

    Lin, Yi; Bunker, Christopher E.; Fernandos, K. A. Shiral; Connell, John W.

    2012-01-01

    The impurity-free aqueous dispersions of boron nitride nanosheets (BNNS) allowed the facile preparation of silver (Ag) nanoparticle-decorated BNNS by chemical reduction of an Ag salt with hydrazine in the presence of BNNS. The resultant Ag-BNNS nanohybrids remained dispersed in water, allowing convenient subsequent solution processing. By using substrate transfer techniques, Ag-BNNS nanohybrid thin film coatings on quartz substrates were prepared and evaluated as reusable surface enhanced Raman spectroscopy (SERS) sensors that were robust against repeated solvent washing. In addition, because of the unique thermal oxidation-resistant properties of the BNNS, the sensor devices may be readily recycled by short-duration high temperature air oxidation to remove residual analyte molecules in repeated runs. The limiting factor associated with the thermal oxidation recycling process was the Ostwald ripening effect of Ag nanostructures.

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

    Science.gov (United States)

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

    1999-01-01

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

  12. Preparation, morphology, and antibacterial properties of polyacrylonitrile/montmorillonite/silver nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Jiunn-Jer, E-mail: jiunnjer1@hotmail.com [Department of Chemical Engineering, Army Academy, Taoyuan 32092, Taiwan, ROC (China); Ma, Te-Wei [Department of Chemical Engineering, Army Academy, Taoyuan 32092, Taiwan, ROC (China)

    2012-10-15

    Modified montmorillonite was intercalated with polyacrylonitrile (PAN) and then reacted with AgNO{sub 3}. Plate-like clay, with anionic charges and a large surface area, was the dispersant of the silver ions. Aqueous 3% NaBH{sub 4}-reduced Ag{sup +} (in situ) was utilized to prepare a series of polyacrylonitrile/montmorillonite/silver nanocomposites (PAN/o-MMT/Ag). The presence of silver particles with diameters of 50-100 nm was confirmed by X-ray and SEM observations. XRD diffraction peaks were obtained at 38.2 Degree-Sign , 44.4 Degree-Sign , 64.6 Degree-Sign and 77.6 Degree-Sign . AFM and TEM were used to evaluate the surface roughness of the nanocomposites and the dispersion of the silver nanoparticles (AgNPs) therein nanocomposites. Adding o-MMT made the nanocomposites rougher. The AgNPs were primarily located in the layered silicate nanofiller. In addition, the silver in nanocomposites was released to the water and dominant form of silver was nanoparticle in the water was verified by particle size analyzer and atomic absorption spectrometer. A higher F value (F = [AgNO{sub 3}/CH{sub 2}CH(CN)], which was the molar ratio of the salt to the PAN repeat unit) of the PAN/3 wt.% o-MMT/Ag nanocomposites corresponded to larger average particle size and more AgNPs in the 2 wt.% AgNPs solution. The bactericidal property of AgNPs solution, which was obtained by soaking PAN/o-MMT/Ag nanocomposite films in distilled water, was evaluated by the paper disc diffusion method. The results revealed that the AgNPs solution did not inhibit the growth of filamentous fungi but was quite effective against tiny bacteria of Gram (+) Staphylococcus aureus, Gram (-) Escherichia coli and Klebsiella pneumonia. In particular, using a 2 wt.% AgNP solution that was obtained by soaking PAN/3 wt.% o-MMT/Ag nanocomposite (F = 0.20) for 24 h in distilled water showed the most effectively inhibited growth of bacteria (16.4 mm). Its antibacterial activity still remained, yielding an inhibition zone

  13. Zinc oxide nanoparticles with incorporated silver: Structural, morphological, optical and vibrational properties

    Energy Technology Data Exchange (ETDEWEB)

    Mosquera, Edgar, E-mail: edemova@ing.uchile.cl [Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Tupper 2069, Santiago (Chile); Rojas-Michea, Carolina, E-mail: rojasmichea@gmail.com [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Tupper 2007, Santiago (Chile); Morel, Mauricio, E-mail: mmorel@ing.uchile.cl [Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Tupper 2069, Santiago (Chile); Gracia, Francisco, E-mail: Fgracia@ing.uchile.cl [Departamento de Ingeniería Química y Biotecnología, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Tupper 2007, Santiago (Chile); Fuenzalida, Víctor, E-mail: vfuenzal@ing.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Zárate, Ramón A., E-mail: rzarate@ucn.cl [Departamento de Física, Facultad de Ciencias, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile)

    2015-08-30

    Graphical abstract: Local vibrational modes of ZnO:Ag nanoparticles. - Highlights: • Formation of Ag biphases is observed when the Ag content increases. • The SPR property has been monitored in the UV–visible regime. • PL emission of ZnO:Ag nanoparticles are associated to structural defects. • A new local vibrational mode induced by Ag content were observed in the Raman spectra. - Abstract: Zinc oxide nanoparticles with different amounts of incorporated silver (ZnO:Ag; 0.6, 3, 6, and 9 at.% Ag) have been successfully synthesized by a simple sol gel method. The effect of Ag content on the properties of ZnO nanoparticles have been studied by various characterization techniques. The results from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (RS) suggest that elemental silver is present as a second phase. The UV–visible absorption and photoluminescence (PL) properties of the samples were also studied. PL data at room temperature reveals a strong blue emission. In addition, Raman spectroscopy results indicate a very strong A{sub 1}(LO) mode resulting from oxygen vacancies and zinc interstitials. A new local vibrational mode (LVM) at 480 cm{sup −1} induced by silver can also be observed in the Raman spectra, suggesting silver incorporation into the ZnO lattice compensating the Zn vacancies, which is consistent with the XRD results.

  14. Ink jet printable silver metallization with zinc oxide for front side metallization for micro crystalline silicon solar cells

    Science.gov (United States)

    Jurk, Robert; Fritsch, Marco; Eberstein, Markus; Schilm, Jochen; Uhlig, Florian; Waltinger, Andreas; Michaelis, Alexander

    2015-12-01

    Ink jet printable water based inks are prepared by a new silver nanoparticle synthesis and the addition of nanoscaled ZnO particles. For the formation of front side contacts the inks are ink jet printed on the front side of micro crystalline silicon solar cells, and contact the cell directly during the firing step by etching through the wafers’ anti-reflection coating (ARC). In terms of Ag dissolution and precipitation the mechanism of contact formation can be compared to commercial glass containing thick film pastes. This avoids additional processing steps, like laser ablation, which are usually necessary to open the ARC prior to ink jet printing. As a consequence process costs can be reduced. In order to optimize the ARC etching and contact formation during firing, zinc oxide nanoparticles are investigated as an ink additive. By utilization of in situ contact resistivity measurements the mechanism of contacting was explored. Our results show that silver inks containing ZnO particles realize a specific contact resistance below 10 mΩṡcm2. By using a multi-pass ink jet printing and plating process a front side metallization of commercial 6  ×  6 inch2 standard micro crystalline silicone solar cells with emitter resistance of 60 Ω/◽ was achieved and showed an efficiency of 15.7%.

  15. Reproducible Preparation of Silver Sols with Small Particle Size Using Borohydride Reduction: For Use as Nuclei for Preparation of Larger Particles.

    Science.gov (United States)

    Shirtcliffe; Nickel; Schneider

    1999-03-01

    Silver colloids are useful as substrates for surface enhanced Raman spectroscopy (SERS). The results are, however, seldom quantitative as the distribution of particle sizes in silver suspensions can vary from sample to sample and thus the SERS spectra can vary in intensity. Monodisperse silver sols are relatively difficult to prepare compared with gold or latex colloids as the nucleation process is difficult to control. Previous workers have used a system where small particles are formed in one process and grown in a second reaction. In this paper a simple procedure is outlined by which the small, "seed" particles (starter sols) can be prepared; this method is simpler and more reproducible than that used in the past. The process by which the sols can be grown is not discussed in detail here as it is the subject of a forthcoming publication. Copyright 1999 Academic Press.

  16. Preparation and characterization of silver nanoparticle loaded amorphous hydrogel of carboxymethylcellulose for infected wounds.

    Science.gov (United States)

    Das, Anup; Kumar, Ajay; Patil, Niranjan B; Viswanathan, Chandra; Ghosh, Deepa

    2015-10-05

    There is a growing demand for an appropriate and safe antimicrobial dressing to treat infected deep wounds. An amorphous gel formulation (SNP-CMC), containing silver nanoparticles (SNPs) and carboxymethylcellulose (CMC), was prepared in one step by the reduction of silver nitrate in situ. Spectrophotometric and microscopic analysis revealed that the SNPs were 7-21 nm in diameter. In simulated wound experiments, SNP-CMC gel was found to absorb 80.48 ± 4.69% w/w of saline and donate 17.43 ± 0.76% w/w of moisture within 24h indicating its dual fluid affinity. Cytocompatibility of the gel was assessed by proliferation studies with primary human skin cells. The antimicrobial activity studies showed that SNP-CMC containing 50 ppm of SNPs was effective against the growth of both Gram negative and Gram positive strains including methicillin-resistant Staphylococcus aureus (MRSA). These results indicate that SNP-CMC could be ideal for the treatment of deep infected wounds.

  17. Preparation of Size-Controlled Silver Nanoparticles and Chitin-Based Composites and Their Antimicrobial Activities

    Directory of Open Access Journals (Sweden)

    Vinh Quang Nguyen

    2013-01-01

    Full Text Available A simple method for the preparation of size-controlled spherical silver nanoparticles (Ag NPs was reported for their generation by autoclaving a mixture of silver-containing glass powder and glucose. The particle size is regulated by the glucose concentration, with concentrations of 0.25, 1.0, and 4.0 wt% glucose providing small (3.48±1.83 nm in diameter, medium (6.53±1.78 nm, and large (12.9±2.5 nm particles, respectively. In this study, Ag NP/chitin composites were synthesized by mixing each of these three Ag NP suspensions with a <5% deacetylated (DAc chitin powder (pH 7.0 at room temperature. The Ag NPs were homogenously dispersed and stably adsorbed onto the chitin. The Ag NP/chitin composites were obtained as yellow or brown powders. Approximately 5, 15, and 20 μg of the small, medium, and large Ag NPs, respectively, were estimated to maximally adsorb onto 1 mg of chitin. The bactericidal and antifungal activities of the Ag NP/chitin composites increased as the amount of Ag NPs in the chitin increased. Furthermore, smaller Ag NPs (per weight in the chitin composites provided higher bactericidal and anti-fungal activities.

  18. Investigating the versatility of multifunctional silver nanoparticles: preparation and inspection of their potential as wound treatment agents

    Science.gov (United States)

    Nam, Geewoo; Purushothaman, Baskaran; Rangasamy, Sabarinathan; Song, Joon Myong

    2016-11-01

    Silver nanoparticles (AgNPs) are capable of inhibiting the growth of a broad spectrum of bacterial species. The minute size of the nanoparticulates enhances their biocidal activity and is thus widely utilized as antibacterial agents. The most recently researched and recognized antibacterial and wound-healing properties of published AgNPs were investigated in this article. The following parameters of the AgNPs affecting their properties and potency were explored: particle size, shape, and type of ligand or stabilizing agent. Research regarding the antibacterial activity enhancement of high-valent silver nanoparticles compared to those of the lower valent forms were summarized and analyzed. Nanocrystalline silver is capable of binding to components that may enhance their preparation and antibacterial properties. By forming complexes with ligands that exhibit desired properties, silver nanoparticles can be synthesized to exhibit those desired properties without compromising their performance. This review will provide a detailed discussion regarding the parameter-dependent bactericidal properties of silver nanoparticles and nanocomposite silver complexes as potent multifunctional wound-healing agents.

  19. Formulation and method for preparing gels comprising hydrous hafnium oxide

    Science.gov (United States)

    Collins, Jack L; Hunt, Rodney D; Montgomery, Frederick C

    2013-08-06

    Formulations useful for preparing hydrous hafnium oxide gels contain a metal salt including hafnium, an acid, an organic base, and a complexing agent. Methods for preparing gels containing hydrous hafnium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including hafnium, an acid, an organic base, and a complexing agent.

  20. Formulation and method for preparing gels comprising hydrous aluminum oxide

    Science.gov (United States)

    Collins, Jack L.

    2014-06-17

    Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

  1. Formulation and method for preparing gels comprising hydrous cerium oxide

    Science.gov (United States)

    Collins, Jack L; Chi, Anthony

    2013-05-07

    Formulations useful for preparing hydrous cerium oxide gels contain a metal salt including cerium, an organic base, and a complexing agent. Methods for preparing gels containing hydrous cerium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including cerium, an organic base, and a complexing agent.

  2. Genotoxicity of copper oxide and silver nanoparticles in the mussel Mytilus galloprovincialis.

    Science.gov (United States)

    Gomes, Tânia; Araújo, Olinda; Pereira, Rita; Almeida, Ana C; Cravo, Alexandra; Bebianno, Maria João

    2013-03-01

    Though there is some information on cytotoxicity of copper nanoparticles and silver nanoparticles on human cell lines, there is no information on their genotoxic and cytotoxic behaviour in bivalve molluscs. The aim of this study was to investigate the genotoxic impact of copper oxide and silver nanoparticles using mussels Mytilus galloprovincialis. Mussels were exposed to 10 μg L⁻¹ of CuO nanoparticles and Cu²⁺ and Ag nanoparticles and Ag⁺ for 15 days to assess genotoxic effects in hemocytes using the comet assay. The results obtained indicated that copper and silver forms (nanoparticles and ionic) induced DNA damage in hemolymph cells and a time-response effect was evident when compared to unexposed mussels. Ionic forms presented higher genotoxicity than nanoparticles, suggesting different mechanisms of action that may be mediated through oxidative stress. DNA strand breaks proved to be a useful biomarker of exposure to genotoxic effects of CuO and Ag nanoparticles in marine molluscs. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Surface modification of indium tin oxide for direct writing of silver nanoparticulate ink micropatterns

    Energy Technology Data Exchange (ETDEWEB)

    Vunnam, Swathi, E-mail: swathi.vunnam@mines.sdsmt.edu [Nanoscience and Nanoengineering Department, South Dakota School of Mines and Technology, Rapid City, SD-57701 (United States); Ankireddy, Krishnamraju; Kellar, Jon; Cross, William [Department of Materials and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD-57701 (United States)

    2013-03-01

    Surface treatment techniques were deployed to alter the surface of indium tin oxide (ITO) samples to attain a favorable interface between printed nano-inks and ITO surface. Surface free energy components of treated ITO substrates were calculated for each treatment using the van Oss–Chaudhury–Good method. The surface treatments of ITO changed the Lifshitz–van der Waals and Lewis acid–base components, and contact angle hysteresis significantly. Among all the surface treatments, air plasma treated samples showed high polar in nature, whereas dodecyltrichlorosilane self-assembled monolayer treated sample showed the lowest. In addition to the polarity and homogeneity, the surface roughness of the ITO was studied with respect to the surface treatment. Silver nanoparticulate ink was printed on treated ITO surfaces using aerosol jet printing system. Printed silver nano-ink line width and morphology strongly depended on the surface treatment of the ITO, ink properties and printing parameters. - Highlights: ► Surface treatments on indium tin oxide (ITO) altered its surface free energy. ► Surface free energies were studied in terms of acid–base components. ► ITO surface morphology and roughness were changed with the surface treatment. ► Silver ink was printed on treated ITO samples using aerosol jet printing system. ► Line widths of printed patterns clearly depended on the surface free energy of ITO.

  4. Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

    Science.gov (United States)

    Shimabuku, Quelen Letícia; Arakawa, Flávia Sayuri; Fernandes Silva, Marcela; Ferri Coldebella, Priscila; Ueda-Nakamura, Tânia; Fagundes-Klen, Márcia Regina; Bergamasco, Rosangela

    2017-08-01

    Continuous flow experiments (450 mL min(-1)) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10(5) UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

  5. Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection to Gain Experience at the Nanochemistry-Microbiology Interface

    Science.gov (United States)

    Furlan, Ping Y.; Fisher, Adam J.; Melcer, Michael E.; Furlan, Alexander Y.; Warren, John B.

    2017-01-01

    We describe a 2 h introductory laboratory procedure that prepares a novel magnetic antimicrobial activated carbon nanocomposite in which nanoscale sized magnetite and silver particles are incorporated (MACAg). The MACAg nanocomposite has achieved the synergistic properties derived from its components and demonstrated its applicability as an…

  6. Structural, morphological, electrical, and optical properties of silver thin films of varying thickness deposited on cupric oxide

    Science.gov (United States)

    Hajakbari, Fatemeh; Shafieinejad, Farzaneh

    2016-03-01

    In this investigation, silver (Ag) films of varying thickness (25-100 nm) were grown on cupric oxide (CuO) on silicon and quartz. The CuO preparation was carried out by the thermal oxidation annealing of copper (Cu) thin films deposited by DC magnetron sputtering. The physical properties of the prepared films were studied by different techniques. Rutherford backscattering spectroscopy (RBS) analysis indicated that the Ag film thickness was about 25-100 nm. X-ray diffraction (XRD) results showed that by increasing Ag thickness, the film crystallinity was improved. Also, atomic force microscopy (AFM) and scanning electron microscopy (SEM) results demonstrated that the surface morphology and the grain size were affected by the Ag film thickness. Furthermore, the electrical resistivity of films determined by four-point probe measurements versus the Ag film thickness was discussed. A reduction in the optical band gap energy of CuO is observed from 1.51 to 1.42 eV with an increase in Ag film thickness to 40 nm in Ag/CuO films.

  7. Hardness and microstructure of internally oxidized silver alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prorok, B. C.; Park, J. H.; Goretta, K. C.; Balachandran, U.; McNallan, M. J.

    1999-11-11

    Alloys of Ag, Ag/1.12 at.% Mg, and Ag/0.25 at.% Mg-0.25 at.% Ni were internally oxidized at 450 to 825 C and their hardnesses and microstructure were observed. Microhardness profiles showed that hardness was high near the surface and decreased with depth into the sample. Microstructure contained regions of small and large grains, where region sizes were dependent on treatment temperature. Transitions between small- and large-grained regions were abrupt. Treatments at higher temperatures failed to alter grain structure, indicating that Mg-O clusters had indeed pinned the grain boundaries. Clustering was shown to affect the hardness of oxidized alloys, not only by inhibiting grain growth, but also by inhibiting dislocation motion.

  8. Copper/bamboo fabric composite prepared via a silver catalytic electroless deposition process for electromagnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Qian; Lu, Yinxiang [Fudan Univ., Shanghai (China). Dept. of Materials Science

    2013-09-15

    Copper/bamboo fabric composite prepared via a silver catalytic electroless plating process is reported. The microstructure of the composite was analyzed by means of scanning electron microscopy, which illustrated that the copper coating was composed of spherical particles and clusters. The composition and chemical state of the metal layer were measured using X-ray diffraction and energy-dispersive X-ray analysis spectra; copper and a small amount of nickel were detected. Mechanical properties were measured based on a standard (ISO 13934-1:1999) for the fabrics with and without copper coating. The breaking force for the composite was improved by about 16.8% compared to uncoated bamboo fabric. The electromagnetic interference shielding effectiveness of the composite was more than 40 dB at frequencies ranging from 0.2 to 1000MHz. The copper coating on bamboo fabric passed the Scotch {sup registered} -tape test. (orig.)

  9. Preparation and Properties of Silver Nanowire-Based Transparent Conductive Composite Films

    Science.gov (United States)

    Tian, Ji-Li; Zhang, Hua-Yu; Wang, Hai-Jun

    2016-06-01

    Silver nanowire-based transparent conductive composite films with different structures were successfully prepared using various methods, including liquid polyol, magnetron sputtering and spin coating. The experimental results revealed that the optical transmittance of all different structural composite films decreased slightly (1-3%) compared to pure films. However, the electrical conductivity of all composite films had a great improvement. Under the condition that the optical transmittance was greater than 78% over the wavelength range of 400-800 nm, the AgNW/PVA/AgNW film became a conductor, while the AZO/AgNW/AZO film and the ITO/AgNW/ITO film showed 88.9% and 94% reductions, respectively, for the sheet resistance compared with pure films. In addition, applying a suitable mechanical pressure can improve the conductivity of AgNW-based composite films.

  10. Method for preparing hydrous zirconium oxide gels and spherules

    Science.gov (United States)

    Collins, Jack L.

    2003-08-05

    Methods for preparing hydrous zirconium oxide spherules, hydrous zirconium oxide gels such as gel slabs, films, capillary and electrophoresis gels, zirconium monohydrogen phosphate spherules, hydrous zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite sorbent, zirconium monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite, hydrous zirconium oxide fiber materials, zirconium oxide fiber materials, hydrous zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite and spherules of barium zirconate. The hydrous zirconium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process are useful as inorganic ion exchangers, catalysts, getters and ceramics.

  11. Preparation and characterization of uniform-sized chitosan/silver microspheres with antibacterial activities

    Energy Technology Data Exchange (ETDEWEB)

    An, Jing; Ji, Zhenxing; Wang, Desong, E-mail: dswang06@126.com; Luo, Qingzhi; Li, Xueyan

    2014-03-01

    The chitosan/silver microspheres (CAgMs), which possess effective inhibitory on microorganisms, were prepared by an inverse-emulsification cross-linking method using CS/Ag sol as dispersed phase, whiteruss as continuous phase, and glutaraldehyde as crosslinking agent. The size and shape of CAgMs, greatly affecting their antibacterial activities, were controlled by varying the concentrations of cross-linking agent, emulsifier and CS/Ag colloid. The preparation conditions for obtaining uniform-sized microspheres were optimized. The morphology of CAgMs was characterized by scanning electron microscopy (SEM) and laser particle size analysis. The spherical CAgMs with smooth surface in the mean size of ca. 5 μm exhibited a narrow particle size distribution. Energy Dispersive X-ray spectroscopy (EDX) revealed the elemental composition of the microspheres. Transmission electron micrographs (TEM) and Fourier transform infrared spectroscopy (FTIR) of the microspheres confirmed the formation of silver nanoparticles (AgNPs). The X-ray diffraction (XRD) patterns and UV–Visible diffuse reflectance spectroscopy (UV–vis DRS) of the sample showed that AgNPs with the diameter no more than 20 nm were face-centered cubic crystallites. X-ray photoelectron spectroscopy (XPS) proved that Ag-O bond existed in the microspheres. Thermogravimetric analysis (TGA) showed that the starting decomposition temperature of CAgMs (ca. 260 °C) was much higher than that of CS (ca. 160 °C), suggesting that the as-prepared CAgMs possessed better thermal stability than original CS did. Antimicrobial assays were performed using typical Gram bacteria and fungi. The inhibitory effect indicated that the as-prepared microspheres exerted a stronger antibacterial activity as the concentration of the AgNPs is increasing, and the microspheres in smaller size had much better antibacterial activity than those in the larger size. The antimicrobial mechanism of CAgMs was discussed. - Highlights: • CAgM was

  12. Kinetic-spectrophotometric determination of trace amounts of silver using the oxidation of thionine with peroxodisulfate.

    Science.gov (United States)

    Tabatabaee, Masoumeh; Nateghi, Mohamad R; Mosavi, Seyed Jaml

    2006-12-01

    A simple, rapid and sensitive method has been developed for determination of traces of silver(I) (0.2 - 13 ng mL(-1)) based on its catalytic effect on the oxidation of thionine by peroxodisulfate in the presence of 1 - 10 phenanthroline as an activator. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 600 nm by the fixed time method. The detection limit is 0.098 ng mL(-1) and the relative standard deviation for 0.5, 3.0, 5.0 and 10 ng ml(-1) Ag(I) are 4.1, 1.37, 1.06 and 0.64%, respectively. The method is free from most interferences and it was applied to determination of silver in photographic solutions and well-water samples.

  13. Laser-Induced Silver Nanoparticles on Titanium Oxide for Photocatalytic Degradation of Methylene Blue

    Directory of Open Access Journals (Sweden)

    Jyun-Jen Chen

    2009-10-01

    Full Text Available Silver nanoparticles doped on titanium oxide (TiO2 were produced by laser-liquid interaction of silver nitrate (AgNO3 in isopropanol. Characteristics of Ag/TiO2 (Ag doped TiO2 nanoparticles produced by the methods presented in this article were investigated by XRD, TEM, SEM, EDX, and UV-Vis. From the UV-Vis measurements, the absorption of visible light of the Ag/TiO2 photocatalysts was improved (additional absorption at longer wavelength in visible light region obviously. The photocatalytic efficiency of Ag/TiO2 was tested by the degradation of methylene blue (MB in aqueous solution. A maximum of 82.3% MB degradation is achieved by 2.0 wt% Ag/TiO2 photocatalyst under 2 h illumination with a halogen lamp.

  14. Laser-induced silver nanoparticles on titanium oxide for photocatalytic degradation of methylene blue.

    Science.gov (United States)

    Whang, Thou-Jen; Huang, Hsien-Yu; Hsieh, Mu-Tao; Chen, Jyun-Jen

    2009-10-29

    Silver nanoparticles doped on titanium oxide (TiO(2)) were produced by laser-liquid interaction of silver nitrate (AgNO(3)) in isopropanol. Characteristics of Ag/TiO(2) (Ag doped TiO(2)) nanoparticles produced by the methods presented in this article were investigated by XRD, TEM, SEM, EDX, and UV-Vis. From the UV-Vis measurements, the absorption of visible light of the Ag/TiO(2) photocatalysts was improved (additional absorption at longer wavelength in visible light region) obviously. The photocatalytic efficiency of Ag/TiO(2) was tested by the degradation of methylene blue (MB) in aqueous solution. A maximum of 82.3% MB degradation is achieved by 2.0 wt% Ag/TiO(2) photocatalyst under 2 h illumination with a halogen lamp.

  15. 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

  16. One-pot green synthesis of silver/iron oxide composite nanoparticles for 4-nitrophenol reduction.

    Science.gov (United States)

    Chiou, Jau-Rung; Lai, Bo-Hung; Hsu, Kai-Chih; Chen, Dong-Hwang

    2013-03-15

    Silver/iron oxide composite nanoparticles have been synthesized successfully via a facile one-pot green route by the use of l-arginine, which created an aqueous solution of about pH 10 and acted as a reducing agent for the successive formation of iron oxide and Ag nanoparticles. The product was characterized to be silver-coated iron oxide and iron oxide hydroxide composite nanoparticles with a mean diameter of about 13.8 ± 3.0 nm and 8.53% of Ag in weight. It exhibited good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride. The reduction reaction followed the pseudo-first-order kinetics. The corresponding rate constants increased with the increases of temperature and catalyst amount but decreased with the increase of initial 4-NP concentration, revealing an activation energy of 28.2 kJ/mol and a diffusion controlled mechanism. In addition, this product had quite good stability. No significant activity loss was observed after reuse for 5 cycles. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. In vitro study on porous silver scaffolds prepared by electroplating method using cellular carbon skeleton as the substrate

    Energy Technology Data Exchange (ETDEWEB)

    Guo, M.; Wang, X.; Zhou, H.M.; Li, L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Nie, F.L. [Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Cheng, Y. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China)

    2012-05-01

    Porous silver scaffolds, with the porosity ranging from 68% to 81% and the apparent density ranging from 0.4 to 1 g Dot-Operator cm{sup -3} were prepared by electroplating method using cellular carbon skeleton as the substrate. The microstructure, mechanical property, cytotoxicity and antibacterial activity of the prepared porous silver scaffold were studied. The present porous silver scaffolds had a highly three-dimensional trabecular porous structure with the porosity and the apparent density close to that of the cancellous bone. Furthermore, the mechanical property such as elastic modulus and yield strength of the porous silver scaffolds were lower than that of commercial available porous Ti and porous Ti alloys but much closer to that of the cancellous bone and porous Ta. In addition, study of in vitro behavior showed that the porous silver scaffold possessed significant antibacterial capability of inhibition of bacterial proliferation and adherence against Staphylococcus aureus and Staphylococcus epidermidis, and little cytotoxicity to Mg-63 cell line and NIH-3T3 cell line. Consequently, the porous silver scaffolds prepared by electrodeposition possess a promising application for bone implants. - Highlights: Black-Right-Pointing-Pointer Porous Ag scaffolds were produced by electroplating Ag on cellular carbon skeleton. Black-Right-Pointing-Pointer Porous Ag scaffolds have the porosity 68-81% and the apparent density 0.4-1 g Dot-Operator cm{sup -3}. Black-Right-Pointing-Pointer The mechanical property of porous Ag is close to cancellous bone and porous Ta. Black-Right-Pointing-Pointer Porous Ag inhibits the proliferation and adherence of S. aureus and S. epidermidis.

  18. Stability of silver nanoparticles: agglomeration and oxidation in biological relevant conditions

    Science.gov (United States)

    Valenti, Laura E.; Giacomelli, Carla E.

    2017-05-01

    Silver nanoparticles (Ag-NP) are the most used nanomaterial in consumer products due to the intrinsic antimicrobial capacity of silver. However, Ag-NP may be also harmful to algae, aquatic species, mammalian cells, and higher plants because both Ag+ and nanoparticles are responsible of cell damages. The oxidative dissolution of Ag-NP would proceed to completion under oxic conditions, but the rate and extent of the dissolution depend on several factors. This work correlates the effect of the capping agent (albumin and citrate) with the stability of Ag-NP towards agglomeration in simulated body fluid (SBF) and oxidation in the presence of ROS species (H2O2). Capping provides colloidal stability only through electrostatic means, whereas albumin acts as bulky ligands giving steric and electrostatic repulsion, inhibiting the agglomeration in SBF. However, citrate capping protects Ag-NP from dissolution to a major extent than albumin does because of its reducing power. Moreover, citrate in solution minimizes the oxidation of albumin-coated Ag-NP even after long incubation times. H2O2-induced dissolution proceeds to completion with Ag-NP incubated in SBF, while incubation in citrate leads to an incomplete oxidation. In short, albumin is an excellent capping agent to minimize Ag-NP agglomeration whereas citrate provides a mild-reductive medium that prevents dissolution in biological relevant media as well as in the presence of ROS species. These results provide insight into how the surface properties and media composition affect the release of Ag+ from Ag-NP, related to the cell toxicity and relevant to the storage and lifetime of silver-containing nanomaterials.

  19. Ferrocenyl branched poly (ethylene imine) micelles as reductive templates for the preparation of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Leize; Zhou Wenbo; Ji Jian, E-mail: jijian@zju.edu.c [Zhejiang University, Department of Polymer Science, Key Laboratory of Macromolecule Synthesis and Functionalization of Minister of Education (China)

    2010-08-15

    Polymeric micelles with a branched poly (ethylene imine) shell and a reductive ferrocene core were prepared via self-assembly of ferrocene modified branched poly (ethylene imine) (BPEI-Fc). The well-controlled polymeric micelles with a reductive core were used as templates to prepare core-shell-structured silver nanoparticles (AgNPs) in aqueous solution. The as-prepared nanoparticles were characterized by UV-Vis spectrophotometer, transmission electron microscope (TEM), selected-area electron diffraction (SAED), thermogravimetry analyzer (TGA), and dynamic light scattering (DLS). The AgNPs of 39 {+-} 9 nm with a 39-nm BPEI layer were obtained. It is demonstrated that ferrocene, which is a neutral, chemically stable, and nontoxic molecule, plays a dual role as the hydrophobe and as the electron donating group. Moreover, the formation of these particles was monitored in situ by UV-Vis spectrophotometer. It is found that the growth of AgNPs through reductive templates is much slower than that reduced by NaBH{sub 4}. Meanwhile, the size distribution of AgNPs becomes narrower during the reaction. BPEI-covered AgNPs (Ag-BPEI) are stable up to 3 months and carry amino groups, which can further be bioconjugated. These core-shell-structured nanoparticles may enable them to be used for wide applications in aqueous solution.

  20. Ferrocenyl branched poly (ethylene imine) micelles as reductive templates for the preparation of silver nanoparticles

    Science.gov (United States)

    Zhu, Lei-ze; Zhou, Wen-bo; Ji, Jian

    2010-08-01

    Polymeric micelles with a branched poly (ethylene imine) shell and a reductive ferrocene core were prepared via self-assembly of ferrocene modified branched poly (ethylene imine) (BPEI-Fc). The well-controlled polymeric micelles with a reductive core were used as templates to prepare core-shell-structured silver nanoparticles (AgNPs) in aqueous solution. The as-prepared nanoparticles were characterized by UV-Vis spectrophotometer, transmission electron microscope (TEM), selected-area electron diffraction (SAED), thermogravimetry analyzer (TGA), and dynamic light scattering (DLS). The AgNPs of 39 ± 9 nm with a 39-nm BPEI layer were obtained. It is demonstrated that ferrocene, which is a neutral, chemically stable, and nontoxic molecule, plays a dual role as the hydrophobe and as the electron donating group. Moreover, the formation of these particles was monitored in situ by UV-Vis spectrophotometer. It is found that the growth of AgNPs through reductive templates is much slower than that reduced by NaBH4. Meanwhile, the size distribution of AgNPs becomes narrower during the reaction. BPEI-covered AgNPs (Ag@BPEI) are stable up to 3 months and carry amino groups, which can further be bioconjugated. These core-shell-structured nanoparticles may enable them to be used for wide applications in aqueous solution.

  1. In situ Silver Spot Preparation and on-Plate Surface-Enhanced Raman Scattering Detection in Thin Layer Chromatography Separation

    Science.gov (United States)

    Herman, K.; Mircescu, N. E.; Szabo, L.; Leopold, L. F.; Chiş, V.; Leopold, N.

    2013-05-01

    An improved approach for surface-enhanced Raman scattering (SERS) detection of mixture constituents after thin layer chromatography (TLC) separation is presented. A SERS active silver substrate was prepared under open air conditions, directly on the thin silica film by photo-reduction of silver nitrate, allowing the detection of binary mixtures of cresyl violet, bixine, crystal violet, and Cu(II) complex of 4-(2-pyridylazo)resorcinol. The recorded SERS spectrum provides a unique spectral fingerprint for each molecule; therefore the use of analyte standards is avoided, thus rendering the presented procedure advantageous compared to the conventional detection methodology in TLC.

  2. The influence of narrow optical gap silver oxide on zinc oxide nanoparticles produced by microwave-assisted colloidal synthesis: photocatalytic studies

    Science.gov (United States)

    Prakoso, S. P.; Paramarta, V.; Tju, H.; Taufik, A.; Saleh, R.

    2016-11-01

    This paper reports a photocatalytic study on wide band gap zinc oxide (ZnO) incorporated by narrow band gap silver oxide (Ag2O), namely Ag2O/ZnO nanocomposites, which were prepared by colloidal synthesis with microwave supports. The Ag2O/ZnO nanocomposites were prepared with three different molar ratios (MR) of Ag2O to ZnO (MR: 0.25, 0.5 and 0.75). In order to confirm qualitatively the concentration ratio of Ag2O in ZnO, crystal phase intensity ratio was executed by peak indexing from x-ray diffraction. The Ag2O/ZnO nanocomposites properties were further investigated using diffuse reflectance spectroscopy. The nanocomposites were tested for the degradation of organic dyes solutions under visible and UV light irradiations. The photocatalytic activity of Ag2O/ZnO nanocomposites under visible light increased with increasing molar ratio of Ag2O to ZnO, while the opposite trends observed under UV light irradiation. The improvement of photoabsorption together with photocatalytic activities might be suspected due to the p-n heterojunction structure in Ag2O/ZnO nanocomposites. The corresponding mechanism will be discussed in detail.

  3. High performance flexible metal oxide/silver nanowire based transparent conductive films by a scalable lamination-assisted solution method

    Directory of Open Access Journals (Sweden)

    Hua Yu

    2017-03-01

    Full Text Available Flexible MoO3/silver nanowire (AgNW/MoO3/TiO2/Epoxy electrodes with comparable performance to ITO were fabricated by a scalable solution-processed method with lamination assistance for transparent and conductive applications. Silver nanoparticle-based electrodes were also prepared for comparison. Using a simple spin-coating and lamination-assisted planarization method, a full solution-based approach allows preparation of AgNW-based composite electrodes at temperatures as low as 140 °C. The resulting flexible AgNW-based electrodes exhibit higher transmittance of 82% at 550 nm and lower sheet resistance about 12–15 Ω sq−1, in comparison with the values of 68% and 22–25 Ω sq−1 separately for AgNP based electrodes. Scanning electron microscopy (SEM and Atomic force microscopy (AFM reveals that the multi-stacked metal-oxide layers embedded with the AgNWs possess lower surface roughness (<15 nm. The AgNW/MoO3 composite network could enhance the charge transport and collection efficiency by broadening the lateral conduction range due to the built of an efficient charge transport network with long-sized nanowire. In consideration of the manufacturing cost, the lamination-assisted solution-processed method is cost-effective and scalable, which is desire for large-area fabrication. While in view of the materials cost and comparable performance, this AgNW-based transparent and conductive electrodes is potential as an alternative to ITO for various optoelectronic applications.

  4. The antimicrobial activity of as-prepared silver-loaded phosphate glasses and zirconium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Wang; Jiang, Ji Zhi; Yang, Yang; Yan, Zhao Chun; Yan, Wang Xiao [China Building Materials Academy, Beijing (China); He, Shui Zhong [Wuhan University of Technology, Wuhan (China)

    2016-03-15

    The antimicrobial activities of silver-loaded zirconium phosphate (JDG) and silver-loaded phosphate glasses (ZZB) against Escherichia coli were studied. Although the silver content in JDG was higher than that in ZZB, ZZB suspensions showed better antimicrobial property than JDG suspensions, especially at low concentrations. The antimicrobial activity was analyzed using minimum inhibitory concentrations, bacterial inhibition ring tests, and detection of silver ions in the suspensions. Furthermore, the amounts of silver ions in suspensions with/without bacterial cells were analyzed. Results revealed that only a portion of released silver ions could be adsorbed by E. coli cells, which are critical to cell death. The damaged microstructures of E. coli cells observed by transmission electron microscopy may further prove that the adsorbed silver ions play an important role in the antimicrobial process.

  5. Recovery of Silver Using Adsorption Gels Prepared from Microalgal Residue Immobilized with Functional Groups Containing Sulfur or Nitrogen

    Directory of Open Access Journals (Sweden)

    Kanjana Khunathai

    2017-06-01

    Full Text Available Although biodiesel oil extracted from microalgae attracts much attention as one of the most promising green energies, its high production cost is a big problem, impeding its extensive use. In order to lower the production cost, the effective use of microalgal residue after extracting biofuel was investigated as a feed material of functional materials. In the present work, a new adsorbent for silver(I was prepared by immobilizing functional groups of polyethylene-polyamine or dithiooxamide, which exhibita high affinity for soft Lewis acids such as silver(I ions. Their adsorption behaviors for silver(I were investigated from aqueous nitrate and acidothiourea media. The effects of the concentrations of nitrate and thiourea, as well as of sulfuric acid, were qualitatively interpreted. From the study of adsorption isotherms on these gels, they were found to exhibita higher adsorption capacity than the majority of those reported to date.

  6. Preparation and Characterization of Nano-silver Loaded Montmorillonite with Strong Antibacterial Activity and Slow Release Property

    Institute of Scientific and Technical Information of China (English)

    Guangnian Xu; Xueliang Qiao; Xiaolin Qiu; Jianguo Chen

    2011-01-01

    Nano-silver loaded montmorillonite (Ag-MMT) was prepared by ion-exchange and then a UV-photoreduction two-step approach was applied. The silver content in Ag-MMT determined by Volhard method was about 6.4 wt%. The morphology and structure of as-synthesized Ag-MMT were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the Ag nanoparticles were spherical and their diameters were about 15-20 nm. Moreover, the structure of MMT did not change. The minimum inhibition concentration (MIC) of Ag-MMT was 100×10-6 and the sterilizing efficiency (SE) of Ag-MMT was approximately 100% against Escherichia coli ATCC 11229 (E. coli. In addition, the slow release property of silver in Ag-MMT was also demonstrated.

  7. Microwave assisted facile synthesis of reduced graphene oxide-silver (RGO-Ag) nanocomposite and their application as active SERS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wadhwa, Heena, E-mail: heenawadhwa1988@gmail.com; Kumar, Devender, E-mail: devkumsaroha@kuk.ac.in; Mahendia, Suman, E-mail: mahendia@gmail.com; Kumar, Shyam, E-mail: profshyam@gmail.com

    2017-06-15

    The present paper represents the facile and rapid synthesis of reduced graphene oxide-silver (RGO-Ag) nanocomposite with the help of microwave irradiation. The graphene oxide (GO) solution has been prepared in bulk using Hummer's method followed by microwave assisted in-situ reduction of GO and silver nitrate (AgNO{sub 3}) by hydrazine hydrate in a short spam of 5 min. The prepared nanocomposite has been characterized using Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) Scanning Electron Microscopy (SEM) and UV–Visible spectroscopy. TEM analysis shows that Ag nanoparticles with average size 32 nm are uniformly entangled with in RGO layers. The UV–Visible absorption spectrum of nanocomposite depicts the reduction of GO to RGO along with the formation of Ag nanoparticles with the presence of characteristic surface Plasmon resonance (SPR) peak of Ag nanoparticles at 422 nm. The performance of prepared nanocomposite has been tested as the active Surface Enhanced Raman Scattering (SERS) substrate for Rhodamine 6G with detection limit 0.1 μM. - Highlights: • The RGO and RGO-Ag nanocomposite were synthesized with microwave irradiation. • Ag nanoparticles of average size 32 nm are uniformly entangled within RGO layers. • RGO itself is a florescence quencher with SERS detection limit 1 μM for R6G. • RGO-Ag nanocomposite show good SERS activity for R6G with detection limit 0.1 μM.

  8. Facile Preparation and Formation Mechanism of Uniform Silver Nanoparticles Using OP-10 as Emulsifier in Reverse Microemulsion

    Institute of Scientific and Technical Information of China (English)

    WU Xia; WANG Ting; WU Hui

    2011-01-01

    Using the polymerizable hydrophobic styrene monomer as the dispersion medium and the traditional nonionic surfactant OP-10 as emulsifier, stable silver nanoparticles of narrow size distribution were prepared by a reverse (w/o) microemulsion method. The powder X-ray diffraction (XRD) pattern indicated that the obtained silver nanoparticles were of face-centered cubic structure.The results of the transmission electron microscopy (TEM) show that the final silver nanoparticles are of spherical structure with an average diameter of 15.2 nm and ofa Gaussian distribution. The internal high-ordered structure of silver nanoparticles was characterized by the field-emission high-resolution transmission electron microscopy (FEHRTEM), indicating that the silver is monocrystalline and it has only one nucleation site during the formation process of a nanoparticle. The time-resolved UV-visible absorption spectra was used to monitor the process of the reaction in situ. The results show that the concentration of silver nanoparticles increases but the size changes little and the morphology transforms from obvious ellipsoidal shape to nearly spherical shape during the process. The experimental results indicate that the droplets' dynamic exchange which is closely related to the nature of surfactant film is the control factor of the kinetics. The dynamic exchange mechanism of silver nanoparticle formation is proposed to involve continual encounter of two separate droplets forming transient fused dimer in which the chemical reaction occurs followed by re-separation without combination. Attributed to the dual role of surfactant in the nanoparticle formation, tailored nanoparticles can be successfully synthesized in control in the premise of a certain stability of reverse microemulsion.

  9. Visible-light-enhanced catalytic oxidation reactions on plasmonic silver nanostructures.

    Science.gov (United States)

    Christopher, Phillip; Xin, Hongliang; Linic, Suljo

    2011-06-01

    Catalysis plays a critical role in chemical conversion, energy production and pollution mitigation. High activation barriers associated with rate-limiting elementary steps require most commercial heterogeneous catalytic reactions to be run at relatively high temperatures, which compromises energy efficiency and the long-term stability of the catalyst. Here we show that plasmonic nanostructures of silver can concurrently use low-intensity visible light (on the order of solar intensity) and thermal energy to drive catalytic oxidation reactions--such as ethylene epoxidation, CO oxidation, and NH₃ oxidation--at lower temperatures than their conventional counterparts that use only thermal stimulus. Based on kinetic isotope experiments and density functional calculations, we postulate that excited plasmons on the silver surface act to populate O₂ antibonding orbitals and so form a transient negative-ion state, which thereby facilitates the rate-limiting O₂-dissociation reaction. The results could assist the design of catalytic processes that are more energy efficient and robust than current processes.

  10. Easily separated silver nanoparticle-decorated magnetic graphene oxide: Synthesis and high antibacterial activity.

    Science.gov (United States)

    Zhang, Huai-Zhi; Zhang, Chang; Zeng, Guang-Ming; Gong, Ji-Lai; Ou, Xiao-Ming; Huan, Shuang-Yan

    2016-06-01

    Silver nanoparticle-decorated magnetic graphene oxide (MGO-Ag) was synthesized by doping silver and Fe3O4 nanoparticles on the surface of GO, which was used as an antibacterial agent. MGO-Ag was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray (EDS), X-ray diffraction (XRD), Raman spectroscopy and magnetic property tests. It can be found that magnetic iron oxide nanoparticles and nano-Ag was well dispersed on graphene oxide; and MGO-Ag exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. Several factors were investigated to study the antibacterial effect of MGO-Ag, such as temperature, time, pH and bacterial concentration. We also found that MGO-Ag maintained high inactivation rates after use six times and can be separated easily after antibacterial process. Moreover, the antibacterial mechanism is discussed and the synergistic effect of GO, Fe3O4 nanoparticles and nano-Ag accounted for high inactivation of MGO-Ag.

  11. Antibacterial electrospun chitosan-polyethylene oxide nanocomposite mats containing bioactive silver nanoparticles.

    Science.gov (United States)

    Kohsari, Iraj; Shariatinia, Zahra; Pourmortazavi, Seied Mahdi

    2016-04-20

    The antimicrobial chitosan-polyethylene oxide (CS-PEO) nanofibrous mats were developed by electrospinning technique for wound dressing applications. Indeed, a green route was introduced for fabrication of antibacterial mats loaded with 0.25% and 0.50% (w/w) of bioactive silver nanoparticles (Ag NPs, ∼70nm diameter) reduced by Falcaria vulgaris herbal extract. The mats were characterized by FE-SEM, EDAX, elemental mapping, FT-IR, contact angle, TGA/DSC as well as tensile strength analysis. All of the nanofibers had an average ∼200nm diameter. Interestingly, both of the CS-PEO mats containing 0.25% and 0.50% bioactive F. vulgaris-Ag NPs revealed 100% bactericidal activities against both Staphylococcus aureus and Escherichia coli bacteria. The silver release from nanofiber mats was sharply increased within first eight hours for both CS-PEO mats including 0.25% and 0.50% F. vulgaris-Ag NPs but after that the Ag nanoparticles were released very slowly (almost constant). The improved hydrophilicity, higher tensile strength and much greater silver release for CS-PEO-0.50% F. vulgaris-Ag NPs relative to those of the CS-PEO 0.25% F. vulgaris-Ag NPs suggested that the former was superior for biomedical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Preparation and characterization of functional fabrics from bamboo charcoal/silver and titanium dioxide/silver composite powders and evaluation of their antibacterial efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fu-Chu, E-mail: yfc580629@yahoo.com.tw [Army Command Headquarters, MND, Taoyuan, Taiwan (China); Wu, Kuo-Hui [Department of Applied Chemistry and Materials Science, Chung Cheng Institute of Technology, NDU, No. 190, Sanyuan 1st Street, Tahsi, Taoyuan 335, Taiwan (China); Huang, Jen-Wei [Department of Physics, Chinese Military Academy, Fengshan, Kaohsiung, Taiwan (China); Horng, Deng-Nan; Liang, Chia-Feng [Department of Chemistry, Chinese Military Academy, Fengshan, Kaohsiung, Taiwan (China); Hu, Ming-Kuan [School of Pharmacy, National Defense Medical Center, Taipei, Taiwan (China)

    2012-07-01

    Bamboo charcoal supporting silver (BC/Ag) and titanium dioxide supporting silver (TiO{sub 2}/Ag) were prepared by activation and chemical reduction. The BC/Ag and TiO{sub 2}/Ag composites were characterized by silver particle size and distribution and antibacterial properties. The pore and surface properties were studied in terms of BET volumetric measurement with nitrogen adsorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The antibacterial effects of the BC/Ag and TiO{sub 2}/Ag composite powders were assessed from the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs), and an excellent antibacterial performance was discovered. Moreover, these composite powders were deposited via immersion coating onto fabrics (nonwoven and carbon fibers) to improve the antibacterial efficacy and to act as a biologically-protective material. The antibacterial activities of the fabrics supported by BC/Ag and TiO{sub 2}/Ag were studied in zone of inhibition and plate counting tests against Gram-positive Staphylococcus aureus ME/GM/TC Resistant, Bacillus subtilis, Candida albicans, Gram-negative Pseudomonas aeruginosae (CTZ and EM and GM) Res. Clin. Isol., Escherichia coli Juhl, and Klebsiella pneumoniae. The results showed that fabric-BC/Ag and fabric-TiO{sub 2}/Ag possess a strong antibacterial activity and an inhibitory effect on the growth of these bacteria and are therefore believed to have great potential for use as antibacterial fabrics.

  13. Preparation of Silver Nanoparticles from Synthetic and Natural Sources: Remediation Model for PAHs

    Science.gov (United States)

    Abbasi, Maryam; Saeed, Fatima; Rafique, Uzaira

    2014-06-01

    The emergence of nanoscience and technology is gaining popularity with an increasing demand for metal nanoparticles applicability in various areas such as electronics, catalysis, chemistry, energy and medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are quite often toxic and flammable. In this work, an attempt is made to compare the efficiency of two different synthesis methods and application of each for the remediation of poly aromatic hydrocarbons (PAHs). In this regard, silver nanoparticles are prepared by green and wet chemical method using plant extract of garlic (Allium sativum). The extract is known to reduce the metal during synthesis and acts as stabilizing ligand. These synthesized silver nanoparticles (Agp) and (AgW) were applied as adsorbents in synthetic batch mode experiments at varying parameters of pH and temperature. A concentration of 0.01mg/L of Phenanthrene, Anthracene, and Pyrene were induced at fixed dosage of 1mg/Kg of adsorbent. Residual concentration of each PAH was analyzed on UV-Visible spectrophotometer. The results indicated that both adsorbents follow the sequence of Phenanthrene>Pyrene>Anthracene with optimal removal of higher than 85% in each case. A distinguishing privilege is attained by Agp adsorbent showing 3, 3 and 11 orders of magnitude higher efficiency than Agw. It may be attributed to more functional groups in the plant extract participating in binding of PAH to the surface. Each synthesized adsorbents was characterized by FTIR, SEM and EDX. The average particle size was determined to be of the order of 13-26 nm. The study concludes the use of alternate economical and green adsorbents for control of poly aromatic hydrocarbons (PAHs).

  14. Photocatalytic Oxidation of Gaseous Isopropanol Using Visible-Light Active Silver Vanadates/SBA-15 Composite

    Directory of Open Access Journals (Sweden)

    Ting-Chung Pan

    2012-01-01

    Full Text Available An environmentally friendly visible-light-driven photocatalyst, silver vanadates/SBA-15, was prepared through an incipient wetness impregnation procedure with silver vanadates (SVO synthesized under a hydrothermal condition without a high-temperature calcination. The addition of mesoporous SBA-15 improves the formation of nanocrystalline silver vanadates. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS confirms the presence of Brønsted and Lewis acids on the SVO/SBA-15 composites. The results of photoluminescence spectra indicated that the electron-hole recombination rate have been effectively inhibited when SVO was loaded with mesoporous SBA-15. All the composites loaded with various amount of SVO inherit the higher adsorption capacity and larger mineralization yield than those of P-25 (commercial TiO2 and pure SVO. The sample loaded with 51% of SVO (51SVO/SBA-15 with mixed phases of Ag4V2O7 and α-Ag3VO4 exhibits the best photocatalytic activity. A favorable crystalline phase combined with high intensities of Brønsted and Lewis acids is considered the main cause of the enhanced adsorption capacity and outstanding photoactivity of the SVO/SBA-15 composites.

  15. Preparation and antibacterial property of silver-containing mesoporous 58S bioactive glass.

    Science.gov (United States)

    Zhu, Hailin; Hu, Chao; Zhang, Fangfang; Feng, Xinxing; Li, Jiuming; Liu, Tao; Chen, Jianyong; Zhang, Jianchun

    2014-09-01

    The modified mesoporous 58S bioglass (SM58S) was prepared through surface modification of the mesoporous 58S bioglass (M58S) with γ-aminopropyl triethoxysilane (KH550). The results of Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) showed that the amino groups were grafted to the surface of M58S after modification with KH550. The silver-containing SM58S (Ag-SM58S) and M58S (Ag-M58S) were prepared by the dipping method. The Ag(+) loading capacity, release rate and antibacterial properties of Ag-SM58S and Ag-M58S were investigated. It is indicated that surface modification of M58S with KH550 can improve the Ag(+) loading capacity. The result of antibacterial property showed that Ag-SM58S exhibited significant anti-bacterial effects against Escherichia coli and Staphylococcus aureus. The sustained release of Ag(+) from Ag-SM58S for 768h ensured excellent antibacterial property of Ag-SM58S. In vitro osteoblast proliferation and differentiation tests showed that Ag-SM58S was a good matrix for the growth of osteoblasts. Consequently, the results of the study suggested that Ag-SM58S might be a promising bone repair material.

  16. Influences of Silver-Doping on the Crystal Structure, Morphology and Photocatalytic Activity of TiO2 Nanofibers

    DEFF Research Database (Denmark)

    Barakat, Nasser A. M.; Kanjwal, Muzafar Ahmed; Al-Deyab, Salem S.

    2011-01-01

    activity of titanium oxide nanofibers has been studied. Sil-ver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600°C. The results affirmed formation of silver...

  17. A Nanoarchitecture Based on Silver and Copper Oxide with an Exceptional Response in the Chlorine-Promoted Epoxidation of Ethylene.

    Science.gov (United States)

    Ramirez, Adrian; Hueso, Jose L; Suarez, Hugo; Mallada, Reyes; Ibarra, Alfonso; Irusta, Silvia; Santamaria, Jesus

    2016-09-05

    The selective oxidation of ethylene to ethylene epoxide is highly challenging as a result of competing reaction pathways leading to the deep oxidation of both ethylene and ethylene oxide. Herein we present a novel catalyst based on silver and copper oxide with an excellent response in the selective oxidation pathway towards ethylene epoxide. The catalyst is composed of different silver nanostructures dispersed on a tubular copper oxide matrix. This type of hybrid nanoarchitecture seems to facilitate the accommodation of chlorine promoters, leading to high yields at low reaction temperatures. The stability after the addition of chlorine promoters implies a substantial improvement over the industrial practice: a single pretreatment step at ambient pressure suffices in contrast with the common practice of continuously feeding organochlorinated precursors during the reaction.

  18. Synthesis of silver nanoparticles on reduced graphene oxide under microwave irradiation with starch as an ideal reductant and stabilizer

    Science.gov (United States)

    Han, Yujie; Luo, Zhimin; Yuwen, Lihui; Tian, Jing; Zhu, Xingrong; Wang, Lianhui

    2013-02-01

    A facile aqueous solution procedure has been developed to synthesize silver nanoparticles (Ag NPs) on reduced graphene oxide (RGO) (RGO/Ag NPs) with starch as an ideal reductant and stabilizer in one pot under microwave irradiation. Graphene oxide and Ag(NH3)2+ were reduced simultaneously by starch in the process of forming Ag NPs. The size of Ag NPs decorated on the RGO sheets is about 20-50 nm and the average size of Ag NPs on RGO is 34 nm calculated by X-ray diffraction. RGO and RGO/Ag NPs prepared with starch show good stability in aqueous solution. With the decoration of Ag NPs on RGO, Raman intensity of RGO increased evidently. Antimicrobial activity of RGO/Ag NPs was investigated against the gram negative bacteria Pseudomonous aeruginosa. The minimum inhibitory concentration (MIC) of RGO/Ag NPs is 0.2 wt%. The antimicrobial activity of RGO/Ag NPs is stronger than Ag NPs because of the synergic effect of RGO and Ag NPs.

  19. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    Science.gov (United States)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  20. Development of silver/gold nanocages onto indium tin oxide glass as a reagentless plasmonic mercury sensor

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daodan; Hu, Tingting; Chen, Na [The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou 215123 (China); Zhang, Wei, E-mail: zhangwei@cigit.ac.cn [Key Laboratory of Multi-scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China); Di, Junwei, E-mail: djw@suda.edu.cn [The Key Lab of Health Chemistry and Molecular Diagnosis of Suzhou, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou 215123 (China)

    2014-05-01

    Highlights: • A reagentless, sensitive and selective optical sensor for detection of Hg(II) was developed. • Silver–gold nanocages were prepared on the transparent indium tin oxide coated glass surface. • The nanomaterials could act as optical sensing probe as well as reducing agent. • The plasmonic sensor could be used to detect mercury ions in field analysis. Abstract: We demonstrate the utilization of silver/gold nanocages (Ag/Au NCs) deposited onto transparent indium tin oxide (ITO) film glass as the basis of a reagentless, simple and inexpensive mercury probe. The localized surface plasmon resonance (LSPR) peak wavelength was located at ~800 nm. By utilizing the redox reaction between Hg²⁺ ions and Ag atoms that existed in Ag/Au NCs, the LSPR peak of Ag/Au NCs was blue-shifted. Thus, we develop an optical sensing probe for the detection of Hg²⁺ ions. The LSPR peak changes were lineally proportional to the concentration of Hg²⁺ ions over the range from 10 ppb to 0.5 ppm. The detection limit was ~5 ppb. This plasmonic probe shows good selectivity and high sensitivity. The proposed optical probe is successfully applied to the sensing of Hg²⁺ in real samples.

  1. Gold & silver nanoparticles supported on manganese oxide: Synthesis, characterization and catalytic studies for selective oxidation of benzyl alcohol

    Directory of Open Access Journals (Sweden)

    Saad Alabbad

    2014-12-01

    Full Text Available Nano-gold and silver particles supported on manganese oxide were synthesized by the co-precipitation method. The catalytic properties of these materials were investigated for the oxidation of benzyl alcohol using molecular oxygen as a source of oxygen. The catalyst was calcined at 300, 400 and 500 °C. They were characterized by electron microscopy, powder X-ray diffraction (XRD and surface area. It was observed that the calcination temperature affects the size of the nanoparticle, which plays a significant role in the catalytic process. The catalyst calcined at 400 °C, gave a 100% conversion and >99% selectivity, whereas catalysts calcined at 300 and 500 °C gave a conversion of 69.51% and 19.90% respectively, although the selectivity remains >99%.

  2. A strategic approach for preparation of oxide nanomaterials

    Indian Academy of Sciences (India)

    K J Rao; Krishnamurthy Mahesh; Sundeep Kumar

    2005-02-01

    A microwave assisted solvothermal method is described for rapid preparation of nano-oxides. This method is based on exploiting differential dielectric constants to induce preferred heating and decomposition of the oxide precursors in the presence of suitable capping agents. This strategic approach has been used to prepare nanopowders of MgO, NiO, ZnO, Al2O3, Fe2O3 and ZrO2.

  3. One-step Preparation and Antibacterial Property of Poly(N-iso- propyl-acrylamide) Grafted Poly(acrylonitrile/styrene) Micro- spheres Immobilized with Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    FENG,Jiao; FAN,Liheng; CHU,Hong; XIONG,Wanbin; JIANG,Jinqiang; CHEN,Mingqing

    2009-01-01

    Monodispersed silver nanoparticles were immobilized onto the surface of poly(N-isopropylacrylamide) grafted poly(acrylonitrile/styrene) (PNIPAAm-g-PAN/PSt) microspheres by a one-step method using AgNO3 as a silver source. This process was performed via the coordination interaction between Ag ions and amide groups on PNIPAAm-g-PAN/PSt microsphere surfaces with the reduction of the corresponding ions by ethanol taking place simultaneously. Fourier transform infrared (FTIR) spectroscopy and ultraviolet (UV)-visible spectra illustrated that the silver nanoparticles were successfully immobilized onto the PNIPAAm-g-PAN/PSt microspheres. The size and morphology of silvered microspheres were characterized by transmission electron microscopy (TEM). The weight percent of silver nanoparticles immobilized onto the microspheres was 12% based on the determination of thermogravimetric analysis (TGA). The antibacterial tests demonstrated that the as-prepared silvered microspheres showed activity against Gram-negative bacteria.

  4. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

    Science.gov (United States)

    Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates.

  5. Nonlinear-Optical and Fluorescent Properties of Ag Aqueous Colloid Prepared by Silver Nitrate Reduction

    Directory of Open Access Journals (Sweden)

    Xiaoqiang Zhang

    2010-01-01

    Full Text Available The nonlinear-optical properties of metal Ag colloidal solutions, which were prepared by the reduction of silver nitrate, were investigated using Z-scan method. Under picosecond 532 nm excitation, the Ag colloidal solution exhibited negative nonlinear refractive index (n2=−5.17×10−4 cm2/W and reverse saturable absorption coefficient (β=4.32 cm/GW. The data fitting result of optical limiting (OL response of metal Ag colloidal solution indicated that the nonlinear absorption was attributed to two-photon absorption effect at 532 nm. Moreover, the fluorescence emission spectra of Ag colloidal solution were recorded under excitations at both 280 nm and 350 nm. Two fluorescence peaks, 336 nm and 543 nm for 280 nm excitation, while 544 nm and 694 nm for 350 nm excitation, were observed.

  6. Large 2D-arrays of size-controllable silver nanoparticles prepared by hybrid deposition

    Science.gov (United States)

    Dieu Thuy Ung, Thi; Hoa Nguyen, Thi; Liem Nguyen, Quang

    2016-09-01

    Two main results are presented in this paper. (i) Silver nanoparticles (AgNPs) with uniform size-distribution and controllability in the range of 20-50 nm were synthesized by seeding and growing at ambient conditions. The single-crystal Ag nano-seeds were created by reduction of AgNO3 in presence of citrate surfactant at 70 °C. Then, importantly, the fresh AgCl precursor was used in the presence of polyvinylpyrrolidone to adjust the reaction rate with ascorbic acid to generate Ag for growing on the surface of single-crystal Ag nano-seeds. The AgNPs size could be well-controlled by varying the amount of Ag nano-seeds while keeping the AgCl precursor concentration to be constant. (ii) The large 2D-arrays with homogeneous and dense monolayers of AgNPs were prepared on ITO substrates by hybrid method, in which the key technological point is the surface functionalization of AgNPs using mixed alkanethiols (dodecanethiol:octadecanethiol = 6:1). We have used the fabricated 2D-arrays from the 50 nm AgNPs as a surface enhanced Raman scattering substrate to take the Raman scattering spectra of rhodamine B (RhB), glucose and viral pathogen (H5N1) at very low concentrations of 10-10 M, 10-12 M and 4 ng μl-1, respectively.

  7. Particle Size and Pore Structure Characterization of Silver Nanoparticles Prepared by Confined Arc Plasma

    Directory of Open Access Journals (Sweden)

    Mingru Zhou

    2009-01-01

    Full Text Available In the protecting inert gas, silver nanoparticles were successfully prepared by confined arc plasma method. The particle size, microstructure, and morphology of the particles by this process were characterized via X-ray powder diffraction (XRD, transmission electron microscopy (TEM and the corresponding selected area electron diffraction (SAED. The N2 absorption-desorption isotherms of the samples were measured by using the static volumetric absorption analyzer, the pore structure of the sample was calculated by Barrett-Joyner-Halenda (BJH academic model, and the specific surface area was calculated from Brunauer-Emmett-Teller (BET adsorption equation. The experiment results indicate that the crystal structure of the samples is face-centered cubic (FCC structure the same as the bulk materials, the particle size distribution ranging from 5 to 65 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 23.81 m2/g, pore volumes are 0.09 cm3/g, and average pore diameter is 18.7 nm.

  8. Effects of diphenyl diselenide on growth, oxidative damage, and antioxidant response in silver catfish.

    Science.gov (United States)

    Menezes, Charlene; Marins, Aline; Murussi, Camila; Pretto, Alexandra; Leitemperger, Jossiele; Loro, Vania Lucia

    2016-01-15

    The aim of this study was to evaluate the effects of dietary diphenyl diselenide [(PhSe)2] at different concentrations (1.5, 3.0, and 5.0 mg/kg) on growth, oxidative damage and antioxidant parameters in silver catfish after 30 and 60 days. Fish fed with 5.0 mg/kg of (PhSe)2 experienced a significant decrease in weight, length, and condition factor after 30 days and these parameters increased after 60 days. Thiobarbituric acid reactive substances (TBARS) and protein carbonyl (PC) decreased in the liver of silver catfish supplemented with (PhSe)2 after 30 days at all concentrations, while after 60 days these parameters decreased in liver, gills, brain, and muscle. Supplementation with (PhSe)2 induced a decrease in catalase (CAT) activity from liver only after 60 days of feeding. Superoxide dismutase (SOD) decreased at 5.0 mg/kg after 30 and 60 days and glutathione peroxidase (GPx) was enhanced at 1.5 and 3.0 mg/kg after 30 and 60 days. Silver catfish supplemented for 30 days showed a significant increase in liver glutathione S-transferase (GST) at 3.0 mg/kg, while after 60 days GST activity increased in liver at 1.5, 3.0, and 5.0 mg/kg and in gills at 3.0 and 5.0 mg/kg of (PhSe)2. After 30 days, non-protein thiols (NPSH) did not change, while after 60 days NPSH increased in liver, gills, brain, and muscle. In addition, ascorbic acid (AA) levels after 30 days increased in liver at three concentrations and in gills and muscle at 1.5 mg/kg, while after 60 days, AA increased at all concentrations in all and tissues tested. Thus, diet supplemented with (PhSe)2 for 60 days could be more effective for silver catfish. Although the concentration of 5.0 mg/kg showed decreased growth parameters, concentrations of 1.5 and 3.0 mg/kg, in general, decreased oxidative damage and increased antioxidant defenses.

  9. A novel preparation of silver-plated polyacrylonitrile fibers functionalized with antibacterial and electromagnetic shielding properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Li, Weiya; Gao, Cuicui; Tian, Weicheng [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Sun, Bin [College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Yu, Dan, E-mail: yudan@dhu.edu.cn [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China)

    2015-07-01

    Highlights: • We propose a novel modification method to initiate silver electroless plating on PAN fiber without noble metal catalyst. • The silver-plated fiber we fabricated has good electromagnetic shielding effectiveness and antibacterial properties. • The metal layer has good adhesion strength and the properties of the silver-plated fiber can stand 30 cycles of standard washing. - Abstract: Polyacrylonitrile (PAN) fibers with antibacterial, electromagnetic shielding and antistatic functionalities were fabricated in this paper through modifying PAN fibers with (3-aminopropyl)triethoxysilane (APTES) and 3-mercaptopropyltriethoxysilane (MPTES) sequentially and followed with silver electroless plating. The silver layer on PAN fiber surface was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The results show that the silver layer was plated uniformly and compactly. The surface resistance of plated fabric was about 40 mΩ/sq on average. The antibacterial tests demonstrate that silver-plated PAN fiber exhibits excellent antibacterial property against S. aureus and E. coli with a non-leaching characteristic. The antibacterial property remains good after 30 cycles of standard washing, which is a strong proof of a durable adhesion between metal layer and fiber. The shielding effectiveness (SE) of silver-plated PAN fabric before and after 30 cycles of standard washing was about 40–80 dB and 35–50 dB, respectively. This resultant fiber can be used in many occasions for reducing or preventing electromagnetic interference (EMI) and electromagnetic hazards.

  10. Evaluation of oxidative stress induction in rats following exposure to silver nanorods.

    Science.gov (United States)

    Lingabathula, Harikiran; Yellu, Narsimhareddy

    2017-01-25

    The study investigated the oxidative stress induction by the 10 and 25 nm silver nanorods (SNRs) following intra-tracheal instillation in rats after 1 day, 1 week, 1 month and 3 months post instillation periods at 1 and 5 mg/kg b.w. doses. The blood was withdrawn by retro orbital plexus method after exposure periods and different oxidative stress markers were estimated. The results showed that the both sizes of SNRs induced increased levels of malondialdehyde (MDA) and depleted glutathione (GSH) levels after 1 day and 1 week post exposure periods. The 10 and 25 nm SNRs at both doses displayed that significantly reduced levels of superoxide dismutase (SOD) and catalase following 1 day and 1 week post exposure periods. Also, the results have shown that decrease in total antioxidant capacity (TAC) of both sizes of SNRs significantly following 1 day and 1 week post exposure periods, indicating the oxidative stress induction by SNRs. In spite, there were no significant changes in oxidative stress markers following 1 month and 3 months post exposure periods may be due to recovery. The increased levels of MDA and decreased levels of GSH, SOD, catalase and TAC activity are strongly associated to ROS production and lipid peroxidation, suggesting the induction of oxidative stress in rats. The 10 nm SNRs at 5 mg/kg b.w. dose exposures in rats have shown greater changes in all oxidative stress parameters, indicating the greater induction of oxidative stress when compared with the 25 nm SNRs, representing the size-dose-dependent induction of oxidative stress of SNRs.

  11. Preparation of uniform mixed metal oxide and superconductive oxides

    Energy Technology Data Exchange (ETDEWEB)

    Barder, T.J.

    1991-04-30

    This paper describes a method for producing a uniform mixed metal oxide. It includes dissolving metals as their salts of a carboxylic acid in an aliphatic alcohol in the substantial absence of water, the metals are in the same proportions as in the corresponding mixed metal oxide; co-precipitating the metals as their oxalates by mixing the alcohol solution with oxalic acid; separating the co-precipitated metal oxalates and calcining the oxalates in air or oxygen above about 500{degrees} C to convert the oxalates to the corresponding metal oxides.

  12. NANO-STRUCTURED SILVER COATING ON COPPER PREPARED IN AN ETHANOL-BASED SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Zheliang Wei; Dian Tang; Thomas O'Keefe

    2005-01-01

    Recently, silver as an electrochemical deposit on copper substrate has been attracting much attention in the microelectronics field. To deposit nano-scale silver particles on copper, immersion plating using cyanide-based baths is commonly used. In this study, non-toxic ethanol was used as the plating solution. Sputtered copper samples were terized by a field emission scanning electron microscope (FE-SEM), an energy dispersive X-ray spectroscope (EDS),and an atomic force microscope (AFM). It was found that the deposited particles are metallic silver. After 3 s immersion,fine particles whose diameters were around 6 nm had covered about 40% of the surface of the copper substrate. After10 s immersion, the copper surface was completely covered by silver particles, the diameters of which have increased to about 10-15 nm. After the whole surface was covered, a dense and smooth silver coating was obtained.

  13. Preparation and antibacterial property of silver-containing mesoporous 58S bioactive glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hailin; Hu, Chao [Key Laboratory of Fiber Materials and Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Zhang, Fangfang [Zhejiang Provincial Hospital of Traditional Chinese Medicine, Hangzhou 310006 (China); Feng, Xinxing, E-mail: f0712@tom.com [The Quartermaster Research Institute of the General Logistic Department of CPLA, Beijing 100082 (China); Li, Jiuming; Liu, Tao [Key Laboratory of Fiber Materials and Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Chen, Jianyong, E-mail: cjy@zstu.edu.cn [Key Laboratory of Fiber Materials and Processing Technology, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Zhang, Jianchun [The Quartermaster Research Institute of the General Logistic Department of CPLA, Beijing 100082 (China)

    2014-09-01

    The modified mesoporous 58S bioglass (SM58S) was prepared through surface modification of the mesoporous 58S bioglass (M58S) with γ-aminopropyl triethoxysilane (KH550). The results of Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) showed that the amino groups were grafted to the surface of M58S after modification with KH550. The silver-containing SM58S (Ag-SM58S) and M58S (Ag-M58S) were prepared by the dipping method. The Ag{sup +} loading capacity, release rate and antibacterial properties of Ag-SM58S and Ag-M58S were investigated. It is indicated that surface modification of M58S with KH550 can improve the Ag{sup +} loading capacity. The result of antibacterial property showed that Ag-SM58S exhibited significant anti-bacterial effects against Escherichia coli and Staphylococcus aureus. The sustained release of Ag{sup +} from Ag-SM58S for 768 h ensured excellent antibacterial property of Ag-SM58S. In vitro osteoblast proliferation and differentiation tests showed that Ag-SM58S was a good matrix for the growth of osteoblasts. Consequently, the results of the study suggested that Ag-SM58S might be a promising bone repair material. - Highlights: • The amino groups are grafted to the surface of M58S after modification with KH550. • Surface modification of M58S with KH550 can improve the Ag{sup +} loading capacity. • The sustained release of Ag{sup +} from Ag-SM58S ensures good antibacterial property.

  14. Preparación de nanopartículas de plata en ausencia de polimeros estabilizantes Preparation of silver nanoparticles in the absence of polymer stabilizers

    Directory of Open Access Journals (Sweden)

    Ángela B. Sifontes

    2010-01-01

    Full Text Available Silver nanoparticles (AgNPs were prepared by means of the polyol method in the absence of stabilizing polymers. To accomplish this objective, AgNO3 was added to ethylene glycol in the presence of NaOH (1 mol.L-1, the suspension formed was irradiated with a microwave source for 60 seconds at a power of 465 watts. It was found that under these conditions AgNPs of sizes between 4-18 nm are formed. Also the results indicate that part of the ethylene glycol is oxidized to carbonyl compounds that reduce the Ag+. These organic compounds are adsorbed on the surfaces of AgNPs, forming a protective film that prevents their aggregation.

  15. Preparation of NO2-Aged Silver-Functionalized Silica-Aerogel and Silver Mordenite Samples

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Jacob A. [ORNL; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    Reprocessing used nuclear fuel can result in the volatilization of radioactive gaseous species, including 129I, into the various process off-gas streams. In order to comply with US regulatory requirements, plant off-gas streams must be treated to remove the iodine prior to discharging the off-gas into the environment. The performance of available gas removal methods depends not only on the concentration of the volatile radioisotope of interest, but also on other constituents that could be present in the reprocessing off-gas streams. Some of the constituents, such as NOx produced during fuel dissolution, are known to have deleterious effects on the capture performance of silver-based sorbents used for iodine removal. Commercially available reduced silver mordenite (AgZ) has an iodine saturation concentration of 7.0-9.0 wt%, and its iodine sorption capacity is reduced by 20-50% as a result of NO2 aging. Silverfunctionalized silica aerogel (AgAerogel), an alternative for iodine capture, has an initial iodine saturation of 29.0 wt% and its iodine capacity is only reduced by 15% from NO2 aging. Understanding the differences in aging behavior between AgZ and AgAerogel is critical to determining the behavior of these sorbents under realistic off-gas conditions. To assist in future technical studies on this topic, samples of both AgZ and AgAerogel were aged with NO2. In the experiment, 10.2190 g of AgZ and 10.1771 g of AgAerogel were exposed to a static 0.75% NO2/dry air blend for a period of 28 days. The samples were then removed and stored under argon until needed for future experiments.=

  16. Efficient electrochemical water oxidation in neutral and near-neutral systems with a nanoscale silver-oxide catalyst.

    Science.gov (United States)

    Joya, Khurram S; Ahmad, Zahoor; Joya, Yasir F; Garcia-Esparza, Angel T; de Groot, Huub J M

    2016-08-11

    In electrocatalytic water splitting systems pursuing for renewable energy using sunlight, developing robust, stable and easily accessible materials operating under mild chemical conditions is pivotal. We present here a unique nanoparticulate type silver-oxide (AgOx-NP) based robust and highly stable electrocatalyst for efficient water oxidation. The AgOx-NP is generated in situ in a HCO3(-)/CO2 system under benign conditions. Micrographs show that they exhibit a nanoscale box type squared nano-bipyramidal configuration. The oxygen generation is initiated at low overpotential, and a sustained O2 evolution current density of >1.1 mA cm(-2) is achieved during prolonged-period water electrolysis. The AgOx-NP electrocatalyst performs exceptionally well in metal-ion free neutral or near-neutral carbonate, phosphate and borate buffers relative to recently reported Co-oxide and Ni-oxide based heterogeneous electrocatalysts, which are unstable in metal-ion free electrolytes and tend to deactivate with time and lose catalytic performance during long-term experimental tests.

  17. Efficient electrochemical water oxidation in neutral and near-neutral systems by nanoscale silver-oxide catalyst

    KAUST Repository

    Joya, Khurram

    2016-07-19

    In electrocatalytic water splitting systems pursuing for renewable energy using sun light, developing robust, stable and easy accessible materials operating under mild chemical conditions is pivotal. We present here unique nano-particulate type silver-oxide (AgOx-NP) based robust and highly stable electrocatalyst for efficient water oxidation. The AgOx-NP is generated in situ in a HCO3–/CO2 system under benign conditions. Mircographs show that they exhibit nanoscale box type squared nano-bipyramidal configuration. The oxygen generation is initiated at low overpotential, and a sustained O2 evolution current density of > 1.1 mA cm–2 is achieved during prolonged-period water electrolysis. The AgOx-NP electrocatalyst performs exceptionally well in metal-ions free neutral or near-neutral carbonate, phosphate and borate buffers relative to recently reported Co-oxide and Ni-oxide based heterogeneous electrocatalysts, which are unstable in metal-ions free electrolyte and tend to degrade with time and lose catalytic performance during long-term experimental tests.

  18. Oxidation-resistant hybrid metal oxides/metal nanodots/silver nanowires for high performance flexible transparent heaters

    Science.gov (United States)

    Kim, A.-Young; Kim, Min Kyu; Hudaya, Chairul; Park, Ji Hun; Byun, Dongjin; Lim, Jong Choo; Lee, Joong Kee

    2016-02-01

    Despite its excellent optical, electrical, mechanical, and thermal performances, a silver nanowire (AgNW)-based transparent conducting heater (TCH) still demonstrates several drawbacks such as facile nanowire breakdown on application of a high DC voltage, easy oxidation when exposed to harsh environments, leading to increased surface resistivity, and high resistance among wire junctions causing nonhomogeneous temperature profiles. To overcome these issues, the AgNW was hybridized with other transparent heating materials made of fluorine-doped tin oxide (FTO) thin films and NiCr nanodots (FTO/NiCr/AgNW). The dispersed NiCr nanodots (~50 nm) and FTO thin films (~20 nm) electrically bridge the nanowire junctions leading to a decreased sheet resistance and uniform temperature profiles. The hybrid transparent heater shows excellent optical transmittance (>90%) and high saturation temperature (162 °C) at low applied DC voltage (6 V). Moreover, the FTO/NiCr/AgNW heater exhibits a stable sheet resistance in a hostile environment, hence highlighting the excellent oxidation-resistance of the heating materials. These results indicate that the proposed hybrid transparent heaters could be a promising approach to combat the inherent problems associated with AgNW-based transparent heaters for various functional applications.Despite its excellent optical, electrical, mechanical, and thermal performances, a silver nanowire (AgNW)-based transparent conducting heater (TCH) still demonstrates several drawbacks such as facile nanowire breakdown on application of a high DC voltage, easy oxidation when exposed to harsh environments, leading to increased surface resistivity, and high resistance among wire junctions causing nonhomogeneous temperature profiles. To overcome these issues, the AgNW was hybridized with other transparent heating materials made of fluorine-doped tin oxide (FTO) thin films and NiCr nanodots (FTO/NiCr/AgNW). The dispersed NiCr nanodots (~50 nm) and FTO thin films

  19. Method for preparing hydrous iron oxide gels and spherules

    Science.gov (United States)

    Collins, Jack L.; Lauf, Robert J.; Anderson, Kimberly K.

    2003-07-29

    The present invention is directed to methods for preparing hydrous iron oxide spherules, hydrous iron oxide gels such as gel slabs, films, capillary and electrophoresis gels, iron monohydrogen phosphate spherules, hydrous iron oxide spherules having suspendable particles homogeneously embedded within to form composite sorbents and catalysts, iron monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent, iron oxide spherules having suspendable particles homogeneously embedded within to form a composite of hydrous iron oxide fiber materials, iron oxide fiber materials, hydrous iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, dielectric spherules of barium, strontium, and lead ferrites and mixtures thereof, and composite catalytic spherules of barium or strontium ferrite embedded with oxides of Mg, Zn, Pb, Ce and mixtures thereof. These variations of hydrous iron oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters, dielectrics, and ceramics.

  20. Inkjet-Printed Porous Silver Thin Film as a Cathode for a Low-Temperature Solid Oxide Fuel Cell.

    Science.gov (United States)

    Yu, Chen-Chiang; Baek, Jong Dae; Su, Chun-Hao; Fan, Liangdong; Wei, Jun; Liao, Ying-Chih; Su, Pei-Chen

    2016-04-27

    In this work we report a porous silver thin film cathode that was fabricated by a simple inkjet printing process for low-temperature solid oxide fuel cell applications. The electrochemical performance of the inkjet-printed silver cathode was studied at 300-450 °C and was compared with that of silver cathodes that were fabricated by the typical sputtering method. Inkjet-printed silver cathodes showed lower electrochemical impedance due to their porous structure, which facilitated oxygen gaseous diffusion and oxygen surface adsorption-dissociation reactions. A typical sputtered nanoporous silver cathode became essentially dense after the operation and showed high impedance due to a lack of oxygen supply. The results of long-term fuel cell operation show that the cell with an inkjet-printed cathode had a more stable current output for more than 45 h at 400 °C. A porous silver cathode is required for high fuel cell performance, and the simple inkjet printing technique offers an alternative method of fabrication for such a desirable porous structure with the required thermal-morphological stability.

  1. In vitro cardiotoxicity screening of silver and metal oxide nanoparticles using human induced pluripotent stem cell-derived cardiomyocytes

    Science.gov (United States)

    Exposure risk to silver and metal oxide nanoparticles (NPs) continues to increase due to their widespread use in products and applications. In vivo studies have shown Ag, TiO2 and CeO2 NPs translocate to the heart following various routes of exposure. Thus, it is critical to asse...

  2. Selective liquid-phase oxidation of alcohols catalyzed by a silver-based catalyst promoted by the presence of ceria

    DEFF Research Database (Denmark)

    Beier, Matthias Josef; Hansen, Thomas Willum; Grunwaldt, Jan-Dierk

    2009-01-01

    A number of silver catalysts supported on SiO2, Al2O3, Celite, CeO2, kaolin, MgO, and activated carbon were screened for their catalytic activity in the selective liquid-phase oxidation of benzyl alcohol using a special screening approach. For this purpose 5–6 catalyst samples were mixed and tested...

  3. In vitro cardiotoxicity screening of silver and metal oxide nanoparticles using human induced pluripotent stem cell-derived cardiomyocytes

    Science.gov (United States)

    Exposure risk to silver and metal oxide nanoparticles (NPs) continues to increase due to their widespread use in products and applications. In vivo studies have shown Ag, TiO2 and CeO2 NPs translocate to the heart following various routes of exposure. Thus, it is critical to asse...

  4. Comparative hazard identification by a single dose lung exposure of zinc oxide and silver nanomaterials in mice

    NARCIS (Netherlands)

    Gosens, Ilse; Kermanizadeh, Ali; Jacobsen, Nicklas Raun; Lenz, Anke-Gabriele; Bokkers, Bas; de Jong, Wim H; Krystek, Petra; Tran, Lang; Stone, Vicki; Wallin, Håkan; Stoeger, Tobias; Cassee, Flemming R

    2015-01-01

    Comparative hazard identification of nanomaterials (NMs) can aid in the prioritisation for further toxicity testing. Here, we assessed the acute lung, systemic and liver responses in C57BL/6N mice for three NMs to provide a hazard ranking. A silver (Ag), non-functionalised zinc oxide (ZnO) and a tri

  5. Graphene Oxide/Silver Nanohybrid as Multi-functional Material for Highly Efficient Bacterial Disinfection and Detection of Organic Dye

    DEFF Research Database (Denmark)

    Tam, L.T.; Dinh, N. X.; Cuong, N. V.

    2016-01-01

    In this work, a multi-functional hybrid system consisting of graphene oxide and silver nanoparticles (GO-Ag NPs) was successfully synthesized by using a two-step chemical process. We firstly demonstrated noticeable bactericidal ability of the GO-Ag hybrid system. We provide more chemo...

  6. A comparative study of silver-graphene oxide nanocomposites as a recyclable catalyst for the aerobic oxidation of benzyl alcohol: Support effect

    Energy Technology Data Exchange (ETDEWEB)

    Zahed, Bahareh; Hosseini-Monfared, Hassan, E-mail: monfared@znu.ac.ir

    2015-02-15

    Graphical abstract: - Highlights: • Characteristics of three different graphene oxide (GO) are studied as a support for Ag nanoparticles. • The required conditions for a best support are determined. • For the first time the silver nanoparticles decorated GO as catalyst for aerobic oxidation of benzyl alcohol and the effects of the degree of reduction of GO on AgNPs on GO are reported. - Abstract: Three different nanocomposites of silver and graphene oxide, namely silver nanoparticles (AgNPs) immobilized on reduced graphene oxide (AgNPs/rGO), partially reduced graphene oxide (AgNPs/GO) and thiolated partially reduced graphene oxide (AgNPs/GOSH), were synthesized in order to compare their properties. Characterizations were carried out by infrared and UV–Vis and Raman spectroscopy, ICP, X-ray diffraction, SEM and TEM, confirming both the targeted chemical modification and the composite formation. The nanocomposites were successfully employed in the aerobic oxidation of benzyl alcohol at atmospheric pressure. AgNPs/GOSH is stable and recyclable catalyst which showed the highest activity in the aerobic oxidation of benzyl alcohol in the presence of N-hydroxyphthalimide (NHPI) to give benzaldehyde with 58% selectivity in 24 h at 61% conversion. The favorite properties of AgNPs/GOSH are reasonably attributed to the stable and well distributed AgNPs over GOSH due to strong adhesion between AgNPs and GOSH.

  7. Preparation and in-vitro Antibacterial Evaluation of Electroless Silver Coated Polymers.

    Science.gov (United States)

    Fazeli, Mohammad Reza; Hosseini, Vahid; Shamsa, Fazel; Jamalifar, Hossein

    2010-01-01

    Long-term use of indwelling medical catheters has often been hindered by catheter-associated nosocomial infections. In this study the effectiveness of silver coating of polystyrene and polyethylene polymers was investigated. Polymer pieces of 2 cm(2) each were coated with a thin layer of silver using electroless plating technique. Silver-coated polymers were challenged with cultures of four different microorganisms known for their involvement in nosocomial infections in both solid and broth media. The tested bacteria included Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Silver release from the coated polymers was 2-5 μg/cm(2) which was confirmed by chemical and biological methods. The silver coating thickness ranged between 20-450 nm. P. aeruginosa and S. aureus were the most adherent bacteria to polystyrene sheets while E. coli showed minimum adherence effect. The survival rate of different bacteria after 80 min in a time course experiment tended to dominate E. coli as the most sensitive bacteria to the effect of silver with zero survival rate while around 4% of P. aeruginosa were detected after same period. Silver coating of indwelling polymers by electroless technique seems promising in combating nosocomial infections due to long-term catheterization.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tian, E-mail: phdlitian@163.com; Lin, Oulian; Lu, Zhiyuan; He, Liuimei; Wang, Xiaosheng

    2014-06-01

    The Na{sup +} 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.

  9. Synthesis of colloidal silver iron oxide nanoparticles--study of their optical and magnetic behavior.

    Science.gov (United States)

    Kumar, Anil; Singhal, Aditi

    2009-07-22

    Silver iron oxide nanoparticles of fairly small size (average diameter approximately 1 nm) with narrow size distribution have been synthesized by the interaction of colloidal beta- Fe2O3 and silver nanoparticles. The surface morphology and size of these particles have been analyzed by using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Their structural analysis has been carried out by employing x-ray diffraction (XRD), selected-area electron diffraction (SAED), optical and infrared (IR) spectroscopic techniques. The ageing of these particles exhibits the formation of self-assembly, possibly involving weak supramolecular interactions between Ag(I)O4 and Fe(III)O4 species. These particles display the onset of absorption in the near-infrared region and have higher absorption coefficient in the visible range compared to that of its precursors. Magnetic measurements reveal an interesting transition in their magnetic behavior from diamagnetic to superparamagnetic. The magnetic moment of these particles attains a limiting value of about 0.19 emu cm(-2), which is more than two times higher than that of colloidal beta- Fe2O3. With enhanced optical and magnetic properties, this system is suggested to have possible applications in optoelectronic and magnetic devices.

  10. Synthesis of Silver-Doped Zinc Oxide Nanocomposite by Pulse Mode Ultrasonication and Its Characterization Studies

    Directory of Open Access Journals (Sweden)

    T. Siva Vijayakumar

    2013-01-01

    Full Text Available The synthesis of silver-doped zinc oxide (Ag:ZnO nanocomposite material was achieved using a simple chemical coprecipitation method, in which 0.2 M zinc chloride and 0.001 M silver nitrate coprecipitated with 25% ammonia solution by pulse mode dispersion using ultrasonicator. The obtained silvery white precipitate was dried overnight at 110°C in hot air oven, and the powder was collected. The resulted Ag:ZnO nanocomposite was structurally and optically characterized using various techniques. The X-ray diffraction (XRD pattern clearly showed the presence of crystalline Ag:ZnO particles. Further, UV-Vis spectrophotometer and fourier transform infrared spectroscopy (FT-IR results showed the presence of Ag:ZnO nanocomposite at specific wavelengths. The scanning electron microscopy (SEM and transmission electron microscopy (TEM analysis confirm that the synthesized Ag:ZnO nanocomposite material was truncated nanorod in shape and has 48 to 226 nm size in diameter.

  11. Synthesis of supported silver nano-spheres on zinc oxide nanorods for visible light photocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Saoud, Khaled [Virginia Commonwealth University-Qatar, Doha (Qatar); Alsoubaihi, Rola [Virginia Commonwealth University, Richmond, VA (United States); Bensalah, Nasr [Qatar University, Doha (Qatar); Bora, Tanujjal [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al-Khoudh-123 (Oman); Bertino, Massimo [Virginia Commonwealth University, Richmond, VA (United States); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al-Khoudh-123 (Oman)

    2015-03-15

    Highlights: • Synthesis of supported Ag NPs on ZnO nanorods using open vessel microwave reactor. • Use of the Ag/ZnO NPs as an efficient visible light photocatalyst. • Complete degradation of methylene blue in 1 h with 0.5 g/L Ag/ZnO NPs. - Abstract: We report the synthesis of silver (Ag) nano-spheres (NS) supported on zinc oxide (ZnO) nanorods through two step mechanism, using open vessel microwave reactor. Direct reduction of ZnO from zinc nitrates was followed by deposition precipitation of the silver on the ZnO nanorods. The supported Ag/ZnO nanoparticles were then characterized by electron microscopy, X-ray diffraction, FTIR, photoluminescence and UV–vis spectroscopy. The visible light photocatalytic activity of Ag/ZnO system was investigated using a test contaminant, methylene blue (MB). Almost complete removal of MB in about 60 min for doses higher than 0.5 g/L of the Ag/ZnO photocatalyst was achieved. This significant improvement in the photocatalytic efficiency of Ag/ZnO photocatalyst under visible light irradiation can be attributed to the presence of Ag nanoparticles on the ZnO nanoparticles which greatly enhances absorption in the visible range of solar spectrum enabled by surface plasmon resonance effect from Ag nanoparticles.

  12. Green synthesis of silver nanoparticle-reduced graphene oxide using Psidium guajava and its application in SERS for the detection of methylene blue

    Science.gov (United States)

    Chettri, Prajwal; Vendamani, V. S.; Tripathi, Ajay; Singh, Manish Kumar; Pathak, Anand P.; Tiwari, Archana

    2017-06-01

    Here we present the synthesis of reduced graphene oxide and silver nanoparticle-reduced graphene oxide composites using aqueous extract of dry leaves of Psidium guajava by one pot reflux method. Psidium guajava extract simultaneously reduces silver nitrate and graphene oxide in the reaction mixture which is confirmed by various spectroscopic techniques. Variable concentrations of silver nitrate solution are used to obtain reduced graphene oxide with different dosage of silver nanoparticles and the resultant composites are examined using surface enhanced Raman scattering measurements. Considering methylene blue as a probe molecule, it is found that the surface enhanced Raman scattering activity increases with the increase in the dose of silver nanoparticles. Our as-synthesised silver nanoparticle-reduced graphene oxide composite shows remarkable performance in detecting methylene blue with concentration as low as 10-8 M for which the enhancement factor is 4.6 × 105. In addition, we report that the reduced graphene oxide quenches the photoluminescence of methylene blue more efficiently than silver nanoparticle-reduced graphene oxide composite. The charge transfer states have been extracted which are mainly responsible for the quenching processes.

  13. CHARACTERISTIC OF SENSITIVITY OF STAPHYLOCOCCUS AUREUS AND CANDIDA ALBICANS TO ANTIBACTERIAL PREPARATIONS AND COLLOIDAL SILVER

    Directory of Open Access Journals (Sweden)

    I. A. Afonina

    2011-01-01

    Full Text Available Abstract. Constant use of antibiotics leads to reliable increasing of resistance among microorganisms. Using non-toxic concentrations of colloidal silver in combination with antimicrobial agents can reduce using concentrations of antibiotics, kept necessary antimicrobial effect. In case of Staphylococcus aureus bactericidal activity of the complex of colloidal silver with unit concentration of neomycin is bigger than the bactericidal effect of double concentration of the antibiotic. Fungicidal effect of combination of antifungal agents with a solution of the colloidal silver on Candida albicans is equal to fungicidal effect of double concentration of antifungal drugs.

  14. A preliminary study of the electro-oxidation of L-ascorbic acid on polycrystalline silver in alkaline solution

    Science.gov (United States)

    Majari Kasmaee, L.; Gobal, F.

    Electrochemical oxidation of L-ascorbic acid on polycrystalline silver in alkaline aqueous solutions is studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (IS). The anodic electro-oxidation starts at -500 mV versus SCE and shows continued anodic oxidation in the cathodic half cycle in the CV regime signifying slowly oxidizing adsorbates. Diffusion coefficient of ascorbate ion measured under both voltammetric regimes is around 1.4 × 10 -5 cm 2 s -1. Impedance spectroscopy measures the capacitances associated with double layer and adsorption around 50 μF cm -2 and 4 mF cm -2 as well as the adsorption and decomposition resistances (rates).

  15. Preparation of graphene/silver hybrid materials and research of Raman enhanced performance%石墨烯携载无机纳米粒子的制备及拉曼性能研究

    Institute of Scientific and Technical Information of China (English)

    侯永超; 黄林军; 王彦欣; 唐建国; 刘继宪; 王瑶; 焦吉庆; 王薇; 赵运超

    2016-01-01

    Through in-situ composite preparation method,silver nanoparticles were doped in the graphene layers to prepared graphene/silver nano hybrid material.The graphene oxide,reduction of oxide graphene and graphene/silver nano hybrid material were characterized by UV-Vis,FTIR,XRD,TEM and Raman spectrum.The results show that Ag can enhanced the Raman signal of reduced graphene oxide/silver nanocomposites.Then,illustrate this problem combined with TEM.Found the reunite of Ag particle can ease the enhancement effect.%通过原位复合的方法,在石墨烯片层间掺杂纳米银颗粒,制备出石墨烯/银纳米杂化材料(RGO/Ag)。利用紫外吸收光谱、傅里叶红外光谱、透射电子显微镜(TEM)、XRD、拉曼光谱等对氧化石墨烯(GO)、还原氧化石墨烯(RGO)和石墨烯/银纳米杂化材料(RGO/Ag)进行表征。发现复合材料中的银对石墨烯/银材料有拉曼增强作用,结合TEM对这种增强作用进行研究,发现银颗粒的团聚对这种增强作用有减弱作用。

  16. Synthesis and characterization of silver nanoparticle and graphene oxide nanosheet composites as a bactericidal agent for water disinfection.

    Science.gov (United States)

    Bao, Qi; Zhang, Dun; Qi, Peng

    2011-08-15

    Graphene oxide (GO) nanosheets impregnated with silver nanoparticles (Ag NPs) were fabricated by the in situ reduction of adsorbed Ag(+) by hydroquinone (HQ) in a citrate buffer solution. Paper-like Ag NP/GO composite materials were fabricated owing to convenient structure characterization and antibacterial tests. The Ag NP/GO composites were characterized by UV-vis spectra, transmission electron microscope, electron diffraction, Raman spectroscopy, and field emission scanning electron microscope coupled with Energy Dispersive Spectrometer. Antibacterial activity was tested using Escherichia coli and Staphylococcus aureus as model strains of Gram negative and Gram positive bacteria, respectively. The as-prepared composites exhibit stronger antibacterial activity against both. The Ag NP/GO composites performed efficiently in bringing down the count of E. coli from 10(6) cfu/mL to zero with 45 mg/L GO in water. The micron-scale GO nanosheets (lateral size) enable them to be easily deposited on porous ceramic membranes during water filtration; making them a promising biocidal material for water disinfection. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

  17. The synthesis of citrate-modified silver nanoparticles in an aqueous suspension of graphene oxide nanosheets and their antibacterial activity.

    Science.gov (United States)

    Das, Manash R; Sarma, Rupak K; Borah, Sarat Ch; Kumari, Roopa; Saikia, Ratul; Deshmukh, Ashvini B; Shelke, Manjusha V; Sengupta, Pinaki; Szunerits, Sabine; Boukherroub, Rabah

    2013-05-01

    A composite material consisting of silver nanoparticles (Ag NPs) deposited on graphene oxide (GO) nanosheets is prepared by chemical reduction of Ag metal ions by sodium borohydride (NaBH4) in the presence of trisodium citrate acting as a stabilizing agent to prevent agglomeration of the nanoparticles. The synthesized GO/Ag NPs composite was characterized by UV/vis spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM analysis confirmed a high density of Ag NPs on the GO nanosheets with a particle size range of 2-25 nm. The activity of the GO/Ag NPs suspension as an antibacterial agent against Gram positive bacteria Staphylococcus aureus and Bacillus subtilis was investigated. The percentage of the killing bacterial colonies by Ag NPs (without GO) is found to be 96-97% while 100% of killing bacterial colonies is only obtained using GO/Ag NPs suspension. Moreover, it was also observed that leakage of sugars and proteins from the cell wall of both S. aureus and B. subtilis in interaction with GO/Ag NPs suspension is higher compared to Ag NPs (without GO) and GO nanosheets. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Polyaniline silver nanoparticle coffee waste extracted porous graphene oxide nanocomposite structures as novel electrode material for rechargeable batteries

    Science.gov (United States)

    Sundriyal, Poonam; Bhattacharya, Shantanu

    2017-03-01

    The exploration of new and advanced electrode materials are required in electronic and electrical devices for power storage applications. Also, there has been a continuous endeavour to formulate strategies for extraction of high performance electrode materials from naturally obtained waste products. In this work, we have developed an in situ hybrid nanocomposite from coffee waste extracted porous graphene oxide (CEPG), polyaniline (PANI) and silver nanoparticles (Ag) and have found this novel composite to serve as an efficient electrode material for batteries. The successful interaction among the three phases of the nano-composite i.e. CEPG-PANI-Ag have been thoroughly understood through RAMAN, Fourier transform infrared and x-ray diffraction spectroscopy, morphological studies through field emission scanning electron microscope and transmission electron microscope. Thermo-gravimetric analysis of the nano-composite demonstrates higher thermal stability up-to a temperature of 495 °C. Further BET studies through nitrogen adsorption-desorption isotherms confirm the presence of micro/meso and macro-pores in the nanocomposite sample. The cyclic-voltammetry (CV) analysis performed on CEPG-PANI-Ag nanocomposite exhibits a purely faradic behaviour using nickel foam as a current collector thus suggests the prepared nanocomposite as a battery electrode material. The nanocomposite reports a maximum specific capacity of 1428 C g-1 and excellent cyclic stability up-to 5000 cycles.

  19. Nonaqueous preparation of stable silver nano particles dispersions from organic sulfonic acids.

    Directory of Open Access Journals (Sweden)

    Valentina Glushko

    2016-05-01

    Full Text Available The conditions for stable silver nano particles dispersions synthesis from organic sulfonic acids in an anhydrous medium of ethylene glycol and its methyl ester were studied. Ascorbic acid and potassium citrate were used as reducing agents.

  20. Electrospun alginate nanofibres impregnated with silver nanoparticles: Preparation, morphology and antibacterial properties

    CSIR Research Space (South Africa)

    Mokhena, Teboho M

    2017-06-01

    Full Text Available Silver nanoparticles are amongst the most valuable nanoparticles with interesting properties, such as a non-toxic nature and high antibacterial efficiency, making them applicable for tissue scaffold, protective clothing and wound dressing...

  1. Preparation of Silver Nanoparticles and Their Industrial and Biomedical Applications: A Comprehensive Review

    National Research Council Canada - National Science Library

    Haider, Adnan; Kang, Inn-Kyu

    2015-01-01

    ... and biomedical devices, cosmetics, electronics, energy sector, and environmental protection [2-4]. Among inorganic NPs, silver nanoparticles (Ag-NPs or nanosilver), due to its novel chemical, physical, a...

  2. Green synthesis of silver nanoparticles, decorated on graphene oxide nanosheets and their catalytic activity

    Science.gov (United States)

    Sreekanth, T. V. M.; Jung, Min-Ji; Eom, In-Yong

    2016-01-01

    In this study, we develop an inexpensive and green route for the synthesis of silver nanoparticles (AgNPs) using Picrasma quassioides bark aqueous extract as reducing and capping agent and also eco-friendly decorate graphene oxide (GO) nanosheets with AgNPs (GO-AgNPs). Green synthesized AgNPs and GO-AgNPs composites were characterized by UV-Visible spectroscopy, SEM-EDX, and TEM-SAED techniques. The resulting GO-AgNPs contained about 41.35% of Ag and the AgNPs size ranges 17.5-66.5 nm, and GO-AgNPs size ranges 10-49.5 nm. Moreover, the GO-AgNPs exhibited excellent catalytic activity towards the methylene blue (MB) in the presence of sodium borohydride (NaBH4) at room temperature. This catalytic reaction completed within 15 min.

  3. Controlled Deposition of Tin Oxide and Silver Nanoparticles Using Microcontact Printing

    Directory of Open Access Journals (Sweden)

    Joo C. Chan

    2015-02-01

    Full Text Available This report describes extensive studies of deposition processes involving tin oxide (SnOx nanoparticles on smooth glass surfaces. We demonstrate the use of smooth films of these nanoparticles as a platform for spatially-selective electroless deposition of silver by soft lithographic stamping. The edge and height roughness of the depositing metallic films are 100 nm and 20 nm, respectively, controlled by the intrinsic size of the nanoparticles. Mixtures of alcohols as capping agents provide further control over the size and shape of nanoparticles clusters. The distribution of cluster heights obtained by atomic force microscopy (AFM is modeled through a modified heterogeneous nucleation theory as well as Oswald ripening. The thermodynamic modeling of the wetting properties of nanoparticles aggregates provides insight into their mechanism of formation and how their properties might be further exploited in wide-ranging applications.

  4. Histopathological studies and oxidative stress of synthesized silver nanoparticles in Mozambique tilapia (Oreochromis mossambicus)

    Institute of Scientific and Technical Information of China (English)

    Rajakumar Govindasamy; Abdul Abdul Rahuman

    2012-01-01

    To evaluate the potential environmental effects of engineered nano metals,it is important to determine the adverse effects of various nanomaterials on aquatic species.Adult tilapia (Oreochromis mossambicus) were maintained in 10 L glass aquaria,and exposed to a graded series of synthesized silver nanoparticles (Ag-NPs) at 25,50 and 75 mg/L for eight days.The LC50 value was 12.6 mg/L.Reduced activities of antioxidant enzymes and the contents of antioxidants were lowered in the gills and liver of fishes treated with Ag-NPs,which resulted in heavy accumulation of free radicals.Histopathological results imply that the balance between the oxidative and antioxidant system in the fish was broken down during Ag-NPs exposure.The principal coneern related with the release of nanomaterials and their smaller particle may change the materials transport and potential toxicity to aquatic organisms compared to larger particles.

  5. Structural and Optical Properties of Chemical Bath Deposited Silver Oxide Thin Films: Role of Deposition Time

    Directory of Open Access Journals (Sweden)

    A. C. Nwanya

    2013-01-01

    Full Text Available Silver oxide thin films were deposited on glass substrates at a temperature of 50°C by chemical bath deposition technique under different deposition times using pure AgNO3 precursor and triethanolamine as the complexing agent. The chemical analysis based on EDX technique shows the presence of Ag and O at the appropriate energy levels. The morphological features obtained from SEM showed that the AgxO structures varied as the deposition time changes. The X-ray diffraction showed the peaks of Ag2O and AgO in the structure. The direct band gap and the refractive index increased as the deposition time increased and was in the range of 1.64–1.95 eV and 1.02–2.07, respectively. The values of the band gap and refractive index obtained indicate possible applications in photovoltaic and photothermal systems.

  6. Synthesis of silver nanoparticles in an aqueous suspension of graphene oxide sheets and its antimicrobial activity.

    Science.gov (United States)

    Das, Manash R; Sarma, Rupak K; Saikia, Ratul; Kale, Vinayak S; Shelke, Manjusha V; Sengupta, Pinaki

    2011-03-01

    A solution-based approach to the synthesis of silver (Ag) nanoparticles by chemical reduction of AgNO(3) in a graphene oxide (GrO) suspension is demonstrated. X-ray diffraction and transmission electron microscopy indicate that the Ag nanoparticles, of size range 5-25nm, were decorated on the GrO sheets. The size and shape of the Ag nanoparticles are dependent on the concentration of the AgNO(3) solution. Antimicrobial activity of such hybrids materials is investigated against the Gram negative bacteria Escherichia coli and Pseudomonous aeruginosa. The bacterial growth kinetics was monitored in nutrient broth supplemented with the Ag nanoparticle-GrO suspension at different conditions. It was observed that P. aeruginosa is comparatively more sensitive to the Ag nanoparticle-GrO suspension. 2010 Elsevier B.V. All rights reserved.

  7. CHARACTERISTIC OF SENSITIVITY OF STAPHYLOCOCCUS AUREUS AND CANDIDA ALBICANS TO ANTIBACTERIAL PREPARATIONS AND COLLOIDAL SILVER

    OpenAIRE

    Afonina, I A; L. A. Kraeva; G. Y. Tseneva

    2011-01-01

    Abstract. Constant use of antibiotics leads to reliable increasing of resistance among microorganisms. Using non-toxic concentrations of colloidal silver in combination with antimicrobial agents can reduce using concentrations of antibiotics, kept necessary antimicrobial effect. In case of Staphylococcus aureus bactericidal activity of the complex of colloidal silver with unit concentration of neomycin is bigger than the bactericidal effect of double concentration of the antibiotic. Fungicida...

  8. Fabrication of highly catalytic silver nanoclusters/graphene oxide nanocomposite as nanotag for sensitive electrochemical immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiamian; Wang, Xiuyun; Wu, Shuo, E-mail: wushuo@dlut.edu.cn; Song, Jie; Zhao, Yanqiu; Ge, Yanqiu; Meng, Changgong

    2016-02-04

    Silver nanoclusters and graphene oxide nanocomposite (AgNCs/GRO) is synthesized and functionalized with detection antibody for highly sensitive electrochemical sensing of carcinoembryonic antigen (CEA), a model tumor marker involved in many cancers. AgNCs with large surface area and abundant amount of low-coordinated sites are synthesized with DNA as template and exhibit high catalytic activity towards the electrochemical reduction of H{sub 2}O{sub 2}. GRO is employed to assemble with AgNCs because it has large specific surface area, super electronic conductivity and strong π-π stacking interaction with the hydrophobic bases of DNA, which can further improve the catalytic ability of the AgNCs. Using AgNCs/GRO as signal amplification tag, an enzyme-free electrochemical immunosensing protocol is designed for the highly sensitive detection of CEA on the capture antibody functionalized immunosensing interface. Under optimal conditions, the designed immunosensor exhibits a wide linear range from 0.1 pg mL{sup −1} to 100 ng mL{sup −1} and a low limit of detection of 0.037 pg mL{sup −1}. Practical sample analysis reveals the sensor has good accuracy and reproducibility, indicating the great application prospective of the AgNCs/GRO in fabricating highly sensitive immunosensors, which can be extended to the detection of various kinds of low abundance disease related proteins. - Highlights: • An enzyme-free electrochemical immunosensor is reported for detecting proteins. • A silver nanocluster/graphene oxide composite is synthesized as nanotag. • The nanotags exhibit highly catalytic activity to the electro-reduction of H{sub 2}O{sub 2}. • The as-fabricated immunosensor could detect protein in serum samples.

  9. Apoptosis inducing ability of silver decorated highly reduced graphene oxide nanocomposites in A549 lung cancer

    Directory of Open Access Journals (Sweden)

    Khan M

    2016-03-01

    Full Text Available Merajuddin Khan,1 Mujeeb Khan,1 Abdulhadi H Al-Marri,1 Abdulrahman Al-Warthan,1 Hamad Z Alkhathlan,1 Mohammed Rafiq H Siddiqui,1 Vadithe Lakshma Nayak,2 Ahmed Kamal,2 Syed F Adil1 1Department of Chemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; 2Department of Medicinal Chemistry and Pharmacology, CSIR – Indian Institute of Chemical Technology, Hyderabad, India Abstract: Recently, graphene and graphene-based materials have been increasingly used for various biological applications due to their extraordinary physicochemical properties. Here, we demonstrate the anticancer properties and apoptosis-inducing ability of silver doped highly reduced graphene oxide nanocomposites synthesized by employing green approach. These nano­composites (PGE-HRG-Ag were synthesized by using Pulicaria glutinosa extract (PGE as a reducing agent and were evaluated for their anticancer properties against various human cancer cell lines with tamoxifen as the reference drug. A correlation between the amount of Ag nanoparticles on the surface of highly reduced graphene oxide (HRG and the anticancer activity of nanocomposite was observed, wherein an increase in the concentration of Ag nanoparticles on the surface of HRG led to the enhanced anticancer activity of the nanocomposite. The nanocomposite PGE-HRG-Ag-2 exhibited more potent cytotoxicity than standard drug in A549 cells, a human lung cancer cell line. A detailed investigation was undertaken and Fluorescence activated cell sorting (FACS analysis demonstrated that the nanocomposite PGE-HRG-Ag-2 showed G0/G1 phase cell cycle arrest and induced apoptosis in A549 cells. Studies such as, measurement of mitochondrial membrane potential, generation of reactive oxygen species (ROS and Annexin V-FITC staining assay suggested that this compound induced apoptosis in human lung cancer cells. Keywords: plant extract, graphene/silver nanocomposites, anticancer, apoptosis

  10. Preparation and characterization of chitosan-silver nanocomposite films and their antibacterial activity against Staphylococcus aureus

    Science.gov (United States)

    Regiel, Anna; Irusta, Silvia; Kyzioł, Agnieszka; Arruebo, Manuel; Santamaria, Jesus

    2013-01-01

    In this work different variables have been analyzed in order to optimize the bactericidal properties of chitosan films loaded with silver nanoparticles. The goal was to achieve complete elimination of antibiotic resistant and biofilm forming strains of Staphylococcus aureus after short contact times. The films were produced by solution casting using chitosan as both a stabilizing and reducing agent for the in situ synthesis of embedded silver nanoparticles. We have applied an innovative approach: the influence of the chitosan molecular weight and its deacetylation degree (DD) were analyzed together with the influence of the bacterial concentration and contact time. The best results were obtained with high DD chitosan where a fast reduction was favored; leading to smaller nanoparticles (nucleation is promoted), and a sufficiently high polymer viscosity prevented the resulting nanoparticles from undesired agglomeration. In addition, for the first time, potential detachment of the silver nanoparticles from the films was evaluated and neglected, demonstrating that uncontrolled release of silver nanoparticles from the chitosan films is prevented. The influence of the ionic silver released from the films, silver loading, nanoparticle sizes, contact, and initial number of bacteria was also analyzed to elucidate the mechanism responsible for the strong bactericidal action observed.

  11. Preparation of carbon microspheres decorated with silver nanoparticles and their ability to remove dyes from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qingchun [Department of Chemistry, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Wu, Qingsheng, E-mail: qswu@tongji.edu.cn [Department of Chemistry, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China)

    2015-02-11

    Highlights: • Carbon microspheres decorated with silver nanoparticles (AgNP-CMSs) were prepared. • AgNP-CMSs show not only rapid and high adsorption capacity to methylene blue (MB) in water, but also excellent reusability. • It exhibits photocatalytic activity to Rhodamine B as well as MB under visible light. • The adsorption is from the ionic interactions but not the π–π conjugations. • The origin of photocatalysis is a surface plasmon resonance effect of AgNP on CMSs. - Abstract: Solid, but not hollow or porous, carbon microspheres decorated with silver nanoparticles (AgNP-CMSs) were prepared from silver nitrate and CMSs by a redox reaction at room temperature. The CMSs and AgNP-CMSs were characterized using X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and UV–vis spectrophotometry. Though with non-high specific surface area, the AgNP-CMSs exhibited a high adsorption capacity toward methylene blue (MB) in an aqueous solution. The AgNP-CMSs were able to remove all the MB from a solution of 30 mg/L MB in water within 1 min when the adsorbent concentration was 0.12 g/L. The AgNP-CMSs also exhibited good adsorption and photocatalytic activity in the decomposition of aqueous Rhodamine B as well as MB under visible light. FTIR was used to examine the interaction between AgNP-CMSs and MB, and the spectrum and more extra experiments suggest ionic interactions between cationic dyes and the negatively charged groups can be formed but not the presence of abundant π–π conjugations between dye molecules and the aromatic rings. The origin of the photocatalytic activity of AgNP-CMSs was attributed to a surface plasmon resonance (SPR) effect of the silver nanoparticles on the CMSs.

  12. Lipid oxidation in omega-3 emulsions prepared with milk proteins

    DEFF Research Database (Denmark)

    Horn, Anna Frisenfeldt; Nielsen, Nina Skall; Andersen, Ulf

    components. In these three studies different parameters that are expected to change the properties and structure of the proteins at the interface were investigated. The first study compares 70% emulsions with either sodium caseinate or whey protein isolate at two pH values with and without iron addition....... The properties of the emulsifier used and the structure at the interface are therefore expected to be of great importance for oxidation in emulsions. This presentation will include results from mainly three different studies of lipid oxidation in omega-3 emulsions prepared with milk proteins and protein....... The second study evaluates the effect of two different high pressure homogenizers on oxidation in 10% emulsions with the same emulsifiers as in the first study. Finally, the third study considers the effect of changing pH on oxidation in emulsions prepared with different whey protein components. Results...

  13. Cytotoxicity of Silver Nanoparticle and Chitin-Nanofiber Sheet Composites Caused by Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Jun Kinoda

    2016-10-01

    Full Text Available Size-controlled spherical silver nanoparticles (<10 nm and chitin-nanofiber sheet composites (Ag NPs/CNFS have previously been reported to have strong antimicrobial activity in vitro. Although Ag NPs/CNFS have strong antimicrobial activity, their cytotoxicity has not been investigated. This study was performed to evaluate the effects of Ag NPs/CNFS on cytotoxicity for fibroblasts in vitro and healing delay of wound repair in vivo, focused on oxidative stress. Cytotoxic activities of Ag NPs/CNFS were investigated using a fibroblast cell proliferation assay, nitric oxide/nitrogen dioxide (NO/NO2 measurement of the cell lysates in vitro, inhibitory effects of Ag NPs/CNFS on healing-impaired wound repair using diabetic mice in vivo, 8-hydroxy-2′-deoxyguanosine (8-OHdG immunohistochemical staining of the skin sections, and generation of carbonyl protein in the wound was performed to evaluate cytotoxicity with oxidative stress. Ag NPs/CNFS exhibited cytotoxicity for fibroblasts and a significant increase of total NO/NO2 levels in the cell lysates in vitro and increased levels of 8-OHdG and carbonyl proteins in vivo. Although wound repair in the continuously Ag NPs/CNFS-treated group was delayed, it could be mitigated by washing the covered wound with saline. Thus, Ag NPs/CNFS may become accepted as an anti-infectious wound dressing.

  14. Reactivity control of C-H bond activation over vanadium-silver bimetallic oxide cluster cations.

    Science.gov (United States)

    Li, Xiao-Na; Wu, Xiao-Nan; Ding, Xun-Lei; Xu, Bo; He, Sheng-Gui

    2012-08-27

    Vanadium-silver bimetallic oxide cluster ions (V(x)Ag(y)O(z)(+); x=1-4, y=1-4, z=3-11) are produced by laser ablation and reacted with ethane in a fast-flow reactor. A reflectron time of flight (Re-TOF) mass spectrometer is used to detect the cluster distribution before and after the reactions. Hydrogen atom abstraction (HAA) reactions are identified over VAgO(3)(+), V(2)Ag(2)O(6)(+), V(2)Ag(4)O(7)(+), V(3)AgO(8)(+), V(3)Ag(3)O(9)(+), and V(4)Ag(2)O(11)(+) ions, in which the oxygen-centered radicals terminally bonded on V atoms are active sites for the facile HAA reactions. DFT calculations are performed to study the structures, bonding, and reactivity. The reaction mechanisms of V(2)Ag(2)O(6)(+) +C(2)H(6) are also given. The doped Ag atoms with a valence state of +1 are highly dispersed at the periphery of the V(x)Ag(y)O(z)(+) cluster ions. The reactivity can be well-tuned gradually by controlling the number of Ag atoms. The steric protection due to the peripherally bonded Ag atoms greatly enhances the selectivity of the V-Ag bimetallic oxide clusters with respect to the corresponding pure vanadium oxide systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Preparation and study of properties of dispersed graphene oxide

    Directory of Open Access Journals (Sweden)

    Evgeniya Seliverstova

    2015-09-01

    Full Text Available Ability of graphene oxide to form stable dispersion in organic solvents was studied in this work. As it was shown, sonication of graphene leads to the decreas of the particle size. Stability of prepared graphene dispersions was studied upon measurements of distribution of number of the particles via size and change of optical density of the solutions with time. It was found that graphene oxide forms a more stable dispersion in tetrahydrofuran and dimethylformamide than in chloroform and acetone.

  16. Methods of preparing deposits containing iron oxides for recycling

    Directory of Open Access Journals (Sweden)

    T. Lis

    2013-04-01

    Full Text Available The metallurgical industry is one of the largest sources of wastes. Some of them, however, owing to their content of metals such as zinc or iron, may become valuable secondary raw materials. In order to achieve that purpose, they require appropriate preparation. This article provides a discussion on the methods of preparation of scrap from steelworks, namely deposits containing iron oxides, enabling their recycling.

  17. Preparation of Reduced Graphene Oxides as Electrode Materials for Supercapacitors

    KAUST Repository

    Bai, Yaocai

    2012-06-01

    Reduced graphene oxide as outstanding candidate electrode material for supercapacitor has been investigated. This thesis includes two topics. One is that three kinds of reduced graphene oxides were prepared by hydrothermal reduction under different pH conditions. The pH values were found to have great influence on the reduction of graphene oxides. Acidic and neutral media yielded reduced graphene oxides with more oxygen-functional groups, lower specific surface areas but broader pore size distributions than those in basic medium. Variations induced by the pH changes resulted in great differences in the supercapacitor performance. The graphene produced in the basic solution presented mainly electric double layer behavior with specific capacitance of 185 F/g, while the other two showed additional pseudocapacitance behavior with specific capacitance of 225 F/g (acidic) and 230 F/g (neutral), all at a constant current density of 1A/g. The other one is that different reduced graphene oxides were prepared via solution based hydrazine reduction, low temperature thermal reduction, and hydrothermal reduction. The as- prepared samples were then investigated by UV-vis spectroscopy, X-ray diffraction, Raman spectroscopy, and Scanning electron microscope. The supercapacitor performances were also studied and the hydrothermally reduced graphene oxide exhibited the highest specific capacitance.

  18. Catalytic systems of cumene oxidation based on multiwalled carbon nanotubes

    Science.gov (United States)

    Kobotaeva, N. S.; Skorokhodova, T. S.; Ryabova, N. V.

    2015-03-01

    Catalytic systems for cumene oxidation were prepared on the basis of silver-activated carbon nanotubes. Silver lies on the surface of the carbon nanotubes in the nanocrystalline state and has a size of 15-20 nm. The use of the obtained catalytic systems in cumene oxidation with molecular oxygen allowed a considerable decrease in the oxidation temperature and an increase in selectivity.

  19. Preparation of polyvinylidene fluoride nanofiber membrane and its antibacterial characteristics with nanosilver or graphene oxide.

    Science.gov (United States)

    Hong, Byungpyo; Jung, Hyemin; Byun, Hongsik

    2013-09-01

    Polyvinylidene fluoride (PVdF) (Kynar 761) nanofibers were prepared by electrospinning at an external voltage of 6-10 kV, a traveling distance of 7-15 cm and flow rate of 0.4-1 ml/hr. Although the diameter of the fiber was not significantly changed, the electrospinning conditions affected the overall distribution of diameter. This is probably due to the interactions, both attraction and repulsion, of positive charges on polymer solutions and the electrically grounded collector. Especially, the effect of voltage on the distribution of diameter was investigated in this study. The final PVdF nanofiber membrane showed narrow pore-size distribution and high water flux compared with the commercial MF membrane. PVdF nanofiber membranes incorporated nanosilver or graphene oxide were also prepared as nanosilver and graphene have an antibacterial activity. It was found that more than 200 ppm of silver nanoparticles in the PVdF nanofiber had 99.9% of growth inhibition of Staphylococcus aureus and Klebsiella pneumonia. It was also found that 0.2 wt% of graphene oxide in the PVdF electrospinning solution had 99.6% of disinfection property to E-Coli.

  20. Promotion of Oxygen Reduction by Exsolved Silver Nanoparticles on a Perovskite Scaffold for Low-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Zhu, Yinlong; Zhou, Wei; Ran, Ran; Chen, Yubo; Shao, Zongping; Liu, Meilin

    2016-01-13

    Solid oxide fuel cells (SOFCs) have potential to be the cleanest and most efficient electrochemical energy conversion devices with excellent fuel flexibility. To make SOFC systems more durable and economically competitive, however, the operation temperature must be significantly reduced, which depends sensitively on the development of highly active electrocatalysts for oxygen reduction reaction (ORR) at low temperatures. Here we report a novel silver nanoparticle-decorated perovskite oxide, prepared via a facile exsolution process from a Sr0.95Ag0.05Nb0.1Co0.9O3-δ (SANC) perovskite precursor, as a highly active and robust ORR electrocatalyst for low-temperature SOFCs. The exsolved Sr0.95Ag0.05Nb0.1Co0.9O3-δ (denoted as e-SANC) electrode is very active for ORR, achieving a very low area specific resistance (∼0.214 Ω cm(2) at 500 °C). An anode-supported cell with the new heterostructured cathode demonstrates very high peak power density (1116 mW cm(-2) at 500 °C) and stable operation for 140 h at a current density of 625 mA cm(-2). The superior ORR activity and stability are attributed to the fast oxygen surface exchange kinetics and the firm adhesion of the Ag nanoparticles to the Sr0.95Nb0.1Co0.9O3-δ (SNC0.95) support. Moreover, the e-SANC cathode displays improved tolerance to CO2. These unique features make the new heterostructured material a highly promising cathode for low-temperature SOFCs.

  1. Amelioration Studies on Optimization of Low Molecular Weight Chitosan Nanoparticle Preparation, Characterization With Potassium Per Sulphate and Silver Nitrate Combined Action With Aid of Drug Delivery to Tetracycline Resistant Bacteria

    Directory of Open Access Journals (Sweden)

    Dipankar Ghosh

    2010-10-01

    Full Text Available Low molecular weight chitosan nanoparticles were prepared by ionotropic gelation of depolymerised chitosan for effective drug delivery in drug resistant bacteria. Depolymerisation reaction was performed by potassium persulfate oxidation at an optimized condition in presence of silver nitrate. Optimized condition for depolymerisation was anticipated at 37°C, pH 4, 2 days reaction time and 0.05 M concentration of potassium per sulphate with 1 mM silver nitrate in final reaction mixture. Chemical characteristics of depolymerised chitosan and low molecular weight chitosan nanoparticles were analyzed by gel permeation chromatography, nuclear magnetic resonance, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Drug loading efficiency and drug releasing efficiency were also studied. Finally, antimicrobial activity of tetracycline loaded low molecular chitosan nanoparticles was determined in terms of minimal inhibitory concentration and putative mode of action on tetracycline resistant bacteria Escherichia coli XL-1 Blue.

  2. Artificial Intelligence in Numerical Modeling of Silver Nanoparticles Prepared in Montmorillonite Interlayer Space

    Directory of Open Access Journals (Sweden)

    Parvaneh Shabanzadeh

    2013-01-01

    Full Text Available Artificial neural network (ANN models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the casting methods. An understanding of the interrelationships between input variables is essential for interpreting the sensitivity data and optimizing the design parameters. Silver nanoparticles (Ag-NPs have attracted considerable attention for chemical, physical, and medical applications due to their exceptional properties. The nanocrystal silver was synthesized into an interlamellar space of montmorillonite by using the chemical reduction technique. The method has an advantage of size control which is essential in nanometals synthesis. Silver nanoparticles with nanosize and devoid of aggregation are favorable for several properties. In this investigation, the accuracy of artificial neural network training algorithm was applied in studying the effects of different parameters on the particles, including the AgNO3 concentration, reaction temperature, UV-visible wavelength, and montmorillonite (MMT d-spacing on the prediction of size of silver nanoparticles. Analysis of the variance showed that the AgNO3 concentration and temperature were the most significant factors affecting the size of silver nanoparticles. Using the best performing artificial neural network, the optimum conditions predicted were a concentration of AgNO3 of 1.0 (M, MMT d-spacing of 1.27 nm, reaction temperature of 27°C, and wavelength of 397.50 nm.

  3. Preparation of titanium dioxide/silver sulfate powder and its antibacterial activity

    Institute of Scientific and Technical Information of China (English)

    PENG Bing; YUAN Chun; CHAI Li-yuan; WEI Shun-wen; YU Yan-fen; SU Wei-feng

    2005-01-01

    Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2 SO4. The granularity of the particles increases from 10.7 nm to 28.7 nm with the temperature of heat-treatment increasing from 300 ℃ to 800 ℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents (MiCs). When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0× 10-4- 1.5 × 10-4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500 ℃. But when the temperature is beyond 600 ℃ the MiCs increase quickly, which shows the inferior antibacterial performance.

  4. A novel preparation of silver-plated polyacrylonitrile fibers functionalized with antibacterial and electromagnetic shielding properties

    Science.gov (United States)

    Wang, Wei; Li, Weiya; Gao, Cuicui; Tian, Weicheng; Sun, Bin; Yu, Dan

    2015-07-01

    Polyacrylonitrile (PAN) fibers with antibacterial, electromagnetic shielding and antistatic functionalities were fabricated in this paper through modifying PAN fibers with (3-aminopropyl)triethoxysilane (APTES) and 3-mercaptopropyltriethoxysilane (MPTES) sequentially and followed with silver electroless plating. The silver layer on PAN fiber surface was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The results show that the silver layer was plated uniformly and compactly. The surface resistance of plated fabric was about 40 mΩ/sq on average. The antibacterial tests demonstrate that silver-plated PAN fiber exhibits excellent antibacterial property against S. aureus and E. coli with a non-leaching characteristic. The antibacterial property remains good after 30 cycles of standard washing, which is a strong proof of a durable adhesion between metal layer and fiber. The shielding effectiveness (SE) of silver-plated PAN fabric before and after 30 cycles of standard washing was about 40-80 dB and 35-50 dB, respectively. This resultant fiber can be used in many occasions for reducing or preventing electromagnetic interference (EMI) and electromagnetic hazards.

  5. Preparation and Anti-oxidative Effects of Corn Peptides

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Corn peptides(CP) were prepared from zein via proteolysis by means of a type of alkaline protease, Alcalase, at 50 ℃ and pH 8.0. The anti-oxidative activity of the hydrolysate was examined. It was found that the anti-oxidative activity reached the maximum at the fourth hour of the hydrolysis and then decreased. The effect of the enzyme dosage on the solubility of corn protein, the dependence of hydrolysis time on the degree of the hydrolysis(DH) and molecular weight distribution were examined respectively. 30% DH was controlled on the basis of anti-oxidative activity. The hydrolysate was fractionated on a Sephadex G-15 column. The anti-oxidative activities were examined for all the fractions. The main fraction for anti-oxidative activity was collected and characterized by the methods of amino acid analysis, the measurement of average chain length and etc.. The main MW distribution of the main fraction was 300-600 Daltons. The anti-oxidative properties of the small peptides in vitro were studied. It was found that they could inhibit the auto-oxidation of pyrogallol and the oxidation of hemoglobin. The hemolysis degree of erythrocyte caused by hydroxyl free radicals was decreased greatly, indicating a protective effect of the anti-oxidative peptides on the cell membrane damage of erythrocyte.

  6. Preparation of carbon microspheres decorated with silver nanoparticles and their ability to remove dyes from aqueous solution.

    Science.gov (United States)

    Chen, Qingchun; Wu, Qingsheng

    2015-01-01

    Solid, but not hollow or porous, carbon microspheres decorated with silver nanoparticles (AgNP-CMSs) were prepared from silver nitrate and CMSs by a redox reaction at room temperature. The CMSs and AgNP-CMSs were characterized using X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and UV-vis spectrophotometry. Though with non-high specific surface area, the AgNP-CMSs exhibited a high adsorption capacity toward methylene blue (MB) in an aqueous solution. The AgNP-CMSs were able to remove all the MB from a solution of 30 mg/L MB in water within 1 min when the adsorbent concentration was 0.12 g/L. The AgNP-CMSs also exhibited good adsorption and photocatalytic activity in the decomposition of aqueous Rhodamine B as well as MB under visible light. FTIR was used to examine the interaction between AgNP-CMSs and MB, and the spectrum and more extra experiments suggest ionic interactions between cationic dyes and the negatively charged groups can be formed but not the presence of abundant π-π conjugations between dye molecules and the aromatic rings. The origin of the photocatalytic activity of AgNP-CMSs was attributed to a surface plasmon resonance (SPR) effect of the silver nanoparticles on the CMSs.

  7. PEDOT:PSS incorporated silver nanoparticles prepared by gamma radiation for the application in organic solar cells

    Directory of Open Access Journals (Sweden)

    Omayma A. Ghazy

    2015-04-01

    Full Text Available Poly(3,4-ethylenedioxythiophene:Polystyrene sulfonate (PEDOT:PSS is a dispersion used as a buffer layer on the ITO electrode in the organic solar cells. Silver nanoparticles (Ag NPs are incorporated to the dispersion using two different strategies. The first is by reduction of silver ions in the PEDOT:PSS dispersion. Chemical reduction of silver ions using sodium borohydried is compared with reduction using gamma radiation. The TEM and UV-visible spectra indicates that smaller Ag NPs are obtained for the chemical reduction method than those obtained from the radiochemical. The second strategy, is by preparing Ag NPs in polyvinyl pyrolidone (PVP solution using gamma irradiation then adding them to the PEDOT:PSS dispersion. Layers of the PEDOT:PSS incorporated different concentrations of Ag NPs (1, 2, 4, 6, 8, 10% are formed. The SEM and AFM studies of the layers morphology reveal that smooth morphology on the obtained for layers containing Ag NPs up to concentrations of 4%.

  8. Graphene Functionalization by 1,6-Diaminohexane and Silver Nanoparticles for Water Disinfection

    National Research Council Canada - National Science Library

    Abdelhalim, Abdelsattar O. E; Galal, Ahmed; Hussein, Mohamed Z; El Sayed, Ibrahim E.-T

    2016-01-01

      Reduced graphene (G) was prepared by chemically reducing graphene oxide (GO). For the first time, the resulting G was functionalized by 1,6-diaminohexane and decorated with silver nanoparticles (AgNPs...

  9. Preparation of Dispersion-Hardened Copper by Internal Oxidation

    DEFF Research Database (Denmark)

    Brøndsted, Povl; Sørensen, Ole Toft

    1978-01-01

    Internal oxidation experiments in CO2/CO atmospheres on Cu-Al alloys for preparation of dispersion-hardened Cu are described. The oxygen pressures of the atmospheres used in the experiments were controlled with a solid electrolyte oxygen cell based on ZrO2 (CaO). The particle size distributions...

  10. PREPARATION OF NICKEL - COBALT SPINEL OXIDES NixCO3 ...

    African Journals Online (AJOL)

    The chemical synthesis of NixCo3-xO4 (0 ≤ x ≤ 2.5) was realised by two sol-gel routes ( ... The amounts used to prepare the mixed oxide are given in ... added in 10 mL of glycol ethylene where were dissolved previously 10 g of citric acid.

  11. Brush-Painting and Photonic Sintering of Copper Oxide and Silver Inks on Wood and Cardboard Substrates to Form Antennas for UHF RFID Tags

    National Research Council Canada - National Science Library

    Sipilä, Erja; Virkki, Johanna; Wang, Jianhua; Sydänheimo, Lauri; Ukkonen, Leena

    2016-01-01

    .... We demonstrate a novel brush-painting method for depositing copper oxide and silver inks directly on wood and cardboard substrates and discuss the optimization of the photonic sintering process...

  12. Oxidative stability during frozen storage of fillets from silver catfish (Rhamdia quelen ) sedated with the essential oil of Aloysia triphylla during transport

    National Research Council Canada - National Science Library

    Daniel, Ana Paula; Ferreira, Lauren Fresinghelli; Klein, Bruna; Ruviaro, Amanda Roggia; Quatrin, Andréia; Parodi, Thaylise Vey; Zeppenfeld, Carla Cristina; Heinzmann, Berta Maria; Baldisserotto, Bernardo; Emanuelli, Tatiana

    2016-01-01

    This research aimed to evaluate whether the essential oil of Aloysia triphylla (EOAT) used in vivo as a sedative in the water for transporting fish could increase the oxidative stability of silver catfish...

  13. 超细颗粒卤化银的制备与稳定性%PREPARATION OF ULTRA-FINE SILVER HALIDE PARTICLES AND THEIR STABILITY

    Institute of Scientific and Technical Information of China (English)

    崔兴品; 岳军

    1999-01-01

    With gelatin or gelatin+PVA as colloid protective medium and under proper reactive condition, ultra-fine silver iodobromide particles with average diameter of about 20 nm and better monodispersity were prepared by direct reaction of silver nitrate with mixture of potassium bromide and potassium iodide. According to TEM data, it was discovered that gelatin+PVA showed stronger colloid protective power for these ultra-fine particles, which restrained particles' coalescence and growth effectively during physical and chemical ripening, so that there was not observable change of particle size and monodispersity to be found. In the case of only gelatin as colloid protective medium to prepare ultra-fine silver iodobromide particles, particles'stability in the process of physical ripening depended on the ratio of gelatin amount to silver content as the preparing reaction. It appears that there exists a critical ratio of gelatin amount to silver content for particles′ stability. When experimental ratio of gelatin amount to silver content in the reaction was over this critical ratio, gelatin can protect ultra-fine particles against coalescence and growth to a considerable degree. On the contrary, the particle size beacme significantly large in the process of physical ripening due to decrease of gelatin protective power if the experimental ratio was lower than this critical ratio.

  14. A Humidity Sensor Based on Silver Nanoparticles Thin Film Prepared by Electrostatic Spray Deposition Process

    Directory of Open Access Journals (Sweden)

    Thutiyaporn Thiwawong

    2013-01-01

    Full Text Available In this work, thin film of silver nanoparticles for humidity sensor application was deposited by electrostatic spray deposition technique. The influence of the deposition times on properties of films was studied. The crystal structures of sample films, their surface morphology, and optical properties have been investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, and UV-VIS spectrophotometer, respectively. The crystalline structure of silver nanoparticles thin film was found in the orientation of (100 and (200 planes of cubic structure at diffraction angles 2θ  =  38.2° and 44.3°, respectively. Moreover, the silver nanoparticles thin films humidity sensor was fabricated onto the interdigitated electrodes. The sensor exhibited the humidity adsorption and desorption properties. The sensing mechanisms of the device were also elucidated by complex impedance analysis.

  15. Preparation of Polyethylene Composites Containing Silver(I) Acylpyrazolonato Additives and SAR Investigation of their Antibacterial Activity.

    Science.gov (United States)

    Marchetti, Fabio; Palmucci, Jessica; Pettinari, Claudio; Pettinari, Riccardo; Marangoni, Mirko; Ferraro, Stefano; Giovannetti, Rita; Scuri, Stefania; Grappasonni, Iolanda; Cocchioni, Mario; Maldonado Hodar, Francisco José; Gunnella, Roberto

    2016-11-02

    Novel composite materials PEn (n = 1-9) have been prepared by an easily up-scalable embedding procedure of three different families of Ag(I) acylpyrazolonato complexes in polyethylene (PE) matrix. In details, PE1-PE3 composites contain polynuclear [Ag(Q(R))]n complexes, PE4-PE6 contain mononuclear [Ag(Q(R))(L)m] complexes and PE7-PE9 are loaded with mononuclear [Ag(Q(R)) (PPh3)2] complexes, respectively (where L = 1-methylimidazole or 2-ethylimidazole, m = 1 or 2, and HQ(R) = 1-phenyl-3-methyl-4-RC(═O)-5-pyrazolone, where in detail HQ(fb), R = -CF2CF2CF3; HQ(cy), R = -cyclo-C6H11; HQ(be), R = -C(H)═C(CH3)2). The PEn composites, prepared by using a 1:1000 w/w silver additive/polyethylene ratio, have been characterized in bulk by IR spectroscopy and TGA analyses, which confirmed that the properties of polyethylene matrix are essentially unchanged. AFM, SEM, and EDX surface techniques show that silver additives form agglomerates with dimensions 10-100 μm on the polyethylene surface, with a slight increment of surface roughness of pristine plastic within 50 nm. However, the elastic properties of the composites are essentially the same of PE. The antibacterial activity of all composites has been tested against three bacterial strains (E. coli, P. aeruginosa and S. aureus) and results show that two classes of composites, PE1-PE3 and PE4-PE6, display high and persistent bactericidal and bacteriostatic activity, comparable to PE embedded with AgNO3. By contrast, composites PE7-PE9 exhibit a reduced antibacterial action. Contact and release tests in several conditions for specific migration of Ag(+) from plastics, indicate a very limited but time persistent release of silver ions from PE1-PE6 composites, thus suggesting that they are potential antibacterial materials for future applications. Instead, PE7-PE9 almost do not release silver, only trace levels of silver ions being detected, in accordance with their reduced antibacterial action. None of the composites is

  16. Preparation of nanosized non-oxide powders using diatomaceous earth

    Directory of Open Access Journals (Sweden)

    Šaponjić A.

    2009-01-01

    Full Text Available In this paper the nanosized non-oxide powders were prepared by carbothermal reduction and subsequent nitridation of diatomaceous earth which is a waste product from coal exploitation. Our scope was to investigate the potential use of diatomaceous earth as a main precursor for low-cost nanosized non-oxide powder preparation as well as to solve an environmental problem. The influence of carbon materials (carbonized sucrose, carbon cryogel and carbon black as a reducing agent on synthesis and properties of low-cost nanosized nonoxide powders was also studied. The powders were characterized by specific surface area, X-ray and SEM investigations. It was found that by using diatomaceous earth it is was possible to produce either a mixture of non-oxide powders (Si3N4/SiC or pure SiC powders depending on temperature.

  17. Soil microbial community responses to contamination with silver, aluminium oxide and silicon dioxide nanoparticles.

    Science.gov (United States)

    McGee, C F; Storey, S; Clipson, N; Doyle, E

    2017-04-01

    Soil microorganisms are key contributors to nutrient cycling and are essential for the maintenance of healthy soils and sustainable agriculture. Although the antimicrobial effects of a broad range of nanoparticulate substances have been characterised in vitro, little is known about the impact of these compounds on microbial communities in environments such as soil. In this study, the effect of three widely used nanoparticulates (silver, silicon dioxide and aluminium oxide) on bacterial and fungal communities in an agricultural pastureland soil was examined in a microcosm-based experiment using a combination of enzyme analysis, molecular fingerprinting and amplicon sequencing. A relatively low concentration of silver nanoparticles (AgNPs) significantly reduced total soil dehydrogenase and urease activity, while Al2O3 and SiO2 nanoparticles had no effect. Amplicon sequencing revealed substantial shifts in bacterial community composition in soils amended with AgNPs, with significant decreases in the relative abundance of Acidobacteria and Verrucomicrobia and an increase in Proteobacteria. In particular, the relative abundance of the Proteobacterial genus Dyella significantly increased in AgNP amended soil. The effects of Al2O3 and SiO2 NPs on bacterial community composition were less pronounced. AgNPs significantly reduced bacterial and archaeal amoA gene abundance in soil, with the archaea more susceptible than bacteria. AgNPs also significantly impacted soil fungal community structure, while Al2O3 and SiO2 NPs had no effect. Several fungal ribotypes increased in soil amended with AgNPs, compared to control soil. This study highlights the need to consider the effects of individual nanoparticles on soil microbial communities when assessing their environmental impact.

  18. Silver nanoaggregates on chitosan functionalized graphene oxide for high-performance surface-enhanced Raman scattering.

    Science.gov (United States)

    Wan, Mingming; Liu, Zhiming; Li, Shaoxin; Yang, Biwen; Zhang, Wen; Qin, Xiaochu; Guo, Zhouyi

    2013-07-01

    Herein we describe a self-assembly synthesis of graphene oxide/Ag nanoparticles nano-composites (GO/CS/AgNPs) by non-covalent attachment of AgNPs to chitosan (CS) functionalized graphene oxide (GO) sheets. The negatively charged AgNPs are prone to form aggregates on GO/CS via electrostatic interaction, which is extremely beneficial to the surface-enhanced Raman scattering (SERS) detection of aromatic molecules. Taking advantage of the enrichment of target molecules on GO, the obtained hybrids exhibit strong SERS activity to aromatic molecules (trypan blue and methylene blue). Furthermore, SERS signals of a negatively charged molecule (trypan blue) are stronger than signals of a positively charged molecule (methylene blue) due to the different adsorption capacity of GO/CS/AgNPs for the two opposite charged molecules through electrostatic interaction. Moreover, GO/CS/AgNPs remarkably enhance the main peaks of l-phenylalanine, in comparison with the silver nanoparticles, showing great potential for biomedical applications.

  19. Oxidized multiwalled carbon nanotubes decorated with silver nanoparticles for fluorometric detection of dimethoate.

    Science.gov (United States)

    Hsu, Chun-Wei; Lin, Zhong-Yi; Chan, Tzu-Yi; Chiu, Tai-Chia; Hu, Cho-Chun

    2017-06-01

    A novel method for the detection of dimethoate based on the peroxidase-like activity of silver-nanoparticles-modified oxidized multiwalled carbon nanotubes (AgNPs/oxMWCNTs) has been developed. The synthesized AgNPs/oxMWCNTs showed excellent peroxidease-like catalytic activity in hydrogen peroxide-Amplex red (AR) system (AR is oxidized to resorufinat, with the resorufin fluorescence at 584nm being used to monitor the catalytic activity). After dimethoate was added to AgNPs/oxMWCNTs, the interaction between dimethoate and the AgNPs inhibited the catalytic activity of AgNPs/oxMWCNTs. The decrease in fluorescence was used for the detection of dimethoate in the range of 0.01-0.35μgmL(-1) (R(2)=0.998) with a detection limit of 0.003μgmL(-1) (signal/noise=3). This method exhibited good selectivity for the detection of dimethoate even in the presence of high concentration of other pesticides. Consequently, the method was applied to measure the concentration of dimethoate residue in lake water and fruit, thus obtaining satisfactory results.

  20. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells.

    Science.gov (United States)

    Kim, Hong-Sik; Patel, Malkeshkumar; Park, Hyeong-Ho; Ray, Abhijit; Jeong, Chaehwan; Kim, Joondong

    2016-04-06

    Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects.

  1. Apoptosis inducing ability of silver decorated highly reduced graphene oxide nanocomposites in A549 lung cancer.

    Science.gov (United States)

    Khan, Merajuddin; Khan, Mujeeb; Al-Marri, Abdulhadi H; Al-Warthan, Abdulrahman; Alkhathlan, Hamad Z; Siddiqui, Mohammed Rafiq H; Nayak, Vadithe Lakshma; Kamal, Ahmed; Adil, Syed F

    2016-01-01

    Recently, graphene and graphene-based materials have been increasingly used for various biological applications due to their extraordinary physicochemical properties. Here, we demonstrate the anticancer properties and apoptosis-inducing ability of silver doped highly reduced graphene oxide nanocomposites synthesized by employing green approach. These nano composites (PGE-HRG-Ag) were synthesized by using Pulicaria glutinosa extract (PGE) as a reducing agent and were evaluated for their anticancer properties against various human cancer cell lines with tamoxifen as the reference drug. A correlation between the amount of Ag nanoparticles on the surface of highly reduced graphene oxide (HRG) and the anticancer activity of nanocomposite was observed, wherein an increase in the concentration of Ag nanoparticles on the surface of HRG led to the enhanced anticancer activity of the nanocomposite. The nanocomposite PGE-HRG-Ag-2 exhibited more potent cytotoxicity than standard drug in A549 cells, a human lung cancer cell line. A detailed investigation was undertaken and Fluorescence activated cell sorting (FACS) analysis demonstrated that the nanocomposite PGE-HRG-Ag-2 showed G0/G1 phase cell cycle arrest and induced apoptosis in A549 cells. Studies such as, measurement of mitochondrial membrane potential, generation of reactive oxygen species (ROS) and Annexin V-FITC staining assay suggested that this compound induced apoptosis in human lung cancer cells.

  2. Preparation of silver nanoparticles in virgin coconut oil using laser ablation

    OpenAIRE

    Zamiri, Reza; Sadrolhosseini, Amir Reza

    2011-01-01

    Reza Zamiri1, B Z Azmi1,2, Amir Reza Sadrolhosseini1, Hossein Abbastabar Ahangar3, A W Zaidan1, M A Mahdi41Department of Physics, 2Advanced Materials and Nanotechnology Laboratory, 3Department of Chemistry, 4Wireless and Photonics Networks Research Center, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaAbstract: Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for a...

  3. Synthesis and characterization of silver and gold nanoparticles in ionic liquid

    Science.gov (United States)

    Singh, Prashant; Kumari, Kamlesh; Katyal, Anju; Kalra, Rashmi; Chandra, Ramesh

    2009-07-01

    In this paper, we report the reduction of silver and gold salts by methanolic solution of sodium borohydride in tetrazolium based ionic liquid as a solvent at 30 °C leads to pure phase of silver and gold nanoparticles. Silver and gold nanoparticles so-prepared were well characterized by powder X-ray diffraction measurements (XRD), transmission electron microscopy (TEM) and QELS. XRD analysis revealed all relevant Bragg's reflection for crystal structure of silver and gold metal. XRD spectra also revealed no oxidation of silver nanoparticles to silver oxide. TEM showed nearly uniform distribution of the particles in methanol and it was confirmed by QELS. Silver and gold nanoparticles in ionic liquid can be easily synthesized and are quite stable too.

  4. Reusable fluorescent sensor for captopril based on energy transfer from photoluminescent graphene oxide self-assembly multilayers to silver nanoparticles

    Science.gov (United States)

    Sun, Xiangying; Liu, Bin; Li, Shuchun; Li, Fang

    2016-05-01

    In this work we designed a self-assembly multilayers, in which photoluminescent graphene oxide was employed as a fluorescence probe. This multilayers film can effectively recognize captopril by resonance energy transfer from graphite oxide to silver nanoparticles. A new interfacial sensing method for captopril with high signal to noise ratio was established, by means of that multilayers was quenched by silver nanoparticles and subsequently recovered by adding captopril. The linear relation between intensity and captopril concentration was good, and the detection limit was found to be 0.1578 μM. Also, this novel detection platform demonstrated intriguing reusable properties, and the sensor could be repeated more than ten times without obviously losing its sensing performance.

  5. Bulk Preparation of Holey Graphene via Controlled Catalytic Oxidation

    Science.gov (United States)

    Watson, Kent (Inventor); Lin, Yi (Inventor); Ghose, Sayata (Inventor); Connell, John (Inventor)

    2015-01-01

    A scalable method allows preparation of bulk quantities of holey carbon allotropes with holes ranging from a few to over 100 nm in diameter. Carbon oxidation catalyst nanoparticles are first deposited onto a carbon allotrope surface in a facile, controllable, and solvent-free process. The catalyst-loaded carbons are then subjected to thermal treatment in air. The carbons in contact with the carbon oxidation catalyst nanoparticles are selectively oxidized into gaseous byproducts such as CO or CO.sub.2, leaving the surface with holes. The catalyst is then removed via refluxing in diluted nitric acid to obtain the final holey carbon allotropes. The average size of the holes correlates strongly with the size of the catalyst nanoparticles and is controlled by adjusting the catalyst precursor concentration. The temperature and time of the air oxidation step, and the catalyst removal treatment conditions, strongly affect the morphology of the holes.

  6. Preparation and characterization of copper-doped cobalt oxide electrodes.

    Science.gov (United States)

    Rosa-Toro, A La; Berenguer, R; Quijada, C; Montilla, F; Morallón, E; Vazquez, J L

    2006-11-30

    Cobalt oxide (Co3O4) and copper-doped cobalt oxide (CuxCo(3-x)O4) films have been prepared onto titanium support by the thermal decomposition method. The electrodes have been characterized by different techniques such as cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The effect on the electrochemical and crystallographic properties and surface morphology of the amount of copper in the oxide layer has been analyzed. The XPS spectra correspond to a characteristic monophasic Cu-Co spinel oxides when x is below 1. However, when the copper content exceeds that for the stoichiometric CuCo2O4 spinel, a new CuO phase segregates at the surface. The analysis of the surface cation distribution indicates that Cu(II) has preference for octahedral sites.

  7. 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.

  8. Environmentally Friendly Preparation of Gold and Silver Nanoparticles for Sers Applications Using Biopolymer Pectin

    Science.gov (United States)

    Balachandran, Y. L.; Panarin, A. Y.; Khodasevich, I. A.; Terekhov, S. N.; Gutleb, A. C.; Girijaa, S.

    2015-01-01

    A facile, one-step, and environmentally friendly fabrication of anisotropic gold nanostructures and size-controlled spherical silver nanoparticles (NP) using biopolymer pectin is reported. The reduction of Au and Ag ions was carried out at room temperature using an increasing concentration of pectin, which acts as the single source of reducing and stabilizing agent. The as-formed NPs were studied by UV-vis, infrared Fourier transform and surface-enhanced Raman spectroscopies, as well as transmission electron microscopy and energy dispersive X-ray spectroscopy. A high yield of anisotropic gold nanostructures was observed at low concentrations of pectin, while its increase results in the formation of smaller sharp edged perfect triangles with a considerable number of quasi-spherically shaped gold NP. On the other hand, the size of spherical silver NP decreased as the biopolymer concentration in the solution increased. The surface-enhanced Raman scattering enhancement of different NPs was evaluated using a Cu-complex of cationic tetrakis(4-N-methylpyridyl)porphyrin as a probe molecule at 441.6 and 532 nm excitation. Great enhancement of Raman signal was obtained with a pectin-silver NP and for most of them their levels were higher than that for the routinely synthesized citrate silver NP.

  9. Investigation of silver and iodine transport through silicon carbide layers prepared for nuclear fuel element cladding

    Science.gov (United States)

    Friedland, E.; van der Berg, N. G.; Malherbe, J. B.; Hancke, J. J.; Barry, J.; Wendler, E.; Wesch, W.

    2011-03-01

    Transport of silver and iodine through polycrystalline SiC layers produced by PBMR (Pty) Ltd. for cladding of TRISO fuel kernels was investigated using Rutherford backscattering analysis and electron microscopy. Fluences of 2 × 10 16 Ag + cm -2 and 1 × 10 16 I + cm -2 were implanted at room temperature, 350 °C and 600 °C with an energy of 360 keV, producing an atomic density of approximately 1.5% at the projected ranges of about 100 nm. The broadening of the implantation profiles and the loss of diffusors through the front surface during vacuum annealing at temperatures up to 1400 °C was determined. The results for room temperature implantations point to completely different transport mechanisms for silver and iodine in highly disordered silicon carbide. However, similar results are obtained for high temperature implantations, although iodine transport is much stronger influenced by lattice defects than is the case for silver. For both diffusors transport in well annealed samples can be described by Fickian grain boundary diffusion with no abnormal loss through the surface as would be expected from the presence of nano-pores and/or micro-cracks. At 1100 °C diffusion coefficients for silver and iodine are below our detection limit of 10 -21 m 2 s -1, while they increase into the 10 -20 m 2 s -1 range at 1300 °C.

  10. 生物法制备纳米银溶胶的稳定性%Stability of Colloidal Silver Nanoparticles Prepared by Bioreduction

    Institute of Scientific and Technical Information of China (English)

    孙道华; 李清彪; 何宁; 黄加乐; 王惠璇

    2011-01-01

    利用生物还原法制备纳米银溶胶,借助于UV-Vis表征技术对其热稳定性和化学稳定性进行考察.结果表明:生物法制备的纳米银溶胶在100℃下加热6 h,UV-Vis谱图未发生明显变化;H+和具有高价阳离子的电解质对其稳定性的影响明显;OH-对银溶胶的稳定性影响相对较弱.生物法制备的纳米银溶胶在热稳定性、化学稳定性方面均略优于柠檬酸三钠法制得的银溶胶.%The thermal and chemical statoilities of the colloid silver nanoparticles prepared by bioreduction were investigated in virtue of UV-Vis spectrometer.The results indicate that UV-Vis spectra of silver colloid prepared by bioreduction have not significant change after heat treatment at 100 ℃ for 6 h.Hydrogen ion and the electrolyte with multivalent cation markedly influence stabilities of the silver colloid, while hydroxide anion has a weak influence on its stability.Thermal and chemical stabilities of the silver colloid prepared by bioreduction are superior to that of the silver colloid prepared by the sodium citrate reduction method.

  11. Silver Nanoparticle-Embedded Thin Silica-Coated Graphene Oxide as an SERS Substrate

    Directory of Open Access Journals (Sweden)

    Xuan-Hung Pham

    2016-09-01

    Full Text Available A hybrid of Ag nanoparticle (NP-embedded thin silica-coated graphene oxide (GO@SiO2@Ag NPs was prepared as a surface-enhanced Raman scattering (SERS substrate. A 6 nm layer of silica was successfully coated on the surface of GO by the physical adsorption of sodium silicate, followed by the hydrolysis of 3-mercaptopropyl trimethoxysilane. Ag NPs were introduced onto the thin silica-coated graphene oxide by the reduction of Ag+ to prepare GO@SiO2@Ag NPs. The GO@SiO2@Ag NPs exhibited a 1.8-fold enhanced Raman signal compared to GO without a silica coating. The GO@SiO2@Ag NPs showed a detection limit of 4-mercaptobenzoic acid (4-MBA at 0.74 μM.

  12. Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Song, Cunfeng [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chang, Ying; Cheng, Ling; Xu, Yiting [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Xiaoling, E-mail: tinachen0628@163.com [Department of Endodontics, Xiamen Stomatology Hospital, Teaching Hospital of Fujian Medical University, Xiamen 361003 (China); Zhang, Long; Zhong, Lina [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Dai, Lizong, E-mail: lzdai@xmu.edu.cn [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China)

    2014-03-01

    A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. - Highlights: • A new type of antibacterial agent (PSA/Ag-NPs nanocomposites) was synthesized. • The antibacterial activity against S. aureus and E. coli was studied. • Inhibition zone, MIC, MBC, and bactericidal kinetics were evaluated. • PSA/Ag-NPs nanocomposites showed excellent antibacterial activity.

  13. Ameliorative effect of zinc oxide and silver nanoparticles on antioxidant system in the brain of diabetic rats

    Institute of Scientific and Technical Information of China (English)

    Mohamed Afifi; Aaser Mohamed Abdelazim

    2015-01-01

    Objective:To test the ability of both zinc oxide nanoparticles (ZnONPs) and silver nanoparticles (SNPs) to ameliorate the oxidative stress resulted from diabetes in diabetic rats. Methods: Fifty male albino rats were used; ten of them were served as control group and forty, as the experiment group, were injected with streptozotocin at the single intraperitoneal dose of 100 mg/kg. Then, the experiment group was subdivided into, diabetic, diabetic +ZnONPs, diabetic +SNPs and diabetic + insulin groups. The activities and mRNA expression levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase were determined in brain tissues. Malondialdehyde, total antioxidant capacity, zinc and silver concentrations were estimated in the brain tissues of all rats. Results:A significant increase in the activities and mRNA expression levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase was shown. Malondialdehyde levels were significantly decreased while there was a significant increase in the zinc, silver concentrations and total antioxidant capacity in brain ofZnONPs andSNPs treated rats, compared with diabetic or diabetic + insulin group and their control group. Conclusions:ZnONPs andSNPs can be used to ameliorate the oxidative stress in brain resulted from diabetes mellitus.

  14. Ameliorative effect of zinc oxide and silver nanoparticles on antioxidant system in the brain of diabetic rats简

    Institute of Scientific and Technical Information of China (English)

    Mohamed; Afifi; Aaser; Mohamed; Abdelazim

    2015-01-01

    Objective: To test the ability of both zinc oxide nanoparticles(Zn ONPs) and silver nanoparticles(SNPs) to ameliorate the oxidative stress resulted from diabetes in diabetic rats.Methods: Fifty male albino rats were used; ten of them were served as control group and forty, as the experiment group, were injected with streptozotocin at the single intraperitoneal dose of 100 mg/kg. Then, the experiment group was subdivided into, diabetic,diabetic + Zn ONPs, diabetic + SNPs and diabetic + insulin groups. The activities and m RNA expression levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase were determined in brain tissues. Malondialdehyde, total antioxidant capacity, zinc and silver concentrations were estimated in the brain tissues of all rats.Results: A significant increase in the activities and m RNA expression levels of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase was shown.Malondialdehyde levels were significantly decreased while there was a significant increase in the zinc, silver concentrations and total antioxidant capacity in brain of Zn ONPs and SNPs treated rats, compared with diabetic or diabetic + insulin group and their control group.Conclusions: Zn ONPs and SNPs can be used to ameliorate the oxidative stress in brain resulted from diabetes mellitus.

  15. Influence of Pretreatment on the Interaction of Oxygen with Silver and the Catalytic Activity of Ag/SiO2 Catalysts for CO Selective Oxidation in H2

    Institute of Scientific and Technical Information of China (English)

    Zhenping Qua; Mojie Cheng; Chuan Shi; Xinhe Bao

    2005-01-01

    The interactions of oxygen with pre-reduced silver catalysts as well as their catalytic properties for CO selective oxidation in H2 after oxygen pre-treatment are studied in this paper. It is found that the pretreatment exerts a strong influence on the activity and selectivity of the silver catalyst. A drop in activity and selectivity is observed after treating a pre-reduced catalyst with oxygen at low temperatures,whereas a converse result is obtained after an oxidizing treatment at high temperatures (T≥350 ℃). O2-TPD results show that surface oxygen species adsorbs on silver surface after the oxygen treatment at low temperatures. However, penetration of oxygen into the silver is enhanced by a high temperature treatment, meanwhile the surface oxygen species disappear. No other silver species except metallic silver are observed on all the catalysts by XRD, and the size of silver particle is not changed after the treatment with oxygen at low temperatures. The surface oxygen species formed by oxygen treatment can also be removed by hydrogen reduction. The strongly-adsorbed surface oxygen species prohibit the adsorption and diffusion of oxygen species in reaction gas on the surface of silver catalyst, causing the decrease in CO oxidation activity, in other words, it is important to obtain a clean silver surface for increasing the catalyst activity in CO removal from H2-rich feed gas. The differences in activity and selectivity due to the oxygen pretreatment at different temperatures are discussed in terms of the changes in the surface/subsurface oxygen species of the silver particles.

  16. Silver/iron oxide/graphitic carbon composites as bacteriostatic catalysts for enhancing oxygen reduction in microbial fuel cells

    Science.gov (United States)

    Ma, Ming; You, Shijie; Gong, Xiaobo; Dai, Ying; Zou, Jinlong; Fu, Honggang

    2015-06-01

    Biofilms from anode heterotrophic bacteria are inevitably formed over cathodic catalytic sites, limiting the performances of single-chamber microbial fuel cells (MFCs). Graphitic carbon (GC) - based nano silver/iron oxide (AgNPs/Fe3O4/GC) composites are prepared from waste pomelo skin and used as antibacterial oxygen reduction catalysts for MFCs. AgNPs and Fe3O4 are introduced in situ into the composites by one-step carbothermal reduction, enhancing their conductivity and catalytic activity. To investigate the effects of Fe species on the antibacterial and catalytic properties, AgNPs/Fe3O4/GC is washed with sulfuric acid (1 mol L-1) for 0.5 h, 1 h, and 5 h and marked as AgNPs/Fe3O4/GC-x (x = 0.5 h, 1 h and 5 h, respectively). A maximum power density of 1712 ± 35 mW m-2 is obtained by AgNPs/Fe3O4/GC-1 h, which declines by 4.12% after 17 cycles. Under catalysis of all AgNP-containing catalysts, oxygen reduction reaction (ORR) proceeds via the 4e- pathway, and no toxic effects to anode microorganisms result from inhibiting the cathodic biofilm overgrowth. With the exception of AgNPs/Fe3O4/GC-5 h, the AgNPs-containing composites exhibit remarkable power output and coulombic efficiency through lowering proton transfer resistance and air-cathode biofouling. This study provides a perspective for the practical application of MFCs using these efficient antibacterial ORR catalysts.

  17. Synthesis, structure, and reactivity of high oxidation state silver fluorides and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lucier, George Michael [Univ. of California, Berkeley, CA (United States)

    1995-05-01

    This thesis has been largely concerned with defining the oxidizing power of Ag(III) and Ag(II) in anhydrous hydrogen fluoride (aHF) solution. Emphasis was on cationic species, since in a cation the electronegativity of a given oxidation state is greatest. Cationic Ag(III) solv has a short half life at ordinary temperatures, oxidizing the solvent to elemental fluorine with formation of Ag(II). Salts of such a cation have not yet been preparable, but solutions which must contain such a species have proved to be effective and powerful oxidizers. In presence of PtF6-, RuF6-, or RhF6-, Ag(III) solv effectively oxidizes the anions to release the neutral hexafluorides. Such reactivity ranks cationic Ag(III) as the most powerfully oxidizing chemical agent known as far. Unlike its trivalent relative Ag (II) solv is thermodynamically stable in acid aHF. Nevertheless, it oxidizes IrF6- to IrF6 at room temperature, placing its oxidizing potential not more than 2 eV below that of cationic Ag(III). Range of Ag2+ (MF6-2 salts attainable in aHF has been explored. An anion must be stable with respect to electron loss to Ag2+. The anion must also be a poor F- donor; otherwise, either AgF+ salts or AgF2 are generated.

  18. Triphenylphosphine Stabilized Silver Carboxylates

    Institute of Scientific and Technical Information of China (English)

    Jian Lin HAN; Ying Zhong SHEN; Yi PAN

    2005-01-01

    A series of novel triphenylphosphine stabilized silver carboxylates, potential precursors for CVD growth of ultrafast interconnection link in microelectronic devices, have been prepared and characterized.

  19. Toxic behavior of silver and zinc oxide nanoparticles on environmental microorganisms.

    Science.gov (United States)

    Dhas, Sindhu Priya; Shiny, Punalur John; Khan, Sudheer; Mukherjee, Amitava; Chandrasekaran, Natrajan

    2014-09-01

    Silver and zinc oxide nanoparticles (Ag and ZnO NPs) are widely used as antimicrobial agents. However, their potential toxicological impact on environmental microorganisms is largely unexplored. The aim of this work was to investigate the sensitivity and adaptability of five bacterial species isolated from sewage towards Ag and ZnO NPs. The bacterial species were exposed to increasing concentration of nanoparticles and the growth inhibitory effect, exopolysaccharides (EPSs) and extracellular proteins (ECPs) productions were determined. The involvement of surface charge in nanoparticles toxicity was also determined. The bacterial species were constantly exposed to nanoparticles to determine the adaptation behavior toward nanoparticles. The nanoparticles exhibited remarkable growth inhibitory effect on tested bacterial species. The toxicity of nanoparticles was found to be strongly dependent on surface charge effects. Though, these organisms are highly sensitive to Ag and ZnO NPs, the continuous exposure to these nanoparticles leads to moderate adaptation of bacterial species and the adapted bacterial species convert the highly toxic nano form to less toxic microform. Finally we predict that the continuing applications of nanoparticles in consumer products may lead to the development of nanoparticles resistant bacterial strains in future.

  20. Electric radiation mapping of silver/zinc oxide nanoantennas by using electron holography

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, J. E.; Mendoza-Santoyo, F.; Cantu-Valle, J.; Velazquez-Salazar, J.; José Yacaman, M.; Ponce, A. [Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio 78249 (United States); González, F. J. [Coordinación para la Innovación y la Aplicación de la Ciencia y la Tecnología, Universidad Autónoma de San Luís Potosí, San Luis Potosí 78210 (Mexico); Diaz de Leon, R. [Instituto Tecnológico de San Luis Potosí, San Luis Potosi 78437 (Mexico)

    2015-01-21

    In this work, we report the fabrication of self-assembled zinc oxide nanorods grown on pentagonal faces of silver nanowires by using microwaves irradiation. The nanostructures resemble a hierarchal nanoantenna and were used to study the far and near field electrical metal-semiconductor behavior from the electrical radiation pattern resulting from the phase map reconstruction obtained using off-axis electron holography. As a comparison, we use electric numerical approximations methods for a finite number of ZnO nanorods on the Ag nanowires and show that the electric radiation intensities maps match closely the experimental results obtained with electron holography. The time evolution of the radiation pattern as generated from the nanostructure was recorded under in-situ radio frequency signal stimulation, in which the generated electrical source amplitude and frequency were varied from 0 to 5 V and from 1 to 10 MHz, respectively. The phase maps obtained from electron holography show the change in the distribution of the electric radiation pattern for individual nanoantennas. The mapping of this electrical behavior is of the utmost importance to gain a complete understanding for the metal-semiconductor (Ag/ZnO) heterojunction that will help to show the mechanism through which these receiving/transmitting structures behave at nanoscale level.

  1. Preparation and antibacterial activity of silver nanoparticles impregnated in bacterial cellulose

    Directory of Open Access Journals (Sweden)

    Luiz C. S. Maria

    2010-01-01

    Full Text Available A simple method was developed to load a large amount of silver nanoparticles into bacterial cellulose (BC produced by Gluconacetobacter xylinus in a controlled manner. Due to the high electron-rich oxygen density in the BC macromolecules and the large surface area of the BC nanoporous structure as an effective nanoreactor, the in situ direct metallization technique was successfully used to synthesize Ag nanoparticles with an average diameter of 30 nm and a loading content of at least 5 wt. (%, approximately. This novel procedure provides an easy and economical way to manufacture Ag nanoparticles supported on a porous membrane for various biomedical applications. These composite fibers showed nearly 100% antibacterial activity (elimination of microorganisms against Escherichia coli because of the presence of the silver nanoparticles.

  2. Silver nanoparticles prepared in presence of ascorbic acid and gelatin, and their electrocatalytic application

    Indian Academy of Sciences (India)

    Fereshteh Chekin; Somayeh Ghasemi

    2014-10-01

    In this paper, we reported a simple and low-cost procedure to synthesize silver nanoparticles (AgNPs) by using ascorbic acid as reducing agent and gelatin as stabilizer. The synthesized AgNPs were characterized by various means such as transmission electron microscope (TEM), powder X-ray diffraction (XRD) and energy-dispersive X-ray (EDX). TEM observations and XRD analysis demonstrated that the size of AgNPs is about 20 nm. Silver nanoparticles modified with carbon-paste electrode (AgNPs–CPE) displayed excellent electrochemical catalytic activities towards hydrogen peroxide (H2O2). The reduction overpotential of H2O2 was decreased significantly compared with those obtained at the bare CPE. The sensor responded linearly to hydrogen peroxide (H2O2) in the concentration of 10–350 M, with detection limit of 5.6 M at 3 using amperometry. The studied sensor exhibited good reproducibility and long-term stability.

  3. The study of the antimicrobial activity of colloidal solutions of silver nanoparticles prepared using food stabilizers.

    Science.gov (United States)

    Balandin, G V; Suvorov, O A; Shaburova, L N; Podkopaev, D O; Frolova, Yu V; Ermolaeva, G A

    2015-06-01

    The bactericidal effect of colloidal solutions of silver nanoparticles based on food stabilizers, gum arabic and chitosan, against bacterial cultures of microorganisms in food production is described. The antibacterial activity of nanotechnology products containing different amounts of stabilizing additives when applied to solid pH-neutral substrates is studied. For its evaluation a method making it possible to take into account the capability of nanoparticles to diffuse in solid media was applied. Minimal inhibitory concentrations of nanoparticles used against Erwinia herbicola, Pseudomonas fluorescens, Bacillus subtilis, Sarcina flava were found. A suggestion was made concerning the influence of the spatial structure of bacteria on the antibacterial activity of colloidal solutions of silver nanoparticles. The data concerning the antibacterial activity and minimal inhibiting concentrations of nanoparticles may be used for development of products suppressing activity of microorganisms hazardous for food production.

  4. Fabrication And Properties Of Silver Based Multiwall Carbon Nanotube Composite Prepared By Spark Plasma Sintering Method

    Directory of Open Access Journals (Sweden)

    Lis M.

    2015-06-01

    Full Text Available The paper presents results of investigations of the obtained nanocomposite materials based on silver with addition of multiwall carbon nanotubes. The powder of carbon nanotubes content from 0.1 to 3 wt. % was produced by application of powder metallurgy methods, through mixing and high-energetic milling, and also chemical methods. Modification of carbon nanotubes included electroless deposition of silver particles on the carbon nanotube active surfaces and chemical reduction with strong reducing agent – sodium borohydride (NaBH4. The obtained powder mixtures were consolidated by SPS – Spark Plasma Sintering method. The formed composites were subjected to tests of relative density, electrical conductivity and electro-erosion properties. Detailed examinations of the structure with application of X-ray microanalysis, with consideration of carbon nanotubes distribution, were also carried out. The effect of manufacturing methods on properties of the obtained composites was observed.

  5. Preparation of superhydrophobic silver nano coatings with feather-like structures by electroless galvanic deposition

    Institute of Scientific and Technical Information of China (English)

    FENG XiaoJuan; SHI YanLong; WANG YongSheng; YUE GuoRen; YANG Wu

    2013-01-01

    Superhydrophobic silver nanocoatings with feather-like morphology are fabricated on copper substrates by electroless galvanic deposition.The coating exhibit superhydrophobicity with a contact angle of 156.4° and glide angle of 4° without any further surface modification.Scanning electron microscope (SEM),X-ray diffraction (XRD) and contact angle measurements are used to investigate the morphology,crystal structure and superhydrophobicity,respectively,of the coatings.The coatings exhibit high thermal stability; their water contact angle did not change when the coatings were heated to 200℃ for 2 h.The mechanism of superhydrophobicity of the silver coating is discussed based on the work of Amirfazli,Wenzel and Cassie.

  6. Preparation of dendritic nanostructures of silver and their characterization for electroreduction.

    Science.gov (United States)

    Qin, Xia; Miao, Zhiying; Fang, Yuxin; Zhang, Di; Ma, Jia; Zhang, Lu; Chen, Qiang; Shao, Xueguang

    2012-03-20

    Silver nanostructures of different morphologies including well-defined dendrites were synthesized on an Au substrate by a simple surfactant-free method without using any template. The morphology of the material was investigated by field-emission transmission electron microscopy and scanning electron microscopy. The crystal nature of the dendritic nanostructure was revealed from their X-ray diffraction and electron diffraction patterns. Effects of applied potential, electrolysis time, and the solution concentration were studied. The possible formation mechanism of the dendritic morphology was discussed from the aspects of kinetics and thermodynamics based on the experiment results. The H(2)O(2) electroreduction ability of the dendritic materials was characterized. Use of silver dendrite-modified electrode as H(2)O(2) sensor was also demonstrated.

  7. Properties of tin oxides prepared by ion-beam-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Martin; Hamann, Robert; Polity, Angelika; Feili, Davar; Meyer, Bruno K. [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

    2013-07-01

    The success of n-type oxide semiconductors and its application in oxide-based electronic devices has motivated the interest in p-type oxide based semiconductors. Therefore synthesis of tin monoxide (SnO) recently has received increasing attention. Another phase of this binary system, SnO{sub 2}, is of great technological interest in manifold applications, such as transparent electrodes, heat-reflecting filters and gas sensing. The preparation of tin oxide thin films has been performed by many different procedures such as sol/gel, epitaxial procedures or methods working under vacuum conditions like sputtering techniques. Radio-Frequency-Ion-Thrusters, as designed for propulsion applications, are also qualified for thin film deposition and surface etching if utilized as ion source. Tin oxide thin films were grown by ion-beam sputtering using a 3 inch metallic tin target. Different aspects of growth and properties of the tin oxide phases were investigated in relation to growth parameters such as substrate temperature or flux of oxygen. Structural, optical and electrical properties of the films are discussed.

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

    Science.gov (United States)

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

    2015-02-01

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

  9. Toxicity profiling of water contextual zinc oxide, silver, and titanium dioxide nanoparticles in human oral and gastrointestinal cell systems.

    Science.gov (United States)

    Giovanni, Marcella; Tay, Chor Yong; Setyawati, Magdiel Inggrid; Xie, Jianping; Ong, Choon Nam; Fan, Rongli; Yue, Junqi; Zhang, Lifeng; Leong, David Tai

    2015-12-01

    Engineered nanoparticles (ENPs) are increasingly detected in water supply due to environmental release of ENPs as the by-products contained within the effluent of domestic and industrial run-off. The partial recycling of water laden with ENPs, albeit at ultra-low concentrations, may pose an uncharacterized threat to human health. In this study, we investigated the toxicity of three prevalent ENPs: zinc oxide, silver, and titanium dioxide over a wide range of concentrations that encompasses drinking water-relevant concentrations, to cellular systems representing oral and gastrointestinal tissues. Based on published in silico-predicted water-relevant ENPs concentration range from 100 pg/L to 100 µg/L, we detected no cytotoxicity to all the cellular systems. Significant cytotoxicity due to the NPs set in around 100 mg/L with decreasing extent of toxicity from zinc oxide to silver to titanium dioxide NPs. We also found that noncytotoxic zinc oxide NPs level of 10 mg/L could elevate the intracellular oxidative stress. The threshold concentrations of NPs that induced cytotoxic effect are at least two to five orders of magnitude higher than the permissible concentrations of the respective metals and metal oxides in drinking water. Based on these findings, the current estimated levels of NPs in potable water pose little cytotoxic threat to the human oral and gastrointestinal systems within our experimental boundaries.

  10. Recombinant human arginase I immobilized on gold and silver nanoparticles: preparation and properties

    Directory of Open Access Journals (Sweden)

    Natalia Stasyuk

    2011-07-01

    Full Text Available Metal nanoparticles (NPs, such as gold (Au and silver (Ag, are important for chemistry, physics, and biology due to their unique optical, electrical, and photothermal properties. Such NPs are widely used for immobilization of various bioactive substances, including peptides, enzymes, antibodies and DNA. The synthesis of silver and gold nanoparticles was carried out by reduction of silver nitrate by glucose and reduction of tetrachloroauric acid by sodium citrate, respectively. The size and structure of the AgNPs and AuNPs were characterized using TEM, AFM and XRD methods. The average size of the AgNPs and AuNPs was between 8 and 15 nm. Recombinant arginase I was immobilized using the carbodiimidepentafluorophenol method on the surface of NPs functionalized with ω-mercaptohexadecanoic acid. It was shown that recombinant human liver arginase I isolated from the yeast Hansenula polymorpha maintains satisfactory stability after immobilization on both NPs. The immobilized arginase retained 40% of its activity on the surface of AuNPs and 25% on AgNPs compared to the free arginase after storage at +4 ºC during 25 days. The immobilized enzyme can be used for assay of arginine in pharmaceuticals, in food products and in blood.

  11. Preparation of novel silver nanoplates/graphene composite and their application in vanillin electrochemical detection.

    Science.gov (United States)

    Huang, Linhong; Hou, Keyu; Jia, Xiao; Pan, Haibo; Du, Min

    2014-05-01

    Hexagonal Ag nanoplates (NPs) were synthesized by polyvinylpyrrolidone (PVP) and trisodium citrate (TSC) which selectively absorbed to Ag (100) and Ag (111) surfaces, then were anchored to graphene (GN) to form novel Ag NPs/GN composite. The thickness of Ag NPs is ~4 nm and the length is 18-66 nm. Transmission electron microscopy (TEM) image shows that the plates are f-c-c crystals containing {111} facets on their two planar surfaces. Zeta potential indicated that the surface of Ag NPs/GN is negatively charged while vanillin is positively charged. Thus Ag NPs/GN modified on glass carbon electrodes (GCE) allowed abundant adsorption for vanillin and electron transfer between vanillin and Ag NPs/GN/GCE. Square wave voltammetry (SWV) results indicated that the over potential on Ag NPs/GN/GCE negatively shifts 52 mV than that on Ag NPs/GCE. Ag NPs/GN with enhanced surface area and good conductivity exhibited an excellent electrocatalytic activity toward the oxidation of vanillin. The corresponding linear range was estimated to be from 2 to 100 μM (R(2)=0.998), and the detection limit is 3.32×10(-7) M (S/N=3). The as-prepared vanillin sensor exhibits good selectivity and potential application in practical vanillin determination.

  12. Mercury- and silver-rich ferromanganese oxides, southern California Borderland: Deposit model and environmental implications

    Science.gov (United States)

    Hein, J.R.; Koschinsky, A.; McIntyre, B.R.

    2005-01-01

    Mercury- and silver-enriched ferromanganese oxide crusts were recovered at water depths of 1,750 tol,300 m from La Victoria knoll, located about 72 km off the coast of northern Baja California. No other ferromanganese precipitate found so far in the modern ocean basins is similarly enriched in Hg and Ag. The precipitates consist of submetallic gray, brecciated, Mn oxide layers overlain by brown earthy, laminated Fe-Mn oxide crusts. Both oxide types are rich in Hg (to 10 ppm) and Ag (to 5.5 ppm). The Mn-rich layers are composed of ??MnO2, with lesser amounts of 10A?? and 7A?? manganates, whereas the Mn phase in the Fe-Mn crusts is solely ??MnO2. The Fe phase in both layers is X-ray amorphous. Established criteria for distinguishing hydrothermal versus hydrogenetic crusts indicate that the Mn-rich layers are predominantly of low-temperature hydrothermal origin, whereas the Fe-Mn crusts are hydrogenetic, although there is some overlap in the source of chemical components in both types. La Victoria knoll is uplifted continental basement rock with basalt, andesite, and schist cropping out at the surface; the knoll may have an intrusive core. The Hg and Ag were derived from leaching by hydrothermal fluids of organic matter-rich sediments in basins adjacent to La Victoria knoll and, to a lesser extent, from continental basement rocks underlying the knoll and adjacent basins. Both rock types are notably enriched in Ag and Hg. Faults were the main fluid transport pathway, and hydrothermal circulation was driven by high heat flow associated with thinned crust. Other elements derived from the hydrothermal fluids include Tl, Cd, Cr, and Li. The main host for Hg and Ag is FeOOH, although MnO2 likely hosts some of the Ag. Minor sulfide and barite also may contain small amounts of these metals. Possible analogs in the geologic record for this deposit type are found in the Basin and Range province of the western United States and Mexico. The discovery highlights the fact that

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

    Science.gov (United States)

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

    2015-11-01

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

  14. Preparation and catalytic properties of tungsten oxides with different morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Bi Yunfei, E-mail: beiyf2003@yahoo.com.cn [Research Institute of Petroleum Processing, SINOPEC, 18 Xue Yuan Road, 100083 Beijing (China); Li Dadong; Nie Hong [Research Institute of Petroleum Processing, SINOPEC, 18 Xue Yuan Road, 100083 Beijing (China)

    2010-09-01

    Tungsten oxides with different morphologies including platelet-like sheets, nanobelts, and nanoparticles have been successfully prepared by changing the ions in the synthetic solution. Transmission electron microscopy, X-ray diffraction, Fourier-transform infrared analysis and N{sub 2} adsorption were employed to reveal the morphological evolution, and results show that the morphological evolution can be attributed to the alteration of coordination environment of tungstenic cations contained in the synthetic solution. Furthermore, these products have been applied into hydrodesulfurization measurement to investigate the relationship between the morphologies of tungsten oxides and their catalytic properties. It is concluded that the catalysts originating from nanobelt-like tungsten oxides have highest catalytic activity and excellent selectivity due to their scrolled character and strong metallic edges.

  15. Interactions between suspension characteristics and physicochemical properties of silver and copper oxide nanoparticles: a case study for optimizing nanoparticle stock suspensions using a central composite design.

    Science.gov (United States)

    Son, Jino; Vavra, Janna; Li, Yusong; Seymour, Megan; Forbes, Valery

    2015-04-01

    The preparation of a stable nanoparticle stock suspension is the first step in nanotoxicological studies, but how different preparation methods influence the physicochemical properties of nanoparticles in a solution, even in Milli-Q water, is often under-appreciated. In this study, a systematic approach using a central composite design (CCD) was employed to investigate the effects of sonication time and suspension concentration on the physicochemical properties (i.e. hydrodynamic diameter, zeta potential and ion dissolution) of silver (Ag) and copper oxide (CuO) nanoparticles (NPs) and to identify optimal conditions for suspension preparation in Milli-Q water; defined as giving the smallest particle sizes, highest suspension stability and lowest ion dissolution. Indeed, all the physicochemical properties of AgNPs and CuONPs varied dramatically depending on how the stock suspensions were prepared and differed profoundly between nanoparticle types, indicating the importance of suspension preparation. Moreover, the physicochemical properties of AgNPs and CuONPs, at least in simple media (Milli-Q water), behaved in predictable ways as a function of sonication time and suspension concentration, confirming the validity of our models. Overall, the approach allows systematic assessment of the influence of various factors on key properties of nanoparticle suspensions, which will facilitate optimization of the preparation of nanoparticle stock suspensions and improve the reproducibility of nanotoxicological results. We recommend that further attention be given to details of stock suspension preparation before conducting nanotoxicological studies as these can have an important influence on the behavior and subsequent toxicity of nanoparticles.

  16. In-vitro anticancer and antimicrobial activities of PLGA/silver nanofiber composites prepared by electrospinning.

    Science.gov (United States)

    Almajhdi, Fahad N; Fouad, H; Khalil, Khalil Abdelrazek; Awad, Hanem M; Mohamed, Sahar H S; Elsarnagawy, T; Albarrag, Ahmed M; Al-Jassir, Fawzi F; Abdo, Hany S

    2014-04-01

    In the present work, a series of 0, 1 and 7 wt% silver nano-particles (Ag NPs) incorporated poly lactic-co-glycolic acid (PLGA) nano-fibers were synthesized by the electrospinning process. The PLGA/Ag nano-fibers sheets were characterized using SEM, TEM and DSC analyses. The three synthesized PLGA/silver nano-fiber composites were screened for anticancer activity against liver cancer cell line using MTT and LDH assays. The anticancer activity of PLGA nano-fibers showed a remarkable improvement due to increasing the concentration of the Ag NPs. In addition to the given result, PLGA nano-fibers did not show any cytotoxic effect. However, PLGA nano-fibers that contain 1 % nano silver showed anticancer activity of 8.8 %, through increasing the concentration of the nano silver to 7 % onto PLGA nano-fibers, the anticancer activity was enhanced to a 67.6 %. Furthermore, the antibacterial activities of these three nano-fibers, against the five bacteria strains namely; E.coli o157:H7 ATCC 51659, Staphylococcus aureus ATCC 13565, Bacillus cereus EMCC 1080, Listeria monocytogenes EMCC 1875 and Salmonella typhimurium ATCC25566 using the disc diffusion method, were evaluated. Sample with an enhanced inhibitory effect was PLGA/Ag NPs (7 %) which inhibited all strains (inhibition zone diameter 10 mm); PLGA/Ag NPs (1 %) sample inhibited only one strain (B. cereus) with zone diameter 8 mm. The PLGA nano-fiber sample has not shown any antimicrobial activity. Based on the anticancer as well as the antimicrobial results in this study, it can be postulated that: PLGA nanofibers containing 7 % nano silver are suitable as anticancer- and antibiotic-drug delivery systems, as they will increase the anticancer as well as the antibiotic drug potency without cytotoxicity effect on the normal cells. These findings also suggest that Ag NPs, of the size (5-10 nm) evaluated in the present study, are appropriate for therapeutic application from a safety standpoint.

  17. Reduced graphene oxide-silver nanoparticle composite as visible light photocatalyst for degradation of colorless endocrine disruptors.

    Science.gov (United States)

    Bhunia, Susanta Kumar; Jana, Nikhil R

    2014-11-26

    Sunlight-induced degradation of organic pollutants is an ideal approach for environmental pollution control and wastewater treatment. Although a variety of photocatalysts have been designed toward this goal, efficient degradation of colorless organic pollutants by visible light is a challenging issue. Here, we show that a reduced graphene oxide (rGO)-based composite with silver nanoparticle (rGO-Ag) can act as an efficient visible-light photocatalyst for the degradation of colorless organic pollutants. We have developed a simple, large-scale synthesis method for rGO-Ag and used it for the degradation of three well-known endocrine disruptors (phenol, bisphenol A, and atrazine) under UV and visible light. It is found that photocatalytic efficiency by rGO-Ag under visible light is significantly higher compared to that of rGO or silver nanoparticles. It is proposed that Ag nanoparticles offer visible-light-induced excitation of silver plasmons, and conductive rGO offers efficient charge separation and thus induces oxidative degradation of the organic pollutant. This approach can be extended for sunlight-induced degradation of different organic pollutants.

  18. High-Performance Silver Window Electrodes for Top-Illuminated Organic Photovoltaics Using an Organo-molybdenum Oxide Bronze Interlayer.

    Science.gov (United States)

    Tyler, Martin S; Walker, Marc; Hatton, Ross A

    2016-05-18

    We report an organo-molybdenumn oxide bronze that enables the fabrication of high-performance silver window electrodes for top-illuminated solution processed organic photovoltaics without complicating the process of device fabrication. This hybrid material combines the function of wide-band-gap interlayer for efficient hole extraction with the role of metal electrode seed layer, enabling the fabrication of highly transparent, low-sheet-resistance silver window electrodes. Additionally it is also processed from ethanol, which ensures orthogonality with a large range of solution processed organic semiconductors. The key organic component is the low cost small molecule 3-mercaptopropionic acid, which (i) promotes metal film formation and imparts robustness at low metal thickness, (ii) reduces the contact resistance at the Ag/molybdenumn oxide bronze interface, (iii) and greatly improves the film forming properties. Silver electrodes with a thickness of 8 nm deposited by simple vacuum evaporation onto this hybrid interlayer have a sheet resistance as low as 9.7 Ohms per square and mean transparency ∼80% over the wavelength range 400-900 nm without the aid of an antireflecting layer, which makes them well-matched to the needs of organic photovoltaics and applicable to perovskite photovoltaics. The application of this hybrid material is demonstrated in two types of top-illuminated organic photovoltaic devices.

  19. PREPARATION OF ZINC OXIDE AND POLY-ETHYLENE OXIDE COMPOSITE MEMBRANES AND THEIR PHASE RELATIONSHIP

    OpenAIRE

    JESÚS FABIAN JURADO; CARLOS VARGAS HERNÁNDEZ; RUBÉN ANTONIO VARGAS

    2012-01-01

    Zinc oxide and organic polymer (poly-ethylene oxide) based nanocomposite membranes were prepared and their phase relationship investigated. The composites were characterized by XRD, Raman scattering, DSC, and impedance spectroscopy analysis. It was found that embedding inorganic nanoparticles of ZnO into the polymer matrix of PEO allowed for some crystallinity formation, and cross-linking of the polymer composites during annealing or synthesis. The XRD and Raman scattering results show more d...

  20. Preparation of silver nano-particles immobilized onto chitin nano-crystals and their application to cellulose paper for imparting antimicrobial activity.

    Science.gov (United States)

    Li, Zhihan; Zhang, Ming; Cheng, Dong; Yang, Rendang

    2016-10-20

    Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5-12nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus.

  1. PHOTOCHEMICAL PREPARATION OF GREEN SILVER AND YELLOW SILVER COLLOID AND THEIR RESONANCE SCATTERING SPECTROSCOPIC STUDY%绿色和黄色银胶的光化学制备及其共振散射光谱研究

    Institute of Scientific and Technical Information of China (English)

    钟福新; 蒋治良; 李廷盛; 李芳; 梁宏

    2001-01-01

    The green silver colloid and yellow silver colloid were prepared by two-step photochemical procedure and UV photochemical procedure respectively.Their sizes measured by TEM are 100 nm and 40 nm respectively.The green silver solloid exhibits two absorption peaks at 393.9 nm and 713.3 nm,The absorption peak of yellow silver colloid is at 419.3 nm.They have a maxium resonance scattering peak at 470 nm,and the green silver colloid has other two resonance scattering peaks at 340 nm and 680nm.%研究了不同光源、光照时间、反应物浓度等对绿色银胶形成的影响,分别制备了绿色银胶和黄色银胶.透射电镜显示,它们的平均粒径分别为100 nm和40 nm.绿色银胶在393.9 nm和713.3 nm处有两个吸收峰;黄色银胶在419.3 nm处有一较宽的吸收峰.它们的最强共振散射峰位于470 nm处;绿色银胶在340 nm和680 nm还有两个小共振峰.

  2. A facile approach to prepare silicon-based Pt-Ag tubular dendritic nano-forests (tDNFs) for solar-light-enhanced methanol oxidation reaction

    Science.gov (United States)

    Lin, Chun-Ting; Shiao, Ming-Hua; Chang, Mao-Nan; Chu, Nancy; Chen, Yu-Wei; Peng, Yu-Hsuan; Liao, Bo-Huei; Huang, Hung Ji; Hsiao, Chien-Nan; Tseng, Fan-Gang

    2015-02-01

    In this paper, a facile two-step Galvanic replacement reaction (GRR) is proposed to prepare Pt-Ag tubular dendritic nano-forests (tDNFs) in ambient condition for enhancing methanol oxidation reaction (MOR) under solar illumination. In the first GRR, a homogeneous layer of silver dendritic nano-forests (DNFs) with 10 μm in thickness was grown on Si wafer in 5 min in silver nitride (AgNO3) and buffer oxide etchant (BOE) solution. In the second GRR, we utilized chloroplatinic acid (H2PtCl6) as the precursor for platinum (Pt) deposition to further transform the prepared Ag DNFs into Pt-Ag tDNFs. The catalytic performance and solar response of the Pt-Ag tDNFs toward methanol electro-oxidation are also studied by cyclic voltammetry (CV) and chronoamperometry (CA). The methanol oxidation current was boosted by 6.4% under solar illumination on the Pt-Ag tDNFs due to the induced localized surface plasmon resonance (LSPR) on the dendritic structure. Current results provide a cost-effective and facile approach to prepare solar-driven metallic electrodes potentially applicable to photo-electro-chemical fuel cells.

  3. Influence of Experimental Conditions on Deposition of Silver Nanoparticles Onto Surface of Graphene Oxide / Wpływ Warunków Eksperymentalnych Na Proces Osadzania Nanocząstek Srebra Na Powierzchni Tlenku Grafenu

    Directory of Open Access Journals (Sweden)

    Wojnicki M.

    2015-12-01

    Full Text Available Present work describes the influence of silver nanoparticles precursor form as well as the impact of graphene oxide initial concentration on deposition of the silver nanoparticles onto graphene oxide. Borane dimethylamine complex (DMAB was used as the reducing agent. It was observed that application of silver ammonia complexes as the silver nanoparticles precursor as well as alkaline solution effect in higher quantity of deposited AgNPs in comparison to deposition process with the use of silver(I nitrate in acidic solution.

  4. Silver nanoparticles deposited on anodic aluminum oxide template using magnetron sputtering for surface-enhanced Raman scattering substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wong-ek, Krongkamol [Nanoscience and Technology Program, Chulalongkorn University, Bangkok 10330 (Thailand); Eiamchai, Pitak; Horprathum, Mati; Patthanasettakul, Viyapol [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Limnonthakul, Puenisara [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Chindaudom, Pongpan [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Nuntawong, Noppadon, E-mail: noppadon.nuntawong@nectec.or.t [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand)

    2010-09-30

    Low-cost and highly sensitive surface-enhanced Raman scattering (SERS) substrates have been fabricated by a simple anodizing process and a magnetron sputtering deposition. The substrates, which consist of silver nanoparticles embedded on anodic aluminum oxide (AAO) templates, are investigated by a scanning electron microscope and a confocal Raman spectroscopy. The SERS activities are demonstrated by Raman scattering from adsorbed solutions of methylene blue and pyridine on the SERS substrate surface. The most optimized SERS substrate contains the silver nanoparticles, with a size distribution of 10-30 nm, deposited on the AAO template. From a calculation, the SERS enhancement factor is as high as 8.5 x 10{sup 7}, which suggests strong potentials for direct applications in the chemical detection and analyses.

  5. Influences of Silver-Doping on the Crystal Structure, Morphology and Photocatalytic Activity of TiO2 Nanofibers

    DEFF Research Database (Denmark)

    Barakat, Nasser A. M.; Kanjwal, Muzafar Ahmed; Al-Deyab, Salem S.

    2011-01-01

    activity of titanium oxide nanofibers has been studied. Sil-ver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600°C. The results affirmed formation of silver......-doped TiO2 nanofibers composed of anatase and rutile when the silver nitrate content in the original electrospun solution was more than 3 wt%. The rutile phase content was directly proportional with the AgNO3 concentration in the electrospun solution. Negative impact of the silver-doping on the nanofibrous...

  6. DNA-stabilized silver nanoclusters and carbon nanoparticles oxide: A sensitive platform for label-free fluorescence turn-on detection of HIV-DNA sequences.

    Science.gov (United States)

    Ye, Yu-Dan; Xia, Li; Xu, Dang-Dang; Xing, Xiao-Jing; Pang, Dai-Wen; Tang, Hong-Wu

    2016-11-15

    Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label-free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1-50nM with a detection limit of 0.40nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Removal and recovery of toxic silver ion using deep-sea bacterial generated biogenic manganese oxides.

    Science.gov (United States)

    Pei, Yuanjun; Chen, Xiao; Xiong, Dandan; Liao, Shuijiao; Wang, Gejiao

    2013-01-01

    Products containing silver ion (Ag(+)) are widely used, leading to a large amount of Ag(+)-containing waste. The deep-sea manganese-oxidizing bacterium Marinobacter sp. MnI7-9 efficiently oxidizes Mn(2+) to generate biogenic Mn oxide (BMO). The potential of BMO for recovering metal ions by adsorption has been investigated for some ions but not for Ag(+). The main aim of this study was to develop effective methods for adsorbing and recovering Ag using BMO produced by Marinobacter sp. MnI7-9. In addition, the adsorption mechanism was determined using X-ray photoelectron spectroscopy analysis, specific surface area analysis, adsorption kinetics and thermodynamics. The results showed that BMO had a higher adsorption capacity for Ag(+) compared to the chemical synthesized MnO2 (CMO). The isothermal absorption curves of BMO and CMO both fit the Langmuir model well and the maximum adsorption capacities at 28°C were 8.097 mmol/g and 0.787 mmol/g, for BMO and CMO, respectively. The change in enthalpy (ΔH(θ)) for BMO was 59.69 kJ/mol indicating that it acts primarily by chemical adsorption. The change in free energy (ΔG(θ)) for BMO was negative, which suggests that the adsorption occurs spontaneously. Ag(+) adsorption by BMO was driven by entropy based on the positive ΔS(θ) values. The Ag(+) adsorption kinetics by BMO fit the pseudo-second order model and the apparent activation energy of Ea is 21.72 kJ/mol. X-ray photoelectron spectroscopy analysis showed that 15.29% Ag(+) adsorbed by BMO was transferred to Ag(0) and meant that redox reaction had happened during the adsorption. Desorption using nitric acid and Na2S completely recovered the Ag. The results show that BMO produced by strain MnI7-9 has potential for bioremediation and reutilization of Ag(+)-containing waste.

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

    Science.gov (United States)

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

    2014-12-10

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

  9. Preparation of novel silver nanoplates/graphene composite and their application in vanillin electrochemical detection

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Linhong [Fujian Key Lab of Medical Instrument and Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Fuzhou University, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Hou, Keyu; Jia, Xiao [Institute of Research for Functional Materials, Fuzhou University, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Pan, Haibo, E-mail: hbpan@fzu.edu.cn [Fujian Key Lab of Medical Instrument and Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Institute of Research for Functional Materials, Fuzhou University, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); College of Chemistry and Chemical Engineering, Qishan Campus, Fuzhou University, Fuzhou, Fujian 350108 (China); Du, Min [Fujian Key Lab of Medical Instrument and Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2014-05-01

    Hexagonal Ag nanoplates (NPs) were synthesized by polyvinylpyrrolidone (PVP) and trisodium citrate (TSC) which selectively absorbed to Ag (100) and Ag (111) surfaces, then were anchored to graphene (GN) to form novel Ag NPs/GN composite. The thickness of Ag NPs is ∼ 4 nm and the length is 18–66 nm. Transmission electron microscopy (TEM) image shows that the plates are f-c-c crystals containing {111} facets on their two planar surfaces. Zeta potential indicated that the surface of Ag NPs/GN is negatively charged while vanillin is positively charged. Thus Ag NPs/GN modified on glass carbon electrodes (GCE) allowed abundant adsorption for vanillin and electron transfer between vanillin and Ag NPs/GN/GCE. Square wave voltammetry (SWV) results indicated that the over potential on Ag NPs/GN/GCE negatively shifts 52 mV than that on Ag NPs/GCE. Ag NPs/GN with enhanced surface area and good conductivity exhibited an excellent electrocatalytic activity toward the oxidation of vanillin. The corresponding linear range was estimated to be from 2 to 100 μM (R{sup 2} = 0.998), and the detection limit is 3.32 × 10{sup −7} M (S/N = 3). The as-prepared vanillin sensor exhibits good selectivity and potential application in practical vanillin determination. - Highlights: • Hexagonal Ag nanoplates were synthesized by controlling of PVP and trisodium citrate. • Ag nanoplates/GN composite allowed adsorption and electron transfer of vanillin. • The composite with good dispersion exhibits enhanced surface area and good catalysis. • Vanillin on the Ag NPs/GN/GCE shows high sensitivity and selectivity.

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

    Directory of Open Access Journals (Sweden)

    Matthew C. Achilonu

    2015-01-01

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

  11. Preparation of metal oxide nanoparticles in ionic liquid medium

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Cabo, Borja; Rodil, Eva; Soto, Ana; Arce, Alberto, E-mail: alberto.arce@usc.es [University of Santiago de Compostela, Department of Chemical Engineering, School of Engineering (Spain)

    2012-07-15

    In the present study, a facile, rapid, and environmentally friendly method was used for the preparation of metal oxide nanoparticles in an ionic liquid medium. This technique involves mixing and heating the corresponding powder material (cadmium oxide, anatase, and hematite) and the selected ionic liquid (trihexyl(tetradecyl)phosphonium chloride, [P{sub 6,6,6,14}]Cl), without any other precursors or solvents. The confirmation of the existence of nanoparticles in the ionic liquid was carried out using UV-Vis absorption spectroscopy, and its concentration was determined by X-ray fluorescence. In order to analyze the shape and size distribution, transmission electron microscopy and a ZetaSizer (DLS technique) were used; finding out that the size of the hematite nanoparticles was 10-55 nm. Nevertheless, for the cadmium oxide and the anatase nanoparticles, the size was between 2 and 15 nm. The composition of the prepared nanoparticles was studied by Raman spectroscopy. The structure of solids did not suffer any modification in their transformation to the nanoscale, as concluded from the X-ray powder diffraction analysis.

  12. Preparation, characterization, and electrochemical properties of lithium vanadium oxide nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zhuo Shujuan [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China); Anhui Key Laboratory of Functional Molecular Solids, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Shao Mingwang, E-mail: mwshao@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China); Zhou Qing; Liao Fan [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123 (China)

    2011-07-15

    Graphical abstract: Display Omitted Highlights: > The lithium ions can easily move between the layers of lithium vanadium oxide. > It can highly increase the electron transfer between the electrode and dopamine. > The reversibility of electrochemical process was significantly improved. - Abstract: Highly uniform lithium vanadium oxide nanoribbons were successfully prepared in large quantities using a facile hydrothermal approach without employing any surfactants or templates. The as-prepared products were up to hundreds of micrometers in length, about 200 nm in width, and 20 nm in thickness. These nanoribbons and nafion composite were employed to modify glassy carbon electrode, which displayed excellent electrochemical sensitivity and rapid response in detecting dopamine in phosphate buffer solution. Lithium ions can greatly increase the electron transfer between the electrode and biological materials, and significantly increase the reversibility of electrochemical process. A linear relationship between the concentrations of dopamine and its oxidation peak currents was obtained. The linear range for the detection of dopamine was 2.0 x 10{sup -6} to 1.0 x 10{sup -4} M with a detection limit of 1.0 x 10{sup -7} M. In addition, the good reproducibility and long-term stability of the sensor make it valuable for further application.

  13. Effective Synthesis and Recovery of Silver Nanowires Prepared by Tapered Continuous Flow Reactor for Flexible and Transparent Conducting Electrode

    Directory of Open Access Journals (Sweden)

    Hyung Duk Yun

    2016-01-01

    Full Text Available Silver nanowires (AgNWs with high aspect ratio were obtained utilizing a tapered tubular reactor by the polyol process. The tapered tubular type flow reactor allowed us to obtain nanowires in high yield without defects that is generally encountered in a closed reactor due to excessive shearing for a long time. After reaction the AgNWs were precipitated in the aqueous solution with the aid of a hydrogen bond breaker and were recovered effectively without using a high-cost centrifugation process. Dispersion of the AgNWs were used to prepare transparent conducting electrode (TCE films by a spray coating method, which showed 86% transmittance and 90 Ωsq−1 sheet resistance.

  14. Ultralow Loading of Silver Nanoparticles on Mn2O3 Nanowires Derived with Molten Salts: A High-Efficiency Catalyst for the Oxidative Removal of Toluene.

    Science.gov (United States)

    Deng, Jiguang; He, Shengnan; Xie, Shaohua; Yang, Huanggen; Liu, Yuxi; Guo, Guangsheng; Dai, Hongxing

    2015-09-15

    Using a mixture of NaNO3 and NaF as molten salt and MnSO4 and AgNO3 as metal precursors, 0.13 wt % Ag/Mn2O3 nanowires (0.13Ag/Mn2O3-ms) were fabricated after calcination at 420 °C for 2 h. Compared to the counterparts derived via the impregnation and poly(vinyl alcohol)-protected reduction routes as well as the bulk Mn2O3-supported silver catalyst, 0.13Ag/Mn2O3-ms exhibited a much higher catalytic activity for toluene oxidation. At a toluene/oxygen molar ratio of 1/400 and a space velocity of 40,000 mL/(g h), toluene could be completely oxidized into CO2 and H2O at 220 °C over the 0.13Ag/Mn2O3-ms catalyst. Furthermore, the toluene consumption rate per gram of noble metal over 0.13Ag/Mn2O3-ms was dozens of times as high as that over the supported Au or AuPd alloy catalysts reported in our previous works. It is concluded that the excellent catalytic activity of 0.13Ag/Mn2O3-ms was associated with its high dispersion of silver nanoparticles on the surface of Mn2O3 nanowires and good low-temperature reducibility. Due to high efficiency, good stability, low cost, and convenient preparation, 0.13Ag/Mn2O3-ms is a promising catalyst for the practical removal of volatile organic compounds.

  15. Oxidative stress generation of silver nanoparticles in three bacterial genera and its relationship with the antimicrobial activity.

    Science.gov (United States)

    Quinteros, M A; Cano Aristizábal, V; Dalmasso, P R; Paraje, M G; Páez, P L

    2016-10-01

    Oxidative stress is a condition caused by the high intracellular concentrations of reactive oxygen species (ROS) that includes superoxide anion radicals, hydroxyl radicals and hydrogen peroxide. Nanoparticles could cause rapid generation of free radicals by redox reactions. ROS can react directly with membrane lipids, proteins and DNA and are normally scavenged by antioxidants that are capable of neutralizing; however, elevated concentrations of ROS in bacterial cells can result in oxidative stress. The aim of this work was contribute to the knowledge of action mechanism of silver nanoparticles (Ag-NPs) and their relation to the generation of oxidative stress in bacteria. We demonstrated that Ag-NPs generated oxidative stress in Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa mediated by the increment of ROS and this increase correlated with a better antimicrobial activity. On the other hand, we showed that the oxidative stress caused by the Ag-NPs biosynthesized was associated to a variation in the level of reactive nitrogen intermediates (RNI). Oxidative stress in bacteria can result from disruption of the electronic transport chain due to the high affinity of Ag-NPs for the cell membrane. This imbalance in the oxidative stress was evidentiated by a macromolecular oxidation at level of DNA, lipids and proteins in E. coli exposed to Ag-NPs. The formation of ROS and RNI by Ag-NPs may also be considered to explain the bacterial death.

  16. Characterization and Antimicrobial Property of Poly(Acrylic Acid) Nanogel Containing Silver Particle Prepared by Electron Beam

    OpenAIRE

    Jong-Bae Choi; Jong-Seok Park; Myung-Seob Khil; Hui-Jeong Gwon; Youn-Mook Lim; Sung-In Jeong; Young-Min Shin; Young-Chang Nho

    2013-01-01

    In this study, we developed a one step process to synthesize nanogel containing silver nanoparticles involving electron beam irradiation. Water-soluble silver nitrate powder is dissolved in the distilled water and then poly(acrylic acid) (PAAc) and hexane are put into this silver nitrate solution. These samples are irradiated by an electron beam to make the PAAc nanogels containing silver nanoparticles (Ag/PAAc nanogels). The nanoparticles were characterized by scanning electron microscopy (S...

  17. 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...

  18. Preparation and properties of magnetic iron oxide nanotubes

    Institute of Scientific and Technical Information of China (English)

    Baoliang Lv; Yao Xu; Dong Wu; Yuhan Sun

    2008-01-01

    Magnetite (Fe3O4) nanotubes were prepared by reducing synthesized hematite (α-Fe2O3) nanotubes in 5% H2+95% Ar atmosphere,and then maghemite (γ-Fe2O3) nanotubes were obtained by re-oxidizing the Fe3O4 nanotubes.The nanotube structure was kept from collapsing or sintering throughout the high temperature reducing and re-oxidizing processes.The coercivities of the Fe3O4 and γ-Fe2O3 nanotubes synthesized were found to be 340.22 Oe and 342.23 Oe,respectively,both higher than other nanostructures with the same phase and of similar size.Both adsorbed phosphate and the nanotube structure are considered responsible for this high coercivity.

  19. The photoluminescence properties of zinc oxide nanofibres prepared by electrospinning

    Science.gov (United States)

    Viswanathamurthi, Periasamy; Bhattarai, Narayan; Kim, Hak Yong; Lee, Douk Rae

    2004-03-01

    The morphology and optical properties of zinc oxide fibres with diameters in the nanometre to micrometre range are reported. The PVA/zinc acetate organic/inorganic hybrid nanofibres were successfully prepared by electrospinning using polyvinyl alcohol (PVA) and zinc acetate. Pure zinc oxide fibres were obtained by high-temperature calcination of the hybrid fibres in air. The nanofibres were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffractometry (XRD) and Raman spectroscopy. The photoluminescence spectra under excitation at 325 nm showed an ultraviolet emission at 3.13 eV and a green emission at 2.21 eV. These nanofibres could be used as light emitting devices in nanoscale optoelectronic applications.

  20. Simultaneous treatment of washing, disinfection and sterilization using ultrasonic levitation, silver electrolysis and ozone oxidation.

    Science.gov (United States)

    Ueda, Toyotoshi; Hara, Masanori; Odagawa, Ikumi; Shigihara, Takanori

    2009-03-01

    A new type of ultrasonic washer-disinfector-sterilizer, able to clean, disinfect and sterilize most kinds of reusable medical devices, has been developed by using the ultrasonic levitation function with umbrella-shape oscillators and ozone bubbling together with sterilization carried out by silver electrolysis. We have examined the biomedical and physicochemical performance of this instrument. Prokariotic and gram-negative Escherichia coli and eukariotic Saccharomyces cerevisiae were killed by silver electrolysis in 18 min and 1 min, respectively. Prokariotic and gram-positive Geobacillus stearothermophilus and Bacillus atrophaeus, which are most resistant to autoclave and gas sterilization, respectively, were killed by silver electrolysis within 20 min. Prokariotic and gram-negative Pseudomonas aeruginosa was also killed by silver electrolysis in 10 min. The intensity distribution of the ultrasonic levitation waves was homogeneous throughout the tank. The concentration of ozone gas was 2.57 mg/ kg. The concentration of dissolved silver ions was around 0.17 mg/L. The disulfide bond in proteins was confirmed to be destroyed by silver electrolysis.

  1. Stability of zinc oxide nanofluids prepared with aggregated nanocrystalline powders.

    Science.gov (United States)

    Leonard, J P; Chung, S J; Nettleship, I; Soong, Y; Martello, D V; Chyu, M K

    2008-12-01

    Aqueous zinc oxide (ZnO) suspensions were prepared using a two-step preparation method in which an aggregated nanocrystalline ZnO powder was dispersed in water using a polyelectrolyte. The fluid showed anomalously high thermal conductivity when compared with the Maxwell and Hamilton-Crosser predictions. However, analysis of the particle size distribution showed that the fluid contained aggregated 20 nm crystallites of ZnO with a high volume fraction of particles larger than 100 nm. Sedimentation experiments revealed that particles settled out of the stationary fluid over times ranging from 0.1 hours to well over 10,000 hours. The size of the particles remaining in suspension agreed well with predictions made using Stoke's law, suggesting flocculation was not occurring in the fluids. Finally, a new concept of nanofluid stability is introduced based on the height of the fluid, sedimentation, Brownian motion and the kinetic energy of the particles.

  2. Structure of silicon oxide films prepared by vacuum deposition

    Science.gov (United States)

    Saito, Yoshio; Kaito, Chihiro; Nishio, Kenzo; Naiki, Toshio

    1985-05-01

    The structure of thin silicon oxide films 5 nm in thickness, which were prepared by electron beam evaporation of SiO 2 glass onto a NaCl substrate, has been examined by high resolution electron microscopy and diffraction. Although the films which were prepared with substrate temperatures ranging from room up to 400°C gave rise to amorphous haloes, lattice fringes in areas 1-2 nm in extent were, however, seen in the micrographs. It is shown that the film is composed of α-quartz micro-crystallites. Crystals of α-cristobalite with sizes of several tens of nanometers appeared at a substrate temperature of 500°C. At a substrate temperature of 600°C, β-cristobalite crystals with sizes of several tens of nanometers appeared. The structural changes due to the substrate temperature were attributed to incorporation of sodium atoms from the substrate into the SiO 2 film.

  3. Influence of daylight on the fate of silver and zinc oxide nanoparticles in natural aquatic environments.

    Science.gov (United States)

    Odzak, Niksa; Kistler, David; Sigg, Laura

    2017-07-01

    Nanoparticles, such as silver (Ag-NP) and zinc oxide (ZnO-NP), are increasingly used in many consumer products. These nanoparticles (NPs) will likely be exposed to the aquatic environment (rain, river, lake water) and to light (visible and UV) in the products where they are applied, or after those products are discharged. Dissolution of Ag-NP and ZnO-NP is an important process because the dissolved Ag(+) and Zn(2+) are readily available and toxic for aquatic organisms. The objective of this study was to investigate the role of daylight (UV and visible) for the fate of engineered Ag-NP and ZnO-NPs in different types of natural waters. Ag-NP and ZnO-NP were exposed to rainwater, river Rhine, and lake waters (Greifen, Lucerne, Cristallina, Gruère) under different light conditions (no light, UV 300-400 nm and visible light 400-700 nm) for up to 8 days. Stronger agglomeration of Ag-NP was observed in the waters with higher ionic strength in comparison to those with lower ionic strength. Visible light tended to increase the dissolution of Ag-NP under most natural water conditions in comparison to dark conditions, whereas UV-light led to decreased dissolved Ag(+) after longer exposure time. These effects illustrate the dynamic interactions of Ag-NP with light, which may lead both to increased oxidation and to increased reduction of Ag(+) by organic compounds under UV-light. In the case of ZnO-NP, agglomeration occurred at higher ionic strength, but the effects of pH were predominant for dissolution, which occurred up to concentrations close to the solubility limit of ZnO(s) at pH around 8.2 and to nearly complete dissolution of ZnO-NP at lower pH (pH 4.8-6.5), with both visible and UV-light facilitating dissolution. This study thus shows that light conditions play an important role in the dissolution processes of nanoparticles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Polyhedral C2@Agn cages distorted by ancillary pyridine N-oxide ligands in silver-acetylenediide complexes.

    Science.gov (United States)

    Zhao, Xiao-Li; Zhang, Lin-Ping; Mak, Thomas C W

    2006-07-01

    Reactions of the pyridine N-oxide ligands L, L2 and L3 with the silver acetylenediide-containing system under hydrothermal conditions gave rise to four silver-acetylenediide complexes bearing interesting C2@Agn motifs: (Ag2C2)2(AgCF3CO2)8(L1)3.5 (1), (Ag2C2)2(AgCF3CO2)8(L2)2 (2), (Ag2C2)(AgCF3CO2)4(L3) (3) and [(Ag7(C2)(CF3SO3)3(L3)2(H2O)2] x 2CF3SO3 (4) (L = nicotinic acid N-oxide, L(1) = pyridine N-oxide, L2 = 1,2-bis(4-pyridyl)ethane N,N'-dioxide, L3 = 1,3-bis(4-pyridyl)propane N,N'-dioxide), which exhibit new distorted polyhedral C2@Agn cage motifs. Complex 1 has a pair of acetylenediide dianions encapsulated in a Ag(14) aggregate composed of three polyhedral parts, whereas 2 contains an irregular (C2)2@Ag13 double cage. In 3, the basic building unit is a centrosymmetric (C2)2@Ag12 double cage with each component single cage taking the shape of a highly distorted triangulated dodecahedron with one missing vertex. As to complex 4, the core is a C2@Ag7 single cage in the form of a slightly distorted monocapped trigonal prism with four cleaved edges that include all three vertical sides. Furthermore, in the silver-rich environment, the pyO-type ligands are induced to exhibit unprecedented coordination modes, such as the mu(5)-O,O,O,O',O' ligation mode of L2 in 2 and the mu4-O,O,O',O' mode of L3 in 3 and 4.

  5. Silver nanoparticles sensitized C60(Ag@C60) as efficient electrocatalysts for hydrazine oxidation: Implication for hydrogen generation reaction

    Science.gov (United States)

    Narwade, Shankar S.; Mulik, Balaji B.; Mali, Shivsharan M.; Sathe, Bhaskar R.

    2017-02-01

    Herein, we report the synthesis of silver nanoparticles (Ag NPs; 10 ± 0.5 nm) sensitized Fullerene (C60; 15 ±2 nm) nanocatalysts (Ag@C60) for the first time showing efficient electroatalytic activity for the oxidation of hydrazine demonstrating activity comparable to that of Pt in acidic, neutral and basic media. The performance is comparable with the best available electrocatalytic system and plays a vital role in the overall hydrogen generation reactions from hydrazine as a one of the fuel cell reaction. The materials are synthesized by a simple and scalable synthetic route involving acid functionalization of C60 followed by chemical reduction of Ag+ ions in ethylene glycol at high temperature. The distributation of Silver nanoparticles (Ag NPs) (morphological information) on C60, bonding, its crystal structure, along with activity towards hydrazine oxidation (electrocatalytic) is studied using TEM, XRD, UV-vis, XPS, FTIR and electrochemical (cyclic voltammetry) studies, respectively. The observed efficient electrocatalytic activity of the as-synthesized electrode is attributed to the co-operative response and associated structural defects due to their oxidative functionalization along with thier cooperative functioning at nanodimensions.

  6. Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.

    Science.gov (United States)

    Chen, Jing; Feng, Shaolong; Gao, Fang; Grant, Edward; Xu, Jie; Wang, Shuo; Huang, Qian; Lu, Xiaonan

    2015-04-01

    We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products.

  7. Preparation and characterization of HMSPP/MMT/silver nanocomposite films with antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Oliani, Washington Luiz; Komatsu, Luiz Gustavo Hiroki; Berenguer, Isabelle; Lugao, Ademar Benevolo; Parra, Duclerc Fernandes, E-mail: washoliani@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Lincopan, Nilton [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola de Farmacia. Dept. de Analises Clinicas; Rangari, Vijaya Kumar [Center For Advanced Materials Science and Engineering Tuskegee University, AL (United States)

    2015-07-01

    The aim of study was to use nanocomposites for bactericide packing for food. The polypropylene modified by irradiation in acetylene at dose of 12.5 kGy, also known as high-melt-strength-polypropylene (HMSPP), with montmorillonite (MMT) and silver nanoparticles (AgNPs) composed a mix to process by melt intercalation in a twin-screw extruder. As compatibilizer agent it has been used a propylene graft maleic anhydride copolymer (PP-g-MA). The nanocomposites were evaluated by Fourier Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and determination of antibacterial activity. The results indicate the formation of microstructures predominantly intercalated and flocculated. Further, the antibacterial properties of the films were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. (author)

  8. Corrosion protection of silver-based telescope mirrors using evaporated anti-oxidation overlayers and aluminum oxide films by atomic layer deposition

    Science.gov (United States)

    Fryauf, David M.; Phillips, Andrew C.; Kobayashi, Nobuhiko P.

    2016-09-01

    An urgent demand remains in astronomy for high-reflectivity silver mirrors that can withstand years of exposure in observatory environments. The University of California Observatories Astronomical Coatings Lab has undertaken development of protected silver coatings suitable for telescope mirrors that maintain high reflectivity at wavelengths from 340 nm through the mid-infrared spectrum. We present results on superior protective layers of transparent dielectrics produced by evaporation and atomic layer deposition. Several novel coating recipes have been developed with ion-assisted electron beam deposition (IAEBD) of various fluorides, oxides, and nitrides in combination with conformal layers of aluminum oxide (AlOx) deposited by ALD using trimethylaluminum as a metal precursor and water vapor as a reactant. Extending on our previous results demonstrating the superior durability of ALD-based AlOx top barrier layers over conventionally-deposited AlOx, this work investigates the effects on mirror barrier durability comparing different anti-oxidation materials on Ag with an identical AlOx top barrier layer deposited by ALD. Samples of coating recipes with different anti-oxidation layers undergo aggressive environmental testing, including high temperature/high humidity (HTHH), in which samples are exposed to an environment of 80% humidity at 80°C for ten days in a simple test set-up. While most samples show fairly successful endurance after HTHH testing, visible results suggest that MgAl2O4, Al2O3, and AlN anti-oxidation layers offer enhanced robust protection against chemical corrosion and moisture in an accelerated aging environment, which is attributed to superior adhesion and intermolecular bonding between the Al-based anti-oxidation layers and the AlOx top barrier layer. Mirror samples are further characterized by reflectivity/absorption before and after deposition of oxide coatings. We also show that the performance of the ALD-AlOx barrier layer depends in part

  9. Effects of oxidation on the defect of reduced graphene oxides in graphene preparation.

    Science.gov (United States)

    Hu, Yang; Song, Shaoxian; Lopez-Valdivieso, Alejandro

    2015-07-15

    The relationship between the defects of reduced graphene oxide (RGO) and the oxidation degree of graphite in the preparation of graphene with chemical conversion method has been studied in this work. This study was performed on an artificial graphite through the measurements of X ray diffraction, Raman spectroscopy and particle size analysis. The experimental results have shown that there indeed was a close relationship between the defects and the oxidation degree, which appeared in the form of S-type curve. Also, it was found that a low KMnO4 addition would lead to a partial oxidation of graphite, leaving defects mainly on the edges of RGO; with a high KMnO4 addition, the defects on RGO mostly appeared on the surfaces.

  10. Preparation and characterization of nanocrystalline cellulose/silver nanoparticles%纳米纤维素/银纳米粒子的制备和表征

    Institute of Scientific and Technical Information of China (English)

    王海英; 孟围; 刘志明

    2013-01-01

    以纳米纤维素(NCC)为分散剂,硼氢化钠为还原剂还原硝酸银,化学还原法制备纳米纤维素/银纳米粒子.m(Ag)/m (NCC)=5%制备的纳米纤维素/银纳米粒子,X射线衍射分析结果表明,纳米纤维素/银纳米粒子中NCC和银纳米粒子相互混合并未改变各自的晶型,纳米纤维素/银纳米粒子中银纳米粒子的晶粒尺寸为11.87nm,与透射电子显微镜(TEM)所测银纳米粒子直径(10nm)相近;热重分析结果表明,纳米纤维素/银纳米粒子的热稳定性较纳米纤维素稍有下降.透射电子显微镜(TEM)分析、紫外光谱分析、固含量分析、机理分析和抑菌活性分析结果表明,m(Ag)/m (NCC)=3%时制备的纳米纤维素/银纳米粒子对大肠杆菌和金黄色葡萄球菌均有抑制作用,且银纳米粒子在纳米纤维素/银纳米粒子中分散较均匀.%Nanocrystalline cellulose/silver nanoparticles was prepared by chemical reduction method with nanocrystalline cellulose(NCC) as dispersing agent, sodium borohydride as reductant of silver nitrate. For NCC/silver nanoparticles prepared with 5wt% of m (Ag)/m (NCC), X-ray diffraction analysis showed that crystalline type of NCC and silver nanoparticles for NCC/silver nanoparticles did not change respectively. Grain size of silver nanoparticles of NCC/silver nanoparticles was 11. 87nm,which was similar to silver nanoparticles diameter (10nm) measured by transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) results showed that thermal stability of NCC/silver nanoparticles decreased slightly compared with NCC. Transmission electron microscopy (TEM) analysis, UV-Vis absorption spectra analysis, solid content analysis, mechanism a-nalysis, and antibacterial activity analysis results showed that escherichia coli and staphylococcus aureus was separately inhibited by NCC/silver nanoparticles prepared with 3% of m (Ag)/m (NCC) and silver nanoparticles of NCC/silver nanoparticles were uniformly

  11. Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity

    Science.gov (United States)

    Phromviyo, Nutthakritta; Boueroy, Parichart; Chompoosor, Apiwat

    2016-01-01

    Background There is worldwide interest in silver nanoparticles (AgNPs) synthesized by various chemical reactions for use in applications exploiting their antibacterial activity, even though these processes exhibit a broad range of toxicity in vertebrates and invertebrates alike. To avoid the chemical toxicity, biosynthesis (green synthesis) of metal nanoparticles is proposed as a cost-effective and environmental friendly alternative. Aloe vera leaf extract is a medicinal agent with multiple properties including an antibacterial effect. Moreover the constituents of aloe vera leaves include lignin, hemicellulose, and pectins which can be used in the reduction of silver ions to produce as AgNPs@aloe vera (AgNPs@AV) with antibacterial activity. Methods AgNPs were prepared by an eco-friendly hydrothermal method using an aloe vera plant extract solution as both a reducing and stabilizing agent. AgNPs@AV were characterized using XRD and SEM. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. MIC and MBC were used to correlate the concentration of AgNPs@AV its bactericidal effect. SEM was used to investigate bacterial inactivation. Then the toxicity with human cells was investigated using an MTT assay. Results The synthesized AgNPs were crystalline with sizes of 70.70 ± 22-192.02 ± 53 nm as revealed using XRD and SEM. The sizes of AgNPs can be varied through alteration of times and temperatures used in their synthesis. These AgNPs were investigated for potential use as an antibacterial agent to inhibit pathogenic bacteria. Their antibacterial activity was tested on S. epidermidis and P. aeruginosa. The results showed that AgNPs had a high antibacterial which depended on their synthesis conditions, particularly when processed at 100 oC for 6 h and 200 oC for 12 h. The cytotoxicity of AgNPs was determined using human PBMCs revealing no obvious cytotoxicity. These results indicated that AgNPs@AV can be effectively utilized in

  12. Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity

    Directory of Open Access Journals (Sweden)

    Patcharaporn Tippayawat

    2016-10-01

    Full Text Available Background There is worldwide interest in silver nanoparticles (AgNPs synthesized by various chemical reactions for use in applications exploiting their antibacterial activity, even though these processes exhibit a broad range of toxicity in vertebrates and invertebrates alike. To avoid the chemical toxicity, biosynthesis (green synthesis of metal nanoparticles is proposed as a cost-effective and environmental friendly alternative. Aloe vera leaf extract is a medicinal agent with multiple properties including an antibacterial effect. Moreover the constituents of aloe vera leaves include lignin, hemicellulose, and pectins which can be used in the reduction of silver ions to produce as AgNPs@aloe vera (AgNPs@AV with antibacterial activity. Methods AgNPs were prepared by an eco-friendly hydrothermal method using an aloe vera plant extract solution as both a reducing and stabilizing agent. AgNPs@AV were characterized using XRD and SEM. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. MIC and MBC were used to correlate the concentration of AgNPs@AV its bactericidal effect. SEM was used to investigate bacterial inactivation. Then the toxicity with human cells was investigated using an MTT assay. Results The synthesized AgNPs were crystalline with sizes of 70.70 ± 22-192.02 ± 53 nm as revealed using XRD and SEM. The sizes of AgNPs can be varied through alteration of times and temperatures used in their synthesis. These AgNPs were investigated for potential use as an antibacterial agent to inhibit pathogenic bacteria. Their antibacterial activity was tested on S. epidermidis and P. aeruginosa. The results showed that AgNPs had a high antibacterial which depended on their synthesis conditions, particularly when processed at 100 oC for 6 h and 200 oC for 12 h. The cytotoxicity of AgNPs was determined using human PBMCs revealing no obvious cytotoxicity. These results indicated that AgNPs@AV can be effectively

  13. Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity.

    Science.gov (United States)

    Tippayawat, Patcharaporn; Phromviyo, Nutthakritta; Boueroy, Parichart; Chompoosor, Apiwat

    2016-01-01

    There is worldwide interest in silver nanoparticles (AgNPs) synthesized by various chemical reactions for use in applications exploiting their antibacterial activity, even though these processes exhibit a broad range of toxicity in vertebrates and invertebrates alike. To avoid the chemical toxicity, biosynthesis (green synthesis) of metal nanoparticles is proposed as a cost-effective and environmental friendly alternative. Aloe vera leaf extract is a medicinal agent with multiple properties including an antibacterial effect. Moreover the constituents of aloe vera leaves include lignin, hemicellulose, and pectins which can be used in the reduction of silver ions to produce as AgNPs@aloe vera (AgNPs@AV) with antibacterial activity. AgNPs were prepared by an eco-friendly hydrothermal method using an aloe vera plant extract solution as both a reducing and stabilizing agent. AgNPs@AV were characterized using XRD and SEM. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. MIC and MBC were used to correlate the concentration of AgNPs@AV its bactericidal effect. SEM was used to investigate bacterial inactivation. Then the toxicity with human cells was investigated using an MTT assay. The synthesized AgNPs were crystalline with sizes of 70.70 ± 22-192.02 ± 53 nm as revealed using XRD and SEM. The sizes of AgNPs can be varied through alteration of times and temperatures used in their synthesis. These AgNPs were investigated for potential use as an antibacterial agent to inhibit pathogenic bacteria. Their antibacterial activity was tested on S. epidermidis and P. aeruginosa. The results showed that AgNPs had a high antibacterial which depended on their synthesis conditions, particularly when processed at 100 (o)C for 6 h and 200 (o)C for 12 h. The cytotoxicity of AgNPs was determined using human PBMCs revealing no obvious cytotoxicity. These results indicated that AgNPs@AV can be effectively utilized in pharmaceutical

  14. Progress of studies on preparation of silver-plated fibers and properties of fabric of silver-plated fibers%镀银纤维制备工艺及其织物性能的研究进展

    Institute of Scientific and Technical Information of China (English)

    林梦梦; 王云仪

    2014-01-01

    Silver-plated fiber , as a kind of conductive fiber , is widely used nowadays .The preparation of silver-plated fiber by electroless plating and its application fields were introduced .To provide a reference for the development and application of silver-plated fiber , progress of studies on anti-electromagnetic radiation property , anti-bacterial property and anti-static property of fabric of silver-plated fibers was reviewed.%镀银纤维是目前应用较广的一种导电纤维。介绍了化学镀银技术中的还原法制备镀银纤维的工艺以及镀银纤维的应用领域。综述了镀银纤维织物在防电磁辐射、抗菌性和抗静电性等方面的研究进展,为镀银纤维的开发及应用提供参考。

  15. Green synthesis of high conductivity silver nanoparticle-reduced graphene oxide composite films

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, D.A. [School of Materials Science and Engineering, Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Hui, K.S., E-mail: kshui@hanyang.ac.kr [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Hui, K.N., E-mail: bizhui@pusan.ac.kr [School of Materials Science and Engineering, Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Cho, Y.R. [School of Materials Science and Engineering, Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Zhou, Wei [Department of Mechanical and Electrical Engineering, Xiamen University, Xiamen 361005 (China); Hong, Xiaoting [School of Chemistry and Environment, South China Normal University, Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, Guangzhou 510006 (China); Chun, Ho-Hwan [Global Core Research Center for Ships and Offshore Plants (GCRC-SOP), Pusan National University, San 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)

    2014-04-01

    Graphical abstract: - Highlights: • A green facile chemical approach to control the dimensions of Ag nanoparticles–graphene oxide (AgNPs/GO) composites was performed at room temperature. • With decreasing ultrasonication time, the size of the Ag nanoparticles decreased and became uniformly distributed over the surface of the GO nanosheets. • The as-prepared AgNPs/rGO composite films were then formed using a spin coating method and reduced at 500 °C under N{sub 2}/H{sub 2} gas flow for 1 h. • The lowest sheet resistance of 270 Ω/sq was obtained in the film corresponding to 1 min of ultrasonication, which showed a 40 times lower resistivity than the rGO film (10.93 kΩ/sq). - Abstract: A green facile chemical approach to control the dimensions of Ag nanoparticles–graphene oxide (AgNPs/GO) composites was performed by the in situ ultrasonication of a mixture of AgNO{sub 3} and graphene oxide solutions with the assistance of vitamin C acting as an environmentally friendly reducing agent at room temperature. With decreasing ultrasonication time, the size of the Ag nanoparticles decreased and became uniformly distributed over the surface of the GO nanosheets. The as-prepared AgNPs/rGO composite films were then formed using a spin coating method and reduced at 500 °C under N{sub 2}/H{sub 2} gas flow for 1 h. Four-point probe measurements showed that the sheet resistance of the AgNPs/rGO films decreased with decreasing AgNPs size. The lowest sheet resistance of 270 Ω/sq was obtained in the film corresponding to 1 min of ultrasonication, which showed a 40 times lower resistivity than the rGO film (10.93 kΩ/sq). The formation mechanisms of the as-prepared AgNPs/rGO films are proposed. This study provides a guide to controlling the dimensions of AgNPs/rGO films, which might hold promise as advanced materials for a range of analytical applications, such as catalysis, sensors and microchips.

  16. Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An, E-mail: lian2010@lut.cn

    2014-06-01

    A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al{sub 2}O{sub 3} and Fe{sub 3}O{sub 4}, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

  17. Facile preparation of superhydrophobic surfaces based on metal oxide nanoparticles

    Science.gov (United States)

    Bao, Xue-Mei; Cui, Jin-Feng; Sun, Han-Xue; Liang, Wei-Dong; Zhu, Zhao-Qi; An, Jin; Yang, Bao-Ping; La, Pei-Qing; Li, An

    2014-06-01

    A novel method for fabrication of superhydrophobic surfaces was developed by facile coating various metal oxide nanoparticles, including ZnO, Al2O3 and Fe3O4, on various substrates followed by treatment with polydimethylsiloxane (PDMS) via chemical vapor deposition (CVD) method. Using ZnO nanoparticles as a model, the changes in the surface chemical composition and crystalline structures of the metal oxide nanoparticles by PDMS treatment were investigated by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The results show that the combination of the improved surface roughness generated from of the nanoparticles aggregation with the low surface-energy of silicon-coating originated from the thermal pyrolysis of PDMS would be responsible for the surface superhydrophobicity. By a simple dip-coating method, we show that the metal oxide nanoparticles can be easily coated onto the surfaces of various textural and dimensional substrates, including glass slide, paper, fabric or sponge, for preparation of superhydrophobic surfaces for different purpose. The present strategy may provide an inexpensive and new route to surperhydrophobic surfaces, which would be of technological significance for various practical applications especially for separation of oils or organic contaminates from water.

  18. Physicochemical of pillared clays prepared by several metal oxides

    Science.gov (United States)

    Rinaldi, Nino; Kristiani, Anis

    2017-03-01

    Natural clays could be modified by the pillarization method, called as Pillared Clays (PILCs). PILCs have been known as porous materials that can be used for many applications, one of the fields is catalysis. PILCs as two dimensional materials are interesting because their structures and textural properties can be controlled by using a metal oxide as the pillar. Different metal oxide used as the pillar causes different properties results of pillared clays. Usually, natural smectite clays/bentonites are used as a raw material. Therefore, a series of bentonite pillared by metal oxides was prepared through pillarization method. Variation of metals pillared into bentonite are aluminium, chromium, zirconium, and ferro. The physicochemical properties of catalysts were characterized by using X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) analysis, and Fourier transform infrared spectroscopy (FTIR) measurement. Noteworthy characterization results showed that different metals pillared into bentonite affected physical and chemical properties, i.e. basal spacing, surface area, pore size distribution, thermal stability and acidity.

  19. PREPARATION AND CHARACTERIZATION OF IRON OXIDE NANOPARTICLES ON DISACCHARIDE TEMPLATES

    Directory of Open Access Journals (Sweden)

    B ANILREDDY

    2013-09-01

    Full Text Available We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharidetemplates. Interaction between iron sulfate and template has been carried out in aqueous phase,followed by the selective and controlled removal of the template to achieve narrow distribution ofparticle size. Particles of iron oxide obtained have been characterized for their stability in solventmedia, size, size distribution and crystallinity and it was found that when the negative value of thezeta potential increases, particle size decreases. A narrow particle size distribution with D100 = 275nm was obtained with chitosan and starch templates. SEM measurements further confirm the particlesize measurement. Diffuse reflectance UV–VIS spectra values show that the template is completelyremoved from the final iron oxide particles and powder XRD measurements show that the peaks ofthe diffractogram are in agreement with the theoretical data of hematite. The salient observations ofour study shows that there occurs a direct correlation between zeta potential, polydispersity index,band gap energy and particle size. The crystallite size of the particles was found to be 30–35 nm. Alarge negative zeta potential was found to be advantageous for achieving lower particle sizes, as theparticles remained discrete without agglomeration.

  20. Improved nonlinear optical and optical limiting properties in non-covalent functionalized reduced graphene oxide/silver nanoparticle (NF-RGO/Ag-NPs) hybrid

    Science.gov (United States)

    Sakho, El hadji Mamour; Oluwafemi, Oluwatobi S.; Sreekanth, P.; Philip, Reji; Thomas, Sabu; Kalarikkal, Nandakumar

    2016-08-01

    Nonlinear optical (NLO) response under near infrared (800 nm) and visible (532 nm) laser excitations, of 100 fs (fs) and 5 ns (ns) pulse durations respectively, of reduced graphene oxide (RGO), non-covalent functionalized reduced graphene oxide (NF-RGO) and NF-RGO decorated with various concentration of silver nanoparticles (NF-RGO/Ag-NPs) have been investigated using the Open-aperture Z-Scan technique. For both femtosecond and nanosecond laser excitations, the studied graphene-based materials exhibit good nonlinear optical power limiting properties (OL), with NF-RGO/Ag-NPs sample prepared with 0.1 M AgNO3 showing the best nonlinear optical properties. For the ns regime, the optical limiting threshold decreased from 8.3 J/cm2 in NF-RGO to 4.3 J/cm2 in NF-RGO/Ag-NPs, while at fs regime, the nonlinear absorption coefficient (β) was found to increase with decrease in concentration of Ag-NPs in the hybrid. Two-photon absorption (2 PA) in combination with saturable absorption (SA) in femtosecond regime, and reverse saturable absorption (RSA) along with saturable absorption (SA) in the nanosecond regime, are responsible for the observed nonlinear optical absorption (NLA) behavior in these materials. These findings show that the as-synthesized NF-RGO/Ag-NPs hybrid is a relatively better material for nonlinear optical limiting applications.

  1. Preparing of Highly Conductive Patterns on Flexible Substrates by Screen Printing of Silver Nanoparticles with Different Size Distribution

    Science.gov (United States)

    Ding, Jin; Liu, Jun; Tian, Qingyong; Wu, Zhaohui; Yao, Weijing; Dai, Zhigao; Liu, Li; Wu, Wei

    2016-09-01

    A facile one-step polyol method is employed to synthesize the Ag nanoparticles (NPs) in large scale. The Ag NPs with different average diameter (from 52 to 120 nm) and particle size distribution are prepared by changing the mass ratio of AgNO3 and PVP. Furthermore, the as-obtained Ag NPs are prepared as conductive inks, which could be screen printed on various flexible substrates and formed as conductive patterns after sintering treatment. During the reaction process, PVP is used as the capping reagent for preventing the agglomeration of Ag NPs, and the influence of the mass ratio of AgNO3 and PVP to the size distribution of Ag NPs is investigated. The results of electronic properties reveal that the conductivity of printed patterns is highly dependent on the size distribution of as-obtained Ag NPs. Among all the samples, the optimal conductivity is obtained when the mass ratio of AgNO3 and PVP is 1:0.4. Subsequently, the sintering time and temperature are further investigated for obtaining the best conductivity; the optimal electrical resistivity value of 3.83 μΩ · cm is achieved at 160 °C for 75 min, which is close to the resistivity value of the bulk silver (1.58 μΩ · cm). Significantly, there are many potential advantages in printed electronics applications because of the as-synthesized Ag NPs with a low sintering temperature and low electrical resistivity.

  2. Evaluation of developmental responses of two crop plants exposed to silver and zinc oxide nanoparticles.

    Science.gov (United States)

    Pokhrel, Lok R; Dubey, Brajesh

    2013-05-01

    The increasing applications of different nanomaterials in the myriad of nano-enabled products and their potential for leaching have raised considerable environmental, health and safety (EHS) concerns. As systematic studies investigating potential anomalies in the morphology and anatomy of crop plants are scarce, herein we report on the developmental responses of two agriculturally significant crop plants, maize (Zea mays L.) and cabbage (Brassica oleracea var. capitata L.), upon in vitro exposure to nanoparticles of citrate-coated silver (Citrate-nAg) and zinc oxide (nZnO). Analyses involve histology of the primary root morphology and anatomy using light microscopy, metal biouptake, moisture content, rate of germination, and root elongation. Comparative toxicity profiles of the ionic salts (AgNO3 and ZnSO4) are developed. Notably, we uncover structural changes in maize primary root cells upon exposure to Citrate-nAg, nZnO, AgNO3, and ZnSO4, possibly due to metal biouptake, suggesting potential for functional impairments in the plant growth and development. Citrate-nAg exposure results in lower Ag biouptake compared to AgNO3 treatment in maize. Microscopic evidence reveals 'tunneling-like effect' with nZnO treatment, while exposure to AgNO3 leads to cell erosion in maize root apical meristem. In maize, a significant change in metaxylem count is evident with Citrate-nAg, AgNO3, and ZnSO4 treatment, but not with nZnO treatment (p>0.1). In both maize and cabbage, measures of germination and root elongation reveal lower nanoparticle toxicity compared to free ions. As moisture data do not support osmotically-induced water stress hypothesis for explaining toxicity, we discuss other proximate mechanisms including the potential role of growth hormones and transcription factors. These findings highlight previously overlooked, anatomically significant effects of metal nanoparticles, and recommend considering detailed anatomical investigations in tandem with the standard

  3. Acute and chronic effects from pulse exposure of D. magna to silver and copper oxide nanoparticles.

    Science.gov (United States)

    Sørensen, Sara Nørgaard; Holten Lützhøft, Hans-Christian; Rasmussen, Rose; Baun, Anders

    2016-11-01

    Aquatic toxicity testing of nanoparticles (NPs) is challenged by their dynamic behavior in test suspensions. The resulting difficulties in controlling and characterizing exposure concentrations are detrimental to the generation of concentration-response data needed for hazard identification of NPs. This study explores the applicability of short-term (1, 2 and 3h) pulse exposures as means to keep the exposure stable and at the same time disclose acute and chronic effects of AgNPs and CuONPs in D. magna. Dissolution, agglomeration and sedimentation were found to have less influence on exposure concentrations during 1-3h pulses than for 24-48h continuous exposures. For AgNPs, preparation of test suspensions in medium 24h before toxicity testing (aging) increased stability during the short-term pulses. In pulse tests, organisms were exposed to the test materials, AgNPs and CuONPs for 1, 2 and 3h, and afterwards transferred to clean medium and observed for 48h (post-exposure period) for acute effects and for 21 d for chronic effects. AgNO3 and CuCl2 were used as reference materials for dissolved silver and copper, respectively. For all test materials, a 3h pulse caused comparable immobility in D. magna (observed after 48h post-exposure) as 24h continuous exposure, as evidenced by overlapping 95% confidence intervals of EC50-values. In the 21 d post-exposure period, no trends in mortality or body length were identified. AgNP and AgNO3 pulses had no effect on the number of moltings, days to first live offspring or cumulated number of offspring, but the number of offspring increased for AgNPs (3h pulse only). In contrast, CuONP and CuCl2 pulses decreased the number of moltings and offspring, and for CuONPs the time to first live offspring was prolonged. After CuONP exposures, the offspring production decreased more with increasing concentrations than for CuCl2 exposures when taking the measured dissolved copper into account. This indicates a nanoparticle-specific effect

  4. Comparative hazard identification by a single dose lung exposure of zinc oxide and silver nanomaterials in mice

    DEFF Research Database (Denmark)

    Gosens, Ilse; Kermanizadeh, Ali; Jacobsen, Nicklas Raun

    2015-01-01

    Comparative hazard identification of nanomaterials (NMs) can aid in the prioritisation for further toxicity testing. Here, we assessed the acute lung, systemic and liver responses in C57BL/6N mice for three NMs to provide a hazard ranking. A silver (Ag), non-functionalised zinc oxide (ZnO) and a ......Comparative hazard identification of nanomaterials (NMs) can aid in the prioritisation for further toxicity testing. Here, we assessed the acute lung, systemic and liver responses in C57BL/6N mice for three NMs to provide a hazard ranking. A silver (Ag), non-functionalised zinc oxide (Zn...... fluid (BALF) after administration of both non-functionalised and functionalised ZnO. The latter also induced systemic inflammation measured as an increase in blood neutrophils and a decrease in blood lymphocytes. Exposure to Ag NM was not accompanied by pulmonary inflammation or cytotoxicity......, or by systemic inflammation. A decrease in glutathione levels was demonstrated in the liver following exposure to high doses of all three nanomaterials irrespective of any noticeable inflammatory or cytotoxic effects in the lung. By applying benchmark dose (BMD) modeling statistics to compare potencies...

  5. Atmospheric oxidation and carbon contamination of silver and its effect on surface-enhanced Raman spectroscopy (SERS)

    Science.gov (United States)

    Matikainen, Antti; Nuutinen, Tarmo; Itkonen, Tommi; Heinilehto, Santtu; Puustinen, Jarkko; Hiltunen, Jussi; Lappalainen, Jyrki; Karioja, Pentti; Vahimaa, Pasi

    2016-11-01

    Surface-enhanced Raman spectroscopy (SERS) is considered a highly promising technology for different analytical purposes. The applications of SERS are still quite limited due its relatively poor quantitative repeatability and the fact that SERS is very sensitive to oxidation, which is a challenge especially with silver based SERS substrates. Here, the link between these phenomena is investigated by exposing silver SERS substrates to ambient laboratory air. We show that SERS intensity decreases exponentially after the exposure, which consequently leads to an increasing standard deviation (σ) in intensity. Within a five-hour measurement window, the SERS intensity already drops by 60%, while σ triples from 7% to 21%. The SERS results are supplemented by elemental analysis, which shows that oxidation and atmospheric carbon contamination coincide with the rapid SERS intensity decrease. The results emphasize how sensitive SERS is towards atmospheric contamination and how it can also reduce the measurement repeatability - even if the substrates are exposed to air just for a very short period of time.

  6. Nano silver and nano zinc-oxide in surface waters - exposure estimation for Europe at high spatial and temporal resolution.

    Science.gov (United States)

    Dumont, Egon; Johnson, Andrew C; Keller, Virginie D J; Williams, Richard J

    2015-01-01

    Nano silver and nano zinc-oxide monthly concentrations in surface waters across Europe were modeled at ~6 x 9 km spatial resolution. Nano-particle loadings from households to rivers were simulated considering household connectivity to sewerage, sewage treatment efficiency, the spatial distribution of sewage treatment plants, and their associated populations. These loadings were used to model temporally varying nano-particle concentrations in rivers, lakes and wetlands by considering dilution, downstream transport, water evaporation, water abstraction, and nano-particle sedimentation. Temporal variability in concentrations caused by weather variation was simulated using monthly weather data for a representative 31-year period. Modeled concentrations represent current levels of nano-particle production.Two scenarios were modeled. In the most likely scenario, half the river stretches had long-term average concentrations exceeding 0.002 ng L(-1) nano silver and 1.5 ng L(-1) nano zinc oxide. In 10% of the river stretches, these concentrations exceeded 0.18 ng L(-1) and 150 ng L(-1), respectively. Predicted concentrations were usually highest in July.

  7. A Facile Method for Preparing Transparent, Conductive, and Paper-Like Silver Nanowire Films

    Directory of Open Access Journals (Sweden)

    Yajie Wang

    2011-01-01

    Full Text Available Transparent, conductive, and flexible silver nanowire (AgNW films have been fabricated by a facile two-step method. Firstly, the well-dispersed AgNW suspension is vacuum filtered using mixed esters of cellulose (MCE membranes as filters. Then, the AgNW-MCE films are treated with acetone vapor. After the infiltration of acetone vapor, the white and porous MCE membranes change into transparent and pore-free, and AgNW-MCE films are obtained with extraordinary optical, conductive, and mechanical properties. An optimal result is obtained with transmittance of 85% at 550 nm and sheet resistance about 50 Ohm/sq. The flexibility of AgNW-MCE films is remarkable, which is comparable to that of the AgNW film on flexible polyethylene terephthalate (PET. More important, AgNW-MCE films show an excellent adhesion to the substrate, which causes a stable electrical conductivity even after scotch tape test and finger friction test. As a result of improved adhesion to the substrate, the sheet resistance of AgNW-MCE films is about 20% smaller than that of AgNW-PET films.

  8. Preparation, characterization, and in vitro cytotoxicity of chitosan hydrogels containing silver nanoparticles.

    Science.gov (United States)

    Tyliszczak, Bożena; Drabczyk, Anna; Kudłacik-Kramarczyk, Sonia; Sobczak-Kupiec, Agnieszka

    2017-10-01

    Hydrogels, chitosan as well as silver nanoparticles become in recent years materials characterized by a great interest. In present paper hydrogel based on chitosan and containing mentioned type of nano-sized particles have been synthesized by means of photopolymerization. Sorption capacity in selected liquids as well as behavior in simulated body fluid (such as Ringer's liquid) have been determined. Particularly attention was paid to the studies on toxicity of the hydrogels in relation to the epidermal cells as well as on their impact on growth of selected strain of bacteria (Escherichia coli). Furthermore, impact of introduction of nanosilver into hydrogel matrix on its properties has also been defined. Surface morphology of attained hydrogels by means of SEM analysis and chemical structure using spectroscopy have been checked. The most interesting conclusion is the fact that proposed chitosan based hydrogels modified with nanosilver do not affect negatively on epidermal cells. However, they inhibit a growth of E. coli. These two observations make them very interesting from the medical point of view.

  9. Electrospun chitosan nanofibers with controlled levels of silver nanoparticles. Preparation, characterization and antibacterial activity.

    Science.gov (United States)

    Lee, Sang Jin; Heo, Dong Nyoung; Moon, Ji-Hoi; Ko, Wan-Kyu; Lee, Jung Bok; Bae, Min Soo; Park, Se Woong; Kim, Ji Eun; Lee, Dong Hyun; Kim, Eun-Cheol; Lee, Chang Hoon; Kwon, Il Keun

    2014-10-13

    The ideal wound dressing would have properties that allow for absorption of exudates, and inhibition of microorganism for wound protection. In this study, we utilized an electrospinning (ELSP) technique to design a novel wound dressing. Chitosan (CTS) nanofibers containing various ratios of silver nanoparticles (AgNPs) were obtained. AgNPs were generated directly in the CTS solution by using a chemical reduction method. The formation and presence of AgNPs in the CTS/AgNPs composite was confirmed by x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV) and thermogravimetric analysis (TGA). The electrospun CTS/AgNPs nanofibers were characterized morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These nanofibers were subsequently tested to evaluate their antibacterial activity against gram-negative Pseudomonas aeruginosa (P. aeruginosa) and gram-positive Methicillin-resistant Staphylococcus aureus (MRSA). Results of this antibacterial testing suggest that CTS/AgNPs nanofibers may be effective in topical antibacterial treatment in wound care.

  10. Graphene oxide functionalized with silver nanoparticles as conducting electrodes for solar cells and electrochemical energy storage devices

    Science.gov (United States)

    Reddy, Kakarla Raghava; Alonso-Marroquin, Fernando

    2017-06-01

    We present the development of novel electrochemical supercapacitor and sensor based on silver (Ag) nanoparticles coated graphene oxide (GO). 10-20 nm diameter of Ag nanoparticles were well dispersed on the surface of graphene oxide through the chemical reduction method. Ag-coated GO nanohybrids were characterized by transmission electron microscopy (TEM), X-ray diffraction, Raman spectroscopy, electrical and an electrochemical analysis for the energy storage (supercapacitors), energy conversion (solar cells) and sensor applications. It is found that nanohybrid electrodes showed good specific capacitance and electrochemical sensing performance in comparison to pristine GO. The improvement in the electrochemical characteristics can be attributed to the sensitizing effect between Ag nanparticles and GO. These GO/Ag hybrid transparent conducting films also show low resistance and good transmittance, suggesting they are good electrodes for the opto-electronic devices (e.g. solar cells).

  11. Matrix isolation infrared spectroscopic and theoretical study of the copper (I) and silver (I) nitrous oxide complexes

    Science.gov (United States)

    Wang, Guanjun; Jin, Xi; Chen, Mohua; Zhou, Mingfei

    2006-03-01

    Copper and silver chloride-nitrous oxide complexes: ClCuNNO and ClAgNNO have been produced and trapped in solid argon by co-deposition of laser-evaporated metal chlorides with nitrous oxide in excess argon. On the basis of isotopic substituted experiments as well as theoretical calculations, infrared absorptions at 2305.8 and 1318.4 cm -1, and 2291.2 and 1325.4 cm -1 are assigned to the N-N and N-O stretching modes of the linear ClCuNNO and ClAgNNO complexes, respectively. The binding energies for the complexes with respect to MCl (M = Cu, Ag) and N 2O were computationally estimated to be 27.9 and 13.1 kcal/mol.

  12. Comparative study on effects of dietary with diphenyl diselenide on oxidative stress in carp (Cyprinus carpio) and silver catfish (Rhamdia sp.) exposed to herbicide clomazone.

    Science.gov (United States)

    Menezes, Charlene; Leitemperger, Jossiele; Toni, Cândida; Santi, Adriana; Lópes, Thais; Barbosa, Nilda Berenice Vargas; Neto, João Radünz; Loro, Vania Lucia

    2013-09-01

    The study investigated the capacity of diphenyl diselenide [(PhSe)2] (3.0mg/kg), on reduce the oxidative damage in liver, gills and muscle of carp and silver catfish exposed to clomazone (192h). Silver catfish exposed to clomazone showed increased thiobarbituric acid-reactive substance (TBARS) in liver and muscle and protein carbonyl in liver and gills. Furthermore, clomazone in silver catfish decrease non-protein thiols (NPSH) in liver and gills and glutathione peroxidase and ascorbic acid in liver. (PhSe)2 reversed the effects caused by clomazone in silver catfish, preventing increases in TBARS and protein carbonyl. Moreover, NPSH and ascorbic acid were increased by values near control. The results suggest that (PhSe)2 attenuated the oxidative damage induced by clomazone in silver catfish. The clomazone no caused an apparent situation of oxidative stress in carp, showing that this species is more resistant to this toxicant. Altogether, the containing (PhSe)2 diet helps fish to increase antioxidants defenses.

  13. Effects of reducibility of graphene oxide nanosheets on preparation of AgNPs/GO nanocomposites and their electrocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Yanpeng; Peng, Junjun, E-mail: john-peng@whu.edu.cn; Li, Wei; Li, Ming; Liu, Huihong; Zhang, Hanmin [Wuhan Textile University, College of Chemistry and Chemical Engineering (China)

    2015-12-15

    Silver nanoparticles/graphene oxide (AgNPs/GO) nanocomposites were prepared in a solution of AgNO{sub 3} and GO. The GO serves not only as a reductant but also as a substrate to support the as-reduced silver nanoparticles. The reducibility of GO was investigated by analyzing the influence factors such as pH, duration, the reaction temperature, and the weight ratio of AgNO{sub 3} and GO in the AgNP/GO nanocomposite mixture, which were evaluated by the UV–vis absorption spectroscopy. The results demonstrated that Ag nanoparticles with an average diameter of 5–10 nm were uniformly dispersed on the surface of GO nanosheets under the optimum synthesis conditions of pH between 8 and 11, weight ratio of AgNO{sub 3} and GO between 55 % and 60 %, and at 80 °C for 6 h. Moreover, the obtained AgNPs/GO nanocomposites exhibit good electrocatalytic activity for the reduction of p-nitrophenol to 4-(hydroxyamino) phenol.

  14. Preparation of starch stabilized silver nanoparticles with spatial self-phase modulation properties by laser ablation technique

    Energy Technology Data Exchange (ETDEWEB)

    Zamiri, Reza; Azmi, B.Z.; Sadrolhosseini, Amir R.; Husin, M.S.; Zaidan, A.W. [Universiti Putra Malaysia, Department of Physics, Faculty of Science, UPM Serdang, Selangor (Malaysia); Darroudi, Majid [Universiti Putra Malaysia, Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, UPM Serdang, Selangor (Malaysia); Mahdi, M.A. [Universiti Putra Malaysia, Wireless and Photonics Networks Research Center, Faculty of Engineering, UPM Serdang, Selangor (Malaysia)

    2011-01-15

    Silver nanoparticles inside the starch solution have been successfully fabricated by laser ablation of a silver plate immersed in starch solution. The ablation has been done using a Q-switched Nd:YAG laser at 10 Hz repetition rate. The starch solution allows for the formation of silver nanoparticles with uniform particle diameters and well dispersed. The ablation was performed at different time durations to study the influence of the laser ablation time on efficiency of particle formation and sizes. The Spatial Self-phase modulation phenomena which can determine the nonlinear optical property of the samples were also investigated for starch solutions containing silver nanoparticles. (orig.)

  15. Preparation of heterocyclic amines by an oxidative amination of zinc organometallics mediated by Cu(I): a new oxidative cycloamination for the preparation of annulated indole derivatives.

    Science.gov (United States)

    Kienle, Marcel; Wagner, Andreas J; Dunst, Cora; Knochel, Paul

    2011-02-01

    Functionalized heterocyclic zinc reagents are easily aminated by an oxidative amination reaction of zinc amidocuprates prepared from various lithium amides. For the oxidation step, PhI(OAc)(2) proved to be the best reagent. The required heterocyclic zinc organometallics can be prepared either by direct metalation, by magnesium insertion in the presence of ZnCl(2), or by transmetalation of a suitable magnesium reagent. Furthermore, we report a new ring-closing reaction involving an intramolecular oxidative amination reaction. This reaction allows the preparation of tetracyclic heterocycles containing furan, thiophene, or indole rings.

  16. Study on preparation and properties of micro silver-coated copper powders%银包覆铜微粉的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    李雅丽; 刘娟; 党蕊

    2011-01-01

    By using CuSO4 · 5H2O as raw materials, the micro size of copper powders were prepared by pre-reduction method using glucose in the ethylene glycol medium, and the micro silver type of copper-coated powders were directly obtained through replacement reaction method. By means of experiment of conductivity, and analysis of the particle size and distribution, the optimum technology condition was confirmed to prepare the micro silver-coated copper powders.%以硫酸铜为原料,采用葡萄糖预还原法在乙二醇介质中制备微米级铜粉,由直接置换法制备铜包银型微粉;通过导电性实验、粒径及粒径分布分析等,优化了制备银包覆铜微粉的工艺条件.

  17. Investigation on steelmaking dust recycling and iron oxide red preparing

    Institute of Scientific and Technical Information of China (English)

    Pingfeng Fu; Qiang Zhang

    2008-01-01

    To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carried out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while fine clay minerals with a size of <38 μm are mainly iosiderite, calcium silicate, and calcite, which are conglomerated to each other.By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe3+ ion content of less than 5 g·L-1 was recovered as feeding water in the wet magnetic separation procedure.

  18. Water oxidation using a cobalt monolayer prepared by underpotential deposition.

    Science.gov (United States)

    Marsh, David A; Yan, Wenbo; Liu, Yu; Hemminger, John C; Penner, Reginald M; Borovik, A S

    2013-11-26

    Development of electrocatalysts for the conversion of water to dioxygen is important in a variety of chemical applications. Despite much research in this field, there are still several fundamental issues about the electrocatalysts that need to be resolved. Two such problems are that the catalyst mass loading on the electrode is subject to large uncertainties and the wetted surface area of the catalyst is often unknown and difficult to determine. To address these topics, a cobalt monolayer was prepared on a gold electrode by underpotential deposition and used to probe its efficiency for the oxidation of water. This electrocatalyst was characterized by atomic force microscopy, grazing-incidence X-ray diffraction, and X-ray photoelectron spectroscopy at various potentials to determine if changes occur on the surface during catalysis. An enhancement of current was observed upon addition of PO4(3-) ions, suggesting an effect from surface-bound ligands on the efficiency of water oxidation. At 500 mV overpotential, current densities of 0.20, 0.74, and 2.4 mA/cm(2) for gold, cobalt, and cobalt in PO4(3-) were observed. This approach thus provided electrocatalysts whose surface areas and activity can be accurately determined.

  19. Facile preparation of reduced graphene oxide - ruthenium oxide nanocomposite electrodes for high-performance supercapacitors

    Science.gov (United States)

    Amir, Fatima; Pham, Viet; Dickerson, James; Winthrop University Team; CFN-Brookhaven National Lab Team

    2015-03-01

    Herein we report a facile approach of synthesis of graphene oxide (GO) sheets modified with ruthenium oxide (RuO2) nanoparticles, followed by a reduction of graphene oxide in an alkaline medium. The as-prepared reduced graphene oxide (rGO)/ruthenium oxide (RuO2) nanocomposite was used for the fabrication of a symmetric supercapacitor. The specific capacitance and charge-discharge periods of the supercapacitor were found to be dependent on both the structural and morphological properties, and the electrolytes used. Surface morphology analysis using scanning electron microscopy (SEM) shows the RuO2 nanoparticles decorating rGO sheets, comprising a highly porous surface. Structural analysis obtained by x-ray diffraction (XRD) revealed an amorphous structure that is necessary to achieve a high cycling rate capability. The electrochemical properties of rGO/RuO2 were measured in a two electrodes system, using two different electrolytes: H2SO4andNa2SO4. The specific capacitance of rGO/RuO2 in H2SO4 was found to be 318 F/g, and is much higher than that of Na2SO4 (184 F/g).

  20. Large-scale synthesis and self-organization of silver nanoparticles with Tween 80 as a reductant and stabilizer

    Science.gov (United States)

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

    2012-11-01

    Tween 80 (polysorbate 80) has been used as a reducing agent and protecting agent to prepare stable water-soluble silver nanoparticles on a large scale through a one-pot process, which is simple and environmentally friendly. Silver ions can accelerate the oxidation of Tween 80 and then get reduced in the reaction process. The well-ordered arrays such as ribbon-like silver nanostructures could be obtained by adjusting the reaction conditions. High-resolution transmission electron microscopy confirms that ribbon-like silver nanostructures (approximately 50 nm in length and approximately 2 μm in width) are composed of a large number of silver nanocrystals with a size range of 2 to 3 nm. In addition, negative absorbance around 320 nm in the UV-visible spectra of silver nanoparticles has been observed, probably owing to the instability of nanosized silver colloids.

  1. 光化学还原法制备纳米银溶胶%Preparation of Nano-silver Sol by Photochemical Reduction Method

    Institute of Scientific and Technical Information of China (English)

    张伟; 谈发堂; 乔学亮; 陈建国

    2012-01-01

    Nano-silver sol with good dispersibility and narrow panicle size distribution was prepared by photochemical reduction of silver ammonia solution precursor with polyvinylpyrrolidone(PVP) as protective agent. Transmission electron microscope(TEM) and UV-Vis were also employed to characterize the prepared nano-silver soL The results indicate that UV irradiation time and the concentration of PVP both have obvious influence for this reaction. A good morphology and dispersibility of silver nano-sol could be synthesized after irradiation 30min, when the mole ratio of PVP/[Ag(NH3 )2]+ in reaction solution equal to 50. Furthermore, the process of synthesizing silver nano-sol does not contain any toxic additive, which makes the product possesse a wide application in the future.%采用光化学还原法,以银氨溶液为前驱体,PVP为保护剂制备分散性良好和粒径分布窄的纳米银溶胶.利用透射电子显微镜(TEM)和紫外-可见分光光度计(UV-Vis)对纳米银溶胶进行表征.结果表明,紫外光照时间和PVP浓度都对该反应有明显的影响,在[Ag(NH3)2]+浓度为1mmol/L,n(PVP)/n([Ag(NH3)2]+)=50时,反应30min就可以生成理想的纳米银溶胶.此外,该方法没有使用有毒添加剂,制备的纳米银溶胶更为安全,从而可以应用在更为广阔的领域.

  2. Graphene oxide powders with different oxidation degree, prepared by synthesis variations of the Hummers method

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Contreras, Jesus; Caballero-Briones, F., E-mail: fcaballero@ipn.mx

    2015-03-01

    Graphene oxide (GO) powders with different oxidation degree estimated through the relative intensity of the infrared absorption bands related to oxygen containing groups were prepared through variations of the Hummers method. The GO powders were analyzed by Transmission Electron Microscopy, Energy dispersive spectroscopy, X-ray Photoelectron Spectroscopy, Fourier Transform Infrared Spectroscopy, Raman spectroscopy, X-ray Diffraction, UV–VIS spectroscopy and Electrical Resistance measurements. Several square micron GO sheets with low wrinkling were obtained. Oxygen to carbon ratio is around 0.2 in all the samples although a strong variance in the relative intensity of the oxygen related infrared bands is evident. Thus, the oxidation degree was estimated from the FTIR measurements using the quotient between the C–O related bands area to the total area under the spectra. FTIR shows presence of hydroxyl (–OH), epoxy (C–O–C), carboxyl (–COOH) and carbonyl (C=O) moieties and evidence of intermolecular interactions between adjacent groups. These interactions influence the exfoliation degree, the absorbance of the GO suspensions, as well as the electrical resistance, while the crystalline domain sizes, estimated from XRD and Raman do not show a noticeable behavior related with the composition and molecular structure. The results indicate that the electrical resistance is influenced mainly by the surface chemistry of the GO powders and not only by the O/C ratio. The control of the surface chemistry of GO powders would allow their use as additives in organic bulk heterojunction solar cells with enhanced photoconversion efficiency. - Highlights: • Powders of graphene oxide with different oxidation degree were prepared through variations of the Hummers method. • Raman spectroscopy and XRD demonstrated similar crystallite domain size in the samples. • Electrical resistance, exfoliation degree and optical absorption depend on the molecular structure.

  3. Canna edulis leaf extract-mediated preparation of stabilized silver nanoparticles: Characterization, antimicrobial activity, and toxicity studies.

    Science.gov (United States)

    Otari, S V; Pawar, S H; Patel, Sanjay K S; Singh, Raushan K; Kim, Sang-Yong; Lee, Jai Hyo; Zhang, Liaoyuan; Lee, Jung-Kul

    2017-01-12

    A novel approach to synthesize silver nanoparticles (AgNPs) using leaf extract of Canna edulis Ker-Gawl. (CELE) under ambient conditions is reported here. The as-prepared AgNPs were analyzed by UV-visible spectroscopy, transmission emission microscopy, X-ray diffraction, Fourier transform-infra red spectroscopy, energy-dispersive analysis of X-ray spectroscopy, zeta potential, and dynamic light scattering. The AgNPs showed excellent antimicrobial activity against various pathogens, including bacteria and various fungi. The biocompatibility of the AgNPs was analyzed in the L929 cell line using NRU and MTT assays. Acridine orange/ethidium bromide staining was used to determine whether the AgNPs had necrotic or apoptotic effects on L929 cells. The concentration of AgNPs required for 50% inhibition of growth of mammalian cells is far more than that required for inhibition of pathogenic microorganisms. Thus, CELE is a candidate for eco-friendly, clean, cost-effective, and non-toxic synthesis of AgNPs.

  4. Preparation of silver nanoparticles/polydopamine functionalized polyacrylonitrile fiber paper and its catalytic activity for the reduction 4-nitrophenol

    Science.gov (United States)

    Lu, Shixiang; Yu, Jianying; Cheng, Yuanyuan; Wang, Qian; Barras, Alexandre; Xu, Wenguo; Szunerits, Sabine; Cornu, David; Boukherroub, Rabah

    2017-07-01

    The study reports on the preparation of polyacrylonitrile fiber paper (PANFP) functionalized with polydopamine (PD) and silver nanoparticles (Ag NPs), named as Ag NPs/PD/PANFP. The composite material was obtained via a simple two-step chemical process. First, a thin polydopamine layer was coated onto the PANFP surface through immersion into an alkaline dopamine (pH 8.5) aqueous solution at room temperature. The reductive properties of polydopamine were further exploited for the deposition of Ag NPs. The morphology and chemical composition of the composite material were characterized using scanning electron microscopy (SEM), X-ray diffraction pattern (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the nanocomposite was evaluated for the reduction of 4-nitrophenol using sodium borohydride (NaBH4) at room temperature. The Ag NPs/PD/PANFP displayed good catalytic performance with a full reduction of 4-nitrophenol into the corresponding 4-aminophenol within 30 min. Moreover, the composite material exhibited a good stability up to 4 cycles without a significant loss of its catalytic activity.

  5. Surface-enhanced Raman scattering study of organic pigments using silver and gold nanoparticles prepared by pulsed laser ablation

    Science.gov (United States)

    Fazio, E.; Trusso, S.; Ponterio, R. C.

    2013-05-01

    The identification of pigments used in ancient times represents an interesting task in order to discriminate a production of a precise geographic area or to trace out the ancient commercial networks. Conventional micro-Raman spectroscopy (MRS), being a non-destructiveness technique, has been largely used for the analysis of dyes. Nevertheless several pigments, especially of organic origin, show weak Raman activity beside a strong a fluorescence that prevents their identification. Surface enhanced Raman scattering (SERS) can address such difficulties. The presence of noble metal nanoparticles induces a giant amplification of the Raman signal beside the fluorescence quenching. In this work we present the use of gold and silver nanoparticles to enhance the Raman signal of some commercial red organic dyes: bazilwood, dragon's blood, carmine and madder lake. The nanoparticles were prepared adopting two approaches: (1) ablating metallic targets in water using a pulsed Nd:YAG laser at 532 nm and (2) depositing the nanoparticles on glass substrates by means of a KrF excimer laser ablation process, performed in a controlled argon atmosphere.

  6. Metal nanoparticles (other than gold or silver) prepared using plant extracts for medical applications

    Science.gov (United States)

    Pasca, Roxana-Diana; Santa, Szabolcs; Racz, Levente Zsolt; Racz, Csaba Pal

    2016-12-01

    There are many modalities to prepare metal nanoparticles, but the reducing of the metal ions with plant extracts is one of the most promising because it is considerate less toxic for the environment, suitable for the use of those nanoparticles in vivo and not very expensive. Various metal ions have been already studied such as: cobalt, copper, iron, platinum, palladium, zinc, indium, manganese and mercury and the number of plant extracts used is continuously increasing. The prepared systems were characterized afterwards with a great number of methods of investigation: both spectroscopic (especially UV-Vis spectroscopy) and microscopic (in principal, electron microscopy-TEM) methods. The applications of the metal nanoparticles obtained are diverse and not completely known, but the medical applications of such nanoparticles occupy a central place, due to their nontoxic components, but some diverse industrial applications do not have to be forgotten.

  7. Preparation and Rapid Analysis of Antibacterial Silver, Copper and Zinc Doped Sol–gel Surfaces

    OpenAIRE

    Jaiswal, Swarna; Duffy, Brendan; McHale, Patrick

    2012-01-01

    The colonisation of clinical and industrial surfaces with microorganisms, including antibiotic-resistant strains, has promoted increased research into the development of effective antibacterial and antifouling coatings. This study describes the preparation of metal nitrate (Ag, Cu, Zn) doped methyltriethoxysilane (MTEOS) coatings and the rapid assessment of their antibacterial activity using polyproylene microtitre plates. Microtitre plate wells were coated with different volumes of liquid so...

  8. 铋银氧化物混合物高效氧化降解四溴双酚 A的研究%Efficient Oxidative Degradation of Tetrabromobisphenol A by Silver Bism uth Oxide

    Institute of Scientific and Technical Information of China (English)

    陈满堂; 宋洲; 王楠; 丁耀彬; 廖海星; 朱丽华

    2015-01-01

    以AgNO3和NaBiO3•2H2O为原料,采用离子交换-共沉淀法制备了铋银氧化物混合物(silver bismuth oxide,BSO),并利用它氧化降解溴代阻燃剂四溴双酚A( TBBPA)。研究了制备过程中银铋摩尔比及降解过程中BSO用量对TBBPA降解效果的影响。结果表明,当银铋摩尔比为1:1,BSO用量为1 g•L-1时,40 mg•L-1 TBBPA在7 min内可完全降解,其总有机碳的去除率高达80%。采用离子色谱﹑气相色谱-质谱联用仪及X射线光电子能谱监测降解过程中TBBPA的变化,发现TBBPA降解过程涉及脱溴﹑叔丁基碳的断裂和苯环的开环氧化等反应。利用NaN3作为分子探针,发现单线态氧是BSO氧化降解TBBPA的主要反应活性物种。%Silver bismuth oxide(BSO)was prepared by a simple ion exchange-coprecipitation method with AgNO3 and NaBiO3•2H2O as raw materials, and then used to oxidatively degrade tetrabromobisphenol A( TBBPA) . Effects of the molar ratio of Ag/Bi during BSO preparation and the BSO dosage on the degradation of TBBPA were investigated. The results showed that under the optimized conditions (i. e. , the Ag/Bi molar ratio of 1:1, BSO dosage of 1 g•L-1), 40 mg•L-1 of TBBPA was completely degraded and the removal of total organic carbon achieved more than 80% within 7 min. The degradation intermediates of TBBPA were identified by ion chromatography, gas chromatograph-mass spectrometer and X-ray photoelectron spectroscopy. The degradation pathway of TBBPA included the debromination, the cleavage of tert-butyl group and the open epoxidation of benzene ring. Based on a quenching study of NaN3 , singlet oxygen was proved to play a dominant role in the TBBPA degradation.

  9. Studies on electrochemical recovery of silver from simulated waste water from Ag(II)/Ag(I) based mediated electrochemical oxidation process.

    Science.gov (United States)

    Chandrasekara Pillai, K; Chung, Sang Joon; Moon, Il-Shik

    2008-11-01

    In the Ag(II)/Ag(I) based mediated electrochemical oxidation (MEO) process, the spent waste from the electrochemical cell, which is integrated with the scrubber columns, contains high concentrations of precious silver as dissolved ions in both the anolyte and the catholyte. This work presents an electrochemical developmental study for the recovery of silver from simulated waste water from Ag(II)/Ag(I) based MEO process. Galvanostatic method of silver deposition on Ti cathode in an undivided cell was used, and the silver recovery rate kinetics of silver deposition was followed. Various experimental parameters, which have a direct bearing on the metal recovery efficiency, were optimized. These included studies with the nitric acid concentration (0.75-6M), the solution stirring rate (0-1400 rpm), the inter-electrode distance between the anode and the cathode (2-8 cm), the applied current density (29.4-88.2 mA cm(-2)), and the initial Ag(I) ion concentration (0.01-0.2M). The silver recovered by the present electrodeposition method was re-dissolved in 6M nitric acid and subjected to electrooxidation of Ag(I) to Ag(II) to ascertain its activity towards Ag(II) electrogeneration from Ag(I), which is a key factor for the efficient working of MEO process. Our studies showed that the silver metal recovered by the present electrochemical deposition method could be reused repeatedly for MEO process with no loss in its electrochemical activity. Some work on silver deposition from sulfuric acid solution of different concentrations was also done because of its promising features as the catholyte in the Ag(II) generating electrochemical cell used in MEO process, which include: (i) complete elimination of poisonous NO(x) gas liberation in the cathode compartment, (ii) reduced Ag(+) ion migration across Nafion membrane from anolyte to catholyte thereby diminished catholyte contamination, and (iii) lower cell voltage and hence lesser power consumption.

  10. Preparing of Highly Conductive Patterns on Flexible Substrates by Screen Printing of Silver Nanoparticles with Different Size Distribution.

    Science.gov (United States)

    Ding, Jin; Liu, Jun; Tian, Qingyong; Wu, Zhaohui; Yao, Weijing; Dai, Zhigao; Liu, Li; Wu, Wei

    2016-12-01

    A facile one-step polyol method is employed to synthesize the Ag nanoparticles (NPs) in large scale. The Ag NPs with different average diameter (from 52 to 120 nm) and particle size distribution are prepared by changing the mass ratio of AgNO3 and PVP. Furthermore, the as-obtained Ag NPs are prepared as conductive inks, which could be screen printed on various flexible substrates and formed as conductive patterns after sintering treatment. During the reaction process, PVP is used as the capping reagent for preventing the agglomeration of Ag NPs, and the influence of the mass ratio of AgNO3 and PVP to the size distribution of Ag NPs is investigated. The results of electronic properties reveal that the conductivity of printed patterns is highly dependent on the size distribution of as-obtained Ag NPs. Among all the samples, the optimal conductivity is obtained when the mass ratio of AgNO3 and PVP is 1:0.4. Subsequently, the sintering time and temperature are further investigated for obtaining the best conductivity; the optimal electrical resistivity value of 3.83 μΩ · cm is achieved at 160 °C for 75 min, which is close to the resistivity value of the bulk silver (1.58 μΩ · cm). Significantly, there are many potential advantages in printed electronics applications because of the as-synthesized Ag NPs with a low sintering temperature and low electrical resistivity.

  11. Evaluation of developmental responses of two crop plants exposed to silver and zinc oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pokhrel, Lok R. [Department of Environmental Health, College of Public Health, East Tennessee State University, Johnson City, TN 37614–1700 (United States); Dubey, Brajesh, E-mail: bdubey@uoguelph.ca [Environmental Engineering, School of Engineering, University of Guelph, 50 Stone Road East, Guelph, Ontario (Canada)

    2013-05-01

    The increasing applications of different nanomaterials in the myriad of nano-enabled products and their potential for leaching have raised considerable environmental, health and safety (EHS) concerns. As systematic studies investigating potential anomalies in the morphology and anatomy of crop plants are scarce, herein we report on the developmental responses of two agriculturally significant crop plants, maize (Zea mays L.) and cabbage (Brassica oleracea var. capitata L.), upon in vitro exposure to nanoparticles of citrate-coated silver (Citrate–nAg) and zinc oxide (nZnO). Analyses involve histology of the primary root morphology and anatomy using light microscopy, metal biouptake, moisture content, rate of germination, and root elongation. Comparative toxicity profiles of the ionic salts (AgNO{sub 3} and ZnSO{sub 4}) are developed. Notably, we uncover structural changes in maize primary root cells upon exposure to Citrate–nAg, nZnO, AgNO{sub 3}, and ZnSO{sub 4}, possibly due to metal biouptake, suggesting potential for functional impairments in the plant growth and development. Citrate–nAg exposure results in lower Ag biouptake compared to AgNO{sub 3} treatment in maize. Microscopic evidence reveals ‘tunneling-like effect’ with nZnO treatment, while exposure to AgNO{sub 3} leads to cell erosion in maize root apical meristem. In maize, a significant change in metaxylem count is evident with Citrate–nAg, AgNO{sub 3}, and ZnSO{sub 4} treatment, but not with nZnO treatment (p > 0.1). In both maize and cabbage, measures of germination and root elongation reveal lower nanoparticle toxicity compared to free ions. As moisture data do not support osmotically-induced water stress hypothesis for explaining toxicity, we discuss other proximate mechanisms including the potential role of growth hormones and transcription factors. These findings highlight previously overlooked, anatomically significant effects of metal nanoparticles, and recommend considering

  12. Observation of asymmetric spectrum broadening induced by silver nanoparticles in a heavy-metal oxide glass

    CERN Document Server

    Zhavoronkov, N; Bregadiolli, B A; Nalin, M; Malomed, B A

    2011-01-01

    We demonstrate experimentally and support by a theoretical analysis an effect of asymmetric spectrum broadening, which results from doping of silver nanoparticles into a heavy-glass matrix, 90(0.5WO3-0.3SbPO4-0.2PbO)-10AgCl. The strong dispersion of the effective nonlinear coefficient of the composite significantly influences the spectral broadening via the self-phase modulation, and leads to a blue upshift of the spectrum. Further extension of the spectrum towards shorter wavelengths is suppressed by a growing loss caused by the plasmon resonance in the silver particles. The red-edge spectral broadening is dominated by the stimulated Raman Scattering.

  13. Catalytic properties of mesoporous Al–La–Mn oxides prepared via spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Goun; Jung, Kyeong Youl; Lee, Choul-Ho [Department of Chemical Engineering, Kongju National University, Cheonan 330-717 (Korea, Republic of); Han, Jeong-Sik; Jeong, Byung-Hun [Agency for Defense Development, Daejeon 305-152 (Korea, Republic of); Park, Young-Kwon [School of Environmental Engineering, University of Seoul, Seoul 130-743 (Korea, Republic of); Jeon, Jong-Ki, E-mail: jkjeon@kongju.ac.kr [Department of Chemical Engineering, Kongju National University, Cheonan 330-717 (Korea, Republic of)

    2016-10-15

    Highlights: • Al–La–Mn oxides were prepared using spray pyrolysis. • Al–La–Mn oxides exhibit large and uniform pore sizes. • Mesoporous Al–La–Mn oxides were compared with those prepared by conventional precipitation. • Mesoporous Al–La–Mn oxides show superior activity in decomposition of hydrogen peroxide. - Abstract: Mesoporous Al–La–Mn oxides are prepared via spray pyrolysis and are applied to the catalytic decomposition of hydrogen peroxide. The characteristics of the mesoporous Al–La–Mn oxides are examined using N{sub 2} adsorption, X-ray diffraction, and X-ray fluorescence measurements. The surface area and pore size of the Al–La–Mn oxides prepared via spray pyrolysis are larger than those of the Al–La–Mn oxides prepared using a precipitation method. The catalytic performance of the materials during the decomposition of hydrogen peroxide is examined in a pulse-injection reactor. It is confirmed that the mesoporous Al–La–Mn oxides prepared via spray pyrolysis exhibit higher catalytic activity and stability in the decomposition of hydrogen peroxide than Al–La–Mn oxides prepared using a conventional precipitation method.

  14. 化学镀银黏胶纤维的制备及性能分析%Preparation and property analysis of silver electroless plated viscose fibre

    Institute of Scientific and Technical Information of China (English)

    刘俊丽; 林红; 陈宇岳

    2013-01-01

    Conductive viscose fibres were prepared by electroless plating of silver .Its characteristics such as surface morphology , chemical composition , crystal structure , structural change and thermal property were analyzed by using SEM , EDS, XRD, FTIR and TG.The mechanical properties and surface resistance of the silver plated viscose fibres were also measured .The results show that the structure and properties of viscose fibers have no obvious change after silver plating , and the silver plated on the surface is compact , combined with good fastness .%采用化学镀银方法,在黏胶纤维表面沉积银金属层,制备导电黏胶纤维。分别借助SEM、EDS、XRD、FTIR、TG等对纤维的表面形貌、镀层成分、结晶情况、结构变化、热性能进行分析,并测试纤维的力学性能和表面电阻。结果表明:镀银后黏胶纤维的结构和性能变化不大,表面覆盖的银单质层比较致密,且结合牢度好。

  15. PREPARATION OF TITANIA SOL-GEL COATINGS CONTAINING SILVER IN VARIOUS FORMS AND MEASURING OF THEIR BACTERICIDAL EFFECTS AGAINST E. COLI

    Directory of Open Access Journals (Sweden)

    Diana Horkavcova

    2015-09-01

    Full Text Available The work describes titania coatings containing various forms of silver applied on a titanium substrate by a dip-coating sol-gel technique. Silver was added into the basic titania sol in form of colloid particles of Ag, crystals of AgNO3, particles of AgI, particles of Ag3PO4 and Ag3PO4 developed in situ (in the sol by reaction of AgNO3 with added calcium phosphate (brushite or monetite. Mechanically and chemically treated titanium substrates were dipped at a constant rate into individual types of sols. Subsequently, they were slowly fired. The fired coatings contained microcracks. All over the surface there were evenly distributed spherical nanoparticles of silver (Ag, AgNO3 or microcrystals of AgI and Ag3PO4. The prepared coatings were tested under static conditions for their bactericidal effects against gram-negative bacteria Escherichia coli (E. coli. The coated substrates were immersed into a suspension of E. coli in physiological solution for 24 and 4 hours. The basic titania coatings with no silver demonstrated no bactericidal properties. Very good bactericidal effect against E. coli in both types of bactericidal test showed the titania coatings with AgNO3, Ag3PO4 crystals and Ag3PO4 developed in situ.

  16. Silver nanoparticle induced cytotoxicity, oxidative stress, and DNA damage in CHO cells

    Energy Technology Data Exchange (ETDEWEB)

    Awasthi, Kumud Kant [University of Rajasthan, Department of Zoology (India); Awasthi, Anjali; Kumar, Narender; Roy, Partha [Indian Institute of Technology Roorkee, Department of Biotechnology (India); Awasthi, Kamlendra, E-mail: kamlendra.awasthi@gmail.com [Malaviya National Institute of Technology, Department of Physics (India); John, P. J., E-mail: placheriljohn@yahoo.com [University of Rajasthan, Department of Zoology (India)

    2013-09-15

    Silver nanoparticles (Ag NPs) are being used increasingly in wound dressings, catheters, and in various household products due to their antimicrobial activity. The present study reports the toxicity evaluation of synthesized and well characterized Ag NPs using Chinese hamster ovary (CHO) cells. The UV-Vis spectroscopy reveals the formation of silver nanoparticles by exhibiting the typical surface plasmon absorption maxima at 408-410 nm. Transmission electron microscopy (TEM) reveals that the average diameter of silver nanoparticles is about 5.0 {+-} 1.0 nm and that they have spherical shape. Cell visibility and cell viability percentage show dose-dependent cellular toxicity of Ag NPs. The half maximal inhibitory concentration (IC{sub 50}) for CHO cells is 68.0 {+-} 2.65 {mu}g/ml after 24 h Ag NPs exposure. Toxicity evaluations, including cellular morphology, mitochondrial function (MTT assay), reactive oxygen species (ROS), and DNA fragmentation assay (Ladder pattern) were assessed in unexposed CHO cells (control) and the cells exposed to Ag NPs concentrations of 15, 30, and 60 {mu}g/ml for 24 h. The findings may assist in the designing of Ag NPs for various applications and provide insights into their toxicity.

  17. Silver nanoparticle induced cytotoxicity, oxidative stress, and DNA damage in CHO cells

    Science.gov (United States)

    Awasthi, Kumud Kant; Awasthi, Anjali; Kumar, Narender; Roy, Partha; Awasthi, Kamlendra; John, P. J.

    2013-09-01

    Silver nanoparticles (Ag NPs) are being used increasingly in wound dressings, catheters, and in various household products due to their antimicrobial activity. The present study reports the toxicity evaluation of synthesized and well characterized Ag NPs using Chinese hamster ovary (CHO) cells. The UV-Vis spectroscopy reveals the formation of silver nanoparticles by exhibiting the typical surface plasmon absorption maxima at 408-410 nm. Transmission electron microscopy (TEM) reveals that the average diameter of silver nanoparticles is about 5.0 ± 1.0 nm and that they have spherical shape. Cell visibility and cell viability percentage show dose-dependent cellular toxicity of Ag NPs. The half maximal inhibitory concentration (IC50) for CHO cells is 68.0 ± 2.65 μg/ml after 24 h Ag NPs exposure. Toxicity evaluations, including cellular morphology, mitochondrial function (MTT assay), reactive oxygen species (ROS), and DNA fragmentation assay (Ladder pattern) were assessed in unexposed CHO cells (control) and the cells exposed to Ag NPs concentrations of 15, 30, and 60 μg/ml for 24 h. The findings may assist in the designing of Ag NPs for various applications and provide insights into their toxicity.

  18. Adding Processes of Silver Solution and the Deposit Process of Silver Coating during Reduction Preparation of Silver-Coated Copper Powders%还原法制备银包铜粉主盐添加工艺及镀层沉积过程研究